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1//===-- Implementations for platform with mandatory aligned memory access -===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8// For some platforms, unaligned loads and stores are either illegal or very9// slow. The implementations in this file make sure all loads and stores are10// always aligned.11//===----------------------------------------------------------------------===//12 13#ifndef LLVM_LIBC_SRC_STRING_MEMORY_UTILS_GENERIC_ALIGNED_ACCESS_H14#define LLVM_LIBC_SRC_STRING_MEMORY_UTILS_GENERIC_ALIGNED_ACCESS_H15 16#include "src/__support/macros/attributes.h" // LIBC_INLINE17#include "src/string/memory_utils/generic/byte_per_byte.h"18#include "src/string/memory_utils/op_generic.h" // generic::splat19#include "src/string/memory_utils/utils.h" // Ptr, CPtr20 21#include <stddef.h> // size_t22 23namespace LIBC_NAMESPACE_DECL {24 25[[maybe_unused]] LIBC_INLINE uint32_t load32_aligned(CPtr ptr, size_t offset,26 size_t alignment) {27 if (alignment == 0)28 return load32_aligned<uint32_t>(ptr, offset);29 else if (alignment == 2)30 return load32_aligned<uint16_t, uint16_t>(ptr, offset);31 else // 1, 332 return load32_aligned<uint8_t, uint16_t, uint8_t>(ptr, offset);33}34 35[[maybe_unused]] LIBC_INLINE uint64_t load64_aligned(CPtr ptr, size_t offset,36 size_t alignment) {37 if (alignment == 0)38 return load64_aligned<uint64_t>(ptr, offset);39 else if (alignment == 4)40 return load64_aligned<uint32_t, uint32_t>(ptr, offset);41 else if (alignment == 6)42 return load64_aligned<uint16_t, uint32_t, uint16_t>(ptr, offset);43 else if (alignment == 2)44 return load64_aligned<uint16_t, uint16_t, uint16_t, uint16_t>(ptr, offset);45 else // 1, 3, 5, 746 return load64_aligned<uint8_t, uint16_t, uint16_t, uint16_t, uint8_t>(47 ptr, offset);48}49 50///////////////////////////////////////////////////////////////////////////////51// memcpy52///////////////////////////////////////////////////////////////////////////////53 54[[maybe_unused]] LIBC_INLINE void55inline_memcpy_aligned_access_32bit(Ptr __restrict dst, CPtr __restrict src,56 size_t count) {57 constexpr size_t kAlign = sizeof(uint32_t);58 if (count <= 2 * kAlign)59 return inline_memcpy_byte_per_byte(dst, src, count);60 size_t bytes_to_dst_align = distance_to_align_up<kAlign>(dst);61 inline_memcpy_byte_per_byte(dst, src, bytes_to_dst_align);62 size_t offset = bytes_to_dst_align;63 size_t src_alignment = distance_to_align_down<kAlign>(src + offset);64 for (; offset < count - kAlign; offset += kAlign) {65 uint32_t value = load32_aligned(src, offset, src_alignment);66 store32_aligned<uint32_t>(value, dst, offset);67 }68 // remainder69 inline_memcpy_byte_per_byte(dst, src, count, offset);70}71 72[[maybe_unused]] LIBC_INLINE void73inline_memcpy_aligned_access_64bit(Ptr __restrict dst, CPtr __restrict src,74 size_t count) {75 constexpr size_t kAlign = sizeof(uint64_t);76 if (count <= 2 * kAlign)77 return inline_memcpy_byte_per_byte(dst, src, count);78 size_t bytes_to_dst_align = distance_to_align_up<kAlign>(dst);79 inline_memcpy_byte_per_byte(dst, src, bytes_to_dst_align);80 size_t offset = bytes_to_dst_align;81 size_t src_alignment = distance_to_align_down<kAlign>(src + offset);82 for (; offset < count - kAlign; offset += kAlign) {83 uint64_t value = load64_aligned(src, offset, src_alignment);84 store64_aligned<uint64_t>(value, dst, offset);85 }86 // remainder87 inline_memcpy_byte_per_byte(dst, src, count, offset);88}89 90///////////////////////////////////////////////////////////////////////////////91// memset92///////////////////////////////////////////////////////////////////////////////93 94[[maybe_unused]] LIBC_INLINE static void95inline_memset_aligned_access_32bit(Ptr dst, uint8_t value, size_t count) {96 constexpr size_t kAlign = sizeof(uint32_t);97 if (count <= 2 * kAlign)98 return inline_memset_byte_per_byte(dst, value, count);99 size_t bytes_to_dst_align = distance_to_align_up<kAlign>(dst);100 inline_memset_byte_per_byte(dst, value, bytes_to_dst_align);101 size_t offset = bytes_to_dst_align;102 for (; offset < count - kAlign; offset += kAlign)103 store32_aligned<uint32_t>(generic::splat<uint32_t>(value), dst, offset);104 inline_memset_byte_per_byte(dst, value, count, offset);105}106 107[[maybe_unused]] LIBC_INLINE static void108inline_memset_aligned_access_64bit(Ptr dst, uint8_t value, size_t count) {109 constexpr size_t kAlign = sizeof(uint64_t);110 if (count <= 2 * kAlign)111 return inline_memset_byte_per_byte(dst, value, count);112 size_t bytes_to_dst_align = distance_to_align_up<kAlign>(dst);113 inline_memset_byte_per_byte(dst, value, bytes_to_dst_align);114 size_t offset = bytes_to_dst_align;115 for (; offset < count - kAlign; offset += kAlign)116 store64_aligned<uint64_t>(generic::splat<uint64_t>(value), dst, offset);117 inline_memset_byte_per_byte(dst, value, count, offset);118}119 120///////////////////////////////////////////////////////////////////////////////121// bcmp122///////////////////////////////////////////////////////////////////////////////123 124[[maybe_unused]] LIBC_INLINE BcmpReturnType125inline_bcmp_aligned_access_32bit(CPtr p1, CPtr p2, size_t count) {126 constexpr size_t kAlign = sizeof(uint32_t);127 if (count <= 2 * kAlign)128 return inline_bcmp_byte_per_byte(p1, p2, count);129 size_t bytes_to_p1_align = distance_to_align_up<kAlign>(p1);130 if (auto value = inline_bcmp_byte_per_byte(p1, p2, bytes_to_p1_align))131 return value;132 size_t offset = bytes_to_p1_align;133 size_t p2_alignment = distance_to_align_down<kAlign>(p2 + offset);134 for (; offset < count - kAlign; offset += kAlign) {135 uint32_t a = load32_aligned<uint32_t>(p1, offset);136 uint32_t b = load32_aligned(p2, offset, p2_alignment);137 if (a != b)138 return BcmpReturnType::nonzero();139 }140 return inline_bcmp_byte_per_byte(p1, p2, count, offset);141}142 143[[maybe_unused]] LIBC_INLINE BcmpReturnType144inline_bcmp_aligned_access_64bit(CPtr p1, CPtr p2, size_t count) {145 constexpr size_t kAlign = sizeof(uint64_t);146 if (count <= 2 * kAlign)147 return inline_bcmp_byte_per_byte(p1, p2, count);148 size_t bytes_to_p1_align = distance_to_align_up<kAlign>(p1);149 if (auto value = inline_bcmp_byte_per_byte(p1, p2, bytes_to_p1_align))150 return value;151 size_t offset = bytes_to_p1_align;152 size_t p2_alignment = distance_to_align_down<kAlign>(p2 + offset);153 for (; offset < count - kAlign; offset += kAlign) {154 uint64_t a = load64_aligned<uint64_t>(p1, offset);155 uint64_t b = load64_aligned(p2, offset, p2_alignment);156 if (a != b)157 return BcmpReturnType::nonzero();158 }159 return inline_bcmp_byte_per_byte(p1, p2, count, offset);160}161 162///////////////////////////////////////////////////////////////////////////////163// memcmp164///////////////////////////////////////////////////////////////////////////////165 166[[maybe_unused]] LIBC_INLINE MemcmpReturnType167inline_memcmp_aligned_access_32bit(CPtr p1, CPtr p2, size_t count) {168 constexpr size_t kAlign = sizeof(uint32_t);169 if (count <= 2 * kAlign)170 return inline_memcmp_byte_per_byte(p1, p2, count);171 size_t bytes_to_p1_align = distance_to_align_up<kAlign>(p1);172 if (auto value = inline_memcmp_byte_per_byte(p1, p2, bytes_to_p1_align))173 return value;174 size_t offset = bytes_to_p1_align;175 size_t p2_alignment = distance_to_align_down<kAlign>(p2 + offset);176 for (; offset < count - kAlign; offset += kAlign) {177 uint32_t a = load32_aligned<uint32_t>(p1, offset);178 uint32_t b = load32_aligned(p2, offset, p2_alignment);179 if (a != b)180 return cmp_uint32_t(Endian::to_big_endian(a), Endian::to_big_endian(b));181 }182 return inline_memcmp_byte_per_byte(p1, p2, count, offset);183}184 185[[maybe_unused]] LIBC_INLINE MemcmpReturnType186inline_memcmp_aligned_access_64bit(CPtr p1, CPtr p2, size_t count) {187 constexpr size_t kAlign = sizeof(uint64_t);188 if (count <= 2 * kAlign)189 return inline_memcmp_byte_per_byte(p1, p2, count);190 size_t bytes_to_p1_align = distance_to_align_up<kAlign>(p1);191 if (auto value = inline_memcmp_byte_per_byte(p1, p2, bytes_to_p1_align))192 return value;193 size_t offset = bytes_to_p1_align;194 size_t p2_alignment = distance_to_align_down<kAlign>(p2 + offset);195 for (; offset < count - kAlign; offset += kAlign) {196 uint64_t a = load64_aligned<uint64_t>(p1, offset);197 uint64_t b = load64_aligned(p2, offset, p2_alignment);198 if (a != b)199 return cmp_neq_uint64_t(Endian::to_big_endian(a),200 Endian::to_big_endian(b));201 }202 return inline_memcmp_byte_per_byte(p1, p2, count, offset);203}204 205} // namespace LIBC_NAMESPACE_DECL206 207#endif // LLVM_LIBC_SRC_STRING_MEMORY_UTILS_GENERIC_ALIGNED_ACCESS_H208