emit premonomorphic ics for loads/stores in optimized code

src/ic/ic-compiler.cc

Index: src/ic/ic-compiler.cc
diff --git a/src/ic/ic-compiler.cc b/src/ic/ic-compiler.cc
index 42b5e753bed21f9062fda382463e036908496eb3..f597083e631be5e9aa49adcab9dbcf58a0225581 100644
--- a/src/ic/ic-compiler.cc
+++ b/src/ic/ic-compiler.cc
@@ -197,6 +197,8 @@ Handle<Code> PropertyICCompiler::ComputeLoad(Isolate* isolate,
     code = compiler.CompileLoadInitialize(flags);
   } else if (ic_state == PREMONOMORPHIC) {
     code = compiler.CompileLoadPreMonomorphic(flags);
+  } else if (ic_state == MEGAMORPHIC) {
+    code = compiler.CompileLoadMegamorphic(flags);
   } else {
     UNREACHABLE();
   }
@@ -334,6 +336,14 @@ Handle<Code> PropertyICCompiler::CompileLoadPreMonomorphic(Code::Flags flags) {
 }
 
 
+Handle<Code> PropertyICCompiler::CompileLoadMegamorphic(Code::Flags flags) {
+  MegamorphicLoadStub stub(isolate(), LoadICState(extra_ic_state_));
+  auto code = stub.GetCode();
+  PROFILE(isolate(), CodeCreateEvent(Logger::LOAD_MEGAMORPHIC_TAG, *code, 0));
+  return code;
+}
+
+
 Handle<Code> PropertyICCompiler::CompileStoreInitialize(Code::Flags flags) {
   StoreIC::GenerateInitialize(masm());
   Handle<Code> code = GetCodeWithFlags(flags, "CompileStoreInitialize");