Canonicalize away simple arithmetic equivalences.

runtime/vm/intermediate_language.h

Index: runtime/vm/intermediate_language.h
diff --git a/runtime/vm/intermediate_language.h b/runtime/vm/intermediate_language.h
index b8ac5a3f0dce352d193dc6eba9c9dc24820abbb6..d900ca1e5f6c9ed34c0ec99e260b79281f0dd257 100644
--- a/runtime/vm/intermediate_language.h
+++ b/runtime/vm/intermediate_language.h
@@ -3519,6 +3519,7 @@ class UnboxIntegerInstr : public TemplateDefinition<1> {
     return kUnboxedMint;
   }
 
+
   virtual bool AffectedBySideEffect() const { return false; }
   virtual bool AttributesEqual(Instruction* other) const { return true; }
 
@@ -3576,9 +3577,9 @@ class MathSqrtInstr : public TemplateDefinition<1> {
 class BinaryDoubleOpInstr : public TemplateDefinition<2> {
  public:
   BinaryDoubleOpInstr(Token::Kind op_kind,
-                             Value* left,
-                             Value* right,
-                             InstanceCallInstr* instance_call)
+                      Value* left,
+                      Value* right,
+                      InstanceCallInstr* instance_call)
       : op_kind_(op_kind) {
     ASSERT(left != NULL);
     ASSERT(right != NULL);
@@ -3624,6 +3625,8 @@ class BinaryDoubleOpInstr : public TemplateDefinition<2> {
   DECLARE_INSTRUCTION(BinaryDoubleOp)
   virtual RawAbstractType* CompileType() const;
 
+  virtual Definition* Canonicalize(FlowGraphOptimizer* optimizer);
+
  private:
   const Token::Kind op_kind_;
 
@@ -3682,6 +3685,8 @@ class BinaryMintOpInstr : public TemplateDefinition<2> {
     return deopt_id_;
   }
 
+  virtual Definition* Canonicalize(FlowGraphOptimizer* optimizer);
+
   DECLARE_INSTRUCTION(BinaryMintOp)
 
  private:
@@ -3853,6 +3858,8 @@ class BinarySmiOpInstr : public TemplateDefinition<2> {
 
   virtual void InferRange();
 
+  virtual Definition* Canonicalize(FlowGraphOptimizer* optimizer);
+
  private:
   const Token::Kind op_kind_;
   InstanceCallInstr* instance_call_;