117 lines
3.7 KiB
C
117 lines
3.7 KiB
C
/*
|
|
* 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
|
|
}
|