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"
19 class Constant : public User {
21 inline Constant(const Type *Ty) : User(Ty, Value::ConstantVal) {}
24 void destroyConstantImpl();
26 // setName - Specialize setName to handle symbol table majik...
27 virtual void setName(const std::string &name, SymbolTable *ST = 0);
29 /// Static constructor to get a '0' constant of arbitrary type...
31 static Constant *getNullValue(const Type *Ty);
33 /// isNullValue - Return true if this is the value that would be returned by
35 virtual bool isNullValue() const = 0;
37 virtual void print(std::ostream &O) const;
39 /// isConstantExpr - Return true if this is a ConstantExpr
41 virtual bool isConstantExpr() const { return false; }
44 /// destroyConstant - Called if some element of this constant is no longer
45 /// valid. At this point only other constants may be on the use_list for this
46 /// constant. Any constants on our Use list must also be destroy'd. The
47 /// implementation must be sure to remove the constant from the list of
48 /// available cached constants. Implementations should call
49 /// destroyConstantImpl as the last thing they do, to destroy all users and
52 /// Note that this call is only valid on non-primitive constants: You cannot
53 /// destroy an integer constant for example. This API is used to delete
54 /// constants that have ConstantPointerRef's embeded in them when the module
55 /// is deleted, and it is used by GlobalDCE to remove ConstantPointerRefs that
56 /// are unneeded, allowing globals to be DCE'd.
58 virtual void destroyConstant() { assert(0 && "Not reached!"); }
61 //// Methods for support type inquiry through isa, cast, and dyn_cast:
62 static inline bool classof(const Constant *) { return true; }
63 static inline bool classof(const Value *V) {
64 return V->getValueType() == Value::ConstantVal;
67 /// replaceUsesOfWithOnConstant - This method is a special form of
68 /// User::replaceUsesOfWith (which does not work on constants) that does work
69 /// on constants. Basically this method goes through the trouble of building
70 /// a new constant that is equivalent to the current one, with all uses of
71 /// From replaced with uses of To. After this construction is completed, all
72 /// of the users of 'this' are replaced to use the new constant, and then
73 /// 'this' is deleted. In general, you should not call this method, instead,
74 /// use Value::replaceAllUsesWith, which automatically dispatches to this
77 virtual void replaceUsesOfWithOnConstant(Value *From, Value *To,
78 bool DisableChecking = false) {
79 // Provide a default implementation for constants (like integers) that
80 // cannot use any other values. This cannot be called at runtime, but needs
81 // to be here to avoid link errors.
82 assert(getNumOperands() == 0 && "replaceUsesOfWithOnConstant must be "
83 "implemented for all constants that have operands!");
84 assert(0 && "Constants that do not have operands cannot be using 'From'!");
87 // WARNING: Only to be used by Bytecode & Assembly Parsers! USER CODE SHOULD
89 // Returns the number of uses of OldV that were replaced.
90 unsigned mutateReferences(Value* OldV, Value *NewV);