221 lines
7.5 KiB
C++
221 lines
7.5 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 was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source 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.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/CallGraph.h"
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#include "llvm/Constants.h" // Remove when ConstantPointerRefs are gone
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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/ADT/STLExtras.h"
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#include <iostream>
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using namespace llvm;
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static RegisterAnalysis<CallGraph> X("callgraph", "Call Graph Construction");
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// getNodeFor - Return the node for the specified function or create one if it
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// does not already exist.
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//
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CallGraphNode *CallGraph::getNodeFor(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(F);
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}
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static bool isOnlyADirectCall(Function *F, CallSite CS) {
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if (!CS.getInstruction()) return false;
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for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end(); I != E; ++I)
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if (*I == F) return false;
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return true;
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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 CallGraph::addToCallGraph(Function *F) {
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CallGraphNode *Node = getNodeFor(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(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->isExternal() && !F->getIntrinsicID())
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Node->addCalledFunction(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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if (isOnlyADirectCall(F, CallSite::get(Inst)))
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getNodeFor(Inst->getParent()->getParent())->addCalledFunction(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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if (isOnlyADirectCall(F, CallSite::get(Inst)))
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getNodeFor(Inst->getParent()->getParent())->addCalledFunction(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(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(); 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(CallsExternalNode);
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}
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}
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bool CallGraph::run(Module &M) {
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destroy();
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Mod = &M;
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ExternalCallingNode = getNodeFor(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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void CallGraph::destroy() {
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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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delete CallsExternalNode;
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CallsExternalNode = 0;
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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)->getFunction())
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OS << " Calls function '" << (*I)->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(std::cerr); }
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void CallGraph::print(std::ostream &OS, const Module *M) 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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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(std::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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void CallGraph::stub() {}
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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] == 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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// 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 (std::vector<CallGraphNode*>::iterator I = CalledFunctions.begin(),
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E = CalledFunctions.end(); I != E; ++I)
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if (*I == Callee) {
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CalledFunctions.erase(I);
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E = CalledFunctions.end();
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}
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}
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