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

Tue May 19 07:34:16 PDT 2020

shchenz added a comment.

In D80077#2043726 <https://reviews.llvm.org/D80077#2043726>, @lkail wrote:

> > We have two incoming values from bb %bb.0, undef and %2:g8rc
>
> Should be one, i.e., undef is a flag of the register operand.

Ah, right, I checked the case `shrink-wrap.ll`, after pass `Process Implicit Definitions`, many `undef` **FLAG** are added to register operands. I misunderstood the `undef` flag with `undef` value in llvm IR representation.

Repository:
  rG LLVM Github Monorepo

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

https://reviews.llvm.org/D80077