[llvm-branch-commits] [llvm] [AArch64][PAC] Move emission of LR checks in tail calls to AsmPrinter (PR #110705)

[Anatoly Trosinenko via llvm-branch-commits]

atrosinenko wrote:

@kovdan01 Thank you for the reproducer!

I restored the original check `TI->readsRegister(AArch64::X16, TRI) ? AArch64::X17 : AArch64::X16` when computing the scratch register, as checking just the specific operand did not handle the `AUTH_TCRETURN*` pseudos which actually have two register operands. Additionally, the register class of the second register operand of these pseudo instructions was restricted, as it seems to be just a coincidence that at least one scratch register was available for authenticated tail calls.

https://github.com/llvm/llvm-project/pull/110705