[AArch64] Add isAuthenticated predicate to MCInstDesc

Add a predicate to MCInstDesc that allows tools to determine whether an
instruction authenticates a pointer. This can be used by diagnostic
tools to hint at pointer authentication failures.

Differential Revision: https://reviews.llvm.org/D70329

rdar://55089604
diff --git a/llvm/utils/TableGen/CodeGenInstruction.h b/llvm/utils/TableGen/CodeGenInstruction.h
index 573822f..1f08ce4 100644
--- a/llvm/utils/TableGen/CodeGenInstruction.h
+++ b/llvm/utils/TableGen/CodeGenInstruction.h
@@ -278,6 +278,7 @@
     bool hasChain : 1;
     bool hasChain_Inferred : 1;
     bool variadicOpsAreDefs : 1;
+    bool isAuthenticated : 1;
 
     std::string DeprecatedReason;
     bool HasComplexDeprecationPredicate;