//===---------------------- CustomBehaviour.h -------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
/// \file
///
/// This file defines the base class CustomBehaviour which can be inherited from
/// by specific targets (ex. llvm/tools/llvm-mca/lib/X86CustomBehaviour.h).
/// CustomBehaviour is designed to enforce custom behaviour and dependencies
/// within the llvm-mca pipeline simulation that llvm-mca isn't already capable
/// of extracting from the Scheduling Models.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_MCA_CUSTOMBEHAVIOUR_H
#define LLVM_MCA_CUSTOMBEHAVIOUR_H
#include "llvm/ADT/SmallVector.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCInstrInfo.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MCA/SourceMgr.h"
#include "llvm/MCA/View.h"
namespace llvm {
namespace mca {
/// Class which can be overriden by targets to modify the
/// mca::Instruction objects before the pipeline starts.
/// A common usage of this class is to add immediate operands to certain
/// instructions or to remove Defs/Uses from an instruction where the
/// schedulinng model is incorrect.
class InstrPostProcess {
protected:
const MCSubtargetInfo &STI;
const MCInstrInfo &MCII;
public:
InstrPostProcess(const MCSubtargetInfo &STI, const MCInstrInfo &MCII)
: STI(STI), MCII(MCII) {}
virtual ~InstrPostProcess() = default;
/// This method can be overriden by targets to modify the mca::Instruction
/// object after it has been lowered from the MCInst.
/// This is generally a less disruptive alternative to modifying the
/// scheduling model.
virtual void postProcessInstruction(std::unique_ptr<Instruction> &Inst,
const MCInst &MCI) {}
// The resetState() method gets invoked at the beginning of each code region
// so that targets that override this function can clear any state that they
// have left from the previous code region.
virtual void resetState() {}
};
/// Class which can be overriden by targets to enforce instruction
/// dependencies and behaviours that aren't expressed well enough
/// within the scheduling model for mca to automatically simulate
/// them properly.
/// If you implement this class for your target, make sure to also implement
/// a target specific InstrPostProcess class as well.
class CustomBehaviour {
protected:
const MCSubtargetInfo &STI;
const mca::SourceMgr &SrcMgr;
const MCInstrInfo &MCII;
public:
CustomBehaviour(const MCSubtargetInfo &STI, const mca::SourceMgr &SrcMgr,
const MCInstrInfo &MCII)
: STI(STI), SrcMgr(SrcMgr), MCII(MCII) {}
virtual ~CustomBehaviour();
/// Before the llvm-mca pipeline dispatches an instruction, it first checks
/// for any register or resource dependencies / hazards. If it doesn't find
/// any, this method will be invoked to determine if there are any custom
/// hazards that the instruction needs to wait for.
/// The return value of this method is the number of cycles that the
/// instruction needs to wait for.
/// It's safe to underestimate the number of cycles to wait for since these
/// checks will be invoked again before the intruction gets dispatched.
/// However, it's not safe (accurate) to overestimate the number of cycles
/// to wait for since the instruction will wait for AT LEAST that number of
/// cycles before attempting to be dispatched again.
virtual unsigned checkCustomHazard(ArrayRef<InstRef> IssuedInst,
const InstRef &IR);
// Functions that target CBs can override to return a list of
// target specific Views that need to live within /lib/Target/ so that
// they can benefit from the target CB or from backend functionality that is
// not already exposed through MC-layer classes. Keep in mind that how this
// function is used is that the function is called within llvm-mca.cpp and
// then each unique_ptr<View> is passed into the PipelinePrinter::addView()
// function. This function will then std::move the View into its own vector of
// Views. So any CB that overrides this function needs to make sure that they
// are not relying on the current address or reference of the View
// unique_ptrs. If you do need the CB and View to be able to communicate with
// each other, consider giving the View a reference or pointer to the CB when
// the View is constructed. Then the View can query the CB for information
// when it needs it.
/// Return a vector of Views that will be added before all other Views.
virtual std::vector<std::unique_ptr<View>>
getStartViews(llvm::MCInstPrinter &IP, llvm::ArrayRef<llvm::MCInst> Insts);
/// Return a vector of Views that will be added after the InstructionInfoView.
virtual std::vector<std::unique_ptr<View>>
getPostInstrInfoViews(llvm::MCInstPrinter &IP,
llvm::ArrayRef<llvm::MCInst> Insts);
/// Return a vector of Views that will be added after all other Views.
virtual std::vector<std::unique_ptr<View>>
getEndViews(llvm::MCInstPrinter &IP, llvm::ArrayRef<llvm::MCInst> Insts);
};
class Instrument {
/// The description of Instrument kind
const StringRef Desc;
/// The instrumentation data
const StringRef Data;
public:
Instrument(StringRef Desc, StringRef Data) : Desc(Desc), Data(Data) {}
Instrument() : Instrument("", "") {}
virtual ~Instrument() = default;
StringRef getDesc() const { return Desc; }
StringRef getData() const { return Data; }
};
using SharedInstrument = std::shared_ptr<Instrument>;
/// This class allows targets to optionally customize the logic that resolves
/// scheduling class IDs. Targets can use information encoded in Instrument
/// objects to make more informed scheduling decisions.
class InstrumentManager {
protected:
const MCSubtargetInfo &STI;
const MCInstrInfo &MCII;
public:
InstrumentManager(const MCSubtargetInfo &STI, const MCInstrInfo &MCII)
: STI(STI), MCII(MCII) {}
virtual ~InstrumentManager() = default;
/// Returns true if llvm-mca should ignore instruments.
virtual bool shouldIgnoreInstruments() const { return true; }
// Returns true if this supports processing Instrument with
// Instrument.Desc equal to Type
virtual bool supportsInstrumentType(StringRef Type) const { return false; }
/// Allocate an Instrument, and return a shared pointer to it.
virtual SharedInstrument createInstrument(StringRef Desc, StringRef Data);
/// Given an MCInst and a vector of Instrument, a target can
/// return a SchedClassID. This can be used by a subtarget to return a
/// PseudoInstruction SchedClassID instead of the one that belongs to the
/// BaseInstruction This can be useful when a BaseInstruction does not convey
/// the correct scheduling information without additional data. By default,
/// it returns the SchedClassID that belongs to MCI.
virtual unsigned
getSchedClassID(const MCInstrInfo &MCII, const MCInst &MCI,
const SmallVector<SharedInstrument> &IVec) const;
};
} // namespace mca
} // namespace llvm
#endif /* LLVM_MCA_CUSTOMBEHAVIOUR_H */