Check for finite/infinity parms in IBM Long Double 128 fmal( )

This patch addresses some IBM Long Double 128 fmal () test-ldouble.out
and test-ildoubl.out failures.  If the ‘x’ and ‘y’ parameters are
finite values and ‘z’ is infinity, the result of fmal () should be ‘z’
not NaN.

2 files changed, 44 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 3c29d6ba1c..f77f1714a0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2011-08-18  David Flaherty  <flaherty@linux.vnet.ibm.com>
+
+	* sysdeps/ieee754/ldbl-128ibm/s_fmal.c: New file which checks
+	for finite and infinity parameters.
+
 2011-08-04  Will Schmidt  <will_schmidt@vnet.ibm.com>
 
 	* sysdeps/powerpc/powerpc32/power7/strncmp.S: Adjust the alignment
diff --git a/sysdeps/ieee754/ldbl-128ibm/s_fmal.c b/sysdeps/ieee754/ldbl-128ibm/s_fmal.c
new file mode 100644
index 0000000000..e59d2c349f
--- /dev/null
+++ b/sysdeps/ieee754/ldbl-128ibm/s_fmal.c
@@ -0,0 +1,39 @@
+/* Compute x * y + z as ternary operation.
+   Copyright (C) 2011 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by David Flaherty <flaherty@linux.vnet.ibm.com>.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <math.h>
+#include <math_ldbl_opt.h>
+
+long double
+__fmal (long double x, long double y, long double z)
+{
+	/* An IBM long double 128 is really just 2 IEEE64 doubles, and in
+	 * the case of inf/nan only the first double counts. So we use the
+	 * (double) cast to avoid any data movement.   */
+       if ((finite ((double)x) && finite ((double)y)) && isinf ((double)z))
+               return (z);
+
+       return (x * y) + z;
+}
+#ifdef IS_IN_libm
+long_double_symbol (libm, __fmal, fmal);
+#else
+long_double_symbol (libc, __fmal, fmal);
+#endif