From cd30fb546e389d1fb78ce8e579b3dba3a8fdb52a Mon Sep 17 00:00:00 2001
From: Richard-Qin-X <richard.qin.001@gmail.com>
Date: Thu, 13 Aug 2026 21:11:10 +0800
Subject: [CodeGen] Match LLVM machine copy propagation

---
 backend/include/rcc/CodeGen/MachineCopyPropagation.h     | 14 ++++----------
 backend/include/rcc/CodeGen/MachineOperand.h             |  2 ++
 .../include/rcc/CodeGen/MachineOptimizationPipeline.h    |  7 ++++++-
 backend/include/rcc/CodeGen/TargetInstrInfo.h            | 16 ++++++++++++++++
 backend/include/rcc/Target/RISCV/RISCVPipeline.h         | 10 ++++++++--
 5 files changed, 36 insertions(+), 13 deletions(-)

(limited to 'backend/include')

diff --git a/backend/include/rcc/CodeGen/MachineCopyPropagation.h b/backend/include/rcc/CodeGen/MachineCopyPropagation.h
index ab8b23f..59a3a77 100644
--- a/backend/include/rcc/CodeGen/MachineCopyPropagation.h
+++ b/backend/include/rcc/CodeGen/MachineCopyPropagation.h
@@ -6,26 +6,21 @@
 #include "rcc/CodeGen/MachinePassManager.h"
 
 #include <cstddef>
-#include <cstdint>
 
 namespace rcc {
 
 class TargetInstrInfo;
 
-enum class MachineCopyPropagationStage : std::uint8_t {
-  PreRegisterAllocation,
-  PostRegisterAllocation,
-};
-
 struct MachineCopyPropagationOptions final {
   std::size_t MaximumPropagatedCopies = 10'000;
+  bool UseTargetCopyInstructions = false;
 };
 
 class MachineCopyPropagationPass final : public MachineFunctionPass {
 public:
-  MachineCopyPropagationPass(const TargetInstrInfo &Info, MachineCopyPropagationStage Stage,
-                             MachineCopyPropagationOptions Options = {}) noexcept
-      : Info(&Info), Stage(Stage), Options(Options) {}
+  explicit MachineCopyPropagationPass(const TargetInstrInfo &Info,
+                                      MachineCopyPropagationOptions Options = {}) noexcept
+      : Info(&Info), Options(Options) {}
 
   [[nodiscard]] const MachinePassContract &contract() const noexcept override;
   [[nodiscard]] Expected<MachinePassResult> run(MachineFunction &Function,
@@ -38,7 +33,6 @@ private:
                                                               MachineActionReplay &Actions) const;
 
   const TargetInstrInfo *Info;
-  MachineCopyPropagationStage Stage;
   MachineCopyPropagationOptions Options;
 };
 
diff --git a/backend/include/rcc/CodeGen/MachineOperand.h b/backend/include/rcc/CodeGen/MachineOperand.h
index ef14638..db04795 100644
--- a/backend/include/rcc/CodeGen/MachineOperand.h
+++ b/backend/include/rcc/CodeGen/MachineOperand.h
@@ -382,6 +382,8 @@ public:
   [[nodiscard]] bool isImplicit() const noexcept;
 
   [[nodiscard]] Expected<void> setRegister(Register Reg);
+  [[nodiscard]] Expected<void> changeToImmediate(std::int64_t Value);
+  [[nodiscard]] Expected<void> setImmediate(std::int64_t Value);
   [[nodiscard]] Expected<void> setRegisterFlags(RegisterOperandFlags Flags);
   [[nodiscard]] Expected<void> setSubReg(SubRegIndex SubReg);
   [[nodiscard]] Expected<void> setBasicBlock(MachineBasicBlock &Block);
diff --git a/backend/include/rcc/CodeGen/MachineOptimizationPipeline.h b/backend/include/rcc/CodeGen/MachineOptimizationPipeline.h
index 51b4ed2..911cb86 100644
--- a/backend/include/rcc/CodeGen/MachineOptimizationPipeline.h
+++ b/backend/include/rcc/CodeGen/MachineOptimizationPipeline.h
@@ -23,6 +23,10 @@ struct MachineOptimizationPipelineTargetInfo final {
   const TargetSchedulingModel &SchedulingModel;
 };
 
+struct MachineOptimizationPipelineOptions final {
+  bool UseTargetCopyInstructions = false;
+};
+
 [[nodiscard]] Expected<void>
 registerMachineOptimizationAnalyses(MachineFunctionAnalysisManager &Analyses);
 
@@ -35,7 +39,8 @@ addSelectedSSAOptimizationPipeline(MachineFunctionPassManager &Pipeline,
 
 [[nodiscard]] Expected<void>
 addPostRegisterAllocationPipeline(MachineFunctionPassManager &Pipeline,
-                                  const MachineOptimizationPipelineTargetInfo &TargetInfo);
+                                  const MachineOptimizationPipelineTargetInfo &TargetInfo,
+                                  MachineOptimizationPipelineOptions Options = {});
 
 } // namespace rcc
 
diff --git a/backend/include/rcc/CodeGen/TargetInstrInfo.h b/backend/include/rcc/CodeGen/TargetInstrInfo.h
index 34752c5..8457ede 100644
--- a/backend/include/rcc/CodeGen/TargetInstrInfo.h
+++ b/backend/include/rcc/CodeGen/TargetInstrInfo.h
@@ -16,8 +16,14 @@ namespace rcc {
 class MachineBasicBlock;
 class MachineFunction;
 class MachineInstr;
+class MachineOperand;
 class TargetDescription;
 
+struct MachineCopyOperands final {
+  MachineOperand *Destination = nullptr;
+  MachineOperand *Source = nullptr;
+};
+
 struct MachineBranchAnalysis final {
   MachineInstr *Conditional = nullptr;
   MachineInstr *Unconditional = nullptr;
@@ -57,6 +63,16 @@ public:
                                                     const MachineFunction &Function,
                                                     const TargetDescription &Target) const = 0;
 
+  [[nodiscard]] virtual std::optional<MachineCopyOperands>
+  getCopyOperands(MachineInstr &) const noexcept {
+    return std::nullopt;
+  }
+
+  [[nodiscard]] virtual Expected<bool> simplifyInstruction(MachineInstr &, MachineFunction &,
+                                                           const TargetDescription &) const {
+    return false;
+  }
+
   [[nodiscard]] virtual Expected<bool> tryConvertToThreeAddress(MachineInstr &, std::size_t,
                                                                 std::size_t, MachineFunction &,
                                                                 const TargetDescription &) const {
diff --git a/backend/include/rcc/Target/RISCV/RISCVPipeline.h b/backend/include/rcc/Target/RISCV/RISCVPipeline.h
index 8b27032..267c497 100644
--- a/backend/include/rcc/Target/RISCV/RISCVPipeline.h
+++ b/backend/include/rcc/Target/RISCV/RISCVPipeline.h
@@ -19,11 +19,17 @@ class TargetDescription;
 
 namespace riscv {
 
+struct RISCVPipelineOptions final {
+  bool UseTargetCopyInstructions = false;
+};
+
 [[nodiscard]] Expected<void> addCanonicalPipeline(MachineFunctionPassManager &Pipeline,
                                                   const MachineFunction &Function,
-                                                  const RISCVSubtarget &Subtarget);
+                                                  const RISCVSubtarget &Subtarget,
+                                                  RISCVPipelineOptions Options = {});
 [[nodiscard]] Expected<std::unique_ptr<MachineFunctionPass>>
-createCanonicalPipelinePass(std::string_view Name, const RISCVSubtarget &Subtarget);
+createCanonicalPipelinePass(std::string_view Name, const RISCVSubtarget &Subtarget,
+                            RISCVPipelineOptions Options = {});
 [[nodiscard]] Expected<std::vector<std::string>>
 canonicalPipelinePassNames(const MachineFunction &Function, const RISCVSubtarget &Subtarget);
 } // namespace riscv
-- 
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