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3d9f171bfb
memset with zero as the value to set is by far the majority value (99%+ for Python3 and GCC). bzero can be slightly more optimized for this case by using a zero-idiom xor for broadcasting the set value to a register (vector or GPR). Co-developed-by: Noah Goldstein <goldstein.w.n@gmail.com>
107 lines
3.4 KiB
C
107 lines
3.4 KiB
C
/* Multiple versions of bzero.
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All versions must be listed in ifunc-impl-list.c.
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Copyright (C) 2022 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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<https://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 __bzero __redirect___bzero
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# include <string.h>
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# undef __bzero
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# define SYMBOL_NAME __bzero
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# include <init-arch.h>
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extern __typeof (REDIRECT_NAME) OPTIMIZE1 (sse2_unaligned)
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attribute_hidden;
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extern __typeof (REDIRECT_NAME) OPTIMIZE1 (sse2_unaligned_erms)
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attribute_hidden;
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extern __typeof (REDIRECT_NAME) OPTIMIZE1 (avx2_unaligned) attribute_hidden;
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extern __typeof (REDIRECT_NAME) OPTIMIZE1 (avx2_unaligned_erms)
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attribute_hidden;
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extern __typeof (REDIRECT_NAME) OPTIMIZE1 (avx2_unaligned_rtm)
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attribute_hidden;
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extern __typeof (REDIRECT_NAME) OPTIMIZE1 (avx2_unaligned_erms_rtm)
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attribute_hidden;
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extern __typeof (REDIRECT_NAME) OPTIMIZE1 (evex_unaligned)
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attribute_hidden;
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extern __typeof (REDIRECT_NAME) OPTIMIZE1 (evex_unaligned_erms)
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attribute_hidden;
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extern __typeof (REDIRECT_NAME) OPTIMIZE1 (avx512_unaligned)
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attribute_hidden;
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extern __typeof (REDIRECT_NAME) OPTIMIZE1 (avx512_unaligned_erms)
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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_FEATURE_USABLE_P (cpu_features, AVX512F)
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&& !CPU_FEATURES_ARCH_P (cpu_features, Prefer_No_AVX512))
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{
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if (CPU_FEATURE_USABLE_P (cpu_features, AVX512VL)
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&& CPU_FEATURE_USABLE_P (cpu_features, AVX512BW)
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&& CPU_FEATURE_USABLE_P (cpu_features, BMI2))
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{
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if (CPU_FEATURE_USABLE_P (cpu_features, ERMS))
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return OPTIMIZE1 (avx512_unaligned_erms);
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return OPTIMIZE1 (avx512_unaligned);
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}
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}
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if (CPU_FEATURE_USABLE_P (cpu_features, AVX2))
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{
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if (CPU_FEATURE_USABLE_P (cpu_features, AVX512VL)
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&& CPU_FEATURE_USABLE_P (cpu_features, AVX512BW)
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&& CPU_FEATURE_USABLE_P (cpu_features, BMI2))
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{
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if (CPU_FEATURE_USABLE_P (cpu_features, ERMS))
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return OPTIMIZE1 (evex_unaligned_erms);
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return OPTIMIZE1 (evex_unaligned);
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}
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if (CPU_FEATURE_USABLE_P (cpu_features, RTM))
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{
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if (CPU_FEATURE_USABLE_P (cpu_features, ERMS))
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return OPTIMIZE1 (avx2_unaligned_erms_rtm);
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return OPTIMIZE1 (avx2_unaligned_rtm);
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}
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if (!CPU_FEATURES_ARCH_P (cpu_features, Prefer_No_VZEROUPPER))
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{
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if (CPU_FEATURE_USABLE_P (cpu_features, ERMS))
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return OPTIMIZE1 (avx2_unaligned_erms);
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return OPTIMIZE1 (avx2_unaligned);
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}
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}
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if (CPU_FEATURE_USABLE_P (cpu_features, ERMS))
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return OPTIMIZE1 (sse2_unaligned_erms);
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return OPTIMIZE1 (sse2_unaligned);
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}
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libc_ifunc_redirected (__redirect___bzero, __bzero, IFUNC_SELECTOR ());
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weak_alias (__bzero, bzero)
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#endif
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