1 //===-- llvm/Constant.h - Constant class definition --------------*- C++ -*--=//
3 // This file contains the declaration of the Constant class.
5 //===----------------------------------------------------------------------===//
7 #ifndef LLVM_CONSTANT_H
8 #define LLVM_CONSTANT_H
10 #include "llvm/User.h"
12 class Constant : public User {
14 inline Constant(const Type *Ty) : User(Ty, Value::ConstantVal) {}
17 void destroyConstantImpl();
19 // setName - Specialize setName to handle symbol table majik...
20 virtual void setName(const std::string &name, SymbolTable *ST = 0);
22 /// Static constructor to get a '0' constant of arbitrary type...
24 static Constant *getNullValue(const Type *Ty);
26 /// isNullValue - Return true if this is the value that would be returned by
28 virtual bool isNullValue() const = 0;
30 virtual void print(std::ostream &O) const;
32 /// isConstantExpr - Return true if this is a ConstantExpr
34 virtual bool isConstantExpr() const { return false; }
37 /// destroyConstant - Called if some element of this constant is no longer
38 /// valid. At this point only other constants may be on the use_list for this
39 /// constant. Any constants on our Use list must also be destroy'd. The
40 /// implementation must be sure to remove the constant from the list of
41 /// available cached constants. Implementations should call
42 /// destroyConstantImpl as the last thing they do, to destroy all users and
45 /// Note that this call is only valid on non-primitive constants: You cannot
46 /// destroy an integer constant for example. This API is used to delete
47 /// constants that have ConstantPointerRef's embeded in them when the module
48 /// is deleted, and it is used by GlobalDCE to remove ConstantPointerRefs that
49 /// are unneeded, allowing globals to be DCE'd.
51 virtual void destroyConstant() { assert(0 && "Not reached!"); }
54 //// Methods for support type inquiry through isa, cast, and dyn_cast:
55 static inline bool classof(const Constant *) { return true; }
56 static inline bool classof(const Value *V) {
57 return V->getValueType() == Value::ConstantVal;
60 /// replaceUsesOfWithOnConstant - This method is a special form of
61 /// User::replaceUsesOfWith (which does not work on constants) that does work
62 /// on constants. Basically this method goes through the trouble of building
63 /// a new constant that is equivalent to the current one, with all uses of
64 /// From replaced with uses of To. After this construction is completed, all
65 /// of the users of 'this' are replaced to use the new constant, and then
66 /// 'this' is deleted. In general, you should not call this method, instead,
67 /// use Value::replaceAllUsesWith, which automatically dispatches to this
70 virtual void replaceUsesOfWithOnConstant(Value *From, Value *To) {
71 // Provide a default implementation for constants (like integers) that
72 // cannot use any other values. This cannot be called at runtime, but needs
73 // to be here to avoid link errors.
74 assert(getNumOperands() == 0 && "replaceUsesOfWithOnConstant must be "
75 "implemented for all constants that have operands!");
76 assert(0 && "Constants that do not have operands cannot be using 'From'!");
79 // WARNING: Only to be used by Bytecode & Assembly Parsers! USER CODE SHOULD
81 // Returns the number of uses of OldV that were replaced.
82 unsigned mutateReferences(Value* OldV, Value *NewV);