sysdeps/x86_64/multiarch/strcmp.c

   1 /* Multiple versions of strcmp.
   2    All versions must be listed in ifunc-impl-list.c.
   3    Copyright (C) 2017-2024 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 strcmp __redirect_strcmp
  23 # include <string.h>
  24 # undef strcmp
  25
  26 # define SYMBOL_NAME strcmp
  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)
  37     OPTIMIZE (sse2_unaligned) attribute_hidden;
  38 extern __typeof (REDIRECT_NAME) OPTIMIZE (sse2) attribute_hidden;
  39
  40
  41
  42 static inline void *
  43 IFUNC_SELECTOR (void)
  44 {
  45   const struct cpu_features *cpu_features = __get_cpu_features ();
  46
  47   if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX2)
  48       && X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, BMI2)
  49       && X86_ISA_CPU_FEATURES_ARCH_P (cpu_features,
  50                                       AVX_Fast_Unaligned_Load, ))
  51     {
  52       if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX512VL)
  53           && X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, AVX512BW))
  54         return OPTIMIZE (evex);
  55
  56       if (CPU_FEATURE_USABLE_P (cpu_features, RTM))
  57         return OPTIMIZE (avx2_rtm);
  58
  59       if (X86_ISA_CPU_FEATURES_ARCH_P (cpu_features,
  60                                        Prefer_No_VZEROUPPER, !))
  61         return OPTIMIZE (avx2);
  62     }
  63
  64   if (X86_ISA_CPU_FEATURE_USABLE_P (cpu_features, SSE4_2)
  65       /* Keep this as runtime check.  Some ISA level >= 2 CPUs such as
  66          Tremont, Silvermont, and more check this.  */
  67       && !CPU_FEATURES_ARCH_P (cpu_features, Slow_SSE4_2))
  68     return OPTIMIZE (sse42);
  69
  70   /* Keep this as runtime check.  The standard SSE2 version has
  71      meaningful optimizations around keeping all loads aligned in the
  72      main loop which can benefit some ISA level >= 2 CPUs.  */
  73   if (CPU_FEATURES_ARCH_P (cpu_features, Fast_Unaligned_Load))
  74     return OPTIMIZE (sse2_unaligned);
  75
  76   return OPTIMIZE (sse2);
  77 }
  78
  79 libc_ifunc_redirected (__redirect_strcmp, strcmp, IFUNC_SELECTOR ());
  80
  81 # ifdef SHARED
  82 __hidden_ver1 (strcmp, __GI_strcmp, __redirect_strcmp)
  83   __attribute__ ((visibility ("hidden"))) __attribute_copy__ (strcmp);
  84 # endif
  85 #endif