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* [Bug c/52138] New: Operations on complex values are not inlined, even with -O3
@ 2012-02-06 18:20 gonnet at maths dot ox.ac.uk
2012-02-06 18:26 ` [Bug c/52138] " jakub at gcc dot gnu.org
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: gonnet at maths dot ox.ac.uk @ 2012-02-06 18:20 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52138
Bug #: 52138
Summary: Operations on complex values are not inlined, even
with -O3
Classification: Unclassified
Product: gcc
Version: 4.5.2
Status: UNCONFIRMED
Severity: major
Priority: P3
Component: c
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: gonnet@maths.ox.ac.uk
Irrespective of the optimization level selected, multiplying or dividing two
complex doubles generates a call to __muldc3 or __divdc3 respectively.
Using the "-fcx-limited-range" flag inlines the operations, but then the range
may be limited.
Strangely enough, in the gfortran frontend, complex arithmetic is inlined even
with no optimization (-O0).
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c/52138] Operations on complex values are not inlined, even with -O3
2012-02-06 18:20 [Bug c/52138] New: Operations on complex values are not inlined, even with -O3 gonnet at maths dot ox.ac.uk
@ 2012-02-06 18:26 ` jakub at gcc dot gnu.org
2012-02-06 18:33 ` gonnet at maths dot ox.ac.uk
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: jakub at gcc dot gnu.org @ 2012-02-06 18:26 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52138
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jakub at gcc dot gnu.org
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-02-06 18:25:47 UTC ---
Why do you think inlining a ~ 750B long routine would be beneficial? Note that
if one of the operands has 0 either the imaginary or real part, gcc will inline
it.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c/52138] Operations on complex values are not inlined, even with -O3
2012-02-06 18:20 [Bug c/52138] New: Operations on complex values are not inlined, even with -O3 gonnet at maths dot ox.ac.uk
2012-02-06 18:26 ` [Bug c/52138] " jakub at gcc dot gnu.org
@ 2012-02-06 18:33 ` gonnet at maths dot ox.ac.uk
2012-02-06 18:51 ` kargl at gcc dot gnu.org
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: gonnet at maths dot ox.ac.uk @ 2012-02-06 18:33 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52138
--- Comment #2 from Pedro <gonnet at maths dot ox.ac.uk> 2012-02-06 18:33:11 UTC ---
I'm a bit confused... In the gfortran output the multiplication only about 40
bytes. Does that mean that gfortran is using a reduced range by default?
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c/52138] Operations on complex values are not inlined, even with -O3
2012-02-06 18:20 [Bug c/52138] New: Operations on complex values are not inlined, even with -O3 gonnet at maths dot ox.ac.uk
2012-02-06 18:26 ` [Bug c/52138] " jakub at gcc dot gnu.org
2012-02-06 18:33 ` gonnet at maths dot ox.ac.uk
@ 2012-02-06 18:51 ` kargl at gcc dot gnu.org
2012-02-06 18:58 ` dominiq at lps dot ens.fr
2012-02-06 19:29 ` pinskia at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: kargl at gcc dot gnu.org @ 2012-02-06 18:51 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52138
kargl at gcc dot gnu.org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |kargl at gcc dot gnu.org
--- Comment #3 from kargl at gcc dot gnu.org 2012-02-06 18:50:41 UTC ---
(In reply to comment #2)
> I'm a bit confused... In the gfortran output the multiplication only about 40
> bytes. Does that mean that gfortran is using a reduced range by default?
>From gcc/toplev.c
/* With -fcx-limited-range, we do cheap and quick complex arithmetic. */
if (flag_cx_limited_range)
flag_complex_method = 0;
/* With -fcx-fortran-rules, we do something in-between cheap and C99. */
if (flag_cx_fortran_rules)
flag_complex_method = 1;
So, yes, gfortran does something different than gcc.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c/52138] Operations on complex values are not inlined, even with -O3
2012-02-06 18:20 [Bug c/52138] New: Operations on complex values are not inlined, even with -O3 gonnet at maths dot ox.ac.uk
` (2 preceding siblings ...)
2012-02-06 18:51 ` kargl at gcc dot gnu.org
@ 2012-02-06 18:58 ` dominiq at lps dot ens.fr
2012-02-06 19:29 ` pinskia at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: dominiq at lps dot ens.fr @ 2012-02-06 18:58 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52138
--- Comment #4 from Dominique d'Humieres <dominiq at lps dot ens.fr> 2012-02-06 18:58:00 UTC ---
>From the manual:
-fcx-limited-range
When enabled, this option states that a range reduction step is not needed when
performing complex division. Also, there is no checking whether the result of a
complex multiplication or division is NaN + I*NaN, with an attempt to rescue
the situation in that case. The default is -fno-cx-limited-range, but is
enabled by -ffast-math.
This option controls the default setting of the ISO C99 CX_LIMITED_RANGE
pragma. Nevertheless, the option applies to all languages.
-fcx-fortran-rules
Complex multiplication and division follow Fortran rules. Range reduction is
done as part of complex division, but there is no checking whether the result
of a complex multiplication or division is NaN + I*NaN, with an attempt to
rescue the situation in that case.
The default is -fno-cx-fortran-rules.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c/52138] Operations on complex values are not inlined, even with -O3
2012-02-06 18:20 [Bug c/52138] New: Operations on complex values are not inlined, even with -O3 gonnet at maths dot ox.ac.uk
` (3 preceding siblings ...)
2012-02-06 18:58 ` dominiq at lps dot ens.fr
@ 2012-02-06 19:29 ` pinskia at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2012-02-06 19:29 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52138
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution| |INVALID
--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-02-06 19:28:41 UTC ---
This is invalid as mentioned above.
^ permalink raw reply [flat|nested] 6+ messages in thread
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2012-02-06 18:20 [Bug c/52138] New: Operations on complex values are not inlined, even with -O3 gonnet at maths dot ox.ac.uk
2012-02-06 18:26 ` [Bug c/52138] " jakub at gcc dot gnu.org
2012-02-06 18:33 ` gonnet at maths dot ox.ac.uk
2012-02-06 18:51 ` kargl at gcc dot gnu.org
2012-02-06 18:58 ` dominiq at lps dot ens.fr
2012-02-06 19:29 ` pinskia at gcc dot gnu.org
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