Remove optimization in unoptimized code that leave the graph in bad state (type test).

runtime/vm/flow_graph_builder.h

 // 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.
 
 #ifndef VM_FLOW_GRAPH_BUILDER_H_
 #define VM_FLOW_GRAPH_BUILDER_H_
 
 #include "platform/assert.h"
 #include "platform/globals.h"
 #include "vm/allocation.h"
@@ skipping 434 matching lines @@
   friend class TempLocalScope;  // For ReturnDefinition.
 
   // Helper to drop the result value.
   virtual void ReturnValue(Value* value) {
     Do(new DropTempsInstr(0, value));
   }
 
   // Specify a definition of the final result.  Adds the definition to
   // the graph, but normally overridden in subclasses.
   virtual void ReturnDefinition(Definition* definition) {
-    Do(definition);
+    // Constants have no effect, do not add them to graph otherwise SSA
+    // builder will get confused.
+    if (!definition->IsConstant()) {
+      Do(definition);
+    }
   }
 
   // Shared global state.
   FlowGraphBuilder* owner_;
 
   // Output parameters.
   Instruction* entry_;
   Instruction* exit_;
 };
 
 
 // Translate an AstNode to a control-flow graph fragment for both its effects
 // and value (e.g., for an expression in a value context).  Implements a
 // function from an AstNode and next temporary index to a graph fragment (as
 // in the EffectGraphVisitor), a next temporary index, and an intermediate
 // language Value.
 class ValueGraphVisitor : public EffectGraphVisitor {
  public:
   explicit ValueGraphVisitor(FlowGraphBuilder* owner)
       : EffectGraphVisitor(owner), value_(NULL) { }
 
   // Visit functions overridden by this class.
-  virtual void VisitLiteralNode(LiteralNode* node);
   virtual void VisitAssignableNode(AssignableNode* node);
   virtual void VisitConstructorCallNode(ConstructorCallNode* node);
   virtual void VisitBinaryOpNode(BinaryOpNode* node);
   virtual void VisitConditionalExprNode(ConditionalExprNode* node);
   virtual void VisitLoadLocalNode(LoadLocalNode* node);
   virtual void VisitStoreIndexedNode(StoreIndexedNode* node);
   virtual void VisitInstanceSetterNode(InstanceSetterNode* node);
   virtual void VisitThrowNode(ThrowNode* node);
   virtual void VisitClosureCallNode(ClosureCallNode* node);
   virtual void VisitStaticSetterNode(StaticSetterNode* node);
@@ skipping 78 matching lines @@
   // Output parameters.
   GrowableArray<TargetEntryInstr**> true_successor_addresses_;
   GrowableArray<TargetEntryInstr**> false_successor_addresses_;
 
   intptr_t condition_token_pos_;
 };
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_BUILDER_H_