[NFC] Add emitAndAddMethodList to replace several similar methods. (swiftlang#29207)

Author: varungandhi-apple

lib/IRGen/GenClass.cpp

@@ -1229,9 +1229,9 @@ namespace {
       //   const class_t *theClass;
       fields.add(getClassMetadataRef());
       //   const method_list_t *instanceMethods;
-      fields.add(buildInstanceMethodList());
+      emitAndAddMethodList(fields, MethodListKind::InstanceMethods);
       //   const method_list_t *classMethods;
-      fields.add(buildClassMethodList());
+      emitAndAddMethodList(fields, MethodListKind::ClassMethods);
       //   const protocol_list_t *baseProtocols;
       fields.add(buildProtocolList());
       //   const property_list_t *properties;
@@ -1264,13 +1264,13 @@ namespace {
       //   const protocol_list_t *baseProtocols;
       fields.add(buildProtocolList());
       //   const method_list_t *requiredInstanceMethods;
-      fields.add(buildInstanceMethodList());
+      emitAndAddMethodList(fields, MethodListKind::InstanceMethods);
       //   const method_list_t *requiredClassMethods;
-      fields.add(buildClassMethodList());
+      emitAndAddMethodList(fields, MethodListKind::ClassMethods);
       //   const method_list_t *optionalInstanceMethods;
-      fields.add(buildOptInstanceMethodList());
+      emitAndAddMethodList(fields, MethodListKind::OptionalInstanceMethods);
       //   const method_list_t *optionalClassMethods;
-      fields.add(buildOptClassMethodList());
+      emitAndAddMethodList(fields, MethodListKind::OptionalClassMethods);
       //   const property_list_t *properties;
       fields.add(buildPropertyList(ForClass));
 
@@ -1348,7 +1348,8 @@ namespace {
       b.add(buildName());
 
       //   const method_list_t *baseMethods;
-      b.add(forMeta ? buildClassMethodList() : buildInstanceMethodList());
+      emitAndAddMethodList(b, forMeta ? MethodListKind::ClassMethods
+                                      : MethodListKind::InstanceMethods);
 
       //   const protocol_list_t *baseProtocols;
       // Apparently, this list is the same in the class and the metaclass.
@@ -1566,28 +1567,43 @@ namespace {
       llvm_unreachable("not a class, category, or protocol?!");
     }
 
-    llvm::Constant *buildClassMethodList() {
-      return buildMethodList(ClassMethods,
-                             chooseNamePrefix("_CLASS_METHODS_",
-                                              "_CATEGORY_CLASS_METHODS_",
-                                              "_PROTOCOL_CLASS_METHODS_"));
-    }
-
-    llvm::Constant *buildInstanceMethodList() {
-      return buildMethodList(InstanceMethods,
-                             chooseNamePrefix("_INSTANCE_METHODS_",
-                                              "_CATEGORY_INSTANCE_METHODS_",
-                                              "_PROTOCOL_INSTANCE_METHODS_"));
-    }
 
-    llvm::Constant *buildOptClassMethodList() {
-      return buildMethodList(OptClassMethods,
-                             "_PROTOCOL_CLASS_METHODS_OPT_");
-    }
+    enum class MethodListKind : uint8_t {
+      ClassMethods,
+      InstanceMethods,
+      OptionalClassMethods,
+      OptionalInstanceMethods
+    };
 
-    llvm::Constant *buildOptInstanceMethodList() {
-      return buildMethodList(OptInstanceMethods,
-                             "_PROTOCOL_INSTANCE_METHODS_OPT_");
+    /// Emit the method list and add the pointer to the `builder`.
+    void emitAndAddMethodList(ConstantInitBuilder::StructBuilder &builder,
+                              MethodListKind kind) {
+      ArrayRef<MethodDescriptor> methods;
+      StringRef namePrefix;
+      switch (kind) {
+      case MethodListKind::ClassMethods:
+        methods = ClassMethods;
+        namePrefix = chooseNamePrefix("_CLASS_METHODS_",
+                                      "_CATEGORY_CLASS_METHODS_",
+                                      "_PROTOCOL_CLASS_METHODS_");
+        break;
+      case MethodListKind::InstanceMethods:
+        methods = InstanceMethods;
+        namePrefix = chooseNamePrefix("_INSTANCE_METHODS_",
+                                      "_CATEGORY_INSTANCE_METHODS_",
+                                      "_PROTOCOL_INSTANCE_METHODS_");
+        break;
+      case MethodListKind::OptionalClassMethods:
+        methods = OptClassMethods;
+        namePrefix = "_PROTOCOL_CLASS_METHODS_OPT_";
+        break;
+      case MethodListKind::OptionalInstanceMethods:
+        methods = OptInstanceMethods;
+        namePrefix = "_PROTOCOL_INSTANCE_METHODS_OPT_";
+        break;
+      }
+      llvm::Constant *methodListPtr = buildMethodList(methods, namePrefix);
+      builder.add(methodListPtr);
     }
 
     llvm::Constant *buildOptExtendedMethodTypes() {