[llvm] [AArch64][llvm] Redefine some insns as an alias of `SYS` (PR #187004)

[Kerry McLaughlin via llvm-commits]

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@@ -138,12 +141,18 @@ brb iall
 brb inj
 // CHECK: brb iall  // encoding: [0x9f,0x72,0x09,0xd5]
 // CHECK: brb inj   // encoding: [0xbf,0x72,0x09,0xd5]
-// ERROR-NO-BRBE: [[@LINE-4]]:1: error: instruction requires: brbe
-// ERROR-NO-BRBE: [[@LINE-4]]:1: error: instruction requires: brbe
+// CHECK-UNKNOWN: d509729f sys #1, c7, c2, #4
+// CHECK-UNKNOWN: d50972bf sys #1, c7, c2, #5
+// ERROR-NO-BRBE: [[@LINE-6]]:1: error: instruction requires: brbe
+// ERROR-NO-BRBE: [[@LINE-6]]:1: error: instruction requires: brbe
 
 brb IALL
 brb INJ
 // CHECK: brb iall  // encoding: [0x9f,0x72,0x09,0xd5]
 // CHECK: brb inj   // encoding: [0xbf,0x72,0x09,0xd5]
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kmclaughlin-arm wrote:

These look like they should have the same behaviour as `brb iall` & `brb inj`, so I think it's worth adding the same `CHECK-UNKNOWN` lines to these existing tests as well.

https://github.com/llvm/llvm-project/pull/187004