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/LiveInterval.h | 144 +++++++++++++++++++++++++++++
 1 file changed, 144 insertions(+)
 create mode 100644 backend/include/rcc/CodeGen/LiveInterval.h

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

diff --git a/backend/include/rcc/CodeGen/LiveInterval.h b/backend/include/rcc/CodeGen/LiveInterval.h
new file mode 100644
index 0000000..28791f1
--- /dev/null
+++ b/backend/include/rcc/CodeGen/LiveInterval.h
@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef RCC_CODEGEN_LIVEINTERVAL_H
+#define RCC_CODEGEN_LIVEINTERVAL_H
+
+#include "rcc/CodeGen/MachineIRTypes.h"
+#include "rcc/CodeGen/Register.h"
+#include "rcc/CodeGen/SlotIndexes.h"
+#include "rcc/CodeGen/StableID.h"
+#include "rcc/Support/Error.h"
+
+#include <compare>
+#include <cstdint>
+#include <limits>
+#include <optional>
+#include <span>
+#include <vector>
+
+namespace rcc {
+
+class LiveValueNumberID final {
+public:
+  constexpr LiveValueNumberID() noexcept = default;
+
+  [[nodiscard]] static constexpr LiveValueNumberID fromValue(std::uint32_t Value) noexcept {
+    return LiveValueNumberID(Value);
+  }
+
+  [[nodiscard]] constexpr bool isValid() const noexcept {
+    return Value != 0;
+  }
+
+  [[nodiscard]] constexpr std::uint32_t value() const noexcept {
+    return Value;
+  }
+
+  friend constexpr bool operator==(LiveValueNumberID, LiveValueNumberID) noexcept = default;
+  friend constexpr auto operator<=>(LiveValueNumberID, LiveValueNumberID) noexcept = default;
+
+private:
+  explicit constexpr LiveValueNumberID(std::uint32_t Value) noexcept : Value(Value) {}
+
+  std::uint32_t Value = 0;
+};
+
+enum class LiveValueState : std::uint8_t {
+  Normal,
+  Phi,
+  Unused,
+  Redefined,
+};
+
+struct LiveValueNumber final {
+  LiveValueNumberID ID;
+  SlotIndex Definition;
+  LiveValueState State = LiveValueState::Normal;
+  std::optional<MachineInstrStableID> Origin;
+
+  friend bool operator==(const LiveValueNumber &, const LiveValueNumber &) = default;
+};
+
+struct LiveSegment final {
+  SlotIndex Start;
+  SlotIndex End;
+  LiveValueNumberID Value;
+
+  [[nodiscard]] constexpr bool empty() const noexcept {
+    return !(Start < End);
+  }
+
+  [[nodiscard]] constexpr bool contains(SlotIndex Position) const noexcept {
+    return !(Position < Start) && Position < End;
+  }
+
+  [[nodiscard]] constexpr bool overlaps(const LiveSegment &Other) const noexcept {
+    return Start < Other.End && Other.Start < End;
+  }
+
+  friend constexpr bool operator==(const LiveSegment &, const LiveSegment &) noexcept = default;
+};
+
+class LiveRange final {
+public:
+  [[nodiscard]] std::span<const LiveSegment> segments() const noexcept {
+    return Segments;
+  }
+  [[nodiscard]] std::span<const LiveValueNumber> values() const noexcept {
+    return Values;
+  }
+  [[nodiscard]] bool empty() const noexcept {
+    return Segments.empty();
+  }
+
+  [[nodiscard]] const LiveSegment *segmentAt(SlotIndex Position) const noexcept;
+  [[nodiscard]] const LiveValueNumber *value(LiveValueNumberID ID) const noexcept;
+  [[nodiscard]] const LiveValueNumber *valueAt(SlotIndex Position) const noexcept;
+  [[nodiscard]] bool liveAt(SlotIndex Position) const noexcept;
+  [[nodiscard]] bool overlaps(const LiveRange &Other) const noexcept;
+
+  [[nodiscard]] Expected<LiveValueNumberID>
+  createValue(SlotIndex Definition, LiveValueState State = LiveValueState::Normal,
+              std::optional<MachineInstrStableID> Origin = std::nullopt);
+  [[nodiscard]] Expected<void> addSegment(LiveSegment Segment);
+  [[nodiscard]] Expected<void> extend(LiveValueNumberID Value, SlotIndex Start, SlotIndex End);
+  [[nodiscard]] Expected<void> remove(SlotIndex Start, SlotIndex End);
+  [[nodiscard]] Expected<void> shrinkToUses(std::span<const SlotIndex> Uses);
+  [[nodiscard]] Expected<void> verify() const;
+
+private:
+  void mergeAdjacent();
+
+  std::vector<LiveSegment> Segments;
+  std::vector<LiveValueNumber> Values;
+};
+
+struct LiveSubRange final {
+  LaneMask Lanes;
+  LiveRange Range;
+};
+
+struct LiveInterval final {
+  Register Reg;
+  LiveRange MainRange;
+  std::vector<LiveSubRange> SubRanges;
+  std::uint64_t SpillWeight = 0;
+  bool Spillable = true;
+  std::vector<PhysicalRegister> AllocationHints;
+  std::optional<Register> SplitParent;
+  std::optional<Register> Origin;
+
+  [[nodiscard]] bool overlaps(const LiveInterval &Other) const noexcept {
+    return MainRange.overlaps(Other.MainRange);
+  }
+};
+
+} // namespace rcc
+
+template <> struct std::hash<rcc::LiveValueNumberID> {
+  [[nodiscard]] std::size_t operator()(rcc::LiveValueNumberID ID) const noexcept {
+    return std::hash<std::uint32_t>{}(ID.value());
+  }
+};
+
+#endif // RCC_CODEGEN_LIVEINTERVAL_H
-- 
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