src/share/classes/jdk/internal/org/objectweb/asm/ClassWriter.java

@@ -783,16 +783,34 @@
     public final void visitInnerClass(final String name,
             final String outerName, final String innerName, final int access) {
         if (innerClasses == null) {
             innerClasses = new ByteVector();
         }
+        // Sec. 4.7.6 of the JVMS states "Every CONSTANT_Class_info entry in the
+        // constant_pool table which represents a class or interface C that is
+        // not a package member must have exactly one corresponding entry in the
+        // classes array". To avoid duplicates we keep track in the intVal field
+        // of the Item of each CONSTANT_Class_info entry C whether an inner
+        // class entry has already been added for C (this field is unused for
+        // class entries, and changing its value does not change the hashcode
+        // and equality tests). If so we store the index of this inner class
+        // entry (plus one) in intVal. This hack allows duplicate detection in
+        // O(1) time.
+        Item nameItem = newClassItem(name);
+        if (nameItem.intVal == 0) {
         ++innerClassesCount;
-        innerClasses.putShort(name == null ? 0 : newClass(name));
+            innerClasses.putShort(nameItem.index);
         innerClasses.putShort(outerName == null ? 0 : newClass(outerName));
         innerClasses.putShort(innerName == null ? 0 : newUTF8(innerName));
         innerClasses.putShort(access);
+            nameItem.intVal = innerClassesCount;
+        } else {
+            // Compare the inner classes entry nameItem.intVal - 1 with the
+            // arguments of this method and throw an exception if there is a
+            // difference?
     }
+    }
 
     @Override
     public final FieldVisitor visitField(final int access, final String name,
             final String desc, final String signature, final Object value) {
         return new FieldWriter(this, access, name, desc, signature, value);