ModuleFields#parentModule should not be CompilationFinal

Author: eregon

src/main/java/org/truffleruby/core/module/ModuleChain.java

@@ -9,12 +9,10 @@
  */
 package org.truffleruby.core.module;
 
-import com.oracle.truffle.api.CompilerDirectives.CompilationFinal;
-
 /** Either an IncludedModule, a RubyClass or a RubyModule. Private interface, do not use outside RubyModule. */
 public abstract class ModuleChain {
 
-    @CompilationFinal protected ModuleChain parentModule;
+    protected ModuleChain parentModule;
 
     public ModuleChain(ModuleChain parentModule) {
         this.parentModule = parentModule;

src/main/java/org/truffleruby/core/module/ModuleFields.java

@@ -177,7 +177,7 @@ public void updateAnonymousChildrenModules(RubyContext context) {
         }
     }
 
-    private boolean hasPrependedModules() {
+    public boolean hasPrependedModules() {
         return start.getParentModule() != this;
     }
 

src/main/java/org/truffleruby/language/methods/LookupMethodNode.java

@@ -89,7 +89,7 @@ protected InternalMethod lookupMethodUncached(
         // Lookup first in the metaclass as we are likely to find the method there
         final ModuleFields fields = metaClass.fields;
         InternalMethod topMethod;
-        if (noPrependedModulesProfile.profile(fields.getFirstModuleChain() == fields) &&
+        if (noPrependedModulesProfile.profile(!fields.hasPrependedModules()) &&
                 onMetaClassProfile.profile((topMethod = fields.getMethod(name)) != null) &&
                 !hasRefinementsProfile.profile(declarationContext != null && declarationContext.hasRefinements())) {
             method = topMethod;