1 //===-- llvm/AbstractTypeUser.h - AbstractTypeUser Interface -----*- C++ -*--=//
3 // The AbstractTypeUser class is an interface to be implemented by classes who
4 // could possible use an abstract type. Abstract types are denoted by the
5 // isAbstract flag set to true in the Type class. These are classes that
6 // contain an Opaque type in their structure somehow.
8 // Classes must implement this interface so that they may be notified when an
9 // abstract type is resolved. Abstract types may be resolved into more concrete
10 // types through: linking, parsing, and bytecode reading. When this happens,
11 // all of the users of the type must be updated to reference the new, more
12 // concrete type. They are notified through the AbstractTypeUser interface.
14 // In addition to this, AbstractTypeUsers must keep the use list of the
15 // potentially abstract type that they reference up-to-date. To do this in a
16 // nice, transparent way, the PATypeHandle class is used to hold "Potentially
17 // Abstract Types", and keep the use list of the abstract types up-to-date.
19 //===----------------------------------------------------------------------===//
21 #ifndef LLVM_ABSTRACT_TYPE_USER_H
22 #define LLVM_ABSTRACT_TYPE_USER_H
27 class AbstractTypeUser {
29 virtual ~AbstractTypeUser() {} // Derive from me
32 // refineAbstractType - The callback method invoked when an abstract type
33 // has been found to be more concrete. A class must override this method to
34 // update its internal state to reference NewType instead of OldType. Soon
35 // after this method is invoked, OldType shall be deleted, so referencing it
38 // Another case that is important to consider is when a type is refined, but
39 // stays in the same place in memory. In this case OldTy will equal NewTy.
40 // This callback just notifies ATU's that the underlying structure of the type
41 // has changed... but any previously used properties are still valid.
43 // Note that it is possible to refine a type with parameters OldTy==NewTy, and
44 // OldTy is no longer abstract. In this case, abstract type users should
45 // release their hold on a type, because it went from being abstract to
48 virtual void refineAbstractType(const DerivedType *OldTy,
49 const Type *NewTy) = 0;
51 virtual void dump() const = 0;
55 // PATypeHandle - Handle to a Type subclass. This class is parameterized so
56 // that users can have handles to FunctionType's that are still specialized, for
57 // example. This class is a simple class used to keep the use list of abstract
60 template <class TypeSubClass>
62 const TypeSubClass *Ty;
63 AbstractTypeUser * const User;
65 // These functions are defined at the bottom of Type.h. See the comment there
67 inline void addUser();
68 inline void removeUser();
70 // ctor - Add use to type if abstract. Note that Ty must not be null
71 inline PATypeHandle(const TypeSubClass *ty, AbstractTypeUser *user)
72 : Ty(ty), User(user) {
76 // ctor - Add use to type if abstract.
77 inline PATypeHandle(const PATypeHandle &T) : Ty(T.Ty), User(T.User) {
81 // dtor - Remove reference to type...
82 inline ~PATypeHandle() { removeUser(); }
84 // Automatic casting operator so that the handle may be used naturally
85 inline operator const TypeSubClass *() const { return Ty; }
86 inline const TypeSubClass *get() const { return Ty; }
88 // operator= - Allow assignment to handle
89 inline const TypeSubClass *operator=(const TypeSubClass *ty) {
90 if (Ty != ty) { // Ensure we don't accidentally drop last ref to Ty
98 // operator= - Allow assignment to handle
99 inline const TypeSubClass *operator=(const PATypeHandle &T) {
100 return operator=(T.Ty);
103 inline bool operator==(const TypeSubClass *ty) {
107 // operator-> - Allow user to dereference handle naturally...
108 inline const TypeSubClass *operator->() const { return Ty; }
110 // removeUserFromConcrete - This function should be called when the User is
111 // notified that our type is refined... and the type is being refined to
112 // itself, which is now a concrete type. When a type becomes concrete like
113 // this, we MUST remove ourself from the AbstractTypeUser list, even though
114 // the type is apparently concrete.
116 inline void removeUserFromConcrete();
120 // PATypeHolder - Holder class for a potentially abstract type. This functions
121 // as both a handle (as above) and an AbstractTypeUser. It uses the callback to
122 // keep its pointer member updated to the current version of the type.
124 struct PATypeHolder : public AbstractTypeUser, public PATypeHandle<Type> {
125 inline PATypeHolder(const Type *ty) : PATypeHandle<Type>(ty, this) {}
126 inline PATypeHolder(const PATypeHolder &T)
127 : AbstractTypeUser(T), PATypeHandle<Type>(T, this) {}
129 // refineAbstractType - All we do is update our PATypeHandle member to point
132 virtual void refineAbstractType(const DerivedType *OldTy, const Type *NewTy) {
133 assert(get() == (const Type*)OldTy && "Can't refine to unknown value!");
135 // Check to see if the type just became concrete. If so, we have to
136 // removeUser to get off its AbstractTypeUser list
137 removeUserFromConcrete();
139 if ((const Type*)OldTy != NewTy)
140 PATypeHandle<Type>::operator=(NewTy);
143 // operator= - Allow assignment to handle
144 inline const Type *operator=(const Type *ty) {
145 return PATypeHandle<Type>::operator=(ty);
148 // operator= - Allow assignment to handle
149 inline const Type *operator=(const PATypeHandle<Type> &T) {
150 return PATypeHandle<Type>::operator=(T);
152 inline const Type *operator=(const PATypeHolder &H) {
153 return PATypeHandle<Type>::operator=(H);