Revert r1900, r1897 and r1895 which are all gc changes. The changes...

src/spaces.h

Index: src/spaces.h
===================================================================
--- src/spaces.h	(revision 1910)
+++ src/spaces.h	(working copy)
@@ -511,22 +511,11 @@
 //
 // A HeapObjectIterator iterates objects from a given address to the
 // top of a space. The given address must be below the current
-// allocation pointer (space top). There are some caveats.
-//
-// (1) If the space top changes upward during iteration (because of
-//     allocating new objects), the iterator does not iterate objects
-//     above the original space top. The caller must create a new
-//     iterator starting from the old top in order to visit these new
-//     objects.
-//
-// (2) If new objects are allocated below the original allocation top
-//     (e.g., free-list allocation in paged spaces), the new objects
-//     may or may not be iterated depending on their position with
-//     respect to the current point of iteration.
-//
-// (3) The space top should not change downward during iteration,
-//     otherwise the iterator will return not-necessarily-valid
-//     objects.
+// allocation pointer (space top). If the space top changes during
+// iteration (because of allocating new objects), the iterator does
+// not iterate new objects. The caller function must create a new
+// iterator starting from the old top in order to visit these new
+// objects. Heap::Scavenage() is such an example.
 
 class HeapObjectIterator: public ObjectIterator {
  public:
@@ -570,35 +559,17 @@
 
 
 // -----------------------------------------------------------------------------
-// A PageIterator iterates the pages in a paged space.
+// A PageIterator iterates pages in a space.
 //
 // The PageIterator class provides three modes for iterating pages in a space:
-//   PAGES_IN_USE iterates pages containing allocated objects.
-//   PAGES_USED_BY_MC iterates pages that hold relocated objects during a
-//                    mark-compact collection.
+//   PAGES_IN_USE iterates pages that are in use by the allocator;
+//   PAGES_USED_BY_GC iterates pages that hold relocated objects during a
+//                    mark-compact collection;
 //   ALL_PAGES iterates all pages in the space.
-//
-// There are some caveats.
-//
-// (1) If the space expands during iteration, new pages will not be
-//     returned by the iterator in any mode.
-//
-// (2) If new objects are allocated during iteration, they will appear
-//     in pages returned by the iterator.  Allocation may cause the
-//     allocation pointer or MC allocation pointer in the last page to
-//     change between constructing the iterator and iterating the last
-//     page.
-//
-// (3) The space should not shrink during iteration, otherwise the
-//     iterator will return deallocated pages.
 
 class PageIterator BASE_EMBEDDED {
  public:
-  enum Mode {
-    PAGES_IN_USE,
-    PAGES_USED_BY_MC,
-    ALL_PAGES
-  };
+  enum Mode {PAGES_IN_USE, PAGES_USED_BY_MC, ALL_PAGES};
 
   PageIterator(PagedSpace* space, Mode mode);
 
@@ -606,9 +577,8 @@
   inline Page* next();
 
  private:
-  PagedSpace* space_;
-  Page* prev_page_;  // Previous page returned.
-  Page* stop_page_;  // Page to stop at (last page returned by the iterator).
+  Page* cur_page_;  // next page to return
+  Page* stop_page_;  // page where to stop
 };
 
 
@@ -839,10 +809,6 @@
   // The first page in this space.
   Page* first_page_;
 
-  // The last page in this space.  Initially set in Setup, updated in
-  // Expand and Shrink.
-  Page* last_page_;
-
   // Normal allocation information.
   AllocationInfo allocation_info_;