[llvm] [AArch64] Define APAS, BRB and TRCIT as SYS aliases (PR #203563)

[via llvm-commits]

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@@ -526,6 +531,25 @@ foo:
   sys #4, c8, c7, #6, x31
 ; CHECK: tlbi vmalls12e1
 
+  sys #3, c7, c2, #7, x2
+; CHECK-ITE: trcit x2
+; CHECK-NO-ITE: sys #3, c7, c2, #7, x2
+  sys #3, c7, c2, #7
+; CHECK-ITE: trcit xzr
+; CHECK-NO-ITE: sys #3, c7, c2, #7
+
+  sys #1, c7, c2, #4
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CarolineConcatto wrote:

What happens if we have :
sys #1, c7, c2, #4, X30
or 
 brb iall, x30?

https://github.com/llvm/llvm-project/pull/203563