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//===---------------------- Stage.h -----------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
/// \file
///
/// This file defines a stage.
/// A chain of stages compose an instruction pipeline.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_TOOLS_LLVM_MCA_STAGE_H
#define LLVM_TOOLS_LLVM_MCA_STAGE_H
#include "HWEventListener.h"
#include "llvm/Support/Error.h"
#include <set>
namespace mca {
class InstRef;
class Stage {
std::set<HWEventListener *> Listeners;
Stage(const Stage &Other) = delete;
Stage &operator=(const Stage &Other) = delete;
public:
/// A Stage's execute() returns Continue, Stop, or an error. Returning
/// Continue means that the stage successfully completed its 'execute'
/// action, and that the instruction being processed can be moved to the next
/// pipeline stage during this cycle. Continue allows the pipeline to
/// continue calling 'execute' on subsequent stages. Returning Stop
/// signifies that the stage ran into an error, and tells the pipeline to stop
/// passing the instruction to subsequent stages during this cycle. Any
/// failures that occur during 'execute' are represented by the error variant
/// that is provided by the Expected template.
enum State { Stop, Continue };
using Status = llvm::Expected<State>;
protected:
const std::set<HWEventListener *> &getListeners() const { return Listeners; }
public:
Stage() {}
virtual ~Stage();
/// Called prior to preExecute to ensure that the stage has items that it
/// is to process. For example, a FetchStage might have more instructions
/// that need to be processed, or a RCU might have items that have yet to
/// retire.
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 llvm::Error cycleStart() { return llvm::ErrorSuccess(); }
/// Called once at the end of each cycle.
virtual llvm::Error cycleEnd() { return llvm::ErrorSuccess(); }
/// Called prior to executing the list of stages.
/// This can be called multiple times per cycle.
virtual void preExecute() {}
/// Called as a cleanup and finalization phase after each execution.
/// This will only be called if all stages return a success from their
/// execute callback. This can be called multiple times per cycle.
virtual void postExecute() {}
/// The primary action that this stage performs.
/// Returning false prevents successor stages from having their 'execute'
/// routine called. This can be called multiple times during a single cycle.
virtual Status execute(InstRef &IR) = 0;
/// 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)
Listener->onEvent(Event);
}
};
} // namespace mca
#endif // LLVM_TOOLS_LLVM_MCA_STAGE_H
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