Add --dump-megamorphic-stats. Lower megamorphic cache load factor to 50%.

runtime/vm/isolate.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/isolate.h"
 
 #include "include/dart_api.h"
 #include "include/dart_native_api.h"
 #include "platform/assert.h"
 #include "platform/text_buffer.h"
@@ skipping 1590 matching lines @@
   if (FLAG_support_timeline && FLAG_timing) {
     TimelinePauseTrace tpt;
     tpt.Print();
   }
 #endif  // !PRODUCT
 
   // Finalize any weak persistent handles with a non-null referent.
   FinalizeWeakPersistentHandlesVisitor visitor;
   api_state()->weak_persistent_handles().VisitHandles(&visitor);
 
+  if (FLAG_dump_megamorphic_stats) {
+    MegamorphicCacheTable::PrintSizes(this);
+  }
   if (FLAG_trace_isolates) {
     heap()->PrintSizes();
-    MegamorphicCacheTable::PrintSizes(this);
     Symbols::DumpStats();
     OS::Print("[-] Stopping isolate:\n"
               "\tisolate:    %s\n", name());
   }
   if (FLAG_print_metrics) {
     LogBlock lb;
     THR_Print("Printing metrics for %s\n", name());
 #define ISOLATE_METRIC_PRINT(type, variable, name, unit)                       \
   THR_Print("%s\n", metric_##variable##_.ToString());
 
@@ skipping 1166 matching lines @@
 void IsolateSpawnState::DecrementSpawnCount() {
   ASSERT(spawn_count_monitor_ != NULL);
   ASSERT(spawn_count_ != NULL);
   MonitorLocker ml(spawn_count_monitor_);
   ASSERT(*spawn_count_ > 0);
   *spawn_count_ = *spawn_count_ - 1;
   ml.Notify();
 }
 
 }  // namespace dart