https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57858
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |rguenth at gcc dot gnu.org
Status|UNCONFIRMED |RESOLVED
Blocks| |53947
Resolution|--- |FIXED
--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
It was fixed by adding another loop header copying pass before vectorization,
aka ch_vect. Of course it means we peel one iteration which might be not 100%
optimal. Optimally we'd teach PRE that those loop carried dependences are
bad(TM) just like we do for loads and extend that to cover calls. The peeling
means we need an epilogue, so we didn't really save a sqrt call.
That said, the situation is somewhat mitigated now and I'd declare it fixed
anyway, the testcase is somewhat artificial (resolvable at compile time).
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53947
[Bug 53947] [meta-bug] vectorizer missed-optimizations
