llvm/lib/Target/Hexagon/Disassembler/HexagonDisassembler.cpp

//===-- HexagonDisassembler.cpp - Disassembler for Hexagon ISA ------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "Hexagon.h"
#include "MCTargetDesc/HexagonBaseInfo.h"
#include "MCTargetDesc/HexagonMCInstrInfo.h"
#include "MCTargetDesc/HexagonMCTargetDesc.h"

#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCDisassembler.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCFixedLenDisassembler.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCInstrDesc.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/LEB128.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/raw_ostream.h"
#include <array>
#include <vector>

using namespace llvm;
using namespace Hexagon;

#define DEBUG_TYPE "hexagon-disassembler"

// Pull DecodeStatus and its enum values into the global namespace.
typedef llvm::MCDisassembler::DecodeStatus DecodeStatus;

namespace {
/// \brief Hexagon disassembler for all Hexagon platforms.
class HexagonDisassembler : public MCDisassembler {
public:
  std::unique_ptr<MCInst *> CurrentBundle;
  HexagonDisassembler(MCSubtargetInfo const &STI, MCContext &Ctx)
      : MCDisassembler(STI, Ctx), CurrentBundle(new MCInst *) {}

  DecodeStatus getSingleInstruction(MCInst &Instr, MCInst &MCB,
                                    ArrayRef<uint8_t> Bytes, uint64_t Address,
                                    raw_ostream &VStream, raw_ostream &CStream,
                                    bool &Complete) const;
  DecodeStatus getInstruction(MCInst &Instr, uint64_t &Size,
                              ArrayRef<uint8_t> Bytes, uint64_t Address,
                              raw_ostream &VStream,
                              raw_ostream &CStream) const override;
};
}

static DecodeStatus DecodeModRegsRegisterClass(MCInst &Inst, unsigned RegNo,
  uint64_t Address, const void *Decoder);
static DecodeStatus DecodeCtrRegsRegisterClass(MCInst &Inst, unsigned RegNo,
  uint64_t Address, const void *Decoder);
static DecodeStatus DecodeCtrRegs64RegisterClass(MCInst &Inst, unsigned RegNo,
                                   uint64_t Address, void const *Decoder);

static const uint16_t IntRegDecoderTable[] = {
  Hexagon::R0, Hexagon::R1, Hexagon::R2, Hexagon::R3, Hexagon::R4,
  Hexagon::R5, Hexagon::R6, Hexagon::R7, Hexagon::R8, Hexagon::R9,
  Hexagon::R10, Hexagon::R11, Hexagon::R12, Hexagon::R13, Hexagon::R14,
  Hexagon::R15, Hexagon::R16, Hexagon::R17, Hexagon::R18, Hexagon::R19,
  Hexagon::R20, Hexagon::R21, Hexagon::R22, Hexagon::R23, Hexagon::R24,
  Hexagon::R25, Hexagon::R26, Hexagon::R27, Hexagon::R28, Hexagon::R29,
  Hexagon::R30, Hexagon::R31 };

static const uint16_t PredRegDecoderTable[] = { Hexagon::P0, Hexagon::P1,
Hexagon::P2, Hexagon::P3 };

static DecodeStatus DecodeRegisterClass(MCInst &Inst, unsigned RegNo,
  const uint16_t Table[], size_t Size) {
  if (RegNo < Size) {
    Inst.addOperand(MCOperand::createReg(Table[RegNo]));
    return MCDisassembler::Success;
  }
  else
    return MCDisassembler::Fail;
}

static DecodeStatus DecodeIntRegsRegisterClass(MCInst &Inst, unsigned RegNo,
  uint64_t /*Address*/,
  void const *Decoder) {
  if (RegNo > 31)
    return MCDisassembler::Fail;

  unsigned Register = IntRegDecoderTable[RegNo];
  Inst.addOperand(MCOperand::createReg(Register));
  return MCDisassembler::Success;
}

static DecodeStatus DecodeCtrRegsRegisterClass(MCInst &Inst, unsigned RegNo,
  uint64_t /*Address*/, const void *Decoder) {
  static const uint16_t CtrlRegDecoderTable[] = {
    Hexagon::SA0, Hexagon::LC0, Hexagon::SA1, Hexagon::LC1,
    Hexagon::P3_0, Hexagon::NoRegister, Hexagon::C6, Hexagon::C7,
    Hexagon::USR, Hexagon::PC, Hexagon::UGP, Hexagon::GP,
    Hexagon::CS0, Hexagon::CS1, Hexagon::UPCL, Hexagon::UPCH
  };

  if (RegNo >= sizeof(CtrlRegDecoderTable) / sizeof(CtrlRegDecoderTable[0]))
    return MCDisassembler::Fail;

  if (CtrlRegDecoderTable[RegNo] == Hexagon::NoRegister)
    return MCDisassembler::Fail;

  unsigned Register = CtrlRegDecoderTable[RegNo];
  Inst.addOperand(MCOperand::createReg(Register));
  return MCDisassembler::Success;
}

static DecodeStatus DecodeCtrRegs64RegisterClass(MCInst &Inst, unsigned RegNo,
                                   uint64_t /*Address*/, void const *Decoder) {
  static const uint16_t CtrlReg64DecoderTable[] = {
    Hexagon::C1_0, Hexagon::NoRegister,
    Hexagon::C3_2, Hexagon::NoRegister,
    Hexagon::NoRegister, Hexagon::NoRegister,
    Hexagon::C7_6, Hexagon::NoRegister,
    Hexagon::C9_8, Hexagon::NoRegister,
    Hexagon::C11_10, Hexagon::NoRegister,
    Hexagon::CS, Hexagon::NoRegister,
    Hexagon::UPC, Hexagon::NoRegister
  };

  if (RegNo >= sizeof(CtrlReg64DecoderTable) / sizeof(CtrlReg64DecoderTable[0]))
    return MCDisassembler::Fail;

  if (CtrlReg64DecoderTable[RegNo] == Hexagon::NoRegister)
    return MCDisassembler::Fail;

  unsigned Register = CtrlReg64DecoderTable[RegNo];
  Inst.addOperand(MCOperand::createReg(Register));
  return MCDisassembler::Success;
}

static DecodeStatus DecodeModRegsRegisterClass(MCInst &Inst, unsigned RegNo,
  uint64_t /*Address*/, const void *Decoder) {
  unsigned Register = 0;
  switch (RegNo) {
  case 0:
    Register = Hexagon::M0;
    break;
  case 1:
    Register = Hexagon::M1;
    break;
  default:
    return MCDisassembler::Fail;
  }
  Inst.addOperand(MCOperand::createReg(Register));
  return MCDisassembler::Success;
}

static DecodeStatus DecodeDoubleRegsRegisterClass(MCInst &Inst, unsigned RegNo,
  uint64_t /*Address*/, const void *Decoder) {
  static const uint16_t DoubleRegDecoderTable[] = {
    Hexagon::D0, Hexagon::D1, Hexagon::D2, Hexagon::D3,
    Hexagon::D4, Hexagon::D5, Hexagon::D6, Hexagon::D7,
    Hexagon::D8, Hexagon::D9, Hexagon::D10, Hexagon::D11,
    Hexagon::D12, Hexagon::D13, Hexagon::D14, Hexagon::D15
  };

  return (DecodeRegisterClass(Inst, RegNo >> 1,
    DoubleRegDecoderTable,
    sizeof (DoubleRegDecoderTable)));
}

static DecodeStatus DecodePredRegsRegisterClass(MCInst &Inst, unsigned RegNo,
  uint64_t /*Address*/,
  void const *Decoder) {
  if (RegNo > 3)
    return MCDisassembler::Fail;

  unsigned Register = PredRegDecoderTable[RegNo];
  Inst.addOperand(MCOperand::createReg(Register));
  return MCDisassembler::Success;
}

#include "HexagonGenDisassemblerTables.inc"

static MCDisassembler *createHexagonDisassembler(Target const &T,
                                                 MCSubtargetInfo const &STI,
                                                 MCContext &Ctx) {
  return new HexagonDisassembler(STI, Ctx);
}

extern "C" void LLVMInitializeHexagonDisassembler() {
  TargetRegistry::RegisterMCDisassembler(TheHexagonTarget,
                                         createHexagonDisassembler);
}

DecodeStatus HexagonDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
                                                 ArrayRef<uint8_t> Bytes,
                                                 uint64_t Address,
                                                 raw_ostream &os,
                                                 raw_ostream &cs) const {
  DecodeStatus Result = DecodeStatus::Success;
  bool Complete = false;
  Size = 0;

  *CurrentBundle = &MI;
  MI.setOpcode(Hexagon::BUNDLE);
  MI.addOperand(MCOperand::createImm(0));
  while (Result == Success && Complete == false)
  {
    if (Bytes.size() < HEXAGON_INSTR_SIZE)
      return MCDisassembler::Fail;
    MCInst * Inst = new (getContext()) MCInst;
    Result = getSingleInstruction(*Inst, MI, Bytes, Address, os, cs, Complete);
    MI.addOperand(MCOperand::createInst(Inst));
    Size += HEXAGON_INSTR_SIZE;
    Bytes = Bytes.slice(HEXAGON_INSTR_SIZE);
  }
  return Result;
}

DecodeStatus HexagonDisassembler::getSingleInstruction(
    MCInst &MI, MCInst &MCB, ArrayRef<uint8_t> Bytes, uint64_t Address,
    raw_ostream &os, raw_ostream &cs, bool &Complete) const {
  assert(Bytes.size() >= HEXAGON_INSTR_SIZE);

  uint32_t Instruction =
      llvm::support::endian::read<uint32_t, llvm::support::little,
                                  llvm::support::unaligned>(Bytes.data());

  auto BundleSize = HexagonMCInstrInfo::bundleSize(MCB);
  if ((Instruction & HexagonII::INST_PARSE_MASK) ==
      HexagonII::INST_PARSE_LOOP_END) {
    if (BundleSize == 0)
      HexagonMCInstrInfo::setInnerLoop(MCB);
    else if (BundleSize == 1)
      HexagonMCInstrInfo::setOuterLoop(MCB);
    else
      return DecodeStatus::Fail;
  }

  DecodeStatus Result = DecodeStatus::Success;
  if ((Instruction & HexagonII::INST_PARSE_MASK) ==
      HexagonII::INST_PARSE_PACKET_END)
    Complete = true;
  // Calling the auto-generated decoder function.
  Result =
      decodeInstruction(DecoderTable32, MI, Instruction, Address, this, STI);

  return Result;
}