changeset 6343:c02077c4b79c

8032536: JVM resolves wrong method in some unusual cases Summary: Handle package private case Reviewed-by: coleenp, acorn, jdn
author hseigel
date Tue, 04 Mar 2014 15:46:33 -0500
parents c28dffbb1d74
children cc7a96a360d0
files src/share/vm/oops/klassVtable.cpp
diffstat 1 files changed, 26 insertions(+), 5 deletions(-) [+]
line wrap: on
line diff
--- a/src/share/vm/oops/klassVtable.cpp	Wed Feb 26 22:07:40 2014 -0800
+++ b/src/share/vm/oops/klassVtable.cpp	Tue Mar 04 15:46:33 2014 -0500
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -249,6 +249,17 @@
 // For bytecodes not produced by javac together it is possible that a method does not override
 // the superclass's method, but might indirectly override a super-super class's vtable entry
 // If none found, return a null superk, else return the superk of the method this does override
+// For public and protected methods: if they override a superclass, they will
+// also be overridden themselves appropriately.
+// Private methods do not override and are not overridden.
+// Package Private methods are trickier:
+// e.g. P1.A, pub m
+// P2.B extends A, package private m
+// P1.C extends B, public m
+// P1.C.m needs to override P1.A.m and can not override P2.B.m
+// Therefore: all package private methods need their own vtable entries for
+// them to be the root of an inheritance overriding decision
+// Package private methods may also override other vtable entries
 InstanceKlass* klassVtable::find_transitive_override(InstanceKlass* initialsuper, methodHandle target_method,
                             int vtable_index, Handle target_loader, Symbol* target_classname, Thread * THREAD) {
   InstanceKlass* superk = initialsuper;
@@ -396,8 +407,11 @@
                              target_classname, THREAD))
                              != (InstanceKlass*)NULL))))
         {
-        // overriding, so no new entry
-        allocate_new = false;
+        // Package private methods always need a new entry to root their own
+        // overriding. They may also override other methods.
+        if (!target_method()->is_package_private()) {
+          allocate_new = false;
+        }
 
         if (checkconstraints) {
         // Override vtable entry if passes loader constraint check
@@ -541,8 +555,9 @@
                                          AccessFlags class_flags,
                                          TRAPS) {
   if (class_flags.is_interface()) {
-    // Interfaces do not use vtables, so there is no point to assigning
-    // a vtable index to any of their methods.  If we refrain from doing this,
+    // Interfaces do not use vtables, except for java.lang.Object methods,
+    // so there is no point to assigning
+    // a vtable index to any of their local methods.  If we refrain from doing this,
     // we can use Method::_vtable_index to hold the itable index
     return false;
   }
@@ -580,6 +595,12 @@
     return true;
   }
 
+  // Package private methods always need a new entry to root their own
+  // overriding. This allows transitive overriding to work.
+  if (target_method()->is_package_private()) {
+    return true;
+  }
+
   // search through the super class hierarchy to see if we need
   // a new entry
   ResourceMark rm;