[PATCH] D152358: [CGP] Remove operand of llvm.assume more aggressively.

[Anna Thomas via Phabricator via llvm-commits]

anna added a comment.

Just to give more input here - we have seen many cases where the loop vectorizer generates a lot of code with a bunch of extracts for each assume operand. Basically we do not have "vectorized assumes". We were looking at two options - we drop such assumes before loop vectorizer or teach CodeGenPrepare to be more aggressive.

The issue is knowing *which assumes* would need to be kept until end of opt at least (@nikic heuristic may work here). I believe Serguei's proposal is to use this patch as a short term fix.
As a long term approach, I think  if we do plan to keep assumes in CodeGen, we would need to figure out a "drop assumes" pass with some good heuristics and appopriate position in pipeline?


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  https://reviews.llvm.org/D152358/new/

https://reviews.llvm.org/D152358