liblzma: Moved CLMUL CRC logic to crc_common.h.

crc64_fast.c was updated to use the code from crc_common.h instead.

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