[llvm] [InstCombine] enable more factorization in SimplifyUsingDistributiveLaws (PR #69892)

[via llvm-commits]

goldsteinn wrote:

> Just to get the obvious stuff out of the way:
> 
> * Please update the patch description to describe what this patch is doing.
> * Add alive2 proofs.
> * It looks like you are adding two related but independent transforms here -- I would recommend splitting them into separate patches.
> * And yes, we should not hardcode mul opcodes -- if we do, there should be clear justification for doing that.

Can you also split the tests commit so we can see the IR diff generated by this patch?

https://github.com/llvm/llvm-project/pull/69892