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Diffstat (limited to 'src/liblzma/check/crc64_fast.c')
| -rw-r--r-- | src/liblzma/check/crc64_fast.c | 530 |
1 files changed, 530 insertions, 0 deletions
diff --git a/src/liblzma/check/crc64_fast.c b/src/liblzma/check/crc64_fast.c new file mode 100644 index 0000000..db44633 --- /dev/null +++ b/src/liblzma/check/crc64_fast.c @@ -0,0 +1,530 @@ +/////////////////////////////////////////////////////////////////////////////// +// +/// \file crc64.c +/// \brief CRC64 calculation +/// +/// There are two methods in this file. crc64_generic uses the +/// the slice-by-four algorithm. This is the same idea that is +/// used in crc32_fast.c, but for CRC64 we use only four tables +/// instead of eight to avoid increasing CPU cache usage. +/// +/// crc64_clmul uses 32/64-bit x86 SSSE3, SSE4.1, and CLMUL instructions. +/// It was derived from +/// https://www.intel.com/content/dam/www/public/us/en/documents/white-papers/fast-crc-computation-generic-polynomials-pclmulqdq-paper.pdf +/// and the public domain code from https://github.com/rawrunprotected/crc +/// (URLs were checked on 2022-11-07). +/// +/// FIXME: Builds for 32-bit x86 use crc64_x86.S by default instead +/// of this file and thus CLMUL version isn't available on 32-bit x86 +/// 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: Lasse Collin +// Ilya Kurdyukov +// +// This file has been put into the public domain. +// You can do whatever you want with this file. +// +/////////////////////////////////////////////////////////////////////////////// + +#include "check.h" + +#undef CRC_GENERIC +#undef CRC_CLMUL +#undef CRC_USE_GENERIC_FOR_SMALL_INPUTS + +// If CLMUL cannot be used then only the generic slice-by-four is built. +#if !defined(HAVE_USABLE_CLMUL) +# define CRC_GENERIC 1 + +// If CLMUL is allowed unconditionally in the compiler options then the +// generic version can be omitted. Note that this doesn't work with MSVC +// as I don't know how to detect the features here. +// +// NOTE: Keep this this in sync with crc64_table.c. +#elif (defined(__SSSE3__) && defined(__SSE4_1__) && defined(__PCLMUL__)) \ + || (defined(__e2k__) && __iset__ >= 6) +# define CRC_CLMUL 1 + +// Otherwise build both and detect at runtime which version to use. +#else +# define CRC_GENERIC 1 +# define CRC_CLMUL 1 + +/* + // The generic code is much faster with 1-8-byte inputs and has + // similar performance up to 16 bytes at least in microbenchmarks + // (it depends on input buffer alignment too). If both versions are + // built, this #define will use the generic version for inputs up to + // 16 bytes and CLMUL for bigger inputs. It saves a little in code + // size since the special cases for 0-16-byte inputs will be omitted + // from the CLMUL code. +# define CRC_USE_GENERIC_FOR_SMALL_INPUTS 1 +*/ + +# if defined(_MSC_VER) +# include <intrin.h> +# elif defined(HAVE_CPUID_H) +# include <cpuid.h> +# endif +#endif + + +///////////////////////////////// +// Generic slice-by-four CRC64 // +///////////////////////////////// + +#ifdef CRC_GENERIC + +#include "crc_macros.h" + + +#ifdef WORDS_BIGENDIAN +# define A1(x) ((x) >> 56) +#else +# define A1 A +#endif + + +// See the comments in crc32_fast.c. They aren't duplicated here. +static uint64_t +crc64_generic(const uint8_t *buf, size_t size, uint64_t crc) +{ + crc = ~crc; + +#ifdef WORDS_BIGENDIAN + crc = bswap64(crc); +#endif + + if (size > 4) { + while ((uintptr_t)(buf) & 3) { + crc = lzma_crc64_table[0][*buf++ ^ A1(crc)] ^ S8(crc); + --size; + } + + const uint8_t *const limit = buf + (size & ~(size_t)(3)); + size &= (size_t)(3); + + while (buf < limit) { +#ifdef WORDS_BIGENDIAN + const uint32_t tmp = (uint32_t)(crc >> 32) + ^ aligned_read32ne(buf); +#else + const uint32_t tmp = (uint32_t)crc + ^ aligned_read32ne(buf); +#endif + buf += 4; + + crc = lzma_crc64_table[3][A(tmp)] + ^ lzma_crc64_table[2][B(tmp)] + ^ S32(crc) + ^ lzma_crc64_table[1][C(tmp)] + ^ lzma_crc64_table[0][D(tmp)]; + } + } + + while (size-- != 0) + crc = lzma_crc64_table[0][*buf++ ^ A1(crc)] ^ S8(crc); + +#ifdef WORDS_BIGENDIAN + crc = bswap64(crc); +#endif + + return ~crc; +} +#endif + + +///////////////////// +// x86 CLMUL CRC64 // +///////////////////// + +#ifdef CRC_CLMUL + +#include <immintrin.h> + + +/* +// These functions were used to generate the constants +// at the top of crc64_clmul(). +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; +} +*/ + + +#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) + + +// 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 +// aren't affected by this problem. +// +// NOTE: Another pragma after the function 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 + +// 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__) +__attribute__((__target__("ssse3,sse4.1,pclmul"))) +#endif +static uint64_t +crc64_clmul(const uint8_t *buf, size_t size, uint64_t crc) +{ + // The prototypes of the intrinsics use signed types while most of + // the values are treated as unsigned here. These warnings in this + // function have been checked and found to be harmless so silence them. +#if TUKLIB_GNUC_REQ(4, 6) || defined(__clang__) +# pragma GCC diagnostic push +# pragma GCC diagnostic ignored "-Wsign-conversion" +# pragma GCC diagnostic ignored "-Wconversion" +#endif + +#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 vfold0 = _mm_set_epi64x(p, mu); + const __m128i vfold1 = _mm_set_epi64x(k2, k1); + + // 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)(-(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. + 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(skip_start)); + const __m128i mask_end = _mm_sub_epi8(vramp, _mm_set1_epi8(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; + +#if defined(__i386__) || defined(_M_IX86) + const __m128i initial_crc = _mm_set_epi64x(0, ~crc); +#else + // GCC and Clang would produce good code with _mm_set_epi64x + // but MSVC needs _mm_cvtsi64_si128 on x86-64. + const __m128i initial_crc = _mm_cvtsi64_si128(~crc); +#endif + + __m128i v0, v1, 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(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 + { + const __m128i data1 = _mm_load_si128(aligned_buf); + MASK_LH(initial_crc, mask_start, v0, v1); + v0 = _mm_xor_si128(v0, data0); + v1 = _mm_xor_si128(v1, data1); + +#define FOLD \ + v1 = _mm_xor_si128(v1, _mm_clmulepi64_si128(v0, vfold1, 0x00)); \ + v0 = _mm_xor_si128(v1, _mm_clmulepi64_si128(v0, vfold1, 0x11)); + + while (size2 > 32) { + ++aligned_buf; + size2 -= 16; + FOLD + v1 = _mm_load_si128(aligned_buf); + } + + if (size2 < 32) { + MASK_H(v0, mask_end, v2); + MASK_L(v0, mask_end, v0); + MASK_L(v1, mask_end, v3); + v1 = _mm_or_si128(v2, v3); + } + + FOLD + v1 = _mm_srli_si128(v0, 8); +#undef FOLD + } + + v1 = _mm_xor_si128(_mm_clmulepi64_si128(v0, vfold1, 0x10), v1); + v0 = _mm_clmulepi64_si128(v1, vfold0, 0x00); + v2 = _mm_clmulepi64_si128(v0, vfold0, 0x10); + v0 = _mm_xor_si128(_mm_xor_si128(v2, _mm_slli_si128(v0, 8)), v1); + +#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 TUKLIB_GNUC_REQ(4, 6) || defined(__clang__) +# pragma GCC diagnostic pop +#endif +} +#if defined(_MSC_VER) && !defined(__INTEL_COMPILER) && !defined(__clang__) \ + && defined(_M_IX86) +# pragma optimize("", on) +#endif +#endif + + +//////////////////////// +// Detect CPU support // +//////////////////////// + +#if defined(CRC_GENERIC) && defined(CRC_CLMUL) +static inline bool +is_clmul_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. +} + + +#ifdef HAVE_FUNC_ATTRIBUTE_CONSTRUCTOR +# define CRC64_FUNC_INIT +# define CRC64_SET_FUNC_ATTR __attribute__((__constructor__)) +#else +# define CRC64_FUNC_INIT = &crc64_dispatch +# define CRC64_SET_FUNC_ATTR +static uint64_t crc64_dispatch(const uint8_t *buf, size_t size, uint64_t crc); +#endif + + +// Pointer to the the selected CRC64 method. +static uint64_t (*crc64_func)(const uint8_t *buf, size_t size, uint64_t crc) + CRC64_FUNC_INIT; + + +CRC64_SET_FUNC_ATTR +static void +crc64_set_func(void) +{ + crc64_func = is_clmul_supported() ? &crc64_clmul : &crc64_generic; + return; +} + + +#ifndef HAVE_FUNC_ATTRIBUTE_CONSTRUCTOR +static uint64_t +crc64_dispatch(const uint8_t *buf, size_t size, uint64_t crc) +{ + // When __attribute__((__constructor__)) isn't supported, set the + // function pointer without any locking. If multiple threads run + // the detection code in parallel, they will all end up setting + // the pointer to the same value. This avoids the use of + // mythread_once() on every call to lzma_crc64() but this likely + // isn't strictly standards compliant. Let's change it if it breaks. + crc64_set_func(); + return crc64_func(buf, size, crc); +} +#endif +#endif + + +extern LZMA_API(uint64_t) +lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc) +{ +#if defined(CRC_GENERIC) && defined(CRC_CLMUL) + // If CLMUL is available, it is the best for non-tiny inputs, + // being over twice as fast as the generic slice-by-four version. + // However, for size <= 16 it's different. In the extreme case + // of size == 1 the generic version can be five times faster. + // At size >= 8 the CLMUL starts to become reasonable. It + // varies depending on the alignment of buf too. + // + // The above doesn't include the overhead of mythread_once(). + // At least on x86-64 GNU/Linux, pthread_once() is very fast but + // it still makes lzma_crc64(buf, 1, crc) 50-100 % slower. When + // size reaches 12-16 bytes the overhead becomes negligible. + // + // So using the generic version for size <= 16 may give better + // performance with tiny inputs but if such inputs happen rarely + // it's not so obvious because then the lookup table of the + // generic version may not be in the processor cache. +#ifdef CRC_USE_GENERIC_FOR_SMALL_INPUTS + if (size <= 16) + return crc64_generic(buf, size, crc); +#endif + +/* +#ifndef HAVE_FUNC_ATTRIBUTE_CONSTRUCTOR + // See crc64_dispatch(). This would be the alternative which uses + // locking and doesn't use crc64_dispatch(). Note that on Windows + // this method needs Vista threads. + mythread_once(crc64_set_func); +#endif +*/ + + return crc64_func(buf, size, crc); + +#elif defined(CRC_CLMUL) + // If CLMUL is used unconditionally without runtime CPU detection + // then omitting the generic version and its 8 KiB lookup table + // makes the library smaller. + // + // FIXME: Lookup table isn't currently omitted on 32-bit x86, + // see crc64_table.c. + return crc64_clmul(buf, size, crc); + +#else + return crc64_generic(buf, size, crc); +#endif +} |