lib/Analysis/IPA/CallGraphSCCPass.cpp

//===- CallGraphSCCPass.cpp - Pass that operates BU on call graph ---------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the CallGraphSCCPass class, which is used for passes
// which are implemented as bottom-up traversals on the call graph.  Because
// there may be cycles in the call graph, passes of this type operate on the
// call-graph in SCC order: that is, they process function bottom-up, except for
// recursive functions, which they process all at once.
//
//===----------------------------------------------------------------------===//

#include "llvm/CallGraphSCCPass.h"
#include "llvm/Analysis/CallGraph.h"
#include "llvm/ADT/SCCIterator.h"
#include "llvm/PassManagers.h"
using namespace llvm;

//===----------------------------------------------------------------------===//
// CGPassManager
//
/// CGPassManager manages FPPassManagers and CalLGraphSCCPasses.

class CGPassManager : public ModulePass, public PMDataManager {

public:
  CGPassManager(int Depth) : PMDataManager(Depth) { }

  /// run - Execute all of the passes scheduled for execution.  Keep track of
  /// whether any of the passes modifies the module, and if so, return true.
  bool runOnModule(Module &M);

  bool doInitialization(CallGraph &CG);
  bool doFinalization(CallGraph &CG);

  /// Pass Manager itself does not invalidate any analysis info.
  void getAnalysisUsage(AnalysisUsage &Info) const {
    // CGPassManager walks SCC and it needs CallGraph.
    Info.addRequired<CallGraph>();
    Info.setPreservesAll();
  }

  // Print passes managed by this manager
  void dumpPassStructure(unsigned Offset) {
    llvm::cerr << std::string(Offset*2, ' ') << "Call Graph SCC Pass Manager\n";
    for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
      Pass *P = getContainedPass(Index);
      P->dumpPassStructure(Offset + 1);
      dumpLastUses(P, Offset+1);
    }
  }

  Pass *getContainedPass(unsigned N) {
    assert ( N < PassVector.size() && "Pass number out of range!");
    Pass *FP = static_cast<Pass *>(PassVector[N]);
    return FP;
  }

  virtual PassManagerType getPassManagerType() { 
    return PMT_CallGraphPassManager; 
  }
};

/// run - Execute all of the passes scheduled for execution.  Keep track of
/// whether any of the passes modifies the module, and if so, return true.
bool CGPassManager::runOnModule(Module &M) {
  CallGraph &CG = getAnalysis<CallGraph>();
  bool Changed = doInitialization(CG);

  std::string Msg1 = "Executing Pass '";
  std::string Msg3 = "' Made Modification '";

  // Walk SCC
  for (scc_iterator<CallGraph*> I = scc_begin(&CG), E = scc_end(&CG);
       I != E; ++I) {

    // Run all passes on current SCC
    for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {  

      Pass *P = getContainedPass(Index);
      AnalysisUsage AnUsage;
      P->getAnalysisUsage(AnUsage);

      std::string Msg2 = "' on Call Graph ...\n'";
      dumpPassInfo(P, Msg1, Msg2);
      dumpAnalysisSetInfo("Required", P, AnUsage.getRequiredSet());

      initializeAnalysisImpl(P);

      //        if (TheTimeInfo) TheTimeInfo->passStarted(P);
      if (CallGraphSCCPass *CGSP = dynamic_cast<CallGraphSCCPass *>(P))
	Changed |= CGSP->runOnSCC(*I);   // TODO : What if CG is changed ?
      else {
	FPPassManager *FPP = dynamic_cast<FPPassManager *>(P);
	assert (FPP && "Invalid CGPassManager member");

	// Run pass P on all functions current SCC
	std::vector<CallGraphNode*> &SCC = *I;
	for (unsigned i = 0, e = SCC.size(); i != e; ++i) {
	  Function *F = SCC[i]->getFunction();
	  if (F) 
	    Changed |= FPP->runOnFunction(*F);
	}
      }
      //        if (TheTimeInfo) TheTimeInfo->passEnded(MP);

      if (Changed)
	dumpPassInfo(P, Msg3, Msg2);
      dumpAnalysisSetInfo("Preserved", P, AnUsage.getPreservedSet());
      
      removeNotPreservedAnalysis(P);
      recordAvailableAnalysis(P);
      removeDeadPasses(P, Msg2);
    }
  }
  Changed |= doFinalization(CG);
  return Changed;
}

/// Initialize CG
bool CGPassManager::doInitialization(CallGraph &CG) {
  bool Changed = false;
  for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {  
    Pass *P = getContainedPass(Index);
    if (CallGraphSCCPass *CGSP = dynamic_cast<CallGraphSCCPass *>(P)) 
      Changed |= CGSP->doInitialization(CG);
  }
  return Changed;
}

/// Finalize CG
bool CGPassManager::doFinalization(CallGraph &CG) {
  bool Changed = false;
  for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {  
    Pass *P = getContainedPass(Index);
    if (CallGraphSCCPass *CGSP = dynamic_cast<CallGraphSCCPass *>(P)) 
      Changed |= CGSP->doFinalization(CG);
  }
  return Changed;
}

/// getAnalysisUsage - For this class, we declare that we require and preserve
/// the call graph.  If the derived class implements this method, it should
/// always explicitly call the implementation here.
void CallGraphSCCPass::getAnalysisUsage(AnalysisUsage &AU) const {
  AU.addRequired<CallGraph>();
  AU.addPreserved<CallGraph>();
}

bool CallGraphSCCPass::runOnModule(Module &M) {
  CallGraph &CG = getAnalysis<CallGraph>();
  bool Changed = doInitialization(CG);
  for (scc_iterator<CallGraph*> I = scc_begin(&CG), E = scc_end(&CG);
       I != E; ++I)
    Changed = runOnSCC(*I);
  return Changed | doFinalization(CG);
}