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glibc/sysdeps/ieee754/ldbl-128ibm/test-fmodl-ldbl-128ibm.c

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Fix ldbl-128ibm fmodl handling of equal arguments with low part zero (bug 19602). The ldbl-128ibm implementation of fmodl has logic to detect when the first argument has absolute value less than or equal to the second. This logic is only correct for nonzero low parts; if the high parts are equal and the low parts are zero, then the signs of the low parts (which have no semantic effect on the value of the long double number) can result in equal values being wrongly treated as unequal, and an incorrect result being returned from fmodl. This patch fixes this by checking for the case of zero low parts. Although this does show up in tests from libm-test.inc (both tests of fmodl, and, indirectly, of remainderl / dreml), the dependence on non-semantic zero low parts means that test shouldn't be expected to reproduce it reliably; thus, this patch adds a standalone test that sets up affected values using unions. Tested for powerpc. [BZ #19602] * sysdeps/ieee754/ldbl-128ibm/e_fmodl.c (__ieee754_fmodl): Handle equal high parts and both low parts zero specially. * sysdeps/ieee754/ldbl-128ibm/test-fmodl-ldbl-128ibm.c: New test. * sysdeps/ieee754/ldbl-128ibm/Makefile [$(subdir) = math] (tests): Add test-fmodl-ldbl-128ibm.
2016-02-18 22:54:07 +00:00
/* Test for ldbl-128ibm fmodl handling of equal values (bug 19602).
Update copyright dates with scripts/update-copyrights.
2017-01-01 00:14:16 +00:00
Copyright (C) 2016-2017 Free Software Foundation, Inc.
Fix ldbl-128ibm fmodl handling of equal arguments with low part zero (bug 19602). The ldbl-128ibm implementation of fmodl has logic to detect when the first argument has absolute value less than or equal to the second. This logic is only correct for nonzero low parts; if the high parts are equal and the low parts are zero, then the signs of the low parts (which have no semantic effect on the value of the long double number) can result in equal values being wrongly treated as unequal, and an incorrect result being returned from fmodl. This patch fixes this by checking for the case of zero low parts. Although this does show up in tests from libm-test.inc (both tests of fmodl, and, indirectly, of remainderl / dreml), the dependence on non-semantic zero low parts means that test shouldn't be expected to reproduce it reliably; thus, this patch adds a standalone test that sets up affected values using unions. Tested for powerpc. [BZ #19602] * sysdeps/ieee754/ldbl-128ibm/e_fmodl.c (__ieee754_fmodl): Handle equal high parts and both low parts zero specially. * sysdeps/ieee754/ldbl-128ibm/test-fmodl-ldbl-128ibm.c: New test. * sysdeps/ieee754/ldbl-128ibm/Makefile [$(subdir) = math] (tests): Add test-fmodl-ldbl-128ibm.
2016-02-18 22:54:07 +00:00
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/>. */
Fix ldbl-128ibm remainderl equality test for zero low part (bug 19677). 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.
2016-03-08 00:27:21 +00:00
#define FUNC fmodl
#define SETUP
#include "test-fmodrem-ldbl-128ibm.c"
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