From 447885ebf1c1fc8adf4084f5e2708ff84d0da43b Mon Sep 17 00:00:00 2001
From: "David S. Miller" <davem@davemloft.net>
Date: Fri, 16 Nov 2012 09:31:38 -0800
Subject: 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.
---
 sysdeps/ieee754/ldbl-128/s_log1pl.c | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'sysdeps/ieee754')

diff --git a/sysdeps/ieee754/ldbl-128/s_log1pl.c b/sysdeps/ieee754/ldbl-128/s_log1pl.c
index 4ecea0fddd..fad18e9da2 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 */
-- 
cgit 1.4.1