[llvm] [NFC][RootSignature] Use `llvm::EnumEntry` for serialization of Root Signature Elements (PR #144106)

[via llvm-commits]

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@@ -15,119 +15,117 @@
 #include "llvm/ADT/bit.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/Metadata.h"
+#include "llvm/Support/ScopedPrinter.h"
 
 namespace llvm {
 namespace hlsl {
 namespace rootsig {
 
-static raw_ostream &operator<<(raw_ostream &OS, const Register &Reg) {
-  switch (Reg.ViewType) {
-  case RegisterType::BReg:
-    OS << "b";
-    break;
-  case RegisterType::TReg:
-    OS << "t";
-    break;
-  case RegisterType::UReg:
-    OS << "u";
-    break;
-  case RegisterType::SReg:
-    OS << "s";
-    break;
-  }
-  OS << Reg.Number;
-  return OS;
+template <typename T>
+static StringRef getEnumName(const T Value, ArrayRef<EnumEntry<T>> Enums) {
+  for (const auto &EnumItem : Enums)
+    if (EnumItem.Value == Value)
+      return EnumItem.Name;
+  return "";
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joaosaffran wrote:

Maybe using `std::optional` can improve dealing with not found Enum values. IMHO, returning an empty string might lead to weird/annoying to debug issues.

https://github.com/llvm/llvm-project/pull/144106