282 lines · cpp
1//===- CallGraph.cpp - AST-based Call graph -------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8//9// This file defines the AST-based CallGraph.10//11//===----------------------------------------------------------------------===//12 13#include "clang/Analysis/CallGraph.h"14#include "clang/AST/Decl.h"15#include "clang/AST/DeclBase.h"16#include "clang/AST/DeclObjC.h"17#include "clang/AST/Expr.h"18#include "clang/AST/ExprObjC.h"19#include "clang/AST/Stmt.h"20#include "clang/AST/StmtVisitor.h"21#include "clang/Basic/IdentifierTable.h"22#include "clang/Basic/LLVM.h"23#include "llvm/ADT/PostOrderIterator.h"24#include "llvm/ADT/Statistic.h"25#include "llvm/Support/Casting.h"26#include "llvm/Support/Compiler.h"27#include "llvm/Support/DOTGraphTraits.h"28#include "llvm/Support/GraphWriter.h"29#include "llvm/Support/raw_ostream.h"30#include <cassert>31#include <memory>32#include <string>33 34using namespace clang;35 36#define DEBUG_TYPE "CallGraph"37 38STATISTIC(NumObjCCallEdges, "Number of Objective-C method call edges");39STATISTIC(NumBlockCallEdges, "Number of block call edges");40 41namespace {42 43/// A helper class, which walks the AST and locates all the call sites in the44/// given function body.45class CGBuilder : public StmtVisitor<CGBuilder> {46 CallGraph *G;47 CallGraphNode *CallerNode;48 49public:50 CGBuilder(CallGraph *g, CallGraphNode *N) : G(g), CallerNode(N) {}51 52 void VisitStmt(Stmt *S) { VisitChildren(S); }53 54 Decl *getDeclFromCall(CallExpr *CE) {55 if (FunctionDecl *CalleeDecl = CE->getDirectCallee())56 return CalleeDecl;57 58 // Simple detection of a call through a block.59 Expr *CEE = CE->getCallee()->IgnoreParenImpCasts();60 if (BlockExpr *Block = dyn_cast<BlockExpr>(CEE)) {61 NumBlockCallEdges++;62 return Block->getBlockDecl();63 }64 65 return nullptr;66 }67 68 void addCalledDecl(Decl *D, Expr *CallExpr) {69 if (G->includeCalleeInGraph(D)) {70 CallGraphNode *CalleeNode = G->getOrInsertNode(D);71 CallerNode->addCallee({CalleeNode, CallExpr});72 }73 }74 75 void VisitCallExpr(CallExpr *CE) {76 if (Decl *D = getDeclFromCall(CE))77 addCalledDecl(D, CE);78 VisitChildren(CE);79 }80 81 void VisitLambdaExpr(LambdaExpr *LE) {82 if (FunctionTemplateDecl *FTD = LE->getDependentCallOperator())83 for (FunctionDecl *FD : FTD->specializations())84 G->VisitFunctionDecl(FD);85 else if (CXXMethodDecl *MD = LE->getCallOperator())86 G->VisitFunctionDecl(MD);87 }88 89 void VisitCXXNewExpr(CXXNewExpr *E) {90 if (FunctionDecl *FD = E->getOperatorNew())91 addCalledDecl(FD, E);92 VisitChildren(E);93 }94 95 void VisitCXXConstructExpr(CXXConstructExpr *E) {96 CXXConstructorDecl *Ctor = E->getConstructor();97 if (FunctionDecl *Def = Ctor->getDefinition())98 addCalledDecl(Def, E);99 VisitChildren(E);100 }101 102 // Include the evaluation of the default argument.103 void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *E) {104 Visit(E->getExpr());105 }106 107 // Include the evaluation of the default initializers in a class.108 void VisitCXXDefaultInitExpr(CXXDefaultInitExpr *E) {109 Visit(E->getExpr());110 }111 112 // Adds may-call edges for the ObjC message sends.113 void VisitObjCMessageExpr(ObjCMessageExpr *ME) {114 if (ObjCInterfaceDecl *IDecl = ME->getReceiverInterface()) {115 Selector Sel = ME->getSelector();116 117 // Find the callee definition within the same translation unit.118 Decl *D = nullptr;119 if (ME->isInstanceMessage())120 D = IDecl->lookupPrivateMethod(Sel);121 else122 D = IDecl->lookupPrivateClassMethod(Sel);123 if (D) {124 addCalledDecl(D, ME);125 NumObjCCallEdges++;126 }127 }128 }129 130 void VisitChildren(Stmt *S) {131 for (Stmt *SubStmt : S->children())132 if (SubStmt)133 this->Visit(SubStmt);134 }135};136 137} // namespace138 139void CallGraph::addNodesForBlocks(DeclContext *D) {140 if (BlockDecl *BD = dyn_cast<BlockDecl>(D))141 addNodeForDecl(BD, true);142 143 for (auto *I : D->decls())144 if (auto *DC = dyn_cast<DeclContext>(I))145 addNodesForBlocks(DC);146}147 148CallGraph::CallGraph() {149 ShouldWalkTypesOfTypeLocs = false;150 ShouldVisitTemplateInstantiations = true;151 ShouldVisitImplicitCode = true;152 Root = getOrInsertNode(nullptr);153}154 155CallGraph::~CallGraph() = default;156 157bool CallGraph::includeInGraph(const Decl *D) {158 assert(D);159 if (!D->hasBody())160 return false;161 162 return includeCalleeInGraph(D);163}164 165bool CallGraph::includeCalleeInGraph(const Decl *D) {166 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {167 // We skip function template definitions, as their semantics is168 // only determined when they are instantiated.169 if (FD->isDependentContext())170 return false;171 172 IdentifierInfo *II = FD->getIdentifier();173 if (II && II->getName().starts_with("__inline"))174 return false;175 }176 177 return true;178}179 180void CallGraph::addNodeForDecl(Decl* D, bool IsGlobal) {181 assert(D);182 183 // Allocate a new node, mark it as root, and process its calls.184 CallGraphNode *Node = getOrInsertNode(D);185 186 // Process all the calls by this function as well.187 CGBuilder builder(this, Node);188 if (Stmt *Body = D->getBody())189 builder.Visit(Body);190 191 // Include C++ constructor member initializers.192 if (auto constructor = dyn_cast<CXXConstructorDecl>(D)) {193 for (CXXCtorInitializer *init : constructor->inits()) {194 builder.Visit(init->getInit());195 }196 }197}198 199CallGraphNode *CallGraph::getNode(const Decl *F) const {200 FunctionMapTy::const_iterator I = FunctionMap.find(F);201 if (I == FunctionMap.end()) return nullptr;202 return I->second.get();203}204 205CallGraphNode *CallGraph::getOrInsertNode(Decl *F) {206 if (F && !isa<ObjCMethodDecl>(F))207 F = F->getCanonicalDecl();208 209 std::unique_ptr<CallGraphNode> &Node = FunctionMap[F];210 if (Node)211 return Node.get();212 213 Node = std::make_unique<CallGraphNode>(F);214 // Make Root node a parent of all functions to make sure all are reachable.215 if (F)216 Root->addCallee({Node.get(), /*Call=*/nullptr});217 return Node.get();218}219 220void CallGraph::print(raw_ostream &OS) const {221 OS << " --- Call graph Dump --- \n";222 223 // We are going to print the graph in reverse post order, partially, to make224 // sure the output is deterministic.225 llvm::ReversePostOrderTraversal<const CallGraph *> RPOT(this);226 for (const CallGraphNode *N : RPOT) {227 OS << " Function: ";228 if (N == Root)229 OS << "< root >";230 else231 N->print(OS);232 233 OS << " calls: ";234 for (CallGraphNode::const_iterator CI = N->begin(),235 CE = N->end(); CI != CE; ++CI) {236 assert(CI->Callee != Root && "No one can call the root node.");237 CI->Callee->print(OS);238 OS << " ";239 }240 OS << '\n';241 }242 OS.flush();243}244 245LLVM_DUMP_METHOD void CallGraph::dump() const {246 print(llvm::errs());247}248 249void CallGraph::viewGraph() const {250 llvm::ViewGraph(this, "CallGraph");251}252 253void CallGraphNode::print(raw_ostream &os) const {254 if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(FD))255 return ND->printQualifiedName(os);256 os << "< >";257}258 259LLVM_DUMP_METHOD void CallGraphNode::dump() const {260 print(llvm::errs());261}262 263namespace llvm {264 265template <>266struct DOTGraphTraits<const CallGraph*> : public DefaultDOTGraphTraits {267 DOTGraphTraits (bool isSimple = false) : DefaultDOTGraphTraits(isSimple) {}268 269 static std::string getNodeLabel(const CallGraphNode *Node,270 const CallGraph *CG) {271 if (CG->getRoot() == Node) {272 return "< root >";273 }274 if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(Node->getDecl()))275 return ND->getNameAsString();276 else277 return "< >";278 }279};280 281} // namespace llvm282