sysdeps/x86_64/multiarch/strstr.c

   1 /* Multiple versions of strstr.
   2    All versions must be listed in ifunc-impl-list.c.
   3    Copyright (C) 2012-2023 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 /* Redefine strstr so that the compiler won't complain about the type
  21    mismatch with the IFUNC selector in strong_alias, below.  */
  22 #undef  strstr
  23 #define strstr __redirect_strstr
  24 #include <string.h>
  25 #undef  strstr
  26
  27 #define STRSTR __strstr_generic
  28 #ifdef SHARED
  29 # undef libc_hidden_builtin_def
  30 # define libc_hidden_builtin_def(name) \
  31   __hidden_ver1 (__strstr_generic, __GI_strstr, __strstr_generic);
  32 #endif
  33
  34 #include "string/strstr.c"
  35
  36 extern __typeof (__redirect_strstr) __strstr_sse2_unaligned attribute_hidden;
  37 extern __typeof (__redirect_strstr) __strstr_generic attribute_hidden;
  38 extern __typeof (__redirect_strstr) __strstr_avx512 attribute_hidden;
  39
  40 #include "init-arch.h"
  41
  42 /* Avoid DWARF definition DIE on ifunc symbol so that GDB can handle
  43    ifunc symbol properly.  */
  44 extern __typeof (__redirect_strstr) __libc_strstr;
  45
  46 static inline void *
  47 IFUNC_SELECTOR (void)
  48 {
  49   const struct cpu_features *cpu_features = __get_cpu_features ();
  50
  51   if (!CPU_FEATURES_ARCH_P (cpu_features, Prefer_No_AVX512)
  52       && CPU_FEATURE_USABLE_P (cpu_features, AVX512VL)
  53       && CPU_FEATURE_USABLE_P (cpu_features, AVX512BW)
  54       && CPU_FEATURE_USABLE_P (cpu_features, AVX512DQ)
  55       && CPU_FEATURE_USABLE_P (cpu_features, BMI2))
  56     return __strstr_avx512;
  57
  58   if (CPU_FEATURES_ARCH_P (cpu_features, Fast_Unaligned_Load))
  59     return __strstr_sse2_unaligned;
  60
  61   return __strstr_generic;
  62 }
  63
  64 libc_ifunc_redirected (__redirect_strstr, __libc_strstr, IFUNC_SELECTOR ());
  65 #undef strstr
  66 strong_alias (__libc_strstr, strstr)