Changes based on review.

Author: aardvark179

lib/truffle/objspace.rb

@@ -152,11 +152,9 @@ def dump_all(output: :file)
   module_function :dump_all
 
   def memsize_of(object)
-    unless Truffle::ObjSpace.has_sizer?(object)
-      Truffle::ObjSpace.memsize_of(object)
-    else
-      Truffle::ObjSpace.memsize_of(object) + Truffle::ObjSpace.sizer(object).call
-    end
+    size = Truffle::ObjSpace.memsize_of(object)
+
+    size + Truffle::ObjSpace.sizer(object).call unless Truffle::ObjSpace.sizer(object).nil?
   end
   module_function :memsize_of
 

src/main/java/org/truffleruby/stdlib/ObjSpaceNodes.java

@@ -71,25 +71,14 @@ public int memsize(Object object) {
         }
     }
 
-    @CoreMethod(names = "has_sizer?", isModuleFunction = true, required = 1)
-    public abstract static class HasMemSizer extends CoreMethodArrayArgumentsNode {
-
-        @Child private ReadObjectFieldNode setSizerNode = ReadObjectFieldNodeGen.create(Layouts.MEMSIZER_IDENTIFIER, nil());
-
-        @Specialization
-        public boolean hasSizer(DynamicObject object) {
-            return setSizerNode.execute(object) != nil();
-        }
-    }
-
     @CoreMethod(names = "sizer", isModuleFunction = true, required = 1)
     public abstract static class GetMemSizer extends CoreMethodArrayArgumentsNode {
 
-        @Child private ReadObjectFieldNode setSizerNode = ReadObjectFieldNodeGen.create(Layouts.MEMSIZER_IDENTIFIER, nil());
+        @Child private ReadObjectFieldNode readSizerNode = ReadObjectFieldNodeGen.create(Layouts.MEMSIZER_IDENTIFIER, nil());
 
         @Specialization
         public Object hasSizer(DynamicObject object) {
-            return setSizerNode.execute(object);
+            return readSizerNode.execute(object);
         }
     }