glibc/sysdeps/x86/fpu/fix-fp-int-compare-invalid.h
Joseph Myers 91c3985c23 Update x86 fix-fp-int-compare-invalid.h for GCC 8.
The glibc implementation of iseqsig relies on ordered comparison
operators raising the "invalid" exception for quiet NaN operands, with
a workaround on platforms where a GCC bug means that exception is not
raised.  For x86, that bug has now been fixed for GCC 8, so this patch
disables the workaround in that case.  If and when the corresponding
bugs for powerpc and s390 are fixed, the headers for those platforms
should of course be updated similarly.

Tested for x86_64 and x86, including with GCC mainline.  Note that
other failures appear with GCC mainline because of spurious use of
ordered comparison instructions for unordered operations
<https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82692>.

	* sysdeps/x86/fpu/fix-fp-int-compare-invalid.h
	(FIX_COMPARE_INVALID): Define to 0 if [__GNUC_PREREQ (8, 0)].
2017-10-24 00:33:08 +00:00

33 lines
1.3 KiB
C

/* Fix for missing "invalid" exceptions from floating-point
comparisons. x86 version.
Copyright (C) 2016-2017 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/>. */
#ifndef FIX_FP_INT_COMPARE_INVALID_H
#define FIX_FP_INT_COMPARE_INVALID_H 1
/* Before GCC 8, both x87 and SSE comparisons use unordered comparison
instructions when they should use ordered comparisons
<https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52451>. */
#if __GNUC_PREREQ (8, 0)
# define FIX_COMPARE_INVALID 0
#else
# define FIX_COMPARE_INVALID 1
#endif
#endif /* fix-fp-int-compare-invalid.h */