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[CFG]CFG优化方法转换为静态方法，方便其他优化遍调用，TODO：简化条件分支

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This commit is contained in:
rain2133
2025-07-17 15:54:37 +08:00
parent f7e318e623
commit 009f54863e
2 changed files with 415 additions and 395 deletions
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776
src/SysYIRCFGOpt.cpp
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@@ -13,248 +13,374 @@ namespace sysy {
// 删除br后的无用指令 // 删除br后的无用指令
void SysYCFGOpt::SysYDelInstAfterBr() { bool SysYCFGOpt::SysYDelInstAfterBr(Function *func) {
auto &functions = pModule->getFunctions(); bool changed = false;
for (auto &function : functions) {
auto basicBlocks = function.second->getBasicBlocks(); auto basicBlocks = func->getBasicBlocks();
for (auto &basicBlock : basicBlocks) { for (auto &basicBlock : basicBlocks) {
bool Branch = false; bool Branch = false;
auto &instructions = basicBlock->getInstructions(); auto &instructions = basicBlock->getInstructions();
auto Branchiter = instructions.end(); auto Branchiter = instructions.end();
for (auto iter = instructions.begin(); iter != instructions.end(); ++iter) { for (auto iter = instructions.begin(); iter != instructions.end(); ++iter) {
if (Branch) if (Branch)
SysYIROptUtils::usedelete(iter->get()); SysYIROptUtils::usedelete(iter->get());
else if ((*iter)->isTerminator()){ else if ((*iter)->isTerminator()){
Branch = true; Branch = true;
Branchiter = iter; Branchiter = iter;
}
} }
if (Branchiter != instructions.end()) ++Branchiter; }
while (Branchiter != instructions.end()) if (Branchiter != instructions.end()) ++Branchiter;
Branchiter = instructions.erase(Branchiter); while (Branchiter != instructions.end()) {
changed = true;
if (Branch) { // 更新前驱后继关系 Branchiter = instructions.erase(Branchiter);
auto thelastinstinst = basicBlock->getInstructions().end(); }
--thelastinstinst;
auto &Successors = basicBlock->getSuccessors(); if (Branch) { // 更新前驱后继关系
for (auto iterSucc = Successors.begin(); iterSucc != Successors.end();) { auto thelastinstinst = basicBlock->getInstructions().end();
(*iterSucc)->removePredecessor(basicBlock.get()); --thelastinstinst;
basicBlock->removeSuccessor(*iterSucc); auto &Successors = basicBlock->getSuccessors();
} for (auto iterSucc = Successors.begin(); iterSucc != Successors.end();) {
if (thelastinstinst->get()->isUnconditional()) { (*iterSucc)->removePredecessor(basicBlock.get());
BasicBlock* branchBlock = dynamic_cast<BasicBlock *>(thelastinstinst->get()->getOperand(0)); basicBlock->removeSuccessor(*iterSucc);
basicBlock->addSuccessor(branchBlock); }
branchBlock->addPredecessor(basicBlock.get()); if (thelastinstinst->get()->isUnconditional()) {
} else if (thelastinstinst->get()->isConditional()) { BasicBlock* branchBlock = dynamic_cast<BasicBlock *>(thelastinstinst->get()->getOperand(0));
BasicBlock* thenBlock = dynamic_cast<BasicBlock *>(thelastinstinst->get()->getOperand(1)); basicBlock->addSuccessor(branchBlock);
BasicBlock* elseBlock = dynamic_cast<BasicBlock *>(thelastinstinst->get()->getOperand(2)); branchBlock->addPredecessor(basicBlock.get());
basicBlock->addSuccessor(thenBlock); } else if (thelastinstinst->get()->isConditional()) {
basicBlock->addSuccessor(elseBlock); BasicBlock* thenBlock = dynamic_cast<BasicBlock *>(thelastinstinst->get()->getOperand(1));
thenBlock->addPredecessor(basicBlock.get()); BasicBlock* elseBlock = dynamic_cast<BasicBlock *>(thelastinstinst->get()->getOperand(2));
elseBlock->addPredecessor(basicBlock.get()); basicBlock->addSuccessor(thenBlock);
} basicBlock->addSuccessor(elseBlock);
thenBlock->addPredecessor(basicBlock.get());
elseBlock->addPredecessor(basicBlock.get());
} }
} }
} }
return changed;
} }
// 合并空基本块 // 合并空基本块
void SysYCFGOpt::SysYBlockMerge() { bool SysYCFGOpt::SysYBlockMerge(Function *func) {
auto &functions = pModule->getFunctions(); //std::map<std::string, std::unique_ptr<Function>> bool changed = false;
for (auto &function : functions) {
// auto basicBlocks = function.second->getBasicBlocks(); for (auto blockiter = func->getBasicBlocks().begin();
auto &func = function.second; blockiter != func->getBasicBlocks().end();) {
for (auto blockiter = func->getBasicBlocks().begin(); if (blockiter->get()->getNumSuccessors() == 1) {
blockiter != func->getBasicBlocks().end();) { // 如果当前块只有一个后继块
if (blockiter->get()->getNumSuccessors() == 1) { // 且后继块只有一个前驱块
// 如果当前块只有一个后继块 // 则将当前块和后继块合并
// 且后继块只有一个前驱块 if (((blockiter->get())->getSuccessors()[0])->getNumPredecessors() == 1) {
// 则将当前块和后继块合并 // std::cout << "merge block: " << blockiter->get()->getName() << std::endl;
if (((blockiter->get())->getSuccessors()[0])->getNumPredecessors() == 1) { BasicBlock* block = blockiter->get();
// std::cout << "merge block: " << blockiter->get()->getName() << std::endl; BasicBlock* nextBlock = blockiter->get()->getSuccessors()[0];
BasicBlock* block = blockiter->get(); auto nextarguments = nextBlock->getArguments();
BasicBlock* nextBlock = blockiter->get()->getSuccessors()[0]; // 删除br指令
auto nextarguments = nextBlock->getArguments(); if (block->getNumInstructions() != 0) {
// 删除br指令 auto thelastinstinst = block->end();
if (block->getNumInstructions() != 0) { (--thelastinstinst);
auto thelastinstinst = block->end(); if (thelastinstinst->get()->isUnconditional()) {
(--thelastinstinst); SysYIROptUtils::usedelete(thelastinstinst->get());
if (thelastinstinst->get()->isUnconditional()) { block->getInstructions().erase(thelastinstinst);
} else if (thelastinstinst->get()->isConditional()) {
// 如果是条件分支，判断条件是否相同，主要优化相同布尔表达式
if (thelastinstinst->get()->getOperand(1)->getName() == thelastinstinst->get()->getOperand(1)->getName()) {
SysYIROptUtils::usedelete(thelastinstinst->get()); SysYIROptUtils::usedelete(thelastinstinst->get());
block->getInstructions().erase(thelastinstinst); block->getInstructions().erase(thelastinstinst);
} else if (thelastinstinst->get()->isConditional()) {
// 如果是条件分支，判断条件是否相同，主要优化相同布尔表达式
if (thelastinstinst->get()->getOperand(1)->getName() == thelastinstinst->get()->getOperand(1)->getName()) {
SysYIROptUtils::usedelete(thelastinstinst->get());
block->getInstructions().erase(thelastinstinst);
}
} }
} }
// 将后继块的指令移动到当前块
// 并将后继块的父指针改为当前块
for (auto institer = nextBlock->begin(); institer != nextBlock->end();) {
institer->get()->setParent(block);
block->getInstructions().emplace_back(institer->release());
institer = nextBlock->getInstructions().erase(institer);
}
// 合并参数
// TODO：是否需要去重?
for (auto &argm : nextarguments) {
argm->setParent(block);
block->insertArgument(argm);
}
// 更新前驱后继关系，类似树节点操作
block->removeSuccessor(nextBlock);
nextBlock->removePredecessor(block);
std::list<BasicBlock *> succshoulddel;
for (auto &succ : nextBlock->getSuccessors()) {
block->addSuccessor(succ);
succ->replacePredecessor(nextBlock, block);
succshoulddel.push_back(succ);
}
for (auto del : succshoulddel) {
nextBlock->removeSuccessor(del);
}
func->removeBasicBlock(nextBlock);
} else {
blockiter++;
} }
// 将后继块的指令移动到当前块
// 并将后继块的父指针改为当前块
for (auto institer = nextBlock->begin(); institer != nextBlock->end();) {
institer->get()->setParent(block);
block->getInstructions().emplace_back(institer->release());
institer = nextBlock->getInstructions().erase(institer);
}
// 合并参数
// TODO：是否需要去重?
for (auto &argm : nextarguments) {
argm->setParent(block);
block->insertArgument(argm);
}
// 更新前驱后继关系，类似树节点操作
block->removeSuccessor(nextBlock);
nextBlock->removePredecessor(block);
std::list<BasicBlock *> succshoulddel;
for (auto &succ : nextBlock->getSuccessors()) {
block->addSuccessor(succ);
succ->replacePredecessor(nextBlock, block);
succshoulddel.push_back(succ);
}
for (auto del : succshoulddel) {
nextBlock->removeSuccessor(del);
}
func->removeBasicBlock(nextBlock);
changed = true;
} else { } else {
blockiter++; blockiter++;
} }
} else {
blockiter++;
} }
} }
return changed;
} }
// 删除无前驱块，兼容SSA后的处理 // 删除无前驱块，兼容SSA后的处理
void SysYCFGOpt::SysYDelNoPreBLock() { bool SysYCFGOpt::SysYDelNoPreBLock(Function *func) {
auto &functions = pModule->getFunctions(); // std::map<std::string, std::unique_ptr<sysy::Function>> bool changed = false;
for (auto &function : functions) {
auto &func = function.second;
for (auto &block : func->getBasicBlocks()) { for (auto &block : func->getBasicBlocks()) {
block->setreachableFalse(); block->setreachableFalse();
} }
// 对函数基本块做一个拓扑排序，排查不可达基本块 // 对函数基本块做一个拓扑排序，排查不可达基本块
auto entryBlock = func->getEntryBlock(); auto entryBlock = func->getEntryBlock();
entryBlock->setreachableTrue(); entryBlock->setreachableTrue();
std::queue<BasicBlock *> blockqueue; std::queue<BasicBlock *> blockqueue;
blockqueue.push(entryBlock); blockqueue.push(entryBlock);
while (!blockqueue.empty()) { while (!blockqueue.empty()) {
auto block = blockqueue.front(); auto block = blockqueue.front();
blockqueue.pop(); blockqueue.pop();
for (auto &succ : block->getSuccessors()) { for (auto &succ : block->getSuccessors()) {
if (!succ->getreachable()) { if (!succ->getreachable()) {
succ->setreachableTrue(); succ->setreachableTrue();
blockqueue.push(succ); blockqueue.push(succ);
}
}
}
// 删除不可达基本块指令
for (auto blockIter = func->getBasicBlocks().begin(); blockIter != func->getBasicBlocks().end();blockIter++) {
if (!blockIter->get()->getreachable())
for (auto &iterInst : blockIter->get()->getInstructions())
SysYIROptUtils::usedelete(iterInst.get());
}
for (auto blockIter = func->getBasicBlocks().begin(); blockIter != func->getBasicBlocks().end();) {
if (!blockIter->get()->getreachable()) {
for (auto succblock : blockIter->get()->getSuccessors()) {
int indexphi = 1;
for (auto pred : succblock->getPredecessors()) {
if (pred == blockIter->get()) {
break;
}
indexphi++;
}
for (auto &phiinst : succblock->getInstructions()) {
if (phiinst->getKind() != Instruction::kPhi) {
break;
}
phiinst->removeOperand(indexphi);
}
}
// 删除不可达基本块，注意迭代器不可达问题
func->removeBasicBlock((blockIter++)->get());
} else {
blockIter++;
} }
} }
} }
}
void SysYCFGOpt::SysYDelEmptyBlock() { // 删除不可达基本块指令
auto &functions = pModule->getFunctions(); for (auto blockIter = func->getBasicBlocks().begin(); blockIter != func->getBasicBlocks().end();blockIter++) {
for (auto &function : functions) { if (!blockIter->get()->getreachable())
// 收集不可达基本块 for (auto &iterInst : blockIter->get()->getInstructions())
// 这里的不可达基本块是指没有实际指令的基本块 SysYIROptUtils::usedelete(iterInst.get());
// 当一个基本块没有实际指令例如只有phi指令和一个uncondbr指令时，也会被视作不可达
auto basicBlocks = function.second->getBasicBlocks(); }
std::map<sysy::BasicBlock *, BasicBlock *> EmptyBlocks;
// 空块儿和后继的基本块的映射
for (auto &basicBlock : basicBlocks) { for (auto blockIter = func->getBasicBlocks().begin(); blockIter != func->getBasicBlocks().end();) {
if (basicBlock->getNumInstructions() == 0) { if (!blockIter->get()->getreachable()) {
if (basicBlock->getNumSuccessors() == 1) { for (auto succblock : blockIter->get()->getSuccessors()) {
EmptyBlocks[basicBlock.get()] = basicBlock->getSuccessors().front(); int indexphi = 1;
for (auto pred : succblock->getPredecessors()) {
if (pred == blockIter->get()) {
break;
}
indexphi++;
}
for (auto &phiinst : succblock->getInstructions()) {
if (phiinst->getKind() != Instruction::kPhi) {
break;
}
phiinst->removeOperand(indexphi);
} }
} }
else{ // 删除不可达基本块，注意迭代器不可达问题
// 如果只有phi指令和一个uncondbr。(phi)*(uncondbr)? func->removeBasicBlock((blockIter++)->get());
// 判断除了最后一个指令之外是不是只有phi指令 changed = true;
bool onlyPhi = true; } else {
for (auto &inst : basicBlock->getInstructions()) { blockIter++;
if (!inst->isPhi() && !inst->isUnconditional()) { }
onlyPhi = false; }
return changed;
}
// 删除空块
bool SysYCFGOpt::SysYDelEmptyBlock(Function *func, IRBuilder* pBuilder) {
bool changed = false;
// 收集不可达基本块
// 这里的不可达基本块是指没有实际指令的基本块
// 当一个基本块没有实际指令例如只有phi指令和一个uncondbr指令时，也会被视作不可达
auto basicBlocks = func->getBasicBlocks();
std::map<sysy::BasicBlock *, BasicBlock *> EmptyBlocks;
// 空块儿和后继的基本块的映射
for (auto &basicBlock : basicBlocks) {
if (basicBlock->getNumInstructions() == 0) {
if (basicBlock->getNumSuccessors() == 1) {
EmptyBlocks[basicBlock.get()] = basicBlock->getSuccessors().front();
}
}
else{
// 如果只有phi指令和一个uncondbr。(phi)*(uncondbr)?
// 判断除了最后一个指令之外是不是只有phi指令
bool onlyPhi = true;
for (auto &inst : basicBlock->getInstructions()) {
if (!inst->isPhi() && !inst->isUnconditional()) {
onlyPhi = false;
break;
}
}
if(onlyPhi)
EmptyBlocks[basicBlock.get()] = basicBlock->getSuccessors().front();
}
}
// 更新基本块信息，增加必要指令
for (auto &basicBlock : basicBlocks) {
// 把空块转换成只有跳转指令的不可达块
if (distance(basicBlock->begin(), basicBlock->end()) == 0) {
if (basicBlock->getNumSuccessors() == 0) {
continue;
}
if (basicBlock->getNumSuccessors() > 1) {
assert("");
}
pBuilder->setPosition(basicBlock.get(), basicBlock->end());
pBuilder->createUncondBrInst(basicBlock->getSuccessors()[0], {});
continue;
}
auto thelastinst = basicBlock->getInstructions().end();
--thelastinst;
// 根据br指令传递的后继块信息，跳过空块链
if (thelastinst->get()->isUnconditional()) {
BasicBlock* OldBrBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0));
BasicBlock *thelastBlockOld = nullptr;
// 如果空块链表为多个块
while (EmptyBlocks.find(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))) !=
EmptyBlocks.end()) {
thelastBlockOld = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0));
thelastinst->get()->replaceOperand(0, EmptyBlocks[thelastBlockOld]);
}
basicBlock->removeSuccessor(OldBrBlock);
OldBrBlock->removePredecessor(basicBlock.get());
basicBlock->addSuccessor(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0)));
dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->addPredecessor(basicBlock.get());
if (thelastBlockOld != nullptr) {
int indexphi = 0;
for (auto &pred : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->getPredecessors()) {
if (pred == thelastBlockOld) {
break;
}
indexphi++;
}
// 更新phi指令的操作数
// 移除thelastBlockOld对应的phi操作数
for (auto &InstInNew : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->getInstructions()) {
if (InstInNew->isPhi()) {
dynamic_cast<PhiInst *>(InstInNew.get())->removeOperand(indexphi + 1);
} else {
break; break;
} }
} }
if(onlyPhi)
EmptyBlocks[basicBlock.get()] = basicBlock->getSuccessors().front();
} }
} else if (thelastinst->get()->getKind() == Instruction::kCondBr) {
} auto OldThenBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1));
// 更新基本块信息，增加必要指令 auto OldElseBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2));
for (auto &basicBlock : basicBlocks) {
// 把空块转换成只有跳转指令的不可达块 BasicBlock *thelastBlockOld = nullptr;
if (distance(basicBlock->begin(), basicBlock->end()) == 0) { while (EmptyBlocks.find(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))) !=
if (basicBlock->getNumSuccessors() == 0) { EmptyBlocks.end()) {
continue; thelastBlockOld = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1));
} thelastinst->get()->replaceOperand(
if (basicBlock->getNumSuccessors() > 1) { 1, EmptyBlocks[dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))]);
assert(""); }
} basicBlock->removeSuccessor(OldThenBlock);
OldThenBlock->removePredecessor(basicBlock.get());
// 处理 then 和 else 分支合并的情况
if (dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1)) ==
dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))) {
auto thebrBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1));
SysYIROptUtils::usedelete(thelastinst->get());
thelastinst = basicBlock->getInstructions().erase(thelastinst);
pBuilder->setPosition(basicBlock.get(), basicBlock->end()); pBuilder->setPosition(basicBlock.get(), basicBlock->end());
pBuilder->createUncondBrInst(basicBlock->getSuccessors()[0], {}); pBuilder->createUncondBrInst(thebrBlock, {});
continue; continue;
} }
basicBlock->addSuccessor(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1)));
dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))->addPredecessor(basicBlock.get());
// auto indexInNew = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->getPredecessors().
auto thelastinst = basicBlock->getInstructions().end(); if (thelastBlockOld != nullptr) {
--thelastinst; int indexphi = 0;
for (auto &pred : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))->getPredecessors()) {
// 根据br指令传递的后继块信息，跳过空块链 if (pred == thelastBlockOld) {
if (thelastinst->get()->isUnconditional()) { break;
BasicBlock* OldBrBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0)); }
BasicBlock *thelastBlockOld = nullptr; indexphi++;
// 如果空块链表为多个块
while (EmptyBlocks.find(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))) !=
EmptyBlocks.end()) {
thelastBlockOld = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0));
thelastinst->get()->replaceOperand(0, EmptyBlocks[thelastBlockOld]);
} }
for (auto &InstInNew : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))->getInstructions()) {
if (InstInNew->isPhi()) {
dynamic_cast<PhiInst *>(InstInNew.get())->removeOperand(indexphi + 1);
} else {
break;
}
}
}
thelastBlockOld = nullptr;
while (EmptyBlocks.find(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))) !=
EmptyBlocks.end()) {
thelastBlockOld = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2));
thelastinst->get()->replaceOperand(
2, EmptyBlocks[dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))]);
}
basicBlock->removeSuccessor(OldElseBlock);
OldElseBlock->removePredecessor(basicBlock.get());
// 处理 then 和 else 分支合并的情况
if (dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1)) ==
dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))) {
auto thebrBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1));
SysYIROptUtils::usedelete(thelastinst->get());
thelastinst = basicBlock->getInstructions().erase(thelastinst);
pBuilder->setPosition(basicBlock.get(), basicBlock->end());
pBuilder->createUncondBrInst(thebrBlock, {});
continue;
}
basicBlock->addSuccessor(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2)));
dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))->addPredecessor(basicBlock.get());
if (thelastBlockOld != nullptr) {
int indexphi = 0;
for (auto &pred : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))->getPredecessors()) {
if (pred == thelastBlockOld) {
break;
}
indexphi++;
}
for (auto &InstInNew : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))->getInstructions()) {
if (InstInNew->isPhi()) {
dynamic_cast<PhiInst *>(InstInNew.get())->removeOperand(indexphi + 1);
} else {
break;
}
}
}
} else {
if (basicBlock->getNumSuccessors() == 1) {
pBuilder->setPosition(basicBlock.get(), basicBlock->end());
pBuilder->createUncondBrInst(basicBlock->getSuccessors()[0], {});
auto thelastinst = basicBlock->getInstructions().end();
(--thelastinst);
auto OldBrBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0));
sysy::BasicBlock *thelastBlockOld = nullptr;
while (EmptyBlocks.find(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))) !=
EmptyBlocks.end()) {
thelastBlockOld = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0));
thelastinst->get()->replaceOperand(
0, EmptyBlocks[dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))]);
}
basicBlock->removeSuccessor(OldBrBlock); basicBlock->removeSuccessor(OldBrBlock);
OldBrBlock->removePredecessor(basicBlock.get()); OldBrBlock->removePredecessor(basicBlock.get());
basicBlock->addSuccessor(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))); basicBlock->addSuccessor(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0)));
dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->addPredecessor(basicBlock.get()); dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->addPredecessor(basicBlock.get());
if (thelastBlockOld != nullptr) { if (thelastBlockOld != nullptr) {
int indexphi = 0; int indexphi = 0;
for (auto &pred : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->getPredecessors()) { for (auto &pred : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->getPredecessors()) {
@@ -264,8 +390,6 @@ void SysYCFGOpt::SysYDelEmptyBlock() {
indexphi++; indexphi++;
} }
// 更新phi指令的操作数
// 移除thelastBlockOld对应的phi操作数
for (auto &InstInNew : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->getInstructions()) { for (auto &InstInNew : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->getInstructions()) {
if (InstInNew->isPhi()) { if (InstInNew->isPhi()) {
dynamic_cast<PhiInst *>(InstInNew.get())->removeOperand(indexphi + 1); dynamic_cast<PhiInst *>(InstInNew.get())->removeOperand(indexphi + 1);
@@ -274,200 +398,82 @@ void SysYCFGOpt::SysYDelEmptyBlock() {
} }
} }
} }
} else if (thelastinst->get()->getKind() == Instruction::kCondBr) {
auto OldThenBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1));
auto OldElseBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2));
BasicBlock *thelastBlockOld = nullptr;
while (EmptyBlocks.find(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))) !=
EmptyBlocks.end()) {
thelastBlockOld = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1));
thelastinst->get()->replaceOperand(
1, EmptyBlocks[dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))]);
}
basicBlock->removeSuccessor(OldThenBlock);
OldThenBlock->removePredecessor(basicBlock.get());
// 处理 then 和 else 分支合并的情况
if (dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1)) ==
dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))) {
auto thebrBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1));
SysYIROptUtils::usedelete(thelastinst->get());
thelastinst = basicBlock->getInstructions().erase(thelastinst);
pBuilder->setPosition(basicBlock.get(), basicBlock->end());
pBuilder->createUncondBrInst(thebrBlock, {});
continue;
}
basicBlock->addSuccessor(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1)));
dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))->addPredecessor(basicBlock.get());
// auto indexInNew = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->getPredecessors().
if (thelastBlockOld != nullptr) {
int indexphi = 0;
for (auto &pred : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))->getPredecessors()) {
if (pred == thelastBlockOld) {
break;
}
indexphi++;
}
for (auto &InstInNew : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1))->getInstructions()) {
if (InstInNew->isPhi()) {
dynamic_cast<PhiInst *>(InstInNew.get())->removeOperand(indexphi + 1);
} else {
break;
}
}
}
thelastBlockOld = nullptr;
while (EmptyBlocks.find(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))) !=
EmptyBlocks.end()) {
thelastBlockOld = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2));
thelastinst->get()->replaceOperand(
2, EmptyBlocks[dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))]);
}
basicBlock->removeSuccessor(OldElseBlock);
OldElseBlock->removePredecessor(basicBlock.get());
// 处理 then 和 else 分支合并的情况
if (dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1)) ==
dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))) {
auto thebrBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(1));
SysYIROptUtils::usedelete(thelastinst->get());
thelastinst = basicBlock->getInstructions().erase(thelastinst);
pBuilder->setPosition(basicBlock.get(), basicBlock->end());
pBuilder->createUncondBrInst(thebrBlock, {});
continue;
}
basicBlock->addSuccessor(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2)));
dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))->addPredecessor(basicBlock.get());
if (thelastBlockOld != nullptr) {
int indexphi = 0;
for (auto &pred : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))->getPredecessors()) {
if (pred == thelastBlockOld) {
break;
}
indexphi++;
}
for (auto &InstInNew : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(2))->getInstructions()) {
if (InstInNew->isPhi()) {
dynamic_cast<PhiInst *>(InstInNew.get())->removeOperand(indexphi + 1);
} else {
break;
}
}
}
} else {
if (basicBlock->getNumSuccessors() == 1) {
pBuilder->setPosition(basicBlock.get(), basicBlock->end());
pBuilder->createUncondBrInst(basicBlock->getSuccessors()[0], {});
auto thelastinst = basicBlock->getInstructions().end();
(--thelastinst);
auto OldBrBlock = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0));
sysy::BasicBlock *thelastBlockOld = nullptr;
while (EmptyBlocks.find(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))) !=
EmptyBlocks.end()) {
thelastBlockOld = dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0));
thelastinst->get()->replaceOperand(
0, EmptyBlocks[dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))]);
}
basicBlock->removeSuccessor(OldBrBlock);
OldBrBlock->removePredecessor(basicBlock.get());
basicBlock->addSuccessor(dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0)));
dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->addPredecessor(basicBlock.get());
if (thelastBlockOld != nullptr) {
int indexphi = 0;
for (auto &pred : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->getPredecessors()) {
if (pred == thelastBlockOld) {
break;
}
indexphi++;
}
for (auto &InstInNew : dynamic_cast<BasicBlock *>(thelastinst->get()->getOperand(0))->getInstructions()) {
if (InstInNew->isPhi()) {
dynamic_cast<PhiInst *>(InstInNew.get())->removeOperand(indexphi + 1);
} else {
break;
}
}
}
}
}
}
for (auto iter = function.second->getBasicBlocks().begin(); iter != function.second->getBasicBlocks().end();) {
if (EmptyBlocks.find(iter->get()) != EmptyBlocks.end()) {
// EntryBlock跳过
if (iter->get() == function.second->getEntryBlock()) {
++iter;
continue;
}
for (auto &iterInst : iter->get()->getInstructions())
SysYIROptUtils::usedelete(iterInst.get());
// 删除不可达基本块的phi指令的操作数
for (auto &succ : iter->get()->getSuccessors()) {
int index = 0;
for (auto &pred : succ->getPredecessors()) {
if (pred == iter->get()) {
break;
}
index++;
}
for (auto &instinsucc : succ->getInstructions()) {
if (instinsucc->isPhi()) {
dynamic_cast<PhiInst *>(instinsucc.get())->removeOperand(index);
} else {
break;
}
}
}
function.second->removeBasicBlock((iter++)->get());
} else {
++iter;
} }
} }
} }
for (auto iter = func->getBasicBlocks().begin(); iter != func->getBasicBlocks().end();) {
if (EmptyBlocks.find(iter->get()) != EmptyBlocks.end()) {
// EntryBlock跳过
if (iter->get() == func->getEntryBlock()) {
++iter;
continue;
}
for (auto &iterInst : iter->get()->getInstructions())
SysYIROptUtils::usedelete(iterInst.get());
// 删除不可达基本块的phi指令的操作数
for (auto &succ : iter->get()->getSuccessors()) {
int index = 0;
for (auto &pred : succ->getPredecessors()) {
if (pred == iter->get()) {
break;
}
index++;
}
for (auto &instinsucc : succ->getInstructions()) {
if (instinsucc->isPhi()) {
dynamic_cast<PhiInst *>(instinsucc.get())->removeOperand(index);
} else {
break;
}
}
}
func->removeBasicBlock((iter++)->get());
changed = true;
} else {
++iter;
}
}
return changed;
} }
// 如果函数没有返回指令，则添加一个默认返回指令(主要解决void函数没有返回指令的问题) // 如果函数没有返回指令，则添加一个默认返回指令(主要解决void函数没有返回指令的问题)
void SysYCFGOpt::SysYAddReturn() { bool SysYCFGOpt::SysYAddReturn(Function *func, IRBuilder* pBuilder) {
auto &functions = pModule->getFunctions(); bool changed = false;
for (auto &function : functions) { auto basicBlocks = func->getBasicBlocks();
auto &func = function.second; for (auto &block : basicBlocks) {
auto basicBlocks = func->getBasicBlocks(); if (block->getNumSuccessors() == 0) {
for (auto &block : basicBlocks) { changed = true;
if (block->getNumSuccessors() == 0) { // 如果基本块没有后继块，则添加一个返回指令
// 如果基本块没有后继块，则添加一个返回指令 if (block->getNumInstructions() == 0) {
if (block->getNumInstructions() == 0) { pBuilder->setPosition(block.get(), block->end());
pBuilder->setPosition(block.get(), block->end()); pBuilder->createReturnInst();
pBuilder->createReturnInst(); }
} auto thelastinst = block->getInstructions().end();
auto thelastinst = block->getInstructions().end(); --thelastinst;
--thelastinst; if (thelastinst->get()->getKind() != Instruction::kReturn) {
if (thelastinst->get()->getKind() != Instruction::kReturn) { // std::cout << "Warning: Function " << func->getName() << " has no return instruction, adding default return." << std::endl;
// std::cout << "Warning: Function " << func->getName() << " has no return instruction, adding default return." << std::endl;
pBuilder->setPosition(block.get(), block->end()); pBuilder->setPosition(block.get(), block->end());
// TODO: 如果int float函数缺少返回值是否需要报错 // TODO: 如果int float函数缺少返回值是否需要报错
if (func->getReturnType()->isInt()) { if (func->getReturnType()->isInt()) {
pBuilder->createReturnInst(ConstantValue::get(0)); pBuilder->createReturnInst(ConstantValue::get(0));
} else if (func->getReturnType()->isFloat()) { } else if (func->getReturnType()->isFloat()) {
pBuilder->createReturnInst(ConstantValue::get(0.0F)); pBuilder->createReturnInst(ConstantValue::get(0.0F));
} else { } else {
pBuilder->createReturnInst(); pBuilder->createReturnInst();
}
} }
} }
} }
} }
return changed;
} }
} // namespace sysy } // namespace sysy

34
src/include/SysYIRCFGOpt.h
View File

@@ -26,18 +26,32 @@ class SysYCFGOpt {
SysYCFGOpt(Module *pMoudle, IRBuilder *pBuilder) : pModule(pMoudle), pBuilder(pBuilder) {} SysYCFGOpt(Module *pMoudle, IRBuilder *pBuilder) : pModule(pMoudle), pBuilder(pBuilder) {}
void SysYOptimizateAfterIR(){ void SysYOptimizateAfterIR(){
SysYDelInstAfterBr();
SysYBlockMerge(); auto &functions = pModule->getFunctions();
SysYDelNoPreBLock(); for (auto &function : functions) {
SysYDelEmptyBlock(); bool changed = false;
SysYAddReturn(); while(changed){
// 删除br后面的无用指令
changed |= SysYDelInstAfterBr(function.second.get());
// 合并空基本块
changed |= SysYBlockMerge(function.second.get());
// 删除无前驱块
changed |= SysYDelNoPreBLock(function.second.get());
// 删除空块
changed |= SysYDelEmptyBlock(function.second.get(), pBuilder);
// 添加return指令
changed |= SysYAddReturn(function.second.get(), pBuilder);
}
}
} }
void SysYDelInstAfterBr(); // 删除br后面的指令
void SysYDelEmptyBlock(); // 空块删除 public:
void SysYDelNoPreBLock(); // 删除无前驱块（不可达块） static bool SysYDelInstAfterBr(Function *func); // 删除br后面的指令
void SysYBlockMerge(); // 合并基本块(主要针对嵌套if while的exit块， static bool SysYDelEmptyBlock(Function *func, IRBuilder* pBuilder); // 空块删除
static bool SysYDelNoPreBLock(Function *func); // 删除无前驱块（不可达块）
static bool SysYBlockMerge(Function *func); // 合并基本块(主要针对嵌套if while的exit块，
// 也可以修改IR生成实现回填机制 // 也可以修改IR生成实现回填机制
void SysYAddReturn(); // 添加return指令(主要针对Void函数) static bool SysYAddReturn(Function *func, IRBuilder* pBuilder); // 添加return指令(主要针对Void函数)
}; };
} // namespace sysy } // namespace sysy