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_IR_USER_H
20#define LLVM_IR_USER_H
21
22#include "llvm/IR/Value.h"
23#include "llvm/Support/ErrorHandling.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  /// Convenience iterator for directly iterating over the Values in the
122  /// OperandList
123  class value_op_iterator : public std::iterator<std::forward_iterator_tag,
124                                                 Value*> {
125    op_iterator OI;
126  public:
127    explicit value_op_iterator(Use *U) : OI(U) {}
128
129    bool operator==(const value_op_iterator &x) const {
130      return OI == x.OI;
131    }
132    bool operator!=(const value_op_iterator &x) const {
133      return !operator==(x);
134    }
135
136    /// Iterator traversal: forward iteration only
137    value_op_iterator &operator++() {          // Preincrement
138      ++OI;
139      return *this;
140    }
141    value_op_iterator operator++(int) {        // Postincrement
142      value_op_iterator tmp = *this; ++*this; return tmp;
143    }
144
145    /// Retrieve a pointer to the current Value.
146    Value *operator*() const {
147      return *OI;
148    }
149
150    Value *operator->() const { return operator*(); }
151  };
152
153  inline value_op_iterator value_op_begin() {
154    return value_op_iterator(op_begin());
155  }
156  inline value_op_iterator value_op_end() {
157    return value_op_iterator(op_end());
158  }
159
160  // dropAllReferences() - This function is in charge of "letting go" of all
161  // objects that this User refers to.  This allows one to
162  // 'delete' a whole class at a time, even though there may be circular
163  // references...  First all references are dropped, and all use counts go to
164  // zero.  Then everything is deleted for real.  Note that no operations are
165  // valid on an object that has "dropped all references", except operator
166  // delete.
167  //
168  void dropAllReferences() {
169    for (op_iterator i = op_begin(), e = op_end(); i != e; ++i)
170      i->set(0);
171  }
172
173  /// replaceUsesOfWith - Replaces all references to the "From" definition with
174  /// references to the "To" definition.
175  ///
176  void replaceUsesOfWith(Value *From, Value *To);
177
178  // Methods for support type inquiry through isa, cast, and dyn_cast:
179  static inline bool classof(const Value *V) {
180    return isa<Instruction>(V) || isa<Constant>(V);
181  }
182};
183
184template<> struct simplify_type<User::op_iterator> {
185  typedef Value* SimpleType;
186  static SimpleType getSimplifiedValue(User::op_iterator &Val) {
187    return Val->get();
188  }
189};
190template<> struct simplify_type<User::const_op_iterator> {
191  typedef /*const*/ Value* SimpleType;
192  static SimpleType getSimplifiedValue(User::const_op_iterator &Val) {
193    return Val->get();
194  }
195};
196
197// value_use_iterator::getOperandNo - Requires the definition of the User class.
198template<typename UserTy>
199unsigned value_use_iterator<UserTy>::getOperandNo() const {
200  return U - U->getUser()->op_begin();
201}
202
203} // End llvm namespace
204
205#endif
206