XCoreMCInstLower.cpp

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//===-- XCoreMCInstLower.cpp - Convert XCore MachineInstr to MCInst -------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// \brief This file contains code to lower XCore MachineInstrs to their
/// corresponding MCInst records.
///
//===----------------------------------------------------------------------===//
#include "XCoreMCInstLower.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/IR/Mangler.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"

using namespace llvm;

XCoreMCInstLower::XCoreMCInstLower(class AsmPrinter &asmprinter)
: Printer(asmprinter) {}

void XCoreMCInstLower::Initialize(Mangler *M, MCContext *C) {
  Mang = M;
  Ctx = C;
}

MCOperand XCoreMCInstLower::LowerSymbolOperand(const MachineOperand &MO,
                                               MachineOperandType MOTy,
                                               unsigned Offset) const {
  MCSymbolRefExpr::VariantKind Kind = MCSymbolRefExpr::VK_None;
  const MCSymbol *Symbol;

  switch (MOTy) {
    case MachineOperand::MO_MachineBasicBlock:
      Symbol = MO.getMBB()->getSymbol();
      break;
    case MachineOperand::MO_GlobalAddress:
      Symbol = Printer.getSymbol(MO.getGlobal());
      Offset += MO.getOffset();
      break;
    case MachineOperand::MO_BlockAddress:
      Symbol = Printer.GetBlockAddressSymbol(MO.getBlockAddress());
      Offset += MO.getOffset();
      break;
    case MachineOperand::MO_ExternalSymbol:
      Symbol = Printer.GetExternalSymbolSymbol(MO.getSymbolName());
      Offset += MO.getOffset();
      break;
    case MachineOperand::MO_JumpTableIndex:
      Symbol = Printer.GetJTISymbol(MO.getIndex());
      break;
    case MachineOperand::MO_ConstantPoolIndex:
      Symbol = Printer.GetCPISymbol(MO.getIndex());
      Offset += MO.getOffset();
      break;
    default:
      llvm_unreachable("<unknown operand type>");
  }

  const MCSymbolRefExpr *MCSym = MCSymbolRefExpr::Create(Symbol, Kind, *Ctx);

  if (!Offset)
    return MCOperand::CreateExpr(MCSym);

  // Assume offset is never negative.
  assert(Offset > 0);

  const MCConstantExpr *OffsetExpr =  MCConstantExpr::Create(Offset, *Ctx);
  const MCBinaryExpr *Add = MCBinaryExpr::CreateAdd(MCSym, OffsetExpr, *Ctx);
  return MCOperand::CreateExpr(Add);
}

MCOperand XCoreMCInstLower::LowerOperand(const MachineOperand &MO,
                                         unsigned offset) const {
  MachineOperandType MOTy = MO.getType();

  switch (MOTy) {
    default: llvm_unreachable("unknown operand type");
    case MachineOperand::MO_Register:
      // Ignore all implicit register operands.
      if (MO.isImplicit()) break;
      return MCOperand::CreateReg(MO.getReg());
    case MachineOperand::MO_Immediate:
      return MCOperand::CreateImm(MO.getImm() + offset);
    case MachineOperand::MO_MachineBasicBlock:
    case MachineOperand::MO_GlobalAddress:
    case MachineOperand::MO_ExternalSymbol:
    case MachineOperand::MO_JumpTableIndex:
    case MachineOperand::MO_ConstantPoolIndex:
    case MachineOperand::MO_BlockAddress:
      return LowerSymbolOperand(MO, MOTy, offset);
    case MachineOperand::MO_RegisterMask:
      break;
  }

  return MCOperand();
}

void XCoreMCInstLower::Lower(const MachineInstr *MI, MCInst &OutMI) const {
  OutMI.setOpcode(MI->getOpcode());

  for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
    const MachineOperand &MO = MI->getOperand(i);
    MCOperand MCOp = LowerOperand(MO);

    if (MCOp.isValid())
      OutMI.addOperand(MCOp);
  }
}