LLVM 17.0.0git
Constant.h
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1//===-- llvm/Constant.h - Constant class definition -------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file contains the declaration of the Constant class.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_IR_CONSTANT_H
14#define LLVM_IR_CONSTANT_H
15
16#include "llvm/IR/User.h"
17#include "llvm/IR/Value.h"
19
20namespace llvm {
21
22class APInt;
23
24/// This is an important base class in LLVM. It provides the common facilities
25/// of all constant values in an LLVM program. A constant is a value that is
26/// immutable at runtime. Functions are constants because their address is
27/// immutable. Same with global variables.
28///
29/// All constants share the capabilities provided in this class. All constants
30/// can have a null value. They can have an operand list. Constants can be
31/// simple (integer and floating point values), complex (arrays and structures),
32/// or expression based (computations yielding a constant value composed of
33/// only certain operators and other constant values).
34///
35/// Note that Constants are immutable (once created they never change)
36/// and are fully shared by structural equivalence. This means that two
37/// structurally equivalent constants will always have the same address.
38/// Constants are created on demand as needed and never deleted: thus clients
39/// don't have to worry about the lifetime of the objects.
40/// LLVM Constant Representation
41class Constant : public User {
42protected:
43 Constant(Type *ty, ValueTy vty, Use *Ops, unsigned NumOps)
44 : User(ty, vty, Ops, NumOps) {}
45
46 ~Constant() = default;
47
48public:
49 void operator=(const Constant &) = delete;
50 Constant(const Constant &) = delete;
51
52 /// Return true if this is the value that would be returned by getNullValue.
53 bool isNullValue() const;
54
55 /// Returns true if the value is one.
56 bool isOneValue() const;
57
58 /// Return true if the value is not the one value, or,
59 /// for vectors, does not contain one value elements.
60 bool isNotOneValue() const;
61
62 /// Return true if this is the value that would be returned by
63 /// getAllOnesValue.
64 bool isAllOnesValue() const;
65
66 /// Return true if the value is what would be returned by
67 /// getZeroValueForNegation.
68 bool isNegativeZeroValue() const;
69
70 /// Return true if the value is negative zero or null value.
71 bool isZeroValue() const;
72
73 /// Return true if the value is not the smallest signed value, or,
74 /// for vectors, does not contain smallest signed value elements.
75 bool isNotMinSignedValue() const;
76
77 /// Return true if the value is the smallest signed value.
78 bool isMinSignedValue() const;
79
80 /// Return true if this is a finite and non-zero floating-point scalar
81 /// constant or a fixed width vector constant with all finite and non-zero
82 /// elements.
83 bool isFiniteNonZeroFP() const;
84
85 /// Return true if this is a normal (as opposed to denormal, infinity, nan,
86 /// or zero) floating-point scalar constant or a vector constant with all
87 /// normal elements. See APFloat::isNormal.
88 bool isNormalFP() const;
89
90 /// Return true if this scalar has an exact multiplicative inverse or this
91 /// vector has an exact multiplicative inverse for each element in the vector.
92 bool hasExactInverseFP() const;
93
94 /// Return true if this is a floating-point NaN constant or a vector
95 /// floating-point constant with all NaN elements.
96 bool isNaN() const;
97
98 /// Return true if this constant and a constant 'Y' are element-wise equal.
99 /// This is identical to just comparing the pointers, with the exception that
100 /// for vectors, if only one of the constants has an `undef` element in some
101 /// lane, the constants still match.
102 bool isElementWiseEqual(Value *Y) const;
103
104 /// Return true if this is a vector constant that includes any undef or
105 /// poison elements. Since it is impossible to inspect a scalable vector
106 /// element- wise at compile time, this function returns true only if the
107 /// entire vector is undef or poison.
108 bool containsUndefOrPoisonElement() const;
109
110 /// Return true if this is a vector constant that includes any poison
111 /// elements.
112 bool containsPoisonElement() const;
113
114 /// Return true if this is a vector constant that includes any strictly undef
115 /// (not poison) elements.
116 bool containsUndefElement() const;
117
118 /// Return true if this is a fixed width vector constant that includes
119 /// any constant expressions.
120 bool containsConstantExpression() const;
121
122 /// Return true if the value can vary between threads.
123 bool isThreadDependent() const;
124
125 /// Return true if the value is dependent on a dllimport variable.
126 bool isDLLImportDependent() const;
127
128 /// Return true if the constant has users other than constant expressions and
129 /// other dangling things.
130 bool isConstantUsed() const;
131
132 /// This method classifies the entry according to whether or not it may
133 /// generate a relocation entry (either static or dynamic). This must be
134 /// conservative, so if it might codegen to a relocatable entry, it should say
135 /// so.
136 ///
137 /// FIXME: This really should not be in IR.
138 bool needsRelocation() const;
139 bool needsDynamicRelocation() const;
140
141 /// For aggregates (struct/array/vector) return the constant that corresponds
142 /// to the specified element if possible, or null if not. This can return null
143 /// if the element index is a ConstantExpr, if 'this' is a constant expr or
144 /// if the constant does not fit into an uint64_t.
145 Constant *getAggregateElement(unsigned Elt) const;
147
148 /// If all elements of the vector constant have the same value, return that
149 /// value. Otherwise, return nullptr. Ignore undefined elements by setting
150 /// AllowUndefs to true.
151 Constant *getSplatValue(bool AllowUndefs = false) const;
152
153 /// If C is a constant integer then return its value, otherwise C must be a
154 /// vector of constant integers, all equal, and the common value is returned.
155 const APInt &getUniqueInteger() const;
156
157 /// Called if some element of this constant is no longer valid.
158 /// At this point only other constants may be on the use_list for this
159 /// constant. Any constants on our Use list must also be destroy'd. The
160 /// implementation must be sure to remove the constant from the list of
161 /// available cached constants. Implementations should implement
162 /// destroyConstantImpl to remove constants from any pools/maps they are
163 /// contained it.
164 void destroyConstant();
165
166 //// Methods for support type inquiry through isa, cast, and dyn_cast:
167 static bool classof(const Value *V) {
168 static_assert(ConstantFirstVal == 0, "V->getValueID() >= ConstantFirstVal always succeeds");
169 return V->getValueID() <= ConstantLastVal;
170 }
171
172 /// This method is a special form of User::replaceUsesOfWith
173 /// (which does not work on constants) that does work
174 /// on constants. Basically this method goes through the trouble of building
175 /// a new constant that is equivalent to the current one, with all uses of
176 /// From replaced with uses of To. After this construction is completed, all
177 /// of the users of 'this' are replaced to use the new constant, and then
178 /// 'this' is deleted. In general, you should not call this method, instead,
179 /// use Value::replaceAllUsesWith, which automatically dispatches to this
180 /// method as needed.
181 ///
183
184 static Constant *getNullValue(Type* Ty);
185
186 /// @returns the value for an integer or vector of integer constant of the
187 /// given type that has all its bits set to true.
188 /// Get the all ones value
189 static Constant *getAllOnesValue(Type* Ty);
190
191 /// Return the value for an integer or pointer constant, or a vector thereof,
192 /// with the given scalar value.
193 static Constant *getIntegerValue(Type *Ty, const APInt &V);
194
195 /// If there are any dead constant users dangling off of this constant, remove
196 /// them. This method is useful for clients that want to check to see if a
197 /// global is unused, but don't want to deal with potentially dead constants
198 /// hanging off of the globals.
199 void removeDeadConstantUsers() const;
200
201 /// Return true if the constant has exactly one live use.
202 ///
203 /// This returns the same result as calling Value::hasOneUse after
204 /// Constant::removeDeadConstantUsers, but doesn't remove dead constants.
205 bool hasOneLiveUse() const;
206
207 /// Return true if the constant has no live uses.
208 ///
209 /// This returns the same result as calling Value::use_empty after
210 /// Constant::removeDeadConstantUsers, but doesn't remove dead constants.
211 bool hasZeroLiveUses() const;
212
214 return cast<Constant>(Value::stripPointerCasts());
215 }
216
218 return const_cast<Constant*>(
219 static_cast<const Constant *>(this)->stripPointerCasts());
220 }
221
222 /// Try to replace undefined constant C or undefined elements in C with
223 /// Replacement. If no changes are made, the constant C is returned.
224 static Constant *replaceUndefsWith(Constant *C, Constant *Replacement);
225
226 /// Merges undefs of a Constant with another Constant, along with the
227 /// undefs already present. Other doesn't have to be the same type as C, but
228 /// both must either be scalars or vectors with the same element count. If no
229 /// changes are made, the constant C is returned.
231
232 /// Return true if a constant is ConstantData or a ConstantAggregate or
233 /// ConstantExpr that contain only ConstantData.
234 bool isManifestConstant() const;
235
236private:
237 enum PossibleRelocationsTy {
238 /// This constant requires no relocations. That is, it holds simple
239 /// constants (like integrals).
240 NoRelocation = 0,
241
242 /// This constant holds static relocations that can be resolved by the
243 /// static linker.
244 LocalRelocation = 1,
245
246 /// This constant holds dynamic relocations that the dynamic linker will
247 /// need to resolve.
248 GlobalRelocation = 2,
249 };
250
251 /// Determine what potential relocations may be needed by this constant.
252 PossibleRelocationsTy getRelocationInfo() const;
253
254 bool hasNLiveUses(unsigned N) const;
255};
256
257} // end namespace llvm
258
259#endif // LLVM_IR_CONSTANT_H
static GCMetadataPrinterRegistry::Add< OcamlGCMetadataPrinter > Y("ocaml", "ocaml 3.10-compatible collector")
Class for arbitrary precision integers.
Definition: APInt.h:75
This is an important base class in LLVM.
Definition: Constant.h:41
static Constant * getIntegerValue(Type *Ty, const APInt &V)
Return the value for an integer or pointer constant, or a vector thereof, with the given scalar value...
Definition: Constants.cpp:386
~Constant()=default
bool hasExactInverseFP() const
Return true if this scalar has an exact multiplicative inverse or this vector has an exact multiplica...
Definition: Constants.cpp:242
static Constant * replaceUndefsWith(Constant *C, Constant *Replacement)
Try to replace undefined constant C or undefined elements in C with Replacement.
Definition: Constants.cpp:755
void operator=(const Constant &)=delete
bool containsUndefElement() const
Return true if this is a vector constant that includes any strictly undef (not poison) elements.
Definition: Constants.cpp:340
Constant * getSplatValue(bool AllowUndefs=false) const
If all elements of the vector constant have the same value, return that value.
Definition: Constants.cpp:1631
static Constant * mergeUndefsWith(Constant *C, Constant *Other)
Merges undefs of a Constant with another Constant, along with the undefs already present.
Definition: Constants.cpp:779
Constant(const Constant &)=delete
static Constant * getAllOnesValue(Type *Ty)
Definition: Constants.cpp:403
Constant(Type *ty, ValueTy vty, Use *Ops, unsigned NumOps)
Definition: Constant.h:43
bool hasZeroLiveUses() const
Return true if the constant has no live uses.
Definition: Constants.cpp:739
bool isOneValue() const
Returns true if the value is one.
Definition: Constants.cpp:110
bool isManifestConstant() const
Return true if a constant is ConstantData or a ConstantAggregate or ConstantExpr that contain only Co...
Definition: Constants.cpp:814
bool isNegativeZeroValue() const
Return true if the value is what would be returned by getZeroValueForNegation.
Definition: Constants.cpp:42
bool isAllOnesValue() const
Return true if this is the value that would be returned by getAllOnesValue.
Definition: Constants.cpp:93
const Constant * stripPointerCasts() const
Definition: Constant.h:213
Constant * stripPointerCasts()
Definition: Constant.h:217
bool hasOneLiveUse() const
Return true if the constant has exactly one live use.
Definition: Constants.cpp:737
bool needsRelocation() const
This method classifies the entry according to whether or not it may generate a relocation entry (eith...
Definition: Constants.cpp:625
bool isDLLImportDependent() const
Return true if the value is dependent on a dllimport variable.
Definition: Constants.cpp:602
const APInt & getUniqueInteger() const
If C is a constant integer then return its value, otherwise C must be a vector of constant integers,...
Definition: Constants.cpp:1690
bool containsConstantExpression() const
Return true if this is a fixed width vector constant that includes any constant expressions.
Definition: Constants.cpp:346
bool isFiniteNonZeroFP() const
Return true if this is a finite and non-zero floating-point scalar constant or a fixed width vector c...
Definition: Constants.cpp:200
void removeDeadConstantUsers() const
If there are any dead constant users dangling off of this constant, remove them.
Definition: Constants.cpp:710
bool isNormalFP() const
Return true if this is a normal (as opposed to denormal, infinity, nan, or zero) floating-point scala...
Definition: Constants.cpp:221
bool needsDynamicRelocation() const
Definition: Constants.cpp:621
static Constant * getNullValue(Type *Ty)
Constructor to create a '0' constant of arbitrary type.
Definition: Constants.cpp:356
bool isNaN() const
Return true if this is a floating-point NaN constant or a vector floating-point constant with all NaN...
Definition: Constants.cpp:263
bool isMinSignedValue() const
Return true if the value is the smallest signed value.
Definition: Constants.cpp:155
bool isConstantUsed() const
Return true if the constant has users other than constant expressions and other dangling things.
Definition: Constants.cpp:609
Constant * getAggregateElement(unsigned Elt) const
For aggregates (struct/array/vector) return the constant that corresponds to the specified element if...
Definition: Constants.cpp:418
bool isThreadDependent() const
Return true if the value can vary between threads.
Definition: Constants.cpp:595
bool isZeroValue() const
Return true if the value is negative zero or null value.
Definition: Constants.cpp:62
void destroyConstant()
Called if some element of this constant is no longer valid.
Definition: Constants.cpp:458
bool isNotMinSignedValue() const
Return true if the value is not the smallest signed value, or, for vectors, does not contain smallest...
Definition: Constants.cpp:172
bool isNullValue() const
Return true if this is the value that would be returned by getNullValue.
Definition: Constants.cpp:76
static bool classof(const Value *V)
Definition: Constant.h:167
bool isNotOneValue() const
Return true if the value is not the one value, or, for vectors, does not contain one value elements.
Definition: Constants.cpp:127
bool isElementWiseEqual(Value *Y) const
Return true if this constant and a constant 'Y' are element-wise equal.
Definition: Constants.cpp:284
bool containsUndefOrPoisonElement() const
Return true if this is a vector constant that includes any undef or poison elements.
Definition: Constants.cpp:330
bool containsPoisonElement() const
Return true if this is a vector constant that includes any poison elements.
Definition: Constants.cpp:335
void handleOperandChange(Value *, Value *)
This method is a special form of User::replaceUsesOfWith (which does not work on constants) that does...
Definition: Constants.cpp:3267
The instances of the Type class are immutable: once they are created, they are never changed.
Definition: Type.h:45
A Use represents the edge between a Value definition and its users.
Definition: Use.h:43
LLVM Value Representation.
Definition: Value.h:74
unsigned getValueID() const
Return an ID for the concrete type of this object.
Definition: Value.h:532
const Value * stripPointerCasts() const
Strip off pointer casts, all-zero GEPs and address space casts.
Definition: Value.cpp:685
ValueTy
Concrete subclass of this.
Definition: Value.h:513
@ C
The default llvm calling convention, compatible with C.
Definition: CallingConv.h:34
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
#define N