sysdeps/x86_64/multiarch/strchr.c

   1 /* Multiple versions of strchr.
   2    All versions must be listed in ifunc-impl-list.c.
   3    Copyright (C) 2009-2017 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 /* Define multiple versions only for the definition in libc.  */
  21 #if IS_IN (libc)
  22 # define strchr __redirect_strchr
  23 # include <string.h>
  24 # undef strchr
  25
  26 # define SYMBOL_NAME strchr
  27 # include <init-arch.h>
  28
  29 extern __typeof (REDIRECT_NAME) OPTIMIZE (sse2) attribute_hidden;
  30 extern __typeof (REDIRECT_NAME) OPTIMIZE (sse2_no_bsf) attribute_hidden;
  31 extern __typeof (REDIRECT_NAME) OPTIMIZE (avx2) attribute_hidden;
  32
  33 static inline void *
  34 IFUNC_SELECTOR (void)
  35 {
  36   const struct cpu_features* cpu_features = __get_cpu_features ();
  37
  38   if (!CPU_FEATURES_ARCH_P (cpu_features, Prefer_No_VZEROUPPER)
  39       && CPU_FEATURES_ARCH_P (cpu_features, AVX2_Usable)
  40       && CPU_FEATURES_ARCH_P (cpu_features, AVX_Fast_Unaligned_Load))
  41     return OPTIMIZE (avx2);
  42
  43   if (CPU_FEATURES_ARCH_P (cpu_features, Slow_BSF))
  44     return OPTIMIZE (sse2_no_bsf);
  45
  46   return OPTIMIZE (sse2);
  47 }
  48
  49 libc_ifunc_redirected (__redirect_strchr, strchr, IFUNC_SELECTOR ());
  50 weak_alias (strchr, index)
  51 # ifdef SHARED
  52 __hidden_ver1 (strchr, __GI_strchr, __redirect_strchr)
  53   __attribute__((visibility ("hidden")));
  54 # endif
  55 #endif