1  /* Multiple versions of strncmp.
       2     All versions must be listed in ifunc-impl-list.c.
       3     Copyright (C) 2017-2023 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  /* 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