[PATCH] D33633: [DAGCombine] Unchecked calls to DAGCombiner::*ExtPromoteOperand

[Jacob Young via Phabricator via llvm-commits]

jacobly added a comment.

I would have, but it was triggered by an out of tree backend.  In order to trigger it, a backend would need to overload `TargetLowering::IsDesirableToPromoteOp` to return true for a type for which `ISD::SIGN_EXTEND_INREG` is marked illegal.  In tree, only X86 overloads and sometimes returns true for `MVT::i16` yet it marks `setOperationAction(ISD::SIGN_EXTEND_INREG, MVT::i16  , Legal);`.


https://reviews.llvm.org/D33633