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llvm-mirror/tools/llvm-mca/Backend.h
Matt Davis 0594746649 [llvm-mca] Introduce the ExecuteStage (was originally the Scheduler class).
Summary: This patch transforms the Scheduler class into the ExecuteStage.  Most of the logic remains.  

Reviewers: andreadb, RKSimon, courbet

Reviewed By: andreadb

Subscribers: mgorny, javed.absar, tschuett, gbedwell, llvm-commits

Differential Revision: https://reviews.llvm.org/D47246

llvm-svn: 334679
2018-06-14 01:20:18 +00:00

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3.8 KiB
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//===--------------------- Backend.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 implements an OoO backend for the llvm-mca tool.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_TOOLS_LLVM_MCA_BACKEND_H
#define LLVM_TOOLS_LLVM_MCA_BACKEND_H
#include "DispatchStage.h"
#include "ExecuteStage.h"
#include "FetchStage.h"
#include "InstrBuilder.h"
#include "RegisterFile.h"
#include "RetireControlUnit.h"
#include "RetireStage.h"
#include "Scheduler.h"
namespace mca {
class HWEventListener;
class HWInstructionEvent;
class HWStallEvent;
/// An out of order backend for a specific subtarget.
///
/// It emulates an out-of-order execution of instructions. Instructions are
/// fetched from a MCInst sequence managed by an initial 'Fetch' stage.
/// Instructions are firstly fetched, then dispatched to the schedulers, and
/// then executed.
///
/// This class tracks the lifetime of an instruction from the moment where
/// it gets dispatched to the schedulers, to the moment where it finishes
/// executing and register writes are architecturally committed.
/// In particular, it monitors changes in the state of every instruction
/// in flight.
///
/// Instructions are executed in a loop of iterations. The number of iterations
/// is defined by the SourceMgr object, which is managed by the initial stage
/// of the instruction pipeline.
///
/// The Backend entry point is method 'run()' which executes cycles in a loop
/// until there are new instructions to dispatch, and not every instruction
/// has been retired.
///
/// Internally, the Backend collects statistical information in the form of
/// histograms. For example, it tracks how the dispatch group size changes
/// over time.
class Backend {
// The following are the simulated hardware components of the backend.
RetireControlUnit RCU;
RegisterFile PRF;
Scheduler HWS;
/// TODO: Eventually this will become a list of unique Stage* that this
/// backend pipeline executes.
std::unique_ptr<FetchStage> Fetch;
std::unique_ptr<DispatchStage> Dispatch;
std::unique_ptr<ExecuteStage> Execute;
std::unique_ptr<RetireStage> Retire;
std::set<HWEventListener *> Listeners;
unsigned Cycles;
void runCycle(unsigned Cycle);
public:
Backend(const llvm::MCSubtargetInfo &Subtarget,
const llvm::MCRegisterInfo &MRI,
std::unique_ptr<FetchStage> InitialStage, unsigned DispatchWidth = 0,
unsigned RegisterFileSize = 0, unsigned LoadQueueSize = 0,
unsigned StoreQueueSize = 0, bool AssumeNoAlias = false)
: RCU(Subtarget.getSchedModel()),
PRF(Subtarget.getSchedModel(), MRI, RegisterFileSize),
HWS(Subtarget.getSchedModel(), LoadQueueSize, StoreQueueSize,
AssumeNoAlias),
Fetch(std::move(InitialStage)),
Dispatch(llvm::make_unique<DispatchStage>(
this, Subtarget, MRI, RegisterFileSize, DispatchWidth, RCU, PRF,
HWS)),
Execute(llvm::make_unique<ExecuteStage>(this, RCU, HWS)),
Retire(llvm::make_unique<RetireStage>(this, RCU, PRF)), Cycles(0) {}
void run();
void addEventListener(HWEventListener *Listener);
void notifyCycleBegin(unsigned Cycle);
void notifyInstructionEvent(const HWInstructionEvent &Event);
void notifyStallEvent(const HWStallEvent &Event);
void notifyResourceAvailable(const ResourceRef &RR);
void notifyReservedBuffers(llvm::ArrayRef<unsigned> Buffers);
void notifyReleasedBuffers(llvm::ArrayRef<unsigned> Buffers);
void notifyCycleEnd(unsigned Cycle);
};
} // namespace mca
#endif