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* [Bug c++/35386] New: Invalid vector code generated with -O2
@ 2008-02-26 23:11 kes at smolek dot com
2008-02-26 23:18 ` [Bug c++/35386] " kes at smolek dot com
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: kes at smolek dot com @ 2008-02-26 23:11 UTC (permalink / raw)
To: gcc-bugs
A simple vector addition loop fails to generate any addition code when -O2
optimization is used; the loop is essentially empty.
--
Summary: Invalid vector code generated with -O2
Product: gcc
Version: 4.2.3
Status: UNCONFIRMED
Severity: major
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: kes at smolek dot com
GCC build triplet: x86_64-unknown-linux-gnu
GCC host triplet: x86_64-unknown-linux-gnu
GCC target triplet: x86_64-unknown-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35386
^ permalink raw reply [flat|nested] 5+ messages in thread* [Bug c++/35386] Invalid vector code generated with -O2 2008-02-26 23:11 [Bug c++/35386] New: Invalid vector code generated with -O2 kes at smolek dot com @ 2008-02-26 23:18 ` kes at smolek dot com 2008-02-26 23:21 ` pinskia at gcc dot gnu dot org ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: kes at smolek dot com @ 2008-02-26 23:18 UTC (permalink / raw) To: gcc-bugs ------- Comment #1 from kes at smolek dot com 2008-02-26 23:17 ------- Created an attachment (id=15234) --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=15234&action=view) temp file output demonstrating the bug Command line: gcc -v -save-temps -O2 -S -msse3 ComputeEven.cpp Note: bug occurs on 4.2.1, 4.2.2; 4.1.2 works okay. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35386 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/35386] Invalid vector code generated with -O2 2008-02-26 23:11 [Bug c++/35386] New: Invalid vector code generated with -O2 kes at smolek dot com 2008-02-26 23:18 ` [Bug c++/35386] " kes at smolek dot com @ 2008-02-26 23:21 ` pinskia at gcc dot gnu dot org 2008-02-27 1:51 ` kes at smolek dot com 2008-02-27 2:00 ` pinskia at gcc dot gnu dot org 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu dot org @ 2008-02-26 23:21 UTC (permalink / raw) To: gcc-bugs ------- Comment #2 from pinskia at gcc dot gnu dot org 2008-02-26 23:20 ------- You are violating C/C++ aliasing rules: typedef float v4sf __attribute__ ((vector_size(16))); v4sf vSum; complex<float> *vp = (complex<float> *) &vSum; ... spectra[4*j] = vp[0]; spectra[4*j+2] = vp[1]; -- pinskia at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- Severity|major |normal Status|UNCONFIRMED |RESOLVED Resolution| |INVALID http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35386 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/35386] Invalid vector code generated with -O2 2008-02-26 23:11 [Bug c++/35386] New: Invalid vector code generated with -O2 kes at smolek dot com 2008-02-26 23:18 ` [Bug c++/35386] " kes at smolek dot com 2008-02-26 23:21 ` pinskia at gcc dot gnu dot org @ 2008-02-27 1:51 ` kes at smolek dot com 2008-02-27 2:00 ` pinskia at gcc dot gnu dot org 3 siblings, 0 replies; 5+ messages in thread From: kes at smolek dot com @ 2008-02-27 1:51 UTC (permalink / raw) To: gcc-bugs ------- Comment #3 from kes at smolek dot com 2008-02-27 01:50 ------- Subject: Re: Invalid vector code generated with -O2 Oops. Sorry for the false alarm. But shouldn't there be an error, or at least a warning? pinskia at gcc dot gnu dot org wrote: > ------- Comment #2 from pinskia at gcc dot gnu dot org 2008-02-26 23:20 ------- > You are violating C/C++ aliasing rules: > > typedef float v4sf __attribute__ ((vector_size(16))); > v4sf vSum; > complex<float> *vp = (complex<float> *) &vSum; > ... > > spectra[4*j] = vp[0]; > spectra[4*j+2] = vp[1]; > > > -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35386 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/35386] Invalid vector code generated with -O2 2008-02-26 23:11 [Bug c++/35386] New: Invalid vector code generated with -O2 kes at smolek dot com ` (2 preceding siblings ...) 2008-02-27 1:51 ` kes at smolek dot com @ 2008-02-27 2:00 ` pinskia at gcc dot gnu dot org 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu dot org @ 2008-02-27 2:00 UTC (permalink / raw) To: gcc-bugs ------- Comment #4 from pinskia at gcc dot gnu dot org 2008-02-27 01:59 ------- (In reply to comment #3) > Subject: Re: Invalid vector code generated with -O2 > > Oops. Sorry for the false alarm. But shouldn't there be an error, or > at least a warning? There should be a warning but sometimes getting warnings for undefined behavior is hard. -- Pinski -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35386 ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2008-02-27 2:00 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2008-02-26 23:11 [Bug c++/35386] New: Invalid vector code generated with -O2 kes at smolek dot com 2008-02-26 23:18 ` [Bug c++/35386] " kes at smolek dot com 2008-02-26 23:21 ` pinskia at gcc dot gnu dot org 2008-02-27 1:51 ` kes at smolek dot com 2008-02-27 2:00 ` pinskia at gcc dot gnu dot org
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