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/AlignOf.h"
26 #include "llvm/Support/ErrorHandling.h"
30 /// \brief Compile-time customization of User operands.
32 /// Customizes operand-related allocators and accessors.
36 class User : public Value {
37 User(const User &) = delete;
39 friend struct HungoffOperandTraits;
40 virtual void anchor();
43 /// Allocate a User with an operand pointer co-allocated.
45 /// This is used for subclasses which need to allocate a variable number
46 /// of operands, ie, 'hung off uses'.
47 void *operator new(size_t Size);
49 /// Allocate a User with the operands co-allocated.
51 /// This is used for subclasses which have a fixed number of operands.
52 void *operator new(size_t Size, unsigned Us);
54 User(Type *ty, unsigned vty, Use *OpList, unsigned NumOps)
56 assert(NumOps < (1u << NumUserOperandsBits) && "Too many operands");
57 NumUserOperands = NumOps;
58 // If we have hung off uses, then the operand list should initially be
60 assert((!HasHungOffUses || !getOperandList()) &&
61 "Error in initializing hung off uses for User");
64 /// \brief Allocate the array of Uses, followed by a pointer
65 /// (with bottom bit set) to the User.
66 /// \param IsPhi identifies callers which are phi nodes and which need
67 /// N BasicBlock* allocated along with N
68 void allocHungoffUses(unsigned N, bool IsPhi = false);
70 /// \brief Grow the number of hung off uses. Note that allocHungoffUses
71 /// should be called if there are no uses.
72 void growHungoffUses(unsigned N, bool IsPhi = false);
77 /// \brief Free memory allocated for User and Use objects.
78 void operator delete(void *Usr);
79 /// \brief Placement delete - required by std, but never called.
80 void operator delete(void*, unsigned) {
81 llvm_unreachable("Constructor throws?");
83 /// \brief Placement delete - required by std, but never called.
84 void operator delete(void*, unsigned, bool) {
85 llvm_unreachable("Constructor throws?");
88 template <int Idx, typename U> static Use &OpFrom(const U *that) {
90 ? OperandTraits<U>::op_end(const_cast<U*>(that))[Idx]
91 : OperandTraits<U>::op_begin(const_cast<U*>(that))[Idx];
93 template <int Idx> Use &Op() {
94 return OpFrom<Idx>(this);
96 template <int Idx> const Use &Op() const {
97 return OpFrom<Idx>(this);
100 Use *&getHungOffOperands() { return *(reinterpret_cast<Use **>(this) - 1); }
102 Use *getIntrusiveOperands() {
103 return reinterpret_cast<Use *>(this) - NumUserOperands;
106 void setOperandList(Use *NewList) {
107 assert(HasHungOffUses &&
108 "Setting operand list only required for hung off uses");
109 getHungOffOperands() = NewList;
112 Use *getOperandList() {
113 return HasHungOffUses ? getHungOffOperands() : getIntrusiveOperands();
115 const Use *getOperandList() const {
116 return const_cast<User *>(this)->getOperandList();
118 Value *getOperand(unsigned i) const {
119 assert(i < NumUserOperands && "getOperand() out of range!");
120 return getOperandList()[i];
122 void setOperand(unsigned i, Value *Val) {
123 assert(i < NumUserOperands && "setOperand() out of range!");
124 assert((!isa<Constant>((const Value*)this) ||
125 isa<GlobalValue>((const Value*)this)) &&
126 "Cannot mutate a constant with setOperand!");
127 getOperandList()[i] = Val;
129 const Use &getOperandUse(unsigned i) const {
130 assert(i < NumUserOperands && "getOperandUse() out of range!");
131 return getOperandList()[i];
133 Use &getOperandUse(unsigned i) {
134 assert(i < NumUserOperands && "getOperandUse() out of range!");
135 return getOperandList()[i];
138 unsigned getNumOperands() const { return NumUserOperands; }
140 /// Set the number of operands on a GlobalVariable.
142 /// GlobalVariable always allocates space for a single operands, but
143 /// doesn't always use it.
145 /// FIXME: As that the number of operands is used to find the start of
146 /// the allocated memory in operator delete, we need to always think we have
147 /// 1 operand before delete.
148 void setGlobalVariableNumOperands(unsigned NumOps) {
149 assert(NumOps <= 1 && "GlobalVariable can only have 0 or 1 operands");
150 NumUserOperands = NumOps;
153 /// \brief Subclasses with hung off uses need to manage the operand count
154 /// themselves. In these instances, the operand count isn't used to find the
155 /// OperandList, so there's no issue in having the operand count change.
156 void setNumHungOffUseOperands(unsigned NumOps) {
157 assert(HasHungOffUses && "Must have hung off uses to use this method");
158 assert(NumOps < (1u << NumUserOperandsBits) && "Too many operands");
159 NumUserOperands = NumOps;
162 // ---------------------------------------------------------------------------
163 // Operand Iterator interface...
165 typedef Use* op_iterator;
166 typedef const Use* const_op_iterator;
167 typedef iterator_range<op_iterator> op_range;
168 typedef iterator_range<const_op_iterator> const_op_range;
170 op_iterator op_begin() { return getOperandList(); }
171 const_op_iterator op_begin() const { return getOperandList(); }
172 op_iterator op_end() {
173 return getOperandList() + NumUserOperands;
175 const_op_iterator op_end() const {
176 return getOperandList() + NumUserOperands;
178 op_range operands() {
179 return op_range(op_begin(), op_end());
181 const_op_range operands() const {
182 return const_op_range(op_begin(), op_end());
185 /// \brief Iterator for directly iterating over the operand Values.
186 struct value_op_iterator
187 : iterator_adaptor_base<value_op_iterator, op_iterator,
188 std::random_access_iterator_tag, Value *,
189 ptrdiff_t, Value *, Value *> {
190 explicit value_op_iterator(Use *U = nullptr) : iterator_adaptor_base(U) {}
192 Value *operator*() const { return *I; }
193 Value *operator->() const { return operator*(); }
196 value_op_iterator value_op_begin() {
197 return value_op_iterator(op_begin());
199 value_op_iterator value_op_end() {
200 return value_op_iterator(op_end());
202 iterator_range<value_op_iterator> operand_values() {
203 return iterator_range<value_op_iterator>(value_op_begin(), value_op_end());
206 /// \brief Drop all references to operands.
208 /// This function is in charge of "letting go" of all objects that this User
209 /// refers to. This allows one to 'delete' a whole class at a time, even
210 /// though there may be circular references... First all references are
211 /// dropped, and all use counts go to zero. Then everything is deleted for
212 /// real. Note that no operations are valid on an object that has "dropped
213 /// all references", except operator delete.
214 void dropAllReferences() {
215 for (Use &U : operands())
219 /// \brief Replace uses of one Value with another.
221 /// Replaces all references to the "From" definition with references to the
223 void replaceUsesOfWith(Value *From, Value *To);
225 // Methods for support type inquiry through isa, cast, and dyn_cast:
226 static inline bool classof(const Value *V) {
227 return isa<Instruction>(V) || isa<Constant>(V);
230 // Either Use objects, or a Use pointer can be prepended to User.
231 static_assert(AlignOf<Use>::Alignment >= AlignOf<User>::Alignment,
232 "Alignment is insufficient after objects prepended to User");
233 static_assert(AlignOf<Use *>::Alignment >= AlignOf<User>::Alignment,
234 "Alignment is insufficient after objects prepended to User");
236 template<> struct simplify_type<User::op_iterator> {
237 typedef Value* SimpleType;
238 static SimpleType getSimplifiedValue(User::op_iterator &Val) {
242 template<> struct simplify_type<User::const_op_iterator> {
243 typedef /*const*/ Value* SimpleType;
244 static SimpleType getSimplifiedValue(User::const_op_iterator &Val) {
249 } // End llvm namespace