[PATCH] D141135: [RFC][GlobalISel] Replace the current GlobalISel matcher with a bottom-up matcher

Fri Jan 6 07:59:49 PST 2023

Kai added a comment.

In D141135#4031482 <https://reviews.llvm.org/D141135#4031482>, @arsenm wrote:

>> Compiling LLVM is slightly longer with this change applied: 25m35.471s vs 28m51.797
>
> This is huge. I don't understand this part. Surely you don't have bootstrapped globalisel working? Why this slowdown?

The slowdown comes from llvm-tblgen and is due to the sorting at the end of `createMatchSets()`. This is currently required to get a stable encoding for testing. I currently work on changing the test structure, with the goal to remove the sorting completely.
Another reason for the slowdown is that my implementation still calculations to much. I always loop over all representer sets, but only sets added in the last round can actually add another set. This can clearly improved.

I have not yet measured bootstrapping with globalisel. The only reason for that is that I struggle a bit with setting up a cross-compile environment. I guess aarch64 is the best architecture to test the impact.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D141135/new/

https://reviews.llvm.org/D141135