Implement simple effect typing for variables

src/typing.h

Index: src/typing.h
diff --git a/src/typing.h b/src/typing.h
index ceef9843650a190e091943f02fc3c3a1546620ce..c942b0063278708d4c4828652ebd7d9365943717 100644
--- a/src/typing.h
+++ b/src/typing.h
@@ -35,6 +35,7 @@
 #include "compiler.h"
 #include "type-info.h"
 #include "types.h"
+#include "effects.h"
 #include "zone.h"
 #include "scopes.h"
 
@@ -57,8 +58,13 @@ class AstTyper: public AstVisitor {
  private:
   explicit AstTyper(CompilationInfo* info);
 
+  static const int kNoVar = INT_MIN;
+  typedef v8::internal::Effects<int, kNoVar> Effects;
+  typedef v8::internal::NestedEffects<int, kNoVar> Store;
+
   CompilationInfo* info_;
   TypeFeedbackOracle oracle_;
+  Store store_;
 
   TypeFeedbackOracle* oracle() { return &oracle_; }
   Zone* zone() const { return info_->zone(); }
@@ -70,6 +76,17 @@ class AstTyper: public AstVisitor {
     e->set_bounds(Bounds::NarrowLower(e->bounds(), t, isolate_));
   }
 
+  Effects EnterEffects() {
+    store_ = store_.Push();
+    return store_.Top();
+  }
+  void ExitEffects() { store_ = store_.Pop(); }
+
+  int variable_index(Variable* var) {
+    return var->IsStackLocal() ? var->index() :
+           var->IsParameter() ? -var->index() : kNoVar;
+  }
+
   void VisitDeclarations(ZoneList<Declaration*>* declarations);
   void VisitStatements(ZoneList<Statement*>* statements);