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| author | Joseph Myers <joseph@codesourcery.com> | 2015-02-17 00:41:50 +0000 |
|---|---|---|
| committer | Joseph Myers <joseph@codesourcery.com> | 2015-02-17 00:41:50 +0000 |
| commit | ce8fc784e619ada624dc41ed7603211131e66573 (patch) | |
| tree | 2e004258c97eb26e6ec382879bcc6f442c2620fa /sysdeps/ieee754/ldbl-96 | |
| parent | 0d7036bdb189a1ecb4232101ff83c6dd72439545 (diff) | |
| download | glibc-ce8fc784e619ada624dc41ed7603211131e66573.tar.gz | |
Fix sign of remquo zero remainder in round-downward mode (bug 17987).
Various remquo implementations produce a zero remainder with the wrong
sign (a zero remainder should always have the sign of the first
argument, as specified in IEEE 754) in round-downward mode, resulting
from the sign of 0 - 0. This patch checks for zero results and fixes
their sign accordingly.
Tested for x86_64, x86, mips64 and powerpc.
[BZ #17987]
* sysdeps/ieee754/dbl-64/s_remquo.c (__remquo): Ensure sign of
zero result does not depend on the sign resulting from
subtraction.
* sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c (__remquo):
Likewise.
* sysdeps/ieee754/flt-32/s_remquof.c (__remquof): Likewise.
* sysdeps/ieee754/ldbl-128/s_remquol.c (__remquol): Likewise.
* sysdeps/ieee754/ldbl-128ibm/s_remquol.c (__remquol): Likewise.
* sysdeps/ieee754/ldbl-96/s_remquol.c (__remquol): Likewise.
* math/libm-test.inc (remquo_test_data): Add more tests.
Diffstat (limited to 'sysdeps/ieee754/ldbl-96')
| -rw-r--r-- | sysdeps/ieee754/ldbl-96/s_remquol.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/sysdeps/ieee754/ldbl-96/s_remquol.c b/sysdeps/ieee754/ldbl-96/s_remquol.c index 1462b54456..8d6b10ed61 100644 --- a/sysdeps/ieee754/ldbl-96/s_remquol.c +++ b/sysdeps/ieee754/ldbl-96/s_remquol.c @@ -101,6 +101,9 @@ __remquol (long double x, long double p, int *quo) *quo = qs ? -cquo : cquo; + /* Ensure correct sign of zero result in round-downward mode. */ + if (x == 0.0L) + x = 0.0L; if (sx) x = -x; return x; |