--- a/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/vmStructs_cms.hpp	Wed Nov 21 21:26:12 2012 -0500
+++ b/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/vmStructs_cms.hpp	Tue Nov 27 07:57:57 2012 -0800
@@ -65,8 +65,7 @@
   declare_toplevel_type(AFLBinaryTreeDictionary*)                         \
   declare_toplevel_type(LinearAllocBlock)                                 \
   declare_toplevel_type(FreeBlockDictionary<FreeChunk>)                   \
-  declare_type(AFLBinaryTreeDictionary, FreeBlockDictionary<FreeChunk>)   \
-            declare_type(AFLBinaryTreeDictionary, FreeBlockDictionary<FreeChunk>) \
+           declare_type(AFLBinaryTreeDictionary, FreeBlockDictionary<FreeChunk>)
 
 #define VM_INT_CONSTANTS_CMS(declare_constant)                            \
   declare_constant(Generation::ConcurrentMarkSweep)                       \

--- a/hotspot/src/share/vm/prims/jni.cpp	Wed Nov 21 21:26:12 2012 -0500
+++ b/hotspot/src/share/vm/prims/jni.cpp	Tue Nov 27 07:57:57 2012 -0800
@@ -5044,6 +5044,9 @@
 
 #include "gc_interface/collectedHeap.hpp"
 #include "utilities/quickSort.hpp"
+#if INCLUDE_VM_STRUCTS
+#include "runtime/vmStructs.hpp"
+#endif
 
 #define run_unit_test(unit_test_function_call)              \
   tty->print_cr("Running test: " #unit_test_function_call); \
@@ -5056,6 +5059,9 @@
     run_unit_test(CollectedHeap::test_is_in());
     run_unit_test(QuickSort::test_quick_sort());
     run_unit_test(AltHashing::test_alt_hash());
+#if INCLUDE_VM_STRUCTS
+    run_unit_test(VMStructs::test());
+#endif
     tty->print_cr("All internal VM tests passed");
   }
 }

--- a/hotspot/src/share/vm/runtime/vmStructs.cpp	Wed Nov 21 21:26:12 2012 -0500
+++ b/hotspot/src/share/vm/runtime/vmStructs.cpp	Tue Nov 27 07:57:57 2012 -0800
@@ -2107,8 +2107,7 @@
   declare_toplevel_type(FreeList<Metablock>*)                             \
   declare_toplevel_type(FreeList<Metablock>)                              \
   declare_toplevel_type(MetablockTreeDictionary*)                         \
-  declare_type(MetablockTreeDictionary, FreeBlockDictionary<Metablock>)   \
-              declare_type(MetablockTreeDictionary, FreeBlockDictionary<Metablock>)
+           declare_type(MetablockTreeDictionary, FreeBlockDictionary<Metablock>)
 
 
   /* NOTE that we do not use the last_entry() macro here; it is used  */
@@ -3215,3 +3214,17 @@
 void vmStructs_init() {
   debug_only(VMStructs::init());
 }
+
+#ifndef PRODUCT
+void VMStructs::test() {
+  // Check for duplicate entries in type array
+  for (int i = 0; localHotSpotVMTypes[i].typeName != NULL; i++) {
+    for (int j = i + 1; localHotSpotVMTypes[j].typeName != NULL; j++) {
+      if (strcmp(localHotSpotVMTypes[i].typeName, localHotSpotVMTypes[j].typeName) == 0) {
+        tty->print_cr("Duplicate entries for '%s'", localHotSpotVMTypes[i].typeName);
+        assert(false, "Duplicate types in localHotSpotVMTypes array");
+      }
+    }
+  }
+}
+#endif

--- a/hotspot/src/share/vm/runtime/vmStructs.hpp	Wed Nov 21 21:26:12 2012 -0500
+++ b/hotspot/src/share/vm/runtime/vmStructs.hpp	Tue Nov 27 07:57:57 2012 -0800
@@ -123,6 +123,11 @@
   // the data structure (debug build only)
   static void init();
 
+#ifndef PRODUCT
+  // Execute unit tests
+  static void test();
+#endif
+
 private:
   // Look up a type in localHotSpotVMTypes using strcmp() (debug build only).
   // Returns 1 if found, 0 if not.