//===- 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 method in a module is represented as a node in the call graph. The
-// callgraph node keeps track of which methods the are called by the method
-// corresponding to the node.
-//
-// A call graph will contain nodes where the method 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 methods with the following properties:
-// 1. All methods in the module without internal linkage, since they could
-// be called by methods outside of the our analysis capability.
-// 2. All methods 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, methods have a call edge to the external node iff:
-// 1. The method is external, reflecting the fact that they could call
-// anything without internal linkage or that has its address taken.
-// 2. The method contains an indirect method call.
-//
-// As an extension in the future, there may be multiple nodes with a null
-// method. These will be used when we can prove (through pointer analysis) that
-// an indirect call site can call only a specific set of methods.
-//
-// 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 method named 'main'.
-// If no method named 'main' is found, the external node is used as the entry
-// node, reflecting the fact that any method 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/Function.h"
-#include "llvm/BasicBlock.h"
#include "llvm/iOther.h"
#include "llvm/iTerminators.h"
+#include "llvm/Support/CallSite.h"
#include "Support/STLExtras.h"
-#include <algorithm>
-#include <iostream>
+using namespace llvm;
-AnalysisID CallGraph::ID(AnalysisID::create<CallGraph>());
+static RegisterAnalysis<CallGraph> X("callgraph", "Call Graph Construction");
-// getNodeFor - Return the node for the specified method or create one if it
+// getNodeFor - Return the node for the specified function or create one if it
// does not already exist.
//
CallGraphNode *CallGraph::getNodeFor(Function *F) {
- CallGraphNode *&CGN = MethodMap[F];
+ CallGraphNode *&CGN = FunctionMap[F];
if (CGN) return CGN;
assert((!F || F->getParent() == Mod) && "Function not in current module!");
return CGN = new CallGraphNode(F);
}
-// addToCallGraph - Add a method to the call graph, and link the node to all of
-// the methods that it calls.
+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 *M) {
- CallGraphNode *Node = getNodeFor(M);
+void CallGraph::addToCallGraph(Function *F) {
+ CallGraphNode *Node = getNodeFor(F);
- // If this method has external linkage,
- if (!M->hasInternalLinkage()) {
- ExternalNode->addCalledMethod(Node);
+ // If this function has external linkage, anything could call it...
+ if (!F->hasInternalLinkage()) {
+ ExternalCallingNode->addCalledFunction(Node);
// Found the entry point?
- if (M->getName() == "main") {
- if (Root)
- Root = ExternalNode; // Found multiple external mains? Don't pick one.
+ 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!
}
- } else if (M->isExternal()) { // Not defined in this xlation unit?
- Node->addCalledMethod(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 method... looking for callers...
+ // Loop over all of the users of the function... looking for callers...
//
- for (Value::use_iterator I = M->use_begin(), E = M->use_end(); I != E; ++I) {
- User *U = *I;
- if (CallInst *CI = dyn_cast<CallInst>(U))
- getNodeFor(CI->getParent()->getParent())->addCalledMethod(Node);
- else if (InvokeInst *II = dyn_cast<InvokeInst>(U))
- getNodeFor(II->getParent()->getParent())->addCalledMethod(Node);
- else // Can't classify the user!
- ExternalNode->addCalledMethod(Node);
+ 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 (ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(*I)) {
+ // THIS IS A DISGUSTING HACK. Brought to you by the power of
+ // ConstantPointerRefs!
+ for (Value::use_iterator I = CPR->use_begin(), E = CPR->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 method call...
- for (Function::iterator BBI = M->begin(), BBE = M->end(); BBI != BBE; ++BBI) {
- BasicBlock *BB = *BBI;
+ // 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->addCalledMethod(ExternalNode);
- } else if (InvokeInst *II = dyn_cast<InvokeInst>(I)) {
- if (II->getCalledFunction() == 0)
- Node->addCalledMethod(ExternalNode);
- }
+ CallSite CS = CallSite::get(II);
+ if (CS.getInstruction() && !CS.getCalledFunction())
+ Node->addCalledFunction(CallsExternalNode);
}
- }
}
-bool CallGraph::run(Module *TheModule) {
+bool CallGraph::run(Module &M) {
destroy();
- Mod = TheModule;
- ExternalNode = getNodeFor(0);
+ Mod = &M;
+ ExternalCallingNode = getNodeFor(0);
+ CallsExternalNode = new CallGraphNode(0);
Root = 0;
- // Add every method to the call graph...
- for_each(Mod->begin(), Mod->end(), bind_obj(this,&CallGraph::addToCallGraph));
+ // 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 method, use the external call graph node
- if (Root == 0) Root = ExternalNode;
+ // 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 (MethodMapTy::iterator I = MethodMap.begin(), E = MethodMap.end();
+ for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end();
I != E; ++I)
delete I->second;
- MethodMap.clear();
+ FunctionMap.clear();
+ delete CallsExternalNode;
+ CallsExternalNode = 0;
}
-
-void WriteToOutput(const CallGraphNode *CGN, std::ostream &o) {
- if (CGN->getMethod())
- o << "Call graph node for method: '" << CGN->getMethod()->getName() <<"'\n";
+static void WriteToOutput(const CallGraphNode *CGN, std::ostream &o) {
+ if (CGN->getFunction())
+ o << "Call graph node for function: '"
+ << CGN->getFunction()->getName() <<"'\n";
else
- o << "Call graph node null method:\n";
+ o << "Call graph node <<null function: 0x" << CGN << ">>:\n";
for (unsigned i = 0; i < CGN->size(); ++i)
- if ((*CGN)[i]->getMethod())
- o << " Calls method '" << (*CGN)[i]->getMethod()->getName() << "'\n";
+ if ((*CGN)[i]->getFunction())
+ o << " Calls function '" << (*CGN)[i]->getFunction()->getName() << "'\n";
else
o << " Calls external node\n";
o << "\n";
}
-void WriteToOutput(const CallGraph &CG, std::ostream &o) {
- for (CallGraph::const_iterator I = CG.begin(), E = CG.end(); I != E; ++I)
- o << I->second;
+void CallGraph::print(std::ostream &o, const Module *M) const {
+ o << "CallGraph Root is: ";
+ if (getRoot()->getFunction())
+ o << getRoot()->getFunction()->getName() << "\n";
+ else
+ o << "<<null function: 0x" << getRoot() << ">>\n";
+
+ for (CallGraph::const_iterator I = begin(), E = end(); I != E; ++I)
+ WriteToOutput(I->second, o);
}
// Implementations of public modification methods
//
-// Methods to keep a call graph up to date with a method that has been
+// Functions to keep a call graph up to date with a function that has been
// modified
//
-void CallGraph::addMethodToModule(Function *Meth) {
+void CallGraph::addFunctionToModule(Function *F) {
assert(0 && "not implemented");
abort();
}
-// removeMethodFromModule - Unlink the method from this module, returning it.
-// Because this removes the method from the module, the call graph node is
-// destroyed. This is only valid if the method does not call any other
-// methods (ie, there are no edges in it's CGN). The easiest way to do this
+// 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::removeMethodFromModule(CallGraphNode *CGN) {
- assert(CGN->CalledMethods.empty() && "Cannot remove method from call graph"
- " if it references other methods!");
- Function *M = CGN->getMethod(); // Get the function for the call graph node
- delete CGN; // Delete the call graph node for this func
- MethodMap.erase(M); // Remove the call graph node from the map
-
- Mod->getFunctionList().remove(M);
- return M;
+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;
}
+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;
+ }
+ }
+}