nudt-compiler-cpp/src/mir/FrameLowering.cpp

#include "mir/MIR.h"

#include <stdexcept>
#include <vector>

#include "utils/Log.h"

namespace mir {
namespace {

int AlignTo(int value, int align) {
  return ((value + align - 1) / align) * align;
}

}  // namespace

void RunFrameLowering(MachineFunction& function) {
  int cursor = 0;
  const auto& slots = function.GetFrameSlots();

  // 为每个栈槽分配偏移
  for (const auto& slot : slots) {
    int align = slot.size;
    cursor = AlignTo(cursor, align);
    function.GetFrameSlot(slot.index).offset = cursor;
    cursor += slot.size;
  }

  // 局部变量区按 16 字节对齐
  int local_vars_size = AlignTo(cursor, 16);
  function.SetLocalVarsSize(local_vars_size);

  // 总帧大小 = 局部变量区 + 16（保存 ra 和 s0）
  function.SetFrameSize(local_vars_size + 16);

  // 插入 Prologue/Epilogue 占位符（原逻辑）
  auto& insts = function.GetEntry()->GetInstructions();
  std::vector<MachineInstr> lowered;
  lowered.emplace_back(Opcode::Prologue);
  for (const auto& inst : insts) {
    if (inst.GetOpcode() == Opcode::Ret) {
      lowered.emplace_back(Opcode::Epilogue);
    }
    lowered.push_back(inst);
  }
  insts = std::move(lowered);
}

}  // namespace mir