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/MC/MCInst.h" 22 #include "llvm/MC/MCInstrInfo.h" 23 #include "llvm/MC/MCSubtargetInfo.h" 24 #include "llvm/MCA/SourceMgr.h" 25 26 namespace llvm { 27 namespace mca { 28 29 /// Class which can be overriden by targets to modify the 30 /// mca::Instruction objects before the pipeline starts. 31 /// A common usage of this class is to add immediate operands to certain 32 /// instructions or to remove Defs/Uses from an instruction where the 33 /// schedulinng model is incorrect. 34 class InstrPostProcess { 35 protected: 36 const MCSubtargetInfo &STI; 37 const MCInstrInfo &MCII; 38 39 public: 40 InstrPostProcess(const MCSubtargetInfo &STI, const MCInstrInfo &MCII) 41 : STI(STI), MCII(MCII) {} 42 43 virtual ~InstrPostProcess() {} 44 45 virtual void postProcessInstruction(std::unique_ptr<Instruction> &Inst, 46 const MCInst &MCI) {} 47 }; 48 49 /// Class which can be overriden by targets to enforce instruction 50 /// dependencies and behaviours that aren't expressed well enough 51 /// within the scheduling model for mca to automatically simulate 52 /// them properly. 53 /// If you implement this class for your target, make sure to also implement 54 /// a target specific InstrPostProcess class as well. 55 class CustomBehaviour { 56 protected: 57 const MCSubtargetInfo &STI; 58 const SourceMgr &SrcMgr; 59 const MCInstrInfo &MCII; 60 61 public: 62 CustomBehaviour(const MCSubtargetInfo &STI, const SourceMgr &SrcMgr, 63 const MCInstrInfo &MCII) 64 : STI(STI), SrcMgr(SrcMgr), MCII(MCII) {} 65 66 virtual ~CustomBehaviour(); 67 68 // Before the llvm-mca pipeline dispatches an instruction, it first checks 69 // for any register or resource dependencies / hazards. If it doesn't find 70 // any, this method will be invoked to determine if there are any custom 71 // hazards that the instruction needs to wait for. 72 // The return value of this method is the number of cycles that the 73 // instruction needs to wait for. 74 // It's safe to underestimate the number of cycles to wait for since these 75 // checks will be invoked again before the intruction gets dispatched. 76 // However, it's not safe (accurate) to overestimate the number of cycles 77 // to wait for since the instruction will wait for AT LEAST that number of 78 // cycles before attempting to be dispatched again. 79 virtual unsigned checkCustomHazard(ArrayRef<InstRef> IssuedInst, 80 const InstRef &IR); 81 }; 82 83 } // namespace mca 84 } // namespace llvm 85 86 #endif /* LLVM_MCA_CUSTOMBEHAVIOUR_H */ 87