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Use wmemchr in optimizations #4894

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merged 8 commits into from
Aug 25, 2024
Merged

Use wmemchr in optimizations #4894

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fbea7a2
Use wmemchr
AlexGuteniev Aug 15, 2024
b6ffa6e
missing include
AlexGuteniev Aug 15, 2024
6a451f9
Simplify 1 or 2 check
AlexGuteniev Aug 17, 2024
5ddb523
Count uniformly
AlexGuteniev Aug 18, 2024
7863bda
`<wchar.h>` => `<cwchar>`
StephanTLavavej Aug 23, 2024
446767b
`_1_or_2_bytes_elements` => `_Elements_are_1_or_2_bytes`
StephanTLavavej Aug 23, 2024
d35f89b
Update comment.
StephanTLavavej Aug 23, 2024
a9fa4e7
Simplify `const wchar_t*` / `wchar_t*` casting.
StephanTLavavej Aug 23, 2024
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42 changes: 29 additions & 13 deletions stl/inc/xutility
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@
#include <climits>
#include <cstdlib>
#include <cstring>
#include <cwchar>

#pragma pack(push, _CRT_PACKING)
#pragma warning(push, _STL_WARNING_LEVEL)
Expand Down Expand Up @@ -6009,17 +6010,27 @@ _NODISCARD _CONSTEXPR20 _InIt _Find_unchecked(_InIt _First, const _InIt _Last, c
return _First + (_Result - _First_ptr);
}
#else // ^^^ _USE_STD_VECTOR_ALGORITHMS / !_USE_STD_VECTOR_ALGORITHMS vvv
if constexpr (sizeof(_Iter_value_t<_InIt>) == 1) {
if constexpr (sizeof(_Iter_value_t<_InIt>) <= 2) {
const auto _First_ptr = _STD _To_address(_First);
const auto _Result = static_cast<remove_reference_t<_Iter_ref_t<_InIt>>*>(
_CSTD memchr(_First_ptr, static_cast<unsigned char>(_Val), static_cast<size_t>(_Last - _First)));
const auto _Count = static_cast<size_t>(_Last - _First);

using _Ptr_t = remove_reference_t<_Iter_ref_t<_InIt>>*;
_Ptr_t _Result;

if constexpr (sizeof(_Iter_value_t<_InIt>) == 1) {
_Result = static_cast<_Ptr_t>(_CSTD memchr(_First_ptr, static_cast<unsigned char>(_Val), _Count));
} else {
_STL_INTERNAL_STATIC_ASSERT(sizeof(_Iter_value_t<_InIt>) == 2);
_Result = reinterpret_cast<_Ptr_t>(const_cast<wchar_t*>(_CSTD wmemchr(
reinterpret_cast<const wchar_t*>(_First_ptr), static_cast<wchar_t>(_Val), _Count)));
}

if constexpr (is_pointer_v<_InIt>) {
return _Result ? _Result : _Last;
} else {
return _Result ? _First + (_Result - _First_ptr) : _Last;
}
}
// TRANSITION, DevCom-1614562: not trying wmemchr
#endif // ^^^ !_USE_STD_VECTOR_ALGORITHMS ^^^
}
}
Expand Down Expand Up @@ -6062,14 +6073,12 @@ namespace ranges {
template <input_iterator _It, sentinel_for<_It> _Se, class _Ty, class _Pj = identity>
requires indirect_binary_predicate<ranges::equal_to, projected<_It, _Pj>, const _Ty*>
_NODISCARD constexpr _It _Find_unchecked(_It _First, const _Se _Last, const _Ty& _Val, _Pj _Proj = {}) {
// TRANSITION, DevCom-1614562: not trying wmemchr
// Only single-byte elements are suitable for unsized optimization
constexpr bool _Single_byte_elements = sizeof(_Iter_value_t<_It>) == 1;
constexpr bool _Is_sized = sized_sentinel_for<_Se, _It>;
constexpr bool _Elements_are_1_or_2_bytes = sizeof(_Iter_value_t<_It>) <= 2;
constexpr bool _Is_sized = sized_sentinel_for<_Se, _It>;

if constexpr (_Vector_alg_in_find_is_safe<_It, _Ty>
&& (_Single_byte_elements ? _Is_sized || same_as<_Se, unreachable_sentinel_t>
: _Is_sized && _USE_STD_VECTOR_ALGORITHMS)
&& (_Elements_are_1_or_2_bytes ? _Is_sized || same_as<_Se, unreachable_sentinel_t>
: _Is_sized && _USE_STD_VECTOR_ALGORITHMS)
&& same_as<_Pj, identity>) {
if (!_STD is_constant_evaluated()) {
if (!_STD _Could_compare_equal_to_value_type<_It>(_Val)) {
Expand All @@ -6087,21 +6096,28 @@ namespace ranges {
_Ptr_t _Result;
#if _USE_STD_VECTOR_ALGORITHMS
if constexpr (_Is_sized) {
// When _Is_sized && _Single_byte_elements, prefer this over memchr() for performance
// When _Is_sized && _Elements_are_1_or_2_bytes, prefer this over memchr()/wmemchr() for performance
const auto _Last_ptr = _First_ptr + (_Last - _First);
_Result = _STD _Find_vectorized(_First_ptr, _Last_ptr, _Val);
} else
#endif // ^^^ _USE_STD_VECTOR_ALGORITHMS ^^^
{
_STL_INTERNAL_STATIC_ASSERT(_Single_byte_elements);
_STL_INTERNAL_STATIC_ASSERT(_Elements_are_1_or_2_bytes);
size_t _Count;
if constexpr (_Is_sized) {
_Count = static_cast<size_t>(_Last - _First);
} else {
_Count = SIZE_MAX;
}

_Result = static_cast<_Ptr_t>(_CSTD memchr(_First_ptr, static_cast<unsigned char>(_Val), _Count));
if constexpr (sizeof(_Iter_value_t<_It>) == 1) {
_Result =
static_cast<_Ptr_t>(_CSTD memchr(_First_ptr, static_cast<unsigned char>(_Val), _Count));
} else {
_STL_INTERNAL_STATIC_ASSERT(sizeof(_Iter_value_t<_It>) == 2);
_Result = reinterpret_cast<_Ptr_t>(const_cast<wchar_t*>(_CSTD wmemchr(
reinterpret_cast<const wchar_t*>(_First_ptr), static_cast<wchar_t>(_Val), _Count)));
}

if constexpr (_Is_sized) {
if (_Result == nullptr) {
Expand Down
4 changes: 2 additions & 2 deletions stl/src/vector_algorithms.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@
#include <__msvc_minmax.hpp>
#include <cstdint>
#include <cstring>
#include <cwchar>
#include <xtr1common>

#ifndef _M_ARM64EC
Expand Down Expand Up @@ -3271,8 +3272,7 @@ const void* __stdcall __std_find_trivial_unsized_1(const void* const _First, con

// TRANSITION, ABI: preserved for binary compatibility
const void* __stdcall __std_find_trivial_unsized_2(const void* const _First, const uint16_t _Val) noexcept {
// TRANSITION, DevCom-1614562: not trying wmemchr
return __std_find_trivial_unsized_impl(_First, _Val);
return wmemchr(static_cast<const wchar_t*>(_First), static_cast<wchar_t>(_Val), SIZE_MAX);
}

// TRANSITION, ABI: preserved for binary compatibility
Expand Down