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authorHans Jansen <hansjansen162@outlook.com>2023-10-12 19:23:40 +0200
committerJia Tan <jiat0218@gmail.com>2023-10-13 20:54:05 +0800
commit93e6fb08b22c7c13be2dd1e7274fe78413436254 (patch)
treebe99c3274e633b738e14ac73e07f332ed9131055 /src/liblzma/check/crc_common.h
parentliblzma: Rename crc_macros.h to crc_common.h. (diff)
downloadxz-93e6fb08b22c7c13be2dd1e7274fe78413436254.tar.xz
liblzma: Moved CLMUL CRC logic to crc_common.h.
crc64_fast.c was updated to use the code from crc_common.h instead.
Diffstat (limited to 'src/liblzma/check/crc_common.h')
-rw-r--r--src/liblzma/check/crc_common.h230
1 files changed, 228 insertions, 2 deletions
diff --git a/src/liblzma/check/crc_common.h b/src/liblzma/check/crc_common.h
index f3ee205d..867e53d9 100644
--- a/src/liblzma/check/crc_common.h
+++ b/src/liblzma/check/crc_common.h
@@ -1,9 +1,11 @@
///////////////////////////////////////////////////////////////////////////////
//
/// \file crc_common.h
-/// \brief Some endian-dependent macros for CRC32 and CRC64
+/// \brief Some functions and macros for CRC32 and CRC64
//
-// Author: Lasse Collin
+// Authors: Lasse Collin
+// Ilya Kurdyukov
+// Hans Jansen
//
// This file has been put into the public domain.
// You can do whatever you want with this file.
@@ -28,3 +30,227 @@
# define S8(x) ((x) >> 8)
# define S32(x) ((x) >> 32)
#endif
+
+
+#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 crc32_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
+
+////////////////////////
+// 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.
+}
+#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)
+
+#ifdef CRC_CLMUL
+
+#include <immintrin.h>
+
+
+#if (defined(__GNUC__) || defined(__clang__)) && !defined(__EDG__)
+__attribute__((__target__("ssse3,sse4.1,pclmul")))
+#endif
+#if lzma_has_attribute(__no_sanitize_address__)
+__attribute__((__no_sanitize_address__))
+#endif
+static inline void
+crc_simd_body(const uint8_t *buf, size_t size, __m128i *v0, __m128i *v1,
+ __m128i vfold16, __m128i crc2vec)
+{
+#if TUKLIB_GNUC_REQ(4, 6) || defined(__clang__)
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wsign-conversion"
+#endif
+ // 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
+ uintptr_t skip_start = (uintptr_t)buf & 15;
+ uintptr_t skip_end = -(uintptr_t)(buf + size) & 15;
+
+ // 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.
+ __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.
+ __m128i vsign = _mm_set1_epi8(-0x80);
+
+ // Masks to be used with _mm_blendv_epi8 and _mm_shuffle_epi8
+ // The first skip_start or skip_end bytes in the vectors will hav
+ // the high bit (0x80) set. _mm_blendv_epi8 and _mm_shuffle_epi
+ // will produce zeros for these positions. (Bitwise-xor of thes
+ // masks with vsign will produce the opposite behavior.)
+ __m128i mask_start = _mm_sub_epi8(vramp, _mm_set1_epi8(skip_start));
+ __m128i mask_end = _mm_sub_epi8(vramp, _mm_set1_epi8(skip_end));
+
+ // 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.
+ uintptr_t size2 = skip_start + size;
+ const __m128i *aligned_buf = (const __m128i*)((uintptr_t)buf & -16);
+ __m128i v2, v3, vcrc, data0;
+
+ vcrc = crc2vec;
+
+ // 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.
+ data0 = _mm_load_si128(aligned_buf);
+ data0 = _mm_blendv_epi8(data0, _mm_setzero_si128(), mask_start);
+ aligned_buf++;
+ 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.
+ __m128i mask_low = _mm_add_epi8(
+ vramp, _mm_set1_epi8(size - 16));
+ MASK_LH(vcrc, mask_low, *v0, *v1)
+ MASK_L(data0, mask_end, v3)
+ *v0 = _mm_xor_si128(*v0, v3);
+ *v1 = _mm_alignr_epi8(*v1, *v0, 8);
+ } else {
+ __m128i data1 = _mm_load_si128(aligned_buf);
+ if (size <= 16) {
+ // 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.
+ __m128i mask_low = _mm_add_epi8(
+ vramp, _mm_set1_epi8(size - 16));
+ MASK_LH(vcrc, mask_low, *v0, *v1);
+ 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 {
+ const __m128i *end = (const __m128i*)(
+ (char*)aligned_buf++ - 16 + size2);
+ MASK_LH(vcrc, 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);
+ }
+ }
+}
+#endif