From a2f8d7c5e22b510965327383410bd576f7cf28e7 Mon Sep 17 00:00:00 2001
From: Richard-Qin-X <richard.qin.001@gmail.com>
Date: Thu, 13 Aug 2026 04:17:52 +0800
Subject: [CodeGen] Split machine liveness components

---
 backend/include/rcc/CodeGen/SlotIndexes.h | 130 ++++++++++++++++++++++++++++++
 1 file changed, 130 insertions(+)
 create mode 100644 backend/include/rcc/CodeGen/SlotIndexes.h

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

diff --git a/backend/include/rcc/CodeGen/SlotIndexes.h b/backend/include/rcc/CodeGen/SlotIndexes.h
new file mode 100644
index 0000000..1767596
--- /dev/null
+++ b/backend/include/rcc/CodeGen/SlotIndexes.h
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef RCC_CODEGEN_SLOTINDEXES_H
+#define RCC_CODEGEN_SLOTINDEXES_H
+
+#include "rcc/CodeGen/MachineIRTypes.h"
+#include "rcc/CodeGen/MachinePass.h"
+#include "rcc/CodeGen/StableID.h"
+#include "rcc/Support/Error.h"
+
+#include <compare>
+#include <cstddef>
+#include <cstdint>
+#include <string_view>
+#include <unordered_map>
+#include <vector>
+
+namespace rcc {
+
+class MachineBasicBlock;
+class MachineFunction;
+class MachineInstr;
+class TargetDescription;
+
+enum class SlotIndexKind : std::uint8_t {
+  Block,
+  EarlyClobber,
+  Register,
+  Dead,
+};
+
+class SlotIndex final {
+public:
+  constexpr SlotIndex() noexcept = default;
+
+  [[nodiscard]] static constexpr SlotIndex fromValue(std::uint64_t Value) noexcept {
+    return SlotIndex(Value);
+  }
+
+  [[nodiscard]] constexpr bool isValid() const noexcept {
+    return Value != 0;
+  }
+
+  [[nodiscard]] constexpr std::uint64_t value() const noexcept {
+    return Value;
+  }
+
+  [[nodiscard]] constexpr SlotIndexKind kind() const noexcept {
+    return static_cast<SlotIndexKind>(Value & KindMask);
+  }
+
+  [[nodiscard]] constexpr SlotIndex baseIndex() const noexcept {
+    return SlotIndex(Value & ~KindMask);
+  }
+
+  [[nodiscard]] constexpr SlotIndex withKind(SlotIndexKind Kind) const noexcept {
+    return isValid() ? SlotIndex((Value & ~KindMask) | static_cast<std::uint64_t>(Kind))
+                     : SlotIndex{};
+  }
+
+  [[nodiscard]] constexpr SlotIndex earlyClobberSlot() const noexcept {
+    return withKind(SlotIndexKind::EarlyClobber);
+  }
+
+  [[nodiscard]] constexpr SlotIndex registerSlot() const noexcept {
+    return withKind(SlotIndexKind::Register);
+  }
+
+  [[nodiscard]] constexpr SlotIndex deadSlot() const noexcept {
+    return withKind(SlotIndexKind::Dead);
+  }
+
+  friend constexpr bool operator==(SlotIndex, SlotIndex) noexcept = default;
+  friend constexpr auto operator<=>(SlotIndex, SlotIndex) noexcept = default;
+
+private:
+  static constexpr std::uint64_t KindMask = 3;
+
+  explicit constexpr SlotIndex(std::uint64_t Value) noexcept : Value(Value) {}
+
+  std::uint64_t Value = 0;
+};
+
+class SlotIndexesAnalysis final {
+public:
+  class Result final {
+  public:
+    [[nodiscard]] SlotIndex instructionIndex(const MachineInstr &Instruction) const noexcept;
+    [[nodiscard]] SlotIndex slot(const MachineInstr &Instruction) const noexcept {
+      return instructionIndex(Instruction);
+    }
+    [[nodiscard]] SlotIndex blockStart(const MachineBasicBlock &Block) const noexcept;
+    [[nodiscard]] SlotIndex blockEnd(const MachineBasicBlock &Block) const noexcept;
+    [[nodiscard]] const MachineInstr *instructionFromIndex(SlotIndex Index) const noexcept;
+    [[nodiscard]] const MachineBasicBlock *blockFromIndex(SlotIndex Index) const noexcept;
+
+    [[nodiscard]] Expected<void> insertInstruction(const MachineInstr &Instruction);
+    [[nodiscard]] Expected<void> eraseInstruction(const MachineInstr &Instruction);
+    [[nodiscard]] Expected<void> renumber(MachineFunction &Function);
+
+    [[nodiscard]] bool invalidate(const MachineFunction &,
+                                  const PreservedAnalyses &Preserved) const noexcept;
+
+  private:
+    std::unordered_map<MachineInstrStableID, SlotIndex> InstructionSlots;
+    std::unordered_map<std::uint64_t, const MachineInstr *> SlotToInstruction;
+    std::unordered_map<const MachineBasicBlock *, SlotIndex> BlockStarts;
+    std::unordered_map<const MachineBasicBlock *, SlotIndex> BlockEnds;
+    std::vector<const MachineBasicBlock *> BlocksByStart;
+
+    friend class SlotIndexesAnalysis;
+  };
+
+  [[nodiscard]] static constexpr std::string_view name() noexcept {
+    return "SlotIndexes";
+  }
+
+  [[nodiscard]] static Expected<Result>
+  run(MachineFunction &Function, const TargetDescription &Target, MachineAnalysisManager &Analyses);
+};
+
+} // namespace rcc
+
+template <> struct std::hash<rcc::SlotIndex> {
+  [[nodiscard]] std::size_t operator()(rcc::SlotIndex Index) const noexcept {
+    return std::hash<std::uint64_t>{}(Index.value());
+  }
+};
+
+#endif // RCC_CODEGEN_SLOTINDEXES_H
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