[PATCH] D87939: [PeepholeOptimizer] Enhance the redundant COPY elimination.

Mon Sep 21 12:04:48 PDT 2020

hliao added a comment.

In D87939#2285876 <https://reviews.llvm.org/D87939#2285876>, @qcolombet wrote:

>> The comment seems outdated, if my understanding is right, and even the original code cannot perform that change since, once the 2nd COPY with same source is found in L1407, the check @ L1419 just skips that earlier as the 1st COPY has no subreg and the 2nd COPY has sub1.
>
> Good point!
>
> Now, I am wondering why is this change not just NFC then?

It does improve the original by considering the COPY from the same subreg.

BTW, the comment seems ambiguous. It may read that that subreg extract won't be eliminated but handled somewhere else. @arsenm any comment?

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https://reviews.llvm.org/D87939