From f6fdfb8d484b4e52cdb24a94a31b0f00d41a5eb7 Mon Sep 17 00:00:00 2001
From: Richard-Qin-X <richard.qin.001@gmail.com>
Date: Sat, 15 Aug 2026 00:38:20 +0800
Subject: [GlobalISel] Match LLVM CSE builder result semantics

---
 backend/include/rcc/CodeGen/GlobalISel/CSEInfo.h | 114 +++++++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 backend/include/rcc/CodeGen/GlobalISel/CSEInfo.h

(limited to 'backend/include/rcc/CodeGen/GlobalISel/CSEInfo.h')

diff --git a/backend/include/rcc/CodeGen/GlobalISel/CSEInfo.h b/backend/include/rcc/CodeGen/GlobalISel/CSEInfo.h
new file mode 100644
index 0000000..27bc2a3
--- /dev/null
+++ b/backend/include/rcc/CodeGen/GlobalISel/CSEInfo.h
@@ -0,0 +1,114 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef RCC_CODEGEN_GLOBALISEL_CSEINFO_H
+#define RCC_CODEGEN_GLOBALISEL_CSEINFO_H
+
+#include "rcc/ADT/APInt.h"
+#include "rcc/CodeGen/CSEConfigBase.h"
+#include "rcc/CodeGen/CommandFlags.h"
+#include "rcc/CodeGen/GlobalISel/GISelChangeObserver.h"
+#include "rcc/CodeGen/GlobalISel/GISelWorkList.h"
+#include "rcc/CodeGen/LowLevelType.h"
+#include "rcc/CodeGen/MachineIRTypes.h"
+#include "rcc/CodeGen/Register.h"
+#include "rcc/Support/Error.h"
+
+#include <cstddef>
+#include <cstdint>
+#include <memory>
+#include <span>
+#include <unordered_map>
+#include <vector>
+
+namespace rcc {
+
+class MachineBasicBlock;
+class MachineFunction;
+class MachineInstr;
+class MachineIRBuilderResult;
+
+class CSEConfigFull final : public CSEConfigBase {
+public:
+  [[nodiscard]] bool shouldCSEOpcode(Opcode InstructionOpcode) const noexcept override;
+};
+
+class CSEConfigConstantOnly final : public CSEConfigBase {
+public:
+  [[nodiscard]] bool shouldCSEOpcode(Opcode InstructionOpcode) const noexcept override;
+};
+
+[[nodiscard]] std::unique_ptr<CSEConfigBase> getStandardCSEConfigForOpt(OptimizationLevel Level);
+
+class GISelCSEInfo final : public GISelChangeObserver {
+public:
+  GISelCSEInfo() = default;
+  GISelCSEInfo(const GISelCSEInfo &) = delete;
+  GISelCSEInfo &operator=(const GISelCSEInfo &) = delete;
+  ~GISelCSEInfo() override = default;
+
+  void setCSEConfig(std::unique_ptr<CSEConfigBase> Config) noexcept;
+  [[nodiscard]] bool shouldCSE(Opcode InstructionOpcode) const noexcept;
+  [[nodiscard]] Expected<void> analyze(MachineFunction &Function);
+  [[nodiscard]] Expected<void> verify();
+  void releaseMemory() noexcept;
+
+  void erasingInstr(MachineInstr &Instruction) override;
+  void createdInstr(MachineInstr &Instruction) override;
+  void changingInstr(MachineInstr &Instruction) override;
+  void changedInstr(MachineInstr &Instruction) override;
+
+private:
+  struct CSEKey final {
+    const MachineBasicBlock *Block = nullptr;
+    Opcode InstructionOpcode;
+    std::vector<std::uint64_t> Profile;
+
+    friend bool operator==(const CSEKey &, const CSEKey &) = default;
+  };
+
+  struct CSEKeyHash final {
+    [[nodiscard]] std::size_t operator()(const CSEKey &Key) const noexcept;
+  };
+
+  [[nodiscard]] Expected<void> appendRegisterProfile(std::vector<std::uint64_t> &Profile,
+                                                     Register Reg, bool IsDefinition) const;
+  [[nodiscard]] Expected<void> appendResultProfile(std::vector<std::uint64_t> &Profile,
+                                                   const MachineIRBuilderResult &Result) const;
+  [[nodiscard]] Expected<CSEKey> profileInstruction(const MachineInstr &Instruction) const;
+  [[nodiscard]] Expected<CSEKey> profileBuilderInstruction(
+      Opcode InstructionOpcode, std::span<const MachineIRBuilderResult> Destinations,
+      std::span<const Register> Sources, std::span<const std::int64_t> Immediates,
+      MachineInstrFlags Flags, const MachineBasicBlock &Block) const;
+  [[nodiscard]] Expected<CSEKey> profileConstant(const MachineIRBuilderResult &Destination,
+                                                 const APInt &Value,
+                                                 const MachineBasicBlock &Block) const;
+
+  void recordNewInstruction(MachineInstr &Instruction);
+  [[nodiscard]] Expected<void> handleRecordedInstruction(MachineInstr &Instruction);
+  [[nodiscard]] Expected<void> handleRecordedInstructions();
+  void handleRemoveInstruction(MachineInstr &Instruction) noexcept;
+  [[nodiscard]] Expected<void> insertInstruction(MachineInstr &Instruction);
+
+  [[nodiscard]] Expected<MachineInstr *> getMachineInstrIfExists(
+      Opcode InstructionOpcode, std::span<const MachineIRBuilderResult> Destinations,
+      std::span<const Register> Sources, std::span<const std::int64_t> Immediates,
+      MachineInstrFlags Flags, MachineBasicBlock &Block);
+  [[nodiscard]] Expected<MachineInstr *>
+  getConstantIfExists(const MachineIRBuilderResult &Destination, const APInt &Value,
+                      MachineBasicBlock &Block);
+  void countOpcodeHit(Opcode InstructionOpcode) noexcept;
+
+  MachineFunction *Function = nullptr;
+  std::unique_ptr<CSEConfigBase> Config;
+  std::unordered_map<CSEKey, MachineInstr *, CSEKeyHash> CSEMap;
+  std::unordered_map<const MachineInstr *, CSEKey> InstructionMapping;
+  GISelWorkList<8> TemporaryInstructions;
+  std::unordered_map<std::uint32_t, std::size_t> OpcodeHitTable;
+  bool HandlingRecordedInstructions = false;
+
+  friend class CSEMIRBuilder;
+};
+
+} // namespace rcc
+
+#endif // RCC_CODEGEN_GLOBALISEL_CSEINFO_H
-- 
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