//===- lib/ReaderWriter/ELF/Hexagon/HexagonRelocationHandler.cpp ---------===//
//
//                             The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "HexagonLinkingContext.h"
#include "HexagonRelocationFunctions.h"
#include "HexagonTargetHandler.h"
#include "HexagonRelocationHandler.h"
#include "llvm/Support/Endian.h"

using namespace lld;
using namespace lld::elf;
using namespace llvm::ELF;
using namespace llvm::support::endian;

#define APPLY_RELOC(result)                                                    \
  write32le(location, result | read32le(location));

static int relocBNPCREL(uint8_t *location, uint64_t P, uint64_t S, uint64_t A,
                        int32_t nBits) {
  int32_t result = (uint32_t)(((S + A) - P) >> 2);
  int32_t range = 1 << nBits;
  if (result < range && result > -range) {
    result = lld::scatterBits<int32_t>(result, FINDV4BITMASK(location));
    APPLY_RELOC(result);
    return 0;
  }
  return 1;
}

/// \brief Word32_LO: 0x00c03fff : (S + A) : Truncate
static int relocLO16(uint8_t *location, uint64_t P, uint64_t S, uint64_t A) {
  uint32_t result = (uint32_t)(S + A);
  result = lld::scatterBits<int32_t>(result, 0x00c03fff);
  APPLY_RELOC(result);
  return 0;
}

/// \brief Word32_LO: 0x00c03fff : (S + A) >> 16 : Truncate
static int relocHI16(uint8_t *location, uint64_t P, uint64_t S, uint64_t A) {
  uint32_t result = (uint32_t)((S + A) >> 16);
  result = lld::scatterBits<int32_t>(result, 0x00c03fff);
  APPLY_RELOC(result);
  return 0;
}

/// \brief Word32: 0xffffffff : (S + A) : Truncate
static int reloc32(uint8_t *location, uint64_t P, uint64_t S, uint64_t A) {
  uint32_t result = (uint32_t)(S + A);
  APPLY_RELOC(result);
  return 0;
}

static int reloc32_6_X(uint8_t *location, uint64_t P, uint64_t S, uint64_t A) {
  int64_t result = ((S + A) >> 6);
  int64_t range = ((int64_t)1) << 32;
  if (result > range)
    return 1;
  result = lld::scatterBits<int32_t>(result, 0xfff3fff);
  APPLY_RELOC(result);
  return 0;
}

// R_HEX_B32_PCREL_X
static int relocHexB32PCRELX(uint8_t *location, uint64_t P, uint64_t S,
                             uint64_t A) {
  int64_t result = ((S + A - P) >> 6);
  result = lld::scatterBits<int32_t>(result, 0xfff3fff);
  APPLY_RELOC(result);
  return 0;
}

// R_HEX_BN_PCREL_X
static int relocHexBNPCRELX(uint8_t *location, uint64_t P, uint64_t S,
                            uint64_t A, int nbits) {
  int32_t result = ((S + A - P) & 0x3f);
  int32_t range = 1 << nbits;
  if (result < range && result > -range) {
    result = lld::scatterBits<int32_t>(result, FINDV4BITMASK(location));
    APPLY_RELOC(result);
    return 0;
  }
  return 1;
}

// R_HEX_6_PCREL_X
static int relocHex6PCRELX(uint8_t *location, uint64_t P, uint64_t S,
                           uint64_t A) {
  int32_t result = (S + A - P);
  result = lld::scatterBits<int32_t>(result, FINDV4BITMASK(location));
  APPLY_RELOC(result);
  return 0;
}

// R_HEX_N_X : Word32_U6 : (S + A) : Unsigned Truncate
static int relocHex_N_X(uint8_t *location, uint64_t P, uint64_t S, uint64_t A) {
  uint32_t result = (S + A);
  result = lld::scatterBits<uint32_t>(result, FINDV4BITMASK(location));
  APPLY_RELOC(result);
  return 0;
}

// GP REL relocations
static int relocHexGPRELN(uint8_t *location, uint64_t P, uint64_t S, uint64_t A,
                          uint64_t GP, int nShiftBits) {
  int32_t result = (int64_t)((S + A - GP) >> nShiftBits);
  int32_t range = 1L << 16;
  if (result <= range) {
    result = lld::scatterBits<uint32_t>(result, FINDV4BITMASK(location));
    APPLY_RELOC(result);
    return 0;
  }
  return 1;
}

/// \brief Word32_LO: 0x00c03fff : (G) : Truncate
static int relocHexGOTLO16(uint8_t *location, uint64_t A, uint64_t GOT) {
  int32_t result = (int32_t)(A-GOT);
  result = lld::scatterBits<int32_t>(result, 0x00c03fff);
  APPLY_RELOC(result);
  return 0;
}

/// \brief Word32_LO: 0x00c03fff : (G) >> 16 : Truncate
static int relocHexGOTHI16(uint8_t *location, uint64_t A, uint64_t GOT) {
  int32_t result = (int32_t)((A-GOT) >> 16);
  result = lld::scatterBits<int32_t>(result, 0x00c03fff);
  APPLY_RELOC(result);
  return 0;
}

/// \brief Word32: 0xffffffff : (G) : Truncate
static int relocHexGOT32(uint8_t *location, uint64_t A, uint64_t GOT) {
  int32_t result = (int32_t)(GOT - A);
  APPLY_RELOC(result);
  return 0;
}

/// \brief Word32_U16 : (G) : Truncate
static int relocHexGOT16(uint8_t *location, uint64_t A, uint64_t GOT) {
  int32_t result = (int32_t)(GOT-A);
  int32_t range = 1L << 16;
  if (result <= range) {
    result = lld::scatterBits<int32_t>(result, FINDV4BITMASK(location));
    APPLY_RELOC(result);
    return 0;
  }
  return 1;
}

static int relocHexGOT32_6_X(uint8_t *location, uint64_t A, uint64_t GOT) {
  int32_t result = (int32_t)((A-GOT) >> 6);
  result = lld::scatterBits<int32_t>(result, FINDV4BITMASK(location));
  APPLY_RELOC(result);
  return 0;
}

static int relocHexGOT16_X(uint8_t *location, uint64_t A, uint64_t GOT) {
  int32_t result = (int32_t)(A-GOT);
  int32_t range = 1L << 6;
  if (result <= range) {
    result = lld::scatterBits<int32_t>(result, FINDV4BITMASK(location));
    APPLY_RELOC(result);
    return 0;
  }
  return 1;
}

static int relocHexGOT11_X(uint8_t *location, uint64_t A, uint64_t GOT) {
  uint32_t result = (uint32_t)(A-GOT);
  result = lld::scatterBits<uint32_t>(result, FINDV4BITMASK(location));
  APPLY_RELOC(result);
  return 0;
}

static int relocHexGOTRELSigned(uint8_t *location, uint64_t P, uint64_t S,
                                uint64_t A, uint64_t GOT, int shiftBits = 0) {
  int32_t result = (int32_t)((S + A - GOT) >> shiftBits);
  result = lld::scatterBits<int32_t>(result, FINDV4BITMASK(location));
  APPLY_RELOC(result);
  return 0;
}

static int relocHexGOTRELUnsigned(uint8_t *location, uint64_t P, uint64_t S,
                                  uint64_t A, uint64_t GOT, int shiftBits = 0) {
  uint32_t result = (uint32_t)((S + A - GOT) >> shiftBits);
  result = lld::scatterBits<uint32_t>(result, FINDV4BITMASK(location));
  APPLY_RELOC(result);
  return 0;
}

static int relocHexGOTREL_HILO16(uint8_t *location, uint64_t P, uint64_t S,
                                 uint64_t A, uint64_t GOT, int shiftBits = 0) {
  int32_t result = (int32_t)((S + A - GOT) >> shiftBits);
  result = lld::scatterBits<int32_t>(result, 0x00c03fff);
  APPLY_RELOC(result);
  return 0;
}

static int relocHexGOTREL_32(uint8_t *location, uint64_t P, uint64_t S,
                             uint64_t A, uint64_t GOT) {
  int32_t result = (int32_t)(S + A - GOT);
  APPLY_RELOC(result);
  return 0;
}

std::error_code HexagonTargetRelocationHandler::applyRelocation(
    ELFWriter &writer, llvm::FileOutputBuffer &buf, const lld::AtomLayout &atom,
    const Reference &ref) const {
  uint8_t *atomContent = buf.getBufferStart() + atom._fileOffset;
  uint8_t *location = atomContent + ref.offsetInAtom();
  uint64_t targetVAddress = writer.addressOfAtom(ref.target());
  uint64_t relocVAddress = atom._virtualAddr + ref.offsetInAtom();

  if (ref.kindNamespace() != Reference::KindNamespace::ELF)
    return std::error_code();
  assert(ref.kindArch() == Reference::KindArch::Hexagon);
  switch (ref.kindValue()) {
  case R_HEX_B22_PCREL:
    relocBNPCREL(location, relocVAddress, targetVAddress, ref.addend(), 21);
    break;
  case R_HEX_B15_PCREL:
    relocBNPCREL(location, relocVAddress, targetVAddress, ref.addend(), 14);
    break;
  case R_HEX_B9_PCREL:
    relocBNPCREL(location, relocVAddress, targetVAddress, ref.addend(), 8);
    break;
  case R_HEX_LO16:
    relocLO16(location, relocVAddress, targetVAddress, ref.addend());
    break;
  case R_HEX_HI16:
    relocHI16(location, relocVAddress, targetVAddress, ref.addend());
    break;
  case R_HEX_32:
    reloc32(location, relocVAddress, targetVAddress, ref.addend());
    break;
  case R_HEX_32_6_X:
    reloc32_6_X(location, relocVAddress, targetVAddress, ref.addend());
    break;
  case R_HEX_B32_PCREL_X:
    relocHexB32PCRELX(location, relocVAddress, targetVAddress, ref.addend());
    break;
  case R_HEX_B22_PCREL_X:
    relocHexBNPCRELX(location, relocVAddress, targetVAddress, ref.addend(), 21);
    break;
  case R_HEX_B15_PCREL_X:
    relocHexBNPCRELX(location, relocVAddress, targetVAddress, ref.addend(), 14);
    break;
  case R_HEX_B13_PCREL_X:
    relocHexBNPCRELX(location, relocVAddress, targetVAddress, ref.addend(), 12);
    break;
  case R_HEX_B9_PCREL_X:
    relocHexBNPCRELX(location, relocVAddress, targetVAddress, ref.addend(), 8);
    break;
  case R_HEX_B7_PCREL_X:
    relocHexBNPCRELX(location, relocVAddress, targetVAddress, ref.addend(), 6);
    break;
  case R_HEX_GPREL16_0:
    relocHexGPRELN(location, relocVAddress, targetVAddress, ref.addend(),
                   _hexagonTargetLayout.getSDataSection()->virtualAddr(), 0);
    break;
  case R_HEX_GPREL16_1:
    relocHexGPRELN(location, relocVAddress, targetVAddress, ref.addend(),
                   _hexagonTargetLayout.getSDataSection()->virtualAddr(), 1);
    break;
  case R_HEX_GPREL16_2:
    relocHexGPRELN(location, relocVAddress, targetVAddress, ref.addend(),
                   _hexagonTargetLayout.getSDataSection()->virtualAddr(), 2);
    break;
  case R_HEX_GPREL16_3:
    relocHexGPRELN(location, relocVAddress, targetVAddress, ref.addend(),
                   _hexagonTargetLayout.getSDataSection()->virtualAddr(), 3);
    break;
  case R_HEX_16_X:
  case R_HEX_12_X:
  case R_HEX_11_X:
  case R_HEX_10_X:
  case R_HEX_9_X:
  case R_HEX_8_X:
  case R_HEX_7_X:
  case R_HEX_6_X:
    relocHex_N_X(location, relocVAddress, targetVAddress, ref.addend());
    break;
  case R_HEX_6_PCREL_X:
    relocHex6PCRELX(location, relocVAddress, targetVAddress, ref.addend());
    break;
  case R_HEX_JMP_SLOT:
  case R_HEX_GLOB_DAT:
    break;
  case R_HEX_GOTREL_32:
    relocHexGOTREL_32(location, relocVAddress, targetVAddress, ref.addend(),
                      _hexagonTargetLayout.getGOTSymAddr());
    break;
  case R_HEX_GOTREL_LO16:
    relocHexGOTREL_HILO16(location, relocVAddress, targetVAddress, ref.addend(),
                          _hexagonTargetLayout.getGOTSymAddr());
    break;
  case R_HEX_GOTREL_HI16:
    relocHexGOTREL_HILO16(location, relocVAddress, targetVAddress, ref.addend(),
                          _hexagonTargetLayout.getGOTSymAddr(), 16);
    break;
  case R_HEX_GOT_LO16:
    relocHexGOTLO16(location, targetVAddress,
                    _hexagonTargetLayout.getGOTSymAddr());
    break;
  case R_HEX_GOT_HI16:
    relocHexGOTHI16(location, targetVAddress,
                    _hexagonTargetLayout.getGOTSymAddr());
    break;
  case R_HEX_GOT_32:
    relocHexGOT32(location, targetVAddress,
                  _hexagonTargetLayout.getGOTSymAddr());
    break;
  case R_HEX_GOT_16:
    relocHexGOT16(location, targetVAddress,
                  _hexagonTargetLayout.getGOTSymAddr());
    break;
  case R_HEX_GOT_32_6_X:
    relocHexGOT32_6_X(location, targetVAddress,
                      _hexagonTargetLayout.getGOTSymAddr());
    break;
  case R_HEX_GOT_16_X:
    relocHexGOT16_X(location, targetVAddress,
                    _hexagonTargetLayout.getGOTSymAddr());
    break;
  case R_HEX_GOT_11_X:
    relocHexGOT11_X(location, targetVAddress,
                    _hexagonTargetLayout.getGOTSymAddr());
    break;
  case R_HEX_GOTREL_32_6_X:
    relocHexGOTRELSigned(location, relocVAddress, targetVAddress, ref.addend(),
                         _hexagonTargetLayout.getGOTSymAddr(), 6);
    break;
  case R_HEX_GOTREL_16_X:
  case R_HEX_GOTREL_11_X:
    relocHexGOTRELUnsigned(location, relocVAddress, targetVAddress,
                           ref.addend(), _hexagonTargetLayout.getGOTSymAddr());
    break;

  default:
    return make_unhandled_reloc_error();
  }

  return std::error_code();
}