615 lines
		
	
	
		
			22 KiB
		
	
	
	
		
			C++
		
	
	
	
			
		
		
	
	
			615 lines
		
	
	
		
			22 KiB
		
	
	
	
		
			C++
		
	
	
	
//===- CallGraphSCCPass.cpp - Pass that operates BU on call graph ---------===//
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//
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//                     The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the CallGraphSCCPass class, which is used for passes
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// which are implemented as bottom-up traversals on the call graph.  Because
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// there may be cycles in the call graph, passes of this type operate on the
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// call-graph in SCC order: that is, they process function bottom-up, except for
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// recursive functions, which they process all at once.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "cgscc-passmgr"
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#include "llvm/Analysis/CallGraphSCCPass.h"
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#include "llvm/ADT/SCCIterator.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Analysis/CallGraph.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/IntrinsicInst.h"
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#include "llvm/PassManagers.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/Timer.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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static cl::opt<unsigned> 
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MaxIterations("max-cg-scc-iterations", cl::ReallyHidden, cl::init(4));
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STATISTIC(MaxSCCIterations, "Maximum CGSCCPassMgr iterations on one SCC");
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//===----------------------------------------------------------------------===//
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// CGPassManager
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//
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/// CGPassManager manages FPPassManagers and CallGraphSCCPasses.
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namespace {
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class CGPassManager : public ModulePass, public PMDataManager {
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public:
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  static char ID;
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  explicit CGPassManager() 
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    : ModulePass(ID), PMDataManager() { }
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  /// run - Execute all of the passes scheduled for execution.  Keep track of
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  /// whether any of the passes modifies the module, and if so, return true.
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  bool runOnModule(Module &M);
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  using ModulePass::doInitialization;
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  using ModulePass::doFinalization;
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  bool doInitialization(CallGraph &CG);
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  bool doFinalization(CallGraph &CG);
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  /// Pass Manager itself does not invalidate any analysis info.
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  void getAnalysisUsage(AnalysisUsage &Info) const {
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    // CGPassManager walks SCC and it needs CallGraph.
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    Info.addRequired<CallGraph>();
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    Info.setPreservesAll();
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  }
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  virtual const char *getPassName() const {
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    return "CallGraph Pass Manager";
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  }
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  virtual PMDataManager *getAsPMDataManager() { return this; }
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  virtual Pass *getAsPass() { return this; }
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  // Print passes managed by this manager
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  void dumpPassStructure(unsigned Offset) {
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    errs().indent(Offset*2) << "Call Graph SCC Pass Manager\n";
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    for (unsigned Index = 0; Index < getNumContainedPasses(); ++Index) {
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      Pass *P = getContainedPass(Index);
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      P->dumpPassStructure(Offset + 1);
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      dumpLastUses(P, Offset+1);
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    }
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  }
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  Pass *getContainedPass(unsigned N) {
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    assert(N < PassVector.size() && "Pass number out of range!");
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    return static_cast<Pass *>(PassVector[N]);
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  }
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  virtual PassManagerType getPassManagerType() const { 
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    return PMT_CallGraphPassManager; 
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  }
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private:
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  bool RunAllPassesOnSCC(CallGraphSCC &CurSCC, CallGraph &CG,
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                         bool &DevirtualizedCall);
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  bool RunPassOnSCC(Pass *P, CallGraphSCC &CurSCC,
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                    CallGraph &CG, bool &CallGraphUpToDate,
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                    bool &DevirtualizedCall);
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  bool RefreshCallGraph(CallGraphSCC &CurSCC, CallGraph &CG,
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                        bool IsCheckingMode);
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};
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} // end anonymous namespace.
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char CGPassManager::ID = 0;
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bool CGPassManager::RunPassOnSCC(Pass *P, CallGraphSCC &CurSCC,
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                                 CallGraph &CG, bool &CallGraphUpToDate,
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                                 bool &DevirtualizedCall) {
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  bool Changed = false;
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  PMDataManager *PM = P->getAsPMDataManager();
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  if (PM == 0) {
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    CallGraphSCCPass *CGSP = (CallGraphSCCPass*)P;
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    if (!CallGraphUpToDate) {
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      DevirtualizedCall |= RefreshCallGraph(CurSCC, CG, false);
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      CallGraphUpToDate = true;
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    }
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    {
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      TimeRegion PassTimer(getPassTimer(CGSP));
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      Changed = CGSP->runOnSCC(CurSCC);
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    }
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    // After the CGSCCPass is done, when assertions are enabled, use
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    // RefreshCallGraph to verify that the callgraph was correctly updated.
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#ifndef NDEBUG
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    if (Changed)
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      RefreshCallGraph(CurSCC, CG, true);
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#endif
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    return Changed;
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  }
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  assert(PM->getPassManagerType() == PMT_FunctionPassManager &&
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         "Invalid CGPassManager member");
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  FPPassManager *FPP = (FPPassManager*)P;
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  // Run pass P on all functions in the current SCC.
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  for (CallGraphSCC::iterator I = CurSCC.begin(), E = CurSCC.end();
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       I != E; ++I) {
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    if (Function *F = (*I)->getFunction()) {
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      dumpPassInfo(P, EXECUTION_MSG, ON_FUNCTION_MSG, F->getName());
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      TimeRegion PassTimer(getPassTimer(FPP));
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      Changed |= FPP->runOnFunction(*F);
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    }
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  }
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  // The function pass(es) modified the IR, they may have clobbered the
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  // callgraph.
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  if (Changed && CallGraphUpToDate) {
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    DEBUG(dbgs() << "CGSCCPASSMGR: Pass Dirtied SCC: "
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                 << P->getPassName() << '\n');
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    CallGraphUpToDate = false;
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  }
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  return Changed;
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}
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/// RefreshCallGraph - Scan the functions in the specified CFG and resync the
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/// callgraph with the call sites found in it.  This is used after
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/// FunctionPasses have potentially munged the callgraph, and can be used after
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/// CallGraphSCC passes to verify that they correctly updated the callgraph.
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///
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/// This function returns true if it devirtualized an existing function call,
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/// meaning it turned an indirect call into a direct call.  This happens when
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/// a function pass like GVN optimizes away stuff feeding the indirect call.
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/// This never happens in checking mode.
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///
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bool CGPassManager::RefreshCallGraph(CallGraphSCC &CurSCC,
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                                     CallGraph &CG, bool CheckingMode) {
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  DenseMap<Value*, CallGraphNode*> CallSites;
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  DEBUG(dbgs() << "CGSCCPASSMGR: Refreshing SCC with " << CurSCC.size()
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               << " nodes:\n";
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        for (CallGraphSCC::iterator I = CurSCC.begin(), E = CurSCC.end();
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             I != E; ++I)
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          (*I)->dump();
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        );
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  bool MadeChange = false;
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  bool DevirtualizedCall = false;
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  // Scan all functions in the SCC.
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  unsigned FunctionNo = 0;
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  for (CallGraphSCC::iterator SCCIdx = CurSCC.begin(), E = CurSCC.end();
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       SCCIdx != E; ++SCCIdx, ++FunctionNo) {
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    CallGraphNode *CGN = *SCCIdx;
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    Function *F = CGN->getFunction();
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    if (F == 0 || F->isDeclaration()) continue;
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    // Walk the function body looking for call sites.  Sync up the call sites in
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    // CGN with those actually in the function.
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    // Keep track of the number of direct and indirect calls that were
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    // invalidated and removed.
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    unsigned NumDirectRemoved = 0, NumIndirectRemoved = 0;
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    // Get the set of call sites currently in the function.
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    for (CallGraphNode::iterator I = CGN->begin(), E = CGN->end(); I != E; ) {
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      // If this call site is null, then the function pass deleted the call
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      // entirely and the WeakVH nulled it out.  
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      if (I->first == 0 ||
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          // If we've already seen this call site, then the FunctionPass RAUW'd
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          // one call with another, which resulted in two "uses" in the edge
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          // list of the same call.
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          CallSites.count(I->first) ||
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          // If the call edge is not from a call or invoke, then the function
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          // pass RAUW'd a call with another value.  This can happen when
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          // constant folding happens of well known functions etc.
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          !CallSite(I->first)) {
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        assert(!CheckingMode &&
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               "CallGraphSCCPass did not update the CallGraph correctly!");
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        // If this was an indirect call site, count it.
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        if (I->second->getFunction() == 0)
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          ++NumIndirectRemoved;
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        else 
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          ++NumDirectRemoved;
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        // Just remove the edge from the set of callees, keep track of whether
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        // I points to the last element of the vector.
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        bool WasLast = I + 1 == E;
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        CGN->removeCallEdge(I);
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        // If I pointed to the last element of the vector, we have to bail out:
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        // iterator checking rejects comparisons of the resultant pointer with
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        // end.
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        if (WasLast)
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          break;
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        E = CGN->end();
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        continue;
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      }
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      assert(!CallSites.count(I->first) &&
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             "Call site occurs in node multiple times");
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      CallSites.insert(std::make_pair(I->first, I->second));
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      ++I;
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    }
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    // Loop over all of the instructions in the function, getting the callsites.
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    // Keep track of the number of direct/indirect calls added.
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    unsigned NumDirectAdded = 0, NumIndirectAdded = 0;
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    for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
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      for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
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        CallSite CS(cast<Value>(I));
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        if (!CS) continue;
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        Function *Callee = CS.getCalledFunction();
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        if (Callee && Callee->isIntrinsic()) continue;
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        // If this call site already existed in the callgraph, just verify it
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        // matches up to expectations and remove it from CallSites.
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        DenseMap<Value*, CallGraphNode*>::iterator ExistingIt =
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          CallSites.find(CS.getInstruction());
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        if (ExistingIt != CallSites.end()) {
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          CallGraphNode *ExistingNode = ExistingIt->second;
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          // Remove from CallSites since we have now seen it.
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          CallSites.erase(ExistingIt);
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          // Verify that the callee is right.
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          if (ExistingNode->getFunction() == CS.getCalledFunction())
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            continue;
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          // If we are in checking mode, we are not allowed to actually mutate
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          // the callgraph.  If this is a case where we can infer that the
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          // callgraph is less precise than it could be (e.g. an indirect call
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          // site could be turned direct), don't reject it in checking mode, and
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          // don't tweak it to be more precise.
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          if (CheckingMode && CS.getCalledFunction() &&
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              ExistingNode->getFunction() == 0)
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            continue;
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          assert(!CheckingMode &&
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                 "CallGraphSCCPass did not update the CallGraph correctly!");
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          // If not, we either went from a direct call to indirect, indirect to
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          // direct, or direct to different direct.
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          CallGraphNode *CalleeNode;
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          if (Function *Callee = CS.getCalledFunction()) {
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            CalleeNode = CG.getOrInsertFunction(Callee);
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            // Keep track of whether we turned an indirect call into a direct
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            // one.
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            if (ExistingNode->getFunction() == 0) {
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              DevirtualizedCall = true;
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              DEBUG(dbgs() << "  CGSCCPASSMGR: Devirtualized call to '"
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                           << Callee->getName() << "'\n");
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            }
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          } else {
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            CalleeNode = CG.getCallsExternalNode();
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          }
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          // Update the edge target in CGN.
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          CGN->replaceCallEdge(CS, CS, CalleeNode);
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          MadeChange = true;
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          continue;
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        }
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        assert(!CheckingMode &&
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               "CallGraphSCCPass did not update the CallGraph correctly!");
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        // If the call site didn't exist in the CGN yet, add it.
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        CallGraphNode *CalleeNode;
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        if (Function *Callee = CS.getCalledFunction()) {
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          CalleeNode = CG.getOrInsertFunction(Callee);
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          ++NumDirectAdded;
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        } else {
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          CalleeNode = CG.getCallsExternalNode();
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          ++NumIndirectAdded;
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        }
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        CGN->addCalledFunction(CS, CalleeNode);
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        MadeChange = true;
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      }
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    // We scanned the old callgraph node, removing invalidated call sites and
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    // then added back newly found call sites.  One thing that can happen is
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    // that an old indirect call site was deleted and replaced with a new direct
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    // call.  In this case, we have devirtualized a call, and CGSCCPM would like
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    // to iteratively optimize the new code.  Unfortunately, we don't really
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    // have a great way to detect when this happens.  As an approximation, we
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    // just look at whether the number of indirect calls is reduced and the
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    // number of direct calls is increased.  There are tons of ways to fool this
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    // (e.g. DCE'ing an indirect call and duplicating an unrelated block with a
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    // direct call) but this is close enough.
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    if (NumIndirectRemoved > NumIndirectAdded &&
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        NumDirectRemoved < NumDirectAdded)
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      DevirtualizedCall = true;
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    // After scanning this function, if we still have entries in callsites, then
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    // they are dangling pointers.  WeakVH should save us for this, so abort if
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    // this happens.
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    assert(CallSites.empty() && "Dangling pointers found in call sites map");
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    // Periodically do an explicit clear to remove tombstones when processing
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    // large scc's.
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    if ((FunctionNo & 15) == 15)
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      CallSites.clear();
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  }
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  DEBUG(if (MadeChange) {
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          dbgs() << "CGSCCPASSMGR: Refreshed SCC is now:\n";
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          for (CallGraphSCC::iterator I = CurSCC.begin(), E = CurSCC.end();
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            I != E; ++I)
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              (*I)->dump();
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          if (DevirtualizedCall)
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            dbgs() << "CGSCCPASSMGR: Refresh devirtualized a call!\n";
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         } else {
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           dbgs() << "CGSCCPASSMGR: SCC Refresh didn't change call graph.\n";
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         }
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        );
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  (void)MadeChange;
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  return DevirtualizedCall;
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}
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/// RunAllPassesOnSCC -  Execute the body of the entire pass manager on the
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/// specified SCC.  This keeps track of whether a function pass devirtualizes
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/// any calls and returns it in DevirtualizedCall.
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bool CGPassManager::RunAllPassesOnSCC(CallGraphSCC &CurSCC, CallGraph &CG,
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                                      bool &DevirtualizedCall) {
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  bool Changed = false;
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  // CallGraphUpToDate - Keep track of whether the callgraph is known to be
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  // up-to-date or not.  The CGSSC pass manager runs two types of passes:
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  // CallGraphSCC Passes and other random function passes.  Because other
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  // random function passes are not CallGraph aware, they may clobber the
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  // call graph by introducing new calls or deleting other ones.  This flag
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  // is set to false when we run a function pass so that we know to clean up
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  // the callgraph when we need to run a CGSCCPass again.
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  bool CallGraphUpToDate = true;
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  // Run all passes on current SCC.
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  for (unsigned PassNo = 0, e = getNumContainedPasses();
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       PassNo != e; ++PassNo) {
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    Pass *P = getContainedPass(PassNo);
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    // If we're in -debug-pass=Executions mode, construct the SCC node list,
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    // otherwise avoid constructing this string as it is expensive.
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    if (isPassDebuggingExecutionsOrMore()) {
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      std::string Functions;
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  #ifndef NDEBUG
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      raw_string_ostream OS(Functions);
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      for (CallGraphSCC::iterator I = CurSCC.begin(), E = CurSCC.end();
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           I != E; ++I) {
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        if (I != CurSCC.begin()) OS << ", ";
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        (*I)->print(OS);
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      }
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      OS.flush();
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  #endif
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      dumpPassInfo(P, EXECUTION_MSG, ON_CG_MSG, Functions);
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    }
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    dumpRequiredSet(P);
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    initializeAnalysisImpl(P);
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    // Actually run this pass on the current SCC.
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    Changed |= RunPassOnSCC(P, CurSCC, CG,
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                            CallGraphUpToDate, DevirtualizedCall);
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    if (Changed)
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      dumpPassInfo(P, MODIFICATION_MSG, ON_CG_MSG, "");
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    dumpPreservedSet(P);
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    verifyPreservedAnalysis(P);      
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    removeNotPreservedAnalysis(P);
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    recordAvailableAnalysis(P);
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    removeDeadPasses(P, "", ON_CG_MSG);
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  }
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 | 
						|
  // If the callgraph was left out of date (because the last pass run was a
 | 
						|
  // functionpass), refresh it before we move on to the next SCC.
 | 
						|
  if (!CallGraphUpToDate)
 | 
						|
    DevirtualizedCall |= RefreshCallGraph(CurSCC, CG, false);
 | 
						|
  return Changed;
 | 
						|
}
 | 
						|
 | 
						|
/// 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);
 | 
						|
  
 | 
						|
  // Walk the callgraph in bottom-up SCC order.
 | 
						|
  scc_iterator<CallGraph*> CGI = scc_begin(&CG);
 | 
						|
 | 
						|
  CallGraphSCC CurSCC(&CGI);
 | 
						|
  while (!CGI.isAtEnd()) {
 | 
						|
    // Copy the current SCC and increment past it so that the pass can hack
 | 
						|
    // on the SCC if it wants to without invalidating our iterator.
 | 
						|
    std::vector<CallGraphNode*> &NodeVec = *CGI;
 | 
						|
    CurSCC.initialize(&NodeVec[0], &NodeVec[0]+NodeVec.size());
 | 
						|
    ++CGI;
 | 
						|
    
 | 
						|
    // At the top level, we run all the passes in this pass manager on the
 | 
						|
    // functions in this SCC.  However, we support iterative compilation in the
 | 
						|
    // case where a function pass devirtualizes a call to a function.  For
 | 
						|
    // example, it is very common for a function pass (often GVN or instcombine)
 | 
						|
    // to eliminate the addressing that feeds into a call.  With that improved
 | 
						|
    // information, we would like the call to be an inline candidate, infer
 | 
						|
    // mod-ref information etc.
 | 
						|
    //
 | 
						|
    // Because of this, we allow iteration up to a specified iteration count.
 | 
						|
    // This only happens in the case of a devirtualized call, so we only burn
 | 
						|
    // compile time in the case that we're making progress.  We also have a hard
 | 
						|
    // iteration count limit in case there is crazy code.
 | 
						|
    unsigned Iteration = 0;
 | 
						|
    bool DevirtualizedCall = false;
 | 
						|
    do {
 | 
						|
      DEBUG(if (Iteration)
 | 
						|
              dbgs() << "  SCCPASSMGR: Re-visiting SCC, iteration #"
 | 
						|
                     << Iteration << '\n');
 | 
						|
      DevirtualizedCall = false;
 | 
						|
      Changed |= RunAllPassesOnSCC(CurSCC, CG, DevirtualizedCall);
 | 
						|
    } while (Iteration++ < MaxIterations && DevirtualizedCall);
 | 
						|
    
 | 
						|
    if (DevirtualizedCall)
 | 
						|
      DEBUG(dbgs() << "  CGSCCPASSMGR: Stopped iteration after " << Iteration
 | 
						|
                   << " times, due to -max-cg-scc-iterations\n");
 | 
						|
    
 | 
						|
    if (Iteration > MaxSCCIterations)
 | 
						|
      MaxSCCIterations = Iteration;
 | 
						|
    
 | 
						|
  }
 | 
						|
  Changed |= doFinalization(CG);
 | 
						|
  return Changed;
 | 
						|
}
 | 
						|
 | 
						|
 | 
						|
/// Initialize CG
 | 
						|
bool CGPassManager::doInitialization(CallGraph &CG) {
 | 
						|
  bool Changed = false;
 | 
						|
  for (unsigned i = 0, e = getNumContainedPasses(); i != e; ++i) {  
 | 
						|
    if (PMDataManager *PM = getContainedPass(i)->getAsPMDataManager()) {
 | 
						|
      assert(PM->getPassManagerType() == PMT_FunctionPassManager &&
 | 
						|
             "Invalid CGPassManager member");
 | 
						|
      Changed |= ((FPPassManager*)PM)->doInitialization(CG.getModule());
 | 
						|
    } else {
 | 
						|
      Changed |= ((CallGraphSCCPass*)getContainedPass(i))->doInitialization(CG);
 | 
						|
    }
 | 
						|
  }
 | 
						|
  return Changed;
 | 
						|
}
 | 
						|
 | 
						|
/// Finalize CG
 | 
						|
bool CGPassManager::doFinalization(CallGraph &CG) {
 | 
						|
  bool Changed = false;
 | 
						|
  for (unsigned i = 0, e = getNumContainedPasses(); i != e; ++i) {  
 | 
						|
    if (PMDataManager *PM = getContainedPass(i)->getAsPMDataManager()) {
 | 
						|
      assert(PM->getPassManagerType() == PMT_FunctionPassManager &&
 | 
						|
             "Invalid CGPassManager member");
 | 
						|
      Changed |= ((FPPassManager*)PM)->doFinalization(CG.getModule());
 | 
						|
    } else {
 | 
						|
      Changed |= ((CallGraphSCCPass*)getContainedPass(i))->doFinalization(CG);
 | 
						|
    }
 | 
						|
  }
 | 
						|
  return Changed;
 | 
						|
}
 | 
						|
 | 
						|
//===----------------------------------------------------------------------===//
 | 
						|
// CallGraphSCC Implementation
 | 
						|
//===----------------------------------------------------------------------===//
 | 
						|
 | 
						|
/// ReplaceNode - This informs the SCC and the pass manager that the specified
 | 
						|
/// Old node has been deleted, and New is to be used in its place.
 | 
						|
void CallGraphSCC::ReplaceNode(CallGraphNode *Old, CallGraphNode *New) {
 | 
						|
  assert(Old != New && "Should not replace node with self");
 | 
						|
  for (unsigned i = 0; ; ++i) {
 | 
						|
    assert(i != Nodes.size() && "Node not in SCC");
 | 
						|
    if (Nodes[i] != Old) continue;
 | 
						|
    Nodes[i] = New;
 | 
						|
    break;
 | 
						|
  }
 | 
						|
  
 | 
						|
  // Update the active scc_iterator so that it doesn't contain dangling
 | 
						|
  // pointers to the old CallGraphNode.
 | 
						|
  scc_iterator<CallGraph*> *CGI = (scc_iterator<CallGraph*>*)Context;
 | 
						|
  CGI->ReplaceNode(Old, New);
 | 
						|
}
 | 
						|
 | 
						|
 | 
						|
//===----------------------------------------------------------------------===//
 | 
						|
// CallGraphSCCPass Implementation
 | 
						|
//===----------------------------------------------------------------------===//
 | 
						|
 | 
						|
/// Assign pass manager to manage this pass.
 | 
						|
void CallGraphSCCPass::assignPassManager(PMStack &PMS,
 | 
						|
                                         PassManagerType PreferredType) {
 | 
						|
  // Find CGPassManager 
 | 
						|
  while (!PMS.empty() &&
 | 
						|
         PMS.top()->getPassManagerType() > PMT_CallGraphPassManager)
 | 
						|
    PMS.pop();
 | 
						|
 | 
						|
  assert(!PMS.empty() && "Unable to handle Call Graph Pass");
 | 
						|
  CGPassManager *CGP;
 | 
						|
  
 | 
						|
  if (PMS.top()->getPassManagerType() == PMT_CallGraphPassManager)
 | 
						|
    CGP = (CGPassManager*)PMS.top();
 | 
						|
  else {
 | 
						|
    // Create new Call Graph SCC Pass Manager if it does not exist. 
 | 
						|
    assert(!PMS.empty() && "Unable to create Call Graph Pass Manager");
 | 
						|
    PMDataManager *PMD = PMS.top();
 | 
						|
 | 
						|
    // [1] Create new Call Graph Pass Manager
 | 
						|
    CGP = new CGPassManager();
 | 
						|
 | 
						|
    // [2] Set up new manager's top level manager
 | 
						|
    PMTopLevelManager *TPM = PMD->getTopLevelManager();
 | 
						|
    TPM->addIndirectPassManager(CGP);
 | 
						|
 | 
						|
    // [3] Assign manager to manage this new manager. This may create
 | 
						|
    // and push new managers into PMS
 | 
						|
    Pass *P = CGP;
 | 
						|
    TPM->schedulePass(P);
 | 
						|
 | 
						|
    // [4] Push new manager into PMS
 | 
						|
    PMS.push(CGP);
 | 
						|
  }
 | 
						|
 | 
						|
  CGP->add(this);
 | 
						|
}
 | 
						|
 | 
						|
/// 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>();
 | 
						|
}
 | 
						|
 | 
						|
 | 
						|
//===----------------------------------------------------------------------===//
 | 
						|
// PrintCallGraphPass Implementation
 | 
						|
//===----------------------------------------------------------------------===//
 | 
						|
 | 
						|
namespace {
 | 
						|
  /// PrintCallGraphPass - Print a Module corresponding to a call graph.
 | 
						|
  ///
 | 
						|
  class PrintCallGraphPass : public CallGraphSCCPass {
 | 
						|
    std::string Banner;
 | 
						|
    raw_ostream &Out;       // raw_ostream to print on.
 | 
						|
    
 | 
						|
  public:
 | 
						|
    static char ID;
 | 
						|
    PrintCallGraphPass(const std::string &B, raw_ostream &o)
 | 
						|
      : CallGraphSCCPass(ID), Banner(B), Out(o) {}
 | 
						|
    
 | 
						|
    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
 | 
						|
      AU.setPreservesAll();
 | 
						|
    }
 | 
						|
    
 | 
						|
    bool runOnSCC(CallGraphSCC &SCC) {
 | 
						|
      Out << Banner;
 | 
						|
      for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I)
 | 
						|
        (*I)->getFunction()->print(Out);
 | 
						|
      return false;
 | 
						|
    }
 | 
						|
  };
 | 
						|
  
 | 
						|
} // end anonymous namespace.
 | 
						|
 | 
						|
char PrintCallGraphPass::ID = 0;
 | 
						|
 | 
						|
Pass *CallGraphSCCPass::createPrinterPass(raw_ostream &O,
 | 
						|
                                          const std::string &Banner) const {
 | 
						|
  return new PrintCallGraphPass(Banner, O);
 | 
						|
}
 | 
						|
 |