Recognize List.fixedLength factory constructor.

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 "vm/ast_printer.h"
 #include "vm/code_descriptors.h"
 #include "vm/dart_entry.h"
 #include "vm/flags.h"
@@ skipping 1797 matching lines @@
   const Class& function_class = Class::Handle(function.Owner());
   const Library& core_lib = Library::Handle(Library::CoreLibrary());
 
   if (function_class.library() != core_lib.raw()) {
     return kDynamicCid;
   }
 
   if (node->constructor().IsFactory()) {
     if ((function_class.Name() == Symbols::List().raw()) &&
         (function.name() == Symbols::ListFactory().raw())) {
-      // If there are no arguments then the result is guaranteed to be a
-      // GrowableObjectArray. However if there is an argument the result
-      // is not guaranteed to be a fixed size array because the argument
-      // can be null.
       return kGrowableObjectArrayCid;
+    } else if ((function_class.Name() == Symbols::List().raw()) &&
+               (function.name() == Symbols::ListFixedLengthFactory().raw())) {
+      return kArrayCid;
     } else {
       if (IsRecognizedConstructor(function, Symbols::ObjectArray()) &&
           (node->arguments()->length() == 1)) {
         return kArrayCid;
       } else if (IsRecognizedConstructor(function,
                                          Symbols::GrowableObjectArray()) &&
                  (node->arguments()->length() == 0)) {
         return kGrowableObjectArrayCid;
       }
     }
@@ skipping 1236 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