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================ @@ -0,0 +1,171 @@ +//===----------------------------------------------------------------------===// +// +// 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 "ExpensiveValueOrCheck.h" +#include "../utils/Matchers.h" +#include "../utils/OptionsUtils.h" +#include "../utils/TypeTraits.h" +#include "clang/AST/ASTContext.h" +#include "clang/ASTMatchers/ASTMatchFinder.h" +#include "clang/Tooling/FixIt.h" + +using namespace clang::ast_matchers; + +namespace clang::tidy::performance { + +static bool hasOperatorStar(const CXXRecordDecl *RD) { + const DeclarationName OpStar = + RD->getASTContext().DeclarationNames.getCXXOperatorName(OO_Star); + return !RD->lookup(OpStar).empty(); +} + +static StringRef findValueMethod(const CXXRecordDecl *RD) { + ASTContext &Ctx = RD->getASTContext(); + for (StringRef Name : {"value", "Value"}) { + const DeclarationName DN = &Ctx.Idents.get(Name); + if (!RD->lookup(DN).empty()) + return Name; + } + return {}; +} + +static std::string buildSuggestion(const CXXRecordDecl *OptionalClass) { + const bool HasDeref = hasOperatorStar(OptionalClass); + StringRef ValueName = findValueMethod(OptionalClass); + + if (HasDeref && !ValueName.empty()) + return (llvm::Twine("consider using 'operator*' or '") + ValueName + + "()' with a separate fallback") + .str(); + if (HasDeref) + return "consider using 'operator*' with a separate fallback"; + if (!ValueName.empty()) + return (llvm::Twine("consider using '") + ValueName + + "()' with a separate fallback") + .str(); + return "consider avoiding the copy"; +} + +static std::optional<FixItHint> buildFixIt(const CXXMemberCallExpr *Call, + const Expr *ObjExpr, + const Expr *FallbackArg, + const CXXRecordDecl *OptionalClass, + const ASTContext &Ctx) { + if (Call->getBeginLoc().isMacroID()) + return std::nullopt; + if (!ObjExpr->isLValue()) + return std::nullopt; + if (!hasOperatorStar(OptionalClass)) + return std::nullopt; + + StringRef ObjText = tooling::fixit::getText(*ObjExpr, Ctx); + StringRef ArgText = tooling::fixit::getText(*FallbackArg, Ctx); + + if (ObjText.empty() || ArgText.empty()) + return std::nullopt; + + const std::string Replacement = + ("(" + ObjText + " ? *" + ObjText + " : " + ArgText + ")").str(); + return FixItHint::CreateReplacement(Call->getSourceRange(), Replacement); +} + +ExpensiveValueOrCheck::ExpensiveValueOrCheck(StringRef Name, + ClangTidyContext *Context) + : ClangTidyCheck(Name, Context), + SizeThreshold(Options.get("SizeThreshold", 16U)), + OptionalTypes(utils::options::parseStringList( + Options.get("OptionalTypes", + "::std::optional;::absl::optional;::boost::optional"))), + WarnOnOwnershipTaking(Options.get("WarnOnOwnershipTaking", false)) {} + +void ExpensiveValueOrCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) { + Options.store(Opts, "SizeThreshold", SizeThreshold); + Options.store(Opts, "OptionalTypes", + utils::options::serializeStringList(OptionalTypes)); + Options.store(Opts, "WarnOnOwnershipTaking", WarnOnOwnershipTaking); +} + +void ExpensiveValueOrCheck::registerMatchers(MatchFinder *Finder) { + auto OptionalTypesMatcher = + matchers::matchesAnyListedRegexName(OptionalTypes); + auto ValueOrMatcher = hasAnyName("value_or", "valueOr", "ValueOr"); + auto ValueOrCall = cxxMemberCallExpr( + callee(cxxMethodDecl(ValueOrMatcher, ofClass(OptionalTypesMatcher)))); + + if (WarnOnOwnershipTaking) { + Finder->addMatcher(ValueOrCall.bind("call"), this); + return; + } + + // Binding to const T& variable. + Finder->addMatcher( + varDecl(hasType(lValueReferenceType(pointee(isConstQualified()))), + hasInitializer(ignoringImplicit(ValueOrCall.bind("call")))), + this); + + // Passing to a const T& parameter. + Finder->addMatcher(callExpr(forEachArgumentWithParam( + ignoringImplicit(ValueOrCall.bind("call")), + parmVarDecl(hasType(lValueReferenceType( + pointee(isConstQualified())))))), + this); + + // Calling a const member function on the result. + Finder->addMatcher( + cxxMemberCallExpr(on(ignoringImplicit(ValueOrCall.bind("call"))), + callee(cxxMethodDecl(isConst()))), + this); +} + +void ExpensiveValueOrCheck::check(const MatchFinder::MatchResult &Result) { + const auto *Call = Result.Nodes.getNodeAs<CXXMemberCallExpr>("call"); + assert(Call && "Matcher guaranteed a bound 'call' node"); + const Expr *ObjExpr = Call->getImplicitObjectArgument(); + assert(ObjExpr && "CXXMemberCallExpr must have an implicit object argument"); + + const ASTContext &Ctx = *Result.Context; + const QualType ValueType = Call->getType(); + + // Rvalue optional uses && overload which moves. Suppress if move is cheap. + if (!ObjExpr->isLValue() && + utils::type_traits::hasNonTrivialMoveConstructor(ValueType)) + return; + + const bool IsExpensiveType = + utils::type_traits::isExpensiveToCopy(ValueType, Ctx).value_or(false); + const int64_t ValueSize = Ctx.getTypeSizeInChars(ValueType).getQuantity(); + const bool IsExpensive = + IsExpensiveType || ValueSize > static_cast<int64_t>(SizeThreshold); + + if (!IsExpensive) + return; ---------------- zwuis wrote: Move them to AST matchers. ``` cxxMemberCallExpr( ..., anyOf(on(/* is lvalue */), hasType(/* no non trivial move ctor */)), hasType(/* expensive to copy */(SizeThreshold))) ``` https://github.com/llvm/llvm-project/pull/200166 _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
