Improve hashCode for closures

runtime/vm/raw_object.h

Index: runtime/vm/raw_object.h
diff --git a/runtime/vm/raw_object.h b/runtime/vm/raw_object.h
index 4362f59279bc2ca6c707c84182e0d413a3a80a40..ff8a4135b9c8400c376222e8942cdf4f777b0047 100644
--- a/runtime/vm/raw_object.h
+++ b/runtime/vm/raw_object.h
@@ -919,8 +919,7 @@ class RawClosureData : public RawObject {
   RawObject** to_snapshot() {
     return reinterpret_cast<RawObject**>(&ptr()->closure_);
   }
-  RawObject* hash_;
-  RawObject** to() { return reinterpret_cast<RawObject**>(&ptr()->hash_); }
+  RawObject** to() { return reinterpret_cast<RawObject**>(&ptr()->closure_); }
 
   friend class Function;
 };
@@ -1799,16 +1798,20 @@ class RawClosure : public RawInstance {
     return reinterpret_cast<RawObject**>(&ptr()->instantiator_type_arguments_);
   }
 
-  // No instance fields should be declared before the following 4 fields whose
+  // No instance fields should be declared before the following fields whose
   // offsets must be identical in Dart and C++.
 
-  // These 4 fields are also declared in the Dart source of class _Closure.
+  // The following fields are also declared in the Dart source of class
+  // _Closure.
   RawTypeArguments* instantiator_type_arguments_;
   RawTypeArguments* function_type_arguments_;
   RawFunction* function_;
   RawContext* context_;
+  RawInteger* cached_hash_code_;

[rmacnak, 2017/07/19 01:00:24]

RawSmi* hash_;

Compare other hash fields on String, Type, etc.

[alexmarkov, 2017/07/19 17:54:19]

Done.

 
-  RawObject** to() { return reinterpret_cast<RawObject**>(&ptr()->context_); }
+  RawObject** to() {
+    return reinterpret_cast<RawObject**>(&ptr()->cached_hash_code_);
+  }
 
   // Note that instantiator_type_arguments_ and function_type_arguments_ are
   // used to instantiate the signature of function_ when this closure is