[ic] Split megamorphic stub cache in two caches (for loads and for stores).

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index 77f483c8db28f450a8d547f38aae50c598dec60c..aaa2e10e976d44df7b2330f46ea61ffb045ddb95 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -1902,7 +1902,8 @@ Isolate::Isolate(bool enable_serializer)
       counters_(NULL),
       logger_(NULL),
       stats_table_(NULL),
-      stub_cache_(NULL),
+      load_stub_cache_(NULL),
+      store_stub_cache_(NULL),
       code_aging_helper_(NULL),
       deoptimizer_data_(NULL),
       deoptimizer_lazy_throw_(false),
@@ -2140,8 +2141,10 @@ Isolate::~Isolate() {
   delete keyed_lookup_cache_;
   keyed_lookup_cache_ = NULL;
 
-  delete stub_cache_;
-  stub_cache_ = NULL;
+  delete load_stub_cache_;
+  load_stub_cache_ = NULL;
+  delete store_stub_cache_;
+  store_stub_cache_ = NULL;
   delete code_aging_helper_;
   code_aging_helper_ = NULL;
   delete stats_table_;
@@ -2284,7 +2287,8 @@ bool Isolate::Init(Deserializer* des) {
   eternal_handles_ = new EternalHandles();
   bootstrapper_ = new Bootstrapper(this);
   handle_scope_implementer_ = new HandleScopeImplementer(this);
-  stub_cache_ = new StubCache(this);
+  load_stub_cache_ = new StubCache(this, Code::LOAD_IC);
+  store_stub_cache_ = new StubCache(this, Code::STORE_IC);
   materialized_object_store_ = new MaterializedObjectStore(this);
   regexp_stack_ = new RegExpStack();
   regexp_stack_->isolate_ = this;
@@ -2360,7 +2364,8 @@ bool Isolate::Init(Deserializer* des) {
   if (!create_heap_objects) {
     des->Deserialize(this);
   }
-  stub_cache_->Initialize();
+  load_stub_cache_->Initialize();
+  store_stub_cache_->Initialize();
   if (FLAG_ignition || serializer_enabled()) {
     interpreter_->Initialize();
   }