forked from OSchip/llvm-project
323 lines
11 KiB
C++
323 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/Support/CallSite.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Support/Streams.h"
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#include <ostream>
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using namespace llvm;
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/// isOnlyADirectCall - Return true if this callsite is *just* a direct call to
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/// the specified function. Specifically return false if the callsite also
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/// takes the address of the function.
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static bool isOnlyADirectCall(Function *F, CallSite CS) {
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if (!CS.getInstruction()) return false;
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return !CS.hasArgument(F);
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}
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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((intptr_t)&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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void print(std::ostream *o, const Module *M) const {
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if (o) print(*o, M);
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}
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virtual void print(std::ostream &o, const Module *M) const {
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o << "CallGraph Root is: ";
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if (Function *F = getRoot()->getFunction())
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o << F->getName() << "\n";
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else
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o << "<<null function: 0x" << getRoot() << ">>\n";
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CallGraph::print(o, M);
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}
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virtual void releaseMemory() {
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destroy();
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}
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/// dump - Print out this call graph.
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///
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inline void dump() const {
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print(cerr, Mod);
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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->hasInternalLinkage()) {
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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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// 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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// Loop over all of the users of the function... looking for callers...
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//
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bool isUsedExternally = false;
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for (Value::use_iterator I = F->use_begin(), E = F->use_end(); I != E; ++I){
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if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
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CallSite CS = CallSite::get(Inst);
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if (isOnlyADirectCall(F, CS))
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getOrInsertFunction(Inst->getParent()->getParent())
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->addCalledFunction(CS, Node);
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else
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isUsedExternally = true;
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} else if (GlobalValue *GV = dyn_cast<GlobalValue>(*I)) {
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for (Value::use_iterator I = GV->use_begin(), E = GV->use_end();
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I != E; ++I)
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if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
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CallSite CS = CallSite::get(Inst);
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if (isOnlyADirectCall(F, CS))
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getOrInsertFunction(Inst->getParent()->getParent())
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->addCalledFunction(CS, Node);
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else
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isUsedExternally = true;
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} else {
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isUsedExternally = true;
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}
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} else { // Can't classify the user!
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isUsedExternally = true;
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}
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}
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if (isUsedExternally)
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ExternalCallingNode->addCalledFunction(CallSite(), Node);
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// Look for an indirect function call.
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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() && !CS.getCalledFunction())
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Node->addCalledFunction(CS, CallsExternalNode);
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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()) {
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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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}
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void CallGraph::print(std::ostream &OS, const Module *M) 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(cerr, 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->CalledFunctions.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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// changeFunction - This method changes the function associated with this
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// CallGraphNode, for use by transformations that need to change the prototype
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// of a Function (thus they must create a new Function and move the old code
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// over).
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void CallGraph::changeFunction(Function *OldF, Function *NewF) {
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iterator I = FunctionMap.find(OldF);
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CallGraphNode *&New = FunctionMap[NewF];
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assert(I != FunctionMap.end() && I->second && !New &&
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"OldF didn't exist in CG or NewF already does!");
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New = I->second;
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New->F = NewF;
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FunctionMap.erase(I);
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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(std::ostream &OS) const {
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if (Function *F = getFunction())
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OS << "Call graph node for function: '" << F->getName() <<"'\n";
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else
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OS << "Call graph node <<null function: 0x" << this << ">>:\n";
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for (const_iterator I = begin(), E = end(); I != E; ++I)
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if (I->second->getFunction())
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OS << " Calls function '" << I->second->getFunction()->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(cerr); }
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void CallGraphNode::removeCallEdgeTo(CallGraphNode *Callee) {
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for (unsigned i = CalledFunctions.size(); ; --i) {
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assert(i && "Cannot find callee to remove!");
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if (CalledFunctions[i-1].second == Callee) {
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CalledFunctions.erase(CalledFunctions.begin()+i-1);
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return;
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}
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}
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}
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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 (unsigned i = CalledFunctions.size(); ; --i) {
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assert(i && "Cannot find callee to remove!");
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if (CalledFunctions[i-1].first == CS) {
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CalledFunctions.erase(CalledFunctions.begin()+i-1);
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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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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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// Enuse that users of CallGraph.h also link with this file
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DEFINING_FILE_FOR(CallGraph)
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