[Bug c/59100] requesting optimization of safe rotate function

jakub at gcc dot gnu.org gcc-bugzilla@gcc.gnu.org
Wed Nov 13 08:06:00 GMT 2013


Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Yeah, see PR45216 and PR57157.  Recognizing n?rotate<x,n>:x as rotate<x,n> can
be done, but probably not in forwprop or at least not at the same spot as
simplify_rotate, because it involves PHIs and different basic blocks.
Anyway, if you are going to recommend some idiom, I think the one in PR57157 is
better because if it doesn't get optimized into the rotate, it at least doesn't
contain any conditionals.

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