Unbox phis that were proven to be of type Double.

runtime/vm/compiler.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/compiler.h"
 
 #include "vm/assembler.h"
 #include "vm/ast_printer.h"
 #include "vm/code_generator.h"
 #include "vm/code_patcher.h"
@@ skipping 161 matching lines @@
         FlowGraphPrinter printer(*flow_graph);
         printer.PrintBlocks();
       }
       if (Dart::flow_graph_writer() != NULL) {
         // Write flow graph to file.
         FlowGraphVisualizer printer(*flow_graph);
         printer.PrintFunction();
       }
 
       if (optimized) {
-        // TODO(vegorov): we need to compute uses for the
-        // purposes of unboxing. Move unboxing to a later
-        // stage.
-        // Compute the use lists.
         flow_graph->ComputeUseLists();
 
         FlowGraphOptimizer optimizer(flow_graph);
         optimizer.ApplyICData();
 
         // Compute the use lists.
         flow_graph->ComputeUseLists();
 
         // Inlining (mutates the flow graph)
         if (FLAG_use_inlining) {
           FlowGraphInliner inliner(flow_graph);
           inliner.Inline();
           // Verify that the use lists are still valid.
           DEBUG_ASSERT(flow_graph->ValidateUseLists());
         }
 
         // Propagate types and eliminate more type tests.
         FlowGraphTypePropagator propagator(*flow_graph);
         propagator.PropagateTypes();
 
         // Verify that the use lists are still valid.
         DEBUG_ASSERT(flow_graph->ValidateUseLists());
 
         // Do optimizations that depend on the propagated type information.
         optimizer.OptimizeComputations();
 
+        // Unbox doubles.
+        flow_graph->ComputeUseLists();
+        optimizer.SelectRepresentations();
+
         if (FLAG_cse) {
+          flow_graph->ComputeUseLists();
           DominatorBasedCSE::Optimize(flow_graph->graph_entry());
         }
 
         // Perform register allocation on the SSA graph.
         FlowGraphAllocator allocator(*flow_graph);
         allocator.AllocateRegisters();
 
         if (FLAG_print_flow_graph) {
           OS::Print("After Optimizations:\n");
           FlowGraphPrinter printer(*flow_graph);
@@ skipping 347 matching lines @@
     result = isolate->object_store()->sticky_error();
     isolate->object_store()->clear_sticky_error();
     isolate->set_long_jump_base(base);
     return result.raw();
   }
   UNREACHABLE();
   return Object::null();
 }
 
 }  // namespace dart