[PATCH] D158063: [GISel][AArch64] Combine G_BUILD_VECTOR(G_UNMERGE) with undef elements

[Matt Arsenault via Phabricator via llvm-commits]

arsenm accepted this revision.
arsenm added a comment.
This revision is now accepted and ready to land.

In D158063#4602879 <https://reviews.llvm.org/D158063#4602879>, @dmgreen wrote:

> OK - this now just removes the nodes. It does mean we lose information about which lanes are undef, but there are less instructions to deal with and we don't need to do it just when the shuffle is legal.

If you think that's useful, it might make sense to add a pre-legalizer combine for that


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