Fix failed tests on Darwin

[FedericoBruzzone]

Hi folks, I'm new to Lighthouse! Thanks for your work :D
I think that it's a super cool project, not only for prototypes but also for eventual educational stuff.

I just set up the repo on Darwin (macOS M4 Pro).
After running uv run lit . I got the following output:

Failed Tests (4):
  Lighthouse test suite :: examples/ingress/mlir_gen/generate-linalg-3layer-mlp.sh
  Lighthouse test suite :: examples/xegpu/kernel_bench.py
  Lighthouse test suite :: test/execution/target_info_host_override.py
  Lighthouse test suite :: test/run/pipeline-check.mlir

This PR aims to resolve them.
For the first three tests, other than minor fixes, it introduces _get_feature_list_darwin by leveraging sysctl.
Regarding pipeline-check.mlir, the problem is relatively simple to fix. Currently, lighthouse assumes a .so extension for shared libs. Unfortunately, on macOS the extension is .dylib. This PR introduces the _SHARED_EXT var to handle it properly.

Please let me know whether this is welcome and if I can improve this submission 🫶

[FedericoBruzzone]

Kind ping: @rengolin @adam-smnk

[rengolin]

Looks good, thanks! Do you want to address the final problem in a separate PR? If so, I'm happy to merge this.

Just need to understand the bash change. Neither solutions are good, mind you, and both play tricks with symlinks and how bash works across systems. So, if cd + pwd work on both cases, I'm happy with it.

@adam-smnk any strong opinion?

[FedericoBruzzone]

Looks good, thanks!

Thanks for the prompt response! :D

Do you want to address the final problem in a separate PR? If so, I'm happy to merge this.

I'll send a PR in a moment. I thought it would take longer, but I almost fixed it'll be stacked on this one.

Just need to understand the bash change. Neither solutions are good, mind you, and both play tricks with symlinks and how bash works across systems. So, if cd + pwd work on both cases, I'm happy with it.

@adam-smnk any strong opinion?

You're absolutely right, an alternative solution could be used:

PROJECT_ROOT="$(python3 -c "from pathlib import Path; print(Path('$0').resolve().parent.parent.parent.parent)")"

If you prefer, I'm happy to make the change.

[rengolin]

Thanks! Is there a free Darwin builder in Github? We could setup a CI loop like we do for Arm and x86 Linux.

[FedericoBruzzone]

Not at all! :D
I've been using macos-14 for about two years, but I believe it will be deprecated.
I think the best way to go is macos-15 (i.e., macos-15-arm), see here for more details.
If you don't mind, I'm happy to send a patch for this.

[rengolin]

Don't worry, PRs for new builders is a pain, I'll try to set up on a new branch and then merge to main when it's working.