Author: Richard Smith Date: 2022-04-15T14:09:45-07:00 New Revision: 64c045e25b8471bbb572bd29159c294a82a86a25
URL: https://github.com/llvm/llvm-project/commit/64c045e25b8471bbb572bd29159c294a82a86a25 DIFF: https://github.com/llvm/llvm-project/commit/64c045e25b8471bbb572bd29159c294a82a86a25.diff LOG: Treat `std::move`, `forward`, and `move_if_noexcept` as builtins. We still require these functions to be declared before they can be used, but don't instantiate their definitions unless their addresses are taken. Instead, code generation, constant evaluation, and static analysis are given direct knowledge of their effect. This change aims to reduce various costs associated with these functions -- per-instantiation memory costs, compile time and memory costs due to creating out-of-line copies and inlining them, code size at -O0, and so on -- so that they are not substantially more expensive than a cast. Most of these improvements are very small, but I measured a 3% decrease in -O0 object file size for a simple C++ source file using the standard library after this change. We now automatically infer the `const` and `nothrow` attributes on these now-builtin functions, in particular meaning that we get a warning for an unused call to one of these functions. In C++20 onwards, we disallow taking the addresses of these functions, per the C++20 "addressable function" rule. In earlier language modes, a compatibility warning is produced but the address can still be taken. The same infrastructure is extended to the existing MSVC builtin `__GetExceptionInfo`, which is now only recognized in namespace `std` like it always should have been. Reviewed By: aaron.ballman Differential Revision: https://reviews.llvm.org/D123345 Added: clang/test/CodeGenCXX/builtin-std-move.cpp clang/test/SemaCXX/builtin-std-move-nobuiltin.cpp clang/test/SemaCXX/builtin-std-move.cpp Modified: clang/docs/CommandGuide/clang.rst clang/docs/ReleaseNotes.rst clang/include/clang/Basic/Builtins.def clang/include/clang/Basic/Builtins.h clang/include/clang/Basic/DiagnosticSemaKinds.td clang/lib/AST/ExprConstant.cpp clang/lib/Analysis/BodyFarm.cpp clang/lib/Basic/Builtins.cpp clang/lib/CodeGen/CGBuiltin.cpp clang/lib/CodeGen/CGCall.cpp clang/lib/Sema/SemaChecking.cpp clang/lib/Sema/SemaDecl.cpp clang/lib/Sema/SemaExpr.cpp clang/lib/Sema/SemaExprCXX.cpp clang/lib/Sema/SemaInit.cpp clang/lib/Sema/SemaOverload.cpp clang/lib/Sema/SemaTemplateInstantiateDecl.cpp clang/test/Analysis/use-after-move.cpp clang/test/CodeGenCXX/microsoft-abi-throw.cpp clang/test/SemaCXX/unqualified-std-call-fixits.cpp clang/test/SemaCXX/unqualified-std-call.cpp clang/test/SemaCXX/warn-consumed-analysis.cpp Removed: ################################################################################ diff --git a/clang/docs/CommandGuide/clang.rst b/clang/docs/CommandGuide/clang.rst index aec62789a43e6..658a30458043e 100644 --- a/clang/docs/CommandGuide/clang.rst +++ b/clang/docs/CommandGuide/clang.rst @@ -252,8 +252,24 @@ Language Selection and Mode Options .. option:: -fno-builtin - Disable special handling and optimizations of builtin functions like - :c:func:`strlen` and :c:func:`malloc`. + Disable special handling and optimizations of well-known library functions, + like :c:func:`strlen` and :c:func:`malloc`. + +.. option:: -fno-builtin-<function> + + Disable special handling and optimizations for the specific library function. + For example, ``-fno-builtin-strlen`` removes any special handling for the + :c:func:`strlen` library function. + +.. option:: -fno-builtin-std-<function> + + Disable special handling and optimizations for the specific C++ standard + library function in namespace ``std``. For example, + ``-fno-builtin-std-move_if_noexcept`` removes any special handling for the + :cpp:func:`std::move_if_noexcept` library function. + + For C standard library functions that the C++ standard library also provides + in namespace ``std``, use :option:`-fno-builtin-\<function\>` instead. .. option:: -fmath-errno diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index c72028c718586..b2a5f6c366dd5 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -230,7 +230,10 @@ C2x Feature Support C++ Language Changes in Clang ----------------------------- -- ... +- Improved ``-O0`` code generation for calls to ``std::move``, ``std::forward``, + and ``std::move_if_noexcept``. These are now treated as compiler builtins and + implemented directly, rather than instantiating the definition from the + standard library. C++20 Feature Support ^^^^^^^^^^^^^^^^^^^^^ diff --git a/clang/include/clang/Basic/Builtins.def b/clang/include/clang/Basic/Builtins.def index 62e82cd36321d..c853229f13970 100644 --- a/clang/include/clang/Basic/Builtins.def +++ b/clang/include/clang/Basic/Builtins.def @@ -81,7 +81,9 @@ // builtin even if type doesn't match signature, and don't warn if we // can't be sure the type is right // F -> this is a libc/libm function with a '__builtin_' prefix added. -// f -> this is a libc/libm function without the '__builtin_' prefix. +// f -> this is a libc/libm function without a '__builtin_' prefix, or with +// 'z', a C++ standard library function in namespace std::. This builtin +// is disableable by '-fno-builtin-foo' / '-fno-builtin-std-foo'. // h -> this function requires a specific header or an explicit declaration. // i -> this is a runtime library implemented function without the // '__builtin_' prefix. It will be implemented in compiler-rt or libgcc. @@ -101,6 +103,8 @@ // V:N: -> requires vectors of at least N bits to be legal // C<N,M_0,...,M_k> -> callback behavior: argument N is called with argument // M_0, ..., M_k as payload +// z -> this is a C++ standard library function in (possibly-versioned) +// namespace std; implied by STDBUILTIN // FIXME: gcc has nonnull #if defined(BUILTIN) && !defined(LIBBUILTIN) @@ -111,6 +115,10 @@ # define LANGBUILTIN(ID, TYPE, ATTRS, BUILTIN_LANG) BUILTIN(ID, TYPE, ATTRS) #endif +#if defined(BUILTIN) && !defined(STDBUILTIN) +# define STDBUILTIN(ID, TYPE, ATTRS, HEADER) LIBBUILTIN(ID, TYPE, "zf" ATTRS, HEADER, CXX_LANG) +#endif + // Standard libc/libm functions: BUILTIN(__builtin_atan2 , "ddd" , "Fne") BUILTIN(__builtin_atan2f, "fff" , "Fne") @@ -919,7 +927,7 @@ LANGBUILTIN(__exception_info, "v*", "n", ALL_MS_LANGUAGES) LANGBUILTIN(_exception_info, "v*", "n", ALL_MS_LANGUAGES) LANGBUILTIN(__abnormal_termination, "i", "n", ALL_MS_LANGUAGES) LANGBUILTIN(_abnormal_termination, "i", "n", ALL_MS_LANGUAGES) -LANGBUILTIN(__GetExceptionInfo, "v*.", "ntu", ALL_MS_LANGUAGES) +LANGBUILTIN(__GetExceptionInfo, "v*.", "zntu", ALL_MS_LANGUAGES) LANGBUILTIN(_InterlockedAnd8, "ccD*c", "n", ALL_MS_LANGUAGES) LANGBUILTIN(_InterlockedAnd16, "ssD*s", "n", ALL_MS_LANGUAGES) LANGBUILTIN(_InterlockedAnd, "NiNiD*Ni", "n", ALL_MS_LANGUAGES) @@ -1543,6 +1551,11 @@ LIBBUILTIN(_Block_object_assign, "vv*vC*iC", "f", "Blocks.h", ALL_LANGUAGES) LIBBUILTIN(_Block_object_dispose, "vvC*iC", "f", "Blocks.h", ALL_LANGUAGES) // FIXME: Also declare NSConcreteGlobalBlock and NSConcreteStackBlock. +// C++11 +STDBUILTIN(move, "v&v&", "ncTh", "utility") +STDBUILTIN(move_if_noexcept, "v&v&", "ncTh", "utility") +STDBUILTIN(forward, "v&v&", "ncTh", "utility") + // Annotation function BUILTIN(__builtin_annotation, "v.", "tn") diff --git a/clang/include/clang/Basic/Builtins.h b/clang/include/clang/Basic/Builtins.h index 2926e0fa2c8d6..a82e15730f992 100644 --- a/clang/include/clang/Basic/Builtins.h +++ b/clang/include/clang/Basic/Builtins.h @@ -138,6 +138,10 @@ class Context { /// Determines whether this builtin is a predefined libc/libm /// function, such as "malloc", where we know the signature a /// priori. + /// In C, such functions behave as if they are predeclared, + /// possibly with a warning on first use. In Objective-C and C++, + /// they do not, but they are recognized as builtins once we see + /// a declaration. bool isPredefinedLibFunction(unsigned ID) const { return strchr(getRecord(ID).Attributes, 'f') != nullptr; } @@ -156,6 +160,23 @@ class Context { return strchr(getRecord(ID).Attributes, 'i') != nullptr; } + /// Determines whether this builtin is a C++ standard library function + /// that lives in (possibly-versioned) namespace std, possibly a template + /// specialization, where the signature is determined by the standard library + /// declaration. + bool isInStdNamespace(unsigned ID) const { + return strchr(getRecord(ID).Attributes, 'z') != nullptr; + } + + /// Determines whether this builtin can have its address taken with no + /// special action required. + bool isDirectlyAddressable(unsigned ID) const { + // Most standard library functions can have their addresses taken. C++ + // standard library functions formally cannot in C++20 onwards, and when + // we allow it, we need to ensure we instantiate a definition. + return isPredefinedLibFunction(ID) && !isInStdNamespace(ID); + } + /// Determines whether this builtin has custom typechecking. bool hasCustomTypechecking(unsigned ID) const { return strchr(getRecord(ID).Attributes, 't') != nullptr; @@ -237,10 +258,6 @@ class Context { private: const Info &getRecord(unsigned ID) const; - /// Is this builtin supported according to the given language options? - bool builtinIsSupported(const Builtin::Info &BuiltinInfo, - const LangOptions &LangOpts); - /// Helper function for isPrintfLike and isScanfLike. bool isLike(unsigned ID, unsigned &FormatIdx, bool &HasVAListArg, const char *Fmt) const; diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td index e79a40d62381f..cebd24302f1d1 100644 --- a/clang/include/clang/Basic/DiagnosticSemaKinds.td +++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td @@ -6586,6 +6586,15 @@ def warn_self_move : Warning< "explicitly moving variable of type %0 to itself">, InGroup<SelfMove>, DefaultIgnore; +def err_builtin_move_forward_unsupported : Error< + "unsupported signature for '%select{std::move|std::forward}0'">; +def err_use_of_unaddressable_function : Error< + "taking address of non-addressable standard library function">; +// FIXME: This should also be in -Wc++23-compat once we have it. +def warn_cxx20_compat_use_of_unaddressable_function : Warning< + "taking address of non-addressable standard library function " + "is incompatible with C++20">, InGroup<CXX20Compat>; + def warn_redundant_move_on_return : Warning< "redundant move in return statement">, InGroup<RedundantMove>, DefaultIgnore; diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp index 6fe5d77a33fe5..ce007edca0fc6 100644 --- a/clang/lib/AST/ExprConstant.cpp +++ b/clang/lib/AST/ExprConstant.cpp @@ -8127,6 +8127,7 @@ class LValueExprEvaluator bool VisitVarDecl(const Expr *E, const VarDecl *VD); bool VisitUnaryPreIncDec(const UnaryOperator *UO); + bool VisitCallExpr(const CallExpr *E); bool VisitDeclRefExpr(const DeclRefExpr *E); bool VisitPredefinedExpr(const PredefinedExpr *E) { return Success(E); } bool VisitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *E); @@ -8292,6 +8293,19 @@ bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) { return Success(*V, E); } +bool LValueExprEvaluator::VisitCallExpr(const CallExpr *E) { + switch (unsigned BuiltinOp = E->getBuiltinCallee()) { + case Builtin::BImove: + case Builtin::BImove_if_noexcept: + case Builtin::BIforward: + if (cast<FunctionDecl>(E->getCalleeDecl())->isConstexpr()) + return Visit(E->getArg(0)); + break; + } + + return ExprEvaluatorBaseTy::VisitCallExpr(E); +} + bool LValueExprEvaluator::VisitMaterializeTemporaryExpr( const MaterializeTemporaryExpr *E) { // Walk through the expression to find the materialized temporary itself. diff --git a/clang/lib/Analysis/BodyFarm.cpp b/clang/lib/Analysis/BodyFarm.cpp index 92c236ed9080c..e8c2d4421c618 100644 --- a/clang/lib/Analysis/BodyFarm.cpp +++ b/clang/lib/Analysis/BodyFarm.cpp @@ -20,6 +20,7 @@ #include "clang/AST/ExprObjC.h" #include "clang/AST/NestedNameSpecifier.h" #include "clang/Analysis/CodeInjector.h" +#include "clang/Basic/Builtins.h" #include "clang/Basic/OperatorKinds.h" #include "llvm/ADT/StringSwitch.h" #include "llvm/Support/Debug.h" @@ -86,6 +87,9 @@ class ASTMaker { ImplicitCastExpr *makeImplicitCast(const Expr *Arg, QualType Ty, CastKind CK = CK_LValueToRValue); + /// Create a cast to reference type. + CastExpr *makeReferenceCast(const Expr *Arg, QualType Ty); + /// Create an Objective-C bool literal. ObjCBoolLiteralExpr *makeObjCBool(bool Val); @@ -173,6 +177,16 @@ ImplicitCastExpr *ASTMaker::makeImplicitCast(const Expr *Arg, QualType Ty, /* FPFeatures */ FPOptionsOverride()); } +CastExpr *ASTMaker::makeReferenceCast(const Expr *Arg, QualType Ty) { + assert(Ty->isReferenceType()); + return CXXStaticCastExpr::Create( + C, Ty.getNonReferenceType(), + Ty->isLValueReferenceType() ? VK_LValue : VK_XValue, CK_NoOp, + const_cast<Expr *>(Arg), /*CXXCastPath=*/nullptr, + /*Written=*/C.getTrivialTypeSourceInfo(Ty), FPOptionsOverride(), + SourceLocation(), SourceLocation(), SourceRange()); +} + Expr *ASTMaker::makeIntegralCast(const Expr *Arg, QualType Ty) { if (Arg->getType() == Ty) return const_cast<Expr*>(Arg); @@ -296,6 +310,22 @@ static CallExpr *create_call_once_lambda_call(ASTContext &C, ASTMaker M, /*FPFeatures=*/FPOptionsOverride()); } +/// Create a fake body for 'std::move' or 'std::forward'. This is just: +/// +/// \code +/// return static_cast<return_type>(param); +/// \endcode +static Stmt *create_std_move_forward(ASTContext &C, const FunctionDecl *D) { + LLVM_DEBUG(llvm::dbgs() << "Generating body for std::move / std::forward\n"); + + ASTMaker M(C); + + QualType ReturnType = D->getType()->castAs<FunctionType>()->getReturnType(); + Expr *Param = M.makeDeclRefExpr(D->getParamDecl(0)); + Expr *Cast = M.makeReferenceCast(Param, ReturnType); + return M.makeReturn(Cast); +} + /// Create a fake body for std::call_once. /// Emulates the following function body: /// @@ -681,8 +711,19 @@ Stmt *BodyFarm::getBody(const FunctionDecl *D) { FunctionFarmer FF; - if (Name.startswith("OSAtomicCompareAndSwap") || - Name.startswith("objc_atomicCompareAndSwap")) { + if (unsigned BuiltinID = D->getBuiltinID()) { + switch (BuiltinID) { + case Builtin::BImove: + case Builtin::BImove_if_noexcept: + case Builtin::BIforward: + FF = create_std_move_forward; + break; + default: + FF = nullptr; + break; + } + } else if (Name.startswith("OSAtomicCompareAndSwap") || + Name.startswith("objc_atomicCompareAndSwap")) { FF = create_OSAtomicCompareAndSwap; } else if (Name == "call_once" && D->getDeclContext()->isStdNamespace()) { FF = create_call_once; diff --git a/clang/lib/Basic/Builtins.cpp b/clang/lib/Basic/Builtins.cpp index 6d278e9c4a229..ef8bb562ac17e 100644 --- a/clang/lib/Basic/Builtins.cpp +++ b/clang/lib/Basic/Builtins.cpp @@ -48,18 +48,22 @@ void Builtin::Context::InitializeTarget(const TargetInfo &Target, } bool Builtin::Context::isBuiltinFunc(llvm::StringRef FuncName) { - for (unsigned i = Builtin::NotBuiltin + 1; i != Builtin::FirstTSBuiltin; ++i) - if (FuncName.equals(BuiltinInfo[i].Name)) + bool InStdNamespace = FuncName.consume_front("std-"); + for (unsigned i = Builtin::NotBuiltin + 1; i != Builtin::FirstTSBuiltin; + ++i) { + if (FuncName.equals(BuiltinInfo[i].Name) && + (bool)strchr(BuiltinInfo[i].Attributes, 'z') == InStdNamespace) return strchr(BuiltinInfo[i].Attributes, 'f') != nullptr; + } return false; } -bool Builtin::Context::builtinIsSupported(const Builtin::Info &BuiltinInfo, - const LangOptions &LangOpts) { +/// Is this builtin supported according to the given language options? +static bool builtinIsSupported(const Builtin::Info &BuiltinInfo, + const LangOptions &LangOpts) { bool BuiltinsUnsupported = - (LangOpts.NoBuiltin || LangOpts.isNoBuiltinFunc(BuiltinInfo.Name)) && - strchr(BuiltinInfo.Attributes, 'f'); + LangOpts.NoBuiltin && strchr(BuiltinInfo.Attributes, 'f') != nullptr; bool CorBuiltinsUnsupported = !LangOpts.Coroutines && (BuiltinInfo.Langs & COR_LANG); bool MathBuiltinsUnsupported = @@ -111,6 +115,19 @@ void Builtin::Context::initializeBuiltins(IdentifierTable &Table, for (unsigned i = 0, e = AuxTSRecords.size(); i != e; ++i) Table.get(AuxTSRecords[i].Name) .setBuiltinID(i + Builtin::FirstTSBuiltin + TSRecords.size()); + + // Step #4: Unregister any builtins specified by -fno-builtin-foo. + for (llvm::StringRef Name : LangOpts.NoBuiltinFuncs) { + bool InStdNamespace = Name.consume_front("std-"); + auto NameIt = Table.find(Name); + if (NameIt != Table.end()) { + unsigned ID = NameIt->second->getBuiltinID(); + if (ID != Builtin::NotBuiltin && isPredefinedLibFunction(ID) && + isInStdNamespace(ID) == InStdNamespace) { + Table.get(Name).setBuiltinID(Builtin::NotBuiltin); + } + } + } } unsigned Builtin::Context::getRequiredVectorWidth(unsigned ID) const { @@ -190,8 +207,7 @@ bool Builtin::Context::performsCallback(unsigned ID, } bool Builtin::Context::canBeRedeclared(unsigned ID) const { - return ID == Builtin::NotBuiltin || - ID == Builtin::BI__va_start || - (!hasReferenceArgsOrResult(ID) && - !hasCustomTypechecking(ID)); + return ID == Builtin::NotBuiltin || ID == Builtin::BI__va_start || + (!hasReferenceArgsOrResult(ID) && !hasCustomTypechecking(ID)) || + isInStdNamespace(ID); } diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp index 3adabcbf4bc97..dc4b104201632 100644 --- a/clang/lib/CodeGen/CGBuiltin.cpp +++ b/clang/lib/CodeGen/CGBuiltin.cpp @@ -4725,6 +4725,11 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID, } break; + // C++ std:: builtins. + case Builtin::BImove: + case Builtin::BImove_if_noexcept: + case Builtin::BIforward: + return RValue::get(EmitLValue(E->getArg(0)).getPointer(*this)); case Builtin::BI__GetExceptionInfo: { if (llvm::GlobalVariable *GV = CGM.getCXXABI().getThrowInfo(FD->getParamDecl(0)->getType())) diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp index e6a5fd1f4f985..d69455d650f43 100644 --- a/clang/lib/CodeGen/CGCall.cpp +++ b/clang/lib/CodeGen/CGCall.cpp @@ -1805,6 +1805,8 @@ void CodeGenModule::getDefaultFunctionAttributes(StringRef Name, if (AttrOnCallSite) { // Attributes that should go on the call site only. + // FIXME: Look for 'BuiltinAttr' on the function rather than re-checking + // the -fno-builtin-foo list. if (!CodeGenOpts.SimplifyLibCalls || LangOpts.isNoBuiltinFunc(Name)) FuncAttrs.addAttribute(llvm::Attribute::NoBuiltin); if (!CodeGenOpts.TrapFuncName.empty()) diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp index 03f9b692c0631..870f1331069f2 100644 --- a/clang/lib/Sema/SemaChecking.cpp +++ b/clang/lib/Sema/SemaChecking.cpp @@ -2130,6 +2130,18 @@ Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID, TheCall->setType(Context.VoidPtrTy); break; + case Builtin::BImove: + case Builtin::BImove_if_noexcept: + case Builtin::BIforward: + if (checkArgCount(*this, TheCall, 1)) + return ExprError(); + if (!Context.hasSameUnqualifiedType(TheCall->getType(), + TheCall->getArg(0)->getType())) { + Diag(TheCall->getBeginLoc(), diag::err_builtin_move_forward_unsupported) + << (BuiltinID == Builtin::BIforward); + return ExprError(); + } + break; // OpenCL v2.0, s6.13.16 - Pipe functions case Builtin::BIread_pipe: case Builtin::BIwrite_pipe: diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp index 499c70e087898..cacd08a62a320 100644 --- a/clang/lib/Sema/SemaDecl.cpp +++ b/clang/lib/Sema/SemaDecl.cpp @@ -9269,6 +9269,29 @@ static Scope *getTagInjectionScope(Scope *S, const LangOptions &LangOpts) { return S; } +/// Determine whether a declaration matches a known function in namespace std. +static bool isStdBuiltin(ASTContext &Ctx, FunctionDecl *FD, + unsigned BuiltinID) { + switch (BuiltinID) { + case Builtin::BI__GetExceptionInfo: + // No type checking whatsoever. + return Ctx.getTargetInfo().getCXXABI().isMicrosoft(); + + case Builtin::BImove: + case Builtin::BImove_if_noexcept: + case Builtin::BIforward: { + // Ensure that we don't treat the algorithm + // OutputIt std::move(InputIt, InputIt, OutputIt) + // as the builtin std::move. + const auto *FPT = FD->getType()->castAs<FunctionProtoType>(); + return FPT->getNumParams() == 1 && !FPT->isVariadic(); + } + + default: + return false; + } +} + NamedDecl* Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC, TypeSourceInfo *TInfo, LookupResult &Previous, @@ -10121,28 +10144,30 @@ Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC, // If this is the first declaration of a library builtin function, add // attributes as appropriate. - if (!D.isRedeclaration() && - NewFD->getDeclContext()->getRedeclContext()->isFileContext()) { + if (!D.isRedeclaration()) { if (IdentifierInfo *II = Previous.getLookupName().getAsIdentifierInfo()) { if (unsigned BuiltinID = II->getBuiltinID()) { - if (NewFD->getLanguageLinkage() == CLanguageLinkage) { - // Validate the type matches unless this builtin is specified as - // matching regardless of its declared type. - if (Context.BuiltinInfo.allowTypeMismatch(BuiltinID)) { - NewFD->addAttr(BuiltinAttr::CreateImplicit(Context, BuiltinID)); - } else { - ASTContext::GetBuiltinTypeError Error; - LookupNecessaryTypesForBuiltin(S, BuiltinID); - QualType BuiltinType = Context.GetBuiltinType(BuiltinID, Error); - - if (!Error && !BuiltinType.isNull() && - Context.hasSameFunctionTypeIgnoringExceptionSpec( - NewFD->getType(), BuiltinType)) + bool InStdNamespace = Context.BuiltinInfo.isInStdNamespace(BuiltinID); + if (!InStdNamespace && + NewFD->getDeclContext()->getRedeclContext()->isFileContext()) { + if (NewFD->getLanguageLinkage() == CLanguageLinkage) { + // Validate the type matches unless this builtin is specified as + // matching regardless of its declared type. + if (Context.BuiltinInfo.allowTypeMismatch(BuiltinID)) { NewFD->addAttr(BuiltinAttr::CreateImplicit(Context, BuiltinID)); + } else { + ASTContext::GetBuiltinTypeError Error; + LookupNecessaryTypesForBuiltin(S, BuiltinID); + QualType BuiltinType = Context.GetBuiltinType(BuiltinID, Error); + + if (!Error && !BuiltinType.isNull() && + Context.hasSameFunctionTypeIgnoringExceptionSpec( + NewFD->getType(), BuiltinType)) + NewFD->addAttr(BuiltinAttr::CreateImplicit(Context, BuiltinID)); + } } - } else if (BuiltinID == Builtin::BI__GetExceptionInfo && - Context.getTargetInfo().getCXXABI().isMicrosoft()) { - // FIXME: We should consider this a builtin only in the std namespace. + } else if (InStdNamespace && NewFD->isInStdNamespace() && + isStdBuiltin(Context, NewFD, BuiltinID)) { NewFD->addAttr(BuiltinAttr::CreateImplicit(Context, BuiltinID)); } } diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp index 334ece62c2bea..cfebd3cb928cf 100644 --- a/clang/lib/Sema/SemaExpr.cpp +++ b/clang/lib/Sema/SemaExpr.cpp @@ -3395,7 +3395,7 @@ ExprResult Sema::BuildDeclarationNameExpr( case Decl::Function: { if (unsigned BID = cast<FunctionDecl>(VD)->getBuiltinID()) { - if (!Context.BuiltinInfo.isPredefinedLibFunction(BID)) { + if (!Context.BuiltinInfo.isDirectlyAddressable(BID)) { type = Context.BuiltinFnTy; valueKind = VK_PRValue; break; @@ -20528,7 +20528,8 @@ ExprResult Sema::CheckPlaceholderExpr(Expr *E) { auto *DRE = dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()); if (DRE) { auto *FD = cast<FunctionDecl>(DRE->getDecl()); - if (FD->getBuiltinID() == Builtin::BI__noop) { + unsigned BuiltinID = FD->getBuiltinID(); + if (BuiltinID == Builtin::BI__noop) { E = ImpCastExprToType(E, Context.getPointerType(FD->getType()), CK_BuiltinFnToFnPtr) .get(); @@ -20536,6 +20537,36 @@ ExprResult Sema::CheckPlaceholderExpr(Expr *E) { VK_PRValue, SourceLocation(), FPOptionsOverride()); } + + if (Context.BuiltinInfo.isInStdNamespace(BuiltinID)) { + // Any use of these other than a direct call is ill-formed as of C++20, + // because they are not addressable functions. In earlier language + // modes, warn and force an instantiation of the real body. + Diag(E->getBeginLoc(), + getLangOpts().CPlusPlus20 + ? diag::err_use_of_unaddressable_function + : diag::warn_cxx20_compat_use_of_unaddressable_function); + if (FD->isImplicitlyInstantiable()) { + // Require a definition here because a normal attempt at + // instantiation for a builtin will be ignored, and we won't try + // again later. We assume that the definition of the template + // precedes this use. + InstantiateFunctionDefinition(E->getBeginLoc(), FD, + /*Recursive=*/false, + /*DefinitionRequired=*/true, + /*AtEndOfTU=*/false); + } + // Produce a properly-typed reference to the function. + CXXScopeSpec SS; + SS.Adopt(DRE->getQualifierLoc()); + TemplateArgumentListInfo TemplateArgs; + DRE->copyTemplateArgumentsInto(TemplateArgs); + return BuildDeclRefExpr( + FD, FD->getType(), VK_LValue, DRE->getNameInfo(), + DRE->hasQualifier() ? &SS : nullptr, DRE->getFoundDecl(), + DRE->getTemplateKeywordLoc(), + DRE->hasExplicitTemplateArgs() ? &TemplateArgs : nullptr); + } } Diag(E->getBeginLoc(), diag::err_builtin_fn_use); diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp index aad9574e9e694..e765d1ff9760d 100644 --- a/clang/lib/Sema/SemaExprCXX.cpp +++ b/clang/lib/Sema/SemaExprCXX.cpp @@ -4236,6 +4236,14 @@ Sema::PerformImplicitConversion(Expr *From, QualType ToType, return ExprError(); From = FixOverloadedFunctionReference(From, Found, Fn); + + // We might get back another placeholder expression if we resolved to a + // builtin. + ExprResult Checked = CheckPlaceholderExpr(From); + if (Checked.isInvalid()) + return ExprError(); + + From = Checked.get(); FromType = From->getType(); } diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp index 233be547bf118..f76fd92d09d3b 100644 --- a/clang/lib/Sema/SemaInit.cpp +++ b/clang/lib/Sema/SemaInit.cpp @@ -8215,6 +8215,10 @@ ExprResult InitializationSequence::Perform(Sema &S, CurInit = S.FixOverloadedFunctionReference(CurInit, Step->Function.FoundDecl, Step->Function.Function); + // We might get back another placeholder expression if we resolved to a + // builtin. + if (!CurInit.isInvalid()) + CurInit = S.CheckPlaceholderExpr(CurInit.get()); break; case SK_CastDerivedToBasePRValue: diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp index 33271609a0081..1add971a81a02 100644 --- a/clang/lib/Sema/SemaOverload.cpp +++ b/clang/lib/Sema/SemaOverload.cpp @@ -1747,13 +1747,6 @@ static bool IsStandardConversion(Sema &S, Expr* From, QualType ToType, "Non-address-of operator for overloaded function expression"); FromType = S.Context.getPointerType(FromType); } - - // Check that we've computed the proper type after overload resolution. - // FIXME: FixOverloadedFunctionReference has side-effects; we shouldn't - // be calling it from within an NDEBUG block. - assert(S.Context.hasSameType( - FromType, - S.FixOverloadedFunctionReference(From, AccessPair, Fn)->getType())); } else { return false; } @@ -15188,10 +15181,9 @@ Expr *Sema::FixOverloadedFunctionReference(Expr *E, DeclAccessPair Found, if (SubExpr == UnOp->getSubExpr()) return UnOp; - return UnaryOperator::Create( - Context, SubExpr, UO_AddrOf, Context.getPointerType(SubExpr->getType()), - VK_PRValue, OK_Ordinary, UnOp->getOperatorLoc(), false, - CurFPFeatureOverrides()); + // FIXME: This can't currently fail, but in principle it could. + return CreateBuiltinUnaryOp(UnOp->getOperatorLoc(), UO_AddrOf, SubExpr) + .get(); } if (UnresolvedLookupExpr *ULE = dyn_cast<UnresolvedLookupExpr>(E)) { @@ -15202,10 +15194,20 @@ Expr *Sema::FixOverloadedFunctionReference(Expr *E, DeclAccessPair Found, TemplateArgs = &TemplateArgsBuffer; } - DeclRefExpr *DRE = - BuildDeclRefExpr(Fn, Fn->getType(), VK_LValue, ULE->getNameInfo(), - ULE->getQualifierLoc(), Found.getDecl(), - ULE->getTemplateKeywordLoc(), TemplateArgs); + QualType Type = Fn->getType(); + ExprValueKind ValueKind = getLangOpts().CPlusPlus ? VK_LValue : VK_PRValue; + + // FIXME: Duplicated from BuildDeclarationNameExpr. + if (unsigned BID = Fn->getBuiltinID()) { + if (!Context.BuiltinInfo.isDirectlyAddressable(BID)) { + Type = Context.BuiltinFnTy; + ValueKind = VK_PRValue; + } + } + + DeclRefExpr *DRE = BuildDeclRefExpr( + Fn, Type, ValueKind, ULE->getNameInfo(), ULE->getQualifierLoc(), + Found.getDecl(), ULE->getTemplateKeywordLoc(), TemplateArgs); DRE->setHadMultipleCandidates(ULE->getNumDecls() > 1); return DRE; } diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp index 9d0dc8cad46b8..8b0147fc66c36 100644 --- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp +++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp @@ -4771,6 +4771,12 @@ void Sema::InstantiateFunctionDefinition(SourceLocation PointOfInstantiation, if (TSK == TSK_ExplicitSpecialization) return; + // Never implicitly instantiate a builtin; we don't actually need a function + // body. + if (Function->getBuiltinID() && TSK == TSK_ImplicitInstantiation && + !DefinitionRequired) + return; + // Don't instantiate a definition if we already have one. const FunctionDecl *ExistingDefn = nullptr; if (Function->isDefined(ExistingDefn, diff --git a/clang/test/Analysis/use-after-move.cpp b/clang/test/Analysis/use-after-move.cpp index d1278cad4c4f2..ce9b26f15360e 100644 --- a/clang/test/Analysis/use-after-move.cpp +++ b/clang/test/Analysis/use-after-move.cpp @@ -244,7 +244,7 @@ void reinitializationTest(int i) { A a; if (i == 1) { // peaceful-note 2 {{'i' is not equal to 1}} // peaceful-note@-1 2 {{Taking false branch}} - std::move(a); + (void)std::move(a); } if (i == 2) { // peaceful-note 2 {{'i' is not equal to 2}} // peaceful-note@-1 2 {{Taking false branch}} @@ -494,7 +494,7 @@ void templateArgIsNotUseTest() { // Moves of global variables are not reported. A global_a; void globalVariablesTest() { - std::move(global_a); + (void)std::move(global_a); global_a.foo(); // no-warning } diff --git a/clang/test/CodeGenCXX/builtin-std-move.cpp b/clang/test/CodeGenCXX/builtin-std-move.cpp new file mode 100644 index 0000000000000..29107c4e162a8 --- /dev/null +++ b/clang/test/CodeGenCXX/builtin-std-move.cpp @@ -0,0 +1,52 @@ +// RUN: %clang_cc1 -triple=x86_64-linux-gnu -emit-llvm -o - -std=c++17 %s | FileCheck %s --implicit-check-not=@_ZSt4move + +namespace std { + template<typename T> constexpr T &&move(T &val) { return static_cast<T&&>(val); } + template<typename T> constexpr T &&move_if_noexcept(T &val); + template<typename T> constexpr T &&forward(T &val); + + // Not the builtin. + template<typename T, typename U> T move(U source, U source_end, T dest); +} + +class T {}; +extern "C" void take(T &&); + +T a; + +// Check emission of a constant-evaluated call. +// CHECK-DAG: @move_a = constant %[[T:.*]]* @a +T &&move_a = std::move(a); +// CHECK-DAG: @move_if_noexcept_a = constant %[[T]]* @a +T &&move_if_noexcept_a = std::move_if_noexcept(a); +// CHECK-DAG: @forward_a = constant %[[T]]* @a +T &forward_a = std::forward<T&>(a); + +// Check emission of a non-constant call. +// CHECK-LABEL: define {{.*}} void @test +extern "C" void test(T &t) { + // CHECK: store %[[T]]* %{{.*}}, %[[T]]** %[[T_REF:[^,]*]] + // CHECK: %0 = load %[[T]]*, %[[T]]** %[[T_REF]] + // CHECK: call void @take(%[[T]]* {{.*}} %0) + take(std::move(t)); + // CHECK: %1 = load %[[T]]*, %[[T]]** %[[T_REF]] + // CHECK: call void @take(%[[T]]* {{.*}} %1) + take(std::move_if_noexcept(t)); + // CHECK: %2 = load %[[T]]*, %[[T]]** %[[T_REF]] + // CHECK: call void @take(%[[T]]* {{.*}} %2) + take(std::forward<T&&>(t)); + + // CHECK: call {{.*}} @_ZSt4moveI1TS0_ET_T0_S2_S1_ + std::move(t, t, t); +} + +// CHECK: declare {{.*}} @_ZSt4moveI1TS0_ET_T0_S2_S1_ + +// Check that we instantiate and emit if the address is taken. +// CHECK-LABEL: define {{.*}} @use_address +extern "C" void *use_address() { + // CHECK: ret {{.*}} @_ZSt4moveIiEOT_RS0_ + return (void*)&std::move<int>; +} + +// CHECK: define {{.*}} i32* @_ZSt4moveIiEOT_RS0_(i32* diff --git a/clang/test/CodeGenCXX/microsoft-abi-throw.cpp b/clang/test/CodeGenCXX/microsoft-abi-throw.cpp index 92849598cf063..aa79935e42ded 100644 --- a/clang/test/CodeGenCXX/microsoft-abi-throw.cpp +++ b/clang/test/CodeGenCXX/microsoft-abi-throw.cpp @@ -1,5 +1,4 @@ // RUN: %clang_cc1 -no-opaque-pointers -emit-llvm -o - -triple=i386-pc-win32 -std=c++11 %s -fcxx-exceptions -fms-extensions | FileCheck %s -// RUN: %clang_cc1 -no-opaque-pointers -emit-llvm -o - -triple=i386-pc-win32 -std=c++11 %s -fcxx-exceptions -fms-extensions -DSTD | FileCheck %s // CHECK-DAG: @"??_R0?AUY@@@8" = linkonce_odr global %rtti.TypeDescriptor7 { i8** @"??_7type_info@@6B@", i8* null, [8 x i8] c".?AUY@@\00" }, comdat // CHECK-DAG: @"_CT??_R0?AUY@@@8??0Y@@QAE@ABU0@@Z8" = linkonce_odr unnamed_addr constant %eh.CatchableType { i32 4, i8* bitcast (%rtti.TypeDescriptor7* @"??_R0?AUY@@@8" to i8*), i32 0, i32 -1, i32 0, i32 8, i8* bitcast (%struct.Y* (%struct.Y*, %struct.Y*, i32)* @"??0Y@@QAE@ABU0@@Z" to i8*) }, section ".xdata", comdat @@ -134,15 +133,10 @@ void h() { throw nullptr; } -#ifdef STD namespace std { template <typename T> void *__GetExceptionInfo(T); } -#else -template <typename T> -void *__GetExceptionInfo(T); -#endif using namespace std; void *GetExceptionInfo_test0() { diff --git a/clang/test/SemaCXX/builtin-std-move-nobuiltin.cpp b/clang/test/SemaCXX/builtin-std-move-nobuiltin.cpp new file mode 100644 index 0000000000000..9185bd87bf8ab --- /dev/null +++ b/clang/test/SemaCXX/builtin-std-move-nobuiltin.cpp @@ -0,0 +1,20 @@ +// RUN: %clang_cc1 -std=c++20 -verify %s -DBUILTIN=builtin +// RUN: %clang_cc1 -std=c++20 -verify %s -DBUILTIN=nobuiltin -fno-builtin +// RUN: %clang_cc1 -std=c++20 -verify %s -DBUILTIN=nobuiltin -fno-builtin-std-move -fno-builtin-std-move_if_noexcept -fno-builtin-std-forward +// RUN: %clang_cc1 -std=c++20 -verify %s -DBUILTIN=nobuiltin -ffreestanding +// expected-no-diagnostics + +int nobuiltin; + +namespace std { + template<typename T> constexpr T &&move(T &x) { return (T&&)nobuiltin; } + template<typename T> constexpr T &&move_if_noexcept(T &x) { return (T&&)nobuiltin; } + template<typename T> constexpr T &&forward(T &x) { return (T&&)nobuiltin; } +} + +template<typename T> constexpr T *addr(T &&r) { return &r; } + +int builtin; +static_assert(addr(std::move(builtin)) == &BUILTIN); +static_assert(addr(std::move_if_noexcept(builtin)) == &BUILTIN); +static_assert(addr(std::forward(builtin)) == &BUILTIN); diff --git a/clang/test/SemaCXX/builtin-std-move.cpp b/clang/test/SemaCXX/builtin-std-move.cpp new file mode 100644 index 0000000000000..6a263239ae6b0 --- /dev/null +++ b/clang/test/SemaCXX/builtin-std-move.cpp @@ -0,0 +1,90 @@ +// RUN: %clang_cc1 -std=c++17 -verify %s +// RUN: %clang_cc1 -std=c++17 -verify %s -DNO_CONSTEXPR +// RUN: %clang_cc1 -std=c++20 -verify %s + +namespace std { +#ifndef NO_CONSTEXPR +#define CONSTEXPR constexpr +#else +#define CONSTEXPR +#endif + + template<typename T> CONSTEXPR T &&move(T &x) { + static_assert(T::moveable, "instantiated move"); // expected-error {{no member named 'moveable' in 'B'}} + // expected-error@-1 {{no member named 'moveable' in 'C'}} + return static_cast<T&&>(x); + } + + // Unrelated move functions are not the builtin. + template<typename T> CONSTEXPR int move(T, T) { return 5; } + + template<typename T, bool Rref> struct ref { using type = T&; }; + template<typename T> struct ref<T, true> { using type = T&&; }; + + template<typename T> CONSTEXPR auto move_if_noexcept(T &x) -> typename ref<T, noexcept(T(static_cast<T&&>(x)))>::type { + static_assert(T::moveable, "instantiated move_if_noexcept"); // expected-error {{no member named 'moveable' in 'B'}} + return static_cast<typename ref<T, noexcept(T(static_cast<T&&>(x)))>::type>(x); + } + + template<typename T> struct remove_reference { using type = T; }; + template<typename T> struct remove_reference<T&> { using type = T; }; + template<typename T> struct remove_reference<T&&> { using type = T; }; + + template<typename T> CONSTEXPR T &&forward(typename remove_reference<T>::type &x) { + static_assert(T::moveable, "instantiated forward"); // expected-error {{no member named 'moveable' in 'B'}} + // expected-error@-1 {{no member named 'moveable' in 'C'}} + return static_cast<T&&>(x); + } +} + +// Note: this doesn't have a 'moveable' member. Instantiation of the above +// functions will fail if it's attempted. +struct A {}; +constexpr bool f(A a) { // #f + A &&move = std::move(a); // #call + A &&move_if_noexcept = std::move_if_noexcept(a); + A &&forward1 = std::forward<A>(a); + A &forward2 = std::forward<A&>(a); + return &move == &a && &move_if_noexcept == &a && + &forward1 == &a && &forward2 == &a && + std::move(a, a) == 5; +} + +#ifndef NO_CONSTEXPR +static_assert(f({}), "should be constexpr"); +#else +// expected-error@#f {{never produces a constant expression}} +// expected-note@#call {{}} +#endif + +struct B {}; +B &&(*pMove)(B&) = std::move; // #1 expected-note {{instantiation of}} +B &&(*pMoveIfNoexcept)(B&) = &std::move_if_noexcept; // #2 expected-note {{instantiation of}} +B &&(*pForward)(B&) = &std::forward<B>; // #3 expected-note {{instantiation of}} +int (*pUnrelatedMove)(B, B) = std::move; + +struct C {}; +C &&(&rMove)(C&) = std::move; // #4 expected-note {{instantiation of}} +C &&(&rForward)(C&) = std::forward<C>; // #5 expected-note {{instantiation of}} +int (&rUnrelatedMove)(B, B) = std::move; + +#if __cplusplus <= 201703L +// expected-warning@#1 {{non-addressable}} +// expected-warning@#2 {{non-addressable}} +// expected-warning@#3 {{non-addressable}} +// expected-warning@#4 {{non-addressable}} +// expected-warning@#5 {{non-addressable}} +#else +// expected-error@#1 {{non-addressable}} +// expected-error@#2 {{non-addressable}} +// expected-error@#3 {{non-addressable}} +// expected-error@#4 {{non-addressable}} +// expected-error@#5 {{non-addressable}} +#endif + +void attribute_const() { + int n; + std::move(n); // expected-warning {{ignoring return value}} + std::move_if_noexcept(n); // expected-warning {{ignoring return value}} + std::forward<int>(n); // expected-warning {{ignoring return value}} +} diff --git a/clang/test/SemaCXX/unqualified-std-call-fixits.cpp b/clang/test/SemaCXX/unqualified-std-call-fixits.cpp index 0b2d70c0360a3..d6f8e5e2b95ed 100644 --- a/clang/test/SemaCXX/unqualified-std-call-fixits.cpp +++ b/clang/test/SemaCXX/unqualified-std-call-fixits.cpp @@ -6,9 +6,9 @@ namespace std { -void move(auto &&a) {} +int &&move(auto &&a) { return a; } -void forward(auto &a) {} +int &&forward(auto &a) { return a; } } // namespace std @@ -16,8 +16,8 @@ using namespace std; void f() { int i = 0; - move(i); // expected-warning {{unqualified call to std::move}} - // CHECK: {{^}} std:: - forward(i); // expected-warning {{unqualified call to std::forward}} - // CHECK: {{^}} std:: + (void)move(i); // expected-warning {{unqualified call to std::move}} + // CHECK: {{^}} (void)std::move + (void)forward(i); // expected-warning {{unqualified call to std::forward}} + // CHECK: {{^}} (void)std::forward } diff --git a/clang/test/SemaCXX/unqualified-std-call.cpp b/clang/test/SemaCXX/unqualified-std-call.cpp index fa66ae9f8e321..0c78c26d063a9 100644 --- a/clang/test/SemaCXX/unqualified-std-call.cpp +++ b/clang/test/SemaCXX/unqualified-std-call.cpp @@ -1,17 +1,17 @@ -// RUN: %clang_cc1 -fsyntax-only -verify -Wall -std=c++11 %s +// RUN: %clang_cc1 -fsyntax-only -verify -Wall -std=c++11 %s -Wno-unused-value namespace std { template <typename T> void dummy(T &&) {} template <typename T> -void move(T &&) {} +T &&move(T &&x) { return x; } template <typename T, typename U> void move(T &&, U &&) {} inline namespace __1 { template <typename T> -void forward(T &) {} +T &forward(T &x) { return x; } } // namespace __1 struct foo {}; diff --git a/clang/test/SemaCXX/warn-consumed-analysis.cpp b/clang/test/SemaCXX/warn-consumed-analysis.cpp index b4dddb6763724..8e09779e64404 100644 --- a/clang/test/SemaCXX/warn-consumed-analysis.cpp +++ b/clang/test/SemaCXX/warn-consumed-analysis.cpp @@ -953,12 +953,12 @@ void test6() { namespace std { void move(); template<class T> - void move(T&&); + T &&move(T&); namespace __1 { void move(); template<class T> - void move(T&&); + T &&move(T&); } } @@ -971,7 +971,7 @@ namespace PR18260 { void test() { x.move(); std::move(); - std::move(x); + std::move(x); // expected-warning {{ignoring return value}} std::__1::move(); std::__1::move(x); } _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
