//===- CallGraph.cpp - Build a Module's call graph ------------------------===//
+//
+// The LLVM Compiler Infrastructure
//
-// This interface is used to build and manipulate a call graph, which is a very
-// useful tool for interprocedural optimization.
-//
-// Every function in a module is represented as a node in the call graph. The
-// callgraph node keeps track of which functions the are called by the function
-// corresponding to the node.
-//
-// A call graph will contain nodes where the function that they correspond to is
-// null. This 'external' node is used to represent control flow that is not
-// represented (or analyzable) in the module. As such, the external node will
-// have edges to functions with the following properties:
-// 1. All functions in the module without internal linkage, since they could
-// be called by functions outside of the our analysis capability.
-// 2. All functions whose address is used for something more than a direct
-// call, for example being stored into a memory location. Since they may
-// be called by an unknown caller later, they must be tracked as such.
-//
-// Similarly, functions have a call edge to the external node iff:
-// 1. The function is external, reflecting the fact that they could call
-// anything without internal linkage or that has its address taken.
-// 2. The function contains an indirect function call.
-//
-// As an extension in the future, there may be multiple nodes with a null
-// function. These will be used when we can prove (through pointer analysis)
-// that an indirect call site can call only a specific set of functions.
-//
-// Because of these properties, the CallGraph captures a conservative superset
-// of all of the caller-callee relationships, which is useful for
-// transformations.
+// 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.
+//
+//===----------------------------------------------------------------------===//
//
-// The CallGraph class also attempts to figure out what the root of the
-// CallGraph is, which is currently does by looking for a function named 'main'.
-// If no function named 'main' is found, the external node is used as the entry
-// node, reflecting the fact that any function without internal linkage could
-// be called into (which is common for libraries).
+// This file implements the CallGraph class.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/CallGraph.h"
+#include "llvm/Constants.h" // Remove when ConstantPointerRefs are gone
#include "llvm/Module.h"
-#include "llvm/iOther.h"
-#include "llvm/iTerminators.h"
+#include "llvm/Instructions.h"
+#include "llvm/Support/CallSite.h"
#include "Support/STLExtras.h"
-#include <algorithm>
+#include <iostream>
+using namespace llvm;
static RegisterAnalysis<CallGraph> X("callgraph", "Call Graph Construction");
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,
+ // If this function has external linkage, anything could call it...
if (!F->hasInternalLinkage()) {
- ExternalNode->addCalledFunction(Node);
+ ExternalCallingNode->addCalledFunction(Node);
// Found the entry point?
if (F->getName() == "main") {
- if (Root)
- Root = ExternalNode; // Found multiple external mains? Don't pick one.
+ if (Root) // Found multiple external mains? Don't pick one.
+ Root = ExternalCallingNode;
else
Root = Node; // Found a main, keep track of it!
}
- } else if (F->isExternal()) { // Not defined in this xlation unit?
- Node->addCalledFunction(ExternalNode); // It could call anything...
}
+
+ // 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) {
- User *U = *I;
- if (CallInst *CI = dyn_cast<CallInst>(U))
- getNodeFor(CI->getParent()->getParent())->addCalledFunction(Node);
- else if (InvokeInst *II = dyn_cast<InvokeInst>(U))
- getNodeFor(II->getParent()->getParent())->addCalledFunction(Node);
- else // Can't classify the user!
- ExternalNode->addCalledFunction(Node);
+ 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){
- Instruction &I = *II;
-
- if (CallInst *CI = dyn_cast<CallInst>(&I)) {
- if (CI->getCalledFunction() == 0)
- Node->addCalledFunction(ExternalNode);
- } else if (InvokeInst *II = dyn_cast<InvokeInst>(&I)) {
- if (II->getCalledFunction() == 0)
- Node->addCalledFunction(ExternalNode);
- }
+ CallSite CS = CallSite::get(II);
+ if (CS.getInstruction() && !CS.getCalledFunction())
+ Node->addCalledFunction(CallsExternalNode);
}
}
destroy();
Mod = &M;
- ExternalNode = getNodeFor(0);
+ ExternalCallingNode = getNodeFor(0);
+ CallsExternalNode = new CallGraphNode(0);
Root = 0;
// Add every function to the call graph...
addToCallGraph(I);
// If we didn't find a main function, use the external call graph node
- if (Root == 0) Root = ExternalNode;
+ if (Root == 0) Root = ExternalCallingNode;
return false;
}
I != E; ++I)
delete I->second;
FunctionMap.clear();
+ delete CallsExternalNode;
+ CallsExternalNode = 0;
}
-static void WriteToOutput(const CallGraphNode *CGN, std::ostream &o) {
- if (CGN->getFunction())
- o << "Call graph node for function: '"
- << CGN->getFunction()->getName() <<"'\n";
+void CallGraphNode::print(std::ostream &OS) const {
+ if (Function *F = getFunction())
+ OS << "Call graph node for function: '" << F->getName() <<"'\n";
else
- o << "Call graph node null function:\n";
+ OS << "Call graph node <<null function: 0x" << this << ">>:\n";
- for (unsigned i = 0; i < CGN->size(); ++i)
- if ((*CGN)[i]->getFunction())
- o << " Calls function '" << (*CGN)[i]->getFunction()->getName() << "'\n";
+ for (const_iterator I = begin(), E = end(); I != E; ++I)
+ if ((*I)->getFunction())
+ OS << " Calls function '" << (*I)->getFunction()->getName() << "'\n";
else
- o << " Calls external node\n";
- o << "\n";
+ OS << " Calls external node\n";
+ OS << "\n";
}
-void CallGraph::print(std::ostream &o, const Module *M) const {
- o << "CallGraph Root is:\n" << getRoot();
+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)
- WriteToOutput(I->second, o);
+ I->second->print(OS);
+}
+
+void CallGraph::dump() const {
+ print(std::cerr, 0);
}
// Functions to keep a call graph up to date with a function that has been
// modified
//
-void CallGraph::addFunctionToModule(Function *Meth) {
+void CallGraph::addFunctionToModule(Function *F) {
assert(0 && "not implemented");
abort();
}
return F;
}
+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;
+ }
+ }
+}
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