[PATCH] D47831: [DAGCombiner] Recognize more patterns for ABS

[Krzysztof Parzyszek via Phabricator via llvm-commits]

kparzysz added a comment.

In https://reviews.llvm.org/D47831#1123994, @spatel wrote:

> I can't rule it out completely, but that seems very unlikely given that we have a generic ABS node. Some set of smaller DAG transforms would have to unknowingly produce the shift+xor+add/sub instructions independently without realizing it has created the larger ABS node?


Yes, that's what I meant.  I've seen a similar kind of behavior before (different operations though).  I can try to create a testcase that shows that.  Is this simply something that we assume could happen and have to live with?


Repository:
  rL LLVM

https://reviews.llvm.org/D47831