From b3b099af0356831530f553934cdd90716137b1a3 Mon Sep 17 00:00:00 2001
From: Joseph Myers <joseph@codesourcery.com>
Date: Tue, 4 Dec 2012 14:39:24 +0000
Subject: [PATCH] Fix powl inaccuracy for ldbl-128ibm (bug 14914).

---
 ChangeLog                            |  7 +++++++
 NEWS                                 |  2 +-
 sysdeps/ieee754/ldbl-128ibm/e_powl.c | 14 +++++++-------
 3 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index cab8d1bb29..3338301a2e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2012-12-04  Joseph Myers  <joseph@codesourcery.com>
+
+	[BZ #14914]
+	* sysdeps/ieee754/ldbl-128ibm/e_powl.c (__ieee754_powl): Clear
+	whole low double instead of just low 47 bits when splitting values
+	into two parts.
+
 2012-12-03  Allan McRae  <allan@archlinux.org>
 
 	* manual/stdio.texi (Predefined Printf Handlers): Remove
diff --git a/NEWS b/NEWS
index 744df37833..24f6302dfa 100644
--- a/NEWS
+++ b/NEWS
@@ -22,7 +22,7 @@ Version 2.17
   14661, 14669, 14672, 14683, 14694, 14716, 14719, 14743, 14767, 14783,
   14784, 14785, 14793, 14796, 14797, 14801, 14803, 14805, 14807, 14811,
   14815, 14821, 14822, 14824, 14828, 14831, 14835, 14838, 14856, 14863,
-  14865, 14866, 14868, 14869, 14871, 14879, 14889, 14893.
+  14865, 14866, 14868, 14869, 14871, 14879, 14889, 14893, 14914.
 
 * CVE-2011-4609 svc_run() produces high cpu usage when accept fails with
   EMFILE has been fixed (Bugzilla #14889).
diff --git a/sysdeps/ieee754/ldbl-128ibm/e_powl.c b/sysdeps/ieee754/ldbl-128ibm/e_powl.c
index 8216c4906b..8bd35d0c88 100644
--- a/sysdeps/ieee754/ldbl-128ibm/e_powl.c
+++ b/sysdeps/ieee754/ldbl-128ibm/e_powl.c
@@ -324,13 +324,13 @@ __ieee754_powl (long double x, long double y)
 
   o.value = s_h;
   o.parts32.w3 = 0;
-  o.parts32.w2 &= 0xffff8000;
+  o.parts32.w2 = 0;
   s_h = o.value;
   /* t_h=ax+bp[k] High */
   t_h = ax + bp[k];
   o.value = t_h;
   o.parts32.w3 = 0;
-  o.parts32.w2 &= 0xffff8000;
+  o.parts32.w2 = 0;
   t_h = o.value;
   t_l = ax - (t_h - bp[k]);
   s_l = v * ((u - s_h * t_h) - s_h * t_l);
@@ -344,7 +344,7 @@ __ieee754_powl (long double x, long double y)
   t_h = 3.0 + s2 + r;
   o.value = t_h;
   o.parts32.w3 = 0;
-  o.parts32.w2 &= 0xffff8000;
+  o.parts32.w2 = 0;
   t_h = o.value;
   t_l = r - ((t_h - 3.0) - s2);
   /* u+v = s*(1+...) */
@@ -354,7 +354,7 @@ __ieee754_powl (long double x, long double y)
   p_h = u + v;
   o.value = p_h;
   o.parts32.w3 = 0;
-  o.parts32.w2 &= 0xffff8000;
+  o.parts32.w2 = 0;
   p_h = o.value;
   p_l = v - (p_h - u);
   z_h = cp_h * p_h;		/* cp_h+cp_l = 2/(3*log2) */
@@ -364,7 +364,7 @@ __ieee754_powl (long double x, long double y)
   t1 = (((z_h + z_l) + dp_h[k]) + t);
   o.value = t1;
   o.parts32.w3 = 0;
-  o.parts32.w2 &= 0xffff8000;
+  o.parts32.w2 = 0;
   t1 = o.value;
   t2 = z_l - (((t1 - t) - dp_h[k]) - z_h);
 
@@ -377,7 +377,7 @@ __ieee754_powl (long double x, long double y)
   y1 = y;
   o.value = y1;
   o.parts32.w3 = 0;
-  o.parts32.w2 &= 0xffff8000;
+  o.parts32.w2 = 0;
   y1 = o.value;
   p_l = (y - y1) * t1 + y * t2;
   p_h = y1 * t1;
@@ -421,7 +421,7 @@ __ieee754_powl (long double x, long double y)
   t = p_l + p_h;
   o.value = t;
   o.parts32.w3 = 0;
-  o.parts32.w2 &= 0xffff8000;
+  o.parts32.w2 = 0;
   t = o.value;
   u = t * lg2_h;
   v = (p_l - (t - p_h)) * lg2 + t * lg2_l;