From e5fdceb9b869f010a2a75638fd38aaf1867f3008 Mon Sep 17 00:00:00 2001
From: Richard-Qin-X <richard.qin.001@gmail.com>
Date: Sun, 9 Aug 2026 04:40:17 +0800
Subject: [CodeGen] Complete register allocation infrastructure

---
 backend/include/rcc/CodeGen/LiveRegMatrix.h | 73 +++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)
 create mode 100644 backend/include/rcc/CodeGen/LiveRegMatrix.h

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

diff --git a/backend/include/rcc/CodeGen/LiveRegMatrix.h b/backend/include/rcc/CodeGen/LiveRegMatrix.h
new file mode 100644
index 0000000..953828c
--- /dev/null
+++ b/backend/include/rcc/CodeGen/LiveRegMatrix.h
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef RCC_CODEGEN_LIVEREGMATRIX_H
+#define RCC_CODEGEN_LIVEREGMATRIX_H
+
+#include "rcc/CodeGen/MachineLiveness.h"
+#include "rcc/CodeGen/TargetRegisterInfo.h"
+
+#include <cstdint>
+#include <optional>
+#include <span>
+#include <unordered_map>
+#include <utility>
+#include <vector>
+
+namespace rcc {
+
+class MachineFunction;
+class TargetDescription;
+
+enum class RegisterInterferenceKind : std::uint8_t {
+  Free,
+  VirtualRegister,
+  FixedRegister,
+  RegisterMask,
+  RegisterUnit,
+};
+
+struct RegisterInterference final {
+  RegisterInterferenceKind Kind = RegisterInterferenceKind::Free;
+  std::optional<Register> VirtualReg;
+  std::optional<PhysicalRegister> FixedReg;
+  std::optional<RegisterUnitID> Unit;
+  std::optional<MachineInstrStableID> Instruction;
+};
+
+class LiveRegMatrix final {
+public:
+  LiveRegMatrix(const MachineFunction &Function, const TargetDescription &Target,
+                const LiveIntervalsAnalysis::Result &Intervals) noexcept
+      : Function(&Function), Target(&Target), Intervals(&Intervals) {}
+
+  [[nodiscard]] Expected<void> assign(Register VirtualReg, PhysicalRegister PhysicalReg);
+  [[nodiscard]] Expected<void> unassign(Register VirtualReg);
+  [[nodiscard]] std::optional<PhysicalRegister> assignment(Register VirtualReg) const noexcept;
+  [[nodiscard]] RegisterInterference checkInterference(Register VirtualReg,
+                                                       PhysicalRegister PhysicalReg) const noexcept;
+  [[nodiscard]] std::vector<RegisterInterference>
+  collectInterferences(Register VirtualReg, PhysicalRegister PhysicalReg) const;
+
+  [[nodiscard]] std::span<const std::pair<Register, PhysicalRegister>>
+  assignments() const noexcept {
+    return OrderedAssignments;
+  }
+
+private:
+  [[nodiscard]] bool intervalsOverlapOnCandidates(const LiveInterval &Left,
+                                                  PhysicalRegister LeftReg,
+                                                  const LiveInterval &Right,
+                                                  PhysicalRegister RightReg) const noexcept;
+  [[nodiscard]] bool intervalOverlapsUnit(const LiveInterval &Interval, RegisterUnitLane Unit,
+                                          const LiveRange &UnitRange) const noexcept;
+
+  const MachineFunction *Function;
+  const TargetDescription *Target;
+  const LiveIntervalsAnalysis::Result *Intervals;
+  std::unordered_map<Register, PhysicalRegister> Assignments;
+  std::vector<std::pair<Register, PhysicalRegister>> OrderedAssignments;
+};
+
+} // namespace rcc
+
+#endif // RCC_CODEGEN_LIVEREGMATRIX_H
-- 
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