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//===- CallGraph.cpp - Build a Module's call graph ------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the CallGraph class.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/CallGraph.h"
#include "llvm/Module.h"
#include "llvm/Instructions.h"
#include "llvm/Support/CallSite.h"
#include "llvm/ADT/STLExtras.h"
#include <iostream>
using namespace llvm;
static RegisterAnalysis<CallGraph> X("callgraph", "Call Graph Construction");
// getNodeFor - Return the node for the specified function or create one if it
// does not already exist.
//
CallGraphNode *CallGraph::getNodeFor(Function *F) {
CallGraphNode *&CGN = FunctionMap[F];
if (CGN) return CGN;
assert((!F || F->getParent() == Mod) && "Function not in current module!");
return CGN = new CallGraphNode(F);
}
static bool isOnlyADirectCall(Function *F, CallSite CS) {
if (!CS.getInstruction()) return false;
for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end(); I != E; ++I)
if (*I == F) return false;
return true;
}
// addToCallGraph - Add a function to the call graph, and link the node to all
// of the functions that it calls.
//
void CallGraph::addToCallGraph(Function *F) {
CallGraphNode *Node = getNodeFor(F);
// If this function has external linkage, anything could call it...
if (!F->hasInternalLinkage()) {
ExternalCallingNode->addCalledFunction(Node);
// Found the entry point?
if (F->getName() == "main") {
if (Root) // Found multiple external mains? Don't pick one.
Root = ExternalCallingNode;
else
Root = Node; // Found a main, keep track of it!
}
}
// If this function is not defined in this translation unit, it could call
// anything.
if (F->isExternal() && !F->getIntrinsicID())
Node->addCalledFunction(CallsExternalNode);
// Loop over all of the users of the function... looking for callers...
//
bool isUsedExternally = false;
for (Value::use_iterator I = F->use_begin(), E = F->use_end(); I != E; ++I) {
if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
if (isOnlyADirectCall(F, CallSite::get(Inst)))
getNodeFor(Inst->getParent()->getParent())->addCalledFunction(Node);
else
isUsedExternally = true;
} else if (GlobalValue *GV = dyn_cast<GlobalValue>(*I)) {
for (Value::use_iterator I = GV->use_begin(), E = GV->use_end();
I != E; ++I)
if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
if (isOnlyADirectCall(F, CallSite::get(Inst)))
getNodeFor(Inst->getParent()->getParent())->addCalledFunction(Node);
else
isUsedExternally = true;
} else {
isUsedExternally = true;
}
} else { // Can't classify the user!
isUsedExternally = true;
}
}
if (isUsedExternally)
ExternalCallingNode->addCalledFunction(Node);
// Look for an indirect function call...
for (Function::iterator BB = F->begin(), BBE = F->end(); BB != BBE; ++BB)
for (BasicBlock::iterator II = BB->begin(), IE = BB->end(); II != IE; ++II){
CallSite CS = CallSite::get(II);
if (CS.getInstruction() && !CS.getCalledFunction())
Node->addCalledFunction(CallsExternalNode);
}
}
bool CallGraph::runOnModule(Module &M) {
destroy();
Mod = &M;
ExternalCallingNode = getNodeFor(0);
CallsExternalNode = new CallGraphNode(0);
Root = 0;
// Add every function to the call graph...
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
addToCallGraph(I);
// If we didn't find a main function, use the external call graph node
if (Root == 0) Root = ExternalCallingNode;
return false;
}
void CallGraph::destroy() {
for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end();
I != E; ++I)
delete I->second;
FunctionMap.clear();
delete CallsExternalNode;
CallsExternalNode = 0;
}
void CallGraphNode::print(std::ostream &OS) const {
if (Function *F = getFunction())
OS << "Call graph node for function: '" << F->getName() <<"'\n";
else
OS << "Call graph node <<null function: 0x" << this << ">>:\n";
for (const_iterator I = begin(), E = end(); I != E; ++I)
if ((*I)->getFunction())
OS << " Calls function '" << (*I)->getFunction()->getName() << "'\n";
else
OS << " Calls external node\n";
OS << "\n";
}
void CallGraphNode::dump() const { print(std::cerr); }
void CallGraph::print(std::ostream &OS, const Module *M) const {
OS << "CallGraph Root is: ";
if (Function *F = getRoot()->getFunction())
OS << F->getName() << "\n";
else
OS << "<<null function: 0x" << getRoot() << ">>\n";
for (CallGraph::const_iterator I = begin(), E = end(); I != E; ++I)
I->second->print(OS);
}
void CallGraph::dump() const {
print(std::cerr, 0);
}
//===----------------------------------------------------------------------===//
// Implementations of public modification methods
//
// removeFunctionFromModule - Unlink the function from this module, returning
// it. Because this removes the function from the module, the call graph node
// is destroyed. This is only valid if the function does not call any other
// functions (ie, there are no edges in it's CGN). The easiest way to do this
// is to dropAllReferences before calling this.
//
Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) {
assert(CGN->CalledFunctions.empty() && "Cannot remove function from call "
"graph if it references other functions!");
Function *F = CGN->getFunction(); // Get the function for the call graph node
delete CGN; // Delete the call graph node for this func
FunctionMap.erase(F); // Remove the call graph node from the map
Mod->getFunctionList().remove(F);
return F;
}
// changeFunction - This method changes the function associated with this
// CallGraphNode, for use by transformations that need to change the prototype
// of a Function (thus they must create a new Function and move the old code
// over).
void CallGraph::changeFunction(Function *OldF, Function *NewF) {
iterator I = FunctionMap.find(OldF);
CallGraphNode *&New = FunctionMap[NewF];
assert(I != FunctionMap.end() && I->second && !New &&
"OldF didn't exist in CG or NewF already does!");
New = I->second;
New->F = NewF;
FunctionMap.erase(I);
}
void CallGraph::stub() {}
void CallGraphNode::removeCallEdgeTo(CallGraphNode *Callee) {
for (unsigned i = CalledFunctions.size(); ; --i) {
assert(i && "Cannot find callee to remove!");
if (CalledFunctions[i-1] == Callee) {
CalledFunctions.erase(CalledFunctions.begin()+i-1);
return;
}
}
}
// removeAnyCallEdgeTo - This method removes any call edges from this node to
// the specified callee function. This takes more time to execute than
// removeCallEdgeTo, so it should not be used unless necessary.
void CallGraphNode::removeAnyCallEdgeTo(CallGraphNode *Callee) {
for (unsigned i = 0, e = CalledFunctions.size(); i != e; ++i)
if (CalledFunctions[i] == Callee) {
CalledFunctions[i] = CalledFunctions.back();
CalledFunctions.pop_back();
--i; --e;
}
}
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