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Remove alpha specific fmax, fmin to fix sNaN handling [BZ #22660]

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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.

One way to fix that is to detect the sNaN and add a special case. That
said there is no FPU instruction to do that, so it requires transfering
the FP value to an integer register and testing bits. This becomes quite
complicated so it's probably better to just use the generic versions of
these functions which just do that through issignaling.

Changelog:
	[BZ #22660]
	* sysdeps/alpha/fpu/s_fmax.S: Remove file.
	* sysdeps/alpha/fpu/s_fmaxf.S: Likewise.
	* sysdeps/alpha/fpu/s_fmin.S: Likewise.
	* sysdeps/alpha/fpu/s_fminf.S: Likewise.
This commit is contained in:
Aurelien Jarno 2018-01-02 09:55:48 +01:00
parent b05cb613e7
commit 6a9dd7a7c5
5 changed files with 8 additions and 106 deletions
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8
ChangeLog
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@ -1,3 +1,11 @@
2018-01-02 Aurelien Jarno <aurelien@aurel32.net>
[BZ #22660]
* sysdeps/alpha/fpu/s_fmax.S: Remove file.
* sysdeps/alpha/fpu/s_fmaxf.S: Likewise.
* sysdeps/alpha/fpu/s_fmin.S: Likewise.
* sysdeps/alpha/fpu/s_fminf.S: Likewise.
2018-01-01 Dmitry V. Levin <ldv@altlinux.org>
[BZ #22433]

52
sysdeps/alpha/fpu/s_fmax.S
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/* Copyright (C) 2007-2018 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Richard Henderson.
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 <sysdep.h>
#include <math_ldbl_opt.h>
#include <libm-alias-float.h>
#include <libm-alias-double.h>
.set noat
.set noreorder
.text
ENTRY (__fmax)
.prologue 0
cmptun/su $f16, $f16, $f10
cmptun/su $f17, $f17, $f11
fmov $f17, $f0
unop
trapb
fbne $f10, $ret
fmov $f16, $f0
fbne $f11, $ret
cmptlt/su $f16, $f17, $f11
trapb
fcmovne $f11, $f17, $f0
$ret: ret
END (__fmax)
/* Given the in-register format of single-precision, this works there too. */
strong_alias (__fmax, __fmaxf)
libm_alias_float (__fmax, fmax)
libm_alias_double (__fmax, fmax)

1
sysdeps/alpha/fpu/s_fmaxf.S
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/* __fmaxf is in s_fmax.c */

52
sysdeps/alpha/fpu/s_fmin.S
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@ -1,52 +0,0 @@
/* Copyright (C) 2007-2018 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Richard Henderson.
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 <sysdep.h>
#include <math_ldbl_opt.h>
#include <libm-alias-float.h>
#include <libm-alias-double.h>
.set noat
.set noreorder
.text
ENTRY (__fmin)
.prologue 0
cmptun/su $f16, $f16, $f10
cmptun/su $f17, $f17, $f11
fmov $f17, $f0
unop
trapb
fbne $f10, $ret
fmov $f16, $f0
fbne $f11, $ret
cmptlt/su $f17, $f16, $f11
trapb
fcmovne $f11, $f17, $f0
$ret: ret
END (__fmin)
/* Given the in-register format of single-precision, this works there too. */
strong_alias (__fmin, __fminf)
libm_alias_float (__fmin, fmin)
libm_alias_double (__fmin, fmin)

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sysdeps/alpha/fpu/s_fminf.S
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/* __fminf is in s_fmin.c */