1//===---------------------- ExecuteStage.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 the execution stage of a default instruction pipeline.
11///
12/// The ExecuteStage is responsible for managing the hardware scheduler
13/// and issuing notifications that an instruction has been executed.
14///
15//===----------------------------------------------------------------------===//
16
17#ifndef LLVM_MCA_STAGES_EXECUTESTAGE_H
18#define LLVM_MCA_STAGES_EXECUTESTAGE_H
19
20#include "llvm/ADT/ArrayRef.h"
21#include "llvm/MCA/HardwareUnits/Scheduler.h"
22#include "llvm/MCA/Instruction.h"
23#include "llvm/MCA/Stages/Stage.h"
24
25namespace llvm {
26namespace mca {
27
28class ExecuteStage final : public Stage {
29 Scheduler &HWS;
30
31 unsigned NumDispatchedOpcodes;
32 unsigned NumIssuedOpcodes;
33
34 // True if this stage should notify listeners of HWPressureEvents.
35 bool EnablePressureEvents;
36
37 Error issueInstruction(InstRef &IR);
38
39 // Called at the beginning of each cycle to issue already dispatched
40 // instructions to the underlying pipelines.
41 Error issueReadyInstructions();
42
43 // Used to notify instructions eliminated at register renaming stage.
44 Error handleInstructionEliminated(InstRef &IR);
45
46 ExecuteStage(const ExecuteStage &Other) = delete;
47 ExecuteStage &operator=(const ExecuteStage &Other) = delete;
48
49public:
50 ExecuteStage(Scheduler &S) : ExecuteStage(S, false) {}
51 ExecuteStage(Scheduler &S, bool ShouldPerformBottleneckAnalysis)
52 : HWS(S), NumDispatchedOpcodes(0), NumIssuedOpcodes(0),
53 EnablePressureEvents(ShouldPerformBottleneckAnalysis) {}
54
55 // This stage works under the assumption that the Pipeline will eventually
56 // execute a retire stage. We don't need to check if pipelines and/or
57 // schedulers have instructions to process, because those instructions are
58 // also tracked by the retire control unit. That means,
59 // RetireControlUnit::hasWorkToComplete() is responsible for checking if there
60 // are still instructions in-flight in the out-of-order backend.
61 bool hasWorkToComplete() const override { return false; }
62 bool isAvailable(const InstRef &IR) const override;
63
64 // Notifies the scheduler that a new cycle just started.
65 //
66 // This method notifies the scheduler that a new cycle started.
67 // This method is also responsible for notifying listeners about instructions
68 // state changes, and processor resources freed by the scheduler.
69 // Instructions that transitioned to the 'Executed' state are automatically
70 // moved to the next stage (i.e. RetireStage).
71 Error cycleStart() override;
72 Error cycleEnd() override;
73 Error execute(InstRef &IR) override;
74
75 void notifyInstructionIssued(const InstRef &IR,
76 MutableArrayRef<ResourceUse> Used) const;
77 void notifyInstructionExecuted(const InstRef &IR) const;
78 void notifyInstructionPending(const InstRef &IR) const;
79 void notifyInstructionReady(const InstRef &IR) const;
80 void notifyResourceAvailable(const ResourceRef &RR) const;
81
82 // Notify listeners that buffered resources have been consumed or freed.
83 void notifyReservedOrReleasedBuffers(const InstRef &IR, bool Reserved) const;
84};
85
86} // namespace mca
87} // namespace llvm
88
89#endif // LLVM_MCA_STAGES_EXECUTESTAGE_H
90

source code of llvm/include/llvm/MCA/Stages/ExecuteStage.h