Reland "Precisely sweep scan on scavenge pages and use heap iterator to iterate over them."

src/spaces.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/base/platform/platform.h"
 #include "src/full-codegen.h"
 #include "src/macro-assembler.h"
 #include "src/mark-compact.h"
 #include "src/msan.h"
 
 namespace v8 {
 namespace internal {
 
 
 // ----------------------------------------------------------------------------
 // HeapObjectIterator
 
 HeapObjectIterator::HeapObjectIterator(PagedSpace* space) {
+  // Check that we actually can iterate this space.
+  ASSERT(space->is_iterable());
+
   // You can't actually iterate over the anchor page.  It is not a real page,
   // just an anchor for the double linked page list.  Initialize as if we have
   // reached the end of the anchor page, then the first iteration will move on
   // to the first page.
   Initialize(space,
              NULL,
              NULL,
              kAllPagesInSpace,
              NULL);
 }
 
 
 HeapObjectIterator::HeapObjectIterator(PagedSpace* space,
                                        HeapObjectCallback size_func) {
+  // Check that we actually can iterate this space.
+  ASSERT(space->is_iterable());
+
   // You can't actually iterate over the anchor page.  It is not a real page,
   // just an anchor for the double linked page list.  Initialize the current
   // address and end as NULL, then the first iteration will move on
   // to the first page.
   Initialize(space,
              NULL,
              NULL,
              kAllPagesInSpace,
              size_func);
 }
@@ skipping 14 matching lines @@
              kOnePageOnly,
              size_func);
   ASSERT(page->WasSweptPrecisely());
 }
 
 
 void HeapObjectIterator::Initialize(PagedSpace* space,
                                     Address cur, Address end,
                                     HeapObjectIterator::PageMode mode,
                                     HeapObjectCallback size_f) {
-  // Check that we actually can iterate this space.
-  ASSERT(space->is_iterable());
-
   space_ = space;
   cur_addr_ = cur;
   cur_end_ = end;
   page_mode_ = mode;
   size_func_ = size_f;
 }
 
 
 // We have hit the end of the page and should advance to the next block of
 // objects.  This happens at the end of the page.
@@ skipping 3056 matching lines @@
     object->ShortPrint();
     PrintF("\n");
   }
   printf(" --------------------------------------\n");
   printf(" Marked: %x, LiveCount: %x\n", mark_size, LiveBytes());
 }
 
 #endif  // DEBUG
 
 } }  // namespace v8::internal