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//===-- llvm/AbstractTypeUser.h - AbstractTypeUser Interface ----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// The AbstractTypeUser class is an interface to be implemented by classes who
// could possible use an abstract type. Abstract types are denoted by the
// isAbstract flag set to true in the Type class. These are classes that
// contain an Opaque type in their structure somehow.
//
// Classes must implement this interface so that they may be notified when an
// abstract type is resolved. Abstract types may be resolved into more concrete
// types through: linking, parsing, and bytecode reading. When this happens,
// all of the users of the type must be updated to reference the new, more
// concrete type. They are notified through the AbstractTypeUser interface.
//
// In addition to this, AbstractTypeUsers must keep the use list of the
// potentially abstract type that they reference up-to-date. To do this in a
// nice, transparent way, the PATypeHandle class is used to hold "Potentially
// Abstract Types", and keep the use list of the abstract types up-to-date.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ABSTRACT_TYPE_USER_H
#define LLVM_ABSTRACT_TYPE_USER_H
// This is the "master" include for <cassert> Whether this file needs it or not,
// it must always include <cassert> for the files which include
// llvm/AbstractTypeUser.h
//
// In this way, most every LLVM source file will have access to the assert()
// macro without having to #include <cassert> directly.
//
#include <cassert>
namespace llvm {
class Type;
class DerivedType;
class AbstractTypeUser {
protected:
virtual ~AbstractTypeUser() {} // Derive from me
public:
/// refineAbstractType - The callback method invoked when an abstract type is
/// resolved to another type. An object must override this method to update
/// its internal state to reference NewType instead of OldType.
///
virtual void refineAbstractType(const DerivedType *OldTy,
const Type *NewTy) = 0;
/// The other case which AbstractTypeUsers must be aware of is when a type
/// makes the transition from being abstract (where it has clients on it's
/// AbstractTypeUsers list) to concrete (where it does not). This method
/// notifies ATU's when this occurs for a type.
///
virtual void typeBecameConcrete(const DerivedType *AbsTy) = 0;
// for debugging...
virtual void dump() const = 0;
};
/// PATypeHandle - Handle to a Type subclass. This class is used to keep the
/// use list of abstract types up-to-date.
///
class PATypeHandle {
const Type *Ty;
AbstractTypeUser * const User;
// These functions are defined at the bottom of Type.h. See the comment there
// for justification.
void addUser();
void removeUser();
public:
// ctor - Add use to type if abstract. Note that Ty must not be null
inline PATypeHandle(const Type *ty, AbstractTypeUser *user)
: Ty(ty), User(user) {
addUser();
}
// ctor - Add use to type if abstract.
inline PATypeHandle(const PATypeHandle &T) : Ty(T.Ty), User(T.User) {
addUser();
}
// dtor - Remove reference to type...
inline ~PATypeHandle() { removeUser(); }
// Automatic casting operator so that the handle may be used naturally
inline operator const Type *() const { return Ty; }
inline const Type *get() const { return Ty; }
// operator= - Allow assignment to handle
inline const Type *operator=(const Type *ty) {
if (Ty != ty) { // Ensure we don't accidentally drop last ref to Ty
removeUser();
Ty = ty;
addUser();
}
return Ty;
}
// operator= - Allow assignment to handle
inline const Type *operator=(const PATypeHandle &T) {
return operator=(T.Ty);
}
inline bool operator==(const Type *ty) {
return Ty == ty;
}
// operator-> - Allow user to dereference handle naturally...
inline const Type *operator->() const { return Ty; }
// removeUserFromConcrete - This function should be called when the User is
// notified that our type is refined... and the type is being refined to
// itself, which is now a concrete type. When a type becomes concrete like
// this, we MUST remove ourself from the AbstractTypeUser list, even though
// the type is apparently concrete.
//
void removeUserFromConcrete();
};
/// PATypeHolder - Holder class for a potentially abstract type. This uses
/// efficient union-find techniques to handle dynamic type resolution. Unless
/// you need to do custom processing when types are resolved, you should always
/// use PATypeHolders in preference to PATypeHandles.
///
class PATypeHolder {
mutable const Type *Ty;
public:
PATypeHolder(const Type *ty) : Ty(ty) {
addRef();
}
PATypeHolder(const PATypeHolder &T) : Ty(T.Ty) {
addRef();
}
operator const Type *() const { return get(); }
const Type *get() const;
// operator-> - Allow user to dereference handle naturally...
const Type *operator->() const { return get(); }
// operator= - Allow assignment to handle
const Type *operator=(const Type *ty) {
if (Ty != ty) { // Don't accidentally drop last ref to Ty.
dropRef();
Ty = ty;
addRef();
}
return get();
}
const Type *operator=(const PATypeHolder &H) {
return operator=(H.Ty);
}
private:
void addRef();
void dropRef();
};
} // End llvm namespace
#endif
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