[PATCH] D65174: [DAGCombine] Limit the number of times for a store being considered for merging

[Wei Mi via Phabricator via llvm-commits]

wmi added a comment.

In D65174#1605103 <https://reviews.llvm.org/D65174#1605103>, @niravd wrote:

> Ah. That's a tricky one.  It sounds like this isn't a case of the candidate stores not being mergable, but rather us giving up before we completely verify that.
>
> I don't suppose the values in the indirect value operands to the candidate stores have a relatively short dependence on a node not too far from the RootNode. Right now, we only prune at the root node (and components through the TokenFactors). but we could also just mark further predecessors of the RootNode as not needing to be searched.


It may not be easy for us to prune the searching space without missing some merging opportunity. I feel it is easier to achieve that goal by controlling how many times a {RootNode, StoreNode} pair appear in candidate set repeatedly. With the patch, no bit change in the binaries were found for clang and some large application. So the current patch is a safe change.


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https://reviews.llvm.org/D65174