Stage.h revision 353358 
1//===---------------------- Stage.h -----------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8/// \file
9///
10/// This file defines a stage.
11/// A chain of stages compose an instruction pipeline.
12///
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_MCA_STAGE_H
16#define LLVM_MCA_STAGE_H
17
18#include "llvm/MCA/HWEventListener.h"
19#include "llvm/Support/Error.h"
20#include <set>
21
22namespace llvm {
23namespace mca {
24
25class InstRef;
26
27class Stage {
28  Stage *NextInSequence;
29  std::set<HWEventListener *> Listeners;
30
31  Stage(const Stage &Other) = delete;
32  Stage &operator=(const Stage &Other) = delete;
33
34protected:
35  const std::set<HWEventListener *> &getListeners() const { return Listeners; }
36
37public:
38  Stage() : NextInSequence(nullptr) {}
39  virtual ~Stage();
40
41  /// Returns true if it can execute IR during this cycle.
42  virtual bool isAvailable(const InstRef &IR) const { return true; }
43
44  /// Returns true if some instructions are still executing this stage.
45  virtual bool hasWorkToComplete() const = 0;
46
47  /// Called once at the start of each cycle.  This can be used as a setup
48  /// phase to prepare for the executions during the cycle.
49  virtual Error cycleStart() { return ErrorSuccess(); }
50
51  /// Called once at the end of each cycle.
52  virtual Error cycleEnd() { return ErrorSuccess(); }
53
54  /// The primary action that this stage performs on instruction IR.
55  virtual Error execute(InstRef &IR) = 0;
56
57  void setNextInSequence(Stage *NextStage) {
58    assert(!NextInSequence && "This stage already has a NextInSequence!");
59    NextInSequence = NextStage;
60  }
61
62  bool checkNextStage(const InstRef &IR) const {
63    return NextInSequence && NextInSequence->isAvailable(IR);
64  }
65
66  /// Called when an instruction is ready to move the next pipeline stage.
67  ///
68  /// Stages are responsible for moving instructions to their immediate
69  /// successor stages.
70  Error moveToTheNextStage(InstRef &IR) {
71    assert(checkNextStage(IR) && "Next stage is not ready!");
72    return NextInSequence->execute(IR);
73  }
74
75  /// Add a listener to receive callbacks during the execution of this stage.
76  void addListener(HWEventListener *Listener);
77
78  /// Notify listeners of a particular hardware event.
79  template <typename EventT> void notifyEvent(const EventT &Event) const {
80    for (HWEventListener *Listener : Listeners)
81      Listener->onEvent(Event);
82  }
83};
84
85} // namespace mca
86} // namespace llvm
87#endif // LLVM_MCA_STAGE_H
88