Line data Source code
1 : //===-- llvm/Constant.h - Constant 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 file contains the declaration of the Constant class.
11 : //
12 : //===----------------------------------------------------------------------===//
13 :
14 : #ifndef LLVM_IR_CONSTANT_H
15 : #define LLVM_IR_CONSTANT_H
16 :
17 : #include "llvm/IR/User.h"
18 : #include "llvm/IR/Value.h"
19 : #include "llvm/Support/Casting.h"
20 :
21 : namespace llvm {
22 :
23 : class APInt;
24 :
25 : /// This is an important base class in LLVM. It provides the common facilities
26 : /// of all constant values in an LLVM program. A constant is a value that is
27 : /// immutable at runtime. Functions are constants because their address is
28 : /// immutable. Same with global variables.
29 : ///
30 : /// All constants share the capabilities provided in this class. All constants
31 : /// can have a null value. They can have an operand list. Constants can be
32 : /// simple (integer and floating point values), complex (arrays and structures),
33 : /// or expression based (computations yielding a constant value composed of
34 : /// only certain operators and other constant values).
35 : ///
36 : /// Note that Constants are immutable (once created they never change)
37 : /// and are fully shared by structural equivalence. This means that two
38 : /// structurally equivalent constants will always have the same address.
39 : /// Constants are created on demand as needed and never deleted: thus clients
40 : /// don't have to worry about the lifetime of the objects.
41 : /// LLVM Constant Representation
42 319141 : class Constant : public User {
43 : protected:
44 : Constant(Type *ty, ValueTy vty, Use *Ops, unsigned NumOps)
45 : : User(ty, vty, Ops, NumOps) {}
46 :
47 : public:
48 : void operator=(const Constant &) = delete;
49 : Constant(const Constant &) = delete;
50 :
51 : /// Return true if this is the value that would be returned by getNullValue.
52 : bool isNullValue() const;
53 :
54 : /// Returns true if the value is one.
55 : bool isOneValue() const;
56 :
57 : /// Return true if this is the value that would be returned by
58 : /// getAllOnesValue.
59 : bool isAllOnesValue() const;
60 :
61 : /// Return true if the value is what would be returned by
62 : /// getZeroValueForNegation.
63 : bool isNegativeZeroValue() const;
64 :
65 : /// Return true if the value is negative zero or null value.
66 : bool isZeroValue() const;
67 :
68 : /// Return true if the value is not the smallest signed value.
69 : bool isNotMinSignedValue() const;
70 :
71 : /// Return true if the value is the smallest signed value.
72 : bool isMinSignedValue() const;
73 :
74 : /// Return true if this is a finite and non-zero floating-point scalar
75 : /// constant or a vector constant with all finite and non-zero elements.
76 : bool isFiniteNonZeroFP() const;
77 :
78 : /// Return true if this is a normal (as opposed to denormal) floating-point
79 : /// scalar constant or a vector constant with all normal elements.
80 : bool isNormalFP() const;
81 :
82 : /// Return true if this scalar has an exact multiplicative inverse or this
83 : /// vector has an exact multiplicative inverse for each element in the vector.
84 : bool hasExactInverseFP() const;
85 :
86 : /// Return true if this is a floating-point NaN constant or a vector
87 : /// floating-point constant with all NaN elements.
88 : bool isNaN() const;
89 :
90 : /// Return true if this is a vector constant that includes any undefined
91 : /// elements.
92 : bool containsUndefElement() const;
93 :
94 : /// Return true if evaluation of this constant could trap. This is true for
95 : /// things like constant expressions that could divide by zero.
96 : bool canTrap() const;
97 :
98 : /// Return true if the value can vary between threads.
99 : bool isThreadDependent() const;
100 :
101 : /// Return true if the value is dependent on a dllimport variable.
102 : bool isDLLImportDependent() const;
103 :
104 : /// Return true if the constant has users other than constant expressions and
105 : /// other dangling things.
106 : bool isConstantUsed() const;
107 :
108 : /// This method classifies the entry according to whether or not it may
109 : /// generate a relocation entry. This must be conservative, so if it might
110 : /// codegen to a relocatable entry, it should say so.
111 : ///
112 : /// FIXME: This really should not be in IR.
113 : bool needsRelocation() const;
114 :
115 : /// For aggregates (struct/array/vector) return the constant that corresponds
116 : /// to the specified element if possible, or null if not. This can return null
117 : /// if the element index is a ConstantExpr, or if 'this' is a constant expr.
118 : Constant *getAggregateElement(unsigned Elt) const;
119 : Constant *getAggregateElement(Constant *Elt) const;
120 :
121 : /// If this is a splat vector constant, meaning that all of the elements have
122 : /// the same value, return that value. Otherwise return 0.
123 : Constant *getSplatValue() const;
124 :
125 : /// If C is a constant integer then return its value, otherwise C must be a
126 : /// vector of constant integers, all equal, and the common value is returned.
127 : const APInt &getUniqueInteger() const;
128 :
129 : /// Called if some element of this constant is no longer valid.
130 : /// At this point only other constants may be on the use_list for this
131 : /// constant. Any constants on our Use list must also be destroy'd. The
132 : /// implementation must be sure to remove the constant from the list of
133 : /// available cached constants. Implementations should implement
134 : /// destroyConstantImpl to remove constants from any pools/maps they are
135 : /// contained it.
136 : void destroyConstant();
137 :
138 : //// Methods for support type inquiry through isa, cast, and dyn_cast:
139 : static bool classof(const Value *V) {
140 : static_assert(ConstantFirstVal == 0, "V->getValueID() >= ConstantFirstVal always succeeds");
141 13848217 : return V->getValueID() <= ConstantLastVal;
142 : }
143 :
144 : /// This method is a special form of User::replaceUsesOfWith
145 : /// (which does not work on constants) that does work
146 : /// on constants. Basically this method goes through the trouble of building
147 : /// a new constant that is equivalent to the current one, with all uses of
148 : /// From replaced with uses of To. After this construction is completed, all
149 : /// of the users of 'this' are replaced to use the new constant, and then
150 : /// 'this' is deleted. In general, you should not call this method, instead,
151 : /// use Value::replaceAllUsesWith, which automatically dispatches to this
152 : /// method as needed.
153 : ///
154 : void handleOperandChange(Value *, Value *);
155 :
156 : static Constant *getNullValue(Type* Ty);
157 :
158 : /// @returns the value for an integer or vector of integer constant of the
159 : /// given type that has all its bits set to true.
160 : /// Get the all ones value
161 : static Constant *getAllOnesValue(Type* Ty);
162 :
163 : /// Return the value for an integer or pointer constant, or a vector thereof,
164 : /// with the given scalar value.
165 : static Constant *getIntegerValue(Type *Ty, const APInt &V);
166 :
167 : /// If there are any dead constant users dangling off of this constant, remove
168 : /// them. This method is useful for clients that want to check to see if a
169 : /// global is unused, but don't want to deal with potentially dead constants
170 : /// hanging off of the globals.
171 : void removeDeadConstantUsers() const;
172 :
173 : const Constant *stripPointerCasts() const {
174 17918486 : return cast<Constant>(Value::stripPointerCasts());
175 : }
176 :
177 : Constant *stripPointerCasts() {
178 : return const_cast<Constant*>(
179 : static_cast<const Constant *>(this)->stripPointerCasts());
180 : }
181 : };
182 :
183 : } // end namespace llvm
184 :
185 : #endif // LLVM_IR_CONSTANT_H
|
