From 447885ebf1c1fc8adf4084f5e2708ff84d0da43b Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Fri, 16 Nov 2012 09:31:38 -0800 Subject: [PATCH] Don't generate underflow for very small values in log1pl. * sysdeps/ieee754/ldbl-128/s_log1pl.c (__log1pl): If xm1 is smaller than LDBL_EPSILON/2.0L, just return xm1. --- ChangeLog | 5 +++++ sysdeps/ieee754/ldbl-128/s_log1pl.c | 6 ++++++ 2 files changed, 11 insertions(+) diff --git a/ChangeLog b/ChangeLog index 8b980c1..64378be 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,8 @@ +2012-11-16 David S. Miller + + * sysdeps/ieee754/ldbl-128/s_log1pl.c (__log1pl): If xm1 is + smaller than LDBL_EPSILON/2.0L, just return xm1. + 2012-11-16 H.J. Lu * elf/tst-array1.c (init): Set constructor priority to 1000. diff --git a/sysdeps/ieee754/ldbl-128/s_log1pl.c b/sysdeps/ieee754/ldbl-128/s_log1pl.c index 4ecea0f..fad18e9 100644 --- a/sysdeps/ieee754/ldbl-128/s_log1pl.c +++ b/sysdeps/ieee754/ldbl-128/s_log1pl.c @@ -138,6 +138,12 @@ __log1pl (long double xm1) && (u.parts32.w1 | u.parts32.w2 | u.parts32.w3) == 0) return xm1; + if ((hx & 0x7fffffff) < 0x3f8e0000) + { + if ((int) xm1 == 0) + return xm1; + } + x = xm1 + 1.0L; /* log1p(-1) = -inf */ -- 2.7.4