[Bug tree-optimization/86024] Missed memcpy loop distribution with elementwise copy

[amker at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86024

--- Comment #3 from bin cheng <amker at gcc dot gnu.org> ---
(In reply to Marc Glisse from comment #2)
> (In reply to Richard Biener from comment #1)
> > Or we may want to un-"SRA" such patterns, generating aggregate copies.
> 
> I notice that store-merging does not merge these stores, I didn't check why.
> SLP can do it for long but not for int (no vector of 2 ints) with
> -fdisable-tree-vect.
> 
> (anyway that's too late for ldist, the DR / vectorizer approach sounds
> better, just mentioning this as another possible missed optimization)
Yes, merging and SRA are conflicting with each other here, and it's difficult
to get a model deciding when to do what.  With DR improvement, we can identify
and connect two or more builtin partitions in ldist.