[RFC] Combine vectorized loops with its scalar remainder.

[Jeff Law]

On 02/09/2016 09:09 AM, Ilya Enkovich wrote:
>
> Another option is to peel scalar loop and then just run vectorizer
> one more time to vectorize and mask it.
>
> Also we may peel vectorized loop and use original version (with all
> STMT_VINFO still available) as a tail and peeled version as a main
> loop.
>
> Currently I think the best option is to peel scalar loop and run
> vectorizer one more time for it. This option is simpler and can also
> be used to vectorize loop tail with a smaller vector size when target
> doesn't support masking or masking is not profitable.
In general, a path where we have peeling & masking as an option seems 
wise.  The sense I've gotten from rth was that there's going to be 
classes of loops where that's going to be the best option.

jeff