79 lines
2.5 KiB
C++
79 lines
2.5 KiB
C++
#include "BuildCFG.h"
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#include "Dom.h"
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#include "Liveness.h"
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#include <iostream>
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#include <queue>
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#include <set>
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namespace sysy {
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void *BuildCFG::ID = (void *)&BuildCFG::ID; // 定义唯一的 Pass ID
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// 声明Pass的分析使用
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void BuildCFG::getAnalysisUsage(std::set<void *> &analysisDependencies, std::set<void *> &analysisInvalidations) const {
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// BuildCFG不依赖其他分析
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// analysisDependencies.insert(&DominatorTreeAnalysisPass::ID); // 错误的例子
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// BuildCFG会使所有依赖于CFG的分析结果失效，所以它必须声明这些失效
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analysisInvalidations.insert(&DominatorTreeAnalysisPass::ID);
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analysisInvalidations.insert(&LivenessAnalysisPass::ID);
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}
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bool BuildCFG::runOnFunction(Function *F, AnalysisManager &AM) {
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if (DEBUG) {
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std::cout << "Running BuildCFG pass on function: " << F->getName() << std::endl;
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}
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bool changed = false;
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// 1. 清空所有基本块的前驱和后继列表
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for (auto &bb : F->getBasicBlocks()) {
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bb->clearPredecessors();
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bb->clearSuccessors();
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}
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// 2. 遍历每个基本块，重建CFG
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for (auto &bb : F->getBasicBlocks()) {
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// 获取基本块的最后一条指令
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auto &inst = *bb->terminator();
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Instruction *termInst = inst.get();
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// 确保基本块有终结指令
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if (!termInst) {
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continue;
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}
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// 根据终结指令类型，建立前驱后继关系
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if (termInst->isBranch()) {
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// 无条件跳转
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if (termInst->isUnconditional()) {
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auto brInst = dynamic_cast<UncondBrInst *>(termInst);
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BasicBlock *succ = dynamic_cast<BasicBlock *>(brInst->getBlock());
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assert(succ && "Branch instruction's target must be a BasicBlock");
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bb->addSuccessor(succ);
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succ->addPredecessor(bb.get());
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changed = true;
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// 条件跳转
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} else if (termInst->isConditional()) {
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auto brInst = dynamic_cast<CondBrInst *>(termInst);
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BasicBlock *trueSucc = dynamic_cast<BasicBlock *>(brInst->getThenBlock());
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BasicBlock *falseSucc = dynamic_cast<BasicBlock *>(brInst->getElseBlock());
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assert(trueSucc && falseSucc && "Branch instruction's targets must be BasicBlocks");
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bb->addSuccessor(trueSucc);
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trueSucc->addPredecessor(bb.get());
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bb->addSuccessor(falseSucc);
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falseSucc->addPredecessor(bb.get());
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changed = true;
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}
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} else if (auto retInst = dynamic_cast<ReturnInst *>(termInst)) {
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// RetInst没有后继，无需处理
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// ...
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}
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}
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return changed;
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}
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} // namespace sysy
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