Incremental mode now works for x64. The only difference

test/cctest/test-serialize.cc

 // Copyright 2007-2010 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 551 matching lines @@
   int paged_space_max = Page::kMaxHeapObjectSize;
 
   for (int size = 1000; size < 5 * MB; size += size >> 1) {
     size &= ~8;  // Round.
     int new_space_size = (size < new_space_max) ? size : new_space_max;
     int paged_space_size = (size < paged_space_max) ? size : paged_space_max;
     HEAP->ReserveSpace(
         new_space_size,
         paged_space_size,  // Old pointer space.
         paged_space_size,  // Old data space.
-        paged_space_size,  // Code space.
-        paged_space_size,  // Map space.
-        paged_space_size,  // Cell space.
+        HEAP->code_space()->RoundSizeDownToObjectAlignment(paged_space_size),
+        HEAP->map_space()->RoundSizeDownToObjectAlignment(paged_space_size),
+        HEAP->cell_space()->RoundSizeDownToObjectAlignment(paged_space_size),
         size);             // Large object space.
     LinearAllocationScope linear_allocation_scope;
     const int kSmallFixedArrayLength = 4;
     const int kSmallFixedArraySize =
         FixedArray::kHeaderSize + kSmallFixedArrayLength * kPointerSize;
     const int kSmallStringLength = 16;
     const int kSmallStringSize =
         (SeqAsciiString::kHeaderSize + kSmallStringLength +
         kObjectAlignmentMask) & ~kObjectAlignmentMask;
     const int kMapSize = Map::kSize;
@@ skipping 90 matching lines @@
 TEST(TestThatAlwaysFails) {
   bool ArtificialFailure = false;
   CHECK(ArtificialFailure);
 }
 
 
 DEPENDENT_TEST(DependentTestThatAlwaysFails, TestThatAlwaysSucceeds) {
   bool ArtificialFailure2 = false;
   CHECK(ArtificialFailure2);
 }