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stem from the fact that we have two types of passes that need to update it: 1. callgraphscc and module passes that are explicitly aware of it 2. Functionpasses (and loop passes etc) that are interlaced with CGSCC passes by the CGSCC Passmgr. In the case of #1, we can reasonably expect the passes to update the call graph just like any analysis. However, functionpasses are not and generally should not be CG aware. This has caused us no end of problems, so this takes a new approach. Logically, the CGSCC Pass manager can rescan every function after it runs a function pass over it to see if the functionpass made any updates to the IR that affect the callgraph. This allows it to catch new calls introduced by the functionpass. In practice, doing this would be slow. This implementation keeps track of whether or not the current scc is dirtied by a function pass, and, if so, delays updating the callgraph until it is actually needed again. This was we avoid extraneous rescans, but we still have good invariants when the callgraph is needed. Step #2 of the "give Callgraph some sane invariants" is to change CallGraphNode to use a CallBackVH for the callsite entry of the CallGraphNode. This way we can immediately remove entries from the callgraph when a FunctionPass is active instead of having dangling pointers. The current pass tries to tolerate these dangling pointers, but it is just an evil hack. This is related to PR3601/4835/4029. This also reverts r80541, a hack working around the sad lack of invariants. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80566 91177308-0d34-0410-b5e6-96231b3b80d8
321 lines
11 KiB
C++
321 lines
11 KiB
C++
//===- CallGraph.cpp - Build a Module's 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 CallGraph class and provides the BasicCallGraph
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// default implementation.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/CallGraph.h"
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#include "llvm/Module.h"
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#include "llvm/Instructions.h"
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#include "llvm/IntrinsicInst.h"
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#include "llvm/Support/CallSite.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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namespace {
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//===----------------------------------------------------------------------===//
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// BasicCallGraph class definition
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//
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class VISIBILITY_HIDDEN BasicCallGraph : public CallGraph, public ModulePass {
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// Root is root of the call graph, or the external node if a 'main' function
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// couldn't be found.
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//
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CallGraphNode *Root;
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// ExternalCallingNode - This node has edges to all external functions and
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// those internal functions that have their address taken.
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CallGraphNode *ExternalCallingNode;
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// CallsExternalNode - This node has edges to it from all functions making
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// indirect calls or calling an external function.
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CallGraphNode *CallsExternalNode;
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public:
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static char ID; // Class identification, replacement for typeinfo
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BasicCallGraph() : ModulePass(&ID), Root(0),
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ExternalCallingNode(0), CallsExternalNode(0) {}
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// runOnModule - Compute the call graph for the specified module.
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virtual bool runOnModule(Module &M) {
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CallGraph::initialize(M);
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ExternalCallingNode = getOrInsertFunction(0);
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CallsExternalNode = new CallGraphNode(0);
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Root = 0;
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// Add every function to the call graph.
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for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
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addToCallGraph(I);
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// If we didn't find a main function, use the external call graph node
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if (Root == 0) Root = ExternalCallingNode;
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return false;
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}
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.setPreservesAll();
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}
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virtual void print(raw_ostream &OS, const Module *) const {
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OS << "CallGraph Root is: ";
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if (Function *F = getRoot()->getFunction())
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OS << F->getName() << "\n";
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else {
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OS << "<<null function: 0x" << getRoot() << ">>\n";
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}
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CallGraph::print(OS, 0);
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}
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virtual void releaseMemory() {
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destroy();
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}
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CallGraphNode* getExternalCallingNode() const { return ExternalCallingNode; }
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CallGraphNode* getCallsExternalNode() const { return CallsExternalNode; }
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// getRoot - Return the root of the call graph, which is either main, or if
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// main cannot be found, the external node.
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//
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CallGraphNode *getRoot() { return Root; }
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const CallGraphNode *getRoot() const { return Root; }
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private:
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//===---------------------------------------------------------------------
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// Implementation of CallGraph construction
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//
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// addToCallGraph - Add a function to the call graph, and link the node to all
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// of the functions that it calls.
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//
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void addToCallGraph(Function *F) {
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CallGraphNode *Node = getOrInsertFunction(F);
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// If this function has external linkage, anything could call it.
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if (!F->hasLocalLinkage()) {
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ExternalCallingNode->addCalledFunction(CallSite(), Node);
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// Found the entry point?
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if (F->getName() == "main") {
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if (Root) // Found multiple external mains? Don't pick one.
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Root = ExternalCallingNode;
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else
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Root = Node; // Found a main, keep track of it!
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}
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}
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// Loop over all of the users of the function, looking for non-call uses.
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for (Value::use_iterator I = F->use_begin(), E = F->use_end(); I != E; ++I)
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if ((!isa<CallInst>(I) && !isa<InvokeInst>(I))
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|| !CallSite(cast<Instruction>(I)).isCallee(I)) {
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// Not a call, or being used as a parameter rather than as the callee.
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ExternalCallingNode->addCalledFunction(CallSite(), Node);
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break;
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}
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// If this function is not defined in this translation unit, it could call
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// anything.
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if (F->isDeclaration() && !F->isIntrinsic())
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Node->addCalledFunction(CallSite(), CallsExternalNode);
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// Look for calls by this function.
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for (Function::iterator BB = F->begin(), BBE = F->end(); BB != BBE; ++BB)
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for (BasicBlock::iterator II = BB->begin(), IE = BB->end();
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II != IE; ++II) {
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CallSite CS = CallSite::get(II);
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if (CS.getInstruction() && !isa<DbgInfoIntrinsic>(II)) {
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const Function *Callee = CS.getCalledFunction();
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if (Callee)
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Node->addCalledFunction(CS, getOrInsertFunction(Callee));
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else
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Node->addCalledFunction(CS, CallsExternalNode);
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}
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}
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}
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//
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// destroy - Release memory for the call graph
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virtual void destroy() {
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/// CallsExternalNode is not in the function map, delete it explicitly.
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delete CallsExternalNode;
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CallsExternalNode = 0;
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CallGraph::destroy();
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}
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};
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} //End anonymous namespace
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static RegisterAnalysisGroup<CallGraph> X("Call Graph");
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static RegisterPass<BasicCallGraph>
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Y("basiccg", "Basic CallGraph Construction", false, true);
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static RegisterAnalysisGroup<CallGraph, true> Z(Y);
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char CallGraph::ID = 0;
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char BasicCallGraph::ID = 0;
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void CallGraph::initialize(Module &M) {
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Mod = &M;
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}
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void CallGraph::destroy() {
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if (FunctionMap.empty()) return;
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for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end();
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I != E; ++I)
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delete I->second;
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FunctionMap.clear();
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}
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void CallGraph::print(raw_ostream &OS, Module*) const {
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for (CallGraph::const_iterator I = begin(), E = end(); I != E; ++I)
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I->second->print(OS);
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}
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void CallGraph::dump() const {
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print(errs(), 0);
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}
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//===----------------------------------------------------------------------===//
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// Implementations of public modification methods
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//
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// removeFunctionFromModule - Unlink the function from this module, returning
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// it. Because this removes the function from the module, the call graph node
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// is destroyed. This is only valid if the function does not call any other
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// functions (ie, there are no edges in it's CGN). The easiest way to do this
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// is to dropAllReferences before calling this.
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//
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Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) {
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assert(CGN->empty() && "Cannot remove function from call "
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"graph if it references other functions!");
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Function *F = CGN->getFunction(); // Get the function for the call graph node
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delete CGN; // Delete the call graph node for this func
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FunctionMap.erase(F); // Remove the call graph node from the map
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Mod->getFunctionList().remove(F);
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return F;
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}
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// getOrInsertFunction - This method is identical to calling operator[], but
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// it will insert a new CallGraphNode for the specified function if one does
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// not already exist.
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CallGraphNode *CallGraph::getOrInsertFunction(const Function *F) {
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CallGraphNode *&CGN = FunctionMap[F];
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if (CGN) return CGN;
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assert((!F || F->getParent() == Mod) && "Function not in current module!");
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return CGN = new CallGraphNode(const_cast<Function*>(F));
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}
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void CallGraphNode::print(raw_ostream &OS) const {
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if (Function *F = getFunction())
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OS << "Call graph node for function: '" << F->getName() << "'";
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else
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OS << "Call graph node <<null function>>";
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OS << "<<0x" << this << ">> #uses=" << getNumReferences() << '\n';
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for (const_iterator I = begin(), E = end(); I != E; ++I)
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if (Function *FI = I->second->getFunction())
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OS << " Calls function '" << FI->getName() <<"'\n";
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else
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OS << " Calls external node\n";
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OS << "\n";
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}
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void CallGraphNode::dump() const { print(errs()); }
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/// removeCallEdgeFor - This method removes the edge in the node for the
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/// specified call site. Note that this method takes linear time, so it
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/// should be used sparingly.
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void CallGraphNode::removeCallEdgeFor(CallSite CS) {
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for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
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assert(I != CalledFunctions.end() && "Cannot find callsite to remove!");
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if (I->first == CS) {
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I->second->DropRef();
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*I = CalledFunctions.back();
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CalledFunctions.pop_back();
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return;
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}
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}
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}
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// FIXME: REMOVE THIS WHEN HACK IS REMOVED FROM CGSCCPASSMGR.
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void CallGraphNode::removeCallEdgeFor(Instruction *CS) {
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for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
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assert(I != CalledFunctions.end() && "Cannot find callsite to remove!");
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if (I->first.getInstruction() == CS) {
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I->second->DropRef();
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*I = CalledFunctions.back();
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CalledFunctions.pop_back();
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return;
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}
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}
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}
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// removeAnyCallEdgeTo - This method removes any call edges from this node to
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// the specified callee function. This takes more time to execute than
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// removeCallEdgeTo, so it should not be used unless necessary.
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void CallGraphNode::removeAnyCallEdgeTo(CallGraphNode *Callee) {
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for (unsigned i = 0, e = CalledFunctions.size(); i != e; ++i)
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if (CalledFunctions[i].second == Callee) {
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Callee->DropRef();
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CalledFunctions[i] = CalledFunctions.back();
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CalledFunctions.pop_back();
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--i; --e;
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}
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}
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/// removeOneAbstractEdgeTo - Remove one edge associated with a null callsite
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/// from this node to the specified callee function.
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void CallGraphNode::removeOneAbstractEdgeTo(CallGraphNode *Callee) {
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for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
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assert(I != CalledFunctions.end() && "Cannot find callee to remove!");
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CallRecord &CR = *I;
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if (CR.second == Callee && CR.first.getInstruction() == 0) {
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Callee->DropRef();
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*I = CalledFunctions.back();
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CalledFunctions.pop_back();
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return;
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}
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}
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}
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/// replaceCallSite - Make the edge in the node for Old CallSite be for
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/// New CallSite instead. Note that this method takes linear time, so it
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/// should be used sparingly.
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void CallGraphNode::replaceCallSite(CallSite Old, CallSite New,
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CallGraphNode *NewCallee) {
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for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
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assert(I != CalledFunctions.end() && "Cannot find callsite to replace!");
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if (I->first != Old) continue;
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I->first = New;
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// If the callee is changing, not just the callsite, then update it as
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// well.
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if (NewCallee) {
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I->second->DropRef();
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I->second = NewCallee;
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I->second->AddRef();
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}
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return;
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}
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}
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// Enuse that users of CallGraph.h also link with this file
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DEFINING_FILE_FOR(CallGraph)
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