Use architecture-specific alignment for hashing in Descriptor lookup cache.

src/heap.h

 // Copyright 2012 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 2377 matching lines @@
     for (int i = 0; i < kLength; ++i) {
       keys_[i].array = NULL;
       keys_[i].name = NULL;
       results_[i] = kAbsent;
     }
   }
 
   static int Hash(DescriptorArray* array, String* name) {
     // Uses only lower 32 bits if pointers are larger.
     uint32_t array_hash =
-        static_cast<uint32_t>(reinterpret_cast<uintptr_t>(array)) >> 2;
+        static_cast<uint32_t>(reinterpret_cast<uintptr_t>(array))
+            >> kPointerSizeLog2;
     uint32_t name_hash =
-        static_cast<uint32_t>(reinterpret_cast<uintptr_t>(name)) >> 2;
+        static_cast<uint32_t>(reinterpret_cast<uintptr_t>(name))
+            >> kPointerSizeLog2;
     return (array_hash ^ name_hash) % kLength;
   }
 
   static const int kLength = 64;
   struct Key {
     DescriptorArray* array;
     String* name;
   };
 
   Key keys_[kLength];
@@ skipping 354 matching lines @@
   AssertNoAllocation no_alloc;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG || LIVE_OBJECT_LIST
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_H_