From 7b428e744b1ae62c8f26b4e1db487230b796c984 Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Fri, 19 Feb 2016 17:19:53 +0000 Subject: [PATCH] Fix ldbl-128ibm nextafterl, nexttowardl sign of zero result (bug 19678). The ldbl-128ibm implementation of nextafterl / nexttowardl returns -0 in FE_DOWNWARD mode when taking the next value below the least positive subnormal, when it should return +0. This patch fixes it to check explicitly for this case. Tested for powerpc. [BZ #19678] * sysdeps/ieee754/ldbl-128ibm/s_nextafterl.c (__nextafterl): Ensure +0.0 is returned when taking the next value below the least positive value. --- ChangeLog | 7 +++++++ sysdeps/ieee754/ldbl-128ibm/s_nextafterl.c | 3 +++ 2 files changed, 10 insertions(+) diff --git a/ChangeLog b/ChangeLog index bad618941c..5f42093e35 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,10 @@ +2016-02-19 Joseph Myers + + [BZ #19678] + * sysdeps/ieee754/ldbl-128ibm/s_nextafterl.c (__nextafterl): + Ensure +0.0 is returned when taking the next value below the least + positive value. + 2016-02-19 Florian Weimer * sysdeps/generic/malloc-machine.h: Assume mutex_init is always diff --git a/sysdeps/ieee754/ldbl-128ibm/s_nextafterl.c b/sysdeps/ieee754/ldbl-128ibm/s_nextafterl.c index 515aa1ef5b..0d6469d548 100644 --- a/sysdeps/ieee754/ldbl-128ibm/s_nextafterl.c +++ b/sysdeps/ieee754/ldbl-128ibm/s_nextafterl.c @@ -87,6 +87,9 @@ long double __nextafterl(long double x, long double y) math_force_eval (u); /* raise underflow flag */ __set_errno (ERANGE); } + /* Avoid returning -0 in FE_DOWNWARD mode. */ + if (x == 0.0L) + return 0.0L; return x; } /* If the high double is an exact power of two and the low