[CIR] Clean up enum attributes (llvm#144999)

This mirrors incubator changes from llvm/clangir#1678

- Create CIR specific EnumAttr bases and prefix enum attributes with CIR_ that automatically puts enum to cir namespace

- Removes unnecessary enum case definitions

- Unifies naming of enum values to use capitals consistently and make enumerations to start from 0

Author: xlauko

clang/include/clang/CIR/Dialect/IR/CIRAttrs.td

@@ -47,6 +47,16 @@ class CIR_I32EnumAttr<string name, string summary, list<I32EnumAttrCase> cases>
   let cppNamespace = "::cir";
 }
 
+class CIR_I64EnumAttr<string name, string summary, list<I64EnumAttrCase> cases>
+    : I64EnumAttr<name, summary, cases> {
+  let cppNamespace = "::cir";
+}
+
+class CIR_EnumAttr<EnumAttrInfo info, string name = "", list<Trait> traits = []>
+    : EnumAttr<CIR_Dialect, info, name, traits> {
+  let assemblyFormat = "`<` $value `>`";
+}
+
 class CIRUnitAttr<string name, string attrMnemonic, list<Trait> traits = []>
     : CIR_Attr<name, attrMnemonic, traits> {
   let returnType = "bool";
@@ -330,36 +340,33 @@ def ConstComplexAttr : CIR_Attr<"ConstComplex", "const_complex",
 // VisibilityAttr
 //===----------------------------------------------------------------------===//
 
-def CIR_VisibilityKind : I32EnumAttr<"VisibilityKind", "C/C++ visibility", [
-  I32EnumAttrCase<"Default", 1, "default">,
-  I32EnumAttrCase<"Hidden", 2, "hidden">,
-  I32EnumAttrCase<"Protected", 3, "protected">
+def CIR_VisibilityKind : CIR_I32EnumAttr<"VisibilityKind", "C/C++ visibility", [
+  I32EnumAttrCase<"Default", 0, "default">,
+  I32EnumAttrCase<"Hidden", 1, "hidden">,
+  I32EnumAttrCase<"Protected", 2, "protected">
 ]> {
   let genSpecializedAttr = 0;
-  let cppNamespace = "::cir";
 }
 
-def CIR_VisibilityAttr : CIR_Attr<"Visibility", "visibility"> {
+def CIR_VisibilityAttr : CIR_EnumAttr<CIR_VisibilityKind, "visibility"> {
   let summary = "Visibility attribute";
   let description = [{
     Visibility attributes.
   }];
-  let parameters = (ins "VisibilityKind":$value);
 
-  let assemblyFormat = [{
-    $value
-  }];
+  let cppClassName = "VisibilityAttr";
 
+  let skipDefaultBuilders = 1;
   let builders = [
-    AttrBuilder<(ins CArg<"VisibilityKind", "cir::VisibilityKind::Default">:$value), [{
+    AttrBuilder<(ins CArg<"VisibilityKind",
+                          "cir::VisibilityKind::Default">:$value), [{
       return $_get($_ctxt, value);
     }]>
   ];
 
-  let skipDefaultBuilders = 1;
-
-  // Make DefaultValuedAttr accept VisibilityKind as default value ($0).
-  let constBuilderCall = "cir::VisibilityAttr::get($_builder.getContext(), $0)";
+  let assemblyFormat = [{
+    $value
+  }];
 
   let extraClassDeclaration = [{
     bool isDefault() const { return getValue() == VisibilityKind::Default; };