llvm/llvm/include/llvm/CodeGen/GlobalISel/GISelChangeObserver.h

//===----- llvm/CodeGen/GlobalISel/GISelChangeObserver.h --------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
/// \file
/// This contains common code to allow clients to notify changes to machine
/// instr.
///
//===----------------------------------------------------------------------===//

#ifndef LLVM_CODEGEN_GLOBALISEL_GISELCHANGEOBSERVER_H
#define LLVM_CODEGEN_GLOBALISEL_GISELCHANGEOBSERVER_H

#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/CodeGen/MachineFunction.h"

namespace llvm {
class MachineInstr;
class MachineRegisterInfo;

/// Abstract class that contains various methods for clients to notify about
/// changes. This should be the preferred way for APIs to notify changes.
/// Typically calling erasingInstr/createdInstr multiple times should not affect
/// the result. The observer would likely need to check if it was already
/// notified earlier (consider using GISelWorkList).
class GISelChangeObserver { … };

/// Simple wrapper observer that takes several observers, and calls
/// each one for each event. If there are multiple observers (say CSE,
/// Legalizer, Combiner), it's sufficient to register this to the machine
/// function as the delegate.
class GISelObserverWrapper : public MachineFunction::Delegate,
                             public GISelChangeObserver { … };

/// A simple RAII based Delegate installer.
/// Use this in a scope to install a delegate to the MachineFunction and reset
/// it at the end of the scope.
class RAIIDelegateInstaller { … };

/// A simple RAII based Observer installer.
/// Use this in a scope to install the Observer to the MachineFunction and reset
/// it at the end of the scope.
class RAIIMFObserverInstaller { … };

/// Class to install both of the above.
class RAIIMFObsDelInstaller { … };

/// A simple RAII based Observer installer.
/// Use this in a scope to install the Observer to the MachineFunction and reset
/// it at the end of the scope.
class RAIITemporaryObserverInstaller { … };

} // namespace llvm
#endif