VM: Another fix for precompiling with >1 iterations.

runtime/vm/aot_optimizer.cc

 // Copyright (c) 2013, 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/aot_optimizer.h"
 
 #include "vm/bit_vector.h"
 #include "vm/branch_optimizer.h"
 #include "vm/cha.h"
 #include "vm/compiler.h"
@@ skipping 105 matching lines @@
   }
 }
 
 
 // TODO(srdjan): Test/support other number types as well.
 static bool IsNumberCid(intptr_t cid) {
   return (cid == kSmiCid) || (cid == kDoubleCid);
 }
 
 
+// Returns named function that is a unique dynamic target, i.e.,
+// - the target is identified by its name alone, since it occurs only once.
+// - target's class has no subclasses, and neither is subclassed, i.e.,
+//   the receiver type can be only the function's class.
+// Returns Function::null() if there is no unique dynamic target for
+// given 'fname'. 'fname' must be a symbol.
 static void GetUniqueDynamicTarget(Isolate* isolate,
                                    const String& fname,
                                    Object* function) {
   UniqueFunctionsSet functions_set(
       isolate->object_store()->unique_dynamic_targets());
   ASSERT(fname.IsSymbol());
   *function = functions_set.GetOrNull(fname);
   ASSERT(functions_set.Release().raw() ==
       isolate->object_store()->unique_dynamic_targets());
 }
@@ skipping 74 matching lines @@
     }
     call->set_ic_data(&ic_data);
     return true;
   }
 
   if (isolate()->object_store()->unique_dynamic_targets() != Array::null()) {
     // Check if the target is unique.
     Function& target_function = Function::Handle(Z);
     GetUniqueDynamicTarget(isolate(), call->function_name(), &target_function);
     // Calls with named arguments must be resolved/checked at runtime.
-    String& error_message = String::Handle(Z);
     if (!target_function.IsNull() &&
         !target_function.HasOptionalNamedParameters() &&
         target_function.AreValidArgumentCounts(call->ArgumentCount(), 0,
-                                               &error_message)) {
+                                               /* error_message = */ NULL)) {
       const intptr_t cid = Class::Handle(Z, target_function.Owner()).id();
       const ICData& ic_data = ICData::ZoneHandle(Z,
           ICData::NewFrom(*call->ic_data(), 1));
       ic_data.AddReceiverCheck(cid, target_function);
       call->set_ic_data(&ic_data);
       return true;
     }
   }
 
   return false;
@@ skipping 2536 matching lines @@
 
   // Discard the environment from the original instruction because the store
   // can't deoptimize.
   instr->RemoveEnvironment();
   ReplaceCall(instr, store);
   return true;
 }
 
 
 }  // namespace dart