[PATCH] D31919: NewGVN: Don't propagate over phi backedges where undef causes us to have >1 value.

[Daniel Berlin via Phabricator via llvm-commits]

dberlin added a comment.

At some point i'm going to try to make the graph-traits'ish version work.
The main issue for us is that we have to iterate through all parts, because it's really stateless from our perspective.

IE every time you call  scc_begin, it is starting the SCC finding from scratch.

That turned out to be pretty expensive for us vs doing this.


https://reviews.llvm.org/D31919