Revision: 9626
Author:   [email protected]
Date:     Fri Oct 14 03:52:30 2011
Log:      Avoid extra GCs when deserializing during incremental marking.
Review URL: http://codereview.chromium.org/8276030
http://code.google.com/p/v8/source/detail?r=9626

Modified:
 /branches/bleeding_edge/src/spaces.cc

=======================================
--- /branches/bleeding_edge/src/spaces.cc       Tue Oct 11 09:50:58 2011
+++ /branches/bleeding_edge/src/spaces.cc       Fri Oct 14 03:52:30 2011
@@ -1909,11 +1909,24 @@

 bool NewSpace::ReserveSpace(int bytes) {
   // We can't reliably unpack a partial snapshot that needs more new space
-  // space than the minimum NewSpace size.
+  // space than the minimum NewSpace size.  The limit can be set lower than
+ // the end of new space either because there is more space on the next page + // or because we have lowered the limit in order to get periodic incremental + // marking. The most reliable way to ensure that there is linear space is
+  // to do the allocation, then rewind the limit.
   ASSERT(bytes <= InitialCapacity());
-  Address limit = allocation_info_.limit;
+  MaybeObject* maybe = AllocateRawInternal(bytes);
+  Object* object = NULL;
+  if (!maybe->ToObject(&object)) return false;
+  HeapObject* allocation = HeapObject::cast(object);
   Address top = allocation_info_.top;
-  return limit - top >= bytes;
+  if ((top - bytes) == allocation->address()) {
+    allocation_info_.top = allocation->address();
+    return true;
+  }
+ // There may be a borderline case here where the allocation succeeded, but + // the limit and top have moved on to a new page. In that case we try again.
+  return ReserveSpace(bytes);
 }


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