182 lines
9.3 KiB
C++
182 lines
9.3 KiB
C++
#include "PrologueEpilogueInsertion.h"
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#include "RISCv64LLIR.h" // 假设包含了 PhysicalReg, RVOpcodes 等定义
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#include "RISCv64ISel.h"
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#include <algorithm>
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#include <vector>
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#include <set>
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namespace sysy {
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char PrologueEpilogueInsertionPass::ID = 0;
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void PrologueEpilogueInsertionPass::runOnMachineFunction(MachineFunction* mfunc) {
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StackFrameInfo& frame_info = mfunc->getFrameInfo();
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Function* F = mfunc->getFunc();
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RISCv64ISel* isel = mfunc->getISel();
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// 1. 清理 KEEPALIVE 伪指令
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for (auto& mbb : mfunc->getBlocks()) {
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auto& instrs = mbb->getInstructions();
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instrs.erase(
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std::remove_if(instrs.begin(), instrs.end(),
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[](const std::unique_ptr<MachineInstr>& instr) {
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return instr->getOpcode() == RVOpcodes::PSEUDO_KEEPALIVE;
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}
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),
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instrs.end()
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);
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}
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// 2. 确定需要保存的被调用者保存寄存器 (callee-saved)
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auto& vreg_to_preg_map = frame_info.vreg_to_preg_map;
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std::set<PhysicalReg> used_callee_saved_regs_set;
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const auto& callee_saved_int = getCalleeSavedIntRegs();
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const auto& callee_saved_fp = getCalleeSavedFpRegs();
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for (const auto& pair : vreg_to_preg_map) {
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PhysicalReg preg = pair.second;
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bool is_int_cs = std::find(callee_saved_int.begin(), callee_saved_int.end(), preg) != callee_saved_int.end();
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bool is_fp_cs = std::find(callee_saved_fp.begin(), callee_saved_fp.end(), preg) != callee_saved_fp.end();
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if ((is_int_cs && preg != PhysicalReg::S0) || is_fp_cs) {
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used_callee_saved_regs_set.insert(preg);
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}
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}
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frame_info.callee_saved_regs_to_store.assign(
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used_callee_saved_regs_set.begin(), used_callee_saved_regs_set.end()
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);
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std::sort(frame_info.callee_saved_regs_to_store.begin(), frame_info.callee_saved_regs_to_store.end());
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frame_info.callee_saved_size = frame_info.callee_saved_regs_to_store.size() * 8;
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// 3. 计算最终的栈帧总大小，包含栈溢出保护
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int total_stack_size = frame_info.locals_size +
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frame_info.spill_size +
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frame_info.callee_saved_size +
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16;
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// 栈溢出保护：增加最大栈帧大小以容纳大型数组
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const int MAX_STACK_FRAME_SIZE = 8192; // 8KB to handle large arrays like 256*4*2 = 2048 bytes
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if (total_stack_size > MAX_STACK_FRAME_SIZE) {
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// 如果仍然超过限制，尝试优化对齐方式
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std::cerr << "Warning: Stack frame size " << total_stack_size
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<< " exceeds recommended limit " << MAX_STACK_FRAME_SIZE << " for function "
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<< mfunc->getName() << std::endl;
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}
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// 优化：减少对齐开销，使用16字节对齐而非更大的对齐
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int aligned_stack_size = (total_stack_size + 15) & ~15;
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frame_info.total_size = aligned_stack_size;
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if (aligned_stack_size > 0) {
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// --- 4. 插入完整的序言 ---
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MachineBasicBlock* entry_block = mfunc->getBlocks().front().get();
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auto& entry_instrs = entry_block->getInstructions();
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std::vector<std::unique_ptr<MachineInstr>> prologue_instrs;
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// 4.1. 分配栈帧
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auto alloc_stack = std::make_unique<MachineInstr>(RVOpcodes::ADDI);
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alloc_stack->addOperand(std::make_unique<RegOperand>(PhysicalReg::SP));
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alloc_stack->addOperand(std::make_unique<RegOperand>(PhysicalReg::SP));
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alloc_stack->addOperand(std::make_unique<ImmOperand>(-aligned_stack_size));
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prologue_instrs.push_back(std::move(alloc_stack));
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// 4.2. 保存 ra 和 s0
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auto save_ra = std::make_unique<MachineInstr>(RVOpcodes::SD);
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save_ra->addOperand(std::make_unique<RegOperand>(PhysicalReg::RA));
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save_ra->addOperand(std::make_unique<MemOperand>(
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std::make_unique<RegOperand>(PhysicalReg::SP),
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std::make_unique<ImmOperand>(aligned_stack_size - 8)
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));
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prologue_instrs.push_back(std::move(save_ra));
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auto save_fp = std::make_unique<MachineInstr>(RVOpcodes::SD);
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save_fp->addOperand(std::make_unique<RegOperand>(PhysicalReg::S0));
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save_fp->addOperand(std::make_unique<MemOperand>(
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std::make_unique<RegOperand>(PhysicalReg::SP),
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std::make_unique<ImmOperand>(aligned_stack_size - 16)
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));
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prologue_instrs.push_back(std::move(save_fp));
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// 4.3. 设置新的帧指针 s0
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auto set_fp = std::make_unique<MachineInstr>(RVOpcodes::ADDI);
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set_fp->addOperand(std::make_unique<RegOperand>(PhysicalReg::S0));
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set_fp->addOperand(std::make_unique<RegOperand>(PhysicalReg::SP));
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set_fp->addOperand(std::make_unique<ImmOperand>(aligned_stack_size));
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prologue_instrs.push_back(std::move(set_fp));
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// 4.4. 保存所有使用到的被调用者保存寄存器
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int next_available_offset = -(16 + frame_info.locals_size + frame_info.spill_size);
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for (const auto& reg : frame_info.callee_saved_regs_to_store) {
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// 改为“先更新，后使用”逻辑
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next_available_offset -= 8; // 先为当前寄存器分配下一个可用槽位
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RVOpcodes store_op = isFPR(reg) ? RVOpcodes::FSD : RVOpcodes::SD;
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auto save_cs_reg = std::make_unique<MachineInstr>(store_op);
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save_cs_reg->addOperand(std::make_unique<RegOperand>(reg));
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save_cs_reg->addOperand(std::make_unique<MemOperand>(
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std::make_unique<RegOperand>(PhysicalReg::S0),
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std::make_unique<ImmOperand>(next_available_offset) // 使用新计算出的正确偏移
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));
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prologue_instrs.push_back(std::move(save_cs_reg));
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// 不再需要在循环末尾递减
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}
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// 4.5. 将所有生成的序言指令一次性插入到函数入口
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entry_instrs.insert(entry_instrs.begin(),
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std::make_move_iterator(prologue_instrs.begin()),
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std::make_move_iterator(prologue_instrs.end()));
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// --- 5. 插入完整的尾声 ---
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for (auto& mbb : mfunc->getBlocks()) {
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for (auto it = mbb->getInstructions().begin(); it != mbb->getInstructions().end(); ++it) {
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if ((*it)->getOpcode() == RVOpcodes::RET) {
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std::vector<std::unique_ptr<MachineInstr>> epilogue_instrs;
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// 5.1. 恢复被调用者保存寄存器
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int next_available_offset_restore = -(16 + frame_info.locals_size + frame_info.spill_size);
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for (const auto& reg : frame_info.callee_saved_regs_to_store) {
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next_available_offset_restore -= 8; // 为下一个寄存器准备偏移
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RVOpcodes load_op = isFPR(reg) ? RVOpcodes::FLD : RVOpcodes::LD;
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auto restore_cs_reg = std::make_unique<MachineInstr>(load_op);
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restore_cs_reg->addOperand(std::make_unique<RegOperand>(reg));
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restore_cs_reg->addOperand(std::make_unique<MemOperand>(
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std::make_unique<RegOperand>(PhysicalReg::S0),
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std::make_unique<ImmOperand>(next_available_offset_restore) // 使用当前偏移
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));
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epilogue_instrs.push_back(std::move(restore_cs_reg));
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}
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// 5.2. 恢复 ra 和 s0
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auto restore_ra = std::make_unique<MachineInstr>(RVOpcodes::LD);
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restore_ra->addOperand(std::make_unique<RegOperand>(PhysicalReg::RA));
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restore_ra->addOperand(std::make_unique<MemOperand>(
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std::make_unique<RegOperand>(PhysicalReg::SP),
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std::make_unique<ImmOperand>(aligned_stack_size - 8)
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));
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epilogue_instrs.push_back(std::move(restore_ra));
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auto restore_fp = std::make_unique<MachineInstr>(RVOpcodes::LD);
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restore_fp->addOperand(std::make_unique<RegOperand>(PhysicalReg::S0));
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restore_fp->addOperand(std::make_unique<MemOperand>(
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std::make_unique<RegOperand>(PhysicalReg::SP),
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std::make_unique<ImmOperand>(aligned_stack_size - 16)
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));
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epilogue_instrs.push_back(std::move(restore_fp));
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// 5.3. 释放栈帧
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auto dealloc_stack = std::make_unique<MachineInstr>(RVOpcodes::ADDI);
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dealloc_stack->addOperand(std::make_unique<RegOperand>(PhysicalReg::SP));
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dealloc_stack->addOperand(std::make_unique<RegOperand>(PhysicalReg::SP));
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dealloc_stack->addOperand(std::make_unique<ImmOperand>(aligned_stack_size));
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epilogue_instrs.push_back(std::move(dealloc_stack));
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// 将尾声指令插入到 RET 指令之前
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mbb->getInstructions().insert(it,
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std::make_move_iterator(epilogue_instrs.begin()),
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std::make_move_iterator(epilogue_instrs.end()));
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goto next_block;
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}
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}
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next_block:;
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}
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}
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}
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} // namespace sysy
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