[CodeGen] Implement machine optimization and scheduling

1 files changed, 518 insertions, 0 deletions

diff --git a/backend/unittests/CodeGen/MachineSchedulingTest.cpp b/backend/unittests/CodeGen/MachineSchedulingTest.cpp
new file mode 100644
index 0000000..a485146
--- /dev/null
+++ b/backend/unittests/CodeGen/MachineSchedulingTest.cpp
@@ -0,0 +1,518 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "rcc/CodeGen/MachineBasicBlock.h"
+#include "rcc/CodeGen/MachineFunction.h"
+#include "rcc/CodeGen/MachineIRBuilder.h"
+#include "rcc/CodeGen/MachineInstr.h"
+#include "rcc/CodeGen/MachineLiveness.h"
+#include "rcc/CodeGen/MachineRegisterInfo.h"
+#include "rcc/CodeGen/MachineScheduler.h"
+#include "rcc/CodeGen/PostRAScheduler.h"
+#include "rcc/CodeGen/ScheduleDAG.h"
+#include "rcc/CodeGen/ScheduleHazardRecognizer.h"
+#include "rcc/CodeGen/TargetSchedulingModel.h"
+#include "rcc/Target/RISCV/RISCVCodeGen.h"
+#include "rcc/Target/RISCV/RISCVTarget.h"
+
+#include <array>
+#include <cstdint>
+#include <iostream>
+#include <memory>
+#include <optional>
+#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 Fixture final {
+  std::unique_ptr<rcc::MachineFunction> Function;
+  rcc::MachineBasicBlock *Block = nullptr;
+};
+
+class OnePerCycleHazard final : public rcc::TargetScheduleHazardRecognizer {
+public:
+  [[nodiscard]] std::unique_ptr<rcc::TargetScheduleHazardRecognizer> clone() const override {
+    return std::make_unique<OnePerCycleHazard>(*this);
+  }
+
+  [[nodiscard]] rcc::Expected<rcc::ScheduleHazardType>
+  getHazardType(const rcc::ScheduleUnit &) const override {
+    return Emitted ? rcc::ScheduleHazardType::Hazard : rcc::ScheduleHazardType::NoHazard;
+  }
+
+  [[nodiscard]] rcc::Expected<void> emitInstruction(const rcc::ScheduleUnit &) override {
+    Emitted = true;
+    return {};
+  }
+
+  [[nodiscard]] rcc::Expected<void> advanceCycle() override {
+    Emitted = false;
+    return {};
+  }
+
+  [[nodiscard]] rcc::Expected<void> recedeCycle() override {
+    Emitted = false;
+    return {};
+  }
+
+  [[nodiscard]] rcc::Expected<void> reset() override {
+    Emitted = false;
+    return {};
+  }
+
+private:
+  bool Emitted = false;
+};
+
+class TestSchedulingHooks final : public rcc::TargetSchedulingHooks {
+public:
+  bool MakeADDIBoundary = false;
+  bool AddMutation = false;
+  bool PreferSecondUnit = false;
+  bool EnableDynamicHazards = false;
+
+  [[nodiscard]] bool isSchedulingBoundary(const rcc::MachineInstr &Instruction,
+                                          const rcc::TargetDescription &) const noexcept override {
+    return MakeADDIBoundary &&
+           Instruction.opcode() == rcc::Opcode::fromValue(static_cast<std::uint32_t>(
+                                       rcc::riscv::InstructionOpcode::ADDI));
+  }
+
+  [[nodiscard]] rcc::Expected<void> mutateScheduleDAG(rcc::ScheduleDAG &DAG,
+                                                      const rcc::MachineFunction &,
+                                                      const rcc::TargetDescription &,
+                                                      rcc::ScheduleDAGMode) const override {
+    if (!AddMutation || DAG.units().size() < 2)
+      return {};
+    return DAG.addArtificialDependency(0, 1, 2);
+  }
+
+  [[nodiscard]] std::int64_t candidatePreference(const rcc::ScheduleUnit &Unit,
+                                                 rcc::ScheduleDirection,
+                                                 const rcc::MachineBasicBlock &,
+                                                 std::uint64_t) const noexcept override {
+    return PreferSecondUnit && Unit.ID == 1 ? 100 : 0;
+  }
+
+  [[nodiscard]] std::unique_ptr<rcc::TargetScheduleHazardRecognizer>
+  createHazardRecognizer(rcc::ScheduleDirection) const override {
+    return EnableDynamicHazards ? std::make_unique<OnePerCycleHazard>() : nullptr;
+  }
+};
+
+[[nodiscard]] rcc::Opcode opcode(rcc::riscv::InstructionOpcode Value) noexcept {
+  return rcc::Opcode::fromValue(static_cast<std::uint32_t>(Value));
+}
+
+[[nodiscard]] rcc::Expected<rcc::TargetSchedulingModel>
+makeSchedulingModel(const rcc::TargetSchedulingHooks *Hooks = nullptr) {
+  rcc::TargetSchedulingModelDesc Description;
+  Description.IssueWidth = 2;
+  Description.DispatchLimit = 2;
+  for (const rcc::riscv::SchedulingClassInfo &Class : rcc::riscv::schedulingClasses()) {
+    Description.SchedulingClasses.push_back({
+        .ID = Class.ID,
+        .Name = std::string(Class.Name),
+        .MicroOps = Class.MicroOps,
+        .Latency = Class.Latency,
+        .Resources = {},
+        .WriteLatencies = {{0, Class.Latency}},
+        .ReadAdvances = {},
+    });
+  }
+  Description.PressureSets.push_back({
+      .ID = rcc::RegisterPressureSetID::fromValue(1),
+      .Name = "gpr",
+      .RegisterClasses =
+          {
+              rcc::RegisterClassID::fromValue(
+                  static_cast<std::uint32_t>(rcc::riscv::RegisterClass::GPR)),
+          },
+      .Limit = 27,
+  });
+  Description.Hooks = Hooks;
+  return rcc::TargetSchedulingModel::create(std::move(Description));
+}
+
+[[nodiscard]] rcc::Register physical(TestContext &Context, rcc::riscv::PhysicalRegisterID ID) {
+  auto Value = rcc::riscv::physicalRegister(ID);
+  Context.expect(Value.has_value(), "physical register creation must succeed");
+  return Value ? rcc::Register::fromPhysical(*Value) : rcc::Register{};
+}
+
+[[nodiscard]] Fixture makeFixture(TestContext &Context, std::string Name, std::uint64_t ID) {
+  auto Function =
+      rcc::MachineFunction::create(std::move(Name), rcc::MachineFunctionStableID::fromValue(ID));
+  Context.expect(Function.has_value(), "scheduler function creation must succeed");
+  if (!Function)
+    return {};
+  auto Block = (*Function)->createBasicBlock();
+  Context.expect(Block.has_value() && (*Function)->appendBlock(**Block).has_value(),
+                 "scheduler block creation must succeed");
+  if (!Block)
+    return {};
+  (*Function)->properties().set(rcc::MachineFunctionProperty::Legalized);
+  (*Function)->properties().set(rcc::MachineFunctionProperty::RegBankSelected);
+  (*Function)->properties().set(rcc::MachineFunctionProperty::Selected);
+  (*Function)->properties().set(rcc::MachineFunctionProperty::NoPHIs);
+  (*Function)->properties().set(rcc::MachineFunctionProperty::TiedOpsRewritten);
+  return {std::move(*Function), *Block};
+}
+
+[[nodiscard]] rcc::Register makeGPR(TestContext &Context, rcc::MachineFunction &Function) {
+  auto Type = rcc::LLT::makeInteger(64);
+  auto Reg = Type ? Function.registerInfo().createVirtualRegister(*Type)
+                  : rcc::Expected<rcc::Register>(std::unexpected(
+                        rcc::Error(rcc::ErrorCode::InternalError, "test LLT creation failed")));
+  Context.expect(Reg.has_value(), "scheduler virtual register creation must succeed");
+  if (!Reg)
+    return {};
+  const auto Bank =
+      rcc::RegisterBankID::fromValue(static_cast<std::uint32_t>(rcc::riscv::RegisterBank::GPR));
+  const auto Class =
+      rcc::RegisterClassID::fromValue(static_cast<std::uint32_t>(rcc::riscv::RegisterClass::GPR));
+  Context.expect(Function.registerInfo().setRegisterBank(*Reg, Bank).has_value() &&
+                     Function.registerInfo().setRegisterClass(*Reg, Class).has_value(),
+                 "scheduler virtual register constraints must be assigned");
+  return *Reg;
+}
+
+[[nodiscard]] rcc::MachineInstr *buildADDI(TestContext &Context, rcc::MachineIRBuilder &Builder,
+                                           rcc::Register Destination, rcc::Register Source,
+                                           std::int64_t Immediate) {
+  auto Pending = Builder.buildInstr(opcode(rcc::riscv::InstructionOpcode::ADDI));
+  if (!Pending || !Pending->addDef(Destination) || !Pending->addUse(Source) ||
+      !Pending->addImmediate(Immediate)) {
+    Context.expect(false, "scheduler ADDI construction must succeed");
+    return nullptr;
+  }
+  auto Built = Pending->build();
+  Context.expect(Built.has_value(), "scheduler ADDI insertion must succeed");
+  return Built.value_or(nullptr);
+}
+
+[[nodiscard]] rcc::MachineInstr *buildBinary(TestContext &Context, rcc::MachineIRBuilder &Builder,
+                                             rcc::riscv::InstructionOpcode Opcode,
+                                             rcc::Register Destination, rcc::Register Left,
+                                             rcc::Register Right) {
+  auto Pending = Builder.buildInstr(opcode(Opcode));
+  if (!Pending || !Pending->addDef(Destination) || !Pending->addUse(Left) ||
+      !Pending->addUse(Right)) {
+    Context.expect(false, "scheduler binary instruction construction must succeed");
+    return nullptr;
+  }
+  auto Built = Pending->build();
+  Context.expect(Built.has_value(), "scheduler binary instruction insertion must succeed");
+  return Built.value_or(nullptr);
+}
+
+[[nodiscard]] bool hasDependency(const rcc::ScheduleUnit &Unit, std::size_t Destination,
+                                 rcc::ScheduleDependencyKind Kind) {
+  for (const rcc::ScheduleDependency &Dependency : Unit.Successors) {
+    if (Dependency.Destination == Destination && Dependency.Kind == Kind)
+      return true;
+  }
+  return false;
+}
+
+void testDAGRegisterDependencies(TestContext &Context, const rcc::TargetDescription &Target) {
+  auto Fixture = makeFixture(Context, "schedule_dag", 1);
+  if (!Fixture.Function || Fixture.Block == nullptr)
+    return;
+  rcc::MachineIRBuilder Builder(*Fixture.Function, Target);
+  Context.expect(Builder.setInsertPoint(*Fixture.Block).has_value(),
+                 "schedule DAG insertion point must be established");
+  const rcc::Register X0 = physical(Context, rcc::riscv::PhysicalRegisterID::X0);
+  const rcc::Register X10 = physical(Context, rcc::riscv::PhysicalRegisterID::X10);
+  const rcc::Register Value = makeGPR(Context, *Fixture.Function);
+  const rcc::Register Consumer = makeGPR(Context, *Fixture.Function);
+  rcc::MachineInstr *Definition = buildADDI(Context, Builder, Value, X0, 1);
+  rcc::MachineInstr *Use =
+      buildBinary(Context, Builder, rcc::riscv::InstructionOpcode::ADD, Consumer, Value, X10);
+  rcc::MachineInstr *Redefinition = buildADDI(Context, Builder, Value, X0, 2);
+  std::array<rcc::MachineInstr *, 3> Instructions{Definition, Use, Redefinition};
+  auto DAG = rcc::ScheduleDAG::build(*Fixture.Block, Instructions, *Fixture.Function, Target,
+                                     rcc::riscv::schedulingModel(),
+                                     rcc::ScheduleDAGMode::PreRegisterAllocation);
+  if (!DAG)
+    std::cerr << "schedule DAG failure: " << DAG.error().message() << '\n';
+  Context.expect(DAG.has_value() && DAG->units().size() == 3,
+                 "schedule DAG must create one unit per instruction");
+  if (!DAG)
+    return;
+  Context.expect(hasDependency(DAG->units()[0], 1, rcc::ScheduleDependencyKind::Data),
+                 "schedule DAG must model virtual-register data dependencies");
+  Context.expect(hasDependency(DAG->units()[0], 2, rcc::ScheduleDependencyKind::Output),
+                 "schedule DAG must model virtual-register output dependencies");
+  Context.expect(hasDependency(DAG->units()[1], 2, rcc::ScheduleDependencyKind::Anti),
+                 "schedule DAG must model virtual-register anti dependencies");
+  Context.expect(DAG->units()[0].Latency != 0 && DAG->units()[0].MicroOps != 0,
+                 "schedule DAG must attach target latency and resource facts");
+}
+
+void testHazardScoreboard(TestContext &Context) {
+  auto Hazards = rcc::ScheduleHazardRecognizer::create(rcc::riscv::schedulingModel());
+  Context.expect(Hazards.has_value(), "hazard recognizer construction must succeed");
+  if (!Hazards)
+    return;
+  const auto Memory = rcc::ProcessorResourceID::fromValue(3);
+  rcc::ScheduleUnit Load;
+  Load.MicroOps = 1;
+  Load.Resources = {{Memory, 1}};
+  Context.expect(Hazards->issue(Load, 0).has_value(),
+                 "first memory operation must issue in cycle zero");
+  auto SecondCycle = Hazards->earliestIssueCycle(Load, 0);
+  Context.expect(SecondCycle.has_value() && *SecondCycle == 1,
+                 "single-unit memory resource must serialize operations");
+
+  rcc::ScheduleUnit Wide;
+  Wide.MicroOps = 5;
+  auto Fresh = rcc::ScheduleHazardRecognizer::create(rcc::riscv::schedulingModel());
+  Context.expect(Fresh.has_value() && Fresh->issue(Wide, 0).has_value(),
+                 "multi-cycle dispatch must accept instructions wider than issue width");
+  auto AfterWide = Fresh ? Fresh->earliestIssueCycle(Load, 0)
+                         : rcc::Expected<std::uint64_t>(std::unexpected(
+                               rcc::Error(rcc::ErrorCode::InternalError, "no recognizer")));
+  Context.expect(AfterWide.has_value() && *AfterWide == 3,
+                 "multi-cycle dispatch must block the complete dispatch interval");
+}
+
+void testOperandLatencyAndModelValidation(TestContext &Context) {
+  const rcc::SchedulingClassID ALU = rcc::SchedulingClassID::fromValue(
+      static_cast<std::uint32_t>(rcc::riscv::SchedulingClass::ALU));
+  const rcc::SchedulingClassID Load = rcc::SchedulingClassID::fromValue(
+      static_cast<std::uint32_t>(rcc::riscv::SchedulingClass::LOAD));
+  auto Forwarded = rcc::riscv::schedulingModel().operandLatency(Load, 0, ALU, 1);
+  auto Unforwarded = rcc::riscv::schedulingModel().operandLatency(Load, 0, ALU, 0);
+  auto ALUChain = rcc::riscv::schedulingModel().operandLatency(ALU, 0, ALU, 1);
+  Context.expect(Forwarded.has_value() && *Forwarded == 2 && Unforwarded.has_value() &&
+                     *Unforwarded == 3 && ALUChain.has_value() && *ALUChain == 1,
+                 "operand latency must combine write latency with exact read advance");
+
+  rcc::TargetSchedulingModelDesc Invalid;
+  Invalid.SchedulingClasses.push_back({
+      .ID = ALU,
+      .Name = "invalid",
+      .MicroOps = 1,
+      .Latency = 1,
+      .Resources = {},
+      .WriteLatencies = {{0, 1}, {0, 2}},
+      .ReadAdvances = {},
+  });
+  auto Rejected = rcc::TargetSchedulingModel::create(std::move(Invalid));
+  Context.expect(!Rejected && Rejected.error().code() == rcc::ErrorCode::InvalidArgument,
+                 "scheduling model must reject duplicate operand latency facts");
+}
+
+void testDynamicTargetHazards(TestContext &Context) {
+  TestSchedulingHooks Hooks;
+  Hooks.EnableDynamicHazards = true;
+  auto Model = makeSchedulingModel(&Hooks);
+  Context.expect(Model.has_value(), "dynamic-hazard scheduling model construction must succeed");
+  if (!Model)
+    return;
+
+  rcc::ScheduleUnit First;
+  First.ID = 1;
+  First.MicroOps = 1;
+  rcc::ScheduleUnit Second;
+  Second.ID = 2;
+  Second.MicroOps = 1;
+  auto Top = rcc::ScheduleHazardRecognizer::create(*Model, rcc::ScheduleDirection::TopDown);
+  Context.expect(Top.has_value() && Top->issue(First, 0).has_value(),
+                 "target dynamic hazard must accept the first top-down issue");
+  auto TopCycle = Top ? Top->earliestIssueCycle(Second, 0)
+                      : rcc::Expected<std::uint64_t>(std::unexpected(
+                            rcc::Error(rcc::ErrorCode::InternalError, "no top-down recognizer")));
+  Context.expect(TopCycle.has_value() && *TopCycle == 1,
+                 "target dynamic hazard must advance the top-down cycle");
+
+  auto Bottom = rcc::ScheduleHazardRecognizer::create(*Model, rcc::ScheduleDirection::BottomUp);
+  Context.expect(Bottom.has_value() && Bottom->issue(First, 0).has_value(),
+                 "target dynamic hazard must accept the first bottom-up issue");
+  auto BottomCycle = Bottom ? Bottom->earliestIssueCycle(Second, 0)
+                            : rcc::Expected<std::uint64_t>(std::unexpected(rcc::Error(
+                                  rcc::ErrorCode::InternalError, "no bottom-up recognizer")));
+  Context.expect(BottomCycle.has_value() && *BottomCycle == 1,
+                 "target dynamic hazard must recede the bottom-up cycle");
+}
+
+void testTargetSchedulingHooks(TestContext &Context, const rcc::TargetDescription &Target) {
+  TestSchedulingHooks MutationHooks;
+  MutationHooks.AddMutation = true;
+  auto MutationModel = makeSchedulingModel(&MutationHooks);
+  auto Fixture = makeFixture(Context, "schedule_mutation", 4);
+  if (!MutationModel || !Fixture.Function || Fixture.Block == nullptr) {
+    Context.expect(false, "target schedule mutation fixture must be created");
+    return;
+  }
+  rcc::MachineIRBuilder Builder(*Fixture.Function, Target);
+  Context.expect(Builder.setInsertPoint(*Fixture.Block).has_value(),
+                 "target schedule mutation insertion point must be established");
+  const rcc::Register X0 = physical(Context, rcc::riscv::PhysicalRegisterID::X0);
+  rcc::MachineInstr *First =
+      buildADDI(Context, Builder, makeGPR(Context, *Fixture.Function), X0, 1);
+  rcc::MachineInstr *Second =
+      buildADDI(Context, Builder, makeGPR(Context, *Fixture.Function), X0, 2);
+  std::array<rcc::MachineInstr *, 2> Instructions{First, Second};
+  auto DAG = rcc::ScheduleDAG::build(*Fixture.Block, Instructions, *Fixture.Function, Target,
+                                     *MutationModel, rcc::ScheduleDAGMode::PreRegisterAllocation);
+  Context.expect(DAG.has_value() &&
+                     hasDependency(DAG->units()[0], 1, rcc::ScheduleDependencyKind::Artificial),
+                 "target schedule mutation must add a checked artificial dependency");
+
+  TestSchedulingHooks PreferenceHooks;
+  PreferenceHooks.PreferSecondUnit = true;
+  auto PreferenceModel = makeSchedulingModel(&PreferenceHooks);
+  if (!PreferenceModel) {
+    Context.expect(false, "target scheduling preference model must be created");
+    return;
+  }
+  rcc::MachineAnalysisManager Analyses;
+  rcc::MachineSchedulerPass PreferencePass(
+      *PreferenceModel, {.MaximumRegionSize = 8, .EnableBidirectionalScheduling = false});
+  auto Preferred = PreferencePass.run(*Fixture.Function, Target, Analyses);
+  Context.expect(Preferred.has_value() && Preferred->Changed &&
+                     Fixture.Block->firstInstruction() == Second,
+                 "target candidate preference must affect the production scheduler");
+
+  auto BoundaryFixture = makeFixture(Context, "schedule_boundary", 5);
+  TestSchedulingHooks BoundaryHooks;
+  BoundaryHooks.MakeADDIBoundary = true;
+  auto BoundaryModel = makeSchedulingModel(&BoundaryHooks);
+  if (!BoundaryFixture.Function || BoundaryFixture.Block == nullptr || !BoundaryModel) {
+    Context.expect(false, "target schedule boundary fixture must be created");
+    return;
+  }
+  rcc::MachineIRBuilder BoundaryBuilder(*BoundaryFixture.Function, Target);
+  Context.expect(BoundaryBuilder.setInsertPoint(*BoundaryFixture.Block).has_value(),
+                 "target schedule boundary insertion point must be established");
+  rcc::MachineInstr *BoundaryFirst =
+      buildADDI(Context, BoundaryBuilder, makeGPR(Context, *BoundaryFixture.Function), X0, 1);
+  (void)buildADDI(Context, BoundaryBuilder, makeGPR(Context, *BoundaryFixture.Function), X0, 2);
+  rcc::MachineAnalysisManager BoundaryAnalyses;
+  rcc::MachineSchedulerPass BoundaryPass(
+      *BoundaryModel, {.MaximumRegionSize = 8, .EnableBidirectionalScheduling = false});
+  auto BoundaryResult = BoundaryPass.run(*BoundaryFixture.Function, Target, BoundaryAnalyses);
+  Context.expect(BoundaryResult.has_value() && !BoundaryResult->Changed &&
+                     BoundaryFixture.Block->firstInstruction() == BoundaryFirst,
+                 "target scheduling boundary must split production schedule regions");
+}
+
+void buildSchedulingChain(TestContext &Context, Fixture &Fixture,
+                          const rcc::TargetDescription &Target, bool PhysicalRegisters,
+                          rcc::MachineInstr *&Short, rcc::MachineInstr *&Long) {
+  rcc::MachineIRBuilder Builder(*Fixture.Function, Target);
+  Context.expect(Builder.setInsertPoint(*Fixture.Block).has_value(),
+                 "scheduler chain insertion point must be established");
+  const rcc::Register X0 = physical(Context, rcc::riscv::PhysicalRegisterID::X0);
+  const rcc::Register X10 = physical(Context, rcc::riscv::PhysicalRegisterID::X10);
+  const rcc::Register X11 = physical(Context, rcc::riscv::PhysicalRegisterID::X11);
+  const rcc::Register ShortValue = PhysicalRegisters
+                                       ? physical(Context, rcc::riscv::PhysicalRegisterID::X12)
+                                       : makeGPR(Context, *Fixture.Function);
+  const rcc::Register LongValue = PhysicalRegisters
+                                      ? physical(Context, rcc::riscv::PhysicalRegisterID::X13)
+                                      : makeGPR(Context, *Fixture.Function);
+  const rcc::Register LongResult = PhysicalRegisters
+                                       ? physical(Context, rcc::riscv::PhysicalRegisterID::X14)
+                                       : makeGPR(Context, *Fixture.Function);
+  const rcc::Register ShortResult = PhysicalRegisters
+                                        ? physical(Context, rcc::riscv::PhysicalRegisterID::X15)
+                                        : makeGPR(Context, *Fixture.Function);
+  Short = buildADDI(Context, Builder, ShortValue, X0, 1);
+  Long = buildBinary(Context, Builder, rcc::riscv::InstructionOpcode::DIV, LongValue, X10, X11);
+  (void)buildBinary(Context, Builder, rcc::riscv::InstructionOpcode::ADD, LongResult, LongValue,
+                    X10);
+  (void)buildBinary(Context, Builder, rcc::riscv::InstructionOpcode::ADD, ShortResult, ShortValue,
+                    X11);
+}
+
+void testPreRAScheduler(TestContext &Context, const rcc::TargetDescription &Target) {
+  auto Fixture = makeFixture(Context, "pre_ra_schedule", 2);
+  if (!Fixture.Function || Fixture.Block == nullptr)
+    return;
+  rcc::MachineInstr *Short = nullptr;
+  rcc::MachineInstr *Long = nullptr;
+  buildSchedulingChain(Context, Fixture, Target, false, Short, Long);
+  Context.expect(Fixture.Block->firstInstruction() == Short,
+                 "pre-RA fixture must begin in intentionally suboptimal order");
+  rcc::MachineAnalysisManager Analyses;
+  rcc::MachineSchedulerPass Pass(rcc::riscv::schedulingModel(),
+                                 {.MaximumRegionSize = 64, .EnableBidirectionalScheduling = false});
+  auto Result = Pass.run(*Fixture.Function, Target, Analyses);
+  if (!Result)
+    std::cerr << "pre-RA scheduler failure: " << Result.error().message() << '\n';
+  Context.expect(Result.has_value() && Result->Changed,
+                 "pre-RA scheduler must reorder the latency-critical chain");
+  Context.expect(Fixture.Block->firstInstruction() == Long,
+                 "pre-RA scheduler must prioritize the long critical path");
+}
+
+void testPostRASchedulerAndLivenessRepair(TestContext &Context,
+                                          const rcc::TargetDescription &Target) {
+  auto Fixture = makeFixture(Context, "post_ra_schedule", 3);
+  if (!Fixture.Function || Fixture.Block == nullptr)
+    return;
+  Fixture.Function->properties().set(rcc::MachineFunctionProperty::NoVRegs);
+  Fixture.Function->properties().set(rcc::MachineFunctionProperty::TracksLiveness);
+  rcc::MachineInstr *Short = nullptr;
+  rcc::MachineInstr *Long = nullptr;
+  buildSchedulingChain(Context, Fixture, Target, true, Short, Long);
+  auto Rebuilt = rcc::rebuildMachineLiveness(*Fixture.Function, Target);
+  Context.expect(Rebuilt.has_value(), "post-RA fixture liveness rebuild must succeed");
+  if (!Rebuilt)
+    return;
+
+  rcc::MachineAnalysisManager Analyses;
+  rcc::PostRASchedulerPass Pass(rcc::riscv::schedulingModel(),
+                                {.MaximumRegionSize = 64, .EnableBidirectionalScheduling = false});
+  auto Result = Pass.run(*Fixture.Function, Target, Analyses);
+  if (!Result)
+    std::cerr << "post-RA scheduler failure: " << Result.error().message() << '\n';
+  Context.expect(Result.has_value() && Result->Changed,
+                 "post-RA scheduler must reorder the latency-critical chain");
+  Context.expect(Fixture.Block->firstInstruction() == Long,
+                 "post-RA scheduler must prioritize the long critical path");
+  auto Verified = rcc::verifyTrackedMachineLiveness(*Fixture.Function, Target);
+  if (!Verified)
+    std::cerr << "post-RA liveness verification failure: " << Verified.error().message() << '\n';
+  Context.expect(Verified.has_value(),
+                 "post-RA scheduler must locally repair exact kill/dead state");
+}
+
+} // namespace
+
+int main() {
+  TestContext Context;
+  auto Target = rcc::riscv::createTargetDescription();
+  Context.expect(Target.has_value(), "scheduler target creation must succeed");
+  if (!Target)
+    return Context.result();
+  testDAGRegisterDependencies(Context, *Target);
+  testHazardScoreboard(Context);
+  testOperandLatencyAndModelValidation(Context);
+  testDynamicTargetHazards(Context);
+  testTargetSchedulingHooks(Context, *Target);
+  testPreRAScheduler(Context, *Target);
+  testPostRASchedulerAndLivenessRepair(Context, *Target);
+  return Context.result();
+}