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* [Bug math/14638] New: fma produced wrong results for (0 * -1.0) + -0.0
@ 2012-09-27 20:45 law at redhat dot com
2012-09-29 18:34 ` [Bug math/14638] " jsm28 at gcc dot gnu.org
2014-06-17 4:17 ` fweimer at redhat dot com
0 siblings, 2 replies; 3+ messages in thread
From: law at redhat dot com @ 2012-09-27 20:45 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=14638
Bug #: 14638
Summary: fma produced wrong results for (0 * -1.0) + -0.0
Product: glibc
Version: 2.17
Status: NEW
Severity: normal
Priority: P2
Component: math
AssignedTo: unassigned@sourceware.org
ReportedBy: law@redhat.com
Classification: Unclassified
The FMA implementation in sysdeps/ieee754/dbl-64/s_fma.c produces the wrong
result for this program when run on a x86_64 box that doesn't have fma3/fma4
support.
#include <assert.h>
#include <math.h>
#include <stdlib.h>
int main (void) {
double f1 = 0.0f;
double f2 = -1.0f;
double f3 = -0.0f;
double dresult = fma (f1, f2, f3);
if (! signbit (dresult))
abort ();
exit (0);
}
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* [Bug math/14638] fma produced wrong results for (0 * -1.0) + -0.0
2012-09-27 20:45 [Bug math/14638] New: fma produced wrong results for (0 * -1.0) + -0.0 law at redhat dot com
@ 2012-09-29 18:34 ` jsm28 at gcc dot gnu.org
2014-06-17 4:17 ` fweimer at redhat dot com
1 sibling, 0 replies; 3+ messages in thread
From: jsm28 at gcc dot gnu.org @ 2012-09-29 18:34 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=14638
Joseph Myers <jsm28 at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |FIXED
--- Comment #1 from Joseph Myers <jsm28 at gcc dot gnu.org> 2012-09-29 18:34:30 UTC ---
Fixed for 2.17 by:
commit 8ec5b01346114da38e806ca1867da688d3a360e2
Author: Joseph Myers <joseph@codesourcery.com>
Date: Sat Sep 29 18:31:54 2012 +0000
Fix sign of exact zero return from fma (bug 14638).
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* [Bug math/14638] fma produced wrong results for (0 * -1.0) + -0.0
2012-09-27 20:45 [Bug math/14638] New: fma produced wrong results for (0 * -1.0) + -0.0 law at redhat dot com
2012-09-29 18:34 ` [Bug math/14638] " jsm28 at gcc dot gnu.org
@ 2014-06-17 4:17 ` fweimer at redhat dot com
1 sibling, 0 replies; 3+ messages in thread
From: fweimer at redhat dot com @ 2014-06-17 4:17 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=14638
Florian Weimer <fweimer at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Flags| |security-
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2012-09-27 20:45 [Bug math/14638] New: fma produced wrong results for (0 * -1.0) + -0.0 law at redhat dot com
2012-09-29 18:34 ` [Bug math/14638] " jsm28 at gcc dot gnu.org
2014-06-17 4:17 ` fweimer at redhat dot com
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