[PATCH] D51589: DAG: Fold extract_vector_elt (scalar_to_vector), K to undef

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added a comment.

I think this is a regression because at some point the high element unnecessarily goes from undef to 0:
Combining: t158: v2i16 = extract_subvector t188, Constant:i32<2>
 ... into: t212: v2i16 = BUILD_VECTOR t134, Constant:i16<0>

This was undef originally


Repository:
  rL LLVM

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  https://reviews.llvm.org/D51589/new/

https://reviews.llvm.org/D51589