1 //===-- llvm/AbstractTypeUser.h - AbstractTypeUser Interface ----*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file declares the AbstractTypeUser class.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_ABSTRACT_TYPE_USER_H
15 #define LLVM_ABSTRACT_TYPE_USER_H
17 #if !defined(LLVM_TYPE_H) && !defined(LLVM_VALUE_H)
18 #error Do not include this file directly. Include Type.h instead.
19 #error Some versions of GCC (e.g. 3.4 and 4.1) can not handle the inlined method
20 #error PATypeHolder::dropRef() correctly otherwise.
23 // This is the "master" include for <cassert> Whether this file needs it or not,
24 // it must always include <cassert> for the files which include
25 // llvm/AbstractTypeUser.h
27 // In this way, most every LLVM source file will have access to the assert()
28 // macro without having to #include <cassert> directly.
37 /// The AbstractTypeUser class is an interface to be implemented by classes who
38 /// could possibly use an abstract type. Abstract types are denoted by the
39 /// isAbstract flag set to true in the Type class. These are classes that
40 /// contain an Opaque type in their structure somewhere.
42 /// Classes must implement this interface so that they may be notified when an
43 /// abstract type is resolved. Abstract types may be resolved into more
44 /// concrete types through: linking, parsing, and bitcode reading. When this
45 /// happens, all of the users of the type must be updated to reference the new,
46 /// more concrete type. They are notified through the AbstractTypeUser
49 /// In addition to this, AbstractTypeUsers must keep the use list of the
50 /// potentially abstract type that they reference up-to-date. To do this in a
51 /// nice, transparent way, the PATypeHandle class is used to hold "Potentially
52 /// Abstract Types", and keep the use list of the abstract types up-to-date.
53 /// @brief LLVM Abstract Type User Representation
54 class AbstractTypeUser {
56 virtual ~AbstractTypeUser(); // Derive from me
59 /// refineAbstractType - The callback method invoked when an abstract type is
60 /// resolved to another type. An object must override this method to update
61 /// its internal state to reference NewType instead of OldType.
63 virtual void refineAbstractType(const DerivedType *OldTy,
64 const Type *NewTy) = 0;
66 /// The other case which AbstractTypeUsers must be aware of is when a type
67 /// makes the transition from being abstract (where it has clients on it's
68 /// AbstractTypeUsers list) to concrete (where it does not). This method
69 /// notifies ATU's when this occurs for a type.
71 virtual void typeBecameConcrete(const DerivedType *AbsTy) = 0;
74 virtual void dump() const = 0;
78 /// PATypeHandle - Handle to a Type subclass. This class is used to keep the
79 /// use list of abstract types up-to-date.
83 AbstractTypeUser * const User;
85 // These functions are defined at the bottom of Type.h. See the comment there
90 // ctor - Add use to type if abstract. Note that Ty must not be null
91 inline PATypeHandle(const Type *ty, AbstractTypeUser *user)
92 : Ty(ty), User(user) {
96 // ctor - Add use to type if abstract.
97 inline PATypeHandle(const PATypeHandle &T) : Ty(T.Ty), User(T.User) {
101 // dtor - Remove reference to type...
102 inline ~PATypeHandle() { removeUser(); }
104 // Automatic casting operator so that the handle may be used naturally
105 inline operator Type *() const { return const_cast<Type*>(Ty); }
106 inline Type *get() const { return const_cast<Type*>(Ty); }
108 // operator= - Allow assignment to handle
109 inline Type *operator=(const Type *ty) {
110 if (Ty != ty) { // Ensure we don't accidentally drop last ref to Ty
118 // operator= - Allow assignment to handle
119 inline const Type *operator=(const PATypeHandle &T) {
120 return operator=(T.Ty);
123 inline bool operator==(const Type *ty) {
127 // operator-> - Allow user to dereference handle naturally...
128 inline const Type *operator->() const { return Ty; }
132 /// PATypeHolder - Holder class for a potentially abstract type. This uses
133 /// efficient union-find techniques to handle dynamic type resolution. Unless
134 /// you need to do custom processing when types are resolved, you should always
135 /// use PATypeHolders in preference to PATypeHandles.
138 mutable const Type *Ty;
140 PATypeHolder(const Type *ty) : Ty(ty) {
143 PATypeHolder(const PATypeHolder &T) : Ty(T.Ty) {
147 ~PATypeHolder() { dropRef(); }
149 operator Type *() const { return get(); }
152 // operator-> - Allow user to dereference handle naturally...
153 Type *operator->() const { return get(); }
155 // operator= - Allow assignment to handle
156 Type *operator=(const Type *ty) {
157 if (Ty != ty) { // Don't accidentally drop last ref to Ty.
164 Type *operator=(const PATypeHolder &H) {
165 return operator=(H.Ty);
168 /// getRawType - This should only be used to implement the vmcore library.
170 const Type *getRawType() const { return Ty; }
177 } // End llvm namespace