include/llvm/IR/DerivedUser.h

   1 //===- DerivedUser.h - Base for non-IR Users --------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef LLVM_IR_DERIVEDUSER_H
  10 #define LLVM_IR_DERIVEDUSER_H
  11
  12 #include "llvm/IR/User.h"
  13
  14 namespace llvm {
  15
  16 class Type;
  17 class Use;
  18
  19 /// Extension point for the Value hierarchy. All classes outside of lib/IR
  20 /// that wish to inherit from User should instead inherit from DerivedUser
  21 /// instead. Inheriting from this class is discouraged.
  22 ///
  23 /// Generally speaking, Value is the base of a closed class hierarchy
  24 /// that can't be extended by code outside of lib/IR. This class creates a
  25 /// loophole that allows classes outside of lib/IR to extend User to leverage
  26 /// its use/def list machinery.
  27 class DerivedUser : public User {
  28 protected:
  29   using  DeleteValueTy = void (*)(DerivedUser *);
  30
  31 private:
  32   friend class Value;
  33
  34   DeleteValueTy DeleteValue;
  35
  36 public:
  37   DerivedUser(Type *Ty, unsigned VK, Use *U, unsigned NumOps,
  38               DeleteValueTy DeleteValue)
  39       : User(Ty, VK, U, NumOps), DeleteValue(DeleteValue) {}
  40 };
  41
  42 } // end namespace llvm
  43
  44 #endif // LLVM_IR_DERIVEDUSER_H