With --noopt run unoptimized code through optimizer, more optimizations can be done later.

runtime/vm/code_generator.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/code_generator.h"
 
 #include "vm/assembler.h"
 #include "vm/ast.h"
 #include "vm/code_patcher.h"
 #include "vm/compiler.h"
@@ skipping 1164 matching lines @@
     // TODO(turnidge): Consider using DeoptimizeAt instead.
     DeoptimizeFunctionsOnStack();
   }
   if (do_stacktrace) {
     String& var_name = String::Handle();
     Instance& var_value = Instance::Handle();
     DebuggerStackTrace* stack = isolate->debugger()->StackTrace();
     intptr_t num_frames = stack->Length();
     for (intptr_t i = 0; i < num_frames; i++) {
       ActivationFrame* frame = stack->FrameAt(i);
-      const int num_vars = frame->NumLocalVariables();
+      // Variable locations and number are unknown when 'always_optimize'.
+      const int num_vars =
+         Compiler::always_optimize() ? 0 : frame->NumLocalVariables();
       intptr_t unused;
       for (intptr_t v = 0; v < num_vars; v++) {
         frame->VariableAt(v, &var_name, &unused, &unused, &var_value);
       }
     }
   }
 
   uword interrupt_bits = isolate->GetAndClearInterrupts();
   if ((interrupt_bits & Isolate::kStoreBufferInterrupt) != 0) {
     if (FLAG_verbose_gc) {
@@ skipping 486 matching lines @@
   const intptr_t elm_size = old_data.ElementSizeInBytes();
   const TypedData& new_data =
       TypedData::Handle(TypedData::New(cid, new_size, Heap::kOld));
   TypedData::Copy(new_data, 0, old_data, 0, old_size * elm_size);
   typed_data_cell.SetAt(0, new_data);
   arguments.SetReturn(new_data);
 }
 
 
 }  // namespace dart