[PATCH] D32916: [DAGCombine] (addcarry 0, 0, X) -> (ext/trunc X)

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added inline comments.


================
Comment at: lib/CodeGen/SelectionDAG/DAGCombiner.cpp:2146
+
+  // fold (addcarry 0, 0, X) -> (ext/trunc X) and no carry.
+  if (isNullConstant(N0) && isNullConstant(N1))
----------------
I'm not sure if you can do this - aren't carry bits boolean types? So won't they be TargetLowering::BooleanContent? 

getBoolExtOrTrunc doesn't quite work - you're wanting a 0 or 1 result......


https://reviews.llvm.org/D32916