Simplify and improve optimization of is-tests in the precompiler.

runtime/vm/flow_graph_range_analysis.cc

 // Copyright (c) 2014, 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_range_analysis.h"
 
 #include "vm/bit_vector.h"
 #include "vm/il_printer.h"
 
 namespace dart {
@@ skipping 1551 matching lines @@
       if (target == NULL) {
         // TODO(vegorov): replace Constraint with an uncoditional
         // deoptimization and kill all dominated dead code.
         continue;
       }
 
       BranchInstr* branch =
           target->PredecessorAt(0)->last_instruction()->AsBranch();
       if (target == branch->true_successor()) {
         // True unreachable.
-        if (FLAG_trace_constant_propagation) {
+        if (FLAG_trace_constant_propagation &&
+            FlowGraphPrinter::ShouldPrint(flow_graph_->function())) {
           THR_Print("Range analysis: True unreachable (B%" Pd ")\n",
                     branch->true_successor()->block_id());
         }
         branch->set_constant_target(branch->false_successor());
       } else {
         ASSERT(target == branch->false_successor());
         // False unreachable.
-        if (FLAG_trace_constant_propagation) {
+        if (FLAG_trace_constant_propagation &&
+            FlowGraphPrinter::ShouldPrint(flow_graph_->function())) {
           THR_Print("Range analysis: False unreachable (B%" Pd ")\n",
                     branch->false_successor()->block_id());
         }
         branch->set_constant_target(branch->true_successor());
       }
     }
   }
 }
 
 
@@ skipping 1566 matching lines @@
     }
   } while (CanonicalizeMaxBoundary(&max) ||
            CanonicalizeMinBoundary(&canonical_length));
 
   // Failed to prove that maximum is bounded with array length.
   return false;
 }
 
 
 }  // namespace dart