[NFC][HLSL] Replace uses of getResourceName/printEnum (#152211)

Introduce the `enumToStringRef` enum into `ScopedPrinter.h` that
replicates `enumToString` behaviour, expect that instead of returning a
hex value string, it just returns an empty string. This allows us to
return a StringRef and easily check if an invalid enum was provided
based on the StringRef size

This then uses `enumToStringRef` to remove the redundant
`getResourceName` and `printEnum` functions.

Resolves: #151200.

Author: inbelic

llvm/include/llvm/Support/ScopedPrinter.h

@@ -107,6 +107,17 @@ std::string enumToString(T Value, ArrayRef<EnumEntry<TEnum>> EnumValues) {
   return utohexstr(Value, true);
 }
 
+/// Retrieves the Value's enum name.
+///
+/// Returns an empty StringRef when an invalid value is provided.
+template <typename T, typename TEnum>
+StringRef enumToStringRef(T Value, ArrayRef<EnumEntry<TEnum>> EnumValues) {
+  for (const EnumEntry<TEnum> &EnumItem : EnumValues)
+    if (EnumItem.Value == Value)
+      return EnumItem.AltName;
+  return "";
+}
+
 class LLVM_ABI ScopedPrinter {
 public:
   enum class ScopedPrinterKind {

llvm/lib/Frontend/HLSL/HLSLRootSignature.cpp

@@ -17,24 +17,6 @@ namespace llvm {
 namespace hlsl {
 namespace rootsig {
 
-template <typename T>
-static std::optional<StringRef> getEnumName(const T Value,
-                                            ArrayRef<EnumEntry<T>> Enums) {
-  for (const auto &EnumItem : Enums)
-    if (EnumItem.Value == Value)
-      return EnumItem.Name;
-  return std::nullopt;
-}
-
-template <typename T>
-static raw_ostream &printEnum(raw_ostream &OS, const T Value,
-                              ArrayRef<EnumEntry<T>> Enums) {
-  auto MaybeName = getEnumName(Value, Enums);
-  if (MaybeName)
-    OS << *MaybeName;
-  return OS;
-}
-
 template <typename T>
 static raw_ostream &printFlags(raw_ostream &OS, const T Value,
                                ArrayRef<EnumEntry<T>> Flags) {
@@ -46,9 +28,9 @@ static raw_ostream &printFlags(raw_ostream &OS, const T Value,
       if (FlagSet)
         OS << " | ";
 
-      auto MaybeFlag = getEnumName(T(Bit), Flags);
-      if (MaybeFlag)
-        OS << *MaybeFlag;
+      StringRef MaybeFlag = enumToStringRef(T(Bit), Flags);
+      if (!MaybeFlag.empty())
+        OS << MaybeFlag;
       else
         OS << "invalid: " << Bit;
 
@@ -70,43 +52,42 @@ static const EnumEntry<RegisterType> RegisterNames[] = {
 };
 
 static raw_ostream &operator<<(raw_ostream &OS, const Register &Reg) {
-  printEnum(OS, Reg.ViewType, ArrayRef(RegisterNames));
-  OS << Reg.Number;
+  OS << enumToStringRef(Reg.ViewType, ArrayRef(RegisterNames)) << Reg.Number;
 
   return OS;
 }
 
 static raw_ostream &operator<<(raw_ostream &OS,
                                const llvm::dxbc::ShaderVisibility &Visibility) {
-  printEnum(OS, Visibility, dxbc::getShaderVisibility());
+  OS << enumToStringRef(Visibility, dxbc::getShaderVisibility());
 
   return OS;
 }
 
 static raw_ostream &operator<<(raw_ostream &OS,
                                const llvm::dxbc::SamplerFilter &Filter) {
-  printEnum(OS, Filter, dxbc::getSamplerFilters());
+  OS << enumToStringRef(Filter, dxbc::getSamplerFilters());
 
   return OS;
 }
 
 static raw_ostream &operator<<(raw_ostream &OS,
                                const dxbc::TextureAddressMode &Address) {
-  printEnum(OS, Address, dxbc::getTextureAddressModes());
+  OS << enumToStringRef(Address, dxbc::getTextureAddressModes());
 
   return OS;
 }
 
 static raw_ostream &operator<<(raw_ostream &OS,
                                const dxbc::ComparisonFunc &CompFunc) {
-  printEnum(OS, CompFunc, dxbc::getComparisonFuncs());
+  OS << enumToStringRef(CompFunc, dxbc::getComparisonFuncs());
 
   return OS;
 }
 
 static raw_ostream &operator<<(raw_ostream &OS,
                                const dxbc::StaticBorderColor &BorderColor) {
-  printEnum(OS, BorderColor, dxbc::getStaticBorderColors());
+  OS << enumToStringRef(BorderColor, dxbc::getStaticBorderColors());
 
   return OS;
 }
@@ -119,8 +100,8 @@ static const EnumEntry<dxil::ResourceClass> ResourceClassNames[] = {
 };
 
 static raw_ostream &operator<<(raw_ostream &OS, const ClauseType &Type) {
-  printEnum(OS, dxil::ResourceClass(llvm::to_underlying(Type)),
-            ArrayRef(ResourceClassNames));
+  OS << enumToStringRef(dxil::ResourceClass(llvm::to_underlying(Type)),
+                        ArrayRef(ResourceClassNames));
 
   return OS;
 }

llvm/lib/Frontend/HLSL/RootSignatureMetadata.cpp

@@ -58,13 +58,6 @@ static const EnumEntry<dxil::ResourceClass> ResourceClassNames[] = {
     {"Sampler", dxil::ResourceClass::Sampler},
 };
 
-static std::optional<StringRef> getResourceName(dxil::ResourceClass Class) {
-  for (const auto &ClassEnum : ResourceClassNames)
-    if (ClassEnum.Value == Class)
-      return ClassEnum.Name;
-  return std::nullopt;
-}
-
 namespace {
 
 // We use the OverloadVisit with std::visit to ensure the compiler catches if a
@@ -133,10 +126,11 @@ MDNode *MetadataBuilder::BuildRootConstants(const RootConstants &Constants) {
 
 MDNode *MetadataBuilder::BuildRootDescriptor(const RootDescriptor &Descriptor) {
   IRBuilder<> Builder(Ctx);
-  std::optional<StringRef> ResName =
-      getResourceName(dxil::ResourceClass(to_underlying(Descriptor.Type)));
-  assert(ResName && "Provided an invalid Resource Class");
-  SmallString<7> Name({"Root", *ResName});
+  StringRef ResName =
+      enumToStringRef(dxil::ResourceClass(to_underlying(Descriptor.Type)),
+                      ArrayRef(ResourceClassNames));
+  assert(!ResName.empty() && "Provided an invalid Resource Class");
+  SmallString<7> Name({"Root", ResName});
   Metadata *Operands[] = {
       MDString::get(Ctx, Name),
       ConstantAsMetadata::get(
@@ -174,11 +168,12 @@ MDNode *MetadataBuilder::BuildDescriptorTable(const DescriptorTable &Table) {
 MDNode *MetadataBuilder::BuildDescriptorTableClause(
     const DescriptorTableClause &Clause) {
   IRBuilder<> Builder(Ctx);
-  std::optional<StringRef> ResName =
-      getResourceName(dxil::ResourceClass(to_underlying(Clause.Type)));
-  assert(ResName && "Provided an invalid Resource Class");
+  StringRef ResName =
+      enumToStringRef(dxil::ResourceClass(to_underlying(Clause.Type)),
+                      ArrayRef(ResourceClassNames));
+  assert(!ResName.empty() && "Provided an invalid Resource Class");
   Metadata *Operands[] = {
-      MDString::get(Ctx, *ResName),
+      MDString::get(Ctx, ResName),
       ConstantAsMetadata::get(Builder.getInt32(Clause.NumDescriptors)),
       ConstantAsMetadata::get(Builder.getInt32(Clause.Reg.Number)),
       ConstantAsMetadata::get(Builder.getInt32(Clause.Space)),