[PATCH] D39352: [SimplifyCFG] Don't do if-conversion if there is a long dependence chain

[Hal Finkel via Phabricator via llvm-commits]

hfinkel added a comment.

> Doing this so early on means that we can't recognize common, direct patterns in terms of select. While perhaps it would be better to go and teach everything to generically reason about either a select or a phi around control flow, that will need a really massive undertaking.

FWIW, I believe that the outcome of the select/GVN discussion (e.g., from PR34603) has been that this is exactly what we need to do: we need to move select formation late in the pipeline, and likely canonicalize away from select early.


Repository:
  rL LLVM

https://reviews.llvm.org/D39352