[GlobalISel] Split the generic pipeline components

7 files changed, 810 insertions, 703 deletions

diff --git a/backend/unittests/CodeGen/CMakeLists.txt b/backend/unittests/CodeGen/CMakeLists.txt
index 1b66194..5f73d3b 100644
--- a/backend/unittests/CodeGen/CMakeLists.txt
+++ b/backend/unittests/CodeGen/CMakeLists.txt
@@ -22,7 +22,6 @@ set(
   MachineOperandTest.cpp
   MachineOptimizationTest.cpp
   MachinePassTest.cpp
-  MachinePipelinePassesTest.cpp
   MachineSchedulingTest.cpp
   PBQPTest.cpp
   RegisterAllocationTest.cpp
@@ -337,16 +336,7 @@ target_link_libraries(
 
 add_test(NAME RCCBackend.CodeGen.MachinePass COMMAND RCCBackendCodeGenMachinePassTests)
 
-add_executable(RCCBackendCodeGenMachinePipelinePassesTests MachinePipelinePassesTest.cpp)
-rcc_backend_configure_target(RCCBackendCodeGenMachinePipelinePassesTests)
-target_link_libraries(
-  RCCBackendCodeGenMachinePipelinePassesTests
-  PRIVATE RCCBackend::CodeGen RCCBackend::RISCV RCCBackend::TestTarget
-)
-add_test(
-  NAME RCCBackend.CodeGen.MachinePipelinePasses
-  COMMAND RCCBackendCodeGenMachinePipelinePassesTests
-)
+add_subdirectory(GlobalISel)
 
 add_executable(RCCBackendCodeGenMachineAnalysesTests MachineAnalysesTest.cpp)
 rcc_backend_configure_target(RCCBackendCodeGenMachineAnalysesTests)
@@ -459,7 +449,6 @@ rcc_backend_register_format_files(
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineOperandTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineOptimizationTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachinePassTest.cpp"
-  "${CMAKE_CURRENT_SOURCE_DIR}/MachinePipelinePassesTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineSchedulingTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/PBQPTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/RegisterAllocationTest.cpp"
@@ -501,7 +490,6 @@ rcc_backend_register_tidy_files(
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineOperandTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineOptimizationTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachinePassTest.cpp"
-  "${CMAKE_CURRENT_SOURCE_DIR}/MachinePipelinePassesTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/MachineSchedulingTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/PBQPTest.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/RegisterAllocationTest.cpp"
diff --git a/backend/unittests/CodeGen/GlobalISel/CMakeLists.txt b/backend/unittests/CodeGen/GlobalISel/CMakeLists.txt
new file mode 100644
index 0000000..319e31f
--- /dev/null
+++ b/backend/unittests/CodeGen/GlobalISel/CMakeLists.txt
@@ -0,0 +1,44 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+add_executable(RCCBackendCodeGenLegalizerTests LegalizerTest.cpp)
+rcc_backend_configure_target(RCCBackendCodeGenLegalizerTests)
+target_link_libraries(
+  RCCBackendCodeGenLegalizerTests
+  PRIVATE RCCBackend::CodeGen RCCBackend::RISCV RCCBackend::TestTarget
+)
+add_test(NAME RCCBackend.CodeGen.GlobalISel.Legalizer COMMAND RCCBackendCodeGenLegalizerTests)
+
+add_executable(RCCBackendCodeGenRegBankSelectTests RegBankSelectTest.cpp)
+rcc_backend_configure_target(RCCBackendCodeGenRegBankSelectTests)
+target_link_libraries(
+  RCCBackendCodeGenRegBankSelectTests
+  PRIVATE RCCBackend::CodeGen RCCBackend::RISCV RCCBackend::TestTarget
+)
+add_test(
+  NAME RCCBackend.CodeGen.GlobalISel.RegBankSelect
+  COMMAND RCCBackendCodeGenRegBankSelectTests
+)
+
+add_executable(RCCBackendCodeGenInstructionSelectTests InstructionSelectTest.cpp)
+rcc_backend_configure_target(RCCBackendCodeGenInstructionSelectTests)
+target_link_libraries(
+  RCCBackendCodeGenInstructionSelectTests
+  PRIVATE RCCBackend::CodeGen RCCBackend::RISCV RCCBackend::TestTarget
+)
+add_test(
+  NAME RCCBackend.CodeGen.GlobalISel.InstructionSelect
+  COMMAND RCCBackendCodeGenInstructionSelectTests
+)
+
+rcc_backend_register_format_files(
+  "${CMAKE_CURRENT_SOURCE_DIR}/GISelMITest.h"
+  "${CMAKE_CURRENT_SOURCE_DIR}/InstructionSelectTest.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/LegalizerTest.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/RegBankSelectTest.cpp"
+)
+
+rcc_backend_register_tidy_files(
+  "${CMAKE_CURRENT_SOURCE_DIR}/InstructionSelectTest.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/LegalizerTest.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/RegBankSelectTest.cpp"
+)
diff --git a/backend/unittests/CodeGen/GlobalISel/GISelMITest.h b/backend/unittests/CodeGen/GlobalISel/GISelMITest.h
new file mode 100644
index 0000000..5b16535
--- /dev/null
+++ b/backend/unittests/CodeGen/GlobalISel/GISelMITest.h
@@ -0,0 +1,115 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef RCC_UNITTESTS_CODEGEN_GLOBALISEL_GISELMITEST_H
+#define RCC_UNITTESTS_CODEGEN_GLOBALISEL_GISELMITEST_H
+
+#include "rcc/CodeGen/GenericOpcodes.h"
+#include "rcc/CodeGen/MachineBasicBlock.h"
+#include "rcc/CodeGen/MachineFunction.h"
+#include "rcc/CodeGen/MachineIRBuilder.h"
+#include "rcc/CodeGen/MachineInstr.h"
+#include "rcc/CodeGen/MachineRegisterInfo.h"
+#include "rcc/Target/RISCV/RISCVTarget.h"
+
+#include <cstdint>
+#include <iostream>
+#include <memory>
+#include <string>
+#include <string_view>
+#include <utility>
+
+namespace rcc::test {
+
+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;
+};
+
+struct FunctionFixture final {
+  std::unique_ptr<rcc::MachineFunction> Function;
+  rcc::MachineBasicBlock *Entry = nullptr;
+};
+
+[[nodiscard]] inline FunctionFixture createFixture(TestContext &Context, std::string_view Name,
+                                                   std::uint64_t ID) {
+  auto Function =
+      rcc::MachineFunction::create(std::string(Name), rcc::MachineFunctionStableID::fromValue(ID));
+  Context.expect(Function.has_value(), "machine pipeline function creation must succeed");
+  if (!Function)
+    return {};
+  auto Entry = (*Function)->createBasicBlock();
+  Context.expect(Entry.has_value(), "machine pipeline block creation must succeed");
+  if (!Entry || !(*Function)->appendBlock(**Entry))
+    return {};
+  return {std::move(*Function), *Entry};
+}
+
+[[nodiscard]] inline rcc::Register
+createRegister(TestContext &Context, rcc::MachineFunction &Function, std::uint32_t Bits) {
+  auto Type = rcc::LLT::makeInteger(Bits);
+  Context.expect(Type.has_value(), "integer LLT construction must succeed");
+  if (!Type)
+    return {};
+  auto Reg = Function.registerInfo().createVirtualRegister(*Type);
+  Context.expect(Reg.has_value(), "virtual register construction must succeed");
+  return Reg ? *Reg : rcc::Register{};
+}
+
+[[nodiscard]] inline rcc::Register createFloatRegister(TestContext &Context,
+                                                       rcc::MachineFunction &Function) {
+  auto Type = rcc::LLT::makeFloat(rcc::FloatSemantics::IEEEDouble);
+  Context.expect(Type.has_value(), "floating LLT construction must succeed");
+  if (!Type)
+    return {};
+  auto Reg = Function.registerInfo().createVirtualRegister(*Type);
+  Context.expect(Reg.has_value(), "floating virtual register construction must succeed");
+  return Reg ? *Reg : rcc::Register{};
+}
+
+[[nodiscard]] inline bool assignGPR(rcc::MachineFunction &Function, rcc::Register Reg) {
+  const auto Bank =
+      rcc::RegisterBankID::fromValue(static_cast<std::uint32_t>(rcc::riscv::RegisterBank::GPR));
+  const auto RegClass =
+      rcc::RegisterClassID::fromValue(static_cast<std::uint32_t>(rcc::riscv::RegisterClass::GPR));
+  return Function.registerInfo().setRegisterBank(Reg, Bank).has_value() &&
+         Function.registerInfo().setRegisterClass(Reg, RegClass).has_value();
+}
+
+[[nodiscard]] inline bool buildConstant(TestContext &Context, rcc::MachineIRBuilder &Builder,
+                                        rcc::Register Destination, std::int64_t Value) {
+  auto Pending = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_CONSTANT));
+  if (!Pending || !Pending->addDef(Destination) || !Pending->addImmediate(Value) ||
+      !Pending->build()) {
+    Context.expect(false, "generic constant construction must succeed");
+    return false;
+  }
+  return true;
+}
+
+[[nodiscard]] inline bool buildAdd(TestContext &Context, rcc::MachineIRBuilder &Builder,
+                                   rcc::Register Destination, rcc::Register Left,
+                                   rcc::Register Right) {
+  auto Pending = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_ADD));
+  if (!Pending || !Pending->addDef(Destination) || !Pending->addUse(Left) ||
+      !Pending->addUse(Right) || !Pending->build()) {
+    Context.expect(false, "generic add construction must succeed");
+    return false;
+  }
+  return true;
+}
+
+} // namespace rcc::test
+
+#endif // RCC_UNITTESTS_CODEGEN_GLOBALISEL_GISELMITEST_H
diff --git a/backend/unittests/CodeGen/GlobalISel/InstructionSelectTest.cpp b/backend/unittests/CodeGen/GlobalISel/InstructionSelectTest.cpp
new file mode 100644
index 0000000..9e09934
--- /dev/null
+++ b/backend/unittests/CodeGen/GlobalISel/InstructionSelectTest.cpp
@@ -0,0 +1,357 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "rcc/CodeGen/GlobalISel/InstructionSelect.h"
+
+#include "GISelMITest.h"
+#include "rcc/CodeGen/GlobalISel/Legalizer.h"
+#include "rcc/CodeGen/GlobalISel/RegBankSelect.h"
+#include "rcc/CodeGen/MachineMemOperand.h"
+#include "rcc/Target/RISCV/RISCVCodeGen.h"
+
+#include <algorithm>
+#include <array>
+#include <cstdint>
+#include <memory>
+#include <ranges>
+#include <vector>
+
+namespace {
+
+using rcc::test::assignGPR;
+using rcc::test::buildAdd;
+using rcc::test::buildConstant;
+using rcc::test::createFixture;
+using rcc::test::createRegister;
+using rcc::test::TestContext;
+
+class MutatingFailingSelector final : public rcc::InstructionSelector {
+public:
+  [[nodiscard]] rcc::Expected<void> canSelect(const rcc::MachineInstr &,
+                                              const rcc::MachineFunction &,
+                                              const rcc::TargetDescription &) const override {
+    return {};
+  }
+
+  [[nodiscard]] rcc::Expected<void> select(rcc::MachineInstr &Instruction, rcc::MachineFunction &,
+                                           const rcc::TargetDescription &) const override {
+    auto Mutation = Instruction.setOpcode(rcc::opcode(rcc::GenericOpcode::G_SUB));
+    if (!Mutation)
+      return std::unexpected(Mutation.error());
+    return rcc::makeUnexpected(rcc::ErrorCode::Unsupported, "test selector rejected its renderer");
+  }
+};
+
+class RecordingSelector final : public rcc::InstructionSelector {
+public:
+  explicit RecordingSelector(const rcc::InstructionSelector &Delegate) : Delegate(&Delegate) {}
+
+  [[nodiscard]] rcc::Expected<void> canSelect(const rcc::MachineInstr &Instruction,
+                                              const rcc::MachineFunction &Function,
+                                              const rcc::TargetDescription &Target) const override {
+    return Delegate->canSelect(Instruction, Function, Target);
+  }
+
+  [[nodiscard]] rcc::Expected<void> select(rcc::MachineInstr &Instruction,
+                                           rcc::MachineFunction &Function,
+                                           const rcc::TargetDescription &Target) const override {
+    SelectedIDs.push_back(Instruction.stableID().value());
+    return Delegate->select(Instruction, Function, Target);
+  }
+
+  [[nodiscard]] const std::vector<std::uint64_t> &selectedIDs() const noexcept {
+    return SelectedIDs;
+  }
+
+private:
+  const rcc::InstructionSelector *Delegate;
+  mutable std::vector<std::uint64_t> SelectedIDs;
+};
+
+class TwoStepSelector final : public rcc::InstructionSelector {
+public:
+  [[nodiscard]] rcc::Expected<void> canSelect(const rcc::MachineInstr &,
+                                              const rcc::MachineFunction &,
+                                              const rcc::TargetDescription &) const override {
+    return {};
+  }
+
+  [[nodiscard]] rcc::Expected<void> select(rcc::MachineInstr &Instruction, rcc::MachineFunction &,
+                                           const rcc::TargetDescription &) const override {
+    ++Selections;
+    if (Instruction.opcode() == rcc::opcode(rcc::GenericOpcode::G_ADD))
+      return Instruction.setOpcode(rcc::opcode(rcc::GenericOpcode::G_SUB));
+    if (Instruction.opcode() == rcc::opcode(rcc::GenericOpcode::G_SUB)) {
+      return Instruction.setOpcode(
+          rcc::Opcode::fromValue(static_cast<std::uint32_t>(rcc::riscv::InstructionOpcode::ADD)));
+    }
+    return rcc::makeUnexpected(rcc::ErrorCode::Unsupported,
+                               "two-step selector received an unexpected opcode");
+  }
+
+  [[nodiscard]] std::size_t selections() const noexcept {
+    return Selections;
+  }
+
+private:
+  mutable std::size_t Selections = 0;
+};
+
+void testPipeline(TestContext &Context) {
+  auto Target = rcc::riscv::createTargetDescription();
+  auto Fixture = createFixture(Context, "pipeline_success", 2);
+  Context.expect(Target.has_value() && Fixture.Function != nullptr && Fixture.Entry != nullptr,
+                 "pipeline success fixture must be complete");
+  if (!Target || !Fixture.Function || Fixture.Entry == nullptr)
+    return;
+
+  const rcc::Register Left = createRegister(Context, *Fixture.Function, 64);
+  const rcc::Register Right = createRegister(Context, *Fixture.Function, 64);
+  const rcc::Register Result = createRegister(Context, *Fixture.Function, 64);
+  rcc::MachineIRBuilder Builder(*Fixture.Function, *Target);
+  Context.expect(Builder.setInsertPoint(*Fixture.Entry).has_value(),
+                 "pipeline insertion point must be valid");
+  if (Left.isNoRegister() || Right.isNoRegister() || Result.isNoRegister() ||
+      !buildConstant(Context, Builder, Left, 42) || !buildConstant(Context, Builder, Right, 1) ||
+      !buildAdd(Context, Builder, Result, Left, Right))
+    return;
+
+  Fixture.Function->properties() = {rcc::MachineFunctionProperty::IsSSA,
+                                    rcc::MachineFunctionProperty::TracksLiveness};
+  rcc::MachinePassManager Pipeline;
+  Context.expect(
+      Pipeline.addPass(std::make_unique<rcc::Legalizer>(rcc::riscv::legalizerInfo())).has_value(),
+      "legalizer must be accepted by the pass manager");
+  Context.expect(
+      Pipeline.addPass(std::make_unique<rcc::RegBankSelect>(rcc::riscv::registerBankInfo()))
+          .has_value(),
+      "register-bank selector must be accepted by the pass manager");
+  Context.expect(
+      Pipeline.addPass(std::make_unique<rcc::InstructionSelect>(rcc::riscv::instructionSelector()))
+          .has_value(),
+      "instruction selector must be accepted by the pass manager");
+  rcc::MachineAnalysisManager Analyses;
+  auto Run = Pipeline.run(*Fixture.Function, *Target, Analyses);
+  Context.expect(Run.has_value(), "RV64GC generic pipeline must complete");
+  Context.expect(Fixture.Function->properties().has(rcc::MachineFunctionProperty::Selected),
+                 "successful instruction selection must publish Selected");
+  Context.expect(Fixture.Function->firstBlock()->firstInstruction() != nullptr,
+                 "selected instructions must remain attached to their block");
+  for (const rcc::MachineInstr *Instruction : Fixture.Function->allInstructions())
+    Context.expect(!rcc::isGenericOpcode(Instruction->opcode()),
+                   "successful instruction selection must remove generic opcodes");
+}
+
+void testInstructionSelectionTransaction(TestContext &Context) {
+  auto Target = rcc::riscv::createTargetDescription();
+  auto Fixture = createFixture(Context, "pipeline_selection_transaction", 8);
+  if (!Target || !Fixture.Function || Fixture.Entry == nullptr)
+    return;
+  const rcc::Register Left = createRegister(Context, *Fixture.Function, 64);
+  const rcc::Register Right = createRegister(Context, *Fixture.Function, 64);
+  const rcc::Register Result = createRegister(Context, *Fixture.Function, 64);
+  rcc::MachineIRBuilder Builder(*Fixture.Function, *Target);
+  if (Left.isNoRegister() || Right.isNoRegister() || Result.isNoRegister() ||
+      !Builder.setInsertPoint(*Fixture.Entry) || !buildAdd(Context, Builder, Result, Left, Right) ||
+      !assignGPR(*Fixture.Function, Left) || !assignGPR(*Fixture.Function, Right) ||
+      !assignGPR(*Fixture.Function, Result)) {
+    return;
+  }
+  rcc::MachineInstr *Original = Fixture.Entry->firstInstruction();
+  if (Original == nullptr)
+    return;
+  const rcc::Opcode OriginalOpcode = Original->opcode();
+  const std::size_t OriginalOperandCount = Original->operandCount();
+  Fixture.Function->properties() = {rcc::MachineFunctionProperty::Legalized,
+                                    rcc::MachineFunctionProperty::RegBankSelected};
+  MutatingFailingSelector Selector;
+  rcc::InstructionSelect Pass(Selector);
+  rcc::MachineAnalysisManager Analyses;
+  auto Run = Pass.run(*Fixture.Function, *Target, Analyses);
+  Context.expect(!Run && Run.error().code() == rcc::ErrorCode::Unsupported,
+                 "a renderer failure must be reported before publication");
+  Context.expect(Original->opcode() == OriginalOpcode &&
+                     Original->operandCount() == OriginalOperandCount &&
+                     Fixture.Entry->instructionCount() == 1,
+                 "a renderer failure must leave the original MachineIR unchanged");
+}
+
+void testInstructionSelectionOrder(TestContext &Context) {
+  auto Target = rcc::riscv::createTargetDescription();
+  auto Fixture = createFixture(Context, "pipeline_selection_order", 9);
+  if (!Target || !Fixture.Function || Fixture.Entry == nullptr)
+    return;
+  const rcc::Register Left = createRegister(Context, *Fixture.Function, 64);
+  const rcc::Register Right = createRegister(Context, *Fixture.Function, 64);
+  const rcc::Register Result = createRegister(Context, *Fixture.Function, 64);
+  rcc::MachineIRBuilder Builder(*Fixture.Function, *Target);
+  if (Left.isNoRegister() || Right.isNoRegister() || Result.isNoRegister() ||
+      !Builder.setInsertPoint(*Fixture.Entry) || !buildConstant(Context, Builder, Left, 6) ||
+      !buildConstant(Context, Builder, Right, 7) ||
+      !buildAdd(Context, Builder, Result, Left, Right) || !assignGPR(*Fixture.Function, Left) ||
+      !assignGPR(*Fixture.Function, Right) || !assignGPR(*Fixture.Function, Result)) {
+    return;
+  }
+  std::vector<std::uint64_t> LayoutIDs;
+  for (const rcc::MachineInstr *Instruction = Fixture.Entry->firstInstruction();
+       Instruction != nullptr; Instruction = Instruction->next()) {
+    LayoutIDs.push_back(Instruction->stableID().value());
+  }
+  Fixture.Function->properties() = {rcc::MachineFunctionProperty::Legalized,
+                                    rcc::MachineFunctionProperty::RegBankSelected};
+  RecordingSelector Selector(rcc::riscv::instructionSelector());
+  rcc::InstructionSelect Pass(Selector);
+  rcc::MachineAnalysisManager Analyses;
+  auto Run = Pass.run(*Fixture.Function, *Target, Analyses);
+  Context.expect(Run.has_value(), "recorded instruction selection must complete");
+  std::ranges::reverse(LayoutIDs);
+  std::vector<std::uint64_t> Expected = LayoutIDs;
+  Expected.insert(Expected.end(), LayoutIDs.begin(), LayoutIDs.end());
+  Context.expect(
+      Selector.selectedIDs() == Expected,
+      "instruction selection must use stable block-postorder and reverse instruction order");
+}
+
+void testInstructionSelectionWorklist(TestContext &Context) {
+  auto Target = rcc::riscv::createTargetDescription();
+  auto Fixture = createFixture(Context, "pipeline_selection_worklist", 10);
+  if (!Target || !Fixture.Function || Fixture.Entry == nullptr)
+    return;
+  const rcc::Register Left = createRegister(Context, *Fixture.Function, 64);
+  const rcc::Register Right = createRegister(Context, *Fixture.Function, 64);
+  const rcc::Register Result = createRegister(Context, *Fixture.Function, 64);
+  rcc::MachineIRBuilder Builder(*Fixture.Function, *Target);
+  if (Left.isNoRegister() || Right.isNoRegister() || Result.isNoRegister() ||
+      !Builder.setInsertPoint(*Fixture.Entry) || !buildAdd(Context, Builder, Result, Left, Right) ||
+      !assignGPR(*Fixture.Function, Left) || !assignGPR(*Fixture.Function, Right) ||
+      !assignGPR(*Fixture.Function, Result)) {
+    return;
+  }
+  Fixture.Function->properties() = {rcc::MachineFunctionProperty::Legalized,
+                                    rcc::MachineFunctionProperty::RegBankSelected};
+  TwoStepSelector Selector;
+  rcc::InstructionSelect Pass(Selector);
+  rcc::MachineAnalysisManager Analyses;
+  auto Run = Pass.run(*Fixture.Function, *Target, Analyses);
+  Context.expect(Run.has_value(), "a progressing multi-step selection must complete");
+  Context.expect(Selector.selections() == 4,
+                 "transaction preflight and publication must each select both generic states");
+  Context.expect(Fixture.Entry->firstInstruction() != nullptr &&
+                     Fixture.Entry->firstInstruction()->opcode() ==
+                         rcc::Opcode::fromValue(
+                             static_cast<std::uint32_t>(rcc::riscv::InstructionOpcode::ADD)),
+                 "the selection worklist must revisit a progressing generic root");
+}
+
+void testExtendedRV64GCPipeline(TestContext &Context) {
+  auto Target = rcc::riscv::createTargetDescription();
+  auto Fixture = createFixture(Context, "pipeline_extended_rv64gc", 7);
+  Context.expect(Target.has_value() && Fixture.Function != nullptr && Fixture.Entry != nullptr,
+                 "extended pipeline fixture must be complete");
+  if (!Target || !Fixture.Function || Fixture.Entry == nullptr)
+    return;
+  auto I1 = rcc::LLT::makeInteger(1);
+  auto I64 = rcc::LLT::makeInteger(64);
+  auto Pointer = rcc::LLT::makePointer(0, 64);
+  if (!I1 || !I64 || !Pointer)
+    return;
+  const rcc::Register Left = createRegister(Context, *Fixture.Function, 64);
+  const rcc::Register Right = createRegister(Context, *Fixture.Function, 64);
+  const rcc::Register Condition =
+      Fixture.Function->registerInfo().createVirtualRegister(*I1).value_or(rcc::Register{});
+  const rcc::Register Selected = createRegister(Context, *Fixture.Function, 64);
+  const rcc::Register Sum = createRegister(Context, *Fixture.Function, 64);
+  const rcc::Register Overflow =
+      Fixture.Function->registerInfo().createVirtualRegister(*I1).value_or(rcc::Register{});
+  const rcc::Register Quotient = createRegister(Context, *Fixture.Function, 64);
+  const rcc::Register Remainder = createRegister(Context, *Fixture.Function, 64);
+  const rcc::Register Address =
+      Fixture.Function->registerInfo().createVirtualRegister(*Pointer).value_or(rcc::Register{});
+  const rcc::Register AtomicResult = createRegister(Context, *Fixture.Function, 64);
+  const std::array Registers{Left,     Right,    Condition, Selected, Sum,
+                             Overflow, Quotient, Remainder, Address,  AtomicResult};
+  if (std::ranges::any_of(Registers, [](rcc::Register Reg) { return Reg.isNoRegister(); }))
+    return;
+  rcc::MachineIRBuilder Builder(*Fixture.Function, *Target);
+  if (!Builder.setInsertPoint(*Fixture.Entry) || !buildConstant(Context, Builder, Left, 41) ||
+      !buildConstant(Context, Builder, Right, 7)) {
+    return;
+  }
+  auto Compare = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_ICMP));
+  if (!Compare || !Compare->addDef(Condition) ||
+      !Compare->addIntegerPredicate(rcc::IntegerPredicate::UnsignedGreaterThan) ||
+      !Compare->addUse(Left) || !Compare->addUse(Right) || !Compare->build()) {
+    return;
+  }
+  auto Select = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_SELECT));
+  if (!Select || !Select->addDef(Selected) || !Select->addUse(Condition) || !Select->addUse(Left) ||
+      !Select->addUse(Right) || !Select->build()) {
+    return;
+  }
+  auto AddOverflow = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_UADDO));
+  if (!AddOverflow || !AddOverflow->addDef(Sum) || !AddOverflow->addDef(Overflow) ||
+      !AddOverflow->addUse(Left) || !AddOverflow->addUse(Right) || !AddOverflow->build()) {
+    return;
+  }
+  auto DivRem = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_SDIVREM));
+  if (!DivRem || !DivRem->addDef(Quotient) || !DivRem->addDef(Remainder) || !DivRem->addUse(Left) ||
+      !DivRem->addUse(Right) || !DivRem->build()) {
+    return;
+  }
+  auto AddressDefinition = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_IMPLICIT_DEF));
+  if (!AddressDefinition || !AddressDefinition->addDef(Address) || !AddressDefinition->build())
+    return;
+  auto Size = rcc::MemorySize::fixed(8);
+  auto Align = rcc::Alignment::create(8);
+  if (!Size || !Align)
+    return;
+  rcc::MachineMemOperandDesc Description;
+  Description.Accesses = {rcc::MemoryAccessFlag::Load, rcc::MemoryAccessFlag::Store};
+  Description.AtomicKind = rcc::AtomicOperation::ReadModifyWrite;
+  Description.SuccessOrdering = rcc::AtomicOrdering::SequentiallyConsistent;
+  Description.Size = *Size;
+  Description.Align = *Align;
+  Description.Base = rcc::MemoryBase::stack();
+  auto Memory = Fixture.Function->createMemOperand(std::move(Description));
+  if (!Memory)
+    return;
+  auto Atomic = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_ATOMICRMW_ADD));
+  if (!Atomic || !Atomic->addDef(AtomicResult) || !Atomic->addUse(Address) ||
+      !Atomic->addUse(Selected) || !Atomic->addMemOperand(**Memory) || !Atomic->build()) {
+    return;
+  }
+
+  Fixture.Function->properties() = {rcc::MachineFunctionProperty::IsSSA,
+                                    rcc::MachineFunctionProperty::TracksLiveness};
+  rcc::MachinePassManager Pipeline;
+  if (!Pipeline.addPass(std::make_unique<rcc::Legalizer>(rcc::riscv::legalizerInfo())) ||
+      !Pipeline.addPass(std::make_unique<rcc::RegBankSelect>(rcc::riscv::registerBankInfo())) ||
+      !Pipeline.addPass(
+          std::make_unique<rcc::InstructionSelect>(rcc::riscv::instructionSelector()))) {
+    Context.expect(false, "extended RV64GC pipeline construction must succeed");
+    return;
+  }
+  rcc::MachineAnalysisManager Analyses;
+  auto Run = Pipeline.run(*Fixture.Function, *Target, Analyses);
+  Context.expect(Run.has_value(), "extended RV64GC pipeline must complete");
+  Context.expect(Run && Fixture.Function->properties().has(rcc::MachineFunctionProperty::Selected),
+                 "extended pipeline must publish Selected");
+  for (const rcc::MachineInstr *Instruction : Fixture.Function->allInstructions()) {
+    Context.expect(!rcc::isGenericOpcode(Instruction->opcode()),
+                   "extended pipeline must eliminate every generic opcode");
+    Context.expect(
+        Target->validateInstruction(*Instruction, Fixture.Function->registerInfo()).has_value(),
+        "extended pipeline output must satisfy target descriptors");
+  }
+}
+
+} // namespace
+
+int main() {
+  TestContext Context;
+  testPipeline(Context);
+  testInstructionSelectionTransaction(Context);
+  testInstructionSelectionOrder(Context);
+  testInstructionSelectionWorklist(Context);
+  testExtendedRV64GCPipeline(Context);
+  return Context.result();
+}
diff --git a/backend/unittests/CodeGen/GlobalISel/LegalizerTest.cpp b/backend/unittests/CodeGen/GlobalISel/LegalizerTest.cpp
new file mode 100644
index 0000000..6280182
--- /dev/null
+++ b/backend/unittests/CodeGen/GlobalISel/LegalizerTest.cpp
@@ -0,0 +1,205 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "rcc/CodeGen/GlobalISel/Legalizer.h"
+
+#include "GISelMITest.h"
+#include "rcc/Target/RISCV/RISCVCodeGen.h"
+
+#include <cstdint>
+#include <memory>
+#include <string>
+
+namespace {
+
+using rcc::test::buildAdd;
+using rcc::test::createFixture;
+using rcc::test::createFloatRegister;
+using rcc::test::createRegister;
+using rcc::test::TestContext;
+
+class TogglingLegalizer final : public rcc::LegalizerInfo {
+public:
+  [[nodiscard]] rcc::Expected<rcc::LegalizationAction>
+  classify(const rcc::MachineInstr &, const rcc::MachineFunction &,
+           const rcc::TargetDescription &) const override {
+    return rcc::LegalizationAction::Lower;
+  }
+
+  [[nodiscard]] rcc::Expected<void> lower(rcc::MachineInstr &Instruction, rcc::MachineFunction &,
+                                          const rcc::TargetDescription &,
+                                          rcc::LegalizationAction) const override {
+    const auto Generic = static_cast<rcc::GenericOpcode>(Instruction.opcode().value());
+    return Instruction.setOpcode(rcc::opcode(Generic == rcc::GenericOpcode::G_ADD
+                                                 ? rcc::GenericOpcode::G_SUB
+                                                 : rcc::GenericOpcode::G_ADD));
+  }
+};
+
+class BackwardInvalidatingLegalizer final : public rcc::LegalizerInfo {
+public:
+  [[nodiscard]] rcc::Expected<rcc::LegalizationAction>
+  classify(const rcc::MachineInstr &Instruction, const rcc::MachineFunction &,
+           const rcc::TargetDescription &) const override {
+    return Instruction.opcode() == rcc::opcode(rcc::GenericOpcode::G_SUB)
+               ? rcc::LegalizationAction::Custom
+               : rcc::LegalizationAction::Legal;
+  }
+
+  [[nodiscard]] rcc::Expected<void> lower(rcc::MachineInstr &Instruction,
+                                          rcc::MachineFunction &Function,
+                                          const rcc::TargetDescription &,
+                                          rcc::LegalizationAction) const override {
+    for (rcc::MachineInstr *Candidate : Function.allInstructions()) {
+      if (Candidate != &Instruction &&
+          Candidate->opcode() == rcc::opcode(rcc::GenericOpcode::G_ADD)) {
+        auto Invalidated = Candidate->setOpcode(rcc::opcode(rcc::GenericOpcode::G_SUB));
+        if (!Invalidated)
+          return std::unexpected(Invalidated.error());
+        break;
+      }
+    }
+    return Instruction.setOpcode(
+        rcc::Opcode::fromValue(static_cast<std::uint32_t>(rcc::riscv::InstructionOpcode::ADD)));
+  }
+};
+
+void testNullAndMissingContracts(TestContext &Context) {
+  auto Target = rcc::riscv::createTargetDescription();
+  auto Fixture = createFixture(Context, "pipeline_contracts", 1);
+  Context.expect(Target.has_value() && Fixture.Function != nullptr && Fixture.Entry != nullptr,
+                 "pipeline contract fixture must be complete");
+  if (!Target || !Fixture.Function)
+    return;
+
+  rcc::Legalizer NullPass(nullptr);
+  rcc::MachineAnalysisManager Analyses;
+  auto NullResult = NullPass.run(*Fixture.Function, *Target, Analyses);
+  Context.expect(!NullResult && NullResult.error().code() == rcc::ErrorCode::InvalidArgument,
+                 "a null legalizer interface must be rejected");
+  Context.expect(Fixture.Function->properties().empty(),
+                 "a rejected pass must not publish function properties");
+
+  rcc::Legalizer ValidPass(rcc::riscv::legalizerInfo());
+  auto MissingResult = ValidPass.run(*Fixture.Function, *Target, Analyses);
+  Context.expect(!MissingResult &&
+                     MissingResult.error().code() == rcc::ErrorCode::VerificationError,
+                 "a pass with missing prerequisites must be rejected");
+}
+
+void testUnsupportedRollback(TestContext &Context) {
+  auto Target = rcc::riscv::createTargetDescription();
+  if (!Target)
+    return;
+  auto Unsupported = createFixture(Context, "pipeline_unsupported", 3);
+  Context.expect(Unsupported.Function != nullptr && Unsupported.Entry != nullptr,
+                 "unsupported pipeline fixture must be complete");
+  if (!Unsupported.Function || Unsupported.Entry == nullptr)
+    return;
+  const rcc::Register UnsupportedReg = createFloatRegister(Context, *Unsupported.Function);
+  const rcc::Register UnsupportedSource = createFloatRegister(Context, *Unsupported.Function);
+  rcc::MachineIRBuilder UnsupportedBuilder(*Unsupported.Function, *Target);
+  Context.expect(UnsupportedBuilder.setInsertPoint(*Unsupported.Entry).has_value(),
+                 "unsupported pipeline insertion point must be valid");
+  if (UnsupportedReg.isNoRegister() || UnsupportedSource.isNoRegister())
+    return;
+  auto Pending = UnsupportedBuilder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_FEXP));
+  Context.expect(Pending.has_value(), "unsupported generic instruction must be constructible");
+  if (!Pending)
+    return;
+  auto Built = Pending->addDef(UnsupportedReg);
+  Context.expect(Built.has_value(), "unsupported generic definition must be accepted");
+  if (!Built)
+    return;
+  Context.expect(Pending->addUse(UnsupportedSource).has_value() && Pending->build().has_value(),
+                 "unsupported floating operation must be constructible");
+  Unsupported.Function->properties() = {rcc::MachineFunctionProperty::IsSSA,
+                                        rcc::MachineFunctionProperty::TracksLiveness};
+  rcc::MachinePassManager OnlyLegalizer;
+  Context.expect(
+      OnlyLegalizer.addPass(std::make_unique<rcc::Legalizer>(rcc::riscv::legalizerInfo()))
+          .has_value(),
+      "standalone legalizer must be accepted");
+  rcc::MachineAnalysisManager UnsupportedAnalyses;
+  auto Failure = OnlyLegalizer.run(*Unsupported.Function, *Target, UnsupportedAnalyses);
+  Context.expect(!Failure && Failure.error().code() == rcc::ErrorCode::Unsupported,
+                 "unsupported generic instructions must produce a target diagnostic");
+  Context.expect(!Failure && Failure.error().message().find("G_FEXP") != std::string::npos,
+                 "unsupported legalization diagnostics must name the rejected opcode");
+  Context.expect(
+      Unsupported.Function->properties().has(rcc::MachineFunctionProperty::IsSSA) &&
+          !Unsupported.Function->properties().has(rcc::MachineFunctionProperty::Legalized),
+      "failed legalizer execution must not publish Legalized");
+}
+
+void testLegalizerCycleDiagnostic(TestContext &Context) {
+  auto Target = rcc::riscv::createTargetDescription();
+  auto Fixture = createFixture(Context, "pipeline_legalizer_cycle", 6);
+  Context.expect(Target.has_value() && Fixture.Function != nullptr && Fixture.Entry != nullptr,
+                 "legalizer cycle fixture must be complete");
+  if (!Target || !Fixture.Function || Fixture.Entry == nullptr)
+    return;
+  const rcc::Register Left = createRegister(Context, *Fixture.Function, 64);
+  const rcc::Register Right = createRegister(Context, *Fixture.Function, 64);
+  const rcc::Register Result = createRegister(Context, *Fixture.Function, 64);
+  rcc::MachineIRBuilder Builder(*Fixture.Function, *Target);
+  if (Left.isNoRegister() || Right.isNoRegister() || Result.isNoRegister() ||
+      !Builder.setInsertPoint(*Fixture.Entry) || !buildAdd(Context, Builder, Result, Left, Right))
+    return;
+  Fixture.Function->properties() = {rcc::MachineFunctionProperty::IsSSA,
+                                    rcc::MachineFunctionProperty::TracksLiveness};
+  TogglingLegalizer Legalizer;
+  rcc::Legalizer StablePass(Legalizer);
+  rcc::MachineAnalysisManager Analyses;
+  auto ResultRun = StablePass.run(*Fixture.Function, *Target, Analyses);
+  Context.expect(!ResultRun && ResultRun.error().code() == rcc::ErrorCode::InternalError,
+                 "repeated legalization states must report InternalError");
+  Context.expect(Fixture.Entry->firstInstruction() != nullptr &&
+                     Fixture.Entry->firstInstruction()->opcode() ==
+                         rcc::opcode(rcc::GenericOpcode::G_ADD),
+                 "failed legalization preflight must preserve the original instruction");
+  Context.expect(!Fixture.Function->properties().has(rcc::MachineFunctionProperty::Legalized),
+                 "a failed legalization cycle must not publish Legalized");
+}
+
+void testLegalizerRevisitsInvalidatedInstructions(TestContext &Context) {
+  auto Target = rcc::riscv::createTargetDescription();
+  auto Fixture = createFixture(Context, "pipeline_legalizer_revisit", 7);
+  if (!Target || !Fixture.Function || Fixture.Entry == nullptr)
+    return;
+  const rcc::Register Left = createRegister(Context, *Fixture.Function, 64);
+  const rcc::Register Right = createRegister(Context, *Fixture.Function, 64);
+  const rcc::Register FirstResult = createRegister(Context, *Fixture.Function, 64);
+  const rcc::Register SecondResult = createRegister(Context, *Fixture.Function, 64);
+  rcc::MachineIRBuilder Builder(*Fixture.Function, *Target);
+  if (Left.isNoRegister() || Right.isNoRegister() || FirstResult.isNoRegister() ||
+      SecondResult.isNoRegister() || !Builder.setInsertPoint(*Fixture.Entry) ||
+      !buildAdd(Context, Builder, FirstResult, Left, Right) ||
+      !buildAdd(Context, Builder, SecondResult, Left, Right))
+    return;
+  rcc::MachineInstr *First = Fixture.Entry->firstInstruction();
+  rcc::MachineInstr *Second = First == nullptr ? nullptr : First->next();
+  if (Second == nullptr || !Second->setOpcode(rcc::opcode(rcc::GenericOpcode::G_SUB)))
+    return;
+
+  Fixture.Function->properties() = {rcc::MachineFunctionProperty::IsSSA,
+                                    rcc::MachineFunctionProperty::TracksLiveness};
+  BackwardInvalidatingLegalizer Legalizer;
+  rcc::Legalizer Pass(Legalizer);
+  rcc::MachineAnalysisManager Analyses;
+  auto Run = Pass.run(*Fixture.Function, *Target, Analyses);
+  const rcc::Opcode LegalOpcode =
+      rcc::Opcode::fromValue(static_cast<std::uint32_t>(rcc::riscv::InstructionOpcode::ADD));
+  Context.expect(Run && First->opcode() == LegalOpcode && Second->opcode() == LegalOpcode,
+                 "legalizer must revisit an earlier instruction invalidated by a later lowering");
+}
+
+} // namespace
+
+int main() {
+  TestContext Context;
+  testNullAndMissingContracts(Context);
+  testUnsupportedRollback(Context);
+  testLegalizerCycleDiagnostic(Context);
+  testLegalizerRevisitsInvalidatedInstructions(Context);
+  return Context.result();
+}
diff --git a/backend/unittests/CodeGen/GlobalISel/RegBankSelectTest.cpp b/backend/unittests/CodeGen/GlobalISel/RegBankSelectTest.cpp
new file mode 100644
index 0000000..3cfa888
--- /dev/null
+++ b/backend/unittests/CodeGen/GlobalISel/RegBankSelectTest.cpp
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "rcc/CodeGen/GlobalISel/RegBankSelect.h"
+
+#include "GISelMITest.h"
+#include "rcc/Target/RISCV/RISCVCodeGen.h"
+
+#include <cstdint>
+
+namespace {
+
+using rcc::test::buildConstant;
+using rcc::test::createFixture;
+using rcc::test::createRegister;
+using rcc::test::TestContext;
+
+void testBankConflict(TestContext &Context) {
+  auto Target = rcc::riscv::createTargetDescription();
+  auto Fixture = createFixture(Context, "pipeline_bank_conflict", 4);
+  Context.expect(Target.has_value() && Fixture.Function != nullptr && Fixture.Entry != nullptr,
+                 "bank conflict fixture must be complete");
+  if (!Target || !Fixture.Function || Fixture.Entry == nullptr)
+    return;
+  const rcc::Register Value = createRegister(Context, *Fixture.Function, 64);
+  Context.expect(
+      Fixture.Function->registerInfo()
+          .setRegisterBank(Value, rcc::RegisterBankID::fromValue(
+                                      static_cast<std::uint32_t>(rcc::riscv::RegisterBank::FPR)))
+          .has_value(),
+      "conflicting bank assignment must be constructible");
+  Fixture.Function->properties() = {rcc::MachineFunctionProperty::Legalized};
+  rcc::RegBankSelect Pass(rcc::riscv::registerBankInfo());
+  rcc::MachineAnalysisManager Analyses;
+  auto Result = Pass.run(*Fixture.Function, *Target, Analyses);
+  Context.expect(!Result && Result.error().code() == rcc::ErrorCode::VerificationError,
+                 "bank selection must reject a conflicting pre-existing bank");
+  auto Info = Fixture.Function->registerInfo().virtualRegisterInfo(Value);
+  Context.expect(Info && Info->get().Bank, "failed bank selection must preserve a bank assignment");
+  if (!Info || !Info->get().Bank)
+    return;
+  const rcc::RegisterBankID Bank = Info->get().Bank.value_or(rcc::RegisterBankID{});
+  Context.expect(Bank == rcc::RegisterBankID::fromValue(
+                             static_cast<std::uint32_t>(rcc::riscv::RegisterBank::FPR)),
+                 "failed bank selection must preserve the original bank assignment");
+}
+
+void testBankClassOnlyChange(TestContext &Context) {
+  auto Target = rcc::riscv::createTargetDescription();
+  auto Fixture = createFixture(Context, "pipeline_bank_class", 5);
+  Context.expect(Target.has_value() && Fixture.Function != nullptr && Fixture.Entry != nullptr,
+                 "bank class fixture must be complete");
+  if (!Target || !Fixture.Function || Fixture.Entry == nullptr)
+    return;
+  const rcc::Register Value = createRegister(Context, *Fixture.Function, 64);
+  rcc::MachineIRBuilder Builder(*Fixture.Function, *Target);
+  if (Value.isNoRegister() || !Builder.setInsertPoint(*Fixture.Entry) ||
+      !buildConstant(Context, Builder, Value, 7))
+    return;
+  const auto GPR =
+      rcc::RegisterBankID::fromValue(static_cast<std::uint32_t>(rcc::riscv::RegisterBank::GPR));
+  Context.expect(Fixture.Function->registerInfo().setRegisterBank(Value, GPR).has_value(),
+                 "pre-existing GPR bank must be assignable");
+  Fixture.Function->properties() = {rcc::MachineFunctionProperty::Legalized};
+  rcc::RegBankSelect Pass(rcc::riscv::registerBankInfo());
+  rcc::MachineAnalysisManager Analyses;
+  auto Result = Pass.run(*Fixture.Function, *Target, Analyses);
+  Context.expect(Result.has_value() && Result->Changed &&
+                     Result->Changes.has(rcc::MachinePassChange::Registers),
+                 "bank selection must report a class-only register change");
+  auto Info = Fixture.Function->registerInfo().virtualRegisterInfo(Value);
+  Context.expect(Info && Info->get().Bank && Info->get().RegClass,
+                 "bank selection must publish both bank and class");
+  if (!Info || !Info->get().RegClass)
+    return;
+  Context.expect(Info->get().RegClass.value_or(rcc::RegisterClassID{}) ==
+                     rcc::RegisterClassID::fromValue(
+                         static_cast<std::uint32_t>(rcc::riscv::RegisterClass::GPR)),
+                 "i64 GPR bank must select the GPR class");
+}
+
+} // namespace
+
+int main() {
+  TestContext Context;
+  testBankConflict(Context);
+  testBankClassOnlyChange(Context);
+  return Context.result();
+}
diff --git a/backend/unittests/CodeGen/MachinePipelinePassesTest.cpp b/backend/unittests/CodeGen/MachinePipelinePassesTest.cpp
deleted file mode 100644
index 78c4cc7..0000000
--- a/backend/unittests/CodeGen/MachinePipelinePassesTest.cpp
+++ /dev/null
@@ -1,690 +0,0 @@
-// SPDX-License-Identifier: GPL-3.0-or-later
-
-#include "rcc/CodeGen/MachinePipelinePasses.h"
-
-#include "rcc/CodeGen/GenericOpcodes.h"
-#include "rcc/CodeGen/MachineBasicBlock.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/Target/RISCV/RISCVCodeGen.h"
-#include "rcc/Target/RISCV/RISCVTarget.h"
-
-#include <algorithm>
-#include <array>
-#include <cstdint>
-#include <iostream>
-#include <memory>
-#include <ranges>
-#include <string>
-#include <string_view>
-#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;
-};
-
-struct FunctionFixture final {
-  std::unique_ptr<rcc::MachineFunction> Function;
-  rcc::MachineBasicBlock *Entry = nullptr;
-};
-
-class TogglingLegalizer final : public rcc::TargetLegalizerInfo {
-public:
-  [[nodiscard]] rcc::Expected<rcc::LegalizationAction>
-  classify(const rcc::MachineInstr &, const rcc::MachineFunction &,
-           const rcc::TargetDescription &) const override {
-    return rcc::LegalizationAction::Lower;
-  }
-
-  [[nodiscard]] rcc::Expected<void> lower(rcc::MachineInstr &Instruction, rcc::MachineFunction &,
-                                          const rcc::TargetDescription &,
-                                          rcc::LegalizationAction) const override {
-    const auto Generic = static_cast<rcc::GenericOpcode>(Instruction.opcode().value());
-    return Instruction.setOpcode(rcc::opcode(Generic == rcc::GenericOpcode::G_ADD
-                                                 ? rcc::GenericOpcode::G_SUB
-                                                 : rcc::GenericOpcode::G_ADD));
-  }
-};
-
-class BackwardInvalidatingLegalizer final : public rcc::TargetLegalizerInfo {
-public:
-  [[nodiscard]] rcc::Expected<rcc::LegalizationAction>
-  classify(const rcc::MachineInstr &Instruction, const rcc::MachineFunction &,
-           const rcc::TargetDescription &) const override {
-    return Instruction.opcode() == rcc::opcode(rcc::GenericOpcode::G_SUB)
-               ? rcc::LegalizationAction::Custom
-               : rcc::LegalizationAction::Legal;
-  }
-
-  [[nodiscard]] rcc::Expected<void> lower(rcc::MachineInstr &Instruction,
-                                          rcc::MachineFunction &Function,
-                                          const rcc::TargetDescription &,
-                                          rcc::LegalizationAction) const override {
-    for (rcc::MachineInstr *Candidate : Function.allInstructions()) {
-      if (Candidate != &Instruction &&
-          Candidate->opcode() == rcc::opcode(rcc::GenericOpcode::G_ADD)) {
-        auto Invalidated = Candidate->setOpcode(rcc::opcode(rcc::GenericOpcode::G_SUB));
-        if (!Invalidated)
-          return std::unexpected(Invalidated.error());
-        break;
-      }
-    }
-    return Instruction.setOpcode(
-        rcc::Opcode::fromValue(static_cast<std::uint32_t>(rcc::riscv::InstructionOpcode::ADD)));
-  }
-};
-
-class MutatingFailingSelector final : public rcc::TargetInstructionSelector {
-public:
-  [[nodiscard]] rcc::Expected<void> canSelect(const rcc::MachineInstr &,
-                                              const rcc::MachineFunction &,
-                                              const rcc::TargetDescription &) const override {
-    return {};
-  }
-
-  [[nodiscard]] rcc::Expected<void> select(rcc::MachineInstr &Instruction, rcc::MachineFunction &,
-                                           const rcc::TargetDescription &) const override {
-    auto Mutation = Instruction.setOpcode(rcc::opcode(rcc::GenericOpcode::G_SUB));
-    if (!Mutation)
-      return std::unexpected(Mutation.error());
-    return rcc::makeUnexpected(rcc::ErrorCode::Unsupported, "test selector rejected its renderer");
-  }
-};
-
-class RecordingSelector final : public rcc::TargetInstructionSelector {
-public:
-  explicit RecordingSelector(const rcc::TargetInstructionSelector &Delegate)
-      : Delegate(&Delegate) {}
-
-  [[nodiscard]] rcc::Expected<void> canSelect(const rcc::MachineInstr &Instruction,
-                                              const rcc::MachineFunction &Function,
-                                              const rcc::TargetDescription &Target) const override {
-    return Delegate->canSelect(Instruction, Function, Target);
-  }
-
-  [[nodiscard]] rcc::Expected<void> select(rcc::MachineInstr &Instruction,
-                                           rcc::MachineFunction &Function,
-                                           const rcc::TargetDescription &Target) const override {
-    SelectedIDs.push_back(Instruction.stableID().value());
-    return Delegate->select(Instruction, Function, Target);
-  }
-
-  [[nodiscard]] const std::vector<std::uint64_t> &selectedIDs() const noexcept {
-    return SelectedIDs;
-  }
-
-private:
-  const rcc::TargetInstructionSelector *Delegate;
-  mutable std::vector<std::uint64_t> SelectedIDs;
-};
-
-class TwoStepSelector final : public rcc::TargetInstructionSelector {
-public:
-  [[nodiscard]] rcc::Expected<void> canSelect(const rcc::MachineInstr &,
-                                              const rcc::MachineFunction &,
-                                              const rcc::TargetDescription &) const override {
-    return {};
-  }
-
-  [[nodiscard]] rcc::Expected<void> select(rcc::MachineInstr &Instruction, rcc::MachineFunction &,
-                                           const rcc::TargetDescription &) const override {
-    ++Selections;
-    if (Instruction.opcode() == rcc::opcode(rcc::GenericOpcode::G_ADD))
-      return Instruction.setOpcode(rcc::opcode(rcc::GenericOpcode::G_SUB));
-    if (Instruction.opcode() == rcc::opcode(rcc::GenericOpcode::G_SUB)) {
-      return Instruction.setOpcode(
-          rcc::Opcode::fromValue(static_cast<std::uint32_t>(rcc::riscv::InstructionOpcode::ADD)));
-    }
-    return rcc::makeUnexpected(rcc::ErrorCode::Unsupported,
-                               "two-step selector received an unexpected opcode");
-  }
-
-  [[nodiscard]] std::size_t selections() const noexcept {
-    return Selections;
-  }
-
-private:
-  mutable std::size_t Selections = 0;
-};
-
-[[nodiscard]] FunctionFixture createFixture(TestContext &Context, std::string_view Name,
-                                            std::uint64_t ID) {
-  auto Function =
-      rcc::MachineFunction::create(std::string(Name), rcc::MachineFunctionStableID::fromValue(ID));
-  Context.expect(Function.has_value(), "machine pipeline function creation must succeed");
-  if (!Function)
-    return {};
-  auto Entry = (*Function)->createBasicBlock();
-  Context.expect(Entry.has_value(), "machine pipeline block creation must succeed");
-  if (!Entry || !(*Function)->appendBlock(**Entry))
-    return {};
-  return {std::move(*Function), *Entry};
-}
-
-[[nodiscard]] rcc::Register createRegister(TestContext &Context, rcc::MachineFunction &Function,
-                                           std::uint32_t Bits) {
-  auto Type = rcc::LLT::makeInteger(Bits);
-  Context.expect(Type.has_value(), "integer LLT construction must succeed");
-  if (!Type)
-    return {};
-  auto Reg = Function.registerInfo().createVirtualRegister(*Type);
-  Context.expect(Reg.has_value(), "virtual register construction must succeed");
-  return Reg ? *Reg : rcc::Register{};
-}
-
-[[nodiscard]] rcc::Register createFloatRegister(TestContext &Context,
-                                                rcc::MachineFunction &Function) {
-  auto Type = rcc::LLT::makeFloat(rcc::FloatSemantics::IEEEDouble);
-  Context.expect(Type.has_value(), "floating LLT construction must succeed");
-  if (!Type)
-    return {};
-  auto Reg = Function.registerInfo().createVirtualRegister(*Type);
-  Context.expect(Reg.has_value(), "floating virtual register construction must succeed");
-  return Reg ? *Reg : rcc::Register{};
-}
-
-[[nodiscard]] bool assignGPR(rcc::MachineFunction &Function, rcc::Register Reg) {
-  const auto Bank =
-      rcc::RegisterBankID::fromValue(static_cast<std::uint32_t>(rcc::riscv::RegisterBank::GPR));
-  const auto RegClass =
-      rcc::RegisterClassID::fromValue(static_cast<std::uint32_t>(rcc::riscv::RegisterClass::GPR));
-  return Function.registerInfo().setRegisterBank(Reg, Bank).has_value() &&
-         Function.registerInfo().setRegisterClass(Reg, RegClass).has_value();
-}
-
-[[nodiscard]] bool buildConstant(TestContext &Context, rcc::MachineIRBuilder &Builder,
-                                 rcc::Register Destination, std::int64_t Value) {
-  auto Pending = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_CONSTANT));
-  if (!Pending || !Pending->addDef(Destination) || !Pending->addImmediate(Value) ||
-      !Pending->build()) {
-    Context.expect(false, "generic constant construction must succeed");
-    return false;
-  }
-  return true;
-}
-
-[[nodiscard]] bool buildAdd(TestContext &Context, rcc::MachineIRBuilder &Builder,
-                            rcc::Register Destination, rcc::Register Left, rcc::Register Right) {
-  auto Pending = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_ADD));
-  if (!Pending || !Pending->addDef(Destination) || !Pending->addUse(Left) ||
-      !Pending->addUse(Right) || !Pending->build()) {
-    Context.expect(false, "generic add construction must succeed");
-    return false;
-  }
-  return true;
-}
-
-void testNullAndMissingContracts(TestContext &Context) {
-  auto Target = rcc::riscv::createTargetDescription();
-  auto Fixture = createFixture(Context, "pipeline_contracts", 1);
-  Context.expect(Target.has_value() && Fixture.Function != nullptr && Fixture.Entry != nullptr,
-                 "pipeline contract fixture must be complete");
-  if (!Target || !Fixture.Function)
-    return;
-
-  rcc::LegalizerPass NullPass(nullptr);
-  rcc::MachineAnalysisManager Analyses;
-  auto NullResult = NullPass.run(*Fixture.Function, *Target, Analyses);
-  Context.expect(!NullResult && NullResult.error().code() == rcc::ErrorCode::InvalidArgument,
-                 "a null legalizer interface must be rejected");
-  Context.expect(Fixture.Function->properties().empty(),
-                 "a rejected pass must not publish function properties");
-
-  rcc::LegalizerPass ValidPass(rcc::riscv::legalizerInfo());
-  auto MissingResult = ValidPass.run(*Fixture.Function, *Target, Analyses);
-  Context.expect(!MissingResult &&
-                     MissingResult.error().code() == rcc::ErrorCode::VerificationError,
-                 "a pass with missing prerequisites must be rejected");
-}
-
-void testPipelineAndUnsupportedRollback(TestContext &Context) {
-  auto Target = rcc::riscv::createTargetDescription();
-  auto Fixture = createFixture(Context, "pipeline_success", 2);
-  Context.expect(Target.has_value() && Fixture.Function != nullptr && Fixture.Entry != nullptr,
-                 "pipeline success fixture must be complete");
-  if (!Target || !Fixture.Function || Fixture.Entry == nullptr)
-    return;
-
-  const rcc::Register Left = createRegister(Context, *Fixture.Function, 64);
-  const rcc::Register Right = createRegister(Context, *Fixture.Function, 64);
-  const rcc::Register Result = createRegister(Context, *Fixture.Function, 64);
-  rcc::MachineIRBuilder Builder(*Fixture.Function, *Target);
-  Context.expect(Builder.setInsertPoint(*Fixture.Entry).has_value(),
-                 "pipeline insertion point must be valid");
-  if (Left.isNoRegister() || Right.isNoRegister() || Result.isNoRegister() ||
-      !buildConstant(Context, Builder, Left, 42) || !buildConstant(Context, Builder, Right, 1) ||
-      !buildAdd(Context, Builder, Result, Left, Right))
-    return;
-
-  Fixture.Function->properties() = {rcc::MachineFunctionProperty::IsSSA,
-                                    rcc::MachineFunctionProperty::TracksLiveness};
-  rcc::MachinePassManager Pipeline;
-  Context.expect(Pipeline.addPass(std::make_unique<rcc::LegalizerPass>(rcc::riscv::legalizerInfo()))
-                     .has_value(),
-                 "legalizer must be accepted by the pass manager");
-  Context.expect(
-      Pipeline
-          .addPass(std::make_unique<rcc::RegisterBankSelectPass>(rcc::riscv::registerBankInfo()))
-          .has_value(),
-      "register-bank selector must be accepted by the pass manager");
-  Context.expect(
-      Pipeline
-          .addPass(std::make_unique<rcc::InstructionSelectPass>(rcc::riscv::instructionSelector()))
-          .has_value(),
-      "instruction selector must be accepted by the pass manager");
-  rcc::MachineAnalysisManager Analyses;
-  auto Run = Pipeline.run(*Fixture.Function, *Target, Analyses);
-  Context.expect(Run.has_value(), "RV64GC generic pipeline must complete");
-  Context.expect(Fixture.Function->properties().has(rcc::MachineFunctionProperty::Selected),
-                 "successful instruction selection must publish Selected");
-  Context.expect(Fixture.Function->firstBlock()->firstInstruction() != nullptr,
-                 "selected instructions must remain attached to their block");
-  for (const rcc::MachineInstr *Instruction : Fixture.Function->allInstructions())
-    Context.expect(!rcc::isGenericOpcode(Instruction->opcode()),
-                   "successful instruction selection must remove generic opcodes");
-
-  auto Unsupported = createFixture(Context, "pipeline_unsupported", 3);
-  Context.expect(Unsupported.Function != nullptr && Unsupported.Entry != nullptr,
-                 "unsupported pipeline fixture must be complete");
-  if (!Unsupported.Function || Unsupported.Entry == nullptr)
-    return;
-  const rcc::Register UnsupportedReg = createFloatRegister(Context, *Unsupported.Function);
-  const rcc::Register UnsupportedSource = createFloatRegister(Context, *Unsupported.Function);
-  rcc::MachineIRBuilder UnsupportedBuilder(*Unsupported.Function, *Target);
-  Context.expect(UnsupportedBuilder.setInsertPoint(*Unsupported.Entry).has_value(),
-                 "unsupported pipeline insertion point must be valid");
-  if (UnsupportedReg.isNoRegister() || UnsupportedSource.isNoRegister())
-    return;
-  auto Pending = UnsupportedBuilder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_FEXP));
-  Context.expect(Pending.has_value(), "unsupported generic instruction must be constructible");
-  if (!Pending)
-    return;
-  auto Built = Pending->addDef(UnsupportedReg);
-  Context.expect(Built.has_value(), "unsupported generic definition must be accepted");
-  if (!Built)
-    return;
-  Context.expect(Pending->addUse(UnsupportedSource).has_value() && Pending->build().has_value(),
-                 "unsupported floating operation must be constructible");
-  Unsupported.Function->properties() = {rcc::MachineFunctionProperty::IsSSA,
-                                        rcc::MachineFunctionProperty::TracksLiveness};
-  rcc::MachinePassManager OnlyLegalizer;
-  Context.expect(
-      OnlyLegalizer.addPass(std::make_unique<rcc::LegalizerPass>(rcc::riscv::legalizerInfo()))
-          .has_value(),
-      "standalone legalizer must be accepted");
-  rcc::MachineAnalysisManager UnsupportedAnalyses;
-  auto Failure = OnlyLegalizer.run(*Unsupported.Function, *Target, UnsupportedAnalyses);
-  Context.expect(!Failure && Failure.error().code() == rcc::ErrorCode::Unsupported,
-                 "unsupported generic instructions must produce a target diagnostic");
-  Context.expect(!Failure && Failure.error().message().find("G_FEXP") != std::string::npos,
-                 "unsupported legalization diagnostics must name the rejected opcode");
-  Context.expect(
-      Unsupported.Function->properties().has(rcc::MachineFunctionProperty::IsSSA) &&
-          !Unsupported.Function->properties().has(rcc::MachineFunctionProperty::Legalized),
-      "failed legalizer execution must not publish Legalized");
-}
-
-void testBankConflict(TestContext &Context) {
-  auto Target = rcc::riscv::createTargetDescription();
-  auto Fixture = createFixture(Context, "pipeline_bank_conflict", 4);
-  Context.expect(Target.has_value() && Fixture.Function != nullptr && Fixture.Entry != nullptr,
-                 "bank conflict fixture must be complete");
-  if (!Target || !Fixture.Function || Fixture.Entry == nullptr)
-    return;
-  const rcc::Register Value = createRegister(Context, *Fixture.Function, 64);
-  Context.expect(
-      Fixture.Function->registerInfo()
-          .setRegisterBank(Value, rcc::RegisterBankID::fromValue(
-                                      static_cast<std::uint32_t>(rcc::riscv::RegisterBank::FPR)))
-          .has_value(),
-      "conflicting bank assignment must be constructible");
-  Fixture.Function->properties() = {rcc::MachineFunctionProperty::Legalized};
-  rcc::RegisterBankSelectPass Pass(rcc::riscv::registerBankInfo());
-  rcc::MachineAnalysisManager Analyses;
-  auto Result = Pass.run(*Fixture.Function, *Target, Analyses);
-  Context.expect(!Result && Result.error().code() == rcc::ErrorCode::VerificationError,
-                 "bank selection must reject a conflicting pre-existing bank");
-  auto Info = Fixture.Function->registerInfo().virtualRegisterInfo(Value);
-  Context.expect(Info && Info->get().Bank, "failed bank selection must preserve a bank assignment");
-  if (!Info || !Info->get().Bank)
-    return;
-  const rcc::RegisterBankID Bank = Info->get().Bank.value_or(rcc::RegisterBankID{});
-  Context.expect(Bank == rcc::RegisterBankID::fromValue(
-                             static_cast<std::uint32_t>(rcc::riscv::RegisterBank::FPR)),
-                 "failed bank selection must preserve the original bank assignment");
-}
-
-void testBankClassOnlyChange(TestContext &Context) {
-  auto Target = rcc::riscv::createTargetDescription();
-  auto Fixture = createFixture(Context, "pipeline_bank_class", 5);
-  Context.expect(Target.has_value() && Fixture.Function != nullptr && Fixture.Entry != nullptr,
-                 "bank class fixture must be complete");
-  if (!Target || !Fixture.Function || Fixture.Entry == nullptr)
-    return;
-  const rcc::Register Value = createRegister(Context, *Fixture.Function, 64);
-  rcc::MachineIRBuilder Builder(*Fixture.Function, *Target);
-  if (Value.isNoRegister() || !Builder.setInsertPoint(*Fixture.Entry) ||
-      !buildConstant(Context, Builder, Value, 7))
-    return;
-  const auto GPR =
-      rcc::RegisterBankID::fromValue(static_cast<std::uint32_t>(rcc::riscv::RegisterBank::GPR));
-  Context.expect(Fixture.Function->registerInfo().setRegisterBank(Value, GPR).has_value(),
-                 "pre-existing GPR bank must be assignable");
-  Fixture.Function->properties() = {rcc::MachineFunctionProperty::Legalized};
-  rcc::RegisterBankSelectPass Pass(rcc::riscv::registerBankInfo());
-  rcc::MachineAnalysisManager Analyses;
-  auto Result = Pass.run(*Fixture.Function, *Target, Analyses);
-  Context.expect(Result.has_value() && Result->Changed &&
-                     Result->Changes.has(rcc::MachinePassChange::Registers),
-                 "bank selection must report a class-only register change");
-  auto Info = Fixture.Function->registerInfo().virtualRegisterInfo(Value);
-  Context.expect(Info && Info->get().Bank && Info->get().RegClass,
-                 "bank selection must publish both bank and class");
-  if (!Info || !Info->get().RegClass)
-    return;
-  Context.expect(Info->get().RegClass.value_or(rcc::RegisterClassID{}) ==
-                     rcc::RegisterClassID::fromValue(
-                         static_cast<std::uint32_t>(rcc::riscv::RegisterClass::GPR)),
-                 "i64 GPR bank must select the GPR class");
-}
-
-void testLegalizerCycleDiagnostic(TestContext &Context) {
-  auto Target = rcc::riscv::createTargetDescription();
-  auto Fixture = createFixture(Context, "pipeline_legalizer_cycle", 6);
-  Context.expect(Target.has_value() && Fixture.Function != nullptr && Fixture.Entry != nullptr,
-                 "legalizer cycle fixture must be complete");
-  if (!Target || !Fixture.Function || Fixture.Entry == nullptr)
-    return;
-  const rcc::Register Left = createRegister(Context, *Fixture.Function, 64);
-  const rcc::Register Right = createRegister(Context, *Fixture.Function, 64);
-  const rcc::Register Result = createRegister(Context, *Fixture.Function, 64);
-  rcc::MachineIRBuilder Builder(*Fixture.Function, *Target);
-  if (Left.isNoRegister() || Right.isNoRegister() || Result.isNoRegister() ||
-      !Builder.setInsertPoint(*Fixture.Entry) || !buildAdd(Context, Builder, Result, Left, Right))
-    return;
-  Fixture.Function->properties() = {rcc::MachineFunctionProperty::IsSSA,
-                                    rcc::MachineFunctionProperty::TracksLiveness};
-  TogglingLegalizer Legalizer;
-  rcc::LegalizerPass StablePass(Legalizer);
-  rcc::MachineAnalysisManager Analyses;
-  auto ResultRun = StablePass.run(*Fixture.Function, *Target, Analyses);
-  Context.expect(!ResultRun && ResultRun.error().code() == rcc::ErrorCode::InternalError,
-                 "repeated legalization states must report InternalError");
-  Context.expect(Fixture.Entry->firstInstruction() != nullptr &&
-                     Fixture.Entry->firstInstruction()->opcode() ==
-                         rcc::opcode(rcc::GenericOpcode::G_ADD),
-                 "failed legalization preflight must preserve the original instruction");
-  Context.expect(!Fixture.Function->properties().has(rcc::MachineFunctionProperty::Legalized),
-                 "a failed legalization cycle must not publish Legalized");
-}
-
-void testLegalizerRevisitsInvalidatedInstructions(TestContext &Context) {
-  auto Target = rcc::riscv::createTargetDescription();
-  auto Fixture = createFixture(Context, "pipeline_legalizer_revisit", 7);
-  if (!Target || !Fixture.Function || Fixture.Entry == nullptr)
-    return;
-  const rcc::Register Left = createRegister(Context, *Fixture.Function, 64);
-  const rcc::Register Right = createRegister(Context, *Fixture.Function, 64);
-  const rcc::Register FirstResult = createRegister(Context, *Fixture.Function, 64);
-  const rcc::Register SecondResult = createRegister(Context, *Fixture.Function, 64);
-  rcc::MachineIRBuilder Builder(*Fixture.Function, *Target);
-  if (Left.isNoRegister() || Right.isNoRegister() || FirstResult.isNoRegister() ||
-      SecondResult.isNoRegister() || !Builder.setInsertPoint(*Fixture.Entry) ||
-      !buildAdd(Context, Builder, FirstResult, Left, Right) ||
-      !buildAdd(Context, Builder, SecondResult, Left, Right))
-    return;
-  rcc::MachineInstr *First = Fixture.Entry->firstInstruction();
-  rcc::MachineInstr *Second = First == nullptr ? nullptr : First->next();
-  if (Second == nullptr || !Second->setOpcode(rcc::opcode(rcc::GenericOpcode::G_SUB)))
-    return;
-
-  Fixture.Function->properties() = {rcc::MachineFunctionProperty::IsSSA,
-                                    rcc::MachineFunctionProperty::TracksLiveness};
-  BackwardInvalidatingLegalizer Legalizer;
-  rcc::LegalizerPass Pass(Legalizer);
-  rcc::MachineAnalysisManager Analyses;
-  auto Run = Pass.run(*Fixture.Function, *Target, Analyses);
-  const rcc::Opcode LegalOpcode =
-      rcc::Opcode::fromValue(static_cast<std::uint32_t>(rcc::riscv::InstructionOpcode::ADD));
-  Context.expect(Run && First->opcode() == LegalOpcode && Second->opcode() == LegalOpcode,
-                 "legalizer must revisit an earlier instruction invalidated by a later lowering");
-}
-
-void testInstructionSelectionTransaction(TestContext &Context) {
-  auto Target = rcc::riscv::createTargetDescription();
-  auto Fixture = createFixture(Context, "pipeline_selection_transaction", 8);
-  if (!Target || !Fixture.Function || Fixture.Entry == nullptr)
-    return;
-  const rcc::Register Left = createRegister(Context, *Fixture.Function, 64);
-  const rcc::Register Right = createRegister(Context, *Fixture.Function, 64);
-  const rcc::Register Result = createRegister(Context, *Fixture.Function, 64);
-  rcc::MachineIRBuilder Builder(*Fixture.Function, *Target);
-  if (Left.isNoRegister() || Right.isNoRegister() || Result.isNoRegister() ||
-      !Builder.setInsertPoint(*Fixture.Entry) || !buildAdd(Context, Builder, Result, Left, Right) ||
-      !assignGPR(*Fixture.Function, Left) || !assignGPR(*Fixture.Function, Right) ||
-      !assignGPR(*Fixture.Function, Result)) {
-    return;
-  }
-  rcc::MachineInstr *Original = Fixture.Entry->firstInstruction();
-  if (Original == nullptr)
-    return;
-  const rcc::Opcode OriginalOpcode = Original->opcode();
-  const std::size_t OriginalOperandCount = Original->operandCount();
-  Fixture.Function->properties() = {rcc::MachineFunctionProperty::Legalized,
-                                    rcc::MachineFunctionProperty::RegBankSelected};
-  MutatingFailingSelector Selector;
-  rcc::InstructionSelectPass Pass(Selector);
-  rcc::MachineAnalysisManager Analyses;
-  auto Run = Pass.run(*Fixture.Function, *Target, Analyses);
-  Context.expect(!Run && Run.error().code() == rcc::ErrorCode::Unsupported,
-                 "a renderer failure must be reported before publication");
-  Context.expect(Original->opcode() == OriginalOpcode &&
-                     Original->operandCount() == OriginalOperandCount &&
-                     Fixture.Entry->instructionCount() == 1,
-                 "a renderer failure must leave the original MachineIR unchanged");
-}
-
-void testInstructionSelectionOrder(TestContext &Context) {
-  auto Target = rcc::riscv::createTargetDescription();
-  auto Fixture = createFixture(Context, "pipeline_selection_order", 9);
-  if (!Target || !Fixture.Function || Fixture.Entry == nullptr)
-    return;
-  const rcc::Register Left = createRegister(Context, *Fixture.Function, 64);
-  const rcc::Register Right = createRegister(Context, *Fixture.Function, 64);
-  const rcc::Register Result = createRegister(Context, *Fixture.Function, 64);
-  rcc::MachineIRBuilder Builder(*Fixture.Function, *Target);
-  if (Left.isNoRegister() || Right.isNoRegister() || Result.isNoRegister() ||
-      !Builder.setInsertPoint(*Fixture.Entry) || !buildConstant(Context, Builder, Left, 6) ||
-      !buildConstant(Context, Builder, Right, 7) ||
-      !buildAdd(Context, Builder, Result, Left, Right) || !assignGPR(*Fixture.Function, Left) ||
-      !assignGPR(*Fixture.Function, Right) || !assignGPR(*Fixture.Function, Result)) {
-    return;
-  }
-  std::vector<std::uint64_t> LayoutIDs;
-  for (const rcc::MachineInstr *Instruction = Fixture.Entry->firstInstruction();
-       Instruction != nullptr; Instruction = Instruction->next()) {
-    LayoutIDs.push_back(Instruction->stableID().value());
-  }
-  Fixture.Function->properties() = {rcc::MachineFunctionProperty::Legalized,
-                                    rcc::MachineFunctionProperty::RegBankSelected};
-  RecordingSelector Selector(rcc::riscv::instructionSelector());
-  rcc::InstructionSelectPass Pass(Selector);
-  rcc::MachineAnalysisManager Analyses;
-  auto Run = Pass.run(*Fixture.Function, *Target, Analyses);
-  Context.expect(Run.has_value(), "recorded instruction selection must complete");
-  std::ranges::reverse(LayoutIDs);
-  std::vector<std::uint64_t> Expected = LayoutIDs;
-  Expected.insert(Expected.end(), LayoutIDs.begin(), LayoutIDs.end());
-  Context.expect(
-      Selector.selectedIDs() == Expected,
-      "instruction selection must use stable block-postorder and reverse instruction order");
-}
-
-void testInstructionSelectionWorklist(TestContext &Context) {
-  auto Target = rcc::riscv::createTargetDescription();
-  auto Fixture = createFixture(Context, "pipeline_selection_worklist", 10);
-  if (!Target || !Fixture.Function || Fixture.Entry == nullptr)
-    return;
-  const rcc::Register Left = createRegister(Context, *Fixture.Function, 64);
-  const rcc::Register Right = createRegister(Context, *Fixture.Function, 64);
-  const rcc::Register Result = createRegister(Context, *Fixture.Function, 64);
-  rcc::MachineIRBuilder Builder(*Fixture.Function, *Target);
-  if (Left.isNoRegister() || Right.isNoRegister() || Result.isNoRegister() ||
-      !Builder.setInsertPoint(*Fixture.Entry) || !buildAdd(Context, Builder, Result, Left, Right) ||
-      !assignGPR(*Fixture.Function, Left) || !assignGPR(*Fixture.Function, Right) ||
-      !assignGPR(*Fixture.Function, Result)) {
-    return;
-  }
-  Fixture.Function->properties() = {rcc::MachineFunctionProperty::Legalized,
-                                    rcc::MachineFunctionProperty::RegBankSelected};
-  TwoStepSelector Selector;
-  rcc::InstructionSelectPass Pass(Selector);
-  rcc::MachineAnalysisManager Analyses;
-  auto Run = Pass.run(*Fixture.Function, *Target, Analyses);
-  Context.expect(Run.has_value(), "a progressing multi-step selection must complete");
-  Context.expect(Selector.selections() == 4,
-                 "transaction preflight and publication must each select both generic states");
-  Context.expect(Fixture.Entry->firstInstruction() != nullptr &&
-                     Fixture.Entry->firstInstruction()->opcode() ==
-                         rcc::Opcode::fromValue(
-                             static_cast<std::uint32_t>(rcc::riscv::InstructionOpcode::ADD)),
-                 "the selection worklist must revisit a progressing generic root");
-}
-
-void testExtendedRV64GCPipeline(TestContext &Context) {
-  auto Target = rcc::riscv::createTargetDescription();
-  auto Fixture = createFixture(Context, "pipeline_extended_rv64gc", 7);
-  Context.expect(Target.has_value() && Fixture.Function != nullptr && Fixture.Entry != nullptr,
-                 "extended pipeline fixture must be complete");
-  if (!Target || !Fixture.Function || Fixture.Entry == nullptr)
-    return;
-  auto I1 = rcc::LLT::makeInteger(1);
-  auto I64 = rcc::LLT::makeInteger(64);
-  auto Pointer = rcc::LLT::makePointer(0, 64);
-  if (!I1 || !I64 || !Pointer)
-    return;
-  const rcc::Register Left = createRegister(Context, *Fixture.Function, 64);
-  const rcc::Register Right = createRegister(Context, *Fixture.Function, 64);
-  const rcc::Register Condition =
-      Fixture.Function->registerInfo().createVirtualRegister(*I1).value_or(rcc::Register{});
-  const rcc::Register Selected = createRegister(Context, *Fixture.Function, 64);
-  const rcc::Register Sum = createRegister(Context, *Fixture.Function, 64);
-  const rcc::Register Overflow =
-      Fixture.Function->registerInfo().createVirtualRegister(*I1).value_or(rcc::Register{});
-  const rcc::Register Quotient = createRegister(Context, *Fixture.Function, 64);
-  const rcc::Register Remainder = createRegister(Context, *Fixture.Function, 64);
-  const rcc::Register Address =
-      Fixture.Function->registerInfo().createVirtualRegister(*Pointer).value_or(rcc::Register{});
-  const rcc::Register AtomicResult = createRegister(Context, *Fixture.Function, 64);
-  const std::array Registers{Left,     Right,    Condition, Selected, Sum,
-                             Overflow, Quotient, Remainder, Address,  AtomicResult};
-  if (std::ranges::any_of(Registers, [](rcc::Register Reg) { return Reg.isNoRegister(); }))
-    return;
-  rcc::MachineIRBuilder Builder(*Fixture.Function, *Target);
-  if (!Builder.setInsertPoint(*Fixture.Entry) || !buildConstant(Context, Builder, Left, 41) ||
-      !buildConstant(Context, Builder, Right, 7)) {
-    return;
-  }
-  auto Compare = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_ICMP));
-  if (!Compare || !Compare->addDef(Condition) ||
-      !Compare->addIntegerPredicate(rcc::IntegerPredicate::UnsignedGreaterThan) ||
-      !Compare->addUse(Left) || !Compare->addUse(Right) || !Compare->build()) {
-    return;
-  }
-  auto Select = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_SELECT));
-  if (!Select || !Select->addDef(Selected) || !Select->addUse(Condition) || !Select->addUse(Left) ||
-      !Select->addUse(Right) || !Select->build()) {
-    return;
-  }
-  auto AddOverflow = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_UADDO));
-  if (!AddOverflow || !AddOverflow->addDef(Sum) || !AddOverflow->addDef(Overflow) ||
-      !AddOverflow->addUse(Left) || !AddOverflow->addUse(Right) || !AddOverflow->build()) {
-    return;
-  }
-  auto DivRem = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_SDIVREM));
-  if (!DivRem || !DivRem->addDef(Quotient) || !DivRem->addDef(Remainder) || !DivRem->addUse(Left) ||
-      !DivRem->addUse(Right) || !DivRem->build()) {
-    return;
-  }
-  auto AddressDefinition = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_IMPLICIT_DEF));
-  if (!AddressDefinition || !AddressDefinition->addDef(Address) || !AddressDefinition->build())
-    return;
-  auto Size = rcc::MemorySize::fixed(8);
-  auto Align = rcc::Alignment::create(8);
-  if (!Size || !Align)
-    return;
-  rcc::MachineMemOperandDesc Description;
-  Description.Accesses = {rcc::MemoryAccessFlag::Load, rcc::MemoryAccessFlag::Store};
-  Description.AtomicKind = rcc::AtomicOperation::ReadModifyWrite;
-  Description.SuccessOrdering = rcc::AtomicOrdering::SequentiallyConsistent;
-  Description.Size = *Size;
-  Description.Align = *Align;
-  Description.Base = rcc::MemoryBase::stack();
-  auto Memory = Fixture.Function->createMemOperand(std::move(Description));
-  if (!Memory)
-    return;
-  auto Atomic = Builder.buildInstr(rcc::opcode(rcc::GenericOpcode::G_ATOMICRMW_ADD));
-  if (!Atomic || !Atomic->addDef(AtomicResult) || !Atomic->addUse(Address) ||
-      !Atomic->addUse(Selected) || !Atomic->addMemOperand(**Memory) || !Atomic->build()) {
-    return;
-  }
-
-  Fixture.Function->properties() = {rcc::MachineFunctionProperty::IsSSA,
-                                    rcc::MachineFunctionProperty::TracksLiveness};
-  rcc::MachinePassManager Pipeline;
-  if (!Pipeline.addPass(std::make_unique<rcc::LegalizerPass>(rcc::riscv::legalizerInfo())) ||
-      !Pipeline.addPass(
-          std::make_unique<rcc::RegisterBankSelectPass>(rcc::riscv::registerBankInfo())) ||
-      !Pipeline.addPass(
-          std::make_unique<rcc::InstructionSelectPass>(rcc::riscv::instructionSelector()))) {
-    Context.expect(false, "extended RV64GC pipeline construction must succeed");
-    return;
-  }
-  rcc::MachineAnalysisManager Analyses;
-  auto Run = Pipeline.run(*Fixture.Function, *Target, Analyses);
-  Context.expect(Run.has_value(), "extended RV64GC pipeline must complete");
-  Context.expect(Run && Fixture.Function->properties().has(rcc::MachineFunctionProperty::Selected),
-                 "extended pipeline must publish Selected");
-  for (const rcc::MachineInstr *Instruction : Fixture.Function->allInstructions()) {
-    Context.expect(!rcc::isGenericOpcode(Instruction->opcode()),
-                   "extended pipeline must eliminate every generic opcode");
-    Context.expect(
-        Target->validateInstruction(*Instruction, Fixture.Function->registerInfo()).has_value(),
-        "extended pipeline output must satisfy target descriptors");
-  }
-}
-
-} // namespace
-
-int main() {
-  TestContext Context;
-  testNullAndMissingContracts(Context);
-  testPipelineAndUnsupportedRollback(Context);
-  testBankConflict(Context);
-  testBankClassOnlyChange(Context);
-  testLegalizerCycleDiagnostic(Context);
-  testLegalizerRevisitsInvalidatedInstructions(Context);
-  testInstructionSelectionTransaction(Context);
-  testInstructionSelectionOrder(Context);
-  testInstructionSelectionWorklist(Context);
-  testExtendedRV64GCPipeline(Context);
-  return Context.result();
-}