Add an option to skip merging anonymous classes

Summary:
## Context

In previous AB tests, we enabled merging more anonymous classes in IntraDexClassMerging while making sure that we emit the correct method profile for the merged symbols. As the next step, we want to

Reviewed By: wsanville

Differential Revision: D70356894

fbshipit-source-id: 3b8d21d0658778c20d6356d4d87cda6e43393379

opt/class-merging/ClassMergingPass.cpp

@@ -130,6 +130,8 @@ void ClassMergingPass::bind_config() {
   trait(Traits::Pass::unique, true);
   bool use_stable_shape_names;
   bind("use_stable_shape_names", false, use_stable_shape_names);
+  bool skip_anonymous_classes;
+  bind("skip_anonymous_classes", false, skip_anonymous_classes);
 
   // load model specifications
   std::vector<Json::Value> models;
@@ -247,6 +249,7 @@ void ClassMergingPass::bind_config() {
       model.process_method_meta = process_method_meta;
       model.max_num_dispatch_target = m_max_num_dispatch_target;
       model.use_stable_shape_names = use_stable_shape_names;
+      model.skip_anonymous_classes = skip_anonymous_classes;
       // Assume config based models are all generated code.
       model_spec.get("is_generated_code", true, model.is_generated_code);
 

service/class-merging/ClassMerging.cpp

@@ -63,7 +63,11 @@ void load_roots_subtypes_as_merging_targets(const TypeSystem& type_system,
       const auto& implementors = type_system.get_implementors(*root);
       for (auto impl_type : implementors) {
         auto impl_cls = type_class(impl_type);
-        // Note: Bellow is to simply make the logic unchange after the
+        if (spec->skip_anonymous_classes &&
+            klass::maybe_anonymous_class(impl_cls)) {
+          continue;
+        }
+        // Note: Below is to simply make the logic unchange after the
         // refactoring.
         // Find the first internal class at the top of the type
         // hierarchy of the impl_cls. if it extends java.lang.Object and
@@ -86,7 +90,17 @@ void load_roots_subtypes_as_merging_targets(const TypeSystem& type_system,
       }
       root = spec->roots.erase(root);
     } else {
-      type_system.get_all_children(*root, merging_targets_set);
+      TypeSet children;
+      type_system.get_all_children(*root, children);
+
+      for (const auto* child : children) {
+        const auto* child_cls = type_class(child);
+        if (spec->skip_anonymous_classes &&
+            klass::maybe_anonymous_class(child_cls)) {
+          continue;
+        }
+        merging_targets_set.insert(child);
+      }
       root++;
     }
   }

service/class-merging/Model.h

@@ -200,6 +200,8 @@ struct ModelSpec {
   bool use_stable_shape_names{false};
 
   bool mergeability_checks_use_of_const_class{false};
+
+  bool skip_anonymous_classes{false};
 };
 
 struct ModelStats {