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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/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"
29 : #include <cassert>
30 : #include <cstddef>
31 : #include <cstdint>
32 : #include <iterator>
33 :
34 : namespace llvm {
35 :
36 : template <typename T> class ArrayRef;
37 : template <typename T> class MutableArrayRef;
38 :
39 : /// Compile-time customization of User operands.
40 : ///
41 : /// Customizes operand-related allocators and accessors.
42 : template <class>
43 : struct OperandTraits;
44 :
45 : class User : public Value {
46 : template <unsigned>
47 : friend struct HungoffOperandTraits;
48 :
49 : LLVM_ATTRIBUTE_ALWAYS_INLINE inline static void *
50 : allocateFixedOperandUser(size_t, unsigned, unsigned);
51 :
52 : protected:
53 : /// Allocate a User with an operand pointer co-allocated.
54 : ///
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);
58 :
59 : /// Allocate a User with the operands co-allocated.
60 : ///
61 : /// This is used for subclasses which have a fixed number of operands.
62 : void *operator new(size_t Size, unsigned Us);
63 :
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.
67 : ///
68 : /// DescBytes needs to be divisible by sizeof(void *). The allocated
69 : /// descriptor, if any, is aligned to sizeof(void *) bytes.
70 : ///
71 : /// This is used for subclasses which have a fixed number of operands.
72 : void *operator new(size_t Size, unsigned Us, unsigned DescBytes);
73 :
74 : User(Type *ty, unsigned vty, Use *, unsigned NumOps)
75 73308394 : : Value(ty, vty) {
76 : assert(NumOps < (1u << NumUserOperandsBits) && "Too many operands");
77 73308090 : NumUserOperands = NumOps;
78 : // If we have hung off uses, then the operand list should initially be
79 : // null.
80 : assert((!HasHungOffUses || !getOperandList()) &&
81 : "Error in initializing hung off uses for User");
82 : }
83 :
84 : /// 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);
89 :
90 : /// 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);
93 :
94 : protected:
95 34831038 : ~User() = default; // Use deleteValue() to delete a generic Instruction.
96 :
97 : public:
98 : User(const User &) = delete;
99 :
100 : /// Free memory allocated for User and Use objects.
101 : void operator delete(void *Usr);
102 : /// Placement delete - required by std, called if the ctor throws.
103 : void operator delete(void *Usr, unsigned) {
104 : // Note: If a subclass manipulates the information which is required to calculate the
105 : // Usr memory pointer, e.g. NumUserOperands, the operator delete of that subclass has
106 : // to restore the changed information to the original value, since the dtor of that class
107 : // is not called if the ctor fails.
108 : User::operator delete(Usr);
109 :
110 : #ifndef LLVM_ENABLE_EXCEPTIONS
111 : llvm_unreachable("Constructor throws?");
112 : #endif
113 : }
114 : /// Placement delete - required by std, called if the ctor throws.
115 : void operator delete(void *Usr, unsigned, bool) {
116 : // Note: If a subclass manipulates the information which is required to calculate the
117 : // Usr memory pointer, e.g. NumUserOperands, the operator delete of that subclass has
118 : // to restore the changed information to the original value, since the dtor of that class
119 : // is not called if the ctor fails.
120 : User::operator delete(Usr);
121 :
122 : #ifndef LLVM_ENABLE_EXCEPTIONS
123 : llvm_unreachable("Constructor throws?");
124 : #endif
125 : }
126 :
127 : protected:
128 : template <int Idx, typename U> static Use &OpFrom(const U *that) {
129 : return Idx < 0
130 : ? OperandTraits<U>::op_end(const_cast<U*>(that))[Idx]
131 21763915 : : OperandTraits<U>::op_begin(const_cast<U*>(that))[Idx];
132 : }
133 :
134 : template <int Idx> Use &Op() {
135 : return OpFrom<Idx>(this);
136 : }
137 : template <int Idx> const Use &Op() const {
138 : return OpFrom<Idx>(this);
139 : }
140 :
141 : private:
142 : const Use *getHungOffOperands() const {
143 71132970 : return *(reinterpret_cast<const Use *const *>(this) - 1);
144 : }
145 :
146 : Use *&getHungOffOperands() { return *(reinterpret_cast<Use **>(this) - 1); }
147 :
148 : const Use *getIntrusiveOperands() const {
149 796433723 : return reinterpret_cast<const Use *>(this) - NumUserOperands;
150 : }
151 :
152 : Use *getIntrusiveOperands() {
153 114155 : return reinterpret_cast<Use *>(this) - NumUserOperands;
154 : }
155 :
156 : void setOperandList(Use *NewList) {
157 : assert(HasHungOffUses &&
158 : "Setting operand list only required for hung off uses");
159 1499249 : getHungOffOperands() = NewList;
160 : }
161 :
162 : public:
163 : const Use *getOperandList() const {
164 820336584 : return HasHungOffUses ? getHungOffOperands() : getIntrusiveOperands();
165 : }
166 : Use *getOperandList() {
167 : return const_cast<Use *>(static_cast<const User *>(this)->getOperandList());
168 : }
169 :
170 : Value *getOperand(unsigned i) const {
171 : assert(i < NumUserOperands && "getOperand() out of range!");
172 381353292 : return getOperandList()[i];
173 : }
174 :
175 614268 : void setOperand(unsigned i, Value *Val) {
176 : assert(i < NumUserOperands && "setOperand() out of range!");
177 : assert((!isa<Constant>((const Value*)this) ||
178 : isa<GlobalValue>((const Value*)this)) &&
179 : "Cannot mutate a constant with setOperand!");
180 614268 : getOperandList()[i] = Val;
181 614268 : }
182 :
183 : const Use &getOperandUse(unsigned i) const {
184 : assert(i < NumUserOperands && "getOperandUse() out of range!");
185 1 : return getOperandList()[i];
186 : }
187 : Use &getOperandUse(unsigned i) {
188 : assert(i < NumUserOperands && "getOperandUse() out of range!");
189 2715601 : return getOperandList()[i];
190 : }
191 :
192 516868852 : unsigned getNumOperands() const { return NumUserOperands; }
193 :
194 : /// Returns the descriptor co-allocated with this User instance.
195 : ArrayRef<const uint8_t> getDescriptor() const;
196 :
197 : /// Returns the descriptor co-allocated with this User instance.
198 : MutableArrayRef<uint8_t> getDescriptor();
199 :
200 : /// Set the number of operands on a GlobalVariable.
201 : ///
202 : /// GlobalVariable always allocates space for a single operands, but
203 : /// doesn't always use it.
204 : ///
205 : /// FIXME: As that the number of operands is used to find the start of
206 : /// the allocated memory in operator delete, we need to always think we have
207 : /// 1 operand before delete.
208 : void setGlobalVariableNumOperands(unsigned NumOps) {
209 : assert(NumOps <= 1 && "GlobalVariable can only have 0 or 1 operands");
210 214931 : NumUserOperands = NumOps;
211 : }
212 :
213 : /// Subclasses with hung off uses need to manage the operand count
214 : /// themselves. In these instances, the operand count isn't used to find the
215 : /// OperandList, so there's no issue in having the operand count change.
216 : void setNumHungOffUseOperands(unsigned NumOps) {
217 : assert(HasHungOffUses && "Must have hung off uses to use this method");
218 : assert(NumOps < (1u << NumUserOperandsBits) && "Too many operands");
219 1968288 : NumUserOperands = NumOps;
220 : }
221 :
222 : // ---------------------------------------------------------------------------
223 : // Operand Iterator interface...
224 : //
225 : using op_iterator = Use*;
226 : using const_op_iterator = const Use*;
227 : using op_range = iterator_range<op_iterator>;
228 : using const_op_range = iterator_range<const_op_iterator>;
229 :
230 : op_iterator op_begin() { return getOperandList(); }
231 : const_op_iterator op_begin() const { return getOperandList(); }
232 : op_iterator op_end() {
233 200850652 : return getOperandList() + NumUserOperands;
234 : }
235 : const_op_iterator op_end() const {
236 166706011 : return getOperandList() + NumUserOperands;
237 : }
238 : op_range operands() {
239 : return op_range(op_begin(), op_end());
240 : }
241 : const_op_range operands() const {
242 : return const_op_range(op_begin(), op_end());
243 : }
244 :
245 : /// Iterator for directly iterating over the operand Values.
246 : struct value_op_iterator
247 : : iterator_adaptor_base<value_op_iterator, op_iterator,
248 : std::random_access_iterator_tag, Value *,
249 : ptrdiff_t, Value *, Value *> {
250 : explicit value_op_iterator(Use *U = nullptr) : iterator_adaptor_base(U) {}
251 :
252 6600400 : Value *operator*() const { return *I; }
253 : Value *operator->() const { return operator*(); }
254 : };
255 :
256 : value_op_iterator value_op_begin() {
257 : return value_op_iterator(op_begin());
258 : }
259 : value_op_iterator value_op_end() {
260 : return value_op_iterator(op_end());
261 : }
262 : iterator_range<value_op_iterator> operand_values() {
263 : return make_range(value_op_begin(), value_op_end());
264 : }
265 :
266 : struct const_value_op_iterator
267 : : iterator_adaptor_base<const_value_op_iterator, const_op_iterator,
268 : std::random_access_iterator_tag, const Value *,
269 : ptrdiff_t, const Value *, const Value *> {
270 : explicit const_value_op_iterator(const Use *U = nullptr) :
271 : iterator_adaptor_base(U) {}
272 :
273 9395774 : const Value *operator*() const { return *I; }
274 : const Value *operator->() const { return operator*(); }
275 : };
276 :
277 : const_value_op_iterator value_op_begin() const {
278 : return const_value_op_iterator(op_begin());
279 : }
280 : const_value_op_iterator value_op_end() const {
281 : return const_value_op_iterator(op_end());
282 : }
283 : iterator_range<const_value_op_iterator> operand_values() const {
284 : return make_range(value_op_begin(), value_op_end());
285 : }
286 :
287 : /// Drop all references to operands.
288 : ///
289 : /// This function is in charge of "letting go" of all objects that this User
290 : /// refers to. This allows one to 'delete' a whole class at a time, even
291 : /// though there may be circular references... First all references are
292 : /// dropped, and all use counts go to zero. Then everything is deleted for
293 : /// real. Note that no operations are valid on an object that has "dropped
294 : /// all references", except operator delete.
295 46717609 : void dropAllReferences() {
296 120743801 : for (Use &U : operands())
297 : U.set(nullptr);
298 46717609 : }
299 :
300 : /// Replace uses of one Value with another.
301 : ///
302 : /// Replaces all references to the "From" definition with references to the
303 : /// "To" definition.
304 : void replaceUsesOfWith(Value *From, Value *To);
305 :
306 : // Methods for support type inquiry through isa, cast, and dyn_cast:
307 : static bool classof(const Value *V) {
308 663341 : return isa<Instruction>(V) || isa<Constant>(V);
309 : }
310 : };
311 :
312 : // Either Use objects, or a Use pointer can be prepended to User.
313 : static_assert(alignof(Use) >= alignof(User),
314 : "Alignment is insufficient after objects prepended to User");
315 : static_assert(alignof(Use *) >= alignof(User),
316 : "Alignment is insufficient after objects prepended to User");
317 :
318 : template<> struct simplify_type<User::op_iterator> {
319 : using SimpleType = Value*;
320 :
321 0 : static SimpleType getSimplifiedValue(User::op_iterator &Val) {
322 728157 : return Val->get();
323 : }
324 : };
325 : template<> struct simplify_type<User::const_op_iterator> {
326 : using SimpleType = /*const*/ Value*;
327 :
328 0 : static SimpleType getSimplifiedValue(User::const_op_iterator &Val) {
329 241773301 : return Val->get();
330 : }
331 : };
332 :
333 : } // end namespace llvm
334 :
335 : #endif // LLVM_IR_USER_H
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