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//===- 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.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/CallGraph.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Config/llvm-config.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/PassManager.h"
#include "llvm/Pass.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
using namespace llvm;
//===----------------------------------------------------------------------===//
// Implementations of the CallGraph class methods.
//
CallGraph::CallGraph(Module &M)
: M(M), ExternalCallingNode(getOrInsertFunction(nullptr)),
CallsExternalNode(llvm::make_unique<CallGraphNode>(nullptr)) {
// Add every function to the call graph.
for (Function &F : M)
addToCallGraph(&F);
}
CallGraph::CallGraph(CallGraph &&Arg)
: M(Arg.M), FunctionMap(std::move(Arg.FunctionMap)),
ExternalCallingNode(Arg.ExternalCallingNode),
CallsExternalNode(std::move(Arg.CallsExternalNode)) {
Arg.FunctionMap.clear();
Arg.ExternalCallingNode = nullptr;
}
CallGraph::~CallGraph() {
// CallsExternalNode is not in the function map, delete it explicitly.
if (CallsExternalNode)
CallsExternalNode->allReferencesDropped();
// Reset all node's use counts to zero before deleting them to prevent an
// assertion from firing.
#ifndef NDEBUG
for (auto &I : FunctionMap)
I.second->allReferencesDropped();
#endif
}
void CallGraph::addToCallGraph(Function *F) {
CallGraphNode *Node = getOrInsertFunction(F);
// If this function has external linkage or has its address taken, anything
// could call it.
if (!F->hasLocalLinkage() || 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.get());
// Look for calls by this function.
for (BasicBlock &BB : *F)
for (Instruction &I : BB) {
if (auto CS = CallSite(&I)) {
const Function *Callee = CS.getCalledFunction();
if (!Callee || !Intrinsic::isLeaf(Callee->getIntrinsicID()))
// Indirect calls of intrinsics are not allowed so no need to check.
// We can be more precise here by using TargetArg returned by
// Intrinsic::isLeaf.
Node->addCalledFunction(CS, CallsExternalNode.get());
else if (!Callee->isIntrinsic())
Node->addCalledFunction(CS, getOrInsertFunction(Callee));
}
}
}
void CallGraph::print(raw_ostream &OS) const {
// Print in a deterministic order by sorting CallGraphNodes by name. We do
// this here to avoid slowing down the non-printing fast path.
SmallVector<CallGraphNode *, 16> Nodes;
Nodes.reserve(FunctionMap.size());
for (const auto &I : *this)
Nodes.push_back(I.second.get());
llvm::sort(Nodes.begin(), Nodes.end(),
[](CallGraphNode *LHS, CallGraphNode *RHS) {
if (Function *LF = LHS->getFunction())
if (Function *RF = RHS->getFunction())
return LF->getName() < RF->getName();
return RHS->getFunction() != nullptr;
});
for (CallGraphNode *CN : Nodes)
CN->print(OS);
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
LLVM_DUMP_METHOD void CallGraph::dump() const { print(dbgs()); }
#endif
// 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
FunctionMap.erase(F); // Remove the call graph node from the map
M.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] = std::move(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) {
auto &CGN = FunctionMap[F];
if (CGN)
return CGN.get();
assert((!F || F->getParent() == &M) && "Function not in current module!");
CGN = llvm::make_unique<CallGraphNode>(const_cast<Function *>(F));
return CGN.get();
}
//===----------------------------------------------------------------------===//
// Implementations of the CallGraphNode class methods.
//
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 auto &I : *this) {
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)
LLVM_DUMP_METHOD 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 == nullptr) {
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;
}
}
}
// Provide an explicit template instantiation for the static ID.
AnalysisKey CallGraphAnalysis::Key;
PreservedAnalyses CallGraphPrinterPass::run(Module &M,
ModuleAnalysisManager &AM) {
AM.getResult<CallGraphAnalysis>(M).print(OS);
return PreservedAnalyses::all();
}
//===----------------------------------------------------------------------===//
// Out-of-line definitions of CallGraphAnalysis class members.
//
//===----------------------------------------------------------------------===//
// Implementations of the CallGraphWrapperPass class methods.
//
CallGraphWrapperPass::CallGraphWrapperPass() : ModulePass(ID) {
initializeCallGraphWrapperPassPass(*PassRegistry::getPassRegistry());
}
CallGraphWrapperPass::~CallGraphWrapperPass() = default;
void CallGraphWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
}
bool CallGraphWrapperPass::runOnModule(Module &M) {
// All the real work is done in the constructor for the CallGraph.
G.reset(new CallGraph(M));
return false;
}
INITIALIZE_PASS(CallGraphWrapperPass, "basiccg", "CallGraph Construction",
false, true)
char CallGraphWrapperPass::ID = 0;
void CallGraphWrapperPass::releaseMemory() { G.reset(); }
void CallGraphWrapperPass::print(raw_ostream &OS, const Module *) const {
if (!G) {
OS << "No call graph has been built!\n";
return;
}
// Just delegate.
G->print(OS);
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
LLVM_DUMP_METHOD
void CallGraphWrapperPass::dump() const { print(dbgs(), nullptr); }
#endif
namespace {
struct CallGraphPrinterLegacyPass : public ModulePass {
static char ID; // Pass ID, replacement for typeid
CallGraphPrinterLegacyPass() : ModulePass(ID) {
initializeCallGraphPrinterLegacyPassPass(*PassRegistry::getPassRegistry());
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesAll();
AU.addRequiredTransitive<CallGraphWrapperPass>();
}
bool runOnModule(Module &M) override {
getAnalysis<CallGraphWrapperPass>().print(errs(), &M);
return false;
}
};
} // end anonymous namespace
char CallGraphPrinterLegacyPass::ID = 0;
INITIALIZE_PASS_BEGIN(CallGraphPrinterLegacyPass, "print-callgraph",
"Print a call graph", true, true)
INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass)
INITIALIZE_PASS_END(CallGraphPrinterLegacyPass, "print-callgraph",
"Print a call graph", true, true)