1 //===-- HelperDeclRefGraph.cpp - AST-based call graph for helper decls ----===//
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-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #include "HelperDeclRefGraph.h"
10 #include "Move.h"
11 #include "clang/AST/Decl.h"
12 #include "llvm/Support/Debug.h"
13 #include <vector>
14
15 #define DEBUG_TYPE "clang-move"
16
17 namespace clang {
18 namespace move {
19
print(raw_ostream & OS) const20 void HelperDeclRefGraph::print(raw_ostream &OS) const {
21 OS << " --- Call graph Dump --- \n";
22 for (auto I = DeclMap.begin(); I != DeclMap.end(); ++I) {
23 const CallGraphNode *N = (I->second).get();
24
25 OS << " Declarations: ";
26 N->print(OS);
27 OS << " (" << N << ") ";
28 OS << " calls: ";
29 for (auto CI = N->begin(), CE = N->end(); CI != CE; ++CI) {
30 CI->Callee->print(OS);
31 OS << " (" << CI << ") ";
32 }
33 OS << '\n';
34 }
35 OS.flush();
36 }
37
addEdge(const Decl * Caller,const Decl * Callee)38 void HelperDeclRefGraph::addEdge(const Decl *Caller, const Decl *Callee) {
39 assert(Caller);
40 assert(Callee);
41
42 // Ignore the case where Caller equals Callee. This happens in the static
43 // class member definitions in global namespace like "int CLASS::static_var =
44 // 1;", its DC is a VarDel whose outmost enclosing declaration is the "CLASS"
45 // CXXRecordDecl.
46 if (Caller == Callee) return;
47
48 // Allocate a new node, mark it as root, and process it's calls.
49 CallGraphNode *CallerNode = getOrInsertNode(const_cast<Decl *>(Caller));
50 CallGraphNode *CalleeNode = getOrInsertNode(const_cast<Decl *>(Callee));
51 CallerNode->addCallee({CalleeNode, /*CallExpr=*/nullptr});
52 }
53
dump() const54 void HelperDeclRefGraph::dump() const { print(llvm::errs()); }
55
getOrInsertNode(Decl * F)56 CallGraphNode *HelperDeclRefGraph::getOrInsertNode(Decl *F) {
57 F = F->getCanonicalDecl();
58 std::unique_ptr<CallGraphNode> &Node = DeclMap[F];
59 if (Node)
60 return Node.get();
61
62 Node = std::make_unique<CallGraphNode>(F);
63 return Node.get();
64 }
65
getNode(const Decl * D) const66 CallGraphNode *HelperDeclRefGraph::getNode(const Decl *D) const {
67 auto I = DeclMap.find(D->getCanonicalDecl());
68 return I == DeclMap.end() ? nullptr : I->second.get();
69 }
70
71 llvm::DenseSet<const CallGraphNode *>
getReachableNodes(const Decl * Root) const72 HelperDeclRefGraph::getReachableNodes(const Decl *Root) const {
73 const auto *RootNode = getNode(Root);
74 if (!RootNode)
75 return {};
76 llvm::DenseSet<const CallGraphNode *> ConnectedNodes;
77 std::function<void(const CallGraphNode *)> VisitNode =
78 [&](const CallGraphNode *Node) {
79 if (ConnectedNodes.count(Node))
80 return;
81 ConnectedNodes.insert(Node);
82 for (auto It = Node->begin(), End = Node->end(); It != End; ++It)
83 VisitNode(*It);
84 };
85
86 VisitNode(RootNode);
87 return ConnectedNodes;
88 }
89
getOutmostClassOrFunDecl(const Decl * D)90 const Decl *HelperDeclRGBuilder::getOutmostClassOrFunDecl(const Decl *D) {
91 const auto *DC = D->getDeclContext();
92 const auto *Result = D;
93 while (DC) {
94 if (const auto *RD = dyn_cast<CXXRecordDecl>(DC))
95 Result = RD;
96 else if (const auto *FD = dyn_cast<FunctionDecl>(DC))
97 Result = FD;
98 DC = DC->getParent();
99 }
100 return Result;
101 }
102
run(const ast_matchers::MatchFinder::MatchResult & Result)103 void HelperDeclRGBuilder::run(
104 const ast_matchers::MatchFinder::MatchResult &Result) {
105 // Construct the graph by adding a directed edge from caller to callee.
106 //
107 // "dc" is the closest ancestor declaration of "func_ref" or "used_class", it
108 // might be not the targetted Caller Decl, we always use the outmost enclosing
109 // FunctionDecl/CXXRecordDecl of "dc". For example,
110 //
111 // int MoveClass::F() { int a = helper(); return a; }
112 //
113 // The matched "dc" of "helper" DeclRefExpr is a VarDecl, we traverse up AST
114 // to find the outmost "MoveClass" CXXRecordDecl and use it as Caller.
115 if (const auto *FuncRef = Result.Nodes.getNodeAs<DeclRefExpr>("func_ref")) {
116 const auto *DC = Result.Nodes.getNodeAs<Decl>("dc");
117 assert(DC);
118 LLVM_DEBUG(llvm::dbgs() << "Find helper function usage: "
119 << FuncRef->getDecl()->getDeclName() << " ("
120 << FuncRef->getDecl() << ")\n");
121 RG->addEdge(
122 getOutmostClassOrFunDecl(DC->getCanonicalDecl()),
123 getOutmostClassOrFunDecl(FuncRef->getDecl()->getCanonicalDecl()));
124 } else if (const auto *UsedClass =
125 Result.Nodes.getNodeAs<CXXRecordDecl>("used_class")) {
126 const auto *DC = Result.Nodes.getNodeAs<Decl>("dc");
127 assert(DC);
128 LLVM_DEBUG(llvm::dbgs()
129 << "Find helper class usage: " << UsedClass->getDeclName()
130 << " (" << UsedClass << ")\n");
131 RG->addEdge(getOutmostClassOrFunDecl(DC->getCanonicalDecl()), UsedClass);
132 }
133 }
134
135 } // namespace move
136 } // namespace clang
137