[Bug tree-optimization/54939] Very poor vectorization of loops with complex arithmetic

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54939



Richard Biener <rguenth at gcc dot gnu.org> changed:



           What    |Removed                     |Added

----------------------------------------------------------------------------

             Status|NEW                         |ASSIGNED

             Blocks|                            |37021

         AssignedTo|unassigned at gcc dot       |rguenth at gcc dot gnu.org

                   |gnu.org                     |



--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> 2013-03-27 
11:19:49 UTC ---

Confirmed.  GCC vectorizes this using hybrid SLP - it unrolls the loop once

to be able to vectorize two minus and two adds resulting from the complex

multiplication.



The PR is kind-of a duplicate of PR37021 where also a reduction and

a variable stride is involved.  So fixing this bug is required to more

efficiently vectorize PR37021.



Note that even this bug has multiple issues that need to be tackled.

I happen to work on them.