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

[Jonathan Thackray via llvm-commits]

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@@ -941,6 +942,38 @@ bool AArch64InstPrinter::printSysAlias(const MCInst *MI,
       case 0: goto Search_IC;
       case 3: goto Search_PRCTX;
       }
+    // BRB aliases.
+    case 2: {
+      switch (Op1Val) {
+      default:
+        return false;
+      case 1:
+        if (!(STI.hasFeature(AArch64::FeatureAll) ||
+              STI.hasFeature(AArch64::FeatureBRBE)))
+          return false;
+
+        NeedsReg = false;
+        switch (Op2Val) {
+        default:
+          return false;
+        case 4:
+          Ins = "brb\t";
+          Name = "iall";
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jthackray wrote:

Sure, happy to rewrite these.

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