[PATCH] D123377: [AArch64] Only mark cost 1 perfect shuffles as legal

[Sjoerd Meijer via Phabricator via llvm-commits]

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

That's quite a lot change in the test cases. It's easy to see that the smaller ones are improvements. For the bigger changes that isn't that obvious. But I trust you have run numbers and this is overall better. So LGTM, let's give this a try.



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Comment at: llvm/lib/Target/AArch64/AArch64ISelLowering.cpp:11495
 
-    if (Cost <= 4)
+    // The cost tables encode cost 1 (or 0) shuffles using the value 0.
+    if (Cost == 0)
----------------
This comment is a bit cryptic for me. The description of this ticket is clear though, perhaps you adopt some of that rationale here.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D123377/new/

https://reviews.llvm.org/D123377