glibc/math/s_fmin_template.c
Joseph Myers f02bb0004c Fix generic fmax, fmin sNaN handling (bug 20947).
Various fmax and fmin function implementations mishandle sNaN
arguments:

(a) When both arguments are NaNs, the return value should be a qNaN,
but sometimes it is an sNaN if at least one argument is an sNaN.

(b) Under TS 18661-1 semantics, if either argument is an sNaN then the
result should be a qNaN (whereas if one argument is a qNaN and the
other is not a NaN, the result should be the non-NaN argument).
Various implementations treat sNaNs like qNaNs here.

This patch fixes the generic implementations used in the absence of
architecture-specific versions.

Tested for mips64 and powerpc (together with testcases that I'll add
along with the x86_64 / x86 fixes).

	[BZ #20947]
	* math/s_fmax_template.c (M_DECL_FUNC (__fmax)): Add the arguments
	when either is a signaling NaN.
	* math/s_fmin_template.c (M_DECL_FUNC (__fmin)): Likewise.
2016-12-14 22:41:26 +00:00

40 lines
1.2 KiB
C

/* Return minimum numeric value of X and Y.
Copyright (C) 1997-2016 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
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 <math.h>
FLOAT
M_DECL_FUNC (__fmin) (FLOAT x, FLOAT y)
{
if (islessequal (x, y))
return x;
else if (isgreater (x, y))
return y;
else if (issignaling (x) || issignaling (y))
return x + y;
else
return isnan (y) ? x : y;
}
declare_mgen_alias (__fmin, fmin);
#if M_LIBM_NEED_COMPAT (fmin)
declare_mgen_libm_compat (__fmin, fmin)
#endif