[PATCH] Remove alpha specific fmax, fmin to fix sNaN handling [BZ #20947]

[Aurelien Jarno <aurelien at aurel32 dot net>]

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 #20947]
	* 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.
---
 ChangeLog                   |  8 +++++++
 sysdeps/alpha/fpu/s_fmax.S  | 52 ---------------------------------------------
 sysdeps/alpha/fpu/s_fmaxf.S |  1 -
 sysdeps/alpha/fpu/s_fmin.S  | 52 ---------------------------------------------
 sysdeps/alpha/fpu/s_fminf.S |  1 -
 5 files changed, 8 insertions(+), 106 deletions(-)
 delete mode 100644 sysdeps/alpha/fpu/s_fmax.S
 delete mode 100644 sysdeps/alpha/fpu/s_fmaxf.S
 delete mode 100644 sysdeps/alpha/fpu/s_fmin.S
 delete mode 100644 sysdeps/alpha/fpu/s_fminf.S

diff --git a/ChangeLog b/ChangeLog
index cd6fc15767..3f6002a175 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2017-12-31  Aurelien Jarno  <aurelien@aurel32.net>
+
+	[BZ #20947]
+	* 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.
+
 2017-12-30  Aurelien Jarno  <aurelien@aurel32.net>
 	    Dmitry V. Levin  <ldv@altlinux.org>
 
diff --git a/sysdeps/alpha/fpu/s_fmax.S b/sysdeps/alpha/fpu/s_fmax.S
deleted file mode 100644
index 5da9e0df11..0000000000
--- a/sysdeps/alpha/fpu/s_fmax.S
+++ /dev/null
@@ -1,52 +0,0 @@
-/* Copyright (C) 2007-2017 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)
diff --git a/sysdeps/alpha/fpu/s_fmaxf.S b/sysdeps/alpha/fpu/s_fmaxf.S
deleted file mode 100644
index 3c2d62bb81..0000000000
--- a/sysdeps/alpha/fpu/s_fmaxf.S
+++ /dev/null
@@ -1 +0,0 @@
-/* __fmaxf is in s_fmax.c  */
diff --git a/sysdeps/alpha/fpu/s_fmin.S b/sysdeps/alpha/fpu/s_fmin.S
deleted file mode 100644
index d752223151..0000000000
--- a/sysdeps/alpha/fpu/s_fmin.S
+++ /dev/null
@@ -1,52 +0,0 @@
-/* Copyright (C) 2007-2017 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)
diff --git a/sysdeps/alpha/fpu/s_fminf.S b/sysdeps/alpha/fpu/s_fminf.S
deleted file mode 100644
index 10ab7fe53c..0000000000
--- a/sysdeps/alpha/fpu/s_fminf.S
+++ /dev/null
@@ -1 +0,0 @@
-/* __fminf is in s_fmin.c  */
-- 
2.15.1