Handle field-invocation and method-extraction in the runtime when --lazy_dispatchers=false.

runtime/vm/dart_entry.cc

 // Copyright (c) 2011, 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/dart_entry.h"
 
 #include "vm/class_finalizer.h"
 #include "vm/code_generator.h"
 #include "vm/compiler.h"
 #include "vm/debugger.h"
@@ skipping 133 matching lines @@
     // Only invoke the function if its arguments are compatible.
     const ArgumentsDescriptor args_desc(arguments_descriptor);
     if (function.AreValidArgumentCounts(args_desc.Count(),
                                         args_desc.NamedCount(),
                                         NULL)) {
       // The closure or non-closure object (receiver) is passed as implicit
       // first argument. It is already included in the arguments array.
       return InvokeFunction(function, arguments, arguments_descriptor);
     }
   }
-  // There is no compatible 'call' method, so invoke noSuchMethod.
+
+  // There is no compatible 'call' method, see if there's a getter.
+  if (instance.IsClosure()) {
+    // Special case: closures are implemented with a call getter instead of a
+    // call method. If the arguments didn't match, go to noSuchMethod instead
+    // of infinitely recursing on the getter.
+  } else {

[Florian Schneider, 2015/06/29 10:37:53]

When is InvokeClosure used with a non-closure object?

[rmacnak, 2015/06/29 21:54:19]

From the runtime stub, e.g.

class FakeFunction {
  call() => ...
}
class A {
  get f => new FakeFunction();
}
new A().f()

Or if someone invokes Dart_InvokeClosure with a FakeFunction.

Maybe this should be renamed InvokeCall.

+    const String& getter_name = String::Handle(Symbols::New("get:call"));
+    Class& cls = Class::Handle(instance.clazz());
+    while (!cls.IsNull()) {
+      function ^= cls.LookupDynamicFunction(getter_name);
+      if (!function.IsNull()) {
+        // Getters don't have a stack overflow check, so do one in C++.
+
+        Isolate* isolate = Isolate::Current();
+#if defined(USING_SIMULATOR)
+        uword stack_pos = Simulator::Current()->get_register(SPREG);
+#else
+        uword stack_pos = Isolate::GetCurrentStackPointer();
+#endif
+        if (stack_pos < isolate->saved_stack_limit()) {
+          const Instance& exception =
+            Instance::Handle(isolate->object_store()->stack_overflow());
+          return UnhandledException::New(exception, Stacktrace::Handle());
+        }
+
+        const Array& getter_arguments = Array::Handle(Array::New(1));
+        getter_arguments.SetAt(0, instance);
+        const Object& getter_result =
+              Object::Handle(DartEntry::InvokeFunction(function,
+                                                       getter_arguments));
+        if (getter_result.IsError()) {
+          return getter_result.raw();
+        }
+        ASSERT(getter_result.IsNull() || getter_result.IsInstance());
+
+        arguments.SetAt(0, getter_result);  // Safe to reuse this?

[Florian Schneider, 2015/06/30 10:28:35]

Why shouldn't it be safe?

[rmacnak, 2015/06/30 22:13:49]

I didn't initially notice a new one was allocated for each runtime entry.

+        return InvokeClosure(arguments, arguments_descriptor);
+      }
+      cls = cls.SuperClass();
+    }
+  }
+
+  // No compataible method or getter so invoke noSuchMethod.

[Florian Schneider, 2015/06/30 10:28:35]

s/compataible/compatible/

[rmacnak, 2015/06/30 22:13:49]

Done.

   return InvokeNoSuchMethod(instance,
                             Symbols::Call(),
                             arguments,
                             arguments_descriptor);
 }
 
 
 RawObject* DartEntry::InvokeNoSuchMethod(const Instance& receiver,
                                          const String& target_name,
                                          const Array& arguments,
@@ skipping 364 matching lines @@
   const Array& args = Array::Handle(Array::New(kNumArguments));
   args.SetAt(0, map);
   args.SetAt(1, key);
   args.SetAt(2, value);
   const Object& result = Object::Handle(DartEntry::InvokeFunction(function,
                                                                   args));
   return result.raw();
 }
 
 }  // namespace dart