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| -rw-r--r-- | src/liblzma/check/crc_x86_clmul.h | 428 |
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diff --git a/src/liblzma/check/crc_x86_clmul.h b/src/liblzma/check/crc_x86_clmul.h new file mode 100644 index 0000000..f1254ec --- /dev/null +++ b/src/liblzma/check/crc_x86_clmul.h @@ -0,0 +1,428 @@ +// SPDX-License-Identifier: 0BSD + +/////////////////////////////////////////////////////////////////////////////// +// +/// \file crc_x86_clmul.h +/// \brief CRC32 and CRC64 implementations using CLMUL instructions. +/// +/// The CRC32 and CRC64 implementations use 32/64-bit x86 SSSE3, SSE4.1, and +/// CLMUL instructions. This is compatible with Elbrus 2000 (E2K) too. +/// +/// They were derived from +/// https://www.researchgate.net/publication/263424619_Fast_CRC_computation +/// and the public domain code from https://github.com/rawrunprotected/crc +/// (URLs were checked on 2023-10-14). +/// +/// While this file has both CRC32 and CRC64 implementations, only one +/// should be built at a time to ensure that crc_simd_body() is inlined +/// even with compilers with which lzma_always_inline expands to plain inline. +/// The version to build is selected by defining BUILDING_CRC32_CLMUL or +/// BUILDING_CRC64_CLMUL before including this file. +/// +/// FIXME: Builds for 32-bit x86 use the assembly .S files by default +/// unless configured with --disable-assembler. Even then the lookup table +/// isn't omitted in crc64_table.c since it doesn't know that assembly +/// code has been disabled. +// +// Authors: Ilya Kurdyukov +// Hans Jansen +// Lasse Collin +// Jia Tan +// +/////////////////////////////////////////////////////////////////////////////// + +// This file must not be included more than once. +#ifdef LZMA_CRC_X86_CLMUL_H +# error crc_x86_clmul.h was included twice. +#endif +#define LZMA_CRC_X86_CLMUL_H + +#include <immintrin.h> + +#if defined(_MSC_VER) +# include <intrin.h> +#elif defined(HAVE_CPUID_H) +# include <cpuid.h> +#endif + + +// EDG-based compilers (Intel's classic compiler and compiler for E2K) can +// define __GNUC__ but the attribute must not be used with them. +// The new Clang-based ICX needs the attribute. +// +// NOTE: Build systems check for this too, keep them in sync with this. +#if (defined(__GNUC__) || defined(__clang__)) && !defined(__EDG__) +# define crc_attr_target \ + __attribute__((__target__("ssse3,sse4.1,pclmul"))) +#else +# define crc_attr_target +#endif + + +#define MASK_L(in, mask, r) r = _mm_shuffle_epi8(in, mask) + +#define MASK_H(in, mask, r) \ + r = _mm_shuffle_epi8(in, _mm_xor_si128(mask, vsign)) + +#define MASK_LH(in, mask, low, high) \ + MASK_L(in, mask, low); \ + MASK_H(in, mask, high) + + +crc_attr_target +crc_attr_no_sanitize_address +static lzma_always_inline void +crc_simd_body(const uint8_t *buf, const size_t size, __m128i *v0, __m128i *v1, + const __m128i vfold16, const __m128i initial_crc) +{ + // Create a vector with 8-bit values 0 to 15. This is used to + // construct control masks for _mm_blendv_epi8 and _mm_shuffle_epi8. + const __m128i vramp = _mm_setr_epi32( + 0x03020100, 0x07060504, 0x0b0a0908, 0x0f0e0d0c); + + // This is used to inverse the control mask of _mm_shuffle_epi8 + // so that bytes that wouldn't be picked with the original mask + // will be picked and vice versa. + const __m128i vsign = _mm_set1_epi8(-0x80); + + // Memory addresses A to D and the distances between them: + // + // A B C D + // [skip_start][size][skip_end] + // [ size2 ] + // + // A and D are 16-byte aligned. B and C are 1-byte aligned. + // skip_start and skip_end are 0-15 bytes. size is at least 1 byte. + // + // A = aligned_buf will initially point to this address. + // B = The address pointed by the caller-supplied buf. + // C = buf + size == aligned_buf + size2 + // D = buf + size + skip_end == aligned_buf + size2 + skip_end + const size_t skip_start = (size_t)((uintptr_t)buf & 15); + const size_t skip_end = (size_t)((0U - (uintptr_t)(buf + size)) & 15); + const __m128i *aligned_buf = (const __m128i *)( + (uintptr_t)buf & ~(uintptr_t)15); + + // If size2 <= 16 then the whole input fits into a single 16-byte + // vector. If size2 > 16 then at least two 16-byte vectors must + // be processed. If size2 > 16 && size <= 16 then there is only + // one 16-byte vector's worth of input but it is unaligned in memory. + // + // NOTE: There is no integer overflow here if the arguments + // are valid. If this overflowed, buf + size would too. + const size_t size2 = skip_start + size; + + // Masks to be used with _mm_blendv_epi8 and _mm_shuffle_epi8: + // The first skip_start or skip_end bytes in the vectors will have + // the high bit (0x80) set. _mm_blendv_epi8 and _mm_shuffle_epi8 + // will produce zeros for these positions. (Bitwise-xor of these + // masks with vsign will produce the opposite behavior.) + const __m128i mask_start + = _mm_sub_epi8(vramp, _mm_set1_epi8((char)skip_start)); + const __m128i mask_end + = _mm_sub_epi8(vramp, _mm_set1_epi8((char)skip_end)); + + // Get the first 1-16 bytes into data0. If loading less than 16 + // bytes, the bytes are loaded to the high bits of the vector and + // the least significant positions are filled with zeros. + const __m128i data0 = _mm_blendv_epi8(_mm_load_si128(aligned_buf), + _mm_setzero_si128(), mask_start); + aligned_buf++; + + __m128i v2, v3; + +#ifndef CRC_USE_GENERIC_FOR_SMALL_INPUTS + if (size <= 16) { + // Right-shift initial_crc by 1-16 bytes based on "size" + // and store the result in v1 (high bytes) and v0 (low bytes). + // + // NOTE: The highest 8 bytes of initial_crc are zeros so + // v1 will be filled with zeros if size >= 8. The highest + // 8 bytes of v1 will always become zeros. + // + // [ v1 ][ v0 ] + // [ initial_crc ] size == 1 + // [ initial_crc ] size == 2 + // [ initial_crc ] size == 15 + // [ initial_crc ] size == 16 (all in v0) + const __m128i mask_low = _mm_add_epi8( + vramp, _mm_set1_epi8((char)(size - 16))); + MASK_LH(initial_crc, mask_low, *v0, *v1); + + if (size2 <= 16) { + // There are 1-16 bytes of input and it is all + // in data0. Copy the input bytes to v3. If there + // are fewer than 16 bytes, the low bytes in v3 + // will be filled with zeros. That is, the input + // bytes are stored to the same position as + // (part of) initial_crc is in v0. + MASK_L(data0, mask_end, v3); + } else { + // There are 2-16 bytes of input but not all bytes + // are in data0. + const __m128i data1 = _mm_load_si128(aligned_buf); + + // Collect the 2-16 input bytes from data0 and data1 + // to v2 and v3, and bitwise-xor them with the + // low bits of initial_crc in v0. Note that the + // the second xor is below this else-block as it + // is shared with the other branch. + MASK_H(data0, mask_end, v2); + MASK_L(data1, mask_end, v3); + *v0 = _mm_xor_si128(*v0, v2); + } + + *v0 = _mm_xor_si128(*v0, v3); + *v1 = _mm_alignr_epi8(*v1, *v0, 8); + } else +#endif + { + // There is more than 16 bytes of input. + const __m128i data1 = _mm_load_si128(aligned_buf); + const __m128i *end = (const __m128i*)( + (const char *)aligned_buf - 16 + size2); + aligned_buf++; + + MASK_LH(initial_crc, mask_start, *v0, *v1); + *v0 = _mm_xor_si128(*v0, data0); + *v1 = _mm_xor_si128(*v1, data1); + + while (aligned_buf < end) { + *v1 = _mm_xor_si128(*v1, _mm_clmulepi64_si128( + *v0, vfold16, 0x00)); + *v0 = _mm_xor_si128(*v1, _mm_clmulepi64_si128( + *v0, vfold16, 0x11)); + *v1 = _mm_load_si128(aligned_buf++); + } + + if (aligned_buf != end) { + MASK_H(*v0, mask_end, v2); + MASK_L(*v0, mask_end, *v0); + MASK_L(*v1, mask_end, v3); + *v1 = _mm_or_si128(v2, v3); + } + + *v1 = _mm_xor_si128(*v1, _mm_clmulepi64_si128( + *v0, vfold16, 0x00)); + *v0 = _mm_xor_si128(*v1, _mm_clmulepi64_si128( + *v0, vfold16, 0x11)); + *v1 = _mm_srli_si128(*v0, 8); + } +} + + +///////////////////// +// x86 CLMUL CRC32 // +///////////////////// + +/* +// These functions were used to generate the constants +// at the top of crc32_arch_optimized(). +static uint64_t +calc_lo(uint64_t p, uint64_t a, int n) +{ + uint64_t b = 0; int i; + for (i = 0; i < n; i++) { + b = b >> 1 | (a & 1) << (n - 1); + a = (a >> 1) ^ ((0 - (a & 1)) & p); + } + return b; +} + +// same as ~crc(&a, sizeof(a), ~0) +static uint64_t +calc_hi(uint64_t p, uint64_t a, int n) +{ + int i; + for (i = 0; i < n; i++) + a = (a >> 1) ^ ((0 - (a & 1)) & p); + return a; +} +*/ + +#ifdef BUILDING_CRC32_CLMUL + +crc_attr_target +crc_attr_no_sanitize_address +static uint32_t +crc32_arch_optimized(const uint8_t *buf, size_t size, uint32_t crc) +{ +#ifndef CRC_USE_GENERIC_FOR_SMALL_INPUTS + // The code assumes that there is at least one byte of input. + if (size == 0) + return crc; +#endif + + // uint32_t poly = 0xedb88320; + const int64_t p = 0x1db710640; // p << 1 + const int64_t mu = 0x1f7011641; // calc_lo(p, p, 32) << 1 | 1 + const int64_t k5 = 0x163cd6124; // calc_hi(p, p, 32) << 1 + const int64_t k4 = 0x0ccaa009e; // calc_hi(p, p, 64) << 1 + const int64_t k3 = 0x1751997d0; // calc_hi(p, p, 128) << 1 + + const __m128i vfold4 = _mm_set_epi64x(mu, p); + const __m128i vfold8 = _mm_set_epi64x(0, k5); + const __m128i vfold16 = _mm_set_epi64x(k4, k3); + + __m128i v0, v1, v2; + + crc_simd_body(buf, size, &v0, &v1, vfold16, + _mm_cvtsi32_si128((int32_t)~crc)); + + v1 = _mm_xor_si128( + _mm_clmulepi64_si128(v0, vfold16, 0x10), v1); // xxx0 + v2 = _mm_shuffle_epi32(v1, 0xe7); // 0xx0 + v0 = _mm_slli_epi64(v1, 32); // [0] + v0 = _mm_clmulepi64_si128(v0, vfold8, 0x00); + v0 = _mm_xor_si128(v0, v2); // [1] [2] + v2 = _mm_clmulepi64_si128(v0, vfold4, 0x10); + v2 = _mm_clmulepi64_si128(v2, vfold4, 0x00); + v0 = _mm_xor_si128(v0, v2); // [2] + return ~(uint32_t)_mm_extract_epi32(v0, 2); +} +#endif // BUILDING_CRC32_CLMUL + + +///////////////////// +// x86 CLMUL CRC64 // +///////////////////// + +/* +// These functions were used to generate the constants +// at the top of crc64_arch_optimized(). +static uint64_t +calc_lo(uint64_t poly) +{ + uint64_t a = poly; + uint64_t b = 0; + + for (unsigned i = 0; i < 64; ++i) { + b = (b >> 1) | (a << 63); + a = (a >> 1) ^ (a & 1 ? poly : 0); + } + + return b; +} + +static uint64_t +calc_hi(uint64_t poly, uint64_t a) +{ + for (unsigned i = 0; i < 64; ++i) + a = (a >> 1) ^ (a & 1 ? poly : 0); + + return a; +} +*/ + +#ifdef BUILDING_CRC64_CLMUL + +// MSVC (VS2015 - VS2022) produces bad 32-bit x86 code from the CLMUL CRC +// code when optimizations are enabled (release build). According to the bug +// report, the ebx register is corrupted and the calculated result is wrong. +// Trying to workaround the problem with "__asm mov ebx, ebx" didn't help. +// The following pragma works and performance is still good. x86-64 builds +// and CRC32 CLMUL aren't affected by this problem. The problem does not +// happen in crc_simd_body() either (which is shared with CRC32 CLMUL anyway). +// +// NOTE: Another pragma after crc64_arch_optimized() restores +// the optimizations. If the #if condition here is updated, +// the other one must be updated too. +#if defined(_MSC_VER) && !defined(__INTEL_COMPILER) && !defined(__clang__) \ + && defined(_M_IX86) +# pragma optimize("g", off) +#endif + +crc_attr_target +crc_attr_no_sanitize_address +static uint64_t +crc64_arch_optimized(const uint8_t *buf, size_t size, uint64_t crc) +{ +#ifndef CRC_USE_GENERIC_FOR_SMALL_INPUTS + // The code assumes that there is at least one byte of input. + if (size == 0) + return crc; +#endif + + // const uint64_t poly = 0xc96c5795d7870f42; // CRC polynomial + const uint64_t p = 0x92d8af2baf0e1e85; // (poly << 1) | 1 + const uint64_t mu = 0x9c3e466c172963d5; // (calc_lo(poly) << 1) | 1 + const uint64_t k2 = 0xdabe95afc7875f40; // calc_hi(poly, 1) + const uint64_t k1 = 0xe05dd497ca393ae4; // calc_hi(poly, k2) + + const __m128i vfold8 = _mm_set_epi64x((int64_t)p, (int64_t)mu); + const __m128i vfold16 = _mm_set_epi64x((int64_t)k2, (int64_t)k1); + + __m128i v0, v1, v2; + +#if defined(__i386__) || defined(_M_IX86) + crc_simd_body(buf, size, &v0, &v1, vfold16, + _mm_set_epi64x(0, (int64_t)~crc)); +#else + // GCC and Clang would produce good code with _mm_set_epi64x + // but MSVC needs _mm_cvtsi64_si128 on x86-64. + crc_simd_body(buf, size, &v0, &v1, vfold16, + _mm_cvtsi64_si128((int64_t)~crc)); +#endif + + v1 = _mm_xor_si128(_mm_clmulepi64_si128(v0, vfold16, 0x10), v1); + v0 = _mm_clmulepi64_si128(v1, vfold8, 0x00); + v2 = _mm_clmulepi64_si128(v0, vfold8, 0x10); + v0 = _mm_xor_si128(_mm_xor_si128(v1, _mm_slli_si128(v0, 8)), v2); + +#if defined(__i386__) || defined(_M_IX86) + return ~(((uint64_t)(uint32_t)_mm_extract_epi32(v0, 3) << 32) | + (uint64_t)(uint32_t)_mm_extract_epi32(v0, 2)); +#else + return ~(uint64_t)_mm_extract_epi64(v0, 1); +#endif +} + +#if defined(_MSC_VER) && !defined(__INTEL_COMPILER) && !defined(__clang__) \ + && defined(_M_IX86) +# pragma optimize("", on) +#endif + +#endif // BUILDING_CRC64_CLMUL + + +// Inlining this function duplicates the function body in crc32_resolve() and +// crc64_resolve(), but this is acceptable because this is a tiny function. +static inline bool +is_arch_extension_supported(void) +{ + int success = 1; + uint32_t r[4]; // eax, ebx, ecx, edx + +#if defined(_MSC_VER) + // This needs <intrin.h> with MSVC. ICC has it as a built-in + // on all platforms. + __cpuid(r, 1); +#elif defined(HAVE_CPUID_H) + // Compared to just using __asm__ to run CPUID, this also checks + // that CPUID is supported and saves and restores ebx as that is + // needed with GCC < 5 with position-independent code (PIC). + success = __get_cpuid(1, &r[0], &r[1], &r[2], &r[3]); +#else + // Just a fallback that shouldn't be needed. + __asm__("cpuid\n\t" + : "=a"(r[0]), "=b"(r[1]), "=c"(r[2]), "=d"(r[3]) + : "a"(1), "c"(0)); +#endif + + // Returns true if these are supported: + // CLMUL (bit 1 in ecx) + // SSSE3 (bit 9 in ecx) + // SSE4.1 (bit 19 in ecx) + const uint32_t ecx_mask = (1 << 1) | (1 << 9) | (1 << 19); + return success && (r[2] & ecx_mask) == ecx_mask; + + // Alternative methods that weren't used: + // - ICC's _may_i_use_cpu_feature: the other methods should work too. + // - GCC >= 6 / Clang / ICX __builtin_cpu_supports("pclmul") + // + // CPUID decding is needed with MSVC anyway and older GCC. This keeps + // the feature checks in the build system simpler too. The nice thing + // about __builtin_cpu_supports would be that it generates very short + // code as is it only reads a variable set at startup but a few bytes + // doesn't matter here. +} |