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1457016337
Optimize x86-64 strcmp/wcscmp and strncmp/wcsncmp with AVX2. It uses vector comparison as much as possible. Peak performance observed on a SkyLake machine: 9x, 3x, 2.5x and 5.5x for strcmp, strncmp, wcscmp and wcsncmp, respectively. The larger the comparison length, the more benefit using avx2 functions, except on the strcmp, where peak is observed at length == 32 bytes. Select AVX2 strcmp/wcscmp on AVX2 machines where vzeroupper is preferred and AVX unaligned load is fast. NB: It uses TZCNT instead of BSF since TZCNT produces the same result as BSF for non-zero input. TZCNT is faster than BSF and is executed as BSF if machine doesn't support TZCNT. * sysdeps/x86_64/multiarch/Makefile (sysdep_routines): Add strcmp-avx2, strncmp-avx2, wcscmp-avx2, wcscmp-sse2, wcsncmp-avx2 and wcsncmp-sse2. * sysdeps/x86_64/multiarch/ifunc-impl-list.c (__libc_ifunc_impl_list): Add tests for __strcmp_avx2, __strncmp_avx2, __wcscmp_avx2, __wcsncmp_avx2, __wcscmp_sse2 and __wcsncmp_sse2. * sysdeps/x86_64/multiarch/strcmp.c (OPTIMIZE (avx2)): (IFUNC_SELECTOR): Return OPTIMIZE (avx2) on AVX 2 machines if AVX unaligned load is fast and vzeroupper is preferred. * sysdeps/x86_64/multiarch/strncmp.c: Likewise. * sysdeps/x86_64/multiarch/strcmp-avx2.S: New file. * sysdeps/x86_64/multiarch/strncmp-avx2.S: Likewise. * sysdeps/x86_64/multiarch/wcscmp-avx2.S: Likewise. * sysdeps/x86_64/multiarch/wcscmp-sse2.S: Likewise. * sysdeps/x86_64/multiarch/wcscmp.c: Likewise. * sysdeps/x86_64/multiarch/wcsncmp-avx2.S: Likewise. * sysdeps/x86_64/multiarch/wcsncmp-sse2.c: Likewise. * sysdeps/x86_64/multiarch/wcsncmp.c: Likewise. * sysdeps/x86_64/wcscmp.S (__wcscmp): Add alias only if __wcscmp is undefined.
32 lines
1.1 KiB
C
32 lines
1.1 KiB
C
/* Multiple versions of wcsncmp.
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Copyright (C) 2018 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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/* Define multiple versions only for the definition in libc. */
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#if IS_IN (libc)
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# define wcsncmp __redirect_wcsncmp
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# define __wcsncmp __redirect___wcsncmp
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# include <wchar.h>
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# undef wcsncmp
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# undef __wcsncmp
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# define SYMBOL_NAME wcsncmp
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# include "ifunc-avx2.h"
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libc_ifunc_redirected (__redirect_wcsncmp, wcsncmp, IFUNC_SELECTOR ());
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#endif
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