[PATCH] D117926: [SLP] Optionally preserve MemorySSA

[Alina Sbirlea via Phabricator via llvm-commits]

asbirlea added a comment.

Reading the details in your post and looking at the SLPVectorizer code I think there's the potential for the pass to benefit from using MemorySSA.  However I do not understand enough of the SLPVectorizer mechanics to guess if this will work out or not.
In this context, I think it makes sense to have incremental changes while keeping building and updating MSSA off by default; as you mentioned in the post, all changes can (and should) be reverted if a later decision is to pursue something else.

@nikic Thoughts?

Regarding this patch, seeing MSSA used in a dependent patch would help.
Is there a benefit from the existance of an `insertAccesses() `/`insertDefs() `/`insertUses` API in MSSA (i.e. bulk add update, perhaps limited to within the same BB)? Does doing lazy updates during the vectorizeTree() call make sense or will MSSA need to be queried?


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  https://reviews.llvm.org/D117926/new/

https://reviews.llvm.org/D117926