90 lines
2.6 KiB
C
90 lines
2.6 KiB
C
/*
|
|
* Copyright (C) 2005, 2007, 2009 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 3, or (at your option) any
|
|
* later version.
|
|
*
|
|
* 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.
|
|
*
|
|
* Under Section 7 of GPL version 3, you are granted additional
|
|
* permissions described in the GCC Runtime Library Exception, version
|
|
* 3.1, as published by the Free Software Foundation.
|
|
*
|
|
* You should have received a copy of the GNU General Public License and
|
|
* a copy of the GCC Runtime Library Exception along with this program;
|
|
* see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
|
|
* <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#define MXCSR_DAZ (1 << 6) /* Enable denormals are zero mode */
|
|
#define MXCSR_FTZ (1 << 15) /* Enable flush to zero mode */
|
|
|
|
#ifndef __x86_64__
|
|
/* All 64-bit targets have SSE and DAZ;
|
|
only check them explicitly for 32-bit ones. */
|
|
#include "cpuid.h"
|
|
#endif
|
|
|
|
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__
|
|
unsigned int eax, ebx, ecx, edx;
|
|
|
|
if (!__get_cpuid (1, &eax, &ebx, &ecx, &edx))
|
|
return;
|
|
|
|
if (edx & bit_SSE)
|
|
{
|
|
unsigned int mxcsr = __builtin_ia32_stmxcsr ();
|
|
|
|
mxcsr |= MXCSR_FTZ;
|
|
|
|
if (edx & bit_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
|
|
}
|