[PATCH] D29489: Optimize SETCC + VSEL of incompatible or illegal types

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added a reviewer: RKSimon.
RKSimon added inline comments.


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Comment at: lib/CodeGen/SelectionDAG/SelectionDAG.cpp:3042
   case ISD::CONCAT_VECTORS:
+  case ISD::VECTOR_SHUFFLE:
     // Determine the minimum number of sign bits across all input vectors.
----------------
Shuffle can't safely reuse the concat implementation - if any mask index is set to -1 (UNDEF) then we know nothing about the sign bits. Typically it will be a random element from one of the sources but it could just as easily be something else depending on shuffle lowering.


https://reviews.llvm.org/D29489