================ @@ -0,0 +1,99 @@ +//===--- InefficientCopyAssignCheck.cpp - clang-tidy ----------------------===// +// +// 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 "InefficientCopyAssignCheck.h" + +#include "clang/AST/Expr.h" +#include "clang/AST/ExprCXX.h" +#include "clang/ASTMatchers/ASTMatchers.h" +#include "clang/Analysis/Analyses/CFGReachabilityAnalysis.h" +#include "clang/Lex/Lexer.h" +#include "llvm/ADT/STLExtras.h" + +using namespace clang::ast_matchers; + +namespace clang::tidy::performance { + +void InefficientCopyAssignCheck::registerMatchers(MatchFinder *Finder) { + auto AssignOperatorExpr = + cxxOperatorCallExpr( + hasOperatorName("="), + hasArgument( + 0, hasType(cxxRecordDecl(hasMethod(isMoveAssignmentOperator())) + .bind("assign-target-type"))), + hasArgument(1, declRefExpr(to(varDecl().bind("assign-value-decl"))) + .bind("assign-value")), + hasAncestor(functionDecl().bind("within-func"))) + .bind("assign"); + Finder->addMatcher(AssignOperatorExpr, this); +} + +CFG *InefficientCopyAssignCheck::getCFG(const FunctionDecl *FD, + ASTContext *Context) { + std::unique_ptr<CFG> &TheCFG = CFGCache[FD]; + if (!TheCFG) { + const CFG::BuildOptions Options; + std::unique_ptr<CFG> FCFG = + CFG::buildCFG(nullptr, FD->getBody(), Context, Options); + if (!FCFG) + return nullptr; + TheCFG.swap(FCFG); + } + return TheCFG.get(); +} + +void InefficientCopyAssignCheck::check(const MatchFinder::MatchResult &Result) { + const auto *AssignExpr = Result.Nodes.getNodeAs<Expr>("assign"); + const auto *AssignValue = Result.Nodes.getNodeAs<DeclRefExpr>("assign-value"); + const auto *AssignValueDecl = + Result.Nodes.getNodeAs<VarDecl>("assign-value-decl"); + const auto *AssignTargetType = + Result.Nodes.getNodeAs<CXXRecordDecl>("assign-target-type"); + const auto *WithinFunctionDecl = + Result.Nodes.getNodeAs<FunctionDecl>("within-func"); + + const QualType AssignValueQual = AssignValueDecl->getType(); + if (AssignValueQual->isLValueReferenceType() || + AssignValueQual.isConstQualified() || AssignValueQual->isPointerType() || + AssignValueQual->isScalarType()) + return; + + if (!AssignValueDecl->hasLocalStorage()) + return; + + if (AssignTargetType->hasTrivialMoveAssignment()) + return; + + if (CFG *TheCFG = getCFG(WithinFunctionDecl, Result.Context)) { + // Walk the CFG bottom-up, starting with the exit node. + // TODO: traverse the whole CFG instead of only considering terminator + // nodes. + + CFGBlock &TheExit = TheCFG->getExit(); + for (auto &Pred : TheExit.preds()) { + for (const CFGElement &Elt : llvm::reverse(*Pred)) { + if (Elt.getKind() == CFGElement::Kind::Statement) { + const Stmt *EltStmt = Elt.castAs<CFGStmt>().getStmt(); + if (EltStmt == AssignExpr) { + diag(AssignValue->getBeginLoc(), "'%0' could be moved here") + << AssignValue->getDecl()->getName(); + break; + } + // The reference is being referenced before the assignment, bail out. + auto DeclRefMatcher = + declRefExpr(hasDeclaration(equalsNode(AssignValue->getDecl()))); + if (!match(findAll(DeclRefMatcher), *EltStmt, *Result.Context) ---------------- zwuis wrote:
We have `allDeclRefExprs()`in "../utils/DeclRefExprUtils.h". https://github.com/llvm/llvm-project/pull/179467 _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
