libgcc/config/arm/crtfastmath.c

   1 /*
   2  * Copyright (C) 2014-2018 Free Software Foundation, Inc.
   3  *
   4  * This file is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License as published by the
   6  * Free Software Foundation; either version 3, or (at your option) any
   7  * later version.
   8  *
   9  * This file is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * Under Section 7 of GPL version 3, you are granted additional
  15  * permissions described in the GCC Runtime Library Exception, version
  16  * 3.1, as published by the Free Software Foundation.
  17  *
  18  * You should have received a copy of the GNU General Public License and
  19  * a copy of the GCC Runtime Library Exception along with this program;
  20  * see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  21  * <http://www.gnu.org/licenses/>.
  22  */
  23
  24 /* Enable flush-to-zero support for -ffast-math on VFP targets.  */
  25 #ifndef __SOFTFP__
  26
  27 #define FPSCR_FZ                (1 << 24)
  28
  29 static void __attribute__((constructor))
  30 __arm_set_fast_math (void)
  31 {
  32   unsigned int fpscr_save;
  33
  34   /* Set the FZ (flush-to-zero) bit in FPSCR.  */
  35   __asm__("vmrs %0, fpscr" : "=r" (fpscr_save));
  36   fpscr_save |= FPSCR_FZ;
  37   __asm__("vmsr fpscr, %0" : : "r" (fpscr_save));
  38 }
  39
  40 #endif /* __SOFTFP__  */