glibc/sysdeps/x86_64/fpu/fegetenv.c
Joseph Myers 9be36fb8cb Make x86_64 fegetenv preserve exception mask (bug 16198).
Bug 16198 is x86_64 fegetenv wrongly masking exceptions for which
traps are enabled, because that's a side-effect of the fnstenv
instruction.  This patch fixes it to use fldenv immediately after
fnstenv, like the i386 version.  Tested x86_64 and x86.

	[BZ #16198]
	* sysdeps/x86_64/fpu/fegetenv.c (fegetenv): Use fldenv after
	fnstenv.
	* math/test-fenv-preserve.c: New file.
	* math/Makefile (tests): Add test-fenv-preserve.
2014-03-26 18:59:08 +00:00

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C

/* Store current floating-point environment.
Copyright (C) 2001-2014 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
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <fenv.h>
int
fegetenv (fenv_t *envp)
{
__asm__ ("fnstenv %0\n"
/* fnstenv changes the exception mask, so load back the
stored environment. */
"fldenv %0\n"
"stmxcsr %1" : "=m" (*envp), "=m" (envp->__mxcsr));
/* Success. */
return 0;
}
libm_hidden_def (fegetenv)