S390: Fix fp comparison not raising FE_INVALID.

As gcc is using unordered comparison instructions which do not
raise invalid exception if any operand is quiet NAN,
FIX_COMPARE_INVALID is defined to 1.
Thus iseqsig is calling feraiseexcept as workaround.

2 files changed, 40 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 06a7338..3c328b2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2016-10-17  Stefan Liebler  <stli@linux.vnet.ibm.com>
+
+	* sysdeps/s390/fpu/fix-fp-int-compare-invalid.h: New file.
+
 2016-09-22  John David Anglin  <dave.anglin@bell.net>
 
 	* sysdeps/unix/sysv/linux/hppa/atomic-machine.h: Don't include
diff --git a/sysdeps/s390/fpu/fix-fp-int-compare-invalid.h b/sysdeps/s390/fpu/fix-fp-int-compare-invalid.h
new file mode 100644
index 0000000..c4c119f
--- /dev/null
+++ b/sysdeps/s390/fpu/fix-fp-int-compare-invalid.h
@@ -0,0 +1,36 @@
+/* Fix for missing "invalid" exceptions from floating-point
+   comparisons.  s390 version.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   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, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef FIX_FP_INT_COMPARE_INVALID_H
+#define FIX_FP_INT_COMPARE_INVALID_H	1
+
+/* GCC uses unordered comparison instructions like cebr (Short BFP COMPARE)
+   when it should use ordered comparison instructions like kebr
+   (Short BFP COMPARE AND SIGNAL) in order to raise invalid exceptions if
+   any operand is quiet (or signaling) NAN. See gcc bugzilla:
+   <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77918>.
+   There exists an equivalent gcc bugzilla for Intel:
+   <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52451>.
+   Once the s390 gcc bug is fixed, the definition of FIX_COMPARE_INVALID
+   should have a __GNUC_PREREQ conditional added so that e.g. the workaround
+   to call feraiseexcept (FE_INVALID) in math/s_iseqsig_template.c can be
+   avoided.  */
+#define FIX_COMPARE_INVALID 1
+
+#endif /* fix-fp-int-compare-invalid.h */