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Fix ldbl-128ibm remainderl equality test for zero low part (bug 19677).

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The ldbl-128ibm implementation of remainderl has logic resulting in
incorrect tests for equality of the absolute values of the arguments
in the case of zero low parts.  If the low parts are both zero but
with different signs, this can wrongly cause equal arguments to be
treated as different, resulting in turn in incorrect signs of zero
result in nondefault rounding modes arising from the subtractions done
when the arguments are not equal.

This patch fixes the logic to convert -0 low parts into +0 before the
comparison (remquo already has separate logic to deal with signs of
zero results, so doesn't need such a change).  Tests are added for
remainderl and remquol similar to that for fmodl, and based on a
refactoring of it, since the bug depends on low parts which should not
be relied upon in tests not setting the representation explicitly
(although in fact the bug shows up in test-ldouble with current GCC).
Tested for powerpc.

	[BZ #19677]
	* sysdeps/ieee754/ldbl-128ibm/e_remainderl.c
	(__ieee754_remainderl): Put zero low parts in canonical form.
	* sysdeps/ieee754/ldbl-128ibm/test-fmodrem-ldbl-128ibm.c: New
	file.  Based on
	sysdeps/ieee754/ldbl-128ibm/test-fmodl-ldbl-128ibm.c.
	* sysdeps/ieee754/ldbl-128ibm/test-fmodl-ldbl-128ibm.c: Replace
	with wrapper round test-fmodrem-ldbl-128ibm.c.
	* sysdeps/ieee754/ldbl-128ibm/test-remainderl-ldbl-128ibm.c: New
	file.
	* sysdeps/ieee754/ldbl-128ibm/test-remquol-ldbl-128ibm.c:
	Likewise.
	* sysdeps/ieee754/ldbl-128ibm/Makefile (tests): Add
	test-remainderl-ldbl-128ibm and test-remquol-ldbl-128ibm.
This commit is contained in:
Joseph Myers 2016-03-08 00:27:21 +00:00
parent 920b35c92e
commit cc4084017e
7 changed files with 161 additions and 60 deletions
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17
ChangeLog
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@ -1,3 +1,20 @@
2016-03-08 Joseph Myers <joseph@codesourcery.com>
[BZ #19677]
* sysdeps/ieee754/ldbl-128ibm/e_remainderl.c
(__ieee754_remainderl): Put zero low parts in canonical form.
* sysdeps/ieee754/ldbl-128ibm/test-fmodrem-ldbl-128ibm.c: New
file. Based on
sysdeps/ieee754/ldbl-128ibm/test-fmodl-ldbl-128ibm.c.
* sysdeps/ieee754/ldbl-128ibm/test-fmodl-ldbl-128ibm.c: Replace
with wrapper round test-fmodrem-ldbl-128ibm.c.
* sysdeps/ieee754/ldbl-128ibm/test-remainderl-ldbl-128ibm.c: New
file.
* sysdeps/ieee754/ldbl-128ibm/test-remquol-ldbl-128ibm.c:
Likewise.
* sysdeps/ieee754/ldbl-128ibm/Makefile (tests): Add
test-remainderl-ldbl-128ibm and test-remquol-ldbl-128ibm.
2016-03-07 Florian Weimer <fweimer@redhat.com>
[BZ #19610]

3
sysdeps/ieee754/ldbl-128ibm/Makefile
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@ -10,5 +10,6 @@ $(objpfx)tst-strtold-ldbl-128ibm: $(libm)
endif
ifeq ($(subdir),math)
tests += test-fmodl-ldbl-128ibm
tests += test-fmodl-ldbl-128ibm test-remainderl-ldbl-128ibm \
test-remquol-ldbl-128ibm
endif

4
sysdeps/ieee754/ldbl-128ibm/e_remainderl.c
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@ -46,6 +46,10 @@ __ieee754_remainderl(long double x, long double p)
hp &= 0x7fffffffffffffffLL;
lx ^= sx;
hx &= 0x7fffffffffffffffLL;
if (lp == 0x8000000000000000ULL)
lp = 0;
if (lx == 0x8000000000000000ULL)
lx = 0;
/* purge off exception values */
if(hp==0) return (x*p)/(x*p); /* p = 0 */

62
sysdeps/ieee754/ldbl-128ibm/test-fmodl-ldbl-128ibm.c
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@ -16,62 +16,6 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <float.h>
#include <math.h>
#include <stdio.h>
union u
{
long double ld;
double d[2];
};
volatile union u p1 = { .d = { DBL_MIN, 0.0 } };
volatile union u p2 = { .d = { DBL_MIN, -0.0 } };
volatile union u m1 = { .d = { -DBL_MIN, 0.0 } };
volatile union u m2 = { .d = { -DBL_MIN, -0.0 } };
static int
test_fmodl (const char *s, long double x, long double y, long double expected)
{
volatile long double r;
r = fmodl (x, y);
if (r != expected || copysignl (1.0, r) != copysignl (1.0, expected))
{
printf ("FAIL: fmodl (%s)\n", s);
return 1;
}
else
{
printf ("PASS: fmodl (%s)\n", s);
return 0;
}
}
#define TEST_FMODL(a, b, e) test_fmodl (#a ", " #b, a, b, e)
static int
do_test (void)
{
int result = 0;
result |= TEST_FMODL (p1.ld, p1.ld, 0.0L);
result |= TEST_FMODL (p1.ld, p2.ld, 0.0L);
result |= TEST_FMODL (p1.ld, m1.ld, 0.0L);
result |= TEST_FMODL (p1.ld, m2.ld, 0.0L);
result |= TEST_FMODL (p2.ld, p1.ld, 0.0L);
result |= TEST_FMODL (p2.ld, p2.ld, 0.0L);
result |= TEST_FMODL (p2.ld, m1.ld, 0.0L);
result |= TEST_FMODL (p2.ld, m2.ld, 0.0L);
result |= TEST_FMODL (m1.ld, p1.ld, -0.0L);
result |= TEST_FMODL (m1.ld, p2.ld, -0.0L);
result |= TEST_FMODL (m1.ld, m1.ld, -0.0L);
result |= TEST_FMODL (m1.ld, m2.ld, -0.0L);
result |= TEST_FMODL (m2.ld, p1.ld, -0.0L);
result |= TEST_FMODL (m2.ld, p2.ld, -0.0L);
result |= TEST_FMODL (m2.ld, m1.ld, -0.0L);
result |= TEST_FMODL (m2.ld, m2.ld, -0.0L);
return result;
}
#define TEST_FUNCTION do_test ()
#include "../../../test-skeleton.c"
#define FUNC fmodl
#define SETUP
#include "test-fmodrem-ldbl-128ibm.c"

84
sysdeps/ieee754/ldbl-128ibm/test-fmodrem-ldbl-128ibm.c Normal file
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@ -0,0 +1,84 @@
/* Test for ldbl-128ibm fmodl etc. handling of equal values.
Copyright (C) 2016 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>
#include <float.h>
#include <math.h>
#include <stdio.h>
/* FUNC is defined to be the name of the function to test. */
#define STRX(x) #x
#define STR(x) STRX (x)
#define SFUNC STR (FUNC)
union u
{
long double ld;
double d[2];
};
volatile union u p1 = { .d = { DBL_MIN, 0.0 } };
volatile union u p2 = { .d = { DBL_MIN, -0.0 } };
volatile union u m1 = { .d = { -DBL_MIN, 0.0 } };
volatile union u m2 = { .d = { -DBL_MIN, -0.0 } };
static int
test_func (const char *s, long double x, long double y, long double expected)
{
volatile long double r;
r = FUNC (x, y);
if (r != expected || copysignl (1.0, r) != copysignl (1.0, expected))
{
printf ("FAIL: " SFUNC " (%s)\n", s);
return 1;
}
else
{
printf ("PASS: " SFUNC " (%s)\n", s);
return 0;
}
}
#define TEST_FUNC(a, b, e) test_func (#a ", " #b, a, b, e)
static int
do_test (void)
{
int result = 0;
SETUP;
result |= TEST_FUNC (p1.ld, p1.ld, 0.0L);
result |= TEST_FUNC (p1.ld, p2.ld, 0.0L);
result |= TEST_FUNC (p1.ld, m1.ld, 0.0L);
result |= TEST_FUNC (p1.ld, m2.ld, 0.0L);
result |= TEST_FUNC (p2.ld, p1.ld, 0.0L);
result |= TEST_FUNC (p2.ld, p2.ld, 0.0L);
result |= TEST_FUNC (p2.ld, m1.ld, 0.0L);
result |= TEST_FUNC (p2.ld, m2.ld, 0.0L);
result |= TEST_FUNC (m1.ld, p1.ld, -0.0L);
result |= TEST_FUNC (m1.ld, p2.ld, -0.0L);
result |= TEST_FUNC (m1.ld, m1.ld, -0.0L);
result |= TEST_FUNC (m1.ld, m2.ld, -0.0L);
result |= TEST_FUNC (m2.ld, p1.ld, -0.0L);
result |= TEST_FUNC (m2.ld, p2.ld, -0.0L);
result |= TEST_FUNC (m2.ld, m1.ld, -0.0L);
result |= TEST_FUNC (m2.ld, m2.ld, -0.0L);
return result;
}
#define TEST_FUNCTION do_test ()
#include "../../../test-skeleton.c"

21
sysdeps/ieee754/ldbl-128ibm/test-remainderl-ldbl-128ibm.c Normal file
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@ -0,0 +1,21 @@
/* Test for ldbl-128ibm remainderl handling of equal values (bug 19677).
Copyright (C) 2016 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/>. */
#define FUNC remainderl
#define SETUP fesetround (FE_DOWNWARD)
#include "test-fmodrem-ldbl-128ibm.c"

30
sysdeps/ieee754/ldbl-128ibm/test-remquol-ldbl-128ibm.c Normal file
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@ -0,0 +1,30 @@
/* Test for ldbl-128ibm remquol handling of equal values (bug 19677).
Copyright (C) 2016 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 <math.h>
static long double
wrap_remquol (long double x, long double y)
{
int quo;
return remquol (x, y, &quo);
}
#define FUNC wrap_remquol
#define SETUP fesetround (FE_DOWNWARD)
#include "test-fmodrem-ldbl-128ibm.c"