[PATCH] D80077: [LiveVariables] Don't set undef reg PHI used as live for FromMBB

[ChenZheng via Phabricator via llvm-commits]

shchenz added a comment.

  bb.0:
    ... // no-definiton for %2
  bb.1:
    ...
  bb.2:
    %3:g8rc = PHI %1, %bb.0, undef %2:g8rc, %bb.0

I am confused with the above `PHI` node in your description. Is it `%3:g8rc = PHI [%1, %bb.0], [undef %2:g8rc, %bb.0]`
If so, do you mean:
1: the PHI node get two different values from the same block `%bb.0`?
2: for `undef` value we still generate `%2:g8rc` as its def?

Maybe adding a more runnable test case is better.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D80077/new/

https://reviews.llvm.org/D80077