[PATCH] D58419: [GISel]: Allow G_EXTRACT_VEC_ELT's result to be larger the source element type

[Aditya Nandakumar via Phabricator via llvm-commits]

aditya_nandakumar added a comment.

In D58419#1404103 <https://reviews.llvm.org/D58419#1404103>, @arsenm wrote:

> I always thought this behavior in SelectionDAG was error prone.


Personally in an out of tree backend, I find BUILD_VEC_TRUNC to be very elegant when trying to legalize/optimize vector types whose scalar types are illegal in the architecture otherwise needing several unmerges + shifts + ands.
I'm fine with adding a separate opcode (say G_EXTRACT_VECTOR_ELT_ANYEXT - suggestions accepted).
We need to do something similar for INSERT_VEC_ELT which can implicitly truncate.


Repository:
  rL LLVM

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https://reviews.llvm.org/D58419