Ensure that compile time types for comparisons are recomputed once comparison are specialized.

runtime/vm/flow_graph_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/flow_graph_optimizer.h"
 
 #include "vm/bit_vector.h"
 #include "vm/cha.h"
 #include "vm/flow_graph_builder.h"
 #include "vm/flow_graph_compiler.h"
@@ skipping 2625 matching lines @@
 
   // Host CheckSmi instruction and make this phi smi one.
   Hoist(it, pre_header, current);
 
   // Replace value we are checking with phi's input. Maintain use lists.
   Definition* non_smi_input_defn = phi->InputAt(non_smi_input)->definition();
   current->value()->RemoveFromUseList();
   current->value()->set_definition(non_smi_input_defn);
   non_smi_input_defn->AddInputUse(current->value());
 
-  phi->Type()->ReplaceWith(CompileType::FromCid(kSmiCid));
+  phi->UpdateType(CompileType::FromCid(kSmiCid));
 }
 
 
 void LICM::Optimize(FlowGraph* flow_graph) {
   GrowableArray<BlockEntryInstr*> loop_headers;
   flow_graph->ComputeLoops(&loop_headers);
 
   for (intptr_t i = 0; i < loop_headers.length(); ++i) {
     BlockEntryInstr* header = loop_headers[i];
     // Skip loop that don't have a pre-header block.
@@ skipping 1600 matching lines @@
 
   if (FLAG_trace_constant_propagation) {
     OS::Print("\n==== After constant propagation ====\n");
     FlowGraphPrinter printer(*graph_);
     printer.PrintBlocks();
   }
 }
 
 
 }  // namespace dart