mac m1 cross compile

[powderluv]

Add support for M1 cross compile. Also compile and test macos x86

[makslevental]

CONGRATS

[sjain-stanford]

I think Run torch-mlir unit tests step is still using x86_64 build for running tests:

cmake --build build --target check-torch-mlir-all

Is this intentional? Or do we want to configure this with _${{ matrix.targetarch }} as well?

[powderluv]

Yeah we are building both architectures and testing only x86

[sjain-stanford]

Yeah we are building both architectures and testing only x86

This makes sense. The only consideration is the 2G ccache limit. As we're building twice in the same job / runner, we may always see low cache hit rate? Is it better to set the cross compile build as a separate github workflow? This will also maximize parallelization (use a separate runner of which there are no restrictions I presume)? I'm hesitant in increasing the ccache limit of 2G more due to the reasons we discussed on discord.

[powderluv]

I think we can drop the macOS x86 build all together. I think we can now reduce the matrix considerably.

[sjain-stanford]

I think we can drop the macOS x86 build all together. I think we can now reduce the matrix considerably.

You mean remove x86 build + tests for macos and only use arm64 build + tests? That would be great indeed :)