InstrBuilder.h

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//===--------------------- InstrBuilder.h -----------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
/// \file
///
/// A builder class for instructions that are statically analyzed by llvm-mca.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_MCA_INSTRBUILDER_H
#define LLVM_MCA_INSTRBUILDER_H

#include "llvm/MC/MCInstrAnalysis.h"
#include "llvm/MC/MCInstrInfo.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MCA/Instruction.h"
#include "llvm/MCA/Support.h"
#include "llvm/Support/Error.h"

namespace llvm {
namespace mca {

/// A builder class that knows how to construct Instruction objects.
///
/// Every llvm-mca Instruction is described by an object of class InstrDesc.
/// An InstrDesc describes which registers are read/written by the instruction,
/// as well as the instruction latency and hardware resources consumed.
///
/// This class is used by the tool to construct Instructions and instruction
/// descriptors (i.e. InstrDesc objects).
/// Information from the machine scheduling model is used to identify processor
/// resources that are consumed by an instruction.
class InstrBuilder {
  const MCSubtargetInfo &STI;
  const MCInstrInfo &MCII;
  const MCRegisterInfo &MRI;
  const MCInstrAnalysis *MCIA;
  SmallVector<uint64_t, 8> ProcResourceMasks;

  DenseMap<unsigned short, std::unique_ptr<const InstrDesc>> Descriptors;
  DenseMap<const MCInst *, std::unique_ptr<const InstrDesc>> VariantDescriptors;

  bool FirstCallInst;
  bool FirstReturnInst;

  Expected<const InstrDesc &> createInstrDescImpl(const MCInst &MCI);
  Expected<const InstrDesc &> getOrCreateInstrDesc(const MCInst &MCI);

  InstrBuilder(const InstrBuilder &) = delete;
  InstrBuilder &operator=(const InstrBuilder &) = delete;

  void populateWrites(InstrDesc &ID, const MCInst &MCI, unsigned SchedClassID);
  void populateReads(InstrDesc &ID, const MCInst &MCI, unsigned SchedClassID);
  Error verifyInstrDesc(const InstrDesc &ID, const MCInst &MCI) const;

public:
  InstrBuilder(const MCSubtargetInfo &STI, const MCInstrInfo &MCII,
               const MCRegisterInfo &RI, const MCInstrAnalysis *IA);

  void clear() {
    VariantDescriptors.shrink_and_clear();
    FirstCallInst = true;
    FirstReturnInst = true;
  }

  Expected<std::unique_ptr<Instruction>> createInstruction(const MCInst &MCI);
};
} // namespace mca
} // namespace llvm

#endif // LLVM_MCA_INSTRBUILDER_H