SkSL performance improvements

src/sksl/ir/SkSLVariable.h

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
  
 #ifndef SKSL_VARIABLE
 #define SKSL_VARIABLE
 
 #include "SkSLModifiers.h"
 #include "SkSLPosition.h"
 #include "SkSLSymbol.h"
 #include "SkSLType.h"
 
 namespace SkSL {
 
 /**
  * Represents a variable, whether local, global, or a function parameter. This represents the
  * variable itself (the storage location), which is shared between all VariableReferences which
  * read or write that storage location.
  */
 struct Variable : public Symbol {
     enum Storage {
         kGlobal_Storage,
         kLocal_Storage,
         kParameter_Storage
     };
 
-    Variable(Position position, Modifiers modifiers, std::string name, std::shared_ptr<Type> type,
+    Variable(Position position, Modifiers modifiers, std::string name, const Type& type,
              Storage storage)
     : INHERITED(position, kVariable_Kind, std::move(name))
     , fModifiers(modifiers)
     , fType(type)
     , fStorage(storage)
     , fIsReadFrom(false)
     , fIsWrittenTo(false) {}
 
     virtual std::string description() const override {
-        return fModifiers.description() + fType->fName + " " + fName;
+        return fModifiers.description() + fType.fName + " " + fName;
     }
 
     const Modifiers fModifiers;
-    const std::string fValue;
-    const std::shared_ptr<Type> fType;
+    const Type& fType;
     const Storage fStorage;
 
     mutable bool fIsReadFrom;
     mutable bool fIsWrittenTo;
 
     typedef Symbol INHERITED;
 };
 
 } // namespace SkSL
 
-namespace std {
-    template <>
-        struct hash<SkSL::Variable> {
-        public :
-        size_t operator()(const SkSL::Variable &var) const{
-            return hash<std::string>()(var.fName) ^ hash<std::string>()(var.fType->description());
-        }
-    };
-} // namespace std
-
 #endif