| //===-- x86 implementation of memory function building blocks -------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file provides x86 specific building blocks to compose memory functions. |
| // |
| //===----------------------------------------------------------------------===// |
| #ifndef LLVM_LIBC_SRC_STRING_MEMORY_UTILS_OP_X86_H |
| #define LLVM_LIBC_SRC_STRING_MEMORY_UTILS_OP_X86_H |
| |
| #include "src/__support/macros/attributes.h" // LIBC_INLINE |
| #include "src/__support/macros/config.h" // LIBC_NAMESPACE_DECL |
| #include "src/__support/macros/properties/architectures.h" |
| |
| #if defined(LIBC_TARGET_ARCH_IS_X86) |
| |
| #include "src/__support/common.h" |
| #include "src/string/memory_utils/op_builtin.h" |
| #include "src/string/memory_utils/op_generic.h" |
| |
| #if defined(__AVX512BW__) || defined(__AVX512F__) || defined(__AVX2__) || \ |
| defined(__SSE2__) |
| #include <immintrin.h> |
| #endif |
| |
| // Define fake functions to prevent the compiler from failing on undefined |
| // functions in case the CPU extension is not present. |
| #if !defined(__AVX512BW__) && (defined(_MSC_VER) || defined(__SCE__)) |
| #undef _mm512_cmpneq_epi8_mask |
| #define _mm512_cmpneq_epi8_mask(A, B) 0 |
| #endif |
| #if !defined(__AVX2__) && (defined(_MSC_VER) || defined(__SCE__)) |
| #undef _mm256_movemask_epi8 |
| #define _mm256_movemask_epi8(A) 0 |
| #endif |
| #if !defined(__SSE2__) && (defined(_MSC_VER) || defined(__SCE__)) |
| #undef _mm_movemask_epi8 |
| #define _mm_movemask_epi8(A) 0 |
| #endif |
| |
| namespace LIBC_NAMESPACE_DECL { |
| namespace x86 { |
| |
| // A set of constants to check compile time features. |
| LIBC_INLINE_VAR constexpr bool K_SSE2 = LLVM_LIBC_IS_DEFINED(__SSE2__); |
| LIBC_INLINE_VAR constexpr bool K_SSE41 = LLVM_LIBC_IS_DEFINED(__SSE4_1__); |
| LIBC_INLINE_VAR constexpr bool K_AVX = LLVM_LIBC_IS_DEFINED(__AVX__); |
| LIBC_INLINE_VAR constexpr bool K_AVX2 = LLVM_LIBC_IS_DEFINED(__AVX2__); |
| LIBC_INLINE_VAR constexpr bool K_AVX512_F = LLVM_LIBC_IS_DEFINED(__AVX512F__); |
| LIBC_INLINE_VAR constexpr bool K_AVX512_BW = LLVM_LIBC_IS_DEFINED(__AVX512BW__); |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| // Memcpy repmovsb implementation |
| struct Memcpy { |
| LIBC_INLINE static void repmovsb(void *dst, const void *src, size_t count) { |
| asm volatile("rep movsb" : "+D"(dst), "+S"(src), "+c"(count) : : "memory"); |
| } |
| }; |
| |
| } // namespace x86 |
| } // namespace LIBC_NAMESPACE_DECL |
| |
| namespace LIBC_NAMESPACE_DECL { |
| namespace generic { |
| |
| // Not equals: returns non-zero iff values at head or tail differ. |
| // This function typically loads more data than necessary when the two buffer |
| // differs. |
| template <typename T> |
| LIBC_INLINE uint32_t branchless_head_tail_neq(CPtr p1, CPtr p2, size_t count) { |
| static_assert(cpp::is_integral_v<T>); |
| return neq<T>(p1, p2, 0) | neq<T>(p1, p2, count - sizeof(T)); |
| } |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| // Specializations for uint16_t |
| template <> struct cmp_is_expensive<uint16_t> : public cpp::false_type {}; |
| template <> LIBC_INLINE bool eq<uint16_t>(CPtr p1, CPtr p2, size_t offset) { |
| return load<uint16_t>(p1, offset) == load<uint16_t>(p2, offset); |
| } |
| template <> |
| LIBC_INLINE uint32_t neq<uint16_t>(CPtr p1, CPtr p2, size_t offset) { |
| return load<uint16_t>(p1, offset) ^ load<uint16_t>(p2, offset); |
| } |
| template <> |
| LIBC_INLINE MemcmpReturnType cmp<uint16_t>(CPtr p1, CPtr p2, size_t offset) { |
| return static_cast<int32_t>(load_be<uint16_t>(p1, offset)) - |
| static_cast<int32_t>(load_be<uint16_t>(p2, offset)); |
| } |
| template <> |
| LIBC_INLINE MemcmpReturnType cmp_neq<uint16_t>(CPtr p1, CPtr p2, size_t offset); |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| // Specializations for uint32_t |
| template <> struct cmp_is_expensive<uint32_t> : public cpp::false_type {}; |
| template <> LIBC_INLINE bool eq<uint32_t>(CPtr p1, CPtr p2, size_t offset) { |
| return load<uint32_t>(p1, offset) == load<uint32_t>(p2, offset); |
| } |
| template <> |
| LIBC_INLINE uint32_t neq<uint32_t>(CPtr p1, CPtr p2, size_t offset) { |
| return load<uint32_t>(p1, offset) ^ load<uint32_t>(p2, offset); |
| } |
| template <> |
| LIBC_INLINE MemcmpReturnType cmp<uint32_t>(CPtr p1, CPtr p2, size_t offset) { |
| const auto a = load_be<uint32_t>(p1, offset); |
| const auto b = load_be<uint32_t>(p2, offset); |
| return cmp_uint32_t(a, b); |
| } |
| template <> |
| LIBC_INLINE MemcmpReturnType cmp_neq<uint32_t>(CPtr p1, CPtr p2, size_t offset); |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| // Specializations for uint64_t |
| template <> struct cmp_is_expensive<uint64_t> : public cpp::true_type {}; |
| template <> LIBC_INLINE bool eq<uint64_t>(CPtr p1, CPtr p2, size_t offset) { |
| return load<uint64_t>(p1, offset) == load<uint64_t>(p2, offset); |
| } |
| template <> |
| LIBC_INLINE uint32_t neq<uint64_t>(CPtr p1, CPtr p2, size_t offset) { |
| return !eq<uint64_t>(p1, p2, offset); |
| } |
| template <> |
| LIBC_INLINE MemcmpReturnType cmp<uint64_t>(CPtr p1, CPtr p2, size_t offset); |
| template <> |
| LIBC_INLINE MemcmpReturnType cmp_neq<uint64_t>(CPtr p1, CPtr p2, |
| size_t offset) { |
| const auto a = load_be<uint64_t>(p1, offset); |
| const auto b = load_be<uint64_t>(p2, offset); |
| return cmp_neq_uint64_t(a, b); |
| } |
| |
| // SIMD types are defined with attributes. e.g., '__m128i' is defined as |
| // long long __attribute__((__vector_size__(16), __aligned__(16))) |
| // When we use these SIMD types in template specialization GCC complains: |
| // "ignoring attributes on template argument ‘__m128i’ [-Wignored-attributes]" |
| // Therefore, we disable this warning in this file. |
| #pragma GCC diagnostic push |
| #pragma GCC diagnostic ignored "-Wignored-attributes" |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| // Specializations for __m128i |
| #if defined(__SSE4_1__) |
| template <> struct is_vector<__m128i> : cpp::true_type {}; |
| template <> struct cmp_is_expensive<__m128i> : cpp::true_type {}; |
| LIBC_INLINE __m128i load_and_xor_m128i(CPtr p1, CPtr p2, size_t offset) { |
| const auto a = load<__m128i>(p1, offset); |
| const auto b = load<__m128i>(p2, offset); |
| return _mm_xor_si128(a, b); |
| } |
| LIBC_INLINE __m128i bytewise_max(__m128i a, __m128i b) { |
| return _mm_max_epu8(a, b); |
| } |
| LIBC_INLINE __m128i bytewise_reverse(__m128i value) { |
| return _mm_shuffle_epi8(value, _mm_set_epi8(0, 1, 2, 3, 4, 5, 6, 7, // |
| 8, 9, 10, 11, 12, 13, 14, 15)); |
| } |
| LIBC_INLINE uint16_t big_endian_cmp_mask(__m128i max, __m128i value) { |
| return static_cast<uint16_t>( |
| _mm_movemask_epi8(bytewise_reverse(_mm_cmpeq_epi8(max, value)))); |
| } |
| LIBC_INLINE bool is_zero(__m128i value) { |
| return _mm_testz_si128(value, value) == 1; |
| } |
| template <> LIBC_INLINE bool eq<__m128i>(CPtr p1, CPtr p2, size_t offset) { |
| return is_zero(load_and_xor_m128i(p1, p2, offset)); |
| } |
| template <> LIBC_INLINE uint32_t neq<__m128i>(CPtr p1, CPtr p2, size_t offset) { |
| return !is_zero(load_and_xor_m128i(p1, p2, offset)); |
| } |
| template <> |
| LIBC_INLINE uint32_t branchless_head_tail_neq<__m128i>(CPtr p1, CPtr p2, |
| size_t count) { |
| const __m128i head = load_and_xor_m128i(p1, p2, 0); |
| const __m128i tail = load_and_xor_m128i(p1, p2, count - sizeof(__m128i)); |
| return !is_zero(_mm_or_si128(head, tail)); |
| } |
| template <> |
| LIBC_INLINE MemcmpReturnType cmp_neq<__m128i>(CPtr p1, CPtr p2, size_t offset) { |
| const auto a = load<__m128i>(p1, offset); |
| const auto b = load<__m128i>(p2, offset); |
| const auto vmax = bytewise_max(a, b); |
| const auto le = big_endian_cmp_mask(vmax, b); |
| const auto ge = big_endian_cmp_mask(vmax, a); |
| static_assert(cpp::is_same_v<cpp::remove_cv_t<decltype(le)>, uint16_t>); |
| return static_cast<int32_t>(ge) - static_cast<int32_t>(le); |
| } |
| #endif // __SSE4_1__ |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| // Specializations for __m256i |
| #if defined(__AVX__) |
| template <> struct is_vector<__m256i> : cpp::true_type {}; |
| template <> struct cmp_is_expensive<__m256i> : cpp::true_type {}; |
| LIBC_INLINE __m256i xor_m256i(__m256i a, __m256i b) { |
| return _mm256_castps_si256( |
| _mm256_xor_ps(_mm256_castsi256_ps(a), _mm256_castsi256_ps(b))); |
| } |
| LIBC_INLINE __m256i or_m256i(__m256i a, __m256i b) { |
| return _mm256_castps_si256( |
| _mm256_or_ps(_mm256_castsi256_ps(a), _mm256_castsi256_ps(b))); |
| } |
| LIBC_INLINE __m256i load_and_xor_m256i(CPtr p1, CPtr p2, size_t offset) { |
| const auto a = load<__m256i>(p1, offset); |
| const auto b = load<__m256i>(p2, offset); |
| return xor_m256i(a, b); |
| } |
| LIBC_INLINE bool is_zero(__m256i value) { |
| return _mm256_testz_si256(value, value) == 1; |
| } |
| template <> LIBC_INLINE bool eq<__m256i>(CPtr p1, CPtr p2, size_t offset) { |
| return is_zero(load_and_xor_m256i(p1, p2, offset)); |
| } |
| template <> LIBC_INLINE uint32_t neq<__m256i>(CPtr p1, CPtr p2, size_t offset) { |
| return !is_zero(load_and_xor_m256i(p1, p2, offset)); |
| } |
| template <> |
| LIBC_INLINE uint32_t branchless_head_tail_neq<__m256i>(CPtr p1, CPtr p2, |
| size_t count) { |
| const __m256i head = load_and_xor_m256i(p1, p2, 0); |
| const __m256i tail = load_and_xor_m256i(p1, p2, count - sizeof(__m256i)); |
| return !is_zero(or_m256i(head, tail)); |
| } |
| #endif // __AVX__ |
| |
| #if defined(__AVX2__) |
| LIBC_INLINE __m256i bytewise_max(__m256i a, __m256i b) { |
| return _mm256_max_epu8(a, b); |
| } |
| LIBC_INLINE uint32_t big_endian_cmp_mask(__m256i max, __m256i value) { |
| // Bytewise comparison of 'max' and 'value'. |
| const __m256i little_endian_byte_mask = _mm256_cmpeq_epi8(max, value); |
| // Because x86 is little endian, bytes in the vector must be reversed before |
| // using movemask. |
| #if defined(__AVX512VBMI__) && defined(__AVX512VL__) |
| // When AVX512BMI is available we can completely reverse the vector through |
| // VPERMB __m256i _mm256_permutexvar_epi8( __m256i idx, __m256i a); |
| const __m256i big_endian_byte_mask = |
| _mm256_permutexvar_epi8(_mm256_set_epi8(0, 1, 2, 3, 4, 5, 6, 7, // |
| 8, 9, 10, 11, 12, 13, 14, 15, // |
| 16, 17, 18, 19, 20, 21, 22, 23, // |
| 24, 25, 26, 27, 28, 29, 30, 31), |
| little_endian_byte_mask); |
| // And turn the byte vector mask into an 'uint32_t' for direct scalar |
| // comparison. |
| return _mm256_movemask_epi8(big_endian_byte_mask); |
| #else |
| // We can't byte-reverse '__m256i' in a single instruction with AVX2. |
| // '_mm256_shuffle_epi8' can only shuffle within each 16-byte lane |
| // leading to: |
| // ymm = ymm[15,14,13,12,11,10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, |
| // 31,30,29,28,27,26,25,24,23,22,21,20,19,18,17,16] |
| // So we first shuffle each 16-byte lane leading to half-reversed vector mask. |
| const __m256i half_reversed = _mm256_shuffle_epi8( |
| little_endian_byte_mask, _mm256_set_epi8(0, 1, 2, 3, 4, 5, 6, 7, // |
| 8, 9, 10, 11, 12, 13, 14, 15, // |
| 0, 1, 2, 3, 4, 5, 6, 7, // |
| 8, 9, 10, 11, 12, 13, 14, 15)); |
| // Then we turn the vector into an uint32_t. |
| const uint32_t half_reversed_scalar = _mm256_movemask_epi8(half_reversed); |
| // And swap the lower and upper parts. This is optimized into a single `rorx` |
| // instruction. |
| return (half_reversed_scalar << 16) | (half_reversed_scalar >> 16); |
| #endif |
| } |
| template <> |
| LIBC_INLINE MemcmpReturnType cmp_neq<__m256i>(CPtr p1, CPtr p2, size_t offset) { |
| const auto a = load<__m256i>(p1, offset); |
| const auto b = load<__m256i>(p2, offset); |
| const auto vmax = bytewise_max(a, b); |
| const auto le = big_endian_cmp_mask(vmax, b); |
| const auto ge = big_endian_cmp_mask(vmax, a); |
| static_assert(cpp::is_same_v<cpp::remove_cv_t<decltype(le)>, uint32_t>); |
| return cmp_neq_uint64_t(ge, le); |
| } |
| #endif // __AVX2__ |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| // Specializations for __m512i |
| #if defined(__AVX512BW__) |
| template <> struct is_vector<__m512i> : cpp::true_type {}; |
| template <> struct cmp_is_expensive<__m512i> : cpp::true_type {}; |
| LIBC_INLINE __m512i bytewise_max(__m512i a, __m512i b) { |
| return _mm512_max_epu8(a, b); |
| } |
| LIBC_INLINE uint64_t big_endian_cmp_mask(__m512i max, __m512i value) { |
| // The AVX512BMI version is disabled due to bad codegen. |
| // https://github.com/llvm/llvm-project/issues/77459 |
| // https://github.com/llvm/llvm-project/pull/77081 |
| // TODO: Re-enable when clang version meets the fixed version. |
| #if false && defined(__AVX512VBMI__) |
| // When AVX512BMI is available we can completely reverse the vector through |
| // VPERMB __m512i _mm512_permutexvar_epi8( __m512i idx, __m512i a); |
| const auto indices = _mm512_set_epi8(0, 1, 2, 3, 4, 5, 6, 7, // |
| 8, 9, 10, 11, 12, 13, 14, 15, // |
| 16, 17, 18, 19, 20, 21, 22, 23, // |
| 24, 25, 26, 27, 28, 29, 30, 31, // |
| 32, 33, 34, 35, 36, 37, 38, 39, // |
| 40, 41, 42, 43, 44, 45, 46, 47, // |
| 48, 49, 50, 51, 52, 53, 54, 55, // |
| 56, 57, 58, 59, 60, 61, 62, 63); |
| // Then we compute the mask for equal bytes. |
| return _mm512_cmpeq_epi8_mask(_mm512_permutexvar_epi8(indices, max), // |
| _mm512_permutexvar_epi8(indices, value)); |
| #else |
| // We can't byte-reverse '__m512i' in a single instruction with __AVX512BW__. |
| // '_mm512_shuffle_epi8' can only shuffle within each 16-byte lane. |
| // So we only reverse groups of 8 bytes, these groups are necessarily within a |
| // 16-byte lane. |
| // zmm = | 16 bytes | 16 bytes | 16 bytes | 16 bytes | |
| // zmm = | <8> | <8> | <8> | <8> | <8> | <8> | <8> | <8> | |
| const __m512i indices = _mm512_set_epi8(8, 9, 10, 11, 12, 13, 14, 15, // |
| 0, 1, 2, 3, 4, 5, 6, 7, // |
| 8, 9, 10, 11, 12, 13, 14, 15, // |
| 0, 1, 2, 3, 4, 5, 6, 7, // |
| 8, 9, 10, 11, 12, 13, 14, 15, // |
| 0, 1, 2, 3, 4, 5, 6, 7, // |
| 8, 9, 10, 11, 12, 13, 14, 15, // |
| 0, 1, 2, 3, 4, 5, 6, 7); |
| // Then we compute the mask for equal bytes. In this mask the bits of each |
| // byte are already reversed but the byte themselves should be reversed, this |
| // is done by using a bswap instruction. |
| return __builtin_bswap64( |
| _mm512_cmpeq_epi8_mask(_mm512_shuffle_epi8(max, indices), // |
| _mm512_shuffle_epi8(value, indices))); |
| |
| #endif |
| } |
| template <> LIBC_INLINE bool eq<__m512i>(CPtr p1, CPtr p2, size_t offset) { |
| const auto a = load<__m512i>(p1, offset); |
| const auto b = load<__m512i>(p2, offset); |
| return _mm512_cmpneq_epi8_mask(a, b) == 0; |
| } |
| template <> LIBC_INLINE uint32_t neq<__m512i>(CPtr p1, CPtr p2, size_t offset) { |
| const auto a = load<__m512i>(p1, offset); |
| const auto b = load<__m512i>(p2, offset); |
| return _mm512_cmpneq_epi8_mask(a, b) != 0; |
| } |
| LIBC_INLINE __m512i load_and_xor_m512i(CPtr p1, CPtr p2, size_t offset) { |
| const auto a = load<__m512i>(p1, offset); |
| const auto b = load<__m512i>(p2, offset); |
| return _mm512_xor_epi64(a, b); |
| } |
| LIBC_INLINE bool is_zero(__m512i value) { |
| return _mm512_test_epi32_mask(value, value) == 0; |
| } |
| template <> |
| LIBC_INLINE uint32_t branchless_head_tail_neq<__m512i>(CPtr p1, CPtr p2, |
| size_t count) { |
| const __m512i head = load_and_xor_m512i(p1, p2, 0); |
| const __m512i tail = load_and_xor_m512i(p1, p2, count - sizeof(__m512i)); |
| return !is_zero(_mm512_or_epi64(head, tail)); |
| } |
| template <> |
| LIBC_INLINE MemcmpReturnType cmp_neq<__m512i>(CPtr p1, CPtr p2, size_t offset) { |
| const auto a = load<__m512i>(p1, offset); |
| const auto b = load<__m512i>(p2, offset); |
| const auto vmax = bytewise_max(a, b); |
| const auto le = big_endian_cmp_mask(vmax, b); |
| const auto ge = big_endian_cmp_mask(vmax, a); |
| static_assert(cpp::is_same_v<cpp::remove_cv_t<decltype(le)>, uint64_t>); |
| return cmp_neq_uint64_t(ge, le); |
| } |
| #endif // __AVX512BW__ |
| |
| #pragma GCC diagnostic pop |
| |
| } // namespace generic |
| } // namespace LIBC_NAMESPACE_DECL |
| |
| #endif // LIBC_TARGET_ARCH_IS_X86 |
| |
| #endif // LLVM_LIBC_SRC_STRING_MEMORY_UTILS_OP_X86_H |
