Improve hashCode for closures

runtime/lib/function.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/bootstrap_natives.h"
 
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
 #include "vm/exceptions.h"
 #include "vm/native_entry.h"
@@ skipping 50 matching lines @@
       if ((receiver_a.raw() == receiver_b.raw()) &&
           (func_a.name() == func_b.name()) &&
           (func_a.Owner() == func_b.Owner())) {
         return Bool::True().raw();
       }
     }
   }
   return Bool::False().raw();
 }
 
-DEFINE_NATIVE_ENTRY(Closure_hashCode, 1) {
+DEFINE_NATIVE_ENTRY(Closure_calculateHashCode, 1) {

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

computeHash

(Compare String and Type)

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

Done.

   const Closure& receiver =
       Closure::CheckedHandle(zone, arguments->NativeArgAt(0));
   const Function& func = Function::Handle(zone, receiver.function());
-  return func.GetClosureHashCode();
+  intptr_t result = func.GetClosureHashCode();
+  if (func.IsImplicitInstanceClosureFunction()) {
+    // Calculate identityHashCode of cached closure receiver and
+    // combine it with function's hash code.
+    const Context& context = Context::Handle(zone, receiver.context());
+    const Object& recv = Object::Handle(zone, context.At(0));
+    ASSERT(recv.IsInstance());
+    const Object& recvHash =
+        Object::Handle(zone, Instance::Cast(recv).IdentityHashCode());
+    if (recvHash.IsInteger()) {
+      result = result ^ static_cast<intptr_t>(

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

Please use CombineHashes and FinalizeHash

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

Done.

+                            Integer::Cast(recvHash).AsTruncatedInt64Value());
+    }
+  }
+  // Finalize hash value like for strings so that it fits into a smi.
+  result += result << 3;
+  result ^= result >> 11;
+  result += result << 15;
+  result &= ((static_cast<intptr_t>(1) << String::kHashBits) - 1);
+  return Smi::New(result);
 }
 
 DEFINE_NATIVE_ENTRY(Closure_clone, 1) {
   const Closure& receiver =
       Closure::CheckedHandle(zone, arguments->NativeArgAt(0));
   const TypeArguments& instantiator_type_arguments =
       TypeArguments::Handle(zone, receiver.instantiator_type_arguments());
   const TypeArguments& function_type_arguments =
       TypeArguments::Handle(zone, receiver.function_type_arguments());
   const Function& function = Function::Handle(zone, receiver.function());
   const Context& context = Context::Handle(zone, receiver.context());
   Context& cloned_context =
       Context::Handle(zone, Context::New(context.num_variables()));
   cloned_context.set_parent(Context::Handle(zone, context.parent()));
   Object& instance = Object::Handle(zone);
   for (int i = 0; i < context.num_variables(); i++) {
     instance = context.At(i);
     cloned_context.SetAt(i, instance);
   }
   return Closure::New(instantiator_type_arguments, function_type_arguments,
                       function, cloned_context);
 }
 
 }  // namespace dart