Streamline IL for instantiating type arguments.

runtime/vm/flow_graph_builder.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/flow_graph_builder.h"
 
 #include "lib/invocation_mirror.h"
 #include "vm/ast_printer.h"
 #include "vm/code_descriptors.h"
 #include "vm/dart_entry.h"
@@ skipping 2281 matching lines @@
     intptr_t token_pos,
     const AbstractTypeArguments& type_arguments) {
   if (type_arguments.IsNull() || type_arguments.IsInstantiated()) {
     return Bind(new ConstantInstr(type_arguments));
   }
   // The type arguments are uninstantiated.
   const Class& instantiator_class = Class::ZoneHandle(
       owner()->parsed_function().function().Owner());
   Value* instantiator_value =
       BuildInstantiatorTypeArguments(token_pos, instantiator_class, NULL);
-  return Bind(new InstantiateTypeArgumentsInstr(token_pos,
-                                                type_arguments,
-                                                instantiator_class,
-                                                instantiator_value));
+  const bool use_instantiator_type_args =
+      type_arguments.IsUninstantiatedIdentity() ||

[Kevin Millikin (Google), 2013/05/27 09:22:03]

This predicate or its negation appears over and over.  Do you think it deserves
to be a named predicate on the AbstractTypeArguments?

[Florian Schneider, 2013/05/27 10:20:11]

Possibly. I don't have a really good name for such a predicate though.

+      type_arguments.CanShareInstantiatorTypeArguments(
+          instantiator_class);
+  return use_instantiator_type_args
+      ? instantiator_value
+      : Bind(new InstantiateTypeArgumentsInstr(token_pos,
+                                               type_arguments,
+                                               instantiator_class,
+                                               instantiator_value));
 }
 
 
 void EffectGraphVisitor::BuildConstructorTypeArguments(
     ConstructorCallNode* node,
     ZoneGrowableArray<PushArgumentInstr*>* call_arguments) {
   const Class& cls = Class::ZoneHandle(node->constructor().Owner());
   ASSERT(cls.HasTypeArguments() && !node->constructor().IsFactory());
   if (node->type_arguments().IsNull() ||
       node->type_arguments().IsInstantiated()) {
@@ skipping 1119 matching lines @@
   intptr_t len = OS::SNPrint(NULL, 0, kFormat, function_name, reason) + 1;
   char* chars = Isolate::Current()->current_zone()->Alloc<char>(len);
   OS::SNPrint(chars, len, kFormat, function_name, reason);
   const Error& error = Error::Handle(
       LanguageError::New(String::Handle(String::New(chars))));
   Isolate::Current()->long_jump_base()->Jump(1, error);
 }
 
 
 }  // namespace dart