If a large object is truncated, also truncate the page.

runtime/vm/gc_sweeper.cc

Index: runtime/vm/gc_sweeper.cc
===================================================================
--- runtime/vm/gc_sweeper.cc	(revision 37758)
+++ runtime/vm/gc_sweeper.cc	(working copy)
@@ -56,12 +56,12 @@
 }
 
 
-bool GCSweeper::SweepLargePage(HeapPage* page) {
-  bool in_use = false;
+intptr_t GCSweeper::SweepLargePage(HeapPage* page) {
+  intptr_t bytes_to_end = 0;
   RawObject* raw_obj = RawObject::FromAddr(page->object_start());
   if (raw_obj->IsMarked()) {
     raw_obj->ClearMarkBit();
-    in_use = true;
+    bytes_to_end += raw_obj->Size();

[Ivan Posva, 2014/06/30 05:51:05]

+= -> =

[koda, 2014/06/30 22:57:48]

Done.

   }
 #ifdef DEBUG
   // String::MakeExternal and Array::MakeArray create trailing filler objects,
@@ -74,7 +74,7 @@
     current += cur_obj->Size();
   }
 #endif  // DEBUG
-  return in_use;
+  return bytes_to_end;
 }
 
 }  // namespace dart