fixup! [AArch64][llvm] Armv9.7-A: Add support for Virtual Memory Tagging (FEAT_MTETC)

Add llvm/test/MC/AArch64/armv9.7a-mtetc-diagnostics.s

Author: jthackray

llvm/test/MC/AArch64/armv9.7a-mtetc-diagnostics.s

@@ -0,0 +1,16 @@
+// RUN: not llvm-mc -triple=aarch64 -mattr=+mtetc -show-encoding < %s 2>&1 \
+// RUN:        | FileCheck %s --check-prefix=CHECK-ERROR
+// RUN: not llvm-mc -triple=aarch64 -show-encoding < %s 2>&1 \
+// RUN:        | FileCheck %s --check-prefix=CHECK-REQUIRES-MTETC
+
+//------------------------------------------------------------------------------
+// FEAT_MTETC Extension instructions
+//------------------------------------------------------------------------------
+
+dc zgbva
+// CHECK-ERROR: error: specified dc op requires a register
+// CHECK-REQUIRES-MTETC: DC ZGBVA requires: mtetc
+
+dc gbva
+// CHECK-ERROR: error: specified dc op requires a register
+// CHECK-REQUIRES-MTETC: DC GBVA requires: mtetc