[Bug target/91735] [9/10 Regression] Runtime regression for SPEC2000 177.mesa on Haswell around the end of August 2018

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91735

--- Comment #5 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Richard Biener from comment #3)
> Reducing the VF here should be the goal.  For the particular case "filling"
> the holes with neutral data and blending in the original values at store time
> will likely be optimal.  So do
> 
>   tem = vector load
>   zero all [4] elements
>   compute
>   blend in 'tem' into the [4] elements
>   vector store

MASKMOVDQU [1] should be an excellent fit here.

[1] https://www.felixcloutier.com/x86/maskmovdqu