--- a/src/share/vm/code/dependencies.hpp	Tue Mar 11 15:34:06 2014 +0100
+++ b/src/share/vm/code/dependencies.hpp	Wed Mar 12 13:30:08 2014 +0100
@@ -32,6 +32,7 @@
 #include "code/compressedStream.hpp"
 #include "code/nmethod.hpp"
 #include "utilities/growableArray.hpp"
+#include "utilities/hashtable.hpp"
 
 //** Dependencies represent assertions (approximate invariants) within
 // the runtime system, e.g. class hierarchy changes.  An example is an
@@ -570,6 +571,9 @@
     bool next();
 
     DepType type()               { return _type; }
+    bool has_oop_argument()      { return type() == call_site_target_value; }
+    uintptr_t get_identifier(int i);
+
     int argument_count()         { return dep_args(type()); }
     int argument_index(int i)    { assert(0 <= i && i < argument_count(), "oob");
                                    return _xi[i]; }
@@ -613,6 +617,30 @@
 };
 
 
+class DependencySignature : public GenericHashtableEntry<DependencySignature, ResourceObj> {
+ private:
+  int                   _args_count;
+  uintptr_t             _argument_hash[Dependencies::max_arg_count];
+  Dependencies::DepType _type;
+
+ public:
+  DependencySignature(Dependencies::DepStream& dep) {
+    _args_count = dep.argument_count();
+    _type = dep.type();
+    for (int i = 0; i < _args_count; i++) {
+      _argument_hash[i] = dep.get_identifier(i);
+    }
+  }
+
+  bool equals(DependencySignature* sig) const;
+  uintptr_t key() const { return _argument_hash[0] >> 2; }
+
+  int args_count()             const { return _args_count; }
+  uintptr_t arg(int idx)       const { return _argument_hash[idx]; }
+  Dependencies::DepType type() const { return _type; }
+};
+
+
 // Every particular DepChange is a sub-class of this class.
 class DepChange : public StackObj {
  public: