Fix a bug in liveness analysis code and add more comments.

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 179 matching lines @@
       // generated code.
       intptr_t length = graph_builder.postorder_block_entries().length();
       for (intptr_t i = length - 1; i >= 0; --i) {
         block_order.Add(graph_builder.postorder_block_entries()[i]);
       }
       if (optimized) {
         FlowGraphOptimizer optimizer(block_order);
         optimizer.ApplyICData();
 
         if (FLAG_use_ssa) {
-          printf("====================================\n");
           // Perform register allocation on the SSA graph.
           FlowGraphAllocator allocator(graph_builder.postorder_block_entries(),
                                        graph_builder.current_ssa_temp_index());
           allocator.ResolveConstraints();
           allocator.AnalyzeLiveness();
 
           // Temporary bailout until we support code generation from SSA form.
           graph_builder.Bailout("No SSA code generation support.");
         }
       }
@@ skipping 377 matching lines @@
     isolate->object_store()->clear_sticky_error();
     isolate->set_long_jump_base(base);
     return result.raw();
   }
   UNREACHABLE();
   return Object::null();
 }
 
 
 }  // namespace dart