[clang] [llvm] [AArch64] Support preserve_none calling convention (PR #91046)

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antangelo wrote:

> I don't think you can use x16 and x17 for argument passing due to them being reserved for PLTs and call veneers. That is if the linker decides to create a branch island or if the function is called via a PLT, x16 and x17 will be clobbered on the call so arguments using that will also won't work.

Thanks for catching this, I've removed them from the argument passing list.

https://github.com/llvm/llvm-project/pull/91046