1 //===-- llvm/Constant.h - Constant class definition -------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains the declaration of the Constant class.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CONSTANT_H
15 #define LLVM_CONSTANT_H
17 #include "llvm/User.h"
21 class Constant : public User {
23 inline Constant(const Type *Ty) : User(Ty, Value::ConstantVal) {}
26 void destroyConstantImpl();
28 // setName - Specialize setName to handle symbol table majik...
29 virtual void setName(const std::string &name, SymbolTable *ST = 0);
31 /// Static constructor to get a '0' constant of arbitrary type...
33 static Constant *getNullValue(const Type *Ty);
35 /// isNullValue - Return true if this is the value that would be returned by
37 virtual bool isNullValue() const = 0;
39 virtual void print(std::ostream &O) const;
41 /// isConstantExpr - Return true if this is a ConstantExpr
43 virtual bool isConstantExpr() const { return false; }
46 /// destroyConstant - Called if some element of this constant is no longer
47 /// valid. At this point only other constants may be on the use_list for this
48 /// constant. Any constants on our Use list must also be destroy'd. The
49 /// implementation must be sure to remove the constant from the list of
50 /// available cached constants. Implementations should call
51 /// destroyConstantImpl as the last thing they do, to destroy all users and
54 /// Note that this call is only valid on non-primitive constants: You cannot
55 /// destroy an integer constant for example. This API is used to delete
56 /// constants that have ConstantPointerRef's embeded in them when the module
57 /// is deleted, and it is used by GlobalDCE to remove ConstantPointerRefs that
58 /// are unneeded, allowing globals to be DCE'd.
60 virtual void destroyConstant() { assert(0 && "Not reached!"); }
63 //// Methods for support type inquiry through isa, cast, and dyn_cast:
64 static inline bool classof(const Constant *) { return true; }
65 static inline bool classof(const Value *V) {
66 return V->getValueType() == Value::ConstantVal;
69 /// replaceUsesOfWithOnConstant - This method is a special form of
70 /// User::replaceUsesOfWith (which does not work on constants) that does work
71 /// on constants. Basically this method goes through the trouble of building
72 /// a new constant that is equivalent to the current one, with all uses of
73 /// From replaced with uses of To. After this construction is completed, all
74 /// of the users of 'this' are replaced to use the new constant, and then
75 /// 'this' is deleted. In general, you should not call this method, instead,
76 /// use Value::replaceAllUsesWith, which automatically dispatches to this
79 virtual void replaceUsesOfWithOnConstant(Value *From, Value *To,
80 bool DisableChecking = false) {
81 // Provide a default implementation for constants (like integers) that
82 // cannot use any other values. This cannot be called at runtime, but needs
83 // to be here to avoid link errors.
84 assert(getNumOperands() == 0 && "replaceUsesOfWithOnConstant must be "
85 "implemented for all constants that have operands!");
86 assert(0 && "Constants that do not have operands cannot be using 'From'!");
90 } // End llvm namespace