//=-- BPFMCInstLower.cpp - Convert BPF MachineInstr to an MCInst ------------=//

//

// 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

//

//===----------------------------------------------------------------------===//

//

// This file contains code to lower BPF MachineInstrs to their corresponding

// MCInst records.

//

//===----------------------------------------------------------------------===//

#include "BPFMCInstLower.h"

#include "llvm/CodeGen/AsmPrinter.h"

#include "llvm/CodeGen/MachineBasicBlock.h"

#include "llvm/CodeGen/MachineInstr.h"

#include "llvm/MC/MCAsmInfo.h"

#include "llvm/MC/MCContext.h"

#include "llvm/MC/MCExpr.h"

#include "llvm/MC/MCInst.h"

#include "llvm/Support/ErrorHandling.h"

#include "llvm/Support/raw_ostream.h"

using namespace llvm;

MCSymbol *

BPFMCInstLower::GetGlobalAddressSymbol(const MachineOperand &MO) const {

  return Printer.getSymbol(MO.getGlobal());

}

MCSymbol *

BPFMCInstLower::GetExternalSymbolSymbol(const MachineOperand &MO) const {

  return Printer.GetExternalSymbolSymbol(MO.getSymbolName());

}

MCOperand BPFMCInstLower::LowerSymbolOperand(const MachineOperand &MO,

                                             MCSymbol *Sym) const {

  const MCExpr *Expr = MCSymbolRefExpr::create(Sym, Ctx);

  if (!MO.isJTI() && MO.getOffset())

    llvm_unreachable("unknown symbol op");

  return MCOperand::createExpr(Expr);

}

void BPFMCInstLower::Lower(const MachineInstr *MI, MCInst &OutMI) const {

  OutMI.setOpcode(MI->getOpcode());

  for (const MachineOperand &MO : MI->operands()) {

    MCOperand MCOp;

    switch (MO.getType()) {

    default:

      MI->print(errs());

      llvm_unreachable("unknown operand type");

    case MachineOperand::MO_Register:

      // Ignore all implicit register operands.

      if (MO.isImplicit())

        continue;

      MCOp = MCOperand::createReg(MO.getReg());

      break;

    case MachineOperand::MO_Immediate:

      MCOp = MCOperand::createImm(MO.getImm());

      break;

    case MachineOperand::MO_MachineBasicBlock:

      MCOp = MCOperand::createExpr(

          MCSymbolRefExpr::create(MO.getMBB()->getSymbol(), Ctx));

      break;

    case MachineOperand::MO_RegisterMask:

      continue;

    case MachineOperand::MO_ExternalSymbol:

      MCOp = LowerSymbolOperand(MO, GetExternalSymbolSymbol(MO));

      break;

    case MachineOperand::MO_GlobalAddress:

      MCOp = LowerSymbolOperand(MO, GetGlobalAddressSymbol(MO));

      break;

    }

    OutMI.addOperand(MCOp);

  }

}