Subversion Repositories openrisc

/*

 * Copyright (C) 2005 Free Software Foundation, Inc.

 *

 * This file is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License as published by the

 * Free Software Foundation; either version 2, or (at your option) any

 * later version.

 *

 * In addition to the permissions in the GNU General Public License, the

 * Free Software Foundation gives you unlimited permission to link the

 * compiled version of this file with other programs, and to distribute

 * those programs without any restriction coming from the use of this

 * file.  (The General Public License restrictions do apply in other

 * respects; for example, they cover modification of the file, and

 * distribution when not linked into another program.)

 *

 * This file is distributed in the hope that it will be useful, but

 * WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; see the file COPYING.  If not, write to

 * the Free Software Foundation, 51 Franklin Street, Fifth Floor,

 * Boston, MA 02110-1301, USA.

 *

 *    As a special exception, if you link this library with files

 *    compiled with GCC to produce an executable, this does not cause

 *    the resulting executable to be covered by the GNU General Public License.

 *    This exception does not however invalidate any other reasons why

 *    the executable file might be covered by the GNU General Public License.

 */

#define MXCSR_DAZ (1 << 6)      /* Enable denormals are zero mode */

#define MXCSR_FTZ (1 << 15)     /* Enable flush to zero mode */

#define FXSAVE  (1 << 24)

#define SSE     (1 << 25)

static void __attribute__((constructor))

#ifndef __x86_64__

/* The i386 ABI only requires 4-byte stack alignment, so this is necessary

   to make sure the fxsave struct gets correct alignment.

   See PR27537 and PR28621.  */

__attribute__ ((force_align_arg_pointer))

#endif

set_fast_math (void)

{

#ifndef __x86_64__

  /* All 64-bit targets have SSE and DAZ; only check them explicitly

     for 32-bit ones. */

  unsigned int eax, ebx, ecx, edx;

  /* See if we can use cpuid.  */

  asm volatile ("pushfl; pushfl; popl %0; movl %0,%1; xorl %2,%0;"

                "pushl %0; popfl; pushfl; popl %0; popfl"

                : "=&r" (eax), "=&r" (ebx)

                : "i" (0x00200000));

  if (((eax ^ ebx) & 0x00200000) == 0)

    return;

  /* Check the highest input value for eax.  */

  asm volatile ("xchgl %%ebx, %1; cpuid; xchgl %%ebx, %1"

                : "=a" (eax), "=r" (ebx), "=c" (ecx), "=d" (edx)

                : "0" (0));

  if (eax == 0)

    return;

  asm volatile ("xchgl %%ebx, %1; cpuid; xchgl %%ebx, %1"

                : "=a" (eax), "=r" (ebx), "=c" (ecx), "=d" (edx)

                : "0" (1));

  if (edx & SSE)

    {

      unsigned int mxcsr = __builtin_ia32_stmxcsr ();

      mxcsr |= MXCSR_FTZ;

      if (edx & FXSAVE)

        {

          /* Check if DAZ is available.  */

          struct

            {

              unsigned short int cwd;

              unsigned short int swd;

              unsigned short int twd;

              unsigned short int fop;

              long int fip;

              long int fcs;

              long int foo;

              long int fos;

              long int mxcsr;

              long int mxcsr_mask;

              long int st_space[32];

              long int xmm_space[32];

              long int padding[56];

            } __attribute__ ((aligned (16))) fxsave;

          __builtin_memset (&fxsave, 0, sizeof (fxsave));

          asm volatile ("fxsave %0" : "=m" (fxsave) : "m" (fxsave));

          if (fxsave.mxcsr_mask & MXCSR_DAZ)

            mxcsr |= MXCSR_DAZ;

        }

      __builtin_ia32_ldmxcsr (mxcsr);

    }

#else

  unsigned int mxcsr = __builtin_ia32_stmxcsr ();

  mxcsr |= MXCSR_DAZ | MXCSR_FTZ;

  __builtin_ia32_ldmxcsr (mxcsr);

#endif

}