LLVM 源码分析（四）FunctionPass

FunctionPass 主要增加doInitaliztion() ;doFinalization();runOnFunction();
1.

bool FunctionPass::doInitialization(Module &) {  // By default, don't do anything.  return false;}bool FunctionPass::doFinalization(Module &) {  // By default, don't do anything.  return false;}

PassManager.cpp

// Implement doInitialization and doFinalizationbool BBPassManager::doInitialization(Module &M) {  bool Changed = false;  for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index)    Changed |= getContainedPass(Index)->doInitialization(M);  return Changed;}bool BBPassManager::doFinalization(Module &M) {  bool Changed = false;  for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index)    Changed |= getContainedPass(Index)->doFinalization(M);  return Changed;}

2.runOnFunction - Virtual method overriden by subclasses to do the per-function processing of the pass.

和runOnModule 类似都是随着FunctionPass 的执行而执行

#include "llvm/Pass.h"#include "llvm/Function.h"#include "llvm/Support/raw_ostream.h"namespace {  // Hello - The first implementation, without getAnalysisUsage.  struct Hello : public FunctionPass {    static char ID; // Pass identification, replacement for typeid    Hello() : FunctionPass(ID) {}    virtual bool runOnFunction(Function &F) {      ++HelloCounter;      errs() << "Hello: ";      errs().write_escaped(F.getName()) << '\n';      return false;    }   bool doInitialization(Module &F){        // By default, don't do anything.        errs()<<"Module test";        return false;    }  };}char Hello::ID = 0;static RegisterPass<Hello> X("hello", "Hello World Pass");

1楼ychw3658小时前

图片都有点不太正常 鼠标左键按住拖到就可以去另外的网页里面看了