Fix issue 16592: Do not attempt to merge operations that do not have uses, otherwise we add force u…

runtime/vm/intermediate_language.h

 // 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.
 
 #ifndef VM_INTERMEDIATE_LANGUAGE_H_
 #define VM_INTERMEDIATE_LANGUAGE_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
@@ skipping 4891 matching lines @@
 
   virtual bool AllowsCSE() const { return true; }
   virtual EffectSet Effects() const { return EffectSet::None(); }
   virtual EffectSet Dependencies() const { return EffectSet::None(); }
   virtual bool AttributesEqual(Instruction* other) const {
     return kind() == other->AsMathUnary()->kind();
   }
 
   virtual bool MayThrow() const { return false; }
 
+  Definition* Canonicalize(FlowGraph* flow_graph);
+
  private:
   const MethodRecognizer::Kind kind_;
 
   DISALLOW_COPY_AND_ASSIGN(MathUnaryInstr);
 };
 
 
 // Represents Math's static min and max functions.
 class MathMinMaxInstr : public TemplateDefinition<2> {
  public:
@@ skipping 2198 matching lines @@
   ForwardInstructionIterator* current_iterator_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FlowGraphVisitor);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_