Refactor building of StoreStaticField and StoreLocal to manually preserve value.

runtime/vm/flow_graph_builder.h

Index: runtime/vm/flow_graph_builder.h
diff --git a/runtime/vm/flow_graph_builder.h b/runtime/vm/flow_graph_builder.h
index d800699b97bc3a460acb383fa27d35f8be07a8b9..1fb97e5d309d0ad2306fd4428fd4fb34a49bd11e 100644
--- a/runtime/vm/flow_graph_builder.h
+++ b/runtime/vm/flow_graph_builder.h
@@ -161,9 +161,13 @@ class EffectGraphVisitor : public AstNodeVisitor {
   }
 
  protected:
-  Definition* BuildStoreLocal(const LocalVariable& local, Value* value);
+  Definition* BuildStoreLocal(const LocalVariable& local,
+                              Value* value,
+                              bool result_is_needed);
   Definition* BuildLoadLocal(const LocalVariable& local);
 
+  void VisitStoreLocal(StoreLocalNode* node, bool result_is_needed);
+
   // Helpers for translating parts of the AST.
   void TranslateArgumentList(const ArgumentListNode& node,
                              ZoneGrowableArray<Value*>* values);
@@ -206,10 +210,8 @@ class EffectGraphVisitor : public AstNodeVisitor {
                               const AbstractType& dst_type,
                               const String& dst_name);
 
-  enum ResultKind {
-    kResultNotNeeded,
-    kResultNeeded
-  };
+  static const bool kResultNeeded = true;
+  static const bool kResultNotNeeded = false;
 
   Definition* BuildStoreIndexedValues(StoreIndexedNode* node,
                                       bool result_is_needed);
@@ -244,6 +246,8 @@ class EffectGraphVisitor : public AstNodeVisitor {
   void BuildThrowNode(ThrowNode* node);
 
   void BuildStaticSetter(StaticSetterNode* node, bool result_is_needed);
+  Definition* BuildStoreStaticField(StoreStaticFieldNode* node,
+                                    bool result_is_needed);
 
   ClosureCallInstr* BuildClosureCall(ClosureCallNode* node);
 
@@ -291,12 +295,14 @@ class ValueGraphVisitor : public EffectGraphVisitor {
   virtual void VisitBinaryOpNode(BinaryOpNode* node);
   virtual void VisitConditionalExprNode(ConditionalExprNode* node);
   virtual void VisitLoadLocalNode(LoadLocalNode* node);
+  virtual void VisitStoreLocalNode(StoreLocalNode* node);
   virtual void VisitStoreIndexedNode(StoreIndexedNode* node);
   virtual void VisitStoreInstanceFieldNode(StoreInstanceFieldNode* node);
   virtual void VisitInstanceSetterNode(InstanceSetterNode* node);
   virtual void VisitThrowNode(ThrowNode* node);
   virtual void VisitClosureCallNode(ClosureCallNode* node);
   virtual void VisitStaticSetterNode(StaticSetterNode* node);
+  virtual void VisitStoreStaticFieldNode(StoreStaticFieldNode* node);
 
   Value* value() const { return value_; }