sysdeps/x86_64/multiarch/strncmp.c

   1 /* Multiple versions of strncmp.
   2    All versions must be listed in ifunc-impl-list.c.
   3    Copyright (C) 2017-2022 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    <https://www.gnu.org/licenses/>.  */
  19
  20 /* Define multiple versions only for the definition in libc.  */
  21 #if IS_IN (libc)
  22 # define strncmp __redirect_strncmp
  23 # include <string.h>
  24 # undef strncmp
  25
  26 # define SYMBOL_NAME strncmp
  27 # include <init-arch.h>
  28
  29 extern __typeof (REDIRECT_NAME) OPTIMIZE (evex) attribute_hidden;
  30
  31 extern __typeof (REDIRECT_NAME) OPTIMIZE (avx2) attribute_hidden;
  32 extern __typeof (REDIRECT_NAME) OPTIMIZE (avx2_rtm) attribute_hidden;
  33
  34 extern __typeof (REDIRECT_NAME) OPTIMIZE (sse42) attribute_hidden;
  35
  36 extern __typeof (REDIRECT_NAME) OPTIMIZE (sse2) attribute_hidden;
  37
  38 static inline void *
  39 IFUNC_SELECTOR (void)
  40 {
  41   const struct cpu_features *cpu_features = __get_cpu_features ();
  42
  43   if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX2)
  44       && X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, BMI2)
  45       && X86_ISA_CPU_FEATURES_ARCH_P (cpu_features,
  46                                       AVX_Fast_Unaligned_Load, ))
  47     {
  48       if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX512VL)
  49           && X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX512BW))
  50         return OPTIMIZE (evex);
  51
  52       if (CPU_FEATURE_USABLE_P (cpu_features, RTM))
  53         return OPTIMIZE (avx2_rtm);
  54
  55       if (X86_ISA_CPU_FEATURES_ARCH_P (cpu_features,
  56                                        Prefer_No_VZEROUPPER, !))
  57         return OPTIMIZE (avx2);
  58     }
  59
  60   if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, SSE4_2)
  61       && !CPU_FEATURES_ARCH_P (cpu_features, Slow_SSE4_2))
  62     return OPTIMIZE (sse42);
  63
  64   return OPTIMIZE (sse2);
  65 }
  66
  67 libc_ifunc_redirected (__redirect_strncmp, strncmp, IFUNC_SELECTOR ());
  68
  69 # ifdef SHARED
  70 __hidden_ver1 (strncmp, __GI_strncmp, __redirect_strncmp)
  71   __attribute__ ((visibility ("hidden"))) __attribute_copy__ (strncmp);
  72 # endif
  73 #endif