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

[Zhang Kang via Phabricator via llvm-commits]

ZhangKang added a comment.

> 1: the PHI node get two different values from the same block `%bb.0`?

It's a typo, it should be

  %3:g8rc = PHI %1, %bb.1, undef %2:g8rc, %bb.0`

I will update it.

> 2: for `undef` value we still generate `%2:g8rc` as its def?

In fact, after the `PHIElimination` pass, if there is no use for %2:g8rc, it will be removed. But the patch D73152 <https://reviews.llvm.org/D73152> has added it into LivrVariables for %bb.0, it's not correct.

> Maybe adding a more runnable test case is better.

The Verification for LiveVariable pass and PHIElimination pass has been disabled, so it's hard to find a case to hit this bug. Because the two passes has some other errors,we can't enable verification for the two passes.


Repository:
  rG LLVM Github Monorepo

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

https://reviews.llvm.org/D80077