[PATCH] D106261: [ARM][LowOverheadLoops] Allow unpredicated VORRs if the operand def produces zeroed false lanes

Mon Jul 26 00:20:15 PDT 2021

SjoerdMeijer added a reviewer: samparker.
SjoerdMeijer added a comment.

In D106261#2903675 <https://reviews.llvm.org/D106261#2903675>, @dmgreen wrote:

> Hello. Sorry for the delay, I had apparently forgotten about this. I'm not sure I understand the reasoning here, but I'm not sure I understood the reasoning for the FalseLanesZero to begin with.

Yes, it's complicated to ensure the transformation is correct. The high-level idea is described in a comments in `LowOverheadLoop::ValidateLiveOuts()`. Please have a look at that, and if it is still unclear, we need to improve that.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D106261/new/

https://reviews.llvm.org/D106261