318 lines
11 KiB
C++
318 lines
11 KiB
C++
//===- CallGraph.cpp - Build a Module's call graph ------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/CallGraph.h"
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#include "llvm/IR/CallSite.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/IntrinsicInst.h"
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#include "llvm/IR/Module.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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//===----------------------------------------------------------------------===//
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// Implementations of the CallGraph class methods.
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//
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CallGraph::CallGraph(Module &M)
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: M(M), ExternalCallingNode(getOrInsertFunction(nullptr)),
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CallsExternalNode(llvm::make_unique<CallGraphNode>(nullptr)) {
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// Add every function to the call graph.
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for (Function &F : M)
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addToCallGraph(&F);
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}
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CallGraph::CallGraph(CallGraph &&Arg)
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: M(Arg.M), FunctionMap(std::move(Arg.FunctionMap)),
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ExternalCallingNode(Arg.ExternalCallingNode),
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CallsExternalNode(std::move(Arg.CallsExternalNode)) {
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Arg.FunctionMap.clear();
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Arg.ExternalCallingNode = nullptr;
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}
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CallGraph::~CallGraph() {
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// CallsExternalNode is not in the function map, delete it explicitly.
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if (CallsExternalNode)
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CallsExternalNode->allReferencesDropped();
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// Reset all node's use counts to zero before deleting them to prevent an
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// assertion from firing.
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#ifndef NDEBUG
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for (auto &I : FunctionMap)
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I.second->allReferencesDropped();
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#endif
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}
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void CallGraph::addToCallGraph(Function *F) {
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CallGraphNode *Node = getOrInsertFunction(F);
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// If this function has external linkage or has its address taken, anything
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// could call it.
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if (!F->hasLocalLinkage() || F->hasAddressTaken())
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ExternalCallingNode->addCalledFunction(CallSite(), Node);
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// If this function is not defined in this translation unit, it could call
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// anything.
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if (F->isDeclaration() && !F->isIntrinsic())
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Node->addCalledFunction(CallSite(), CallsExternalNode.get());
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// Look for calls by this function.
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for (BasicBlock &BB : *F)
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for (Instruction &I : BB) {
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if (auto CS = CallSite(&I)) {
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const Function *Callee = CS.getCalledFunction();
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if (!Callee || !Intrinsic::isLeaf(Callee->getIntrinsicID()))
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// Indirect calls of intrinsics are not allowed so no need to check.
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// We can be more precise here by using TargetArg returned by
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// Intrinsic::isLeaf.
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Node->addCalledFunction(CS, CallsExternalNode.get());
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else if (!Callee->isIntrinsic())
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Node->addCalledFunction(CS, getOrInsertFunction(Callee));
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}
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}
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}
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void CallGraph::print(raw_ostream &OS) const {
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// Print in a deterministic order by sorting CallGraphNodes by name. We do
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// this here to avoid slowing down the non-printing fast path.
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SmallVector<CallGraphNode *, 16> Nodes;
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Nodes.reserve(FunctionMap.size());
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for (const auto &I : *this)
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Nodes.push_back(I.second.get());
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std::sort(Nodes.begin(), Nodes.end(),
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[](CallGraphNode *LHS, CallGraphNode *RHS) {
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if (Function *LF = LHS->getFunction())
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if (Function *RF = RHS->getFunction())
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return LF->getName() < RF->getName();
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return RHS->getFunction() != nullptr;
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});
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for (CallGraphNode *CN : Nodes)
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CN->print(OS);
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}
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#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
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LLVM_DUMP_METHOD void CallGraph::dump() const { print(dbgs()); }
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#endif
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// removeFunctionFromModule - Unlink the function from this module, returning
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// it. Because this removes the function from the module, the call graph node
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// is destroyed. This is only valid if the function does not call any other
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// functions (ie, there are no edges in it's CGN). The easiest way to do this
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// is to dropAllReferences before calling this.
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//
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Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) {
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assert(CGN->empty() && "Cannot remove function from call "
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"graph if it references other functions!");
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Function *F = CGN->getFunction(); // Get the function for the call graph node
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FunctionMap.erase(F); // Remove the call graph node from the map
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M.getFunctionList().remove(F);
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return F;
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}
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/// spliceFunction - Replace the function represented by this node by another.
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/// This does not rescan the body of the function, so it is suitable when
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/// splicing the body of the old function to the new while also updating all
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/// callers from old to new.
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///
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void CallGraph::spliceFunction(const Function *From, const Function *To) {
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assert(FunctionMap.count(From) && "No CallGraphNode for function!");
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assert(!FunctionMap.count(To) &&
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"Pointing CallGraphNode at a function that already exists");
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FunctionMapTy::iterator I = FunctionMap.find(From);
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I->second->F = const_cast<Function*>(To);
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FunctionMap[To] = std::move(I->second);
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FunctionMap.erase(I);
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}
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// getOrInsertFunction - This method is identical to calling operator[], but
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// it will insert a new CallGraphNode for the specified function if one does
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// not already exist.
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CallGraphNode *CallGraph::getOrInsertFunction(const Function *F) {
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auto &CGN = FunctionMap[F];
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if (CGN)
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return CGN.get();
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assert((!F || F->getParent() == &M) && "Function not in current module!");
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CGN = llvm::make_unique<CallGraphNode>(const_cast<Function *>(F));
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return CGN.get();
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}
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//===----------------------------------------------------------------------===//
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// Implementations of the CallGraphNode class methods.
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//
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void CallGraphNode::print(raw_ostream &OS) const {
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if (Function *F = getFunction())
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OS << "Call graph node for function: '" << F->getName() << "'";
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else
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OS << "Call graph node <<null function>>";
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OS << "<<" << this << ">> #uses=" << getNumReferences() << '\n';
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for (const auto &I : *this) {
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OS << " CS<" << I.first << "> calls ";
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if (Function *FI = I.second->getFunction())
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OS << "function '" << FI->getName() <<"'\n";
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else
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OS << "external node\n";
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}
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OS << '\n';
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}
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#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
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LLVM_DUMP_METHOD void CallGraphNode::dump() const { print(dbgs()); }
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#endif
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/// removeCallEdgeFor - This method removes the edge in the node for the
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/// specified call site. Note that this method takes linear time, so it
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/// should be used sparingly.
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void CallGraphNode::removeCallEdgeFor(CallSite CS) {
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for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
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assert(I != CalledFunctions.end() && "Cannot find callsite to remove!");
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if (I->first == CS.getInstruction()) {
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I->second->DropRef();
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*I = CalledFunctions.back();
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CalledFunctions.pop_back();
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return;
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}
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}
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}
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// removeAnyCallEdgeTo - This method removes any call edges from this node to
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// the specified callee function. This takes more time to execute than
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// removeCallEdgeTo, so it should not be used unless necessary.
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void CallGraphNode::removeAnyCallEdgeTo(CallGraphNode *Callee) {
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for (unsigned i = 0, e = CalledFunctions.size(); i != e; ++i)
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if (CalledFunctions[i].second == Callee) {
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Callee->DropRef();
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CalledFunctions[i] = CalledFunctions.back();
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CalledFunctions.pop_back();
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--i; --e;
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}
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}
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/// removeOneAbstractEdgeTo - Remove one edge associated with a null callsite
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/// from this node to the specified callee function.
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void CallGraphNode::removeOneAbstractEdgeTo(CallGraphNode *Callee) {
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for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
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assert(I != CalledFunctions.end() && "Cannot find callee to remove!");
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CallRecord &CR = *I;
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if (CR.second == Callee && CR.first == nullptr) {
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Callee->DropRef();
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*I = CalledFunctions.back();
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CalledFunctions.pop_back();
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return;
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}
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}
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}
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/// replaceCallEdge - This method replaces the edge in the node for the
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/// specified call site with a new one. Note that this method takes linear
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/// time, so it should be used sparingly.
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void CallGraphNode::replaceCallEdge(CallSite CS,
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CallSite NewCS, CallGraphNode *NewNode){
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for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
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assert(I != CalledFunctions.end() && "Cannot find callsite to remove!");
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if (I->first == CS.getInstruction()) {
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I->second->DropRef();
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I->first = NewCS.getInstruction();
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I->second = NewNode;
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NewNode->AddRef();
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return;
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}
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}
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}
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// Provide an explicit template instantiation for the static ID.
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AnalysisKey CallGraphAnalysis::Key;
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PreservedAnalyses CallGraphPrinterPass::run(Module &M,
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ModuleAnalysisManager &AM) {
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AM.getResult<CallGraphAnalysis>(M).print(OS);
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return PreservedAnalyses::all();
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}
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//===----------------------------------------------------------------------===//
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// Out-of-line definitions of CallGraphAnalysis class members.
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//
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//===----------------------------------------------------------------------===//
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// Implementations of the CallGraphWrapperPass class methods.
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//
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CallGraphWrapperPass::CallGraphWrapperPass() : ModulePass(ID) {
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initializeCallGraphWrapperPassPass(*PassRegistry::getPassRegistry());
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}
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CallGraphWrapperPass::~CallGraphWrapperPass() {}
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void CallGraphWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
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AU.setPreservesAll();
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}
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bool CallGraphWrapperPass::runOnModule(Module &M) {
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// All the real work is done in the constructor for the CallGraph.
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G.reset(new CallGraph(M));
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return false;
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}
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INITIALIZE_PASS(CallGraphWrapperPass, "basiccg", "CallGraph Construction",
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false, true)
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char CallGraphWrapperPass::ID = 0;
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void CallGraphWrapperPass::releaseMemory() { G.reset(); }
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void CallGraphWrapperPass::print(raw_ostream &OS, const Module *) const {
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if (!G) {
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OS << "No call graph has been built!\n";
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return;
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}
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// Just delegate.
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G->print(OS);
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}
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#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
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LLVM_DUMP_METHOD
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void CallGraphWrapperPass::dump() const { print(dbgs(), nullptr); }
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#endif
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namespace {
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struct CallGraphPrinterLegacyPass : public ModulePass {
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static char ID; // Pass ID, replacement for typeid
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CallGraphPrinterLegacyPass() : ModulePass(ID) {
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initializeCallGraphPrinterLegacyPassPass(*PassRegistry::getPassRegistry());
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}
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.setPreservesAll();
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AU.addRequiredTransitive<CallGraphWrapperPass>();
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}
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bool runOnModule(Module &M) override {
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getAnalysis<CallGraphWrapperPass>().print(errs(), &M);
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return false;
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}
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};
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}
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char CallGraphPrinterLegacyPass::ID = 0;
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INITIALIZE_PASS_BEGIN(CallGraphPrinterLegacyPass, "print-callgraph",
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"Print a call graph", true, true)
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INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass)
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INITIALIZE_PASS_END(CallGraphPrinterLegacyPass, "print-callgraph",
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"Print a call graph", true, true)
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