[llvm] [TableGen][GISel] Reuse `importNodeRenderer` for `OperandWithDefaultOps` (PR #121285)

[Matt Arsenault via llvm-commits]

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@@ -1300,11 +1299,24 @@ Error GlobalISelEmitter::importLeafNodeRenderer(
   if (const auto *DI = dyn_cast<DefInit>(N.getLeafValue())) {
     const Record *R = DI->getDef();
 
-    if (R->isSubClassOf("Register")) {
+    if (R->isSubClassOf("Register") || R->getName() == "zero_reg") {
       MIBuilder.addRenderer<AddRegisterRenderer>(Target, R);
       return Error::success();
     }
 
+    if (R->getName() == "undef_tied_input") {
+      std::optional<LLTCodeGen> OpTyOrNone = MVTToLLT(N.getSimpleType(0));
+      unsigned TempRegID = M.allocateTempRegID();
+      M.insertAction<MakeTempRegisterAction>(InsertPt, *OpTyOrNone, TempRegID);
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arsenm wrote:

Unchecked optional us? 

https://github.com/llvm/llvm-project/pull/121285