Backport @10366 to 3.6

src/utils.h

 // Copyright 2011 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 219 matching lines @@
   // Extracts the bit field from the value.
   static T decode(uint32_t value) {
     return static_cast<T>((value & kMask) >> shift);
   }
 };
 
 
 // ----------------------------------------------------------------------------
 // Hash function.
 
+static const uint32_t kZeroHashSeed = 0;
+
 // Thomas Wang, Integer Hash Functions.
 // http://www.concentric.net/~Ttwang/tech/inthash.htm
-static inline uint32_t ComputeIntegerHash(uint32_t key) {
+static inline uint32_t ComputeIntegerHash(uint32_t key, uint32_t seed) {
   uint32_t hash = key;
+  hash = hash ^ seed;
   hash = ~hash + (hash << 15);  // hash = (hash << 15) - hash - 1;
   hash = hash ^ (hash >> 12);
   hash = hash + (hash << 2);
   hash = hash ^ (hash >> 4);
   hash = hash * 2057;  // hash = (hash + (hash << 3)) + (hash << 11);
   hash = hash ^ (hash >> 16);
   return hash;
 }
 
 
 static inline uint32_t ComputePointerHash(void* ptr) {
   return ComputeIntegerHash(
-      static_cast<uint32_t>(reinterpret_cast<intptr_t>(ptr)));
+      static_cast<uint32_t>(reinterpret_cast<intptr_t>(ptr)),
+      v8::internal::kZeroHashSeed);
 }
 
 
 // ----------------------------------------------------------------------------
 // Miscellaneous
 
 // A static resource holds a static instance that can be reserved in
 // a local scope using an instance of Access.  Attempts to re-reserve
 // the instance will cause an error.
 template <typename T>
@@ skipping 644 matching lines @@
     ASSERT(element < static_cast<int>(sizeof(T) * CHAR_BIT));
     return 1 << element;
   }
 
   T bits_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_UTILS_H_