Make stub cache hash work on X64 platform. Stub cache now works....

src/stub-cache.h

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 238 matching lines @@
         static_cast<uint32_t>(reinterpret_cast<uintptr_t>(name));
     // We always set the in_loop bit to zero when generating the lookup code
     // so do it here too so the hash codes match.
     uint32_t iflags =
         (static_cast<uint32_t>(flags) & ~Code::kFlagsICInLoopMask);
     uint32_t key = seed - string_low32bits + iflags;
     return key & ((kSecondaryTableSize - 1) << kHeapObjectTagSize);
   }
 
   // Compute the entry for a given offset in exactly the same way as
-  // we done in generated code. This makes it a lot easier to avoid
-  // making mistakes in the hashed offset computations.
+  // we do in generated code.  We generate an hash code that already
+  // ends in String::kHashShift 0s.  Then we shift it so it is a multiple
+  // of sizeof(Entry).  This makes it easier to avoid making mistakes
+  // in the hashed offset computations.
   static Entry* entry(Entry* table, int offset) {
+    const int shift_amount = kPointerSizeLog2 + 1 - String::kHashShift;
     return reinterpret_cast<Entry*>(
-        reinterpret_cast<Address>(table) + (offset << 1));
+        reinterpret_cast<Address>(table) + (offset << shift_amount));
   }
 };
 
 
 class SCTableReference {
  public:
   static SCTableReference keyReference(StubCache::Table table) {
     return SCTableReference(
         reinterpret_cast<Address>(&first_entry(table)->key));
   }
@@ skipping 278 matching lines @@
 
   const ParameterCount& arguments() { return arguments_; }
 
   Object* GetCode(PropertyType type, String* name);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_STUB_CACHE_H_