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       1             : //===- DerivedUser.h - Base for non-IR Users --------------------*- C++ -*-===//
       2             : //
       3             : //                     The LLVM Compiler Infrastructure
       4             : //
       5             : // This file is distributed under the University of Illinois Open Source
       6             : // License. See LICENSE.TXT for details.
       7             : //
       8             : //===----------------------------------------------------------------------===//
       9             : 
      10             : #ifndef LLVM_IR_DERIVEDUSER_H
      11             : #define LLVM_IR_DERIVEDUSER_H
      12             : 
      13             : #include "llvm/IR/User.h"
      14             : 
      15             : namespace llvm {
      16             : 
      17             : class Type;
      18             : class Use;
      19             : 
      20             : /// Extension point for the Value hierarchy. All classes outside of lib/IR
      21             : /// that wish to inherit from User should instead inherit from DerivedUser
      22             : /// instead. Inheriting from this class is discouraged.
      23             : ///
      24             : /// Generally speaking, Value is the base of a closed class hierarchy
      25             : /// that can't be extended by code outside of lib/IR. This class creates a
      26             : /// loophole that allows classes outside of lib/IR to extend User to leverage
      27             : /// its use/def list machinery.
      28             : class DerivedUser : public User {
      29             : protected:
      30             :   using  DeleteValueTy = void (*)(DerivedUser *);
      31             : 
      32             : private:
      33             :   friend class Value;
      34             : 
      35             :   DeleteValueTy DeleteValue;
      36             : 
      37             : public:
      38             :   DerivedUser(Type *Ty, unsigned VK, Use *U, unsigned NumOps,
      39             :               DeleteValueTy DeleteValue)
      40     1820877 :       : User(Ty, VK, U, NumOps), DeleteValue(DeleteValue) {}
      41             : };
      42             : 
      43             : } // end namespace llvm
      44             : 
      45             : #endif // LLVM_IR_DERIVEDUSER_H