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//===---------------------- Stage.h -----------------------------*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
/// \file
/// This file defines a stage.
/// A chain of stages compose an instruction pipeline.
#include "llvm/MCA/HWEventListener.h"
#include "llvm/Support/Error.h"
#include <set>
namespace llvm {
namespace mca {
class InstRef;
class Stage {
Stage *NextInSequence;
std::set<HWEventListener *> Listeners;
Stage(const Stage &Other) = delete;
Stage &operator=(const Stage &Other) = delete;
const std::set<HWEventListener *> &getListeners() const { return Listeners; }
Stage() : NextInSequence(nullptr) {}
virtual ~Stage();
/// Returns true if it can execute IR during this cycle.
virtual bool isAvailable(const InstRef &IR) const { return true; }
/// Returns true if some instructions are still executing this stage.
virtual bool hasWorkToComplete() const = 0;
/// Called once at the start of each cycle. This can be used as a setup
/// phase to prepare for the executions during the cycle.
virtual Error cycleStart() { return ErrorSuccess(); }
/// Called once at the end of each cycle.
virtual Error cycleEnd() { return ErrorSuccess(); }
/// The primary action that this stage performs on instruction IR.
virtual Error execute(InstRef &IR) = 0;
void setNextInSequence(Stage *NextStage) {
assert(!NextInSequence && "This stage already has a NextInSequence!");
NextInSequence = NextStage;
bool checkNextStage(const InstRef &IR) const {
return NextInSequence && NextInSequence->isAvailable(IR);
/// Called when an instruction is ready to move the next pipeline stage.
/// Stages are responsible for moving instructions to their immediate
/// successor stages.
Error moveToTheNextStage(InstRef &IR) {
assert(checkNextStage(IR) && "Next stage is not ready!");
return NextInSequence->execute(IR);
/// Add a listener to receive callbacks during the execution of this stage.
void addListener(HWEventListener *Listener);
/// Notify listeners of a particular hardware event.
template <typename EventT> void notifyEvent(const EventT &Event) const {
for (HWEventListener *Listener : Listeners)
} // namespace mca
} // namespace llvm
#endif // LLVM_MCA_STAGE_H