[PATCH] D19984: [LV] Handle RAW dependences in interleaved access analysis

[Adam Nemet via llvm-commits]

anemet added a comment.

In http://reviews.llvm.org/D19984#424731, @mssimpso wrote:

> Hi Silviu, thanks for the comments.
>
> > I think non-zero dependences would have already been rejected by LAA. Would this this be the reason why it is correct to only look at the zero distance ones?
>
>
> Yes, that should be the case!


Why are non-zero forward deps rejected by LAA?  Because of the HW store-to-load forwarding case?  I think that that is only a performance consideration and it's only on conditionally.

I think that we should probably take the time and review the soundness of these code motions with respect to interleaved access vectorization {RAW, WAR, WAW} x {loop-independent, loop-carried}.  I've only looked at the LAA aspects of this feature so far but I am a bit worried about this code now.

Matt, do you think you can do this?

I am also thinking if we should disable this feature in the meantime?!


http://reviews.llvm.org/D19984