[PATCH] D50248: [GuardWidening] Insert fictive guards to loop preheader to increase chances of widening

[Philip Reames via Phabricator via llvm-commits]

reames requested changes to this revision.
reames added a comment.
This revision now requires changes to proceed.

I think this is the wrong approach.  I'd suggest tackling the example in two ways:

1. Try to hoist c2 above the existing guard.  We have lots of precedent for such things, look for makeAvailableAt.
2. Hoisting a guard from within a loop to the preheader is worthwhile.  I've been cleaning up the pieces of LICM needed to make this easy.  We can chat offline if you want to pick that up and finish it.


https://reviews.llvm.org/D50248