[llvm] [AArch64][PAC] Select auth+load into LDRAA/LDRAB/LDRA[pre]. (PR #123769)

[Anatoly Trosinenko via llvm-commits]

================
@@ -2159,6 +2163,111 @@ void AArch64AsmPrinter::emitPtrauthBranch(const MachineInstr *MI) {
   EmitToStreamer(*OutStreamer, BRInst);
 }
 
+void AArch64AsmPrinter::LowerPtrauthAuthLoad(const MachineInstr &MI) {
+  const bool IsPreWB = MI.getOpcode() == AArch64::LDRApre;
+
+  const unsigned DstReg = MI.getOperand(0).getReg();
+  const int64_t Offset = MI.getOperand(1).getImm();
+  const auto Key = (AArch64PACKey::ID)MI.getOperand(2).getImm();
+  const uint64_t Disc = MI.getOperand(3).getImm();
+  const unsigned AddrDisc = MI.getOperand(4).getReg();
----------------
atrosinenko wrote:

```suggestion
  const Register AddrDisc = MI.getOperand(4).getReg();
```

https://github.com/llvm/llvm-project/pull/123769