C++ CallGraphNode::removeCallEdgeTo方法代码示例

/// DeleteBasicBlock - remove the specified basic block from the program,
/// updating the callgraph to reflect any now-obsolete edges due to calls that
/// exist in the BB.
void PruneEH::DeleteBasicBlock(BasicBlock *BB) {
  assert(pred_begin(BB) == pred_end(BB) && "BB is not dead!");
  CallGraph &CG = getAnalysis<CallGraph>();

  CallGraphNode *CGN = CG[BB->getParent()];
  for (BasicBlock::iterator I = BB->end(), E = BB->begin(); I != E; ) {
    --I;
    if (CallInst *CI = dyn_cast<CallInst>(I)) {
      if (Function *Callee = CI->getCalledFunction())
        CGN->removeCallEdgeTo(CG[Callee]);
    } else if (InvokeInst *II = dyn_cast<InvokeInst>(I)) {
      if (Function *Callee = II->getCalledFunction())
        CGN->removeCallEdgeTo(CG[Callee]);
    }
    if (!I->use_empty())
      I->replaceAllUsesWith(UndefValue::get(I->getType()));
  }

  // Get the list of successors of this block.
  std::vector<BasicBlock*> Succs(succ_begin(BB), succ_end(BB));

  for (unsigned i = 0, e = Succs.size(); i != e; ++i)
    Succs[i]->removePredecessor(BB);

  BB->eraseFromParent();
}

/// UpdateCallGraphAfterInlining - Once we have cloned code over from a callee
/// into the caller, update the specified callgraph to reflect the changes we
/// made.  Note that it's possible that not all code was copied over, so only
/// some edges of the callgraph will be remain.
static void UpdateCallGraphAfterInlining(const Function *Caller,
                                         const Function *Callee,
                                         Function::iterator FirstNewBlock,
                                       DenseMap<const Value*, Value*> &ValueMap,
                                         CallGraph &CG) {
  // Update the call graph by deleting the edge from Callee to Caller
  CallGraphNode *CalleeNode = CG[Callee];
  CallGraphNode *CallerNode = CG[Caller];
  CallerNode->removeCallEdgeTo(CalleeNode);
  
  // Since we inlined some uninlined call sites in the callee into the caller,
  // add edges from the caller to all of the callees of the callee.
  for (CallGraphNode::iterator I = CalleeNode->begin(),
       E = CalleeNode->end(); I != E; ++I) {
    const Instruction *OrigCall = I->first.getInstruction();
    
    DenseMap<const Value*, Value*>::iterator VMI = ValueMap.find(OrigCall);
    // Only copy the edge if the call was inlined!
    if (VMI != ValueMap.end() && VMI->second) {
      // If the call was inlined, but then constant folded, there is no edge to
      // add.  Check for this case.
      if (Instruction *NewCall = dyn_cast<Instruction>(VMI->second))
        CallerNode->addCalledFunction(CallSite::get(NewCall), I->second);
    }
  }
}

// doFinalization - Remove now-dead linkonce functions at the end of
// processing to avoid breaking the SCC traversal.
bool Inliner::doFinalization(CallGraph &CG) {
  std::set<CallGraphNode*> FunctionsToRemove;

  // Scan for all of the functions, looking for ones that should now be removed
  // from the program.  Insert the dead ones in the FunctionsToRemove set.
  for (CallGraph::iterator I = CG.begin(), E = CG.end(); I != E; ++I) {
    CallGraphNode *CGN = I->second;
    if (Function *F = CGN ? CGN->getFunction() : 0) {
      // If the only remaining users of the function are dead constants, remove
      // them.
      F->removeDeadConstantUsers();

      if ((F->hasLinkOnceLinkage() || F->hasInternalLinkage()) &&
          F->use_empty()) {

        // Remove any call graph edges from the function to its callees.
        while (!CGN->empty())
          CGN->removeCallEdgeTo((CGN->end()-1)->second);

        // Remove any edges from the external node to the function's call graph
        // node.  These edges might have been made irrelegant due to
        // optimization of the program.
        CG.getExternalCallingNode()->removeAnyCallEdgeTo(CGN);

        // Removing the node for callee from the call graph and delete it.
        FunctionsToRemove.insert(CGN);
      }
    }
  }

  // Now that we know which functions to delete, do so.  We didn't want to do
  // this inline, because that would invalidate our CallGraph::iterator
  // objects. :(
  bool Changed = false;
  for (std::set<CallGraphNode*>::iterator I = FunctionsToRemove.begin(),
         E = FunctionsToRemove.end(); I != E; ++I) {
    delete CG.removeFunctionFromModule(*I);
    ++NumDeleted;
    Changed = true;
  }

  return Changed;
}

// InlineCallIfPossible - If it is possible to inline the specified call site,
// do so and update the CallGraph for this operation.
static bool InlineCallIfPossible(CallSite CS, CallGraph &CG,
                                 const std::set<Function*> &SCCFunctions,
                                 const TargetData &TD) {
  Function *Callee = CS.getCalledFunction();
  if (!InlineFunction(CS, &CG, &TD)) return false;

  // If we inlined the last possible call site to the function, delete the
  // function body now.
  if (Callee->use_empty() && Callee->hasInternalLinkage() &&
      !SCCFunctions.count(Callee)) {
    DOUT << "    -> Deleting dead function: " << Callee->getName() << "\n";

    // Remove any call graph edges from the callee to its callees.
    CallGraphNode *CalleeNode = CG[Callee];
    while (!CalleeNode->empty())
      CalleeNode->removeCallEdgeTo((CalleeNode->end()-1)->second);

    // Removing the node for callee from the call graph and delete it.
    delete CG.removeFunctionFromModule(CalleeNode);
    ++NumDeleted;
  }
  return true;
}