Implement aging of maps embedded in optimized code.

src/heap/mark-compact.cc

 // Copyright 2012 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/atomicops.h"
 #include "src/base/bits.h"
 #include "src/code-stubs.h"
 #include "src/compilation-cache.h"
@@ skipping 1942 matching lines @@
 void MarkCompactCollector::MarkRoots(RootMarkingVisitor* visitor) {
   // Mark the heap roots including global variables, stack variables,
   // etc., and all objects reachable from them.
   heap()->IterateStrongRoots(visitor, VISIT_ONLY_STRONG);
 
   // Handle the string table specially.
   MarkStringTable(visitor);
 
   MarkWeakObjectToCodeTable();
 
+  heap()->IterateEmbeddedMapCache(visitor);
+
   // There may be overflowed objects in the heap.  Visit them now.
   while (marking_deque_.overflowed()) {
     RefillMarkingDeque();
     EmptyMarkingDeque();
   }
 }
 
 
 void MarkCompactCollector::MarkImplicitRefGroups() {
   List<ImplicitRefGroup*>* ref_groups =
@@ skipping 219 matching lines @@
         }
       }
     }
   }
 
   RootMarkingVisitor root_visitor(heap());
   MarkRoots(&root_visitor);
 
   ProcessTopOptimizedFrame(&root_visitor);
 
+  ProcessMarkingDeque();

[Hannes Payer (out of office), 2014/11/17 17:34:33]

Why?

+
   // The objects reachable from the roots are marked, yet unreachable
   // objects are unmarked.  Mark objects reachable due to host
   // application specific logic or through Harmony weak maps.
   ProcessEphemeralMarking(&root_visitor);
 
   // The objects reachable from the roots, weak maps or object groups
   // are marked, yet unreachable objects are unmarked.  Mark objects
   // reachable only from weak global handles.
   //
   // First we identify nonlive weak handles and mark them as pending
@@ skipping 1314 matching lines @@
 
   heap_->string_table()->Iterate(&updating_visitor);
   updating_visitor.VisitPointer(heap_->weak_object_to_code_table_address());
   if (heap_->weak_object_to_code_table()->IsHashTable()) {
     WeakHashTable* table =
         WeakHashTable::cast(heap_->weak_object_to_code_table());
     table->Iterate(&updating_visitor);
     table->Rehash(heap_->isolate()->factory()->undefined_value());
   }
 
+  updating_visitor.VisitPointer(heap_->embedded_map_cache_address());
+  // No need to iterate the contents of the embedded map cache since

[Hannes Payer (out of office), 2014/11/17 17:34:33]

Please move the comment before
updating_visitor.VisitPointer(heap_->embedded_map_cache_address()); and say
something like "We just visit the embedded_map_cache slot here and update it if
needed.  No need to iterate the contents of the embedded map cache since maps do
not move."

+  // maps do not move.
+
   // Update pointers from external string table.
   heap_->UpdateReferencesInExternalStringTable(
       &UpdateReferenceInExternalStringTableEntry);
 
   EvacuationWeakObjectRetainer evacuation_object_retainer;
   heap()->ProcessWeakReferences(&evacuation_object_retainer);
 
   // Visit invalidated code (we ignored all slots on it) and clear mark-bits
   // under it.
   ProcessInvalidatedCode(&updating_visitor);
@@ skipping 846 matching lines @@
   SlotsBuffer* buffer = *buffer_address;
   while (buffer != NULL) {
     SlotsBuffer* next_buffer = buffer->next();
     DeallocateBuffer(buffer);
     buffer = next_buffer;
   }
   *buffer_address = NULL;
 }
 }
 }  // namespace v8::internal