[PATCH] D31686: [InstCombine] Support folding a subtract with a constant LHS into a phi node

[Daniel Berlin via Phabricator via llvm-commits]

dberlin added a comment.

Just FYI, i'm about to post a patch to newgvn (just doing some debugging) which will do equivalence between phi of ops and op of phis, in value numbering (which makes them susceptible for later simplification)

It gets these cases already (and i suspect, a lot of instcombine cases)
For the initial version, it is limited to insertion in cases where the phi nodes end up constants for simplicity.
(Which is enough to catch all of these cases)


Repository:
  rL LLVM

https://reviews.llvm.org/D31686