1//===-- llvm/User.h - User class definition ---------------------*- 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// This class defines the interface that one who uses a Value must implement.
11// Each instance of the Value class keeps track of what User's have handles
12// to it.
13//
14//  * Instructions are the largest class of Users.
15//  * Constants may be users of other constants (think arrays and stuff)
16//
17//===----------------------------------------------------------------------===//
18
19#ifndef LLVM_USER_H
20#define LLVM_USER_H
21
22#include "llvm/Support/ErrorHandling.h"
23#include "llvm/Value.h"
24
25namespace llvm {
26
27/// OperandTraits - Compile-time customization of
28/// operand-related allocators and accessors
29/// for use of the User class
30template <class>
31struct OperandTraits;
32
33class User : public Value {
34  User(const User &) LLVM_DELETED_FUNCTION;
35  void *operator new(size_t) LLVM_DELETED_FUNCTION;
36  template <unsigned>
37  friend struct HungoffOperandTraits;
38  virtual void anchor();
39protected:
40  /// OperandList - This is a pointer to the array of Uses for this User.
41  /// For nodes of fixed arity (e.g. a binary operator) this array will live
42  /// prefixed to some derived class instance.  For nodes of resizable variable
43  /// arity (e.g. PHINodes, SwitchInst etc.), this memory will be dynamically
44  /// allocated and should be destroyed by the classes' virtual dtor.
45  Use *OperandList;
46
47  /// NumOperands - The number of values used by this User.
48  ///
49  unsigned NumOperands;
50
51  void *operator new(size_t s, unsigned Us);
52  User(Type *ty, unsigned vty, Use *OpList, unsigned NumOps)
53    : Value(ty, vty), OperandList(OpList), NumOperands(NumOps) {}
54  Use *allocHungoffUses(unsigned) const;
55  void dropHungoffUses() {
56    Use::zap(OperandList, OperandList + NumOperands, true);
57    OperandList = 0;
58    // Reset NumOperands so User::operator delete() does the right thing.
59    NumOperands = 0;
60  }
61public:
62  ~User() {
63    Use::zap(OperandList, OperandList + NumOperands);
64  }
65  /// operator delete - free memory allocated for User and Use objects
66  void operator delete(void *Usr);
67  /// placement delete - required by std, but never called.
68  void operator delete(void*, unsigned) {
69    llvm_unreachable("Constructor throws?");
70  }
71  /// placement delete - required by std, but never called.
72  void operator delete(void*, unsigned, bool) {
73    llvm_unreachable("Constructor throws?");
74  }
75protected:
76  template <int Idx, typename U> static Use &OpFrom(const U *that) {
77    return Idx < 0
78      ? OperandTraits<U>::op_end(const_cast<U*>(that))[Idx]
79      : OperandTraits<U>::op_begin(const_cast<U*>(that))[Idx];
80  }
81  template <int Idx> Use &Op() {
82    return OpFrom<Idx>(this);
83  }
84  template <int Idx> const Use &Op() const {
85    return OpFrom<Idx>(this);
86  }
87public:
88  Value *getOperand(unsigned i) const {
89    assert(i < NumOperands && "getOperand() out of range!");
90    return OperandList[i];
91  }
92  void setOperand(unsigned i, Value *Val) {
93    assert(i < NumOperands && "setOperand() out of range!");
94    assert((!isa<Constant>((const Value*)this) ||
95            isa<GlobalValue>((const Value*)this)) &&
96           "Cannot mutate a constant with setOperand!");
97    OperandList[i] = Val;
98  }
99  const Use &getOperandUse(unsigned i) const {
100    assert(i < NumOperands && "getOperandUse() out of range!");
101    return OperandList[i];
102  }
103  Use &getOperandUse(unsigned i) {
104    assert(i < NumOperands && "getOperandUse() out of range!");
105    return OperandList[i];
106  }
107
108  unsigned getNumOperands() const { return NumOperands; }
109
110  // ---------------------------------------------------------------------------
111  // Operand Iterator interface...
112  //
113  typedef Use*       op_iterator;
114  typedef const Use* const_op_iterator;
115
116  inline op_iterator       op_begin()       { return OperandList; }
117  inline const_op_iterator op_begin() const { return OperandList; }
118  inline op_iterator       op_end()         { return OperandList+NumOperands; }
119  inline const_op_iterator op_end()   const { return OperandList+NumOperands; }
120
121  // dropAllReferences() - This function is in charge of "letting go" of all
122  // objects that this User refers to.  This allows one to
123  // 'delete' a whole class at a time, even though there may be circular
124  // references...  First all references are dropped, and all use counts go to
125  // zero.  Then everything is deleted for real.  Note that no operations are
126  // valid on an object that has "dropped all references", except operator
127  // delete.
128  //
129  void dropAllReferences() {
130    for (op_iterator i = op_begin(), e = op_end(); i != e; ++i)
131      i->set(0);
132  }
133
134  /// replaceUsesOfWith - Replaces all references to the "From" definition with
135  /// references to the "To" definition.
136  ///
137  void replaceUsesOfWith(Value *From, Value *To);
138
139  // Methods for support type inquiry through isa, cast, and dyn_cast:
140  static inline bool classof(const User *) { return true; }
141  static inline bool classof(const Value *V) {
142    return isa<Instruction>(V) || isa<Constant>(V);
143  }
144};
145
146template<> struct simplify_type<User::op_iterator> {
147  typedef Value* SimpleType;
148
149  static SimpleType getSimplifiedValue(const User::op_iterator &Val) {
150    return static_cast<SimpleType>(Val->get());
151  }
152};
153
154template<> struct simplify_type<const User::op_iterator>
155  : public simplify_type<User::op_iterator> {};
156
157template<> struct simplify_type<User::const_op_iterator> {
158  typedef Value* SimpleType;
159
160  static SimpleType getSimplifiedValue(const User::const_op_iterator &Val) {
161    return static_cast<SimpleType>(Val->get());
162  }
163};
164
165template<> struct simplify_type<const User::const_op_iterator>
166  : public simplify_type<User::const_op_iterator> {};
167
168
169// value_use_iterator::getOperandNo - Requires the definition of the User class.
170template<typename UserTy>
171unsigned value_use_iterator<UserTy>::getOperandNo() const {
172  return U - U->getUser()->op_begin();
173}
174
175} // End llvm namespace
176
177#endif
178