[llvm] InstSimplify: lookthru casts, binops in folding shuffles (PR #92668)

[David Green via llvm-commits]

https://github.com/davemgreen commented:

Hi - I recently added something very similar in VectorCombine under #88693. I deliberately added it to vector combine as I thought trying the combine many times through the pipeline was best avoided. I didn't think we had things like that in instsimplify.

I have some patches to extend the current functionality, and it should be able to handle this case if I understand it correctly. I have been holding off adding additions until the comments from https://github.com/llvm/llvm-project/commit/a4d10266d20bfe5930dfed77e17832af341ed66e can be worked out. I can try and put up the zext/sext/trunc patch I have, it should already handle intrinsics and binops/other unary ops.

> Why is the CI failing? All tests pass, so is it some timing issue?

That looks like ccache failed - it sometimes does that.

https://github.com/llvm/llvm-project/pull/92668