sysdeps/sparc/cpu_relax.c

   1 /* CPU strand yielding for busy loops.  Linux/sparc version.
   2    Copyright (C) 2017-2020 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <sparc-ifunc.h>
  20
  21 #ifdef __sparc_v9__
  22 static void
  23 __cpu_relax_generic (void)
  24 {
  25   asm volatile ("rd %ccr, %g0;"
  26                 "rd %ccr, %g0;"
  27                 "rd %ccr, %g0");
  28 }
  29
  30 static void
  31 __cpu_relax_pause (void)
  32 {
  33   asm volatile ("wr %g0, 128, %asr27");
  34 }
  35
  36 sparc_libc_ifunc (__cpu_relax,
  37                   hwcap & HWCAP_SPARC_PAUSE
  38                   ? __cpu_relax_pause
  39                   : __cpu_relax_generic)
  40 #endif