[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#428293, @mssimpso wrote:

> Hi Adam,
>
> > 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.
>
>
> Siviu was referring to a comment I had made in the source. But I think the idea was that LAA had already ensured the absence of the dependences that would have prevented vectorization. So the interleaved access analysis didn't need to worry about them. Regarding the store-to-load forwarding case, yes, that is the assumption the original analysis made, which was incorrect. The current patch attempts to fix that.


No, I was asking about *non-zero* distance deps specifically.  The current patch only handles zero-distance deps.  So my question was whether for non-zero distance we still rely on the store-to-load forwarding detection code to make the dep unsafe for vectorization.


http://reviews.llvm.org/D19984