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i386/x86_64: Optimize feholdexcept.

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Richard Henderson 2012-03-18 15:51:53 -07:00
parent 0fe0f1f86f
commit d0adc92230
3 changed files with 14 additions and 29 deletions
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3
ChangeLog
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@ -1,5 +1,8 @@
2012-03-19 Richard Henderson <rth@twiddle.net>
* sysdeps/i386/fpu/feholdexcpt.c (feholdexcept): Avoid the fldenv.
* sysdeps/x86_64/fpu/feholdexcpt.c (feholdexcept): Likewise.
* sysdeps/generic/math_private.h (default_libc_feupdateenv_test): New.
(libc_feupdateenv_test, libc_feupdateenv_testf): New.
(libc_feupdateenv_testl): New.

19
sysdeps/i386/fpu/feholdexcpt.c
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@ -1,6 +1,5 @@
/* Store current floating-point environment and clear exceptions.
Copyright (C) 1997, 1999, 2003, 2004, 2005, 2007
Free Software Foundation, Inc.
Copyright (C) 1997-2012 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
@ -26,19 +25,9 @@
int
feholdexcept (fenv_t *envp)
{
fenv_t temp;
/* Store the environment. */
__asm__ ("fnstenv %0" : "=m" (temp));
*envp = temp;
/* Now set all exceptions to non-stop. */
temp.__control_word |= 0x3f;
/* And clear all exceptions. */
temp.__status_word &= ~0x3f;
__asm__ ("fldenv %0" : : "m" (temp));
/* Store the environment. Recall that fnstenv has a side effect of
masking all exceptions. Then clear all exceptions. */
__asm__ volatile ("fnstenv %0; fnclex" : "=m" (*envp));
/* If the CPU supports SSE we set the MXCSR as well. */
if ((GLRO(dl_hwcap) & HWCAP_I386_XMM) != 0)

21
sysdeps/x86_64/fpu/feholdexcpt.c
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@ -1,5 +1,5 @@
/* Store current floating-point environment and clear exceptions.
Copyright (C) 2001, 2005, 2007 Free Software Foundation, Inc.
Copyright (C) 2001-2012 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
@ -22,20 +22,13 @@ int
feholdexcept (fenv_t *envp)
{
unsigned int mxcsr;
fenv_t temp;
/* Store the environment. */
__asm__ ("fnstenv %0\n"
"stmxcsr %1" : "=m" (temp), "=m" (temp.__mxcsr));
*envp = temp;
/* Now set all exceptions to non-stop, first the x87 FPU. */
temp.__control_word |= 0x3f;
/* And clear all exceptions. */
temp.__status_word &= ~0x3f;
__asm__ ("fldenv %0" : : "m" (temp));
/* Store the environment. Recall that fnstenv has a side effect of
masking all exceptions. Then clear all exceptions. */
__asm__ ("fnstenv %0\n\t"
"stmxcsr %1\n\t"
"fnclex"
: "=m" (*envp), "=m" (envp->__mxcsr));
/* Set the SSE MXCSR register. */
mxcsr = (envp->__mxcsr | 0x1f80) & ~0x3f;