//===- CallGraph.cpp - Build a Module's call graph ------------------------===//
//
-// This interface is used to build and manipulate a call graph, which is a very
-// useful tool for interprocedural optimization.
+// The LLVM Compiler Infrastructure
//
-// 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.
-//
-// 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 is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/CallGraph.h"
-#include "llvm/Module.h"
-#include "llvm/Method.h"
-#include "llvm/iOther.h"
-#include "llvm/iTerminators.h"
-#include "Support/STLExtras.h"
-#include <algorithm>
-#include <iostream>
-
-AnalysisID CallGraph::ID(AnalysisID::create<CallGraph>());
-
-// getNodeFor - Return the node for the specified method or create one if it
-// does not already exist.
-//
-CallGraphNode *CallGraph::getNodeFor(Method *M) {
- CallGraphNode *&CGN = MethodMap[M];
- if (CGN) return CGN;
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Support/CallSite.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
- assert((!M || M->getParent() == Mod) && "Method not in current module!");
- return CGN = new CallGraphNode(M);
+CallGraph::CallGraph()
+ : ModulePass(ID), Root(0), ExternalCallingNode(0), CallsExternalNode(0) {
+ initializeCallGraphPass(*PassRegistry::getPassRegistry());
}
-// addToCallGraph - Add a method to the call graph, and link the node to all of
-// the methods that it calls.
-//
-void CallGraph::addToCallGraph(Method *M) {
- CallGraphNode *Node = getNodeFor(M);
+void CallGraph::addToCallGraph(Function *F) {
+ CallGraphNode *Node = getOrInsertFunction(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->hasLocalLinkage()) {
+ ExternalCallingNode->addCalledFunction(CallSite(), 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!
+ 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...
}
- // Loop over all of the users of the method... 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);
- }
+ // If this function has its address taken, anything could call it.
+ if (F->hasAddressTaken())
+ ExternalCallingNode->addCalledFunction(CallSite(), Node);
+
+ // If this function is not defined in this translation unit, it could call
+ // anything.
+ if (F->isDeclaration() && !F->isIntrinsic())
+ Node->addCalledFunction(CallSite(), CallsExternalNode);
- // Look for an indirect method call...
- for (Method::iterator BBI = M->begin(), BBE = M->end(); BBI != BBE; ++BBI) {
- BasicBlock *BB = *BBI;
- for (BasicBlock::iterator II = BB->begin(), IE = BB->end(); II != IE; ++II){
- Instruction *I = *II;
-
- if (CallInst *CI = dyn_cast<CallInst>(I)) {
- if (CI->getCalledMethod() == 0)
- Node->addCalledMethod(ExternalNode);
- } else if (InvokeInst *II = dyn_cast<InvokeInst>(I)) {
- if (II->getCalledMethod() == 0)
- Node->addCalledMethod(ExternalNode);
+ // Look for calls by this function.
+ 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(cast<Value>(II));
+ if (CS) {
+ const Function *Callee = CS.getCalledFunction();
+ if (!Callee)
+ // Indirect calls of intrinsics are not allowed so no need to check.
+ Node->addCalledFunction(CS, CallsExternalNode);
+ else if (!Callee->isIntrinsic())
+ Node->addCalledFunction(CS, getOrInsertFunction(Callee));
}
}
- }
}
-bool CallGraph::run(Module *TheModule) {
- destroy();
+void CallGraph::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesAll();
+}
- Mod = TheModule;
- ExternalNode = getNodeFor(0);
+bool CallGraph::runOnModule(Module &M) {
+ Mod = &M;
+
+ ExternalCallingNode = getOrInsertFunction(0);
+ assert(!CallsExternalNode);
+ 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 function, use the external call graph node
+ if (Root == 0)
+ Root = ExternalCallingNode;
- // If we didn't find a main method, use the external call graph node
- if (Root == 0) Root = ExternalNode;
-
return false;
}
-void CallGraph::destroy() {
- for (MethodMapTy::iterator I = MethodMap.begin(), E = MethodMap.end();
+INITIALIZE_PASS(CallGraph, "basiccg", "CallGraph Construction", false, true)
+
+char CallGraph::ID = 0;
+
+void CallGraph::releaseMemory() {
+ /// CallsExternalNode is not in the function map, delete it explicitly.
+ if (CallsExternalNode) {
+ CallsExternalNode->allReferencesDropped();
+ delete CallsExternalNode;
+ CallsExternalNode = 0;
+ }
+
+ if (FunctionMap.empty())
+ return;
+
+// Reset all node's use counts to zero before deleting them to prevent an
+// assertion from firing.
+#ifndef NDEBUG
+ for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end();
I != E; ++I)
+ I->second->allReferencesDropped();
+#endif
+
+ for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end();
+ I != E; ++I)
delete I->second;
- MethodMap.clear();
+ FunctionMap.clear();
}
+void CallGraph::print(raw_ostream &OS, const Module*) const {
+ OS << "CallGraph Root is: ";
+ if (Function *F = Root->getFunction())
+ OS << F->getName() << "\n";
+ else {
+ OS << "<<null function: 0x" << Root << ">>\n";
+ }
-void WriteToOutput(const CallGraphNode *CGN, std::ostream &o) {
- if (CGN->getMethod())
- o << "Call graph node for method: '" << CGN->getMethod()->getName() <<"'\n";
- else
- o << "Call graph node null method:\n";
-
- for (unsigned i = 0; i < CGN->size(); ++i)
- if ((*CGN)[i]->getMethod())
- o << " Calls method '" << (*CGN)[i]->getMethod()->getName() << "'\n";
- else
- o << " Calls external node\n";
- o << "\n";
+ for (CallGraph::const_iterator I = begin(), E = end(); I != E; ++I)
+ I->second->print(OS);
}
-
-void WriteToOutput(const CallGraph &CG, std::ostream &o) {
- for (CallGraph::const_iterator I = CG.begin(), E = CG.end(); I != E; ++I)
- o << I->second;
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+void CallGraph::dump() const {
+ print(dbgs(), 0);
}
-
+#endif
//===----------------------------------------------------------------------===//
// Implementations of public modification methods
//
-// Methods to keep a call graph up to date with a method that has been
-// modified
+// 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.
//
-void CallGraph::addMethodToModule(Method *Meth) {
- assert(0 && "not implemented");
- abort();
+Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) {
+ assert(CGN->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;
}
-// 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
-// is to dropAllReferences before calling this.
-//
-Method *CallGraph::removeMethodFromModule(CallGraphNode *CGN) {
- assert(CGN->CalledMethods.empty() && "Cannot remove method from call graph"
- " if it references other methods!");
- Method *M = CGN->getMethod(); // Get the method for the call graph node
- delete CGN; // Delete the call graph node for this method
- MethodMap.erase(M); // Remove the call graph node from the map
-
- Mod->getMethodList().remove(M);
- return M;
+/// spliceFunction - Replace the function represented by this node by another.
+/// This does not rescan the body of the function, so it is suitable when
+/// splicing the body of the old function to the new while also updating all
+/// callers from old to new.
+///
+void CallGraph::spliceFunction(const Function *From, const Function *To) {
+ assert(FunctionMap.count(From) && "No CallGraphNode for function!");
+ assert(!FunctionMap.count(To) &&
+ "Pointing CallGraphNode at a function that already exists");
+ FunctionMapTy::iterator I = FunctionMap.find(From);
+ I->second->F = const_cast<Function*>(To);
+ FunctionMap[To] = I->second;
+ 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(raw_ostream &OS) const {
+ if (Function *F = getFunction())
+ OS << "Call graph node for function: '" << F->getName() << "'";
+ else
+ OS << "Call graph node <<null function>>";
+
+ OS << "<<" << this << ">> #uses=" << getNumReferences() << '\n';
+
+ for (const_iterator I = begin(), E = end(); I != E; ++I) {
+ OS << " CS<" << I->first << "> calls ";
+ if (Function *FI = I->second->getFunction())
+ OS << "function '" << FI->getName() <<"'\n";
+ else
+ OS << "external node\n";
+ }
+ OS << '\n';
+}
+
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+void CallGraphNode::dump() const { print(dbgs()); }
+#endif
+
+/// removeCallEdgeFor - This method removes the edge in the node for the
+/// specified call site. Note that this method takes linear time, so it
+/// should be used sparingly.
+void CallGraphNode::removeCallEdgeFor(CallSite CS) {
+ for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
+ assert(I != CalledFunctions.end() && "Cannot find callsite to remove!");
+ if (I->first == CS.getInstruction()) {
+ I->second->DropRef();
+ *I = CalledFunctions.back();
+ CalledFunctions.pop_back();
+ 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) {
+ Callee->DropRef();
+ CalledFunctions[i] = CalledFunctions.back();
+ CalledFunctions.pop_back();
+ --i; --e;
+ }
+}
+
+/// removeOneAbstractEdgeTo - Remove one edge associated with a null callsite
+/// from this node to the specified callee function.
+void CallGraphNode::removeOneAbstractEdgeTo(CallGraphNode *Callee) {
+ for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
+ assert(I != CalledFunctions.end() && "Cannot find callee to remove!");
+ CallRecord &CR = *I;
+ if (CR.second == Callee && CR.first == 0) {
+ Callee->DropRef();
+ *I = CalledFunctions.back();
+ CalledFunctions.pop_back();
+ return;
+ }
+ }
+}
+
+/// replaceCallEdge - This method replaces the edge in the node for the
+/// specified call site with a new one. Note that this method takes linear
+/// time, so it should be used sparingly.
+void CallGraphNode::replaceCallEdge(CallSite CS,
+ CallSite NewCS, CallGraphNode *NewNode){
+ for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
+ assert(I != CalledFunctions.end() && "Cannot find callsite to remove!");
+ if (I->first == CS.getInstruction()) {
+ I->second->DropRef();
+ I->first = NewCS.getInstruction();
+ I->second = NewNode;
+ NewNode->AddRef();
+ return;
+ }
+ }
}
+// Enuse that users of CallGraph.h also link with this file
+DEFINING_FILE_FOR(CallGraph)
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