r338455 - [constexpr] Support for constant evaluation of __builtin_memcpy and
Richard Smith via cfe-commits
cfe-commits at lists.llvm.org
Fri Aug 3 17:58:06 PDT 2018
On Wed, 1 Aug 2018 at 10:52, Hans Wennborg via cfe-commits <
cfe-commits at lists.llvm.org> wrote:
> We hit this in Chromium too, see crbug.com/869824
>
> I've reverted in r338602
>
Thanks, fixed and re-landed in r338941.
> On Wed, Aug 1, 2018 at 5:26 PM, Benjamin Kramer via cfe-commits
> <cfe-commits at lists.llvm.org> wrote:
> > It's pretty easy to make this crash
> >
> > $ cat memcpy.c
> > void foo() {
> > int a[1], b;
> > memcpy((char*)a, (const char*)&b, (unsigned long)4);
> > }
> >
> > $ clang memcpy.c
> > llvm/include/llvm/ADT/SmallVector.h:178: const_reference
> > llvm::SmallVectorTemplateCommon<clang::APValue::LValuePathEntry,
> > void>::back() const [T = clang::APValue::LValue
> > PathEntry]: Assertion `!empty()' failed.
> >
> > On Wed, Aug 1, 2018 at 1:35 AM Richard Smith via cfe-commits
> > <cfe-commits at lists.llvm.org> wrote:
> >>
> >> Author: rsmith
> >> Date: Tue Jul 31 16:35:09 2018
> >> New Revision: 338455
> >>
> >> URL: http://llvm.org/viewvc/llvm-project?rev=338455&view=rev
> >> Log:
> >> [constexpr] Support for constant evaluation of __builtin_memcpy and
> >> __builtin_memmove (in non-type-punning cases).
> >>
> >> This is intended to permit libc++ to make std::copy etc constexpr
> >> without sacrificing the optimization that uses memcpy on
> >> trivially-copyable types.
> >>
> >> __builtin_strcpy and __builtin_wcscpy are not handled by this change.
> >> They'd be straightforward to add, but we haven't encountered a need for
> >> them just yet.
> >>
> >> Modified:
> >> cfe/trunk/include/clang/Basic/Builtins.def
> >> cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td
> >> cfe/trunk/lib/AST/ExprConstant.cpp
> >> cfe/trunk/test/CodeGen/builtin-memfns.c
> >> cfe/trunk/test/SemaCXX/constexpr-string.cpp
> >>
> >> Modified: cfe/trunk/include/clang/Basic/Builtins.def
> >> URL:
> >>
> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/Builtins.def?rev=338455&r1=338454&r2=338455&view=diff
> >>
> >>
> ==============================================================================
> >> --- cfe/trunk/include/clang/Basic/Builtins.def (original)
> >> +++ cfe/trunk/include/clang/Basic/Builtins.def Tue Jul 31 16:35:09 2018
> >> @@ -471,6 +471,8 @@ BUILTIN(__builtin_wcslen, "zwC*", "nF")
> >> BUILTIN(__builtin_wcsncmp, "iwC*wC*z", "nF")
> >> BUILTIN(__builtin_wmemchr, "w*wC*wz", "nF")
> >> BUILTIN(__builtin_wmemcmp, "iwC*wC*z", "nF")
> >> +BUILTIN(__builtin_wmemcpy, "w*w*wC*z", "nF")
> >> +BUILTIN(__builtin_wmemmove, "w*w*wC*z", "nF")
> >> BUILTIN(__builtin_return_address, "v*IUi", "n")
> >> BUILTIN(__builtin_extract_return_addr, "v*v*", "n")
> >> BUILTIN(__builtin_frame_address, "v*IUi", "n")
> >> @@ -908,6 +910,8 @@ LIBBUILTIN(wcslen, "zwC*", "f", "wc
> >> LIBBUILTIN(wcsncmp, "iwC*wC*z", "f", "wchar.h", ALL_LANGUAGES)
> >> LIBBUILTIN(wmemchr, "w*wC*wz", "f", "wchar.h", ALL_LANGUAGES)
> >> LIBBUILTIN(wmemcmp, "iwC*wC*z", "f", "wchar.h", ALL_LANGUAGES)
> >> +LIBBUILTIN(wmemcpy, "w*w*wC*z", "f", "wchar.h", ALL_LANGUAGES)
> >> +LIBBUILTIN(wmemmove,"w*w*wC*z", "f", "wchar.h", ALL_LANGUAGES)
> >>
> >> // C99
> >> // In some systems setjmp is a macro that expands to _setjmp. We
> undefine
> >>
> >> Modified: cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td
> >> URL:
> >>
> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td?rev=338455&r1=338454&r2=338455&view=diff
> >>
> >>
> ==============================================================================
> >> --- cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td (original)
> >> +++ cfe/trunk/include/clang/Basic/DiagnosticASTKinds.td Tue Jul 31
> >> 16:35:09 2018
> >> @@ -163,6 +163,20 @@ def note_constexpr_unsupported_unsized_a
> >> def note_constexpr_unsized_array_indexed : Note<
> >> "indexing of array without known bound is not allowed "
> >> "in a constant expression">;
> >> +def note_constexpr_memcpy_type_pun : Note<
> >> + "cannot constant evaluate '%select{memcpy|memmove}0' from object of "
> >> + "type %1 to object of type %2">;
> >> +def note_constexpr_memcpy_nontrivial : Note<
> >> + "cannot constant evaluate '%select{memcpy|memmove}0' between objects
> of
> >> "
> >> + "non-trivially-copyable type %1">;
> >> +def note_constexpr_memcpy_overlap : Note<
> >> + "'%select{memcpy|wmemcpy}0' between overlapping memory regions">;
> >> +def note_constexpr_memcpy_unsupported : Note<
> >> + "'%select{%select{memcpy|wmemcpy}1|%select{memmove|wmemmove}1}0' "
> >> + "not supported: %select{"
> >> + "size to copy (%4) is not a multiple of size of element type %3
> (%5)|"
> >> + "source is not a contiguous array of at least %4 elements of type
> %3|"
> >> + "destination is not a contiguous array of at least %4 elements of
> type
> >> %3}2">;
> >>
> >> def warn_integer_constant_overflow : Warning<
> >> "overflow in expression; result is %0 with type %1">,
> >>
> >> Modified: cfe/trunk/lib/AST/ExprConstant.cpp
> >> URL:
> >>
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=338455&r1=338454&r2=338455&view=diff
> >>
> >>
> ==============================================================================
> >> --- cfe/trunk/lib/AST/ExprConstant.cpp (original)
> >> +++ cfe/trunk/lib/AST/ExprConstant.cpp Tue Jul 31 16:35:09 2018
> >> @@ -319,6 +319,25 @@ namespace {
> >> return false;
> >> }
> >>
> >> + /// Get the range of valid index adjustments in the form
> >> + /// {maximum value that can be subtracted from this pointer,
> >> + /// maximum value that can be added to this pointer}
> >> + std::pair<uint64_t, uint64_t> validIndexAdjustments() {
> >> + if (Invalid || isMostDerivedAnUnsizedArray())
> >> + return {0, 0};
> >> +
> >> + // [expr.add]p4: For the purposes of these operators, a pointer
> to
> >> a
> >> + // nonarray object behaves the same as a pointer to the first
> >> element of
> >> + // an array of length one with the type of the object as its
> >> element type.
> >> + bool IsArray = MostDerivedPathLength == Entries.size() &&
> >> + MostDerivedIsArrayElement;
> >> + uint64_t ArrayIndex =
> >> + IsArray ? Entries.back().ArrayIndex :
> >> (uint64_t)IsOnePastTheEnd;
> >> + uint64_t ArraySize =
> >> + IsArray ? getMostDerivedArraySize() : (uint64_t)1;
> >> + return {ArrayIndex, ArraySize - ArrayIndex};
> >> + }
> >> +
> >> /// Check that this refers to a valid subobject.
> >> bool isValidSubobject() const {
> >> if (Invalid)
> >> @@ -329,6 +348,13 @@ namespace {
> >> /// relevant diagnostic and set the designator as invalid.
> >> bool checkSubobject(EvalInfo &Info, const Expr *E,
> CheckSubobjectKind
> >> CSK);
> >>
> >> + /// Get the type of the designated object.
> >> + QualType getType(ASTContext &Ctx) const {
> >> + return MostDerivedPathLength == Entries.size()
> >> + ? MostDerivedType
> >> + : Ctx.getRecordType(getAsBaseClass(Entries.back()));
> >> + }
> >> +
> >> /// Update this designator to refer to the first element within
> this
> >> array.
> >> void addArrayUnchecked(const ConstantArrayType *CAT) {
> >> PathEntry Entry;
> >> @@ -1706,6 +1732,54 @@ static bool IsGlobalLValue(APValue::LVal
> >> }
> >> }
> >>
> >> +static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) {
> >> + return LVal.Base.dyn_cast<const ValueDecl*>();
> >> +}
> >> +
> >> +static bool IsLiteralLValue(const LValue &Value) {
> >> + if (Value.getLValueCallIndex())
> >> + return false;
> >> + const Expr *E = Value.Base.dyn_cast<const Expr*>();
> >> + return E && !isa<MaterializeTemporaryExpr>(E);
> >> +}
> >> +
> >> +static bool IsWeakLValue(const LValue &Value) {
> >> + const ValueDecl *Decl = GetLValueBaseDecl(Value);
> >> + return Decl && Decl->isWeak();
> >> +}
> >> +
> >> +static bool isZeroSized(const LValue &Value) {
> >> + const ValueDecl *Decl = GetLValueBaseDecl(Value);
> >> + if (Decl && isa<VarDecl>(Decl)) {
> >> + QualType Ty = Decl->getType();
> >> + if (Ty->isArrayType())
> >> + return Ty->isIncompleteType() ||
> >> + Decl->getASTContext().getTypeSize(Ty) == 0;
> >> + }
> >> + return false;
> >> +}
> >> +
> >> +static bool HasSameBase(const LValue &A, const LValue &B) {
> >> + if (!A.getLValueBase())
> >> + return !B.getLValueBase();
> >> + if (!B.getLValueBase())
> >> + return false;
> >> +
> >> + if (A.getLValueBase().getOpaqueValue() !=
> >> + B.getLValueBase().getOpaqueValue()) {
> >> + const Decl *ADecl = GetLValueBaseDecl(A);
> >> + if (!ADecl)
> >> + return false;
> >> + const Decl *BDecl = GetLValueBaseDecl(B);
> >> + if (!BDecl || ADecl->getCanonicalDecl() !=
> BDecl->getCanonicalDecl())
> >> + return false;
> >> + }
> >> +
> >> + return IsGlobalLValue(A.getLValueBase()) ||
> >> + (A.getLValueCallIndex() == B.getLValueCallIndex() &&
> >> + A.getLValueVersion() == B.getLValueVersion());
> >> +}
> >> +
> >> static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase
> Base)
> >> {
> >> assert(Base && "no location for a null lvalue");
> >> const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
> >> @@ -1917,33 +1991,6 @@ CheckConstantExpression(EvalInfo &Info,
> >> return true;
> >> }
> >>
> >> -static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) {
> >> - return LVal.Base.dyn_cast<const ValueDecl*>();
> >> -}
> >> -
> >> -static bool IsLiteralLValue(const LValue &Value) {
> >> - if (Value.getLValueCallIndex())
> >> - return false;
> >> - const Expr *E = Value.Base.dyn_cast<const Expr*>();
> >> - return E && !isa<MaterializeTemporaryExpr>(E);
> >> -}
> >> -
> >> -static bool IsWeakLValue(const LValue &Value) {
> >> - const ValueDecl *Decl = GetLValueBaseDecl(Value);
> >> - return Decl && Decl->isWeak();
> >> -}
> >> -
> >> -static bool isZeroSized(const LValue &Value) {
> >> - const ValueDecl *Decl = GetLValueBaseDecl(Value);
> >> - if (Decl && isa<VarDecl>(Decl)) {
> >> - QualType Ty = Decl->getType();
> >> - if (Ty->isArrayType())
> >> - return Ty->isIncompleteType() ||
> >> - Decl->getASTContext().getTypeSize(Ty) == 0;
> >> - }
> >> - return false;
> >> -}
> >> -
> >> static bool EvalPointerValueAsBool(const APValue &Value, bool &Result)
> {
> >> // A null base expression indicates a null pointer. These are always
> >> // evaluatable, and they are false unless the offset is zero.
> >> @@ -6117,6 +6164,130 @@ bool PointerExprEvaluator::VisitBuiltinC
> >> return ZeroInitialization(E);
> >> }
> >>
> >> + case Builtin::BImemcpy:
> >> + case Builtin::BImemmove:
> >> + case Builtin::BIwmemcpy:
> >> + case Builtin::BIwmemmove:
> >> + if (Info.getLangOpts().CPlusPlus11)
> >> + Info.CCEDiag(E, diag::note_constexpr_invalid_function)
> >> + << /*isConstexpr*/0 << /*isConstructor*/0
> >> + << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp)
> +
> >> "'");
> >> + else
> >> + Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
> >> + LLVM_FALLTHROUGH;
> >> + case Builtin::BI__builtin_memcpy:
> >> + case Builtin::BI__builtin_memmove:
> >> + case Builtin::BI__builtin_wmemcpy:
> >> + case Builtin::BI__builtin_wmemmove: {
> >> + bool WChar = BuiltinOp == Builtin::BIwmemcpy ||
> >> + BuiltinOp == Builtin::BIwmemmove ||
> >> + BuiltinOp == Builtin::BI__builtin_wmemcpy ||
> >> + BuiltinOp == Builtin::BI__builtin_wmemmove;
> >> + bool Move = BuiltinOp == Builtin::BImemmove ||
> >> + BuiltinOp == Builtin::BIwmemmove ||
> >> + BuiltinOp == Builtin::BI__builtin_memmove ||
> >> + BuiltinOp == Builtin::BI__builtin_wmemmove;
> >> +
> >> + // The result of mem* is the first argument.
> >> + if (!Visit(E->getArg(0)))
> >> + return false;
> >> + LValue Dest = Result;
> >> +
> >> + LValue Src;
> >> + if (!EvaluatePointer(E->getArg(1), Src, Info))
> >> + return false;
> >> +
> >> + APSInt N;
> >> + if (!EvaluateInteger(E->getArg(2), N, Info))
> >> + return false;
> >> + assert(!N.isSigned() && "memcpy and friends take an unsigned
> size");
> >> +
> >> + // If the size is zero, we treat this as always being a valid
> no-op.
> >> + // (Even if one of the src and dest pointers is null.)
> >> + if (!N)
> >> + return true;
> >> +
> >> + // We require that Src and Dest are both pointers to arrays of
> >> + // trivially-copyable type. (For the wide version, the designator
> >> will be
> >> + // invalid if the designated object is not a wchar_t.)
> >> + QualType T = Dest.Designator.getType(Info.Ctx);
> >> + QualType SrcT = Src.Designator.getType(Info.Ctx);
> >> + if (!Info.Ctx.hasSameUnqualifiedType(T, SrcT)) {
> >> + Info.FFDiag(E, diag::note_constexpr_memcpy_type_pun) << Move <<
> >> SrcT << T;
> >> + return false;
> >> + }
> >> + if (!T.isTriviallyCopyableType(Info.Ctx)) {
> >> + Info.FFDiag(E, diag::note_constexpr_memcpy_nontrivial) << Move <<
> >> T;
> >> + return false;
> >> + }
> >> +
> >> + // Figure out how many T's we're copying.
> >> + uint64_t TSize = Info.Ctx.getTypeSizeInChars(T).getQuantity();
> >> + if (!WChar) {
> >> + uint64_t Remainder;
> >> + llvm::APInt OrigN = N;
> >> + llvm::APInt::udivrem(OrigN, TSize, N, Remainder);
> >> + if (Remainder) {
> >> + Info.FFDiag(E, diag::note_constexpr_memcpy_unsupported)
> >> + << Move << WChar << 0 << T << OrigN.toString(10,
> >> /*Signed*/false)
> >> + << (unsigned)TSize;
> >> + return false;
> >> + }
> >> + }
> >> +
> >> + // Check that the copying will remain within the arrays, just so
> that
> >> we
> >> + // can give a more meaningful diagnostic. This implicitly also
> checks
> >> that
> >> + // N fits into 64 bits.
> >> + uint64_t RemainingSrcSize =
> >> Src.Designator.validIndexAdjustments().second;
> >> + uint64_t RemainingDestSize =
> >> Dest.Designator.validIndexAdjustments().second;
> >> + if (N.ugt(RemainingSrcSize) || N.ugt(RemainingDestSize)) {
> >> + Info.FFDiag(E, diag::note_constexpr_memcpy_unsupported)
> >> + << Move << WChar << (N.ugt(RemainingSrcSize) ? 1 : 2) << T
> >> + << N.toString(10, /*Signed*/false);
> >> + return false;
> >> + }
> >> + uint64_t NElems = N.getZExtValue();
> >> + uint64_t NBytes = NElems * TSize;
> >> +
> >> + // Check for overlap.
> >> + int Direction = 1;
> >> + if (HasSameBase(Src, Dest)) {
> >> + uint64_t SrcOffset = Src.getLValueOffset().getQuantity();
> >> + uint64_t DestOffset = Dest.getLValueOffset().getQuantity();
> >> + if (DestOffset >= SrcOffset && DestOffset - SrcOffset < NBytes) {
> >> + // Dest is inside the source region.
> >> + if (!Move) {
> >> + Info.FFDiag(E, diag::note_constexpr_memcpy_overlap) << WChar;
> >> + return false;
> >> + }
> >> + // For memmove and friends, copy backwards.
> >> + if (!HandleLValueArrayAdjustment(Info, E, Src, T, NElems - 1)
> ||
> >> + !HandleLValueArrayAdjustment(Info, E, Dest, T, NElems - 1))
> >> + return false;
> >> + Direction = -1;
> >> + } else if (!Move && SrcOffset >= DestOffset &&
> >> + SrcOffset - DestOffset < NBytes) {
> >> + // Src is inside the destination region for memcpy: invalid.
> >> + Info.FFDiag(E, diag::note_constexpr_memcpy_overlap) << WChar;
> >> + return false;
> >> + }
> >> + }
> >> +
> >> + while (true) {
> >> + APValue Val;
> >> + if (!handleLValueToRValueConversion(Info, E, T, Src, Val) ||
> >> + !handleAssignment(Info, E, Dest, T, Val))
> >> + return false;
> >> + // Do not iterate past the last element; if we're copying
> >> backwards, that
> >> + // might take us off the start of the array.
> >> + if (--NElems == 0)
> >> + return true;
> >> + if (!HandleLValueArrayAdjustment(Info, E, Src, T, Direction) ||
> >> + !HandleLValueArrayAdjustment(Info, E, Dest, T, Direction))
> >> + return false;
> >> + }
> >> + }
> >> +
> >> default:
> >> return visitNonBuiltinCallExpr(E);
> >> }
> >> @@ -8357,27 +8528,6 @@ bool IntExprEvaluator::VisitBuiltinCallE
> >> }
> >> }
> >>
> >> -static bool HasSameBase(const LValue &A, const LValue &B) {
> >> - if (!A.getLValueBase())
> >> - return !B.getLValueBase();
> >> - if (!B.getLValueBase())
> >> - return false;
> >> -
> >> - if (A.getLValueBase().getOpaqueValue() !=
> >> - B.getLValueBase().getOpaqueValue()) {
> >> - const Decl *ADecl = GetLValueBaseDecl(A);
> >> - if (!ADecl)
> >> - return false;
> >> - const Decl *BDecl = GetLValueBaseDecl(B);
> >> - if (!BDecl || ADecl->getCanonicalDecl() !=
> BDecl->getCanonicalDecl())
> >> - return false;
> >> - }
> >> -
> >> - return IsGlobalLValue(A.getLValueBase()) ||
> >> - (A.getLValueCallIndex() == B.getLValueCallIndex() &&
> >> - A.getLValueVersion() == B.getLValueVersion());
> >> -}
> >> -
> >> /// Determine whether this is a pointer past the end of the complete
> >> /// object referred to by the lvalue.
> >> static bool isOnePastTheEndOfCompleteObject(const ASTContext &Ctx,
> >>
> >> Modified: cfe/trunk/test/CodeGen/builtin-memfns.c
> >> URL:
> >>
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/builtin-memfns.c?rev=338455&r1=338454&r2=338455&view=diff
> >>
> >>
> ==============================================================================
> >> --- cfe/trunk/test/CodeGen/builtin-memfns.c (original)
> >> +++ cfe/trunk/test/CodeGen/builtin-memfns.c Tue Jul 31 16:35:09 2018
> >> @@ -1,5 +1,8 @@
> >> // RUN: %clang_cc1 -triple i386-pc-linux-gnu -emit-llvm < %s| FileCheck
> >> %s
> >>
> >> +typedef __WCHAR_TYPE__ wchar_t;
> >> +typedef __SIZE_TYPE__ size_t;
> >> +
> >> // CHECK: @test1
> >> // CHECK: call void @llvm.memset.p0i8.i32
> >> // CHECK: call void @llvm.memset.p0i8.i32
> >> @@ -83,3 +86,17 @@ void test9() {
> >> // CHECK: call void @llvm.memcpy{{.*}} align 16 {{.*}} align 16
> {{.*}}
> >> 16, i1 false)
> >> __builtin_memcpy(x, y, sizeof(y));
> >> }
> >> +
> >> +wchar_t dest;
> >> +wchar_t src;
> >> +
> >> +// CHECK-LABEL: @test10
> >> +// FIXME: Consider lowering these to llvm.memcpy / llvm.memmove.
> >> +void test10() {
> >> + // CHECK: call i32* @wmemcpy(i32* @dest, i32* @src, i32 4)
> >> + __builtin_wmemcpy(&dest, &src, 4);
> >> +
> >> + // CHECK: call i32* @wmemmove(i32* @dest, i32* @src, i32 4)
> >> + __builtin_wmemmove(&dest, &src, 4);
> >> +}
> >> +
> >>
> >> Modified: cfe/trunk/test/SemaCXX/constexpr-string.cpp
> >> URL:
> >>
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/constexpr-string.cpp?rev=338455&r1=338454&r2=338455&view=diff
> >>
> >>
> ==============================================================================
> >> --- cfe/trunk/test/SemaCXX/constexpr-string.cpp (original)
> >> +++ cfe/trunk/test/SemaCXX/constexpr-string.cpp Tue Jul 31 16:35:09 2018
> >> @@ -1,6 +1,6 @@
> >> -// RUN: %clang_cc1 %s -std=c++1z -fsyntax-only -verify -pedantic
> >> -// RUN: %clang_cc1 %s -std=c++1z -fsyntax-only -verify -pedantic
> >> -fno-signed-char
> >> -// RUN: %clang_cc1 %s -std=c++1z -fsyntax-only -verify -pedantic
> >> -fno-wchar -Dwchar_t=__WCHAR_TYPE__
> >> +// RUN: %clang_cc1 %s -triple x86_64-linux-gnu -std=c++1z -fsyntax-only
> >> -verify -pedantic
> >> +// RUN: %clang_cc1 %s -triple x86_64-linux-gnu -std=c++1z -fsyntax-only
> >> -verify -pedantic -fno-signed-char
> >> +// RUN: %clang_cc1 %s -triple x86_64-linux-gnu -std=c++1z -fsyntax-only
> >> -verify -pedantic -fno-wchar -Dwchar_t=__WCHAR_TYPE__
> >>
> >> # 6 "/usr/include/string.h" 1 3 4
> >> extern "C" {
> >> @@ -14,10 +14,13 @@ extern "C" {
> >>
> >> extern char *strchr(const char *s, int c);
> >> extern void *memchr(const void *s, int c, size_t n);
> >> +
> >> + extern void *memcpy(void *d, const void *s, size_t n);
> >> + extern void *memmove(void *d, const void *s, size_t n);
> >> }
> >> -# 19 "SemaCXX/constexpr-string.cpp" 2
> >> +# 22 "SemaCXX/constexpr-string.cpp" 2
> >>
> >> -# 21 "/usr/include/wchar.h" 1 3 4
> >> +# 24 "/usr/include/wchar.h" 1 3 4
> >> extern "C" {
> >> extern size_t wcslen(const wchar_t *p);
> >>
> >> @@ -27,9 +30,12 @@ extern "C" {
> >>
> >> extern wchar_t *wcschr(const wchar_t *s, wchar_t c);
> >> extern wchar_t *wmemchr(const wchar_t *s, wchar_t c, size_t n);
> >> +
> >> + extern wchar_t *wmemcpy(wchar_t *d, const wchar_t *s, size_t n);
> >> + extern wchar_t *wmemmove(wchar_t *d, const wchar_t *s, size_t n);
> >> }
> >>
> >> -# 33 "SemaCXX/constexpr-string.cpp" 2
> >> +# 39 "SemaCXX/constexpr-string.cpp" 2
> >> namespace Strlen {
> >> constexpr int n = __builtin_strlen("hello"); // ok
> >> static_assert(n == 5);
> >> @@ -235,3 +241,133 @@ namespace WcschrEtc {
> >> constexpr bool a = !wcschr(L"hello", L'h'); // expected-error
> >> {{constant expression}} expected-note {{non-constexpr function 'wcschr'
> >> cannot be used in a constant expression}}
> >> constexpr bool b = !wmemchr(L"hello", L'h', 3); // expected-error
> >> {{constant expression}} expected-note {{non-constexpr function 'wmemchr'
> >> cannot be used in a constant expression}}
> >> }
> >> +
> >> +namespace MemcpyEtc {
> >> + template<typename T>
> >> + constexpr T result(T (&arr)[4]) {
> >> + return arr[0] * 1000 + arr[1] * 100 + arr[2] * 10 + arr[3];
> >> + }
> >> +
> >> + constexpr int test_memcpy(int a, int b, int n) {
> >> + int arr[4] = {1, 2, 3, 4};
> >> + __builtin_memcpy(arr + a, arr + b, n);
> >> + // expected-note at -1 2{{overlapping memory regions}}
> >> + // expected-note at -2 {{size to copy (1) is not a multiple of size
> of
> >> element type 'int'}}
> >> + // expected-note at -3 {{source is not a contiguous array of at
> least 2
> >> elements of type 'int'}}
> >> + // expected-note at -4 {{destination is not a contiguous array of at
> >> least 3 elements of type 'int'}}
> >> + return result(arr);
> >> + }
> >> + constexpr int test_memmove(int a, int b, int n) {
> >> + int arr[4] = {1, 2, 3, 4};
> >> + __builtin_memmove(arr + a, arr + b, n);
> >> + // expected-note at -1 {{size to copy (1) is not a multiple of size
> of
> >> element type 'int'}}
> >> + // expected-note at -2 {{source is not a contiguous array of at
> least 2
> >> elements of type 'int'}}
> >> + // expected-note at -3 {{destination is not a contiguous array of at
> >> least 3 elements of type 'int'}}
> >> + return result(arr);
> >> + }
> >> + constexpr int test_wmemcpy(int a, int b, int n) {
> >> + wchar_t arr[4] = {1, 2, 3, 4};
> >> + __builtin_wmemcpy(arr + a, arr + b, n);
> >> + // expected-note at -1 2{{overlapping memory regions}}
> >> + // expected-note-re at -2 {{source is not a contiguous array of at
> least
> >> 2 elements of type '{{wchar_t|int}}'}}
> >> + // expected-note-re at -3 {{destination is not a contiguous array of
> at
> >> least 3 elements of type '{{wchar_t|int}}'}}
> >> + return result(arr);
> >> + }
> >> + constexpr int test_wmemmove(int a, int b, int n) {
> >> + wchar_t arr[4] = {1, 2, 3, 4};
> >> + __builtin_wmemmove(arr + a, arr + b, n);
> >> + // expected-note-re at -1 {{source is not a contiguous array of at
> least
> >> 2 elements of type '{{wchar_t|int}}'}}
> >> + // expected-note-re at -2 {{destination is not a contiguous array of
> at
> >> least 3 elements of type '{{wchar_t|int}}'}}
> >> + return result(arr);
> >> + }
> >> +
> >> + static_assert(test_memcpy(1, 2, 4) == 1334);
> >> + static_assert(test_memcpy(2, 1, 4) == 1224);
> >> + static_assert(test_memcpy(0, 1, 8) == 2334); // expected-error
> >> {{constant}} expected-note {{in call}}
> >> + static_assert(test_memcpy(1, 0, 8) == 1124); // expected-error
> >> {{constant}} expected-note {{in call}}
> >> + static_assert(test_memcpy(1, 2, 1) == 1334); // expected-error
> >> {{constant}} expected-note {{in call}}
> >> + static_assert(test_memcpy(0, 3, 4) == 4234);
> >> + static_assert(test_memcpy(0, 3, 8) == 4234); // expected-error
> >> {{constant}} expected-note {{in call}}
> >> + static_assert(test_memcpy(2, 0, 12) == 4234); // expected-error
> >> {{constant}} expected-note {{in call}}
> >> +
> >> + static_assert(test_memmove(1, 2, 4) == 1334);
> >> + static_assert(test_memmove(2, 1, 4) == 1224);
> >> + static_assert(test_memmove(0, 1, 8) == 2334);
> >> + static_assert(test_memmove(1, 0, 8) == 1124);
> >> + static_assert(test_memmove(1, 2, 1) == 1334); // expected-error
> >> {{constant}} expected-note {{in call}}
> >> + static_assert(test_memmove(0, 3, 4) == 4234);
> >> + static_assert(test_memmove(0, 3, 8) == 4234); // expected-error
> >> {{constant}} expected-note {{in call}}
> >> + static_assert(test_memmove(2, 0, 12) == 4234); // expected-error
> >> {{constant}} expected-note {{in call}}
> >> +
> >> + static_assert(test_wmemcpy(1, 2, 1) == 1334);
> >> + static_assert(test_wmemcpy(2, 1, 1) == 1224);
> >> + static_assert(test_wmemcpy(0, 1, 2) == 2334); // expected-error
> >> {{constant}} expected-note {{in call}}
> >> + static_assert(test_wmemcpy(1, 0, 2) == 1124); // expected-error
> >> {{constant}} expected-note {{in call}}
> >> + static_assert(test_wmemcpy(1, 2, 1) == 1334);
> >> + static_assert(test_wmemcpy(0, 3, 1) == 4234);
> >> + static_assert(test_wmemcpy(0, 3, 2) == 4234); // expected-error
> >> {{constant}} expected-note {{in call}}
> >> + static_assert(test_wmemcpy(2, 0, 3) == 4234); // expected-error
> >> {{constant}} expected-note {{in call}}
> >> +
> >> + static_assert(test_wmemmove(1, 2, 1) == 1334);
> >> + static_assert(test_wmemmove(2, 1, 1) == 1224);
> >> + static_assert(test_wmemmove(0, 1, 2) == 2334);
> >> + static_assert(test_wmemmove(1, 0, 2) == 1124);
> >> + static_assert(test_wmemmove(1, 2, 1) == 1334);
> >> + static_assert(test_wmemmove(0, 3, 1) == 4234);
> >> + static_assert(test_wmemmove(0, 3, 2) == 4234); // expected-error
> >> {{constant}} expected-note {{in call}}
> >> + static_assert(test_wmemmove(2, 0, 3) == 4234); // expected-error
> >> {{constant}} expected-note {{in call}}
> >> +
> >> + // Copying is permitted for any trivially-copyable type.
> >> + struct Trivial { char k; short s; constexpr bool ok() { return k == 3
> >> && s == 4; } };
> >> + constexpr bool test_trivial() {
> >> + Trivial arr[3] = {{1, 2}, {3, 4}, {5, 6}};
> >> + __builtin_memcpy(arr, arr+1, sizeof(Trivial));
> >> + __builtin_memmove(arr+1, arr, 2 * sizeof(Trivial));
> >> + return arr[0].ok() && arr[1].ok() && arr[2].ok();
> >> + }
> >> + static_assert(test_trivial());
> >> +
> >> + // But not for a non-trivially-copyable type.
> >> + struct NonTrivial {
> >> + constexpr NonTrivial() : n(0) {}
> >> + constexpr NonTrivial(const NonTrivial &) : n(1) {}
> >> + int n;
> >> + };
> >> + constexpr bool test_nontrivial_memcpy() { // expected-error {{never
> >> produces a constant}}
> >> + NonTrivial arr[3] = {};
> >> + __builtin_memcpy(arr, arr + 1, sizeof(NonTrivial)); //
> expected-note
> >> 2{{non-trivially-copyable}}
> >> + return true;
> >> + }
> >> + static_assert(test_nontrivial_memcpy()); // expected-error
> {{constant}}
> >> expected-note {{in call}}
> >> + constexpr bool test_nontrivial_memmove() { // expected-error {{never
> >> produces a constant}}
> >> + NonTrivial arr[3] = {};
> >> + __builtin_memcpy(arr, arr + 1, sizeof(NonTrivial)); //
> expected-note
> >> 2{{non-trivially-copyable}}
> >> + return true;
> >> + }
> >> + static_assert(test_nontrivial_memmove()); // expected-error
> >> {{constant}} expected-note {{in call}}
> >> +
> >> + // Type puns via constant evaluated memcpy are not supported yet.
> >> + constexpr float type_pun(const unsigned &n) {
> >> + float f = 0.0f;
> >> + __builtin_memcpy(&f, &n, 4); // expected-note {{cannot constant
> >> evaluate 'memcpy' from object of type 'const unsigned int' to object of
> type
> >> 'float'}}
> >> + return f;
> >> + }
> >> + static_assert(type_pun(0x3f800000) == 1.0f); // expected-error
> >> {{constant}} expected-note {{in call}}
> >> +
> >> + // Make sure we're not confused by derived-to-base conversions.
> >> + struct Base { int a; };
> >> + struct Derived : Base { int b; };
> >> + constexpr int test_derived_to_base(int n) {
> >> + Derived arr[2] = {1, 2, 3, 4};
> >> + Base *p = &arr[0];
> >> + Base *q = &arr[1];
> >> + __builtin_memcpy(p, q, sizeof(Base) * n); // expected-note {{source
> >> is not a contiguous array of at least 2 elements of type
> 'MemcpyEtc::Base'}}
> >> + return arr[0].a * 1000 + arr[0].b * 100 + arr[1].a * 10 + arr[1].b;
> >> + }
> >> + static_assert(test_derived_to_base(0) == 1234);
> >> + static_assert(test_derived_to_base(1) == 3234);
> >> + // FIXME: We could consider making this work by stripping elements
> off
> >> both
> >> + // designators until we have a long enough matching size, if both
> >> designators
> >> + // point to the start of their respective final elements.
> >> + static_assert(test_derived_to_base(2) == 3434); // expected-error
> >> {{constant}} expected-note {{in call}}
> >> +}
> >>
> >>
> >> _______________________________________________
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> >> cfe-commits at lists.llvm.org
> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
> >
> >
> > _______________________________________________
> > cfe-commits mailing list
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> > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
> >
> _______________________________________________
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