[PATCH] D127516: RegisterCoalescer: Fix verifier error when merging copy of undef

[Matthias Braun via Phabricator via llvm-commits]

MatzeB added a comment.

I am not sure I understand this change... Wasn't the intention of the existing that code that when you have something like:

  %2 = COPY undef %1
    USE %2

that you merge the regs to remove the copy and add an `undef` to the use operands? =>

  USE undef %1

Why are we starting to use `IMPLICIT_DEF`s here? Is this related to subregs?


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D127516/new/

https://reviews.llvm.org/D127516