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
17namespace clang {
18namespace move {
19
20void 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&: OS);
27 OS << " (" << N << ") ";
28 OS << " calls: ";
29 for (auto CI = N->begin(), CE = N->end(); CI != CE; ++CI) {
30 CI->Callee->print(os&: OS);
31 OS << " (" << CI << ") ";
32 }
33 OS << '\n';
34 }
35 OS.flush();
36}
37
38void 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(D: const_cast<Decl *>(Caller));
50 CallGraphNode *CalleeNode = getOrInsertNode(D: const_cast<Decl *>(Callee));
51 CallerNode->addCallee(Call: {CalleeNode, /*CallExpr=*/nullptr});
52}
53
54void HelperDeclRefGraph::dump() const { print(OS&: llvm::errs()); }
55
56CallGraphNode *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>(args&: F);
63 return Node.get();
64}
65
66CallGraphNode *HelperDeclRefGraph::getNode(const Decl *D) const {
67 auto I = DeclMap.find(Val: D->getCanonicalDecl());
68 return I == DeclMap.end() ? nullptr : I->second.get();
69}
70
71llvm::DenseSet<const CallGraphNode *>
72HelperDeclRefGraph::getReachableNodes(const Decl *Root) const {
73 const auto *RootNode = getNode(D: 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.insert(V: Node).second)
80 return;
81 for (const CallGraphNode::CallRecord &Callee : *Node)
82 VisitNode(Callee);
83 };
84
85 VisitNode(RootNode);
86 return ConnectedNodes;
87}
88
89const Decl *HelperDeclRGBuilder::getOutmostClassOrFunDecl(const Decl *D) {
90 const auto *DC = D->getDeclContext();
91 const auto *Result = D;
92 while (DC) {
93 if (const auto *RD = dyn_cast<CXXRecordDecl>(Val: DC))
94 Result = RD;
95 else if (const auto *FD = dyn_cast<FunctionDecl>(Val: DC))
96 Result = FD;
97 DC = DC->getParent();
98 }
99 return Result;
100}
101
102void HelperDeclRGBuilder::run(
103 const ast_matchers::MatchFinder::MatchResult &Result) {
104 // Construct the graph by adding a directed edge from caller to callee.
105 //
106 // "dc" is the closest ancestor declaration of "func_ref" or "used_class", it
107 // might be not the targetted Caller Decl, we always use the outmost enclosing
108 // FunctionDecl/CXXRecordDecl of "dc". For example,
109 //
110 // int MoveClass::F() { int a = helper(); return a; }
111 //
112 // The matched "dc" of "helper" DeclRefExpr is a VarDecl, we traverse up AST
113 // to find the outmost "MoveClass" CXXRecordDecl and use it as Caller.
114 if (const auto *FuncRef = Result.Nodes.getNodeAs<DeclRefExpr>(ID: "func_ref")) {
115 const auto *DC = Result.Nodes.getNodeAs<Decl>(ID: "dc");
116 assert(DC);
117 LLVM_DEBUG(llvm::dbgs() << "Find helper function usage: "
118 << FuncRef->getDecl()->getDeclName() << " ("
119 << FuncRef->getDecl() << ")\n");
120 RG->addEdge(
121 Caller: getOutmostClassOrFunDecl(D: DC->getCanonicalDecl()),
122 Callee: getOutmostClassOrFunDecl(D: FuncRef->getDecl()->getCanonicalDecl()));
123 } else if (const auto *UsedClass =
124 Result.Nodes.getNodeAs<CXXRecordDecl>(ID: "used_class")) {
125 const auto *DC = Result.Nodes.getNodeAs<Decl>(ID: "dc");
126 assert(DC);
127 LLVM_DEBUG(llvm::dbgs()
128 << "Find helper class usage: " << UsedClass->getDeclName()
129 << " (" << UsedClass << ")\n");
130 RG->addEdge(getOutmostClassOrFunDecl(D: DC->getCanonicalDecl()), UsedClass);
131 }
132}
133
134} // namespace move
135} // namespace clang
136

source code of clang-tools-extra/clang-move/HelperDeclRefGraph.cpp