http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51041
Bug #: 51041
Summary: g++ strange optimisation behaviour
Classification: Unclassified
Product: gcc
Version: 4.6.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51041
--- Comment #1 from fb.programming at gmail dot com 2011-11-08 22:20:53 UTC ---
Created attachment 25761
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25761
performance test doing vec*vec calc
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51499
Bug #: 51499
Summary: vectorizer missing simple case
Classification: Unclassified
Product: gcc
Version: 4.6.2
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51499
--- Comment #2 from fb.programming at gmail dot com 2011-12-11 08:33:40 UTC ---
(In reply to comment #1)
g++-4.6.2 -S -Wall -O3 -ftree-vectorize -ftree-vectorizer-verbose=2 \
-ffast-math -fno-vect-cost-model
gives me exactly the same
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51499
--- Comment #4 from fb.programming at gmail dot com 2011-12-11 11:52:30 UTC ---
Looks like there has been some great progress in gcc 4.7!
Still I think it behaves slightly buggy.
(1) In this case it should work without -funsafe-math
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51499
--- Comment #7 from fb.programming at gmail dot com 2011-12-11 14:55:13 UTC ---
(In reply to comment #5)
> > (3) If I change all double's into float's in the code above it seems to
> I think you are looking at the scalar epil
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51499
--- Comment #13 from fb.programming at gmail dot com 2011-12-12 14:20:58 UTC ---
(In reply to comment #9)
> So, you are suggesting to remove the need in flag_associative_math for fp for
> cases when a reduction computation is already unrol
