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AK: Use bit_cast in SIMDExtras.h/AK::Detail::byte_reverse_impl

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This necessitates marking bit_cast as ALWAYS_INLINE since emitting it as
a function call there will create an unnecessary potential SSE
registers -> plain registers/memory round-trip.
This commit is contained in:
Dan Klishch 2024-07-05 12:46:18 -04:00 committed by Nico Weber
parent 56b7f9e404
commit 2b65b62c6e
2 changed files with 6 additions and 7 deletions
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2
AK/BitCast.h
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@ -11,7 +11,7 @@
namespace AK {
template<typename T, typename U>
[[nodiscard]] constexpr inline T bit_cast(U const& a)
[[nodiscard]] constexpr ALWAYS_INLINE T bit_cast(U const& a)
{
#if (__has_builtin(__builtin_bit_cast))
return __builtin_bit_cast(T, a);

11
AK/SIMDExtras.h
View file

@ -254,12 +254,11 @@ ALWAYS_INLINE static T byte_reverse_impl(T a, IndexSequence<Idx...>)
// Hence this giant conditional
using BytesVector = Conditional<sizeof(T) == 2, u8x2, Conditional<sizeof(T) == 4, u8x4, Conditional<sizeof(T) == 8, u8x8, Conditional<sizeof(T) == 16, u8x16, Conditional<sizeof(T) == 32, u8x32, void>>>>>;
static_assert(sizeof(BytesVector) == sizeof(T));
// Note: Using __builtin_bit_cast instead of bit_cast to avoid a psabi warning from bit_cast
auto tmp = __builtin_shufflevector(
__builtin_bit_cast(BytesVector, a),
__builtin_bit_cast(BytesVector, a),
N - 1 - Idx...);
return __builtin_bit_cast(T, tmp);
return bit_cast<T>(
__builtin_shufflevector(
bit_cast<BytesVector>(a),
bit_cast<BytesVector>(a),
N - 1 - Idx...));
}
template<SIMDVector T, size_t... Idx>