Yi Kong | 878f994 | 2023-12-13 12:55:04 +0900 | [diff] [blame^] | 1 | //===---------------------- CustomBehaviour.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 base class CustomBehaviour which can be inherited from |
| 11 | /// by specific targets (ex. llvm/tools/llvm-mca/lib/X86CustomBehaviour.h). |
| 12 | /// CustomBehaviour is designed to enforce custom behaviour and dependencies |
| 13 | /// within the llvm-mca pipeline simulation that llvm-mca isn't already capable |
| 14 | /// of extracting from the Scheduling Models. |
| 15 | /// |
| 16 | //===----------------------------------------------------------------------===// |
| 17 | |
| 18 | #ifndef LLVM_MCA_CUSTOMBEHAVIOUR_H |
| 19 | #define LLVM_MCA_CUSTOMBEHAVIOUR_H |
| 20 | |
| 21 | #include "llvm/ADT/SmallVector.h" |
| 22 | #include "llvm/MC/MCInst.h" |
| 23 | #include "llvm/MC/MCInstrInfo.h" |
| 24 | #include "llvm/MC/MCSubtargetInfo.h" |
| 25 | #include "llvm/MCA/SourceMgr.h" |
| 26 | #include "llvm/MCA/View.h" |
| 27 | |
| 28 | namespace llvm { |
| 29 | namespace mca { |
| 30 | |
| 31 | /// Class which can be overriden by targets to modify the |
| 32 | /// mca::Instruction objects before the pipeline starts. |
| 33 | /// A common usage of this class is to add immediate operands to certain |
| 34 | /// instructions or to remove Defs/Uses from an instruction where the |
| 35 | /// schedulinng model is incorrect. |
| 36 | class InstrPostProcess { |
| 37 | protected: |
| 38 | const MCSubtargetInfo &STI; |
| 39 | const MCInstrInfo &MCII; |
| 40 | |
| 41 | public: |
| 42 | InstrPostProcess(const MCSubtargetInfo &STI, const MCInstrInfo &MCII) |
| 43 | : STI(STI), MCII(MCII) {} |
| 44 | |
| 45 | virtual ~InstrPostProcess() = default; |
| 46 | |
| 47 | /// This method can be overriden by targets to modify the mca::Instruction |
| 48 | /// object after it has been lowered from the MCInst. |
| 49 | /// This is generally a less disruptive alternative to modifying the |
| 50 | /// scheduling model. |
| 51 | virtual void postProcessInstruction(std::unique_ptr<Instruction> &Inst, |
| 52 | const MCInst &MCI) {} |
| 53 | |
| 54 | // The resetState() method gets invoked at the beginning of each code region |
| 55 | // so that targets that override this function can clear any state that they |
| 56 | // have left from the previous code region. |
| 57 | virtual void resetState() {} |
| 58 | }; |
| 59 | |
| 60 | /// Class which can be overriden by targets to enforce instruction |
| 61 | /// dependencies and behaviours that aren't expressed well enough |
| 62 | /// within the scheduling model for mca to automatically simulate |
| 63 | /// them properly. |
| 64 | /// If you implement this class for your target, make sure to also implement |
| 65 | /// a target specific InstrPostProcess class as well. |
| 66 | class CustomBehaviour { |
| 67 | protected: |
| 68 | const MCSubtargetInfo &STI; |
| 69 | const mca::SourceMgr &SrcMgr; |
| 70 | const MCInstrInfo &MCII; |
| 71 | |
| 72 | public: |
| 73 | CustomBehaviour(const MCSubtargetInfo &STI, const mca::SourceMgr &SrcMgr, |
| 74 | const MCInstrInfo &MCII) |
| 75 | : STI(STI), SrcMgr(SrcMgr), MCII(MCII) {} |
| 76 | |
| 77 | virtual ~CustomBehaviour(); |
| 78 | |
| 79 | /// Before the llvm-mca pipeline dispatches an instruction, it first checks |
| 80 | /// for any register or resource dependencies / hazards. If it doesn't find |
| 81 | /// any, this method will be invoked to determine if there are any custom |
| 82 | /// hazards that the instruction needs to wait for. |
| 83 | /// The return value of this method is the number of cycles that the |
| 84 | /// instruction needs to wait for. |
| 85 | /// It's safe to underestimate the number of cycles to wait for since these |
| 86 | /// checks will be invoked again before the intruction gets dispatched. |
| 87 | /// However, it's not safe (accurate) to overestimate the number of cycles |
| 88 | /// to wait for since the instruction will wait for AT LEAST that number of |
| 89 | /// cycles before attempting to be dispatched again. |
| 90 | virtual unsigned checkCustomHazard(ArrayRef<InstRef> IssuedInst, |
| 91 | const InstRef &IR); |
| 92 | |
| 93 | // Functions that target CBs can override to return a list of |
| 94 | // target specific Views that need to live within /lib/Target/ so that |
| 95 | // they can benefit from the target CB or from backend functionality that is |
| 96 | // not already exposed through MC-layer classes. Keep in mind that how this |
| 97 | // function is used is that the function is called within llvm-mca.cpp and |
| 98 | // then each unique_ptr<View> is passed into the PipelinePrinter::addView() |
| 99 | // function. This function will then std::move the View into its own vector of |
| 100 | // Views. So any CB that overrides this function needs to make sure that they |
| 101 | // are not relying on the current address or reference of the View |
| 102 | // unique_ptrs. If you do need the CB and View to be able to communicate with |
| 103 | // each other, consider giving the View a reference or pointer to the CB when |
| 104 | // the View is constructed. Then the View can query the CB for information |
| 105 | // when it needs it. |
| 106 | /// Return a vector of Views that will be added before all other Views. |
| 107 | virtual std::vector<std::unique_ptr<View>> |
| 108 | getStartViews(llvm::MCInstPrinter &IP, llvm::ArrayRef<llvm::MCInst> Insts); |
| 109 | /// Return a vector of Views that will be added after the InstructionInfoView. |
| 110 | virtual std::vector<std::unique_ptr<View>> |
| 111 | getPostInstrInfoViews(llvm::MCInstPrinter &IP, |
| 112 | llvm::ArrayRef<llvm::MCInst> Insts); |
| 113 | /// Return a vector of Views that will be added after all other Views. |
| 114 | virtual std::vector<std::unique_ptr<View>> |
| 115 | getEndViews(llvm::MCInstPrinter &IP, llvm::ArrayRef<llvm::MCInst> Insts); |
| 116 | }; |
| 117 | |
| 118 | class Instrument { |
| 119 | /// The description of Instrument kind |
| 120 | const StringRef Desc; |
| 121 | |
| 122 | /// The instrumentation data |
| 123 | const StringRef Data; |
| 124 | |
| 125 | public: |
| 126 | Instrument(StringRef Desc, StringRef Data) : Desc(Desc), Data(Data) {} |
| 127 | |
| 128 | Instrument() : Instrument("", "") {} |
| 129 | |
| 130 | virtual ~Instrument() = default; |
| 131 | |
| 132 | StringRef getDesc() const { return Desc; } |
| 133 | StringRef getData() const { return Data; } |
| 134 | }; |
| 135 | |
| 136 | using UniqueInstrument = std::unique_ptr<Instrument>; |
| 137 | |
| 138 | /// This class allows targets to optionally customize the logic that resolves |
| 139 | /// scheduling class IDs. Targets can use information encoded in Instrument |
| 140 | /// objects to make more informed scheduling decisions. |
| 141 | class InstrumentManager { |
| 142 | protected: |
| 143 | const MCSubtargetInfo &STI; |
| 144 | const MCInstrInfo &MCII; |
| 145 | |
| 146 | public: |
| 147 | InstrumentManager(const MCSubtargetInfo &STI, const MCInstrInfo &MCII) |
| 148 | : STI(STI), MCII(MCII) {} |
| 149 | |
| 150 | virtual ~InstrumentManager() = default; |
| 151 | |
| 152 | /// Returns true if llvm-mca should ignore instruments. |
| 153 | virtual bool shouldIgnoreInstruments() const { return true; } |
| 154 | |
| 155 | // Returns true if this supports processing Instrument with |
| 156 | // Instrument.Desc equal to Type |
| 157 | virtual bool supportsInstrumentType(StringRef Type) const { return false; } |
| 158 | |
| 159 | /// Allocate an Instrument, and return a unique pointer to it. This function |
| 160 | /// may be useful to create instruments coming from comments in the assembly. |
| 161 | /// See createInstruments to create Instruments from MCInst |
| 162 | virtual UniqueInstrument createInstrument(StringRef Desc, StringRef Data); |
| 163 | |
| 164 | /// Return a list of unique pointers to Instruments, where each Instrument |
| 165 | /// is allocated by this function. See createInstrument to create Instrument |
| 166 | /// from a description and data. |
| 167 | virtual SmallVector<UniqueInstrument> createInstruments(const MCInst &Inst); |
| 168 | |
| 169 | /// Given an MCInst and a vector of Instrument, a target can |
| 170 | /// return a SchedClassID. This can be used by a subtarget to return a |
| 171 | /// PseudoInstruction SchedClassID instead of the one that belongs to the |
| 172 | /// BaseInstruction This can be useful when a BaseInstruction does not convey |
| 173 | /// the correct scheduling information without additional data. By default, |
| 174 | /// it returns the SchedClassID that belongs to MCI. |
| 175 | virtual unsigned getSchedClassID(const MCInstrInfo &MCII, const MCInst &MCI, |
| 176 | const SmallVector<Instrument *> &IVec) const; |
| 177 | }; |
| 178 | |
| 179 | } // namespace mca |
| 180 | } // namespace llvm |
| 181 | |
| 182 | #endif /* LLVM_MCA_CUSTOMBEHAVIOUR_H */ |