PowerPC: Fix nearbyintl failure for few inputs

This patch fixes few failures in nearbyintl() where the fraction part is
close to 0.5.i  The new tests added report few extra failures in
nearbyint_downward and nearbyint_towardzero which is a known issue.

Fixes #17031.

4 files changed, 23 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index 9ebf711103..2c554fae8e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2014-16-17  Rajalakshmi Srinivasaraghavan <raji@linux.vnet.ibm.com>
+
+	[BZ #17031]
+	* sysdeps/ieee754/ldbl-128ibm/s_nearbyintl.c: Consider the low
+	double, adjusted for any remainder from the high double.
+	* math/libm-test.inc (nearbyint): Add tests.
+	(rint): Likewise.
+
 2014-06-17  Adhemerval Zanella  <azanella@linux.vnet.ibm.com>
 
 	* nptl/sysdeps/powerpc/Makefile: Moved ...
diff --git a/NEWS b/NEWS
index 0ba83dcaa7..d90acbf2d0 100644
--- a/NEWS
+++ b/NEWS
@@ -19,7 +19,8 @@ Version 2.20
   16791, 16796, 16799, 16800, 16815, 16823, 16824, 16831, 16838, 16849,
   16854, 16876, 16877, 16878, 16882, 16885, 16888, 16890, 16912, 16915,
   16916, 16917, 16922, 16927, 16928, 16932, 16943, 16958, 16965, 16966,
-  16967, 16977, 16978, 16984, 16990, 16996, 17009, 17042, 17048, 17058.
+  16967, 16977, 16978, 16984, 16990, 16996, 17009, 17031, 17042, 17048,
+  17058.
 
 * The minimum Linux kernel version that this version of the GNU C Library
   can be used with is 2.6.32.
diff --git a/math/libm-test.inc b/math/libm-test.inc
index fa8e2385dc..d98d85c715 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -8188,6 +8188,10 @@ static const struct test_f_f_data nearbyint_test_data[] =
     TEST_f_f (nearbyint, 4503599627370496.75L, 4503599627370496.0L, NO_INEXACT_EXCEPTION, 4503599627370497.0L, NO_INEXACT_EXCEPTION, 4503599627370496.0L, NO_INEXACT_EXCEPTION, 4503599627370497.0L, NO_INEXACT_EXCEPTION),
     TEST_f_f (nearbyint, 4503599627370497.5L, 4503599627370497.0L, NO_INEXACT_EXCEPTION, 4503599627370498.0L, NO_INEXACT_EXCEPTION, 4503599627370497.0L, NO_INEXACT_EXCEPTION, 4503599627370498.0L, NO_INEXACT_EXCEPTION),
 # if LDBL_MANT_DIG > 100
+    TEST_f_f (nearbyint, 1024.5000000000001L, 1024.0L, NO_INEXACT_EXCEPTION, 1025.0L, NO_INEXACT_EXCEPTION, 1024.0L, NO_INEXACT_EXCEPTION, 1025.0L, NO_INEXACT_EXCEPTION),
+    TEST_f_f (nearbyint, 1025.5000000000001L, 1025.0L, NO_INEXACT_EXCEPTION, 1026.0L, NO_INEXACT_EXCEPTION, 1025.0L, NO_INEXACT_EXCEPTION, 1026.0L, NO_INEXACT_EXCEPTION),
+    TEST_f_f (nearbyint, -1024.5000000000001L, -1025.0L, NO_INEXACT_EXCEPTION, -1025.0L, NO_INEXACT_EXCEPTION, -1024.0L, NO_INEXACT_EXCEPTION, -1024.0L, NO_INEXACT_EXCEPTION),
+    TEST_f_f (nearbyint, -1025.5000000000001L, -1026.0L, NO_INEXACT_EXCEPTION, -1026.0L, NO_INEXACT_EXCEPTION, -1025.0L, NO_INEXACT_EXCEPTION, -1025.0L, NO_INEXACT_EXCEPTION),
     TEST_f_f (nearbyint, 4503599627370494.5000000000001L, 4503599627370494.0L, NO_INEXACT_EXCEPTION, 4503599627370495.0L, NO_INEXACT_EXCEPTION, 4503599627370494.0L, NO_INEXACT_EXCEPTION, 4503599627370495.0L, NO_INEXACT_EXCEPTION),
     TEST_f_f (nearbyint, 4503599627370495.5000000000001L, 4503599627370495.0L, NO_INEXACT_EXCEPTION, 4503599627370496.0L, NO_INEXACT_EXCEPTION, 4503599627370495.0L, NO_INEXACT_EXCEPTION, 4503599627370496.0L, NO_INEXACT_EXCEPTION),
     TEST_f_f (nearbyint, 4503599627370496.5000000000001L, 4503599627370496.0L, NO_INEXACT_EXCEPTION, 4503599627370497.0L, NO_INEXACT_EXCEPTION, 4503599627370496.0L, NO_INEXACT_EXCEPTION, 4503599627370497.0L, NO_INEXACT_EXCEPTION),
@@ -8890,6 +8894,10 @@ static const struct test_f_f_data rint_test_data[] =
     TEST_f_f (rint, 4503599627370496.75L, 4503599627370496.0L, INEXACT_EXCEPTION, 4503599627370497.0L, INEXACT_EXCEPTION, 4503599627370496.0L, INEXACT_EXCEPTION, 4503599627370497.0L, INEXACT_EXCEPTION),
     TEST_f_f (rint, 4503599627370497.5L, 4503599627370497.0L, INEXACT_EXCEPTION, 4503599627370498.0L, INEXACT_EXCEPTION, 4503599627370497.0L, INEXACT_EXCEPTION, 4503599627370498.0L, INEXACT_EXCEPTION),
 # if LDBL_MANT_DIG > 100
+    TEST_f_f (rint, 1024.5000000000001L, 1024.0L, INEXACT_EXCEPTION, 1025.0L, INEXACT_EXCEPTION, 1024.0L, INEXACT_EXCEPTION, 1025.0L, INEXACT_EXCEPTION),
+    TEST_f_f (rint, 1025.5000000000001L, 1025.0L, INEXACT_EXCEPTION, 1026.0L, INEXACT_EXCEPTION, 1025.0L, INEXACT_EXCEPTION, 1026.0L, INEXACT_EXCEPTION),
+    TEST_f_f (rint, -1024.5000000000001L, -1025.0L, INEXACT_EXCEPTION, -1025.0L, INEXACT_EXCEPTION, -1024.0L, INEXACT_EXCEPTION, -1024.0L, INEXACT_EXCEPTION),
+    TEST_f_f (rint, -1025.5000000000001L, -1026.0L, INEXACT_EXCEPTION, -1026.0L, INEXACT_EXCEPTION, -1025.0L, INEXACT_EXCEPTION, -1025.0L, INEXACT_EXCEPTION),
     TEST_f_f (rint, 4503599627370494.5000000000001L, 4503599627370494.0L, INEXACT_EXCEPTION, 4503599627370495.0L, INEXACT_EXCEPTION, 4503599627370494.0L, INEXACT_EXCEPTION, 4503599627370495.0L, INEXACT_EXCEPTION),
     TEST_f_f (rint, 4503599627370495.5000000000001L, 4503599627370495.0L, INEXACT_EXCEPTION, 4503599627370496.0L, INEXACT_EXCEPTION, 4503599627370495.0L, INEXACT_EXCEPTION, 4503599627370496.0L, INEXACT_EXCEPTION),
     TEST_f_f (rint, 4503599627370496.5000000000001L, 4503599627370496.0L, INEXACT_EXCEPTION, 4503599627370497.0L, INEXACT_EXCEPTION, 4503599627370496.0L, INEXACT_EXCEPTION, 4503599627370497.0L, INEXACT_EXCEPTION),
diff --git a/sysdeps/ieee754/ldbl-128ibm/s_nearbyintl.c b/sysdeps/ieee754/ldbl-128ibm/s_nearbyintl.c
index 4e997a68f9..8f34604f54 100644
--- a/sysdeps/ieee754/ldbl-128ibm/s_nearbyintl.c
+++ b/sysdeps/ieee754/ldbl-128ibm/s_nearbyintl.c
@@ -38,6 +38,7 @@ __nearbyintl (long double x)
 
   if (fabs (u.d[0].d) < TWO52)
     {
+      double xh = u.d[0].d;
       double high = u.d[0].d;
       feholdexcept (&env);
       if (high > 0.0)
@@ -52,6 +53,10 @@ __nearbyintl (long double x)
 	  high += TWO52;
           if (high == 0.0) high = -0.0;
 	}
+      if (u.d[1].d > 0.0 && (xh - high == 0.5))
+        high += 1.0;
+      else if (u.d[1].d < 0.0 && (-(xh - high) == 0.5))
+        high -= 1.0;
       u.d[0].d = high;
       u.d[1].d = 0.0;
       math_force_eval (u.d[0]);