LLVM  7.0.0svn
User.h
Go to the documentation of this file.
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"
24 #include "llvm/IR/Use.h"
25 #include "llvm/IR/Value.h"
26 #include "llvm/Support/Casting.h"
27 #include "llvm/Support/Compiler.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 /// \brief Compile-time customization of User operands.
40 ///
41 /// Customizes operand-related allocators and accessors.
42 template <class>
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  : Value(ty, vty) {
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
79  // null.
81  "Error in initializing hung off uses for User");
82  }
83 
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);
89 
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);
93 
94 protected:
95  ~User() = default; // Use deleteValue() to delete a generic Instruction.
96 
97 public:
98  User(const User &) = delete;
99 
100  /// \brief Free memory allocated for User and Use objects.
101  void operator delete(void *Usr);
102  /// \brief 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  /// \brief 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  : 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  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  return reinterpret_cast<const Use *>(this) - NumUserOperands;
150  }
151 
152  Use *getIntrusiveOperands() {
153  return reinterpret_cast<Use *>(this) - NumUserOperands;
154  }
155 
156  void setOperandList(Use *NewList) {
158  "Setting operand list only required for hung off uses");
159  getHungOffOperands() = NewList;
160  }
161 
162 public:
163  const Use *getOperandList() const {
164  return HasHungOffUses ? getHungOffOperands() : getIntrusiveOperands();
165  }
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  return getOperandList()[i];
173  }
174 
175  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  getOperandList()[i] = Val;
181  }
182 
183  const Use &getOperandUse(unsigned i) const {
184  assert(i < NumUserOperands && "getOperandUse() out of range!");
185  return getOperandList()[i];
186  }
187  Use &getOperandUse(unsigned i) {
188  assert(i < NumUserOperands && "getOperandUse() out of range!");
189  return getOperandList()[i];
190  }
191 
192  unsigned getNumOperands() const { return NumUserOperands; }
193 
194  /// Returns the descriptor co-allocated with this User instance.
196 
197  /// Returns the descriptor co-allocated with this User instance.
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  NumUserOperands = NumOps;
211  }
212 
213  /// \brief 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  NumUserOperands = NumOps;
220  }
221 
222  // ---------------------------------------------------------------------------
223  // Operand Iterator interface...
224  //
225  using op_iterator = Use*;
226  using const_op_iterator = const Use*;
229 
233  return getOperandList() + NumUserOperands;
234  }
236  return getOperandList() + NumUserOperands;
237  }
239  return op_range(op_begin(), op_end());
240  }
242  return const_op_range(op_begin(), op_end());
243  }
244 
245  /// \brief Iterator for directly iterating over the operand Values.
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  Value *operator*() const { return *I; }
253  Value *operator->() const { return operator*(); }
254  };
255 
257  return value_op_iterator(op_begin());
258  }
260  return value_op_iterator(op_end());
261  }
264  }
265 
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) :
272 
273  const Value *operator*() const { return *I; }
274  const Value *operator->() const { return operator*(); }
275  };
276 
279  }
282  }
285  }
286 
287  /// \brief 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.
296  for (Use &U : operands())
297  U.set(nullptr);
298  }
299 
300  /// \brief 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  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 
322  return Val->get();
323  }
324 };
325 template<> struct simplify_type<User::const_op_iterator> {
326  using SimpleType = /*const*/ Value*;
327 
329  return Val->get();
330  }
331 };
332 
333 } // end namespace llvm
334 
335 #endif // LLVM_IR_USER_H
static Use & OpFrom(const U *that)
Definition: User.h:128
const_value_op_iterator value_op_begin() const
Definition: User.h:277
void dropAllReferences()
Drop all references to operands.
Definition: User.h:295
const_op_iterator op_begin() const
Definition: User.h:231
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
This provides a very simple, boring adaptor for a begin and end iterator into a range type...
value_op_iterator value_op_begin()
Definition: User.h:256
iterator_range< op_iterator > op_range
Definition: User.h:227
Use & getOperandUse(unsigned i)
Definition: User.h:187
const Use & getOperandUse(unsigned i) const
Definition: User.h:183
value_op_iterator value_op_end()
Definition: User.h:259
This defines the Use class.
Use * op_iterator
Definition: User.h:225
op_iterator op_begin()
Definition: User.h:230
static bool classof(const Value *V)
Definition: User.h:307
const_value_op_iterator(const Use *U=nullptr)
Definition: User.h:270
A Use represents the edge between a Value definition and its users.
Definition: Use.h:56
void growHungoffUses(unsigned N, bool IsPhi=false)
Grow the number of hung off uses.
Definition: User.cpp:59
iterator_range< const_op_iterator > const_op_range
Definition: User.h:228
Use * getOperandList()
Definition: User.h:166
unsigned HasHungOffUses
Definition: Value.h:120
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory)...
Definition: APInt.h:33
Value * getOperand(unsigned i) const
Definition: User.h:170
void replaceUsesOfWith(Value *From, Value *To)
Replace uses of one Value with another.
Definition: User.cpp:21
const Use * getOperandList() const
Definition: User.h:163
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:46
CRTP base class for adapting an iterator to a different type.
Definition: iterator.h:208
op_iterator op_end()
Definition: User.h:232
ArrayRef< const uint8_t > getDescriptor() const
Returns the descriptor co-allocated with this User instance.
Definition: User.cpp:93
op_range operands()
Definition: User.h:238
const_op_iterator op_end() const
Definition: User.h:235
void setGlobalVariableNumOperands(unsigned NumOps)
Set the number of operands on a GlobalVariable.
Definition: User.h:208
static SimpleType getSimplifiedValue(User::const_op_iterator &Val)
Definition: User.h:328
Value * operator->() const
Definition: User.h:253
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
Iterator for directly iterating over the operand Values.
Definition: User.h:246
iterator_range< T > make_range(T x, T y)
Convenience function for iterating over sub-ranges.
unsigned getNumOperands() const
Definition: User.h:192
#define LLVM_ATTRIBUTE_ALWAYS_INLINE
LLVM_ATTRIBUTE_ALWAYS_INLINE - On compilers where we have a directive to do so, mark a method "always...
Definition: Compiler.h:198
User(Type *ty, unsigned vty, Use *, unsigned NumOps)
Definition: User.h:74
~User()=default
unsigned NumUserOperands
Definition: Value.h:115
void setOperand(unsigned i, Value *Val)
Definition: User.h:175
A range adaptor for a pair of iterators.
Value * operator*() const
Definition: User.h:252
const Use * const_op_iterator
Definition: User.h:226
const Use & Op() const
Definition: User.h:137
#define N
iterator_range< value_op_iterator > operand_values()
Definition: User.h:262
Compile-time customization of User operands.
Definition: User.h:43
iterator_range< const_value_op_iterator > operand_values() const
Definition: User.h:283
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
const Value * operator->() const
Definition: User.h:274
LLVM Value Representation.
Definition: Value.h:73
constexpr char Size[]
Key for Kernel::Arg::Metadata::mSize.
HungoffOperandTraits - determine the allocation regime of the Use array when it is not a prefix to th...
Definition: OperandTraits.h:96
void allocHungoffUses(unsigned N, bool IsPhi=false)
Allocate the array of Uses, followed by a pointer (with bottom bit set) to the User.
Definition: User.cpp:40
const_value_op_iterator value_op_end() const
Definition: User.h:280
Use & Op()
Definition: User.h:134
void setNumHungOffUseOperands(unsigned NumOps)
Subclasses with hung off uses need to manage the operand count themselves.
Definition: User.h:216
const Value * operator*() const
Definition: User.h:273
static SimpleType getSimplifiedValue(User::op_iterator &Val)
Definition: User.h:321
const_op_range operands() const
Definition: User.h:241
value_op_iterator(Use *U=nullptr)
Definition: User.h:250