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* [Bug ports/13742] New: Use of fsincos is incorrect for large input on m68k
@ 2012-02-24 16:13 carlos at systemhalted dot org
2012-02-24 16:13 ` [Bug ports/13742] " carlos at systemhalted dot org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: carlos at systemhalted dot org @ 2012-02-24 16:13 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=13742
Bug #: 13742
Summary: Use of fsincos is incorrect for large input on m68k
Product: glibc
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: ports
AssignedTo: unassigned@sourceware.org
ReportedBy: carlos@systemhalted.org
CC: carlos@systemhalted.org, roland@gnu.org,
schwab@linux-m68k.org
Classification: Unclassified
Target: m68k-linux-gnu
This bug:
http://sourceware.org/bugzilla/show_bug.cgi?id=13658
Raises the question of the accuracy of hardware fsincos instructions for large
inputs.
It would appear that this bug, present on x86 and x86_64, would also effect
m68k since it uses a fsincos instruction with limited accuracy at high input
values.
A quick grep shows:
sysdeps/m68k/m680x0/fpu/s_csin.c: __asm ("fsincos%.x %2,%1:%0" : "=f"
(sin_rx), "=f" (cos_rx)
sysdeps/m68k/m680x0/fpu/bits/mathinline.h: __asm ("fsincos%.x %2,%1:%0"
\
sysdeps/m68k/m680x0/fpu/k_sin.c: __asm__ __volatile__ ("fsincosx %2,%0:%1" :
"=f" (cos_x), "=f" (sin_x)
sysdeps/m68k/m680x0/fpu/k_sin.c: __asm__ __volatile__ ("fsincosx %2,%0:%1" :
"=f" (cos_y), "=f" (sin_y)
sysdeps/m68k/m680x0/fpu/s_ccosh.c: __asm ("fsincos%.x %2,%1:%0" : "=f"
(sin_ix), "=f" (cos_ix)
sysdeps/m68k/m680x0/fpu/s_csinh.c: __asm ("fsincos%.x %2,%1:%0" : "=f"
(sin_ix), "=f" (cos_ix)
sysdeps/m68k/m680x0/fpu/k_cos.c: __asm__ __volatile__ ("fsincosx %2,%0:%1" :
"=f" (cos_x), "=f" (sin_x)
sysdeps/m68k/m680x0/fpu/k_cos.c: __asm__ __volatile__ ("fsincosx %2,%0:%1" :
"=f" (cos_y), "=f" (sin_y)
sysdeps/m68k/m680x0/fpu/s_cexp.c: __asm ("fsincos%.x %2,%1:%0" : "=f"
(sin_ix), "=f" (cos_ix)
A quick inspection does not show any input argument reduction.
The M68000PM/AD REV.1 states loss of accuracy if the input is > 10^20.
Therefore it seems to me that the m68k port also suffers the same problems as
x86 and x86_64.
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* [Bug ports/13742] Use of fsincos is incorrect for large input on m68k
2012-02-24 16:13 [Bug ports/13742] New: Use of fsincos is incorrect for large input on m68k carlos at systemhalted dot org
@ 2012-02-24 16:13 ` carlos at systemhalted dot org
2012-04-05 9:28 ` aj at suse dot de
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: carlos at systemhalted dot org @ 2012-02-24 16:13 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=13742
Carlos O'Donell <carlos at systemhalted dot org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |UNCONFIRMED
Ever Confirmed|1 |0
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* [Bug ports/13742] Use of fsincos is incorrect for large input on m68k
2012-02-24 16:13 [Bug ports/13742] New: Use of fsincos is incorrect for large input on m68k carlos at systemhalted dot org
2012-02-24 16:13 ` [Bug ports/13742] " carlos at systemhalted dot org
@ 2012-04-05 9:28 ` aj at suse dot de
2014-02-11 0:31 ` [Bug math/13742] [m68k] " jsm28 at gcc dot gnu.org
2014-06-26 15:15 ` fweimer at redhat dot com
3 siblings, 0 replies; 5+ messages in thread
From: aj at suse dot de @ 2012-04-05 9:28 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=13742
Andreas Jaeger <aj at suse dot de> changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at sourceware |schwab@linux-m68k.org
|dot org |
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* [Bug math/13742] [m68k] Use of fsincos is incorrect for large input on m68k
2012-02-24 16:13 [Bug ports/13742] New: Use of fsincos is incorrect for large input on m68k carlos at systemhalted dot org
2012-02-24 16:13 ` [Bug ports/13742] " carlos at systemhalted dot org
2012-04-05 9:28 ` aj at suse dot de
@ 2014-02-11 0:31 ` jsm28 at gcc dot gnu.org
2014-06-26 15:15 ` fweimer at redhat dot com
3 siblings, 0 replies; 5+ messages in thread
From: jsm28 at gcc dot gnu.org @ 2014-02-11 0:31 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=13742
Joseph Myers <jsm28 at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|ports |math
Host| |m68k-*-*
Summary|Use of fsincos is incorrect |[m68k] Use of fsincos is
|for large input on m68k |incorrect for large input
| |on m68k
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* [Bug math/13742] [m68k] Use of fsincos is incorrect for large input on m68k
2012-02-24 16:13 [Bug ports/13742] New: Use of fsincos is incorrect for large input on m68k carlos at systemhalted dot org
` (2 preceding siblings ...)
2014-02-11 0:31 ` [Bug math/13742] [m68k] " jsm28 at gcc dot gnu.org
@ 2014-06-26 15:15 ` fweimer at redhat dot com
3 siblings, 0 replies; 5+ messages in thread
From: fweimer at redhat dot com @ 2014-06-26 15:15 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=13742
Florian Weimer <fweimer at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Flags| |security-
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end of thread, other threads:[~2014-06-26 15:15 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2012-02-24 16:13 [Bug ports/13742] New: Use of fsincos is incorrect for large input on m68k carlos at systemhalted dot org
2012-02-24 16:13 ` [Bug ports/13742] " carlos at systemhalted dot org
2012-04-05 9:28 ` aj at suse dot de
2014-02-11 0:31 ` [Bug math/13742] [m68k] " jsm28 at gcc dot gnu.org
2014-06-26 15:15 ` fweimer at redhat dot com
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