root/src/mips/disasm-mips.cc

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DEFINITIONS

This source file includes following definitions.
  1. out_buffer_pos_
  2. Print
  3. PrintRegister
  4. PrintRs
  5. PrintRt
  6. PrintRd
  7. PrintFPURegister
  8. PrintFs
  9. PrintFt
  10. PrintFd
  11. PrintSa
  12. PrintSd
  13. PrintSs1
  14. PrintSs2
  15. PrintBc
  16. PrintCc
  17. PrintUImm16
  18. PrintSImm16
  19. PrintXImm16
  20. PrintXImm26
  21. PrintCode
  22. PrintInstructionName
  23. FormatRegister
  24. FormatFPURegister
  25. FormatOption
  26. Format
  27. Unknown
  28. DecodeTypeRegister
  29. DecodeTypeImmediate
  30. DecodeTypeJump
  31. InstructionDecode
  32. NameOfAddress
  33. NameOfConstant
  34. NameOfCPURegister
  35. NameOfXMMRegister
  36. NameOfByteCPURegister
  37. NameInCode
  38. InstructionDecode
  39. ConstantPoolSizeAt

// Copyright 2012 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
//       copyright notice, this list of conditions and the following
//       disclaimer in the documentation and/or other materials provided
//       with the distribution.
//     * Neither the name of Google Inc. nor the names of its
//       contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// A Disassembler object is used to disassemble a block of code instruction by
// instruction. The default implementation of the NameConverter object can be
// overriden to modify register names or to do symbol lookup on addresses.
//
// The example below will disassemble a block of code and print it to stdout.
//
//   NameConverter converter;
//   Disassembler d(converter);
//   for (byte* pc = begin; pc < end;) {
//     v8::internal::EmbeddedVector<char, 256> buffer;
//     byte* prev_pc = pc;
//     pc += d.InstructionDecode(buffer, pc);
//     printf("%p    %08x      %s\n",
//            prev_pc, *reinterpret_cast<int32_t*>(prev_pc), buffer);
//   }
//
// The Disassembler class also has a convenience method to disassemble a block
// of code into a FILE*, meaning that the above functionality could also be
// achieved by just calling Disassembler::Disassemble(stdout, begin, end);


#include <assert.h>
#include <stdio.h>
#include <stdarg.h>
#include <string.h>
#ifndef WIN32
#include <stdint.h>
#endif

#include "v8.h"

#if defined(V8_TARGET_ARCH_MIPS)

#include "mips/constants-mips.h"
#include "disasm.h"
#include "macro-assembler.h"
#include "platform.h"

namespace v8 {
namespace internal {

//------------------------------------------------------------------------------

// Decoder decodes and disassembles instructions into an output buffer.
// It uses the converter to convert register names and call destinations into
// more informative description.
class Decoder {
 public:
  Decoder(const disasm::NameConverter& converter,
          v8::internal::Vector<char> out_buffer)
    : converter_(converter),
      out_buffer_(out_buffer),
      out_buffer_pos_(0) {
    out_buffer_[out_buffer_pos_] = '\0';
  }

  ~Decoder() {}

  // Writes one disassembled instruction into 'buffer' (0-terminated).
  // Returns the length of the disassembled machine instruction in bytes.
  int InstructionDecode(byte* instruction);

 private:
  // Bottleneck functions to print into the out_buffer.
  void PrintChar(const char ch);
  void Print(const char* str);

  // Printing of common values.
  void PrintRegister(int reg);
  void PrintFPURegister(int freg);
  void PrintRs(Instruction* instr);
  void PrintRt(Instruction* instr);
  void PrintRd(Instruction* instr);
  void PrintFs(Instruction* instr);
  void PrintFt(Instruction* instr);
  void PrintFd(Instruction* instr);
  void PrintSa(Instruction* instr);
  void PrintSd(Instruction* instr);
  void PrintSs1(Instruction* instr);
  void PrintSs2(Instruction* instr);
  void PrintBc(Instruction* instr);
  void PrintCc(Instruction* instr);
  void PrintFunction(Instruction* instr);
  void PrintSecondaryField(Instruction* instr);
  void PrintUImm16(Instruction* instr);
  void PrintSImm16(Instruction* instr);
  void PrintXImm16(Instruction* instr);
  void PrintXImm26(Instruction* instr);
  void PrintCode(Instruction* instr);   // For break and trap instructions.
  // Printing of instruction name.
  void PrintInstructionName(Instruction* instr);

  // Handle formatting of instructions and their options.
  int FormatRegister(Instruction* instr, const char* option);
  int FormatFPURegister(Instruction* instr, const char* option);
  int FormatOption(Instruction* instr, const char* option);
  void Format(Instruction* instr, const char* format);
  void Unknown(Instruction* instr);

  // Each of these functions decodes one particular instruction type.
  void DecodeTypeRegister(Instruction* instr);
  void DecodeTypeImmediate(Instruction* instr);
  void DecodeTypeJump(Instruction* instr);

  const disasm::NameConverter& converter_;
  v8::internal::Vector<char> out_buffer_;
  int out_buffer_pos_;

  DISALLOW_COPY_AND_ASSIGN(Decoder);
};


// Support for assertions in the Decoder formatting functions.
#define STRING_STARTS_WITH(string, compare_string) \
  (strncmp(string, compare_string, strlen(compare_string)) == 0)


// Append the ch to the output buffer.
void Decoder::PrintChar(const char ch) {
  out_buffer_[out_buffer_pos_++] = ch;
}


// Append the str to the output buffer.
void Decoder::Print(const char* str) {
  char cur = *str++;
  while (cur != '\0' && (out_buffer_pos_ < (out_buffer_.length() - 1))) {
    PrintChar(cur);
    cur = *str++;
  }
  out_buffer_[out_buffer_pos_] = 0;
}


// Print the register name according to the active name converter.
void Decoder::PrintRegister(int reg) {
  Print(converter_.NameOfCPURegister(reg));
}


void Decoder::PrintRs(Instruction* instr) {
  int reg = instr->RsValue();
  PrintRegister(reg);
}


void Decoder::PrintRt(Instruction* instr) {
  int reg = instr->RtValue();
  PrintRegister(reg);
}


void Decoder::PrintRd(Instruction* instr) {
  int reg = instr->RdValue();
  PrintRegister(reg);
}


// Print the FPUregister name according to the active name converter.
void Decoder::PrintFPURegister(int freg) {
  Print(converter_.NameOfXMMRegister(freg));
}


void Decoder::PrintFs(Instruction* instr) {
  int freg = instr->RsValue();
  PrintFPURegister(freg);
}


void Decoder::PrintFt(Instruction* instr) {
  int freg = instr->RtValue();
  PrintFPURegister(freg);
}


void Decoder::PrintFd(Instruction* instr) {
  int freg = instr->RdValue();
  PrintFPURegister(freg);
}


// Print the integer value of the sa field.
void Decoder::PrintSa(Instruction* instr) {
  int sa = instr->SaValue();
  out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_, "%d", sa);
}


// Print the integer value of the rd field, when it is not used as reg.
void Decoder::PrintSd(Instruction* instr) {
  int sd = instr->RdValue();
  out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_, "%d", sd);
}


// Print the integer value of the rd field, when used as 'ext' size.
void Decoder::PrintSs1(Instruction* instr) {
  int ss = instr->RdValue();
  out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_, "%d", ss + 1);
}


// Print the integer value of the rd field, when used as 'ins' size.
void Decoder::PrintSs2(Instruction* instr) {
  int ss = instr->RdValue();
  int pos = instr->SaValue();
  out_buffer_pos_ +=
      OS::SNPrintF(out_buffer_ + out_buffer_pos_, "%d", ss - pos + 1);
}


// Print the integer value of the cc field for the bc1t/f instructions.
void Decoder::PrintBc(Instruction* instr) {
  int cc = instr->FBccValue();
  out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_, "%d", cc);
}


// Print the integer value of the cc field for the FP compare instructions.
void Decoder::PrintCc(Instruction* instr) {
  int cc = instr->FCccValue();
  out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_, "cc(%d)", cc);
}


// Print 16-bit unsigned immediate value.
void Decoder::PrintUImm16(Instruction* instr) {
  int32_t imm = instr->Imm16Value();
  out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_, "%u", imm);
}


// Print 16-bit signed immediate value.
void Decoder::PrintSImm16(Instruction* instr) {
  int32_t imm = ((instr->Imm16Value()) << 16) >> 16;
  out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_, "%d", imm);
}


// Print 16-bit hexa immediate value.
void Decoder::PrintXImm16(Instruction* instr) {
  int32_t imm = instr->Imm16Value();
  out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_, "0x%x", imm);
}


// Print 26-bit immediate value.
void Decoder::PrintXImm26(Instruction* instr) {
  uint32_t imm = instr->Imm26Value() << kImmFieldShift;
  out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_, "0x%x", imm);
}


// Print 26-bit immediate value.
void Decoder::PrintCode(Instruction* instr) {
  if (instr->OpcodeFieldRaw() != SPECIAL)
    return;  // Not a break or trap instruction.
  switch (instr->FunctionFieldRaw()) {
    case BREAK: {
      int32_t code = instr->Bits(25, 6);
      out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_,
                                      "0x%05x (%d)", code, code);
      break;
                }
    case TGE:
    case TGEU:
    case TLT:
    case TLTU:
    case TEQ:
    case TNE: {
      int32_t code = instr->Bits(15, 6);
      out_buffer_pos_ +=
          OS::SNPrintF(out_buffer_ + out_buffer_pos_, "0x%03x", code);
      break;
    }
    default:  // Not a break or trap instruction.
    break;
  };
}


// Printing of instruction name.
void Decoder::PrintInstructionName(Instruction* instr) {
}


// Handle all register based formatting in this function to reduce the
// complexity of FormatOption.
int Decoder::FormatRegister(Instruction* instr, const char* format) {
  ASSERT(format[0] == 'r');
  if (format[1] == 's') {  // 'rs: Rs register.
    int reg = instr->RsValue();
    PrintRegister(reg);
    return 2;
  } else if (format[1] == 't') {  // 'rt: rt register.
    int reg = instr->RtValue();
    PrintRegister(reg);
    return 2;
  } else if (format[1] == 'd') {  // 'rd: rd register.
    int reg = instr->RdValue();
    PrintRegister(reg);
    return 2;
  }
  UNREACHABLE();
  return -1;
}


// Handle all FPUregister based formatting in this function to reduce the
// complexity of FormatOption.
int Decoder::FormatFPURegister(Instruction* instr, const char* format) {
  ASSERT(format[0] == 'f');
  if (format[1] == 's') {  // 'fs: fs register.
    int reg = instr->FsValue();
    PrintFPURegister(reg);
    return 2;
  } else if (format[1] == 't') {  // 'ft: ft register.
    int reg = instr->FtValue();
    PrintFPURegister(reg);
    return 2;
  } else if (format[1] == 'd') {  // 'fd: fd register.
    int reg = instr->FdValue();
    PrintFPURegister(reg);
    return 2;
  }
  UNREACHABLE();
  return -1;
}


// FormatOption takes a formatting string and interprets it based on
// the current instructions. The format string points to the first
// character of the option string (the option escape has already been
// consumed by the caller.)  FormatOption returns the number of
// characters that were consumed from the formatting string.
int Decoder::FormatOption(Instruction* instr, const char* format) {
  switch (format[0]) {
    case 'c': {   // 'code for break or trap instructions.
      ASSERT(STRING_STARTS_WITH(format, "code"));
      PrintCode(instr);
      return 4;
    }
    case 'i': {   // 'imm16u or 'imm26.
      if (format[3] == '1') {
        ASSERT(STRING_STARTS_WITH(format, "imm16"));
        if (format[5] == 's') {
          ASSERT(STRING_STARTS_WITH(format, "imm16s"));
          PrintSImm16(instr);
        } else if (format[5] == 'u') {
          ASSERT(STRING_STARTS_WITH(format, "imm16u"));
          PrintSImm16(instr);
        } else {
          ASSERT(STRING_STARTS_WITH(format, "imm16x"));
          PrintXImm16(instr);
        }
        return 6;
      } else {
        ASSERT(STRING_STARTS_WITH(format, "imm26x"));
        PrintXImm26(instr);
        return 6;
      }
    }
    case 'r': {   // 'r: registers.
      return FormatRegister(instr, format);
    }
    case 'f': {   // 'f: FPUregisters.
      return FormatFPURegister(instr, format);
    }
    case 's': {   // 'sa.
      switch (format[1]) {
        case 'a': {
          ASSERT(STRING_STARTS_WITH(format, "sa"));
          PrintSa(instr);
          return 2;
        }
        case 'd': {
          ASSERT(STRING_STARTS_WITH(format, "sd"));
          PrintSd(instr);
          return 2;
        }
        case 's': {
          if (format[2] == '1') {
              ASSERT(STRING_STARTS_WITH(format, "ss1"));  /* ext size */
              PrintSs1(instr);
              return 3;
          } else {
              ASSERT(STRING_STARTS_WITH(format, "ss2"));  /* ins size */
              PrintSs2(instr);
              return 3;
          }
        }
      }
    }
    case 'b': {   // 'bc - Special for bc1 cc field.
      ASSERT(STRING_STARTS_WITH(format, "bc"));
      PrintBc(instr);
      return 2;
    }
    case 'C': {   // 'Cc - Special for c.xx.d cc field.
      ASSERT(STRING_STARTS_WITH(format, "Cc"));
      PrintCc(instr);
      return 2;
    }
  };
  UNREACHABLE();
  return -1;
}


// Format takes a formatting string for a whole instruction and prints it into
// the output buffer. All escaped options are handed to FormatOption to be
// parsed further.
void Decoder::Format(Instruction* instr, const char* format) {
  char cur = *format++;
  while ((cur != 0) && (out_buffer_pos_ < (out_buffer_.length() - 1))) {
    if (cur == '\'') {  // Single quote is used as the formatting escape.
      format += FormatOption(instr, format);
    } else {
      out_buffer_[out_buffer_pos_++] = cur;
    }
    cur = *format++;
  }
  out_buffer_[out_buffer_pos_]  = '\0';
}


// For currently unimplemented decodings the disassembler calls Unknown(instr)
// which will just print "unknown" of the instruction bits.
void Decoder::Unknown(Instruction* instr) {
  Format(instr, "unknown");
}


void Decoder::DecodeTypeRegister(Instruction* instr) {
  switch (instr->OpcodeFieldRaw()) {
    case COP1:    // Coprocessor instructions.
      switch (instr->RsFieldRaw()) {
        case BC1:   // bc1 handled in DecodeTypeImmediate.
          UNREACHABLE();
          break;
        case MFC1:
          Format(instr, "mfc1    'rt, 'fs");
          break;
        case MFHC1:
          Format(instr, "mfhc1   'rt, 'fs");
          break;
        case MTC1:
          Format(instr, "mtc1    'rt, 'fs");
          break;
        // These are called "fs" too, although they are not FPU registers.
        case CTC1:
          Format(instr, "ctc1    'rt, 'fs");
          break;
        case CFC1:
          Format(instr, "cfc1    'rt, 'fs");
          break;
        case MTHC1:
          Format(instr, "mthc1   'rt, 'fs");
          break;
        case D:
          switch (instr->FunctionFieldRaw()) {
            case ADD_D:
              Format(instr, "add.d   'fd, 'fs, 'ft");
              break;
            case SUB_D:
              Format(instr, "sub.d   'fd, 'fs, 'ft");
              break;
            case MUL_D:
              Format(instr, "mul.d   'fd, 'fs, 'ft");
              break;
            case DIV_D:
              Format(instr, "div.d   'fd, 'fs, 'ft");
              break;
            case ABS_D:
              Format(instr, "abs.d   'fd, 'fs");
              break;
            case MOV_D:
              Format(instr, "mov.d   'fd, 'fs");
              break;
            case NEG_D:
              Format(instr, "neg.d   'fd, 'fs");
              break;
            case SQRT_D:
              Format(instr, "sqrt.d  'fd, 'fs");
              break;
            case CVT_W_D:
              Format(instr, "cvt.w.d 'fd, 'fs");
              break;
            case CVT_L_D: {
              if (kArchVariant == kMips32r2) {
                Format(instr, "cvt.l.d 'fd, 'fs");
              } else {
                Unknown(instr);
              }
              break;
            }
            case TRUNC_W_D:
              Format(instr, "trunc.w.d 'fd, 'fs");
              break;
            case TRUNC_L_D: {
              if (kArchVariant == kMips32r2) {
                Format(instr, "trunc.l.d 'fd, 'fs");
              } else {
                Unknown(instr);
              }
              break;
            }
            case ROUND_W_D:
              Format(instr, "round.w.d 'fd, 'fs");
              break;
            case FLOOR_W_D:
              Format(instr, "floor.w.d 'fd, 'fs");
              break;
            case CEIL_W_D:
              Format(instr, "ceil.w.d 'fd, 'fs");
              break;
            case CVT_S_D:
              Format(instr, "cvt.s.d 'fd, 'fs");
              break;
            case C_F_D:
              Format(instr, "c.f.d   'fs, 'ft, 'Cc");
              break;
            case C_UN_D:
              Format(instr, "c.un.d  'fs, 'ft, 'Cc");
              break;
            case C_EQ_D:
              Format(instr, "c.eq.d  'fs, 'ft, 'Cc");
              break;
            case C_UEQ_D:
              Format(instr, "c.ueq.d 'fs, 'ft, 'Cc");
              break;
            case C_OLT_D:
              Format(instr, "c.olt.d 'fs, 'ft, 'Cc");
              break;
            case C_ULT_D:
              Format(instr, "c.ult.d 'fs, 'ft, 'Cc");
              break;
            case C_OLE_D:
              Format(instr, "c.ole.d 'fs, 'ft, 'Cc");
              break;
            case C_ULE_D:
              Format(instr, "c.ule.d 'fs, 'ft, 'Cc");
              break;
            default:
              Format(instr, "unknown.cop1.d");
              break;
          }
          break;
        case S:
          UNIMPLEMENTED_MIPS();
          break;
        case W:
          switch (instr->FunctionFieldRaw()) {
            case CVT_S_W:   // Convert word to float (single).
              Format(instr, "cvt.s.w 'fd, 'fs");
              break;
            case CVT_D_W:   // Convert word to double.
              Format(instr, "cvt.d.w 'fd, 'fs");
              break;
            default:
              UNREACHABLE();
          }
          break;
        case L:
          switch (instr->FunctionFieldRaw()) {
            case CVT_D_L: {
              if (kArchVariant == kMips32r2) {
                Format(instr, "cvt.d.l 'fd, 'fs");
              } else {
                Unknown(instr);
              }
              break;
            }
            case CVT_S_L: {
              if (kArchVariant == kMips32r2) {
                Format(instr, "cvt.s.l 'fd, 'fs");
              } else {
                Unknown(instr);
              }
              break;
            }
            default:
              UNREACHABLE();
          }
          break;
        case PS:
          UNIMPLEMENTED_MIPS();
          break;
        default:
          UNREACHABLE();
      }
      break;
    case SPECIAL:
      switch (instr->FunctionFieldRaw()) {
        case JR:
          Format(instr, "jr      'rs");
          break;
        case JALR:
          Format(instr, "jalr    'rs");
          break;
        case SLL:
          if ( 0x0 == static_cast<int>(instr->InstructionBits()))
            Format(instr, "nop");
          else
            Format(instr, "sll     'rd, 'rt, 'sa");
          break;
        case SRL:
          if (instr->RsValue() == 0) {
            Format(instr, "srl     'rd, 'rt, 'sa");
          } else {
            if (kArchVariant == kMips32r2) {
              Format(instr, "rotr    'rd, 'rt, 'sa");
            } else {
              Unknown(instr);
            }
          }
          break;
        case SRA:
          Format(instr, "sra     'rd, 'rt, 'sa");
          break;
        case SLLV:
          Format(instr, "sllv    'rd, 'rt, 'rs");
          break;
        case SRLV:
          if (instr->SaValue() == 0) {
            Format(instr, "srlv    'rd, 'rt, 'rs");
          } else {
            if (kArchVariant == kMips32r2) {
              Format(instr, "rotrv   'rd, 'rt, 'rs");
            } else {
              Unknown(instr);
            }
          }
          break;
        case SRAV:
          Format(instr, "srav    'rd, 'rt, 'rs");
          break;
        case MFHI:
          Format(instr, "mfhi    'rd");
          break;
        case MFLO:
          Format(instr, "mflo    'rd");
          break;
        case MULT:
          Format(instr, "mult    'rs, 'rt");
          break;
        case MULTU:
          Format(instr, "multu   'rs, 'rt");
          break;
        case DIV:
          Format(instr, "div     'rs, 'rt");
          break;
        case DIVU:
          Format(instr, "divu    'rs, 'rt");
          break;
        case ADD:
          Format(instr, "add     'rd, 'rs, 'rt");
          break;
        case ADDU:
          Format(instr, "addu    'rd, 'rs, 'rt");
          break;
        case SUB:
          Format(instr, "sub     'rd, 'rs, 'rt");
          break;
        case SUBU:
          Format(instr, "subu    'rd, 'rs, 'rt");
          break;
        case AND:
          Format(instr, "and     'rd, 'rs, 'rt");
          break;
        case OR:
          if (0 == instr->RsValue()) {
            Format(instr, "mov     'rd, 'rt");
          } else if (0 == instr->RtValue()) {
            Format(instr, "mov     'rd, 'rs");
          } else {
            Format(instr, "or      'rd, 'rs, 'rt");
          }
          break;
        case XOR:
          Format(instr, "xor     'rd, 'rs, 'rt");
          break;
        case NOR:
          Format(instr, "nor     'rd, 'rs, 'rt");
          break;
        case SLT:
          Format(instr, "slt     'rd, 'rs, 'rt");
          break;
        case SLTU:
          Format(instr, "sltu    'rd, 'rs, 'rt");
          break;
        case BREAK:
          Format(instr, "break, code: 'code");
          break;
        case TGE:
          Format(instr, "tge     'rs, 'rt, code: 'code");
          break;
        case TGEU:
          Format(instr, "tgeu    'rs, 'rt, code: 'code");
          break;
        case TLT:
          Format(instr, "tlt     'rs, 'rt, code: 'code");
          break;
        case TLTU:
          Format(instr, "tltu    'rs, 'rt, code: 'code");
          break;
        case TEQ:
          Format(instr, "teq     'rs, 'rt, code: 'code");
          break;
        case TNE:
          Format(instr, "tne     'rs, 'rt, code: 'code");
          break;
        case MOVZ:
          Format(instr, "movz    'rd, 'rs, 'rt");
          break;
        case MOVN:
          Format(instr, "movn    'rd, 'rs, 'rt");
          break;
        case MOVCI:
          if (instr->Bit(16)) {
            Format(instr, "movt    'rd, 'rs, 'bc");
          } else {
            Format(instr, "movf    'rd, 'rs, 'bc");
          }
          break;
        default:
          UNREACHABLE();
      }
      break;
    case SPECIAL2:
      switch (instr->FunctionFieldRaw()) {
        case MUL:
          Format(instr, "mul     'rd, 'rs, 'rt");
          break;
        case CLZ:
          Format(instr, "clz     'rd, 'rs");
          break;
        default:
          UNREACHABLE();
      }
      break;
    case SPECIAL3:
      switch (instr->FunctionFieldRaw()) {
        case INS: {
          if (kArchVariant == kMips32r2) {
            Format(instr, "ins     'rt, 'rs, 'sa, 'ss2");
          } else {
            Unknown(instr);
          }
          break;
        }
        case EXT: {
          if (kArchVariant == kMips32r2) {
            Format(instr, "ext     'rt, 'rs, 'sa, 'ss1");
          } else {
            Unknown(instr);
          }
          break;
        }
        default:
          UNREACHABLE();
      }
      break;
    default:
      UNREACHABLE();
  }
}


void Decoder::DecodeTypeImmediate(Instruction* instr) {
  switch (instr->OpcodeFieldRaw()) {
    // ------------- REGIMM class.
    case COP1:
      switch (instr->RsFieldRaw()) {
        case BC1:
          if (instr->FBtrueValue()) {
            Format(instr, "bc1t    'bc, 'imm16u");
          } else {
            Format(instr, "bc1f    'bc, 'imm16u");
          }
          break;
        default:
          UNREACHABLE();
      };
      break;  // Case COP1.
    case REGIMM:
      switch (instr->RtFieldRaw()) {
        case BLTZ:
          Format(instr, "bltz    'rs, 'imm16u");
          break;
        case BLTZAL:
          Format(instr, "bltzal  'rs, 'imm16u");
          break;
        case BGEZ:
          Format(instr, "bgez    'rs, 'imm16u");
          break;
        case BGEZAL:
          Format(instr, "bgezal  'rs, 'imm16u");
          break;
        default:
          UNREACHABLE();
      }
    break;  // Case REGIMM.
    // ------------- Branch instructions.
    case BEQ:
      Format(instr, "beq     'rs, 'rt, 'imm16u");
      break;
    case BNE:
      Format(instr, "bne     'rs, 'rt, 'imm16u");
      break;
    case BLEZ:
      Format(instr, "blez    'rs, 'imm16u");
      break;
    case BGTZ:
      Format(instr, "bgtz    'rs, 'imm16u");
      break;
    // ------------- Arithmetic instructions.
    case ADDI:
      Format(instr, "addi    'rt, 'rs, 'imm16s");
      break;
    case ADDIU:
      Format(instr, "addiu   'rt, 'rs, 'imm16s");
      break;
    case SLTI:
      Format(instr, "slti    'rt, 'rs, 'imm16s");
      break;
    case SLTIU:
      Format(instr, "sltiu   'rt, 'rs, 'imm16u");
      break;
    case ANDI:
      Format(instr, "andi    'rt, 'rs, 'imm16x");
      break;
    case ORI:
      Format(instr, "ori     'rt, 'rs, 'imm16x");
      break;
    case XORI:
      Format(instr, "xori    'rt, 'rs, 'imm16x");
      break;
    case LUI:
      Format(instr, "lui     'rt, 'imm16x");
      break;
    // ------------- Memory instructions.
    case LB:
      Format(instr, "lb      'rt, 'imm16s('rs)");
      break;
    case LH:
      Format(instr, "lh      'rt, 'imm16s('rs)");
      break;
    case LWL:
      Format(instr, "lwl     'rt, 'imm16s('rs)");
      break;
    case LW:
      Format(instr, "lw      'rt, 'imm16s('rs)");
      break;
    case LBU:
      Format(instr, "lbu     'rt, 'imm16s('rs)");
      break;
    case LHU:
      Format(instr, "lhu     'rt, 'imm16s('rs)");
      break;
    case LWR:
      Format(instr, "lwr     'rt, 'imm16s('rs)");
      break;
    case SB:
      Format(instr, "sb      'rt, 'imm16s('rs)");
      break;
    case SH:
      Format(instr, "sh      'rt, 'imm16s('rs)");
      break;
    case SWL:
      Format(instr, "swl     'rt, 'imm16s('rs)");
      break;
    case SW:
      Format(instr, "sw      'rt, 'imm16s('rs)");
      break;
    case SWR:
      Format(instr, "swr     'rt, 'imm16s('rs)");
      break;
    case LWC1:
      Format(instr, "lwc1    'ft, 'imm16s('rs)");
      break;
    case LDC1:
      Format(instr, "ldc1    'ft, 'imm16s('rs)");
      break;
    case SWC1:
      Format(instr, "swc1    'ft, 'imm16s('rs)");
      break;
    case SDC1:
      Format(instr, "sdc1    'ft, 'imm16s('rs)");
      break;
    default:
      UNREACHABLE();
      break;
  };
}


void Decoder::DecodeTypeJump(Instruction* instr) {
  switch (instr->OpcodeFieldRaw()) {
    case J:
      Format(instr, "j       'imm26x");
      break;
    case JAL:
      Format(instr, "jal     'imm26x");
      break;
    default:
      UNREACHABLE();
  }
}


// Disassemble the instruction at *instr_ptr into the output buffer.
int Decoder::InstructionDecode(byte* instr_ptr) {
  Instruction* instr = Instruction::At(instr_ptr);
  // Print raw instruction bytes.
  out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_,
                                       "%08x       ",
                                       instr->InstructionBits());
  switch (instr->InstructionType()) {
    case Instruction::kRegisterType: {
      DecodeTypeRegister(instr);
      break;
    }
    case Instruction::kImmediateType: {
      DecodeTypeImmediate(instr);
      break;
    }
    case Instruction::kJumpType: {
      DecodeTypeJump(instr);
      break;
    }
    default: {
      Format(instr, "UNSUPPORTED");
      UNSUPPORTED_MIPS();
    }
  }
  return Instruction::kInstrSize;
}


} }  // namespace v8::internal



//------------------------------------------------------------------------------

namespace disasm {

const char* NameConverter::NameOfAddress(byte* addr) const {
  v8::internal::OS::SNPrintF(tmp_buffer_, "%p", addr);
  return tmp_buffer_.start();
}


const char* NameConverter::NameOfConstant(byte* addr) const {
  return NameOfAddress(addr);
}


const char* NameConverter::NameOfCPURegister(int reg) const {
  return v8::internal::Registers::Name(reg);
}


const char* NameConverter::NameOfXMMRegister(int reg) const {
  return v8::internal::FPURegisters::Name(reg);
}


const char* NameConverter::NameOfByteCPURegister(int reg) const {
  UNREACHABLE();  // MIPS does not have the concept of a byte register.
  return "nobytereg";
}


const char* NameConverter::NameInCode(byte* addr) const {
  // The default name converter is called for unknown code. So we will not try
  // to access any memory.
  return "";
}


//------------------------------------------------------------------------------

Disassembler::Disassembler(const NameConverter& converter)
    : converter_(converter) {}


Disassembler::~Disassembler() {}


int Disassembler::InstructionDecode(v8::internal::Vector<char> buffer,
                                    byte* instruction) {
  v8::internal::Decoder d(converter_, buffer);
  return d.InstructionDecode(instruction);
}


// The MIPS assembler does not currently use constant pools.
int Disassembler::ConstantPoolSizeAt(byte* instruction) {
  return -1;
}


void Disassembler::Disassemble(FILE* f, byte* begin, byte* end) {
  NameConverter converter;
  Disassembler d(converter);
  for (byte* pc = begin; pc < end;) {
    v8::internal::EmbeddedVector<char, 128> buffer;
    buffer[0] = '\0';
    byte* prev_pc = pc;
    pc += d.InstructionDecode(buffer, pc);
    fprintf(f, "%p    %08x      %s\n",
            prev_pc, *reinterpret_cast<int32_t*>(prev_pc), buffer.start());
  }
}


#undef UNSUPPORTED

}  // namespace disasm

#endif  // V8_TARGET_ARCH_MIPS

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