Another round of cleanups for http://www.dartbug.com/15922

runtime/platform/utils.cc

 // 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.
 
 #include "platform/utils.h"
 
 namespace dart {
 
 // Implementation is from "Hacker's Delight" by Henry S. Warren, Jr.,
 // figure 3-3, page 48, where the function is called clp2.
-uint32_t Utils::RoundUpToPowerOfTwo(uint32_t x) {
+uintptr_t Utils::RoundUpToPowerOfTwo(uintptr_t x) {
   x = x - 1;
   x = x | (x >> 1);
   x = x | (x >> 2);
   x = x | (x >> 4);
   x = x | (x >> 8);
   x = x | (x >> 16);
+#if defined(ARCH_IS_64_BIT)
+  x = x | (x >> 32);
+#endif  // defined(ARCH_IS_64_BIT)
   return x + 1;
 }
 
 
 // Implementation is from "Hacker's Delight" by Henry S. Warren, Jr.,
 // figure 5-2, page 66, where the function is called pop.
 int Utils::CountOneBits(uint32_t x) {
   x = x - ((x >> 1) & 0x55555555);
   x = (x & 0x33333333) + ((x >> 2) & 0x33333333);
   x = (x + (x >> 4)) & 0x0F0F0F0F;
@@ skipping 65 matching lines @@
   a = (a ^ 0xc761c23c) ^ (a >> 19);
   a = (a + 0x165667b1) + (a << 5);
   a = (a + 0xd3a2646c) ^ (a << 9);
   a = (a + 0xfd7046c5) + (a << 3);
   a = (a ^ 0xb55a4f09) ^ (a >> 16);
   return static_cast<uint32_t>(a);
 }
 
 
 }  // namespace dart