Made simple instance-of checks fast for unoptimized code.

runtime/lib/object.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/bootstrap_natives.h"
 
 #include "lib/invocation_mirror.h"
 #include "vm/code_patcher.h"
 #include "vm/exceptions.h"
 #include "vm/heap.h"
@@ skipping 148 matching lines @@
     String& bound_error_message = String::Handle(
         zone, String::New(bound_error.ToErrorCString()));
     Exceptions::CreateAndThrowTypeError(
         location, AbstractType::Handle(zone), AbstractType::Handle(zone),
         Symbols::Empty(), bound_error_message);
     UNREACHABLE();
   }
   return Bool::Get(negate.value() ? !is_instance_of : is_instance_of).raw();
 }
 
+DEFINE_NATIVE_ENTRY(Object_simpleInstanceOf, 2) {
+  // This native is only called when the right hand side passes
+  // simpleInstanceOfType and it is a non-negative test.

[regis, 2016/07/14 01:41:45]

It would be interesting to do it for the negative case as well and see if it
helps dart2js.
I suppose a 'negate' extra argument would not work, but you would need a
separate call (e.g. Object_simpleNotInstanceOf).

[bakster, 2016/07/14 17:59:41]

Yes, that is an easy change.
However, in the benchmarks I measured, it is hardly used.

+  const Instance& instance =
+      Instance::CheckedHandle(zone, arguments->NativeArgAt(0));
+  const AbstractType& type =
+      AbstractType::CheckedHandle(zone, arguments->NativeArgAt(1));
+  const TypeArguments& instantiator_type_arguments =
+      TypeArguments::Handle(TypeArguments::null());
+  ASSERT(type.IsFinalized());
+  ASSERT(!type.IsMalformed());
+  ASSERT(!type.IsMalbounded());
+  Error& bound_error = Error::Handle(zone, Error::null());
+  const bool is_instance_of = instance.IsInstanceOf(type,
+                                                    instantiator_type_arguments,
+                                                    &bound_error);
+  if (!is_instance_of && !bound_error.IsNull()) {
+    // Throw a dynamic type error only if the instanceof test fails.
+    DartFrameIterator iterator;
+    StackFrame* caller_frame = iterator.NextFrame();
+    ASSERT(caller_frame != NULL);
+    const TokenPosition location = caller_frame->GetTokenPos();
+    String& bound_error_message = String::Handle(
+        zone, String::New(bound_error.ToErrorCString()));
+    Exceptions::CreateAndThrowTypeError(
+        location, AbstractType::Handle(zone), AbstractType::Handle(zone),
+        Symbols::Empty(), bound_error_message);
+    UNREACHABLE();
+  }
+  return Bool::Get(is_instance_of).raw();
+}
 
 DEFINE_NATIVE_ENTRY(Object_instanceOfNum, 2) {
   const Instance& instance =
       Instance::CheckedHandle(zone, arguments->NativeArgAt(0));
   const Bool& negate = Bool::CheckedHandle(zone, arguments->NativeArgAt(1));
   bool is_instance_of = instance.IsNumber();
   if (negate.value()) {
     is_instance_of = !is_instance_of;
   }
   return Bool::Get(is_instance_of).raw();
@@ skipping 153 matching lines @@
 
 DEFINE_NATIVE_ENTRY(Internal_inquireIs64Bit, 0) {
 #if defined(ARCH_IS_64_BIT)
   return Bool::True().raw();
 #else
   return Bool::False().raw();
 #endif  // defined(ARCH_IS_64_BIT)
 }
 
 }  // namespace dart