Skip to content

[libc++] Run vector instructions during constant evaluation when Clang supports it #160057

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Draft
wants to merge 1 commit into
base: main
Choose a base branch
from
+28 −8
Draft

[libc++] Run vector instructions during constant evaluation when Clang supports it #160057

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 1 addition & 1 deletion libcxx/include/__algorithm/mismatch.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -65,7 +65,7 @@ __mismatch_vectorized(_Iter __first1, _Iter __last1, _Iter __first2) {
constexpr size_t __vec_size = __native_vector_size<__value_type>;
using __vec = __simd_vector<__value_type, __vec_size>;

if (!__libcpp_is_constant_evaluated()) {
if (!__libcpp_is_constant_evaluated() || _LIBCPP_HAS_CONSTEXPR_VECTORS) {
auto __orig_first1 = __first1;
auto __last2 = __first2 + (__last1 - __first1);
while (static_cast<size_t>(__last1 - __first1) >= __unroll_count * __vec_size) [[__unlikely__]] {
Expand Down
34 changes: 27 additions & 7 deletions libcxx/include/__algorithm/simd_utils.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,14 @@ _LIBCPP_PUSH_MACROS

#if _LIBCPP_HAS_ALGORITHM_VECTOR_UTILS

# if defined(_LIBCPP_CLANG_VER) && _LIBCPP_CLANG_VER >= 2200
# define _LIBCPP_HAS_CONSTEXPR_VECTORS 1
# define _LIBCPP_VECTOR_CONSTEXPR _LIBCPP_CONSTEXPR
# else
# define _LIBCPP_HAS_CONSTEXPR_VECTORS 0
# define _LIBCPP_VECTOR_CONSTEXPR
# endif

_LIBCPP_BEGIN_NAMESPACE_STD

template <class _Tp>
Expand Down Expand Up @@ -108,30 +116,40 @@ using __simd_vector_underlying_type_t _LIBCPP_NODEBUG = decltype(std::__simd_vec

// This isn't inlined without always_inline when loading chars.
template <class _VecT, class _Iter>
[[__nodiscard__]] _LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _VecT __load_vector(_Iter __iter) noexcept {
[[__nodiscard__]] _LIBCPP_ALWAYS_INLINE _LIBCPP_HIDE_FROM_ABI _LIBCPP_VECTOR_CONSTEXPR _VecT
__load_vector(_Iter __iter) noexcept {
return [=]<size_t... _Indices>(index_sequence<_Indices...>) _LIBCPP_ALWAYS_INLINE noexcept {
return _VecT{__iter[_Indices]...};
}(make_index_sequence<__simd_vector_size_v<_VecT>>{});
}

template <class _Tp, size_t _Np>
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI bool __all_of(__simd_vector<_Tp, _Np> __vec) noexcept {
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_VECTOR_CONSTEXPR 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 size_t __find_first_set(__simd_vector<_Tp, _Np> __vec) noexcept {
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_VECTOR_CONSTEXPR size_t
__find_first_set(__simd_vector<_Tp, _Np> __vec) noexcept {
using __mask_vec = __simd_vector<bool, _Np>;

# if _LIBCPP_HAS_CONSTEXPR_VECTORS
# if defined(_LIBCPP_BIG_ENDIAN)
return __builtin_clzg(__builtin_convertvector(__vec, __mask_vec), static_cast<int>(_Np));
# else
return __builtin_ctzg(__builtin_convertvector(__vec, __mask_vec), static_cast<int>(_Np));
# endif
# else

// This has MSan disabled du to https://llvm.org/PR85876
auto __impl = [&]<class _MaskT>(_MaskT) _LIBCPP_NO_SANITIZE("memory") noexcept {
# if defined(_LIBCPP_BIG_ENDIAN)
# if defined(_LIBCPP_BIG_ENDIAN)
return std::min<size_t>(
_Np, std::__countl_zero(__builtin_bit_cast(_MaskT, __builtin_convertvector(__vec, __mask_vec))));
# else
# else
return std::min<size_t>(
_Np, std::__countr_zero(__builtin_bit_cast(_MaskT, __builtin_convertvector(__vec, __mask_vec))));
# endif
# endif
};

if constexpr (sizeof(__mask_vec) == sizeof(uint8_t)) {
Expand All @@ -146,10 +164,12 @@ template <class _Tp, size_t _Np>
static_assert(sizeof(__mask_vec) == 0, "unexpected required size for mask integer type");
return 0;
}
# endif
}

template <class _Tp, size_t _Np>
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI size_t __find_first_not_set(__simd_vector<_Tp, _Np> __vec) noexcept {
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_VECTOR_CONSTEXPR size_t
__find_first_not_set(__simd_vector<_Tp, _Np> __vec) noexcept {
return std::__find_first_set(~__vec);
}

Expand Down
Loading