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Revert "Reapply "[libc++] Explicitly convert to masks in SIMD code (#107983)"" (#122022)

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Reverts llvm/llvm-project#121352

Triggers "vector type should not be a bool!" on:
```
  bool a[100];
  bool b[100];
  auto t = std::mismatch(std::begin(a), std::end(a), std::begin(b), std::end(b));
```

https://godbolt.org/z/Y73s3sdef
This commit is contained in:
Vitaly Buka 2025-01-08 09:14:39 -08:00 committed by GitHub
parent d4182f1b56
commit 570f03096a
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
2 changed files with 30 additions and 53 deletions
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8
libcxx/include/__algorithm/mismatch.h
View File

@ -78,7 +78,7 @@ __mismatch_vectorized(_Iter __first1, _Iter __last1, _Iter __first2) {
}
for (size_t __i = 0; __i != __unroll_count; ++__i) {
if (auto __cmp_res = std::__as_mask(__lhs[__i] == __rhs[__i]); !std::__all_of(__cmp_res)) {
if (auto __cmp_res = __lhs[__i] == __rhs[__i]; !std::__all_of(__cmp_res)) {
auto __offset = __i * __vec_size + std::__find_first_not_set(__cmp_res);
return {__first1 + __offset, __first2 + __offset};
}
@ -90,7 +90,7 @@ __mismatch_vectorized(_Iter __first1, _Iter __last1, _Iter __first2) {
// check the remaining 0-3 vectors
while (static_cast<size_t>(__last1 - __first1) >= __vec_size) {
if (auto __cmp_res = std::__as_mask(std::__load_vector<__vec>(__first1) == std::__load_vector<__vec>(__first2));
if (auto __cmp_res = std::__load_vector<__vec>(__first1) == std::__load_vector<__vec>(__first2);
!std::__all_of(__cmp_res)) {
auto __offset = std::__find_first_not_set(__cmp_res);
return {__first1 + __offset, __first2 + __offset};
@ -107,8 +107,8 @@ __mismatch_vectorized(_Iter __first1, _Iter __last1, _Iter __first2) {
if (static_cast<size_t>(__first1 - __orig_first1) >= __vec_size) {
__first1 = __last1 - __vec_size;
__first2 = __last2 - __vec_size;
auto __offset = std::__find_first_not_set(
std::__as_mask(std::__load_vector<__vec>(__first1) == std::__load_vector<__vec>(__first2)));
auto __offset =
std::__find_first_not_set(std::__load_vector<__vec>(__first1) == std::__load_vector<__vec>(__first2));
return {__first1 + __offset, __first2 + __offset};
} // else loop over the elements individually
}

75
libcxx/include/__algorithm/simd_utils.h
View File

@ -116,65 +116,42 @@ template <class _VecT, class _Iter>
}(make_index_sequence<__simd_vector_size_v<_VecT>>{});
}
template <size_t _Np>
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI bool __all_of(__simd_vector<bool, _Np> __vec) noexcept {
return __builtin_reduce_and(__vec);
template <class _Tp, size_t _Np>
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI bool __all_of(__simd_vector<_Tp, _Np> __vec) noexcept {
return __builtin_reduce_and(__builtin_convertvector(__vec, __simd_vector<bool, _Np>));
}
template <class _Tp, size_t _Np>
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI auto __as_mask(__simd_vector<_Tp, _Np> __vec) noexcept {
static_assert(!is_same<_Tp, bool>::value, "vector type should not be a bool!");
return __builtin_convertvector(__vec, __simd_vector<bool, _Np>);
}
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI size_t __find_first_set(__simd_vector<_Tp, _Np> __vec) noexcept {
using __mask_vec = __simd_vector<bool, _Np>;
// This uses __builtin_convertvector around the __builtin_shufflevector to work around #107981.
template <size_t _Np>
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI __simd_vector<bool, 8>
__extend_vector(__simd_vector<bool, _Np> __vec) noexcept {
using _VecT = __simd_vector<bool, _Np>;
if constexpr (_Np == 4) {
return __builtin_convertvector(
__builtin_shufflevector(__vec, _VecT{}, 0, 1, 2, 3, 4, 5, 6, 7), __simd_vector<bool, 8>);
} else if constexpr (_Np == 2) {
return std::__extend_vector(
__builtin_convertvector(__builtin_shufflevector(__vec, _VecT{}, 0, 1, 2, 3), __simd_vector<bool, 4>));
} else if constexpr (_Np == 1) {
return std::__extend_vector(
__builtin_convertvector(__builtin_shufflevector(__vec, _VecT{}, 0, 1), __simd_vector<bool, 2>));
} else {
static_assert(sizeof(_VecT) == 0, "Unexpected vector size");
}
}
// This has MSan disabled du to https://github.com/llvm/llvm-project/issues/85876
auto __impl = [&]<class _MaskT>(_MaskT) _LIBCPP_NO_SANITIZE("memory") noexcept {
# if defined(_LIBCPP_BIG_ENDIAN)
return std::min<size_t>(
_Np, std::__countl_zero(__builtin_bit_cast(_MaskT, __builtin_convertvector(__vec, __mask_vec))));
# else
return std::min<size_t>(
_Np, std::__countr_zero(__builtin_bit_cast(_MaskT, __builtin_convertvector(__vec, __mask_vec))));
# endif
};
template <size_t _Np>
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI auto __to_int_mask(__simd_vector<bool, _Np> __vec) {
if constexpr (_Np < 8) {
return std::__bit_cast<uint8_t>(std::__extend_vector(__vec));
} else if constexpr (_Np == 8) {
return std::__bit_cast<uint8_t>(__vec);
} else if constexpr (_Np == 16) {
return std::__bit_cast<uint16_t>(__vec);
} else if constexpr (_Np == 32) {
return std::__bit_cast<uint32_t>(__vec);
} else if constexpr (_Np == 64) {
return std::__bit_cast<uint64_t>(__vec);
if constexpr (sizeof(__mask_vec) == sizeof(uint8_t)) {
return __impl(uint8_t{});
} else if constexpr (sizeof(__mask_vec) == sizeof(uint16_t)) {
return __impl(uint16_t{});
} else if constexpr (sizeof(__mask_vec) == sizeof(uint32_t)) {
return __impl(uint32_t{});
} else if constexpr (sizeof(__mask_vec) == sizeof(uint64_t)) {
return __impl(uint64_t{});
} else {
static_assert(sizeof(__simd_vector<bool, _Np>) == 0, "Unexpected vector size");
static_assert(sizeof(__mask_vec) == 0, "unexpected required size for mask integer type");
return 0;
}
}
template <size_t _Np>
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI size_t __find_first_set(__simd_vector<bool, _Np> __vec) noexcept {
# if defined(_LIBCPP_BIG_ENDIAN)
return std::min<size_t>(_Np, std::__countl_zero(std::__to_int_mask(__vec)));
# else
return std::min<size_t>(_Np, std::__countr_zero(std::__to_int_mask(__vec)));
# endif
}
template <size_t _Np>
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI size_t __find_first_not_set(__simd_vector<bool, _Np> __vec) noexcept {
template <class _Tp, size_t _Np>
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI size_t __find_first_not_set(__simd_vector<_Tp, _Np> __vec) noexcept {
return std::__find_first_set(~__vec);
}