[llvm] [X86] Support EGPR (R16-R31) for APX (PR #67702)

[Nikita Popov via llvm-commits]

nikic wrote:

> I am going to reland this PR tomorrow if no objection.

I don't think this should be relanded without addressing the issue. Even if it is a pre-existing one, this patch makes it worse.

@jayfoad How far are we from removing LiveVariables completely? I saw https://github.com/llvm/llvm-project/pull/66784 waiting for review -- is that the last step needed to make TwoAddressInstruction work on LiveIntervals instead? Is any further work needed after that?

https://github.com/llvm/llvm-project/pull/67702