[PATCH] D82618: [MemorySSA] Update comment in PassBuilder

[Alina Sbirlea via Phabricator via llvm-commits]

asbirlea accepted this revision.
asbirlea added a comment.
This revision is now accepted and ready to land.

It's not impossible. It's hard and likely not worth it.
Preserving MemorySSA for this pass means creating MemoryAccesses for all blocks cloned when unrolling. Creating an access and then updating so many times is likely more expensive than recomputing MemorySSA from scratch.

I have a patch lined up where MemorySSA would be set to true when unroll added to LPM2, but preliminary testing didn't show this case to provide much value.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D82618/new/

https://reviews.llvm.org/D82618