[PATCH] D63981: [LV] Avoid building interleaved group in presence of WAW dependency

[Ayal Zaks via Phabricator via llvm-commits]

Ayal added a comment.

In D63981#1580294 <https://reviews.llvm.org/D63981#1580294>, @ebrevnov wrote:

> [snip]
>  But I'm a bit worry if reporting such WAW dependencies by LoopAccessInfo will affect many other places...and possibly compile time. What do you think?


I think same-iteration WAW dependences should be reported just as (and especially given that) same-iteration WAR dependences are. There's already a `MaxDependences` threshold in place to bail out when there are too many dependences. Admittedly borderline cases may now bail out with these extra WAW dependencies. But how many stores to the same address do we expect... and as commented in D57180 <https://reviews.llvm.org/D57180> - best optimize them into one. Also, as commented, it should suffice to record only a path of dependences between pairs of adjacent stores, e.g., by setting I2E to std::next(I2) instead of I1E, unless I2==I2E.


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