[PATCH] D47927: [WIP][TargetLowering] Simplify expansion of S{ADD,SUB}O

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added a comment.

Hmm, while there, just to point out the obvious, the another approach here would be to teach DAGCombine/`TargetLowering::SimplifySetCC()` about these folds.
That is explicitly one of a few valid reasons to add optimizations into backend 'instead' of middle-end.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D47927/new/

https://reviews.llvm.org/D47927