diff options
| 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/dbl-64 | |
| parent | 0d7036bdb189a1ecb4232101ff83c6dd72439545 (diff) | |
| download | glibc-ce8fc784e619ada624dc41ed7603211131e66573.tar.gz glibc-ce8fc784e619ada624dc41ed7603211131e66573.tar.xz glibc-ce8fc784e619ada624dc41ed7603211131e66573.zip | |
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/dbl-64')
| -rw-r--r-- | sysdeps/ieee754/dbl-64/s_remquo.c | 3 | ||||
| -rw-r--r-- | sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c | 3 |
2 files changed, 6 insertions, 0 deletions
diff --git a/sysdeps/ieee754/dbl-64/s_remquo.c b/sysdeps/ieee754/dbl-64/s_remquo.c index e07efa89f8..b081d26b0d 100644 --- a/sysdeps/ieee754/dbl-64/s_remquo.c +++ b/sysdeps/ieee754/dbl-64/s_remquo.c @@ -101,6 +101,9 @@ __remquo (double x, double y, int *quo) *quo = qs ? -cquo : cquo; + /* Ensure correct sign of zero result in round-downward mode. */ + if (x == 0.0) + x = 0.0; if (sx) x = -x; return x; diff --git a/sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c b/sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c index ab561780c8..304e9d0fb4 100644 --- a/sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c +++ b/sysdeps/ieee754/dbl-64/wordsize-64/s_remquo.c @@ -100,6 +100,9 @@ __remquo (double x, double y, int *quo) *quo = qs ? -cquo : cquo; + /* Ensure correct sign of zero result in round-downward mode. */ + if (x == 0.0) + x = 0.0; if (sx) x = -x; return x; |