* [PATCH] S390: Fix fp comparison not raising FE_INVALID.
@ 2016-10-10 12:00 Stefan Liebler
2016-10-17 8:39 ` Stefan Liebler
0 siblings, 1 reply; 2+ messages in thread
From: Stefan Liebler @ 2016-10-10 12:00 UTC (permalink / raw)
To: libc-alpha
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Hi,
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.
ChangeLog:
* sysdeps/s390/fpu/fix-fp-int-compare-invalid.h: New file.
[-- Attachment #2: 20161010_iseqsig_invalid_exception.patch --]
[-- Type: text/x-patch, Size: 2485 bytes --]
commit 2aa18f963deed0ae455b00b75e773a2972fe2071
Author: Stefan Liebler <stli@linux.vnet.ibm.com>
Date: Mon Oct 10 08:35:54 2016 +0200
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.
ChangeLog:
* sysdeps/s390/fpu/fix-fp-int-compare-invalid.h: New file.
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 */
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] S390: Fix fp comparison not raising FE_INVALID.
2016-10-10 12:00 [PATCH] S390: Fix fp comparison not raising FE_INVALID Stefan Liebler
@ 2016-10-17 8:39 ` Stefan Liebler
0 siblings, 0 replies; 2+ messages in thread
From: Stefan Liebler @ 2016-10-17 8:39 UTC (permalink / raw)
To: libc-alpha
Committed.
On 10/10/2016 01:59 PM, Stefan Liebler wrote:
> Hi,
>
> 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.
>
> ChangeLog:
>
> * sysdeps/s390/fpu/fix-fp-int-compare-invalid.h: New file.
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