llvm-6502/lib/Analysis/IPA/CallGraph.cpp
2011-06-09 19:46:27 +00:00

341 lines
12 KiB
C++

//===- CallGraph.cpp - Build a Module's call graph ------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file 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/IntrinsicInst.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
namespace {
//===----------------------------------------------------------------------===//
// BasicCallGraph class definition
//
class BasicCallGraph : public ModulePass, public CallGraph {
// 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 char ID; // Class identification, replacement for typeinfo
BasicCallGraph() : ModulePass(ID), Root(0),
ExternalCallingNode(0), CallsExternalNode(0) {
initializeBasicCallGraphPass(*PassRegistry::getPassRegistry());
}
// 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();
}
virtual void print(raw_ostream &OS, const Module *) const {
OS << "CallGraph Root is: ";
if (Function *F = getRoot()->getFunction())
OS << F->getName() << "\n";
else {
OS << "<<null function: 0x" << getRoot() << ">>\n";
}
CallGraph::print(OS, 0);
}
virtual void releaseMemory() {
destroy();
}
/// getAdjustedAnalysisPointer - This method is used when a pass implements
/// an analysis interface through multiple inheritance. If needed, it should
/// override this to adjust the this pointer as needed for the specified pass
/// info.
virtual void *getAdjustedAnalysisPointer(AnalysisID PI) {
if (PI == &CallGraph::ID)
return (CallGraph*)this;
return this;
}
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->hasLocalLinkage()) {
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!
}
}
// Loop over all of the users of the function, looking for non-call uses.
for (Value::use_iterator I = F->use_begin(), E = F->use_end(); I != E; ++I){
User *U = *I;
if ((!isa<CallInst>(U) && !isa<InvokeInst>(U))
|| !CallSite(cast<Instruction>(U)).isCallee(I)) {
// Not a call, or being used as a parameter rather than as the callee.
ExternalCallingNode->addCalledFunction(CallSite(), Node);
break;
}
}
// 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 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 && !isa<IntrinsicInst>(II)) {
const Function *Callee = CS.getCalledFunction();
if (Callee)
Node->addCalledFunction(CS, getOrInsertFunction(Callee));
else
Node->addCalledFunction(CS, CallsExternalNode);
}
}
}
//
// destroy - Release memory for the call graph
virtual void destroy() {
/// CallsExternalNode is not in the function map, delete it explicitly.
if (CallsExternalNode) {
CallsExternalNode->allReferencesDropped();
delete CallsExternalNode;
CallsExternalNode = 0;
}
CallGraph::destroy();
}
};
} //End anonymous namespace
INITIALIZE_ANALYSIS_GROUP(CallGraph, "Call Graph", BasicCallGraph)
INITIALIZE_AG_PASS(BasicCallGraph, CallGraph, "basiccg",
"Basic CallGraph Construction", false, true, true)
char CallGraph::ID = 0;
char BasicCallGraph::ID = 0;
void CallGraph::initialize(Module &M) {
Mod = &M;
}
void CallGraph::destroy() {
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;
FunctionMap.clear();
}
void CallGraph::print(raw_ostream &OS, Module*) const {
for (CallGraph::const_iterator I = begin(), E = end(); I != E; ++I)
I->second->print(OS);
}
void CallGraph::dump() const {
print(dbgs(), 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->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;
}
/// 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';
}
void CallGraphNode::dump() const { print(dbgs()); }
/// 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)