<div dir="ltr"><div class="gmail_quote"><div dir="ltr">On Wed, 1 Aug 2018 at 10:52, Hans Wennborg via cfe-commits <<a href="mailto:cfe-commits@lists.llvm.org">cfe-commits@lists.llvm.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">We hit this in Chromium too, see <a href="http://crbug.com/869824" rel="noreferrer" target="_blank">crbug.com/869824</a><br>
<br>
I've reverted in r338602<br></blockquote><div><br></div><div>Thanks, fixed and re-landed in r338941.</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
On Wed, Aug 1, 2018 at 5:26 PM, Benjamin Kramer via cfe-commits<br>
<<a href="mailto:cfe-commits@lists.llvm.org" target="_blank">cfe-commits@lists.llvm.org</a>> wrote:<br>
> It's pretty easy to make this crash<br>
><br>
> $ cat memcpy.c<br>
> void foo() {<br>
> int a[1], b;<br>
> memcpy((char*)a, (const char*)&b, (unsigned long)4);<br>
> }<br>
><br>
> $ clang memcpy.c<br>
> llvm/include/llvm/ADT/SmallVector.h:178: const_reference<br>
> llvm::SmallVectorTemplateCommon<clang::APValue::LValuePathEntry,<br>
> void>::back() const [T = clang::APValue::LValue<br>
> PathEntry]: Assertion `!empty()' failed.<br>
><br>
> On Wed, Aug 1, 2018 at 1:35 AM Richard Smith via cfe-commits<br>
> <<a href="mailto:cfe-commits@lists.llvm.org" target="_blank">cfe-commits@lists.llvm.org</a>> wrote:<br>
>><br>
>> Author: rsmith<br>
>> Date: Tue Jul 31 16:35:09 2018<br>
>> New Revision: 338455<br>
>><br>
>> URL: <a href="http://llvm.org/viewvc/llvm-project?rev=338455&view=rev" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project?rev=338455&view=rev</a><br>
>> Log:<br>
>> [constexpr] Support for constant evaluation of __builtin_memcpy and<br>
>> __builtin_memmove (in non-type-punning cases).<br>
>><br>
>> This is intended to permit libc++ to make std::copy etc constexpr<br>
>> without sacrificing the optimization that uses memcpy on<br>
>> trivially-copyable types.<br>
>><br>
>> __builtin_strcpy and __builtin_wcscpy are not handled by this change.<br>
>> They'd be straightforward to add, but we haven't encountered a need for<br>
>> them just yet.<br>
>><br>
>> Modified:<br>
>> cfe/trunk/include/clang/Basic/Builtins.def<br>
>> cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td<br>
>> cfe/trunk/lib/AST/ExprConstant.cpp<br>
>> cfe/trunk/test/CodeGen/builtin-memfns.c<br>
>> cfe/trunk/test/SemaCXX/constexpr-string.cpp<br>
>><br>
>> Modified: cfe/trunk/include/clang/Basic/Builtins.def<br>
>> URL:<br>
>> <a href="http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/Builtins.def?rev=338455&r1=338454&r2=338455&view=diff" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/Builtins.def?rev=338455&r1=338454&r2=338455&view=diff</a><br>
>><br>
>> ==============================================================================<br>
>> --- cfe/trunk/include/clang/Basic/Builtins.def (original)<br>
>> +++ cfe/trunk/include/clang/Basic/Builtins.def Tue Jul 31 16:35:09 2018<br>
>> @@ -471,6 +471,8 @@ BUILTIN(__builtin_wcslen, "zwC*", "nF")<br>
>> BUILTIN(__builtin_wcsncmp, "iwC*wC*z", "nF")<br>
>> BUILTIN(__builtin_wmemchr, "w*wC*wz", "nF")<br>
>> BUILTIN(__builtin_wmemcmp, "iwC*wC*z", "nF")<br>
>> +BUILTIN(__builtin_wmemcpy, "w*w*wC*z", "nF")<br>
>> +BUILTIN(__builtin_wmemmove, "w*w*wC*z", "nF")<br>
>> BUILTIN(__builtin_return_address, "v*IUi", "n")<br>
>> BUILTIN(__builtin_extract_return_addr, "v*v*", "n")<br>
>> BUILTIN(__builtin_frame_address, "v*IUi", "n")<br>
>> @@ -908,6 +910,8 @@ LIBBUILTIN(wcslen, "zwC*", "f", "wc<br>
>> LIBBUILTIN(wcsncmp, "iwC*wC*z", "f", "wchar.h", ALL_LANGUAGES)<br>
>> LIBBUILTIN(wmemchr, "w*wC*wz", "f", "wchar.h", ALL_LANGUAGES)<br>
>> LIBBUILTIN(wmemcmp, "iwC*wC*z", "f", "wchar.h", ALL_LANGUAGES)<br>
>> +LIBBUILTIN(wmemcpy, "w*w*wC*z", "f", "wchar.h", ALL_LANGUAGES)<br>
>> +LIBBUILTIN(wmemmove,"w*w*wC*z", "f", "wchar.h", ALL_LANGUAGES)<br>
>><br>
>> // C99<br>
>> // In some systems setjmp is a macro that expands to _setjmp. We undefine<br>
>><br>
>> Modified: cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td<br>
>> URL:<br>
>> <a href="http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td?rev=338455&r1=338454&r2=338455&view=diff" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td?rev=338455&r1=338454&r2=338455&view=diff</a><br>
>><br>
>> ==============================================================================<br>
>> --- cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td (original)<br>
>> +++ cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td Tue Jul 31<br>
>> 16:35:09 2018<br>
>> @@ -163,6 +163,20 @@ def note_constexpr_unsupported_unsized_a<br>
>> def note_constexpr_unsized_array_indexed : Note<<br>
>> "indexing of array without known bound is not allowed "<br>
>> "in a constant expression">;<br>
>> +def note_constexpr_memcpy_type_pun : Note<<br>
>> + "cannot constant evaluate '%select{memcpy|memmove}0' from object of "<br>
>> + "type %1 to object of type %2">;<br>
>> +def note_constexpr_memcpy_nontrivial : Note<<br>
>> + "cannot constant evaluate '%select{memcpy|memmove}0' between objects of<br>
>> "<br>
>> + "non-trivially-copyable type %1">;<br>
>> +def note_constexpr_memcpy_overlap : Note<<br>
>> + "'%select{memcpy|wmemcpy}0' between overlapping memory regions">;<br>
>> +def note_constexpr_memcpy_unsupported : Note<<br>
>> + "'%select{%select{memcpy|wmemcpy}1|%select{memmove|wmemmove}1}0' "<br>
>> + "not supported: %select{"<br>
>> + "size to copy (%4) is not a multiple of size of element type %3 (%5)|"<br>
>> + "source is not a contiguous array of at least %4 elements of type %3|"<br>
>> + "destination is not a contiguous array of at least %4 elements of type<br>
>> %3}2">;<br>
>><br>
>> def warn_integer_constant_overflow : Warning<<br>
>> "overflow in expression; result is %0 with type %1">,<br>
>><br>
>> Modified: cfe/trunk/lib/AST/ExprConstant.cpp<br>
>> URL:<br>
>> <a href="http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=338455&r1=338454&r2=338455&view=diff" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=338455&r1=338454&r2=338455&view=diff</a><br>
>><br>
>> ==============================================================================<br>
>> --- cfe/trunk/lib/AST/ExprConstant.cpp (original)<br>
>> +++ cfe/trunk/lib/AST/ExprConstant.cpp Tue Jul 31 16:35:09 2018<br>
>> @@ -319,6 +319,25 @@ namespace {<br>
>> return false;<br>
>> }<br>
>><br>
>> + /// Get the range of valid index adjustments in the form<br>
>> + /// {maximum value that can be subtracted from this pointer,<br>
>> + /// maximum value that can be added to this pointer}<br>
>> + std::pair<uint64_t, uint64_t> validIndexAdjustments() {<br>
>> + if (Invalid || isMostDerivedAnUnsizedArray())<br>
>> + return {0, 0};<br>
>> +<br>
>> + // [expr.add]p4: For the purposes of these operators, a pointer to<br>
>> a<br>
>> + // nonarray object behaves the same as a pointer to the first<br>
>> element of<br>
>> + // an array of length one with the type of the object as its<br>
>> element type.<br>
>> + bool IsArray = MostDerivedPathLength == Entries.size() &&<br>
>> + MostDerivedIsArrayElement;<br>
>> + uint64_t ArrayIndex =<br>
>> + IsArray ? Entries.back().ArrayIndex :<br>
>> (uint64_t)IsOnePastTheEnd;<br>
>> + uint64_t ArraySize =<br>
>> + IsArray ? getMostDerivedArraySize() : (uint64_t)1;<br>
>> + return {ArrayIndex, ArraySize - ArrayIndex};<br>
>> + }<br>
>> +<br>
>> /// Check that this refers to a valid subobject.<br>
>> bool isValidSubobject() const {<br>
>> if (Invalid)<br>
>> @@ -329,6 +348,13 @@ namespace {<br>
>> /// relevant diagnostic and set the designator as invalid.<br>
>> bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind<br>
>> CSK);<br>
>><br>
>> + /// Get the type of the designated object.<br>
>> + QualType getType(ASTContext &Ctx) const {<br>
>> + return MostDerivedPathLength == Entries.size()<br>
>> + ? MostDerivedType<br>
>> + : Ctx.getRecordType(getAsBaseClass(Entries.back()));<br>
>> + }<br>
>> +<br>
>> /// Update this designator to refer to the first element within this<br>
>> array.<br>
>> void addArrayUnchecked(const ConstantArrayType *CAT) {<br>
>> PathEntry Entry;<br>
>> @@ -1706,6 +1732,54 @@ static bool IsGlobalLValue(APValue::LVal<br>
>> }<br>
>> }<br>
>><br>
>> +static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) {<br>
>> + return LVal.Base.dyn_cast<const ValueDecl*>();<br>
>> +}<br>
>> +<br>
>> +static bool IsLiteralLValue(const LValue &Value) {<br>
>> + if (Value.getLValueCallIndex())<br>
>> + return false;<br>
>> + const Expr *E = Value.Base.dyn_cast<const Expr*>();<br>
>> + return E && !isa<MaterializeTemporaryExpr>(E);<br>
>> +}<br>
>> +<br>
>> +static bool IsWeakLValue(const LValue &Value) {<br>
>> + const ValueDecl *Decl = GetLValueBaseDecl(Value);<br>
>> + return Decl && Decl->isWeak();<br>
>> +}<br>
>> +<br>
>> +static bool isZeroSized(const LValue &Value) {<br>
>> + const ValueDecl *Decl = GetLValueBaseDecl(Value);<br>
>> + if (Decl && isa<VarDecl>(Decl)) {<br>
>> + QualType Ty = Decl->getType();<br>
>> + if (Ty->isArrayType())<br>
>> + return Ty->isIncompleteType() ||<br>
>> + Decl->getASTContext().getTypeSize(Ty) == 0;<br>
>> + }<br>
>> + return false;<br>
>> +}<br>
>> +<br>
>> +static bool HasSameBase(const LValue &A, const LValue &B) {<br>
>> + if (!A.getLValueBase())<br>
>> + return !B.getLValueBase();<br>
>> + if (!B.getLValueBase())<br>
>> + return false;<br>
>> +<br>
>> + if (A.getLValueBase().getOpaqueValue() !=<br>
>> + B.getLValueBase().getOpaqueValue()) {<br>
>> + const Decl *ADecl = GetLValueBaseDecl(A);<br>
>> + if (!ADecl)<br>
>> + return false;<br>
>> + const Decl *BDecl = GetLValueBaseDecl(B);<br>
>> + if (!BDecl || ADecl->getCanonicalDecl() != BDecl->getCanonicalDecl())<br>
>> + return false;<br>
>> + }<br>
>> +<br>
>> + return IsGlobalLValue(A.getLValueBase()) ||<br>
>> + (A.getLValueCallIndex() == B.getLValueCallIndex() &&<br>
>> + A.getLValueVersion() == B.getLValueVersion());<br>
>> +}<br>
>> +<br>
>> static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base)<br>
>> {<br>
>> assert(Base && "no location for a null lvalue");<br>
>> const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();<br>
>> @@ -1917,33 +1991,6 @@ CheckConstantExpression(EvalInfo &Info,<br>
>> return true;<br>
>> }<br>
>><br>
>> -static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) {<br>
>> - return LVal.Base.dyn_cast<const ValueDecl*>();<br>
>> -}<br>
>> -<br>
>> -static bool IsLiteralLValue(const LValue &Value) {<br>
>> - if (Value.getLValueCallIndex())<br>
>> - return false;<br>
>> - const Expr *E = Value.Base.dyn_cast<const Expr*>();<br>
>> - return E && !isa<MaterializeTemporaryExpr>(E);<br>
>> -}<br>
>> -<br>
>> -static bool IsWeakLValue(const LValue &Value) {<br>
>> - const ValueDecl *Decl = GetLValueBaseDecl(Value);<br>
>> - return Decl && Decl->isWeak();<br>
>> -}<br>
>> -<br>
>> -static bool isZeroSized(const LValue &Value) {<br>
>> - const ValueDecl *Decl = GetLValueBaseDecl(Value);<br>
>> - if (Decl && isa<VarDecl>(Decl)) {<br>
>> - QualType Ty = Decl->getType();<br>
>> - if (Ty->isArrayType())<br>
>> - return Ty->isIncompleteType() ||<br>
>> - Decl->getASTContext().getTypeSize(Ty) == 0;<br>
>> - }<br>
>> - return false;<br>
>> -}<br>
>> -<br>
>> static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) {<br>
>> // A null base expression indicates a null pointer. These are always<br>
>> // evaluatable, and they are false unless the offset is zero.<br>
>> @@ -6117,6 +6164,130 @@ bool PointerExprEvaluator::VisitBuiltinC<br>
>> return ZeroInitialization(E);<br>
>> }<br>
>><br>
>> + case Builtin::BImemcpy:<br>
>> + case Builtin::BImemmove:<br>
>> + case Builtin::BIwmemcpy:<br>
>> + case Builtin::BIwmemmove:<br>
>> + if (Info.getLangOpts().CPlusPlus11)<br>
>> + Info.CCEDiag(E, diag::note_constexpr_invalid_function)<br>
>> + << /*isConstexpr*/0 << /*isConstructor*/0<br>
>> + << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) +<br>
>> "'");<br>
>> + else<br>
>> + Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);<br>
>> + LLVM_FALLTHROUGH;<br>
>> + case Builtin::BI__builtin_memcpy:<br>
>> + case Builtin::BI__builtin_memmove:<br>
>> + case Builtin::BI__builtin_wmemcpy:<br>
>> + case Builtin::BI__builtin_wmemmove: {<br>
>> + bool WChar = BuiltinOp == Builtin::BIwmemcpy ||<br>
>> + BuiltinOp == Builtin::BIwmemmove ||<br>
>> + BuiltinOp == Builtin::BI__builtin_wmemcpy ||<br>
>> + BuiltinOp == Builtin::BI__builtin_wmemmove;<br>
>> + bool Move = BuiltinOp == Builtin::BImemmove ||<br>
>> + BuiltinOp == Builtin::BIwmemmove ||<br>
>> + BuiltinOp == Builtin::BI__builtin_memmove ||<br>
>> + BuiltinOp == Builtin::BI__builtin_wmemmove;<br>
>> +<br>
>> + // The result of mem* is the first argument.<br>
>> + if (!Visit(E->getArg(0)))<br>
>> + return false;<br>
>> + LValue Dest = Result;<br>
>> +<br>
>> + LValue Src;<br>
>> + if (!EvaluatePointer(E->getArg(1), Src, Info))<br>
>> + return false;<br>
>> +<br>
>> + APSInt N;<br>
>> + if (!EvaluateInteger(E->getArg(2), N, Info))<br>
>> + return false;<br>
>> + assert(!N.isSigned() && "memcpy and friends take an unsigned size");<br>
>> +<br>
>> + // If the size is zero, we treat this as always being a valid no-op.<br>
>> + // (Even if one of the src and dest pointers is null.)<br>
>> + if (!N)<br>
>> + return true;<br>
>> +<br>
>> + // We require that Src and Dest are both pointers to arrays of<br>
>> + // trivially-copyable type. (For the wide version, the designator<br>
>> will be<br>
>> + // invalid if the designated object is not a wchar_t.)<br>
>> + QualType T = Dest.Designator.getType(Info.Ctx);<br>
>> + QualType SrcT = Src.Designator.getType(Info.Ctx);<br>
>> + if (!Info.Ctx.hasSameUnqualifiedType(T, SrcT)) {<br>
>> + Info.FFDiag(E, diag::note_constexpr_memcpy_type_pun) << Move <<<br>
>> SrcT << T;<br>
>> + return false;<br>
>> + }<br>
>> + if (!T.isTriviallyCopyableType(Info.Ctx)) {<br>
>> + Info.FFDiag(E, diag::note_constexpr_memcpy_nontrivial) << Move <<<br>
>> T;<br>
>> + return false;<br>
>> + }<br>
>> +<br>
>> + // Figure out how many T's we're copying.<br>
>> + uint64_t TSize = Info.Ctx.getTypeSizeInChars(T).getQuantity();<br>
>> + if (!WChar) {<br>
>> + uint64_t Remainder;<br>
>> + llvm::APInt OrigN = N;<br>
>> + llvm::APInt::udivrem(OrigN, TSize, N, Remainder);<br>
>> + if (Remainder) {<br>
>> + Info.FFDiag(E, diag::note_constexpr_memcpy_unsupported)<br>
>> + << Move << WChar << 0 << T << OrigN.toString(10,<br>
>> /*Signed*/false)<br>
>> + << (unsigned)TSize;<br>
>> + return false;<br>
>> + }<br>
>> + }<br>
>> +<br>
>> + // Check that the copying will remain within the arrays, just so that<br>
>> we<br>
>> + // can give a more meaningful diagnostic. This implicitly also checks<br>
>> that<br>
>> + // N fits into 64 bits.<br>
>> + uint64_t RemainingSrcSize =<br>
>> Src.Designator.validIndexAdjustments().second;<br>
>> + uint64_t RemainingDestSize =<br>
>> Dest.Designator.validIndexAdjustments().second;<br>
>> + if (N.ugt(RemainingSrcSize) || N.ugt(RemainingDestSize)) {<br>
>> + Info.FFDiag(E, diag::note_constexpr_memcpy_unsupported)<br>
>> + << Move << WChar << (N.ugt(RemainingSrcSize) ? 1 : 2) << T<br>
>> + << N.toString(10, /*Signed*/false);<br>
>> + return false;<br>
>> + }<br>
>> + uint64_t NElems = N.getZExtValue();<br>
>> + uint64_t NBytes = NElems * TSize;<br>
>> +<br>
>> + // Check for overlap.<br>
>> + int Direction = 1;<br>
>> + if (HasSameBase(Src, Dest)) {<br>
>> + uint64_t SrcOffset = Src.getLValueOffset().getQuantity();<br>
>> + uint64_t DestOffset = Dest.getLValueOffset().getQuantity();<br>
>> + if (DestOffset >= SrcOffset && DestOffset - SrcOffset < NBytes) {<br>
>> + // Dest is inside the source region.<br>
>> + if (!Move) {<br>
>> + Info.FFDiag(E, diag::note_constexpr_memcpy_overlap) << WChar;<br>
>> + return false;<br>
>> + }<br>
>> + // For memmove and friends, copy backwards.<br>
>> + if (!HandleLValueArrayAdjustment(Info, E, Src, T, NElems - 1) ||<br>
>> + !HandleLValueArrayAdjustment(Info, E, Dest, T, NElems - 1))<br>
>> + return false;<br>
>> + Direction = -1;<br>
>> + } else if (!Move && SrcOffset >= DestOffset &&<br>
>> + SrcOffset - DestOffset < NBytes) {<br>
>> + // Src is inside the destination region for memcpy: invalid.<br>
>> + Info.FFDiag(E, diag::note_constexpr_memcpy_overlap) << WChar;<br>
>> + return false;<br>
>> + }<br>
>> + }<br>
>> +<br>
>> + while (true) {<br>
>> + APValue Val;<br>
>> + if (!handleLValueToRValueConversion(Info, E, T, Src, Val) ||<br>
>> + !handleAssignment(Info, E, Dest, T, Val))<br>
>> + return false;<br>
>> + // Do not iterate past the last element; if we're copying<br>
>> backwards, that<br>
>> + // might take us off the start of the array.<br>
>> + if (--NElems == 0)<br>
>> + return true;<br>
>> + if (!HandleLValueArrayAdjustment(Info, E, Src, T, Direction) ||<br>
>> + !HandleLValueArrayAdjustment(Info, E, Dest, T, Direction))<br>
>> + return false;<br>
>> + }<br>
>> + }<br>
>> +<br>
>> default:<br>
>> return visitNonBuiltinCallExpr(E);<br>
>> }<br>
>> @@ -8357,27 +8528,6 @@ bool IntExprEvaluator::VisitBuiltinCallE<br>
>> }<br>
>> }<br>
>><br>
>> -static bool HasSameBase(const LValue &A, const LValue &B) {<br>
>> - if (!A.getLValueBase())<br>
>> - return !B.getLValueBase();<br>
>> - if (!B.getLValueBase())<br>
>> - return false;<br>
>> -<br>
>> - if (A.getLValueBase().getOpaqueValue() !=<br>
>> - B.getLValueBase().getOpaqueValue()) {<br>
>> - const Decl *ADecl = GetLValueBaseDecl(A);<br>
>> - if (!ADecl)<br>
>> - return false;<br>
>> - const Decl *BDecl = GetLValueBaseDecl(B);<br>
>> - if (!BDecl || ADecl->getCanonicalDecl() != BDecl->getCanonicalDecl())<br>
>> - return false;<br>
>> - }<br>
>> -<br>
>> - return IsGlobalLValue(A.getLValueBase()) ||<br>
>> - (A.getLValueCallIndex() == B.getLValueCallIndex() &&<br>
>> - A.getLValueVersion() == B.getLValueVersion());<br>
>> -}<br>
>> -<br>
>> /// Determine whether this is a pointer past the end of the complete<br>
>> /// object referred to by the lvalue.<br>
>> static bool isOnePastTheEndOfCompleteObject(const ASTContext &Ctx,<br>
>><br>
>> Modified: cfe/trunk/test/CodeGen/builtin-memfns.c<br>
>> URL:<br>
>> <a href="http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/builtin-memfns.c?rev=338455&r1=338454&r2=338455&view=diff" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/builtin-memfns.c?rev=338455&r1=338454&r2=338455&view=diff</a><br>
>><br>
>> ==============================================================================<br>
>> --- cfe/trunk/test/CodeGen/builtin-memfns.c (original)<br>
>> +++ cfe/trunk/test/CodeGen/builtin-memfns.c Tue Jul 31 16:35:09 2018<br>
>> @@ -1,5 +1,8 @@<br>
>> // RUN: %clang_cc1 -triple i386-pc-linux-gnu -emit-llvm < %s| FileCheck<br>
>> %s<br>
>><br>
>> +typedef __WCHAR_TYPE__ wchar_t;<br>
>> +typedef __SIZE_TYPE__ size_t;<br>
>> +<br>
>> // CHECK: @test1<br>
>> // CHECK: call void @llvm.memset.p0i8.i32<br>
>> // CHECK: call void @llvm.memset.p0i8.i32<br>
>> @@ -83,3 +86,17 @@ void test9() {<br>
>> // CHECK: call void @llvm.memcpy{{.*}} align 16 {{.*}} align 16 {{.*}}<br>
>> 16, i1 false)<br>
>> __builtin_memcpy(x, y, sizeof(y));<br>
>> }<br>
>> +<br>
>> +wchar_t dest;<br>
>> +wchar_t src;<br>
>> +<br>
>> +// CHECK-LABEL: @test10<br>
>> +// FIXME: Consider lowering these to llvm.memcpy / llvm.memmove.<br>
>> +void test10() {<br>
>> + // CHECK: call i32* @wmemcpy(i32* @dest, i32* @src, i32 4)<br>
>> + __builtin_wmemcpy(&dest, &src, 4);<br>
>> +<br>
>> + // CHECK: call i32* @wmemmove(i32* @dest, i32* @src, i32 4)<br>
>> + __builtin_wmemmove(&dest, &src, 4);<br>
>> +}<br>
>> +<br>
>><br>
>> Modified: cfe/trunk/test/SemaCXX/constexpr-string.cpp<br>
>> URL:<br>
>> <a href="http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/constexpr-string.cpp?rev=338455&r1=338454&r2=338455&view=diff" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/constexpr-string.cpp?rev=338455&r1=338454&r2=338455&view=diff</a><br>
>><br>
>> ==============================================================================<br>
>> --- cfe/trunk/test/SemaCXX/constexpr-string.cpp (original)<br>
>> +++ cfe/trunk/test/SemaCXX/constexpr-string.cpp Tue Jul 31 16:35:09 2018<br>
>> @@ -1,6 +1,6 @@<br>
>> -// RUN: %clang_cc1 %s -std=c++1z -fsyntax-only -verify -pedantic<br>
>> -// RUN: %clang_cc1 %s -std=c++1z -fsyntax-only -verify -pedantic<br>
>> -fno-signed-char<br>
>> -// RUN: %clang_cc1 %s -std=c++1z -fsyntax-only -verify -pedantic<br>
>> -fno-wchar -Dwchar_t=__WCHAR_TYPE__<br>
>> +// RUN: %clang_cc1 %s -triple x86_64-linux-gnu -std=c++1z -fsyntax-only<br>
>> -verify -pedantic<br>
>> +// RUN: %clang_cc1 %s -triple x86_64-linux-gnu -std=c++1z -fsyntax-only<br>
>> -verify -pedantic -fno-signed-char<br>
>> +// RUN: %clang_cc1 %s -triple x86_64-linux-gnu -std=c++1z -fsyntax-only<br>
>> -verify -pedantic -fno-wchar -Dwchar_t=__WCHAR_TYPE__<br>
>><br>
>> # 6 "/usr/include/string.h" 1 3 4<br>
>> extern "C" {<br>
>> @@ -14,10 +14,13 @@ extern "C" {<br>
>><br>
>> extern char *strchr(const char *s, int c);<br>
>> extern void *memchr(const void *s, int c, size_t n);<br>
>> +<br>
>> + extern void *memcpy(void *d, const void *s, size_t n);<br>
>> + extern void *memmove(void *d, const void *s, size_t n);<br>
>> }<br>
>> -# 19 "SemaCXX/constexpr-string.cpp" 2<br>
>> +# 22 "SemaCXX/constexpr-string.cpp" 2<br>
>><br>
>> -# 21 "/usr/include/wchar.h" 1 3 4<br>
>> +# 24 "/usr/include/wchar.h" 1 3 4<br>
>> extern "C" {<br>
>> extern size_t wcslen(const wchar_t *p);<br>
>><br>
>> @@ -27,9 +30,12 @@ extern "C" {<br>
>><br>
>> extern wchar_t *wcschr(const wchar_t *s, wchar_t c);<br>
>> extern wchar_t *wmemchr(const wchar_t *s, wchar_t c, size_t n);<br>
>> +<br>
>> + extern wchar_t *wmemcpy(wchar_t *d, const wchar_t *s, size_t n);<br>
>> + extern wchar_t *wmemmove(wchar_t *d, const wchar_t *s, size_t n);<br>
>> }<br>
>><br>
>> -# 33 "SemaCXX/constexpr-string.cpp" 2<br>
>> +# 39 "SemaCXX/constexpr-string.cpp" 2<br>
>> namespace Strlen {<br>
>> constexpr int n = __builtin_strlen("hello"); // ok<br>
>> static_assert(n == 5);<br>
>> @@ -235,3 +241,133 @@ namespace WcschrEtc {<br>
>> constexpr bool a = !wcschr(L"hello", L'h'); // expected-error<br>
>> {{constant expression}} expected-note {{non-constexpr function 'wcschr'<br>
>> cannot be used in a constant expression}}<br>
>> constexpr bool b = !wmemchr(L"hello", L'h', 3); // expected-error<br>
>> {{constant expression}} expected-note {{non-constexpr function 'wmemchr'<br>
>> cannot be used in a constant expression}}<br>
>> }<br>
>> +<br>
>> +namespace MemcpyEtc {<br>
>> + template<typename T><br>
>> + constexpr T result(T (&arr)[4]) {<br>
>> + return arr[0] * 1000 + arr[1] * 100 + arr[2] * 10 + arr[3];<br>
>> + }<br>
>> +<br>
>> + constexpr int test_memcpy(int a, int b, int n) {<br>
>> + int arr[4] = {1, 2, 3, 4};<br>
>> + __builtin_memcpy(arr + a, arr + b, n);<br>
>> + // expected-note@-1 2{{overlapping memory regions}}<br>
>> + // expected-note@-2 {{size to copy (1) is not a multiple of size of<br>
>> element type 'int'}}<br>
>> + // expected-note@-3 {{source is not a contiguous array of at least 2<br>
>> elements of type 'int'}}<br>
>> + // expected-note@-4 {{destination is not a contiguous array of at<br>
>> least 3 elements of type 'int'}}<br>
>> + return result(arr);<br>
>> + }<br>
>> + constexpr int test_memmove(int a, int b, int n) {<br>
>> + int arr[4] = {1, 2, 3, 4};<br>
>> + __builtin_memmove(arr + a, arr + b, n);<br>
>> + // expected-note@-1 {{size to copy (1) is not a multiple of size of<br>
>> element type 'int'}}<br>
>> + // expected-note@-2 {{source is not a contiguous array of at least 2<br>
>> elements of type 'int'}}<br>
>> + // expected-note@-3 {{destination is not a contiguous array of at<br>
>> least 3 elements of type 'int'}}<br>
>> + return result(arr);<br>
>> + }<br>
>> + constexpr int test_wmemcpy(int a, int b, int n) {<br>
>> + wchar_t arr[4] = {1, 2, 3, 4};<br>
>> + __builtin_wmemcpy(arr + a, arr + b, n);<br>
>> + // expected-note@-1 2{{overlapping memory regions}}<br>
>> + // expected-note-re@-2 {{source is not a contiguous array of at least<br>
>> 2 elements of type '{{wchar_t|int}}'}}<br>
>> + // expected-note-re@-3 {{destination is not a contiguous array of at<br>
>> least 3 elements of type '{{wchar_t|int}}'}}<br>
>> + return result(arr);<br>
>> + }<br>
>> + constexpr int test_wmemmove(int a, int b, int n) {<br>
>> + wchar_t arr[4] = {1, 2, 3, 4};<br>
>> + __builtin_wmemmove(arr + a, arr + b, n);<br>
>> + // expected-note-re@-1 {{source is not a contiguous array of at least<br>
>> 2 elements of type '{{wchar_t|int}}'}}<br>
>> + // expected-note-re@-2 {{destination is not a contiguous array of at<br>
>> least 3 elements of type '{{wchar_t|int}}'}}<br>
>> + return result(arr);<br>
>> + }<br>
>> +<br>
>> + static_assert(test_memcpy(1, 2, 4) == 1334);<br>
>> + static_assert(test_memcpy(2, 1, 4) == 1224);<br>
>> + static_assert(test_memcpy(0, 1, 8) == 2334); // expected-error<br>
>> {{constant}} expected-note {{in call}}<br>
>> + static_assert(test_memcpy(1, 0, 8) == 1124); // expected-error<br>
>> {{constant}} expected-note {{in call}}<br>
>> + static_assert(test_memcpy(1, 2, 1) == 1334); // expected-error<br>
>> {{constant}} expected-note {{in call}}<br>
>> + static_assert(test_memcpy(0, 3, 4) == 4234);<br>
>> + static_assert(test_memcpy(0, 3, 8) == 4234); // expected-error<br>
>> {{constant}} expected-note {{in call}}<br>
>> + static_assert(test_memcpy(2, 0, 12) == 4234); // expected-error<br>
>> {{constant}} expected-note {{in call}}<br>
>> +<br>
>> + static_assert(test_memmove(1, 2, 4) == 1334);<br>
>> + static_assert(test_memmove(2, 1, 4) == 1224);<br>
>> + static_assert(test_memmove(0, 1, 8) == 2334);<br>
>> + static_assert(test_memmove(1, 0, 8) == 1124);<br>
>> + static_assert(test_memmove(1, 2, 1) == 1334); // expected-error<br>
>> {{constant}} expected-note {{in call}}<br>
>> + static_assert(test_memmove(0, 3, 4) == 4234);<br>
>> + static_assert(test_memmove(0, 3, 8) == 4234); // expected-error<br>
>> {{constant}} expected-note {{in call}}<br>
>> + static_assert(test_memmove(2, 0, 12) == 4234); // expected-error<br>
>> {{constant}} expected-note {{in call}}<br>
>> +<br>
>> + static_assert(test_wmemcpy(1, 2, 1) == 1334);<br>
>> + static_assert(test_wmemcpy(2, 1, 1) == 1224);<br>
>> + static_assert(test_wmemcpy(0, 1, 2) == 2334); // expected-error<br>
>> {{constant}} expected-note {{in call}}<br>
>> + static_assert(test_wmemcpy(1, 0, 2) == 1124); // expected-error<br>
>> {{constant}} expected-note {{in call}}<br>
>> + static_assert(test_wmemcpy(1, 2, 1) == 1334);<br>
>> + static_assert(test_wmemcpy(0, 3, 1) == 4234);<br>
>> + static_assert(test_wmemcpy(0, 3, 2) == 4234); // expected-error<br>
>> {{constant}} expected-note {{in call}}<br>
>> + static_assert(test_wmemcpy(2, 0, 3) == 4234); // expected-error<br>
>> {{constant}} expected-note {{in call}}<br>
>> +<br>
>> + static_assert(test_wmemmove(1, 2, 1) == 1334);<br>
>> + static_assert(test_wmemmove(2, 1, 1) == 1224);<br>
>> + static_assert(test_wmemmove(0, 1, 2) == 2334);<br>
>> + static_assert(test_wmemmove(1, 0, 2) == 1124);<br>
>> + static_assert(test_wmemmove(1, 2, 1) == 1334);<br>
>> + static_assert(test_wmemmove(0, 3, 1) == 4234);<br>
>> + static_assert(test_wmemmove(0, 3, 2) == 4234); // expected-error<br>
>> {{constant}} expected-note {{in call}}<br>
>> + static_assert(test_wmemmove(2, 0, 3) == 4234); // expected-error<br>
>> {{constant}} expected-note {{in call}}<br>
>> +<br>
>> + // Copying is permitted for any trivially-copyable type.<br>
>> + struct Trivial { char k; short s; constexpr bool ok() { return k == 3<br>
>> && s == 4; } };<br>
>> + constexpr bool test_trivial() {<br>
>> + Trivial arr[3] = {{1, 2}, {3, 4}, {5, 6}};<br>
>> + __builtin_memcpy(arr, arr+1, sizeof(Trivial));<br>
>> + __builtin_memmove(arr+1, arr, 2 * sizeof(Trivial));<br>
>> + return arr[0].ok() && arr[1].ok() && arr[2].ok();<br>
>> + }<br>
>> + static_assert(test_trivial());<br>
>> +<br>
>> + // But not for a non-trivially-copyable type.<br>
>> + struct NonTrivial {<br>
>> + constexpr NonTrivial() : n(0) {}<br>
>> + constexpr NonTrivial(const NonTrivial &) : n(1) {}<br>
>> + int n;<br>
>> + };<br>
>> + constexpr bool test_nontrivial_memcpy() { // expected-error {{never<br>
>> produces a constant}}<br>
>> + NonTrivial arr[3] = {};<br>
>> + __builtin_memcpy(arr, arr + 1, sizeof(NonTrivial)); // expected-note<br>
>> 2{{non-trivially-copyable}}<br>
>> + return true;<br>
>> + }<br>
>> + static_assert(test_nontrivial_memcpy()); // expected-error {{constant}}<br>
>> expected-note {{in call}}<br>
>> + constexpr bool test_nontrivial_memmove() { // expected-error {{never<br>
>> produces a constant}}<br>
>> + NonTrivial arr[3] = {};<br>
>> + __builtin_memcpy(arr, arr + 1, sizeof(NonTrivial)); // expected-note<br>
>> 2{{non-trivially-copyable}}<br>
>> + return true;<br>
>> + }<br>
>> + static_assert(test_nontrivial_memmove()); // expected-error<br>
>> {{constant}} expected-note {{in call}}<br>
>> +<br>
>> + // Type puns via constant evaluated memcpy are not supported yet.<br>
>> + constexpr float type_pun(const unsigned &n) {<br>
>> + float f = 0.0f;<br>
>> + __builtin_memcpy(&f, &n, 4); // expected-note {{cannot constant<br>
>> evaluate 'memcpy' from object of type 'const unsigned int' to object of type<br>
>> 'float'}}<br>
>> + return f;<br>
>> + }<br>
>> + static_assert(type_pun(0x3f800000) == 1.0f); // expected-error<br>
>> {{constant}} expected-note {{in call}}<br>
>> +<br>
>> + // Make sure we're not confused by derived-to-base conversions.<br>
>> + struct Base { int a; };<br>
>> + struct Derived : Base { int b; };<br>
>> + constexpr int test_derived_to_base(int n) {<br>
>> + Derived arr[2] = {1, 2, 3, 4};<br>
>> + Base *p = &arr[0];<br>
>> + Base *q = &arr[1];<br>
>> + __builtin_memcpy(p, q, sizeof(Base) * n); // expected-note {{source<br>
>> is not a contiguous array of at least 2 elements of type 'MemcpyEtc::Base'}}<br>
>> + return arr[0].a * 1000 + arr[0].b * 100 + arr[1].a * 10 + arr[1].b;<br>
>> + }<br>
>> + static_assert(test_derived_to_base(0) == 1234);<br>
>> + static_assert(test_derived_to_base(1) == 3234);<br>
>> + // FIXME: We could consider making this work by stripping elements off<br>
>> both<br>
>> + // designators until we have a long enough matching size, if both<br>
>> designators<br>
>> + // point to the start of their respective final elements.<br>
>> + static_assert(test_derived_to_base(2) == 3434); // expected-error<br>
>> {{constant}} expected-note {{in call}}<br>
>> +}<br>
>><br>
>><br>
>> _______________________________________________<br>
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>> <a href="mailto:cfe-commits@lists.llvm.org" target="_blank">cfe-commits@lists.llvm.org</a><br>
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