Revert r35682, one test is failing: standalone/io/process_sync_test. Code may actually be changing …

runtime/vm/flow_graph_allocator.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_allocator.h"
 
 #include "vm/bit_vector.h"
 #include "vm/intermediate_language.h"
 #include "vm/il_printer.h"
 #include "vm/flow_graph.h"
@@ skipping 213 matching lines @@
     }
   }
 
   // Process initial definitions, ie, constants and incoming parameters.
   for (intptr_t i = 0; i < graph_entry_->initial_definitions()->length(); i++) {
     Definition* def = (*graph_entry_->initial_definitions())[i];
     const intptr_t vreg = def->ssa_temp_index();
     kill_[graph_entry_->postorder_number()]->Add(vreg);
     live_in_[graph_entry_->postorder_number()]->Remove(vreg);
   }
+
+  // Update initial live_in sets to match live_out sets. Has to be
+  // done in a separate path because of backwards branches.
+  for (intptr_t i = 0; i < block_count; i++) {
+    UpdateLiveIn(*postorder_[i]);
+  }
 }
 
 
 void LiveRange::AddUse(intptr_t pos, Location* location_slot) {
   ASSERT(location_slot != NULL);
   ASSERT((first_use_interval_->start_ <= pos) &&
          (pos <= first_use_interval_->end_));
   if ((uses_ != NULL) &&
       (uses_->pos() == pos) &&
       (uses_->location_slot() == location_slot)) {
@@ skipping 2535 matching lines @@
     OS::Print("-- [after ssa allocator] ir [%s] -------------\n",
               function.ToFullyQualifiedCString());
     FlowGraphPrinter printer(flow_graph_, true);
     printer.PrintBlocks();
     OS::Print("----------------------------------------------\n");
   }
 }
 
 
 }  // namespace dart