VM: Fix crash bug in constant propagation.

runtime/vm/constant_propagator.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/constant_propagator.h"
 
 #include "vm/bit_vector.h"
 #include "vm/flow_graph_builder.h"
 #include "vm/flow_graph_compiler.h"
 #include "vm/flow_graph_range_analysis.h"
@@ skipping 1002 matching lines @@
     SetValue(instr, non_constant_);
   }
 }
 
 
 void ConstantPropagator::VisitSmiToDouble(SmiToDoubleInstr* instr) {
   const Object& value = instr->value()->definition()->constant_value();
   if (IsConstant(value) && value.IsInteger()) {
     SetValue(instr, Double::Handle(I,
         Double::New(Integer::Cast(value).AsDoubleValue(), Heap::kOld)));
-  } else if (IsNonConstant(value)) {
+  } else if (!IsUnknown(value)) {
     SetValue(instr, non_constant_);
   }
 }
 
 
 void ConstantPropagator::VisitMintToDouble(MintToDoubleInstr* instr) {
   const Object& value = instr->value()->definition()->constant_value();
   if (IsConstant(value) && value.IsInteger()) {
     SetValue(instr, Double::Handle(I,
         Double::New(Integer::Cast(value).AsDoubleValue(), Heap::kOld)));
-  } else if (IsNonConstant(value)) {
+  } else if (!IsUnknown(value)) {
     SetValue(instr, non_constant_);
   }
 }
 
 
 void ConstantPropagator::VisitInt32ToDouble(Int32ToDoubleInstr* instr) {
   const Object& value = instr->value()->definition()->constant_value();
   if (IsConstant(value) && value.IsInteger()) {
     SetValue(instr, Double::Handle(I,
         Double::New(Integer::Cast(value).AsDoubleValue(), Heap::kOld)));
-  } else if (IsNonConstant(value)) {
+  } else if (!IsUnknown(value)) {
     SetValue(instr, non_constant_);
   }
 }
 
 
 void ConstantPropagator::VisitDoubleToInteger(DoubleToIntegerInstr* instr) {
   // TODO(kmillikin): Handle conversion.
   SetValue(instr, non_constant_);
 }
 
@@ skipping 623 matching lines @@
   graph_->MergeBlocks();
   GrowableArray<BitVector*> dominance_frontier;
   graph_->ComputeDominators(&dominance_frontier);
 
   if (FLAG_trace_constant_propagation) {
     FlowGraphPrinter::PrintGraph("After CP", graph_);
   }
 }
 
 }  // namespace dart