[llvm] CodeGen: Add RegisterClass by HwMode (PR #158269)

[Matt Arsenault via llvm-commits]

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@@ -187,7 +182,8 @@ CodeGenInstAlias::CodeGenInstAlias(const Record *R, const CodeGenTarget &T)
       PrintFatalError(R->getLoc(), "not enough arguments for instruction!");
 
     const Record *Op = OpInfo.Rec;
-    if (Op->isSubClassOf("Operand") && !OpInfo.MIOperandInfo->arg_empty()) {
+    if (Op->isSubClassOf("Operand") && OpInfo.MIOperandInfo &&
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arsenm wrote:

RegisterOperand is surprisingly not a subclass of Operand, only DAGOperand 

https://github.com/llvm/llvm-project/pull/158269