[PATCH] D125335: Give option to use isCopyInstr to determine which MI is treated as Copy instruction in MCP

[Dave Green via Phabricator via llvm-commits]

dmgreen added a comment.

I hadn't expected MachineCopyPropgation would be too expensive - it sounds like a simple concept and seems to already be run twice in the default pipeline. This is only adding an extra at -O3, so hopefully won't be too bad for compile time.

Perhaps it is worth running some quick tests though? And if it is a problem adding `disablePass(&MachineCopyPropagationID);` for AArch64, to run just at the new pass location, not the old. I'm not sure if that would have any knock-on effects, disabling the two existing runs of the pass earlier in the pipeline.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D125335/new/

https://reviews.llvm.org/D125335