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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 and provides the BasicCallGraph
// default implementation.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/CallGraph.h"
#include "llvm/Module.h"
#include "llvm/Instructions.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Streams.h"
#include <ostream>
using namespace llvm;
/// isOnlyADirectCall - Return true if this callsite is *just* a direct call to
/// the specified function. Specifically return false if the callsite also
/// takes the address of the function.
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;
}
namespace {
//===----------------------------------------------------------------------===//
// BasicCallGraph class definition
//
class VISIBILITY_HIDDEN BasicCallGraph : public CallGraph, public ModulePass {
// Root is root of the call graph, or the external node if a 'main' function
// couldn't be found.
//
CallGraphNode *Root;
// ExternalCallingNode - This node has edges to all external functions and
// those internal functions that have their address taken.
CallGraphNode *ExternalCallingNode;
// CallsExternalNode - This node has edges to it from all functions making
// indirect calls or calling an external function.
CallGraphNode *CallsExternalNode;
public:
static const char ID; // Class identification, replacement for typeinfo
BasicCallGraph() : ModulePass((intptr_t)&ID), Root(0),
ExternalCallingNode(0), CallsExternalNode(0) {}
// runOnModule - Compute the call graph for the specified module.
virtual bool runOnModule(Module &M) {
CallGraph::initialize(M);
ExternalCallingNode = getOrInsertFunction(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;
}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
}
void print(std::ostream *o, const Module *M) const {
if (o) print(*o, M);
}
virtual void print(std::ostream &o, const Module *M) const {
o << "CallGraph Root is: ";
if (Function *F = getRoot()->getFunction())
o << F->getName() << "\n";
else
o << "<<null function: 0x" << getRoot() << ">>\n";
CallGraph::print(o, M);
}
virtual void releaseMemory() {
destroy();
}
/// dump - Print out this call graph.
///
inline void dump() const {
print(cerr, Mod);
}
CallGraphNode* getExternalCallingNode() const { return ExternalCallingNode; }
CallGraphNode* getCallsExternalNode() const { return CallsExternalNode; }
// getRoot - Return the root of the call graph, which is either main, or if
// main cannot be found, the external node.
//
CallGraphNode *getRoot() { return Root; }
const CallGraphNode *getRoot() const { return Root; }
private:
//===---------------------------------------------------------------------
// Implementation of CallGraph construction
//
// addToCallGraph - Add a function to the call graph, and link the node to all
// of the functions that it calls.
//
void addToCallGraph(Function *F) {
CallGraphNode *Node = getOrInsertFunction(F);
// If this function has external linkage, anything could call it.
if (!F->hasInternalLinkage()) {
ExternalCallingNode->addCalledFunction(CallSite(), 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->isDeclaration() && !F->getIntrinsicID())
Node->addCalledFunction(CallSite(), 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)) {
CallSite CS = CallSite::get(Inst);
if (isOnlyADirectCall(F, CS))
getOrInsertFunction(Inst->getParent()->getParent())
->addCalledFunction(CS, 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)) {
CallSite CS = CallSite::get(Inst);
if (isOnlyADirectCall(F, CS))
getOrInsertFunction(Inst->getParent()->getParent())
->addCalledFunction(CS, Node);
else
isUsedExternally = true;
} else {
isUsedExternally = true;
}
} else { // Can't classify the user!
isUsedExternally = true;
}
}
if (isUsedExternally)
ExternalCallingNode->addCalledFunction(CallSite(), 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(CS, CallsExternalNode);
}
}
//
// destroy - Release memory for the call graph
virtual void destroy() {
/// CallsExternalNode is not in the function map, delete it explicitly.
delete CallsExternalNode;
CallsExternalNode = 0;
CallGraph::destroy();
}
};
RegisterAnalysisGroup<CallGraph> X("Call Graph");
RegisterPass<BasicCallGraph> Y("basiccg", "Basic CallGraph Construction");
RegisterAnalysisGroup<CallGraph, true> Z(Y);
} //End anonymous namespace
const char CallGraph::ID = 0;
const char BasicCallGraph::ID = 0;
void CallGraph::initialize(Module &M) {
Mod = &M;
}
void CallGraph::destroy() {
if (!FunctionMap.empty()) {
for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end();
I != E; ++I)
delete I->second;
FunctionMap.clear();
}
}
void CallGraph::print(std::ostream &OS, const Module *M) const {
for (CallGraph::const_iterator I = begin(), E = end(); I != E; ++I)
I->second->print(OS);
}
void CallGraph::dump() const {
print(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);
}
// getOrInsertFunction - This method is identical to calling operator[], but
// it will insert a new CallGraphNode for the specified function if one does
// not already exist.
CallGraphNode *CallGraph::getOrInsertFunction(const Function *F) {
CallGraphNode *&CGN = FunctionMap[F];
if (CGN) return CGN;
assert((!F || F->getParent() == Mod) && "Function not in current module!");
return CGN = new CallGraphNode(const_cast<Function*>(F));
}
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->second->getFunction())
OS << " Calls function '" << I->second->getFunction()->getName() <<"'\n";
else
OS << " Calls external node\n";
OS << "\n";
}
void CallGraphNode::dump() const { print(cerr); }
void CallGraphNode::removeCallEdgeTo(CallGraphNode *Callee) {
for (unsigned i = CalledFunctions.size(); ; --i) {
assert(i && "Cannot find callee to remove!");
if (CalledFunctions[i-1].second == 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].second == Callee) {
CalledFunctions[i] = CalledFunctions.back();
CalledFunctions.pop_back();
--i; --e;
}
}
// Enuse that users of CallGraph.h also link with this file
DEFINING_FILE_FOR(CallGraph)
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