Using unsigned shifts and masks when dealing with 64-bit addresses.

include/v8.h

 // Copyright 2007-2009 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 3349 matching lines @@
   static const int kSmiShiftSize = 0;
   static const int kSmiValueSize = 31;
   static inline int SmiToInt(internal::Object* value) {
     int shift_bits = kSmiTagSize + kSmiShiftSize;
     // Throw away top 32 bits and shift down (requires >> to be sign extending).
     return static_cast<int>(reinterpret_cast<intptr_t>(value)) >> shift_bits;
   }
 
   // For 32-bit systems any 2 bytes aligned pointer can be encoded as smi
   // with a plain reinterpret_cast.
-  static const intptr_t kEncodablePointerMask = 0x1;
+  static const uintptr_t kEncodablePointerMask = 0x1;
   static const int kPointerToSmiShift = 0;
 };
 
 // Smi constants for 64-bit systems.
 template <> struct SmiTagging<8> {
   static const int kSmiShiftSize = 31;
   static const int kSmiValueSize = 32;
   static inline int SmiToInt(internal::Object* value) {
     int shift_bits = kSmiTagSize + kSmiShiftSize;
     // Shift down and throw away top 32 bits.
     return static_cast<int>(reinterpret_cast<intptr_t>(value) >> shift_bits);
   }
 
   // To maximize the range of pointers that can be encoded
   // in the available 32 bits, we require them to be 8 bytes aligned.
   // This gives 2 ^ (32 + 3) = 32G address space covered.
   // It might be not enough to cover stack allocated objects on some platforms.
   static const int kPointerAlignment = 3;
 
-  static const intptr_t kEncodablePointerMask =
-      ~(intptr_t(0xffffffff) << kPointerAlignment);
+  static const uintptr_t kEncodablePointerMask =
+      ~(uintptr_t(0xffffffff) << kPointerAlignment);
 
   static const int kPointerToSmiShift =
       kSmiTagSize + kSmiShiftSize - kPointerAlignment;
 };
 
 typedef SmiTagging<kApiPointerSize> PlatformSmiTagging;
 const int kSmiShiftSize = PlatformSmiTagging::kSmiShiftSize;
 const int kSmiValueSize = PlatformSmiTagging::kSmiValueSize;
-const intptr_t kEncodablePointerMask =
+const uintptr_t kEncodablePointerMask =
     PlatformSmiTagging::kEncodablePointerMask;
 const int kPointerToSmiShift = PlatformSmiTagging::kPointerToSmiShift;
 
 template <size_t ptr_size> struct InternalConstants;
 
 // Internal constants for 32-bit systems.
 template <> struct InternalConstants<4> {
   static const int kStringResourceOffset = 3 * kApiPointerSize;
 };
 
@@ skipping 39 matching lines @@
     return PlatformSmiTagging::SmiToInt(value);
   }
 
   static inline int GetInstanceType(internal::Object* obj) {
     typedef internal::Object O;
     O* map = ReadField<O*>(obj, kHeapObjectMapOffset);
     return ReadField<uint8_t>(map, kMapInstanceTypeOffset);
   }
 
   static inline void* GetExternalPointerFromSmi(internal::Object* value) {
-    const intptr_t address = reinterpret_cast<intptr_t>(value);
+    const uintptr_t address = reinterpret_cast<uintptr_t>(value);
     return reinterpret_cast<void*>(address >> kPointerToSmiShift);
   }
 
   static inline void* GetExternalPointer(internal::Object* obj) {
     if (HasSmiTag(obj)) {
       return GetExternalPointerFromSmi(obj);
     } else if (GetInstanceType(obj) == kProxyType) {
       return ReadField<void*>(obj, kProxyProxyOffset);
     } else {
       return NULL;
@@ skipping 352 matching lines @@
 
 
 }  // namespace v8
 
 
 #undef V8EXPORT
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_