[llvm] ✨[AArch64] Custom lower abds and abdu to avoid regressions caused by freezes (PR #177992)

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AZero13 wrote:

> Sorry for the delay @AZero13. I'm struggling to link the PR's description to the PR's changes. When looking at the isel output (without the PR applied) for some of the tests with significant changes (i.e. not just a change of CC), for example abd_minmax_i8, I don't see any freezes in the DAG? Is the PR missing dedicated tests for the issue you're wanting to fix?

Well, that can only be the explanation for the changes. But either way, improvements are improvements no? 

https://github.com/llvm/llvm-project/pull/177992