From: David S. Miller <davem@davemloft.net>
Date: Fri, 16 Nov 2012 17:31:38 +0000 (-0800)
Subject: Don't generate underflow for very small values in log1pl.
X-Git-Tag: upstream/2.20~2954
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=447885ebf1c1fc8adf4084f5e2708ff84d0da43b;p=platform%2Fupstream%2Flinaro-glibc.git

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.
---

diff --git a/ChangeLog b/ChangeLog
index 8b980c1..64378be 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2012-11-16  David S. Miller  <davem@davemloft.net>
+
+	* 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  <hongjiu.lu@intel.com>
 
 	* 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 */