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| 1 | //===-- Memset implementation for x86_64 ------------------------*- C++ -*-===// |
|---|---|
| 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-exception |
| 6 | // |
| 7 | //===----------------------------------------------------------------------===// |
| 8 | #ifndef LLVM_LIBC_SRC_STRING_MEMORY_UTILS_X86_64_INLINE_MEMSET_H |
| 9 | #define LLVM_LIBC_SRC_STRING_MEMORY_UTILS_X86_64_INLINE_MEMSET_H |
| 10 | |
| 11 | #include "src/__support/macros/attributes.h" // LIBC_INLINE, LIBC_INLINE_VAR |
| 12 | #include "src/__support/macros/config.h" // LIBC_NAMESPACE_DECL |
| 13 | #include "src/string/memory_utils/op_generic.h" |
| 14 | #include "src/string/memory_utils/op_x86.h" |
| 15 | #include "src/string/memory_utils/utils.h" // Ptr, CPtr |
| 16 | |
| 17 | #include <stddef.h> // size_t |
| 18 | |
| 19 | namespace LIBC_NAMESPACE_DECL { |
| 20 | namespace x86 { |
| 21 | // Size of one cache line for software prefetching |
| 22 | LIBC_INLINE_VAR constexpr size_t K_ONE_CACHELINE_SIZE = 64; |
| 23 | LIBC_INLINE_VAR constexpr size_t K_TWO_CACHELINES_SIZE = |
| 24 | K_ONE_CACHELINE_SIZE * 2; |
| 25 | LIBC_INLINE_VAR constexpr size_t K_FIVE_CACHELINES_SIZE = |
| 26 | K_ONE_CACHELINE_SIZE * 5; |
| 27 | |
| 28 | LIBC_INLINE_VAR constexpr bool K_USE_SOFTWARE_PREFETCHING_MEMSET = |
| 29 | LLVM_LIBC_IS_DEFINED(LIBC_COPT_MEMSET_X86_USE_SOFTWARE_PREFETCHING); |
| 30 | |
| 31 | } // namespace x86 |
| 32 | |
| 33 | #if defined(__AVX512F__) |
| 34 | using uint128_t = generic_v128; |
| 35 | using uint256_t = generic_v256; |
| 36 | using uint512_t = generic_v512; |
| 37 | #elif defined(__AVX__) |
| 38 | using uint128_t = generic_v128; |
| 39 | using uint256_t = generic_v256; |
| 40 | using uint512_t = cpp::array<generic_v256, 2>; |
| 41 | #elif defined(__SSE2__) |
| 42 | using uint128_t = generic_v128; |
| 43 | using uint256_t = cpp::array<generic_v128, 2>; |
| 44 | using uint512_t = cpp::array<generic_v128, 4>; |
| 45 | #else |
| 46 | using uint128_t = cpp::array<uint64_t, 2>; |
| 47 | using uint256_t = cpp::array<uint64_t, 4>; |
| 48 | using uint512_t = cpp::array<uint64_t, 8>; |
| 49 | #endif |
| 50 | |
| 51 | [[maybe_unused]] LIBC_INLINE static void |
| 52 | inline_memset_x86_gt64_sw_prefetching(Ptr dst, uint8_t value, size_t count) { |
| 53 | constexpr size_t PREFETCH_DISTANCE = x86::K_FIVE_CACHELINES_SIZE; |
| 54 | constexpr size_t PREFETCH_DEGREE = x86::K_TWO_CACHELINES_SIZE; |
| 55 | constexpr size_t SIZE = sizeof(uint256_t); |
| 56 | // Prefetch one cache line |
| 57 | prefetch_for_write(dst + x86::K_ONE_CACHELINE_SIZE); |
| 58 | if (count <= 128) |
| 59 | return generic::Memset<uint512_t>::head_tail(dst, value, count); |
| 60 | // Prefetch the second cache line |
| 61 | prefetch_for_write(dst + x86::K_TWO_CACHELINES_SIZE); |
| 62 | // Aligned loop |
| 63 | generic::Memset<uint256_t>::block(dst, value); |
| 64 | align_to_next_boundary<32>(dst, count); |
| 65 | if (count <= 192) { |
| 66 | return generic::Memset<uint256_t>::loop_and_tail(dst, value, count); |
| 67 | } else { |
| 68 | generic::MemsetSequence<uint512_t, uint256_t>::block(dst, value); |
| 69 | size_t offset = 96; |
| 70 | while (offset + PREFETCH_DEGREE + SIZE <= count) { |
| 71 | prefetch_for_write(dst + offset + PREFETCH_DISTANCE); |
| 72 | prefetch_for_write(dst + offset + PREFETCH_DISTANCE + |
| 73 | x86::K_ONE_CACHELINE_SIZE); |
| 74 | for (size_t i = 0; i < PREFETCH_DEGREE; i += SIZE, offset += SIZE) |
| 75 | generic::Memset<uint256_t>::block(dst + offset, value); |
| 76 | } |
| 77 | generic::Memset<uint256_t>::loop_and_tail_offset(dst, value, count, offset); |
| 78 | } |
| 79 | } |
| 80 | |
| 81 | [[maybe_unused]] LIBC_INLINE static void |
| 82 | inline_memset_x86(Ptr dst, uint8_t value, size_t count) { |
| 83 | if (count == 0) |
| 84 | return; |
| 85 | if (count == 1) |
| 86 | return generic::Memset<uint8_t>::block(dst, value); |
| 87 | if (count == 2) |
| 88 | return generic::Memset<uint16_t>::block(dst, value); |
| 89 | if (count == 3) |
| 90 | return generic::MemsetSequence<uint16_t, uint8_t>::block(dst, value); |
| 91 | if (count <= 8) |
| 92 | return generic::Memset<uint32_t>::head_tail(dst, value, count); |
| 93 | if (count <= 16) |
| 94 | return generic::Memset<uint64_t>::head_tail(dst, value, count); |
| 95 | if (count <= 32) |
| 96 | return generic::Memset<uint128_t>::head_tail(dst, value, count); |
| 97 | if (count <= 64) |
| 98 | return generic::Memset<uint256_t>::head_tail(dst, value, count); |
| 99 | if constexpr (x86::K_USE_SOFTWARE_PREFETCHING_MEMSET) |
| 100 | return inline_memset_x86_gt64_sw_prefetching(dst, value, count); |
| 101 | if (count <= 128) |
| 102 | return generic::Memset<uint512_t>::head_tail(dst, value, count); |
| 103 | // Aligned loop |
| 104 | generic::Memset<uint256_t>::block(dst, value); |
| 105 | align_to_next_boundary<32>(dst, count); |
| 106 | return generic::Memset<uint256_t>::loop_and_tail(dst, value, count); |
| 107 | } |
| 108 | } // namespace LIBC_NAMESPACE_DECL |
| 109 | |
| 110 | #endif // LLVM_LIBC_SRC_STRING_MEMORY_UTILS_X86_64_INLINE_MEMSET_H |
| 111 |
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