Cache lookups at megamorphic call sites in optimized code.

runtime/vm/isolate.h

Index: runtime/vm/isolate.h
diff --git a/runtime/vm/isolate.h b/runtime/vm/isolate.h
index 6be219391fcc2c25882c81859d01b04aa354581c..7dc4a716e3d63bb5ff6f7634c93b05fa41a892b2 100644
--- a/runtime/vm/isolate.h
+++ b/runtime/vm/isolate.h
@@ -7,10 +7,11 @@
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
-#include "vm/class_table.h"
 #include "platform/thread.h"
 #include "vm/base_isolate.h"
+#include "vm/class_table.h"
 #include "vm/gc_callbacks.h"
+#include "vm/megamorphic_cache_table.h"
 #include "vm/store_buffer.h"
 #include "vm/timer.h"
 
@@ -114,6 +115,10 @@ class Isolate : public BaseIsolate {
     return OFFSET_OF(Isolate, class_table_);
   }
 
+  MegamorphicCacheTable* megamorphic_cache_table() {
+    return &megamorphic_cache_table_;
+  }
+
   Dart_MessageNotifyCallback message_notify_callback() const {
     return message_notify_callback_;
   }
@@ -325,6 +330,7 @@ class Isolate : public BaseIsolate {
   StoreBufferBlock store_buffer_block_;
   StoreBuffer store_buffer_;
   ClassTable class_table_;
+  MegamorphicCacheTable megamorphic_cache_table_;
   Dart_MessageNotifyCallback message_notify_callback_;
   char* name_;
   Dart_Port main_port_;