--- a/src/share/vm/oops/methodDataOop.hpp	Tue Mar 11 11:25:13 2008 -0700
+++ b/src/share/vm/oops/methodDataOop.hpp	Tue Mar 11 19:00:38 2008 -0700
@@ -101,7 +101,8 @@
     virtual_call_data_tag,
     ret_data_tag,
     branch_data_tag,
-    multi_branch_data_tag
+    multi_branch_data_tag,
+    arg_info_data_tag
   };
 
   enum {
@@ -245,6 +246,7 @@
 class     BranchData;
 class   ArrayData;
 class     MultiBranchData;
+class     ArgInfoData;
 
 
 // ProfileData
@@ -376,6 +378,8 @@
   virtual bool is_BranchData()      { return false; }
   virtual bool is_ArrayData()       { return false; }
   virtual bool is_MultiBranchData() { return false; }
+  virtual bool is_ArgInfoData()     { return false; }
+
 
   BitData* as_BitData() {
     assert(is_BitData(), "wrong type");
@@ -413,6 +417,10 @@
     assert(is_MultiBranchData(), "wrong type");
     return is_MultiBranchData() ? (MultiBranchData*)this : NULL;
   }
+  ArgInfoData* as_ArgInfoData() {
+    assert(is_ArgInfoData(), "wrong type");
+    return is_ArgInfoData() ? (ArgInfoData*)this : NULL;
+  }
 
 
   // Subclass specific initialization
@@ -1047,6 +1055,33 @@
 #endif
 };
 
+class ArgInfoData : public ArrayData {
+
+public:
+  ArgInfoData(DataLayout* layout) : ArrayData(layout) {
+    assert(layout->tag() == DataLayout::arg_info_data_tag, "wrong type");
+  }
+
+  virtual bool is_ArgInfoData() { return true; }
+
+
+  int number_of_args() {
+    return array_len();
+  }
+
+  uint arg_modified(int arg) {
+    return array_uint_at(arg);
+  }
+
+  void set_arg_modified(int arg, uint val) {
+    array_set_int_at(arg, val);
+  }
+
+#ifndef PRODUCT
+  void print_data_on(outputStream* st);
+#endif
+};
+
 // methodDataOop
 //
 // A methodDataOop holds information which has been collected about
@@ -1183,6 +1218,9 @@
   // Find or create an extra ProfileData:
   ProfileData* bci_to_extra_data(int bci, bool create_if_missing);
 
+  // return the argument info cell
+  ArgInfoData *arg_info();
+
 public:
   static int header_size() {
     return sizeof(methodDataOopDesc)/wordSize;
@@ -1222,11 +1260,18 @@
   intx arg_local()                               { return _arg_local; }
   intx arg_stack()                               { return _arg_stack; }
   intx arg_returned()                            { return _arg_returned; }
+  uint arg_modified(int a)                       { ArgInfoData *aid = arg_info();
+                                                   assert(a >= 0 && a < aid->number_of_args(), "valid argument number");
+                                                   return aid->arg_modified(a); }
 
   void set_eflags(intx v)                        { _eflags = v; }
   void set_arg_local(intx v)                     { _arg_local = v; }
   void set_arg_stack(intx v)                     { _arg_stack = v; }
   void set_arg_returned(intx v)                  { _arg_returned = v; }
+  void set_arg_modified(int a, uint v)           { ArgInfoData *aid = arg_info();
+                                                   assert(a >= 0 && a < aid->number_of_args(), "valid argument number");
+
+                                                   aid->set_arg_modified(a, v); }
 
   void clear_escape_info()                       { _eflags = _arg_local = _arg_stack = _arg_returned = 0; }