[CodeGen] Complete machine pass and ABI lowering infrastructure

25 files changed, 10628 insertions, 0 deletions

diff --git a/.clang-tidy b/.clang-tidy
index dcad2ae..514bd75 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -7,6 +7,7 @@ Checks: >
   bugprone-*,
   -bugprone-easily-swappable-parameters,
   performance-*,
+  -performance-enum-size,
   portability-*,
   llvm-header-guard,
   llvm-namespace-comment,
@@ -47,6 +48,8 @@ CheckOptions:
   - { key: readability-identifier-naming.ConstexprVariableCase,     value: CamelCase  }
   - { key: readability-identifier-naming.ClassConstantCase,         value: CamelCase  }
   - { key: readability-identifier-naming.EnumConstantCase,          value: CamelCase  }
+  # Preserve canonical protocol, opcode, ABI, and ISA spellings.
+  - { key: readability-identifier-naming.EnumConstantIgnoredRegexp, value: '^([A-Z][A-Z0-9_]*|Pseudo[A-Z0-9_]+)$' }
   - { key: readability-identifier-naming.MacroDefinitionCase,       value: UPPER_CASE }
   # Other
   - { key: readability-identifier-naming.IgnoreMainLikeFunctions,                  value: 1 }
diff --git a/backend/.clang-tidy b/backend/.clang-tidy
index a0e18ce..73a225a 100644
--- a/backend/.clang-tidy
+++ b/backend/.clang-tidy
@@ -7,6 +7,7 @@ Checks: >
   bugprone-*,
   -bugprone-easily-swappable-parameters,
   performance-*,
+  -performance-enum-size,
   portability-*,
   llvm-header-guard,
   llvm-namespace-comment,
@@ -43,6 +44,8 @@ CheckOptions:
   - { key: readability-identifier-naming.ConstexprVariableCase,     value: CamelCase  }
   - { key: readability-identifier-naming.ClassConstantCase,         value: CamelCase  }
   - { key: readability-identifier-naming.EnumConstantCase,          value: CamelCase  }
+  # Preserve canonical protocol, opcode, ABI, and ISA spellings.
+  - { key: readability-identifier-naming.EnumConstantIgnoredRegexp, value: '^([A-Z][A-Z0-9_]*|Pseudo[A-Z0-9_]+)$' }
   - { key: readability-identifier-naming.MacroDefinitionCase,       value: UPPER_CASE }
   - { key: readability-identifier-naming.IgnoreMainLikeFunctions,   value: 1          }
   - { key: readability-redundant-member-init.IgnoreBaseInCopyConstructors, value: 1    }
diff --git a/backend/include/rcc/CodeGen/GenericOpcode.def b/backend/include/rcc/CodeGen/GenericOpcode.def
new file mode 100644
index 0000000..8caaf7b
--- /dev/null
+++ b/backend/include/rcc/CodeGen/GenericOpcode.def
@@ -0,0 +1,336 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+// This file is intentionally included multiple times. Define
+// RCC_CORE_OPCODE and RCC_GENERIC_OPCODE before including it.
+
+RCC_CORE_OPCODE(PHI)
+RCC_CORE_OPCODE(INLINEASM)
+RCC_CORE_OPCODE(INLINEASM_BR)
+RCC_CORE_OPCODE(CFI_INSTRUCTION)
+RCC_CORE_OPCODE(EH_LABEL)
+RCC_CORE_OPCODE(GC_LABEL)
+RCC_CORE_OPCODE(ANNOTATION_LABEL)
+RCC_CORE_OPCODE(KILL)
+RCC_CORE_OPCODE(EXTRACT_SUBREG)
+RCC_CORE_OPCODE(INSERT_SUBREG)
+RCC_CORE_OPCODE(IMPLICIT_DEF)
+RCC_CORE_OPCODE(INIT_UNDEF)
+RCC_CORE_OPCODE(SUBREG_TO_REG)
+RCC_CORE_OPCODE(COPY_TO_REGCLASS)
+RCC_CORE_OPCODE(DBG_VALUE)
+RCC_CORE_OPCODE(DBG_VALUE_LIST)
+RCC_CORE_OPCODE(DBG_INSTR_REF)
+RCC_CORE_OPCODE(DBG_PHI)
+RCC_CORE_OPCODE(DBG_LABEL)
+RCC_CORE_OPCODE(REG_SEQUENCE)
+RCC_CORE_OPCODE(COPY)
+RCC_CORE_OPCODE(COPY_LANEMASK)
+RCC_CORE_OPCODE(BUNDLE)
+RCC_CORE_OPCODE(LIFETIME_START)
+RCC_CORE_OPCODE(LIFETIME_END)
+RCC_CORE_OPCODE(PSEUDO_PROBE)
+RCC_CORE_OPCODE(ARITH_FENCE)
+RCC_CORE_OPCODE(STACKMAP)
+RCC_CORE_OPCODE(FENTRY_CALL)
+RCC_CORE_OPCODE(PATCHPOINT)
+RCC_CORE_OPCODE(LOAD_STACK_GUARD)
+RCC_CORE_OPCODE(PREALLOCATED_SETUP)
+RCC_CORE_OPCODE(PREALLOCATED_ARG)
+RCC_CORE_OPCODE(STATEPOINT)
+RCC_CORE_OPCODE(LOCAL_ESCAPE)
+RCC_CORE_OPCODE(FAULTING_OP)
+RCC_CORE_OPCODE(PATCHABLE_OP)
+RCC_CORE_OPCODE(PATCHABLE_FUNCTION_ENTER)
+RCC_CORE_OPCODE(PATCHABLE_RET)
+RCC_CORE_OPCODE(PATCHABLE_FUNCTION_EXIT)
+RCC_CORE_OPCODE(PATCHABLE_TAIL_CALL)
+RCC_CORE_OPCODE(PATCHABLE_EVENT_CALL)
+RCC_CORE_OPCODE(PATCHABLE_TYPED_EVENT_CALL)
+RCC_CORE_OPCODE(ICALL_BRANCH_FUNNEL)
+RCC_CORE_OPCODE(FAKE_USE)
+RCC_CORE_OPCODE(MEMBARRIER)
+RCC_CORE_OPCODE(JUMP_TABLE_DEBUG_INFO)
+RCC_CORE_OPCODE(RELOC_NONE)
+RCC_CORE_OPCODE(CONVERGENCECTRL_ENTRY)
+RCC_CORE_OPCODE(CONVERGENCECTRL_ANCHOR)
+RCC_CORE_OPCODE(CONVERGENCECTRL_LOOP)
+RCC_CORE_OPCODE(CONVERGENCECTRL_GLUE)
+
+RCC_GENERIC_OPCODE(G_ASSERT_SEXT)
+RCC_GENERIC_OPCODE(G_ASSERT_ZEXT)
+RCC_GENERIC_OPCODE(G_ASSERT_ALIGN)
+RCC_GENERIC_OPCODE(G_ADD)
+RCC_GENERIC_OPCODE(G_SUB)
+RCC_GENERIC_OPCODE(G_MUL)
+RCC_GENERIC_OPCODE(G_SDIV)
+RCC_GENERIC_OPCODE(G_UDIV)
+RCC_GENERIC_OPCODE(G_SREM)
+RCC_GENERIC_OPCODE(G_UREM)
+RCC_GENERIC_OPCODE(G_SDIVREM)
+RCC_GENERIC_OPCODE(G_UDIVREM)
+RCC_GENERIC_OPCODE(G_AND)
+RCC_GENERIC_OPCODE(G_OR)
+RCC_GENERIC_OPCODE(G_XOR)
+RCC_GENERIC_OPCODE(G_ABDS)
+RCC_GENERIC_OPCODE(G_ABDU)
+RCC_GENERIC_OPCODE(G_UAVGFLOOR)
+RCC_GENERIC_OPCODE(G_UAVGCEIL)
+RCC_GENERIC_OPCODE(G_SAVGFLOOR)
+RCC_GENERIC_OPCODE(G_SAVGCEIL)
+RCC_GENERIC_OPCODE(G_IMPLICIT_DEF)
+RCC_GENERIC_OPCODE(G_PHI)
+RCC_GENERIC_OPCODE(G_FRAME_INDEX)
+RCC_GENERIC_OPCODE(G_GLOBAL_VALUE)
+RCC_GENERIC_OPCODE(G_PTRAUTH_GLOBAL_VALUE)
+RCC_GENERIC_OPCODE(G_CONSTANT_POOL)
+RCC_GENERIC_OPCODE(G_EXTRACT)
+RCC_GENERIC_OPCODE(G_UNMERGE_VALUES)
+RCC_GENERIC_OPCODE(G_INSERT)
+RCC_GENERIC_OPCODE(G_MERGE_VALUES)
+RCC_GENERIC_OPCODE(G_BUILD_VECTOR)
+RCC_GENERIC_OPCODE(G_BUILD_VECTOR_TRUNC)
+RCC_GENERIC_OPCODE(G_CONCAT_VECTORS)
+RCC_GENERIC_OPCODE(G_PTRTOINT)
+RCC_GENERIC_OPCODE(G_INTTOPTR)
+RCC_GENERIC_OPCODE(G_BITCAST)
+RCC_GENERIC_OPCODE(G_FREEZE)
+RCC_GENERIC_OPCODE(G_CONSTANT_FOLD_BARRIER)
+RCC_GENERIC_OPCODE(G_INTRINSIC_FPTRUNC_ROUND)
+RCC_GENERIC_OPCODE(G_INTRINSIC_TRUNC)
+RCC_GENERIC_OPCODE(G_INTRINSIC_ROUND)
+RCC_GENERIC_OPCODE(G_INTRINSIC_LRINT)
+RCC_GENERIC_OPCODE(G_INTRINSIC_LLRINT)
+RCC_GENERIC_OPCODE(G_INTRINSIC_ROUNDEVEN)
+RCC_GENERIC_OPCODE(G_READCYCLECOUNTER)
+RCC_GENERIC_OPCODE(G_READSTEADYCOUNTER)
+RCC_GENERIC_OPCODE(G_LOAD)
+RCC_GENERIC_OPCODE(G_SEXTLOAD)
+RCC_GENERIC_OPCODE(G_ZEXTLOAD)
+RCC_GENERIC_OPCODE(G_FPEXTLOAD)
+RCC_GENERIC_OPCODE(G_INDEXED_LOAD)
+RCC_GENERIC_OPCODE(G_INDEXED_SEXTLOAD)
+RCC_GENERIC_OPCODE(G_INDEXED_ZEXTLOAD)
+RCC_GENERIC_OPCODE(G_STORE)
+RCC_GENERIC_OPCODE(G_FPTRUNCSTORE)
+RCC_GENERIC_OPCODE(G_INDEXED_STORE)
+RCC_GENERIC_OPCODE(G_ATOMIC_CMPXCHG_WITH_SUCCESS)
+RCC_GENERIC_OPCODE(G_ATOMIC_CMPXCHG)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_XCHG)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_ADD)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_SUB)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_AND)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_NAND)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_OR)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_XOR)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_MAX)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_MIN)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_UMAX)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_UMIN)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_FADD)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_FSUB)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_FMAX)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_FMIN)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_FMAXIMUM)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_FMINIMUM)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_FMAXIMUMNUM)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_FMINIMUMNUM)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_UINC_WRAP)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_UDEC_WRAP)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_USUB_COND)
+RCC_GENERIC_OPCODE(G_ATOMICRMW_USUB_SAT)
+RCC_GENERIC_OPCODE(G_FENCE)
+RCC_GENERIC_OPCODE(G_PREFETCH)
+RCC_GENERIC_OPCODE(G_BRCOND)
+RCC_GENERIC_OPCODE(G_BRINDIRECT)
+RCC_GENERIC_OPCODE(G_INVOKE_REGION_START)
+RCC_GENERIC_OPCODE(G_INTRINSIC)
+RCC_GENERIC_OPCODE(G_INTRINSIC_W_SIDE_EFFECTS)
+RCC_GENERIC_OPCODE(G_INTRINSIC_CONVERGENT)
+RCC_GENERIC_OPCODE(G_INTRINSIC_CONVERGENT_W_SIDE_EFFECTS)
+RCC_GENERIC_OPCODE(G_ANYEXT)
+RCC_GENERIC_OPCODE(G_TRUNC)
+RCC_GENERIC_OPCODE(G_TRUNC_SSAT_S)
+RCC_GENERIC_OPCODE(G_TRUNC_SSAT_U)
+RCC_GENERIC_OPCODE(G_TRUNC_USAT_U)
+RCC_GENERIC_OPCODE(G_CONSTANT)
+RCC_GENERIC_OPCODE(G_FCONSTANT)
+RCC_GENERIC_OPCODE(G_VASTART)
+RCC_GENERIC_OPCODE(G_VAARG)
+RCC_GENERIC_OPCODE(G_SEXT)
+RCC_GENERIC_OPCODE(G_SEXT_INREG)
+RCC_GENERIC_OPCODE(G_ZEXT)
+RCC_GENERIC_OPCODE(G_SHL)
+RCC_GENERIC_OPCODE(G_LSHR)
+RCC_GENERIC_OPCODE(G_ASHR)
+RCC_GENERIC_OPCODE(G_FSHL)
+RCC_GENERIC_OPCODE(G_FSHR)
+RCC_GENERIC_OPCODE(G_ROTR)
+RCC_GENERIC_OPCODE(G_ROTL)
+RCC_GENERIC_OPCODE(G_ICMP)
+RCC_GENERIC_OPCODE(G_FCMP)
+RCC_GENERIC_OPCODE(G_SCMP)
+RCC_GENERIC_OPCODE(G_UCMP)
+RCC_GENERIC_OPCODE(G_SELECT)
+RCC_GENERIC_OPCODE(G_UADDO)
+RCC_GENERIC_OPCODE(G_UADDE)
+RCC_GENERIC_OPCODE(G_USUBO)
+RCC_GENERIC_OPCODE(G_USUBE)
+RCC_GENERIC_OPCODE(G_SADDO)
+RCC_GENERIC_OPCODE(G_SADDE)
+RCC_GENERIC_OPCODE(G_SSUBO)
+RCC_GENERIC_OPCODE(G_SSUBE)
+RCC_GENERIC_OPCODE(G_UMULO)
+RCC_GENERIC_OPCODE(G_SMULO)
+RCC_GENERIC_OPCODE(G_UMULH)
+RCC_GENERIC_OPCODE(G_SMULH)
+RCC_GENERIC_OPCODE(G_UADDSAT)
+RCC_GENERIC_OPCODE(G_SADDSAT)
+RCC_GENERIC_OPCODE(G_USUBSAT)
+RCC_GENERIC_OPCODE(G_SSUBSAT)
+RCC_GENERIC_OPCODE(G_USHLSAT)
+RCC_GENERIC_OPCODE(G_SSHLSAT)
+RCC_GENERIC_OPCODE(G_SMULFIX)
+RCC_GENERIC_OPCODE(G_UMULFIX)
+RCC_GENERIC_OPCODE(G_SMULFIXSAT)
+RCC_GENERIC_OPCODE(G_UMULFIXSAT)
+RCC_GENERIC_OPCODE(G_SDIVFIX)
+RCC_GENERIC_OPCODE(G_UDIVFIX)
+RCC_GENERIC_OPCODE(G_SDIVFIXSAT)
+RCC_GENERIC_OPCODE(G_UDIVFIXSAT)
+RCC_GENERIC_OPCODE(G_FADD)
+RCC_GENERIC_OPCODE(G_FSUB)
+RCC_GENERIC_OPCODE(G_FMUL)
+RCC_GENERIC_OPCODE(G_FMA)
+RCC_GENERIC_OPCODE(G_FMAD)
+RCC_GENERIC_OPCODE(G_FDIV)
+RCC_GENERIC_OPCODE(G_FREM)
+RCC_GENERIC_OPCODE(G_FMODF)
+RCC_GENERIC_OPCODE(G_FPOW)
+RCC_GENERIC_OPCODE(G_FPOWI)
+RCC_GENERIC_OPCODE(G_FEXP)
+RCC_GENERIC_OPCODE(G_FEXP2)
+RCC_GENERIC_OPCODE(G_FEXP10)
+RCC_GENERIC_OPCODE(G_FLOG)
+RCC_GENERIC_OPCODE(G_FLOG2)
+RCC_GENERIC_OPCODE(G_FLOG10)
+RCC_GENERIC_OPCODE(G_FLDEXP)
+RCC_GENERIC_OPCODE(G_FFREXP)
+RCC_GENERIC_OPCODE(G_FNEG)
+RCC_GENERIC_OPCODE(G_FPEXT)
+RCC_GENERIC_OPCODE(G_FPTRUNC)
+RCC_GENERIC_OPCODE(G_FPTOSI)
+RCC_GENERIC_OPCODE(G_FPTOUI)
+RCC_GENERIC_OPCODE(G_SITOFP)
+RCC_GENERIC_OPCODE(G_UITOFP)
+RCC_GENERIC_OPCODE(G_FPTOSI_SAT)
+RCC_GENERIC_OPCODE(G_FPTOUI_SAT)
+RCC_GENERIC_OPCODE(G_FABS)
+RCC_GENERIC_OPCODE(G_FCOPYSIGN)
+RCC_GENERIC_OPCODE(G_IS_FPCLASS)
+RCC_GENERIC_OPCODE(G_FCANONICALIZE)
+RCC_GENERIC_OPCODE(G_FMINNUM)
+RCC_GENERIC_OPCODE(G_FMAXNUM)
+RCC_GENERIC_OPCODE(G_FMINNUM_IEEE)
+RCC_GENERIC_OPCODE(G_FMAXNUM_IEEE)
+RCC_GENERIC_OPCODE(G_FMINIMUM)
+RCC_GENERIC_OPCODE(G_FMAXIMUM)
+RCC_GENERIC_OPCODE(G_FMINIMUMNUM)
+RCC_GENERIC_OPCODE(G_FMAXIMUMNUM)
+RCC_GENERIC_OPCODE(G_GET_FPENV)
+RCC_GENERIC_OPCODE(G_SET_FPENV)
+RCC_GENERIC_OPCODE(G_RESET_FPENV)
+RCC_GENERIC_OPCODE(G_GET_FPMODE)
+RCC_GENERIC_OPCODE(G_SET_FPMODE)
+RCC_GENERIC_OPCODE(G_RESET_FPMODE)
+RCC_GENERIC_OPCODE(G_GET_ROUNDING)
+RCC_GENERIC_OPCODE(G_SET_ROUNDING)
+RCC_GENERIC_OPCODE(G_PTR_ADD)
+RCC_GENERIC_OPCODE(G_PTRMASK)
+RCC_GENERIC_OPCODE(G_SMIN)
+RCC_GENERIC_OPCODE(G_SMAX)
+RCC_GENERIC_OPCODE(G_UMIN)
+RCC_GENERIC_OPCODE(G_UMAX)
+RCC_GENERIC_OPCODE(G_ABS)
+RCC_GENERIC_OPCODE(G_LROUND)
+RCC_GENERIC_OPCODE(G_LLROUND)
+RCC_GENERIC_OPCODE(G_BR)
+RCC_GENERIC_OPCODE(G_BRJT)
+RCC_GENERIC_OPCODE(G_VSCALE)
+RCC_GENERIC_OPCODE(G_INSERT_SUBVECTOR)
+RCC_GENERIC_OPCODE(G_EXTRACT_SUBVECTOR)
+RCC_GENERIC_OPCODE(G_INSERT_VECTOR_ELT)
+RCC_GENERIC_OPCODE(G_EXTRACT_VECTOR_ELT)
+RCC_GENERIC_OPCODE(G_SHUFFLE_VECTOR)
+RCC_GENERIC_OPCODE(G_SPLAT_VECTOR)
+RCC_GENERIC_OPCODE(G_STEP_VECTOR)
+RCC_GENERIC_OPCODE(G_VECTOR_COMPRESS)
+RCC_GENERIC_OPCODE(G_CTTZ)
+RCC_GENERIC_OPCODE(G_CTTZ_ZERO_POISON)
+RCC_GENERIC_OPCODE(G_CTLZ)
+RCC_GENERIC_OPCODE(G_CTLZ_ZERO_POISON)
+RCC_GENERIC_OPCODE(G_CTLS)
+RCC_GENERIC_OPCODE(G_CTPOP)
+RCC_GENERIC_OPCODE(G_BSWAP)
+RCC_GENERIC_OPCODE(G_BITREVERSE)
+RCC_GENERIC_OPCODE(G_CLMUL)
+RCC_GENERIC_OPCODE(G_FCEIL)
+RCC_GENERIC_OPCODE(G_FCOS)
+RCC_GENERIC_OPCODE(G_FSIN)
+RCC_GENERIC_OPCODE(G_FSINCOS)
+RCC_GENERIC_OPCODE(G_FTAN)
+RCC_GENERIC_OPCODE(G_FACOS)
+RCC_GENERIC_OPCODE(G_FASIN)
+RCC_GENERIC_OPCODE(G_FATAN)
+RCC_GENERIC_OPCODE(G_FATAN2)
+RCC_GENERIC_OPCODE(G_FCOSH)
+RCC_GENERIC_OPCODE(G_FSINH)
+RCC_GENERIC_OPCODE(G_FTANH)
+RCC_GENERIC_OPCODE(G_FSQRT)
+RCC_GENERIC_OPCODE(G_FFLOOR)
+RCC_GENERIC_OPCODE(G_FRINT)
+RCC_GENERIC_OPCODE(G_FNEARBYINT)
+RCC_GENERIC_OPCODE(G_ADDRSPACE_CAST)
+RCC_GENERIC_OPCODE(G_BLOCK_ADDR)
+RCC_GENERIC_OPCODE(G_JUMP_TABLE)
+RCC_GENERIC_OPCODE(G_DYN_STACKALLOC)
+RCC_GENERIC_OPCODE(G_STACKSAVE)
+RCC_GENERIC_OPCODE(G_STACKRESTORE)
+RCC_GENERIC_OPCODE(G_STRICT_FADD)
+RCC_GENERIC_OPCODE(G_STRICT_FSUB)
+RCC_GENERIC_OPCODE(G_STRICT_FMUL)
+RCC_GENERIC_OPCODE(G_STRICT_FDIV)
+RCC_GENERIC_OPCODE(G_STRICT_FREM)
+RCC_GENERIC_OPCODE(G_STRICT_FMA)
+RCC_GENERIC_OPCODE(G_STRICT_FSQRT)
+RCC_GENERIC_OPCODE(G_STRICT_FLDEXP)
+RCC_GENERIC_OPCODE(G_STRICT_FCMP)
+RCC_GENERIC_OPCODE(G_STRICT_FCMPS)
+RCC_GENERIC_OPCODE(G_READ_REGISTER)
+RCC_GENERIC_OPCODE(G_WRITE_REGISTER)
+RCC_GENERIC_OPCODE(G_MEMCPY)
+RCC_GENERIC_OPCODE(G_MEMCPY_INLINE)
+RCC_GENERIC_OPCODE(G_MEMMOVE)
+RCC_GENERIC_OPCODE(G_MEMSET)
+RCC_GENERIC_OPCODE(G_BZERO)
+RCC_GENERIC_OPCODE(G_TRAP)
+RCC_GENERIC_OPCODE(G_DEBUGTRAP)
+RCC_GENERIC_OPCODE(G_UBSANTRAP)
+RCC_GENERIC_OPCODE(G_VECREDUCE_SEQ_FADD)
+RCC_GENERIC_OPCODE(G_VECREDUCE_SEQ_FMUL)
+RCC_GENERIC_OPCODE(G_VECREDUCE_FADD)
+RCC_GENERIC_OPCODE(G_VECREDUCE_FMUL)
+RCC_GENERIC_OPCODE(G_VECREDUCE_FMAX)
+RCC_GENERIC_OPCODE(G_VECREDUCE_FMIN)
+RCC_GENERIC_OPCODE(G_VECREDUCE_FMAXIMUM)
+RCC_GENERIC_OPCODE(G_VECREDUCE_FMINIMUM)
+RCC_GENERIC_OPCODE(G_VECREDUCE_ADD)
+RCC_GENERIC_OPCODE(G_VECREDUCE_MUL)
+RCC_GENERIC_OPCODE(G_VECREDUCE_AND)
+RCC_GENERIC_OPCODE(G_VECREDUCE_OR)
+RCC_GENERIC_OPCODE(G_VECREDUCE_XOR)
+RCC_GENERIC_OPCODE(G_VECREDUCE_SMAX)
+RCC_GENERIC_OPCODE(G_VECREDUCE_SMIN)
+RCC_GENERIC_OPCODE(G_VECREDUCE_UMAX)
+RCC_GENERIC_OPCODE(G_VECREDUCE_UMIN)
+RCC_GENERIC_OPCODE(G_SBFX)
+RCC_GENERIC_OPCODE(G_UBFX)
diff --git a/backend/include/rcc/CodeGen/GenericOpcodes.h b/backend/include/rcc/CodeGen/GenericOpcodes.h
new file mode 100644
index 0000000..5a46e21
--- /dev/null
+++ b/backend/include/rcc/CodeGen/GenericOpcodes.h
@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef RCC_CODEGEN_GENERICOPCODES_H
+#define RCC_CODEGEN_GENERICOPCODES_H
+
+#include "rcc/CodeGen/InstructionDescriptor.h"
+
+#include <cstdint>
+#include <span>
+#include <string_view>
+#include <vector>
+
+namespace rcc {
+
+// Target-independent values are build-local. Target tables start at 1024 and
+// are appended to this set when a target description is constructed.
+enum class GenericOpcode : std::uint32_t {
+  Invalid,
+#define RCC_CORE_OPCODE(Name) Name,
+#define RCC_GENERIC_OPCODE(Name)
+#include "rcc/CodeGen/GenericOpcode.def"
+#undef RCC_GENERIC_OPCODE
+#undef RCC_CORE_OPCODE
+  CORE_PSEUDO_END,
+
+#define RCC_CORE_OPCODE(Name)
+#define RCC_GENERIC_OPCODE(Name) Name,
+#include "rcc/CodeGen/GenericOpcode.def"
+#undef RCC_GENERIC_OPCODE
+#undef RCC_CORE_OPCODE
+  G_GENERIC_END,
+};
+
+[[nodiscard]] constexpr Opcode opcode(GenericOpcode Generic) noexcept {
+  return Opcode::fromValue(static_cast<std::uint32_t>(Generic));
+}
+
+[[nodiscard]] constexpr bool isGenericOpcode(Opcode Value) noexcept {
+  return Value.value() >= static_cast<std::uint32_t>(GenericOpcode::G_ASSERT_SEXT) &&
+         Value.value() < static_cast<std::uint32_t>(GenericOpcode::G_GENERIC_END);
+}
+
+[[nodiscard]] constexpr bool isCorePseudoOpcode(Opcode Value) noexcept {
+  return Value.value() >= static_cast<std::uint32_t>(GenericOpcode::PHI) &&
+         Value.value() < static_cast<std::uint32_t>(GenericOpcode::CORE_PSEUDO_END);
+}
+
+inline constexpr std::size_t CorePseudoOpcodeCount =
+    static_cast<std::size_t>(GenericOpcode::CORE_PSEUDO_END) -
+    static_cast<std::size_t>(GenericOpcode::PHI);
+
+inline constexpr std::size_t GenericOpcodeCount =
+    static_cast<std::size_t>(GenericOpcode::G_GENERIC_END) -
+    static_cast<std::size_t>(GenericOpcode::G_ASSERT_SEXT);
+
+[[nodiscard]] std::string_view getGenericOpcodeName(GenericOpcode OpcodeValue) noexcept;
+
+[[nodiscard]] std::span<const InstructionDescriptor> genericInstructionDescriptors() noexcept;
+
+[[nodiscard]] std::span<const ImmediatePredicate> genericImmediatePredicates() noexcept;
+
+[[nodiscard]] Expected<void>
+appendGenericInstructionInfo(std::vector<InstructionDescriptor> &Descriptors,
+                             std::vector<ImmediatePredicate> &Predicates);
+
+} // namespace rcc
+
+#endif // RCC_CODEGEN_GENERICOPCODES_H
diff --git a/backend/include/rcc/CodeGen/MachineAnalyses.h b/backend/include/rcc/CodeGen/MachineAnalyses.h
new file mode 100644
index 0000000..eda550d
--- /dev/null
+++ b/backend/include/rcc/CodeGen/MachineAnalyses.h
@@ -0,0 +1,244 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef RCC_CODEGEN_MACHINEANALYSES_H
+#define RCC_CODEGEN_MACHINEANALYSES_H
+
+#include "rcc/CodeGen/MachineBasicBlock.h"
+#include "rcc/CodeGen/MachineIRTypes.h"
+#include "rcc/CodeGen/MachinePass.h"
+#include "rcc/CodeGen/StableID.h"
+#include "rcc/Support/Error.h"
+
+#include <cstddef>
+#include <cstdint>
+#include <span>
+#include <string_view>
+#include <unordered_map>
+#include <unordered_set>
+#include <vector>
+
+namespace rcc {
+
+class MachineBasicBlock;
+class MachineFunction;
+class MachineInstr;
+class MachineMemOperand;
+class TargetDescription;
+
+class MachineDominatorTreeAnalysis final {
+public:
+  class Result final {
+  public:
+    [[nodiscard]] bool isReachable(const MachineBasicBlock &Block) const noexcept;
+    [[nodiscard]] bool dominates(const MachineBasicBlock &Dominator,
+                                 const MachineBasicBlock &Block) const noexcept;
+    [[nodiscard]] bool dominates(const MachineInstr &Dominator,
+                                 const MachineInstr &Instruction) const noexcept;
+    [[nodiscard]] const MachineBasicBlock *
+    immediateDominator(const MachineBasicBlock &Block) const noexcept;
+    [[nodiscard]] const MachineBasicBlock *
+    nearestCommonDominator(const MachineBasicBlock &Left,
+                           const MachineBasicBlock &Right) const noexcept;
+    [[nodiscard]] std::span<MachineBasicBlock *const> unreachableBlocks() const noexcept {
+      return UnreachableBlocks;
+    }
+
+    [[nodiscard]] Expected<void> updateAfterCFGChange(MachineFunction &Function);
+
+  private:
+    [[nodiscard]] Expected<void> build(MachineFunction &Function);
+
+    std::vector<MachineBasicBlock *> Blocks;
+    std::unordered_map<const MachineBasicBlock *, std::size_t> BlockToIndex;
+    std::vector<std::vector<bool>> Dominators;
+    std::vector<const MachineBasicBlock *> ImmediateDominators;
+    std::vector<bool> Reachable;
+    std::vector<MachineBasicBlock *> UnreachableBlocks;
+
+    friend class MachineDominatorTreeAnalysis;
+  };
+
+  [[nodiscard]] static constexpr std::string_view name() noexcept {
+    return "MachineDominatorTree";
+  }
+
+  [[nodiscard]] static Expected<Result>
+  run(MachineFunction &Function, const TargetDescription &Target, MachineAnalysisManager &Analyses);
+};
+
+struct MachineLoop final {
+  MachineBasicBlock *Header = nullptr;
+  std::vector<MachineBasicBlock *> Blocks;
+  std::vector<MachineBasicBlock *> Latches;
+  std::size_t Parent = static_cast<std::size_t>(-1);
+  std::vector<std::size_t> Children;
+  std::uint32_t Depth = 1;
+};
+
+struct IrreducibleMachineRegion final {
+  std::vector<MachineBasicBlock *> Blocks;
+  std::vector<MachineBasicBlock *> Entries;
+};
+
+class MachineLoopAnalysis final {
+public:
+  class Result final {
+  public:
+    [[nodiscard]] std::span<const MachineLoop> loops() const noexcept {
+      return Loops;
+    }
+    [[nodiscard]] std::span<const IrreducibleMachineRegion> irreducibleRegions() const noexcept {
+      return IrreducibleRegions;
+    }
+    [[nodiscard]] const MachineLoop *loopFor(const MachineBasicBlock &Block) const noexcept;
+    [[nodiscard]] std::uint32_t loopDepth(const MachineBasicBlock &Block) const noexcept;
+    [[nodiscard]] bool isIrreducible(const MachineBasicBlock &Block) const noexcept;
+
+  private:
+    std::vector<MachineLoop> Loops;
+    std::vector<IrreducibleMachineRegion> IrreducibleRegions;
+    std::unordered_map<const MachineBasicBlock *, std::size_t> InnermostLoop;
+    std::unordered_set<const MachineBasicBlock *> IrreducibleBlocks;
+
+    friend class MachineLoopAnalysis;
+  };
+
+  [[nodiscard]] static constexpr std::string_view name() noexcept {
+    return "MachineLoopInfo";
+  }
+
+  [[nodiscard]] static Expected<Result>
+  run(MachineFunction &Function, const TargetDescription &Target, MachineAnalysisManager &Analyses);
+};
+
+class MachineBranchProbabilityAnalysis final {
+public:
+  class Result final {
+  public:
+    [[nodiscard]] BranchProbability probability(const MachineBasicBlock &From,
+                                                const MachineBasicBlock &To) const noexcept;
+    [[nodiscard]] std::span<const MachineSuccessor>
+    successors(const MachineBasicBlock &Block) const noexcept;
+
+  private:
+    std::unordered_map<const MachineBasicBlock *, std::vector<MachineSuccessor>> Probabilities;
+
+    friend class MachineBranchProbabilityAnalysis;
+  };
+
+  [[nodiscard]] static constexpr std::string_view name() noexcept {
+    return "MachineBranchProbability";
+  }
+
+  [[nodiscard]] static Expected<Result>
+  run(MachineFunction &Function, const TargetDescription &Target, MachineAnalysisManager &Analyses);
+};
+
+class MachineBlockFrequencyAnalysis final {
+public:
+  static constexpr std::uint64_t EntryFrequency = std::uint64_t{1} << 32U;
+
+  class Result final {
+  public:
+    [[nodiscard]] std::uint64_t frequency(const MachineBasicBlock &Block) const noexcept;
+
+  private:
+    std::unordered_map<const MachineBasicBlock *, std::uint64_t> Frequencies;
+
+    friend class MachineBlockFrequencyAnalysis;
+  };
+
+  [[nodiscard]] static constexpr std::string_view name() noexcept {
+    return "MachineBlockFrequency";
+  }
+
+  [[nodiscard]] static Expected<Result>
+  run(MachineFunction &Function, const TargetDescription &Target, MachineAnalysisManager &Analyses);
+};
+
+enum class MachineAliasResult : std::uint8_t {
+  NoAlias,
+  MayAlias,
+  PartialAlias,
+  MustAlias,
+};
+
+class MachineAliasAnalysis final {
+public:
+  class Result final {
+  public:
+    [[nodiscard]] MachineAliasResult alias(const MachineMemOperand &Left,
+                                           const MachineMemOperand &Right) const noexcept;
+  };
+
+  [[nodiscard]] static constexpr std::string_view name() noexcept {
+    return "MachineAliasAnalysis";
+  }
+
+  [[nodiscard]] static Expected<Result>
+  run(MachineFunction &Function, const TargetDescription &Target, MachineAnalysisManager &Analyses);
+};
+
+enum class MachineMemoryDependencyKind : std::uint8_t {
+  Flow,
+  Anti,
+  Output,
+  Ordered,
+};
+
+struct MachineMemoryDependency final {
+  MachineInstrStableID Source;
+  MachineInstrStableID Destination;
+  MachineMemoryDependencyKind Kind = MachineMemoryDependencyKind::Ordered;
+};
+
+struct MachineMemoryDependenceRegion final {
+  const MachineBasicBlock *Block = nullptr;
+  std::vector<MachineInstrStableID> Instructions;
+};
+
+class MachineMemoryDependenceAnalysis final {
+public:
+  class Result final {
+  public:
+    [[nodiscard]] std::span<const MachineMemoryDependenceRegion> regions() const noexcept {
+      return Regions;
+    }
+    [[nodiscard]] const MachineMemoryDependenceRegion *
+    regionFor(const MachineBasicBlock &Block) const noexcept;
+    [[nodiscard]] std::span<const MachineMemoryDependency>
+    dependencies(const MachineBasicBlock &Block) const noexcept;
+    [[nodiscard]] std::span<const MachineMemoryDependency>
+    dependencies(const MachineInstr &Instruction) const noexcept;
+    [[nodiscard]] std::span<const MachineMemoryDependency> allDependencies() const noexcept {
+      return Dependencies;
+    }
+
+  private:
+    struct Range final {
+      std::size_t Begin = 0;
+      std::size_t Size = 0;
+    };
+
+    std::vector<MachineMemoryDependency> Dependencies;
+    std::vector<MachineMemoryDependenceRegion> Regions;
+    std::unordered_map<const MachineBasicBlock *, std::size_t> BlockToRegion;
+    std::unordered_map<const MachineBasicBlock *, Range> BlockRanges;
+    std::unordered_map<MachineInstrStableID, Range> DestinationRanges;
+
+    friend class MachineMemoryDependenceAnalysis;
+  };
+
+  [[nodiscard]] static constexpr std::string_view name() noexcept {
+    return "MachineMemoryDependence";
+  }
+
+  [[nodiscard]] static Expected<Result>
+  run(MachineFunction &Function, const TargetDescription &Target, MachineAnalysisManager &Analyses);
+};
+
+[[nodiscard]] Expected<void> registerStage8MachineAnalyses(MachineAnalysisManager &Analyses);
+
+} // namespace rcc
+
+#endif // RCC_CODEGEN_MACHINEANALYSES_H
diff --git a/backend/include/rcc/CodeGen/MachineIRBuilder.h b/backend/include/rcc/CodeGen/MachineIRBuilder.h
index 2a5979b..2524c7a 100644
--- a/backend/include/rcc/CodeGen/MachineIRBuilder.h
+++ b/backend/include/rcc/CodeGen/MachineIRBuilder.h
@@ -161,6 +161,16 @@ public:
     return *Function;
   }
 
+  [[nodiscard]] const TargetDescription &target() const noexcept {
+    return *Target;
+  }
+
+  [[nodiscard]] MachineBasicBlock *insertionBlock() const noexcept {
+    return InsertBlock;
+  }
+
+  [[nodiscard]] Expected<void> verifyInsertPoint() const;
+
   [[nodiscard]] Expected<void> setInsertPoint(MachineBasicBlock &Block);
   [[nodiscard]] Expected<void> setInsertPointBefore(MachineInstr &Instruction);
   [[nodiscard]] Expected<void> setInsertPointAfter(MachineInstr &Instruction);
diff --git a/backend/include/rcc/CodeGen/MachineIRTypes.h b/backend/include/rcc/CodeGen/MachineIRTypes.h
index f7095cc..ea65eff 100644
--- a/backend/include/rcc/CodeGen/MachineIRTypes.h
+++ b/backend/include/rcc/CodeGen/MachineIRTypes.h
@@ -61,6 +61,7 @@ struct OriginIDTag;
 struct TargetConstantTypeIDTag;
 struct TargetFunctionStateTypeIDTag;
 struct TargetRelocationKindIDTag;
+struct CallingConventionIDTag;
 
 } // namespace detail
 
@@ -86,6 +87,7 @@ using OriginID = MachineIndex<detail::OriginIDTag, std::uint64_t>;
 using TargetConstantTypeID = MachineIndex<detail::TargetConstantTypeIDTag, std::uint64_t>;
 using TargetFunctionStateTypeID = MachineIndex<detail::TargetFunctionStateTypeIDTag, std::uint64_t>;
 using TargetRelocationKindID = MachineIndex<detail::TargetRelocationKindIDTag>;
+using CallingConventionID = MachineIndex<detail::CallingConventionIDTag>;
 
 class Alignment final {
 public:
@@ -298,6 +300,7 @@ struct SourceLocation final {
 static_assert(sizeof(Opcode) == sizeof(std::uint32_t));
 static_assert(sizeof(Alignment) == sizeof(std::uint64_t));
 static_assert(sizeof(FrameIndex) == sizeof(std::uint32_t));
+static_assert(sizeof(CallingConventionID) == sizeof(std::uint32_t));
 static_assert(sizeof(MemoryAliasSourceID) == sizeof(std::uint64_t));
 static_assert(std::is_trivially_copyable_v<Opcode>);
 static_assert(std::is_trivially_copyable_v<FrameIndex>);
diff --git a/backend/include/rcc/CodeGen/MachinePass.h b/backend/include/rcc/CodeGen/MachinePass.h
new file mode 100644
index 0000000..66e3b6b
--- /dev/null
+++ b/backend/include/rcc/CodeGen/MachinePass.h
@@ -0,0 +1,655 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef RCC_CODEGEN_MACHINEPASS_H
+#define RCC_CODEGEN_MACHINEPASS_H
+
+#include "rcc/CodeGen/InstructionDescriptor.h"
+#include "rcc/CodeGen/MachineFunctionProperties.h"
+#include "rcc/Support/Error.h"
+
+#include <concepts>
+#include <cstddef>
+#include <cstdint>
+#include <functional>
+#include <initializer_list>
+#include <memory>
+#include <mutex>
+#include <optional>
+#include <span>
+#include <string>
+#include <string_view>
+#include <unordered_map>
+#include <unordered_set>
+#include <utility>
+#include <vector>
+
+namespace rcc {
+
+class CompilationUnit;
+class MachineFunction;
+class MachineVerifier;
+class TargetDescription;
+
+using AnalysisID = const void *;
+
+enum class MachinePassChange : std::uint32_t {
+  None = 0,
+  Instructions = 1U << 0U,
+  Operands = 1U << 1U,
+  Registers = 1U << 2U,
+  CFG = 1U << 3U,
+  BlockLayout = 1U << 4U,
+  Frame = 1U << 5U,
+  ConstantPool = 1U << 6U,
+  JumpTable = 1U << 7U,
+  TargetState = 1U << 8U,
+};
+
+class MachinePassChanges final {
+public:
+  constexpr MachinePassChanges() noexcept = default;
+  constexpr MachinePassChanges(std::initializer_list<MachinePassChange> Changes) noexcept {
+    for (const MachinePassChange Change : Changes)
+      add(Change);
+  }
+
+  [[nodiscard]] static constexpr MachinePassChanges all() noexcept {
+    return fromRaw((1U << 9U) - 1U);
+  }
+
+  [[nodiscard]] static constexpr MachinePassChanges fromRaw(std::uint32_t Bits) noexcept {
+    MachinePassChanges Result;
+    Result.Bits = Bits & rawMask();
+    return Result;
+  }
+
+  constexpr void add(MachinePassChange Change) noexcept {
+    Bits |= static_cast<std::uint32_t>(Change);
+  }
+
+  [[nodiscard]] constexpr bool has(MachinePassChange Change) const noexcept {
+    return (Bits & static_cast<std::uint32_t>(Change)) != 0;
+  }
+
+  [[nodiscard]] constexpr bool contains(MachinePassChanges Other) const noexcept {
+    return (Bits & Other.Bits) == Other.Bits;
+  }
+
+  [[nodiscard]] constexpr bool intersects(MachinePassChanges Other) const noexcept {
+    return (Bits & Other.Bits) != 0;
+  }
+
+  [[nodiscard]] constexpr bool empty() const noexcept {
+    return Bits == 0;
+  }
+
+  [[nodiscard]] constexpr std::uint32_t rawValue() const noexcept {
+    return Bits;
+  }
+
+  friend constexpr bool operator==(MachinePassChanges Left,
+                                   MachinePassChanges Right) noexcept = default;
+
+private:
+  [[nodiscard]] static constexpr std::uint32_t rawMask() noexcept {
+    return (1U << 9U) - 1U;
+  }
+
+  std::uint32_t Bits = 0;
+};
+
+class PreservedAnalyses final {
+public:
+  [[nodiscard]] static PreservedAnalyses all() noexcept {
+    PreservedAnalyses Result;
+    Result.PreserveAll = true;
+    return Result;
+  }
+
+  [[nodiscard]] static PreservedAnalyses none() noexcept {
+    return {};
+  }
+
+  void preserve(AnalysisID ID) {
+    if (ID != nullptr)
+      Preserved.insert(ID);
+  }
+
+  template <typename AnalysisT> void preserve() {
+    preserve(analysisID<AnalysisT>());
+  }
+
+  [[nodiscard]] bool preserves(AnalysisID ID) const noexcept {
+    return PreserveAll || (ID != nullptr && Preserved.contains(ID));
+  }
+
+  [[nodiscard]] bool preservesAll() const noexcept {
+    return PreserveAll;
+  }
+
+  template <typename AnalysisT> [[nodiscard]] static AnalysisID analysisID() noexcept {
+    static const std::uint8_t Token = 0;
+    return &Token;
+  }
+
+private:
+  bool PreserveAll = false;
+  std::unordered_set<AnalysisID> Preserved;
+};
+
+enum class PassThreadSafety : std::uint8_t {
+  NotThreadSafe,
+  ThreadSafe,
+};
+
+struct PassParameter final {
+  std::string Name;
+  std::string Description;
+  std::optional<std::string> DefaultValue;
+  bool Required = false;
+};
+
+struct MachinePassRegistrationMetadata {
+  std::vector<PassParameter> Parameters;
+  PassThreadSafety ThreadSafety = PassThreadSafety::NotThreadSafe;
+  MachinePassChanges DeclaredChanges = MachinePassChanges::all();
+};
+
+struct MachinePassContract final : MachinePassRegistrationMetadata {
+  std::string Name;
+  MachineFunctionProperties Requires;
+  MachineFunctionProperties Sets;
+  MachineFunctionProperties Clears;
+  std::vector<AnalysisID> RequiredAnalyses;
+  std::optional<PipelineStage> VerificationStage;
+};
+
+struct MachinePassResult final {
+  bool Changed = false;
+  MachinePassChanges Changes;
+  PreservedAnalyses Preserved = PreservedAnalyses::none();
+};
+
+struct CompilationUnitPassContract final {
+  std::string Name;
+  std::vector<AnalysisID> RequiredAnalyses;
+  std::vector<PassParameter> Parameters;
+  MachinePassChanges DeclaredChanges = MachinePassChanges::all();
+};
+
+struct CompilationUnitPassResult final {
+  bool Changed = false;
+  MachinePassChanges Changes;
+  PreservedAnalyses PreservedUnitAnalyses = PreservedAnalyses::none();
+  PreservedAnalyses PreservedFunctionAnalyses = PreservedAnalyses::none();
+};
+
+struct MachineAnalysisRegistration final {
+  AnalysisID ID = nullptr;
+  std::string Name;
+  std::vector<AnalysisID> Dependencies;
+  MachinePassChanges InvalidatedBy = MachinePassChanges::all();
+  PassThreadSafety ThreadSafety = PassThreadSafety::NotThreadSafe;
+};
+
+struct CompilationUnitAnalysisRegistration final {
+  AnalysisID ID = nullptr;
+  std::string Name;
+  std::vector<AnalysisID> Dependencies;
+  MachinePassChanges InvalidatedBy = MachinePassChanges::all();
+};
+
+class MachinePassInstrumentation;
+
+class MachineAnalysisManager final {
+public:
+  MachineAnalysisManager() = default;
+  MachineAnalysisManager(const MachineAnalysisManager &) = delete;
+  MachineAnalysisManager &operator=(const MachineAnalysisManager &) = delete;
+  MachineAnalysisManager(MachineAnalysisManager &&) = delete;
+  MachineAnalysisManager &operator=(MachineAnalysisManager &&) = delete;
+  ~MachineAnalysisManager() = default;
+
+  template <typename AnalysisT> [[nodiscard]] static AnalysisID id() noexcept {
+    return PreservedAnalyses::analysisID<AnalysisT>();
+  }
+
+  template <typename AnalysisT>
+  [[nodiscard]] Expected<void> registerAnalysis(MachineAnalysisRegistration Registration = {}) {
+    using ResultT = typename AnalysisT::Result;
+    if (Registration.ID == nullptr)
+      Registration.ID = id<AnalysisT>();
+    if (Registration.Name.empty()) {
+      if constexpr (requires {
+                      { AnalysisT::name() } -> std::convertible_to<std::string_view>;
+                    }) {
+        Registration.Name = std::string(AnalysisT::name());
+      } else {
+        Registration.Name = "unnamed-machine-analysis";
+      }
+    }
+
+    ErasedRunner Runner = [](MachineFunction &Function, const TargetDescription &Target,
+                             MachineAnalysisManager &Manager) -> Expected<std::shared_ptr<void>> {
+      auto Computed = AnalysisT::run(Function, Target, Manager);
+      if (!Computed)
+        return std::unexpected(Computed.error());
+      return std::shared_ptr<void>(new ResultT(std::move(*Computed)),
+                                   [](void *Value) { delete static_cast<ResultT *>(Value); });
+    };
+    ErasedInvalidator Invalidator = [](void *Value, const MachineFunction &Function,
+                                       const PreservedAnalyses &Preserved) -> bool {
+      if constexpr (requires(ResultT &Result, const MachineFunction &InputFunction,
+                             const PreservedAnalyses &Analyses) {
+                      { Result.invalidate(InputFunction, Analyses) } -> std::convertible_to<bool>;
+                    }) {
+        return static_cast<ResultT *>(Value)->invalidate(Function, Preserved);
+      }
+      return true;
+    };
+    return registerAnalysisImpl(std::move(Registration), std::move(Runner), std::move(Invalidator));
+  }
+
+  template <typename AnalysisT>
+  [[nodiscard]] Expected<typename AnalysisT::Result *> getResult(MachineFunction &Function,
+                                                                 const TargetDescription &Target) {
+    const AnalysisID Key = id<AnalysisT>();
+    if (!isRegistered(Key)) {
+      auto Registered = registerAnalysis<AnalysisT>();
+      if (!Registered)
+        return std::unexpected(Registered.error());
+    }
+    auto Result = getResultImpl(Key, Function, Target);
+    if (!Result)
+      return std::unexpected(Result.error());
+    return static_cast<typename AnalysisT::Result *>(*Result);
+  }
+
+  void invalidate(MachineFunction &Function, const PreservedAnalyses &Preserved,
+                  MachinePassChanges Changes) noexcept;
+  void invalidate(MachineFunction &Function, const PreservedAnalyses &Preserved) noexcept {
+    invalidate(Function, Preserved, MachinePassChanges::all());
+  }
+  [[nodiscard]] bool hasCached(const MachineFunction &Function, AnalysisID ID) const noexcept;
+  [[nodiscard]] bool isRegistered(AnalysisID ID) const noexcept;
+  [[nodiscard]] std::size_t cachedResultCount(const MachineFunction &Function) const noexcept;
+  void clear(MachineFunction &Function) noexcept;
+  void clearAll() noexcept;
+
+  [[nodiscard]] Expected<std::unique_ptr<MachineAnalysisManager>> forkEmpty() const;
+  [[nodiscard]] Expected<bool>
+  requestAction(std::string_view Action, const MachineFunction &Function, std::uint64_t Cost = 1);
+
+private:
+  using ErasedRunner = std::function<Expected<std::shared_ptr<void>>(
+      MachineFunction &, const TargetDescription &, MachineAnalysisManager &)>;
+  using ErasedInvalidator =
+      std::function<bool(void *, const MachineFunction &, const PreservedAnalyses &)>;
+
+  struct RegisteredAnalysis final {
+    MachineAnalysisRegistration Info;
+    ErasedRunner Runner;
+    ErasedInvalidator Invalidator;
+  };
+
+  struct CacheEntry final {
+    std::shared_ptr<void> Value;
+    AnalysisID ID = nullptr;
+  };
+
+  [[nodiscard]] Expected<void> registerAnalysisImpl(MachineAnalysisRegistration Registration,
+                                                    ErasedRunner Runner,
+                                                    ErasedInvalidator Invalidator);
+  [[nodiscard]] Expected<void *> getResultImpl(AnalysisID ID, MachineFunction &Function,
+                                               const TargetDescription &Target);
+  [[nodiscard]] Expected<void> materializeDependencies(const RegisteredAnalysis &Registration,
+                                                       MachineFunction &Function,
+                                                       const TargetDescription &Target);
+  [[nodiscard]] Expected<void>
+  validateParallelRequirements(std::span<const AnalysisID> RequiredAnalyses) const;
+  void setInstrumentation(MachinePassInstrumentation *NewInstrumentation) noexcept {
+    Instrumentation = NewInstrumentation;
+  }
+
+  std::unordered_map<AnalysisID, RegisteredAnalysis> Registry;
+  std::unordered_map<MachineFunction *, std::unordered_map<AnalysisID, CacheEntry>> Cache;
+  std::unordered_map<MachineFunction *, std::vector<AnalysisID>> ActiveComputations;
+  MachinePassInstrumentation *Instrumentation = nullptr;
+
+  friend class MachinePassManager;
+  friend class CompilationUnitPassManager;
+  friend Expected<void> registerStage8MachineAnalyses(MachineAnalysisManager &Analyses);
+};
+
+class CompilationUnitAnalysisManager final {
+public:
+  CompilationUnitAnalysisManager() = default;
+  CompilationUnitAnalysisManager(const CompilationUnitAnalysisManager &) = delete;
+  CompilationUnitAnalysisManager &operator=(const CompilationUnitAnalysisManager &) = delete;
+  CompilationUnitAnalysisManager(CompilationUnitAnalysisManager &&) = delete;
+  CompilationUnitAnalysisManager &operator=(CompilationUnitAnalysisManager &&) = delete;
+  ~CompilationUnitAnalysisManager() = default;
+
+  template <typename AnalysisT> [[nodiscard]] static AnalysisID id() noexcept {
+    return PreservedAnalyses::analysisID<AnalysisT>();
+  }
+
+  template <typename AnalysisT>
+  [[nodiscard]] Expected<void>
+  registerAnalysis(CompilationUnitAnalysisRegistration Registration = {}) {
+    using ResultT = typename AnalysisT::Result;
+    if (Registration.ID == nullptr)
+      Registration.ID = id<AnalysisT>();
+    if (Registration.Name.empty()) {
+      if constexpr (requires {
+                      { AnalysisT::name() } -> std::convertible_to<std::string_view>;
+                    }) {
+        Registration.Name = std::string(AnalysisT::name());
+      } else {
+        Registration.Name = "unnamed-compilation-unit-analysis";
+      }
+    }
+
+    ErasedRunner Runner =
+        [](CompilationUnit &Unit, const TargetDescription &Target,
+           CompilationUnitAnalysisManager &Manager) -> Expected<std::shared_ptr<void>> {
+      auto Computed = AnalysisT::run(Unit, Target, Manager);
+      if (!Computed)
+        return std::unexpected(Computed.error());
+      return std::shared_ptr<void>(new ResultT(std::move(*Computed)),
+                                   [](void *Value) { delete static_cast<ResultT *>(Value); });
+    };
+    ErasedInvalidator Invalidator = [](void *Value, const CompilationUnit &Unit,
+                                       const PreservedAnalyses &Preserved) -> bool {
+      if constexpr (requires(ResultT &Result, const CompilationUnit &InputUnit,
+                             const PreservedAnalyses &Analyses) {
+                      { Result.invalidate(InputUnit, Analyses) } -> std::convertible_to<bool>;
+                    }) {
+        return static_cast<ResultT *>(Value)->invalidate(Unit, Preserved);
+      }
+      return true;
+    };
+    return registerAnalysisImpl(std::move(Registration), std::move(Runner), std::move(Invalidator));
+  }
+
+  template <typename AnalysisT>
+  [[nodiscard]] Expected<typename AnalysisT::Result *> getResult(CompilationUnit &Unit,
+                                                                 const TargetDescription &Target) {
+    const AnalysisID Key = id<AnalysisT>();
+    if (!isRegistered(Key)) {
+      auto Registered = registerAnalysis<AnalysisT>();
+      if (!Registered)
+        return std::unexpected(Registered.error());
+    }
+    auto Result = getResultImpl(Key, Unit, Target);
+    if (!Result)
+      return std::unexpected(Result.error());
+    return static_cast<typename AnalysisT::Result *>(*Result);
+  }
+
+  void invalidate(CompilationUnit &Unit, const PreservedAnalyses &Preserved,
+                  MachinePassChanges Changes) noexcept;
+  [[nodiscard]] bool hasCached(const CompilationUnit &Unit, AnalysisID ID) const noexcept;
+  [[nodiscard]] bool isRegistered(AnalysisID ID) const noexcept;
+  void clear(CompilationUnit &Unit) noexcept;
+  void clearAll() noexcept;
+
+private:
+  using ErasedRunner = std::function<Expected<std::shared_ptr<void>>(
+      CompilationUnit &, const TargetDescription &, CompilationUnitAnalysisManager &)>;
+  using ErasedInvalidator =
+      std::function<bool(void *, const CompilationUnit &, const PreservedAnalyses &)>;
+
+  struct RegisteredAnalysis final {
+    CompilationUnitAnalysisRegistration Info;
+    ErasedRunner Runner;
+    ErasedInvalidator Invalidator;
+  };
+
+  struct CacheEntry final {
+    std::shared_ptr<void> Value;
+    AnalysisID ID = nullptr;
+  };
+
+  [[nodiscard]] Expected<void>
+  registerAnalysisImpl(CompilationUnitAnalysisRegistration Registration, ErasedRunner Runner,
+                       ErasedInvalidator Invalidator);
+  [[nodiscard]] Expected<void *> getResultImpl(AnalysisID ID, CompilationUnit &Unit,
+                                               const TargetDescription &Target);
+  [[nodiscard]] Expected<void> materializeDependencies(const RegisteredAnalysis &Registration,
+                                                       CompilationUnit &Unit,
+                                                       const TargetDescription &Target);
+  void setInstrumentation(MachinePassInstrumentation *NewInstrumentation) noexcept {
+    Instrumentation = NewInstrumentation;
+  }
+
+  std::unordered_map<AnalysisID, RegisteredAnalysis> Registry;
+  std::unordered_map<CompilationUnit *, std::unordered_map<AnalysisID, CacheEntry>> Cache;
+  std::unordered_map<CompilationUnit *, std::vector<AnalysisID>> ActiveComputations;
+  MachinePassInstrumentation *Instrumentation = nullptr;
+
+  friend class CompilationUnitPassManager;
+};
+
+class MachineFunctionPass {
+public:
+  MachineFunctionPass() = default;
+  MachineFunctionPass(const MachineFunctionPass &) = delete;
+  MachineFunctionPass &operator=(const MachineFunctionPass &) = delete;
+  virtual ~MachineFunctionPass() = default;
+
+  [[nodiscard]] virtual const MachinePassContract &contract() const noexcept = 0;
+  [[nodiscard]] virtual Expected<MachinePassResult> run(MachineFunction &Function,
+                                                        const TargetDescription &Target,
+                                                        MachineAnalysisManager &Analyses) = 0;
+};
+
+class CompilationUnitPass {
+public:
+  CompilationUnitPass() = default;
+  CompilationUnitPass(const CompilationUnitPass &) = delete;
+  CompilationUnitPass &operator=(const CompilationUnitPass &) = delete;
+  virtual ~CompilationUnitPass() = default;
+
+  [[nodiscard]] virtual const CompilationUnitPassContract &contract() const noexcept = 0;
+  [[nodiscard]] virtual Expected<CompilationUnitPassResult>
+  run(CompilationUnit &Unit, const TargetDescription &Target,
+      CompilationUnitAnalysisManager &UnitAnalyses, MachineAnalysisManager &FunctionAnalyses) = 0;
+};
+
+enum class InstrumentationPhase : std::uint8_t {
+  Before,
+  After,
+};
+
+struct InstrumentationStatistic final {
+  std::string Name;
+  bool IsAnalysis = false;
+  std::uint64_t Invocations = 0;
+  std::uint64_t CacheHits = 0;
+  std::uint64_t Changes = 0;
+  std::uint64_t Failures = 0;
+  std::uint64_t TotalNanoseconds = 0;
+};
+
+class MachinePassInstrumentation final {
+public:
+  using BeforeCallback = std::function<void(std::string_view, const MachineFunction &)>;
+  using AfterCallback =
+      std::function<void(std::string_view, const MachineFunction &, const MachinePassResult &)>;
+  using FailureCallback =
+      std::function<void(std::string_view, const MachineFunction &, const Error &)>;
+  using BeforeAnalysisCallback = std::function<void(std::string_view, const MachineFunction &)>;
+  using AfterAnalysisCallback =
+      std::function<void(std::string_view, const MachineFunction &, bool, std::uint64_t)>;
+  using AnalysisFailureCallback =
+      std::function<void(std::string_view, const MachineFunction &, const Error &)>;
+  using IRPrintCallback =
+      std::function<void(InstrumentationPhase, std::string_view, const MachineFunction &)>;
+  using ChangeCallback =
+      std::function<void(std::string_view, const MachineFunction &, MachinePassChanges, bool)>;
+  using ActionFilter =
+      std::function<bool(std::string_view, const MachineFunction &, std::uint64_t)>;
+
+  using BeforeUnitCallback = std::function<void(std::string_view, const CompilationUnit &)>;
+  using AfterUnitCallback = std::function<void(std::string_view, const CompilationUnit &,
+                                               const CompilationUnitPassResult &)>;
+  using UnitFailureCallback =
+      std::function<void(std::string_view, const CompilationUnit &, const Error &)>;
+  using BeforeUnitAnalysisCallback = std::function<void(std::string_view, const CompilationUnit &)>;
+  using AfterUnitAnalysisCallback =
+      std::function<void(std::string_view, const CompilationUnit &, bool, std::uint64_t)>;
+  using UnitAnalysisFailureCallback =
+      std::function<void(std::string_view, const CompilationUnit &, const Error &)>;
+
+  void addBeforeCallback(BeforeCallback Callback);
+  void addAfterCallback(AfterCallback Callback);
+  void addFailureCallback(FailureCallback Callback);
+  void addBeforeAnalysisCallback(BeforeAnalysisCallback Callback);
+  void addAfterAnalysisCallback(AfterAnalysisCallback Callback);
+  void addAnalysisFailureCallback(AnalysisFailureCallback Callback);
+  void addIRPrintCallback(IRPrintCallback Callback);
+  void addChangeCallback(ChangeCallback Callback);
+  void setActionFilter(ActionFilter Filter);
+  void setPerFunctionFuel(std::optional<std::uint64_t> Fuel);
+
+  void addBeforeUnitCallback(BeforeUnitCallback Callback);
+  void addAfterUnitCallback(AfterUnitCallback Callback);
+  void addUnitFailureCallback(UnitFailureCallback Callback);
+  void addBeforeUnitAnalysisCallback(BeforeUnitAnalysisCallback Callback);
+  void addAfterUnitAnalysisCallback(AfterUnitAnalysisCallback Callback);
+  void addUnitAnalysisFailureCallback(UnitAnalysisFailureCallback Callback);
+
+  [[nodiscard]] std::vector<InstrumentationStatistic> statistics() const;
+  void clearStatistics();
+
+private:
+  struct BufferedEvents final {
+    const TargetDescription *Target = nullptr;
+    std::vector<std::function<void()>> Events;
+  };
+
+  [[nodiscard]] bool bufferFunctionEvent(const MachineFunction &Function,
+                                         std::function<void(const MachineFunction &)> Replay) const;
+  void beginBuffering(BufferedEvents &Buffer, const TargetDescription &Target) const noexcept;
+  void endBuffering() const noexcept;
+  void replayBufferedEvents(BufferedEvents &Buffer) const;
+
+  void before(std::string_view Name, const MachineFunction &Function) const;
+  void after(std::string_view Name, const MachineFunction &Function,
+             const MachinePassResult &Result, std::uint64_t Nanoseconds) const;
+  void failure(std::string_view Name, const MachineFunction &Function, const Error &ErrorValue,
+               std::uint64_t Nanoseconds = 0) const;
+  void beforeAnalysis(std::string_view Name, const MachineFunction &Function) const;
+  void afterAnalysis(std::string_view Name, const MachineFunction &Function, bool CacheHit,
+                     std::uint64_t Nanoseconds) const;
+  void analysisFailure(std::string_view Name, const MachineFunction &Function,
+                       const Error &ErrorValue, std::uint64_t Nanoseconds) const;
+  void change(std::string_view Name, const MachineFunction &Function, MachinePassChanges Changes,
+              bool FingerprintChanged) const;
+  [[nodiscard]] Expected<bool> requestAction(std::string_view Action,
+                                             const MachineFunction &Function, std::uint64_t Cost);
+
+  void beforeUnit(std::string_view Name, const CompilationUnit &Unit) const;
+  void afterUnit(std::string_view Name, const CompilationUnit &Unit,
+                 const CompilationUnitPassResult &Result, std::uint64_t Nanoseconds) const;
+  void unitFailure(std::string_view Name, const CompilationUnit &Unit, const Error &ErrorValue,
+                   std::uint64_t Nanoseconds = 0) const;
+  void beforeUnitAnalysis(std::string_view Name, const CompilationUnit &Unit) const;
+  void afterUnitAnalysis(std::string_view Name, const CompilationUnit &Unit, bool CacheHit,
+                         std::uint64_t Nanoseconds) const;
+  void unitAnalysisFailure(std::string_view Name, const CompilationUnit &Unit,
+                           const Error &ErrorValue, std::uint64_t Nanoseconds) const;
+
+  [[nodiscard]] InstrumentationStatistic &statistic(std::string_view Name, bool IsAnalysis) const;
+
+  mutable std::mutex Mutex;
+  mutable std::mutex ActionMutex;
+  std::vector<BeforeCallback> Before;
+  std::vector<AfterCallback> After;
+  std::vector<FailureCallback> Failure;
+  std::vector<BeforeAnalysisCallback> BeforeAnalysis;
+  std::vector<AfterAnalysisCallback> AfterAnalysis;
+  std::vector<AnalysisFailureCallback> AnalysisFailure;
+  std::vector<IRPrintCallback> IRPrint;
+  std::vector<ChangeCallback> Change;
+  ActionFilter Filter;
+  std::optional<std::uint64_t> PerFunctionFuel;
+  std::unordered_map<std::uint64_t, std::uint64_t> ConsumedFuel;
+
+  std::vector<BeforeUnitCallback> BeforeUnit;
+  std::vector<AfterUnitCallback> AfterUnit;
+  std::vector<UnitFailureCallback> UnitFailure;
+  std::vector<BeforeUnitAnalysisCallback> BeforeUnitAnalysis;
+  std::vector<AfterUnitAnalysisCallback> AfterUnitAnalysis;
+  std::vector<UnitAnalysisFailureCallback> UnitAnalysisFailure;
+  mutable std::unordered_map<std::string, InstrumentationStatistic> Statistics;
+
+  static thread_local BufferedEvents *ActiveBuffer;
+
+  friend class CompilationUnitAnalysisManager;
+  friend class CompilationUnitPassManager;
+  friend class MachineAnalysisManager;
+  friend class MachinePassManager;
+};
+
+struct MachinePassManagerOptions final {
+  bool VerifyBefore = true;
+  bool VerifyEach = true;
+  bool DetectUnreportedChanges = false;
+};
+
+class MachinePassManager final {
+public:
+  explicit MachinePassManager(MachinePassManagerOptions Options = {}) : Options(Options) {}
+
+  MachinePassManager(const MachinePassManager &) = delete;
+  MachinePassManager &operator=(const MachinePassManager &) = delete;
+
+  [[nodiscard]] Expected<void> addPass(std::unique_ptr<MachineFunctionPass> Pass);
+  [[nodiscard]] Expected<void> run(MachineFunction &Function, const TargetDescription &Target,
+                                   MachineAnalysisManager &Analyses,
+                                   MachinePassInstrumentation *Instrumentation = nullptr) const;
+  [[nodiscard]] Expected<void>
+  runFunctions(CompilationUnit &Unit, const TargetDescription &Target,
+               const MachineAnalysisManager &AnalysisPrototype, std::size_t ThreadCount,
+               MachinePassInstrumentation *Instrumentation = nullptr) const;
+
+  [[nodiscard]] std::size_t size() const noexcept {
+    return Passes.size();
+  }
+
+private:
+  [[nodiscard]] Expected<void> validateContract(const MachinePassContract &Contract) const;
+
+  MachinePassManagerOptions Options;
+  std::vector<std::unique_ptr<MachineFunctionPass>> Passes;
+};
+
+struct CompilationUnitPassManagerOptions final {
+  bool VerifyBefore = true;
+  bool VerifyEach = true;
+};
+
+class CompilationUnitPassManager final {
+public:
+  explicit CompilationUnitPassManager(CompilationUnitPassManagerOptions Options = {})
+      : Options(Options) {}
+
+  CompilationUnitPassManager(const CompilationUnitPassManager &) = delete;
+  CompilationUnitPassManager &operator=(const CompilationUnitPassManager &) = delete;
+
+  [[nodiscard]] Expected<void> addPass(std::unique_ptr<CompilationUnitPass> Pass);
+  [[nodiscard]] Expected<void> run(CompilationUnit &Unit, const TargetDescription &Target,
+                                   CompilationUnitAnalysisManager &UnitAnalyses,
+                                   MachineAnalysisManager &FunctionAnalyses,
+                                   MachinePassInstrumentation *Instrumentation = nullptr) const;
+
+private:
+  CompilationUnitPassManagerOptions Options;
+  std::vector<std::unique_ptr<CompilationUnitPass>> Passes;
+};
+
+} // namespace rcc
+
+#endif // RCC_CODEGEN_MACHINEPASS_H
diff --git a/backend/include/rcc/CodeGen/TargetCallLowering.h b/backend/include/rcc/CodeGen/TargetCallLowering.h
new file mode 100644
index 0000000..a6b3535
--- /dev/null
+++ b/backend/include/rcc/CodeGen/TargetCallLowering.h
@@ -0,0 +1,404 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef RCC_CODEGEN_TARGETCALLLOWERING_H
+#define RCC_CODEGEN_TARGETCALLLOWERING_H
+
+#include "rcc/CodeGen/LowLevelType.h"
+#include "rcc/CodeGen/MachineIRTypes.h"
+#include "rcc/CodeGen/Register.h"
+#include "rcc/CodeGen/RegisterMask.h"
+#include "rcc/Support/Error.h"
+
+#include <cstddef>
+#include <cstdint>
+#include <initializer_list>
+#include <memory>
+#include <optional>
+#include <span>
+#include <string>
+#include <string_view>
+#include <utility>
+#include <variant>
+#include <vector>
+
+namespace rcc {
+
+class MachineIRBuilder;
+
+enum class ABIExtensionKind : std::uint8_t {
+  None,
+  AnyExtend,
+  SignExtend,
+  ZeroExtend,
+  Count,
+};
+
+enum class ABIValueFlag : std::uint8_t {
+  ByVal,
+  StructReturn,
+  Indirect,
+  InRegister,
+  Count,
+};
+
+class ABIValueFlags final {
+public:
+  constexpr ABIValueFlags() noexcept = default;
+
+  ABIValueFlags(std::initializer_list<ABIValueFlag> Flags) noexcept;
+
+  [[nodiscard]] constexpr bool has(ABIValueFlag Flag) const noexcept {
+    const auto Index = static_cast<std::uint32_t>(Flag);
+    return Index < static_cast<std::uint32_t>(ABIValueFlag::Count) &&
+           (Bits & (std::uint8_t{1} << Index)) != 0;
+  }
+
+  constexpr void set(ABIValueFlag Flag) noexcept {
+    const auto Index = static_cast<std::uint32_t>(Flag);
+    if (Index < static_cast<std::uint32_t>(ABIValueFlag::Count))
+      Bits |= std::uint8_t{1} << Index;
+  }
+
+  [[nodiscard]] constexpr std::uint8_t rawValue() const noexcept {
+    return Bits;
+  }
+
+  friend constexpr bool operator==(ABIValueFlags Left, ABIValueFlags Right) noexcept = default;
+
+private:
+  std::uint8_t Bits = 0;
+};
+
+struct ABIValue final {
+  Register Value;
+  LLT Type;
+  std::uint32_t OriginalValue = 0;
+  std::uint16_t FragmentIndex = 0;
+  std::uint16_t FragmentCount = 1;
+  std::uint32_t FragmentOffsetBytes = 0;
+  Alignment OriginalAlignment;
+  ABIExtensionKind Extension = ABIExtensionKind::None;
+  ABIValueFlags Flags;
+  std::uint64_t ByValSizeBytes = 0;
+  Alignment ByValAlignment;
+
+  friend bool operator==(const ABIValue &Left, const ABIValue &Right) = default;
+};
+
+enum class MachineCallTargetKind : std::uint8_t {
+  Invalid,
+  GlobalSymbol,
+  ExternalSymbol,
+  IndirectRegister,
+};
+
+class MachineCallTarget final {
+public:
+  constexpr MachineCallTarget() noexcept = default;
+
+  [[nodiscard]] static Expected<MachineCallTarget> globalSymbol(std::string Name,
+                                                                std::uint32_t TargetFlags = 0);
+  [[nodiscard]] static Expected<MachineCallTarget> externalSymbol(std::string Name,
+                                                                  std::uint32_t TargetFlags = 0);
+  [[nodiscard]] static Expected<MachineCallTarget> indirect(Register Callee,
+                                                            std::uint32_t TargetFlags = 0);
+
+  [[nodiscard]] MachineCallTargetKind kind() const noexcept {
+    return Kind;
+  }
+
+  [[nodiscard]] std::string_view symbolName() const noexcept;
+  [[nodiscard]] Register indirectRegister() const noexcept;
+  [[nodiscard]] std::uint32_t targetFlags() const noexcept {
+    return TargetFlags;
+  }
+
+  [[nodiscard]] bool isValid() const noexcept {
+    return Kind != MachineCallTargetKind::Invalid;
+  }
+
+  friend bool operator==(const MachineCallTarget &Left, const MachineCallTarget &Right) = default;
+
+private:
+  using Storage = std::variant<std::monostate, std::string, Register>;
+
+  MachineCallTarget(MachineCallTargetKind Kind, Storage Value, std::uint32_t TargetFlags) noexcept
+      : Kind(Kind), Value(std::move(Value)), TargetFlags(TargetFlags) {}
+
+  MachineCallTargetKind Kind = MachineCallTargetKind::Invalid;
+  Storage Value;
+  std::uint32_t TargetFlags = 0;
+};
+
+enum class TailCallKind : std::uint8_t {
+  NotTail,
+  Tail,
+  MustTail,
+};
+
+struct TailCallContext final {
+  CallingConventionID CallerConvention;
+  std::vector<ABIValue> CallerReturns;
+  std::uint64_t ReusableIncomingArgumentBytes = 0;
+  std::size_t CallerFixedArgumentCount = 0;
+  bool CallerIsVariadic = false;
+  bool CallerHasDynamicStackAllocation = false;
+  bool CallerUsesStructReturn = false;
+};
+
+struct FormalArgumentRequest final {
+  CallingConventionID Convention;
+  std::vector<ABIValue> Arguments;
+  std::size_t FixedArgumentCount = 0;
+  bool IsVariadic = false;
+};
+
+struct CallLoweringRequest final {
+  CallingConventionID Convention;
+  MachineCallTarget Callee;
+  std::vector<ABIValue> Arguments;
+  std::vector<ABIValue> Results;
+  std::size_t FixedArgumentCount = 0;
+  std::uint64_t CallSiteID = 0;
+  bool IsVariadic = false;
+  TailCallKind TailKind = TailCallKind::NotTail;
+  std::optional<TailCallContext> TailContext;
+};
+
+struct ReturnLoweringRequest final {
+  CallingConventionID Convention;
+  std::vector<ABIValue> Values;
+  bool FunctionIsVariadic = false;
+};
+
+enum class CCLocationKind : std::uint8_t {
+  Register,
+  Stack,
+  Indirect,
+  Custom,
+};
+
+enum class CCAssignmentFlag : std::uint8_t {
+  Variadic,
+  ByVal,
+  StructReturn,
+  Indirect,
+  InRegister,
+  Bitcast,
+  Count,
+};
+
+class CCAssignmentFlags final {
+public:
+  constexpr CCAssignmentFlags() noexcept = default;
+
+  CCAssignmentFlags(std::initializer_list<CCAssignmentFlag> Flags) noexcept;
+
+  [[nodiscard]] constexpr bool has(CCAssignmentFlag Flag) const noexcept {
+    const auto Index = static_cast<std::uint32_t>(Flag);
+    return Index < static_cast<std::uint32_t>(CCAssignmentFlag::Count) &&
+           (Bits & (std::uint8_t{1} << Index)) != 0;
+  }
+
+  constexpr void set(CCAssignmentFlag Flag) noexcept {
+    const auto Index = static_cast<std::uint32_t>(Flag);
+    if (Index < static_cast<std::uint32_t>(CCAssignmentFlag::Count))
+      Bits |= std::uint8_t{1} << Index;
+  }
+
+  [[nodiscard]] constexpr std::uint8_t rawValue() const noexcept {
+    return Bits;
+  }
+
+  friend constexpr bool operator==(CCAssignmentFlags Left,
+                                   CCAssignmentFlags Right) noexcept = default;
+
+private:
+  std::uint8_t Bits = 0;
+};
+
+struct CCAssignment final {
+  std::size_t ValueIndex = 0;
+  Register OriginalValue;
+  std::uint32_t OriginalValueIndex = 0;
+  std::uint16_t FragmentIndex = 0;
+  std::uint16_t FragmentCount = 1;
+  LLT ValueType;
+  LLT LocationType;
+  CCLocationKind LocationKind = CCLocationKind::Register;
+  std::optional<PhysicalRegister> LocationRegister;
+  std::optional<std::uint64_t> StackOffsetBytes;
+  std::uint64_t LocationSizeBytes = 0;
+  std::uint64_t StackSlotSizeBytes = 0;
+  Alignment LocationAlignment;
+  ABIExtensionKind Extension = ABIExtensionKind::None;
+  CCAssignmentFlags CustomFlags;
+
+  friend bool operator==(const CCAssignment &Left, const CCAssignment &Right) = default;
+};
+
+struct StackArgumentArea final {
+  std::uint64_t SizeBytes = 0;
+  std::uint64_t ShadowSpaceBytes = 0;
+  Alignment Align;
+
+  friend bool operator==(StackArgumentArea Left, StackArgumentArea Right) noexcept = default;
+};
+
+struct CallFrameRequirements final {
+  std::uint64_t SizeBytes = 0;
+  Alignment Align;
+  bool EmitSetup = false;
+  bool EmitDestroy = false;
+  bool ReusesIncomingArea = false;
+
+  friend bool operator==(CallFrameRequirements Left,
+                         CallFrameRequirements Right) noexcept = default;
+};
+
+struct VarArgRegisterSave final {
+  PhysicalRegister Reg;
+  std::uint64_t OffsetBytes = 0;
+
+  friend bool operator==(VarArgRegisterSave Left, VarArgRegisterSave Right) noexcept = default;
+};
+
+struct VarArgLoweringState final {
+  bool IsVariadic = false;
+  std::size_t FixedArgumentCount = 0;
+  std::size_t FirstUnallocatedIntegerRegister = 0;
+  std::uint64_t OverflowAreaOffsetBytes = 0;
+  std::int64_t RegisterSaveAreaOffsetBytes = 0;
+  std::uint64_t RegisterSaveAreaSizeBytes = 0;
+  std::uint64_t RegisterSavePaddingBytes = 0;
+  std::vector<VarArgRegisterSave> RegistersToSave;
+
+  friend bool operator==(const VarArgLoweringState &Left,
+                         const VarArgLoweringState &Right) = default;
+};
+
+struct ByValCopyAssignment final {
+  std::size_t ArgumentAssignmentIndex = 0;
+  Register Source;
+  LLT PointerType;
+  std::uint64_t StackOffsetBytes = 0;
+  std::uint64_t SizeBytes = 0;
+  Alignment Align;
+
+  friend bool operator==(ByValCopyAssignment Left, ByValCopyAssignment Right) noexcept = default;
+};
+
+enum class CallLoweringPlanKind : std::uint8_t {
+  FormalArguments,
+  Call,
+  Return,
+};
+
+struct CallLoweringPlanDesc final {
+  CallLoweringPlanKind Kind = CallLoweringPlanKind::FormalArguments;
+  std::string Target;
+  CallingConventionID Convention;
+  std::vector<CCAssignment> ArgumentAssignments;
+  std::vector<CCAssignment> ReturnAssignments;
+  StackArgumentArea StackArguments;
+  CallFrameRequirements CallFrame;
+  VarArgLoweringState VarArgs;
+  std::vector<ByValCopyAssignment> ByValCopies;
+  std::shared_ptr<const RegisterMask> PreservedMask;
+  std::optional<MachineCallTarget> Callee;
+  std::uint64_t CallSiteID = 0;
+  TailCallKind TailDecision = TailCallKind::NotTail;
+  std::string TailRejectionReason;
+};
+
+class CallLoweringPlan final {
+public:
+  [[nodiscard]] static Expected<CallLoweringPlan> create(CallLoweringPlanDesc Description);
+
+  [[nodiscard]] CallLoweringPlanKind kind() const noexcept {
+    return Description.Kind;
+  }
+
+  [[nodiscard]] std::string_view target() const noexcept {
+    return Description.Target;
+  }
+
+  [[nodiscard]] CallingConventionID convention() const noexcept {
+    return Description.Convention;
+  }
+
+  [[nodiscard]] std::span<const CCAssignment> argumentAssignments() const noexcept {
+    return Description.ArgumentAssignments;
+  }
+
+  [[nodiscard]] std::span<const CCAssignment> returnAssignments() const noexcept {
+    return Description.ReturnAssignments;
+  }
+
+  [[nodiscard]] const StackArgumentArea &stackArguments() const noexcept {
+    return Description.StackArguments;
+  }
+
+  [[nodiscard]] const CallFrameRequirements &callFrame() const noexcept {
+    return Description.CallFrame;
+  }
+
+  [[nodiscard]] const VarArgLoweringState &varArgs() const noexcept {
+    return Description.VarArgs;
+  }
+
+  [[nodiscard]] std::span<const ByValCopyAssignment> byValCopies() const noexcept {
+    return Description.ByValCopies;
+  }
+
+  [[nodiscard]] const std::shared_ptr<const RegisterMask> &preservedMask() const noexcept {
+    return Description.PreservedMask;
+  }
+
+  [[nodiscard]] const MachineCallTarget *callee() const noexcept {
+    return Description.Callee ? &*Description.Callee : nullptr;
+  }
+
+  [[nodiscard]] std::uint64_t callSiteID() const noexcept {
+    return Description.CallSiteID;
+  }
+
+  [[nodiscard]] TailCallKind tailDecision() const noexcept {
+    return Description.TailDecision;
+  }
+
+  [[nodiscard]] std::string_view tailRejectionReason() const noexcept {
+    return Description.TailRejectionReason;
+  }
+
+private:
+  explicit CallLoweringPlan(CallLoweringPlanDesc Description)
+      : Description(std::move(Description)) {}
+
+  CallLoweringPlanDesc Description;
+};
+
+class TargetCallLowering {
+public:
+  virtual ~TargetCallLowering() = default;
+
+  [[nodiscard]] Expected<void> lowerFormalArguments(MachineIRBuilder &Builder,
+                                                    const FormalArgumentRequest &Request) const;
+  [[nodiscard]] Expected<void> lowerCall(MachineIRBuilder &Builder,
+                                         const CallLoweringRequest &Request) const;
+  [[nodiscard]] Expected<void> lowerReturn(MachineIRBuilder &Builder,
+                                           const ReturnLoweringRequest &Request) const;
+
+  [[nodiscard]] virtual Expected<CallLoweringPlan>
+  planFormalArguments(const FormalArgumentRequest &Request) const = 0;
+  [[nodiscard]] virtual Expected<CallLoweringPlan>
+  planCall(const CallLoweringRequest &Request) const = 0;
+  [[nodiscard]] virtual Expected<CallLoweringPlan>
+  planReturn(const ReturnLoweringRequest &Request) const = 0;
+  [[nodiscard]] virtual Expected<void> emitPlan(MachineIRBuilder &Builder,
+                                                const CallLoweringPlan &Plan) const = 0;
+};
+
+} // namespace rcc
+
+#endif // RCC_CODEGEN_TARGETCALLLOWERING_H
diff --git a/backend/include/rcc/Target/RISCV/RISCVCallLowering.h b/backend/include/rcc/Target/RISCV/RISCVCallLowering.h
new file mode 100644
index 0000000..445c922
--- /dev/null
+++ b/backend/include/rcc/Target/RISCV/RISCVCallLowering.h
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef RCC_TARGET_RISCV_RISCVCALLLOWERING_H
+#define RCC_TARGET_RISCV_RISCVCALLLOWERING_H
+
+#include "rcc/CodeGen/TargetCallLowering.h"
+#include "rcc/Target/RISCV/RISCVInstructions.h"
+
+#include <cstdint>
+
+namespace rcc::riscv {
+
+enum class CallTargetFlag : std::uint32_t {
+  DirectCall = 1U << 0U,
+};
+
+enum class CallStackObjectFlag : std::uint64_t {
+  IncomingArgument = 1ULL << 0U,
+  OutgoingArgument = 1ULL << 1U,
+  ByValCopy = 1ULL << 2U,
+  VarArgSaveArea = 1ULL << 3U,
+  VarArgAlignmentPadding = 1ULL << 4U,
+};
+
+enum class CallValueTransform : std::uint8_t {
+  Full,
+  AnyExtend,
+  SignExtend,
+  ZeroExtend,
+  Truncate,
+  Bitcast,
+};
+
+[[nodiscard]] constexpr CallingConventionID
+callingConventionID(CallingConvention Convention) noexcept {
+  return CallingConventionID::fromValue(static_cast<std::uint32_t>(Convention));
+}
+
+[[nodiscard]] const TargetCallLowering &callLowering() noexcept;
+
+} // namespace rcc::riscv
+
+#endif // RCC_TARGET_RISCV_RISCVCALLLOWERING_H
diff --git a/backend/lib/CodeGen/CMakeLists.txt b/backend/lib/CodeGen/CMakeLists.txt
index 34e9ef6..5a12055 100644
--- a/backend/lib/CodeGen/CMakeLists.txt
+++ b/backend/lib/CodeGen/CMakeLists.txt
@@ -3,6 +3,7 @@
 set(
   RCCBackendCodeGenSources
   CompilationUnit.cpp
+  GenericOpcodes.cpp
   GenericConstant.cpp
   InstructionDescriptor.cpp
   LowLevelType.cpp
@@ -19,11 +20,13 @@ set(
   MachineFunctionCloner.cpp
   MachineIRTypes.cpp
   MachineIRBuilder.cpp
+  MachineAnalyses.cpp
   MachineInstr.cpp
   MachineJumpTableInfo.cpp
   MachineMemOperand.cpp
   MachineMetadata.cpp
   MachineOperand.cpp
+  MachinePass.cpp
   MachineRegisterInfo.cpp
   MachineVerifier.cpp
   MachineFunctionProperties.cpp
@@ -31,6 +34,7 @@ set(
   Register.cpp
   RegisterMask.cpp
   TargetConstant.cpp
+  TargetCallLowering.cpp
   TargetDescription.cpp
   TargetFunctionState.cpp
   TargetMIRTextInfo.cpp
@@ -39,6 +43,7 @@ set(
 set(
   RCCBackendCodeGenHeaders
   "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/CompilationUnit.h"
+  "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/GenericOpcodes.h"
   "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/GenericConstant.h"
   "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/InstructionDescriptor.h"
   "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/LowLevelType.h"
@@ -55,11 +60,13 @@ set(
   "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/MachineFunctionCloner.h"
   "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/MachineIRTypes.h"
   "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/MachineIRBuilder.h"
+  "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/MachineAnalyses.h"
   "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/MachineInstr.h"
   "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/MachineJumpTableInfo.h"
   "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/MachineMemOperand.h"
   "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/MachineMetadata.h"
   "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/MachineOperand.h"
+  "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/MachinePass.h"
   "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/MachineRegisterInfo.h"
   "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/MachineVerifier.h"
   "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/MachineFunctionProperties.h"
@@ -68,6 +75,7 @@ set(
   "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/RegisterMask.h"
   "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/StableID.h"
   "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/TargetConstant.h"
+  "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/TargetCallLowering.h"
   "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/TargetDescription.h"
   "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/TargetFunctionState.h"
   "${RCC_BACKEND_SOURCE_DIR}/include/rcc/CodeGen/TargetMIRTextInfo.h"
@@ -104,6 +112,7 @@ install(
 
 rcc_backend_register_format_files(
   "${CMAKE_CURRENT_SOURCE_DIR}/CompilationUnit.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/GenericOpcodes.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/GenericConstant.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/InstructionDescriptor.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/LowLevelType.cpp"
@@ -120,11 +129,13 @@ rcc_backend_register_format_files(
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineFunctionCloner.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineIRTypes.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineIRBuilder.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/MachineAnalyses.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineInstr.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineJumpTableInfo.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineMemOperand.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineMetadata.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineOperand.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/MachinePass.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineRegisterInfo.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineVerifier.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineFunctionProperties.cpp"
@@ -132,6 +143,7 @@ rcc_backend_register_format_files(
   "${CMAKE_CURRENT_SOURCE_DIR}/Register.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/RegisterMask.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/TargetConstant.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/TargetCallLowering.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/TargetDescription.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/TargetFunctionState.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/TargetMIRTextInfo.cpp"
@@ -140,6 +152,7 @@ rcc_backend_register_format_files(
 )
 rcc_backend_register_tidy_files(
   "${CMAKE_CURRENT_SOURCE_DIR}/CompilationUnit.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/GenericOpcodes.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/GenericConstant.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/InstructionDescriptor.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/LowLevelType.cpp"
@@ -156,11 +169,13 @@ rcc_backend_register_tidy_files(
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineFunctionCloner.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineIRTypes.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineIRBuilder.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/MachineAnalyses.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineInstr.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineJumpTableInfo.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineMemOperand.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineMetadata.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineOperand.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/MachinePass.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineRegisterInfo.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineVerifier.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineFunctionProperties.cpp"
@@ -168,6 +183,7 @@ rcc_backend_register_tidy_files(
   "${CMAKE_CURRENT_SOURCE_DIR}/Register.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/RegisterMask.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/TargetConstant.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/TargetCallLowering.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/TargetDescription.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/TargetFunctionState.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/TargetMIRTextInfo.cpp"
diff --git a/backend/lib/CodeGen/GenericOpcodes.cpp b/backend/lib/CodeGen/GenericOpcodes.cpp
new file mode 100644
index 0000000..0b0e0fe
--- /dev/null
+++ b/backend/lib/CodeGen/GenericOpcodes.cpp
@@ -0,0 +1,1498 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "rcc/CodeGen/GenericOpcodes.h"
+
+#include "rcc/CodeGen/MachineInstr.h"
+#include "rcc/CodeGen/MachineMemOperand.h"
+#include "rcc/CodeGen/MachineRegisterInfo.h"
+
+#include <algorithm>
+#include <array>
+#include <bit>
+#include <cstddef>
+#include <cstdint>
+#include <exception>
+#include <initializer_list>
+#include <limits>
+#include <optional>
+#include <ranges>
+#include <span>
+#include <string>
+#include <string_view>
+#include <utility>
+#include <vector>
+
+namespace rcc {
+namespace {
+
+using GO = GenericOpcode;
+
+[[nodiscard]] Expected<void> verifyGenericExplicitOperands(Opcode InstructionOpcode,
+                                                           std::span<const MachineOperand> Operands,
+                                                           const MachineRegisterInfo &RegInfo);
+[[nodiscard]] Expected<void> verifyGenericInstructionSemantics(const MachineInstr &Instruction,
+                                                               const MachineRegisterInfo &RegInfo);
+
+[[nodiscard]] LLTKindSet anyValueKinds() {
+  return {LLT::Kind::AnyScalar,   LLT::Kind::Integer,      LLT::Kind::Float,
+          LLT::Kind::Pointer,     LLT::Kind::VectorAny,    LLT::Kind::VectorInteger,
+          LLT::Kind::VectorFloat, LLT::Kind::VectorPointer};
+}
+
+[[nodiscard]] LLTKindSet integerKinds() {
+  return {LLT::Kind::AnyScalar, LLT::Kind::Integer, LLT::Kind::VectorAny, LLT::Kind::VectorInteger};
+}
+
+[[nodiscard]] LLTKindSet scalarIntegerKinds() {
+  return {LLT::Kind::AnyScalar, LLT::Kind::Integer};
+}
+
+[[nodiscard]] LLTKindSet scalarValueKinds() {
+  return {LLT::Kind::AnyScalar, LLT::Kind::Integer, LLT::Kind::Float, LLT::Kind::Pointer};
+}
+
+[[nodiscard]] LLTKindSet floatingKinds() {
+  return {LLT::Kind::AnyScalar, LLT::Kind::Float, LLT::Kind::VectorAny, LLT::Kind::VectorFloat};
+}
+
+[[nodiscard]] LLTKindSet scalarFloatingKinds() {
+  return {LLT::Kind::AnyScalar, LLT::Kind::Float};
+}
+
+[[nodiscard]] LLTKindSet pointerKinds() {
+  return {LLT::Kind::Pointer, LLT::Kind::VectorPointer};
+}
+
+[[nodiscard]] LLTKindSet scalarPointerKinds() {
+  return {LLT::Kind::Pointer};
+}
+
+[[nodiscard]] LLTKindSet vectorKinds() {
+  return {LLT::Kind::VectorAny, LLT::Kind::VectorInteger, LLT::Kind::VectorFloat,
+          LLT::Kind::VectorPointer};
+}
+
+[[nodiscard]] OperandKindSet allOperandKinds() {
+  return {MachineOperand::Kind::Register,
+          MachineOperand::Kind::Immediate,
+          MachineOperand::Kind::IntegerImmediate,
+          MachineOperand::Kind::FloatingImmediate,
+          MachineOperand::Kind::BasicBlock,
+          MachineOperand::Kind::FrameIndex,
+          MachineOperand::Kind::ConstantPoolIndex,
+          MachineOperand::Kind::JumpTableIndex,
+          MachineOperand::Kind::GlobalSymbol,
+          MachineOperand::Kind::ExternalSymbol,
+          MachineOperand::Kind::BlockAddress,
+          MachineOperand::Kind::RegisterMask,
+          MachineOperand::Kind::LiveOutRegisterMask,
+          MachineOperand::Kind::Metadata,
+          MachineOperand::Kind::TargetIndex,
+          MachineOperand::Kind::MCSymbol,
+          MachineOperand::Kind::CFIIndex,
+          MachineOperand::Kind::Intrinsic,
+          MachineOperand::Kind::Predicate,
+          MachineOperand::Kind::ShuffleMask,
+          MachineOperand::Kind::DebugInstrRef,
+          MachineOperand::Kind::LaneMask};
+}
+
+[[nodiscard]] OperandDescriptor typedRegister(RegisterOperandRole Role, LLTKindSet Kinds,
+                                              std::uint16_t Group) {
+  OperandDescriptor Result;
+  Result.Kinds = {MachineOperand::Kind::Register};
+  Result.RegisterRole = Role;
+  Result.TypeConstraint = OperandTypeConstraint{std::move(Kinds), Group};
+  return Result;
+}
+
+[[nodiscard]] OperandDescriptor untypedRegister(RegisterOperandRole Role, bool AllowSubReg = true) {
+  OperandDescriptor Result;
+  Result.Kinds = {MachineOperand::Kind::Register};
+  Result.RegisterRole = Role;
+  Result.AllowSubReg = AllowSubReg;
+  return Result;
+}
+
+[[nodiscard]] OperandDescriptor operand(OperandKindSet Kinds) {
+  OperandDescriptor Result;
+  Result.Kinds = Kinds;
+  if (Kinds.contains(MachineOperand::Kind::Register)) {
+    Result.RegisterRole = RegisterOperandRole::Any;
+    Result.AllowSubReg = true;
+  }
+  return Result;
+}
+
+[[nodiscard]] OperandDescriptor kind(MachineOperand::Kind Kind) {
+  return operand(OperandKindSet{Kind});
+}
+
+[[nodiscard]] OperandDescriptor immediate() {
+  return operand({MachineOperand::Kind::Immediate, MachineOperand::Kind::IntegerImmediate});
+}
+
+[[nodiscard]] OperandDescriptor symbol() {
+  return operand({MachineOperand::Kind::GlobalSymbol, MachineOperand::Kind::ExternalSymbol,
+                  MachineOperand::Kind::MCSymbol});
+}
+
+[[nodiscard]] OperandDescriptor anyOperand() {
+  return operand(allOperandKinds());
+}
+
+[[nodiscard]] OperandDescriptor repeated(OperandDescriptor Descriptor) {
+  Descriptor.VariadicGroup = true;
+  return Descriptor;
+}
+
+class DescriptorRegistry final {
+public:
+  DescriptorRegistry() {
+    Descriptors.reserve(CorePseudoOpcodeCount + GenericOpcodeCount);
+    Configured.reserve(CorePseudoOpcodeCount + GenericOpcodeCount);
+#define RCC_CORE_OPCODE(Name) add(GO::Name, #Name, false);
+#define RCC_GENERIC_OPCODE(Name) add(GO::Name, #Name, true);
+#include "rcc/CodeGen/GenericOpcode.def"
+#undef RCC_GENERIC_OPCODE
+#undef RCC_CORE_OPCODE
+  }
+
+  void configure(std::initializer_list<GO> Opcodes, std::vector<OperandDescriptor> Operands,
+                 std::size_t NumDefs, std::initializer_list<InstructionFlag> Flags = {},
+                 bool Variadic = false, std::size_t MinimumRepetitions = 0,
+                 bool RequiresMemoryOperands = false, PseudoOwner Owner = PseudoOwner::None,
+                 PipelineStage Deadline = PipelineStage::Emission,
+                 bool AllowExtraImplicitOperands = false) {
+    for (const GO OpcodeValue : Opcodes) {
+      const std::size_t Index = index(OpcodeValue);
+      if (Index >= Descriptors.size() || Configured[Index])
+        std::terminate();
+      Configured[Index] = true;
+      InstructionDescriptor &Descriptor = Descriptors[Index];
+      Descriptor.Operands = Operands;
+      Descriptor.NumExplicitDefs = NumDefs;
+      Descriptor.Variadic = Variadic;
+      Descriptor.MinimumVariadicRepetitions = MinimumRepetitions;
+      Descriptor.Flags = {};
+      Descriptor.Flags.set(isGenericOpcode(Descriptor.InstructionOpcode) ? InstructionFlag::Generic
+                                                                         : InstructionFlag::Pseudo);
+      Descriptor.Flags.set(InstructionFlag::AllowedPreLegalizer);
+      for (const InstructionFlag Flag : Flags)
+        Descriptor.Flags.set(Flag);
+      Descriptor.RequiresMemoryOperands = RequiresMemoryOperands;
+      Descriptor.Owner = Owner;
+      Descriptor.Deadline = Deadline;
+      Descriptor.AllowExtraImplicitOperands = AllowExtraImplicitOperands;
+      if (isGenericOpcode(Descriptor.InstructionOpcode)) {
+        Descriptor.VerifyExplicitOperands = &verifyGenericExplicitOperands;
+        Descriptor.VerifyInstructionSemantics = &verifyGenericInstructionSemantics;
+      }
+    }
+  }
+
+  void addFlag(std::initializer_list<GO> Opcodes, InstructionFlag Flag) {
+    for (const GO OpcodeValue : Opcodes) {
+      const std::size_t Index = index(OpcodeValue);
+      if (Index >= Descriptors.size() || !Configured[Index])
+        std::terminate();
+      Descriptors[Index].Flags.set(Flag);
+    }
+  }
+
+  void tie(GO OpcodeValue, std::size_t Left, std::size_t Right) {
+    InstructionDescriptor &Descriptor = Descriptors[index(OpcodeValue)];
+    if (!Configured[index(OpcodeValue)] || Left >= Descriptor.Operands.size() ||
+        Right >= Descriptor.Operands.size()) {
+      std::terminate();
+    }
+    Descriptor.Operands[Left].DefaultTiedOperand = Right;
+    Descriptor.Operands[Right].DefaultTiedOperand = Left;
+  }
+
+  [[nodiscard]] std::vector<InstructionDescriptor> take() {
+    if (!std::ranges::all_of(Configured, [](bool Value) { return Value; }))
+      std::terminate();
+    return std::move(Descriptors);
+  }
+
+private:
+  static std::size_t index(GO OpcodeValue) {
+    const std::size_t Value = static_cast<std::size_t>(OpcodeValue);
+    if (Value < static_cast<std::size_t>(GO::CORE_PSEUDO_END))
+      return Value - static_cast<std::size_t>(GO::PHI);
+    return CorePseudoOpcodeCount + Value - static_cast<std::size_t>(GO::G_ASSERT_SEXT);
+  }
+
+  void add(GO OpcodeValue, std::string_view Name, bool IsGeneric) {
+    InstructionDescriptor Descriptor;
+    Descriptor.InstructionOpcode = opcode(OpcodeValue);
+    Descriptor.Name = Name;
+    if (IsGeneric != isGenericOpcode(Descriptor.InstructionOpcode))
+      std::terminate();
+    Descriptors.push_back(std::move(Descriptor));
+    Configured.push_back(false);
+  }
+
+  std::vector<InstructionDescriptor> Descriptors;
+  std::vector<bool> Configured;
+};
+
+[[nodiscard]] Expected<void> semanticError(std::string_view Message) {
+  return makeUnexpected(ErrorCode::VerificationError, std::string(Message));
+}
+
+[[nodiscard]] std::optional<std::int64_t> plainImmediate(const MachineOperand &Operand) noexcept {
+  const auto *Value = Operand.getIf<std::int64_t>();
+  if (Operand.kind() != MachineOperand::Kind::Immediate || Value == nullptr)
+    return std::nullopt;
+  return *Value;
+}
+
+[[nodiscard]] std::uint64_t minimumBitWidth(LLT Type) noexcept {
+  const std::uint64_t Elements = Type.isVector() ? Type.minimumElementCount() : 1;
+  return Elements * Type.scalarBitWidth();
+}
+
+[[nodiscard]] std::uint64_t minimumStoreBytes(LLT Type) noexcept {
+  return (minimumBitWidth(Type) + 7) / 8;
+}
+
+[[nodiscard]] LLT scalarElementType(LLT Type) noexcept {
+  if (const auto Element = Type.scalarElementType())
+    return *Element;
+  return Type;
+}
+
+[[nodiscard]] bool hasSameShape(LLT Left, LLT Right) noexcept {
+  if (Left.isVector() != Right.isVector())
+    return false;
+  if (!Left.isVector())
+    return true;
+  return Left.isScalableVector() == Right.isScalableVector() &&
+         Left.minimumElementCount() == Right.minimumElementCount();
+}
+
+[[nodiscard]] bool isI1(LLT Type) noexcept {
+  return Type.isIntegerOrIntegerVector() && Type.scalarBitWidth() == 1;
+}
+
+[[nodiscard]] Expected<void> requireSameShape(LLT Left, LLT Right, std::string_view Message) {
+  if (!hasSameShape(Left, Right))
+    return semanticError(Message);
+  return {};
+}
+
+[[nodiscard]] Expected<void> requireI1WithShape(LLT Condition, LLT Value,
+                                                bool AllowScalarCondition) {
+  if (!isI1(Condition))
+    return semanticError("generic condition or status result must use an i1 LLT");
+  if (AllowScalarCondition && !Condition.isVector())
+    return {};
+  return requireSameShape(Condition, Value,
+                          "generic condition or status vector shape does not match its value");
+}
+
+[[nodiscard]] Expected<void> verifyGenericExplicitOperands(Opcode InstructionOpcode,
+                                                           std::span<const MachineOperand> Operands,
+                                                           const MachineRegisterInfo &RegInfo) {
+  std::vector<std::optional<LLT>> Types(Operands.size());
+  bool SawNonDefinition = false;
+  for (std::size_t Index = 0; Index < Operands.size(); ++Index) {
+    const MachineOperand &Operand = Operands[Index];
+    if (!Operand.isRegister()) {
+      SawNonDefinition = true;
+      continue;
+    }
+
+    if (Operand.isDef() == Operand.isUse())
+      return semanticError("generic register operand must be either a pure definition or use");
+    if (Operand.isDef()) {
+      if (SawNonDefinition)
+        return semanticError("generic register definitions must form the explicit operand prefix");
+    } else {
+      SawNonDefinition = true;
+      if (Operand.registerFlags().has(RegisterOperandFlag::Undef))
+        return semanticError("generic virtual-register uses cannot carry the undef flag");
+    }
+
+    const Register *Reg = Operand.getIf<Register>();
+    if (Reg == nullptr || !Reg->isVirtual())
+      return semanticError("generic instruction register operands must be virtual registers");
+    auto Info = RegInfo.virtualRegisterInfo(*Reg);
+    if (!Info)
+      return std::unexpected(Info.error());
+    if (!Info->get().Type)
+      return semanticError("generic virtual register is missing its LLT");
+    Types[Index] = *Info->get().Type;
+  }
+
+  const auto TypeAt = [&Types](std::size_t Index) -> LLT { return *Types[Index]; };
+  const GO Generic = static_cast<GO>(InstructionOpcode.value());
+
+  const auto VerifyWidthChange = [&](bool IsExtension) -> Expected<void> {
+    const LLT Dst = TypeAt(0);
+    const LLT Src = TypeAt(1);
+    if (auto Shape =
+            requireSameShape(Dst, Src, "generic width conversion must preserve vector shape");
+        !Shape) {
+      return Shape;
+    }
+    if ((IsExtension && Dst.scalarBitWidth() <= Src.scalarBitWidth()) ||
+        (!IsExtension && Dst.scalarBitWidth() >= Src.scalarBitWidth())) {
+      return semanticError(IsExtension
+                               ? "generic extension destination must be wider than its source"
+                               : "generic truncation destination must be narrower than its source");
+    }
+    return {};
+  };
+
+  const auto VerifyImmediateBitWidth = [&](std::size_t ImmediateIndex, std::size_t TypeIndex,
+                                           bool StrictlySmaller) -> Expected<void> {
+    const auto Value = plainImmediate(Operands[ImmediateIndex]);
+    if (!Value || *Value <= 0)
+      return semanticError("generic bit-width immediate must be a positive machine immediate");
+    const std::uint64_t Width = TypeAt(TypeIndex).scalarBitWidth();
+    if ((StrictlySmaller && static_cast<std::uint64_t>(*Value) >= Width) ||
+        (!StrictlySmaller && static_cast<std::uint64_t>(*Value) > Width)) {
+      return semanticError("generic bit-width immediate exceeds its register element width");
+    }
+    return {};
+  };
+
+  switch (Generic) {
+  case GO::G_ASSERT_SEXT:
+  case GO::G_ASSERT_ZEXT:
+  case GO::G_SEXT_INREG:
+    return VerifyImmediateBitWidth(2, 1, true);
+  case GO::G_ASSERT_ALIGN: {
+    const auto AlignmentValue = plainImmediate(Operands[2]);
+    if (!AlignmentValue || *AlignmentValue <= 0 ||
+        !std::has_single_bit(static_cast<std::uint64_t>(*AlignmentValue))) {
+      return semanticError("G_ASSERT_ALIGN requires a positive power-of-two alignment");
+    }
+    return {};
+  }
+  case GO::G_CONSTANT: {
+    if (const auto *Payload = Operands[1].getIf<IntegerImmediateOperand>();
+        Payload != nullptr && Payload->Value.bitWidth() != TypeAt(0).scalarBitWidth()) {
+      return semanticError("G_CONSTANT integer width must match its destination LLT");
+    }
+    return {};
+  }
+  case GO::G_FCONSTANT: {
+    const auto *Payload = Operands[1].getIf<FloatingImmediateOperand>();
+    if (Payload == nullptr || Payload->Bits.semantics() != TypeAt(0).floatSemantics())
+      return semanticError("G_FCONSTANT semantics must match its destination LLT");
+    return {};
+  }
+  case GO::G_BITCAST: {
+    const LLT Dst = TypeAt(0);
+    const LLT Src = TypeAt(1);
+    if (Dst.isPointerOrPointerVector() != Src.isPointerOrPointerVector())
+      return semanticError("G_BITCAST cannot cross the pointer/non-pointer boundary");
+    if (minimumBitWidth(Dst) != minimumBitWidth(Src) ||
+        Dst.isScalableVector() != Src.isScalableVector()) {
+      return semanticError("G_BITCAST source and destination sizes must match");
+    }
+    if (Dst == Src)
+      return semanticError("G_BITCAST must change the LLT");
+    return {};
+  }
+  case GO::G_INTTOPTR:
+  case GO::G_PTRTOINT:
+    return requireSameShape(TypeAt(0), TypeAt(1),
+                            "pointer/integer conversion must preserve vector shape");
+  case GO::G_ADDRSPACE_CAST: {
+    const LLT Dst = TypeAt(0);
+    const LLT Src = TypeAt(1);
+    if (auto Shape = requireSameShape(Dst, Src, "G_ADDRSPACE_CAST must preserve vector shape");
+        !Shape) {
+      return Shape;
+    }
+    if (Dst.addressSpace() == Src.addressSpace())
+      return semanticError("G_ADDRSPACE_CAST must change the address space");
+    return {};
+  }
+  case GO::G_ANYEXT:
+  case GO::G_SEXT:
+  case GO::G_ZEXT:
+  case GO::G_FPEXT:
+    return VerifyWidthChange(true);
+  case GO::G_TRUNC:
+  case GO::G_TRUNC_SSAT_S:
+  case GO::G_TRUNC_SSAT_U:
+  case GO::G_TRUNC_USAT_U:
+  case GO::G_FPTRUNC:
+    return VerifyWidthChange(false);
+  case GO::G_PTR_ADD:
+  case GO::G_PTRMASK:
+    return requireSameShape(TypeAt(1), TypeAt(2),
+                            "pointer arithmetic operands must have matching scalar/vector shape");
+  case GO::G_ICMP:
+  case GO::G_FCMP:
+  case GO::G_STRICT_FCMP:
+  case GO::G_STRICT_FCMPS: {
+    const PredicateOperand *Predicate = Operands[1].getIf<PredicateOperand>();
+    if (Predicate == nullptr || ((Generic == GO::G_ICMP) != Predicate->isInteger())) {
+      return semanticError("generic comparison predicate kind does not match its opcode");
+    }
+    return requireI1WithShape(TypeAt(0), TypeAt(2), false);
+  }
+  case GO::G_SCMP:
+  case GO::G_UCMP:
+    if (TypeAt(0).scalarBitWidth() < 2)
+      return semanticError("G_SCMP/G_UCMP result elements must be at least two bits wide");
+    return requireSameShape(TypeAt(0), TypeAt(1),
+                            "G_SCMP/G_UCMP must preserve scalar/vector shape");
+  case GO::G_SELECT:
+    return requireI1WithShape(TypeAt(1), TypeAt(0), true);
+  case GO::G_UADDO:
+  case GO::G_USUBO:
+  case GO::G_SADDO:
+  case GO::G_SSUBO:
+  case GO::G_UMULO:
+  case GO::G_SMULO:
+  case GO::G_UADDE:
+  case GO::G_USUBE:
+  case GO::G_SADDE:
+  case GO::G_SSUBE:
+    return requireI1WithShape(TypeAt(1), TypeAt(0), false);
+  case GO::G_CTTZ:
+  case GO::G_CTTZ_ZERO_POISON:
+  case GO::G_CTLZ:
+  case GO::G_CTLZ_ZERO_POISON:
+  case GO::G_CTLS:
+  case GO::G_CTPOP:
+    return requireSameShape(TypeAt(0), TypeAt(1),
+                            "generic bit-count operation must preserve scalar/vector shape");
+  case GO::G_BSWAP:
+    if ((TypeAt(0).scalarBitWidth() % 16) != 0)
+      return semanticError("G_BSWAP element width must be a multiple of 16 bits");
+    return {};
+  case GO::G_FPTOSI:
+  case GO::G_FPTOUI:
+  case GO::G_FPTOSI_SAT:
+  case GO::G_FPTOUI_SAT:
+  case GO::G_SITOFP:
+  case GO::G_UITOFP:
+  case GO::G_LROUND:
+  case GO::G_LLROUND:
+    return requireSameShape(TypeAt(0), TypeAt(1),
+                            "generic numeric conversion must preserve scalar/vector shape");
+  case GO::G_FCOPYSIGN:
+    return requireSameShape(TypeAt(0), TypeAt(2),
+                            "G_FCOPYSIGN operands must have matching scalar/vector shape");
+  case GO::G_IS_FPCLASS: {
+    if (auto Shape = requireI1WithShape(TypeAt(0), TypeAt(1), false); !Shape)
+      return Shape;
+    const auto Classes = plainImmediate(Operands[2]);
+    if (!Classes || *Classes < 0 || *Classes > 0x3ff)
+      return semanticError("G_IS_FPCLASS class mask must fit the supported ten-bit mask");
+    return {};
+  }
+  case GO::G_FPOWI:
+  case GO::G_FLDEXP:
+  case GO::G_STRICT_FLDEXP:
+    return requireSameShape(TypeAt(0), TypeAt(2),
+                            "floating operation exponent must match the result vector shape");
+  case GO::G_FFREXP:
+    return requireSameShape(TypeAt(0), TypeAt(1),
+                            "G_FFREXP mantissa and exponent results must have matching shape");
+  case GO::G_MERGE_VALUES: {
+    if (TypeAt(0).isVector() || TypeAt(1).isVector())
+      return semanticError("G_MERGE_VALUES only merges scalar values");
+    if (minimumBitWidth(TypeAt(0)) != minimumBitWidth(TypeAt(1)) * (Operands.size() - 1))
+      return semanticError("G_MERGE_VALUES source widths do not fill the destination");
+    return {};
+  }
+  case GO::G_UNMERGE_VALUES: {
+    const std::size_t DestinationCount = Operands.size() - 1;
+    const LLT Dst = TypeAt(0);
+    const LLT Src = TypeAt(DestinationCount);
+    if (minimumBitWidth(Src) != minimumBitWidth(Dst) * DestinationCount)
+      return semanticError("G_UNMERGE_VALUES destination widths do not cover the source");
+    if (Dst.isVector() && (!Src.isVector() || Dst.isScalableVector() != Src.isScalableVector() ||
+                           scalarElementType(Dst) != scalarElementType(Src))) {
+      return semanticError("vector G_UNMERGE_VALUES operands have incompatible element types");
+    }
+    return {};
+  }
+  case GO::G_EXTRACT: {
+    const auto Offset = plainImmediate(Operands[2]);
+    const std::uint64_t DstBits = minimumBitWidth(TypeAt(0));
+    const std::uint64_t SrcBits = minimumBitWidth(TypeAt(1));
+    if (!Offset || *Offset < 0 || DstBits >= SrcBits ||
+        static_cast<std::uint64_t>(*Offset) > SrcBits - DstBits) {
+      return semanticError("G_EXTRACT offset and result width must stay inside its source");
+    }
+    return {};
+  }
+  case GO::G_INSERT: {
+    const auto Offset = plainImmediate(Operands[3]);
+    const std::uint64_t DstBits = minimumBitWidth(TypeAt(0));
+    const std::uint64_t InsertBits = minimumBitWidth(TypeAt(2));
+    if (!Offset || *Offset < 0 || InsertBits >= DstBits ||
+        static_cast<std::uint64_t>(*Offset) > DstBits - InsertBits) {
+      return semanticError("G_INSERT offset and inserted width must stay inside its result");
+    }
+    return {};
+  }
+  case GO::G_BUILD_VECTOR:
+  case GO::G_BUILD_VECTOR_TRUNC: {
+    const LLT Dst = TypeAt(0);
+    const LLT Src = TypeAt(1);
+    if (!Dst.isVector() || Dst.isScalableVector() || Src.isVector())
+      return semanticError("G_BUILD_VECTOR requires a fixed vector result and scalar sources");
+    if (Dst.minimumElementCount() != Operands.size() - 1)
+      return semanticError("G_BUILD_VECTOR source count must equal the result lane count");
+    const LLT Element = scalarElementType(Dst);
+    if (Generic == GO::G_BUILD_VECTOR && Element != Src)
+      return semanticError("G_BUILD_VECTOR source LLT must equal the result element LLT");
+    if (Generic == GO::G_BUILD_VECTOR_TRUNC && Src.scalarBitWidth() <= Element.scalarBitWidth())
+      return semanticError("G_BUILD_VECTOR_TRUNC sources must be wider than result elements");
+    return {};
+  }
+  case GO::G_CONCAT_VECTORS: {
+    const LLT Dst = TypeAt(0);
+    const LLT Src = TypeAt(1);
+    if (!Dst.isVector() || !Src.isVector() || Dst.isScalableVector() != Src.isScalableVector() ||
+        scalarElementType(Dst) != scalarElementType(Src) ||
+        Dst.minimumElementCount() != Src.minimumElementCount() * (Operands.size() - 1)) {
+      return semanticError("G_CONCAT_VECTORS operands do not exactly tile the result vector");
+    }
+    return {};
+  }
+  case GO::G_VSCALE: {
+    const auto *Scale = Operands[1].getIf<IntegerImmediateOperand>();
+    if (TypeAt(0).isVector() || Scale == nullptr || Scale->Value.isZero() ||
+        Scale->Value.bitWidth() != TypeAt(0).scalarBitWidth()) {
+      return semanticError("G_VSCALE requires a nonzero typed constant matching a scalar result");
+    }
+    return {};
+  }
+  case GO::G_SHL:
+  case GO::G_LSHR:
+  case GO::G_ASHR:
+  case GO::G_ROTR:
+  case GO::G_ROTL:
+  case GO::G_USHLSAT:
+  case GO::G_SSHLSAT:
+  case GO::G_FSHL:
+  case GO::G_FSHR:
+    return requireSameShape(TypeAt(1), TypeAt(Operands.size() - 1),
+                            "shift amount must match the shifted value's scalar/vector shape");
+  case GO::G_INSERT_SUBVECTOR:
+  case GO::G_EXTRACT_SUBVECTOR: {
+    const bool IsInsert = Generic == GO::G_INSERT_SUBVECTOR;
+    const LLT Outer = TypeAt(IsInsert ? 0 : 1);
+    const LLT Inner = TypeAt(IsInsert ? 2 : 0);
+    const auto Index = plainImmediate(Operands[IsInsert ? 3 : 2]);
+    if (!Outer.isVector() || !Inner.isVector() ||
+        scalarElementType(Outer) != scalarElementType(Inner) || !Index || *Index < 0) {
+      return semanticError("subvector operation has incompatible vector types or index");
+    }
+    if ((!Outer.isScalableVector() && Inner.isScalableVector()) ||
+        Inner.minimumElementCount() > Outer.minimumElementCount()) {
+      return semanticError("subvector operation cannot place a larger vector inside a smaller one");
+    }
+    const std::uint64_t Start = static_cast<std::uint64_t>(*Index);
+    const std::uint64_t InnerLength = Inner.minimumElementCount();
+    const std::uint64_t OuterLength = Outer.minimumElementCount();
+    const bool MixedScalability = Outer.isScalableVector() && !Inner.isScalableVector();
+    if ((Start % InnerLength) != 0 || Start >= OuterLength ||
+        (!MixedScalability && Start + InnerLength > OuterLength)) {
+      return semanticError("subvector index is misaligned or outside the containing vector");
+    }
+    return {};
+  }
+  case GO::G_SHUFFLE_VECTOR: {
+    const LLT Dst = TypeAt(0);
+    const LLT Src = TypeAt(1);
+    const auto *Mask = Operands[3].getIf<ShuffleMaskOperand>();
+    if (!Dst.isVector() || !Src.isVector() || Dst.isScalableVector() || Src.isScalableVector() ||
+        scalarElementType(Dst) != scalarElementType(Src) || Mask == nullptr ||
+        Mask->Elements.size() != Dst.minimumElementCount()) {
+      return semanticError("G_SHUFFLE_VECTOR types and mask length are inconsistent");
+    }
+    const std::uint64_t SourceLanes = Src.minimumElementCount();
+    for (const std::int32_t Element : Mask->Elements) {
+      if (Element < ShuffleMaskOperand::Undef ||
+          (Element >= 0 && static_cast<std::uint64_t>(Element) >= 2 * SourceLanes)) {
+        return semanticError("G_SHUFFLE_VECTOR mask contains an invalid lane index");
+      }
+    }
+    return {};
+  }
+  case GO::G_SPLAT_VECTOR: {
+    const LLT Dst = TypeAt(0);
+    const LLT Src = TypeAt(1);
+    if (!Dst.isScalableVector() || Src.isVector() ||
+        scalarElementType(Dst).scalarBitWidth() > Src.scalarBitWidth()) {
+      return semanticError("G_SPLAT_VECTOR requires a scalable result with no wider elements");
+    }
+    return {};
+  }
+  case GO::G_STEP_VECTOR: {
+    const LLT Dst = TypeAt(0);
+    const auto *Step = Operands[1].getIf<IntegerImmediateOperand>();
+    if (!Dst.isScalableVector() || Step == nullptr || Step->Value.isZero() ||
+        Step->Value.isNegative() || Step->Value.bitWidth() != Dst.scalarBitWidth()) {
+      return semanticError("G_STEP_VECTOR step must be a positive typed element-width constant");
+    }
+    return {};
+  }
+  case GO::G_INSERT_VECTOR_ELT: {
+    const LLT Vector = TypeAt(0);
+    if (scalarElementType(Vector) != TypeAt(2) || TypeAt(3).isVector())
+      return semanticError("G_INSERT_VECTOR_ELT element or index LLT is incompatible");
+    return {};
+  }
+  case GO::G_EXTRACT_VECTOR_ELT: {
+    const LLT Vector = TypeAt(1);
+    if (scalarElementType(Vector) != TypeAt(0) || TypeAt(2).isVector())
+      return semanticError("G_EXTRACT_VECTOR_ELT result or index LLT is incompatible");
+    return {};
+  }
+  case GO::G_VECTOR_COMPRESS:
+    return requireI1WithShape(TypeAt(2), TypeAt(0), false);
+  case GO::G_VECREDUCE_SEQ_FADD:
+  case GO::G_VECREDUCE_SEQ_FMUL:
+    if (TypeAt(0).isVector() || TypeAt(1).isVector() || !TypeAt(2).isVector() ||
+        scalarElementType(TypeAt(2)) != TypeAt(0) || TypeAt(0) != TypeAt(1)) {
+      return semanticError("sequential vector reduction accumulator and element LLTs must match");
+    }
+    return {};
+  case GO::G_VECREDUCE_FADD:
+  case GO::G_VECREDUCE_FMUL:
+  case GO::G_VECREDUCE_FMAX:
+  case GO::G_VECREDUCE_FMIN:
+  case GO::G_VECREDUCE_FMAXIMUM:
+  case GO::G_VECREDUCE_FMINIMUM:
+  case GO::G_VECREDUCE_ADD:
+  case GO::G_VECREDUCE_MUL:
+  case GO::G_VECREDUCE_AND:
+  case GO::G_VECREDUCE_OR:
+  case GO::G_VECREDUCE_XOR:
+  case GO::G_VECREDUCE_SMAX:
+  case GO::G_VECREDUCE_SMIN:
+  case GO::G_VECREDUCE_UMAX:
+  case GO::G_VECREDUCE_UMIN:
+    if (TypeAt(0).isVector() || !TypeAt(1).isVector() ||
+        scalarElementType(TypeAt(1)) != TypeAt(0)) {
+      return semanticError("vector reduction result must equal the source element LLT");
+    }
+    return {};
+  case GO::G_SBFX:
+  case GO::G_UBFX:
+    if (TypeAt(0).isVector() || TypeAt(2).isVector() || TypeAt(3).isVector())
+      return semanticError("generic bit-field extraction only supports scalar operands");
+    return {};
+  case GO::G_BRCOND:
+    if (!isI1(TypeAt(0)) || TypeAt(0).isVector())
+      return semanticError("G_BRCOND condition must be a scalar i1 virtual register");
+    return {};
+  case GO::G_BRJT:
+    if (TypeAt(0).isVector() || TypeAt(2).isVector())
+      return semanticError("G_BRJT table pointer and index must be scalar values");
+    return {};
+  case GO::G_INTRINSIC:
+  case GO::G_INTRINSIC_W_SIDE_EFFECTS:
+  case GO::G_INTRINSIC_CONVERGENT:
+  case GO::G_INTRINSIC_CONVERGENT_W_SIDE_EFFECTS: {
+    const auto FirstUse = std::ranges::find_if_not(Operands, [](const MachineOperand &Operand) {
+      return Operand.isRegister() && Operand.isDef();
+    });
+    if (FirstUse == Operands.end() || FirstUse->kind() != MachineOperand::Kind::Intrinsic)
+      return semanticError("generic intrinsic must place its intrinsic ID after all definitions");
+    return {};
+  }
+  case GO::G_INDEXED_LOAD:
+  case GO::G_INDEXED_SEXTLOAD:
+  case GO::G_INDEXED_ZEXTLOAD:
+    if (const auto Mode = plainImmediate(Operands[4]); !Mode || (*Mode != 0 && *Mode != 1))
+      return semanticError("generic indexed-load address mode must be immediate 0 or 1");
+    return {};
+  case GO::G_INDEXED_STORE:
+    if (const auto Mode = plainImmediate(Operands[4]); !Mode || (*Mode != 0 && *Mode != 1))
+      return semanticError("G_INDEXED_STORE address mode must be immediate 0 or 1");
+    return {};
+  case GO::G_ATOMIC_CMPXCHG_WITH_SUCCESS:
+    return requireI1WithShape(TypeAt(1), TypeAt(0), false);
+  case GO::G_FENCE: {
+    const auto Ordering = plainImmediate(Operands[0]);
+    const auto Scope = plainImmediate(Operands[1]);
+    if (!Ordering || *Ordering < 4 || *Ordering > 7 || !Scope || *Scope < 0 ||
+        static_cast<std::uint64_t>(*Scope) > std::numeric_limits<std::uint32_t>::max()) {
+      return semanticError("G_FENCE requires acquire-or-stronger ordering and a uint32 scope");
+    }
+    return {};
+  }
+  case GO::G_PREFETCH: {
+    const auto ReadWrite = plainImmediate(Operands[1]);
+    const auto Locality = plainImmediate(Operands[2]);
+    const auto CacheType = plainImmediate(Operands[3]);
+    if (!ReadWrite || *ReadWrite < 0 || *ReadWrite > 1 || !Locality || *Locality < 0 ||
+        *Locality > 3 || !CacheType || *CacheType < 0 || *CacheType > 1) {
+      return semanticError("G_PREFETCH control operands are outside their defined ranges");
+    }
+    return {};
+  }
+  case GO::G_VAARG: {
+    const auto Align = plainImmediate(Operands[2]);
+    if (!Align || *Align <= 0 || !std::has_single_bit(static_cast<std::uint64_t>(*Align)))
+      return semanticError("G_VAARG alignment must be a positive power of two");
+    return {};
+  }
+  case GO::G_DYN_STACKALLOC: {
+    const auto Align = plainImmediate(Operands[2]);
+    if (!Align || *Align <= 0 || !std::has_single_bit(static_cast<std::uint64_t>(*Align)))
+      return semanticError("G_DYN_STACKALLOC alignment must be a positive power of two");
+    return {};
+  }
+  case GO::G_MEMCPY:
+  case GO::G_MEMMOVE:
+    if (const auto Tail = plainImmediate(Operands[3]); !Tail || (*Tail != 0 && *Tail != 1))
+      return semanticError("generic memory-transfer tail flag must be immediate 0 or 1");
+    return {};
+  case GO::G_MEMSET:
+    if (TypeAt(1).isVector() || TypeAt(1).scalarBitWidth() != 8)
+      return semanticError("G_MEMSET fill value must be a scalar i8 value");
+    if (const auto Tail = plainImmediate(Operands[3]); !Tail || (*Tail != 0 && *Tail != 1))
+      return semanticError("G_MEMSET tail flag must be immediate 0 or 1");
+    return {};
+  case GO::G_BZERO:
+    if (const auto Tail = plainImmediate(Operands[2]); !Tail || (*Tail != 0 && *Tail != 1))
+      return semanticError("G_BZERO tail flag must be immediate 0 or 1");
+    return {};
+  case GO::G_UBSANTRAP: {
+    const auto Kind = plainImmediate(Operands[0]);
+    if (!Kind || *Kind < -128 || *Kind > 127)
+      return semanticError("G_UBSANTRAP kind must fit in a signed eight-bit immediate");
+    return {};
+  }
+  case GO::G_INTRINSIC_FPTRUNC_ROUND: {
+    const auto Rounding = plainImmediate(Operands[2]);
+    if (!Rounding || !((*Rounding >= 0 && *Rounding <= 4) || *Rounding == 7))
+      return semanticError("floating truncation rounding mode is invalid");
+    return VerifyWidthChange(false);
+  }
+  default:
+    return {};
+  }
+}
+
+[[nodiscard]] Expected<void> verifyGenericInstructionSemantics(const MachineInstr &Instruction,
+                                                               const MachineRegisterInfo &RegInfo) {
+  const auto Operands = Instruction.operands();
+  const auto MemoryOperands = Instruction.memOperands();
+  const GO Generic = static_cast<GO>(Instruction.opcode().value());
+
+  const auto TypeAt = [&](std::size_t Index) -> Expected<LLT> {
+    if (Index >= Operands.size())
+      return makeUnexpected(ErrorCode::InternalError,
+                            "generic semantic verifier operand index is out of range");
+    const Register *Reg = Operands[Index].getIf<Register>();
+    if (Reg == nullptr || !Reg->isVirtual())
+      return makeUnexpected(ErrorCode::InternalError,
+                            "generic semantic verifier expected a virtual register");
+    auto Info = RegInfo.virtualRegisterInfo(*Reg);
+    if (!Info)
+      return std::unexpected(Info.error());
+    if (!Info->get().Type)
+      return makeUnexpected(ErrorCode::InternalError,
+                            "generic semantic verifier found a register without an LLT");
+    return *Info->get().Type;
+  };
+
+  const auto VerifyAddress = [&](std::size_t OperandIndex,
+                                 const MachineMemOperand &Memory) -> Expected<void> {
+    auto Type = TypeAt(OperandIndex);
+    if (!Type)
+      return std::unexpected(Type.error());
+    if (!Type->isPointer() || Type->addressSpace() != Memory.description().AddressSpace)
+      return semanticError("generic memory address LLT and MMO address space do not match");
+    return {};
+  };
+
+  enum class SizeRelation : std::uint8_t {
+    Equal,
+    NoLarger,
+    StrictlySmaller,
+  };
+  const auto VerifySize = [&](LLT ValueType, const MachineMemOperand &Memory,
+                              SizeRelation Relation) -> Expected<void> {
+    const MemorySize Size = Memory.description().Size;
+    if (!Size.isKnown())
+      return semanticError("typed generic memory access requires a known MMO size");
+    if (Size.isScalable() != ValueType.isScalableVector())
+      return semanticError("generic value and MMO scalability do not match");
+    const std::uint64_t MemoryBytes = Size.minimumBytes();
+    const std::uint64_t ValueBytes = minimumStoreBytes(ValueType);
+    const bool Valid = Relation == SizeRelation::Equal
+                           ? MemoryBytes == ValueBytes
+                           : (Relation == SizeRelation::NoLarger ? MemoryBytes <= ValueBytes
+                                                                 : MemoryBytes < ValueBytes);
+    if (!Valid)
+      return semanticError("generic memory access size is incompatible with its value LLT");
+    return {};
+  };
+
+  const auto VerifySingleAccess = [&](std::size_t AddressIndex, std::size_t ValueIndex,
+                                      bool MustLoad, bool MustStore,
+                                      SizeRelation Relation) -> Expected<void> {
+    if (MemoryOperands.size() != 1)
+      return semanticError("generic scalar memory instruction requires exactly one MMO");
+    const MachineMemOperand &Memory = *MemoryOperands.front();
+    if (Memory.isLoad() != MustLoad || Memory.isStore() != MustStore)
+      return semanticError("generic instruction and MMO access directions do not match");
+    if (auto Address = VerifyAddress(AddressIndex, Memory); !Address)
+      return Address;
+    auto ValueType = TypeAt(ValueIndex);
+    if (!ValueType)
+      return std::unexpected(ValueType.error());
+    return VerifySize(*ValueType, Memory, Relation);
+  };
+
+  switch (Generic) {
+  case GO::G_LOAD:
+    return VerifySingleAccess(1, 0, true, false, SizeRelation::NoLarger);
+  case GO::G_SEXTLOAD:
+  case GO::G_ZEXTLOAD:
+  case GO::G_FPEXTLOAD:
+    return VerifySingleAccess(1, 0, true, false, SizeRelation::StrictlySmaller);
+  case GO::G_STORE:
+    return VerifySingleAccess(1, 0, false, true, SizeRelation::NoLarger);
+  case GO::G_FPTRUNCSTORE:
+    return VerifySingleAccess(1, 0, false, true, SizeRelation::StrictlySmaller);
+  case GO::G_INDEXED_LOAD:
+    return VerifySingleAccess(2, 0, true, false, SizeRelation::NoLarger);
+  case GO::G_INDEXED_SEXTLOAD:
+  case GO::G_INDEXED_ZEXTLOAD:
+    return VerifySingleAccess(2, 0, true, false, SizeRelation::StrictlySmaller);
+  case GO::G_INDEXED_STORE:
+    return VerifySingleAccess(2, 1, false, true, SizeRelation::NoLarger);
+  case GO::G_ATOMIC_CMPXCHG_WITH_SUCCESS:
+    if (MemoryOperands.size() != 1 ||
+        MemoryOperands.front()->description().AtomicKind != AtomicOperation::CompareExchange)
+      return semanticError("G_ATOMIC_CMPXCHG_WITH_SUCCESS requires one compare-exchange MMO");
+    return VerifySingleAccess(2, 0, true, true, SizeRelation::Equal);
+  case GO::G_ATOMIC_CMPXCHG:
+    if (MemoryOperands.size() != 1 ||
+        MemoryOperands.front()->description().AtomicKind != AtomicOperation::CompareExchange)
+      return semanticError("G_ATOMIC_CMPXCHG requires one compare-exchange MMO");
+    return VerifySingleAccess(1, 0, true, true, SizeRelation::Equal);
+  case GO::G_ATOMICRMW_XCHG:
+  case GO::G_ATOMICRMW_ADD:
+  case GO::G_ATOMICRMW_SUB:
+  case GO::G_ATOMICRMW_AND:
+  case GO::G_ATOMICRMW_NAND:
+  case GO::G_ATOMICRMW_OR:
+  case GO::G_ATOMICRMW_XOR:
+  case GO::G_ATOMICRMW_MAX:
+  case GO::G_ATOMICRMW_MIN:
+  case GO::G_ATOMICRMW_UMAX:
+  case GO::G_ATOMICRMW_UMIN:
+  case GO::G_ATOMICRMW_FADD:
+  case GO::G_ATOMICRMW_FSUB:
+  case GO::G_ATOMICRMW_FMAX:
+  case GO::G_ATOMICRMW_FMIN:
+  case GO::G_ATOMICRMW_FMAXIMUM:
+  case GO::G_ATOMICRMW_FMINIMUM:
+  case GO::G_ATOMICRMW_FMAXIMUMNUM:
+  case GO::G_ATOMICRMW_FMINIMUMNUM:
+  case GO::G_ATOMICRMW_UINC_WRAP:
+  case GO::G_ATOMICRMW_UDEC_WRAP:
+  case GO::G_ATOMICRMW_USUB_COND:
+  case GO::G_ATOMICRMW_USUB_SAT:
+    if (MemoryOperands.size() != 1 ||
+        MemoryOperands.front()->description().AtomicKind != AtomicOperation::ReadModifyWrite)
+      return semanticError("generic atomic RMW requires one read-modify-write MMO");
+    return VerifySingleAccess(1, 0, true, true, SizeRelation::Equal);
+  case GO::G_PREFETCH: {
+    if (MemoryOperands.size() != 1)
+      return semanticError("G_PREFETCH requires exactly one MMO");
+    const auto ReadWrite = plainImmediate(Operands[1]);
+    if (!ReadWrite)
+      return semanticError("G_PREFETCH is missing its validated read/write selector");
+    const MachineMemOperand &Memory = *MemoryOperands.front();
+    if ((*ReadWrite == 0 && (!Memory.isLoad() || Memory.isStore())) ||
+        (*ReadWrite == 1 && (Memory.isLoad() || !Memory.isStore()))) {
+      return semanticError("G_PREFETCH selector and MMO access direction do not match");
+    }
+    return VerifyAddress(0, Memory);
+  }
+  case GO::G_VASTART:
+    if (MemoryOperands.size() != 1 || MemoryOperands.front()->isLoad() ||
+        !MemoryOperands.front()->isStore()) {
+      return semanticError("G_VASTART requires exactly one store-only MMO");
+    }
+    return VerifyAddress(0, *MemoryOperands.front());
+  case GO::G_VAARG: {
+    if (MemoryOperands.size() != 2)
+      return semanticError("G_VAARG requires separate value-load and list-update MMOs");
+    const MachineMemOperand *ValueLoad = nullptr;
+    const MachineMemOperand *ListStore = nullptr;
+    for (const MachineMemOperand *Memory : MemoryOperands) {
+      if (Memory->isLoad() == Memory->isStore()) {
+        return semanticError("G_VAARG MMOs must each describe exactly one access direction");
+      }
+      if (Memory->isLoad())
+        ValueLoad = Memory;
+      else
+        ListStore = Memory;
+      if (auto Address = VerifyAddress(1, *Memory); !Address)
+        return Address;
+    }
+    if (ValueLoad == nullptr || ListStore == nullptr)
+      return semanticError("G_VAARG MMOs must cover both the value load and list update");
+    auto ResultType = TypeAt(0);
+    if (!ResultType)
+      return std::unexpected(ResultType.error());
+    return VerifySize(*ResultType, *ValueLoad, SizeRelation::Equal);
+  }
+  case GO::G_MEMCPY:
+  case GO::G_MEMCPY_INLINE:
+  case GO::G_MEMMOVE: {
+    if (MemoryOperands.size() != 2 || MemoryOperands[0]->isLoad() ||
+        !MemoryOperands[0]->isStore() || !MemoryOperands[1]->isLoad() ||
+        MemoryOperands[1]->isStore()) {
+      return semanticError("generic memory transfer requires store and load MMOs in that order");
+    }
+    if (MemoryOperands[0]->description().Size != MemoryOperands[1]->description().Size)
+      return semanticError("generic memory-transfer MMOs must have identical sizes");
+    if (auto Destination = VerifyAddress(0, *MemoryOperands[0]); !Destination)
+      return Destination;
+    return VerifyAddress(1, *MemoryOperands[1]);
+  }
+  case GO::G_MEMSET:
+  case GO::G_BZERO:
+    if (MemoryOperands.size() != 1 || MemoryOperands.front()->isLoad() ||
+        !MemoryOperands.front()->isStore()) {
+      return semanticError("generic memory fill requires exactly one store-only MMO");
+    }
+    return VerifyAddress(0, *MemoryOperands.front());
+  default:
+    return {};
+  }
+}
+
+void configureCoreOpcodes(DescriptorRegistry &Registry) {
+  const auto RegDef = untypedRegister(RegisterOperandRole::Def);
+  const auto RegUse = untypedRegister(RegisterOperandRole::Use);
+  const auto Any = anyOperand();
+  const auto VariadicAny = repeated(Any);
+  const auto VariadicUse = repeated(RegUse);
+
+  Registry.configure({GO::PHI},
+                     {RegDef, VariadicUse, repeated(kind(MachineOperand::Kind::BasicBlock))}, 1,
+                     {InstructionFlag::Phi}, true, 1, false, PseudoOwner::PhiElimination,
+                     PipelineStage::SSAEliminated);
+  Registry.configure({GO::INLINEASM}, {VariadicAny}, 0,
+                     {InstructionFlag::ProducesCode, InstructionFlag::TerminalEmission,
+                      InstructionFlag::UnmodeledSideEffects},
+                     true, 0, false, PseudoOwner::AsmPrinter, PipelineStage::Emission, true);
+  Registry.configure({GO::INLINEASM_BR}, {VariadicAny}, 0,
+                     {InstructionFlag::ProducesCode, InstructionFlag::TerminalEmission,
+                      InstructionFlag::UnmodeledSideEffects, InstructionFlag::HasSideEffects},
+                     true, 0, false, PseudoOwner::AsmPrinter, PipelineStage::Emission, true);
+  Registry.configure({GO::CFI_INSTRUCTION}, {kind(MachineOperand::Kind::CFIIndex)}, 0,
+                     {InstructionFlag::Meta, InstructionFlag::NotDuplicable});
+  Registry.configure({GO::EH_LABEL, GO::GC_LABEL, GO::ANNOTATION_LABEL},
+                     {kind(MachineOperand::Kind::MCSymbol)}, 0,
+                     {InstructionFlag::Meta, InstructionFlag::NotDuplicable});
+  Registry.configure({GO::KILL}, {VariadicUse}, 0, {InstructionFlag::Meta}, true);
+  Registry.configure({GO::EXTRACT_SUBREG}, {RegDef, RegUse, immediate()}, 1, {}, false, 0, false,
+                     PseudoOwner::PostRAExpansion, PipelineStage::PostRAFinalized);
+  Registry.configure({GO::INSERT_SUBREG}, {RegDef, RegUse, RegUse, immediate()}, 1, {}, false, 0,
+                     false, PseudoOwner::TwoAddressRewrite, PipelineStage::TiedOpsRewritten);
+  Registry.tie(GO::INSERT_SUBREG, 0, 1);
+  Registry.configure({GO::IMPLICIT_DEF}, {RegDef}, 1,
+                     {InstructionFlag::Meta, InstructionFlag::Rematerializable});
+  Registry.configure({GO::INIT_UNDEF}, {RegDef}, 1, {}, false, 0, false,
+                     PseudoOwner::RegisterAllocator, PipelineStage::RegisterAllocated);
+  Registry.configure({GO::SUBREG_TO_REG}, {RegDef, RegUse, immediate()}, 1, {}, false, 0, false,
+                     PseudoOwner::PostRAExpansion, PipelineStage::PostRAFinalized);
+  Registry.configure({GO::COPY_TO_REGCLASS}, {RegDef, RegUse, immediate()}, 1, {}, false, 0, false,
+                     PseudoOwner::RegisterAllocator, PipelineStage::RegisterAllocated);
+  Registry.configure({GO::DBG_VALUE, GO::DBG_VALUE_LIST, GO::DBG_INSTR_REF, GO::DBG_PHI},
+                     {VariadicAny}, 0, {InstructionFlag::Meta}, true);
+  Registry.configure({GO::DBG_LABEL}, {kind(MachineOperand::Kind::Metadata)}, 0,
+                     {InstructionFlag::Meta});
+  Registry.configure({GO::REG_SEQUENCE}, {RegDef, repeated(RegUse), repeated(immediate())}, 1, {},
+                     true, 1, false, PseudoOwner::TwoAddressRewrite,
+                     PipelineStage::TiedOpsRewritten);
+  Registry.configure({GO::COPY}, {RegDef, RegUse}, 1, {}, false, 0, false,
+                     PseudoOwner::PostRAExpansion, PipelineStage::PostRAFinalized);
+  Registry.configure({GO::COPY_LANEMASK}, {RegDef, RegUse, kind(MachineOperand::Kind::LaneMask)}, 1,
+                     {}, false, 0, false, PseudoOwner::PostRAExpansion,
+                     PipelineStage::PostRAFinalized);
+  Registry.configure({GO::BUNDLE}, {VariadicAny}, 0, {InstructionFlag::Meta}, true, 0, false,
+                     PseudoOwner::None, PipelineStage::Emission, true);
+  Registry.configure({GO::LIFETIME_START, GO::LIFETIME_END}, {immediate()}, 0,
+                     {InstructionFlag::Meta});
+  Registry.configure({GO::PSEUDO_PROBE}, {immediate(), immediate(), immediate(), immediate()}, 0,
+                     {InstructionFlag::Meta, InstructionFlag::HasSideEffects});
+  Registry.configure({GO::ARITH_FENCE}, {RegDef, RegUse}, 1, {InstructionFlag::Meta});
+  Registry.tie(GO::ARITH_FENCE, 0, 1);
+  Registry.configure({GO::STACKMAP}, {immediate(), immediate(), VariadicAny}, 0,
+                     {InstructionFlag::Call, InstructionFlag::MayLoad,
+                      InstructionFlag::HasSideEffects, InstructionFlag::ProducesCode,
+                      InstructionFlag::TerminalEmission},
+                     true, 0, false, PseudoOwner::AsmPrinter, PipelineStage::Emission, true);
+  Registry.configure({GO::FENTRY_CALL}, {}, 0,
+                     {InstructionFlag::Call, InstructionFlag::MayLoad, InstructionFlag::MayStore,
+                      InstructionFlag::HasSideEffects, InstructionFlag::ProducesCode,
+                      InstructionFlag::TerminalEmission},
+                     false, 0, false, PseudoOwner::AsmPrinter, PipelineStage::Emission, true);
+  Registry.configure(
+      {GO::PATCHPOINT},
+      {RegDef, immediate(), immediate(), Any, immediate(), immediate(), VariadicAny}, 1,
+      {InstructionFlag::Call, InstructionFlag::MayLoad, InstructionFlag::HasSideEffects,
+       InstructionFlag::ProducesCode, InstructionFlag::TerminalEmission},
+      true, 0, false, PseudoOwner::AsmPrinter, PipelineStage::Emission, true);
+  Registry.configure({GO::LOAD_STACK_GUARD}, {RegDef}, 1,
+                     {InstructionFlag::MayLoad, InstructionFlag::Rematerializable}, false, 0, false,
+                     PseudoOwner::InstructionSelect, PipelineStage::Selected);
+  Registry.configure({GO::PREALLOCATED_SETUP}, {immediate()}, 0, {InstructionFlag::HasSideEffects},
+                     false, 0, false, PseudoOwner::InstructionSelect, PipelineStage::Selected);
+  Registry.configure({GO::PREALLOCATED_ARG}, {RegDef, immediate(), immediate()}, 1,
+                     {InstructionFlag::HasSideEffects}, false, 0, false,
+                     PseudoOwner::InstructionSelect, PipelineStage::Selected);
+  Registry.configure({GO::STATEPOINT}, {VariadicAny}, 0,
+                     {InstructionFlag::Call, InstructionFlag::MayLoad, InstructionFlag::MayStore,
+                      InstructionFlag::HasSideEffects, InstructionFlag::ProducesCode,
+                      InstructionFlag::TerminalEmission},
+                     true, 0, false, PseudoOwner::AsmPrinter, PipelineStage::Emission, true);
+  Registry.configure({GO::LOCAL_ESCAPE}, {symbol(), kind(MachineOperand::Kind::FrameIndex)}, 0,
+                     {InstructionFlag::Meta});
+  Registry.configure({GO::FAULTING_OP}, {RegDef, VariadicAny}, 1,
+                     {InstructionFlag::MayLoad, InstructionFlag::MayStore,
+                      InstructionFlag::HasSideEffects, InstructionFlag::Terminator,
+                      InstructionFlag::Branch, InstructionFlag::ProducesCode,
+                      InstructionFlag::TerminalEmission},
+                     true, 0, false, PseudoOwner::AsmPrinter, PipelineStage::Emission, true);
+  Registry.configure({GO::PATCHABLE_OP}, {VariadicAny}, 0,
+                     {InstructionFlag::MayLoad, InstructionFlag::MayStore,
+                      InstructionFlag::HasSideEffects, InstructionFlag::ProducesCode,
+                      InstructionFlag::TerminalEmission},
+                     true, 0, false, PseudoOwner::AsmPrinter, PipelineStage::Emission, true);
+  Registry.configure({GO::PATCHABLE_FUNCTION_ENTER, GO::PATCHABLE_FUNCTION_EXIT}, {}, 0,
+                     {InstructionFlag::HasSideEffects, InstructionFlag::ProducesCode,
+                      InstructionFlag::TerminalEmission},
+                     false, 0, false, PseudoOwner::AsmPrinter, PipelineStage::Emission);
+  Registry.configure({GO::PATCHABLE_RET, GO::PATCHABLE_TAIL_CALL}, {VariadicAny}, 0,
+                     {InstructionFlag::HasSideEffects, InstructionFlag::ProducesCode,
+                      InstructionFlag::TerminalEmission, InstructionFlag::Terminator,
+                      InstructionFlag::Return},
+                     true, 0, false, PseudoOwner::AsmPrinter, PipelineStage::Emission, true);
+  Registry.configure({GO::PATCHABLE_EVENT_CALL}, {RegUse, Any}, 0,
+                     {InstructionFlag::Call, InstructionFlag::MayLoad, InstructionFlag::MayStore,
+                      InstructionFlag::HasSideEffects, InstructionFlag::ProducesCode,
+                      InstructionFlag::TerminalEmission},
+                     false, 0, false, PseudoOwner::AsmPrinter, PipelineStage::Emission, true);
+  Registry.configure({GO::PATCHABLE_TYPED_EVENT_CALL}, {Any, RegUse, Any}, 0,
+                     {InstructionFlag::Call, InstructionFlag::MayLoad, InstructionFlag::MayStore,
+                      InstructionFlag::HasSideEffects, InstructionFlag::ProducesCode,
+                      InstructionFlag::TerminalEmission},
+                     false, 0, false, PseudoOwner::AsmPrinter, PipelineStage::Emission, true);
+  Registry.configure({GO::ICALL_BRANCH_FUNNEL}, {VariadicAny}, 0, {InstructionFlag::HasSideEffects},
+                     true, 0, false, PseudoOwner::PostRAExpansion, PipelineStage::PostRAFinalized,
+                     true);
+  Registry.configure({GO::FAKE_USE}, {VariadicUse}, 0,
+                     {InstructionFlag::Meta, InstructionFlag::FakeUse}, true);
+  Registry.configure({GO::MEMBARRIER}, {}, 0,
+                     {InstructionFlag::Meta, InstructionFlag::HasSideEffects});
+  Registry.configure({GO::JUMP_TABLE_DEBUG_INFO}, {kind(MachineOperand::Kind::JumpTableIndex)}, 0,
+                     {InstructionFlag::Meta});
+  Registry.configure({GO::RELOC_NONE}, {symbol()}, 0,
+                     {InstructionFlag::Meta, InstructionFlag::HasSideEffects});
+  Registry.configure({GO::CONVERGENCECTRL_ENTRY, GO::CONVERGENCECTRL_ANCHOR}, {RegDef}, 1,
+                     {InstructionFlag::Meta, InstructionFlag::Convergent});
+  Registry.configure({GO::CONVERGENCECTRL_LOOP}, {RegDef, RegUse}, 1,
+                     {InstructionFlag::Meta, InstructionFlag::Convergent});
+  Registry.configure({GO::CONVERGENCECTRL_GLUE}, {RegUse}, 0,
+                     {InstructionFlag::Meta, InstructionFlag::Convergent});
+}
+
+void configureGenericOpcodes(DescriptorRegistry &Registry) {
+  const LLTKindSet AnyTypes = anyValueKinds();
+  const LLTKindSet IntTypes = integerKinds();
+  const LLTKindSet ScalarValues = scalarValueKinds();
+  const LLTKindSet ScalarInts = scalarIntegerKinds();
+  const LLTKindSet FloatTypes = floatingKinds();
+  const LLTKindSet ScalarFloats = scalarFloatingKinds();
+  const LLTKindSet PointerTypes = pointerKinds();
+  const LLTKindSet ScalarPointers = scalarPointerKinds();
+  const LLTKindSet VectorTypes = vectorKinds();
+
+  const auto AnyDef0 = typedRegister(RegisterOperandRole::Def, AnyTypes, 0);
+  const auto AnyUse0 = typedRegister(RegisterOperandRole::Use, AnyTypes, 0);
+  const auto AnyUse1 = typedRegister(RegisterOperandRole::Use, AnyTypes, 1);
+  const auto ScalarDef0 = typedRegister(RegisterOperandRole::Def, ScalarValues, 0);
+  const auto ScalarUse0 = typedRegister(RegisterOperandRole::Use, ScalarValues, 0);
+  const auto IntDef0 = typedRegister(RegisterOperandRole::Def, IntTypes, 0);
+  const auto IntDef1 = typedRegister(RegisterOperandRole::Def, IntTypes, 1);
+  const auto IntUse0 = typedRegister(RegisterOperandRole::Use, IntTypes, 0);
+  const auto IntUse1 = typedRegister(RegisterOperandRole::Use, IntTypes, 1);
+  const auto ScalarIntDef0 = typedRegister(RegisterOperandRole::Def, ScalarInts, 0);
+  const auto ScalarIntDef1 = typedRegister(RegisterOperandRole::Def, ScalarInts, 1);
+  const auto ScalarIntUse0 = typedRegister(RegisterOperandRole::Use, ScalarInts, 0);
+  const auto ScalarIntUse1 = typedRegister(RegisterOperandRole::Use, ScalarInts, 1);
+  const auto ScalarIntUse2 = typedRegister(RegisterOperandRole::Use, ScalarInts, 2);
+  const auto FloatDef0 = typedRegister(RegisterOperandRole::Def, FloatTypes, 0);
+  const auto FloatUse0 = typedRegister(RegisterOperandRole::Use, FloatTypes, 0);
+  const auto FloatUse1 = typedRegister(RegisterOperandRole::Use, FloatTypes, 1);
+  const auto ScalarFloatDef0 = typedRegister(RegisterOperandRole::Def, ScalarFloats, 0);
+  const auto ScalarFloatUse0 = typedRegister(RegisterOperandRole::Use, ScalarFloats, 0);
+  const auto PointerDef0 = typedRegister(RegisterOperandRole::Def, PointerTypes, 0);
+  const auto PointerUse0 = typedRegister(RegisterOperandRole::Use, PointerTypes, 0);
+  const auto PointerUse1 = typedRegister(RegisterOperandRole::Use, PointerTypes, 1);
+  const auto ScalarPointerDef0 = typedRegister(RegisterOperandRole::Def, ScalarPointers, 0);
+  const auto ScalarPointerDef1 = typedRegister(RegisterOperandRole::Def, ScalarPointers, 1);
+  const auto ScalarPointerUse0 = typedRegister(RegisterOperandRole::Use, ScalarPointers, 0);
+  const auto ScalarPointerUse1 = typedRegister(RegisterOperandRole::Use, ScalarPointers, 1);
+  const auto ScalarPointerUse2 = typedRegister(RegisterOperandRole::Use, ScalarPointers, 2);
+
+  Registry.configure({GO::G_ASSERT_SEXT, GO::G_ASSERT_ZEXT}, {IntDef0, IntUse0, immediate()}, 1);
+  Registry.configure({GO::G_ASSERT_ALIGN}, {AnyDef0, AnyUse0, immediate()}, 1);
+
+  Registry.configure(
+      {GO::G_ADD,       GO::G_SUB,      GO::G_MUL,       GO::G_SDIV,     GO::G_UDIV,  GO::G_SREM,
+       GO::G_UREM,      GO::G_AND,      GO::G_OR,        GO::G_XOR,      GO::G_ABDS,  GO::G_ABDU,
+       GO::G_UAVGFLOOR, GO::G_UAVGCEIL, GO::G_SAVGFLOOR, GO::G_SAVGCEIL, GO::G_UMULH, GO::G_SMULH,
+       GO::G_UADDSAT,   GO::G_SADDSAT,  GO::G_USUBSAT,   GO::G_SSUBSAT,  GO::G_SMIN,  GO::G_SMAX,
+       GO::G_UMIN,      GO::G_UMAX,     GO::G_CLMUL},
+      {IntDef0, IntUse0, IntUse0}, 1);
+  Registry.addFlag({GO::G_ADD, GO::G_MUL, GO::G_AND, GO::G_OR, GO::G_XOR, GO::G_ABDS, GO::G_ABDU,
+                    GO::G_UMULH, GO::G_SMULH, GO::G_UADDSAT, GO::G_SADDSAT, GO::G_SMIN, GO::G_SMAX,
+                    GO::G_UMIN, GO::G_UMAX, GO::G_CLMUL},
+                   InstructionFlag::Commutable);
+
+  Registry.configure({GO::G_SDIVREM, GO::G_UDIVREM}, {IntDef0, IntDef0, IntUse0, IntUse0}, 2);
+  Registry.configure({GO::G_IMPLICIT_DEF}, {AnyDef0}, 1);
+  Registry.configure({GO::G_PHI},
+                     {AnyDef0, repeated(AnyUse0), repeated(kind(MachineOperand::Kind::BasicBlock))},
+                     1, {InstructionFlag::Phi}, true, 1);
+  Registry.configure({GO::G_FRAME_INDEX},
+                     {ScalarPointerDef0, kind(MachineOperand::Kind::FrameIndex)}, 1);
+  Registry.configure({GO::G_GLOBAL_VALUE},
+                     {ScalarPointerDef0, kind(MachineOperand::Kind::GlobalSymbol)}, 1);
+  Registry.configure(
+      {GO::G_PTRAUTH_GLOBAL_VALUE},
+      {ScalarPointerDef0, ScalarPointerUse1, immediate(), ScalarIntUse2, immediate()}, 1);
+  Registry.configure({GO::G_CONSTANT_POOL},
+                     {ScalarPointerDef0, kind(MachineOperand::Kind::ConstantPoolIndex)}, 1);
+  Registry.configure({GO::G_EXTRACT}, {AnyDef0, AnyUse1, immediate()}, 1);
+  Registry.configure({GO::G_UNMERGE_VALUES}, {AnyDef0, repeated(AnyDef0), AnyUse1}, 2, {}, true, 1);
+  Registry.configure({GO::G_INSERT}, {AnyDef0, AnyUse0, AnyUse1, immediate()}, 1);
+  Registry.configure({GO::G_MERGE_VALUES}, {AnyDef0, AnyUse1, repeated(AnyUse1)}, 1, {}, true, 1);
+
+  const auto VectorDef0 = typedRegister(RegisterOperandRole::Def, VectorTypes, 0);
+  Registry.configure({GO::G_BUILD_VECTOR, GO::G_BUILD_VECTOR_TRUNC},
+                     {VectorDef0, AnyUse1, repeated(AnyUse1)}, 1, {}, true);
+  Registry.configure({GO::G_CONCAT_VECTORS},
+                     {VectorDef0, typedRegister(RegisterOperandRole::Use, VectorTypes, 1),
+                      repeated(typedRegister(RegisterOperandRole::Use, VectorTypes, 1))},
+                     1, {}, true, 1);
+
+  Registry.configure({GO::G_PTRTOINT}, {IntDef0, PointerUse1}, 1);
+  Registry.configure({GO::G_INTTOPTR}, {PointerDef0, IntUse1}, 1);
+  Registry.configure({GO::G_BITCAST}, {AnyDef0, AnyUse1}, 1);
+  Registry.configure({GO::G_FREEZE, GO::G_CONSTANT_FOLD_BARRIER}, {AnyDef0, AnyUse0}, 1);
+  Registry.configure({GO::G_INTRINSIC_FPTRUNC_ROUND}, {FloatDef0, FloatUse1, immediate()}, 1);
+  Registry.configure({GO::G_INTRINSIC_TRUNC, GO::G_INTRINSIC_ROUND, GO::G_INTRINSIC_ROUNDEVEN},
+                     {FloatDef0, FloatUse0}, 1);
+  Registry.configure({GO::G_INTRINSIC_LRINT, GO::G_INTRINSIC_LLRINT}, {IntDef0, FloatUse1}, 1);
+  Registry.configure({GO::G_READCYCLECOUNTER, GO::G_READSTEADYCOUNTER},
+                     {typedRegister(RegisterOperandRole::Def, ScalarInts, 0)}, 1,
+                     {InstructionFlag::HasSideEffects});
+
+  Registry.configure({GO::G_LOAD}, {AnyDef0, ScalarPointerUse1}, 1, {InstructionFlag::MayLoad},
+                     false, 0, true);
+  Registry.configure({GO::G_SEXTLOAD, GO::G_ZEXTLOAD}, {IntDef0, ScalarPointerUse1}, 1,
+                     {InstructionFlag::MayLoad}, false, 0, true);
+  Registry.configure({GO::G_FPEXTLOAD}, {FloatDef0, ScalarPointerUse1}, 1,
+                     {InstructionFlag::MayLoad}, false, 0, true);
+  Registry.configure({GO::G_INDEXED_LOAD},
+                     {AnyDef0, ScalarPointerDef1, ScalarPointerUse1, ScalarIntUse2, immediate()}, 2,
+                     {InstructionFlag::MayLoad}, false, 0, true);
+  Registry.configure({GO::G_INDEXED_SEXTLOAD, GO::G_INDEXED_ZEXTLOAD},
+                     {IntDef0, ScalarPointerDef1, ScalarPointerUse1, ScalarIntUse2, immediate()}, 2,
+                     {InstructionFlag::MayLoad}, false, 0, true);
+  Registry.configure({GO::G_STORE}, {AnyUse0, ScalarPointerUse1}, 0, {InstructionFlag::MayStore},
+                     false, 0, true);
+  Registry.configure({GO::G_FPTRUNCSTORE}, {FloatUse0, ScalarPointerUse1}, 0,
+                     {InstructionFlag::MayStore}, false, 0, true);
+  Registry.configure({GO::G_INDEXED_STORE},
+                     {ScalarPointerDef0, AnyUse1, ScalarPointerUse0, ScalarIntUse2, immediate()}, 1,
+                     {InstructionFlag::MayStore}, false, 0, true);
+  Registry.configure({GO::G_ATOMIC_CMPXCHG_WITH_SUCCESS},
+                     {ScalarDef0, ScalarIntDef1, ScalarPointerUse2, ScalarUse0, ScalarUse0}, 2,
+                     {InstructionFlag::MayLoad, InstructionFlag::MayStore}, false, 0, true);
+  Registry.configure({GO::G_ATOMIC_CMPXCHG},
+                     {ScalarDef0, ScalarPointerUse1, ScalarUse0, ScalarUse0}, 1,
+                     {InstructionFlag::MayLoad, InstructionFlag::MayStore}, false, 0, true);
+  Registry.configure({GO::G_ATOMICRMW_XCHG}, {ScalarDef0, ScalarPointerUse1, ScalarUse0}, 1,
+                     {InstructionFlag::MayLoad, InstructionFlag::MayStore}, false, 0, true);
+  Registry.configure({GO::G_ATOMICRMW_ADD, GO::G_ATOMICRMW_SUB, GO::G_ATOMICRMW_AND,
+                      GO::G_ATOMICRMW_NAND, GO::G_ATOMICRMW_OR, GO::G_ATOMICRMW_XOR,
+                      GO::G_ATOMICRMW_MAX, GO::G_ATOMICRMW_MIN, GO::G_ATOMICRMW_UMAX,
+                      GO::G_ATOMICRMW_UMIN, GO::G_ATOMICRMW_UINC_WRAP, GO::G_ATOMICRMW_UDEC_WRAP,
+                      GO::G_ATOMICRMW_USUB_COND, GO::G_ATOMICRMW_USUB_SAT},
+                     {ScalarIntDef0, ScalarPointerUse1, ScalarIntUse0}, 1,
+                     {InstructionFlag::MayLoad, InstructionFlag::MayStore}, false, 0, true);
+  Registry.configure({GO::G_ATOMICRMW_FADD, GO::G_ATOMICRMW_FSUB, GO::G_ATOMICRMW_FMAX,
+                      GO::G_ATOMICRMW_FMIN, GO::G_ATOMICRMW_FMAXIMUM, GO::G_ATOMICRMW_FMINIMUM,
+                      GO::G_ATOMICRMW_FMAXIMUMNUM, GO::G_ATOMICRMW_FMINIMUMNUM},
+                     {ScalarFloatDef0, ScalarPointerUse1, ScalarFloatUse0}, 1,
+                     {InstructionFlag::MayLoad, InstructionFlag::MayStore}, false, 0, true);
+  Registry.configure({GO::G_FENCE}, {immediate(), immediate()}, 0,
+                     {InstructionFlag::HasSideEffects});
+  Registry.configure(
+      {GO::G_PREFETCH}, {ScalarPointerUse0, immediate(), immediate(), immediate()}, 0,
+      {InstructionFlag::MayLoad, InstructionFlag::MayStore, InstructionFlag::HasSideEffects}, false,
+      0, true);
+  Registry.configure({GO::G_BRCOND}, {ScalarIntUse0, kind(MachineOperand::Kind::BasicBlock)}, 0,
+                     {InstructionFlag::Terminator, InstructionFlag::Branch});
+  Registry.configure({GO::G_BRINDIRECT}, {ScalarPointerUse0}, 0,
+                     {InstructionFlag::Terminator, InstructionFlag::Branch,
+                      InstructionFlag::IndirectBranch, InstructionFlag::Barrier});
+  Registry.configure({GO::G_INVOKE_REGION_START}, {}, 0, {InstructionFlag::Terminator});
+  Registry.configure({GO::G_INTRINSIC, GO::G_INTRINSIC_W_SIDE_EFFECTS, GO::G_INTRINSIC_CONVERGENT,
+                      GO::G_INTRINSIC_CONVERGENT_W_SIDE_EFFECTS},
+                     {repeated(anyOperand())}, 0, {}, true, 1, false, PseudoOwner::None,
+                     PipelineStage::Emission, true);
+  Registry.addFlag({GO::G_INTRINSIC_W_SIDE_EFFECTS, GO::G_INTRINSIC_CONVERGENT_W_SIDE_EFFECTS},
+                   InstructionFlag::HasSideEffects);
+  Registry.addFlag({GO::G_INTRINSIC_W_SIDE_EFFECTS, GO::G_INTRINSIC_CONVERGENT_W_SIDE_EFFECTS},
+                   InstructionFlag::MayLoad);
+  Registry.addFlag({GO::G_INTRINSIC_W_SIDE_EFFECTS, GO::G_INTRINSIC_CONVERGENT_W_SIDE_EFFECTS},
+                   InstructionFlag::MayStore);
+  Registry.addFlag({GO::G_INTRINSIC_CONVERGENT, GO::G_INTRINSIC_CONVERGENT_W_SIDE_EFFECTS},
+                   InstructionFlag::Convergent);
+
+  Registry.configure({GO::G_ANYEXT, GO::G_SEXT, GO::G_ZEXT}, {IntDef0, IntUse1}, 1);
+  Registry.configure({GO::G_TRUNC, GO::G_TRUNC_SSAT_S, GO::G_TRUNC_SSAT_U, GO::G_TRUNC_USAT_U},
+                     {IntDef0, IntUse1}, 1);
+  Registry.configure(
+      {GO::G_CONSTANT},
+      {typedRegister(RegisterOperandRole::Def, ScalarInts, 0),
+       operand({MachineOperand::Kind::Immediate, MachineOperand::Kind::IntegerImmediate})},
+      1);
+  Registry.configure({GO::G_FCONSTANT},
+                     {ScalarFloatDef0, kind(MachineOperand::Kind::FloatingImmediate)}, 1);
+  Registry.configure({GO::G_VASTART}, {ScalarPointerUse0}, 0, {InstructionFlag::MayStore}, false, 0,
+                     true);
+  Registry.configure({GO::G_VAARG}, {AnyDef0, ScalarPointerUse1, immediate()}, 1,
+                     {InstructionFlag::MayLoad, InstructionFlag::MayStore}, false, 0, true);
+  Registry.configure({GO::G_SEXT_INREG}, {IntDef0, IntUse0, immediate()}, 1);
+  Registry.configure(
+      {GO::G_SHL, GO::G_LSHR, GO::G_ASHR, GO::G_ROTR, GO::G_ROTL, GO::G_USHLSAT, GO::G_SSHLSAT},
+      {IntDef0, IntUse0, IntUse1}, 1);
+  Registry.configure({GO::G_FSHL, GO::G_FSHR}, {IntDef0, IntUse0, IntUse0, IntUse1}, 1);
+  Registry.configure({GO::G_ICMP},
+                     {IntDef0, kind(MachineOperand::Kind::Predicate), IntUse1, IntUse1}, 1);
+  Registry.configure({GO::G_FCMP},
+                     {IntDef0, kind(MachineOperand::Kind::Predicate), FloatUse1, FloatUse1}, 1);
+  Registry.configure({GO::G_SCMP, GO::G_UCMP}, {IntDef0, IntUse1, IntUse1}, 1);
+  Registry.configure({GO::G_SELECT}, {AnyDef0, IntUse1, AnyUse0, AnyUse0}, 1);
+
+  Registry.configure({GO::G_UADDO, GO::G_USUBO, GO::G_SADDO, GO::G_SSUBO, GO::G_UMULO, GO::G_SMULO},
+                     {IntDef0, IntDef1, IntUse0, IntUse0}, 2);
+  Registry.configure({GO::G_UADDE, GO::G_USUBE, GO::G_SADDE, GO::G_SSUBE},
+                     {IntDef0, IntDef1, IntUse0, IntUse0, IntUse1}, 2);
+  Registry.addFlag({GO::G_UADDO, GO::G_SADDO, GO::G_UMULO, GO::G_SMULO},
+                   InstructionFlag::Commutable);
+  Registry.configure({GO::G_SMULFIX, GO::G_UMULFIX, GO::G_SMULFIXSAT, GO::G_UMULFIXSAT,
+                      GO::G_SDIVFIX, GO::G_UDIVFIX, GO::G_SDIVFIXSAT, GO::G_UDIVFIXSAT},
+                     {IntDef0, IntUse0, IntUse0, immediate()}, 1);
+  Registry.addFlag({GO::G_SMULFIX, GO::G_UMULFIX, GO::G_SMULFIXSAT, GO::G_UMULFIXSAT},
+                   InstructionFlag::Commutable);
+
+  Registry.configure({GO::G_FNEG,   GO::G_FABS,  GO::G_FCANONICALIZE, GO::G_FEXP,   GO::G_FEXP2,
+                      GO::G_FEXP10, GO::G_FLOG,  GO::G_FLOG2,         GO::G_FLOG10, GO::G_FCEIL,
+                      GO::G_FCOS,   GO::G_FSIN,  GO::G_FTAN,          GO::G_FACOS,  GO::G_FASIN,
+                      GO::G_FATAN,  GO::G_FCOSH, GO::G_FSINH,         GO::G_FTANH,  GO::G_FSQRT,
+                      GO::G_FFLOOR, GO::G_FRINT, GO::G_FNEARBYINT},
+                     {FloatDef0, FloatUse0}, 1);
+  Registry.configure({GO::G_FPEXT, GO::G_FPTRUNC}, {FloatDef0, FloatUse1}, 1);
+  Registry.configure({GO::G_FPTOSI, GO::G_FPTOUI, GO::G_FPTOSI_SAT, GO::G_FPTOUI_SAT},
+                     {IntDef0, FloatUse1}, 1);
+  Registry.configure({GO::G_SITOFP, GO::G_UITOFP}, {FloatDef0, IntUse1}, 1);
+  Registry.configure({GO::G_FCOPYSIGN}, {FloatDef0, FloatUse0, FloatUse1}, 1);
+  Registry.configure({GO::G_IS_FPCLASS}, {IntDef0, FloatUse1, immediate()}, 1);
+  Registry.configure({GO::G_FADD, GO::G_FSUB, GO::G_FMUL, GO::G_FDIV, GO::G_FREM, GO::G_FPOW,
+                      GO::G_FATAN2, GO::G_FMINNUM, GO::G_FMAXNUM, GO::G_FMINNUM_IEEE,
+                      GO::G_FMAXNUM_IEEE, GO::G_FMINIMUM, GO::G_FMAXIMUM, GO::G_FMINIMUMNUM,
+                      GO::G_FMAXIMUMNUM},
+                     {FloatDef0, FloatUse0, FloatUse0}, 1);
+  Registry.addFlag({GO::G_FADD, GO::G_FMUL, GO::G_FMINNUM, GO::G_FMAXNUM, GO::G_FMINNUM_IEEE,
+                    GO::G_FMAXNUM_IEEE, GO::G_FMINIMUM, GO::G_FMAXIMUM, GO::G_FMINIMUMNUM,
+                    GO::G_FMAXIMUMNUM},
+                   InstructionFlag::Commutable);
+  Registry.configure({GO::G_FMA, GO::G_FMAD}, {FloatDef0, FloatUse0, FloatUse0, FloatUse0}, 1);
+  Registry.configure({GO::G_FMODF, GO::G_FSINCOS}, {FloatDef0, FloatDef0, FloatUse0}, 2);
+  Registry.configure({GO::G_FPOWI, GO::G_FLDEXP}, {FloatDef0, FloatUse0, IntUse1}, 1);
+  Registry.configure({GO::G_FFREXP}, {FloatDef0, IntDef1, FloatUse0}, 2);
+
+  Registry.configure({GO::G_GET_FPENV, GO::G_GET_FPMODE}, {AnyDef0}, 1,
+                     {InstructionFlag::HasSideEffects});
+  Registry.configure({GO::G_SET_FPENV, GO::G_SET_FPMODE}, {AnyUse0}, 0,
+                     {InstructionFlag::HasSideEffects});
+  Registry.configure({GO::G_RESET_FPENV, GO::G_RESET_FPMODE}, {}, 0,
+                     {InstructionFlag::HasSideEffects});
+  Registry.configure({GO::G_GET_ROUNDING}, {IntDef0}, 1, {InstructionFlag::HasSideEffects});
+  Registry.configure({GO::G_SET_ROUNDING}, {IntUse0}, 0, {InstructionFlag::HasSideEffects});
+  Registry.configure({GO::G_PTR_ADD}, {PointerDef0, PointerUse0, IntUse1}, 1);
+  Registry.configure({GO::G_PTRMASK}, {PointerDef0, PointerUse0, IntUse1}, 1);
+  Registry.configure({GO::G_ABS}, {IntDef0, IntUse0}, 1);
+  Registry.configure({GO::G_LROUND, GO::G_LLROUND}, {IntDef0, FloatUse1}, 1);
+  Registry.configure(
+      {GO::G_BR}, {kind(MachineOperand::Kind::BasicBlock)}, 0,
+      {InstructionFlag::Terminator, InstructionFlag::Branch, InstructionFlag::Barrier});
+  Registry.configure({GO::G_BRJT},
+                     {ScalarPointerUse0, kind(MachineOperand::Kind::JumpTableIndex), ScalarIntUse1},
+                     0,
+                     {InstructionFlag::Terminator, InstructionFlag::Branch,
+                      InstructionFlag::IndirectBranch, InstructionFlag::Barrier});
+  Registry.configure({GO::G_VSCALE}, {ScalarIntDef0, immediate()}, 1);
+
+  Registry.configure({GO::G_INSERT_SUBVECTOR},
+                     {VectorDef0, typedRegister(RegisterOperandRole::Use, VectorTypes, 0),
+                      typedRegister(RegisterOperandRole::Use, VectorTypes, 1), immediate()},
+                     1);
+  Registry.configure(
+      {GO::G_EXTRACT_SUBVECTOR},
+      {VectorDef0, typedRegister(RegisterOperandRole::Use, VectorTypes, 1), immediate()}, 1);
+  Registry.configure(
+      {GO::G_INSERT_VECTOR_ELT},
+      {VectorDef0, typedRegister(RegisterOperandRole::Use, VectorTypes, 0), AnyUse1, ScalarIntUse2},
+      1);
+  Registry.configure(
+      {GO::G_EXTRACT_VECTOR_ELT},
+      {AnyDef0, typedRegister(RegisterOperandRole::Use, VectorTypes, 1), ScalarIntUse2}, 1);
+  Registry.configure({GO::G_SHUFFLE_VECTOR},
+                     {VectorDef0, typedRegister(RegisterOperandRole::Use, VectorTypes, 1),
+                      typedRegister(RegisterOperandRole::Use, VectorTypes, 1),
+                      kind(MachineOperand::Kind::ShuffleMask)},
+                     1);
+  Registry.configure({GO::G_SPLAT_VECTOR}, {VectorDef0, AnyUse1}, 1);
+  Registry.configure({GO::G_STEP_VECTOR}, {VectorDef0, immediate()}, 1);
+  Registry.configure({GO::G_VECTOR_COMPRESS},
+                     {VectorDef0, typedRegister(RegisterOperandRole::Use, VectorTypes, 0),
+                      typedRegister(RegisterOperandRole::Use, VectorTypes, 1),
+                      typedRegister(RegisterOperandRole::Use, VectorTypes, 0)},
+                     1);
+
+  Registry.configure({GO::G_CTTZ, GO::G_CTTZ_ZERO_POISON, GO::G_CTLZ, GO::G_CTLZ_ZERO_POISON,
+                      GO::G_CTLS, GO::G_CTPOP, GO::G_BSWAP, GO::G_BITREVERSE},
+                     {IntDef0, IntUse0}, 1);
+  Registry.configure({GO::G_ADDRSPACE_CAST}, {PointerDef0, PointerUse1}, 1);
+  Registry.configure({GO::G_BLOCK_ADDR},
+                     {ScalarPointerDef0, kind(MachineOperand::Kind::BlockAddress)}, 1);
+  Registry.configure({GO::G_JUMP_TABLE},
+                     {ScalarPointerDef0, kind(MachineOperand::Kind::JumpTableIndex)}, 1);
+  Registry.configure({GO::G_DYN_STACKALLOC}, {ScalarPointerDef0, ScalarIntUse1, immediate()}, 1,
+                     {InstructionFlag::HasSideEffects});
+  Registry.configure({GO::G_STACKSAVE}, {ScalarPointerDef0}, 1, {InstructionFlag::HasSideEffects});
+  Registry.configure({GO::G_STACKRESTORE}, {ScalarPointerUse0}, 0,
+                     {InstructionFlag::HasSideEffects});
+
+  Registry.configure({GO::G_STRICT_FADD, GO::G_STRICT_FSUB, GO::G_STRICT_FMUL, GO::G_STRICT_FDIV,
+                      GO::G_STRICT_FREM},
+                     {FloatDef0, FloatUse0, FloatUse0}, 1, {InstructionFlag::HasSideEffects});
+  Registry.configure({GO::G_STRICT_FMA}, {FloatDef0, FloatUse0, FloatUse0, FloatUse0}, 1,
+                     {InstructionFlag::HasSideEffects});
+  Registry.configure({GO::G_STRICT_FSQRT}, {FloatDef0, FloatUse0}, 1,
+                     {InstructionFlag::HasSideEffects});
+  Registry.configure({GO::G_STRICT_FLDEXP}, {FloatDef0, FloatUse0, IntUse1}, 1,
+                     {InstructionFlag::HasSideEffects});
+  Registry.configure({GO::G_STRICT_FCMP, GO::G_STRICT_FCMPS},
+                     {IntDef0, kind(MachineOperand::Kind::Predicate), FloatUse1, FloatUse1}, 1,
+                     {InstructionFlag::HasSideEffects});
+  Registry.configure({GO::G_READ_REGISTER}, {AnyDef0, kind(MachineOperand::Kind::Metadata)}, 1,
+                     {InstructionFlag::HasSideEffects, InstructionFlag::Convergent});
+  Registry.configure({GO::G_WRITE_REGISTER}, {kind(MachineOperand::Kind::Metadata), AnyUse0}, 0,
+                     {InstructionFlag::HasSideEffects, InstructionFlag::Convergent});
+  Registry.configure({GO::G_MEMCPY, GO::G_MEMMOVE},
+                     {ScalarPointerUse0, ScalarPointerUse1, ScalarIntUse2, immediate()}, 0,
+                     {InstructionFlag::MayLoad, InstructionFlag::MayStore}, false, 0, true);
+  Registry.configure({GO::G_MEMCPY_INLINE}, {ScalarPointerUse0, ScalarPointerUse1, ScalarIntUse2},
+                     0, {InstructionFlag::MayLoad, InstructionFlag::MayStore}, false, 0, true);
+  Registry.configure({GO::G_MEMSET}, {ScalarPointerUse0, ScalarIntUse1, ScalarIntUse2, immediate()},
+                     0, {InstructionFlag::MayStore}, false, 0, true);
+  Registry.configure({GO::G_BZERO}, {ScalarPointerUse0, ScalarIntUse1, immediate()}, 0,
+                     {InstructionFlag::MayStore}, false, 0, true);
+  Registry.configure({GO::G_TRAP}, {}, 0,
+                     {InstructionFlag::HasSideEffects, InstructionFlag::MayStore});
+  Registry.configure({GO::G_DEBUGTRAP}, {}, 0, {InstructionFlag::HasSideEffects});
+  Registry.configure({GO::G_UBSANTRAP}, {immediate()}, 0, {InstructionFlag::HasSideEffects});
+
+  Registry.configure({GO::G_VECREDUCE_SEQ_FADD, GO::G_VECREDUCE_SEQ_FMUL},
+                     {ScalarFloatDef0, typedRegister(RegisterOperandRole::Use, ScalarFloats, 1),
+                      typedRegister(RegisterOperandRole::Use, VectorTypes, 2)},
+                     1);
+  Registry.configure({GO::G_VECREDUCE_FADD, GO::G_VECREDUCE_FMUL, GO::G_VECREDUCE_FMAX,
+                      GO::G_VECREDUCE_FMIN, GO::G_VECREDUCE_FMAXIMUM, GO::G_VECREDUCE_FMINIMUM},
+                     {ScalarFloatDef0, typedRegister(RegisterOperandRole::Use, VectorTypes, 1)}, 1);
+  Registry.configure({GO::G_VECREDUCE_ADD, GO::G_VECREDUCE_MUL, GO::G_VECREDUCE_AND,
+                      GO::G_VECREDUCE_OR, GO::G_VECREDUCE_XOR, GO::G_VECREDUCE_SMAX,
+                      GO::G_VECREDUCE_SMIN, GO::G_VECREDUCE_UMAX, GO::G_VECREDUCE_UMIN},
+                     {ScalarIntDef0, typedRegister(RegisterOperandRole::Use, VectorTypes, 1)}, 1);
+  Registry.configure({GO::G_SBFX, GO::G_UBFX},
+                     {ScalarIntDef0, ScalarIntUse0, ScalarIntUse1, ScalarIntUse1}, 1);
+}
+
+[[nodiscard]] std::vector<InstructionDescriptor> buildDescriptors() {
+  DescriptorRegistry Registry;
+  configureCoreOpcodes(Registry);
+  configureGenericOpcodes(Registry);
+  return Registry.take();
+}
+
+[[nodiscard]] const std::vector<InstructionDescriptor> &descriptors() {
+  static const std::vector<InstructionDescriptor> Value = buildDescriptors();
+  return Value;
+}
+
+} // namespace
+
+std::string_view getGenericOpcodeName(GenericOpcode OpcodeValue) noexcept {
+  const Opcode Value = opcode(OpcodeValue);
+  const auto Position =
+      std::ranges::find_if(descriptors(), [Value](const InstructionDescriptor &Descriptor) {
+        return Descriptor.InstructionOpcode == Value;
+      });
+  return Position == descriptors().end() ? std::string_view{} : std::string_view(Position->Name);
+}
+
+std::span<const InstructionDescriptor> genericInstructionDescriptors() noexcept {
+  return descriptors();
+}
+
+std::span<const ImmediatePredicate> genericImmediatePredicates() noexcept {
+  static const std::vector<ImmediatePredicate> Predicates;
+  return Predicates;
+}
+
+Expected<void> appendGenericInstructionInfo(std::vector<InstructionDescriptor> &Descriptors,
+                                            std::vector<ImmediatePredicate> &Predicates) {
+  const auto ExistingOpcode = [&Descriptors](Opcode Value) {
+    return std::ranges::any_of(Descriptors, [Value](const InstructionDescriptor &Descriptor) {
+      return Descriptor.InstructionOpcode == Value;
+    });
+  };
+  for (const InstructionDescriptor &Descriptor : descriptors()) {
+    if (ExistingOpcode(Descriptor.InstructionOpcode)) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "target instruction set already contains a target-independent opcode");
+    }
+    Descriptors.push_back(Descriptor);
+  }
+  for (const ImmediatePredicate &Predicate : genericImmediatePredicates())
+    Predicates.push_back(Predicate);
+  return {};
+}
+
+} // namespace rcc
diff --git a/backend/lib/CodeGen/MachineAnalyses.cpp b/backend/lib/CodeGen/MachineAnalyses.cpp
new file mode 100644
index 0000000..cbc46fd
--- /dev/null
+++ b/backend/lib/CodeGen/MachineAnalyses.cpp
@@ -0,0 +1,850 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "rcc/CodeGen/MachineAnalyses.h"
+
+#include "rcc/CodeGen/MachineFunction.h"
+#include "rcc/CodeGen/MachineInstr.h"
+#include "rcc/CodeGen/MachineMemOperand.h"
+#include "rcc/CodeGen/TargetDescription.h"
+
+#include <algorithm>
+#include <array>
+#include <cstddef>
+#include <cstdint>
+#include <limits>
+#include <optional>
+#include <ranges>
+#include <span>
+#include <unordered_map>
+#include <unordered_set>
+#include <utility>
+#include <vector>
+
+namespace rcc {
+namespace {
+
+[[nodiscard]] std::vector<MachineBasicBlock *> linkedBlocks(MachineFunction &Function) {
+  std::vector<MachineBasicBlock *> Result;
+  Result.reserve(Function.blockCount());
+  for (MachineBasicBlock *Block = Function.firstBlock(); Block != nullptr; Block = Block->next())
+    Result.push_back(Block);
+  return Result;
+}
+
+[[nodiscard]] std::unordered_map<const MachineBasicBlock *, std::size_t>
+blockOrder(std::span<MachineBasicBlock *const> Blocks) {
+  std::unordered_map<const MachineBasicBlock *, std::size_t> Result;
+  for (std::size_t Index = 0; Index < Blocks.size(); ++Index)
+    Result.emplace(Blocks[Index], Index);
+  return Result;
+}
+
+[[nodiscard]] bool containsBlock(std::span<MachineBasicBlock *const> Blocks,
+                                 const MachineBasicBlock *Block) {
+  return std::ranges::find(Blocks, Block) != Blocks.end();
+}
+
+[[nodiscard]] std::uint64_t saturatingAdd(std::uint64_t Left, std::uint64_t Right) noexcept {
+  if (std::numeric_limits<std::uint64_t>::max() - Left < Right)
+    return std::numeric_limits<std::uint64_t>::max();
+  return Left + Right;
+}
+
+[[nodiscard]] std::uint64_t saturatingMultiply(std::uint64_t Value,
+                                               std::uint64_t Multiplier) noexcept {
+  if (Value != 0 && Multiplier > std::numeric_limits<std::uint64_t>::max() / Value)
+    return std::numeric_limits<std::uint64_t>::max();
+  return Value * Multiplier;
+}
+
+[[nodiscard]] std::uint64_t scaleByProbability(std::uint64_t Value,
+                                               BranchProbability Probability) noexcept {
+  constexpr std::uint64_t Denominator = std::numeric_limits<std::uint32_t>::max();
+  const std::uint64_t Numerator = Probability.rawValue();
+  const std::uint64_t Quotient = Value / Denominator;
+  const std::uint64_t Remainder = Value % Denominator;
+  return saturatingAdd(saturatingMultiply(Quotient, Numerator),
+                       (Remainder * Numerator) / Denominator);
+}
+
+[[nodiscard]] bool isKnownDistinctObject(const MachineMemOperandDesc &Left,
+                                         const MachineMemOperandDesc &Right) noexcept {
+  const auto IsUniqueObject = [](MemoryBase::Kind Kind) {
+    return Kind == MemoryBase::Kind::FrameIndex || Kind == MemoryBase::Kind::ConstantPool ||
+           Kind == MemoryBase::Kind::JumpTable;
+  };
+  if (IsUniqueObject(Left.Base.kind()) && IsUniqueObject(Right.Base.kind()) &&
+      Left.Base.kind() != Right.Base.kind()) {
+    return true;
+  }
+  if (Left.Base.kind() != Right.Base.kind())
+    return false;
+  switch (Left.Base.kind()) {
+  case MemoryBase::Kind::FrameIndex:
+    return Left.Base.frameIndex() != Right.Base.frameIndex();
+  case MemoryBase::Kind::ConstantPool:
+    return Left.Base.constantPoolIndex() != Right.Base.constantPoolIndex();
+  case MemoryBase::Kind::JumpTable:
+    return Left.Base.jumpTableIndex() != Right.Base.jumpTableIndex();
+  default:
+    return false;
+  }
+}
+
+[[nodiscard]] bool hasOrderedMemory(const MachineInstr &Instruction) noexcept {
+  for (const MachineMemOperand *Memory : Instruction.memOperands()) {
+    if (Memory != nullptr && (Memory->isAtomic() || Memory->isVolatile()))
+      return true;
+  }
+  return false;
+}
+
+} // namespace
+
+Expected<void> MachineDominatorTreeAnalysis::Result::build(MachineFunction &Function) {
+  Blocks = linkedBlocks(Function);
+  BlockToIndex = blockOrder(Blocks);
+  Dominators.assign(Blocks.size(), std::vector<bool>(Blocks.size(), false));
+  ImmediateDominators.assign(Blocks.size(), nullptr);
+  Reachable.assign(Blocks.size(), false);
+  UnreachableBlocks.clear();
+  if (Blocks.empty())
+    return {};
+
+  std::vector<MachineBasicBlock *> Worklist{Blocks.front()};
+  Reachable[0] = true;
+  for (std::size_t Position = 0; Position < Worklist.size(); ++Position) {
+    MachineBasicBlock *Block = Worklist[Position];
+    for (const MachineSuccessor &Successor : Block->successors()) {
+      const auto Found = BlockToIndex.find(Successor.Block);
+      if (Successor.Block == nullptr || Found == BlockToIndex.end()) {
+        return makeUnexpected(ErrorCode::VerificationError,
+                              "dominator analysis encountered an out-of-function CFG edge");
+      }
+      if (!Reachable[Found->second]) {
+        Reachable[Found->second] = true;
+        Worklist.push_back(Successor.Block);
+      }
+    }
+  }
+
+  for (std::size_t BlockIndex = 0; BlockIndex < Blocks.size(); ++BlockIndex) {
+    if (!Reachable[BlockIndex]) {
+      UnreachableBlocks.push_back(Blocks[BlockIndex]);
+      Dominators[BlockIndex][BlockIndex] = true;
+      continue;
+    }
+    if (BlockIndex == 0) {
+      Dominators[BlockIndex][BlockIndex] = true;
+      continue;
+    }
+    for (std::size_t Candidate = 0; Candidate < Blocks.size(); ++Candidate)
+      Dominators[BlockIndex][Candidate] = Reachable[Candidate];
+  }
+
+  bool Changed = true;
+  while (Changed) {
+    Changed = false;
+    for (std::size_t BlockIndex = 1; BlockIndex < Blocks.size(); ++BlockIndex) {
+      if (!Reachable[BlockIndex])
+        continue;
+      std::vector<bool> NewDominators(Blocks.size(), false);
+      bool HasReachablePredecessor = false;
+      for (MachineBasicBlock *Predecessor : Blocks[BlockIndex]->predecessors()) {
+        const auto Found = BlockToIndex.find(Predecessor);
+        if (Found == BlockToIndex.end() || !Reachable[Found->second])
+          continue;
+        if (!HasReachablePredecessor) {
+          NewDominators = Dominators[Found->second];
+          HasReachablePredecessor = true;
+        } else {
+          for (std::size_t Candidate = 0; Candidate < Blocks.size(); ++Candidate)
+            NewDominators[Candidate] =
+                NewDominators[Candidate] && Dominators[Found->second][Candidate];
+        }
+      }
+      if (!HasReachablePredecessor) {
+        return makeUnexpected(ErrorCode::VerificationError,
+                              "reachable non-entry block has no reachable predecessor");
+      }
+      NewDominators[BlockIndex] = true;
+      if (NewDominators != Dominators[BlockIndex]) {
+        Dominators[BlockIndex] = std::move(NewDominators);
+        Changed = true;
+      }
+    }
+  }
+
+  for (std::size_t BlockIndex = 1; BlockIndex < Blocks.size(); ++BlockIndex) {
+    if (!Reachable[BlockIndex])
+      continue;
+    std::size_t Best = Blocks.size();
+    std::size_t BestDepth = 0;
+    for (std::size_t Candidate = 0; Candidate < Blocks.size(); ++Candidate) {
+      if (Candidate == BlockIndex || !Dominators[BlockIndex][Candidate])
+        continue;
+      const std::size_t Depth =
+          static_cast<std::size_t>(std::ranges::count(Dominators[Candidate], true));
+      if (Best == Blocks.size() || Depth > BestDepth) {
+        Best = Candidate;
+        BestDepth = Depth;
+      }
+    }
+    if (Best == Blocks.size())
+      return makeUnexpected(ErrorCode::InternalError, "reachable block has no immediate dominator");
+    ImmediateDominators[BlockIndex] = Blocks[Best];
+  }
+  return {};
+}
+
+Expected<void>
+MachineDominatorTreeAnalysis::Result::updateAfterCFGChange(MachineFunction &Function) {
+  return build(Function);
+}
+
+bool MachineDominatorTreeAnalysis::Result::isReachable(
+    const MachineBasicBlock &Block) const noexcept {
+  const auto Found = BlockToIndex.find(&Block);
+  return Found != BlockToIndex.end() && Reachable[Found->second];
+}
+
+bool MachineDominatorTreeAnalysis::Result::dominates(
+    const MachineBasicBlock &Dominator, const MachineBasicBlock &Block) const noexcept {
+  const auto DominatorPosition = BlockToIndex.find(&Dominator);
+  const auto BlockPosition = BlockToIndex.find(&Block);
+  if (DominatorPosition == BlockToIndex.end() || BlockPosition == BlockToIndex.end() ||
+      !Reachable[BlockPosition->second]) {
+    return false;
+  }
+  return Dominators[BlockPosition->second][DominatorPosition->second];
+}
+
+bool MachineDominatorTreeAnalysis::Result::dominates(
+    const MachineInstr &Dominator, const MachineInstr &Instruction) const noexcept {
+  const MachineBasicBlock *DominatorBlock = Dominator.parent();
+  const MachineBasicBlock *InstructionBlock = Instruction.parent();
+  if (DominatorBlock == nullptr || InstructionBlock == nullptr)
+    return false;
+  if (DominatorBlock != InstructionBlock)
+    return dominates(*DominatorBlock, *InstructionBlock);
+  for (const MachineInstr *Current = DominatorBlock->firstInstruction(); Current != nullptr;
+       Current = Current->next()) {
+    if (Current == &Dominator)
+      return true;
+    if (Current == &Instruction)
+      return false;
+  }
+  return false;
+}
+
+const MachineBasicBlock *MachineDominatorTreeAnalysis::Result::immediateDominator(
+    const MachineBasicBlock &Block) const noexcept {
+  const auto Found = BlockToIndex.find(&Block);
+  return Found == BlockToIndex.end() ? nullptr : ImmediateDominators[Found->second];
+}
+
+const MachineBasicBlock *MachineDominatorTreeAnalysis::Result::nearestCommonDominator(
+    const MachineBasicBlock &Left, const MachineBasicBlock &Right) const noexcept {
+  if (!isReachable(Left) || !isReachable(Right))
+    return nullptr;
+  std::unordered_set<const MachineBasicBlock *> LeftAncestors;
+  for (const MachineBasicBlock *Current = &Left; Current != nullptr;
+       Current = immediateDominator(*Current)) {
+    LeftAncestors.insert(Current);
+  }
+  for (const MachineBasicBlock *Current = &Right; Current != nullptr;
+       Current = immediateDominator(*Current)) {
+    if (LeftAncestors.contains(Current))
+      return Current;
+  }
+  return nullptr;
+}
+
+Expected<MachineDominatorTreeAnalysis::Result>
+MachineDominatorTreeAnalysis::run(MachineFunction &Function, const TargetDescription &,
+                                  MachineAnalysisManager &) {
+  Result ResultValue;
+  auto Built = ResultValue.build(Function);
+  if (!Built)
+    return std::unexpected(Built.error());
+  return ResultValue;
+}
+
+const MachineLoop *
+MachineLoopAnalysis::Result::loopFor(const MachineBasicBlock &Block) const noexcept {
+  const auto Found = InnermostLoop.find(&Block);
+  return Found == InnermostLoop.end() ? nullptr : &Loops[Found->second];
+}
+
+std::uint32_t
+MachineLoopAnalysis::Result::loopDepth(const MachineBasicBlock &Block) const noexcept {
+  const MachineLoop *Loop = loopFor(Block);
+  return Loop == nullptr ? 0 : Loop->Depth;
+}
+
+bool MachineLoopAnalysis::Result::isIrreducible(const MachineBasicBlock &Block) const noexcept {
+  return IrreducibleBlocks.contains(&Block);
+}
+
+Expected<MachineLoopAnalysis::Result> MachineLoopAnalysis::run(MachineFunction &Function,
+                                                               const TargetDescription &Target,
+                                                               MachineAnalysisManager &Analyses) {
+  auto Dominators = Analyses.getResult<MachineDominatorTreeAnalysis>(Function, Target);
+  if (!Dominators)
+    return std::unexpected(Dominators.error());
+
+  Result ResultValue;
+  std::vector<MachineBasicBlock *> Blocks = linkedBlocks(Function);
+  const auto Order = blockOrder(Blocks);
+  std::unordered_map<MachineBasicBlock *, std::unordered_set<MachineBasicBlock *>> LoopBlocks;
+  std::unordered_map<MachineBasicBlock *, std::vector<MachineBasicBlock *>> LoopLatches;
+
+  for (MachineBasicBlock *Latch : Blocks) {
+    if (!(*Dominators)->isReachable(*Latch))
+      continue;
+    for (const MachineSuccessor &Successor : Latch->successors()) {
+      MachineBasicBlock *Header = Successor.Block;
+      if (Header == nullptr || !(*Dominators)->dominates(*Header, *Latch))
+        continue;
+      auto &Members = LoopBlocks[Header];
+      Members.insert(Header);
+      Members.insert(Latch);
+      LoopLatches[Header].push_back(Latch);
+      std::vector<MachineBasicBlock *> Worklist;
+      if (Latch != Header)
+        Worklist.push_back(Latch);
+      for (std::size_t Position = 0; Position < Worklist.size(); ++Position) {
+        MachineBasicBlock *Current = Worklist[Position];
+        for (MachineBasicBlock *Predecessor : Current->predecessors()) {
+          if (!(*Dominators)->isReachable(*Predecessor) ||
+              !(*Dominators)->dominates(*Header, *Predecessor)) {
+            continue;
+          }
+          if (Members.insert(Predecessor).second && Predecessor != Header)
+            Worklist.push_back(Predecessor);
+        }
+      }
+    }
+  }
+
+  std::vector<MachineBasicBlock *> Headers;
+  Headers.reserve(LoopBlocks.size());
+  for (const auto &[Header, Members] : LoopBlocks) {
+    (void)Members;
+    Headers.push_back(Header);
+  }
+  std::ranges::sort(Headers,
+                    [&Order](const MachineBasicBlock *Left, const MachineBasicBlock *Right) {
+                      return Order.at(Left) < Order.at(Right);
+                    });
+  for (MachineBasicBlock *Header : Headers) {
+    MachineLoop Loop;
+    Loop.Header = Header;
+    Loop.Blocks.assign(LoopBlocks[Header].begin(), LoopBlocks[Header].end());
+    Loop.Latches = LoopLatches[Header];
+    std::ranges::sort(Loop.Blocks,
+                      [&Order](const MachineBasicBlock *Left, const MachineBasicBlock *Right) {
+                        return Order.at(Left) < Order.at(Right);
+                      });
+    std::ranges::sort(Loop.Latches,
+                      [&Order](const MachineBasicBlock *Left, const MachineBasicBlock *Right) {
+                        return Order.at(Left) < Order.at(Right);
+                      });
+    Loop.Latches.erase(std::ranges::unique(Loop.Latches).begin(), Loop.Latches.end());
+    ResultValue.Loops.push_back(std::move(Loop));
+  }
+
+  for (std::size_t Index = 0; Index < ResultValue.Loops.size(); ++Index) {
+    const MachineLoop &Loop = ResultValue.Loops[Index];
+    std::size_t Parent = static_cast<std::size_t>(-1);
+    for (std::size_t Candidate = 0; Candidate < ResultValue.Loops.size(); ++Candidate) {
+      if (Candidate == Index || ResultValue.Loops[Candidate].Blocks.size() <= Loop.Blocks.size()) {
+        continue;
+      }
+      const bool Contains = std::ranges::all_of(Loop.Blocks, [&](MachineBasicBlock *Block) {
+        return containsBlock(ResultValue.Loops[Candidate].Blocks, Block);
+      });
+      if (Contains &&
+          (Parent == static_cast<std::size_t>(-1) ||
+           ResultValue.Loops[Candidate].Blocks.size() < ResultValue.Loops[Parent].Blocks.size())) {
+        Parent = Candidate;
+      }
+    }
+    ResultValue.Loops[Index].Parent = Parent;
+  }
+  for (std::size_t Index = 0; Index < ResultValue.Loops.size(); ++Index) {
+    const std::size_t Parent = ResultValue.Loops[Index].Parent;
+    if (Parent != static_cast<std::size_t>(-1))
+      ResultValue.Loops[Parent].Children.push_back(Index);
+    std::uint32_t Depth = 1;
+    for (std::size_t Ancestor = Parent; Ancestor != static_cast<std::size_t>(-1);
+         Ancestor = ResultValue.Loops[Ancestor].Parent) {
+      ++Depth;
+    }
+    ResultValue.Loops[Index].Depth = Depth;
+  }
+  for (std::size_t Index = 0; Index < ResultValue.Loops.size(); ++Index) {
+    for (MachineBasicBlock *Block : ResultValue.Loops[Index].Blocks) {
+      const auto Existing = ResultValue.InnermostLoop.find(Block);
+      if (Existing == ResultValue.InnermostLoop.end() ||
+          ResultValue.Loops[Existing->second].Depth < ResultValue.Loops[Index].Depth) {
+        ResultValue.InnermostLoop[Block] = Index;
+      }
+    }
+  }
+
+  std::unordered_set<MachineBasicBlock *> Visited;
+  std::vector<MachineBasicBlock *> FinishOrder;
+  for (MachineBasicBlock *Root : Blocks) {
+    if (!(*Dominators)->isReachable(*Root) || Visited.contains(Root))
+      continue;
+    std::vector<std::pair<MachineBasicBlock *, std::size_t>> Stack{{Root, 0}};
+    Visited.insert(Root);
+    while (!Stack.empty()) {
+      auto &[Current, NextSuccessor] = Stack.back();
+      if (NextSuccessor < Current->successors().size()) {
+        MachineBasicBlock *Next = Current->successors()[NextSuccessor++].Block;
+        if (Next != nullptr && (*Dominators)->isReachable(*Next) && Visited.insert(Next).second)
+          Stack.emplace_back(Next, 0);
+        continue;
+      }
+      FinishOrder.push_back(Current);
+      Stack.pop_back();
+    }
+  }
+
+  Visited.clear();
+  for (auto RootPosition = FinishOrder.rbegin(); RootPosition != FinishOrder.rend();
+       ++RootPosition) {
+    MachineBasicBlock *Root = *RootPosition;
+    if (!Visited.insert(Root).second)
+      continue;
+    std::vector<MachineBasicBlock *> Component;
+    std::vector<MachineBasicBlock *> Worklist{Root};
+    for (std::size_t Position = 0; Position < Worklist.size(); ++Position) {
+      MachineBasicBlock *Current = Worklist[Position];
+      Component.push_back(Current);
+      for (MachineBasicBlock *Predecessor : Current->predecessors()) {
+        if ((*Dominators)->isReachable(*Predecessor) && Visited.insert(Predecessor).second)
+          Worklist.push_back(Predecessor);
+      }
+    }
+    bool Cyclic = Component.size() > 1;
+    if (!Cyclic) {
+      Cyclic = std::ranges::any_of(
+          Component.front()->successors(),
+          [Root](const MachineSuccessor &Successor) { return Successor.Block == Root; });
+    }
+    if (!Cyclic)
+      continue;
+
+    std::unordered_set<MachineBasicBlock *> ComponentSet(Component.begin(), Component.end());
+    std::unordered_set<MachineBasicBlock *> EntrySet;
+    for (MachineBasicBlock *Block : Component) {
+      if (std::ranges::any_of(Block->predecessors(), [&](MachineBasicBlock *Predecessor) {
+            return !ComponentSet.contains(Predecessor);
+          })) {
+        EntrySet.insert(Block);
+      }
+    }
+    if (EntrySet.size() <= 1)
+      continue;
+
+    std::ranges::sort(Component,
+                      [&Order](const MachineBasicBlock *Left, const MachineBasicBlock *Right) {
+                        return Order.at(Left) < Order.at(Right);
+                      });
+    IrreducibleMachineRegion Region;
+    Region.Blocks = std::move(Component);
+    Region.Entries.assign(EntrySet.begin(), EntrySet.end());
+    std::ranges::sort(Region.Entries,
+                      [&Order](const MachineBasicBlock *Left, const MachineBasicBlock *Right) {
+                        return Order.at(Left) < Order.at(Right);
+                      });
+    for (MachineBasicBlock *Block : Region.Blocks)
+      ResultValue.IrreducibleBlocks.insert(Block);
+    ResultValue.IrreducibleRegions.push_back(std::move(Region));
+  }
+  std::ranges::sort(
+      ResultValue.IrreducibleRegions,
+      [&Order](const IrreducibleMachineRegion &Left, const IrreducibleMachineRegion &Right) {
+        return Order.at(Left.Blocks.front()) < Order.at(Right.Blocks.front());
+      });
+  return ResultValue;
+}
+
+BranchProbability
+MachineBranchProbabilityAnalysis::Result::probability(const MachineBasicBlock &From,
+                                                      const MachineBasicBlock &To) const noexcept {
+  const auto Found = Probabilities.find(&From);
+  if (Found == Probabilities.end())
+    return BranchProbability::zero();
+  for (const MachineSuccessor &Successor : Found->second) {
+    if (Successor.Block == &To)
+      return Successor.Probability;
+  }
+  return BranchProbability::zero();
+}
+
+std::span<const MachineSuccessor> MachineBranchProbabilityAnalysis::Result::successors(
+    const MachineBasicBlock &Block) const noexcept {
+  const auto Found = Probabilities.find(&Block);
+  return Found == Probabilities.end() ? std::span<const MachineSuccessor>{}
+                                      : std::span<const MachineSuccessor>{Found->second};
+}
+
+Expected<MachineBranchProbabilityAnalysis::Result>
+MachineBranchProbabilityAnalysis::run(MachineFunction &Function, const TargetDescription &,
+                                      MachineAnalysisManager &) {
+  Result ResultValue;
+  const std::vector<MachineBasicBlock *> Blocks = linkedBlocks(Function);
+  const auto Order = blockOrder(Blocks);
+  for (MachineBasicBlock *Block : Blocks) {
+    std::vector<MachineSuccessor> Successors(Block->successors().begin(),
+                                             Block->successors().end());
+    for (const MachineSuccessor &Successor : Successors) {
+      if (Successor.Block == nullptr || !Order.contains(Successor.Block)) {
+        return makeUnexpected(ErrorCode::VerificationError,
+                              "branch-probability analysis encountered an invalid CFG edge");
+      }
+    }
+    ResultValue.Probabilities.emplace(Block, std::move(Successors));
+  }
+  return ResultValue;
+}
+
+std::uint64_t
+MachineBlockFrequencyAnalysis::Result::frequency(const MachineBasicBlock &Block) const noexcept {
+  const auto Found = Frequencies.find(&Block);
+  return Found == Frequencies.end() ? 0 : Found->second;
+}
+
+Expected<MachineBlockFrequencyAnalysis::Result>
+MachineBlockFrequencyAnalysis::run(MachineFunction &Function, const TargetDescription &Target,
+                                   MachineAnalysisManager &Analyses) {
+  auto Dominators = Analyses.getResult<MachineDominatorTreeAnalysis>(Function, Target);
+  auto Loops = Analyses.getResult<MachineLoopAnalysis>(Function, Target);
+  auto Probabilities = Analyses.getResult<MachineBranchProbabilityAnalysis>(Function, Target);
+  if (!Dominators)
+    return std::unexpected(Dominators.error());
+  if (!Loops)
+    return std::unexpected(Loops.error());
+  if (!Probabilities)
+    return std::unexpected(Probabilities.error());
+
+  Result ResultValue;
+  MachineBasicBlock *Entry = Function.firstBlock();
+  if (Entry == nullptr)
+    return ResultValue;
+
+  std::unordered_set<MachineBasicBlock *> Visited;
+  std::vector<MachineBasicBlock *> PostOrder;
+  std::vector<std::pair<MachineBasicBlock *, std::size_t>> Stack{{Entry, 0}};
+  Visited.insert(Entry);
+  while (!Stack.empty()) {
+    auto &[Current, NextSuccessor] = Stack.back();
+    const auto Successors = (*Probabilities)->successors(*Current);
+    if (NextSuccessor < Successors.size()) {
+      MachineBasicBlock *Next = Successors[NextSuccessor++].Block;
+      if (Next != nullptr && (*Dominators)->isReachable(*Next) && Visited.insert(Next).second)
+        Stack.emplace_back(Next, 0);
+      continue;
+    }
+    PostOrder.push_back(Current);
+    Stack.pop_back();
+  }
+  std::ranges::reverse(PostOrder);
+  std::unordered_map<MachineBasicBlock *, std::uint64_t> BaseFrequencies;
+  BaseFrequencies[Entry] = EntryFrequency;
+  for (MachineBasicBlock *Block : PostOrder) {
+    const std::uint64_t Frequency = BaseFrequencies[Block];
+
+    const auto Successors = (*Probabilities)->successors(*Block);
+    const bool UseUniformProbability =
+        !Successors.empty() && std::ranges::all_of(Successors, [](const MachineSuccessor &Edge) {
+          return Edge.Probability == BranchProbability::zero();
+        });
+    for (std::size_t SuccessorIndex = 0; SuccessorIndex < Successors.size(); ++SuccessorIndex) {
+      const MachineSuccessor &Successor = Successors[SuccessorIndex];
+      if (Successor.Block == nullptr || (*Dominators)->dominates(*Successor.Block, *Block))
+        continue;
+      std::uint64_t Contribution = 0;
+      if (UseUniformProbability) {
+        const std::uint64_t Count = Successors.size();
+        Contribution = Frequency / Count;
+        if (SuccessorIndex < Frequency % Count)
+          ++Contribution;
+      } else {
+        Contribution = scaleByProbability(Frequency, Successor.Probability);
+      }
+      BaseFrequencies[Successor.Block] =
+          saturatingAdd(BaseFrequencies[Successor.Block], Contribution);
+    }
+  }
+  for (MachineBasicBlock *Block : linkedBlocks(Function)) {
+    if (!(*Dominators)->isReachable(*Block)) {
+      ResultValue.Frequencies[Block] = 0;
+      continue;
+    }
+    std::uint64_t Frequency = std::max<std::uint64_t>(BaseFrequencies[Block], 1);
+    for (std::uint32_t Level = 0; Level < (*Loops)->loopDepth(*Block); ++Level)
+      Frequency = saturatingMultiply(Frequency, 8);
+    ResultValue.Frequencies[Block] = Frequency;
+  }
+  return ResultValue;
+}
+
+MachineAliasResult
+MachineAliasAnalysis::Result::alias(const MachineMemOperand &Left,
+                                    const MachineMemOperand &Right) const noexcept {
+  const MachineMemOperandDesc &LeftDesc = Left.description();
+  const MachineMemOperandDesc &RightDesc = Right.description();
+  if (isKnownDistinctObject(LeftDesc, RightDesc))
+    return MachineAliasResult::NoAlias;
+
+  const bool SameBase =
+      LeftDesc.Base == RightDesc.Base && LeftDesc.Base.kind() != MemoryBase::Kind::Unknown;
+  const bool SameAliasSource = LeftDesc.AliasSource && RightDesc.AliasSource &&
+                               LeftDesc.AliasSource == RightDesc.AliasSource;
+  if (!SameBase && !SameAliasSource)
+    return MachineAliasResult::MayAlias;
+  if (!LeftDesc.Size.isKnown() || !RightDesc.Size.isKnown() || LeftDesc.Size.isScalable() ||
+      RightDesc.Size.isScalable()) {
+    return MachineAliasResult::MayAlias;
+  }
+
+  const std::uint64_t LeftSize = LeftDesc.Size.minimumBytes();
+  const std::uint64_t RightSize = RightDesc.Size.minimumBytes();
+  if (LeftDesc.Offset == RightDesc.Offset)
+    return LeftSize == RightSize ? MachineAliasResult::MustAlias : MachineAliasResult::PartialAlias;
+
+  const bool LeftFirst = LeftDesc.Offset < RightDesc.Offset;
+  const std::int64_t Lower = LeftFirst ? LeftDesc.Offset : RightDesc.Offset;
+  const std::int64_t Higher = LeftFirst ? RightDesc.Offset : LeftDesc.Offset;
+  const std::uint64_t LowerSize = LeftFirst ? LeftSize : RightSize;
+  const std::uint64_t Distance =
+      static_cast<std::uint64_t>(Higher) - static_cast<std::uint64_t>(Lower);
+  return Distance >= LowerSize ? MachineAliasResult::NoAlias : MachineAliasResult::PartialAlias;
+}
+
+Expected<MachineAliasAnalysis::Result>
+MachineAliasAnalysis::run(MachineFunction &, const TargetDescription &, MachineAnalysisManager &) {
+  return Result{};
+}
+
+std::span<const MachineMemoryDependency> MachineMemoryDependenceAnalysis::Result::dependencies(
+    const MachineInstr &Instruction) const noexcept {
+  const auto Found = DestinationRanges.find(Instruction.stableID());
+  if (Found == DestinationRanges.end())
+    return {};
+  return std::span<const MachineMemoryDependency>(Dependencies)
+      .subspan(Found->second.Begin, Found->second.Size);
+}
+
+const MachineMemoryDependenceRegion *
+MachineMemoryDependenceAnalysis::Result::regionFor(const MachineBasicBlock &Block) const noexcept {
+  const auto Found = BlockToRegion.find(&Block);
+  return Found == BlockToRegion.end() ? nullptr : &Regions[Found->second];
+}
+
+std::span<const MachineMemoryDependency> MachineMemoryDependenceAnalysis::Result::dependencies(
+    const MachineBasicBlock &Block) const noexcept {
+  const auto Found = BlockRanges.find(&Block);
+  if (Found == BlockRanges.end())
+    return {};
+  return std::span<const MachineMemoryDependency>(Dependencies)
+      .subspan(Found->second.Begin, Found->second.Size);
+}
+
+Expected<MachineMemoryDependenceAnalysis::Result>
+MachineMemoryDependenceAnalysis::run(MachineFunction &Function, const TargetDescription &Target,
+                                     MachineAnalysisManager &Analyses) {
+  auto Alias = Analyses.getResult<MachineAliasAnalysis>(Function, Target);
+  if (!Alias)
+    return std::unexpected(Alias.error());
+
+  struct MemoryNode final {
+    MachineInstr *Instruction = nullptr;
+    bool Reads = false;
+    bool Writes = false;
+    bool Ordered = false;
+    bool Barrier = false;
+  };
+
+  Result ResultValue;
+  for (MachineBasicBlock *Block = Function.firstBlock(); Block != nullptr; Block = Block->next()) {
+    std::vector<MemoryNode> Nodes;
+    for (MachineInstr *Instruction = Block->firstInstruction(); Instruction != nullptr;
+         Instruction = Instruction->next()) {
+      const InstructionDescriptor *Descriptor = Target.instructionDescriptor(Instruction->opcode());
+      if (Descriptor == nullptr) {
+        return makeUnexpected(ErrorCode::VerificationError,
+                              "memory-dependence analysis encountered an unknown opcode");
+      }
+      MemoryNode Node;
+      Node.Instruction = Instruction;
+      Node.Reads = Descriptor->Flags.has(InstructionFlag::MayLoad);
+      Node.Writes = Descriptor->Flags.has(InstructionFlag::MayStore);
+      Node.Ordered = hasOrderedMemory(*Instruction);
+      Node.Barrier = Descriptor->Flags.has(InstructionFlag::Call) ||
+                     Descriptor->Flags.has(InstructionFlag::UnmodeledSideEffects) ||
+                     (Descriptor->Flags.has(InstructionFlag::HasSideEffects) &&
+                      Instruction->memOperands().empty());
+      for (const MachineMemOperand *Memory : Instruction->memOperands()) {
+        if (Memory == nullptr)
+          continue;
+        Node.Reads = Node.Reads || Memory->isLoad();
+        Node.Writes = Node.Writes || Memory->isStore();
+      }
+      if (Node.Reads || Node.Writes || Node.Ordered || Node.Barrier)
+        Nodes.push_back(Node);
+    }
+
+    MachineMemoryDependenceRegion Region;
+    Region.Block = Block;
+    Region.Instructions.reserve(Nodes.size());
+    for (const MemoryNode &Node : Nodes)
+      Region.Instructions.push_back(Node.Instruction->stableID());
+    ResultValue.BlockToRegion.emplace(Block, ResultValue.Regions.size());
+    ResultValue.Regions.push_back(std::move(Region));
+
+    const std::size_t RegionBegin = ResultValue.Dependencies.size();
+    for (std::size_t Destination = 0; Destination < Nodes.size(); ++Destination) {
+      for (std::size_t Source = 0; Source < Destination; ++Source) {
+        const MemoryNode &From = Nodes[Source];
+        const MemoryNode &To = Nodes[Destination];
+        if (!From.Writes && !To.Writes && !From.Ordered && !To.Ordered && !From.Barrier &&
+            !To.Barrier) {
+          continue;
+        }
+
+        bool MayAlias = From.Barrier || To.Barrier || From.Ordered || To.Ordered ||
+                        From.Instruction->memOperands().empty() ||
+                        To.Instruction->memOperands().empty();
+        if (!MayAlias) {
+          for (const MachineMemOperand *Left : From.Instruction->memOperands()) {
+            for (const MachineMemOperand *Right : To.Instruction->memOperands()) {
+              if (Left != nullptr && Right != nullptr &&
+                  (*Alias)->alias(*Left, *Right) != MachineAliasResult::NoAlias) {
+                MayAlias = true;
+                break;
+              }
+            }
+            if (MayAlias)
+              break;
+          }
+        }
+        if (!MayAlias)
+          continue;
+
+        MachineMemoryDependencyKind Kind = MachineMemoryDependencyKind::Ordered;
+        if (From.Writes && To.Reads)
+          Kind = MachineMemoryDependencyKind::Flow;
+        else if (From.Reads && To.Writes)
+          Kind = MachineMemoryDependencyKind::Anti;
+        else if (From.Writes && To.Writes)
+          Kind = MachineMemoryDependencyKind::Output;
+        ResultValue.Dependencies.push_back(
+            {From.Instruction->stableID(), To.Instruction->stableID(), Kind});
+      }
+    }
+
+    const std::size_t RegionEnd = ResultValue.Dependencies.size();
+    ResultValue.BlockRanges.emplace(Block, Result::Range{RegionBegin, RegionEnd - RegionBegin});
+    for (std::size_t Begin = RegionBegin; Begin < RegionEnd;) {
+      std::size_t End = Begin + 1;
+      while (End < RegionEnd && ResultValue.Dependencies[End].Destination ==
+                                    ResultValue.Dependencies[Begin].Destination) {
+        ++End;
+      }
+      ResultValue.DestinationRanges.emplace(ResultValue.Dependencies[Begin].Destination,
+                                            Result::Range{Begin, End - Begin});
+      Begin = End;
+    }
+  }
+  return ResultValue;
+}
+
+Expected<void> registerStage8MachineAnalyses(MachineAnalysisManager &Analyses) {
+  const std::array IDs{
+      MachineAnalysisManager::id<MachineDominatorTreeAnalysis>(),
+      MachineAnalysisManager::id<MachineLoopAnalysis>(),
+      MachineAnalysisManager::id<MachineBranchProbabilityAnalysis>(),
+      MachineAnalysisManager::id<MachineBlockFrequencyAnalysis>(),
+      MachineAnalysisManager::id<MachineAliasAnalysis>(),
+      MachineAnalysisManager::id<MachineMemoryDependenceAnalysis>(),
+  };
+  const std::size_t Registered = static_cast<std::size_t>(
+      std::ranges::count_if(IDs, [&Analyses](AnalysisID ID) { return Analyses.isRegistered(ID); }));
+  if (Registered == IDs.size())
+    return {};
+  if (Registered != 0) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "standard machine analyses are only partially registered");
+  }
+
+  auto Candidate = Analyses.forkEmpty();
+  if (!Candidate)
+    return std::unexpected(Candidate.error());
+  MachineAnalysisManager &Staging = **Candidate;
+
+  auto Dominators = Staging.registerAnalysis<MachineDominatorTreeAnalysis>({
+      .Name = "MachineDominatorTree",
+      .Dependencies = {},
+      .InvalidatedBy = {MachinePassChange::CFG, MachinePassChange::BlockLayout},
+      .ThreadSafety = PassThreadSafety::ThreadSafe,
+  });
+  if (!Dominators)
+    return std::unexpected(Dominators.error());
+  auto Loops = Staging.registerAnalysis<MachineLoopAnalysis>({
+      .Name = "MachineLoopInfo",
+      .Dependencies = {MachineAnalysisManager::id<MachineDominatorTreeAnalysis>()},
+      .InvalidatedBy = {MachinePassChange::CFG, MachinePassChange::BlockLayout},
+      .ThreadSafety = PassThreadSafety::ThreadSafe,
+  });
+  if (!Loops)
+    return std::unexpected(Loops.error());
+  auto Probabilities = Staging.registerAnalysis<MachineBranchProbabilityAnalysis>({
+      .Name = "MachineBranchProbability",
+      .Dependencies = {},
+      .InvalidatedBy = {MachinePassChange::CFG},
+      .ThreadSafety = PassThreadSafety::ThreadSafe,
+  });
+  if (!Probabilities)
+    return std::unexpected(Probabilities.error());
+  auto Frequencies = Staging.registerAnalysis<MachineBlockFrequencyAnalysis>({
+      .Name = "MachineBlockFrequency",
+      .Dependencies = {MachineAnalysisManager::id<MachineDominatorTreeAnalysis>(),
+                       MachineAnalysisManager::id<MachineLoopAnalysis>(),
+                       MachineAnalysisManager::id<MachineBranchProbabilityAnalysis>()},
+      .InvalidatedBy = {MachinePassChange::CFG, MachinePassChange::BlockLayout},
+      .ThreadSafety = PassThreadSafety::ThreadSafe,
+  });
+  if (!Frequencies)
+    return std::unexpected(Frequencies.error());
+  auto Alias = Staging.registerAnalysis<MachineAliasAnalysis>({
+      .Name = "MachineAliasAnalysis",
+      .Dependencies = {},
+      .InvalidatedBy = {MachinePassChange::Operands, MachinePassChange::Frame,
+                        MachinePassChange::ConstantPool, MachinePassChange::JumpTable,
+                        MachinePassChange::TargetState},
+      .ThreadSafety = PassThreadSafety::ThreadSafe,
+  });
+  if (!Alias)
+    return std::unexpected(Alias.error());
+  auto MemoryDependence = Staging.registerAnalysis<MachineMemoryDependenceAnalysis>({
+      .Name = "MachineMemoryDependence",
+      .Dependencies = {MachineAnalysisManager::id<MachineAliasAnalysis>()},
+      .InvalidatedBy = {MachinePassChange::Instructions, MachinePassChange::Operands,
+                        MachinePassChange::CFG, MachinePassChange::BlockLayout,
+                        MachinePassChange::Frame, MachinePassChange::ConstantPool,
+                        MachinePassChange::JumpTable, MachinePassChange::TargetState},
+      .ThreadSafety = PassThreadSafety::ThreadSafe,
+  });
+  if (!MemoryDependence)
+    return std::unexpected(MemoryDependence.error());
+  Analyses.Registry = std::move(Staging.Registry);
+  return {};
+}
+
+} // namespace rcc
diff --git a/backend/lib/CodeGen/MachineIRBuilder.cpp b/backend/lib/CodeGen/MachineIRBuilder.cpp
index e1e8006..6887804 100644
--- a/backend/lib/CodeGen/MachineIRBuilder.cpp
+++ b/backend/lib/CodeGen/MachineIRBuilder.cpp
@@ -650,6 +650,19 @@ Expected<void> MachineIRBuilder::validateInstruction(const MachineInstr &Instruc
   return {};
 }
 
+Expected<void> MachineIRBuilder::verifyInsertPoint() const {
+  if (InsertBlock == nullptr)
+    return makeUnexpected(ErrorCode::InvalidArgument, "machine IR builder has no insertion point");
+  auto BlockValidation = validateBlock(*InsertBlock);
+  if (!BlockValidation)
+    return std::unexpected(BlockValidation.error());
+  if (InsertBefore != nullptr && InsertBefore->parent() != InsertBlock) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "machine IR builder insertion cursor is no longer in its block");
+  }
+  return {};
+}
+
 Expected<void> MachineIRBuilder::setInsertPoint(MachineBasicBlock &Block) {
   auto Validation = validateBlock(Block);
   if (!Validation)
diff --git a/backend/lib/CodeGen/MachinePass.cpp b/backend/lib/CodeGen/MachinePass.cpp
new file mode 100644
index 0000000..e6dccd0
--- /dev/null
+++ b/backend/lib/CodeGen/MachinePass.cpp
@@ -0,0 +1,1370 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "rcc/CodeGen/MachinePass.h"
+
+#include "rcc/CodeGen/CompilationUnit.h"
+#include "rcc/CodeGen/MachineBasicBlock.h"
+#include "rcc/CodeGen/MachineFunction.h"
+#include "rcc/CodeGen/MachineFunctionCloner.h"
+#include "rcc/CodeGen/MachineInstr.h"
+#include "rcc/CodeGen/MachineOperand.h"
+#include "rcc/CodeGen/MachineVerifier.h"
+#include "rcc/CodeGen/TargetDescription.h"
+
+#include <algorithm>
+#include <atomic>
+#include <chrono>
+#include <cstddef>
+#include <cstdint>
+#include <limits>
+#include <memory>
+#include <optional>
+#include <ranges>
+#include <string>
+#include <string_view>
+#include <thread>
+#include <unordered_set>
+#include <utility>
+#include <vector>
+
+namespace rcc {
+
+thread_local MachinePassInstrumentation::BufferedEvents *MachinePassInstrumentation::ActiveBuffer =
+    nullptr;
+
+namespace {
+
+using Clock = std::chrono::steady_clock;
+
+[[nodiscard]] std::uint64_t elapsedNanoseconds(Clock::time_point Start) noexcept {
+  const auto Elapsed = std::chrono::duration_cast<std::chrono::nanoseconds>(Clock::now() - Start);
+  if (Elapsed.count() <= 0)
+    return 0;
+  return static_cast<std::uint64_t>(Elapsed.count());
+}
+
+[[nodiscard]] Error prefixedError(const Error &Source, std::string Prefix) {
+  Prefix.append(Source.message());
+  return Error(Source.code(), std::move(Prefix));
+}
+
+[[nodiscard]] bool hasDuplicateAnalysisIDs(std::span<const AnalysisID> IDs) {
+  std::unordered_set<AnalysisID> Unique;
+  for (const AnalysisID ID : IDs) {
+    if (ID == nullptr || !Unique.insert(ID).second)
+      return true;
+  }
+  return false;
+}
+
+[[nodiscard]] Expected<void> validateParameters(std::span<const PassParameter> Parameters) {
+  std::unordered_set<std::string> Names;
+  for (const PassParameter &Parameter : Parameters) {
+    if (Parameter.Name.empty())
+      return makeUnexpected(ErrorCode::InvalidArgument, "pass parameter name cannot be empty");
+    if (!Names.insert(Parameter.Name).second)
+      return makeUnexpected(ErrorCode::InvalidArgument, "pass parameter names must be unique");
+    if (Parameter.Required && Parameter.DefaultValue) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "a required pass parameter cannot have a default value");
+    }
+  }
+  return {};
+}
+
+void combineFingerprint(std::uint64_t &State, std::uint64_t Value) noexcept {
+  State ^= Value + 0x9e3779b97f4a7c15ULL + (State << 6U) + (State >> 2U);
+}
+
+[[nodiscard]] std::uint64_t machineFunctionFingerprint(const MachineFunction &Function) noexcept {
+  std::uint64_t Result = 0xcbf29ce484222325ULL;
+  combineFingerprint(Result, Function.stableID().value());
+  combineFingerprint(Result, Function.properties().rawValue());
+  combineFingerprint(Result, Function.blockCount());
+  combineFingerprint(Result, Function.allInstructions().size());
+  combineFingerprint(Result, Function.allMemOperands().size());
+
+  for (const MachineBasicBlock *Block = Function.firstBlock(); Block != nullptr;
+       Block = Block->next()) {
+    combineFingerprint(Result, Block->stableID().value());
+    combineFingerprint(Result, Block->instructionCount());
+    combineFingerprint(Result, Block->successors().size());
+    for (const MachineSuccessor &Successor : Block->successors()) {
+      combineFingerprint(Result,
+                         Successor.Block == nullptr ? 0 : Successor.Block->stableID().value());
+      combineFingerprint(Result, Successor.Probability.rawValue());
+    }
+    for (const MachineBasicBlockLiveIn &LiveIn : Block->liveIns()) {
+      combineFingerprint(Result, LiveIn.PhysReg.number());
+      combineFingerprint(Result, LiveIn.Lanes.rawValue());
+    }
+
+    for (const MachineInstr *Instruction = Block->firstInstruction(); Instruction != nullptr;
+         Instruction = Instruction->next()) {
+      combineFingerprint(Result, Instruction->stableID().value());
+      combineFingerprint(Result, Instruction->opcode().value());
+      combineFingerprint(Result, Instruction->flags().rawValue());
+      combineFingerprint(Result, Instruction->operandCount());
+      combineFingerprint(Result, Instruction->memOperands().size());
+      for (const MachineOperand &Operand : Instruction->operands()) {
+        combineFingerprint(Result, static_cast<std::uint64_t>(Operand.kind()));
+        combineFingerprint(Result, Operand.targetFlags());
+        combineFingerprint(Result, Operand.registerFlags().rawValue());
+        combineFingerprint(Result, Operand.subReg().value());
+        if (const Register *Reg = Operand.getIf<Register>())
+          combineFingerprint(Result, Reg->opaqueValue());
+        else if (const std::int64_t *Immediate = Operand.getIf<std::int64_t>())
+          combineFingerprint(Result, static_cast<std::uint64_t>(*Immediate));
+      }
+    }
+  }
+  return Result;
+}
+
+[[nodiscard]] Expected<void> verifyCompilationUnit(const CompilationUnit &Unit,
+                                                   const TargetDescription &Target) {
+  auto UnitVerification = Unit.verify();
+  if (!UnitVerification)
+    return std::unexpected(UnitVerification.error());
+  for (std::size_t Index = 0; Index < Unit.functionCount(); ++Index) {
+    const MachineFunction *Function = Unit.functionAt(Index);
+    if (Function == nullptr)
+      return makeUnexpected(ErrorCode::InternalError,
+                            "compilation unit function order contains a null entry");
+    auto FunctionVerification = MachineVerifier::verify(*Function, Target);
+    if (!FunctionVerification)
+      return std::unexpected(FunctionVerification.error());
+  }
+  return {};
+}
+
+} // namespace
+
+Expected<void>
+MachineAnalysisManager::registerAnalysisImpl(MachineAnalysisRegistration Registration,
+                                             ErasedRunner Runner, ErasedInvalidator Invalidator) {
+  if (Registration.ID == nullptr || Registration.Name.empty() || !Runner || !Invalidator) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "machine analysis registration is incomplete");
+  }
+  if (hasDuplicateAnalysisIDs(Registration.Dependencies)) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "machine analysis dependencies must be non-null and unique");
+  }
+  if (std::ranges::find(Registration.Dependencies, Registration.ID) !=
+      Registration.Dependencies.end()) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "machine analysis cannot directly depend on itself");
+  }
+  if (Registry.contains(Registration.ID))
+    return makeUnexpected(ErrorCode::InvalidArgument, "machine analysis ID is already registered");
+  if (std::ranges::any_of(Registry, [&Registration](const auto &Entry) {
+        return Entry.second.Info.Name == Registration.Name;
+      })) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "machine analysis name is already registered");
+  }
+  Registry.emplace(Registration.ID, RegisteredAnalysis{std::move(Registration), std::move(Runner),
+                                                       std::move(Invalidator)});
+  return {};
+}
+
+bool MachineAnalysisManager::isRegistered(AnalysisID ID) const noexcept {
+  return ID != nullptr && Registry.contains(ID);
+}
+
+bool MachineAnalysisManager::hasCached(const MachineFunction &Function,
+                                       AnalysisID ID) const noexcept {
+  const auto FunctionPosition = Cache.find(const_cast<MachineFunction *>(&Function));
+  if (FunctionPosition == Cache.end())
+    return false;
+  const auto AnalysisPosition = FunctionPosition->second.find(ID);
+  return AnalysisPosition != FunctionPosition->second.end() && AnalysisPosition->second.Value;
+}
+
+std::size_t
+MachineAnalysisManager::cachedResultCount(const MachineFunction &Function) const noexcept {
+  const auto Position = Cache.find(const_cast<MachineFunction *>(&Function));
+  return Position == Cache.end() ? 0 : Position->second.size();
+}
+
+Expected<void>
+MachineAnalysisManager::materializeDependencies(const RegisteredAnalysis &Registration,
+                                                MachineFunction &Function,
+                                                const TargetDescription &Target) {
+  for (const AnalysisID Dependency : Registration.Info.Dependencies) {
+    if (!Registry.contains(Dependency)) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "machine analysis depends on an unregistered analysis");
+    }
+    auto Result = getResultImpl(Dependency, Function, Target);
+    if (!Result)
+      return std::unexpected(Result.error());
+  }
+  return {};
+}
+
+Expected<void *> MachineAnalysisManager::getResultImpl(AnalysisID ID, MachineFunction &Function,
+                                                       const TargetDescription &Target) {
+  if (ID == nullptr)
+    return makeUnexpected(ErrorCode::InvalidArgument, "machine analysis ID cannot be null");
+
+  auto &FunctionCache = Cache[&Function];
+  if (const auto Cached = FunctionCache.find(ID);
+      Cached != FunctionCache.end() && Cached->second.Value) {
+    const auto Registration = Registry.find(ID);
+    const std::string_view Name = Registration == Registry.end()
+                                      ? std::string_view{"unknown-machine-analysis"}
+                                      : std::string_view{Registration->second.Info.Name};
+    if (Instrumentation != nullptr)
+      Instrumentation->afterAnalysis(Name, Function, true, 0);
+    return Cached->second.Value.get();
+  }
+
+  const auto RegistrationPosition = Registry.find(ID);
+  if (RegistrationPosition == Registry.end())
+    return makeUnexpected(ErrorCode::InvalidArgument, "machine analysis ID is not registered");
+  const RegisteredAnalysis &Registration = RegistrationPosition->second;
+
+  auto &Stack = ActiveComputations[&Function];
+  if (std::ranges::find(Stack, ID) != Stack.end()) {
+    Error Failure(ErrorCode::InvalidArgument,
+                  "machine analysis dependency cycle reaches '" + Registration.Info.Name + "'");
+    if (Instrumentation != nullptr)
+      Instrumentation->analysisFailure(Registration.Info.Name, Function, Failure, 0);
+    return std::unexpected(std::move(Failure));
+  }
+
+  if (Instrumentation != nullptr)
+    Instrumentation->beforeAnalysis(Registration.Info.Name, Function);
+  const Clock::time_point Start = Clock::now();
+  Stack.push_back(ID);
+  auto Dependencies = materializeDependencies(Registration, Function, Target);
+  if (!Dependencies) {
+    Stack.pop_back();
+    if (Stack.empty())
+      ActiveComputations.erase(&Function);
+    Error Failure = prefixedError(Dependencies.error(),
+                                  "machine analysis '" + Registration.Info.Name + "' failed: ");
+    if (Instrumentation != nullptr) {
+      Instrumentation->analysisFailure(Registration.Info.Name, Function, Failure,
+                                       elapsedNanoseconds(Start));
+    }
+    return std::unexpected(std::move(Failure));
+  }
+
+  auto Computed = Registration.Runner(Function, Target, *this);
+  Stack.pop_back();
+  if (Stack.empty())
+    ActiveComputations.erase(&Function);
+  const std::uint64_t Duration = elapsedNanoseconds(Start);
+  if (!Computed) {
+    Error Failure = prefixedError(Computed.error(),
+                                  "machine analysis '" + Registration.Info.Name + "' failed: ");
+    if (Instrumentation != nullptr)
+      Instrumentation->analysisFailure(Registration.Info.Name, Function, Failure, Duration);
+    return std::unexpected(std::move(Failure));
+  }
+  if (!*Computed) {
+    Error Failure(ErrorCode::InternalError,
+                  "machine analysis '" + Registration.Info.Name + "' returned a null result");
+    if (Instrumentation != nullptr)
+      Instrumentation->analysisFailure(Registration.Info.Name, Function, Failure, Duration);
+    return std::unexpected(std::move(Failure));
+  }
+
+  void *Result = Computed->get();
+  FunctionCache.emplace(ID, CacheEntry{std::move(*Computed), ID});
+  if (Instrumentation != nullptr)
+    Instrumentation->afterAnalysis(Registration.Info.Name, Function, false, Duration);
+  return Result;
+}
+
+void MachineAnalysisManager::invalidate(MachineFunction &Function,
+                                        const PreservedAnalyses &Preserved,
+                                        MachinePassChanges Changes) noexcept {
+  const auto FunctionPosition = Cache.find(&Function);
+  if (FunctionPosition == Cache.end() || Preserved.preservesAll() || Changes.empty())
+    return;
+
+  std::unordered_set<AnalysisID> Invalid;
+  for (auto &[ID, Entry] : FunctionPosition->second) {
+    if (Preserved.preserves(ID))
+      continue;
+    const auto Registration = Registry.find(ID);
+    if (Registration == Registry.end() ||
+        Registration->second.Info.InvalidatedBy.intersects(Changes)) {
+      const bool ShouldInvalidate =
+          Registration == Registry.end() || !Entry.Value || !Registration->second.Invalidator ||
+          Registration->second.Invalidator(Entry.Value.get(), Function, Preserved);
+      if (ShouldInvalidate)
+        Invalid.insert(ID);
+    }
+  }
+
+  bool Added = true;
+  while (Added) {
+    Added = false;
+    for (const auto &[ID, Entry] : FunctionPosition->second) {
+      (void)Entry;
+      if (Invalid.contains(ID) || Preserved.preserves(ID))
+        continue;
+      const auto Registration = Registry.find(ID);
+      if (Registration != Registry.end() &&
+          std::ranges::any_of(
+              Registration->second.Info.Dependencies,
+              [&Invalid](AnalysisID Dependency) { return Invalid.contains(Dependency); })) {
+        Added = Invalid.insert(ID).second || Added;
+      }
+    }
+  }
+
+  for (const AnalysisID ID : Invalid)
+    FunctionPosition->second.erase(ID);
+  if (FunctionPosition->second.empty())
+    Cache.erase(FunctionPosition);
+}
+
+void MachineAnalysisManager::clear(MachineFunction &Function) noexcept {
+  Cache.erase(&Function);
+  ActiveComputations.erase(&Function);
+}
+
+void MachineAnalysisManager::clearAll() noexcept {
+  Cache.clear();
+  ActiveComputations.clear();
+}
+
+Expected<std::unique_ptr<MachineAnalysisManager>> MachineAnalysisManager::forkEmpty() const {
+  if (!ActiveComputations.empty()) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "cannot fork a machine analysis manager during analysis computation");
+  }
+  auto Result = std::make_unique<MachineAnalysisManager>();
+  Result->Registry = Registry;
+  return Result;
+}
+
+Expected<void> MachineAnalysisManager::validateParallelRequirements(
+    std::span<const AnalysisID> RequiredAnalyses) const {
+  std::vector<AnalysisID> Worklist(RequiredAnalyses.begin(), RequiredAnalyses.end());
+  std::unordered_set<AnalysisID> Visited;
+  for (std::size_t Index = 0; Index < Worklist.size(); ++Index) {
+    const AnalysisID ID = Worklist[Index];
+    if (ID == nullptr || !Visited.insert(ID).second)
+      continue;
+    const auto Position = Registry.find(ID);
+    if (Position == Registry.end()) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "parallel machine pass requires an unregistered analysis");
+    }
+    if (Position->second.Info.ThreadSafety != PassThreadSafety::ThreadSafe) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "parallel machine pipeline requires analysis '" +
+                                Position->second.Info.Name + "' to be marked thread-safe");
+    }
+    Worklist.insert(Worklist.end(), Position->second.Info.Dependencies.begin(),
+                    Position->second.Info.Dependencies.end());
+  }
+  return {};
+}
+
+Expected<bool> MachineAnalysisManager::requestAction(std::string_view Action,
+                                                     const MachineFunction &Function,
+                                                     std::uint64_t Cost) {
+  if (Action.empty() || Cost == 0)
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "machine action requires a name and nonzero cost");
+  if (Instrumentation == nullptr)
+    return true;
+  return Instrumentation->requestAction(Action, Function, Cost);
+}
+
+Expected<void> CompilationUnitAnalysisManager::registerAnalysisImpl(
+    CompilationUnitAnalysisRegistration Registration, ErasedRunner Runner,
+    ErasedInvalidator Invalidator) {
+  if (Registration.ID == nullptr || Registration.Name.empty() || !Runner || !Invalidator) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "compilation-unit analysis registration is incomplete");
+  }
+  if (hasDuplicateAnalysisIDs(Registration.Dependencies)) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "compilation-unit analysis dependencies must be non-null and unique");
+  }
+  if (std::ranges::find(Registration.Dependencies, Registration.ID) !=
+      Registration.Dependencies.end()) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "compilation-unit analysis cannot directly depend on itself");
+  }
+  if (Registry.contains(Registration.ID)) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "compilation-unit analysis ID is already registered");
+  }
+  if (std::ranges::any_of(Registry, [&Registration](const auto &Entry) {
+        return Entry.second.Info.Name == Registration.Name;
+      })) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "compilation-unit analysis name is already registered");
+  }
+  Registry.emplace(Registration.ID, RegisteredAnalysis{std::move(Registration), std::move(Runner),
+                                                       std::move(Invalidator)});
+  return {};
+}
+
+bool CompilationUnitAnalysisManager::isRegistered(AnalysisID ID) const noexcept {
+  return ID != nullptr && Registry.contains(ID);
+}
+
+bool CompilationUnitAnalysisManager::hasCached(const CompilationUnit &Unit,
+                                               AnalysisID ID) const noexcept {
+  const auto UnitPosition = Cache.find(const_cast<CompilationUnit *>(&Unit));
+  if (UnitPosition == Cache.end())
+    return false;
+  const auto AnalysisPosition = UnitPosition->second.find(ID);
+  return AnalysisPosition != UnitPosition->second.end() && AnalysisPosition->second.Value;
+}
+
+Expected<void>
+CompilationUnitAnalysisManager::materializeDependencies(const RegisteredAnalysis &Registration,
+                                                        CompilationUnit &Unit,
+                                                        const TargetDescription &Target) {
+  for (const AnalysisID Dependency : Registration.Info.Dependencies) {
+    if (!Registry.contains(Dependency)) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "compilation-unit analysis depends on an unregistered analysis");
+    }
+    auto Result = getResultImpl(Dependency, Unit, Target);
+    if (!Result)
+      return std::unexpected(Result.error());
+  }
+  return {};
+}
+
+Expected<void *> CompilationUnitAnalysisManager::getResultImpl(AnalysisID ID, CompilationUnit &Unit,
+                                                               const TargetDescription &Target) {
+  if (ID == nullptr)
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "compilation-unit analysis ID cannot be null");
+  auto &UnitCache = Cache[&Unit];
+  if (const auto Cached = UnitCache.find(ID); Cached != UnitCache.end() && Cached->second.Value) {
+    const auto Registration = Registry.find(ID);
+    const std::string_view Name = Registration == Registry.end()
+                                      ? std::string_view{"unknown-compilation-unit-analysis"}
+                                      : std::string_view{Registration->second.Info.Name};
+    if (Instrumentation != nullptr)
+      Instrumentation->afterUnitAnalysis(Name, Unit, true, 0);
+    return Cached->second.Value.get();
+  }
+
+  const auto RegistrationPosition = Registry.find(ID);
+  if (RegistrationPosition == Registry.end()) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "compilation-unit analysis ID is not registered");
+  }
+  const RegisteredAnalysis &Registration = RegistrationPosition->second;
+  auto &Stack = ActiveComputations[&Unit];
+  if (std::ranges::find(Stack, ID) != Stack.end()) {
+    Error Failure(ErrorCode::InvalidArgument,
+                  "compilation-unit analysis dependency cycle reaches '" + Registration.Info.Name +
+                      "'");
+    if (Instrumentation != nullptr)
+      Instrumentation->unitAnalysisFailure(Registration.Info.Name, Unit, Failure, 0);
+    return std::unexpected(std::move(Failure));
+  }
+
+  if (Instrumentation != nullptr)
+    Instrumentation->beforeUnitAnalysis(Registration.Info.Name, Unit);
+  const Clock::time_point Start = Clock::now();
+  Stack.push_back(ID);
+  auto Dependencies = materializeDependencies(Registration, Unit, Target);
+  if (!Dependencies) {
+    Stack.pop_back();
+    if (Stack.empty())
+      ActiveComputations.erase(&Unit);
+    Error Failure = prefixedError(Dependencies.error(), "compilation-unit analysis '" +
+                                                            Registration.Info.Name + "' failed: ");
+    if (Instrumentation != nullptr) {
+      Instrumentation->unitAnalysisFailure(Registration.Info.Name, Unit, Failure,
+                                           elapsedNanoseconds(Start));
+    }
+    return std::unexpected(std::move(Failure));
+  }
+
+  auto Computed = Registration.Runner(Unit, Target, *this);
+  Stack.pop_back();
+  if (Stack.empty())
+    ActiveComputations.erase(&Unit);
+  const std::uint64_t Duration = elapsedNanoseconds(Start);
+  if (!Computed) {
+    Error Failure = prefixedError(Computed.error(), "compilation-unit analysis '" +
+                                                        Registration.Info.Name + "' failed: ");
+    if (Instrumentation != nullptr)
+      Instrumentation->unitAnalysisFailure(Registration.Info.Name, Unit, Failure, Duration);
+    return std::unexpected(std::move(Failure));
+  }
+  if (!*Computed) {
+    Error Failure(ErrorCode::InternalError, "compilation-unit analysis '" + Registration.Info.Name +
+                                                "' returned a null result");
+    if (Instrumentation != nullptr)
+      Instrumentation->unitAnalysisFailure(Registration.Info.Name, Unit, Failure, Duration);
+    return std::unexpected(std::move(Failure));
+  }
+
+  void *Result = Computed->get();
+  UnitCache.emplace(ID, CacheEntry{std::move(*Computed), ID});
+  if (Instrumentation != nullptr)
+    Instrumentation->afterUnitAnalysis(Registration.Info.Name, Unit, false, Duration);
+  return Result;
+}
+
+void CompilationUnitAnalysisManager::invalidate(CompilationUnit &Unit,
+                                                const PreservedAnalyses &Preserved,
+                                                MachinePassChanges Changes) noexcept {
+  const auto UnitPosition = Cache.find(&Unit);
+  if (UnitPosition == Cache.end() || Preserved.preservesAll() || Changes.empty())
+    return;
+
+  std::unordered_set<AnalysisID> Invalid;
+  for (auto &[ID, Entry] : UnitPosition->second) {
+    if (Preserved.preserves(ID))
+      continue;
+    const auto Registration = Registry.find(ID);
+    if (Registration == Registry.end() ||
+        Registration->second.Info.InvalidatedBy.intersects(Changes)) {
+      const bool ShouldInvalidate =
+          Registration == Registry.end() || !Entry.Value || !Registration->second.Invalidator ||
+          Registration->second.Invalidator(Entry.Value.get(), Unit, Preserved);
+      if (ShouldInvalidate)
+        Invalid.insert(ID);
+    }
+  }
+
+  bool Added = true;
+  while (Added) {
+    Added = false;
+    for (const auto &[ID, Entry] : UnitPosition->second) {
+      (void)Entry;
+      if (Invalid.contains(ID) || Preserved.preserves(ID))
+        continue;
+      const auto Registration = Registry.find(ID);
+      if (Registration != Registry.end() &&
+          std::ranges::any_of(
+              Registration->second.Info.Dependencies,
+              [&Invalid](AnalysisID Dependency) { return Invalid.contains(Dependency); })) {
+        Added = Invalid.insert(ID).second || Added;
+      }
+    }
+  }
+  for (const AnalysisID InvalidID : Invalid)
+    UnitPosition->second.erase(InvalidID);
+  if (UnitPosition->second.empty())
+    Cache.erase(UnitPosition);
+}
+
+void CompilationUnitAnalysisManager::clear(CompilationUnit &Unit) noexcept {
+  Cache.erase(&Unit);
+  ActiveComputations.erase(&Unit);
+}
+
+void CompilationUnitAnalysisManager::clearAll() noexcept {
+  Cache.clear();
+  ActiveComputations.clear();
+}
+
+void MachinePassInstrumentation::addBeforeCallback(BeforeCallback Callback) {
+  if (!Callback)
+    return;
+  std::scoped_lock Lock(Mutex);
+  Before.push_back(std::move(Callback));
+}
+
+void MachinePassInstrumentation::addAfterCallback(AfterCallback Callback) {
+  if (!Callback)
+    return;
+  std::scoped_lock Lock(Mutex);
+  After.push_back(std::move(Callback));
+}
+
+void MachinePassInstrumentation::addFailureCallback(FailureCallback Callback) {
+  if (!Callback)
+    return;
+  std::scoped_lock Lock(Mutex);
+  Failure.push_back(std::move(Callback));
+}
+
+void MachinePassInstrumentation::addBeforeAnalysisCallback(BeforeAnalysisCallback Callback) {
+  if (!Callback)
+    return;
+  std::scoped_lock Lock(Mutex);
+  BeforeAnalysis.push_back(std::move(Callback));
+}
+
+void MachinePassInstrumentation::addAfterAnalysisCallback(AfterAnalysisCallback Callback) {
+  if (!Callback)
+    return;
+  std::scoped_lock Lock(Mutex);
+  AfterAnalysis.push_back(std::move(Callback));
+}
+
+void MachinePassInstrumentation::addAnalysisFailureCallback(AnalysisFailureCallback Callback) {
+  if (!Callback)
+    return;
+  std::scoped_lock Lock(Mutex);
+  AnalysisFailure.push_back(std::move(Callback));
+}
+
+void MachinePassInstrumentation::addIRPrintCallback(IRPrintCallback Callback) {
+  if (!Callback)
+    return;
+  std::scoped_lock Lock(Mutex);
+  IRPrint.push_back(std::move(Callback));
+}
+
+void MachinePassInstrumentation::addChangeCallback(ChangeCallback Callback) {
+  if (!Callback)
+    return;
+  std::scoped_lock Lock(Mutex);
+  Change.push_back(std::move(Callback));
+}
+
+void MachinePassInstrumentation::setActionFilter(ActionFilter NewFilter) {
+  std::scoped_lock Lock(Mutex);
+  Filter = std::move(NewFilter);
+}
+
+void MachinePassInstrumentation::setPerFunctionFuel(std::optional<std::uint64_t> Fuel) {
+  std::scoped_lock Lock(Mutex);
+  PerFunctionFuel = Fuel;
+  ConsumedFuel.clear();
+}
+
+void MachinePassInstrumentation::addBeforeUnitCallback(BeforeUnitCallback Callback) {
+  if (!Callback)
+    return;
+  std::scoped_lock Lock(Mutex);
+  BeforeUnit.push_back(std::move(Callback));
+}
+
+void MachinePassInstrumentation::addAfterUnitCallback(AfterUnitCallback Callback) {
+  if (!Callback)
+    return;
+  std::scoped_lock Lock(Mutex);
+  AfterUnit.push_back(std::move(Callback));
+}
+
+void MachinePassInstrumentation::addUnitFailureCallback(UnitFailureCallback Callback) {
+  if (!Callback)
+    return;
+  std::scoped_lock Lock(Mutex);
+  UnitFailure.push_back(std::move(Callback));
+}
+
+void MachinePassInstrumentation::addBeforeUnitAnalysisCallback(
+    BeforeUnitAnalysisCallback Callback) {
+  if (!Callback)
+    return;
+  std::scoped_lock Lock(Mutex);
+  BeforeUnitAnalysis.push_back(std::move(Callback));
+}
+
+void MachinePassInstrumentation::addAfterUnitAnalysisCallback(AfterUnitAnalysisCallback Callback) {
+  if (!Callback)
+    return;
+  std::scoped_lock Lock(Mutex);
+  AfterUnitAnalysis.push_back(std::move(Callback));
+}
+
+void MachinePassInstrumentation::addUnitAnalysisFailureCallback(
+    UnitAnalysisFailureCallback Callback) {
+  if (!Callback)
+    return;
+  std::scoped_lock Lock(Mutex);
+  UnitAnalysisFailure.push_back(std::move(Callback));
+}
+
+InstrumentationStatistic &MachinePassInstrumentation::statistic(std::string_view Name,
+                                                                bool IsAnalysis) const {
+  const std::string Key = std::string(IsAnalysis ? "analysis:" : "pass:") + std::string(Name);
+  auto [Position, Inserted] = Statistics.try_emplace(Key);
+  if (Inserted) {
+    Position->second.Name = std::string(Name);
+    Position->second.IsAnalysis = IsAnalysis;
+  }
+  return Position->second;
+}
+
+bool MachinePassInstrumentation::bufferFunctionEvent(
+    const MachineFunction &Function, std::function<void(const MachineFunction &)> Replay) const {
+  if (ActiveBuffer == nullptr)
+    return false;
+
+  std::shared_ptr<const MachineFunction> Snapshot;
+  auto Cloned = cloneMachineFunction(
+      Function, *ActiveBuffer->Target,
+      MachineFunctionCloneOptions{.NewStableID = Function.stableID(), .NewName = std::nullopt});
+  if (Cloned) {
+    Snapshot = std::shared_ptr<const MachineFunction>(std::move(Cloned->ClonedFunction));
+  } else {
+    Snapshot =
+        std::shared_ptr<const MachineFunction>(&Function, [](const MachineFunction *) noexcept {});
+  }
+  ActiveBuffer->Events.emplace_back(
+      [Snapshot = std::move(Snapshot), Replay = std::move(Replay)]() { Replay(*Snapshot); });
+  return true;
+}
+
+void MachinePassInstrumentation::beginBuffering(BufferedEvents &Buffer,
+                                                const TargetDescription &Target) const noexcept {
+  Buffer.Target = &Target;
+  Buffer.Events.clear();
+  ActiveBuffer = &Buffer;
+}
+
+void MachinePassInstrumentation::endBuffering() const noexcept {
+  ActiveBuffer = nullptr;
+}
+
+void MachinePassInstrumentation::replayBufferedEvents(BufferedEvents &Buffer) const {
+  for (const std::function<void()> &Event : Buffer.Events)
+    Event();
+  Buffer.Events.clear();
+  Buffer.Target = nullptr;
+}
+
+void MachinePassInstrumentation::before(std::string_view Name,
+                                        const MachineFunction &Function) const {
+  if (bufferFunctionEvent(Function, [this, Name = std::string(Name)](const MachineFunction &Input) {
+        before(Name, Input);
+      })) {
+    return;
+  }
+  std::vector<BeforeCallback> Callbacks;
+  std::vector<IRPrintCallback> Printers;
+  {
+    std::scoped_lock Lock(Mutex);
+    Callbacks = Before;
+    Printers = IRPrint;
+  }
+  for (const BeforeCallback &Callback : Callbacks)
+    Callback(Name, Function);
+  for (const IRPrintCallback &Printer : Printers)
+    Printer(InstrumentationPhase::Before, Name, Function);
+}
+
+void MachinePassInstrumentation::after(std::string_view Name, const MachineFunction &Function,
+                                       const MachinePassResult &Result,
+                                       std::uint64_t Nanoseconds) const {
+  if (bufferFunctionEvent(Function, [this, Name = std::string(Name), Result,
+                                     Nanoseconds](const MachineFunction &Input) {
+        after(Name, Input, Result, Nanoseconds);
+      })) {
+    return;
+  }
+  std::vector<AfterCallback> Callbacks;
+  std::vector<IRPrintCallback> Printers;
+  {
+    std::scoped_lock Lock(Mutex);
+    InstrumentationStatistic &Record = statistic(Name, false);
+    ++Record.Invocations;
+    Record.Changes += Result.Changed ? 1U : 0U;
+    Record.TotalNanoseconds += Nanoseconds;
+    Callbacks = After;
+    Printers = IRPrint;
+  }
+  for (const AfterCallback &Callback : Callbacks)
+    Callback(Name, Function, Result);
+  for (const IRPrintCallback &Printer : Printers)
+    Printer(InstrumentationPhase::After, Name, Function);
+}
+
+void MachinePassInstrumentation::failure(std::string_view Name, const MachineFunction &Function,
+                                         const Error &ErrorValue, std::uint64_t Nanoseconds) const {
+  if (bufferFunctionEvent(Function, [this, Name = std::string(Name), ErrorValue,
+                                     Nanoseconds](const MachineFunction &Input) {
+        failure(Name, Input, ErrorValue, Nanoseconds);
+      })) {
+    return;
+  }
+  std::vector<FailureCallback> Callbacks;
+  {
+    std::scoped_lock Lock(Mutex);
+    InstrumentationStatistic &Record = statistic(Name, false);
+    ++Record.Invocations;
+    ++Record.Failures;
+    Record.TotalNanoseconds += Nanoseconds;
+    Callbacks = Failure;
+  }
+  for (const FailureCallback &Callback : Callbacks)
+    Callback(Name, Function, ErrorValue);
+}
+
+void MachinePassInstrumentation::beforeAnalysis(std::string_view Name,
+                                                const MachineFunction &Function) const {
+  if (bufferFunctionEvent(Function, [this, Name = std::string(Name)](const MachineFunction &Input) {
+        beforeAnalysis(Name, Input);
+      })) {
+    return;
+  }
+  std::vector<BeforeAnalysisCallback> Callbacks;
+  {
+    std::scoped_lock Lock(Mutex);
+    Callbacks = BeforeAnalysis;
+  }
+  for (const BeforeAnalysisCallback &Callback : Callbacks)
+    Callback(Name, Function);
+}
+
+void MachinePassInstrumentation::afterAnalysis(std::string_view Name,
+                                               const MachineFunction &Function, bool CacheHit,
+                                               std::uint64_t Nanoseconds) const {
+  if (bufferFunctionEvent(Function, [this, Name = std::string(Name), CacheHit,
+                                     Nanoseconds](const MachineFunction &Input) {
+        afterAnalysis(Name, Input, CacheHit, Nanoseconds);
+      })) {
+    return;
+  }
+  std::vector<AfterAnalysisCallback> Callbacks;
+  {
+    std::scoped_lock Lock(Mutex);
+    InstrumentationStatistic &Record = statistic(Name, true);
+    ++Record.Invocations;
+    Record.CacheHits += CacheHit ? 1U : 0U;
+    Record.TotalNanoseconds += Nanoseconds;
+    Callbacks = AfterAnalysis;
+  }
+  for (const AfterAnalysisCallback &Callback : Callbacks)
+    Callback(Name, Function, CacheHit, Nanoseconds);
+}
+
+void MachinePassInstrumentation::analysisFailure(std::string_view Name,
+                                                 const MachineFunction &Function,
+                                                 const Error &ErrorValue,
+                                                 std::uint64_t Nanoseconds) const {
+  if (bufferFunctionEvent(Function, [this, Name = std::string(Name), ErrorValue,
+                                     Nanoseconds](const MachineFunction &Input) {
+        analysisFailure(Name, Input, ErrorValue, Nanoseconds);
+      })) {
+    return;
+  }
+  std::vector<AnalysisFailureCallback> Callbacks;
+  {
+    std::scoped_lock Lock(Mutex);
+    InstrumentationStatistic &Record = statistic(Name, true);
+    ++Record.Invocations;
+    ++Record.Failures;
+    Record.TotalNanoseconds += Nanoseconds;
+    Callbacks = AnalysisFailure;
+  }
+  for (const AnalysisFailureCallback &Callback : Callbacks)
+    Callback(Name, Function, ErrorValue);
+}
+
+void MachinePassInstrumentation::change(std::string_view Name, const MachineFunction &Function,
+                                        MachinePassChanges Changes, bool FingerprintChanged) const {
+  if (bufferFunctionEvent(Function, [this, Name = std::string(Name), Changes,
+                                     FingerprintChanged](const MachineFunction &Input) {
+        change(Name, Input, Changes, FingerprintChanged);
+      })) {
+    return;
+  }
+  std::vector<ChangeCallback> Callbacks;
+  {
+    std::scoped_lock Lock(Mutex);
+    Callbacks = Change;
+  }
+  for (const ChangeCallback &Callback : Callbacks)
+    Callback(Name, Function, Changes, FingerprintChanged);
+}
+
+Expected<bool> MachinePassInstrumentation::requestAction(std::string_view Action,
+                                                         const MachineFunction &Function,
+                                                         std::uint64_t Cost) {
+  std::scoped_lock ActionLock(ActionMutex);
+  ActionFilter CurrentFilter;
+  {
+    std::scoped_lock Lock(Mutex);
+    CurrentFilter = Filter;
+  }
+  if (CurrentFilter && !CurrentFilter(Action, Function, Cost))
+    return false;
+
+  std::scoped_lock Lock(Mutex);
+  if (!PerFunctionFuel)
+    return true;
+  std::uint64_t &Consumed = ConsumedFuel[Function.stableID().value()];
+  if (Consumed > *PerFunctionFuel || Cost > *PerFunctionFuel - Consumed)
+    return false;
+  Consumed += Cost;
+  return true;
+}
+
+void MachinePassInstrumentation::beforeUnit(std::string_view Name,
+                                            const CompilationUnit &Unit) const {
+  std::vector<BeforeUnitCallback> Callbacks;
+  {
+    std::scoped_lock Lock(Mutex);
+    Callbacks = BeforeUnit;
+  }
+  for (const BeforeUnitCallback &Callback : Callbacks)
+    Callback(Name, Unit);
+}
+
+void MachinePassInstrumentation::afterUnit(std::string_view Name, const CompilationUnit &Unit,
+                                           const CompilationUnitPassResult &Result,
+                                           std::uint64_t Nanoseconds) const {
+  std::vector<AfterUnitCallback> Callbacks;
+  {
+    std::scoped_lock Lock(Mutex);
+    InstrumentationStatistic &Record = statistic("unit:" + std::string(Name), false);
+    ++Record.Invocations;
+    Record.Changes += Result.Changed ? 1U : 0U;
+    Record.TotalNanoseconds += Nanoseconds;
+    Callbacks = AfterUnit;
+  }
+  for (const AfterUnitCallback &Callback : Callbacks)
+    Callback(Name, Unit, Result);
+}
+
+void MachinePassInstrumentation::unitFailure(std::string_view Name, const CompilationUnit &Unit,
+                                             const Error &ErrorValue,
+                                             std::uint64_t Nanoseconds) const {
+  std::vector<UnitFailureCallback> Callbacks;
+  {
+    std::scoped_lock Lock(Mutex);
+    InstrumentationStatistic &Record = statistic("unit:" + std::string(Name), false);
+    ++Record.Invocations;
+    ++Record.Failures;
+    Record.TotalNanoseconds += Nanoseconds;
+    Callbacks = UnitFailure;
+  }
+  for (const UnitFailureCallback &Callback : Callbacks)
+    Callback(Name, Unit, ErrorValue);
+}
+
+void MachinePassInstrumentation::beforeUnitAnalysis(std::string_view Name,
+                                                    const CompilationUnit &Unit) const {
+  std::vector<BeforeUnitAnalysisCallback> Callbacks;
+  {
+    std::scoped_lock Lock(Mutex);
+    Callbacks = BeforeUnitAnalysis;
+  }
+  for (const BeforeUnitAnalysisCallback &Callback : Callbacks)
+    Callback(Name, Unit);
+}
+
+void MachinePassInstrumentation::afterUnitAnalysis(std::string_view Name,
+                                                   const CompilationUnit &Unit, bool CacheHit,
+                                                   std::uint64_t Nanoseconds) const {
+  std::vector<AfterUnitAnalysisCallback> Callbacks;
+  {
+    std::scoped_lock Lock(Mutex);
+    InstrumentationStatistic &Record = statistic("unit:" + std::string(Name), true);
+    ++Record.Invocations;
+    Record.CacheHits += CacheHit ? 1U : 0U;
+    Record.TotalNanoseconds += Nanoseconds;
+    Callbacks = AfterUnitAnalysis;
+  }
+  for (const AfterUnitAnalysisCallback &Callback : Callbacks)
+    Callback(Name, Unit, CacheHit, Nanoseconds);
+}
+
+void MachinePassInstrumentation::unitAnalysisFailure(std::string_view Name,
+                                                     const CompilationUnit &Unit,
+                                                     const Error &ErrorValue,
+                                                     std::uint64_t Nanoseconds) const {
+  std::vector<UnitAnalysisFailureCallback> Callbacks;
+  {
+    std::scoped_lock Lock(Mutex);
+    InstrumentationStatistic &Record = statistic("unit:" + std::string(Name), true);
+    ++Record.Invocations;
+    ++Record.Failures;
+    Record.TotalNanoseconds += Nanoseconds;
+    Callbacks = UnitAnalysisFailure;
+  }
+  for (const UnitAnalysisFailureCallback &Callback : Callbacks)
+    Callback(Name, Unit, ErrorValue);
+}
+
+std::vector<InstrumentationStatistic> MachinePassInstrumentation::statistics() const {
+  std::vector<InstrumentationStatistic> Result;
+  {
+    std::scoped_lock Lock(Mutex);
+    Result.reserve(Statistics.size());
+    for (const auto &[Key, Record] : Statistics) {
+      (void)Key;
+      Result.push_back(Record);
+    }
+  }
+  std::ranges::sort(
+      Result, [](const InstrumentationStatistic &Left, const InstrumentationStatistic &Right) {
+        if (Left.IsAnalysis != Right.IsAnalysis)
+          return Left.IsAnalysis < Right.IsAnalysis;
+        return Left.Name < Right.Name;
+      });
+  return Result;
+}
+
+void MachinePassInstrumentation::clearStatistics() {
+  std::scoped_lock Lock(Mutex);
+  Statistics.clear();
+  ConsumedFuel.clear();
+}
+
+Expected<void> MachinePassManager::validateContract(const MachinePassContract &Contract) const {
+  if (Contract.Name.empty())
+    return makeUnexpected(ErrorCode::InvalidArgument, "machine pass must have a non-empty name");
+  if (Contract.Sets.intersects(Contract.Clears)) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "machine pass cannot set and clear the same property");
+  }
+  if (hasDuplicateAnalysisIDs(Contract.RequiredAnalyses)) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "machine pass required analyses must be non-null and unique");
+  }
+  return validateParameters(Contract.Parameters);
+}
+
+Expected<void> MachinePassManager::addPass(std::unique_ptr<MachineFunctionPass> Pass) {
+  if (!Pass)
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "machine pass manager cannot add a null pass");
+  auto Validation = validateContract(Pass->contract());
+  if (!Validation)
+    return std::unexpected(Validation.error());
+  Passes.push_back(std::move(Pass));
+  return {};
+}
+
+Expected<void> MachinePassManager::run(MachineFunction &Function, const TargetDescription &Target,
+                                       MachineAnalysisManager &Analyses,
+                                       MachinePassInstrumentation *Instrumentation) const {
+  Analyses.setInstrumentation(Instrumentation);
+  for (const std::unique_ptr<MachineFunctionPass> &Pass : Passes) {
+    const MachinePassContract &Contract = Pass->contract();
+    const std::string_view Name = Contract.Name;
+
+    if (const MachineFunctionProperties Missing =
+            Contract.Requires.missingFrom(Function.properties());
+        !Missing.empty()) {
+      Error Failure(ErrorCode::VerificationError,
+                    "pass '" + std::string(Name) + "' requires properties: " + Missing.toString());
+      if (Instrumentation != nullptr)
+        Instrumentation->failure(Name, Function, Failure);
+      Analyses.setInstrumentation(nullptr);
+      return std::unexpected(std::move(Failure));
+    }
+
+    if (Options.VerifyBefore) {
+      auto Verification = MachineVerifier::verify(Function, Target);
+      if (!Verification) {
+        Error Failure = prefixedError(Verification.error(), "pass '" + std::string(Name) +
+                                                                "' received invalid MachineIR: ");
+        if (Instrumentation != nullptr)
+          Instrumentation->failure(Name, Function, Failure);
+        Analyses.setInstrumentation(nullptr);
+        return std::unexpected(std::move(Failure));
+      }
+    }
+
+    for (const AnalysisID Required : Contract.RequiredAnalyses) {
+      auto Result = Analyses.getResultImpl(Required, Function, Target);
+      if (!Result) {
+        Error Failure =
+            prefixedError(Result.error(), "pass '" + std::string(Name) +
+                                              "' could not materialize a required analysis: ");
+        if (Instrumentation != nullptr)
+          Instrumentation->failure(Name, Function, Failure);
+        Analyses.setInstrumentation(nullptr);
+        return std::unexpected(std::move(Failure));
+      }
+    }
+
+    const std::uint64_t FingerprintBefore =
+        Options.DetectUnreportedChanges ? machineFunctionFingerprint(Function) : 0;
+    if (Instrumentation != nullptr)
+      Instrumentation->before(Name, Function);
+    const Clock::time_point Start = Clock::now();
+    auto PassResult = Pass->run(Function, Target, Analyses);
+    const std::uint64_t Duration = elapsedNanoseconds(Start);
+    if (!PassResult) {
+      Error Failure =
+          prefixedError(PassResult.error(), "pass '" + std::string(Name) + "' failed: ");
+      if (Instrumentation != nullptr)
+        Instrumentation->failure(Name, Function, Failure, Duration);
+      Analyses.clear(Function);
+      Analyses.setInstrumentation(nullptr);
+      return std::unexpected(std::move(Failure));
+    }
+
+    if (PassResult->Changed != !PassResult->Changes.empty()) {
+      Error Failure(ErrorCode::VerificationError,
+                    "pass '" + std::string(Name) +
+                        "' reported inconsistent changed state and modification categories");
+      if (Instrumentation != nullptr)
+        Instrumentation->failure(Name, Function, Failure, Duration);
+      Analyses.clear(Function);
+      Analyses.setInstrumentation(nullptr);
+      return std::unexpected(std::move(Failure));
+    }
+    if (!Contract.DeclaredChanges.contains(PassResult->Changes)) {
+      Error Failure(ErrorCode::VerificationError,
+                    "pass '" + std::string(Name) +
+                        "' reported a modification category absent from its registration");
+      if (Instrumentation != nullptr)
+        Instrumentation->failure(Name, Function, Failure, Duration);
+      Analyses.clear(Function);
+      Analyses.setInstrumentation(nullptr);
+      return std::unexpected(std::move(Failure));
+    }
+
+    bool FingerprintChanged = PassResult->Changed;
+    if (Options.DetectUnreportedChanges) {
+      FingerprintChanged = FingerprintBefore != machineFunctionFingerprint(Function);
+      if (FingerprintChanged && !PassResult->Changed) {
+        Error Failure(ErrorCode::VerificationError,
+                      "pass '" + std::string(Name) +
+                          "' changed MachineIR without reporting a modification");
+        if (Instrumentation != nullptr)
+          Instrumentation->failure(Name, Function, Failure, Duration);
+        Analyses.clear(Function);
+        Analyses.setInstrumentation(nullptr);
+        return std::unexpected(std::move(Failure));
+      }
+    }
+    if (Instrumentation != nullptr)
+      Instrumentation->change(Name, Function, PassResult->Changes, FingerprintChanged);
+
+    auto Transition =
+        Function.properties().applyTransition(Contract.Requires, Contract.Sets, Contract.Clears);
+    if (!Transition) {
+      Error Failure =
+          prefixedError(Transition.error(), "pass '" + std::string(Name) +
+                                                "' produced an invalid property transition: ");
+      if (Instrumentation != nullptr)
+        Instrumentation->failure(Name, Function, Failure, Duration);
+      Analyses.clear(Function);
+      Analyses.setInstrumentation(nullptr);
+      return std::unexpected(std::move(Failure));
+    }
+    Analyses.invalidate(Function, PassResult->Preserved, PassResult->Changes);
+
+    if (Options.VerifyEach) {
+      MachineVerifierOptions VerifyOptions;
+      VerifyOptions.Stage = Contract.VerificationStage;
+      auto Verification = MachineVerifier::verify(Function, Target, VerifyOptions);
+      if (!Verification) {
+        Error Failure = prefixedError(Verification.error(),
+                                      "pass '" + std::string(Name) + "' left invalid MachineIR: ");
+        if (Instrumentation != nullptr)
+          Instrumentation->failure(Name, Function, Failure, Duration);
+        Analyses.clear(Function);
+        Analyses.setInstrumentation(nullptr);
+        return std::unexpected(std::move(Failure));
+      }
+    }
+    if (Instrumentation != nullptr)
+      Instrumentation->after(Name, Function, *PassResult, Duration);
+  }
+  Analyses.setInstrumentation(nullptr);
+  return {};
+}
+
+Expected<void> MachinePassManager::runFunctions(CompilationUnit &Unit,
+                                                const TargetDescription &Target,
+                                                const MachineAnalysisManager &AnalysisPrototype,
+                                                std::size_t ThreadCount,
+                                                MachinePassInstrumentation *Instrumentation) const {
+  if (ThreadCount == 0)
+    return makeUnexpected(ErrorCode::InvalidArgument, "machine pass thread count must be nonzero");
+  auto UnitVerification = verifyCompilationUnit(Unit, Target);
+  if (!UnitVerification)
+    return std::unexpected(UnitVerification.error());
+  const std::size_t FunctionCount = Unit.functionCount();
+  if (FunctionCount == 0)
+    return {};
+  const std::size_t WorkerCount = std::min(ThreadCount, FunctionCount);
+  if (WorkerCount > 1) {
+    for (const std::unique_ptr<MachineFunctionPass> &Pass : Passes) {
+      if (Pass->contract().ThreadSafety != PassThreadSafety::ThreadSafe) {
+        return makeUnexpected(ErrorCode::InvalidArgument,
+                              "parallel machine pipeline contains a pass not marked thread-safe");
+      }
+      auto AnalysisSafety =
+          AnalysisPrototype.validateParallelRequirements(Pass->contract().RequiredAnalyses);
+      if (!AnalysisSafety)
+        return std::unexpected(AnalysisSafety.error());
+    }
+  }
+  std::vector<std::unique_ptr<MachineAnalysisManager>> Managers;
+  Managers.reserve(FunctionCount);
+  for (std::size_t Index = 0; Index < FunctionCount; ++Index) {
+    auto Manager = AnalysisPrototype.forkEmpty();
+    if (!Manager)
+      return std::unexpected(Manager.error());
+    Managers.push_back(std::move(*Manager));
+  }
+
+  std::vector<std::optional<Error>> Failures(FunctionCount);
+  std::vector<MachinePassInstrumentation::BufferedEvents> EventBuffers(FunctionCount);
+  std::atomic<std::size_t> NextFunction = 0;
+  const auto Worker = [&]() {
+    while (true) {
+      const std::size_t Index = NextFunction.fetch_add(1, std::memory_order_relaxed);
+      if (Index >= FunctionCount)
+        return;
+      MachineFunction *Function = Unit.functionAt(Index);
+      if (Function == nullptr) {
+        Failures[Index] = Error(ErrorCode::InternalError,
+                                "compilation unit contains a null function during parallel run");
+        continue;
+      }
+      if (Instrumentation != nullptr)
+        Instrumentation->beginBuffering(EventBuffers[Index], Target);
+      auto Result = run(*Function, Target, *Managers[Index], Instrumentation);
+      if (Instrumentation != nullptr)
+        Instrumentation->endBuffering();
+      if (!Result)
+        Failures[Index] = Result.error();
+    }
+  };
+
+  std::vector<std::thread> Workers;
+  Workers.reserve(WorkerCount);
+  for (std::size_t Index = 0; Index < WorkerCount; ++Index)
+    Workers.emplace_back(Worker);
+  for (std::thread &WorkerThread : Workers)
+    WorkerThread.join();
+
+  for (std::size_t Index = 0; Index < FunctionCount; ++Index) {
+    if (Instrumentation != nullptr)
+      Instrumentation->replayBufferedEvents(EventBuffers[Index]);
+    if (Failures[Index]) {
+      return std::unexpected(
+          prefixedError(*Failures[Index],
+                        "function '" + std::string(Unit.functionAt(Index)->name()) + "' failed: "));
+    }
+  }
+  return {};
+}
+
+Expected<void> CompilationUnitPassManager::addPass(std::unique_ptr<CompilationUnitPass> Pass) {
+  if (!Pass) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "compilation-unit pass manager cannot add a null pass");
+  }
+  const CompilationUnitPassContract &Contract = Pass->contract();
+  if (Contract.Name.empty()) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "compilation-unit pass must have a non-empty name");
+  }
+  if (hasDuplicateAnalysisIDs(Contract.RequiredAnalyses)) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "compilation-unit pass required analyses must be non-null and unique");
+  }
+  auto Parameters = validateParameters(Contract.Parameters);
+  if (!Parameters)
+    return std::unexpected(Parameters.error());
+  Passes.push_back(std::move(Pass));
+  return {};
+}
+
+Expected<void> CompilationUnitPassManager::run(CompilationUnit &Unit,
+                                               const TargetDescription &Target,
+                                               CompilationUnitAnalysisManager &UnitAnalyses,
+                                               MachineAnalysisManager &FunctionAnalyses,
+                                               MachinePassInstrumentation *Instrumentation) const {
+  UnitAnalyses.setInstrumentation(Instrumentation);
+  FunctionAnalyses.setInstrumentation(Instrumentation);
+  for (const std::unique_ptr<CompilationUnitPass> &Pass : Passes) {
+    const CompilationUnitPassContract &Contract = Pass->contract();
+    const std::string_view Name = Contract.Name;
+
+    if (Options.VerifyBefore) {
+      auto Verification = verifyCompilationUnit(Unit, Target);
+      if (!Verification) {
+        Error Failure =
+            prefixedError(Verification.error(), "compilation-unit pass '" + std::string(Name) +
+                                                    "' received invalid MachineIR: ");
+        if (Instrumentation != nullptr)
+          Instrumentation->unitFailure(Name, Unit, Failure);
+        UnitAnalyses.setInstrumentation(nullptr);
+        FunctionAnalyses.setInstrumentation(nullptr);
+        return std::unexpected(std::move(Failure));
+      }
+    }
+
+    for (const AnalysisID Required : Contract.RequiredAnalyses) {
+      auto Result = UnitAnalyses.getResultImpl(Required, Unit, Target);
+      if (!Result) {
+        Error Failure =
+            prefixedError(Result.error(), "compilation-unit pass '" + std::string(Name) +
+                                              "' could not materialize a required analysis: ");
+        if (Instrumentation != nullptr)
+          Instrumentation->unitFailure(Name, Unit, Failure);
+        UnitAnalyses.setInstrumentation(nullptr);
+        FunctionAnalyses.setInstrumentation(nullptr);
+        return std::unexpected(std::move(Failure));
+      }
+    }
+
+    if (Instrumentation != nullptr)
+      Instrumentation->beforeUnit(Name, Unit);
+    const Clock::time_point Start = Clock::now();
+    auto Result = Pass->run(Unit, Target, UnitAnalyses, FunctionAnalyses);
+    const std::uint64_t Duration = elapsedNanoseconds(Start);
+    if (!Result) {
+      Error Failure = prefixedError(Result.error(),
+                                    "compilation-unit pass '" + std::string(Name) + "' failed: ");
+      if (Instrumentation != nullptr)
+        Instrumentation->unitFailure(Name, Unit, Failure, Duration);
+      UnitAnalyses.clearAll();
+      FunctionAnalyses.clearAll();
+      UnitAnalyses.setInstrumentation(nullptr);
+      FunctionAnalyses.setInstrumentation(nullptr);
+      return std::unexpected(std::move(Failure));
+    }
+    if (Result->Changed != !Result->Changes.empty() ||
+        !Contract.DeclaredChanges.contains(Result->Changes)) {
+      Error Failure(ErrorCode::VerificationError,
+                    "compilation-unit pass '" + std::string(Name) +
+                        "' reported inconsistent or undeclared modifications");
+      if (Instrumentation != nullptr)
+        Instrumentation->unitFailure(Name, Unit, Failure, Duration);
+      UnitAnalyses.clearAll();
+      FunctionAnalyses.clearAll();
+      UnitAnalyses.setInstrumentation(nullptr);
+      FunctionAnalyses.setInstrumentation(nullptr);
+      return std::unexpected(std::move(Failure));
+    }
+
+    UnitAnalyses.invalidate(Unit, Result->PreservedUnitAnalyses, Result->Changes);
+    for (std::size_t Index = 0; Index < Unit.functionCount(); ++Index) {
+      MachineFunction *Function = Unit.functionAt(Index);
+      if (Function != nullptr) {
+        FunctionAnalyses.invalidate(*Function, Result->PreservedFunctionAnalyses, Result->Changes);
+      }
+    }
+    if (Options.VerifyEach) {
+      auto Verification = verifyCompilationUnit(Unit, Target);
+      if (!Verification) {
+        Error Failure =
+            prefixedError(Verification.error(), "compilation-unit pass '" + std::string(Name) +
+                                                    "' left invalid MachineIR: ");
+        if (Instrumentation != nullptr)
+          Instrumentation->unitFailure(Name, Unit, Failure, Duration);
+        UnitAnalyses.clearAll();
+        FunctionAnalyses.clearAll();
+        UnitAnalyses.setInstrumentation(nullptr);
+        FunctionAnalyses.setInstrumentation(nullptr);
+        return std::unexpected(std::move(Failure));
+      }
+    }
+    if (Instrumentation != nullptr)
+      Instrumentation->afterUnit(Name, Unit, *Result, Duration);
+  }
+  UnitAnalyses.setInstrumentation(nullptr);
+  FunctionAnalyses.setInstrumentation(nullptr);
+  return {};
+}
+
+} // namespace rcc
diff --git a/backend/lib/CodeGen/TargetCallLowering.cpp b/backend/lib/CodeGen/TargetCallLowering.cpp
new file mode 100644
index 0000000..d6a14b7
--- /dev/null
+++ b/backend/lib/CodeGen/TargetCallLowering.cpp
@@ -0,0 +1,353 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "rcc/CodeGen/TargetCallLowering.h"
+
+#include "rcc/CodeGen/MachineIRBuilder.h"
+
+#include <algorithm>
+#include <cstddef>
+#include <cstdint>
+#include <limits>
+#include <string>
+#include <unordered_set>
+#include <utility>
+#include <vector>
+
+namespace rcc {
+namespace {
+
+[[nodiscard]] bool isKnownExtension(ABIExtensionKind Extension) noexcept {
+  return Extension < ABIExtensionKind::Count;
+}
+
+[[nodiscard]] bool isKnownLocationKind(CCLocationKind Kind) noexcept {
+  return Kind <= CCLocationKind::Custom;
+}
+
+[[nodiscard]] bool isKnownTailCallKind(TailCallKind Kind) noexcept {
+  return Kind <= TailCallKind::MustTail;
+}
+
+[[nodiscard]] bool addOverflows(std::uint64_t Left, std::uint64_t Right) noexcept {
+  return Left > std::numeric_limits<std::uint64_t>::max() - Right;
+}
+
+[[nodiscard]] Expected<void> verifyAssignment(const CCAssignment &Assignment,
+                                              bool AllowNoRegister) {
+  if (Assignment.OriginalValue.isNoRegister() && !AllowNoRegister) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "call-lowering assignment requires a machine register value");
+  }
+  if (!Assignment.ValueType.isValid() || !Assignment.LocationType.isValid() ||
+      !Assignment.ValueType.isScalarValue() || !Assignment.LocationType.isScalarValue()) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "call-lowering assignments require scalar value and location LLTs");
+  }
+  if (Assignment.FragmentCount == 0 || Assignment.FragmentIndex >= Assignment.FragmentCount) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "call-lowering assignment has invalid fragment coordinates");
+  }
+  if (Assignment.LocationSizeBytes == 0 || Assignment.StackSlotSizeBytes == 0 ||
+      Assignment.LocationSizeBytes > Assignment.StackSlotSizeBytes ||
+      !isKnownExtension(Assignment.Extension) || !isKnownLocationKind(Assignment.LocationKind)) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "call-lowering assignment has invalid size or extension metadata");
+  }
+
+  const bool HasRegister = Assignment.LocationRegister.has_value();
+  const bool HasStack = Assignment.StackOffsetBytes.has_value();
+  if (HasRegister && !Assignment.LocationRegister->isValid()) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "call-lowering assignment names an invalid physical register");
+  }
+  if (HasStack && *Assignment.StackOffsetBytes % Assignment.LocationAlignment.bytes() != 0) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "stack assignment offset violates its location alignment");
+  }
+  switch (Assignment.LocationKind) {
+  case CCLocationKind::Register:
+    if (!HasRegister || HasStack) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "register assignment must name exactly one physical register");
+    }
+    break;
+  case CCLocationKind::Stack:
+    if (HasRegister || !HasStack) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "stack assignment must name exactly one stack offset");
+    }
+    break;
+  case CCLocationKind::Indirect:
+    if (HasRegister == HasStack || !Assignment.CustomFlags.has(CCAssignmentFlag::Indirect)) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "indirect assignment must have one transport location and its flag");
+    }
+    break;
+  case CCLocationKind::Custom:
+    if (HasRegister && HasStack) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "custom assignment cannot use register and stack simultaneously");
+    }
+    break;
+  }
+  return {};
+}
+
+[[nodiscard]] Expected<void> verifyAssignments(std::span<const CCAssignment> Assignments,
+                                               bool AllowNoRegister,
+                                               const StackArgumentArea &StackArea) {
+  std::unordered_set<PhysicalRegister> Registers;
+  std::vector<std::pair<std::uint64_t, std::uint64_t>> StackRanges;
+  StackRanges.reserve(Assignments.size());
+  for (const CCAssignment &Assignment : Assignments) {
+    auto Verification = verifyAssignment(Assignment, AllowNoRegister);
+    if (!Verification)
+      return std::unexpected(Verification.error());
+    if (Assignment.LocationRegister && !Registers.insert(*Assignment.LocationRegister).second) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "call-lowering assignments reuse a physical location register");
+    }
+    if (!Assignment.StackOffsetBytes)
+      continue;
+    if (addOverflows(*Assignment.StackOffsetBytes, Assignment.StackSlotSizeBytes)) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "call-lowering stack assignment range overflows uint64");
+    }
+    const std::uint64_t End = *Assignment.StackOffsetBytes + Assignment.StackSlotSizeBytes;
+    if (End > StackArea.SizeBytes) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "call-lowering stack assignment exceeds its argument area");
+    }
+    StackRanges.emplace_back(*Assignment.StackOffsetBytes, End);
+  }
+
+  std::ranges::sort(StackRanges);
+  for (std::size_t Index = 1; Index < StackRanges.size(); ++Index) {
+    if (StackRanges[Index].first < StackRanges[Index - 1].second) {
+      return makeUnexpected(ErrorCode::InvalidArgument, "call-lowering stack assignments overlap");
+    }
+  }
+  return {};
+}
+
+[[nodiscard]] Expected<void> verifyVarArgs(const VarArgLoweringState &State) {
+  if (!State.IsVariadic) {
+    if (State.FixedArgumentCount != 0 || State.FirstUnallocatedIntegerRegister != 0 ||
+        State.OverflowAreaOffsetBytes != 0 || State.RegisterSaveAreaOffsetBytes != 0 ||
+        State.RegisterSaveAreaSizeBytes != 0 || State.RegisterSavePaddingBytes != 0 ||
+        !State.RegistersToSave.empty()) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "non-variadic plan contains variadic lowering state");
+    }
+    return {};
+  }
+
+  if (State.RegisterSaveAreaSizeBytes == 0 && !State.RegistersToSave.empty()) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "variadic register saves require a nonempty save area");
+  }
+  if (State.RegisterSaveAreaSizeBytes % 8 != 0 || State.RegisterSavePaddingBytes % 8 != 0) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "variadic register-save size and padding must be XLEN aligned");
+  }
+  std::unordered_set<PhysicalRegister> SavedRegisters;
+  std::unordered_set<std::uint64_t> SavedOffsets;
+  for (const VarArgRegisterSave Save : State.RegistersToSave) {
+    if (!Save.Reg.isValid() || !SavedRegisters.insert(Save.Reg).second ||
+        Save.OffsetBytes % 8 != 0 || !SavedOffsets.insert(Save.OffsetBytes).second ||
+        addOverflows(Save.OffsetBytes, std::uint64_t{8}) ||
+        Save.OffsetBytes + 8 > State.RegisterSaveAreaSizeBytes) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "variadic register-save entry is invalid or outside its area");
+    }
+  }
+  return {};
+}
+
+} // namespace
+
+ABIValueFlags::ABIValueFlags(std::initializer_list<ABIValueFlag> Flags) noexcept {
+  for (const ABIValueFlag Flag : Flags)
+    set(Flag);
+}
+
+CCAssignmentFlags::CCAssignmentFlags(std::initializer_list<CCAssignmentFlag> Flags) noexcept {
+  for (const CCAssignmentFlag Flag : Flags)
+    set(Flag);
+}
+
+Expected<MachineCallTarget> MachineCallTarget::globalSymbol(std::string Name,
+                                                            std::uint32_t TargetFlags) {
+  if (Name.empty())
+    return makeUnexpected(ErrorCode::InvalidArgument, "global call target name cannot be empty");
+  return MachineCallTarget(MachineCallTargetKind::GlobalSymbol, std::move(Name), TargetFlags);
+}
+
+Expected<MachineCallTarget> MachineCallTarget::externalSymbol(std::string Name,
+                                                              std::uint32_t TargetFlags) {
+  if (Name.empty())
+    return makeUnexpected(ErrorCode::InvalidArgument, "external call target name cannot be empty");
+  return MachineCallTarget(MachineCallTargetKind::ExternalSymbol, std::move(Name), TargetFlags);
+}
+
+Expected<MachineCallTarget> MachineCallTarget::indirect(Register Callee,
+                                                        std::uint32_t TargetFlags) {
+  if (Callee.isNoRegister()) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "indirect call target requires a machine register");
+  }
+  return MachineCallTarget(MachineCallTargetKind::IndirectRegister, Callee, TargetFlags);
+}
+
+std::string_view MachineCallTarget::symbolName() const noexcept {
+  const auto *Name = std::get_if<std::string>(&Value);
+  return Name == nullptr ? std::string_view{} : std::string_view(*Name);
+}
+
+Register MachineCallTarget::indirectRegister() const noexcept {
+  const auto *Reg = std::get_if<Register>(&Value);
+  return Reg == nullptr ? Register{} : *Reg;
+}
+
+Expected<CallLoweringPlan> CallLoweringPlan::create(CallLoweringPlanDesc Description) {
+  if (Description.Target.empty() || Description.Convention.value() == 0) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "call-lowering plan requires target and calling-convention identities");
+  }
+  if (Description.Kind > CallLoweringPlanKind::Return ||
+      !isKnownTailCallKind(Description.TailDecision)) {
+    return makeUnexpected(ErrorCode::InvalidArgument, "call-lowering plan kind is invalid");
+  }
+  if (Description.StackArguments.ShadowSpaceBytes > Description.StackArguments.SizeBytes ||
+      Description.StackArguments.SizeBytes % Description.StackArguments.Align.bytes() != 0) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "call-lowering stack argument area is malformed");
+  }
+  if (Description.CallFrame.SizeBytes % Description.CallFrame.Align.bytes() != 0 ||
+      Description.CallFrame.EmitSetup != Description.CallFrame.EmitDestroy) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "call-lowering call-frame requirements are inconsistent");
+  }
+
+  auto ArgumentVerification =
+      verifyAssignments(Description.ArgumentAssignments, false, Description.StackArguments);
+  if (!ArgumentVerification)
+    return std::unexpected(ArgumentVerification.error());
+  const bool AllowNoReturnRegister = Description.Kind == CallLoweringPlanKind::Call &&
+                                     Description.TailDecision != TailCallKind::NotTail;
+  auto ReturnVerification = verifyAssignments(Description.ReturnAssignments, AllowNoReturnRegister,
+                                              StackArgumentArea{0, 0, Alignment{}});
+  if (!ReturnVerification)
+    return std::unexpected(ReturnVerification.error());
+  auto VarArgVerification = verifyVarArgs(Description.VarArgs);
+  if (!VarArgVerification)
+    return std::unexpected(VarArgVerification.error());
+
+  switch (Description.Kind) {
+  case CallLoweringPlanKind::FormalArguments:
+    if (!Description.ReturnAssignments.empty() || Description.Callee || Description.PreservedMask ||
+        Description.CallSiteID != 0 || Description.TailDecision != TailCallKind::NotTail ||
+        Description.CallFrame.EmitSetup || Description.CallFrame.ReusesIncomingArea ||
+        !Description.ByValCopies.empty() || !Description.TailRejectionReason.empty()) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "formal-argument plan contains call or return state");
+    }
+    break;
+  case CallLoweringPlanKind::Return:
+    if (!Description.ArgumentAssignments.empty() || Description.Callee ||
+        Description.PreservedMask || Description.CallSiteID != 0 ||
+        Description.TailDecision != TailCallKind::NotTail || Description.CallFrame.EmitSetup ||
+        Description.CallFrame.ReusesIncomingArea || !Description.ByValCopies.empty() ||
+        Description.VarArgs.IsVariadic || !Description.TailRejectionReason.empty()) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "return plan contains formal-argument or call state");
+    }
+    break;
+  case CallLoweringPlanKind::Call:
+    if (!Description.Callee || !Description.Callee->isValid() || !Description.PreservedMask ||
+        Description.CallSiteID == 0) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "call plan requires a callee, call-site ID, and preserved mask");
+    }
+    if (Description.TailDecision == TailCallKind::NotTail) {
+      if (!Description.CallFrame.EmitSetup || Description.CallFrame.ReusesIncomingArea) {
+        return makeUnexpected(ErrorCode::InvalidArgument,
+                              "ordinary call plan requires a private call frame");
+      }
+    } else if (Description.CallFrame.EmitSetup || !Description.CallFrame.ReusesIncomingArea ||
+               !Description.TailRejectionReason.empty()) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "tail-call plan must reuse the caller's incoming argument area");
+    }
+    if (Description.CallFrame.SizeBytes < Description.StackArguments.SizeBytes) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "call frame does not contain the stack-argument area");
+    }
+    break;
+  }
+
+  std::unordered_set<std::size_t> ByValAssignments;
+  std::vector<std::pair<std::uint64_t, std::uint64_t>> ByValRanges;
+  for (const ByValCopyAssignment &Copy : Description.ByValCopies) {
+    if (Copy.ArgumentAssignmentIndex >= Description.ArgumentAssignments.size() ||
+        !ByValAssignments.insert(Copy.ArgumentAssignmentIndex).second ||
+        Copy.Source.isNoRegister() || !Copy.PointerType.isPointer() || Copy.SizeBytes == 0 ||
+        Copy.StackOffsetBytes % Copy.Align.bytes() != 0 ||
+        Copy.StackOffsetBytes < Description.StackArguments.SizeBytes ||
+        !Description.ArgumentAssignments[Copy.ArgumentAssignmentIndex].CustomFlags.has(
+            CCAssignmentFlag::ByVal) ||
+        addOverflows(Copy.StackOffsetBytes, Copy.SizeBytes) ||
+        Copy.StackOffsetBytes + Copy.SizeBytes > Description.CallFrame.SizeBytes) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "call-lowering byval copy is malformed or outside the call frame");
+    }
+    ByValRanges.emplace_back(Copy.StackOffsetBytes, Copy.StackOffsetBytes + Copy.SizeBytes);
+  }
+  std::ranges::sort(ByValRanges);
+  for (std::size_t Index = 1; Index < ByValRanges.size(); ++Index) {
+    if (ByValRanges[Index].first < ByValRanges[Index - 1].second) {
+      return makeUnexpected(ErrorCode::InvalidArgument, "call-lowering byval copy ranges overlap");
+    }
+  }
+
+  return CallLoweringPlan(std::move(Description));
+}
+
+Expected<void>
+TargetCallLowering::lowerFormalArguments(MachineIRBuilder &Builder,
+                                         const FormalArgumentRequest &Request) const {
+  auto Plan = planFormalArguments(Request);
+  if (!Plan)
+    return std::unexpected(Plan.error());
+  if (Plan->kind() != CallLoweringPlanKind::FormalArguments) {
+    return makeUnexpected(ErrorCode::InternalError,
+                          "target returned the wrong call-lowering plan kind for formal arguments");
+  }
+  return emitPlan(Builder, *Plan);
+}
+
+Expected<void> TargetCallLowering::lowerCall(MachineIRBuilder &Builder,
+                                             const CallLoweringRequest &Request) const {
+  auto Plan = planCall(Request);
+  if (!Plan)
+    return std::unexpected(Plan.error());
+  if (Plan->kind() != CallLoweringPlanKind::Call) {
+    return makeUnexpected(ErrorCode::InternalError,
+                          "target returned the wrong call-lowering plan kind for a call");
+  }
+  return emitPlan(Builder, *Plan);
+}
+
+Expected<void> TargetCallLowering::lowerReturn(MachineIRBuilder &Builder,
+                                               const ReturnLoweringRequest &Request) const {
+  auto Plan = planReturn(Request);
+  if (!Plan)
+    return std::unexpected(Plan.error());
+  if (Plan->kind() != CallLoweringPlanKind::Return) {
+    return makeUnexpected(ErrorCode::InternalError,
+                          "target returned the wrong call-lowering plan kind for a return");
+  }
+  return emitPlan(Builder, *Plan);
+}
+
+} // namespace rcc
diff --git a/backend/lib/Target/RISCV/CMakeLists.txt b/backend/lib/Target/RISCV/CMakeLists.txt
index a77494a..ff3f334 100644
--- a/backend/lib/Target/RISCV/CMakeLists.txt
+++ b/backend/lib/Target/RISCV/CMakeLists.txt
@@ -47,6 +47,7 @@ set_source_files_properties(
 
 add_library(
   RCCBackendRISCV
+  RISCVCallLowering.cpp
   RISCVTarget.cpp
   "${RCCBackendRISCVGeneratedRegisterHeader}"
   "${RCCBackendRISCVGeneratedInstructionHeader}"
@@ -89,9 +90,12 @@ install(
 )
 
 rcc_backend_register_format_files(
+  "${CMAKE_CURRENT_SOURCE_DIR}/RISCVCallLowering.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/RISCVTarget.cpp"
+  "${RCC_BACKEND_SOURCE_DIR}/include/rcc/Target/RISCV/RISCVCallLowering.h"
   "${RCC_BACKEND_SOURCE_DIR}/include/rcc/Target/RISCV/RISCVTarget.h"
 )
 rcc_backend_register_tidy_files(
+  "${CMAKE_CURRENT_SOURCE_DIR}/RISCVCallLowering.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/RISCVTarget.cpp"
 )
diff --git a/backend/lib/Target/RISCV/RISCVCallLowering.cpp b/backend/lib/Target/RISCV/RISCVCallLowering.cpp
new file mode 100644
index 0000000..13cd348
--- /dev/null
+++ b/backend/lib/Target/RISCV/RISCVCallLowering.cpp
@@ -0,0 +1,1473 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "rcc/Target/RISCV/RISCVCallLowering.h"
+
+#include "rcc/CodeGen/MachineBasicBlock.h"
+#include "rcc/CodeGen/MachineFrameInfo.h"
+#include "rcc/CodeGen/MachineFunction.h"
+#include "rcc/CodeGen/MachineIRBuilder.h"
+#include "rcc/CodeGen/MachineInstr.h"
+#include "rcc/CodeGen/MachineMemOperand.h"
+#include "rcc/CodeGen/MachineRegisterInfo.h"
+#include "rcc/CodeGen/TargetDescription.h"
+#include "rcc/Target/RISCV/RISCVTarget.h"
+
+#include <algorithm>
+#include <array>
+#include <cstddef>
+#include <cstdint>
+#include <limits>
+#include <optional>
+#include <span>
+#include <string>
+#include <unordered_map>
+#include <unordered_set>
+#include <utility>
+#include <vector>
+
+namespace rcc::riscv {
+namespace {
+
+constexpr std::string_view PlanTarget = "riscv64-unknown-linux-gnu:lp64d";
+constexpr std::uint64_t XLenBytes = 8;
+constexpr std::uint64_t LP64DStackAlignmentBytes = 16;
+constexpr std::uint32_t AllowedDirectCallFlags =
+    static_cast<std::uint32_t>(CallTargetFlag::DirectCall);
+
+[[nodiscard]] Opcode targetOpcode(InstructionOpcode Value) noexcept {
+  return Opcode::fromValue(static_cast<std::uint32_t>(Value));
+}
+
+[[nodiscard]] std::uint64_t stackObjectFlag(CallStackObjectFlag Flag) noexcept {
+  return static_cast<std::uint64_t>(Flag);
+}
+
+[[nodiscard]] Expected<Alignment> alignment(std::uint64_t Bytes) {
+  return Alignment::create(Bytes);
+}
+
+[[nodiscard]] Expected<std::uint64_t> alignTo(std::uint64_t Value, std::uint64_t AlignmentBytes) {
+  const std::uint64_t Remainder = Value % AlignmentBytes;
+  if (Remainder == 0)
+    return Value;
+  const std::uint64_t Increment = AlignmentBytes - Remainder;
+  if (Value > std::numeric_limits<std::uint64_t>::max() - Increment) {
+    return makeUnexpected(ErrorCode::Unsupported, "LP64D stack-area size overflows uint64");
+  }
+  return Value + Increment;
+}
+
+[[nodiscard]] std::uint64_t valueSizeBytes(LLT Type) noexcept {
+  return (static_cast<std::uint64_t>(Type.scalarBitWidth()) + 7U) / 8U;
+}
+
+[[nodiscard]] bool isSupportedFloat(LLT Type) noexcept {
+  if (!Type.isFloat())
+    return false;
+  const auto Semantics = Type.floatSemantics();
+  return Semantics &&
+         (*Semantics == FloatSemantics::IEEESingle || *Semantics == FloatSemantics::IEEEDouble);
+}
+
+[[nodiscard]] bool requiresIntegerTransport(const ABIValue &Value) noexcept {
+  return !isSupportedFloat(Value.Type) || Value.Flags.has(ABIValueFlag::ByVal) ||
+         Value.Flags.has(ABIValueFlag::StructReturn) || Value.Flags.has(ABIValueFlag::Indirect);
+}
+
+[[nodiscard]] Expected<void> verifyABIValue(const ABIValue &Value, bool RequireRegister) {
+  if (RequireRegister && Value.Value.isNoRegister()) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "LP64D ABI value requires a source or destination register");
+  }
+  if (!Value.Type.isValid() || !Value.Type.isScalarValue() || Value.Type.isAnyScalar() ||
+      Value.Type.scalarBitWidth() > 64) {
+    return makeUnexpected(
+        ErrorCode::Unsupported,
+        "LP64D accepts explicitly classified integer, pointer, f32, and f64 scalar fragments");
+  }
+  if (Value.Type.isFloat() && !isSupportedFloat(Value.Type)) {
+    return makeUnexpected(ErrorCode::Unsupported,
+                          "RV64GC LP64D only supports f32 and f64 ABI fragments");
+  }
+  if (Value.Type.isPointer() && Value.Type.scalarBitWidth() != 64) {
+    return makeUnexpected(ErrorCode::Unsupported, "RV64GC LP64D requires 64-bit machine pointers");
+  }
+  if (Value.Type.isInteger() && Value.Type.scalarBitWidth() < 64) {
+    if (Value.Extension == ABIExtensionKind::None) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "narrow LP64D integer fragments require an explicit extension kind");
+    }
+  } else if (Value.Extension != ABIExtensionKind::None) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "only narrow integer ABI fragments may carry an extension kind");
+  }
+  if (Value.Extension >= ABIExtensionKind::Count || Value.FragmentCount == 0 ||
+      Value.FragmentIndex >= Value.FragmentCount || Value.FragmentCount > 2) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "LP64D ABI fragment coordinates or extension are invalid");
+  }
+
+  const bool IsByVal = Value.Flags.has(ABIValueFlag::ByVal);
+  const bool IsSRet = Value.Flags.has(ABIValueFlag::StructReturn);
+  const bool IsIndirect = Value.Flags.has(ABIValueFlag::Indirect);
+  const unsigned SpecialFlagCount = static_cast<unsigned>(IsByVal) + static_cast<unsigned>(IsSRet) +
+                                    static_cast<unsigned>(IsIndirect);
+  if (SpecialFlagCount > 1) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "byval, sret, and indirect ABI flags are mutually exclusive");
+  }
+  if ((IsByVal || IsSRet || IsIndirect) &&
+      (!Value.Type.isPointer() || Value.FragmentCount != 1 || Value.FragmentIndex != 0 ||
+       Value.FragmentOffsetBytes != 0)) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "byval, sret, and indirect values require one explicit pointer fragment");
+  }
+  if (IsByVal) {
+    if (Value.ByValSizeBytes == 0) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "byval arguments require a nonzero copy size");
+    }
+  } else if (Value.ByValSizeBytes != 0) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "non-byval values cannot carry a byval copy size");
+  }
+  return {};
+}
+
+[[nodiscard]] Expected<std::size_t> verifyValueSequence(std::span<const ABIValue> Values,
+                                                        bool RequireRegisters) {
+  std::size_t ExpectedOriginal = 0;
+  std::size_t Index = 0;
+  while (Index < Values.size()) {
+    const ABIValue &First = Values[Index];
+    auto ValueVerification = verifyABIValue(First, RequireRegisters);
+    if (!ValueVerification)
+      return std::unexpected(ValueVerification.error());
+    if (First.OriginalValue != ExpectedOriginal || First.FragmentIndex != 0 ||
+        Index + First.FragmentCount > Values.size()) {
+      return makeUnexpected(
+          ErrorCode::InvalidArgument,
+          "LP64D ABI values must form contiguous, zero-based original-value groups");
+    }
+
+    std::uint64_t PreviousEnd = 0;
+    for (std::size_t Fragment = 0; Fragment < First.FragmentCount; ++Fragment) {
+      const ABIValue &Value = Values[Index + Fragment];
+      auto FragmentVerification = verifyABIValue(Value, RequireRegisters);
+      if (!FragmentVerification)
+        return std::unexpected(FragmentVerification.error());
+      if (Value.OriginalValue != First.OriginalValue || Value.FragmentIndex != Fragment ||
+          Value.FragmentCount != First.FragmentCount ||
+          Value.OriginalAlignment != First.OriginalAlignment || Value.Flags != First.Flags ||
+          Value.ByValSizeBytes != First.ByValSizeBytes ||
+          Value.ByValAlignment != First.ByValAlignment || Value.FragmentOffsetBytes < PreviousEnd) {
+        return makeUnexpected(ErrorCode::InvalidArgument,
+                              "LP64D fragments of one value have inconsistent metadata");
+      }
+      PreviousEnd =
+          static_cast<std::uint64_t>(Value.FragmentOffsetBytes) + valueSizeBytes(Value.Type);
+    }
+    Index += First.FragmentCount;
+    ++ExpectedOriginal;
+  }
+  return ExpectedOriginal;
+}
+
+[[nodiscard]] CCAssignmentFlags assignmentFlags(const ABIValue &Value, bool IsVariadic,
+                                                bool IsBitcast) {
+  CCAssignmentFlags Result;
+  if (IsVariadic)
+    Result.set(CCAssignmentFlag::Variadic);
+  if (Value.Flags.has(ABIValueFlag::ByVal))
+    Result.set(CCAssignmentFlag::ByVal);
+  if (Value.Flags.has(ABIValueFlag::StructReturn))
+    Result.set(CCAssignmentFlag::StructReturn);
+  if (Value.Flags.has(ABIValueFlag::Indirect))
+    Result.set(CCAssignmentFlag::Indirect);
+  if (Value.Flags.has(ABIValueFlag::InRegister))
+    Result.set(CCAssignmentFlag::InRegister);
+  if (IsBitcast)
+    Result.set(CCAssignmentFlag::Bitcast);
+  return Result;
+}
+
+[[nodiscard]] CCLocationKind locationKind(const ABIValue &Value, bool IsRegister) noexcept {
+  if (Value.Flags.has(ABIValueFlag::Indirect))
+    return CCLocationKind::Indirect;
+  return IsRegister ? CCLocationKind::Register : CCLocationKind::Stack;
+}
+
+struct ArgumentAssignmentResult final {
+  std::vector<CCAssignment> Assignments;
+  StackArgumentArea StackArea;
+  std::size_t FirstUnallocatedGPR = 0;
+};
+
+struct AssignmentState final {
+  std::size_t GPR = 0;
+  std::size_t FPR = 0;
+  std::uint64_t StackOffset = 0;
+  bool VariadicStackOnly = false;
+};
+
+[[nodiscard]] Expected<CCAssignment> registerAssignment(const ABIValue &Value,
+                                                        std::size_t ValueIndex,
+                                                        PhysicalRegister Location, LLT LocationType,
+                                                        bool IsVariadic, bool IsBitcast) {
+  auto Align =
+      alignment(std::min<std::uint64_t>(Value.OriginalAlignment.bytes(), LP64DStackAlignmentBytes));
+  if (!Align)
+    return std::unexpected(Align.error());
+  return CCAssignment{
+      .ValueIndex = ValueIndex,
+      .OriginalValue = Value.Value,
+      .OriginalValueIndex = Value.OriginalValue,
+      .FragmentIndex = Value.FragmentIndex,
+      .FragmentCount = Value.FragmentCount,
+      .ValueType = Value.Type,
+      .LocationType = LocationType,
+      .LocationKind = locationKind(Value, true),
+      .LocationRegister = Location,
+      .StackOffsetBytes = std::nullopt,
+      .LocationSizeBytes = valueSizeBytes(LocationType),
+      .StackSlotSizeBytes = XLenBytes,
+      .LocationAlignment = *Align,
+      .Extension = Value.Extension,
+      .CustomFlags = assignmentFlags(Value, IsVariadic, IsBitcast),
+  };
+}
+
+[[nodiscard]] Expected<CCAssignment> stackAssignment(const ABIValue &Value, std::size_t ValueIndex,
+                                                     std::uint64_t StackOffset, LLT LocationType,
+                                                     bool IsVariadic,
+                                                     std::uint64_t StackAlignment) {
+  auto Align = alignment(StackAlignment);
+  if (!Align)
+    return std::unexpected(Align.error());
+  return CCAssignment{
+      .ValueIndex = ValueIndex,
+      .OriginalValue = Value.Value,
+      .OriginalValueIndex = Value.OriginalValue,
+      .FragmentIndex = Value.FragmentIndex,
+      .FragmentCount = Value.FragmentCount,
+      .ValueType = Value.Type,
+      .LocationType = LocationType,
+      .LocationKind = locationKind(Value, false),
+      .LocationRegister = std::nullopt,
+      .StackOffsetBytes = StackOffset,
+      .LocationSizeBytes = valueSizeBytes(LocationType),
+      .StackSlotSizeBytes = XLenBytes,
+      .LocationAlignment = *Align,
+      .Extension = Value.Extension,
+      .CustomFlags = assignmentFlags(Value, IsVariadic, false),
+  };
+}
+
+[[nodiscard]] Expected<ArgumentAssignmentResult>
+assignArguments(std::span<const ABIValue> Values, std::size_t FixedArgumentCount, bool IsVariadic,
+                const CallingConventionInfo &Convention) {
+  auto I64 = LLT::makeInteger(64);
+  auto StackAlign = alignment(Convention.StackArgumentAlignmentBytes);
+  if (!I64 || !StackAlign)
+    return makeUnexpected(ErrorCode::InternalError, "LP64D primitive type facts are invalid");
+
+  ArgumentAssignmentResult Result;
+  AssignmentState State;
+  State.StackOffset = Convention.ShadowSpaceBytes;
+  Result.Assignments.reserve(Values.size());
+
+  std::size_t Index = 0;
+  while (Index < Values.size()) {
+    const ABIValue &First = Values[Index];
+    const std::size_t GroupSize = First.FragmentCount;
+    const bool VariadicArgument = IsVariadic && First.OriginalValue >= FixedArgumentCount;
+    bool HasPreferredFloat = false;
+    std::size_t RequiredGPRs = 0;
+    std::size_t RequiredFPRs = 0;
+    for (std::size_t Fragment = 0; Fragment < GroupSize; ++Fragment) {
+      const ABIValue &Value = Values[Index + Fragment];
+      if (!VariadicArgument && !requiresIntegerTransport(Value)) {
+        HasPreferredFloat = true;
+        ++RequiredFPRs;
+      } else {
+        ++RequiredGPRs;
+      }
+    }
+
+    const bool CanUsePreferredAggregate =
+        HasPreferredFloat &&
+        State.GPR + RequiredGPRs <= Convention.IntegerArgumentRegisters.size() &&
+        State.FPR + RequiredFPRs <= Convention.FloatingArgumentRegisters.size();
+    if (CanUsePreferredAggregate) {
+      for (std::size_t Fragment = 0; Fragment < GroupSize; ++Fragment) {
+        const ABIValue &Value = Values[Index + Fragment];
+        Expected<CCAssignment> Assignment =
+            requiresIntegerTransport(Value)
+                ? registerAssignment(Value, Index + Fragment,
+                                     Convention.IntegerArgumentRegisters[State.GPR++], *I64, false,
+                                     false)
+                : registerAssignment(Value, Index + Fragment,
+                                     Convention.FloatingArgumentRegisters[State.FPR++], Value.Type,
+                                     false, false);
+        if (!Assignment)
+          return std::unexpected(Assignment.error());
+        Result.Assignments.push_back(*Assignment);
+      }
+      Index += GroupSize;
+      continue;
+    }
+
+    const bool RequiresAlignedPair =
+        VariadicArgument && GroupSize == 2 && First.OriginalAlignment.bytes() >= 16;
+    if (RequiresAlignedPair && State.GPR % 2 != 0 &&
+        State.GPR < Convention.IntegerArgumentRegisters.size()) {
+      ++State.GPR;
+    }
+    bool ForceEntireGroupToStack = State.VariadicStackOnly;
+    if (RequiresAlignedPair && State.GPR + GroupSize > Convention.IntegerArgumentRegisters.size()) {
+      ForceEntireGroupToStack = true;
+      State.GPR = Convention.IntegerArgumentRegisters.size();
+    }
+
+    bool FirstStackFragment = true;
+    for (std::size_t Fragment = 0; Fragment < GroupSize; ++Fragment) {
+      const ABIValue &Value = Values[Index + Fragment];
+      const bool HasGPR =
+          !ForceEntireGroupToStack && State.GPR < Convention.IntegerArgumentRegisters.size();
+      if (HasGPR) {
+        const bool Bitcast = isSupportedFloat(Value.Type);
+        auto Assignment = registerAssignment(Value, Index + Fragment,
+                                             Convention.IntegerArgumentRegisters[State.GPR++], *I64,
+                                             VariadicArgument, Bitcast);
+        if (!Assignment)
+          return std::unexpected(Assignment.error());
+        Result.Assignments.push_back(*Assignment);
+        continue;
+      }
+
+      if (Value.Flags.has(ABIValueFlag::InRegister)) {
+        return makeUnexpected(ErrorCode::Unsupported,
+                              "LP64D inreg argument cannot be assigned to the stack");
+      }
+      std::uint64_t RequiredAlignment = XLenBytes;
+      if (FirstStackFragment && ForceEntireGroupToStack) {
+        RequiredAlignment = std::min<std::uint64_t>(
+            std::max<std::uint64_t>(XLenBytes, First.OriginalAlignment.bytes()),
+            LP64DStackAlignmentBytes);
+      }
+      auto AlignedOffset = alignTo(State.StackOffset, RequiredAlignment);
+      if (!AlignedOffset)
+        return std::unexpected(AlignedOffset.error());
+      State.StackOffset = *AlignedOffset;
+      const LLT LocationType = isSupportedFloat(Value.Type) ? Value.Type : *I64;
+      auto Assignment = stackAssignment(Value, Index + Fragment, State.StackOffset, LocationType,
+                                        VariadicArgument, RequiredAlignment);
+      if (!Assignment)
+        return std::unexpected(Assignment.error());
+      Result.Assignments.push_back(*Assignment);
+      if (State.StackOffset > std::numeric_limits<std::uint64_t>::max() - XLenBytes) {
+        return makeUnexpected(ErrorCode::Unsupported, "LP64D argument area overflows uint64");
+      }
+      State.StackOffset += XLenBytes;
+      FirstStackFragment = false;
+      if (VariadicArgument)
+        State.VariadicStackOnly = true;
+    }
+    Index += GroupSize;
+  }
+
+  auto FinalSize = alignTo(State.StackOffset, Convention.StackArgumentAlignmentBytes);
+  if (!FinalSize)
+    return std::unexpected(FinalSize.error());
+  Result.StackArea = StackArgumentArea{*FinalSize, Convention.ShadowSpaceBytes, *StackAlign};
+  Result.FirstUnallocatedGPR = State.GPR;
+  return Result;
+}
+
+[[nodiscard]] Expected<std::vector<CCAssignment>>
+assignReturns(std::span<const ABIValue> Values, bool RequireRegisters,
+              const CallingConventionInfo &Convention) {
+  auto Sequence = verifyValueSequence(Values, RequireRegisters);
+  if (!Sequence)
+    return std::unexpected(Sequence.error());
+  if (Values.size() > 2) {
+    return makeUnexpected(ErrorCode::Unsupported,
+                          "LP64D direct returns are limited to two explicit fragments");
+  }
+  auto I64 = LLT::makeInteger(64);
+  if (!I64)
+    return std::unexpected(I64.error());
+
+  std::vector<CCAssignment> Result;
+  Result.reserve(Values.size());
+  std::size_t GPR = 0;
+  std::size_t FPR = 0;
+  for (std::size_t Index = 0; Index < Values.size(); ++Index) {
+    const ABIValue &Value = Values[Index];
+    if (Value.Flags.rawValue() != 0) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "return fragments cannot carry argument-only ABI flags");
+    }
+    Expected<CCAssignment> Assignment =
+        isSupportedFloat(Value.Type)
+            ? registerAssignment(Value, Index, Convention.FloatingReturnRegisters[FPR++],
+                                 Value.Type, false, false)
+            : registerAssignment(Value, Index, Convention.IntegerReturnRegisters[GPR++], *I64,
+                                 false, false);
+    if (!Assignment)
+      return std::unexpected(Assignment.error());
+    Result.push_back(*Assignment);
+  }
+  return Result;
+}
+
+[[nodiscard]] bool hasStructReturn(std::span<const ABIValue> Arguments) noexcept {
+  return std::ranges::any_of(
+      Arguments, [](const ABIValue &Value) { return Value.Flags.has(ABIValueFlag::StructReturn); });
+}
+
+[[nodiscard]] bool equivalentReturnLocations(std::span<const CCAssignment> Left,
+                                             std::span<const CCAssignment> Right) noexcept {
+  if (Left.size() != Right.size())
+    return false;
+  for (std::size_t Index = 0; Index < Left.size(); ++Index) {
+    if (Left[Index].ValueType != Right[Index].ValueType ||
+        Left[Index].LocationType != Right[Index].LocationType ||
+        Left[Index].LocationKind != Right[Index].LocationKind ||
+        Left[Index].LocationRegister != Right[Index].LocationRegister ||
+        Left[Index].Extension != Right[Index].Extension ||
+        Left[Index].CustomFlags != Right[Index].CustomFlags) {
+      return false;
+    }
+  }
+  return true;
+}
+
+[[nodiscard]] Expected<std::string>
+tailCallRejection(const CallLoweringRequest &Request, const ArgumentAssignmentResult &Arguments,
+                  std::span<const CCAssignment> Results,
+                  std::span<const ByValCopyAssignment> ByValCopies,
+                  const CallingConventionInfo &Convention) {
+  if (!Convention.SupportsTailCalls)
+    return std::string("the calling convention does not support tail calls");
+  if (!Request.TailContext)
+    return std::string("tail-call context is missing");
+  const TailCallContext &Context = *Request.TailContext;
+  if (Context.CallerConvention != Request.Convention)
+    return std::string("caller and callee calling conventions differ");
+  if (Context.CallerIsVariadic != Request.IsVariadic ||
+      (Request.IsVariadic && Context.CallerFixedArgumentCount != Request.FixedArgumentCount)) {
+    return std::string("caller and callee variadic signatures differ");
+  }
+  if (Context.CallerHasDynamicStackAllocation)
+    return std::string("the caller has a dynamic stack allocation");
+  if (!ByValCopies.empty())
+    return std::string("tail calls cannot create byval copies");
+  if (Context.CallerUsesStructReturn != hasStructReturn(Request.Arguments))
+    return std::string("caller and callee sret conventions differ");
+  if (Arguments.StackArea.SizeBytes > Context.ReusableIncomingArgumentBytes)
+    return std::string("outgoing stack arguments exceed the reusable incoming area");
+  if (std::ranges::any_of(Request.Results,
+                          [](const ABIValue &Value) { return !Value.Value.isNoRegister(); })) {
+    return std::string("tail-call result signatures must not request local result copies");
+  }
+  auto CallerReturns = assignReturns(Context.CallerReturns, false, Convention);
+  if (!CallerReturns)
+    return std::unexpected(CallerReturns.error());
+  if (!equivalentReturnLocations(Results, *CallerReturns))
+    return std::string("caller and callee return locations differ");
+  return std::string{};
+}
+
+[[nodiscard]] Expected<const CallingConventionInfo *>
+lp64dConvention(CallingConventionID Convention) {
+  if (Convention != callingConventionID(CallingConvention::LP64D)) {
+    return makeUnexpected(ErrorCode::Unsupported,
+                          "RISC-V backend only supports the LP64D calling convention");
+  }
+  const CallingConventionInfo *Info = callingConvention(CallingConvention::LP64D);
+  if (Info == nullptr)
+    return makeUnexpected(ErrorCode::InternalError, "LP64D target facts are unavailable");
+  return Info;
+}
+
+class RISCVCallLowering final : public TargetCallLowering {
+public:
+  [[nodiscard]] Expected<CallLoweringPlan>
+  planFormalArguments(const FormalArgumentRequest &Request) const override;
+  [[nodiscard]] Expected<CallLoweringPlan>
+  planCall(const CallLoweringRequest &Request) const override;
+  [[nodiscard]] Expected<CallLoweringPlan>
+  planReturn(const ReturnLoweringRequest &Request) const override;
+  [[nodiscard]] Expected<void> emitPlan(MachineIRBuilder &Builder,
+                                        const CallLoweringPlan &Plan) const override;
+};
+
+Expected<CallLoweringPlan>
+RISCVCallLowering::planFormalArguments(const FormalArgumentRequest &Request) const {
+  auto Convention = lp64dConvention(Request.Convention);
+  if (!Convention)
+    return std::unexpected(Convention.error());
+  auto OriginalCount = verifyValueSequence(Request.Arguments, true);
+  if (!OriginalCount)
+    return std::unexpected(OriginalCount.error());
+  if (Request.FixedArgumentCount != *OriginalCount) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "formal-argument request must identify every declared argument as fixed");
+  }
+  if (!Request.IsVariadic && Request.FixedArgumentCount != *OriginalCount) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "non-variadic formal request has an invalid fixed-argument boundary");
+  }
+  if (hasStructReturn(Request.Arguments) &&
+      (Request.Arguments.empty() || Request.Arguments.front().OriginalValue != 0 ||
+       !Request.Arguments.front().Flags.has(ABIValueFlag::StructReturn))) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "LP64D sret must be the first formal argument");
+  }
+
+  auto Assignments = assignArguments(Request.Arguments, Request.FixedArgumentCount,
+                                     Request.IsVariadic, **Convention);
+  if (!Assignments)
+    return std::unexpected(Assignments.error());
+
+  VarArgLoweringState VarArgs;
+  if (Request.IsVariadic) {
+    VarArgs.IsVariadic = true;
+    VarArgs.FixedArgumentCount = Request.FixedArgumentCount;
+    VarArgs.FirstUnallocatedIntegerRegister = Assignments->FirstUnallocatedGPR;
+    VarArgs.OverflowAreaOffsetBytes = Assignments->StackArea.SizeBytes;
+    const std::size_t First = Assignments->FirstUnallocatedGPR;
+    const std::size_t RegisterCount = (*Convention)->IntegerArgumentRegisters.size();
+    VarArgs.RegisterSaveAreaSizeBytes = (RegisterCount - First) * XLenBytes;
+    VarArgs.RegisterSaveAreaOffsetBytes =
+        VarArgs.RegisterSaveAreaSizeBytes == 0
+            ? static_cast<std::int64_t>(VarArgs.OverflowAreaOffsetBytes)
+            : -static_cast<std::int64_t>(VarArgs.RegisterSaveAreaSizeBytes);
+    if (VarArgs.RegisterSaveAreaSizeBytes != 0 && First % 2 != 0)
+      VarArgs.RegisterSavePaddingBytes = XLenBytes;
+    for (std::size_t Index = First; Index < RegisterCount; ++Index) {
+      VarArgs.RegistersToSave.push_back(
+          {(*Convention)->IntegerArgumentRegisters[Index], (Index - First) * XLenBytes});
+    }
+  }
+
+  CallLoweringPlanDesc Plan;
+  Plan.Kind = CallLoweringPlanKind::FormalArguments;
+  Plan.Target = PlanTarget;
+  Plan.Convention = Request.Convention;
+  Plan.ArgumentAssignments = std::move(Assignments->Assignments);
+  Plan.StackArguments = Assignments->StackArea;
+  Plan.VarArgs = std::move(VarArgs);
+  return CallLoweringPlan::create(std::move(Plan));
+}
+
+Expected<CallLoweringPlan> RISCVCallLowering::planCall(const CallLoweringRequest &Request) const {
+  auto Convention = lp64dConvention(Request.Convention);
+  if (!Convention)
+    return std::unexpected(Convention.error());
+  auto OriginalCount = verifyValueSequence(Request.Arguments, true);
+  if (!OriginalCount)
+    return std::unexpected(OriginalCount.error());
+  if ((!Request.IsVariadic && Request.FixedArgumentCount != *OriginalCount) ||
+      (Request.IsVariadic && Request.FixedArgumentCount > *OriginalCount)) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "call request has an invalid fixed/variadic argument boundary");
+  }
+  if (Request.CallSiteID == 0 || !Request.Callee.isValid()) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "call request requires a valid callee and nonzero call-site ID");
+  }
+  if (hasStructReturn(Request.Arguments) &&
+      (Request.Arguments.empty() ||
+       !Request.Arguments.front().Flags.has(ABIValueFlag::StructReturn))) {
+    return makeUnexpected(ErrorCode::InvalidArgument, "LP64D sret must be the first call argument");
+  }
+  if (hasStructReturn(Request.Arguments) && !Request.Results.empty()) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "LP64D sret calls cannot also request direct return values");
+  }
+
+  MachineCallTarget EffectiveCallee = Request.Callee;
+  switch (Request.Callee.kind()) {
+  case MachineCallTargetKind::GlobalSymbol: {
+    if ((Request.Callee.targetFlags() & ~AllowedDirectCallFlags) != 0) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "direct RISC-V call uses unknown target flags");
+    }
+    auto Callee = MachineCallTarget::globalSymbol(
+        std::string(Request.Callee.symbolName()),
+        Request.Callee.targetFlags() | static_cast<std::uint32_t>(CallTargetFlag::DirectCall));
+    if (!Callee)
+      return std::unexpected(Callee.error());
+    EffectiveCallee = std::move(*Callee);
+    break;
+  }
+  case MachineCallTargetKind::ExternalSymbol: {
+    if ((Request.Callee.targetFlags() & ~AllowedDirectCallFlags) != 0) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "direct RISC-V call uses unknown target flags");
+    }
+    auto Callee = MachineCallTarget::externalSymbol(
+        std::string(Request.Callee.symbolName()),
+        Request.Callee.targetFlags() | static_cast<std::uint32_t>(CallTargetFlag::DirectCall));
+    if (!Callee)
+      return std::unexpected(Callee.error());
+    EffectiveCallee = std::move(*Callee);
+    break;
+  }
+  case MachineCallTargetKind::IndirectRegister:
+    if (Request.Callee.targetFlags() != 0) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "indirect RISC-V calls cannot carry direct-call target flags");
+    }
+    break;
+  case MachineCallTargetKind::Invalid:
+    return makeUnexpected(ErrorCode::InvalidArgument, "call target is invalid");
+  }
+
+  const bool RequireResultRegisters = Request.TailKind == TailCallKind::NotTail;
+  auto ResultSequence = verifyValueSequence(Request.Results, RequireResultRegisters);
+  if (!ResultSequence)
+    return std::unexpected(ResultSequence.error());
+  auto Arguments = assignArguments(Request.Arguments, Request.FixedArgumentCount,
+                                   Request.IsVariadic, **Convention);
+  if (!Arguments)
+    return std::unexpected(Arguments.error());
+  auto Results = assignReturns(Request.Results, RequireResultRegisters, **Convention);
+  if (!Results)
+    return std::unexpected(Results.error());
+
+  auto Align16 = alignment(LP64DStackAlignmentBytes);
+  if (!Align16)
+    return std::unexpected(Align16.error());
+  std::uint64_t CallFrameCursor = Arguments->StackArea.SizeBytes;
+  std::vector<ByValCopyAssignment> ByValCopies;
+  for (std::size_t Index = 0; Index < Arguments->Assignments.size(); ++Index) {
+    const CCAssignment &Assignment = Arguments->Assignments[Index];
+    if (!Assignment.CustomFlags.has(CCAssignmentFlag::ByVal))
+      continue;
+    const ABIValue &Value = Request.Arguments[Assignment.ValueIndex];
+    const std::uint64_t CopyAlignment =
+        std::min<std::uint64_t>(Value.ByValAlignment.bytes(), LP64DStackAlignmentBytes);
+    auto CopyOffset = alignTo(CallFrameCursor, CopyAlignment);
+    if (!CopyOffset)
+      return std::unexpected(CopyOffset.error());
+    if (*CopyOffset > std::numeric_limits<std::uint64_t>::max() - Value.ByValSizeBytes) {
+      return makeUnexpected(ErrorCode::Unsupported, "LP64D byval area overflows uint64");
+    }
+    auto CopyAlign = alignment(CopyAlignment);
+    if (!CopyAlign)
+      return std::unexpected(CopyAlign.error());
+    ByValCopies.push_back(
+        {Index, Value.Value, Value.Type, *CopyOffset, Value.ByValSizeBytes, *CopyAlign});
+    CallFrameCursor = *CopyOffset + Value.ByValSizeBytes;
+  }
+  auto CallFrameSize = alignTo(CallFrameCursor, LP64DStackAlignmentBytes);
+  if (!CallFrameSize)
+    return std::unexpected(CallFrameSize.error());
+
+  TailCallKind Decision = TailCallKind::NotTail;
+  std::string RejectionReason;
+  if (Request.TailKind != TailCallKind::NotTail) {
+    auto Rejection = tailCallRejection(Request, *Arguments, *Results, ByValCopies, **Convention);
+    if (!Rejection)
+      return std::unexpected(Rejection.error());
+    RejectionReason = std::move(*Rejection);
+    if (RejectionReason.empty()) {
+      Decision = Request.TailKind;
+    } else if (Request.TailKind == TailCallKind::MustTail) {
+      return makeUnexpected(ErrorCode::Unsupported,
+                            "musttail call is not ABI-compatible: " + RejectionReason);
+    } else {
+      auto NormalResults = verifyValueSequence(Request.Results, true);
+      if (!NormalResults)
+        return std::unexpected(NormalResults.error());
+    }
+  }
+
+  CallLoweringPlanDesc Plan;
+  Plan.Kind = CallLoweringPlanKind::Call;
+  Plan.Target = PlanTarget;
+  Plan.Convention = Request.Convention;
+  Plan.ArgumentAssignments = std::move(Arguments->Assignments);
+  Plan.ReturnAssignments = std::move(*Results);
+  Plan.StackArguments = Arguments->StackArea;
+  Plan.CallFrame = CallFrameRequirements{
+      Decision == TailCallKind::NotTail ? *CallFrameSize : Arguments->StackArea.SizeBytes, *Align16,
+      Decision == TailCallKind::NotTail, Decision == TailCallKind::NotTail,
+      Decision != TailCallKind::NotTail};
+  if (Request.IsVariadic) {
+    Plan.VarArgs.IsVariadic = true;
+    Plan.VarArgs.FixedArgumentCount = Request.FixedArgumentCount;
+  }
+  Plan.ByValCopies = std::move(ByValCopies);
+  Plan.PreservedMask = createCallPreservedMask();
+  Plan.Callee = std::move(EffectiveCallee);
+  Plan.CallSiteID = Request.CallSiteID;
+  Plan.TailDecision = Decision;
+  Plan.TailRejectionReason = std::move(RejectionReason);
+  return CallLoweringPlan::create(std::move(Plan));
+}
+
+Expected<CallLoweringPlan>
+RISCVCallLowering::planReturn(const ReturnLoweringRequest &Request) const {
+  auto Convention = lp64dConvention(Request.Convention);
+  if (!Convention)
+    return std::unexpected(Convention.error());
+  auto Values = assignReturns(Request.Values, true, **Convention);
+  if (!Values)
+    return std::unexpected(Values.error());
+
+  CallLoweringPlanDesc Plan;
+  Plan.Kind = CallLoweringPlanKind::Return;
+  Plan.Target = PlanTarget;
+  Plan.Convention = Request.Convention;
+  Plan.ReturnAssignments = std::move(*Values);
+  return CallLoweringPlan::create(std::move(Plan));
+}
+
+[[nodiscard]] CallValueTransform outgoingTransform(const CCAssignment &Assignment) noexcept {
+  if (Assignment.CustomFlags.has(CCAssignmentFlag::Bitcast))
+    return CallValueTransform::Bitcast;
+  switch (Assignment.Extension) {
+  case ABIExtensionKind::None:
+    return CallValueTransform::Full;
+  case ABIExtensionKind::AnyExtend:
+    return CallValueTransform::AnyExtend;
+  case ABIExtensionKind::SignExtend:
+    return CallValueTransform::SignExtend;
+  case ABIExtensionKind::ZeroExtend:
+    return CallValueTransform::ZeroExtend;
+  case ABIExtensionKind::Count:
+    break;
+  }
+  return CallValueTransform::Full;
+}
+
+[[nodiscard]] CallValueTransform incomingTransform(const CCAssignment &Assignment) noexcept {
+  if (Assignment.CustomFlags.has(CCAssignmentFlag::Bitcast))
+    return CallValueTransform::Bitcast;
+  if (Assignment.ValueType.scalarBitWidth() < Assignment.LocationType.scalarBitWidth())
+    return CallValueTransform::Truncate;
+  return CallValueTransform::Full;
+}
+
+[[nodiscard]] Expected<void> addUnsignedImmediate(MachineInstrBuilder &Builder,
+                                                  std::uint64_t Value) {
+  auto Immediate = IntegerImmediate::fromUnsigned(64, Value);
+  if (!Immediate)
+    return std::unexpected(Immediate.error());
+  return Builder.addIntegerImmediate(std::move(*Immediate));
+}
+
+[[nodiscard]] Expected<const MachineMemOperand *>
+createMemoryOperand(MachineFunction &Function, MemoryAccessFlags Accesses, std::uint64_t SizeBytes,
+                    Alignment Align, MemoryBase Base, std::int64_t Offset = 0) {
+  auto Size = MemorySize::fixed(SizeBytes);
+  if (!Size)
+    return std::unexpected(Size.error());
+  MachineMemOperandDesc Description;
+  Description.Accesses = Accesses;
+  Description.Size = *Size;
+  Description.Align = Align;
+  Description.Base = std::move(Base);
+  Description.Offset = Offset;
+  return Function.createMemOperand(std::move(Description));
+}
+
+[[nodiscard]] Expected<void> emitCCCopy(MachineIRBuilder &Builder, Register Destination,
+                                        Register Source, CallValueTransform Transform) {
+  auto Instruction = Builder.buildInstr(targetOpcode(InstructionOpcode::PseudoCC_COPY));
+  if (!Instruction)
+    return std::unexpected(Instruction.error());
+  auto Def = Instruction->addDef(Destination);
+  if (!Def)
+    return std::unexpected(Def.error());
+  auto Use = Instruction->addUse(Source);
+  if (!Use)
+    return std::unexpected(Use.error());
+  auto Action = Instruction->addImmediate(static_cast<std::int64_t>(Transform));
+  if (!Action)
+    return std::unexpected(Action.error());
+  auto Built = Instruction->build();
+  if (!Built)
+    return std::unexpected(Built.error());
+  return {};
+}
+
+[[nodiscard]] Expected<void> emitStackLoad(MachineIRBuilder &Builder,
+                                           const CCAssignment &Assignment, FrameIndex Object,
+                                           std::uint64_t ObjectOffset,
+                                           const MachineMemOperand &Memory) {
+  auto Instruction = Builder.buildInstr(targetOpcode(InstructionOpcode::PseudoLOAD_STACK_ARG));
+  if (!Instruction)
+    return std::unexpected(Instruction.error());
+  auto Def = Instruction->addDef(Assignment.OriginalValue);
+  if (!Def)
+    return std::unexpected(Def.error());
+  auto Frame = Instruction->addFrameIndex(Object);
+  if (!Frame)
+    return std::unexpected(Frame.error());
+  auto Offset = addUnsignedImmediate(*Instruction, ObjectOffset);
+  if (!Offset)
+    return std::unexpected(Offset.error());
+  auto Transform =
+      Instruction->addImmediate(static_cast<std::int64_t>(incomingTransform(Assignment)));
+  if (!Transform)
+    return std::unexpected(Transform.error());
+  auto Mem = Instruction->addMemOperand(Memory);
+  if (!Mem)
+    return std::unexpected(Mem.error());
+  auto Built = Instruction->build();
+  if (!Built)
+    return std::unexpected(Built.error());
+  return {};
+}
+
+[[nodiscard]] Expected<void> emitStackStore(MachineIRBuilder &Builder, Register Source,
+                                            FrameIndex Object, std::uint64_t ObjectOffset,
+                                            const MachineMemOperand &Memory,
+                                            CallValueTransform Transform) {
+  auto Instruction = Builder.buildInstr(targetOpcode(InstructionOpcode::PseudoSTORE_STACK_ARG));
+  if (!Instruction)
+    return std::unexpected(Instruction.error());
+  auto Use = Instruction->addUse(Source);
+  if (!Use)
+    return std::unexpected(Use.error());
+  auto Frame = Instruction->addFrameIndex(Object);
+  if (!Frame)
+    return std::unexpected(Frame.error());
+  auto Offset = addUnsignedImmediate(*Instruction, ObjectOffset);
+  if (!Offset)
+    return std::unexpected(Offset.error());
+  auto Action = Instruction->addImmediate(static_cast<std::int64_t>(Transform));
+  if (!Action)
+    return std::unexpected(Action.error());
+  auto Mem = Instruction->addMemOperand(Memory);
+  if (!Mem)
+    return std::unexpected(Mem.error());
+  auto Built = Instruction->build();
+  if (!Built)
+    return std::unexpected(Built.error());
+  return {};
+}
+
+[[nodiscard]] Expected<void> ensureFunctionLiveIn(MachineRegisterInfo &Registers,
+                                                  PhysicalRegister Reg,
+                                                  std::optional<Register> InitialValue) {
+  const auto Existing =
+      std::ranges::find(Registers.liveIns(), Reg, &PhysicalRegisterLiveIn::PhysReg);
+  if (Existing == Registers.liveIns().end())
+    return Registers.addLiveIn(Reg, InitialValue);
+  if (InitialValue && Existing->InitialVirtualRegister &&
+      Existing->InitialVirtualRegister != InitialValue) {
+    return makeUnexpected(ErrorCode::VerificationError,
+                          "physical formal register already maps to another virtual live-in");
+  }
+  return {};
+}
+
+[[nodiscard]] Expected<void> ensureBlockLiveIn(MachineBasicBlock &Block, PhysicalRegister Reg) {
+  return Block.addLiveIn(Reg, LaneMask::all());
+}
+
+[[nodiscard]] Expected<void> verifyPlanRegisters(const CallLoweringPlan &Plan,
+                                                 const MachineFunction &Function,
+                                                 const TargetDescription &Target) {
+  const MachineRegisterInfo &Registers = Function.registerInfo();
+  const auto Verify = [&Registers, &Target](const CCAssignment &Assignment) -> Expected<void> {
+    if (Assignment.LocationRegister &&
+        !Target.registers().isKnownPhysicalRegister(*Assignment.LocationRegister)) {
+      return makeUnexpected(ErrorCode::VerificationError,
+                            "call-lowering plan names an unknown ABI location register");
+    }
+    const Register Reg = Assignment.OriginalValue;
+    if (Reg.isNoRegister())
+      return {};
+    if (Reg.isPhysical()) {
+      if (!Target.registers().isKnownPhysicalRegister(*Reg.physicalRegister())) {
+        return makeUnexpected(ErrorCode::VerificationError,
+                              "call-lowering plan names an unknown physical value register");
+      }
+      return {};
+    }
+    auto Info = Registers.virtualRegisterInfo(Reg);
+    if (!Info)
+      return std::unexpected(Info.error());
+    if (!Info->get().Type || *Info->get().Type != Assignment.ValueType) {
+      return makeUnexpected(ErrorCode::VerificationError,
+                            "call-lowering plan register LLT differs from MachineRegisterInfo");
+    }
+    return {};
+  };
+  for (const CCAssignment &Assignment : Plan.argumentAssignments()) {
+    auto Result = Verify(Assignment);
+    if (!Result)
+      return std::unexpected(Result.error());
+  }
+  for (const CCAssignment &Assignment : Plan.returnAssignments()) {
+    auto Result = Verify(Assignment);
+    if (!Result)
+      return std::unexpected(Result.error());
+  }
+  if (const MachineCallTarget *Callee = Plan.callee();
+      Callee != nullptr && Callee->kind() == MachineCallTargetKind::IndirectRegister) {
+    const Register CalleeReg = Callee->indirectRegister();
+    if (CalleeReg.isPhysical()) {
+      const std::optional<PhysicalRegister> Physical = CalleeReg.physicalRegister();
+      if (!Physical || !Target.registers().isKnownPhysicalRegister(*Physical)) {
+        return makeUnexpected(ErrorCode::VerificationError,
+                              "indirect LP64D callee names an unknown physical register");
+      }
+    } else {
+      auto Info = Registers.virtualRegisterInfo(CalleeReg);
+      if (!Info)
+        return std::unexpected(Info.error());
+      const std::optional<LLT> Type = Info->get().Type;
+      if (!Type || ((!Type->isPointer() && !Type->isInteger()) || Type->scalarBitWidth() != 64)) {
+        return makeUnexpected(ErrorCode::VerificationError,
+                              "indirect LP64D callee requires a 64-bit pointer or integer LLT");
+      }
+    }
+  }
+  return {};
+}
+
+[[nodiscard]] Expected<void> verifyRequiredOpcodes(const MachineIRBuilder &Builder) {
+  static constexpr std::array Required{
+      InstructionOpcode::PseudoCC_COPY,
+      InstructionOpcode::PseudoLOAD_STACK_ARG,
+      InstructionOpcode::PseudoSTORE_STACK_ARG,
+      InstructionOpcode::PseudoBYVAL_COPY,
+      InstructionOpcode::ADJCALLSTACKDOWN,
+      InstructionOpcode::ADJCALLSTACKUP,
+      InstructionOpcode::PseudoCALL,
+      InstructionOpcode::PseudoTAIL,
+      InstructionOpcode::PseudoRET,
+  };
+  for (const InstructionOpcode OpcodeValue : Required) {
+    if (Builder.target().instructionDescriptor(targetOpcode(OpcodeValue)) == nullptr) {
+      return makeUnexpected(ErrorCode::InternalError,
+                            "RISC-V target description lacks a call-lowering pseudo");
+    }
+  }
+  return {};
+}
+
+[[nodiscard]] Expected<void> verifyFormalLiveIns(const CallLoweringPlan &Plan,
+                                                 const MachineFunction &Function) {
+  if (Plan.kind() != CallLoweringPlanKind::FormalArguments)
+    return {};
+
+  const auto LiveIns = Function.registerInfo().liveIns();
+  for (const CCAssignment &Assignment : Plan.argumentAssignments()) {
+    if (!Assignment.LocationRegister || !Assignment.OriginalValue.isVirtual())
+      continue;
+    const auto Existing =
+        std::ranges::find(LiveIns, *Assignment.LocationRegister, &PhysicalRegisterLiveIn::PhysReg);
+    if (Existing != LiveIns.end() && Existing->InitialVirtualRegister &&
+        *Existing->InitialVirtualRegister != Assignment.OriginalValue) {
+      return makeUnexpected(ErrorCode::VerificationError,
+                            "physical formal register already maps to another virtual live-in");
+    }
+  }
+  return {};
+}
+
+[[nodiscard]] Expected<void> preflightPlan(MachineIRBuilder &Builder,
+                                           const CallLoweringPlan &Plan) {
+  if (Plan.target() != PlanTarget ||
+      Plan.convention() != callingConventionID(CallingConvention::LP64D)) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "call-lowering plan belongs to another target or ABI");
+  }
+  auto InsertPoint = Builder.verifyInsertPoint();
+  if (!InsertPoint)
+    return std::unexpected(InsertPoint.error());
+  auto Opcodes = verifyRequiredOpcodes(Builder);
+  if (!Opcodes)
+    return std::unexpected(Opcodes.error());
+  auto Registers = verifyPlanRegisters(Plan, Builder.function(), Builder.target());
+  if (!Registers)
+    return std::unexpected(Registers.error());
+  auto LiveIns = verifyFormalLiveIns(Plan, Builder.function());
+  if (!LiveIns)
+    return std::unexpected(LiveIns.error());
+  for (const CCAssignment &Assignment : Plan.argumentAssignments()) {
+    if (Assignment.StackOffsetBytes &&
+        *Assignment.StackOffsetBytes >
+            static_cast<std::uint64_t>(std::numeric_limits<std::int64_t>::max())) {
+      return makeUnexpected(ErrorCode::Unsupported,
+                            "LP64D stack assignment offset exceeds the frame-index range");
+    }
+  }
+  for (const ByValCopyAssignment &Copy : Plan.byValCopies()) {
+    if (Copy.StackOffsetBytes >
+        static_cast<std::uint64_t>(std::numeric_limits<std::int64_t>::max())) {
+      return makeUnexpected(ErrorCode::Unsupported,
+                            "LP64D byval offset exceeds the frame-index range");
+    }
+  }
+  if (Plan.kind() != CallLoweringPlanKind::Return && Builder.function().frameInfo().isFrozen()) {
+    return makeUnexpected(ErrorCode::VerificationError,
+                          "call lowering cannot modify a frozen machine frame");
+  }
+  if (Plan.kind() == CallLoweringPlanKind::FormalArguments &&
+      (Builder.function().firstBlock() == nullptr ||
+       Builder.insertionBlock() != Builder.function().firstBlock())) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "formal arguments must be lowered in the entry machine block");
+  }
+  return {};
+}
+
+[[nodiscard]] Expected<void> updateMaximumFrameAlignment(MachineFrameState &State,
+                                                         Alignment Required) {
+  if (!State.MaxAlignment || State.MaxAlignment->bytes() < Required.bytes())
+    State.MaxAlignment = Required;
+  return {};
+}
+
+[[nodiscard]] Expected<void> emitFormalArguments(MachineIRBuilder &Builder,
+                                                 const CallLoweringPlan &Plan) {
+  MachineFunction &Function = Builder.function();
+  MachineBasicBlock &Entry = *Function.firstBlock();
+  MachineRegisterInfo &Registers = Function.registerInfo();
+  MachineFrameInfo &Frame = Function.frameInfo();
+  Alignment RequiredFrameAlignment;
+
+  for (const CCAssignment &Assignment : Plan.argumentAssignments()) {
+    if (Assignment.LocationRegister) {
+      const PhysicalRegister Location = *Assignment.LocationRegister;
+      const std::optional<Register> Initial =
+          Assignment.OriginalValue.isVirtual() ? std::optional<Register>(Assignment.OriginalValue)
+                                               : std::nullopt;
+      auto FunctionLiveIn = ensureFunctionLiveIn(Registers, Location, Initial);
+      if (!FunctionLiveIn)
+        return std::unexpected(FunctionLiveIn.error());
+      auto BlockLiveIn = ensureBlockLiveIn(Entry, Location);
+      if (!BlockLiveIn)
+        return std::unexpected(BlockLiveIn.error());
+      auto Copy = emitCCCopy(Builder, Assignment.OriginalValue, Register::fromPhysical(Location),
+                             incomingTransform(Assignment));
+      if (!Copy)
+        return std::unexpected(Copy.error());
+      continue;
+    }
+
+    if (!Assignment.StackOffsetBytes) {
+      return makeUnexpected(ErrorCode::InternalError,
+                            "verified formal stack assignment has no stack offset");
+    }
+    StackObjectDesc Object;
+    Object.Kind = StackObjectKind::FixedABI;
+    Object.Size = Assignment.StackSlotSizeBytes;
+    Object.Align = Assignment.LocationAlignment;
+    Object.Offset = static_cast<std::int64_t>(*Assignment.StackOffsetBytes);
+    Object.IsImmutable = true;
+    Object.TargetFlags = stackObjectFlag(CallStackObjectFlag::IncomingArgument);
+    auto FrameObject = Frame.createObject(std::move(Object));
+    if (!FrameObject)
+      return std::unexpected(FrameObject.error());
+    auto Memory =
+        createMemoryOperand(Function, {MemoryAccessFlag::Load}, Assignment.LocationSizeBytes,
+                            Assignment.LocationAlignment, MemoryBase::frameIndex(*FrameObject));
+    if (!Memory)
+      return std::unexpected(Memory.error());
+    auto Load = emitStackLoad(Builder, Assignment, *FrameObject, 0, **Memory);
+    if (!Load)
+      return std::unexpected(Load.error());
+    if (RequiredFrameAlignment.bytes() < Assignment.LocationAlignment.bytes())
+      RequiredFrameAlignment = Assignment.LocationAlignment;
+  }
+
+  const VarArgLoweringState &VarArgs = Plan.varArgs();
+  if (!VarArgs.IsVariadic) {
+    if (RequiredFrameAlignment.bytes() == 1)
+      return {};
+    MachineFrameState State = Frame.state();
+    auto AlignmentUpdate = updateMaximumFrameAlignment(State, RequiredFrameAlignment);
+    if (!AlignmentUpdate)
+      return std::unexpected(AlignmentUpdate.error());
+    return Frame.setState(std::move(State));
+  }
+
+  auto Align8 = alignment(XLenBytes);
+  auto Align16 = alignment(LP64DStackAlignmentBytes);
+  if (!Align8 || !Align16)
+    return makeUnexpected(ErrorCode::InternalError, "LP64D primitive type facts are invalid");
+
+  FrameIndex SaveObject;
+  if (VarArgs.RegisterSaveAreaSizeBytes == 0) {
+    StackObjectDesc Object;
+    Object.Kind = StackObjectKind::FixedABI;
+    Object.Size = XLenBytes;
+    Object.Align = *Align8;
+    Object.Offset = VarArgs.RegisterSaveAreaOffsetBytes;
+    Object.IsImmutable = true;
+    Object.TargetFlags = stackObjectFlag(CallStackObjectFlag::VarArgSaveArea);
+    auto Created = Frame.createObject(std::move(Object));
+    if (!Created)
+      return std::unexpected(Created.error());
+    SaveObject = *Created;
+  } else {
+    StackObjectDesc Object;
+    Object.Kind = StackObjectKind::FixedABI;
+    Object.Size = VarArgs.RegisterSaveAreaSizeBytes;
+    Object.Align = VarArgs.FirstUnallocatedIntegerRegister % 2 == 0 ? *Align16 : *Align8;
+    Object.Offset = VarArgs.RegisterSaveAreaOffsetBytes;
+    Object.TargetFlags = stackObjectFlag(CallStackObjectFlag::VarArgSaveArea);
+    auto Created = Frame.createObject(std::move(Object));
+    if (!Created)
+      return std::unexpected(Created.error());
+    SaveObject = *Created;
+
+    if (VarArgs.RegisterSavePaddingBytes != 0) {
+      StackObjectDesc Padding;
+      Padding.Kind = StackObjectKind::FixedABI;
+      Padding.Size = VarArgs.RegisterSavePaddingBytes;
+      Padding.Align = *Align8;
+      Padding.Offset = VarArgs.RegisterSaveAreaOffsetBytes -
+                       static_cast<std::int64_t>(VarArgs.RegisterSavePaddingBytes);
+      Padding.IsImmutable = true;
+      Padding.TargetFlags = stackObjectFlag(CallStackObjectFlag::VarArgAlignmentPadding);
+      auto CreatedPadding = Frame.createObject(std::move(Padding));
+      if (!CreatedPadding)
+        return std::unexpected(CreatedPadding.error());
+    }
+  }
+
+  for (const VarArgRegisterSave Save : VarArgs.RegistersToSave) {
+    auto FunctionLiveIn = ensureFunctionLiveIn(Registers, Save.Reg, std::nullopt);
+    if (!FunctionLiveIn)
+      return std::unexpected(FunctionLiveIn.error());
+    auto BlockLiveIn = ensureBlockLiveIn(Entry, Save.Reg);
+    if (!BlockLiveIn)
+      return std::unexpected(BlockLiveIn.error());
+    auto Memory = createMemoryOperand(Function, {MemoryAccessFlag::Store}, XLenBytes, *Align8,
+                                      MemoryBase::frameIndex(SaveObject),
+                                      static_cast<std::int64_t>(Save.OffsetBytes));
+    if (!Memory)
+      return std::unexpected(Memory.error());
+    auto Store = emitStackStore(Builder, Register::fromPhysical(Save.Reg), SaveObject,
+                                Save.OffsetBytes, **Memory, CallValueTransform::Full);
+    if (!Store)
+      return std::unexpected(Store.error());
+  }
+
+  MachineFrameState State = Frame.state();
+  const Alignment VarArgAlignment =
+      RequiredFrameAlignment.bytes() > Align16->bytes() ? RequiredFrameAlignment : *Align16;
+  auto AlignmentUpdate = updateMaximumFrameAlignment(State, VarArgAlignment);
+  if (!AlignmentUpdate)
+    return std::unexpected(AlignmentUpdate.error());
+  return Frame.setState(std::move(State));
+}
+
+[[nodiscard]] Expected<void> emitCallFrameAdjustment(MachineIRBuilder &Builder,
+                                                     InstructionOpcode OpcodeValue,
+                                                     const CallFrameRequirements &Frame,
+                                                     MachineInstrFlag Flag) {
+  auto Instruction = Builder.buildInstr(targetOpcode(OpcodeValue));
+  if (!Instruction)
+    return std::unexpected(Instruction.error());
+  auto Size = addUnsignedImmediate(*Instruction, Frame.SizeBytes);
+  if (!Size)
+    return std::unexpected(Size.error());
+  auto Align = addUnsignedImmediate(*Instruction, Frame.Align.bytes());
+  if (!Align)
+    return std::unexpected(Align.error());
+  auto Flags = Instruction->setFlags({Flag});
+  if (!Flags)
+    return std::unexpected(Flags.error());
+  auto Built = Instruction->build();
+  if (!Built)
+    return std::unexpected(Built.error());
+  return {};
+}
+
+[[nodiscard]] Expected<std::unordered_map<std::size_t, Register>>
+emitByValCopies(MachineIRBuilder &Builder, const CallLoweringPlan &Plan) {
+  MachineFunction &Function = Builder.function();
+  MachineFrameInfo &Frame = Function.frameInfo();
+  std::unordered_map<std::size_t, Register> Replacements;
+  for (const ByValCopyAssignment Copy : Plan.byValCopies()) {
+    StackObjectDesc Object;
+    Object.Kind = StackObjectKind::Target;
+    Object.Size = Copy.SizeBytes;
+    Object.Align = Copy.Align;
+    Object.LocalOffset = static_cast<std::int64_t>(Copy.StackOffsetBytes);
+    Object.TargetFlags = stackObjectFlag(CallStackObjectFlag::ByValCopy);
+    auto FrameObject = Frame.createObject(std::move(Object));
+    if (!FrameObject)
+      return std::unexpected(FrameObject.error());
+    auto Temporary = Function.registerInfo().createVirtualRegister(Copy.PointerType);
+    if (!Temporary)
+      return std::unexpected(Temporary.error());
+
+    auto SourceMemory = createMemoryOperand(Function, {MemoryAccessFlag::Load}, Copy.SizeBytes,
+                                            Copy.Align, MemoryBase{});
+    if (!SourceMemory)
+      return std::unexpected(SourceMemory.error());
+    auto DestinationMemory =
+        createMemoryOperand(Function, {MemoryAccessFlag::Store}, Copy.SizeBytes, Copy.Align,
+                            MemoryBase::frameIndex(*FrameObject));
+    if (!DestinationMemory)
+      return std::unexpected(DestinationMemory.error());
+
+    auto Instruction = Builder.buildInstr(targetOpcode(InstructionOpcode::PseudoBYVAL_COPY));
+    if (!Instruction)
+      return std::unexpected(Instruction.error());
+    auto Def = Instruction->addDef(*Temporary);
+    if (!Def)
+      return std::unexpected(Def.error());
+    auto Use = Instruction->addUse(Copy.Source);
+    if (!Use)
+      return std::unexpected(Use.error());
+    auto FrameOperand = Instruction->addFrameIndex(*FrameObject);
+    if (!FrameOperand)
+      return std::unexpected(FrameOperand.error());
+    auto Size = addUnsignedImmediate(*Instruction, Copy.SizeBytes);
+    if (!Size)
+      return std::unexpected(Size.error());
+    auto Align = addUnsignedImmediate(*Instruction, Copy.Align.bytes());
+    if (!Align)
+      return std::unexpected(Align.error());
+    auto SourceMem = Instruction->addMemOperand(**SourceMemory);
+    if (!SourceMem)
+      return std::unexpected(SourceMem.error());
+    auto DestinationMem = Instruction->addMemOperand(**DestinationMemory);
+    if (!DestinationMem)
+      return std::unexpected(DestinationMem.error());
+    auto Built = Instruction->build();
+    if (!Built)
+      return std::unexpected(Built.error());
+    Replacements.emplace(Copy.ArgumentAssignmentIndex, *Temporary);
+  }
+  return Replacements;
+}
+
+[[nodiscard]] Expected<void>
+emitOutgoingArguments(MachineIRBuilder &Builder, const CallLoweringPlan &Plan,
+                      const std::unordered_map<std::size_t, Register> &Replacements) {
+  MachineFunction &Function = Builder.function();
+  MachineFrameInfo &Frame = Function.frameInfo();
+  const auto Assignments = Plan.argumentAssignments();
+  for (std::size_t Index = 0; Index < Assignments.size(); ++Index) {
+    const CCAssignment &Assignment = Assignments[Index];
+    const auto Replacement = Replacements.find(Index);
+    const Register Source =
+        Replacement == Replacements.end() ? Assignment.OriginalValue : Replacement->second;
+    if (Assignment.LocationRegister) {
+      auto Copy = emitCCCopy(Builder, Register::fromPhysical(*Assignment.LocationRegister), Source,
+                             outgoingTransform(Assignment));
+      if (!Copy)
+        return std::unexpected(Copy.error());
+      continue;
+    }
+
+    if (!Assignment.StackOffsetBytes) {
+      return makeUnexpected(ErrorCode::InternalError,
+                            "verified outgoing stack assignment has no stack offset");
+    }
+    StackObjectDesc Object;
+    Object.Size = Assignment.StackSlotSizeBytes;
+    Object.Align = Assignment.LocationAlignment;
+    Object.TargetFlags = stackObjectFlag(CallStackObjectFlag::OutgoingArgument);
+    if (Plan.tailDecision() == TailCallKind::NotTail) {
+      Object.Kind = StackObjectKind::Target;
+      Object.LocalOffset = static_cast<std::int64_t>(*Assignment.StackOffsetBytes);
+    } else {
+      Object.Kind = StackObjectKind::FixedABI;
+      Object.Offset = static_cast<std::int64_t>(*Assignment.StackOffsetBytes);
+    }
+    auto FrameObject = Frame.createObject(std::move(Object));
+    if (!FrameObject)
+      return std::unexpected(FrameObject.error());
+    auto Memory =
+        createMemoryOperand(Function, {MemoryAccessFlag::Store}, Assignment.LocationSizeBytes,
+                            Assignment.LocationAlignment, MemoryBase::frameIndex(*FrameObject));
+    if (!Memory)
+      return std::unexpected(Memory.error());
+    auto Store =
+        emitStackStore(Builder, Source, *FrameObject, 0, **Memory, outgoingTransform(Assignment));
+    if (!Store)
+      return std::unexpected(Store.error());
+  }
+  return {};
+}
+
+[[nodiscard]] Expected<void> addCallTarget(MachineInstrBuilder &Instruction,
+                                           const MachineCallTarget &Callee) {
+  switch (Callee.kind()) {
+  case MachineCallTargetKind::GlobalSymbol:
+    return Instruction.addGlobalSymbol(std::string(Callee.symbolName()), 0, Callee.targetFlags());
+  case MachineCallTargetKind::ExternalSymbol:
+    return Instruction.addExternalSymbol(std::string(Callee.symbolName()), 0, Callee.targetFlags());
+  case MachineCallTargetKind::IndirectRegister:
+    return Instruction.addUse(Callee.indirectRegister());
+  case MachineCallTargetKind::Invalid:
+    break;
+  }
+  return makeUnexpected(ErrorCode::InternalError,
+                        "verified call-lowering plan has an invalid callee");
+}
+
+[[nodiscard]] Expected<PhysicalRegister> requiredLocationRegister(const CCAssignment &Assignment) {
+  if (!Assignment.LocationRegister) {
+    return makeUnexpected(ErrorCode::InternalError,
+                          "verified return assignment has no location register");
+  }
+  return *Assignment.LocationRegister;
+}
+
+[[nodiscard]] Expected<void> emitCallInstruction(MachineIRBuilder &Builder,
+                                                 const CallLoweringPlan &Plan) {
+  const bool IsTail = Plan.tailDecision() != TailCallKind::NotTail;
+  auto Instruction = Builder.buildInstr(
+      targetOpcode(IsTail ? InstructionOpcode::PseudoTAIL : InstructionOpcode::PseudoCALL));
+  if (!Instruction)
+    return std::unexpected(Instruction.error());
+  auto Callee = addCallTarget(*Instruction, *Plan.callee());
+  if (!Callee)
+    return std::unexpected(Callee.error());
+  auto CallSite = addUnsignedImmediate(*Instruction, Plan.callSiteID());
+  if (!CallSite)
+    return std::unexpected(CallSite.error());
+  auto Mask = Instruction->addRegisterMask(Plan.preservedMask());
+  if (!Mask)
+    return std::unexpected(Mask.error());
+
+  std::unordered_set<PhysicalRegister> DynamicDefs;
+  if (!IsTail) {
+    for (const CCAssignment &Assignment : Plan.returnAssignments()) {
+      if (Assignment.LocationRegister && DynamicDefs.insert(*Assignment.LocationRegister).second) {
+        auto Def =
+            Instruction->addImplicitDef(Register::fromPhysical(*Assignment.LocationRegister));
+        if (!Def)
+          return std::unexpected(Def.error());
+      }
+    }
+  }
+  std::unordered_set<PhysicalRegister> DynamicUses;
+  for (const CCAssignment &Assignment : Plan.argumentAssignments()) {
+    if (Assignment.LocationRegister && DynamicUses.insert(*Assignment.LocationRegister).second) {
+      auto Use = Instruction->addImplicitUse(Register::fromPhysical(*Assignment.LocationRegister));
+      if (!Use)
+        return std::unexpected(Use.error());
+    }
+  }
+  auto Built = Instruction->build();
+  if (!Built)
+    return std::unexpected(Built.error());
+  return {};
+}
+
+[[nodiscard]] Expected<void> emitCall(MachineIRBuilder &Builder, const CallLoweringPlan &Plan) {
+  if (Plan.callFrame().EmitSetup) {
+    auto Down = emitCallFrameAdjustment(Builder, InstructionOpcode::ADJCALLSTACKDOWN,
+                                        Plan.callFrame(), MachineInstrFlag::FrameSetup);
+    if (!Down)
+      return std::unexpected(Down.error());
+  }
+
+  auto Replacements = emitByValCopies(Builder, Plan);
+  if (!Replacements)
+    return std::unexpected(Replacements.error());
+  auto Arguments = emitOutgoingArguments(Builder, Plan, *Replacements);
+  if (!Arguments)
+    return std::unexpected(Arguments.error());
+  auto Call = emitCallInstruction(Builder, Plan);
+  if (!Call)
+    return std::unexpected(Call.error());
+
+  if (Plan.callFrame().EmitDestroy) {
+    auto Up = emitCallFrameAdjustment(Builder, InstructionOpcode::ADJCALLSTACKUP, Plan.callFrame(),
+                                      MachineInstrFlag::FrameDestroy);
+    if (!Up)
+      return std::unexpected(Up.error());
+  }
+  if (Plan.tailDecision() == TailCallKind::NotTail) {
+    for (const CCAssignment &Assignment : Plan.returnAssignments()) {
+      auto Location = requiredLocationRegister(Assignment);
+      if (!Location)
+        return std::unexpected(Location.error());
+      auto Copy = emitCCCopy(Builder, Assignment.OriginalValue, Register::fromPhysical(*Location),
+                             incomingTransform(Assignment));
+      if (!Copy)
+        return std::unexpected(Copy.error());
+    }
+  }
+
+  MachineFrameInfo &Frame = Builder.function().frameInfo();
+  MachineFrameState State = Frame.state();
+  State.HasCalls = true;
+  State.HasTailCall = State.HasTailCall || Plan.tailDecision() != TailCallKind::NotTail;
+  State.AdjustsStack =
+      State.AdjustsStack || (Plan.callFrame().EmitSetup && Plan.callFrame().SizeBytes != 0);
+  State.HasMustTailInVarArgFunc =
+      State.HasMustTailInVarArgFunc ||
+      (Plan.tailDecision() == TailCallKind::MustTail && Plan.varArgs().IsVariadic);
+  if (Plan.tailDecision() == TailCallKind::NotTail) {
+    State.MaxCallFrameSize =
+        std::max(State.MaxCallFrameSize.value_or(0), Plan.callFrame().SizeBytes);
+  }
+  auto AlignmentUpdate = updateMaximumFrameAlignment(State, Plan.callFrame().Align);
+  if (!AlignmentUpdate)
+    return std::unexpected(AlignmentUpdate.error());
+  return Frame.setState(std::move(State));
+}
+
+[[nodiscard]] Expected<void> emitReturn(MachineIRBuilder &Builder, const CallLoweringPlan &Plan) {
+  for (const CCAssignment &Assignment : Plan.returnAssignments()) {
+    auto Location = requiredLocationRegister(Assignment);
+    if (!Location)
+      return std::unexpected(Location.error());
+    auto Copy = emitCCCopy(Builder, Register::fromPhysical(*Location), Assignment.OriginalValue,
+                           outgoingTransform(Assignment));
+    if (!Copy)
+      return std::unexpected(Copy.error());
+  }
+
+  auto Return = Builder.buildInstr(targetOpcode(InstructionOpcode::PseudoRET));
+  if (!Return)
+    return std::unexpected(Return.error());
+  for (const CCAssignment &Assignment : Plan.returnAssignments()) {
+    auto Location = requiredLocationRegister(Assignment);
+    if (!Location)
+      return std::unexpected(Location.error());
+    auto Use = Return->addImplicitUse(Register::fromPhysical(*Location));
+    if (!Use)
+      return std::unexpected(Use.error());
+  }
+  auto Built = Return->build();
+  if (!Built)
+    return std::unexpected(Built.error());
+  return {};
+}
+
+Expected<void> RISCVCallLowering::emitPlan(MachineIRBuilder &Builder,
+                                           const CallLoweringPlan &Plan) const {
+  auto Preflight = preflightPlan(Builder, Plan);
+  if (!Preflight)
+    return std::unexpected(Preflight.error());
+  switch (Plan.kind()) {
+  case CallLoweringPlanKind::FormalArguments:
+    return emitFormalArguments(Builder, Plan);
+  case CallLoweringPlanKind::Call:
+    return emitCall(Builder, Plan);
+  case CallLoweringPlanKind::Return:
+    return emitReturn(Builder, Plan);
+  }
+  return makeUnexpected(ErrorCode::InternalError, "call-lowering plan kind is invalid");
+}
+
+} // namespace
+
+const TargetCallLowering &callLowering() noexcept {
+  static const RISCVCallLowering Lowering;
+  return Lowering;
+}
+
+} // namespace rcc::riscv
diff --git a/backend/unittests/CodeGen/CMakeLists.txt b/backend/unittests/CodeGen/CMakeLists.txt
index ef96358..deb7a75 100644
--- a/backend/unittests/CodeGen/CMakeLists.txt
+++ b/backend/unittests/CodeGen/CMakeLists.txt
@@ -4,6 +4,7 @@ set(
   RCCBackendCodeGenTestSources
   CompilationUnitTest.cpp
   CoreTypesTest.cpp
+  GenericOpcodesTest.cpp
   InstructionDescriptorTest.cpp
   MachineCompilationStatusTest.cpp
   MachineConstantPoolTest.cpp
@@ -14,13 +15,16 @@ set(
   MachineIRAttributesTest.cpp
   MachineIRBuilderTest.cpp
   MachineIRCoreTest.cpp
+  MachineAnalysesTest.cpp
   MachineJumpTableInfoTest.cpp
   MachineMetadataTest.cpp
   MachineOperandTest.cpp
+  MachinePassTest.cpp
   MachineVerifierTest.cpp
   MachineVerifierTargetTest.cpp
   MachineValueTypesTest.cpp
   TargetConstantTest.cpp
+  TargetCallLoweringTest.cpp
   TargetFunctionStateTest.cpp
   TargetMIRTextInfoTest.cpp
   TargetRegisterInfoTest.cpp
@@ -41,6 +45,12 @@ target_link_libraries(RCCBackendCodeGenCoreTypesTests PRIVATE RCCBackend::CodeGe
 
 add_test(NAME RCCBackend.CodeGen.CoreTypes COMMAND RCCBackendCodeGenCoreTypesTests)
 
+add_executable(RCCBackendCodeGenGenericOpcodesTests GenericOpcodesTest.cpp)
+rcc_backend_configure_target(RCCBackendCodeGenGenericOpcodesTests)
+target_link_libraries(RCCBackendCodeGenGenericOpcodesTests PRIVATE RCCBackend::CodeGen)
+
+add_test(NAME RCCBackend.CodeGen.GenericOpcodes COMMAND RCCBackendCodeGenGenericOpcodesTests)
+
 add_executable(
   RCCBackendCodeGenInstructionDescriptorTests
   InstructionDescriptorTest.cpp
@@ -233,6 +243,24 @@ add_test(
   COMMAND RCCBackendCodeGenMachineOperandTests
 )
 
+add_executable(RCCBackendCodeGenMachinePassTests MachinePassTest.cpp)
+rcc_backend_configure_target(RCCBackendCodeGenMachinePassTests)
+target_link_libraries(
+  RCCBackendCodeGenMachinePassTests
+  PRIVATE RCCBackend::CodeGen RCCBackend::TestTarget
+)
+
+add_test(NAME RCCBackend.CodeGen.MachinePass COMMAND RCCBackendCodeGenMachinePassTests)
+
+add_executable(RCCBackendCodeGenMachineAnalysesTests MachineAnalysesTest.cpp)
+rcc_backend_configure_target(RCCBackendCodeGenMachineAnalysesTests)
+target_link_libraries(
+  RCCBackendCodeGenMachineAnalysesTests
+  PRIVATE RCCBackend::CodeGen RCCBackend::TestTarget
+)
+
+add_test(NAME RCCBackend.CodeGen.MachineAnalyses COMMAND RCCBackendCodeGenMachineAnalysesTests)
+
 add_executable(RCCBackendCodeGenTargetConstantTests TargetConstantTest.cpp)
 rcc_backend_configure_target(RCCBackendCodeGenTargetConstantTests)
 target_link_libraries(RCCBackendCodeGenTargetConstantTests PRIVATE RCCBackend::CodeGen)
@@ -242,6 +270,18 @@ add_test(
   COMMAND RCCBackendCodeGenTargetConstantTests
 )
 
+add_executable(RCCBackendCodeGenTargetCallLoweringTests TargetCallLoweringTest.cpp)
+rcc_backend_configure_target(RCCBackendCodeGenTargetCallLoweringTests)
+target_link_libraries(
+  RCCBackendCodeGenTargetCallLoweringTests
+  PRIVATE RCCBackend::CodeGen RCCBackend::TestTarget
+)
+
+add_test(
+  NAME RCCBackend.CodeGen.TargetCallLowering
+  COMMAND RCCBackendCodeGenTargetCallLoweringTests
+)
+
 add_executable(RCCBackendCodeGenTargetFunctionStateTests TargetFunctionStateTest.cpp)
 rcc_backend_configure_target(RCCBackendCodeGenTargetFunctionStateTests)
 target_link_libraries(
@@ -281,6 +321,7 @@ add_test(
 rcc_backend_register_format_files(
   "${CMAKE_CURRENT_SOURCE_DIR}/CompilationUnitTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/CoreTypesTest.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/GenericOpcodesTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/InstructionDescriptorTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineCompilationStatusTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineConstantPoolTest.cpp"
@@ -291,13 +332,16 @@ rcc_backend_register_format_files(
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineIRAttributesTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineIRBuilderTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineIRCoreTest.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/MachineAnalysesTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineJumpTableInfoTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineMetadataTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineOperandTest.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/MachinePassTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineVerifierTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineVerifierTargetTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineValueTypesTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/TargetConstantTest.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/TargetCallLoweringTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/TargetFunctionStateTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/TargetMIRTextInfoTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/TargetRegisterInfoTest.cpp"
@@ -305,6 +349,7 @@ rcc_backend_register_format_files(
 rcc_backend_register_tidy_files(
   "${CMAKE_CURRENT_SOURCE_DIR}/CompilationUnitTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/CoreTypesTest.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/GenericOpcodesTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/InstructionDescriptorTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineCompilationStatusTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineConstantPoolTest.cpp"
@@ -315,13 +360,16 @@ rcc_backend_register_tidy_files(
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineIRAttributesTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineIRBuilderTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineIRCoreTest.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/MachineAnalysesTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineJumpTableInfoTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineMetadataTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineOperandTest.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/MachinePassTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineVerifierTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineVerifierTargetTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineValueTypesTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/TargetConstantTest.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/TargetCallLoweringTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/TargetFunctionStateTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/TargetMIRTextInfoTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/TargetRegisterInfoTest.cpp"
diff --git a/backend/unittests/CodeGen/GenericOpcodesTest.cpp b/backend/unittests/CodeGen/GenericOpcodesTest.cpp
new file mode 100644
index 0000000..36cc6ca
--- /dev/null
+++ b/backend/unittests/CodeGen/GenericOpcodesTest.cpp
@@ -0,0 +1,701 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "rcc/CodeGen/GenericOpcodes.h"
+
+#include "rcc/CodeGen/MachineBasicBlock.h"
+#include "rcc/CodeGen/MachineFunction.h"
+#include "rcc/CodeGen/MachineInstr.h"
+#include "rcc/CodeGen/MachineMemOperand.h"
+
+#include <array>
+#include <bit>
+#include <cstddef>
+#include <cstdint>
+#include <iostream>
+#include <ranges>
+#include <span>
+#include <string>
+#include <string_view>
+#include <unordered_set>
+#include <utility>
+#include <vector>
+
+namespace {
+
+class TestContext final {
+public:
+  void expect(bool Condition, std::string_view Message) {
+    if (Condition)
+      return;
+    std::cerr << Message << '\n';
+    ++Failures;
+  }
+
+  [[nodiscard]] int result() const noexcept {
+    return Failures == 0 ? 0 : 1;
+  }
+
+private:
+  int Failures = 0;
+};
+
+[[nodiscard]] std::vector<rcc::InstructionDescriptor> copyDescriptors() {
+  const auto Source = rcc::genericInstructionDescriptors();
+  return {Source.begin(), Source.end()};
+}
+
+[[nodiscard]] rcc::MachineOperand registerOperand(rcc::Register Reg, bool IsDef) {
+  rcc::RegisterOperandFlags Flags;
+  Flags.set(IsDef ? rcc::RegisterOperandFlag::Define : rcc::RegisterOperandFlag::Use);
+  auto Operand = rcc::MachineOperand::registerOperand(Reg, Flags);
+  if (!Operand)
+    std::terminate();
+  return std::move(*Operand);
+}
+
+[[nodiscard]] rcc::Register createVirtualRegister(rcc::MachineFunction &Function, rcc::LLT Type) {
+  auto Reg = Function.registerInfo().createVirtualRegister(Type);
+  if (!Reg)
+    std::terminate();
+  return *Reg;
+}
+
+[[nodiscard]] rcc::MachineInstr &createInstruction(rcc::MachineFunction &Function,
+                                                   rcc::GenericOpcode OpcodeValue,
+                                                   std::vector<rcc::MachineOperand> Operands) {
+  auto Instruction = Function.createInstruction(rcc::opcode(OpcodeValue));
+  if (!Instruction)
+    std::terminate();
+  for (rcc::MachineOperand &Operand : Operands) {
+    if (!(*Instruction)->addOperand(std::move(Operand)))
+      std::terminate();
+  }
+  return **Instruction;
+}
+
+[[nodiscard]] rcc::MachineMemOperandDesc
+memoryDescription(rcc::MemoryAccessFlags Accesses, std::uint64_t Bytes,
+                  std::uint32_t AddressSpace = 0,
+                  rcc::AtomicOperation AtomicKind = rcc::AtomicOperation::None) {
+  rcc::MachineMemOperandDesc Description;
+  Description.Accesses = Accesses;
+  Description.AtomicKind = AtomicKind;
+  if (AtomicKind == rcc::AtomicOperation::ReadModifyWrite) {
+    Description.SuccessOrdering = rcc::AtomicOrdering::AcquireRelease;
+  } else if (AtomicKind == rcc::AtomicOperation::CompareExchange) {
+    Description.SuccessOrdering = rcc::AtomicOrdering::AcquireRelease;
+    Description.FailureOrdering = rcc::AtomicOrdering::Acquire;
+  }
+  Description.Size = *rcc::MemorySize::fixed(Bytes);
+  Description.Align = *rcc::Alignment::create(std::bit_floor(Bytes));
+  Description.AddressSpace = AddressSpace;
+  Description.Base = rcc::MemoryBase::stack();
+  return Description;
+}
+
+void addMemOperand(rcc::MachineFunction &Function, rcc::MachineInstr &Instruction,
+                   rcc::MachineMemOperandDesc Description) {
+  auto Memory = Function.createMemOperand(std::move(Description));
+  if (!Memory || !Instruction.addMemOperand(**Memory))
+    std::terminate();
+}
+
+void testCompleteRegistry(TestContext &Context) {
+  static_assert(rcc::CorePseudoOpcodeCount == 52);
+  static_assert(rcc::GenericOpcodeCount == 278);
+
+  const auto Descriptors = rcc::genericInstructionDescriptors();
+  Context.expect(Descriptors.size() == 330,
+                 "the target-independent registry must contain 52 core and 278 generic opcodes");
+
+  std::unordered_set<std::string> Names;
+  std::unordered_set<rcc::Opcode> Opcodes;
+  bool ClassesAreCorrect = true;
+  for (const rcc::InstructionDescriptor &Descriptor : Descriptors) {
+    ClassesAreCorrect &= Descriptor.InstructionOpcode.isValid() && !Descriptor.Name.empty() &&
+                         Names.insert(Descriptor.Name).second &&
+                         Opcodes.insert(Descriptor.InstructionOpcode).second;
+    if (rcc::isGenericOpcode(Descriptor.InstructionOpcode)) {
+      ClassesAreCorrect &= Descriptor.Flags.has(rcc::InstructionFlag::Generic) &&
+                           !Descriptor.Flags.has(rcc::InstructionFlag::Pseudo);
+    } else {
+      ClassesAreCorrect &= rcc::isCorePseudoOpcode(Descriptor.InstructionOpcode) &&
+                           Descriptor.Flags.has(rcc::InstructionFlag::Pseudo) &&
+                           !Descriptor.Flags.has(rcc::InstructionFlag::Generic);
+    }
+  }
+  Context.expect(ClassesAreCorrect,
+                 "every target-independent opcode must have one valid name, value, and class");
+  Context.expect(rcc::getGenericOpcodeName(rcc::GenericOpcode::PHI) == "PHI" &&
+                     rcc::getGenericOpcodeName(rcc::GenericOpcode::G_ASSERT_SEXT) ==
+                         "G_ASSERT_SEXT" &&
+                     rcc::getGenericOpcodeName(rcc::GenericOpcode::G_UBFX) == "G_UBFX" &&
+                     rcc::getGenericOpcodeName(rcc::GenericOpcode::Invalid).empty(),
+                 "opcode names must cover both ranges without assigning marker names");
+
+  auto Set = rcc::InstructionSet::create(copyDescriptors());
+  Context.expect(Set.has_value(), "the complete target-independent descriptor set must validate");
+}
+
+void testCoreOpcodeContracts(TestContext &Context) {
+  struct Contract final {
+    rcc::GenericOpcode OpcodeValue;
+    std::size_t DescriptorOperands;
+    std::size_t ExplicitDefs;
+    bool Variadic;
+    std::size_t MinimumRepetitions;
+    bool Meta;
+    bool TerminalEmission;
+    rcc::PseudoOwner Owner;
+    rcc::PipelineStage Deadline;
+  };
+
+#define RCC_META(Name, Operands, Defs, Variadic, Minimum)                                          \
+  Contract{rcc::GenericOpcode::Name,                                                               \
+           Operands,                                                                               \
+           Defs,                                                                                   \
+           Variadic,                                                                               \
+           Minimum,                                                                                \
+           true,                                                                                   \
+           false,                                                                                  \
+           rcc::PseudoOwner::None,                                                                 \
+           rcc::PipelineStage::Emission}
+#define RCC_PSEUDO(Name, Operands, Defs, Variadic, Minimum, Owner, Deadline)                       \
+  Contract{rcc::GenericOpcode::Name,                                                               \
+           Operands,                                                                               \
+           Defs,                                                                                   \
+           Variadic,                                                                               \
+           Minimum,                                                                                \
+           false,                                                                                  \
+           false,                                                                                  \
+           rcc::PseudoOwner::Owner,                                                                \
+           rcc::PipelineStage::Deadline}
+#define RCC_TERMINAL(Name, Operands, Defs, Variadic, Minimum)                                      \
+  Contract {                                                                                       \
+    rcc::GenericOpcode::Name, Operands, Defs, Variadic, Minimum, false, true,                      \
+        rcc::PseudoOwner::AsmPrinter, rcc::PipelineStage::Emission                                 \
+  }
+
+  const std::array Contracts{
+      RCC_PSEUDO(PHI, 3, 1, true, 1, PhiElimination, SSAEliminated),
+      RCC_TERMINAL(INLINEASM, 1, 0, true, 0),
+      RCC_TERMINAL(INLINEASM_BR, 1, 0, true, 0),
+      RCC_META(CFI_INSTRUCTION, 1, 0, false, 0),
+      RCC_META(EH_LABEL, 1, 0, false, 0),
+      RCC_META(GC_LABEL, 1, 0, false, 0),
+      RCC_META(ANNOTATION_LABEL, 1, 0, false, 0),
+      RCC_META(KILL, 1, 0, true, 0),
+      RCC_PSEUDO(EXTRACT_SUBREG, 3, 1, false, 0, PostRAExpansion, PostRAFinalized),
+      RCC_PSEUDO(INSERT_SUBREG, 4, 1, false, 0, TwoAddressRewrite, TiedOpsRewritten),
+      RCC_META(IMPLICIT_DEF, 1, 1, false, 0),
+      RCC_PSEUDO(INIT_UNDEF, 1, 1, false, 0, RegisterAllocator, RegisterAllocated),
+      RCC_PSEUDO(SUBREG_TO_REG, 3, 1, false, 0, PostRAExpansion, PostRAFinalized),
+      RCC_PSEUDO(COPY_TO_REGCLASS, 3, 1, false, 0, RegisterAllocator, RegisterAllocated),
+      RCC_META(DBG_VALUE, 1, 0, true, 0),
+      RCC_META(DBG_VALUE_LIST, 1, 0, true, 0),
+      RCC_META(DBG_INSTR_REF, 1, 0, true, 0),
+      RCC_META(DBG_PHI, 1, 0, true, 0),
+      RCC_META(DBG_LABEL, 1, 0, false, 0),
+      RCC_PSEUDO(REG_SEQUENCE, 3, 1, true, 1, TwoAddressRewrite, TiedOpsRewritten),
+      RCC_PSEUDO(COPY, 2, 1, false, 0, PostRAExpansion, PostRAFinalized),
+      RCC_PSEUDO(COPY_LANEMASK, 3, 1, false, 0, PostRAExpansion, PostRAFinalized),
+      RCC_META(BUNDLE, 1, 0, true, 0),
+      RCC_META(LIFETIME_START, 1, 0, false, 0),
+      RCC_META(LIFETIME_END, 1, 0, false, 0),
+      RCC_META(PSEUDO_PROBE, 4, 0, false, 0),
+      RCC_META(ARITH_FENCE, 2, 1, false, 0),
+      RCC_TERMINAL(STACKMAP, 3, 0, true, 0),
+      RCC_TERMINAL(FENTRY_CALL, 0, 0, false, 0),
+      RCC_TERMINAL(PATCHPOINT, 7, 1, true, 0),
+      RCC_PSEUDO(LOAD_STACK_GUARD, 1, 1, false, 0, InstructionSelect, Selected),
+      RCC_PSEUDO(PREALLOCATED_SETUP, 1, 0, false, 0, InstructionSelect, Selected),
+      RCC_PSEUDO(PREALLOCATED_ARG, 3, 1, false, 0, InstructionSelect, Selected),
+      RCC_TERMINAL(STATEPOINT, 1, 0, true, 0),
+      RCC_META(LOCAL_ESCAPE, 2, 0, false, 0),
+      RCC_TERMINAL(FAULTING_OP, 2, 1, true, 0),
+      RCC_TERMINAL(PATCHABLE_OP, 1, 0, true, 0),
+      RCC_TERMINAL(PATCHABLE_FUNCTION_ENTER, 0, 0, false, 0),
+      RCC_TERMINAL(PATCHABLE_RET, 1, 0, true, 0),
+      RCC_TERMINAL(PATCHABLE_FUNCTION_EXIT, 0, 0, false, 0),
+      RCC_TERMINAL(PATCHABLE_TAIL_CALL, 1, 0, true, 0),
+      RCC_TERMINAL(PATCHABLE_EVENT_CALL, 2, 0, false, 0),
+      RCC_TERMINAL(PATCHABLE_TYPED_EVENT_CALL, 3, 0, false, 0),
+      RCC_PSEUDO(ICALL_BRANCH_FUNNEL, 1, 0, true, 0, PostRAExpansion, PostRAFinalized),
+      RCC_META(FAKE_USE, 1, 0, true, 0),
+      RCC_META(MEMBARRIER, 0, 0, false, 0),
+      RCC_META(JUMP_TABLE_DEBUG_INFO, 1, 0, false, 0),
+      RCC_META(RELOC_NONE, 1, 0, false, 0),
+      RCC_META(CONVERGENCECTRL_ENTRY, 1, 1, false, 0),
+      RCC_META(CONVERGENCECTRL_ANCHOR, 1, 1, false, 0),
+      RCC_META(CONVERGENCECTRL_LOOP, 2, 1, false, 0),
+      RCC_META(CONVERGENCECTRL_GLUE, 1, 0, false, 0),
+  };
+#undef RCC_TERMINAL
+#undef RCC_PSEUDO
+#undef RCC_META
+
+  static_assert(Contracts.size() == rcc::CorePseudoOpcodeCount);
+  const auto Descriptors = rcc::genericInstructionDescriptors();
+  bool Matches = true;
+  for (const Contract &Expected : Contracts) {
+    const auto Found = std::ranges::find_if(
+        Descriptors, [&Expected](const rcc::InstructionDescriptor &Descriptor) {
+          return Descriptor.InstructionOpcode == rcc::opcode(Expected.OpcodeValue);
+        });
+    if (Found == Descriptors.end()) {
+      Matches = false;
+      continue;
+    }
+    Matches &=
+        Found->Operands.size() == Expected.DescriptorOperands &&
+        Found->NumExplicitDefs == Expected.ExplicitDefs && Found->Variadic == Expected.Variadic &&
+        Found->MinimumVariadicRepetitions == Expected.MinimumRepetitions &&
+        Found->Flags.has(rcc::InstructionFlag::Meta) == Expected.Meta &&
+        Found->Flags.has(rcc::InstructionFlag::TerminalEmission) == Expected.TerminalEmission &&
+        Found->Owner == Expected.Owner && Found->Deadline == Expected.Deadline;
+  }
+  Context.expect(Matches,
+                 "all 52 core opcodes must retain their reviewed shape and lifecycle contracts");
+
+  const auto InlineAsm = std::ranges::find_if(Descriptors, [](const auto &Descriptor) {
+    return Descriptor.InstructionOpcode == rcc::opcode(rcc::GenericOpcode::INLINEASM);
+  });
+  const auto InlineAsmBr = std::ranges::find_if(Descriptors, [](const auto &Descriptor) {
+    return Descriptor.InstructionOpcode == rcc::opcode(rcc::GenericOpcode::INLINEASM_BR);
+  });
+  Context.expect(InlineAsm != Descriptors.end() && InlineAsmBr != Descriptors.end() &&
+                     !InlineAsm->Flags.has(rcc::InstructionFlag::HasSideEffects) &&
+                     InlineAsmBr->Flags.has(rcc::InstructionFlag::HasSideEffects),
+                 "INLINEASM_BR must be intrinsically side-effecting while INLINEASM uses its "
+                 "operand flags");
+}
+
+void testShapesAndTypes(TestContext &Context) {
+  auto Set = rcc::InstructionSet::create(copyDescriptors());
+  auto Function =
+      rcc::MachineFunction::create("generic", rcc::MachineFunctionStableID::fromValue(1));
+  Context.expect(Set.has_value() && Function.has_value(),
+                 "generic opcode tests require a descriptor set and machine function");
+  if (!Set || !Function)
+    return;
+
+  auto I32 = rcc::LLT::makeInteger(32);
+  auto I64 = rcc::LLT::makeInteger(64);
+  auto I1 = rcc::LLT::makeInteger(1);
+  auto F32 = rcc::LLT::makeFloat(rcc::FloatSemantics::IEEESingle);
+  auto F64 = rcc::LLT::makeFloat(rcc::FloatSemantics::IEEEDouble);
+  auto P64 = rcc::LLT::makePointer(0, 64);
+  auto V2I32 = I32 ? rcc::LLT::makeFixedVector(2, *I32) : rcc::Expected<rcc::LLT>{};
+  auto V4I32 = I32 ? rcc::LLT::makeFixedVector(4, *I32) : rcc::Expected<rcc::LLT>{};
+  auto V2P64 = P64 ? rcc::LLT::makeFixedVector(2, *P64) : rcc::Expected<rcc::LLT>{};
+  if (!I1 || !I32 || !I64 || !F32 || !F64 || !P64 || !V2I32 || !V4I32 || !V2P64)
+    std::terminate();
+  auto Dst32 = (*Function)->registerInfo().createVirtualRegister(*I32);
+  auto Src32A = (*Function)->registerInfo().createVirtualRegister(*I32);
+  auto Src32B = (*Function)->registerInfo().createVirtualRegister(*I32);
+  auto Wide = (*Function)->registerInfo().createVirtualRegister(*I64);
+  auto Address = (*Function)->registerInfo().createVirtualRegister(*P64);
+  auto NewAddress = (*Function)->registerInfo().createVirtualRegister(*P64);
+  const rcc::Register Cond = createVirtualRegister(**Function, *I1);
+  const rcc::Register Float32 = createVirtualRegister(**Function, *F32);
+  const rcc::Register Float64 = createVirtualRegister(**Function, *F64);
+  const rcc::Register Vec2A = createVirtualRegister(**Function, *V2I32);
+  const rcc::Register Vec2B = createVirtualRegister(**Function, *V2I32);
+  const rcc::Register Vec4 = createVirtualRegister(**Function, *V4I32);
+  const rcc::Register PointerVector = createVirtualRegister(**Function, *V2P64);
+  if (!Dst32 || !Src32A || !Src32B || !Wide || !Address || !NewAddress)
+    std::terminate();
+
+  std::vector<rcc::MachineOperand> AddOperands;
+  AddOperands.push_back(registerOperand(*Dst32, true));
+  AddOperands.push_back(registerOperand(*Src32A, false));
+  AddOperands.push_back(registerOperand(*Src32B, false));
+  Context.expect(Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_ADD), AddOperands,
+                                               (*Function)->registerInfo())
+                     .has_value(),
+                 "same-typed integer operands must satisfy G_ADD");
+  AddOperands.back() = registerOperand(*Wide, false);
+  Context.expect(!Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_ADD), AddOperands,
+                                                (*Function)->registerInfo()),
+                 "G_ADD must reject a source from a different LLT equality group");
+
+  auto Block0 = (*Function)->createBasicBlock();
+  auto Block1 = (*Function)->createBasicBlock();
+  if (!Block0 || !Block1 || !(*Function)->appendBlock(**Block0) ||
+      !(*Function)->appendBlock(**Block1)) {
+    std::terminate();
+  }
+  std::vector<rcc::MachineOperand> PhiOperands;
+  PhiOperands.push_back(registerOperand(*Dst32, true));
+  Context.expect(!Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_PHI), PhiOperands,
+                                                (*Function)->registerInfo()),
+                 "G_PHI must require at least one value and predecessor pair");
+  PhiOperands.push_back(registerOperand(*Src32A, false));
+  PhiOperands.push_back(rcc::MachineOperand::basicBlock(**Block0));
+  PhiOperands.push_back(registerOperand(*Src32B, false));
+  PhiOperands.push_back(rcc::MachineOperand::basicBlock(**Block1));
+  Context.expect(Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_PHI), PhiOperands,
+                                               (*Function)->registerInfo())
+                     .has_value(),
+                 "G_PHI must accept repeated value and predecessor pairs");
+  PhiOperands.pop_back();
+  Context.expect(!Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_PHI), PhiOperands,
+                                                (*Function)->registerInfo()),
+                 "G_PHI must reject an incomplete variadic operand pair");
+
+  std::vector<rcc::MachineOperand> IndexedLoad;
+  IndexedLoad.push_back(registerOperand(*Dst32, true));
+  IndexedLoad.push_back(registerOperand(*NewAddress, true));
+  IndexedLoad.push_back(registerOperand(*Address, false));
+  IndexedLoad.push_back(registerOperand(*Wide, false));
+  IndexedLoad.push_back(rcc::MachineOperand::immediate(1));
+  Context.expect(Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_INDEXED_LOAD),
+                                               IndexedLoad, (*Function)->registerInfo())
+                     .has_value(),
+                 "indexed loads must keep address and integer offset type groups independent");
+
+  std::vector<rcc::MachineOperand> UnmergeOperands;
+  UnmergeOperands.push_back(registerOperand(*Dst32, true));
+  UnmergeOperands.push_back(registerOperand(*Wide, false));
+  Context.expect(!Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_UNMERGE_VALUES),
+                                                UnmergeOperands, (*Function)->registerInfo()),
+                 "G_UNMERGE_VALUES must require at least two definitions");
+  UnmergeOperands.insert(UnmergeOperands.begin() + 1, registerOperand(*Src32B, true));
+  Context.expect(Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_UNMERGE_VALUES),
+                                               UnmergeOperands, (*Function)->registerInfo())
+                     .has_value(),
+                 "two homogeneous halves must exactly cover a G_UNMERGE_VALUES source");
+
+  std::vector<rcc::MachineOperand> MergeOperands;
+  MergeOperands.push_back(registerOperand(*Wide, true));
+  MergeOperands.push_back(registerOperand(*Src32A, false));
+  Context.expect(!Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_MERGE_VALUES),
+                                                MergeOperands, (*Function)->registerInfo()),
+                 "G_MERGE_VALUES must require at least two sources");
+  MergeOperands.push_back(registerOperand(*Src32B, false));
+  Context.expect(Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_MERGE_VALUES),
+                                               MergeOperands, (*Function)->registerInfo())
+                     .has_value(),
+                 "two homogeneous sources must exactly fill a G_MERGE_VALUES result");
+
+  std::vector<rcc::MachineOperand> ConcatOperands;
+  ConcatOperands.push_back(registerOperand(Vec4, true));
+  ConcatOperands.push_back(registerOperand(Vec2A, false));
+  Context.expect(!Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_CONCAT_VECTORS),
+                                                ConcatOperands, (*Function)->registerInfo()),
+                 "G_CONCAT_VECTORS must require at least two source vectors");
+  ConcatOperands.push_back(registerOperand(Vec2B, false));
+  Context.expect(Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_CONCAT_VECTORS),
+                                               ConcatOperands, (*Function)->registerInfo())
+                     .has_value(),
+                 "two vector sources must exactly tile a G_CONCAT_VECTORS result");
+
+  std::vector<rcc::MachineOperand> FrameIndexOperands;
+  FrameIndexOperands.push_back(registerOperand(PointerVector, true));
+  FrameIndexOperands.push_back(rcc::MachineOperand::frameIndex(rcc::FrameIndex::fromValue(0)));
+  Context.expect(!Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_FRAME_INDEX),
+                                                FrameIndexOperands, (*Function)->registerInfo()),
+                 "G_FRAME_INDEX must reject a vector-of-pointers result");
+
+  std::vector<rcc::MachineOperand> PtrAuthOperands;
+  PtrAuthOperands.push_back(registerOperand(*NewAddress, true));
+  PtrAuthOperands.push_back(registerOperand(*Address, false));
+  PtrAuthOperands.push_back(rcc::MachineOperand::immediate(0));
+  PtrAuthOperands.push_back(registerOperand(*Wide, false));
+  PtrAuthOperands.push_back(rcc::MachineOperand::immediate(7));
+  Context.expect(
+      Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_PTRAUTH_GLOBAL_VALUE),
+                                    PtrAuthOperands, (*Function)->registerInfo())
+          .has_value(),
+      "G_PTRAUTH_GLOBAL_VALUE must accept pointer and discriminator registers");
+  auto Symbol = rcc::MachineOperand::globalSymbol("global");
+  if (!Symbol)
+    std::terminate();
+  PtrAuthOperands[1] = std::move(*Symbol);
+  Context.expect(
+      !Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_PTRAUTH_GLOBAL_VALUE),
+                                     PtrAuthOperands, (*Function)->registerInfo()),
+      "G_PTRAUTH_GLOBAL_VALUE must reject a symbol in place of its address register");
+
+  std::vector<rcc::MachineOperand> ExtensionOperands;
+  ExtensionOperands.push_back(registerOperand(*Wide, true));
+  ExtensionOperands.push_back(registerOperand(*Src32A, false));
+  Context.expect(Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_ZEXT),
+                                               ExtensionOperands, (*Function)->registerInfo())
+                     .has_value(),
+                 "G_ZEXT must accept a wider destination with matching shape");
+  ExtensionOperands[0] = registerOperand(*Dst32, true);
+  ExtensionOperands[1] = registerOperand(*Wide, false);
+  Context.expect(!Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_ZEXT),
+                                                ExtensionOperands, (*Function)->registerInfo()),
+                 "G_ZEXT must reject a narrower destination");
+
+  auto Predicate = rcc::MachineOperand::integerPredicate(rcc::IntegerPredicate::Equal);
+  if (!Predicate)
+    std::terminate();
+  std::vector<rcc::MachineOperand> CompareOperands;
+  CompareOperands.push_back(registerOperand(Cond, true));
+  CompareOperands.push_back(std::move(*Predicate));
+  CompareOperands.push_back(registerOperand(*Src32A, false));
+  CompareOperands.push_back(registerOperand(*Src32B, false));
+  Context.expect(Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_ICMP),
+                                               CompareOperands, (*Function)->registerInfo())
+                     .has_value(),
+                 "G_ICMP must accept an i1 result and homogeneous integer sources");
+  CompareOperands[0] = registerOperand(*Dst32, true);
+  Context.expect(!Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_ICMP),
+                                                CompareOperands, (*Function)->registerInfo()),
+                 "G_ICMP must reject a non-i1 result");
+
+  std::vector<rcc::MachineOperand> FloatingLoad;
+  FloatingLoad.push_back(registerOperand(Float64, true));
+  FloatingLoad.push_back(registerOperand(*Address, false));
+  Context.expect(Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_FPEXTLOAD),
+                                               FloatingLoad, (*Function)->registerInfo())
+                     .has_value(),
+                 "G_FPEXTLOAD must accept a scalar floating result and pointer address");
+  FloatingLoad[0] = registerOperand(*Wide, true);
+  Context.expect(!Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_FPEXTLOAD),
+                                                FloatingLoad, (*Function)->registerInfo()),
+                 "G_FPEXTLOAD must reject an integer result");
+
+  const std::array<std::uint64_t, 1> FloatWords{0};
+  auto FloatBits = rcc::FloatingPointBits::create(rcc::FloatSemantics::IEEESingle, FloatWords);
+  if (!FloatBits)
+    std::terminate();
+  std::vector<rcc::MachineOperand> FConstantOperands;
+  FConstantOperands.push_back(registerOperand(Float32, true));
+  FConstantOperands.push_back(rcc::MachineOperand::floatingImmediate(*FloatBits));
+  Context.expect(Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_FCONSTANT),
+                                               FConstantOperands, (*Function)->registerInfo())
+                     .has_value(),
+                 "G_FCONSTANT payload semantics must match its scalar destination");
+  FConstantOperands[0] = registerOperand(Float64, true);
+  Context.expect(!Set->validateExplicitOperands(rcc::opcode(rcc::GenericOpcode::G_FCONSTANT),
+                                                FConstantOperands, (*Function)->registerInfo()),
+                 "G_FCONSTANT must reject mismatched floating semantics");
+}
+
+void testInstructionMemorySemantics(TestContext &Context) {
+  auto Set = rcc::InstructionSet::create(copyDescriptors());
+  auto Function =
+      rcc::MachineFunction::create("generic_memory", rcc::MachineFunctionStableID::fromValue(2));
+  Context.expect(Set && Function, "generic memory tests require an instruction set and function");
+  if (!Set || !Function)
+    return;
+
+  const rcc::LLT I1 = *rcc::LLT::makeInteger(1);
+  const rcc::LLT I32 = *rcc::LLT::makeInteger(32);
+  const rcc::LLT I64 = *rcc::LLT::makeInteger(64);
+  const rcc::LLT F64 = *rcc::LLT::makeFloat(rcc::FloatSemantics::IEEEDouble);
+  const rcc::LLT P0 = *rcc::LLT::makePointer(0, 64);
+  const rcc::LLT P1 = *rcc::LLT::makePointer(1, 64);
+  const rcc::Register Dst32 = createVirtualRegister(**Function, I32);
+  const rcc::Register Dst64 = createVirtualRegister(**Function, I64);
+  const rcc::Register Src64 = createVirtualRegister(**Function, I64);
+  const rcc::Register Float64 = createVirtualRegister(**Function, F64);
+  const rcc::Register Status = createVirtualRegister(**Function, I1);
+  const rcc::Register Address0 = createVirtualRegister(**Function, P0);
+  const rcc::Register Address1 = createVirtualRegister(**Function, P1);
+
+  std::vector<rcc::MachineOperand> LoadOperands;
+  LoadOperands.push_back(registerOperand(Dst64, true));
+  LoadOperands.push_back(registerOperand(Address0, false));
+  rcc::MachineInstr &Load =
+      createInstruction(**Function, rcc::GenericOpcode::G_LOAD, std::move(LoadOperands));
+  addMemOperand(**Function, Load, memoryDescription({rcc::MemoryAccessFlag::Load}, 8));
+  Context.expect(Set->validateInstruction(Load, (*Function)->registerInfo()).has_value(),
+                 "G_LOAD must accept one matching load MMO");
+
+  std::vector<rcc::MachineOperand> OversizedLoadOperands;
+  OversizedLoadOperands.push_back(registerOperand(Dst32, true));
+  OversizedLoadOperands.push_back(registerOperand(Address0, false));
+  rcc::MachineInstr &OversizedLoad =
+      createInstruction(**Function, rcc::GenericOpcode::G_LOAD, std::move(OversizedLoadOperands));
+  addMemOperand(**Function, OversizedLoad, memoryDescription({rcc::MemoryAccessFlag::Load}, 8));
+  Context.expect(!Set->validateInstruction(OversizedLoad, (*Function)->registerInfo()),
+                 "G_LOAD must reject an MMO larger than its result LLT");
+
+  std::vector<rcc::MachineOperand> WrongAddressSpaceOperands;
+  WrongAddressSpaceOperands.push_back(registerOperand(Dst64, true));
+  WrongAddressSpaceOperands.push_back(registerOperand(Address1, false));
+  rcc::MachineInstr &WrongAddressSpace = createInstruction(**Function, rcc::GenericOpcode::G_LOAD,
+                                                           std::move(WrongAddressSpaceOperands));
+  addMemOperand(**Function, WrongAddressSpace,
+                memoryDescription({rcc::MemoryAccessFlag::Load}, 8, 0));
+  Context.expect(!Set->validateInstruction(WrongAddressSpace, (*Function)->registerInfo()),
+                 "generic memory access must match its pointer and MMO address spaces");
+
+  std::vector<rcc::MachineOperand> ExtLoadOperands;
+  ExtLoadOperands.push_back(registerOperand(Dst64, true));
+  ExtLoadOperands.push_back(registerOperand(Address0, false));
+  rcc::MachineInstr &ExtLoad =
+      createInstruction(**Function, rcc::GenericOpcode::G_ZEXTLOAD, std::move(ExtLoadOperands));
+  addMemOperand(**Function, ExtLoad, memoryDescription({rcc::MemoryAccessFlag::Load}, 4));
+  Context.expect(Set->validateInstruction(ExtLoad, (*Function)->registerInfo()).has_value(),
+                 "G_ZEXTLOAD must accept a strictly narrower memory access");
+
+  std::vector<rcc::MachineOperand> NonExtendingLoadOperands;
+  NonExtendingLoadOperands.push_back(registerOperand(Dst64, true));
+  NonExtendingLoadOperands.push_back(registerOperand(Address0, false));
+  rcc::MachineInstr &NonExtendingLoad = createInstruction(
+      **Function, rcc::GenericOpcode::G_ZEXTLOAD, std::move(NonExtendingLoadOperands));
+  addMemOperand(**Function, NonExtendingLoad, memoryDescription({rcc::MemoryAccessFlag::Load}, 8));
+  Context.expect(!Set->validateInstruction(NonExtendingLoad, (*Function)->registerInfo()),
+                 "G_ZEXTLOAD must reject a non-narrowing MMO");
+
+  std::vector<rcc::MachineOperand> CompareExchangeOperands;
+  CompareExchangeOperands.push_back(registerOperand(Dst64, true));
+  CompareExchangeOperands.push_back(registerOperand(Status, true));
+  CompareExchangeOperands.push_back(registerOperand(Address0, false));
+  CompareExchangeOperands.push_back(registerOperand(Src64, false));
+  CompareExchangeOperands.push_back(registerOperand(Src64, false));
+  rcc::MachineInstr &CompareExchange =
+      createInstruction(**Function, rcc::GenericOpcode::G_ATOMIC_CMPXCHG_WITH_SUCCESS,
+                        std::move(CompareExchangeOperands));
+  addMemOperand(**Function, CompareExchange,
+                memoryDescription({rcc::MemoryAccessFlag::Load, rcc::MemoryAccessFlag::Store}, 8, 0,
+                                  rcc::AtomicOperation::CompareExchange));
+  Context.expect(Set->validateInstruction(CompareExchange, (*Function)->registerInfo()).has_value(),
+                 "generic compare-exchange must accept a matching atomic MMO");
+
+  std::vector<rcc::MachineOperand> WrongAtomicOperands;
+  WrongAtomicOperands.push_back(registerOperand(Dst64, true));
+  WrongAtomicOperands.push_back(registerOperand(Address0, false));
+  WrongAtomicOperands.push_back(registerOperand(Src64, false));
+  rcc::MachineInstr &WrongAtomic = createInstruction(
+      **Function, rcc::GenericOpcode::G_ATOMICRMW_ADD, std::move(WrongAtomicOperands));
+  addMemOperand(**Function, WrongAtomic,
+                memoryDescription({rcc::MemoryAccessFlag::Load, rcc::MemoryAccessFlag::Store}, 8, 0,
+                                  rcc::AtomicOperation::CompareExchange));
+  Context.expect(!Set->validateInstruction(WrongAtomic, (*Function)->registerInfo()),
+                 "generic atomic RMW must reject a compare-exchange MMO");
+
+  std::vector<rcc::MachineOperand> FloatingAtomicOperands;
+  FloatingAtomicOperands.push_back(registerOperand(Float64, true));
+  FloatingAtomicOperands.push_back(registerOperand(Address0, false));
+  FloatingAtomicOperands.push_back(registerOperand(Float64, false));
+  rcc::MachineInstr &FloatingAtomic = createInstruction(
+      **Function, rcc::GenericOpcode::G_ATOMICRMW_FADD, std::move(FloatingAtomicOperands));
+  addMemOperand(**Function, FloatingAtomic,
+                memoryDescription({rcc::MemoryAccessFlag::Load, rcc::MemoryAccessFlag::Store}, 8, 0,
+                                  rcc::AtomicOperation::ReadModifyWrite));
+  Context.expect(Set->validateInstruction(FloatingAtomic, (*Function)->registerInfo()).has_value(),
+                 "floating atomic RMW must accept a scalar floating value and RMW MMO");
+
+  std::vector<rcc::MachineOperand> WrongFloatingAtomicOperands;
+  WrongFloatingAtomicOperands.push_back(registerOperand(Dst64, true));
+  WrongFloatingAtomicOperands.push_back(registerOperand(Address0, false));
+  WrongFloatingAtomicOperands.push_back(registerOperand(Src64, false));
+  rcc::MachineInstr &WrongFloatingAtomic = createInstruction(
+      **Function, rcc::GenericOpcode::G_ATOMICRMW_FADD, std::move(WrongFloatingAtomicOperands));
+  addMemOperand(**Function, WrongFloatingAtomic,
+                memoryDescription({rcc::MemoryAccessFlag::Load, rcc::MemoryAccessFlag::Store}, 8, 0,
+                                  rcc::AtomicOperation::ReadModifyWrite));
+  Context.expect(!Set->validateInstruction(WrongFloatingAtomic, (*Function)->registerInfo()),
+                 "floating atomic RMW must reject integer value registers");
+
+  std::vector<rcc::MachineOperand> PrefetchOperands;
+  PrefetchOperands.push_back(registerOperand(Address0, false));
+  PrefetchOperands.push_back(rcc::MachineOperand::immediate(0));
+  PrefetchOperands.push_back(rcc::MachineOperand::immediate(3));
+  PrefetchOperands.push_back(rcc::MachineOperand::immediate(1));
+  rcc::MachineInstr &Prefetch =
+      createInstruction(**Function, rcc::GenericOpcode::G_PREFETCH, std::move(PrefetchOperands));
+  Context.expect(!Set->validateInstruction(Prefetch, (*Function)->registerInfo()),
+                 "G_PREFETCH must require an MMO");
+  addMemOperand(**Function, Prefetch, memoryDescription({rcc::MemoryAccessFlag::Load}, 1));
+  Context.expect(Set->validateInstruction(Prefetch, (*Function)->registerInfo()).has_value(),
+                 "read-prefetch selector must match a load-only MMO");
+
+  std::vector<rcc::MachineOperand> VarArgOperands;
+  VarArgOperands.push_back(registerOperand(Dst64, true));
+  VarArgOperands.push_back(registerOperand(Address0, false));
+  VarArgOperands.push_back(rcc::MachineOperand::immediate(8));
+  rcc::MachineInstr &VarArg =
+      createInstruction(**Function, rcc::GenericOpcode::G_VAARG, std::move(VarArgOperands));
+  addMemOperand(**Function, VarArg, memoryDescription({rcc::MemoryAccessFlag::Load}, 8));
+  addMemOperand(**Function, VarArg, memoryDescription({rcc::MemoryAccessFlag::Store}, 8));
+  Context.expect(Set->validateInstruction(VarArg, (*Function)->registerInfo()).has_value(),
+                 "G_VAARG must accept separate value-load and list-update MMOs");
+
+  std::vector<rcc::MachineOperand> CombinedVarArgOperands;
+  CombinedVarArgOperands.push_back(registerOperand(Dst64, true));
+  CombinedVarArgOperands.push_back(registerOperand(Address0, false));
+  CombinedVarArgOperands.push_back(rcc::MachineOperand::immediate(8));
+  rcc::MachineInstr &CombinedVarArg =
+      createInstruction(**Function, rcc::GenericOpcode::G_VAARG, std::move(CombinedVarArgOperands));
+  addMemOperand(**Function, CombinedVarArg,
+                memoryDescription({rcc::MemoryAccessFlag::Load, rcc::MemoryAccessFlag::Store}, 8));
+  Context.expect(!Set->validateInstruction(CombinedVarArg, (*Function)->registerInfo()),
+                 "G_VAARG must reject a combined read-write MMO in place of two accesses");
+
+  std::vector<rcc::MachineOperand> MemoryTransferOperands;
+  MemoryTransferOperands.push_back(registerOperand(Address0, false));
+  MemoryTransferOperands.push_back(registerOperand(Address1, false));
+  MemoryTransferOperands.push_back(registerOperand(Src64, false));
+  MemoryTransferOperands.push_back(rcc::MachineOperand::immediate(0));
+  rcc::MachineInstr &MemoryTransfer = createInstruction(**Function, rcc::GenericOpcode::G_MEMCPY,
+                                                        std::move(MemoryTransferOperands));
+  addMemOperand(**Function, MemoryTransfer,
+                memoryDescription({rcc::MemoryAccessFlag::Store}, 8, 0));
+  addMemOperand(**Function, MemoryTransfer, memoryDescription({rcc::MemoryAccessFlag::Load}, 8, 1));
+  Context.expect(Set->validateInstruction(MemoryTransfer, (*Function)->registerInfo()).has_value(),
+                 "G_MEMCPY must accept equal-sized store/load MMOs in canonical order");
+
+  std::vector<rcc::MachineOperand> ReversedTransferOperands;
+  ReversedTransferOperands.push_back(registerOperand(Address0, false));
+  ReversedTransferOperands.push_back(registerOperand(Address1, false));
+  ReversedTransferOperands.push_back(registerOperand(Src64, false));
+  ReversedTransferOperands.push_back(rcc::MachineOperand::immediate(0));
+  rcc::MachineInstr &ReversedTransfer = createInstruction(**Function, rcc::GenericOpcode::G_MEMCPY,
+                                                          std::move(ReversedTransferOperands));
+  addMemOperand(**Function, ReversedTransfer,
+                memoryDescription({rcc::MemoryAccessFlag::Load}, 8, 0));
+  addMemOperand(**Function, ReversedTransfer,
+                memoryDescription({rcc::MemoryAccessFlag::Store}, 8, 1));
+  Context.expect(!Set->validateInstruction(ReversedTransfer, (*Function)->registerInfo()),
+                 "G_MEMCPY must reject reversed MMO access directions");
+}
+
+void testSemanticFlags(TestContext &Context) {
+  const auto Descriptors = rcc::genericInstructionDescriptors();
+  const auto Find = [Descriptors](rcc::GenericOpcode OpcodeValue) {
+    const rcc::Opcode Value = rcc::opcode(OpcodeValue);
+    const auto Position =
+        std::ranges::find_if(Descriptors, [Value](const rcc::InstructionDescriptor &Descriptor) {
+          return Descriptor.InstructionOpcode == Value;
+        });
+    return Position == Descriptors.end() ? nullptr : &*Position;
+  };
+
+  const auto *Load = Find(rcc::GenericOpcode::G_LOAD);
+  const auto *Atomic = Find(rcc::GenericOpcode::G_ATOMIC_CMPXCHG);
+  const auto *Branch = Find(rcc::GenericOpcode::G_BRINDIRECT);
+  const auto *Strict = Find(rcc::GenericOpcode::G_STRICT_FMA);
+  const auto *InlineAsm = Find(rcc::GenericOpcode::INLINEASM);
+  Context.expect(
+      Load != nullptr && Load->Flags.has(rcc::InstructionFlag::MayLoad) &&
+          Load->RequiresMemoryOperands && Atomic != nullptr &&
+          Atomic->Flags.has(rcc::InstructionFlag::MayLoad) &&
+          Atomic->Flags.has(rcc::InstructionFlag::MayStore) && Atomic->RequiresMemoryOperands &&
+          Branch != nullptr && Branch->Flags.has(rcc::InstructionFlag::Terminator) &&
+          Branch->Flags.has(rcc::InstructionFlag::IndirectBranch) &&
+          Branch->Flags.has(rcc::InstructionFlag::Barrier) && Strict != nullptr &&
+          Strict->Flags.has(rcc::InstructionFlag::HasSideEffects) && InlineAsm != nullptr &&
+          InlineAsm->Flags.has(rcc::InstructionFlag::TerminalEmission) &&
+          InlineAsm->Owner == rcc::PseudoOwner::AsmPrinter,
+      "memory, control-flow, constrained-FP, and terminal flags must be explicit");
+}
+
+} // namespace
+
+int main() {
+  TestContext Context;
+  testCompleteRegistry(Context);
+  testCoreOpcodeContracts(Context);
+  testShapesAndTypes(Context);
+  testInstructionMemorySemantics(Context);
+  testSemanticFlags(Context);
+  return Context.result();
+}
diff --git a/backend/unittests/CodeGen/MachineAnalysesTest.cpp b/backend/unittests/CodeGen/MachineAnalysesTest.cpp
new file mode 100644
index 0000000..23c5e19
--- /dev/null
+++ b/backend/unittests/CodeGen/MachineAnalysesTest.cpp
@@ -0,0 +1,477 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "rcc/CodeGen/MachineAnalyses.h"
+
+#include "Target/TestTarget.h"
+#include "rcc/CodeGen/GenericOpcodes.h"
+#include "rcc/CodeGen/MachineCFGUpdater.h"
+#include "rcc/CodeGen/MachineFunction.h"
+#include "rcc/CodeGen/MachineIRBuilder.h"
+#include "rcc/CodeGen/MachineInstr.h"
+#include "rcc/CodeGen/MachineMemOperand.h"
+#include "rcc/CodeGen/MachineVerifier.h"
+
+#include <algorithm>
+#include <cstddef>
+#include <cstdint>
+#include <iostream>
+#include <string_view>
+#include <utility>
+#include <vector>
+
+namespace {
+
+class TestContext final {
+public:
+  void expect(bool Condition, std::string_view Message) {
+    if (Condition)
+      return;
+    std::cerr << Message << '\n';
+    ++Failures;
+  }
+
+  [[nodiscard]] int result() const noexcept {
+    return Failures == 0 ? 0 : 1;
+  }
+
+private:
+  int Failures = 0;
+};
+
+[[nodiscard]] rcc::Expected<rcc::TargetDescription> createTarget() {
+  std::vector<rcc::InstructionDescriptor> Descriptors;
+  std::vector<rcc::ImmediatePredicate> Predicates;
+  auto Appended = rcc::appendGenericInstructionInfo(Descriptors, Predicates);
+  if (!Appended)
+    return std::unexpected(Appended.error());
+  auto Instructions = rcc::InstructionSet::create(std::move(Descriptors), std::move(Predicates));
+  if (!Instructions)
+    return std::unexpected(Instructions.error());
+  return rcc::test::createTestTargetDescription(std::move(*Instructions));
+}
+
+[[nodiscard]] rcc::Expected<rcc::MachineBasicBlock *> appendBlock(rcc::MachineFunction &Function) {
+  auto Block = Function.createBasicBlock();
+  if (!Block)
+    return std::unexpected(Block.error());
+  auto Appended = Function.appendBlock(**Block);
+  if (!Appended)
+    return std::unexpected(Appended.error());
+  return *Block;
+}
+
+void testCFGAnalyses(TestContext &Context, const rcc::TargetDescription &Target) {
+  auto Function = rcc::MachineFunction::create("cfg", rcc::MachineFunctionStableID::fromValue(1));
+  Context.expect(Function.has_value(), "CFG analysis function creation must succeed");
+  if (!Function)
+    return;
+
+  auto Entry = appendBlock(**Function);
+  auto Header = appendBlock(**Function);
+  auto Body = appendBlock(**Function);
+  auto Exit = appendBlock(**Function);
+  auto Dead = appendBlock(**Function);
+  Context.expect(Entry && Header && Body && Exit && Dead,
+                 "CFG analysis blocks must be appended successfully");
+  if (!Entry || !Header || !Body || !Exit || !Dead)
+    return;
+
+  auto ThreeQuarters = rcc::BranchProbability::fromFraction(3, 4);
+  auto OneQuarter = rcc::BranchProbability::fromFraction(1, 4);
+  auto Updater = (*Function)->cfgUpdater();
+  Context.expect(ThreeQuarters && OneQuarter &&
+                     Updater.addSuccessor(**Entry, **Header, rcc::BranchProbability::one()) &&
+                     Updater.addSuccessor(**Header, **Body, *ThreeQuarters) &&
+                     Updater.addSuccessor(**Header, **Exit, *OneQuarter) &&
+                     Updater.addSuccessor(**Body, **Header, rcc::BranchProbability::one()),
+                 "reducible loop CFG construction must succeed");
+
+  rcc::MachineAnalysisManager Analyses;
+  Context.expect(rcc::registerStage8MachineAnalyses(Analyses).has_value(),
+                 "standard Stage 8 analyses must register atomically");
+  auto Dominators = Analyses.getResult<rcc::MachineDominatorTreeAnalysis>(**Function, Target);
+  auto Loops = Analyses.getResult<rcc::MachineLoopAnalysis>(**Function, Target);
+  auto Probabilities =
+      Analyses.getResult<rcc::MachineBranchProbabilityAnalysis>(**Function, Target);
+  auto Frequencies = Analyses.getResult<rcc::MachineBlockFrequencyAnalysis>(**Function, Target);
+  Context.expect(Dominators && Loops && Probabilities && Frequencies,
+                 "CFG analyses and their dependencies must materialize");
+  if (!Dominators || !Loops || !Probabilities || !Frequencies)
+    return;
+
+  Context.expect((*Dominators)->dominates(**Entry, **Exit) &&
+                     (*Dominators)->dominates(**Header, **Body) &&
+                     (*Dominators)->immediateDominator(**Body) == *Header &&
+                     (*Dominators)->nearestCommonDominator(**Body, **Exit) == *Header &&
+                     !(*Dominators)->isReachable(**Dead),
+                 "dominator analysis must model reachability, IDom, and common dominators");
+  Context.expect((*Loops)->loops().size() == 1 && (*Loops)->loopFor(**Header) != nullptr &&
+                     (*Loops)->loopFor(**Body) != nullptr && (*Loops)->loopDepth(**Body) == 1,
+                 "loop analysis must recover the natural loop and loop depth");
+  Context.expect((*Probabilities)->probability(**Header, **Body) == *ThreeQuarters &&
+                     (*Probabilities)->probability(**Header, **Exit) == *OneQuarter,
+                 "branch-probability analysis must retain exact integer edge probabilities");
+  Context.expect((*Frequencies)->frequency(**Entry) != 0 &&
+                     (*Frequencies)->frequency(**Header) > (*Frequencies)->frequency(**Entry) &&
+                     (*Frequencies)->frequency(**Dead) == 0,
+                 "block-frequency analysis must distinguish loop and unreachable blocks");
+
+  auto Alias = Analyses.getResult<rcc::MachineAliasAnalysis>(**Function, Target);
+  auto MemoryDependence =
+      Analyses.getResult<rcc::MachineMemoryDependenceAnalysis>(**Function, Target);
+  Context.expect(Alias && MemoryDependence && Analyses.cachedResultCount(**Function) == 6,
+                 "the complete Stage 8 analysis set must materialize into one function cache");
+  Analyses.invalidate(**Function, rcc::PreservedAnalyses::none(),
+                      {rcc::MachinePassChange::Registers});
+  Context.expect(Analyses.cachedResultCount(**Function) == 6,
+                 "register-only changes must preserve CFG and memory analyses");
+  Analyses.invalidate(**Function, rcc::PreservedAnalyses::none(), {rcc::MachinePassChange::CFG});
+  Context.expect(
+      Analyses.cachedResultCount(**Function) == 1 &&
+          Analyses.hasCached(**Function,
+                             rcc::MachineAnalysisManager::id<rcc::MachineAliasAnalysis>()),
+      "CFG changes must invalidate CFG dependents and memory dependence but preserve aliasing");
+
+  auto RefreshedDominators =
+      Analyses.getResult<rcc::MachineDominatorTreeAnalysis>(**Function, Target);
+  Context.expect(
+      RefreshedDominators &&
+          Updater.addSuccessor(**Entry, **Exit, rcc::BranchProbability::zero()).has_value() &&
+          (*RefreshedDominators)->updateAfterCFGChange(**Function).has_value() &&
+          (*RefreshedDominators)->immediateDominator(**Exit) == *Entry,
+      "dominator result must support exact updates after CFG edge changes");
+}
+
+void testIrreducibleCFG(TestContext &Context, const rcc::TargetDescription &Target) {
+  auto Function =
+      rcc::MachineFunction::create("irreducible", rcc::MachineFunctionStableID::fromValue(2));
+  if (!Function) {
+    Context.expect(false, "irreducible CFG function creation must succeed");
+    return;
+  }
+  auto Entry = appendBlock(**Function);
+  auto Left = appendBlock(**Function);
+  auto Right = appendBlock(**Function);
+  auto Exit = appendBlock(**Function);
+  if (!Entry || !Left || !Right || !Exit) {
+    Context.expect(false, "irreducible CFG blocks must be appended");
+    return;
+  }
+  auto Half = rcc::BranchProbability::fromFraction(1, 2);
+  auto Updater = (*Function)->cfgUpdater();
+  Context.expect(Half && Updater.addSuccessor(**Entry, **Left, *Half) &&
+                     Updater.addSuccessor(**Entry, **Right, *Half) &&
+                     Updater.addSuccessor(**Left, **Right, *Half) &&
+                     Updater.addSuccessor(**Left, **Exit, *Half) &&
+                     Updater.addSuccessor(**Right, **Left, *Half) &&
+                     Updater.addSuccessor(**Right, **Exit, *Half),
+                 "irreducible CFG construction must succeed");
+
+  rcc::MachineAnalysisManager Analyses;
+  auto Registered = rcc::registerStage8MachineAnalyses(Analyses);
+  auto Loops =
+      Registered
+          ? Analyses.getResult<rcc::MachineLoopAnalysis>(**Function, Target)
+          : rcc::Expected<rcc::MachineLoopAnalysis::Result *>{std::unexpected(Registered.error())};
+  Context.expect(Loops && (*Loops)->irreducibleRegions().size() == 1 &&
+                     (*Loops)->irreducibleRegions().front().Entries.size() == 2 &&
+                     (*Loops)->isIrreducible(**Left) && (*Loops)->isIrreducible(**Right),
+                 "loop analysis must explicitly identify multi-entry irreducible regions");
+}
+
+[[nodiscard]] rcc::MachineMemOperandDesc
+memoryDescription(rcc::MemoryBase Base, std::int64_t Offset, rcc::MemoryAccessFlag Access) {
+  rcc::MachineMemOperandDesc Description;
+  Description.Accesses = {Access};
+  Description.Size = *rcc::MemorySize::fixed(8);
+  Description.Align = *rcc::Alignment::create(8);
+  Description.Base = std::move(Base);
+  Description.Offset = Offset;
+  return Description;
+}
+
+void testAliasAnalysis(TestContext &Context) {
+  auto First = rcc::MachineMemOperand::create(memoryDescription(
+      rcc::MemoryBase::frameIndex(rcc::FrameIndex::fromValue(0)), 0, rcc::MemoryAccessFlag::Load));
+  auto Same = rcc::MachineMemOperand::create(memoryDescription(
+      rcc::MemoryBase::frameIndex(rcc::FrameIndex::fromValue(0)), 0, rcc::MemoryAccessFlag::Store));
+  auto Partial = rcc::MachineMemOperand::create(memoryDescription(
+      rcc::MemoryBase::frameIndex(rcc::FrameIndex::fromValue(0)), 4, rcc::MemoryAccessFlag::Store));
+  auto DisjointRange = rcc::MachineMemOperand::create(
+      memoryDescription(rcc::MemoryBase::frameIndex(rcc::FrameIndex::fromValue(0)), 16,
+                        rcc::MemoryAccessFlag::Store));
+  auto DistinctObject = rcc::MachineMemOperand::create(memoryDescription(
+      rcc::MemoryBase::frameIndex(rcc::FrameIndex::fromValue(1)), 0, rcc::MemoryAccessFlag::Store));
+  auto DifferentObjectKind = rcc::MachineMemOperand::create(
+      memoryDescription(rcc::MemoryBase::constantPool(rcc::ConstantPoolIndex::fromValue(0)), 0,
+                        rcc::MemoryAccessFlag::Store));
+  Context.expect(First && Same && Partial && DisjointRange && DistinctObject && DifferentObjectKind,
+                 "alias-analysis memory operands must be valid");
+  if (!First || !Same || !Partial || !DisjointRange || !DistinctObject || !DifferentObjectKind)
+    return;
+
+  rcc::MachineAliasAnalysis::Result Alias;
+  Context.expect(Alias.alias(*First, *Same) == rcc::MachineAliasResult::MustAlias &&
+                     Alias.alias(*First, *Partial) == rcc::MachineAliasResult::PartialAlias &&
+                     Alias.alias(*First, *DisjointRange) == rcc::MachineAliasResult::NoAlias &&
+                     Alias.alias(*First, *DistinctObject) == rcc::MachineAliasResult::NoAlias &&
+                     Alias.alias(*First, *DifferentObjectKind) == rcc::MachineAliasResult::NoAlias,
+                 "alias analysis must distinguish exact, partial, range, and object aliasing");
+}
+
+void testMemoryDependence(TestContext &Context, const rcc::TargetDescription &Target) {
+  auto Function =
+      rcc::MachineFunction::create("memory", rcc::MachineFunctionStableID::fromValue(3));
+  if (!Function) {
+    Context.expect(false, "memory-dependence function creation must succeed");
+    return;
+  }
+  auto Block = appendBlock(**Function);
+  auto OtherBlock = appendBlock(**Function);
+  auto I64 = rcc::LLT::makeInteger(64);
+  auto Pointer = rcc::LLT::makePointer(0, 64);
+  auto Value = I64 ? (*Function)->registerInfo().createVirtualRegister(*I64)
+                   : rcc::Expected<rcc::Register>{std::unexpected(I64.error())};
+  auto Address = Pointer ? (*Function)->registerInfo().createVirtualRegister(*Pointer)
+                         : rcc::Expected<rcc::Register>{std::unexpected(Pointer.error())};
+  if (!Block || !OtherBlock || !Value || !Address) {
+    Context.expect(false, "memory-dependence MachineIR setup must succeed");
+    return;
+  }
+
+  auto StoreMemory = (*Function)->createMemOperand(
+      memoryDescription(rcc::MemoryBase::stack(), 0, rcc::MemoryAccessFlag::Store));
+  auto AliasingLoadMemory = (*Function)->createMemOperand(
+      memoryDescription(rcc::MemoryBase::stack(), 0, rcc::MemoryAccessFlag::Load));
+  auto DisjointLoadMemory = (*Function)->createMemOperand(
+      memoryDescription(rcc::MemoryBase::stack(), 32, rcc::MemoryAccessFlag::Load));
+  auto VolatileStoreDescription =
+      memoryDescription(rcc::MemoryBase::stack(), 64, rcc::MemoryAccessFlag::Store);
+  VolatileStoreDescription.Accesses.set(rcc::MemoryAccessFlag::Volatile);
+  auto VolatileLoadDescription =
+      memoryDescription(rcc::MemoryBase::stack(), 96, rcc::MemoryAccessFlag::Load);
+  VolatileLoadDescription.Accesses.set(rcc::MemoryAccessFlag::Volatile);
+  auto VolatileStoreMemory = (*Function)->createMemOperand(std::move(VolatileStoreDescription));
+  auto VolatileLoadMemory = (*Function)->createMemOperand(std::move(VolatileLoadDescription));
+  auto OtherBlockLoadMemory = (*Function)->createMemOperand(
+      memoryDescription(rcc::MemoryBase::stack(), 0, rcc::MemoryAccessFlag::Load));
+  rcc::MachineIRBuilder Builder(**Function, Target);
+  Context.expect(StoreMemory && AliasingLoadMemory && DisjointLoadMemory && VolatileStoreMemory &&
+                     VolatileLoadMemory && OtherBlockLoadMemory && Builder.setInsertPoint(**Block),
+                 "memory-dependence builder setup must succeed");
+  if (!StoreMemory || !AliasingLoadMemory || !DisjointLoadMemory || !VolatileStoreMemory ||
+      !VolatileLoadMemory || !OtherBlockLoadMemory)
+    return;
+
+  auto Store = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_STORE));
+  if (!Store || !Store->addUse(*Value) || !Store->addUse(*Address) ||
+      !Store->addMemOperand(**StoreMemory)) {
+    Context.expect(false, "generic store construction must succeed");
+    return;
+  }
+  auto StoreInstruction = Store->build();
+  auto Load = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_LOAD));
+  if (!Load || !Load->addDef(*Value) || !Load->addUse(*Address) ||
+      !Load->addMemOperand(**AliasingLoadMemory)) {
+    Context.expect(false, "aliasing generic load construction must succeed");
+    return;
+  }
+  auto LoadInstruction = Load->build();
+  auto DisjointLoad = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_LOAD));
+  if (!DisjointLoad || !DisjointLoad->addDef(*Value) || !DisjointLoad->addUse(*Address) ||
+      !DisjointLoad->addMemOperand(**DisjointLoadMemory)) {
+    Context.expect(false, "disjoint generic load construction must succeed");
+    return;
+  }
+  auto DisjointLoadInstruction = DisjointLoad->build();
+  auto VolatileStore = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_STORE));
+  if (!VolatileStore || !VolatileStore->addUse(*Value) || !VolatileStore->addUse(*Address) ||
+      !VolatileStore->addMemOperand(**VolatileStoreMemory)) {
+    Context.expect(false, "volatile store construction must succeed");
+    return;
+  }
+  auto VolatileStoreInstruction = VolatileStore->build();
+  auto VolatileLoad = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_LOAD));
+  if (!VolatileLoad || !VolatileLoad->addDef(*Value) || !VolatileLoad->addUse(*Address) ||
+      !VolatileLoad->addMemOperand(**VolatileLoadMemory)) {
+    Context.expect(false, "volatile load construction must succeed");
+    return;
+  }
+  auto VolatileLoadInstruction = VolatileLoad->build();
+  if (!Builder.setInsertPoint(**OtherBlock)) {
+    Context.expect(false, "second memory region insertion point must be valid");
+    return;
+  }
+  auto OtherBlockLoad = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_LOAD));
+  if (!OtherBlockLoad || !OtherBlockLoad->addDef(*Value) || !OtherBlockLoad->addUse(*Address) ||
+      !OtherBlockLoad->addMemOperand(**OtherBlockLoadMemory)) {
+    Context.expect(false, "second-region generic load construction must succeed");
+    return;
+  }
+  auto OtherBlockLoadInstruction = OtherBlockLoad->build();
+  Context.expect(StoreInstruction && LoadInstruction && DisjointLoadInstruction &&
+                     VolatileStoreInstruction && VolatileLoadInstruction &&
+                     OtherBlockLoadInstruction,
+                 "memory instructions must be published transactionally");
+  if (!StoreInstruction || !LoadInstruction || !DisjointLoadInstruction ||
+      !VolatileStoreInstruction || !VolatileLoadInstruction || !OtherBlockLoadInstruction)
+    return;
+
+  rcc::MachineAnalysisManager Analyses;
+  auto Registered = rcc::registerStage8MachineAnalyses(Analyses);
+  auto Dependencies =
+      Registered ? Analyses.getResult<rcc::MachineMemoryDependenceAnalysis>(**Function, Target)
+                 : rcc::Expected<rcc::MachineMemoryDependenceAnalysis::Result *>{
+                       std::unexpected(Registered.error())};
+  Context.expect(Dependencies && (*Dependencies)->dependencies(**LoadInstruction).size() == 1 &&
+                     (*Dependencies)->dependencies(**LoadInstruction).front().Source ==
+                         (*StoreInstruction)->stableID() &&
+                     (*Dependencies)->dependencies(**DisjointLoadInstruction).empty(),
+                 "memory dependence must add flow edges only for potentially aliasing accesses");
+  Context.expect(
+      Dependencies && (*Dependencies)->regions().size() == 2 &&
+          (*Dependencies)->regionFor(**Block) != nullptr &&
+          (*Dependencies)->regionFor(**Block)->Instructions.size() == 5 &&
+          (*Dependencies)->regionFor(**OtherBlock) != nullptr &&
+          (*Dependencies)->regionFor(**OtherBlock)->Instructions.size() == 1 &&
+          (*Dependencies)->dependencies(**OtherBlockLoadInstruction).empty() &&
+          (*Dependencies)->dependencies(**OtherBlock).empty(),
+      "memory dependence must expose deterministic block regions without cross-CFG edges");
+  bool HasOrderedVolatileDependency = false;
+  if (Dependencies) {
+    HasOrderedVolatileDependency =
+        std::ranges::any_of((*Dependencies)->dependencies(**VolatileLoadInstruction),
+                            [&](const rcc::MachineMemoryDependency &Dependency) {
+                              return Dependency.Source == (*VolatileStoreInstruction)->stableID();
+                            });
+  }
+  Context.expect(HasOrderedVolatileDependency,
+                 "ordered memory accesses must retain dependencies across disjoint addresses");
+}
+
+class ConflictingAnalysis final {
+public:
+  struct Result final {};
+  [[nodiscard]] static rcc::Expected<Result>
+  run(rcc::MachineFunction &, const rcc::TargetDescription &, rcc::MachineAnalysisManager &) {
+    return Result{};
+  }
+};
+
+void testAtomicStandardRegistration(TestContext &Context) {
+  rcc::MachineAnalysisManager Analyses;
+  Context.expect(Analyses
+                     .registerAnalysis<ConflictingAnalysis>({
+                         .Name = "MachineLoopInfo",
+                         .Dependencies = {},
+                     })
+                     .has_value(),
+                 "analysis-name conflict setup must succeed");
+  Context.expect(!rcc::registerStage8MachineAnalyses(Analyses) &&
+                     !Analyses.isRegistered(
+                         rcc::MachineAnalysisManager::id<rcc::MachineDominatorTreeAnalysis>()),
+                 "failed standard-analysis registration must not publish a partial set");
+}
+
+void testCFGUpdaterPHIs(TestContext &Context, const rcc::TargetDescription &Target) {
+  auto Function =
+      rcc::MachineFunction::create("cfg_phi", rcc::MachineFunctionStableID::fromValue(4));
+  if (!Function) {
+    Context.expect(false, "CFG PHI function creation must succeed");
+    return;
+  }
+  auto Source = appendBlock(**Function);
+  auto Other = appendBlock(**Function);
+  auto Merge = appendBlock(**Function);
+  auto Unconnected = appendBlock(**Function);
+  if (!Source || !Other || !Merge || !Unconnected) {
+    Context.expect(false, "CFG PHI blocks must be appended");
+    return;
+  }
+  auto Updater = (*Function)->cfgUpdater();
+  if (!Updater.addSuccessor(**Source, **Merge, rcc::BranchProbability::one()) ||
+      !Updater.addSuccessor(**Other, **Merge, rcc::BranchProbability::one())) {
+    Context.expect(false, "CFG PHI predecessor edges must be created");
+    return;
+  }
+
+  auto I64 = rcc::LLT::makeInteger(64);
+  auto Destination = I64 ? (*Function)->registerInfo().createVirtualRegister(*I64)
+                         : rcc::Expected<rcc::Register>{std::unexpected(I64.error())};
+  auto SourceValue = I64 ? (*Function)->registerInfo().createVirtualRegister(*I64)
+                         : rcc::Expected<rcc::Register>{std::unexpected(I64.error())};
+  auto OtherValue = I64 ? (*Function)->registerInfo().createVirtualRegister(*I64)
+                        : rcc::Expected<rcc::Register>{std::unexpected(I64.error())};
+  if (!Destination || !SourceValue || !OtherValue) {
+    Context.expect(false, "CFG PHI registers must be created");
+    return;
+  }
+
+  rcc::MachineIRBuilder Builder(**Function, Target);
+  if (!Builder.setInsertPoint(**Source))
+    return;
+  auto SourceDefinition = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_IMPLICIT_DEF));
+  if (!SourceDefinition || !SourceDefinition->addDef(*SourceValue) || !SourceDefinition->build()) {
+    Context.expect(false, "CFG PHI source definition must build");
+    return;
+  }
+  auto Branch = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_BR));
+  if (!Branch || !Branch->addBasicBlock(**Merge)) {
+    Context.expect(false, "CFG PHI branch must be assembled");
+    return;
+  }
+  auto BranchInstruction = Branch->build();
+  if (!BranchInstruction || !Builder.setInsertPoint(**Merge)) {
+    Context.expect(false, "CFG PHI branch must publish");
+    return;
+  }
+  auto Phi = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_PHI));
+  if (!Phi || !Phi->addDef(*Destination) || !Phi->addUse(*SourceValue) ||
+      !Phi->addBasicBlock(**Source) || !Phi->addUse(*OtherValue) || !Phi->addBasicBlock(**Other)) {
+    Context.expect(false, "CFG PHI instruction must be assembled");
+    return;
+  }
+  auto PhiInstruction = Phi->build();
+  Context.expect(PhiInstruction && rcc::MachineVerifier::verify(**Function, Target),
+                 "initial CFG PHI function must verify");
+  if (!PhiInstruction)
+    return;
+
+  auto Split = Updater.splitBlock(**Source, **BranchInstruction);
+  Context.expect(
+      Split && (*Split)->predecessors().size() == 1 &&
+          (*Split)->predecessors().front() == *Source && (*Split)->successors().size() == 1 &&
+          (*PhiInstruction)->operandAt(2)->getIf<rcc::BasicBlockOperand>()->Block == *Split &&
+          rcc::MachineVerifier::verify(**Function, Target),
+      "block split must redirect CFG edges and PHI predecessor identity");
+  if (!Split)
+    return;
+
+  Context.expect(Updater.removeSuccessor(**Other, **Merge) &&
+                     (*PhiInstruction)->operandCount() == 3 &&
+                     rcc::MachineVerifier::verify(**Function, Target),
+                 "edge deletion must remove the corresponding PHI incoming pair");
+  Context.expect(!Updater.addSuccessor(**Unconnected, **Merge, rcc::BranchProbability::one()),
+                 "new PHI predecessors without incoming values must be rejected");
+  Context.expect(Updater.deleteBlock(**Other) && !(*Other)->isLinked() &&
+                     rcc::MachineVerifier::verify(**Function, Target),
+                 "CFG block deletion must detach a disconnected block cleanly");
+}
+
+} // namespace
+
+int main() {
+  TestContext Context;
+  auto Target = createTarget();
+  Context.expect(Target.has_value(), "machine analysis tests require a valid target");
+  if (!Target)
+    return Context.result();
+
+  testCFGAnalyses(Context, *Target);
+  testIrreducibleCFG(Context, *Target);
+  testAliasAnalysis(Context);
+  testMemoryDependence(Context, *Target);
+  testCFGUpdaterPHIs(Context, *Target);
+  testAtomicStandardRegistration(Context);
+  return Context.result();
+}
diff --git a/backend/unittests/CodeGen/MachinePassTest.cpp b/backend/unittests/CodeGen/MachinePassTest.cpp
new file mode 100644
index 0000000..fb125a4
--- /dev/null
+++ b/backend/unittests/CodeGen/MachinePassTest.cpp
@@ -0,0 +1,918 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "rcc/CodeGen/MachinePass.h"
+
+#include "Target/TestTarget.h"
+#include "rcc/CodeGen/CompilationUnit.h"
+#include "rcc/CodeGen/GenericOpcodes.h"
+#include "rcc/CodeGen/MachineFunction.h"
+
+#include <algorithm>
+#include <atomic>
+#include <chrono>
+#include <cstddef>
+#include <cstdint>
+#include <iostream>
+#include <memory>
+#include <ranges>
+#include <string>
+#include <string_view>
+#include <thread>
+#include <utility>
+#include <vector>
+
+namespace {
+
+class TestContext final {
+public:
+  void expect(bool Condition, std::string_view Message) {
+    if (Condition)
+      return;
+    std::cerr << Message << '\n';
+    ++Failures;
+  }
+
+  [[nodiscard]] int result() const noexcept {
+    return Failures == 0 ? 0 : 1;
+  }
+
+private:
+  int Failures = 0;
+};
+
+[[nodiscard]] rcc::Expected<rcc::TargetDescription> createTarget() {
+  std::vector<rcc::InstructionDescriptor> Descriptors;
+  std::vector<rcc::ImmediatePredicate> Predicates;
+  auto Appended = rcc::appendGenericInstructionInfo(Descriptors, Predicates);
+  if (!Appended)
+    return std::unexpected(Appended.error());
+  auto Instructions = rcc::InstructionSet::create(std::move(Descriptors), std::move(Predicates));
+  if (!Instructions)
+    return std::unexpected(Instructions.error());
+  return rcc::test::createTestTargetDescription(std::move(*Instructions));
+}
+
+class BlockCountAnalysis final {
+public:
+  struct Result final {
+    std::size_t Count = 0;
+  };
+
+  [[nodiscard]] static constexpr std::string_view name() noexcept {
+    return "BlockCount";
+  }
+
+  [[nodiscard]] static rcc::Expected<Result> run(rcc::MachineFunction &Function,
+                                                 const rcc::TargetDescription &,
+                                                 rcc::MachineAnalysisManager &) {
+    ++Runs;
+    return Result{Function.blockCount()};
+  }
+
+  static inline std::atomic<std::uint32_t> Runs = 0;
+};
+
+class DependentAnalysis final {
+public:
+  struct Result final {
+    std::size_t Count = 0;
+  };
+
+  [[nodiscard]] static constexpr std::string_view name() noexcept {
+    return "Dependent";
+  }
+
+  [[nodiscard]] static rcc::Expected<Result> run(rcc::MachineFunction &Function,
+                                                 const rcc::TargetDescription &Target,
+                                                 rcc::MachineAnalysisManager &Analyses) {
+    auto Blocks = Analyses.getResult<BlockCountAnalysis>(Function, Target);
+    if (!Blocks)
+      return std::unexpected(Blocks.error());
+    return Result{(*Blocks)->Count};
+  }
+};
+
+class NonThreadSafeAnalysis final {
+public:
+  struct Result final {};
+
+  [[nodiscard]] static constexpr std::string_view name() noexcept {
+    return "NonThreadSafe";
+  }
+
+  [[nodiscard]] static rcc::Expected<Result>
+  run(rcc::MachineFunction &, const rcc::TargetDescription &, rcc::MachineAnalysisManager &) {
+    return Result{};
+  }
+};
+
+class FailingAnalysis final {
+public:
+  struct Result final {};
+
+  [[nodiscard]] static constexpr std::string_view name() noexcept {
+    return "Failing";
+  }
+
+  [[nodiscard]] static rcc::Expected<Result>
+  run(rcc::MachineFunction &, const rcc::TargetDescription &, rcc::MachineAnalysisManager &) {
+    return rcc::makeUnexpected(rcc::ErrorCode::VerificationError,
+                               "intentional machine analysis failure");
+  }
+};
+
+class StickyAnalysis final {
+public:
+  struct Result final {
+    [[nodiscard]] bool invalidate(const rcc::MachineFunction &,
+                                  const rcc::PreservedAnalyses &) noexcept {
+      return false;
+    }
+  };
+
+  [[nodiscard]] static constexpr std::string_view name() noexcept {
+    return "Sticky";
+  }
+  [[nodiscard]] static rcc::Expected<Result>
+  run(rcc::MachineFunction &, const rcc::TargetDescription &, rcc::MachineAnalysisManager &) {
+    return Result{};
+  }
+};
+
+class ExpiringAnalysis final {
+public:
+  struct Result final {
+    [[nodiscard]] bool invalidate(const rcc::MachineFunction &,
+                                  const rcc::PreservedAnalyses &) noexcept {
+      return true;
+    }
+  };
+
+  [[nodiscard]] static constexpr std::string_view name() noexcept {
+    return "Expiring";
+  }
+  [[nodiscard]] static rcc::Expected<Result>
+  run(rcc::MachineFunction &, const rcc::TargetDescription &, rcc::MachineAnalysisManager &) {
+    return Result{};
+  }
+};
+
+class CycleA final {
+public:
+  struct Result final {};
+  [[nodiscard]] static constexpr std::string_view name() noexcept {
+    return "CycleA";
+  }
+  [[nodiscard]] static rcc::Expected<Result>
+  run(rcc::MachineFunction &, const rcc::TargetDescription &, rcc::MachineAnalysisManager &) {
+    return Result{};
+  }
+};
+
+class CycleB final {
+public:
+  struct Result final {};
+  [[nodiscard]] static constexpr std::string_view name() noexcept {
+    return "CycleB";
+  }
+  [[nodiscard]] static rcc::Expected<Result>
+  run(rcc::MachineFunction &, const rcc::TargetDescription &, rcc::MachineAnalysisManager &) {
+    return Result{};
+  }
+};
+
+class RequiredAnalysisPass final : public rcc::MachineFunctionPass {
+public:
+  [[nodiscard]] const rcc::MachinePassContract &contract() const noexcept override {
+    static const rcc::MachinePassContract Contract{
+        .Name = "RequiredAnalysis",
+        .Requires = {},
+        .Sets = {},
+        .Clears = {},
+        .RequiredAnalyses = {rcc::MachineAnalysisManager::id<DependentAnalysis>()},
+        .VerificationStage = std::nullopt,
+    };
+    return Contract;
+  }
+
+  [[nodiscard]] rcc::Expected<rcc::MachinePassResult>
+  run(rcc::MachineFunction &Function, const rcc::TargetDescription &Target,
+      rcc::MachineAnalysisManager &Analyses) override {
+    auto Dependent = Analyses.getResult<DependentAnalysis>(Function, Target);
+    if (!Dependent)
+      return std::unexpected(Dependent.error());
+    auto FirstAction = Analyses.requestAction("first", Function);
+    auto SecondAction = Analyses.requestAction("second", Function);
+    if (!FirstAction || !SecondAction || !*FirstAction || *SecondAction) {
+      return rcc::makeUnexpected(rcc::ErrorCode::VerificationError,
+                                 "per-function action fuel was not enforced");
+    }
+    rcc::MachinePassResult Result;
+    Result.Preserved = rcc::PreservedAnalyses::all();
+    return Result;
+  }
+};
+
+class UnreportedChangePass final : public rcc::MachineFunctionPass {
+public:
+  [[nodiscard]] const rcc::MachinePassContract &contract() const noexcept override {
+    static const rcc::MachinePassContract Contract{
+        .Name = "UnreportedChange",
+        .Requires = {},
+        .Sets = {},
+        .Clears = {},
+        .RequiredAnalyses = {},
+        .VerificationStage = std::nullopt,
+    };
+    return Contract;
+  }
+
+  [[nodiscard]] rcc::Expected<rcc::MachinePassResult> run(rcc::MachineFunction &Function,
+                                                          const rcc::TargetDescription &,
+                                                          rcc::MachineAnalysisManager &) override {
+    auto Block = Function.createBasicBlock();
+    if (!Block)
+      return std::unexpected(Block.error());
+    auto Appended = Function.appendBlock(**Block);
+    if (!Appended)
+      return std::unexpected(Appended.error());
+    return rcc::MachinePassResult{};
+  }
+};
+
+class RequiresFailingAnalysisPass final : public rcc::MachineFunctionPass {
+public:
+  [[nodiscard]] const rcc::MachinePassContract &contract() const noexcept override {
+    static const rcc::MachinePassContract Contract{
+        .Name = "RequiresFailingAnalysis",
+        .Requires = {},
+        .Sets = {},
+        .Clears = {},
+        .RequiredAnalyses = {rcc::MachineAnalysisManager::id<FailingAnalysis>()},
+        .VerificationStage = std::nullopt,
+    };
+    return Contract;
+  }
+
+  [[nodiscard]] rcc::Expected<rcc::MachinePassResult> run(rcc::MachineFunction &,
+                                                          const rcc::TargetDescription &,
+                                                          rcc::MachineAnalysisManager &) override {
+    return rcc::MachinePassResult{};
+  }
+};
+
+class MutatingFailurePass final : public rcc::MachineFunctionPass {
+public:
+  [[nodiscard]] const rcc::MachinePassContract &contract() const noexcept override {
+    static const rcc::MachinePassContract Contract{
+        .Name = "MutatingFailure",
+        .Requires = {},
+        .Sets = {},
+        .Clears = {},
+        .RequiredAnalyses = {rcc::MachineAnalysisManager::id<BlockCountAnalysis>()},
+        .VerificationStage = std::nullopt,
+    };
+    return Contract;
+  }
+
+  [[nodiscard]] rcc::Expected<rcc::MachinePassResult> run(rcc::MachineFunction &Function,
+                                                          const rcc::TargetDescription &,
+                                                          rcc::MachineAnalysisManager &) override {
+    auto Block = Function.createBasicBlock();
+    if (!Block)
+      return std::unexpected(Block.error());
+    auto Appended = Function.appendBlock(**Block);
+    if (!Appended)
+      return std::unexpected(Appended.error());
+    return rcc::makeUnexpected(rcc::ErrorCode::VerificationError,
+                               "intentional mutating pass failure");
+  }
+};
+
+class ParallelCountingPass final : public rcc::MachineFunctionPass {
+public:
+  explicit ParallelCountingPass(std::atomic<std::uint32_t> &Count) : Count(&Count) {}
+
+  [[nodiscard]] const rcc::MachinePassContract &contract() const noexcept override {
+    static const rcc::MachinePassContract Contract = [] {
+      rcc::MachinePassContract Value{
+          .Name = "ParallelCounting",
+          .Requires = {},
+          .Sets = {},
+          .Clears = {},
+          .RequiredAnalyses = {},
+          .VerificationStage = std::nullopt,
+      };
+      Value.ThreadSafety = rcc::PassThreadSafety::ThreadSafe;
+      return Value;
+    }();
+    return Contract;
+  }
+
+  [[nodiscard]] rcc::Expected<rcc::MachinePassResult> run(rcc::MachineFunction &,
+                                                          const rcc::TargetDescription &,
+                                                          rcc::MachineAnalysisManager &) override {
+    Count->fetch_add(1, std::memory_order_relaxed);
+    return rcc::MachinePassResult{};
+  }
+
+private:
+  std::atomic<std::uint32_t> *Count;
+};
+
+class InstrumentedParallelPass final : public rcc::MachineFunctionPass {
+public:
+  InstrumentedParallelPass(std::atomic<std::uint32_t> &Runs, std::atomic<std::uint32_t> &Active,
+                           std::atomic<std::uint32_t> &MaximumActive)
+      : Runs(&Runs), Active(&Active), MaximumActive(&MaximumActive) {}
+
+  [[nodiscard]] const rcc::MachinePassContract &contract() const noexcept override {
+    static const rcc::MachinePassContract Contract = [] {
+      rcc::MachinePassContract Value{
+          .Name = "InstrumentedParallel",
+          .Requires = {},
+          .Sets = {},
+          .Clears = {},
+          .RequiredAnalyses = {},
+          .VerificationStage = std::nullopt,
+      };
+      Value.ThreadSafety = rcc::PassThreadSafety::ThreadSafe;
+      Value.DeclaredChanges = {rcc::MachinePassChange::BlockLayout};
+      return Value;
+    }();
+    return Contract;
+  }
+
+  [[nodiscard]] rcc::Expected<rcc::MachinePassResult> run(rcc::MachineFunction &Function,
+                                                          const rcc::TargetDescription &,
+                                                          rcc::MachineAnalysisManager &) override {
+    const std::uint32_t Current = Active->fetch_add(1, std::memory_order_acq_rel) + 1U;
+    std::uint32_t Maximum = MaximumActive->load(std::memory_order_relaxed);
+    while (Maximum < Current &&
+           !MaximumActive->compare_exchange_weak(Maximum, Current, std::memory_order_relaxed)) {
+    }
+    std::this_thread::sleep_for(std::chrono::milliseconds(2));
+    auto Block = Function.createBasicBlock();
+    if (!Block) {
+      Active->fetch_sub(1, std::memory_order_acq_rel);
+      return std::unexpected(Block.error());
+    }
+    auto Appended = Function.appendBlock(**Block);
+    Active->fetch_sub(1, std::memory_order_acq_rel);
+    if (!Appended)
+      return std::unexpected(Appended.error());
+    Runs->fetch_add(1, std::memory_order_relaxed);
+    rcc::MachinePassResult Result;
+    Result.Changed = true;
+    Result.Changes.add(rcc::MachinePassChange::BlockLayout);
+    return Result;
+  }
+
+private:
+  std::atomic<std::uint32_t> *Runs;
+  std::atomic<std::uint32_t> *Active;
+  std::atomic<std::uint32_t> *MaximumActive;
+};
+
+class RequiresNonThreadSafeAnalysisPass final : public rcc::MachineFunctionPass {
+public:
+  [[nodiscard]] const rcc::MachinePassContract &contract() const noexcept override {
+    static const rcc::MachinePassContract Contract = [] {
+      rcc::MachinePassContract Value{
+          .Name = "RequiresNonThreadSafe",
+          .Requires = {},
+          .Sets = {},
+          .Clears = {},
+          .RequiredAnalyses =
+              {
+                  rcc::MachineAnalysisManager::id<NonThreadSafeAnalysis>(),
+              },
+          .VerificationStage = std::nullopt,
+      };
+      Value.ThreadSafety = rcc::PassThreadSafety::ThreadSafe;
+      return Value;
+    }();
+    return Contract;
+  }
+
+  [[nodiscard]] rcc::Expected<rcc::MachinePassResult> run(rcc::MachineFunction &,
+                                                          const rcc::TargetDescription &,
+                                                          rcc::MachineAnalysisManager &) override {
+    return rcc::MachinePassResult{};
+  }
+};
+
+class UnitFunctionCountAnalysis final {
+public:
+  struct Result final {
+    std::size_t Count = 0;
+  };
+  [[nodiscard]] static constexpr std::string_view name() noexcept {
+    return "UnitFunctionCount";
+  }
+  [[nodiscard]] static rcc::Expected<Result> run(rcc::CompilationUnit &Unit,
+                                                 const rcc::TargetDescription &,
+                                                 rcc::CompilationUnitAnalysisManager &) {
+    return Result{Unit.functionCount()};
+  }
+};
+
+class FailingUnitAnalysis final {
+public:
+  struct Result final {};
+
+  [[nodiscard]] static constexpr std::string_view name() noexcept {
+    return "FailingUnit";
+  }
+
+  [[nodiscard]] static rcc::Expected<Result> run(rcc::CompilationUnit &,
+                                                 const rcc::TargetDescription &,
+                                                 rcc::CompilationUnitAnalysisManager &) {
+    return rcc::makeUnexpected(rcc::ErrorCode::VerificationError,
+                               "intentional compilation-unit analysis failure");
+  }
+};
+
+class RequiresFailingUnitAnalysisPass final : public rcc::CompilationUnitPass {
+public:
+  [[nodiscard]] const rcc::CompilationUnitPassContract &contract() const noexcept override {
+    static const rcc::CompilationUnitPassContract Contract{
+        .Name = "RequiresFailingUnitAnalysis",
+        .RequiredAnalyses =
+            {
+                rcc::CompilationUnitAnalysisManager::id<FailingUnitAnalysis>(),
+            },
+        .Parameters = {},
+        .DeclaredChanges = {},
+    };
+    return Contract;
+  }
+
+  [[nodiscard]] rcc::Expected<rcc::CompilationUnitPassResult>
+  run(rcc::CompilationUnit &, const rcc::TargetDescription &, rcc::CompilationUnitAnalysisManager &,
+      rcc::MachineAnalysisManager &) override {
+    return rcc::CompilationUnitPassResult{};
+  }
+};
+
+class ObserveUnitPass final : public rcc::CompilationUnitPass {
+public:
+  [[nodiscard]] const rcc::CompilationUnitPassContract &contract() const noexcept override {
+    static const rcc::CompilationUnitPassContract Contract{
+        .Name = "ObserveUnit",
+        .RequiredAnalyses = {rcc::CompilationUnitAnalysisManager::id<UnitFunctionCountAnalysis>()},
+        .Parameters = {},
+        .DeclaredChanges = {},
+    };
+    return Contract;
+  }
+
+  [[nodiscard]] rcc::Expected<rcc::CompilationUnitPassResult>
+  run(rcc::CompilationUnit &Unit, const rcc::TargetDescription &Target,
+      rcc::CompilationUnitAnalysisManager &Analyses, rcc::MachineAnalysisManager &) override {
+    auto Count = Analyses.getResult<UnitFunctionCountAnalysis>(Unit, Target);
+    if (!Count)
+      return std::unexpected(Count.error());
+    if ((*Count)->Count != Unit.functionCount()) {
+      return rcc::makeUnexpected(rcc::ErrorCode::VerificationError,
+                                 "unit analysis returned a stale function count");
+    }
+    return rcc::CompilationUnitPassResult{};
+  }
+};
+
+class MutatingUnitFailurePass final : public rcc::CompilationUnitPass {
+public:
+  [[nodiscard]] const rcc::CompilationUnitPassContract &contract() const noexcept override {
+    static const rcc::CompilationUnitPassContract Contract{
+        .Name = "MutatingUnitFailure",
+        .RequiredAnalyses = {rcc::CompilationUnitAnalysisManager::id<UnitFunctionCountAnalysis>()},
+        .Parameters = {},
+        .DeclaredChanges = {rcc::MachinePassChange::BlockLayout},
+    };
+    return Contract;
+  }
+
+  [[nodiscard]] rcc::Expected<rcc::CompilationUnitPassResult>
+  run(rcc::CompilationUnit &Unit, const rcc::TargetDescription &,
+      rcc::CompilationUnitAnalysisManager &, rcc::MachineAnalysisManager &) override {
+    auto Created = Unit.createMachineFunction("added-before-failure");
+    if (!Created)
+      return std::unexpected(Created.error());
+    return rcc::makeUnexpected(rcc::ErrorCode::VerificationError,
+                               "intentional compilation-unit pass failure");
+  }
+};
+
+void testAnalysisInfrastructure(TestContext &Context, const rcc::TargetDescription &Target) {
+  auto Function =
+      rcc::MachineFunction::create("analysis", rcc::MachineFunctionStableID::fromValue(1));
+  Context.expect(Function.has_value(), "analysis function creation must succeed");
+  if (!Function)
+    return;
+
+  rcc::MachineAnalysisManager Analyses;
+  Context.expect(Analyses
+                     .registerAnalysis<BlockCountAnalysis>({
+                         .Name = "BlockCount",
+                         .Dependencies = {},
+                         .InvalidatedBy = {rcc::MachinePassChange::CFG},
+                     })
+                     .has_value(),
+                 "base analysis registration must succeed");
+  Context.expect(Analyses
+                     .registerAnalysis<DependentAnalysis>({
+                         .Name = "Dependent",
+                         .Dependencies = {rcc::MachineAnalysisManager::id<BlockCountAnalysis>()},
+                         .InvalidatedBy = {rcc::MachinePassChange::Operands},
+                     })
+                     .has_value(),
+                 "dependent analysis registration must succeed");
+
+  BlockCountAnalysis::Runs = 0;
+  auto First = Analyses.getResult<DependentAnalysis>(**Function, Target);
+  auto Second = Analyses.getResult<DependentAnalysis>(**Function, Target);
+  Context.expect(First && Second && *First == *Second && BlockCountAnalysis::Runs == 1,
+                 "analysis dependencies must materialize once and then use the cache");
+
+  Analyses.invalidate(**Function, rcc::PreservedAnalyses::none(),
+                      {rcc::MachinePassChange::Registers});
+  Context.expect(Analyses.cachedResultCount(**Function) == 2,
+                 "unrelated changes must preserve cached analyses precisely");
+  Analyses.invalidate(**Function, rcc::PreservedAnalyses::none(), {rcc::MachinePassChange::CFG});
+  Context.expect(Analyses.cachedResultCount(**Function) == 0,
+                 "invalidating a dependency must invalidate its dependent analysis");
+
+  rcc::MachineAnalysisManager Cyclic;
+  Context.expect(Cyclic
+                         .registerAnalysis<CycleA>({
+                             .Name = "CycleA",
+                             .Dependencies = {rcc::MachineAnalysisManager::id<CycleB>()},
+                         })
+                         .has_value() &&
+                     Cyclic
+                         .registerAnalysis<CycleB>({
+                             .Name = "CycleB",
+                             .Dependencies = {rcc::MachineAnalysisManager::id<CycleA>()},
+                         })
+                         .has_value(),
+                 "cyclic analysis registrations must be accepted until requested");
+  Context.expect(!Cyclic.getResult<CycleA>(**Function, Target),
+                 "analysis dependency cycles must produce a structured error");
+
+  rcc::MachineAnalysisManager CustomInvalidation;
+  Context.expect(CustomInvalidation
+                         .registerAnalysis<StickyAnalysis>({
+                             .Name = "Sticky",
+                             .Dependencies = {},
+                             .InvalidatedBy = {rcc::MachinePassChange::CFG},
+                         })
+                         .has_value() &&
+                     CustomInvalidation
+                         .registerAnalysis<ExpiringAnalysis>({
+                             .Name = "Expiring",
+                             .Dependencies = {},
+                             .InvalidatedBy = {rcc::MachinePassChange::CFG},
+                         })
+                         .has_value() &&
+                     CustomInvalidation.getResult<StickyAnalysis>(**Function, Target) &&
+                     CustomInvalidation.getResult<ExpiringAnalysis>(**Function, Target),
+                 "custom invalidation analyses must materialize");
+  CustomInvalidation.invalidate(**Function, rcc::PreservedAnalyses::none(),
+                                {rcc::MachinePassChange::CFG});
+  Context.expect(
+      CustomInvalidation.hasCached(**Function, rcc::MachineAnalysisManager::id<StickyAnalysis>()) &&
+          !CustomInvalidation.hasCached(**Function,
+                                        rcc::MachineAnalysisManager::id<ExpiringAnalysis>()),
+      "analysis invalidate() must return false to preserve and true to invalidate");
+}
+
+void testPassAndInstrumentation(TestContext &Context, const rcc::TargetDescription &Target) {
+  auto Function = rcc::MachineFunction::create("pass", rcc::MachineFunctionStableID::fromValue(2));
+  Context.expect(Function.has_value(), "pass function creation must succeed");
+  if (!Function)
+    return;
+
+  rcc::MachineAnalysisManager Analyses;
+  Context.expect(
+      Analyses
+              .registerAnalysis<BlockCountAnalysis>({
+                  .Name = "BlockCount",
+                  .Dependencies = {},
+                  .InvalidatedBy = rcc::MachinePassChanges::all(),
+                  .ThreadSafety = rcc::PassThreadSafety::ThreadSafe,
+              })
+              .has_value() &&
+          Analyses
+              .registerAnalysis<DependentAnalysis>({
+                  .Name = "Dependent",
+                  .Dependencies = {rcc::MachineAnalysisManager::id<BlockCountAnalysis>()},
+              })
+              .has_value(),
+      "pass analysis registrations must succeed");
+
+  rcc::MachinePassInstrumentation Instrumentation;
+  Instrumentation.setPerFunctionFuel(1);
+  std::uint32_t BeforePass = 0;
+  std::uint32_t AfterPass = 0;
+  std::uint32_t BeforeAnalysis = 0;
+  std::uint32_t AfterAnalysis = 0;
+  std::uint32_t AnalysisCacheHits = 0;
+  std::uint32_t Printed = 0;
+  std::uint32_t ChangeEvents = 0;
+  std::uint32_t FailureEvents = 0;
+  Instrumentation.addBeforeCallback(
+      [&BeforePass](std::string_view, const rcc::MachineFunction &) { ++BeforePass; });
+  Instrumentation.addAfterCallback([&AfterPass](std::string_view, const rcc::MachineFunction &,
+                                                const rcc::MachinePassResult &) { ++AfterPass; });
+  Instrumentation.addBeforeAnalysisCallback(
+      [&BeforeAnalysis](std::string_view, const rcc::MachineFunction &) { ++BeforeAnalysis; });
+  Instrumentation.addAfterAnalysisCallback(
+      [&AfterAnalysis, &AnalysisCacheHits](std::string_view, const rcc::MachineFunction &,
+                                           bool CacheHit, std::uint64_t) {
+        ++AfterAnalysis;
+        AnalysisCacheHits += CacheHit ? 1U : 0U;
+      });
+  Instrumentation.addIRPrintCallback([&Printed](rcc::InstrumentationPhase, std::string_view,
+                                                const rcc::MachineFunction &) { ++Printed; });
+  Instrumentation.addChangeCallback([&ChangeEvents](std::string_view, const rcc::MachineFunction &,
+                                                    rcc::MachinePassChanges Changes,
+                                                    bool FingerprintChanged) {
+    if (Changes.empty() && !FingerprintChanged)
+      ++ChangeEvents;
+  });
+  Instrumentation.addFailureCallback([&FailureEvents](std::string_view,
+                                                      const rcc::MachineFunction &,
+                                                      const rcc::Error &) { ++FailureEvents; });
+
+  rcc::MachinePassManager Pipeline;
+  Context.expect(Pipeline.addPass(std::make_unique<RequiredAnalysisPass>()).has_value(),
+                 "a valid pass must be accepted");
+  auto Run = Pipeline.run(**Function, Target, Analyses, &Instrumentation);
+  Context.expect(Run.has_value(), "a pass with a materialized required analysis must run");
+  Context.expect(BeforePass == 1 && AfterPass == 1 && BeforeAnalysis == 2 && AfterAnalysis == 4 &&
+                     AnalysisCacheHits == 2 && Printed == 2 && ChangeEvents == 1,
+                 "pass, analysis, cache-hit, IR-print, and change callbacks must all run");
+  const auto Statistics = Instrumentation.statistics();
+  Context.expect(Statistics.size() == 3,
+                 "instrumentation must collect one pass and two analysis statistics");
+
+  auto ChangedFunction =
+      rcc::MachineFunction::create("unreported", rcc::MachineFunctionStableID::fromValue(3));
+  rcc::MachineAnalysisManager EmptyAnalyses;
+  rcc::MachinePassManager Detecting(
+      {.VerifyBefore = true, .VerifyEach = true, .DetectUnreportedChanges = true});
+  Context.expect(ChangedFunction &&
+                     Detecting.addPass(std::make_unique<UnreportedChangePass>()).has_value() &&
+                     !Detecting.run(**ChangedFunction, Target, EmptyAnalyses, &Instrumentation) &&
+                     FailureEvents == 1,
+                 "change detection must reject an unreported MachineIR mutation");
+
+  auto FailedFunction =
+      rcc::MachineFunction::create("failed", rcc::MachineFunctionStableID::fromValue(4));
+  rcc::MachineAnalysisManager FailureAnalyses;
+  Context.expect(FailedFunction && FailureAnalyses
+                                       .registerAnalysis<BlockCountAnalysis>({
+                                           .Name = "BlockCount",
+                                           .Dependencies = {},
+                                           .InvalidatedBy = rcc::MachinePassChanges::all(),
+                                       })
+                                       .has_value(),
+                 "mutating failure analysis fixtures must be valid");
+  rcc::MachinePassManager FailingPipeline;
+  Context.expect(FailedFunction &&
+                     FailingPipeline.addPass(std::make_unique<MutatingFailurePass>()).has_value() &&
+                     !FailingPipeline.run(**FailedFunction, Target, FailureAnalyses) &&
+                     !FailureAnalyses.hasCached(
+                         **FailedFunction, rcc::MachineAnalysisManager::id<BlockCountAnalysis>()),
+                 "a pass that mutates and fails must not leave stale function analyses cached");
+
+  rcc::MachineAnalysisManager FailingAnalyses;
+  Context.expect(FailingAnalyses
+                     .registerAnalysis<FailingAnalysis>({
+                         .Name = "Failing",
+                         .Dependencies = {},
+                     })
+                     .has_value(),
+                 "failing analysis registration must succeed");
+  rcc::MachinePassInstrumentation FailureInstrumentation;
+  std::uint32_t BeforeFailingAnalysis = 0;
+  std::uint32_t FailingAnalysisEvents = 0;
+  std::uint32_t RequiredAnalysisPassFailures = 0;
+  FailureInstrumentation.addBeforeAnalysisCallback(
+      [&BeforeFailingAnalysis](std::string_view, const rcc::MachineFunction &) {
+        ++BeforeFailingAnalysis;
+      });
+  FailureInstrumentation.addAnalysisFailureCallback(
+      [&FailingAnalysisEvents](std::string_view, const rcc::MachineFunction &, const rcc::Error &) {
+        ++FailingAnalysisEvents;
+      });
+  FailureInstrumentation.addFailureCallback(
+      [&RequiredAnalysisPassFailures](std::string_view, const rcc::MachineFunction &,
+                                      const rcc::Error &) { ++RequiredAnalysisPassFailures; });
+  rcc::MachinePassManager RequiredAnalysisFailurePipeline;
+  Context.expect(
+      RequiredAnalysisFailurePipeline.addPass(std::make_unique<RequiresFailingAnalysisPass>())
+              .has_value() &&
+          !RequiredAnalysisFailurePipeline.run(**Function, Target, FailingAnalyses,
+                                               &FailureInstrumentation) &&
+          BeforeFailingAnalysis == 1 && FailingAnalysisEvents == 1 &&
+          RequiredAnalysisPassFailures == 1,
+      "analysis and pass failure instrumentation must report required-analysis failures");
+}
+
+void testCompilationUnitAndParallelism(TestContext &Context, const rcc::TargetDescription &Target) {
+  rcc::CompilationUnit Unit;
+  for (std::size_t Index = 0; Index < 8; ++Index) {
+    auto Function = Unit.createMachineFunction("f" + std::to_string(Index));
+    Context.expect(Function.has_value(), "parallel test function creation must succeed");
+  }
+
+  std::atomic<std::uint32_t> Runs = 0;
+  rcc::MachinePassManager Parallel;
+  Context.expect(Parallel.addPass(std::make_unique<ParallelCountingPass>(Runs)).has_value(),
+                 "thread-safe pass registration must succeed");
+  rcc::MachineAnalysisManager Prototype;
+  auto ParallelRun = Parallel.runFunctions(Unit, Target, Prototype, 4);
+  Context.expect(ParallelRun.has_value() && Runs == Unit.functionCount(),
+                 "parallel function execution must visit every function exactly once");
+
+  std::atomic<std::uint32_t> DuplicateRuns = 0;
+  rcc::MachinePassManager Repeated;
+  Context.expect(
+      Repeated.addPass(std::make_unique<ParallelCountingPass>(DuplicateRuns)).has_value() &&
+          Repeated.addPass(std::make_unique<ParallelCountingPass>(DuplicateRuns)).has_value() &&
+          Repeated.runFunctions(Unit, Target, Prototype, 4).has_value() &&
+          DuplicateRuns == Unit.functionCount() * 2,
+      "a pipeline must allow the same named pass to run more than once");
+
+  rcc::MachinePassInstrumentation Instrumentation;
+  std::vector<std::string> ObservedFunctions;
+  std::vector<std::size_t> BeforeBlockCounts;
+  std::vector<std::size_t> AfterBlockCounts;
+  Instrumentation.addBeforeCallback([&ObservedFunctions, &BeforeBlockCounts](
+                                        std::string_view, const rcc::MachineFunction &Function) {
+    ObservedFunctions.emplace_back(Function.name());
+    BeforeBlockCounts.push_back(Function.blockCount());
+  });
+  Instrumentation.addAfterCallback([&AfterBlockCounts](std::string_view,
+                                                       const rcc::MachineFunction &Function,
+                                                       const rcc::MachinePassResult &) {
+    AfterBlockCounts.push_back(Function.blockCount());
+  });
+  std::atomic<std::uint32_t> InstrumentedRuns = 0;
+  std::atomic<std::uint32_t> ActiveRuns = 0;
+  std::atomic<std::uint32_t> MaximumActiveRuns = 0;
+  rcc::MachinePassManager Instrumented;
+  Context.expect(
+      Instrumented
+              .addPass(std::make_unique<InstrumentedParallelPass>(InstrumentedRuns, ActiveRuns,
+                                                                  MaximumActiveRuns))
+              .has_value() &&
+          Instrumented.runFunctions(Unit, Target, Prototype, 4, &Instrumentation).has_value() &&
+          InstrumentedRuns == Unit.functionCount() && MaximumActiveRuns > 1,
+      "instrumented function pipelines must execute concurrently with a parallel request");
+  bool StableCallbackOrder = ObservedFunctions.size() == Unit.functionCount();
+  for (std::size_t Index = 0; StableCallbackOrder && Index < ObservedFunctions.size(); ++Index)
+    StableCallbackOrder = ObservedFunctions[Index] == "f" + std::to_string(Index);
+  Context.expect(StableCallbackOrder,
+                 "instrumentation callbacks must commit in stable compilation-unit order");
+  Context.expect(
+      BeforeBlockCounts.size() == Unit.functionCount() &&
+          AfterBlockCounts.size() == Unit.functionCount() &&
+          std::ranges::all_of(BeforeBlockCounts, [](std::size_t Count) { return Count == 0; }) &&
+          std::ranges::all_of(AfterBlockCounts, [](std::size_t Count) { return Count == 1; }),
+      "buffered instrumentation must retain distinct before/after IR snapshots");
+
+  rcc::MachineAnalysisManager UnsafePrototype;
+  Context.expect(UnsafePrototype
+                     .registerAnalysis<NonThreadSafeAnalysis>({
+                         .Name = "NonThreadSafe",
+                         .Dependencies = {},
+                         .InvalidatedBy = rcc::MachinePassChanges::all(),
+                         .ThreadSafety = rcc::PassThreadSafety::NotThreadSafe,
+                     })
+                     .has_value(),
+                 "non-thread-safe analysis registration must be explicit");
+  rcc::MachinePassManager UnsafeParallel;
+  Context.expect(
+      UnsafeParallel.addPass(std::make_unique<RequiresNonThreadSafeAnalysisPass>()).has_value() &&
+          !UnsafeParallel.runFunctions(Unit, Target, UnsafePrototype, 4),
+      "parallel pipelines must reject a required analysis not marked thread-safe");
+
+  rcc::CompilationUnitAnalysisManager UnitAnalyses;
+  Context.expect(UnitAnalyses
+                     .registerAnalysis<UnitFunctionCountAnalysis>({
+                         .Name = "UnitFunctionCount",
+                         .Dependencies = {},
+                         .InvalidatedBy = rcc::MachinePassChanges::all(),
+                     })
+                     .has_value(),
+                 "compilation-unit analysis registration must succeed");
+  rcc::MachineAnalysisManager FunctionAnalyses;
+  rcc::CompilationUnitPassManager UnitPipeline;
+  Context.expect(UnitPipeline.addPass(std::make_unique<ObserveUnitPass>()).has_value(),
+                 "compilation-unit pass registration must succeed");
+  rcc::MachinePassInstrumentation UnitInstrumentation;
+  std::uint32_t BeforeUnit = 0;
+  std::uint32_t AfterUnit = 0;
+  std::uint32_t BeforeUnitAnalysis = 0;
+  std::uint32_t AfterUnitAnalysis = 0;
+  std::uint32_t UnitAnalysisCacheHits = 0;
+  UnitInstrumentation.addBeforeUnitCallback(
+      [&BeforeUnit](std::string_view, const rcc::CompilationUnit &) { ++BeforeUnit; });
+  UnitInstrumentation.addAfterUnitCallback(
+      [&AfterUnit](std::string_view, const rcc::CompilationUnit &,
+                   const rcc::CompilationUnitPassResult &) { ++AfterUnit; });
+  UnitInstrumentation.addBeforeUnitAnalysisCallback(
+      [&BeforeUnitAnalysis](std::string_view, const rcc::CompilationUnit &) {
+        ++BeforeUnitAnalysis;
+      });
+  UnitInstrumentation.addAfterUnitAnalysisCallback(
+      [&AfterUnitAnalysis, &UnitAnalysisCacheHits](std::string_view, const rcc::CompilationUnit &,
+                                                   bool CacheHit, std::uint64_t) {
+        ++AfterUnitAnalysis;
+        UnitAnalysisCacheHits += CacheHit ? 1U : 0U;
+      });
+  Context.expect(
+      UnitPipeline.run(Unit, Target, UnitAnalyses, FunctionAnalyses, &UnitInstrumentation)
+          .has_value(),
+      "compilation-unit pass and analysis must run through their own manager");
+  Context.expect(BeforeUnit == 1 && AfterUnit == 1 && BeforeUnitAnalysis == 1 &&
+                     AfterUnitAnalysis == 2 && UnitAnalysisCacheHits == 1,
+                 "compilation-unit instrumentation must report pass and analysis cache events");
+
+  rcc::CompilationUnitAnalysisManager FailingUnitAnalyses;
+  Context.expect(FailingUnitAnalyses
+                     .registerAnalysis<FailingUnitAnalysis>({
+                         .Name = "FailingUnit",
+                         .Dependencies = {},
+                     })
+                     .has_value(),
+                 "failing compilation-unit analysis registration must succeed");
+  rcc::CompilationUnitPassManager FailingUnitAnalysisPipeline;
+  Context.expect(
+      FailingUnitAnalysisPipeline.addPass(std::make_unique<RequiresFailingUnitAnalysisPass>())
+          .has_value(),
+      "a pass requiring a failing unit analysis must register");
+  rcc::MachinePassInstrumentation FailingUnitInstrumentation;
+  std::uint32_t BeforeFailingUnitAnalysis = 0;
+  std::uint32_t FailingUnitAnalysisEvents = 0;
+  std::uint32_t RequiredUnitAnalysisPassFailures = 0;
+  FailingUnitInstrumentation.addBeforeUnitAnalysisCallback(
+      [&BeforeFailingUnitAnalysis](std::string_view, const rcc::CompilationUnit &) {
+        ++BeforeFailingUnitAnalysis;
+      });
+  FailingUnitInstrumentation.addUnitAnalysisFailureCallback(
+      [&FailingUnitAnalysisEvents](std::string_view, const rcc::CompilationUnit &,
+                                   const rcc::Error &) { ++FailingUnitAnalysisEvents; });
+  FailingUnitInstrumentation.addUnitFailureCallback(
+      [&RequiredUnitAnalysisPassFailures](std::string_view, const rcc::CompilationUnit &,
+                                          const rcc::Error &) {
+        ++RequiredUnitAnalysisPassFailures;
+      });
+  Context.expect(
+      !FailingUnitAnalysisPipeline.run(Unit, Target, FailingUnitAnalyses, FunctionAnalyses,
+                                       &FailingUnitInstrumentation) &&
+          BeforeFailingUnitAnalysis == 1 && FailingUnitAnalysisEvents == 1 &&
+          RequiredUnitAnalysisPassFailures == 1,
+      "unit analysis and pass failure instrumentation must report required-analysis failures");
+
+  rcc::MachineFunction *FirstFunction = Unit.functionAt(0);
+  Context.expect(
+      FirstFunction != nullptr &&
+          FunctionAnalyses
+              .registerAnalysis<BlockCountAnalysis>({
+                  .Name = "BlockCount",
+                  .Dependencies = {},
+                  .InvalidatedBy = rcc::MachinePassChanges::all(),
+              })
+              .has_value() &&
+          FunctionAnalyses.getResult<BlockCountAnalysis>(*FirstFunction, Target).has_value(),
+      "compilation-unit failure cache fixtures must materialize");
+  rcc::CompilationUnitPassManager FailingUnitPipeline;
+  Context.expect(
+      FirstFunction != nullptr &&
+          FailingUnitPipeline.addPass(std::make_unique<MutatingUnitFailurePass>()).has_value() &&
+          !FailingUnitPipeline.run(Unit, Target, UnitAnalyses, FunctionAnalyses) &&
+          !UnitAnalyses.hasCached(
+              Unit, rcc::CompilationUnitAnalysisManager::id<UnitFunctionCountAnalysis>()) &&
+          !FunctionAnalyses.hasCached(*FirstFunction,
+                                      rcc::MachineAnalysisManager::id<BlockCountAnalysis>()),
+      "a mutating compilation-unit failure must clear unit and function analysis caches");
+}
+
+} // namespace
+
+int main() {
+  TestContext Context;
+  auto Target = createTarget();
+  Context.expect(Target.has_value(), "machine pass tests require a valid target description");
+  if (!Target)
+    return Context.result();
+
+  testAnalysisInfrastructure(Context, *Target);
+  testPassAndInstrumentation(Context, *Target);
+  testCompilationUnitAndParallelism(Context, *Target);
+  return Context.result();
+}
diff --git a/backend/unittests/CodeGen/TargetCallLoweringTest.cpp b/backend/unittests/CodeGen/TargetCallLoweringTest.cpp
new file mode 100644
index 0000000..f826285
--- /dev/null
+++ b/backend/unittests/CodeGen/TargetCallLoweringTest.cpp
@@ -0,0 +1,329 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "rcc/CodeGen/TargetCallLowering.h"
+
+#include "Target/TestTarget.h"
+#include "rcc/CodeGen/InstructionDescriptor.h"
+#include "rcc/CodeGen/MachineFunction.h"
+#include "rcc/CodeGen/MachineIRBuilder.h"
+
+#include <concepts>
+#include <cstdint>
+#include <iostream>
+#include <memory>
+#include <span>
+#include <string_view>
+#include <utility>
+#include <vector>
+
+namespace {
+
+class TestContext final {
+public:
+  void expect(bool Condition, std::string_view Message) {
+    if (Condition)
+      return;
+    std::cerr << Message << '\n';
+    ++FailureCount;
+  }
+
+  [[nodiscard]] int result() const noexcept {
+    return FailureCount == 0 ? 0 : 1;
+  }
+
+private:
+  int FailureCount = 0;
+};
+
+[[nodiscard]] rcc::Alignment align(std::uint64_t Bytes) {
+  const auto Value = rcc::Alignment::create(Bytes);
+  if (!Value)
+    std::terminate();
+  return *Value;
+}
+
+[[nodiscard]] rcc::LLT integer(std::uint32_t Bits) {
+  const auto Type = rcc::LLT::makeInteger(Bits);
+  if (!Type)
+    std::terminate();
+  return *Type;
+}
+
+[[nodiscard]] rcc::PhysicalRegister physical(std::uint32_t ID) {
+  const auto Register = rcc::PhysicalRegister::create(ID);
+  if (!Register)
+    std::terminate();
+  return *Register;
+}
+
+[[nodiscard]] rcc::Expected<rcc::TargetDescription> createTarget() {
+  rcc::InstructionDescriptor Nop;
+  Nop.InstructionOpcode = rcc::Opcode::fromValue(1);
+  Nop.Name = "TEST_NOP";
+  Nop.Flags = {rcc::InstructionFlag::ProducesCode};
+  std::vector<rcc::InstructionDescriptor> Descriptors;
+  Descriptors.push_back(std::move(Nop));
+  auto Instructions = rcc::InstructionSet::create(std::move(Descriptors));
+  if (!Instructions)
+    return std::unexpected(Instructions.error());
+  return rcc::test::createTestTargetDescription(std::move(*Instructions));
+}
+
+[[nodiscard]] rcc::CallLoweringPlanDesc emptyPlanDescription(rcc::CallLoweringPlanKind Kind) {
+  rcc::CallLoweringPlanDesc Description;
+  Description.Kind = Kind;
+  Description.Target = "test-target:test-abi";
+  Description.Convention = rcc::CallingConventionID::fromValue(1);
+  Description.StackArguments.Align = align(8);
+  Description.CallFrame.Align = align(8);
+  if (Kind == rcc::CallLoweringPlanKind::Call) {
+    Description.CallFrame.EmitSetup = true;
+    Description.CallFrame.EmitDestroy = true;
+    Description.PreservedMask = rcc::test::createTestCallPreservedMask();
+    Description.Callee = *rcc::MachineCallTarget::externalSymbol("callee");
+    Description.CallSiteID = 1;
+  }
+  return Description;
+}
+
+[[nodiscard]] rcc::Expected<rcc::CallLoweringPlan> emptyPlan(rcc::CallLoweringPlanKind Kind) {
+  return rcc::CallLoweringPlan::create(emptyPlanDescription(Kind));
+}
+
+[[nodiscard]] rcc::CCAssignment registerAssignment() {
+  return {
+      .ValueIndex = 0,
+      .OriginalValue = rcc::Register::fromPhysical(physical(2)),
+      .OriginalValueIndex = 0,
+      .FragmentIndex = 0,
+      .FragmentCount = 1,
+      .ValueType = integer(64),
+      .LocationType = integer(64),
+      .LocationKind = rcc::CCLocationKind::Register,
+      .LocationRegister = physical(1),
+      .StackOffsetBytes = std::nullopt,
+      .LocationSizeBytes = 8,
+      .StackSlotSizeBytes = 8,
+      .LocationAlignment = align(8),
+      .Extension = rcc::ABIExtensionKind::None,
+      .CustomFlags = {},
+  };
+}
+
+void testPlanValidation(TestContext &Context) {
+  static_assert(
+      std::same_as<decltype(std::declval<const rcc::CallLoweringPlan &>().argumentAssignments()),
+                   std::span<const rcc::CCAssignment>>);
+  static_assert(std::same_as<decltype(std::declval<const rcc::CallLoweringPlan &>().byValCopies()),
+                             std::span<const rcc::ByValCopyAssignment>>);
+
+  auto Valid = emptyPlan(rcc::CallLoweringPlanKind::FormalArguments);
+  Context.expect(Valid && Valid->target() == "test-target:test-abi" &&
+                     Valid->argumentAssignments().empty(),
+                 "a valid immutable formal-argument plan must be accepted");
+
+  auto MissingRegister = emptyPlanDescription(rcc::CallLoweringPlanKind::FormalArguments);
+  auto Assignment = registerAssignment();
+  Assignment.OriginalValue = {};
+  MissingRegister.ArgumentAssignments.push_back(Assignment);
+  Context.expect(!rcc::CallLoweringPlan::create(std::move(MissingRegister)),
+                 "an assignment without a machine value must be rejected");
+
+  auto BadStack = emptyPlanDescription(rcc::CallLoweringPlanKind::FormalArguments);
+  BadStack.StackArguments.SizeBytes = 8;
+  auto StackAssignment = registerAssignment();
+  StackAssignment.LocationKind = rcc::CCLocationKind::Stack;
+  StackAssignment.LocationRegister.reset();
+  StackAssignment.StackOffsetBytes = 8;
+  BadStack.ArgumentAssignments.push_back(StackAssignment);
+  Context.expect(!rcc::CallLoweringPlan::create(std::move(BadStack)),
+                 "an assignment outside the declared stack area must be rejected");
+
+  auto Overlap = emptyPlanDescription(rcc::CallLoweringPlanKind::FormalArguments);
+  Overlap.StackArguments.SizeBytes = 16;
+  StackAssignment.StackOffsetBytes = 0;
+  Overlap.ArgumentAssignments.push_back(StackAssignment);
+  StackAssignment.OriginalValue = rcc::Register::fromPhysical(physical(3));
+  StackAssignment.StackOffsetBytes = 4;
+  Overlap.ArgumentAssignments.push_back(StackAssignment);
+  Context.expect(!rcc::CallLoweringPlan::create(std::move(Overlap)),
+                 "overlapping stack assignments must be rejected");
+
+  auto MisalignedStack = emptyPlanDescription(rcc::CallLoweringPlanKind::FormalArguments);
+  MisalignedStack.StackArguments.SizeBytes = 16;
+  StackAssignment.StackOffsetBytes = 4;
+  MisalignedStack.ArgumentAssignments.push_back(StackAssignment);
+  Context.expect(!rcc::CallLoweringPlan::create(std::move(MisalignedStack)),
+                 "a stack assignment must satisfy its declared alignment");
+
+  auto OversizedLocation = emptyPlanDescription(rcc::CallLoweringPlanKind::FormalArguments);
+  auto OversizedAssignment = registerAssignment();
+  OversizedAssignment.LocationSizeBytes = 16;
+  OversizedLocation.ArgumentAssignments.push_back(OversizedAssignment);
+  Context.expect(!rcc::CallLoweringPlan::create(std::move(OversizedLocation)),
+                 "an ABI location cannot exceed its transport slot");
+
+  auto UnknownLocation = emptyPlanDescription(rcc::CallLoweringPlanKind::FormalArguments);
+  auto UnknownAssignment = registerAssignment();
+  UnknownAssignment.LocationKind =
+      static_cast<rcc::CCLocationKind>(255); // NOLINT(clang-analyzer-optin.core.EnumCastOutOfRange)
+  UnknownLocation.ArgumentAssignments.push_back(UnknownAssignment);
+  Context.expect(!rcc::CallLoweringPlan::create(std::move(UnknownLocation)),
+                 "an unknown ABI location kind must be rejected");
+
+  auto BadFrame = emptyPlanDescription(rcc::CallLoweringPlanKind::Call);
+  BadFrame.CallFrame.EmitDestroy = false;
+  Context.expect(!rcc::CallLoweringPlan::create(std::move(BadFrame)),
+                 "unpaired call-frame setup and destroy requirements must be rejected");
+
+  auto SmallFrame = emptyPlanDescription(rcc::CallLoweringPlanKind::Call);
+  SmallFrame.StackArguments.SizeBytes = 16;
+  SmallFrame.CallFrame.SizeBytes = 8;
+  StackAssignment.StackOffsetBytes = 0;
+  SmallFrame.ArgumentAssignments.push_back(StackAssignment);
+  Context.expect(!rcc::CallLoweringPlan::create(std::move(SmallFrame)),
+                 "a call frame must contain its complete stack-argument area");
+
+  auto BadTail = emptyPlanDescription(rcc::CallLoweringPlanKind::Call);
+  BadTail.CallFrame.EmitSetup = false;
+  BadTail.CallFrame.EmitDestroy = false;
+  BadTail.CallFrame.ReusesIncomingArea = true;
+  BadTail.TailDecision = rcc::TailCallKind::Tail;
+  BadTail.TailRejectionReason = "inconsistent accepted tail call";
+  Context.expect(!rcc::CallLoweringPlan::create(std::move(BadTail)),
+                 "an accepted tail call cannot retain a rejection reason");
+
+  auto UnknownTail = emptyPlanDescription(rcc::CallLoweringPlanKind::Call);
+  UnknownTail.TailDecision =
+      static_cast<rcc::TailCallKind>(255); // NOLINT(clang-analyzer-optin.core.EnumCastOutOfRange)
+  Context.expect(!rcc::CallLoweringPlan::create(std::move(UnknownTail)),
+                 "an unknown tail-call decision must be rejected");
+
+  auto BadVarArgs = emptyPlanDescription(rcc::CallLoweringPlanKind::FormalArguments);
+  BadVarArgs.VarArgs.IsVariadic = true;
+  BadVarArgs.VarArgs.RegisterSaveAreaSizeBytes = 8;
+  BadVarArgs.VarArgs.RegistersToSave.push_back({physical(1), 8});
+  Context.expect(!rcc::CallLoweringPlan::create(std::move(BadVarArgs)),
+                 "a variadic register save outside its area must be rejected");
+
+  auto BadByVal = emptyPlanDescription(rcc::CallLoweringPlanKind::Call);
+  auto ByValAssignment = registerAssignment();
+  ByValAssignment.ValueType = *rcc::LLT::makePointer(0, 64);
+  ByValAssignment.LocationType = ByValAssignment.ValueType;
+  ByValAssignment.CustomFlags.set(rcc::CCAssignmentFlag::ByVal);
+  BadByVal.ArgumentAssignments.push_back(ByValAssignment);
+  BadByVal.ByValCopies.push_back(
+      {0, ByValAssignment.OriginalValue, ByValAssignment.ValueType, 0, 16, align(8)});
+  Context.expect(!rcc::CallLoweringPlan::create(std::move(BadByVal)),
+                 "a byval copy outside the call frame must be rejected");
+
+  auto OverlappingByVal = emptyPlanDescription(rcc::CallLoweringPlanKind::Call);
+  OverlappingByVal.CallFrame.SizeBytes = 32;
+  auto FirstByVal = registerAssignment();
+  FirstByVal.ValueType = *rcc::LLT::makePointer(0, 64);
+  FirstByVal.LocationType = FirstByVal.ValueType;
+  FirstByVal.CustomFlags.set(rcc::CCAssignmentFlag::ByVal);
+  auto SecondByVal = FirstByVal;
+  SecondByVal.ValueIndex = 1;
+  SecondByVal.OriginalValue = rcc::Register::fromPhysical(physical(3));
+  SecondByVal.OriginalValueIndex = 1;
+  SecondByVal.LocationRegister = physical(2);
+  OverlappingByVal.ArgumentAssignments = {FirstByVal, SecondByVal};
+  OverlappingByVal.ByValCopies = {
+      {0, FirstByVal.OriginalValue, FirstByVal.ValueType, 0, 16, align(8)},
+      {1, SecondByVal.OriginalValue, SecondByVal.ValueType, 8, 16, align(8)},
+  };
+  Context.expect(!rcc::CallLoweringPlan::create(std::move(OverlappingByVal)),
+                 "overlapping byval copy ranges must be rejected");
+
+  Context.expect(!rcc::MachineCallTarget::globalSymbol("") && !rcc::MachineCallTarget::indirect({}),
+                 "call-target factories must reject missing targets");
+}
+
+class RecordingCallLowering final : public rcc::TargetCallLowering {
+public:
+  enum class Behavior : std::uint8_t {
+    Valid,
+    PlannerFailure,
+    WrongKind,
+  };
+
+  explicit RecordingCallLowering(Behavior CurrentBehavior) : CurrentBehavior(CurrentBehavior) {}
+
+  [[nodiscard]] rcc::Expected<rcc::CallLoweringPlan>
+  planFormalArguments(const rcc::FormalArgumentRequest &) const override {
+    return plan(rcc::CallLoweringPlanKind::FormalArguments);
+  }
+
+  [[nodiscard]] rcc::Expected<rcc::CallLoweringPlan>
+  planCall(const rcc::CallLoweringRequest &) const override {
+    return plan(rcc::CallLoweringPlanKind::Call);
+  }
+
+  [[nodiscard]] rcc::Expected<rcc::CallLoweringPlan>
+  planReturn(const rcc::ReturnLoweringRequest &) const override {
+    return plan(rcc::CallLoweringPlanKind::Return);
+  }
+
+  [[nodiscard]] rcc::Expected<void> emitPlan(rcc::MachineIRBuilder &,
+                                             const rcc::CallLoweringPlan &) const override {
+    ++EmissionCount;
+    return {};
+  }
+
+  [[nodiscard]] std::uint32_t emissions() const noexcept {
+    return EmissionCount;
+  }
+
+private:
+  [[nodiscard]] rcc::Expected<rcc::CallLoweringPlan>
+  plan(rcc::CallLoweringPlanKind RequestedKind) const {
+    if (CurrentBehavior == Behavior::PlannerFailure) {
+      return rcc::makeUnexpected(rcc::ErrorCode::Unsupported,
+                                 "intentional call-lowering planner failure");
+    }
+    if (CurrentBehavior == Behavior::WrongKind)
+      RequestedKind = RequestedKind == rcc::CallLoweringPlanKind::Call
+                          ? rcc::CallLoweringPlanKind::Return
+                          : rcc::CallLoweringPlanKind::Call;
+    return emptyPlan(RequestedKind);
+  }
+
+  Behavior CurrentBehavior;
+  mutable std::uint32_t EmissionCount = 0;
+};
+
+void testPlanThenEmitBoundary(TestContext &Context) {
+  auto Target = createTarget();
+  auto Function =
+      rcc::MachineFunction::create("plan_then_emit", rcc::MachineFunctionStableID::fromValue(1));
+  Context.expect(Target && Function, "call-lowering workflow fixtures must be valid");
+  if (!Target || !Function)
+    return;
+  rcc::MachineIRBuilder Builder(**Function, *Target);
+  rcc::CallLoweringRequest Request;
+
+  RecordingCallLowering Failing(RecordingCallLowering::Behavior::PlannerFailure);
+  auto Failure = Failing.lowerCall(Builder, Request);
+  Context.expect(!Failure && Failing.emissions() == 0 && (*Function)->allInstructions().empty(),
+                 "planner failure must not invoke emission or mutate MachineIR");
+
+  RecordingCallLowering WrongKind(RecordingCallLowering::Behavior::WrongKind);
+  auto Mismatch = WrongKind.lowerCall(Builder, Request);
+  Context.expect(!Mismatch && Mismatch.error().code() == rcc::ErrorCode::InternalError &&
+                     WrongKind.emissions() == 0,
+                 "a target returning the wrong plan kind must be rejected before emission");
+
+  RecordingCallLowering Valid(RecordingCallLowering::Behavior::Valid);
+  Context.expect(Valid.lowerCall(Builder, Request) && Valid.emissions() == 1,
+                 "a valid plan must be emitted exactly once");
+}
+
+} // namespace
+
+int main() {
+  TestContext Context;
+  testPlanValidation(Context);
+  testPlanThenEmitBoundary(Context);
+  return Context.result();
+}
diff --git a/backend/unittests/Target/CMakeLists.txt b/backend/unittests/Target/CMakeLists.txt
index 1ceb1ef..aa45b90 100644
--- a/backend/unittests/Target/CMakeLists.txt
+++ b/backend/unittests/Target/CMakeLists.txt
@@ -23,14 +23,21 @@ rcc_backend_configure_target(RCCBackendRISCVTargetTests)
 target_link_libraries(RCCBackendRISCVTargetTests PRIVATE RCCBackend::RISCV)
 add_test(NAME RCCBackendRISCVTargetTests COMMAND RCCBackendRISCVTargetTests)
 
+add_executable(RCCBackendRISCVCallLoweringTests RISCVCallLoweringTest.cpp)
+rcc_backend_configure_target(RCCBackendRISCVCallLoweringTests)
+target_link_libraries(RCCBackendRISCVCallLoweringTests PRIVATE RCCBackend::RISCV)
+add_test(NAME RCCBackendRISCVCallLoweringTests COMMAND RCCBackendRISCVCallLoweringTests)
+
 rcc_backend_register_format_files(
   "${CMAKE_CURRENT_SOURCE_DIR}/DescriptionGeneratorTest.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/RISCVCallLoweringTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/RISCVTargetTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/TestTarget.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/TestTarget.h"
 )
 rcc_backend_register_tidy_files(
   "${CMAKE_CURRENT_SOURCE_DIR}/DescriptionGeneratorTest.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/RISCVCallLoweringTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/RISCVTargetTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/TestTarget.cpp"
 )
diff --git a/backend/unittests/Target/RISCVCallLoweringTest.cpp b/backend/unittests/Target/RISCVCallLoweringTest.cpp
new file mode 100644
index 0000000..0262bf5
--- /dev/null
+++ b/backend/unittests/Target/RISCVCallLoweringTest.cpp
@@ -0,0 +1,802 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "rcc/Target/RISCV/RISCVCallLowering.h"
+
+#include "rcc/CodeGen/MachineBasicBlock.h"
+#include "rcc/CodeGen/MachineFrameInfo.h"
+#include "rcc/CodeGen/MachineFunction.h"
+#include "rcc/CodeGen/MachineIRBuilder.h"
+#include "rcc/CodeGen/MachineInstr.h"
+#include "rcc/CodeGen/MachineMemOperand.h"
+#include "rcc/CodeGen/MachineOperand.h"
+#include "rcc/CodeGen/MachineVerifier.h"
+#include "rcc/Target/RISCV/RISCVTarget.h"
+
+#include <algorithm>
+#include <cstddef>
+#include <cstdint>
+#include <exception>
+#include <iostream>
+#include <memory>
+#include <optional>
+#include <ranges>
+#include <span>
+#include <string>
+#include <string_view>
+#include <utility>
+#include <vector>
+
+namespace {
+
+class TestContext final {
+public:
+  void expect(bool Condition, std::string_view Message) {
+    if (Condition)
+      return;
+    std::cerr << Message << '\n';
+    ++FailureCount;
+  }
+
+  [[nodiscard]] int result() const noexcept {
+    return FailureCount == 0 ? 0 : 1;
+  }
+
+private:
+  int FailureCount = 0;
+};
+
+[[nodiscard]] rcc::CallingConventionID convention() noexcept {
+  return rcc::riscv::callingConventionID(rcc::riscv::CallingConvention::LP64D);
+}
+
+[[nodiscard]] rcc::Alignment align(std::uint64_t Bytes) {
+  const auto Value = rcc::Alignment::create(Bytes);
+  if (!Value)
+    std::terminate();
+  return *Value;
+}
+
+[[nodiscard]] rcc::LLT integer(std::uint32_t Bits) {
+  const auto Type = rcc::LLT::makeInteger(Bits);
+  if (!Type)
+    std::terminate();
+  return *Type;
+}
+
+[[nodiscard]] rcc::LLT floating(rcc::FloatSemantics Semantics) {
+  const auto Type = rcc::LLT::makeFloat(Semantics);
+  if (!Type)
+    std::terminate();
+  return *Type;
+}
+
+[[nodiscard]] rcc::LLT pointer() {
+  const auto Type = rcc::LLT::makePointer(0, 64);
+  if (!Type)
+    std::terminate();
+  return *Type;
+}
+
+[[nodiscard]] rcc::PhysicalRegister physical(rcc::riscv::PhysicalRegisterID ID) {
+  const auto Register = rcc::riscv::physicalRegister(ID);
+  if (!Register)
+    std::terminate();
+  return *Register;
+}
+
+[[nodiscard]] rcc::PhysicalRegister argumentGPR(std::size_t Index) {
+  const auto *Convention = rcc::riscv::callingConvention(rcc::riscv::CallingConvention::LP64D);
+  if (Convention == nullptr || Index >= Convention->IntegerArgumentRegisters.size())
+    std::terminate();
+  return Convention->IntegerArgumentRegisters[Index];
+}
+
+[[nodiscard]] rcc::PhysicalRegister argumentFPR(std::size_t Index) {
+  const auto *Convention = rcc::riscv::callingConvention(rcc::riscv::CallingConvention::LP64D);
+  if (Convention == nullptr || Index >= Convention->FloatingArgumentRegisters.size())
+    std::terminate();
+  return Convention->FloatingArgumentRegisters[Index];
+}
+
+[[nodiscard]] rcc::PhysicalRegister returnGPR(std::size_t Index) {
+  const auto *Convention = rcc::riscv::callingConvention(rcc::riscv::CallingConvention::LP64D);
+  if (Convention == nullptr || Index >= Convention->IntegerReturnRegisters.size())
+    std::terminate();
+  return Convention->IntegerReturnRegisters[Index];
+}
+
+[[nodiscard]] rcc::PhysicalRegister returnFPR(std::size_t Index) {
+  const auto *Convention = rcc::riscv::callingConvention(rcc::riscv::CallingConvention::LP64D);
+  if (Convention == nullptr || Index >= Convention->FloatingReturnRegisters.size())
+    std::terminate();
+  return Convention->FloatingReturnRegisters[Index];
+}
+
+[[nodiscard]] rcc::Register planningRegister() {
+  return rcc::Register::fromPhysical(physical(rcc::riscv::PhysicalRegisterID::X5));
+}
+
+[[nodiscard]] rcc::ABIValue
+abiValue(rcc::LLT Type, std::uint32_t OriginalValue, rcc::Register Value = planningRegister(),
+         rcc::ABIExtensionKind Extension = rcc::ABIExtensionKind::None) {
+  const std::uint64_t Size = std::max<std::uint64_t>(1, (Type.scalarBitWidth() + 7U) / 8U);
+  return {
+      .Value = Value,
+      .Type = Type,
+      .OriginalValue = OriginalValue,
+      .FragmentIndex = 0,
+      .FragmentCount = 1,
+      .FragmentOffsetBytes = 0,
+      .OriginalAlignment = align(std::min<std::uint64_t>(Size, 8)),
+      .Extension = Extension,
+      .Flags = {},
+      .ByValSizeBytes = 0,
+      .ByValAlignment = align(1),
+  };
+}
+
+[[nodiscard]] std::vector<rcc::ABIValue> integerValues(std::size_t Count) {
+  std::vector<rcc::ABIValue> Values;
+  Values.reserve(Count);
+  for (std::size_t Index = 0; Index < Count; ++Index)
+    Values.push_back(abiValue(integer(64), static_cast<std::uint32_t>(Index)));
+  return Values;
+}
+
+[[nodiscard]] std::vector<rcc::ABIValue> floatingValues(std::size_t Count) {
+  std::vector<rcc::ABIValue> Values;
+  Values.reserve(Count);
+  for (std::size_t Index = 0; Index < Count; ++Index) {
+    Values.push_back(
+        abiValue(floating(rcc::FloatSemantics::IEEEDouble), static_cast<std::uint32_t>(Index)));
+  }
+  return Values;
+}
+
+[[nodiscard]] rcc::MachineCallTarget externalTarget() {
+  auto Target = rcc::MachineCallTarget::externalSymbol("callee");
+  if (!Target)
+    std::terminate();
+  return std::move(*Target);
+}
+
+[[nodiscard]] rcc::CallLoweringRequest callRequest(std::vector<rcc::ABIValue> Arguments,
+                                                   std::size_t FixedArgumentCount,
+                                                   bool IsVariadic = false) {
+  rcc::CallLoweringRequest Request;
+  Request.Convention = convention();
+  Request.Callee = externalTarget();
+  Request.Arguments = std::move(Arguments);
+  Request.FixedArgumentCount = FixedArgumentCount;
+  Request.CallSiteID = 17;
+  Request.IsVariadic = IsVariadic;
+  return Request;
+}
+
+[[nodiscard]] bool isLocation(const rcc::CCAssignment &Assignment, rcc::PhysicalRegister Register) {
+  return Assignment.LocationRegister && *Assignment.LocationRegister == Register;
+}
+
+void testIntegerAndFloatingAssignments(TestContext &Context) {
+  auto Integers = callRequest(integerValues(9), 9);
+  auto IntegerPlan = rcc::riscv::callLowering().planCall(Integers);
+  Context.expect(IntegerPlan.has_value(), "nine integer arguments must produce an LP64D call plan");
+  if (!IntegerPlan)
+    return;
+  const auto IntegerAssignments = IntegerPlan->argumentAssignments();
+  bool IntegerRegistersMatch = IntegerAssignments.size() == 9;
+  for (std::size_t Index = 0; IntegerRegistersMatch && Index < 8; ++Index)
+    IntegerRegistersMatch = isLocation(IntegerAssignments[Index], argumentGPR(Index));
+  Context.expect(IntegerRegistersMatch &&
+                     IntegerAssignments[8].LocationKind == rcc::CCLocationKind::Stack &&
+                     IntegerAssignments[8].StackOffsetBytes == 0 &&
+                     IntegerPlan->stackArguments().SizeBytes == 16 &&
+                     IntegerPlan->callFrame().SizeBytes == 16 &&
+                     IntegerPlan->callee()->targetFlags() ==
+                         static_cast<std::uint32_t>(rcc::riscv::CallTargetFlag::DirectCall),
+                 "LP64D integer arguments must use a0-a7 before a 16-byte stack area");
+
+  auto Floats = callRequest(floatingValues(17), 17);
+  auto FloatPlan = rcc::riscv::callLowering().planCall(Floats);
+  Context.expect(FloatPlan.has_value(),
+                 "seventeen floating arguments must produce an LP64D call plan");
+  if (!FloatPlan)
+    return;
+  const auto FloatAssignments = FloatPlan->argumentAssignments();
+  bool FloatingRegistersMatch = FloatAssignments.size() == 17;
+  for (std::size_t Index = 0; FloatingRegistersMatch && Index < 8; ++Index)
+    FloatingRegistersMatch = isLocation(FloatAssignments[Index], argumentFPR(Index));
+  for (std::size_t Index = 0; FloatingRegistersMatch && Index < 8; ++Index) {
+    FloatingRegistersMatch =
+        isLocation(FloatAssignments[Index + 8], argumentGPR(Index)) &&
+        FloatAssignments[Index + 8].CustomFlags.has(rcc::CCAssignmentFlag::Bitcast);
+  }
+  Context.expect(FloatingRegistersMatch &&
+                     FloatAssignments[16].LocationKind == rcc::CCLocationKind::Stack &&
+                     FloatAssignments[16].StackOffsetBytes == 0,
+                 "LP64D floating arguments must fall back from fa0-fa7 to a0-a7 and then stack");
+
+  auto FloatFragment = abiValue(floating(rcc::FloatSemantics::IEEEDouble), 0);
+  FloatFragment.FragmentCount = 2;
+  FloatFragment.OriginalAlignment = align(16);
+  auto IntegerFragment = abiValue(integer(64), 0);
+  IntegerFragment.FragmentIndex = 1;
+  IntegerFragment.FragmentCount = 2;
+  IntegerFragment.FragmentOffsetBytes = 8;
+  IntegerFragment.OriginalAlignment = align(16);
+  auto Mixed = callRequest({FloatFragment, IntegerFragment}, 1);
+  auto MixedPlan = rcc::riscv::callLowering().planCall(Mixed);
+  Context.expect(MixedPlan && MixedPlan->argumentAssignments().size() == 2 &&
+                     isLocation(MixedPlan->argumentAssignments()[0], argumentFPR(0)) &&
+                     isLocation(MixedPlan->argumentAssignments()[1], argumentGPR(0)),
+                 "a mixed floating/integer aggregate must use one FPR and one GPR");
+
+  auto Narrow = abiValue(integer(32), 0);
+  auto InvalidNarrow = callRequest({Narrow}, 1);
+  Context.expect(!rcc::riscv::callLowering().planCall(InvalidNarrow),
+                 "a narrow integer without an explicit ABI extension must be rejected");
+  Narrow.Extension = rcc::ABIExtensionKind::SignExtend;
+  auto ExtendedNarrow = callRequest({Narrow}, 1);
+  auto NarrowPlan = rcc::riscv::callLowering().planCall(ExtendedNarrow);
+  Context.expect(NarrowPlan && NarrowPlan->argumentAssignments()[0].LocationType == integer(64) &&
+                     NarrowPlan->argumentAssignments()[0].Extension ==
+                         rcc::ABIExtensionKind::SignExtend,
+                 "a narrow integer extension must be explicit in its LP64D assignment");
+}
+
+void testVariadicAssignments(TestContext &Context) {
+  auto FixedFloat = abiValue(floating(rcc::FloatSemantics::IEEEDouble), 0);
+  auto VariableFloat = abiValue(floating(rcc::FloatSemantics::IEEEDouble), 1);
+  auto Request = callRequest({FixedFloat, VariableFloat}, 1, true);
+  auto Plan = rcc::riscv::callLowering().planCall(Request);
+  Context.expect(
+      Plan && isLocation(Plan->argumentAssignments()[0], argumentFPR(0)) &&
+          isLocation(Plan->argumentAssignments()[1], argumentGPR(0)) &&
+          Plan->argumentAssignments()[1].CustomFlags.has(rcc::CCAssignmentFlag::Variadic) &&
+          Plan->argumentAssignments()[1].CustomFlags.has(rcc::CCAssignmentFlag::Bitcast),
+      "variadic floating arguments must use integer calling-convention transport");
+
+  auto FixedInteger = abiValue(integer(64), 0);
+  auto PairLow = abiValue(integer(64), 1);
+  PairLow.FragmentCount = 2;
+  PairLow.OriginalAlignment = align(16);
+  auto PairHigh = abiValue(integer(64), 1);
+  PairHigh.FragmentIndex = 1;
+  PairHigh.FragmentCount = 2;
+  PairHigh.FragmentOffsetBytes = 8;
+  PairHigh.OriginalAlignment = align(16);
+  auto PairRequest = callRequest({FixedInteger, PairLow, PairHigh}, 1, true);
+  auto PairPlan = rcc::riscv::callLowering().planCall(PairRequest);
+  Context.expect(PairPlan && isLocation(PairPlan->argumentAssignments()[0], argumentGPR(0)) &&
+                     isLocation(PairPlan->argumentAssignments()[1], argumentGPR(2)) &&
+                     isLocation(PairPlan->argumentAssignments()[2], argumentGPR(3)),
+                 "an aligned variadic pair must skip an odd GPR before assignment");
+
+  rcc::FormalArgumentRequest Formal;
+  Formal.Convention = convention();
+  Formal.Arguments = {FixedInteger};
+  Formal.FixedArgumentCount = 1;
+  Formal.IsVariadic = true;
+  auto FormalPlan = rcc::riscv::callLowering().planFormalArguments(Formal);
+  Context.expect(FormalPlan && FormalPlan->varArgs().IsVariadic &&
+                     FormalPlan->varArgs().FirstUnallocatedIntegerRegister == 1 &&
+                     FormalPlan->varArgs().RegisterSaveAreaSizeBytes == 56 &&
+                     FormalPlan->varArgs().RegisterSaveAreaOffsetBytes == -56 &&
+                     FormalPlan->varArgs().RegisterSavePaddingBytes == 8 &&
+                     FormalPlan->varArgs().RegistersToSave.size() == 7 &&
+                     FormalPlan->varArgs().RegistersToSave.front().Reg == argumentGPR(1) &&
+                     FormalPlan->varArgs().RegistersToSave.back().Reg == argumentGPR(7),
+                 "a variadic formal function must describe its GPR save area and padding");
+}
+
+void testSpecialArgumentsAndReturns(TestContext &Context) {
+  auto ByVal = abiValue(pointer(), 0);
+  ByVal.Flags.set(rcc::ABIValueFlag::ByVal);
+  ByVal.ByValSizeBytes = 24;
+  ByVal.ByValAlignment = align(16);
+  auto ByValRequest = callRequest({ByVal}, 1);
+  auto ByValPlan = rcc::riscv::callLowering().planCall(ByValRequest);
+  Context.expect(
+      ByValPlan && ByValPlan->byValCopies().size() == 1 &&
+          ByValPlan->byValCopies()[0].StackOffsetBytes == 0 &&
+          ByValPlan->callFrame().SizeBytes == 32 &&
+          ByValPlan->argumentAssignments()[0].CustomFlags.has(rcc::CCAssignmentFlag::ByVal),
+      "byval must allocate an aligned caller-owned copy and pass its pointer");
+
+  auto SRet = abiValue(pointer(), 0);
+  SRet.Flags.set(rcc::ABIValueFlag::StructReturn);
+  auto SRetPlan = rcc::riscv::callLowering().planCall(callRequest({SRet}, 1));
+  Context.expect(
+      SRetPlan && isLocation(SRetPlan->argumentAssignments()[0], argumentGPR(0)) &&
+          SRetPlan->argumentAssignments()[0].CustomFlags.has(rcc::CCAssignmentFlag::StructReturn),
+      "sret must be carried as the first integer argument");
+  auto SRetWithDirectResult = callRequest({SRet}, 1);
+  SRetWithDirectResult.Results = {abiValue(integer(64), 0)};
+  Context.expect(!rcc::riscv::callLowering().planCall(SRetWithDirectResult),
+                 "an sret call cannot also expose direct ABI return registers");
+  auto Plain = abiValue(integer(64), 0);
+  SRet.OriginalValue = 1;
+  Context.expect(!rcc::riscv::callLowering().planCall(callRequest({Plain, SRet}, 2)),
+                 "sret outside the first argument position must be rejected");
+
+  auto Indirect = abiValue(pointer(), 0);
+  Indirect.Flags.set(rcc::ABIValueFlag::Indirect);
+  auto IndirectPlan = rcc::riscv::callLowering().planCall(callRequest({Indirect}, 1));
+  Context.expect(
+      IndirectPlan &&
+          IndirectPlan->argumentAssignments()[0].LocationKind == rcc::CCLocationKind::Indirect &&
+          IndirectPlan->argumentAssignments()[0].CustomFlags.has(rcc::CCAssignmentFlag::Indirect),
+      "an explicitly indirect ABI value must preserve its transport classification");
+
+  auto InRegister = integerValues(9);
+  InRegister.back().Flags.set(rcc::ABIValueFlag::InRegister);
+  Context.expect(!rcc::riscv::callLowering().planCall(callRequest(std::move(InRegister), 9)),
+                 "an inreg argument that would spill to the stack must be rejected");
+
+  rcc::ReturnLoweringRequest Return;
+  Return.Convention = convention();
+  Return.Values = {abiValue(integer(64), 0),
+                   abiValue(floating(rcc::FloatSemantics::IEEEDouble), 1)};
+  auto ReturnPlan = rcc::riscv::callLowering().planReturn(Return);
+  Context.expect(ReturnPlan && ReturnPlan->returnAssignments().size() == 2 &&
+                     isLocation(ReturnPlan->returnAssignments()[0], returnGPR(0)) &&
+                     isLocation(ReturnPlan->returnAssignments()[1], returnFPR(0)),
+                 "mixed integer and floating returns must use a0 and fa0 independently");
+}
+
+[[nodiscard]] rcc::TailCallContext emptyTailContext() {
+  rcc::TailCallContext Context;
+  Context.CallerConvention = convention();
+  Context.ReusableIncomingArgumentBytes = 0;
+  Context.CallerFixedArgumentCount = 0;
+  return Context;
+}
+
+void testTailCalls(TestContext &Context) {
+  auto Tail = callRequest({}, 0);
+  Tail.TailKind = rcc::TailCallKind::Tail;
+  Tail.TailContext = emptyTailContext();
+  auto TailPlan = rcc::riscv::callLowering().planCall(Tail);
+  Context.expect(TailPlan && TailPlan->tailDecision() == rcc::TailCallKind::Tail &&
+                     TailPlan->callFrame().ReusesIncomingArea && !TailPlan->callFrame().EmitSetup,
+                 "an ABI-compatible tail call must reuse the incoming argument area");
+
+  auto Fallback = callRequest({}, 0);
+  Fallback.TailKind = rcc::TailCallKind::Tail;
+  auto FallbackPlan = rcc::riscv::callLowering().planCall(Fallback);
+  Context.expect(FallbackPlan && FallbackPlan->tailDecision() == rcc::TailCallKind::NotTail &&
+                     !FallbackPlan->tailRejectionReason().empty() &&
+                     FallbackPlan->callFrame().EmitSetup,
+                 "a non-mandatory incompatible tail call must fall back with a reason");
+
+  auto MustTail = callRequest({}, 0);
+  MustTail.TailKind = rcc::TailCallKind::MustTail;
+  auto MustTailPlan = rcc::riscv::callLowering().planCall(MustTail);
+  Context.expect(!MustTailPlan && MustTailPlan.error().code() == rcc::ErrorCode::Unsupported,
+                 "an incompatible musttail call must fail instead of falling back");
+
+  auto StackTail = callRequest(integerValues(9), 9);
+  StackTail.TailKind = rcc::TailCallKind::Tail;
+  auto StackContext = emptyTailContext();
+  StackContext.CallerFixedArgumentCount = 9;
+  StackContext.ReusableIncomingArgumentBytes = 16;
+  StackTail.TailContext = std::move(StackContext);
+  auto StackTailPlan = rcc::riscv::callLowering().planCall(StackTail);
+  Context.expect(StackTailPlan && StackTailPlan->tailDecision() == rcc::TailCallKind::Tail &&
+                     StackTailPlan->callFrame().SizeBytes == 16,
+                 "a tail call may reuse a sufficiently large incoming stack argument area");
+}
+
+[[nodiscard]] std::unique_ptr<rcc::MachineFunction> createFunction(TestContext &Context,
+                                                                   std::string Name,
+                                                                   std::uint64_t ID,
+                                                                   rcc::MachineBasicBlock *&Block) {
+  auto Function =
+      rcc::MachineFunction::create(std::move(Name), rcc::MachineFunctionStableID::fromValue(ID));
+  Context.expect(Function.has_value(), "machine function creation must succeed");
+  if (!Function)
+    return nullptr;
+  auto CreatedBlock = (*Function)->createBasicBlock();
+  Context.expect(CreatedBlock && (*Function)->appendBlock(**CreatedBlock),
+                 "machine entry block creation must succeed");
+  if (!CreatedBlock || !(*Function)->firstBlock())
+    return nullptr;
+  Block = *CreatedBlock;
+  return std::move(*Function);
+}
+
+[[nodiscard]] rcc::Register virtualRegister(rcc::MachineFunction &Function, rcc::LLT Type) {
+  auto Register = Function.registerInfo().createVirtualRegister(Type);
+  if (!Register)
+    std::terminate();
+  return *Register;
+}
+
+[[nodiscard]] rcc::Opcode opcode(rcc::riscv::InstructionOpcode Opcode) noexcept {
+  return rcc::Opcode::fromValue(static_cast<std::uint32_t>(Opcode));
+}
+
+[[nodiscard]] std::vector<rcc::MachineInstr *> instructions(rcc::MachineBasicBlock &Block) {
+  std::vector<rcc::MachineInstr *> Result;
+  for (rcc::MachineInstr *Instruction = Block.firstInstruction(); Instruction != nullptr;
+       Instruction = Instruction->next()) {
+    Result.push_back(Instruction);
+  }
+  return Result;
+}
+
+[[nodiscard]] rcc::MachineInstr *findInstruction(rcc::MachineBasicBlock &Block,
+                                                 rcc::riscv::InstructionOpcode OpcodeValue) {
+  for (rcc::MachineInstr *Instruction = Block.firstInstruction(); Instruction != nullptr;
+       Instruction = Instruction->next()) {
+    if (Instruction->opcode() == opcode(OpcodeValue))
+      return Instruction;
+  }
+  return nullptr;
+}
+
+[[nodiscard]] bool verifyFunction(const rcc::MachineFunction &Function,
+                                  const rcc::TargetDescription &Target) {
+  rcc::MachineVerifierOptions Options;
+  Options.VerifyProperties = false;
+  return rcc::MachineVerifier::verify(Function, Target, Options).has_value();
+}
+
+void testOrdinaryAndIndirectEmission(TestContext &Context) {
+  auto Target = rcc::riscv::createTargetDescription();
+  rcc::MachineBasicBlock *Block = nullptr;
+  auto Function = createFunction(Context, "ordinary_call", 1, Block);
+  Context.expect(Target && Function && Block != nullptr, "ordinary-call fixtures must be valid");
+  if (!Target || !Function || Block == nullptr)
+    return;
+
+  const rcc::LLT I64 = integer(64);
+  const rcc::LLT F64 = floating(rcc::FloatSemantics::IEEEDouble);
+  const rcc::Register Argument = virtualRegister(*Function, I64);
+  const rcc::Register Result = virtualRegister(*Function, F64);
+  auto Request = callRequest({abiValue(I64, 0, Argument)}, 1);
+  Request.Results = {abiValue(F64, 0, Result)};
+
+  rcc::MachineIRBuilder Builder(*Function, *Target);
+  Context.expect(Builder.setInsertPoint(*Block).has_value(),
+                 "ordinary-call insertion point must be valid");
+  auto Lowered = rcc::riscv::callLowering().lowerCall(Builder, Request);
+  Context.expect(Lowered.has_value(), "ordinary direct call emission must succeed");
+  if (!Lowered)
+    return;
+
+  const auto Instructions = instructions(*Block);
+  rcc::MachineInstr *Call = findInstruction(*Block, rcc::riscv::InstructionOpcode::PseudoCALL);
+  Context.expect(Instructions.size() == 5 &&
+                     Instructions.front()->opcode() ==
+                         opcode(rcc::riscv::InstructionOpcode::ADJCALLSTACKDOWN) &&
+                     Instructions.back()->opcode() ==
+                         opcode(rcc::riscv::InstructionOpcode::PseudoCC_COPY) &&
+                     Call != nullptr && Call->operandCount() >= 6 &&
+                     Call->operandAt(0)->kind() == rcc::MachineOperand::Kind::ExternalSymbol &&
+                     Call->operandAt(0)->targetFlags() ==
+                         static_cast<std::uint32_t>(rcc::riscv::CallTargetFlag::DirectCall) &&
+                     Call->operandAt(1)->kind() == rcc::MachineOperand::Kind::IntegerImmediate &&
+                     Call->operandAt(2)->kind() == rcc::MachineOperand::Kind::RegisterMask,
+                 "ordinary emission must materialize call-frame, copies, target, ID, and RegMask");
+  bool HasArgumentUse = false;
+  bool HasResultDef = false;
+  for (const rcc::MachineOperand &Operand : Call->operands()) {
+    if (!Operand.isRegister() || !Operand.isImplicit())
+      continue;
+    HasArgumentUse |=
+        Operand.isUse() && Operand.registerValue() == rcc::Register::fromPhysical(argumentGPR(0));
+    HasResultDef |=
+        Operand.isDef() && Operand.registerValue() == rcc::Register::fromPhysical(returnFPR(0));
+  }
+  Context.expect(HasArgumentUse && HasResultDef && Function->frameInfo().state().HasCalls &&
+                     Function->frameInfo().maxCallFrameSize() == 0 &&
+                     Function->frameInfo().stackAlignment().bytes() == 16 &&
+                     verifyFunction(*Function, *Target),
+                 "ordinary call emission must record implicit ABI registers and valid frame state");
+
+  rcc::MachineBasicBlock *IndirectBlock = nullptr;
+  auto IndirectFunction = createFunction(Context, "indirect_call", 2, IndirectBlock);
+  if (!IndirectFunction || IndirectBlock == nullptr)
+    return;
+  const rcc::Register Callee = virtualRegister(*IndirectFunction, pointer());
+  auto IndirectTarget = rcc::MachineCallTarget::indirect(Callee);
+  if (!IndirectTarget)
+    return;
+  auto IndirectRequest = callRequest({}, 0);
+  IndirectRequest.Callee = std::move(*IndirectTarget);
+  rcc::MachineIRBuilder IndirectBuilder(*IndirectFunction, *Target);
+  if (!IndirectBuilder.setInsertPoint(*IndirectBlock))
+    return;
+  auto IndirectLowered = rcc::riscv::callLowering().lowerCall(IndirectBuilder, IndirectRequest);
+  rcc::MachineInstr *IndirectCall =
+      findInstruction(*IndirectBlock, rcc::riscv::InstructionOpcode::PseudoCALL);
+  Context.expect(IndirectLowered && IndirectCall != nullptr &&
+                     IndirectCall->operandAt(0)->registerValue() == Callee &&
+                     verifyFunction(*IndirectFunction, *Target),
+                 "indirect call emission must retain the callee register operand");
+}
+
+void testStackAndByValEmission(TestContext &Context) {
+  auto Target = rcc::riscv::createTargetDescription();
+  rcc::MachineBasicBlock *Block = nullptr;
+  auto Function = createFunction(Context, "stack_byval_call", 3, Block);
+  if (!Target || !Function || Block == nullptr)
+    return;
+
+  std::vector<rcc::ABIValue> Arguments;
+  const rcc::Register ByValSource = virtualRegister(*Function, pointer());
+  auto ByVal = abiValue(pointer(), 0, ByValSource);
+  ByVal.Flags.set(rcc::ABIValueFlag::ByVal);
+  ByVal.ByValSizeBytes = 24;
+  ByVal.ByValAlignment = align(16);
+  Arguments.push_back(ByVal);
+  for (std::uint32_t Index = 1; Index < 9; ++Index) {
+    Arguments.push_back(abiValue(integer(64), Index, virtualRegister(*Function, integer(64))));
+  }
+  auto Request = callRequest(std::move(Arguments), 9);
+  rcc::MachineIRBuilder Builder(*Function, *Target);
+  if (!Builder.setInsertPoint(*Block))
+    return;
+  auto Lowered = rcc::riscv::callLowering().lowerCall(Builder, Request);
+  rcc::MachineInstr *ByValCopy =
+      findInstruction(*Block, rcc::riscv::InstructionOpcode::PseudoBYVAL_COPY);
+  rcc::MachineInstr *StackStore =
+      findInstruction(*Block, rcc::riscv::InstructionOpcode::PseudoSTORE_STACK_ARG);
+  bool HasByValObject = false;
+  bool HasOutgoingObject = false;
+  for (const rcc::StackObject &Object : Function->frameInfo().objects()) {
+    const rcc::StackObjectDesc *Description = Object.description();
+    if (Description == nullptr)
+      continue;
+    HasByValObject |= Description->Kind == rcc::StackObjectKind::Target &&
+                      Description->TargetFlags ==
+                          static_cast<std::uint64_t>(rcc::riscv::CallStackObjectFlag::ByValCopy);
+    HasOutgoingObject |=
+        Description->Kind == rcc::StackObjectKind::Target &&
+        Description->TargetFlags ==
+            static_cast<std::uint64_t>(rcc::riscv::CallStackObjectFlag::OutgoingArgument);
+  }
+  Context.expect(
+      Lowered && ByValCopy != nullptr && ByValCopy->memOperands().size() == 2 &&
+          ByValCopy->memOperands()[0]->isLoad() && ByValCopy->memOperands()[1]->isStore() &&
+          StackStore != nullptr && StackStore->memOperands().size() == 1 &&
+          StackStore->memOperands()[0]->isStore() && HasByValObject && HasOutgoingObject &&
+          Function->frameInfo().liveObjectCount() == 2 &&
+          Function->frameInfo().maxCallFrameSize() == 48 && verifyFunction(*Function, *Target),
+      "stack and byval emission must create precise objects, MMOs, and frame size");
+}
+
+void testFormalReturnAndTailEmission(TestContext &Context) {
+  auto Target = rcc::riscv::createTargetDescription();
+  if (!Target)
+    return;
+
+  rcc::MachineBasicBlock *FormalBlock = nullptr;
+  auto FormalFunction = createFunction(Context, "variadic_formal", 4, FormalBlock);
+  if (!FormalFunction || FormalBlock == nullptr)
+    return;
+  const rcc::Register FormalValue = virtualRegister(*FormalFunction, integer(64));
+  rcc::FormalArgumentRequest Formal;
+  Formal.Convention = convention();
+  Formal.Arguments = {abiValue(integer(64), 0, FormalValue)};
+  Formal.FixedArgumentCount = 1;
+  Formal.IsVariadic = true;
+  rcc::MachineIRBuilder FormalBuilder(*FormalFunction, *Target);
+  if (!FormalBuilder.setInsertPoint(*FormalBlock))
+    return;
+  auto FormalLowered = rcc::riscv::callLowering().lowerFormalArguments(FormalBuilder, Formal);
+  std::size_t SaveStores = 0;
+  for (rcc::MachineInstr *Instruction : instructions(*FormalBlock)) {
+    if (Instruction->opcode() == opcode(rcc::riscv::InstructionOpcode::PseudoSTORE_STACK_ARG))
+      ++SaveStores;
+  }
+  bool HasSaveArea = false;
+  bool HasPadding = false;
+  for (const rcc::StackObject &Object : FormalFunction->frameInfo().objects()) {
+    const rcc::StackObjectDesc *Description = Object.description();
+    if (Description == nullptr)
+      continue;
+    HasSaveArea |= Description->TargetFlags ==
+                   static_cast<std::uint64_t>(rcc::riscv::CallStackObjectFlag::VarArgSaveArea);
+    HasPadding |=
+        Description->TargetFlags ==
+        static_cast<std::uint64_t>(rcc::riscv::CallStackObjectFlag::VarArgAlignmentPadding);
+  }
+  Context.expect(FormalLowered && SaveStores == 7 && HasSaveArea && HasPadding &&
+                     FormalFunction->registerInfo().liveIns().size() == 8 &&
+                     FormalBlock->liveIns().size() == 8 && verifyFunction(*FormalFunction, *Target),
+                 "variadic formal emission must save remaining GPRs with explicit padding");
+
+  rcc::MachineBasicBlock *ReturnBlock = nullptr;
+  auto ReturnFunction = createFunction(Context, "return_value", 5, ReturnBlock);
+  if (!ReturnFunction || ReturnBlock == nullptr)
+    return;
+  const rcc::Register ReturnValue = virtualRegister(*ReturnFunction, integer(64));
+  rcc::ReturnLoweringRequest Return;
+  Return.Convention = convention();
+  Return.Values = {abiValue(integer(64), 0, ReturnValue)};
+  rcc::MachineIRBuilder ReturnBuilder(*ReturnFunction, *Target);
+  if (!ReturnBuilder.setInsertPoint(*ReturnBlock))
+    return;
+  auto ReturnLowered = rcc::riscv::callLowering().lowerReturn(ReturnBuilder, Return);
+  rcc::MachineInstr *ReturnPseudo =
+      findInstruction(*ReturnBlock, rcc::riscv::InstructionOpcode::PseudoRET);
+  bool HasReturnRegister = false;
+  if (ReturnPseudo != nullptr) {
+    HasReturnRegister = std::ranges::any_of(ReturnPseudo->operands(), [](const auto &Operand) {
+      return Operand.isRegister() && Operand.isImplicit() && Operand.isUse() &&
+             Operand.registerValue() == rcc::Register::fromPhysical(returnGPR(0));
+    });
+  }
+  Context.expect(ReturnLowered && instructions(*ReturnBlock).size() == 2 &&
+                     ReturnPseudo != nullptr && HasReturnRegister &&
+                     verifyFunction(*ReturnFunction, *Target),
+                 "return emission must copy into a0 and record its implicit PseudoRET use");
+
+  rcc::MachineBasicBlock *TailBlock = nullptr;
+  auto TailFunction = createFunction(Context, "tail_call", 6, TailBlock);
+  if (!TailFunction || TailBlock == nullptr)
+    return;
+  auto Tail = callRequest({}, 0);
+  Tail.TailKind = rcc::TailCallKind::Tail;
+  Tail.TailContext = emptyTailContext();
+  rcc::MachineIRBuilder TailBuilder(*TailFunction, *Target);
+  if (!TailBuilder.setInsertPoint(*TailBlock))
+    return;
+  auto TailLowered = rcc::riscv::callLowering().lowerCall(TailBuilder, Tail);
+  Context.expect(TailLowered && instructions(*TailBlock).size() == 1 &&
+                     TailBlock->firstInstruction()->opcode() ==
+                         opcode(rcc::riscv::InstructionOpcode::PseudoTAIL) &&
+                     TailFunction->frameInfo().state().HasCalls &&
+                     TailFunction->frameInfo().state().HasTailCall &&
+                     !TailFunction->frameInfo().state().AdjustsStack &&
+                     verifyFunction(*TailFunction, *Target),
+                 "tail emission must avoid a private call frame and mark function frame state");
+
+  rcc::MachineBasicBlock *StackTailBlock = nullptr;
+  auto StackTailFunction = createFunction(Context, "stack_tail_call", 8, StackTailBlock);
+  if (!StackTailFunction || StackTailBlock == nullptr)
+    return;
+  std::vector<rcc::ABIValue> StackTailArguments;
+  StackTailArguments.reserve(9);
+  for (std::uint32_t Index = 0; Index < 9; ++Index) {
+    StackTailArguments.push_back(
+        abiValue(integer(64), Index, virtualRegister(*StackTailFunction, integer(64))));
+  }
+  auto StackTail = callRequest(std::move(StackTailArguments), 9);
+  StackTail.TailKind = rcc::TailCallKind::Tail;
+  auto StackTailContext = emptyTailContext();
+  StackTailContext.CallerFixedArgumentCount = 9;
+  StackTailContext.ReusableIncomingArgumentBytes = 16;
+  StackTail.TailContext = std::move(StackTailContext);
+  rcc::MachineIRBuilder StackTailBuilder(*StackTailFunction, *Target);
+  if (!StackTailBuilder.setInsertPoint(*StackTailBlock))
+    return;
+  auto StackTailLowered = rcc::riscv::callLowering().lowerCall(StackTailBuilder, StackTail);
+  Context.expect(
+      StackTailLowered &&
+          findInstruction(*StackTailBlock, rcc::riscv::InstructionOpcode::PseudoSTORE_STACK_ARG) !=
+              nullptr &&
+          findInstruction(*StackTailBlock, rcc::riscv::InstructionOpcode::ADJCALLSTACKDOWN) ==
+              nullptr &&
+          StackTailFunction->frameInfo().state().HasTailCall &&
+          !StackTailFunction->frameInfo().state().AdjustsStack &&
+          verifyFunction(*StackTailFunction, *Target),
+      "a stack-argument tail call must reuse fixed incoming slots without claiming an SP change");
+}
+
+void testFormalStackAlignmentAndPreflight(TestContext &Context) {
+  auto Target = rcc::riscv::createTargetDescription();
+  if (!Target)
+    return;
+
+  rcc::MachineBasicBlock *StackBlock = nullptr;
+  auto StackFunction = createFunction(Context, "stack_formal", 9, StackBlock);
+  if (!StackFunction || StackBlock == nullptr)
+    return;
+  std::vector<rcc::ABIValue> StackArguments;
+  StackArguments.reserve(9);
+  for (std::uint32_t Index = 0; Index < 9; ++Index) {
+    StackArguments.push_back(
+        abiValue(integer(64), Index, virtualRegister(*StackFunction, integer(64))));
+  }
+  rcc::FormalArgumentRequest StackRequest;
+  StackRequest.Convention = convention();
+  StackRequest.Arguments = std::move(StackArguments);
+  StackRequest.FixedArgumentCount = 9;
+  rcc::MachineIRBuilder StackBuilder(*StackFunction, *Target);
+  if (!StackBuilder.setInsertPoint(*StackBlock))
+    return;
+  auto StackLowered = rcc::riscv::callLowering().lowerFormalArguments(StackBuilder, StackRequest);
+  bool HasIncomingObject = false;
+  for (const rcc::StackObject &Object : StackFunction->frameInfo().objects()) {
+    const rcc::StackObjectDesc *Description = Object.description();
+    HasIncomingObject |=
+        Description != nullptr && Description->Kind == rcc::StackObjectKind::FixedABI &&
+        Description->Align.bytes() == 8 && Description->Offset == 0 &&
+        Description->TargetFlags ==
+            static_cast<std::uint64_t>(rcc::riscv::CallStackObjectFlag::IncomingArgument);
+  }
+  Context.expect(
+      StackLowered && StackFunction->frameInfo().liveObjectCount() == 1 && HasIncomingObject &&
+          StackFunction->frameInfo().stackAlignment().bytes() == 8 &&
+          findInstruction(*StackBlock, rcc::riscv::InstructionOpcode::PseudoLOAD_STACK_ARG) !=
+              nullptr &&
+          verifyFunction(*StackFunction, *Target),
+      "non-variadic stack formals must publish fixed objects and maximum frame alignment");
+
+  rcc::MachineBasicBlock *ConflictBlock = nullptr;
+  auto ConflictFunction = createFunction(Context, "conflicting_formal", 10, ConflictBlock);
+  if (!ConflictFunction || ConflictBlock == nullptr)
+    return;
+  const rcc::Register Existing = virtualRegister(*ConflictFunction, integer(64));
+  const rcc::Register First = virtualRegister(*ConflictFunction, integer(64));
+  const rcc::Register Second = virtualRegister(*ConflictFunction, integer(64));
+  const rcc::PhysicalRegister ConflictingRegister = argumentGPR(1);
+  if (!ConflictFunction->registerInfo().addLiveIn(ConflictingRegister, Existing) ||
+      !ConflictBlock->addLiveIn(ConflictingRegister, rcc::LaneMask::all())) {
+    Context.expect(false, "formal live-in conflict fixture must be valid");
+    return;
+  }
+  rcc::FormalArgumentRequest ConflictRequest;
+  ConflictRequest.Convention = convention();
+  ConflictRequest.Arguments = {abiValue(integer(64), 0, First), abiValue(integer(64), 1, Second)};
+  ConflictRequest.FixedArgumentCount = 2;
+  rcc::MachineIRBuilder ConflictBuilder(*ConflictFunction, *Target);
+  if (!ConflictBuilder.setInsertPoint(*ConflictBlock))
+    return;
+  auto ConflictLowered =
+      rcc::riscv::callLowering().lowerFormalArguments(ConflictBuilder, ConflictRequest);
+  Context.expect(
+      !ConflictLowered && ConflictBlock->instructionCount() == 0 &&
+          ConflictFunction->allInstructions().empty() &&
+          ConflictFunction->registerInfo().liveIns().size() == 1 &&
+          ConflictBlock->liveIns().size() == 1 &&
+          ConflictFunction->frameInfo().liveObjectCount() == 0,
+      "formal live-in conflicts must fail preflight without partially modifying MachineIR");
+}
+
+void testPlanningFailureDoesNotMutate(TestContext &Context) {
+  auto Target = rcc::riscv::createTargetDescription();
+  rcc::MachineBasicBlock *Block = nullptr;
+  auto Function = createFunction(Context, "failed_call", 7, Block);
+  if (!Target || !Function || Block == nullptr)
+    return;
+  const rcc::Register Value = virtualRegister(*Function, integer(32));
+  auto Request = callRequest({abiValue(integer(32), 0, Value)}, 1);
+  rcc::MachineIRBuilder Builder(*Function, *Target);
+  if (!Builder.setInsertPoint(*Block))
+    return;
+  auto Lowered = rcc::riscv::callLowering().lowerCall(Builder, Request);
+  auto UnknownPhysical = rcc::PhysicalRegister::create(999);
+  auto UnknownRequest =
+      UnknownPhysical
+          ? callRequest({abiValue(integer(64), 0, rcc::Register::fromPhysical(*UnknownPhysical))},
+                        1)
+          : rcc::CallLoweringRequest{};
+  auto UnknownLowered = UnknownPhysical
+                            ? rcc::riscv::callLowering().lowerCall(Builder, UnknownRequest)
+                            : rcc::Expected<void>{std::unexpected(UnknownPhysical.error())};
+  Context.expect(!Lowered && !UnknownLowered && Block->instructionCount() == 0 &&
+                     Function->allInstructions().empty() &&
+                     Function->frameInfo().liveObjectCount() == 0,
+                 "RISC-V planning and preflight failures must leave MachineIR and frame state "
+                 "untouched");
+}
+
+} // namespace
+
+int main() {
+  TestContext Context;
+  testIntegerAndFloatingAssignments(Context);
+  testVariadicAssignments(Context);
+  testSpecialArgumentsAndReturns(Context);
+  testTailCalls(Context);
+  testOrdinaryAndIndirectEmission(Context);
+  testStackAndByValEmission(Context);
+  testFormalReturnAndTailEmission(Context);
+  testFormalStackAlignmentAndPreflight(Context);
+  testPlanningFailureDoesNotMutate(Context);
+  return Context.result();
+}