Fix powl inaccuracy for ldbl-128ibm (bug 14914).

3 files changed, 15 insertions, 8 deletions

diff --git a/ChangeLog b/ChangeLog
index cab8d1b..3338301 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 744df37..24f6302 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 8216c49..8bd35d0 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;