]>
Commit | Line | Data |
---|---|---|
223e47cc LB |
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 | ||
970d7e83 LB |
14 | #ifndef LLVM_IR_CONSTANT_H |
15 | #define LLVM_IR_CONSTANT_H | |
223e47cc | 16 | |
970d7e83 | 17 | #include "llvm/IR/User.h" |
223e47cc LB |
18 | |
19 | namespace llvm { | |
20 | class APInt; | |
21 | ||
22 | template<typename T> class SmallVectorImpl; | |
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 | /// @brief LLVM Constant Representation | |
41 | class Constant : public User { | |
42 | void operator=(const Constant &) LLVM_DELETED_FUNCTION; | |
43 | Constant(const Constant &) LLVM_DELETED_FUNCTION; | |
1a4d82fc JJ |
44 | void anchor() override; |
45 | ||
223e47cc LB |
46 | protected: |
47 | Constant(Type *ty, ValueTy vty, Use *Ops, unsigned NumOps) | |
48 | : User(ty, vty, Ops, NumOps) {} | |
49 | ||
50 | void destroyConstantImpl(); | |
1a4d82fc JJ |
51 | void replaceUsesOfWithOnConstantImpl(Constant *Replacement); |
52 | ||
223e47cc LB |
53 | public: |
54 | /// isNullValue - Return true if this is the value that would be returned by | |
55 | /// getNullValue. | |
56 | bool isNullValue() const; | |
57 | ||
1a4d82fc JJ |
58 | /// \brief Returns true if the value is one. |
59 | bool isOneValue() const; | |
60 | ||
223e47cc LB |
61 | /// isAllOnesValue - Return true if this is the value that would be returned by |
62 | /// getAllOnesValue. | |
63 | bool isAllOnesValue() const; | |
64 | ||
65 | /// isNegativeZeroValue - Return true if the value is what would be returned | |
66 | /// by getZeroValueForNegation. | |
67 | bool isNegativeZeroValue() const; | |
68 | ||
970d7e83 LB |
69 | /// Return true if the value is negative zero or null value. |
70 | bool isZeroValue() const; | |
71 | ||
1a4d82fc JJ |
72 | /// \brief Return true if the value is not the smallest signed value. |
73 | bool isNotMinSignedValue() const; | |
74 | ||
75 | /// \brief Return true if the value is the smallest signed value. | |
76 | bool isMinSignedValue() const; | |
77 | ||
223e47cc LB |
78 | /// canTrap - Return true if evaluation of this constant could trap. This is |
79 | /// true for things like constant expressions that could divide by zero. | |
80 | bool canTrap() const; | |
81 | ||
970d7e83 LB |
82 | /// isThreadDependent - Return true if the value can vary between threads. |
83 | bool isThreadDependent() const; | |
84 | ||
1a4d82fc JJ |
85 | /// Return true if the value is dependent on a dllimport variable. |
86 | bool isDLLImportDependent() const; | |
87 | ||
223e47cc LB |
88 | /// isConstantUsed - Return true if the constant has users other than constant |
89 | /// exprs and other dangling things. | |
90 | bool isConstantUsed() const; | |
91 | ||
92 | enum PossibleRelocationsTy { | |
93 | NoRelocation = 0, | |
94 | LocalRelocation = 1, | |
95 | GlobalRelocations = 2 | |
96 | }; | |
97 | ||
98 | /// getRelocationInfo - This method classifies the entry according to | |
99 | /// whether or not it may generate a relocation entry. This must be | |
100 | /// conservative, so if it might codegen to a relocatable entry, it should say | |
101 | /// so. The return values are: | |
102 | /// | |
103 | /// NoRelocation: This constant pool entry is guaranteed to never have a | |
104 | /// relocation applied to it (because it holds a simple constant like | |
105 | /// '4'). | |
106 | /// LocalRelocation: This entry has relocations, but the entries are | |
107 | /// guaranteed to be resolvable by the static linker, so the dynamic | |
108 | /// linker will never see them. | |
109 | /// GlobalRelocations: This entry may have arbitrary relocations. | |
110 | /// | |
111 | /// FIXME: This really should not be in VMCore. | |
112 | PossibleRelocationsTy getRelocationInfo() const; | |
113 | ||
114 | /// getAggregateElement - For aggregates (struct/array/vector) return the | |
115 | /// constant that corresponds to the specified element if possible, or null if | |
116 | /// not. This can return null if the element index is a ConstantExpr, or if | |
117 | /// 'this' is a constant expr. | |
118 | Constant *getAggregateElement(unsigned Elt) const; | |
119 | Constant *getAggregateElement(Constant *Elt) const; | |
970d7e83 LB |
120 | |
121 | /// getSplatValue - If this is a splat vector constant, meaning that all of | |
122 | /// the elements have 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 | ||
223e47cc LB |
129 | /// destroyConstant - Called if some element of this constant is no longer |
130 | /// valid. 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 call | |
134 | /// destroyConstantImpl as the last thing they do, to destroy all users and | |
135 | /// delete this. | |
136 | virtual void destroyConstant() { llvm_unreachable("Not reached!"); } | |
137 | ||
138 | //// Methods for support type inquiry through isa, cast, and dyn_cast: | |
223e47cc LB |
139 | static inline bool classof(const Value *V) { |
140 | return V->getValueID() >= ConstantFirstVal && | |
141 | V->getValueID() <= ConstantLastVal; | |
142 | } | |
143 | ||
144 | /// replaceUsesOfWithOnConstant - This method is a special form of | |
145 | /// User::replaceUsesOfWith (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 | virtual void replaceUsesOfWithOnConstant(Value *, Value *, Use *) { | |
155 | // Provide a default implementation for constants (like integers) that | |
156 | // cannot use any other values. This cannot be called at runtime, but needs | |
157 | // to be here to avoid link errors. | |
158 | assert(getNumOperands() == 0 && "replaceUsesOfWithOnConstant must be " | |
159 | "implemented for all constants that have operands!"); | |
160 | llvm_unreachable("Constants that do not have operands cannot be using " | |
161 | "'From'!"); | |
162 | } | |
163 | ||
164 | static Constant *getNullValue(Type* Ty); | |
165 | ||
166 | /// @returns the value for an integer or vector of integer constant of the | |
167 | /// given type that has all its bits set to true. | |
168 | /// @brief Get the all ones value | |
169 | static Constant *getAllOnesValue(Type* Ty); | |
170 | ||
171 | /// getIntegerValue - Return the value for an integer or pointer constant, | |
172 | /// or a vector thereof, with the given scalar value. | |
173 | static Constant *getIntegerValue(Type* Ty, const APInt &V); | |
174 | ||
175 | /// removeDeadConstantUsers - If there are any dead constant users dangling | |
176 | /// off of this constant, remove them. This method is useful for clients | |
177 | /// that want to check to see if a global is unused, but don't want to deal | |
178 | /// with potentially dead constants hanging off of the globals. | |
179 | void removeDeadConstantUsers() const; | |
1a4d82fc JJ |
180 | |
181 | Constant *stripPointerCasts() { | |
182 | return cast<Constant>(Value::stripPointerCasts()); | |
183 | } | |
184 | ||
185 | const Constant *stripPointerCasts() const { | |
186 | return const_cast<Constant*>(this)->stripPointerCasts(); | |
187 | } | |
223e47cc LB |
188 | }; |
189 | ||
190 | } // End llvm namespace | |
191 | ||
192 | #endif |