libgcc/config/sparc/crtfastmath.c

   1 /*
   2  * Copyright (C) 2001-2018 Free Software Foundation, Inc.
   3  * Contributed by David S. Miller (davem@redhat.com)
   4  *
   5  * This file is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License as published by the
   7  * Free Software Foundation; either version 3, or (at your option) any
   8  * later version.
   9  *
  10  * This file is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License for more details.
  14  *
  15  * Under Section 7 of GPL version 3, you are granted additional
  16  * permissions described in the GCC Runtime Library Exception, version
  17  * 3.1, as published by the Free Software Foundation.
  18  *
  19  * You should have received a copy of the GNU General Public License and
  20  * a copy of the GCC Runtime Library Exception along with this program;
  21  * see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  22  * <http://www.gnu.org/licenses/>.
  23  */
  24
  25 #define FPRS_NS         (1 << 22)       /* Non-Standard fpu results */
  26
  27 static void __attribute__((constructor))
  28 set_fast_math (void)
  29 {
  30   unsigned int fsr;
  31
  32   /* This works for the 64-bit case because, even if 32-bit ld/st of
  33      the fsr register modified the upper 32-bit, the only thing up there
  34      are the 3 other condition codes which are "do not care" at the time
  35      that this runs.  */
  36
  37   __asm__("st %%fsr, %0"
  38           : "=m" (fsr));
  39
  40   fsr |= FPRS_NS;
  41
  42   __asm__("ld %0, %%fsr"
  43           : : "m" (fsr));
  44 }