Only clear monomorphic ICs on GC after Context exit

src/mark-compact.cc

-// Copyright 2011 the V8 project authors. All rights reserved.
+// Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
 //       with the distribution.
@@ skipping 44 matching lines @@
 // MarkCompactCollector
 
 MarkCompactCollector::MarkCompactCollector() :  // NOLINT
 #ifdef DEBUG
       state_(IDLE),
 #endif
       sweep_precisely_(false),
       compacting_(false),
       was_marked_incrementally_(false),
       collect_maps_(FLAG_collect_maps),
+      flush_monomorphic_ics_(false),
       tracer_(NULL),
       migration_slots_buffer_(NULL),
       heap_(NULL),
       code_flusher_(NULL),
       encountered_weak_maps_(NULL) { }
 
 
 #ifdef DEBUG
 class VerifyMarkingVisitor: public ObjectVisitor {
  public:
@@ skipping 432 matching lines @@
 
 
 void MarkCompactCollector::Prepare(GCTracer* tracer) {
   was_marked_incrementally_ = heap()->incremental_marking()->IsMarking();
 
   // Disable collection of maps if incremental marking is enabled.
   // Map collection algorithm relies on a special map transition tree traversal
   // order which is not implemented for incremental marking.
   collect_maps_ = FLAG_collect_maps && !was_marked_incrementally_;
 
+  // Monomorphic ICs are preserved when possible, but need to be flushed
+  // when they might be keeping a Context alive, or when the heap is about
+  // to be serialized.
+  flush_monomorphic_ics_ =
+      heap()->isolate()->context_exit_happened() || Serializer::enabled();
+
   // Rather than passing the tracer around we stash it in a static member
   // variable.
   tracer_ = tracer;
 
 #ifdef DEBUG
   ASSERT(state_ == IDLE);
   state_ = PREPARE_GC;
 #endif
 
   ASSERT(!FLAG_never_compact || !FLAG_always_compact);
@@ skipping 346 matching lines @@
     // that there can be no such embedded pointers and add assertion here.
     HeapObject* object = HeapObject::cast(rinfo->target_object());
     heap->mark_compact_collector()->RecordRelocSlot(rinfo, object);
     MarkBit mark = Marking::MarkBitFrom(object);
     heap->mark_compact_collector()->MarkObject(object, mark);
   }
 
   static inline void VisitCodeTarget(Heap* heap, RelocInfo* rinfo) {
     ASSERT(RelocInfo::IsCodeTarget(rinfo->rmode()));
     Code* target = Code::GetCodeFromTargetAddress(rinfo->target_address());
-    if (FLAG_cleanup_code_caches_at_gc && target->is_inline_cache_stub()) {
+    if (FLAG_cleanup_code_caches_at_gc && target->is_inline_cache_stub()
+        && (target->ic_state() == MEGAMORPHIC ||
+            heap->mark_compact_collector()->flush_monomorphic_ics_)) {
       IC::Clear(rinfo->pc());
       target = Code::GetCodeFromTargetAddress(rinfo->target_address());
     } else {
       if (FLAG_cleanup_code_caches_at_gc &&
           target->kind() == Code::STUB &&
           target->major_key() == CodeStub::CallFunction &&
           target->has_function_cache()) {
         CallFunctionStub::Clear(heap, rinfo->pc());
       }
     }
@@ skipping 3012 matching lines @@
   while (buffer != NULL) {
     SlotsBuffer* next_buffer = buffer->next();
     DeallocateBuffer(buffer);
     buffer = next_buffer;
   }
   *buffer_address = NULL;
 }
 
 
 } }  // namespace v8::internal