[interpreter] Faster and fewer flushes in register optimizer.

src/interpreter/bytecode-register-optimizer.h

Index: src/interpreter/bytecode-register-optimizer.h
diff --git a/src/interpreter/bytecode-register-optimizer.h b/src/interpreter/bytecode-register-optimizer.h
index f1de6fb1c37e562410ade99fba8c1d7f3934264a..4229610b1cd06b5e9afd1dbb6a46180de5a4d24b 100644
--- a/src/interpreter/bytecode-register-optimizer.h
+++ b/src/interpreter/bytecode-register-optimizer.h
@@ -93,6 +93,8 @@ class BytecodeRegisterOptimizer final : public BytecodePipelineStage,
   RegisterInfo* GetMaterializedEquivalent(RegisterInfo* info);
   RegisterInfo* GetMaterializedEquivalentNotAccumulator(RegisterInfo* info);
   void Materialize(RegisterInfo* info);
+  void AddToEquivalenceSet(RegisterInfo* set_member,
+                           RegisterInfo* non_set_member);
 
   // Methods for finding and creating metadata for each register.
   RegisterInfo* GetOrCreateRegisterInfo(Register reg);
@@ -140,7 +142,7 @@ class BytecodeRegisterOptimizer final : public BytecodePipelineStage,
   int equivalence_id_;
 
   BytecodePipelineStage* next_stage_;
-  bool flushed_;
+  bool flush_required_;
   Zone* zone_;
 
   DISALLOW_COPY_AND_ASSIGN(BytecodeRegisterOptimizer);