[llvm] [AArch64] Fix tryMergeAdjacentSTG function in PrologEpilog pass (PR #68873)

[Kristof Beyls via llvm-commits]

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@@ -3703,6 +3703,17 @@ bool isMergeableStackTaggingInstruction(MachineInstr &MI, int64_t &Offset,
   return true;
 }
 
+bool isNZCVLiveOut(MachineBasicBlock &MBB) {
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kbeyls wrote:

Yeah, it seems like there is no `MBB.isLiveOut`.

https://github.com/llvm/llvm-project/pull/68873