[llvm] [AArch64] Hint regalloc to choose distinct predicate for MATCH/CMP (PR #190139)

[Paul Walker via llvm-commits]

paulwalker-arm wrote:

I believe this preference applies to all predicate setting instructions that take a governing predicate.  Rather than doing this in C++ code that's likely to become out of date, can we use TSFlags. More specifically, can you add DestructivePredicate to DestructiveInstType to represent non-movpfrxable instructions that have a predicated predicate result. That removes the need for the instruction opcodes switch and will make it easier to extend to cover the other instructions now and in the future.  I'm not asking for this PR to support the other instructions but if you want to do that then I'll not complain either.

https://github.com/llvm/llvm-project/pull/190139