================ @@ -0,0 +1,70 @@ +//===----------------------------------------------------------------------===// +// +// 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/OptionsUtils.h" +#include "clang/AST/ASTContext.h" +#include "clang/ASTMatchers/ASTMatchFinder.h" + +using namespace clang::ast_matchers; + +namespace clang::tidy::performance { + +ExpensiveValueOrCheck::ExpensiveValueOrCheck(StringRef Name, + ClangTidyContext *Context) + : ClangTidyCheck(Name, Context), + SizeThreshold(Options.get("SizeThreshold", 8U)), + WarnOnRvalueOptional(Options.get("WarnOnRvalueOptional", false)), + OptionalTypes(utils::options::parseStringList( + Options.get("OptionalTypes", "::std::optional"))) {} + +void ExpensiveValueOrCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) { + Options.store(Opts, "SizeThreshold", SizeThreshold); + Options.store(Opts, "WarnOnRvalueOptional", WarnOnRvalueOptional); + Options.store(Opts, "OptionalTypes", + utils::options::serializeStringList(OptionalTypes)); +} + +void ExpensiveValueOrCheck::registerMatchers(MatchFinder *Finder) { + auto OptionalTypesMatcher = hasAnyName(OptionalTypes); + + Finder->addMatcher( + cxxMemberCallExpr(callee(cxxMethodDecl(hasName("value_or"), + ofClass(OptionalTypesMatcher)))) + .bind("call"), + this); +} + +void ExpensiveValueOrCheck::check(const MatchFinder::MatchResult &Result) { + const auto *Call = Result.Nodes.getNodeAs<CXXMemberCallExpr>("call"); + if (!Call) + return; + + const Expr *ObjExpr = Call->getImplicitObjectArgument(); + if (!WarnOnRvalueOptional && ObjExpr && !ObjExpr->isLValue()) + return; + + const QualType ValueType = Call->getType().getCanonicalType(); + if (ValueType->isDependentType() || ValueType->isIncompleteType()) + return; + + const ASTContext &Ctx = *Result.Context; + const int64_t ValueSize = Ctx.getTypeSizeInChars(ValueType).getQuantity(); + const bool IsExpensive = !ValueType.isTriviallyCopyableType(Ctx) || + ValueSize > static_cast<int64_t>(SizeThreshold); + + if (!IsExpensive) + return; + + diag(Call->getExprLoc(), + "'value_or' copies expensive type %0; consider using 'operator*' or " + "'value()' with a separate fallback") + << ValueType; ---------------- gamesh411 wrote:
Thanks, this is a new alternative I haven't considered here. For me, at least some type of information seems beneficial, especially if we choose the "duck typing" detection (all methods named `value_or` and returning a value). Because then it is not clear from the context of the check alone which type we are talking about, and that I think would help see patterns in the code for those reading the clang-tidy diag. Also, the suggestion list should take into account which operators/methods are available on the matched type if we go down the duck-typing route. https://github.com/llvm/llvm-project/pull/200166 _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
