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/Use.h"
25 #include "llvm/IR/Value.h"
26 #include "llvm/Support/Casting.h"
27 #include "llvm/Support/Compiler.h"
28 #include "llvm/Support/ErrorHandling.h"
36 template <typename T> class ArrayRef;
37 template <typename T> class MutableArrayRef;
39 /// \brief Compile-time customization of User operands.
41 /// Customizes operand-related allocators and accessors.
45 class User : public Value {
47 friend struct HungoffOperandTraits;
49 LLVM_ATTRIBUTE_ALWAYS_INLINE inline static void *
50 allocateFixedOperandUser(size_t, unsigned, unsigned);
53 /// Allocate a User with an operand pointer co-allocated.
55 /// This is used for subclasses which need to allocate a variable number
56 /// of operands, ie, 'hung off uses'.
57 void *operator new(size_t Size);
59 /// Allocate a User with the operands co-allocated.
61 /// This is used for subclasses which have a fixed number of operands.
62 void *operator new(size_t Size, unsigned Us);
64 /// Allocate a User with the operands co-allocated. If DescBytes is non-zero
65 /// then allocate an additional DescBytes bytes before the operands. These
66 /// bytes can be accessed by calling getDescriptor.
68 /// DescBytes needs to be divisible by sizeof(void *). The allocated
69 /// descriptor, if any, is aligned to sizeof(void *) bytes.
71 /// This is used for subclasses which have a fixed number of operands.
72 void *operator new(size_t Size, unsigned Us, unsigned DescBytes);
74 User(Type *ty, unsigned vty, Use *, unsigned NumOps)
76 assert(NumOps < (1u << NumUserOperandsBits) && "Too many operands");
77 NumUserOperands = NumOps;
78 // If we have hung off uses, then the operand list should initially be
80 assert((!HasHungOffUses || !getOperandList()) &&
81 "Error in initializing hung off uses for User");
84 /// \brief Allocate the array of Uses, followed by a pointer
85 /// (with bottom bit set) to the User.
86 /// \param IsPhi identifies callers which are phi nodes and which need
87 /// N BasicBlock* allocated along with N
88 void allocHungoffUses(unsigned N, bool IsPhi = false);
90 /// \brief Grow the number of hung off uses. Note that allocHungoffUses
91 /// should be called if there are no uses.
92 void growHungoffUses(unsigned N, bool IsPhi = false);
95 ~User() = default; // Use deleteValue() to delete a generic Instruction.
98 User(const User &) = delete;
100 /// \brief Free memory allocated for User and Use objects.
101 void operator delete(void *Usr);
102 /// \brief Placement delete - required by std, but never called.
103 void operator delete(void*, unsigned) {
104 llvm_unreachable("Constructor throws?");
106 /// \brief Placement delete - required by std, but never called.
107 void operator delete(void*, unsigned, bool) {
108 llvm_unreachable("Constructor throws?");
112 template <int Idx, typename U> static Use &OpFrom(const U *that) {
114 ? OperandTraits<U>::op_end(const_cast<U*>(that))[Idx]
115 : OperandTraits<U>::op_begin(const_cast<U*>(that))[Idx];
118 template <int Idx> Use &Op() {
119 return OpFrom<Idx>(this);
121 template <int Idx> const Use &Op() const {
122 return OpFrom<Idx>(this);
126 const Use *getHungOffOperands() const {
127 return *(reinterpret_cast<const Use *const *>(this) - 1);
130 Use *&getHungOffOperands() { return *(reinterpret_cast<Use **>(this) - 1); }
132 const Use *getIntrusiveOperands() const {
133 return reinterpret_cast<const Use *>(this) - NumUserOperands;
136 Use *getIntrusiveOperands() {
137 return reinterpret_cast<Use *>(this) - NumUserOperands;
140 void setOperandList(Use *NewList) {
141 assert(HasHungOffUses &&
142 "Setting operand list only required for hung off uses");
143 getHungOffOperands() = NewList;
147 const Use *getOperandList() const {
148 return HasHungOffUses ? getHungOffOperands() : getIntrusiveOperands();
150 Use *getOperandList() {
151 return const_cast<Use *>(static_cast<const User *>(this)->getOperandList());
154 Value *getOperand(unsigned i) const {
155 assert(i < NumUserOperands && "getOperand() out of range!");
156 return getOperandList()[i];
159 void setOperand(unsigned i, Value *Val) {
160 assert(i < NumUserOperands && "setOperand() out of range!");
161 assert((!isa<Constant>((const Value*)this) ||
162 isa<GlobalValue>((const Value*)this)) &&
163 "Cannot mutate a constant with setOperand!");
164 getOperandList()[i] = Val;
167 const Use &getOperandUse(unsigned i) const {
168 assert(i < NumUserOperands && "getOperandUse() out of range!");
169 return getOperandList()[i];
171 Use &getOperandUse(unsigned i) {
172 assert(i < NumUserOperands && "getOperandUse() out of range!");
173 return getOperandList()[i];
176 unsigned getNumOperands() const { return NumUserOperands; }
178 /// Returns the descriptor co-allocated with this User instance.
179 ArrayRef<const uint8_t> getDescriptor() const;
181 /// Returns the descriptor co-allocated with this User instance.
182 MutableArrayRef<uint8_t> getDescriptor();
184 /// Set the number of operands on a GlobalVariable.
186 /// GlobalVariable always allocates space for a single operands, but
187 /// doesn't always use it.
189 /// FIXME: As that the number of operands is used to find the start of
190 /// the allocated memory in operator delete, we need to always think we have
191 /// 1 operand before delete.
192 void setGlobalVariableNumOperands(unsigned NumOps) {
193 assert(NumOps <= 1 && "GlobalVariable can only have 0 or 1 operands");
194 NumUserOperands = NumOps;
197 /// \brief Subclasses with hung off uses need to manage the operand count
198 /// themselves. In these instances, the operand count isn't used to find the
199 /// OperandList, so there's no issue in having the operand count change.
200 void setNumHungOffUseOperands(unsigned NumOps) {
201 assert(HasHungOffUses && "Must have hung off uses to use this method");
202 assert(NumOps < (1u << NumUserOperandsBits) && "Too many operands");
203 NumUserOperands = NumOps;
206 // ---------------------------------------------------------------------------
207 // Operand Iterator interface...
209 using op_iterator = Use*;
210 using const_op_iterator = const Use*;
211 using op_range = iterator_range<op_iterator>;
212 using const_op_range = iterator_range<const_op_iterator>;
214 op_iterator op_begin() { return getOperandList(); }
215 const_op_iterator op_begin() const { return getOperandList(); }
216 op_iterator op_end() {
217 return getOperandList() + NumUserOperands;
219 const_op_iterator op_end() const {
220 return getOperandList() + NumUserOperands;
222 op_range operands() {
223 return op_range(op_begin(), op_end());
225 const_op_range operands() const {
226 return const_op_range(op_begin(), op_end());
229 /// \brief Iterator for directly iterating over the operand Values.
230 struct value_op_iterator
231 : iterator_adaptor_base<value_op_iterator, op_iterator,
232 std::random_access_iterator_tag, Value *,
233 ptrdiff_t, Value *, Value *> {
234 explicit value_op_iterator(Use *U = nullptr) : iterator_adaptor_base(U) {}
236 Value *operator*() const { return *I; }
237 Value *operator->() const { return operator*(); }
240 value_op_iterator value_op_begin() {
241 return value_op_iterator(op_begin());
243 value_op_iterator value_op_end() {
244 return value_op_iterator(op_end());
246 iterator_range<value_op_iterator> operand_values() {
247 return make_range(value_op_begin(), value_op_end());
250 struct const_value_op_iterator
251 : iterator_adaptor_base<const_value_op_iterator, const_op_iterator,
252 std::random_access_iterator_tag, const Value *,
253 ptrdiff_t, const Value *, const Value *> {
254 explicit const_value_op_iterator(const Use *U = nullptr) :
255 iterator_adaptor_base(U) {}
257 const Value *operator*() const { return *I; }
258 const Value *operator->() const { return operator*(); }
261 const_value_op_iterator value_op_begin() const {
262 return const_value_op_iterator(op_begin());
264 const_value_op_iterator value_op_end() const {
265 return const_value_op_iterator(op_end());
267 iterator_range<const_value_op_iterator> operand_values() const {
268 return make_range(value_op_begin(), value_op_end());
271 /// \brief Drop all references to operands.
273 /// This function is in charge of "letting go" of all objects that this User
274 /// refers to. This allows one to 'delete' a whole class at a time, even
275 /// though there may be circular references... First all references are
276 /// dropped, and all use counts go to zero. Then everything is deleted for
277 /// real. Note that no operations are valid on an object that has "dropped
278 /// all references", except operator delete.
279 void dropAllReferences() {
280 for (Use &U : operands())
284 /// \brief Replace uses of one Value with another.
286 /// Replaces all references to the "From" definition with references to the
288 void replaceUsesOfWith(Value *From, Value *To);
290 // Methods for support type inquiry through isa, cast, and dyn_cast:
291 static bool classof(const Value *V) {
292 return isa<Instruction>(V) || isa<Constant>(V);
296 // Either Use objects, or a Use pointer can be prepended to User.
297 static_assert(alignof(Use) >= alignof(User),
298 "Alignment is insufficient after objects prepended to User");
299 static_assert(alignof(Use *) >= alignof(User),
300 "Alignment is insufficient after objects prepended to User");
302 template<> struct simplify_type<User::op_iterator> {
303 using SimpleType = Value*;
305 static SimpleType getSimplifiedValue(User::op_iterator &Val) {
309 template<> struct simplify_type<User::const_op_iterator> {
310 using SimpleType = /*const*/ Value*;
312 static SimpleType getSimplifiedValue(User::const_op_iterator &Val) {
317 } // end namespace llvm
319 #endif // LLVM_IR_USER_H