Constant.h revision 9769ab22265b313171d201b5928688524a01bd87 
1//===-- llvm/Constant.h - Constant class definition -------------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file was developed by the LLVM research group and is distributed under
6// the University of Illinois Open Source License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file contains the declaration of the Constant class.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_CONSTANT_H
15#define LLVM_CONSTANT_H
16
17#include "llvm/User.h"
18
19namespace llvm {
20
21class Constant : public User {
22protected:
23  Constant(const Type *Ty, ValueTy vty, Use *Ops, unsigned NumOps,
24           const std::string& Name = "")
25    : User(Ty, vty, Ops, NumOps, Name) {}
26
27  void destroyConstantImpl();
28public:
29  /// Static constructor to get a '0' constant of arbitrary type...
30  ///
31  static Constant *getNullValue(const Type *Ty);
32
33  /// isNullValue - Return true if this is the value that would be returned by
34  /// getNullValue.
35  virtual bool isNullValue() const = 0;
36
37  virtual void print(std::ostream &O) const;
38
39  // Specialize get/setOperand for Constant's as their operands are always
40  // constants as well.
41  Constant *getOperand(unsigned i) {
42    return static_cast<Constant*>(User::getOperand(i));
43  }
44  const Constant *getOperand(unsigned i) const {
45    return static_cast<const Constant*>(User::getOperand(i));
46  }
47  void setOperand(unsigned i, Constant *C) {
48    User::setOperand(i, C);
49  }
50
51  /// destroyConstant - Called if some element of this constant is no longer
52  /// valid.  At this point only other constants may be on the use_list for this
53  /// constant.  Any constants on our Use list must also be destroy'd.  The
54  /// implementation must be sure to remove the constant from the list of
55  /// available cached constants.  Implementations should call
56  /// destroyConstantImpl as the last thing they do, to destroy all users and
57  /// delete this.
58  virtual void destroyConstant() { assert(0 && "Not reached!"); }
59
60  //// Methods for support type inquiry through isa, cast, and dyn_cast:
61  static inline bool classof(const Constant *) { return true; }
62  static inline bool classof(const GlobalValue *) { return true; }
63  static inline bool classof(const Value *V) {
64    return V->getValueType() == Value::SimpleConstantVal ||
65           V->getValueType() == Value::ConstantExprVal ||
66           V->getValueType() == Value::ConstantAggregateZeroVal ||
67           V->getValueType() == Value::FunctionVal ||
68           V->getValueType() == Value::GlobalVariableVal ||
69           V->getValueType() == Value::UndefValueVal;
70  }
71
72  /// replaceUsesOfWithOnConstant - This method is a special form of
73  /// User::replaceUsesOfWith (which does not work on constants) that does work
74  /// on constants.  Basically this method goes through the trouble of building
75  /// a new constant that is equivalent to the current one, with all uses of
76  /// From replaced with uses of To.  After this construction is completed, all
77  /// of the users of 'this' are replaced to use the new constant, and then
78  /// 'this' is deleted.  In general, you should not call this method, instead,
79  /// use Value::replaceAllUsesWith, which automatically dispatches to this
80  /// method as needed.
81  ///
82  virtual void replaceUsesOfWithOnConstant(Value *From, Value *To,
83                                           bool DisableChecking = false) {
84    // Provide a default implementation for constants (like integers) that
85    // cannot use any other values.  This cannot be called at runtime, but needs
86    // to be here to avoid link errors.
87    assert(getNumOperands() == 0 && "replaceUsesOfWithOnConstant must be "
88           "implemented for all constants that have operands!");
89    assert(0 && "Constants that do not have operands cannot be using 'From'!");
90  }
91
92  /// clearAllValueMaps - This method frees all internal memory used by the
93  /// constant subsystem, which can be used in environments where this memory
94  /// is otherwise reported as a leak.
95  static void clearAllValueMaps();
96};
97
98} // End llvm namespace
99
100#endif
101