Convert diamond shaped control flow into a single conditional instruction.

runtime/vm/intermediate_language.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/intermediate_language.h"
 
 #include "vm/bit_vector.h"
 #include "vm/dart_entry.h"
 #include "vm/flow_graph_allocator.h"
 #include "vm/flow_graph_builder.h"
@@ skipping 2021 matching lines @@
       range_ = new Range(RangeBoundary::FromConstant(0),
                          RangeBoundary::FromConstant(0xFFFF));
       break;
     default:
       Definition::InferRange();
       break;
   }
 }
 
 
+void IfThenElseInstr::InferRange() {
+  const intptr_t min = Utils::Minimum(if_true_, if_false_);
+  const intptr_t max = Utils::Maximum(if_true_, if_false_);
+  range_ = new Range(RangeBoundary::FromConstant(min),
+                     RangeBoundary::FromConstant(max));
+}
+
+
 void PhiInstr::InferRange() {
   RangeBoundary new_min;
   RangeBoundary new_max;
 
   for (intptr_t i = 0; i < InputCount(); i++) {
     Range* input_range = InputAt(i)->definition()->range();
     if (input_range == NULL) {
       range_ = Range::Unknown();
       return;
     }
@@ skipping 320 matching lines @@
     default:
       UNREACHABLE();
   }
   return kPowRuntimeEntry;
 }
 
 
 #undef __
 
 }  // namespace dart