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dc485ceb2a
Optimize strlen/strnlen/wcslen/wcsnlen with AVX2 to check 32 bytes with a single vector compare instruction. 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 strlen-sse2, strnlen-sse2, strlen-avx2, strnlen-avx2, wcslen-sse2, wcslen-avx2 and wcsnlen-avx2. * sysdeps/x86_64/multiarch/ifunc-impl-list.c (__libc_ifunc_impl_list): Add tests for __strlen_avx2, __strlen_sse2, __strnlen_avx2, __strnlen_sse2, __wcslen_avx2, __wcslen_sse2 and __wcsnlen_avx2. * sysdeps/x86_64/multiarch/strlen-avx2.S: New file. * sysdeps/x86_64/multiarch/strlen-sse2.S: Likewise. * sysdeps/x86_64/multiarch/strlen.c: Likewise. * sysdeps/x86_64/multiarch/strnlen-avx2.S: Likewise. * sysdeps/x86_64/multiarch/strnlen-sse2.S: Likewise. * sysdeps/x86_64/multiarch/strnlen.c: Likewise. * sysdeps/x86_64/multiarch/wcslen-avx2.S: Likewise. * sysdeps/x86_64/multiarch/wcslen-sse2.S: Likewise. * sysdeps/x86_64/multiarch/wcslen.c: Likewise. * sysdeps/x86_64/multiarch/wcsnlen-avx2.S: Likewise. * sysdeps/x86_64/multiarch/wcsnlen.c (OPTIMIZE (avx2)): New. (IFUNC_SELECTOR): Return OPTIMIZE (avx2) on AVX2 machines where vzeroupper is preferred and AVX unaligned load is fast.
52 lines
1.8 KiB
C
52 lines
1.8 KiB
C
/* Multiple versions of wcsnlen.
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All versions must be listed in ifunc-impl-list.c.
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Copyright (C) 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 __wcsnlen __redirect_wcsnlen
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# include <wchar.h>
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# undef __wcsnlen
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# define SYMBOL_NAME wcsnlen
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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 (sse4_1) 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_CPU_P (cpu_features, SSE4_1))
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return OPTIMIZE (sse4_1);
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return OPTIMIZE (sse2);
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}
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libc_ifunc_redirected (__redirect_wcsnlen, __wcsnlen, IFUNC_SELECTOR ());
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weak_alias (__wcsnlen, wcsnlen);
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#endif
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