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[clang][bytecode] Implement __builtin_wmem{cpy,move} #135969

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Merged
merged 1 commit into from
Apr 16, 2025
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[clang][bytecode] Implement __builtin_wmem{cpy,move} #135969

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30 changes: 22 additions & 8 deletions clang/lib/AST/ByteCode/InterpBuiltin.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1792,14 +1792,18 @@ static bool interp__builtin_memcpy(InterpState &S, CodePtr OpPC,
Pointer DestPtr = getParam<Pointer>(Frame, 0);
const ASTContext &ASTCtx = S.getASTContext();
const Pointer &SrcPtr = getParam<Pointer>(Frame, 1);
const APSInt &Size =
peekToAPSInt(S.Stk, *S.getContext().classify(Call->getArg(2)));
APSInt Size = peekToAPSInt(S.Stk, *S.getContext().classify(Call->getArg(2)));
assert(!Size.isSigned() && "memcpy and friends take an unsigned size");

if (ID == Builtin::BImemcpy || ID == Builtin::BImemmove)
diagnoseNonConstexprBuiltin(S, OpPC, ID);

bool Move = (ID == Builtin::BI__builtin_memmove || ID == Builtin::BImemmove);
bool Move =
(ID == Builtin::BI__builtin_memmove || ID == Builtin::BImemmove ||
ID == Builtin::BI__builtin_wmemmove || ID == Builtin::BIwmemmove);
bool WChar = ID == Builtin::BIwmemcpy || ID == Builtin::BIwmemmove ||
ID == Builtin::BI__builtin_wmemcpy ||
ID == Builtin::BI__builtin_wmemmove;

// If the size is zero, we treat this as always being a valid no-op.
if (Size.isZero()) {
Expand All @@ -1810,7 +1814,7 @@ static bool interp__builtin_memcpy(InterpState &S, CodePtr OpPC,
if (SrcPtr.isZero() || DestPtr.isZero()) {
Pointer DiagPtr = (SrcPtr.isZero() ? SrcPtr : DestPtr);
S.FFDiag(S.Current->getSource(OpPC), diag::note_constexpr_memcpy_null)
<< /*IsMove=*/Move << /*IsWchar=*/false << !SrcPtr.isZero()
<< /*IsMove=*/Move << /*IsWchar=*/WChar << !SrcPtr.isZero()
<< DiagPtr.toDiagnosticString(ASTCtx);
return false;
}
Expand All @@ -1822,7 +1826,7 @@ static bool interp__builtin_memcpy(InterpState &S, CodePtr OpPC,
? std::to_string(SrcPtr.getIntegerRepresentation())
: std::to_string(DestPtr.getIntegerRepresentation());
S.FFDiag(S.Current->getSource(OpPC), diag::note_constexpr_memcpy_null)
<< Move << false << DestPtr.isIntegralPointer() << DiagVal;
<< Move << WChar << DestPtr.isIntegralPointer() << DiagVal;
return false;
}

Expand All @@ -1841,11 +1845,17 @@ static bool interp__builtin_memcpy(InterpState &S, CodePtr OpPC,
}
unsigned DestElemSize = ASTCtx.getTypeSizeInChars(DestElemType).getQuantity();

if (WChar) {
uint64_t WCharSize =
ASTCtx.getTypeSizeInChars(ASTCtx.getWCharType()).getQuantity();
Size *= APSInt(APInt(Size.getBitWidth(), WCharSize, /*IsSigned=*/false),
/*IsUnsigend=*/true);
}

if (Size.urem(DestElemSize) != 0) {
S.FFDiag(S.Current->getSource(OpPC),
diag::note_constexpr_memcpy_unsupported)
<< Move << /*IsWchar=*/false << 0 << DestElemType << Size
<< DestElemSize;
<< Move << WChar << 0 << DestElemType << Size << DestElemSize;
return false;
}

Expand Down Expand Up @@ -1873,7 +1883,7 @@ static bool interp__builtin_memcpy(InterpState &S, CodePtr OpPC,
APInt N = Size.udiv(DestElemSize);
S.FFDiag(S.Current->getSource(OpPC),
diag::note_constexpr_memcpy_unsupported)
<< Move << /*IsWChar*/ false << (Size.ugt(RemainingSrcBytes) ? 1 : 2)
<< Move << WChar << (Size.ugt(RemainingSrcBytes) ? 1 : 2)
<< DestElemType << toString(N, 10, /*Signed=*/false);
return false;
}
Expand Down Expand Up @@ -2591,8 +2601,12 @@ bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const Function *F,

case Builtin::BI__builtin_memcpy:
case Builtin::BImemcpy:
case Builtin::BI__builtin_wmemcpy:
case Builtin::BIwmemcpy:
case Builtin::BI__builtin_memmove:
case Builtin::BImemmove:
case Builtin::BI__builtin_wmemmove:
case Builtin::BIwmemmove:
if (!interp__builtin_memcpy(S, OpPC, Frame, F, Call))
return false;
break;
Expand Down
62 changes: 62 additions & 0 deletions clang/test/AST/ByteCode/builtin-functions.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@ extern "C" {
extern wchar_t *wcschr(const wchar_t *s, wchar_t c);
extern int wcscmp(const wchar_t *s1, const wchar_t *s2);
extern int wcsncmp(const wchar_t *s1, const wchar_t *s2, size_t n);
extern wchar_t *wmemcpy(wchar_t *d, const wchar_t *s, size_t n);
}

namespace strcmp {
Expand Down Expand Up @@ -1592,6 +1593,67 @@ namespace WMemChr {
// both-note {{non-constexpr function 'wcschr' cannot be used in a constant expression}}
}

namespace WMemCpy {
template<typename T>
constexpr T result(T (&arr)[4]) {
return arr[0] * 1000 + arr[1] * 100 + arr[2] * 10 + arr[3];
}
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);
// both-note@-1 2{{overlapping memory regions}}
// both-note@-2 {{source is not a contiguous array of at least 2 elements of type 'wchar_t'}}
// both-note@-3 {{destination is not a contiguous array of at least 3 elements of type 'wchar_t'}}
return result(arr);
}
static_assert(test_wmemcpy(1, 2, 1) == 1334);
static_assert(test_wmemcpy(2, 1, 1) == 1224);
static_assert(test_wmemcpy(0, 1, 2) == 2334); // both-error {{constant}} both-note {{in call}}
static_assert(test_wmemcpy(1, 0, 2) == 1124); // both-error {{constant}} both-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); // both-error {{constant}} both-note {{in call}}
static_assert(test_wmemcpy(2, 0, 3) == 4234); // both-error {{constant}} both-note {{in call}}

wchar_t global;
constexpr wchar_t *null = 0;
static_assert(__builtin_wmemcpy(&global, null, sizeof(wchar_t))); // both-error {{}} \
// both-note {{source of 'wmemcpy' is nullptr}}
static_assert(__builtin_wmemcpy(null, &global, sizeof(wchar_t))); // both-error {{}} \
// both-note {{destination of 'wmemcpy' is nullptr}}
}

namespace WMemMove {
template<typename T>
constexpr T result(T (&arr)[4]) {
return arr[0] * 1000 + arr[1] * 100 + arr[2] * 10 + arr[3];
}

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);
// both-note@-1 {{source is not a contiguous array of at least 2 elements of type 'wchar_t'}}
// both-note@-2 {{destination is not a contiguous array of at least 3 elements of type 'wchar_t'}}
return result(arr);
}

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); // both-error {{constant}} both-note {{in call}}
static_assert(test_wmemmove(2, 0, 3) == 4234); // both-error {{constant}} both-note {{in call}}

wchar_t global;
constexpr wchar_t *null = 0;
static_assert(__builtin_wmemmove(&global, null, sizeof(wchar_t))); // both-error {{}} \
// both-note {{source of 'wmemmove' is nullptr}}
static_assert(__builtin_wmemmove(null, &global, sizeof(wchar_t))); // both-error {{}} \
// both-note {{destination of 'wmemmove' is nullptr}}
}

namespace Invalid {
constexpr int test() { // both-error {{never produces a constant expression}}
__builtin_abort(); // both-note 2{{subexpression not valid in a constant expression}}
Expand Down
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