More compact string representation on 64 bit.

runtime/vm/globals.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef RUNTIME_VM_GLOBALS_H_
 #define RUNTIME_VM_GLOBALS_H_
 
 // This file contains global definitions for the VM library only. Anything that
 // is more globally useful should be added to 'vm/globals.h'.
 
@@ skipping 26 matching lines @@
 
 // The expression ARRAY_SIZE(array) is a compile-time constant of type
 // size_t which represents the number of elements of the given
 // array. You should only use ARRAY_SIZE on statically allocated
 // arrays.
 #define ARRAY_SIZE(array)                                                      \
   ((sizeof(array) / sizeof(*(array))) /                                        \
    static_cast<intptr_t>(!(sizeof(array) % sizeof(*(array)))))  // NOLINT
 
 
+#if defined(ARCH_IS_64_BIT)
+#define HASH_IN_OBJECT_HEADER 1
+#endif
+
 // The expression OFFSET_OF(type, field) computes the byte-offset of
 // the specified field relative to the containing type.
 //
 // The expression OFFSET_OF_RETURNED_VALUE(type, accessor) computes the
 // byte-offset of the return value of the accessor to the containing type.
 //
 // None of these use 0 or NULL, which causes a problem with the compiler
 // warnings we have enabled (which is also why 'offsetof' doesn't seem to work).
 // The workaround is to use the non-zero value kOffsetOfPtr.
 const intptr_t kOffsetOfPtr = 32;
@@ skipping 61 matching lines @@
 
 // Assume GCC-compatible builtins.
 #define COPY_FP_REGISTER(fp)                                                   \
   fp = reinterpret_cast<uintptr_t>(__builtin_frame_address(0));
 
 #endif  // !defined(HOST_OS_WINDOWS))
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_GLOBALS_H_