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8fe57365bf
Optimize strchr/strchrnul/wcschr with AVX2 to search 32 bytes with vector instructions. It is as fast as SSE2 versions for size <= 16 bytes and up to 1X faster for or size > 16 bytes on Haswell. Select AVX2 version 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 strchr-sse2, strchrnul-sse2, strchr-avx2, strchrnul-avx2, wcschr-sse2 and wcschr-avx2. * sysdeps/x86_64/multiarch/ifunc-impl-list.c (__libc_ifunc_impl_list): Add tests for __strchr_avx2, __strchrnul_avx2, __strchrnul_sse2, __wcschr_avx2 and __wcschr_sse2. * sysdeps/x86_64/multiarch/strchr-avx2.S: New file. * sysdeps/x86_64/multiarch/strchr-sse2.S: Likewise. * sysdeps/x86_64/multiarch/strchr.c: Likewise. * sysdeps/x86_64/multiarch/strchrnul-avx2.S: Likewise. * sysdeps/x86_64/multiarch/strchrnul-sse2.S: Likewise. * sysdeps/x86_64/multiarch/strchrnul.c: Likewise. * sysdeps/x86_64/multiarch/wcschr-avx2.S: Likewise. * sysdeps/x86_64/multiarch/wcschr-sse2.S: Likewise. * sysdeps/x86_64/multiarch/wcschr.c: Likewise. * sysdeps/x86_64/multiarch/strchr.S: Removed.
56 lines
1.9 KiB
C
56 lines
1.9 KiB
C
/* Multiple versions of strchr.
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All versions must be listed in ifunc-impl-list.c.
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Copyright (C) 2009-2017 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 strchr __redirect_strchr
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# include <string.h>
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# undef strchr
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# define SYMBOL_NAME strchr
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# include <init-arch.h>
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extern __typeof (REDIRECT_NAME) OPTIMIZE (sse2) attribute_hidden;
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extern __typeof (REDIRECT_NAME) OPTIMIZE (sse2_no_bsf) attribute_hidden;
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extern __typeof (REDIRECT_NAME) OPTIMIZE (avx2) attribute_hidden;
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static inline void *
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IFUNC_SELECTOR (void)
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{
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const struct cpu_features* cpu_features = __get_cpu_features ();
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if (!CPU_FEATURES_ARCH_P (cpu_features, Prefer_No_VZEROUPPER)
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&& CPU_FEATURES_ARCH_P (cpu_features, AVX2_Usable)
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&& CPU_FEATURES_ARCH_P (cpu_features, AVX_Fast_Unaligned_Load))
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return OPTIMIZE (avx2);
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if (CPU_FEATURES_ARCH_P (cpu_features, Slow_BSF))
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return OPTIMIZE (sse2_no_bsf);
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return OPTIMIZE (sse2);
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}
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libc_ifunc_redirected (__redirect_strchr, strchr, IFUNC_SELECTOR ());
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weak_alias (strchr, index)
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# ifdef SHARED
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__hidden_ver1 (strchr, __GI_strchr, __redirect_strchr)
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__attribute__((visibility ("hidden")));
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# endif
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#endif
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