[PATCH] D62775: [SelectionDAG] Skip addrspacecast expansion when casting undef values

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

If you look at some targets, they provide multiple address-spaces which are essentially identical; see, for example, the implementation of isNoopAddrSpaceCast on x86.  Not sure what the complete justification was, but it can be convenient if you need to dereference null.

It's legitimate for a target to reject addrspacecasts which don't make sense.


Repository:
  rL LLVM

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  https://reviews.llvm.org/D62775/new/

https://reviews.llvm.org/D62775