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

ChenZheng via Phabricator via llvm-commits llvm-commits at lists.llvm.org
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.


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