Optimize StoreIndexedComp on ia32&x64.

runtime/vm/intermediate_language.h

Index: runtime/vm/intermediate_language.h
diff --git a/runtime/vm/intermediate_language.h b/runtime/vm/intermediate_language.h
index 2b8d0fe31386533c1915aa92bdf2b36c4bd2d55d..0325900e75c63131ae6dee236326b6e70a525122 100644
--- a/runtime/vm/intermediate_language.h
+++ b/runtime/vm/intermediate_language.h
@@ -878,7 +878,8 @@ class StoreIndexedComp : public TemplateComputation<3> {
                    Value* index,
                    Value* value)
       : token_index_(token_index),
-        try_index_(try_index) {
+        try_index_(try_index),
+        receiver_type_(kIllegalObjectKind) {
     inputs_[0] = array;
     inputs_[1] = index;
     inputs_[2] = value;
@@ -892,9 +893,18 @@ class StoreIndexedComp : public TemplateComputation<3> {
   Value* index() const { return inputs_[1]; }
   Value* value() const { return inputs_[2]; }
 
+  void set_receiver_type(ObjectKind receiver_type) {
+    receiver_type_ = receiver_type;
+  }
+
+  ObjectKind receiver_type() const {
+    return receiver_type_;
+  }
+
  private:
   const intptr_t token_index_;
   const intptr_t try_index_;
+  ObjectKind receiver_type_;
 
   DISALLOW_COPY_AND_ASSIGN(StoreIndexedComp);
 };