| /////////////////////////////////////////////////////////////////////////////// |
| // |
| /// \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 |
| // The intrinsics use 16-byte-aligned reads from buf, thus they may read |
| // up to 15 bytes before or after the buffer (depending on the alignment |
| // of the buf argument). The values of the extra bytes are ignored. |
| // This unavoidably trips -fsanitize=address so address sanitizier has |
| // to be disabled for this function. |
| #if lzma_has_attribute(__no_sanitize_address__) |
| __attribute__((__no_sanitize_address__)) |
| #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)((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. |
| 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 |
| } |