[PATCH] D100486: [COST]Improve cost model for shuffles in SLP.

[Alexey Bataev via Phabricator via llvm-commits]

ABataev added a comment.

In D100486#2773883 <https://reviews.llvm.org/D100486#2773883>, @lebedev.ri wrote:

> Just because we've legalized to a certain vector type, is that sufficient guarantee that we have an appropriate shuffle operations on that legal vector type?

I think so, at least the existing code relies on this. This code just improves the existing situation. Currently, we conservatively calculate the cost of the shuffles as the permutation of all source subvectors. But in presence of mask we can estimate this cost more precisely, choosing only subvectors actually used in the permutations.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D100486/new/

https://reviews.llvm.org/D100486