[PATCH] D29926: [SelectionDAGBuilder] Simplify creation of shufflevector DAG nodes where inputs are larger than the mask

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.

The current code loops over all elements to calculate a used range. Then a second short loop looks at the ranges and determines if they can be used in a extract and creates a properly aligned start index for the extract.

This range finding is unnecessary, we can just calculate a properly aligned start index for an extract for each input during the first loop. If we don't find the same start index for each indice we can't use an extract.


https://reviews.llvm.org/D29926

Files:
  lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

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