HelperDeclRefGraph.cpp
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//===-- HelperDeclRefGraph.cpp - AST-based call graph for helper decls ----===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "HelperDeclRefGraph.h"
#include "Move.h"
#include "clang/AST/Decl.h"
#include "llvm/Support/Debug.h"
#include <vector>
#define DEBUG_TYPE "clang-move"
namespace clang {
namespace move {
void HelperDeclRefGraph::print(raw_ostream &OS) const {
OS << " --- Call graph Dump --- \n";
for (auto I = DeclMap.begin(); I != DeclMap.end(); ++I) {
const CallGraphNode *N = (I->second).get();
OS << " Declarations: ";
N->print(OS);
OS << " (" << N << ") ";
OS << " calls: ";
for (auto CI = N->begin(), CE = N->end(); CI != CE; ++CI) {
CI->Callee->print(OS);
OS << " (" << CI << ") ";
}
OS << '\n';
}
OS.flush();
}
void HelperDeclRefGraph::addEdge(const Decl *Caller, const Decl *Callee) {
assert(Caller);
assert(Callee);
// Ignore the case where Caller equals Callee. This happens in the static
// class member definitions in global namespace like "int CLASS::static_var =
// 1;", its DC is a VarDel whose outmost enclosing declaration is the "CLASS"
// CXXRecordDecl.
if (Caller == Callee) return;
// Allocate a new node, mark it as root, and process it's calls.
CallGraphNode *CallerNode = getOrInsertNode(const_cast<Decl *>(Caller));
CallGraphNode *CalleeNode = getOrInsertNode(const_cast<Decl *>(Callee));
CallerNode->addCallee({CalleeNode, /*CallExpr=*/nullptr});
}
void HelperDeclRefGraph::dump() const { print(llvm::errs()); }
CallGraphNode *HelperDeclRefGraph::getOrInsertNode(Decl *F) {
F = F->getCanonicalDecl();
std::unique_ptr<CallGraphNode> &Node = DeclMap[F];
if (Node)
return Node.get();
Node = std::make_unique<CallGraphNode>(F);
return Node.get();
}
CallGraphNode *HelperDeclRefGraph::getNode(const Decl *D) const {
auto I = DeclMap.find(D->getCanonicalDecl());
return I == DeclMap.end() ? nullptr : I->second.get();
}
llvm::DenseSet<const CallGraphNode *>
HelperDeclRefGraph::getReachableNodes(const Decl *Root) const {
const auto *RootNode = getNode(Root);
if (!RootNode)
return {};
llvm::DenseSet<const CallGraphNode *> ConnectedNodes;
std::function<void(const CallGraphNode *)> VisitNode =
[&](const CallGraphNode *Node) {
if (ConnectedNodes.count(Node))
return;
ConnectedNodes.insert(Node);
for (auto It = Node->begin(), End = Node->end(); It != End; ++It)
VisitNode(*It);
};
VisitNode(RootNode);
return ConnectedNodes;
}
const Decl *HelperDeclRGBuilder::getOutmostClassOrFunDecl(const Decl *D) {
const auto *DC = D->getDeclContext();
const auto *Result = D;
while (DC) {
if (const auto *RD = dyn_cast<CXXRecordDecl>(DC))
Result = RD;
else if (const auto *FD = dyn_cast<FunctionDecl>(DC))
Result = FD;
DC = DC->getParent();
}
return Result;
}
void HelperDeclRGBuilder::run(
const ast_matchers::MatchFinder::MatchResult &Result) {
// Construct the graph by adding a directed edge from caller to callee.
//
// "dc" is the closest ancestor declaration of "func_ref" or "used_class", it
// might be not the targetted Caller Decl, we always use the outmost enclosing
// FunctionDecl/CXXRecordDecl of "dc". For example,
//
// int MoveClass::F() { int a = helper(); return a; }
//
// The matched "dc" of "helper" DeclRefExpr is a VarDecl, we traverse up AST
// to find the outmost "MoveClass" CXXRecordDecl and use it as Caller.
if (const auto *FuncRef = Result.Nodes.getNodeAs<DeclRefExpr>("func_ref")) {
const auto *DC = Result.Nodes.getNodeAs<Decl>("dc");
assert(DC);
LLVM_DEBUG(llvm::dbgs() << "Find helper function usage: "
<< FuncRef->getDecl()->getDeclName() << " ("
<< FuncRef->getDecl() << ")\n");
RG->addEdge(
getOutmostClassOrFunDecl(DC->getCanonicalDecl()),
getOutmostClassOrFunDecl(FuncRef->getDecl()->getCanonicalDecl()));
} else if (const auto *UsedClass =
Result.Nodes.getNodeAs<CXXRecordDecl>("used_class")) {
const auto *DC = Result.Nodes.getNodeAs<Decl>("dc");
assert(DC);
LLVM_DEBUG(llvm::dbgs()
<< "Find helper class usage: " << UsedClass->getDeclName()
<< " (" << UsedClass << ")\n");
RG->addEdge(getOutmostClassOrFunDecl(DC->getCanonicalDecl()), UsedClass);
}
}
} // namespace move
} // namespace clang