1 //===-- llvm/User.h - User class definition ---------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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
14 // * Instructions are the largest class of Users.
15 // * Constants may be users of other constants (think arrays and stuff)
17 //===----------------------------------------------------------------------===//
19 #ifndef LLVM_IR_USER_H
20 #define LLVM_IR_USER_H
22 #include "llvm/ADT/iterator.h"
23 #include "llvm/ADT/iterator_range.h"
24 #include "llvm/IR/Value.h"
25 #include "llvm/Support/ErrorHandling.h"
29 /// \brief Compile-time customization of User operands.
31 /// Customizes operand-related allocators and accessors.
35 class User : public Value {
36 User(const User &) = delete;
37 void *operator new(size_t) = delete;
39 friend struct HungoffOperandTraits;
40 virtual void anchor();
42 /// \brief This is a pointer to the array of Uses for this User.
44 /// For nodes of fixed arity (e.g. a binary operator) this array will live
45 /// prefixed to some derived class instance. For nodes of resizable variable
46 /// arity (e.g. PHINodes, SwitchInst etc.), this memory will be dynamically
47 /// allocated and should be destroyed by the classes' virtual dtor.
50 void *operator new(size_t s, unsigned Us);
51 User(Type *ty, unsigned vty, Use *OpList, unsigned NumOps)
52 : Value(ty, vty), OperandList(OpList) {
56 /// \brief Allocate the array of Uses, followed by a pointer
57 /// (with bottom bit set) to the User.
58 /// \param IsPhi identifies callers which are phi nodes and which need
59 /// N BasicBlock* allocated along with N
60 Use *allocHungoffUses(unsigned N, bool IsPhi = false);
61 void dropHungoffUses() {
62 Use::zap(OperandList, OperandList + NumOperands, true);
63 OperandList = nullptr;
64 // Reset NumOperands so User::operator delete() does the right thing.
68 ~User() override { Use::zap(OperandList, OperandList + NumOperands); }
69 /// \brief Free memory allocated for User and Use objects.
70 void operator delete(void *Usr);
71 /// \brief Placement delete - required by std, but never called.
72 void operator delete(void*, unsigned) {
73 llvm_unreachable("Constructor throws?");
75 /// \brief Placement delete - required by std, but never called.
76 void operator delete(void*, unsigned, bool) {
77 llvm_unreachable("Constructor throws?");
80 template <int Idx, typename U> static Use &OpFrom(const U *that) {
82 ? OperandTraits<U>::op_end(const_cast<U*>(that))[Idx]
83 : OperandTraits<U>::op_begin(const_cast<U*>(that))[Idx];
85 template <int Idx> Use &Op() {
86 return OpFrom<Idx>(this);
88 template <int Idx> const Use &Op() const {
89 return OpFrom<Idx>(this);
92 Value *getOperand(unsigned i) const {
93 assert(i < NumOperands && "getOperand() out of range!");
94 return OperandList[i];
96 void setOperand(unsigned i, Value *Val) {
97 assert(i < NumOperands && "setOperand() out of range!");
98 assert((!isa<Constant>((const Value*)this) ||
99 isa<GlobalValue>((const Value*)this)) &&
100 "Cannot mutate a constant with setOperand!");
101 OperandList[i] = Val;
103 const Use &getOperandUse(unsigned i) const {
104 assert(i < NumOperands && "getOperandUse() out of range!");
105 return OperandList[i];
107 Use &getOperandUse(unsigned i) {
108 assert(i < NumOperands && "getOperandUse() out of range!");
109 return OperandList[i];
112 unsigned getNumOperands() const { return NumOperands; }
114 // ---------------------------------------------------------------------------
115 // Operand Iterator interface...
117 typedef Use* op_iterator;
118 typedef const Use* const_op_iterator;
119 typedef iterator_range<op_iterator> op_range;
120 typedef iterator_range<const_op_iterator> const_op_range;
122 inline op_iterator op_begin() { return OperandList; }
123 inline const_op_iterator op_begin() const { return OperandList; }
124 inline op_iterator op_end() { return OperandList+NumOperands; }
125 inline const_op_iterator op_end() const { return OperandList+NumOperands; }
126 inline op_range operands() {
127 return op_range(op_begin(), op_end());
129 inline const_op_range operands() const {
130 return const_op_range(op_begin(), op_end());
133 /// \brief Iterator for directly iterating over the operand Values.
134 struct value_op_iterator
135 : iterator_adaptor_base<value_op_iterator, op_iterator,
136 std::random_access_iterator_tag, Value *,
137 ptrdiff_t, Value *, Value *> {
138 explicit value_op_iterator(Use *U = nullptr) : iterator_adaptor_base(U) {}
140 Value *operator*() const { return *I; }
141 Value *operator->() const { return operator*(); }
144 inline value_op_iterator value_op_begin() {
145 return value_op_iterator(op_begin());
147 inline value_op_iterator value_op_end() {
148 return value_op_iterator(op_end());
150 inline iterator_range<value_op_iterator> operand_values() {
151 return iterator_range<value_op_iterator>(value_op_begin(), value_op_end());
154 /// \brief Drop all references to operands.
156 /// This function is in charge of "letting go" of all objects that this User
157 /// refers to. This allows one to 'delete' a whole class at a time, even
158 /// though there may be circular references... First all references are
159 /// dropped, and all use counts go to zero. Then everything is deleted for
160 /// real. Note that no operations are valid on an object that has "dropped
161 /// all references", except operator delete.
162 void dropAllReferences() {
163 for (Use &U : operands())
167 /// \brief Replace uses of one Value with another.
169 /// Replaces all references to the "From" definition with references to the
171 void replaceUsesOfWith(Value *From, Value *To);
173 // Methods for support type inquiry through isa, cast, and dyn_cast:
174 static inline bool classof(const Value *V) {
175 return isa<Instruction>(V) || isa<Constant>(V);
179 template<> struct simplify_type<User::op_iterator> {
180 typedef Value* SimpleType;
181 static SimpleType getSimplifiedValue(User::op_iterator &Val) {
185 template<> struct simplify_type<User::const_op_iterator> {
186 typedef /*const*/ Value* SimpleType;
187 static SimpleType getSimplifiedValue(User::const_op_iterator &Val) {
192 } // End llvm namespace