//===-- SystemZMCObjectWriter.cpp - SystemZ ELF writer --------------------===//

//

//                     The LLVM Compiler Infrastructure

//

// This file is distributed under the University of Illinois Open Source

// License. See LICENSE.TXT for details.

//

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

#include "MCTargetDesc/SystemZMCTargetDesc.h"

#include "MCTargetDesc/SystemZMCFixups.h"

#include "llvm/MC/MCELFObjectWriter.h"

#include "llvm/MC/MCExpr.h"

#include "llvm/MC/MCValue.h"

using namespace llvm_ks;

namespace {

class SystemZObjectWriter : public MCELFObjectTargetWriter {

public:

  SystemZObjectWriter(uint8_t OSABI);

  ~SystemZObjectWriter() override;

protected:

  // Override MCELFObjectTargetWriter.

  unsigned getRelocType(MCContext &Ctx, const MCValue &Target,

                        const MCFixup &Fixup, bool IsPCRel) const override;

};

} // end anonymous namespace

SystemZObjectWriter::SystemZObjectWriter(uint8_t OSABI)

  : MCELFObjectTargetWriter(/*Is64Bit=*/true, OSABI, ELF::EM_S390,

                            /*HasRelocationAddend=*/ true) {}

SystemZObjectWriter::~SystemZObjectWriter() {

}

// Return the relocation type for an absolute value of MCFixupKind Kind.

static unsigned getAbsoluteReloc(unsigned Kind) {

  switch (Kind) {

  case FK_Data_1: return ELF::R_390_8;

  case FK_Data_2: return ELF::R_390_16;

  case FK_Data_4: return ELF::R_390_32;

  case FK_Data_8: return ELF::R_390_64;

  }

  llvm_unreachable("Unsupported absolute address");

}

// Return the relocation type for a PC-relative value of MCFixupKind Kind.

static unsigned getPCRelReloc(unsigned Kind) {

  switch (Kind) {

  case FK_Data_2:                return ELF::R_390_PC16;

  case FK_Data_4:                return ELF::R_390_PC32;

  case FK_Data_8:                return ELF::R_390_PC64;

  case SystemZ::FK_390_PC16DBL:  return ELF::R_390_PC16DBL;

  case SystemZ::FK_390_PC32DBL:  return ELF::R_390_PC32DBL;

  }

  llvm_unreachable("Unsupported PC-relative address");

}

// Return the R_390_TLS_LE* relocation type for MCFixupKind Kind.

static unsigned getTLSLEReloc(unsigned Kind) {

  switch (Kind) {

  case FK_Data_4: return ELF::R_390_TLS_LE32;

  case FK_Data_8: return ELF::R_390_TLS_LE64;

  }

  llvm_unreachable("Unsupported absolute address");

}

// Return the R_390_TLS_LDO* relocation type for MCFixupKind Kind.

static unsigned getTLSLDOReloc(unsigned Kind) {

  switch (Kind) {

  case FK_Data_4: return ELF::R_390_TLS_LDO32;

  case FK_Data_8: return ELF::R_390_TLS_LDO64;

  }

  llvm_unreachable("Unsupported absolute address");

}

// Return the R_390_TLS_LDM* relocation type for MCFixupKind Kind.

static unsigned getTLSLDMReloc(unsigned Kind) {

  switch (Kind) {

  case FK_Data_4: return ELF::R_390_TLS_LDM32;

  case FK_Data_8: return ELF::R_390_TLS_LDM64;

  case SystemZ::FK_390_TLS_CALL: return ELF::R_390_TLS_LDCALL;

  }

  llvm_unreachable("Unsupported absolute address");

}

// Return the R_390_TLS_GD* relocation type for MCFixupKind Kind.

static unsigned getTLSGDReloc(unsigned Kind) {

  switch (Kind) {

  case FK_Data_4: return ELF::R_390_TLS_GD32;

  case FK_Data_8: return ELF::R_390_TLS_GD64;

  case SystemZ::FK_390_TLS_CALL: return ELF::R_390_TLS_GDCALL;

  }

  llvm_unreachable("Unsupported absolute address");

}

// Return the PLT relocation counterpart of MCFixupKind Kind.

static unsigned getPLTReloc(unsigned Kind) {

  switch (Kind) {

  case SystemZ::FK_390_PC16DBL: return ELF::R_390_PLT16DBL;

  case SystemZ::FK_390_PC32DBL: return ELF::R_390_PLT32DBL;

  }

  llvm_unreachable("Unsupported absolute address");

}

unsigned SystemZObjectWriter::getRelocType(MCContext &Ctx,

                                           const MCValue &Target,

                                           const MCFixup &Fixup,

                                           bool IsPCRel) const {

  MCSymbolRefExpr::VariantKind Modifier = Target.getAccessVariant();

  unsigned Kind = Fixup.getKind();

  switch (Modifier) {

  case MCSymbolRefExpr::VK_None:

    if (IsPCRel)

      return getPCRelReloc(Kind);

    return getAbsoluteReloc(Kind);

  case MCSymbolRefExpr::VK_NTPOFF:

    assert(!IsPCRel && "NTPOFF shouldn't be PC-relative");

    return getTLSLEReloc(Kind);

  case MCSymbolRefExpr::VK_INDNTPOFF:

    if (IsPCRel && Kind == SystemZ::FK_390_PC32DBL)

      return ELF::R_390_TLS_IEENT;

    llvm_unreachable("Only PC-relative INDNTPOFF accesses are supported for now");

  case MCSymbolRefExpr::VK_DTPOFF:

    assert(!IsPCRel && "DTPOFF shouldn't be PC-relative");

    return getTLSLDOReloc(Kind);

  case MCSymbolRefExpr::VK_TLSLDM:

    assert(!IsPCRel && "TLSLDM shouldn't be PC-relative");

    return getTLSLDMReloc(Kind);

  case MCSymbolRefExpr::VK_TLSGD:

    assert(!IsPCRel && "TLSGD shouldn't be PC-relative");

    return getTLSGDReloc(Kind);

  case MCSymbolRefExpr::VK_GOT:

    if (IsPCRel && Kind == SystemZ::FK_390_PC32DBL)

      return ELF::R_390_GOTENT;

    llvm_unreachable("Only PC-relative GOT accesses are supported for now");

  case MCSymbolRefExpr::VK_PLT:

    assert(IsPCRel && "@PLT shouldt be PC-relative");

    return getPLTReloc(Kind);

  default:

    llvm_unreachable("Modifier not supported");

  }

}

MCObjectWriter *llvm_ks::createSystemZObjectWriter(raw_pwrite_stream &OS,

                                                uint8_t OSABI) {

  MCELFObjectTargetWriter *MOTW = new SystemZObjectWriter(OSABI);

  return createELFObjectWriter(MOTW, OS, /*IsLittleEndian=*/false);

}