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git.ipfire.org Git - thirdparty/gcc.git/blob - libgcc/config/i386/crtfastmath.c
2 * Copyright (C) 2005-2014 Free Software Foundation, Inc.
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
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.
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.
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/>.
25 #define MXCSR_DAZ (1 << 6) /* Enable denormals are zero mode */
26 #define MXCSR_FTZ (1 << 15) /* Enable flush to zero mode */
29 /* All 64-bit targets have SSE and DAZ;
30 only check them explicitly for 32-bit ones. */
34 #if !defined __x86_64__ && defined __sun__ && defined __svr4__
38 static volatile sig_atomic_t sigill_caught
;
41 sigill_hdlr (int sig
__attribute((unused
)),
42 siginfo_t
*sip
__attribute__((unused
)),
46 /* Set PC to the instruction after the faulting one to skip over it,
47 otherwise we enter an infinite loop. 3 is the size of the movaps
49 ucp
->uc_mcontext
.gregs
[EIP
] += 3;
54 static void __attribute__((constructor
))
56 /* The i386 ABI only requires 4-byte stack alignment, so this is necessary
57 to make sure the fxsave struct gets correct alignment.
58 See PR27537 and PR28621. */
59 __attribute__ ((force_align_arg_pointer
))
64 unsigned int eax
, ebx
, ecx
, edx
;
66 if (!__get_cpuid (1, &eax
, &ebx
, &ecx
, &edx
))
75 /* Check if DAZ is available. */
87 unsigned int mxcsr_mask
;
88 unsigned int st_space
[32];
89 unsigned int xmm_space
[32];
90 unsigned int padding
[56];
91 } __attribute__ ((aligned (16))) fxsave
;
93 /* This is necessary since some implementations of FXSAVE
94 do not modify reserved areas within the image. */
95 fxsave
.mxcsr_mask
= 0;
97 __builtin_ia32_fxsave (&fxsave
);
101 if (fxsave
.mxcsr_mask
& MXCSR_DAZ
)
105 mxcsr
= __builtin_ia32_stmxcsr ();
108 __builtin_ia32_ldmxcsr (mxcsr
);
111 unsigned int mxcsr
= __builtin_ia32_stmxcsr ();
112 mxcsr
|= MXCSR_DAZ
| MXCSR_FTZ
;
113 __builtin_ia32_ldmxcsr (mxcsr
);