Target/Hexagon/HexagonRelocator.cpp

//===- HexagonRelocator.cpp -----------------------------------------------===//
//
//                     The MCLinker Project
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "HexagonRelocator.h"
#include "HexagonRelocationFunctions.h"
#include "HexagonEncodings.h"

#include "mcld/LD/ELFFileFormat.h"
#include "mcld/LD/LDSymbol.h"
#include "mcld/Support/MsgHandling.h"

#include <llvm/ADT/Twine.h>
#include <llvm/Support/DataTypes.h>
#include <llvm/Support/ELF.h>

namespace mcld {

//===--------------------------------------------------------------------===//
// Relocation Helper Functions
//===--------------------------------------------------------------------===//
/// helper_DynRel - Get an relocation entry in .rela.dyn
static Relocation& helper_DynRel_init(ResolveInfo* pSym,
                                      Fragment& pFrag,
                                      uint64_t pOffset,
                                      Relocator::Type pType,
                                      HexagonRelocator& pParent) {
  HexagonLDBackend& ld_backend = pParent.getTarget();
  Relocation& rela_entry = *ld_backend.getRelaDyn().create();
  rela_entry.setType(pType);
  rela_entry.targetRef().assign(pFrag, pOffset);
  if (pType == llvm::ELF::R_HEX_RELATIVE || pSym == NULL)
    rela_entry.setSymInfo(0);
  else
    rela_entry.setSymInfo(pSym);

  return rela_entry;
}

/// helper_use_relative_reloc - Check if symbol can use relocation
/// R_HEX_RELATIVE
static bool helper_use_relative_reloc(const ResolveInfo& pSym,
                                      const HexagonRelocator& pFactory) {
  // if symbol is dynamic or undefine or preemptible
  if (pSym.isDyn() || pSym.isUndef() ||
      pFactory.getTarget().isSymbolPreemptible(pSym))
    return false;
  return true;
}

static HexagonGOTEntry& helper_GOT_init(Relocation& pReloc,
                                        bool pHasRel,
                                        HexagonRelocator& pParent) {
  // rsym - The relocation target symbol
  ResolveInfo* rsym = pReloc.symInfo();
  HexagonLDBackend& ld_backend = pParent.getTarget();
  assert(pParent.getSymGOTMap().lookUp(*rsym) == NULL);

  HexagonGOTEntry* got_entry = ld_backend.getGOT().create();
  pParent.getSymGOTMap().record(*rsym, *got_entry);

  if (!pHasRel) {
    // No corresponding dynamic relocation, initialize to the symbol value.
    got_entry->setValue(HexagonRelocator::SymVal);
  } else {
    // Initialize got_entry content and the corresponding dynamic relocation.
    if (helper_use_relative_reloc(*rsym, pParent)) {
      helper_DynRel_init(
          rsym, *got_entry, 0x0, llvm::ELF::R_HEX_RELATIVE, pParent);
      got_entry->setValue(HexagonRelocator::SymVal);
    } else {
      helper_DynRel_init(
          rsym, *got_entry, 0x0, llvm::ELF::R_HEX_GLOB_DAT, pParent);
      got_entry->setValue(0);
    }
  }
  return *got_entry;
}

static Relocator::Address helper_get_GOT_address(ResolveInfo& pSym,
                                                 HexagonRelocator& pParent) {
  HexagonGOTEntry* got_entry = pParent.getSymGOTMap().lookUp(pSym);
  assert(got_entry != NULL);
  return pParent.getTarget().getGOT().addr() + got_entry->getOffset();
}

static PLTEntryBase& helper_PLT_init(Relocation& pReloc,
                                     HexagonRelocator& pParent) {
  // rsym - The relocation target symbol
  ResolveInfo* rsym = pReloc.symInfo();
  HexagonLDBackend& ld_backend = pParent.getTarget();
  assert(pParent.getSymPLTMap().lookUp(*rsym) == NULL);

  PLTEntryBase* plt_entry = ld_backend.getPLT().create();
  pParent.getSymPLTMap().record(*rsym, *plt_entry);

  assert(pParent.getSymGOTPLTMap().lookUp(*rsym) == NULL &&
         "PLT entry not exist, but DynRel entry exist!");
  HexagonGOTEntry* gotplt_entry = ld_backend.getGOTPLT().create();
  pParent.getSymGOTPLTMap().record(*rsym, *gotplt_entry);
  // init the corresponding rel entry in .rela.plt
  Relocation& rela_entry = *ld_backend.getRelaPLT().create();
  rela_entry.setType(llvm::ELF::R_HEX_JMP_SLOT);
  rela_entry.targetRef().assign(*gotplt_entry);
  rela_entry.setSymInfo(rsym);

  return *plt_entry;
}

static Relocator::Address helper_get_PLT_address(ResolveInfo& pSym,
                                                 HexagonRelocator& pParent) {
  PLTEntryBase* plt_entry = pParent.getSymPLTMap().lookUp(pSym);
  assert(plt_entry != NULL);
  return pParent.getTarget().getPLT().addr() + plt_entry->getOffset();
}

//===--------------------------------------------------------------------===//
// Relocation Functions and Tables
//===--------------------------------------------------------------------===//
DECL_HEXAGON_APPLY_RELOC_FUNCS

/// the prototype of applying function
typedef Relocator::Result (*ApplyFunctionType)(Relocation& pReloc,
                                               HexagonRelocator& pParent);

// the table entry of applying functions
struct ApplyFunctionTriple {
  ApplyFunctionType func;
  unsigned int type;
  const char* name;
};

// declare the table of applying functions
static const ApplyFunctionTriple ApplyFunctions[] = {
    DECL_HEXAGON_APPLY_RELOC_FUNC_PTRS};

static uint32_t findBitMask(uint32_t insn,
                            Instruction* encodings,
                            int32_t numInsns) {
  for (int32_t i = 0; i < numInsns; ++i) {
    if (((insn & 0xc000) == 0) && !(encodings[i].isDuplex))
      continue;

    if (((insn & 0xc000) != 0) && (encodings[i].isDuplex))
      continue;

    if (((encodings[i].insnMask) & insn) == encodings[i].insnCmpMask)
      return encodings[i].insnBitMask;
  }
  assert(0);
  // Should not be here, but add a return for -Werror=return-type
  // error: control reaches end of non-void function
  return -1;
}

#define FINDBITMASK(INSN)     \
  findBitMask((uint32_t)INSN, \
              insn_encodings, \
              sizeof(insn_encodings) / sizeof(Instruction))

//===--------------------------------------------------------------------===//
// HexagonRelocator
//===--------------------------------------------------------------------===//
HexagonRelocator::HexagonRelocator(HexagonLDBackend& pParent,
                                   const LinkerConfig& pConfig)
    : Relocator(pConfig), m_Target(pParent) {
}

HexagonRelocator::~HexagonRelocator() {
}

Relocator::Result HexagonRelocator::applyRelocation(Relocation& pRelocation) {
  Relocation::Type type = pRelocation.type();

  if (type > 85) {  // 86-255 relocs do not exists for Hexagon
    return Relocator::Unknown;
  }

  // apply the relocation
  return ApplyFunctions[type].func(pRelocation, *this);
}

const char* HexagonRelocator::getName(Relocation::Type pType) const {
  return ApplyFunctions[pType].name;
}

Relocator::Size HexagonRelocator::getSize(Relocation::Type pType) const {
  return 32;
}

void HexagonRelocator::scanRelocation(Relocation& pReloc,
                                      IRBuilder& pLinker,
                                      Module& pModule,
                                      LDSection& pSection,
                                      Input& pInput) {
  if (LinkerConfig::Object == config().codeGenType())
    return;

  // rsym - The relocation target symbol
  ResolveInfo* rsym = pReloc.symInfo();
  assert(rsym != NULL &&
         "ResolveInfo of relocation not set while scanRelocation");

  if (config().isCodeStatic())
    return;

  assert(pSection.getLink() != NULL);
  if ((pSection.getLink()->flag() & llvm::ELF::SHF_ALLOC) == 0)
    return;

  if (rsym->isLocal())  // rsym is local
    scanLocalReloc(pReloc, pLinker, pModule, pSection);
  else  // rsym is external
    scanGlobalReloc(pReloc, pLinker, pModule, pSection);

  // check if we should issue undefined reference for the relocation target
  // symbol
  if (rsym->isUndef() && !rsym->isDyn() && !rsym->isWeak() && !rsym->isNull())
    issueUndefRef(pReloc, pSection, pInput);
}

void HexagonRelocator::addCopyReloc(ResolveInfo& pSym,
                                    HexagonLDBackend& pTarget) {
  Relocation& rel_entry = *pTarget.getRelaDyn().create();
  rel_entry.setType(pTarget.getCopyRelType());
  assert(pSym.outSymbol()->hasFragRef());
  rel_entry.targetRef().assign(*pSym.outSymbol()->fragRef());
  rel_entry.setSymInfo(&pSym);
}

void HexagonRelocator::scanLocalReloc(Relocation& pReloc,
                                      IRBuilder& pBuilder,
                                      Module& pModule,
                                      LDSection& pSection) {
  // rsym - The relocation target symbol
  ResolveInfo* rsym = pReloc.symInfo();

  switch (pReloc.type()) {
    case llvm::ELF::R_HEX_LO16:
    case llvm::ELF::R_HEX_HI16:
    case llvm::ELF::R_HEX_16:
    case llvm::ELF::R_HEX_8:
    case llvm::ELF::R_HEX_32_6_X:
    case llvm::ELF::R_HEX_16_X:
    case llvm::ELF::R_HEX_12_X:
    case llvm::ELF::R_HEX_11_X:
    case llvm::ELF::R_HEX_10_X:
    case llvm::ELF::R_HEX_9_X:
    case llvm::ELF::R_HEX_8_X:
    case llvm::ELF::R_HEX_7_X:
    case llvm::ELF::R_HEX_6_X:
      assert(!(rsym->reserved() & ReserveRel) &&
             "Cannot apply this relocation for read only section");
      return;

    case llvm::ELF::R_HEX_32:
      // If buiding PIC object (shared library or PIC executable),
      // a dynamic relocations with RELATIVE type to this location is needed.
      // Reserve an entry in .rel.dyn
      if (config().isCodeIndep()) {
        Relocation& reloc = helper_DynRel_init(rsym,
                                               *pReloc.targetRef().frag(),
                                               pReloc.targetRef().offset(),
                                               llvm::ELF::R_HEX_RELATIVE,
                                               *this);
        // we need to set up the relocation addend at apply relocation, record
        // the
        // relocation
        getRelRelMap().record(pReloc, reloc);

        // set Rel bit
        rsym->setReserved(rsym->reserved() | ReserveRel);
        getTarget().checkAndSetHasTextRel(*pSection.getLink());
      }
      return;

    default:
      return;
  }
}

void HexagonRelocator::scanGlobalReloc(Relocation& pReloc,
                                       IRBuilder& pBuilder,
                                       Module& pModule,
                                       LDSection& pSection) {
  // rsym - The relocation target symbol
  ResolveInfo* rsym = pReloc.symInfo();
  HexagonLDBackend& ld_backend = getTarget();

  switch (pReloc.type()) {
    case llvm::ELF::R_HEX_LO16:
    case llvm::ELF::R_HEX_HI16:
    case llvm::ELF::R_HEX_16:
    case llvm::ELF::R_HEX_8:
    case llvm::ELF::R_HEX_32_6_X:
    case llvm::ELF::R_HEX_16_X:
    case llvm::ELF::R_HEX_12_X:
    case llvm::ELF::R_HEX_11_X:
    case llvm::ELF::R_HEX_10_X:
    case llvm::ELF::R_HEX_9_X:
    case llvm::ELF::R_HEX_8_X:
    case llvm::ELF::R_HEX_7_X:
    case llvm::ELF::R_HEX_6_X:
      assert(!(rsym->reserved() & ReserveRel) &&
             "Cannot apply this relocation for read only section");
      return;

    case llvm::ELF::R_HEX_32:
      if (ld_backend.symbolNeedsPLT(*rsym)) {
        // create PLT for this symbol if it does not have.
        if (!(rsym->reserved() & ReservePLT)) {
          helper_PLT_init(pReloc, *this);
          rsym->setReserved(rsym->reserved() | ReservePLT);
        }
      }

      if (ld_backend.symbolNeedsDynRel(
              *rsym, (rsym->reserved() & ReservePLT), true)) {
        if (ld_backend.symbolNeedsCopyReloc(pReloc, *rsym)) {
          LDSymbol& cpy_sym =
              defineSymbolforCopyReloc(pBuilder, *rsym, ld_backend);
          addCopyReloc(*cpy_sym.resolveInfo(), ld_backend);
        } else {
          Relocation& reloc = helper_DynRel_init(rsym,
                                                 *pReloc.targetRef().frag(),
                                                 pReloc.targetRef().offset(),
                                                 llvm::ELF::R_HEX_RELATIVE,
                                                 *this);
          // we need to set up the relocation addend at apply relocation, record
          // the
          // relocation
          getRelRelMap().record(pReloc, reloc);
          rsym->setReserved(rsym->reserved() | ReserveRel);
          ld_backend.checkAndSetHasTextRel(*pSection.getLink());
        }
      }
      return;

    case llvm::ELF::R_HEX_GOTREL_LO16:
    case llvm::ELF::R_HEX_GOTREL_HI16:
    case llvm::ELF::R_HEX_GOTREL_32:
    case llvm::ELF::R_HEX_GOTREL_32_6_X:
    case llvm::ELF::R_HEX_GOTREL_16_X:
    case llvm::ELF::R_HEX_GOTREL_11_X:
      // This assumes that GOT exists
      return;

    case llvm::ELF::R_HEX_GOT_LO16:
    case llvm::ELF::R_HEX_GOT_HI16:
    case llvm::ELF::R_HEX_GOT_32:
    case llvm::ELF::R_HEX_GOT_16:
    case llvm::ELF::R_HEX_GOT_32_6_X:
    case llvm::ELF::R_HEX_GOT_16_X:
    case llvm::ELF::R_HEX_GOT_11_X:
      // Symbol needs GOT entry, reserve entry in .got
      // return if we already create GOT for this symbol
      if (rsym->reserved() & ReserveGOT)
        return;
      // If the GOT is used in statically linked binaries,
      // the GOT entry is enough and no relocation is needed.
      if (config().isCodeStatic())
        helper_GOT_init(pReloc, false, *this);
      else
        helper_GOT_init(pReloc, true, *this);
      // set GOT bit
      rsym->setReserved(rsym->reserved() | ReserveGOT);
      return;

    case llvm::ELF::R_HEX_B22_PCREL:
    case llvm::ELF::R_HEX_B15_PCREL:
    case llvm::ELF::R_HEX_B7_PCREL:
    case llvm::ELF::R_HEX_B13_PCREL:
    case llvm::ELF::R_HEX_B9_PCREL:
    case llvm::ELF::R_HEX_B32_PCREL_X:
    case llvm::ELF::R_HEX_B22_PCREL_X:
    case llvm::ELF::R_HEX_B15_PCREL_X:
    case llvm::ELF::R_HEX_B13_PCREL_X:
    case llvm::ELF::R_HEX_B9_PCREL_X:
    case llvm::ELF::R_HEX_B7_PCREL_X:
    case llvm::ELF::R_HEX_32_PCREL:
    case llvm::ELF::R_HEX_6_PCREL_X:
    case llvm::ELF::R_HEX_PLT_B22_PCREL:
      if (rsym->reserved() & ReservePLT)
        return;
      if (ld_backend.symbolNeedsPLT(*rsym) ||
          pReloc.type() == llvm::ELF::R_HEX_PLT_B22_PCREL) {
        helper_PLT_init(pReloc, *this);
        rsym->setReserved(rsym->reserved() | ReservePLT);
      }
      return;

    default:
      break;
  }  // end of switch
}

/// defineSymbolforCopyReloc
/// For a symbol needing copy relocation, define a copy symbol in the BSS
/// section and all other reference to this symbol should refer to this
/// copy.
/// @note This is executed at `scan relocation' stage.
LDSymbol& HexagonRelocator::defineSymbolforCopyReloc(
    IRBuilder& pBuilder,
    const ResolveInfo& pSym,
    HexagonLDBackend& pTarget) {
  // get or create corresponding BSS LDSection
  LDSection* bss_sect_hdr = NULL;
  ELFFileFormat* file_format = pTarget.getOutputFormat();
  if (ResolveInfo::ThreadLocal == pSym.type())
    bss_sect_hdr = &file_format->getTBSS();
  else
    bss_sect_hdr = &file_format->getBSS();

  // get or create corresponding BSS SectionData
  assert(bss_sect_hdr != NULL);
  SectionData* bss_section = NULL;
  if (bss_sect_hdr->hasSectionData())
    bss_section = bss_sect_hdr->getSectionData();
  else
    bss_section = IRBuilder::CreateSectionData(*bss_sect_hdr);

  // Determine the alignment by the symbol value
  // FIXME: here we use the largest alignment
  uint32_t addralign = config().targets().bitclass() / 8;

  // allocate space in BSS for the copy symbol
  Fragment* frag = new FillFragment(0x0, 1, pSym.size());
  uint64_t size = ObjectBuilder::AppendFragment(*frag, *bss_section, addralign);
  bss_sect_hdr->setSize(bss_sect_hdr->size() + size);

  // change symbol binding to Global if it's a weak symbol
  ResolveInfo::Binding binding = (ResolveInfo::Binding)pSym.binding();
  if (binding == ResolveInfo::Weak)
    binding = ResolveInfo::Global;

  // Define the copy symbol in the bss section and resolve it
  LDSymbol* cpy_sym = pBuilder.AddSymbol<IRBuilder::Force, IRBuilder::Resolve>(
      pSym.name(),
      (ResolveInfo::Type)pSym.type(),
      ResolveInfo::Define,
      binding,
      pSym.size(),  // size
      0x0,          // value
      FragmentRef::Create(*frag, 0x0),
      (ResolveInfo::Visibility)pSym.other());

  // output all other alias symbols if any
  Module& pModule = pBuilder.getModule();
  Module::AliasList* alias_list = pModule.getAliasList(pSym);
  if (alias_list != NULL) {
    Module::alias_iterator it, it_e = alias_list->end();
    for (it = alias_list->begin(); it != it_e; ++it) {
      const ResolveInfo* alias = *it;
      if (alias != &pSym && alias->isDyn()) {
        pBuilder.AddSymbol<IRBuilder::Force, IRBuilder::Resolve>(
            alias->name(),
            (ResolveInfo::Type)alias->type(),
            ResolveInfo::Define,
            binding,
            alias->size(),  // size
            0x0,            // value
            FragmentRef::Create(*frag, 0x0),
            (ResolveInfo::Visibility)alias->other());
      }
    }
  }

  return *cpy_sym;
}

void HexagonRelocator::partialScanRelocation(Relocation& pReloc,
                                             Module& pModule) {
  pReloc.updateAddend();
  // if we meet a section symbol
  if (pReloc.symInfo()->type() == ResolveInfo::Section) {
    LDSymbol* input_sym = pReloc.symInfo()->outSymbol();

    // 1. update the relocation target offset
    assert(input_sym->hasFragRef());
    // 2. get the output LDSection which the symbol defined in
    const LDSection& out_sect =
        input_sym->fragRef()->frag()->getParent()->getSection();
    ResolveInfo* sym_info =
        pModule.getSectionSymbolSet().get(out_sect)->resolveInfo();
    // set relocation target symbol to the output section symbol's resolveInfo
    pReloc.setSymInfo(sym_info);
  }
}

//=========================================//
// Each relocation function implementation //
//=========================================//

// R_HEX_NONE
Relocator::Result none(Relocation& pReloc, HexagonRelocator& pParent) {
  return Relocator::OK;
}

// R_HEX_32 and its class of relocations use only addend and symbol value
// S + A : result is unsigned truncate.
// Exception: R_HEX_32_6_X : unsigned verify
Relocator::Result applyAbs(Relocation& pReloc) {
  Relocator::Address S = pReloc.symValue();
  Relocator::DWord A = pReloc.addend();
  uint32_t result = (uint32_t)(S + A);
  uint32_t bitMask = 0;
  uint32_t effectiveBits = 0;
  uint32_t alignment = 1;
  uint32_t shift = 0;

  switch (pReloc.type()) {
    case llvm::ELF::R_HEX_LO16:
      bitMask = 0x00c03fff;
      break;

    case llvm::ELF::R_HEX_HI16:
      shift = 16;
      bitMask = 0x00c03fff;
      break;

    case llvm::ELF::R_HEX_32:
      bitMask = 0xffffffff;
      break;

    case llvm::ELF::R_HEX_16:
      bitMask = 0x0000ffff;
      alignment = 2;
      break;

    case llvm::ELF::R_HEX_8:
      bitMask = 0x000000ff;
      alignment = 1;
      break;

    case llvm::ELF::R_HEX_12_X:
      bitMask = 0x000007e0;
      break;

    case llvm::ELF::R_HEX_32_6_X:
      bitMask = 0xfff3fff;
      shift = 6;
      effectiveBits = 26;
      break;

    case llvm::ELF::R_HEX_16_X:
    case llvm::ELF::R_HEX_11_X:
    case llvm::ELF::R_HEX_10_X:
    case llvm::ELF::R_HEX_9_X:
    case llvm::ELF::R_HEX_8_X:
    case llvm::ELF::R_HEX_7_X:
    case llvm::ELF::R_HEX_6_X:
      bitMask = FINDBITMASK(pReloc.target());
      break;

    default:
      // show proper error
      fatal(diag::unsupported_relocation) << static_cast<int>(pReloc.type())
                                          << "mclinker@googlegroups.com";
  }

  if ((shift != 0) && (result % alignment != 0))
    return Relocator::BadReloc;

  result >>= shift;

  if (effectiveBits) {
    uint32_t range = 1 << effectiveBits;
    if (result > (range - 1))
      return Relocator::Overflow;
  }

  pReloc.target() |= ApplyMask<uint32_t>(bitMask, result);
  return Relocator::OK;
}

// R_HEX_B22_PCREL and its class of relocations, use
// S + A - P : result is signed verify.
// Exception: R_HEX_B32_PCREL_X : signed truncate
// Another Exception: R_HEX_6_PCREL_X is unsigned truncate
Relocator::Result applyRel(Relocation& pReloc, int64_t pResult) {
  uint32_t bitMask = 0;
  uint32_t effectiveBits = 0;
  uint32_t alignment = 1;
  uint32_t result;
  uint32_t shift = 0;

  switch (pReloc.type()) {
    case llvm::ELF::R_HEX_B22_PCREL:
      bitMask = 0x01ff3ffe;
      effectiveBits = 22;
      alignment = 4;
      shift = 2;
      break;

    case llvm::ELF::R_HEX_B15_PCREL:
      bitMask = 0x00df20fe;
      effectiveBits = 15;
      alignment = 4;
      shift = 2;
      break;

    case llvm::ELF::R_HEX_B7_PCREL:
      bitMask = 0x00001f18;
      effectiveBits = 7;
      alignment = 4;
      shift = 2;
      break;

    case llvm::ELF::R_HEX_B13_PCREL:
      bitMask = 0x00202ffe;
      effectiveBits = 13;
      alignment = 4;
      shift = 2;
      break;

    case llvm::ELF::R_HEX_B9_PCREL:
      bitMask = 0x003000fe;
      effectiveBits = 9;
      alignment = 4;
      shift = 2;
      break;

    case llvm::ELF::R_HEX_B32_PCREL_X:
      bitMask = 0xfff3fff;
      shift = 6;
      break;

    case llvm::ELF::R_HEX_B22_PCREL_X:
      bitMask = 0x01ff3ffe;
      effectiveBits = 22;
      pResult &= 0x3f;
      break;

    case llvm::ELF::R_HEX_B15_PCREL_X:
      bitMask = 0x00df20fe;
      effectiveBits = 15;
      pResult &= 0x3f;
      break;

    case llvm::ELF::R_HEX_B13_PCREL_X:
      bitMask = 0x00202ffe;
      effectiveBits = 13;
      pResult &= 0x3f;
      break;

    case llvm::ELF::R_HEX_B9_PCREL_X:
      bitMask = 0x003000fe;
      effectiveBits = 9;
      pResult &= 0x3f;
      break;

    case llvm::ELF::R_HEX_B7_PCREL_X:
      bitMask = 0x00001f18;
      effectiveBits = 7;
      pResult &= 0x3f;
      break;

    case llvm::ELF::R_HEX_32_PCREL:
      bitMask = 0xffffffff;
      effectiveBits = 32;
      break;

    case llvm::ELF::R_HEX_6_PCREL_X:
      // This is unique since it has a unsigned operand and its truncated
      bitMask = FINDBITMASK(pReloc.target());
      result = pReloc.addend() + pReloc.symValue() - pReloc.place();
      pReloc.target() |= ApplyMask<uint32_t>(bitMask, result);
      return Relocator::OK;

    default:
      // show proper error
      fatal(diag::unsupported_relocation) << static_cast<int>(pReloc.type())
                                          << "mclinker@googlegroups.com";
  }

  if ((shift != 0) && (pResult % alignment != 0))
    return Relocator::BadReloc;

  pResult >>= shift;

  if (effectiveBits) {
    int64_t range = 1LL << (effectiveBits - 1);
    if ((pResult > (range - 1)) || (pResult < -range))
      return Relocator::Overflow;
  }

  pReloc.target() |= (uint32_t)ApplyMask<int32_t>(bitMask, pResult);
  return Relocator::OK;
}

Relocator::Result relocAbs(Relocation& pReloc, HexagonRelocator& pParent) {
  ResolveInfo* rsym = pReloc.symInfo();
  Relocator::Address S = pReloc.symValue();
  Relocator::DWord A = pReloc.addend();

  Relocation* rel_entry = pParent.getRelRelMap().lookUp(pReloc);
  bool has_dyn_rel = (rel_entry != NULL);

  // if the flag of target section is not ALLOC, we eprform only static
  // relocation.
  if (0 == (llvm::ELF::SHF_ALLOC &
            pReloc.targetRef().frag()->getParent()->getSection().flag())) {
    return applyAbs(pReloc);
  }

  // a local symbol with .rela type relocation
  if (rsym->isLocal() && has_dyn_rel) {
    rel_entry->setAddend(S + A);
    return Relocator::OK;
  }

  if (!rsym->isLocal()) {
    if (rsym->reserved() & HexagonRelocator::ReservePLT) {
      S = helper_get_PLT_address(*rsym, pParent);
    }

    if (has_dyn_rel) {
      if (llvm::ELF::R_HEX_32 == pReloc.type() &&
          helper_use_relative_reloc(*rsym, pParent)) {
        rel_entry->setAddend(S + A);
      } else {
        rel_entry->setAddend(A);
        return Relocator::OK;
      }
    }
  }

  return applyAbs(pReloc);
}

Relocator::Result relocPCREL(Relocation& pReloc, HexagonRelocator& pParent) {
  ResolveInfo* rsym = pReloc.symInfo();
  int64_t result;

  Relocator::Address S = pReloc.symValue();
  Relocator::DWord A = pReloc.addend();
  Relocator::DWord P = pReloc.place();

  FragmentRef& target_fragref = pReloc.targetRef();
  Fragment* target_frag = target_fragref.frag();
  LDSection& target_sect = target_frag->getParent()->getSection();

  result = (int64_t)(S + A - P);

  // for relocs inside non ALLOC, just apply
  if ((llvm::ELF::SHF_ALLOC & target_sect.flag()) == 0) {
    return applyRel(pReloc, result);
  }

  if (!rsym->isLocal()) {
    if (rsym->reserved() & HexagonRelocator::ReservePLT) {
      S = helper_get_PLT_address(*rsym, pParent);
      result = (int64_t)(S + A - P);
      applyRel(pReloc, result);
      return Relocator::OK;
    }
  }

  return applyRel(pReloc, result);
}

// R_HEX_GPREL16_0 and its class : Unsigned Verify
Relocator::Result relocGPREL(Relocation& pReloc, HexagonRelocator& pParent) {
  Relocator::Address S = pReloc.symValue();
  Relocator::DWord A = pReloc.addend();
  Relocator::DWord GP = pParent.getTarget().getGP();

  uint32_t result = (uint32_t)(S + A - GP);
  uint32_t shift = 0;
  uint32_t alignment = 1;

  switch (pReloc.type()) {
    case llvm::ELF::R_HEX_GPREL16_0:
      break;

    case llvm::ELF::R_HEX_GPREL16_1:
      shift = 1;
      alignment = 2;
      break;

    case llvm::ELF::R_HEX_GPREL16_2:
      shift = 2;
      alignment = 4;
      break;

    case llvm::ELF::R_HEX_GPREL16_3:
      shift = 3;
      alignment = 8;
      break;

    default:
      // show proper error
      fatal(diag::unsupported_relocation) << static_cast<int>(pReloc.type())
                                          << "mclinker@googlegroups.com";
  }

  uint32_t range = 1 << 16;
  uint32_t bitMask = FINDBITMASK(pReloc.target());

  if ((shift != 0) && (result % alignment != 0))
    return Relocator::BadReloc;

  result >>= shift;

  if (result < range - 1) {
    pReloc.target() |= ApplyMask<uint32_t>(bitMask, result);
    return Relocator::OK;
  }
  return Relocator::Overflow;
}

// R_HEX_PLT_B22_PCREL: PLT(S) + A - P
Relocator::Result relocPLTB22PCREL(Relocation& pReloc,
                                   HexagonRelocator& pParent) {
  // PLT_S depends on if there is a PLT entry.
  Relocator::Address PLT_S;
  if ((pReloc.symInfo()->reserved() & HexagonRelocator::ReservePLT))
    PLT_S = helper_get_PLT_address(*pReloc.symInfo(), pParent);
  else
    PLT_S = pReloc.symValue();
  Relocator::Address P = pReloc.place();
  uint32_t bitMask = FINDBITMASK(pReloc.target());
  uint32_t result = (PLT_S + pReloc.addend() - P) >> 2;
  pReloc.target() = pReloc.target() | ApplyMask<uint32_t>(bitMask, result);
  return Relocator::OK;
}

// R_HEX_GOT_LO16 and its class : (G) Signed Truncate
// Exception: R_HEX_GOT_16(_X): signed verify
// Exception: R_HEX_GOT_11_X : unsigned truncate
Relocator::Result relocGOT(Relocation& pReloc, HexagonRelocator& pParent) {
  if (!(pReloc.symInfo()->reserved() & HexagonRelocator::ReserveGOT)) {
    return Relocator::BadReloc;
  }

  // set got entry value if needed
  HexagonGOTEntry* got_entry = pParent.getSymGOTMap().lookUp(*pReloc.symInfo());
  assert(got_entry != NULL);
  if (HexagonRelocator::SymVal == got_entry->getValue())
    got_entry->setValue(pReloc.symValue());

  Relocator::Address GOT_S = helper_get_GOT_address(*pReloc.symInfo(), pParent);
  Relocator::Address GOT = pParent.getTarget().getGOTSymbolAddr();
  int32_t result = (int32_t)(GOT_S - GOT);
  uint32_t effectiveBits = 0;
  uint32_t alignment = 1;
  uint32_t bitMask = 0;
  uint32_t result_u;
  uint32_t shift = 0;

  switch (pReloc.type()) {
    case llvm::ELF::R_HEX_GOT_LO16:
      bitMask = 0x00c03fff;
      break;

    case llvm::ELF::R_HEX_GOT_HI16:
      bitMask = 0x00c03fff;
      shift = 16;
      alignment = 4;
      break;

    case llvm::ELF::R_HEX_GOT_32:
      bitMask = 0xffffffff;
      break;

    case llvm::ELF::R_HEX_GOT_16:
      bitMask = FINDBITMASK(pReloc.target());
      effectiveBits = 16;
      break;

    case llvm::ELF::R_HEX_GOT_32_6_X:
      bitMask = 0xfff3fff;
      shift = 6;
      break;

    case llvm::ELF::R_HEX_GOT_16_X:
      bitMask = FINDBITMASK(pReloc.target());
      effectiveBits = 6;
      break;

    case llvm::ELF::R_HEX_GOT_11_X:
      bitMask = FINDBITMASK(pReloc.target());
      result_u = GOT_S - GOT;
      pReloc.target() |= ApplyMask<uint32_t>(bitMask, result_u);
      return Relocator::OK;

    default:
      // show proper error
      fatal(diag::unsupported_relocation) << static_cast<int>(pReloc.type())
                                          << "mclinker@googlegroups.com";
  }

  if ((shift != 0) && (result % alignment != 0))
    return Relocator::BadReloc;

  result >>= shift;

  if (effectiveBits) {
    int32_t range = 1 << (effectiveBits - 1);
    if ((result > range - 1) || (result < -range))
      return Relocator::Overflow;
  }
  pReloc.target() |= ApplyMask<int32_t>(bitMask, result);
  return Relocator::OK;
}

// R_HEX_GOTREL_LO16: and its class of relocs
// (S + A - GOT) : Signed Truncate
Relocator::Result relocGOTREL(Relocation& pReloc, HexagonRelocator& pParent) {
  Relocator::Address S = pReloc.symValue();
  Relocator::DWord A = pReloc.addend();
  Relocator::Address GOT = pParent.getTarget().getGOTSymbolAddr();

  uint32_t bitMask = 0;
  uint32_t alignment = 1;
  uint32_t shift = 0;

  uint32_t result = (uint32_t)(S + A - GOT);

  switch (pReloc.type()) {
    case llvm::ELF::R_HEX_GOTREL_LO16:
      bitMask = 0x00c03fff;
      break;

    case llvm::ELF::R_HEX_GOTREL_HI16:
      bitMask = 0x00c03fff;
      shift = 16;
      alignment = 4;
      break;

    case llvm::ELF::R_HEX_GOTREL_32:
      bitMask = 0xffffffff;
      break;

    case llvm::ELF::R_HEX_GOTREL_32_6_X:
      bitMask = 0x0fff3fff;
      shift = 6;
      break;

    case llvm::ELF::R_HEX_GOTREL_16_X:
    case llvm::ELF::R_HEX_GOTREL_11_X:
      bitMask = FINDBITMASK(pReloc.target());
      break;

    default:
      // show proper error
      fatal(diag::unsupported_relocation) << static_cast<int>(pReloc.type())
                                          << "mclinker@googlegroups.com";
  }

  if (result % alignment != 0)
    return Relocator::BadReloc;

  result >>= shift;

  pReloc.target() |= ApplyMask<uint32_t>(bitMask, result);
  return Relocator::OK;
}

Relocator::Result unsupported(Relocation& pReloc, HexagonRelocator& pParent) {
  return Relocator::Unsupported;
}

}  // namespace mcld