libdeflate/lib/x86/matchfinder_impl.h
Eric Biggers 29dfcfd866 lib/matchfinder: support dynamic dispatch for init and rebase
Currently the optimized implementations of matchfinder_init() and
matchfinder_rebase() are chosen via static dispatch.  That means that
the AVX-2 implementations usually aren't used.

Fix this by using dynamic dispatch, like what libdeflate does for the
Adler-32 and CRC-32 checksums and for DEFLATE decompression.

Based on work by Andrew Steinborn <git@steinborn.me>
(https://github.com/ebiggers/libdeflate/pull/77).  He wrote:

"The main impact is on x86: the AVX2 matchfinder can now be properly
dynamically dispatched at runtime and if -mavx2 is included in CFLAGS
(or -march set to any platform with AVX2 support). On my Ryzen 9 3900X,
I got an approximately 1% boost in deflate time (measured with a
uncompressed tarball of the Silesia corpus) using just the changes in
this PR and the regular CFLAGS, and a 2.7% boost when specifying -mavx2
as CFLAGS. (I also tested with an Intel Xeon Skylake c5.large EC2
instance, and did not see any performance regression)."
2020-10-28 19:20:53 -07:00

177 lines
5.0 KiB
C

/*
* x86/matchfinder_impl.h - x86 implementations of matchfinder functions
*
* Copyright 2016 Eric Biggers
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#include "cpu_features.h"
#undef DISPATCH_AVX2
#if !defined(matchfinder_init_default) && \
(defined(__AVX2__) || (X86_CPU_FEATURES_ENABLED && \
COMPILER_SUPPORTS_AVX2_TARGET_INTRINSICS))
# ifdef __AVX2__
# define ATTRIBUTES
# define matchfinder_init_default matchfinder_init_avx2
# define matchfinder_rebase_default matchfinder_rebase_avx2
# else
# define ATTRIBUTES __attribute__((target("avx2")))
# define DISPATCH 1
# define DISPATCH_AVX2 1
# endif
# include <immintrin.h>
static void ATTRIBUTES
matchfinder_init_avx2(mf_pos_t *data, size_t size)
{
__m256i *p = (__m256i *)data;
__m256i v = _mm256_set1_epi16(MATCHFINDER_INITVAL);
STATIC_ASSERT(MATCHFINDER_MEM_ALIGNMENT % sizeof(*p) == 0);
STATIC_ASSERT(MATCHFINDER_SIZE_ALIGNMENT % (4 * sizeof(*p)) == 0);
STATIC_ASSERT(sizeof(mf_pos_t) == 2);
do {
p[0] = v;
p[1] = v;
p[2] = v;
p[3] = v;
p += 4;
size -= 4 * sizeof(*p);
} while (size != 0);
}
static void ATTRIBUTES
matchfinder_rebase_avx2(mf_pos_t *data, size_t size)
{
__m256i *p = (__m256i *)data;
__m256i v = _mm256_set1_epi16((u16)-MATCHFINDER_WINDOW_SIZE);
STATIC_ASSERT(MATCHFINDER_MEM_ALIGNMENT % sizeof(*p) == 0);
STATIC_ASSERT(MATCHFINDER_SIZE_ALIGNMENT % (4 * sizeof(*p)) == 0);
STATIC_ASSERT(sizeof(mf_pos_t) == 2);
do {
/* PADDSW: Add Packed Signed Integers With Signed Saturation */
p[0] = _mm256_adds_epi16(p[0], v);
p[1] = _mm256_adds_epi16(p[1], v);
p[2] = _mm256_adds_epi16(p[2], v);
p[3] = _mm256_adds_epi16(p[3], v);
p += 4;
size -= 4 * sizeof(*p);
} while (size != 0);
}
#undef ATTRIBUTES
#endif /* AVX2 implementation */
#undef DISPATCH_SSE2
#if !defined(matchfinder_init_default) && \
(defined(__SSE2__) || (X86_CPU_FEATURES_ENABLED && \
COMPILER_SUPPORTS_SSE2_TARGET_INTRINSICS))
# ifdef __SSE2__
# define ATTRIBUTES
# define matchfinder_init_default matchfinder_init_sse2
# define matchfinder_rebase_default matchfinder_rebase_sse2
# else
# define ATTRIBUTES __attribute__((target("sse2")))
# define DISPATCH 1
# define DISPATCH_SSE2 1
# endif
# include <emmintrin.h>
static void ATTRIBUTES
matchfinder_init_sse2(mf_pos_t *data, size_t size)
{
__m128i *p = (__m128i *)data;
__m128i v = _mm_set1_epi16(MATCHFINDER_INITVAL);
STATIC_ASSERT(MATCHFINDER_MEM_ALIGNMENT % sizeof(*p) == 0);
STATIC_ASSERT(MATCHFINDER_SIZE_ALIGNMENT % (4 * sizeof(*p)) == 0);
STATIC_ASSERT(sizeof(mf_pos_t) == 2);
do {
p[0] = v;
p[1] = v;
p[2] = v;
p[3] = v;
p += 4;
size -= 4 * sizeof(*p);
} while (size != 0);
}
static void ATTRIBUTES
matchfinder_rebase_sse2(mf_pos_t *data, size_t size)
{
__m128i *p = (__m128i *)data;
__m128i v = _mm_set1_epi16((u16)-MATCHFINDER_WINDOW_SIZE);
STATIC_ASSERT(MATCHFINDER_MEM_ALIGNMENT % sizeof(*p) == 0);
STATIC_ASSERT(MATCHFINDER_SIZE_ALIGNMENT % (4 * sizeof(*p)) == 0);
STATIC_ASSERT(sizeof(mf_pos_t) == 2);
do {
/* PADDSW: Add Packed Signed Integers With Signed Saturation */
p[0] = _mm_adds_epi16(p[0], v);
p[1] = _mm_adds_epi16(p[1], v);
p[2] = _mm_adds_epi16(p[2], v);
p[3] = _mm_adds_epi16(p[3], v);
p += 4;
size -= 4 * sizeof(*p);
} while (size != 0);
}
#undef ATTRIBUTES
#endif /* SSE2 implementation */
#ifdef DISPATCH
static inline mf_init_func_t
arch_select_matchfinder_init_func(void)
{
u32 features = get_cpu_features();
#ifdef DISPATCH_AVX2
if (features & X86_CPU_FEATURE_AVX2)
return matchfinder_init_avx2;
#endif
#ifdef DISPATCH_SSE2
if (features & X86_CPU_FEATURE_SSE2)
return matchfinder_init_sse2;
#endif
return NULL;
}
static inline mf_rebase_func_t
arch_select_matchfinder_rebase_func(void)
{
u32 features = get_cpu_features();
#ifdef DISPATCH_AVX2
if (features & X86_CPU_FEATURE_AVX2)
return matchfinder_rebase_avx2;
#endif
#ifdef DISPATCH_SSE2
if (features & X86_CPU_FEATURE_SSE2)
return matchfinder_rebase_sse2;
#endif
return NULL;
}
#endif /* DISPATCH */