[PATCH] D46492: [DAGCombiner] Masked merge: don't touch "not" xor's.

[Sanjay Patel via Phabricator via llvm-commits]

spatel accepted this revision.
spatel added a comment.
This revision is now accepted and ready to land.

LGTM.



================
Comment at: lib/CodeGen/SelectionDAG/DAGCombiner.cpp:5378
 
+  // Don't touch 'not' (i.e. where y = -1).
+  if (isAllOnesConstantOrAllOnesSplatConstant(N->getOperand(1)))
----------------
Explain the 'why' of this logic in the comment here. Something like:
We don't expect 'not' patterns to occur here because those are simplified in IR and shouldn't be created in the DAG.


Repository:
  rL LLVM

https://reviews.llvm.org/D46492