PowerPC specific sub-directories

src/ppc/disasm-ppc.cc

+// Copyright 2014 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// 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 <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "src/v8.h"
+
+#if V8_TARGET_ARCH_PPC
+
+#include "src/base/platform/platform.h"
+#include "src/disasm.h"
+#include "src/macro-assembler.h"
+#include "src/ppc/constants-ppc.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, 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 PrintDRegister(int reg);
+  int FormatFPRegister(Instruction* instr, const char* format);
+  void PrintSoftwareInterrupt(SoftwareInterruptCodes svc);
+
+  // Handle formatting of instructions and their options.
+  int FormatRegister(Instruction* instr, const char* option);
+  int FormatOption(Instruction* instr, const char* option);
+  void Format(Instruction* instr, const char* format);
+  void Unknown(Instruction* instr);
+  void UnknownFormat(Instruction* instr, const char* opcname);
+  void MarkerFormat(Instruction* instr, const char* opcname, int id);
+
+  void DecodeExt1(Instruction* instr);
+  void DecodeExt2(Instruction* instr);
+  void DecodeExt4(Instruction* instr);
+  void DecodeExt5(Instruction* instr);
+
+  const disasm::NameConverter& converter_;
+  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));
+}
+
+
+// Print the double FP register name according to the active name converter.
+void Decoder::PrintDRegister(int reg) { Print(FPRegisters::Name(reg)); }
+
+
+// Print SoftwareInterrupt codes. Factoring this out reduces the complexity of
+// the FormatOption method.
+void Decoder::PrintSoftwareInterrupt(SoftwareInterruptCodes svc) {
+  switch (svc) {
+    case kCallRtRedirected:
+      Print("call rt redirected");
+      return;
+    case kBreakpoint:
+      Print("breakpoint");
+      return;
+    default:
+      if (svc >= kStopCode) {
+        out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_, "%d - 0x%x",
+                                    svc & kStopCodeMask, svc & kStopCodeMask);
+      } else {
+        out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_, "%d", svc);
+      }
+      return;
+  }
+}
+
+
+// Handle all register based formatting in this function to reduce the
+// complexity of FormatOption.
+int Decoder::FormatRegister(Instruction* instr, const char* format) {
+  DCHECK(format[0] == 'r');
+
+  if ((format[1] == 't') || (format[1] == 's')) {  // 'rt & 'rs register
+    int reg = instr->RTValue();
+    PrintRegister(reg);
+    return 2;
+  } else if (format[1] == 'a') {  // 'ra: RA register
+    int reg = instr->RAValue();
+    PrintRegister(reg);
+    return 2;
+  } else if (format[1] == 'b') {  // 'rb: RB register
+    int reg = instr->RBValue();
+    PrintRegister(reg);
+    return 2;
+  }
+
+  UNREACHABLE();
+  return -1;
+}
+
+
+// Handle all FP register based formatting in this function to reduce the
+// complexity of FormatOption.
+int Decoder::FormatFPRegister(Instruction* instr, const char* format) {
+  DCHECK(format[0] == 'D');
+
+  int retval = 2;
+  int reg = -1;
+  if (format[1] == 't') {
+    reg = instr->RTValue();
+  } else if (format[1] == 'a') {
+    reg = instr->RAValue();
+  } else if (format[1] == 'b') {
+    reg = instr->RBValue();
+  } else if (format[1] == 'c') {
+    reg = instr->RCValue();
+  } else {
+    UNREACHABLE();
+  }
+
+  PrintDRegister(reg);
+
+  return retval;
+}
+
+
+// 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 'o': {
+      if (instr->Bit(10) == 1) {
+        Print("o");
+      }
+      return 1;
+    }
+    case '.': {
+      if (instr->Bit(0) == 1) {
+        Print(".");
+      } else {
+        Print(" ");  // ensure consistent spacing
+      }
+      return 1;
+    }
+    case 'r': {
+      return FormatRegister(instr, format);
+    }
+    case 'D': {
+      return FormatFPRegister(instr, format);
+    }
+    case 'i': {  // int16
+      int32_t value = (instr->Bits(15, 0) << 16) >> 16;
+      out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_, "%d", value);
+      return 5;
+    }
+    case 'u': {  // uint16
+      int32_t value = instr->Bits(15, 0);
+      out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_, "%d", value);
+      return 6;
+    }
+    case 'l': {
+      // Link (LK) Bit 0
+      if (instr->Bit(0) == 1) {
+        Print("l");
+      }
+      return 1;
+    }
+    case 'a': {
+      // Absolute Address Bit 1
+      if (instr->Bit(1) == 1) {
+        Print("a");
+      }
+      return 1;
+    }
+    case 't': {  // 'target: target of branch instructions
+      // target26 or target16
+      DCHECK(STRING_STARTS_WITH(format, "target"));
+      if ((format[6] == '2') && (format[7] == '6')) {
+        int off = ((instr->Bits(25, 2)) << 8) >> 6;
+        out_buffer_pos_ += SNPrintF(
+            out_buffer_ + out_buffer_pos_, "%+d -> %s", off,
+            converter_.NameOfAddress(reinterpret_cast<byte*>(instr) + off));
+        return 8;
+      } else if ((format[6] == '1') && (format[7] == '6')) {
+        int off = ((instr->Bits(15, 2)) << 18) >> 16;
+        out_buffer_pos_ += SNPrintF(
+            out_buffer_ + out_buffer_pos_, "%+d -> %s", off,
+            converter_.NameOfAddress(reinterpret_cast<byte*>(instr) + off));
+        return 8;
+      }
+      case 's': {
+        DCHECK(format[1] == 'h');
+        int32_t value = 0;
+        int32_t opcode = instr->OpcodeValue() << 26;
+        int32_t sh = instr->Bits(15, 11);
+        if (opcode == EXT5 ||
+            (opcode == EXT2 && instr->Bits(10, 2) << 2 == SRADIX)) {
+          // SH Bits 1 and 15-11 (split field)
+          value = (sh | (instr->Bit(1) << 5));
+        } else {
+          // SH Bits 15-11
+          value = (sh << 26) >> 26;
+        }
+        out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_, "%d", value);
+        return 2;
+      }
+      case 'm': {
+        int32_t value = 0;
+        if (format[1] == 'e') {
+          if (instr->OpcodeValue() << 26 != EXT5) {
+            // ME Bits 10-6
+            value = (instr->Bits(10, 6) << 26) >> 26;
+          } else {
+            // ME Bits 5 and 10-6 (split field)
+            value = (instr->Bits(10, 6) | (instr->Bit(5) << 5));
+          }
+        } else if (format[1] == 'b') {
+          if (instr->OpcodeValue() << 26 != EXT5) {
+            // MB Bits 5-1
+            value = (instr->Bits(5, 1) << 26) >> 26;
+          } else {
+            // MB Bits 5 and 10-6 (split field)
+            value = (instr->Bits(10, 6) | (instr->Bit(5) << 5));
+          }
+        } else {
+          UNREACHABLE();  // bad format
+        }
+        out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_, "%d", value);
+        return 2;
+      }
+    }
+#if V8_TARGET_ARCH_PPC64
+    case 'd': {  // ds value for offset
+      int32_t value = SIGN_EXT_IMM16(instr->Bits(15, 0) & ~3);
+      out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_, "%d", value);
+      return 1;
+    }
+#endif
+    default: {
+      UNREACHABLE();
+      break;
+    }
+  }
+
+  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';
+}
+
+
+// The disassembler may end up decoding data inlined in the code. We do not want
+// it to crash if the data does not ressemble any known instruction.
+#define VERIFY(condition) \
+  if (!(condition)) {     \
+    Unknown(instr);       \
+    return;               \
+  }
+
+
+// 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"); }
+
+
+// For currently unimplemented decodings the disassembler calls
+// UnknownFormat(instr) which will just print opcode name of the
+// instruction bits.
+void Decoder::UnknownFormat(Instruction* instr, const char* name) {
+  char buffer[100];
+  snprintf(buffer, sizeof(buffer), "%s (unknown-format)", name);
+  Format(instr, buffer);
+}
+
+
+void Decoder::MarkerFormat(Instruction* instr, const char* name, int id) {
+  char buffer[100];
+  snprintf(buffer, sizeof(buffer), "%s %d", name, id);
+  Format(instr, buffer);
+}
+
+
+void Decoder::DecodeExt1(Instruction* instr) {
+  switch (instr->Bits(10, 1) << 1) {
+    case MCRF: {
+      UnknownFormat(instr, "mcrf");  // not used by V8
+      break;
+    }
+    case BCLRX: {
+      switch (instr->Bits(25, 21) << 21) {
+        case DCBNZF: {
+          UnknownFormat(instr, "bclrx-dcbnzf");
+          break;
+        }
+        case DCBEZF: {
+          UnknownFormat(instr, "bclrx-dcbezf");
+          break;
+        }
+        case BF: {
+          UnknownFormat(instr, "bclrx-bf");
+          break;
+        }
+        case DCBNZT: {
+          UnknownFormat(instr, "bclrx-dcbbzt");
+          break;
+        }
+        case DCBEZT: {
+          UnknownFormat(instr, "bclrx-dcbnezt");
+          break;
+        }
+        case BT: {
+          UnknownFormat(instr, "bclrx-bt");
+          break;
+        }
+        case DCBNZ: {
+          UnknownFormat(instr, "bclrx-dcbnz");
+          break;
+        }
+        case DCBEZ: {
+          UnknownFormat(instr, "bclrx-dcbez");  // not used by V8
+          break;
+        }
+        case BA: {
+          if (instr->Bit(0) == 1) {
+            Format(instr, "blrl");
+          } else {
+            Format(instr, "blr");
+          }
+          break;
+        }
+      }
+      break;
+    }
+    case BCCTRX: {
+      switch (instr->Bits(25, 21) << 21) {
+        case DCBNZF: {
+          UnknownFormat(instr, "bcctrx-dcbnzf");
+          break;
+        }
+        case DCBEZF: {
+          UnknownFormat(instr, "bcctrx-dcbezf");
+          break;
+        }
+        case BF: {
+          UnknownFormat(instr, "bcctrx-bf");
+          break;
+        }
+        case DCBNZT: {
+          UnknownFormat(instr, "bcctrx-dcbnzt");
+          break;
+        }
+        case DCBEZT: {
+          UnknownFormat(instr, "bcctrx-dcbezf");
+          break;
+        }
+        case BT: {
+          UnknownFormat(instr, "bcctrx-bt");
+          break;
+        }
+        case DCBNZ: {
+          UnknownFormat(instr, "bcctrx-dcbnz");
+          break;
+        }
+        case DCBEZ: {
+          UnknownFormat(instr, "bcctrx-dcbez");
+          break;
+        }
+        case BA: {
+          if (instr->Bit(0) == 1) {
+            Format(instr, "bctrl");
+          } else {
+            Format(instr, "bctr");
+          }
+          break;
+        }
+        default: { UNREACHABLE(); }
+      }
+      break;
+    }
+    case CRNOR: {
+      Format(instr, "crnor (stuff)");
+      break;
+    }
+    case RFI: {
+      Format(instr, "rfi (stuff)");
+      break;
+    }
+    case CRANDC: {
+      Format(instr, "crandc (stuff)");
+      break;
+    }
+    case ISYNC: {
+      Format(instr, "isync (stuff)");
+      break;
+    }
+    case CRXOR: {
+      Format(instr, "crxor (stuff)");
+      break;
+    }
+    case CRNAND: {
+      UnknownFormat(instr, "crnand");
+      break;
+    }
+    case CRAND: {
+      UnknownFormat(instr, "crand");
+      break;
+    }
+    case CREQV: {
+      UnknownFormat(instr, "creqv");
+      break;
+    }
+    case CRORC: {
+      UnknownFormat(instr, "crorc");
+      break;
+    }
+    case CROR: {
+      UnknownFormat(instr, "cror");
+      break;
+    }
+    default: {
+      Unknown(instr);  // not used by V8
+    }
+  }
+}
+
+
+void Decoder::DecodeExt2(Instruction* instr) {
+  // Some encodings are 10-1 bits, handle those first
+  switch (instr->Bits(10, 1) << 1) {
+    case SRWX: {
+      Format(instr, "srw'.    'ra, 'rs, 'rb");
+      return;
+    }
+#if V8_TARGET_ARCH_PPC64
+    case SRDX: {
+      Format(instr, "srd'.    'ra, 'rs, 'rb");
+      return;
+    }
+#endif
+    case SRAW: {
+      Format(instr, "sraw'.   'ra, 'rs, 'rb");
+      return;
+    }
+#if V8_TARGET_ARCH_PPC64
+    case SRAD: {
+      Format(instr, "srad'.   'ra, 'rs, 'rb");
+      return;
+    }
+#endif
+    case SRAWIX: {
+      Format(instr, "srawi'.  'ra,'rs,'sh");
+      return;
+    }
+    case EXTSH: {
+      Format(instr, "extsh'.  'ra, 'rs");
+      return;
+    }
+#if V8_TARGET_ARCH_PPC64
+    case EXTSW: {
+      Format(instr, "extsw'.  'ra, 'rs");
+      return;
+    }
+#endif
+    case EXTSB: {
+      Format(instr, "extsb'.  'ra, 'rs");
+      return;
+    }
+    case LFSX: {
+      Format(instr, "lfsx    'rt, 'ra, 'rb");
+      return;
+    }
+    case LFSUX: {
+      Format(instr, "lfsux   'rt, 'ra, 'rb");
+      return;
+    }
+    case LFDX: {
+      Format(instr, "lfdx    'rt, 'ra, 'rb");
+      return;
+    }
+    case LFDUX: {
+      Format(instr, "lfdux   'rt, 'ra, 'rb");
+      return;
+    }
+    case STFSX: {
+      Format(instr, "stfsx    'rs, 'ra, 'rb");
+      return;
+    }
+    case STFSUX: {
+      Format(instr, "stfsux   'rs, 'ra, 'rb");
+      return;
+    }
+    case STFDX: {
+      Format(instr, "stfdx    'rs, 'ra, 'rb");
+      return;
+    }
+    case STFDUX: {
+      Format(instr, "stfdux   'rs, 'ra, 'rb");
+      return;
+    }
+  }
+
+  switch (instr->Bits(10, 2) << 2) {
+    case SRADIX: {
+      Format(instr, "sradi'.  'ra,'rs,'sh");
+      return;
+    }
+  }
+
+  // ?? are all of these xo_form?
+  switch (instr->Bits(9, 1) << 1) {
+    case CMP: {
+#if V8_TARGET_ARCH_PPC64
+      if (instr->Bit(21)) {
+#endif
+        Format(instr, "cmp     'ra, 'rb");
+#if V8_TARGET_ARCH_PPC64
+      } else {
+        Format(instr, "cmpw    'ra, 'rb");
+      }
+#endif
+      break;
+    }
+    case SLWX: {
+      Format(instr, "slw'.   'ra, 'rs, 'rb");
+      break;
+    }
+#if V8_TARGET_ARCH_PPC64
+    case SLDX: {
+      Format(instr, "sld'.   'ra, 'rs, 'rb");
+      break;
+    }
+#endif
+    case SUBFCX: {
+      Format(instr, "subfc'. 'rt, 'ra, 'rb");
+      break;
+    }
+    case ADDCX: {
+      Format(instr, "addc'.   'rt, 'ra, 'rb");
+      break;
+    }
+    case CNTLZWX: {
+      Format(instr, "cntlzw'. 'ra, 'rs");
+      break;
+    }
+#if V8_TARGET_ARCH_PPC64
+    case CNTLZDX: {
+      Format(instr, "cntlzd'. 'ra, 'rs");
+      break;
+    }
+#endif
+    case ANDX: {
+      Format(instr, "and'.    'ra, 'rs, 'rb");
+      break;
+    }
+    case ANDCX: {
+      Format(instr, "andc'.   'ra, 'rs, 'rb");
+      break;
+    }
+    case CMPL: {
+#if V8_TARGET_ARCH_PPC64
+      if (instr->Bit(21)) {
+#endif
+        Format(instr, "cmpl    'ra, 'rb");
+#if V8_TARGET_ARCH_PPC64
+      } else {
+        Format(instr, "cmplw   'ra, 'rb");
+      }
+#endif
+      break;
+    }
+    case NEGX: {
+      Format(instr, "neg'.    'rt, 'ra");
+      break;
+    }
+    case NORX: {
+      Format(instr, "nor'.    'rt, 'ra, 'rb");
+      break;
+    }
+    case SUBFX: {
+      Format(instr, "subf'.   'rt, 'ra, 'rb");
+      break;
+    }
+    case MULHWX: {
+      Format(instr, "mulhw'o'.  'rt, 'ra, 'rb");
+      break;
+    }
+    case ADDZEX: {
+      Format(instr, "addze'.   'rt, 'ra");
+      break;
+    }
+    case MULLW: {
+      Format(instr, "mullw'o'.  'rt, 'ra, 'rb");
+      break;
+    }
+#if V8_TARGET_ARCH_PPC64
+    case MULLD: {
+      Format(instr, "mulld'o'.  'rt, 'ra, 'rb");
+      break;
+    }
+#endif
+    case DIVW: {
+      Format(instr, "divw'o'.   'rt, 'ra, 'rb");
+      break;
+    }
+#if V8_TARGET_ARCH_PPC64
+    case DIVD: {
+      Format(instr, "divd'o'.   'rt, 'ra, 'rb");
+      break;
+    }
+#endif
+    case ADDX: {
+      Format(instr, "add'o     'rt, 'ra, 'rb");
+      break;
+    }
+    case XORX: {
+      Format(instr, "xor'.    'ra, 'rs, 'rb");
+      break;
+    }
+    case ORX: {
+      if (instr->RTValue() == instr->RBValue()) {
+        Format(instr, "mr      'ra, 'rb");
+      } else {
+        Format(instr, "or      'ra, 'rs, 'rb");
+      }
+      break;
+    }
+    case MFSPR: {
+      int spr = instr->Bits(20, 11);
+      if (256 == spr) {
+        Format(instr, "mflr    'rt");
+      } else {
+        Format(instr, "mfspr   'rt ??");
+      }
+      break;
+    }
+    case MTSPR: {
+      int spr = instr->Bits(20, 11);
+      if (256 == spr) {
+        Format(instr, "mtlr    'rt");
+      } else if (288 == spr) {
+        Format(instr, "mtctr   'rt");
+      } else {
+        Format(instr, "mtspr   'rt ??");
+      }
+      break;
+    }
+    case MFCR: {
+      Format(instr, "mfcr    'rt");
+      break;
+    }
+    case STWX: {
+      Format(instr, "stwx    'rs, 'ra, 'rb");
+      break;
+    }
+    case STWUX: {
+      Format(instr, "stwux   'rs, 'ra, 'rb");
+      break;
+    }
+    case STBX: {
+      Format(instr, "stbx    'rs, 'ra, 'rb");
+      break;
+    }
+    case STBUX: {
+      Format(instr, "stbux   'rs, 'ra, 'rb");
+      break;
+    }
+    case STHX: {
+      Format(instr, "sthx    'rs, 'ra, 'rb");
+      break;
+    }
+    case STHUX: {
+      Format(instr, "sthux   'rs, 'ra, 'rb");
+      break;
+    }
+    case LWZX: {
+      Format(instr, "lwzx    'rt, 'ra, 'rb");
+      break;
+    }
+    case LWZUX: {
+      Format(instr, "lwzux   'rt, 'ra, 'rb");
+      break;
+    }
+    case LBZX: {
+      Format(instr, "lbzx    'rt, 'ra, 'rb");
+      break;
+    }
+    case LBZUX: {
+      Format(instr, "lbzux   'rt, 'ra, 'rb");
+      break;
+    }
+    case LHZX: {
+      Format(instr, "lhzx    'rt, 'ra, 'rb");
+      break;
+    }
+    case LHZUX: {
+      Format(instr, "lhzux   'rt, 'ra, 'rb");
+      break;
+    }
+#if V8_TARGET_ARCH_PPC64
+    case LDX: {
+      Format(instr, "ldx     'rt, 'ra, 'rb");
+      break;
+    }
+    case LDUX: {
+      Format(instr, "ldux    'rt, 'ra, 'rb");
+      break;
+    }
+    case STDX: {
+      Format(instr, "stdx    'rt, 'ra, 'rb");
+      break;
+    }
+    case STDUX: {
+      Format(instr, "stdux   'rt, 'ra, 'rb");
+      break;
+    }
+    case MFVSRD: {
+      Format(instr, "mffprd  'ra, 'Dt");
+      break;
+    }
+    case MFVSRWZ: {
+      Format(instr, "mffprwz 'ra, 'Dt");
+      break;
+    }
+    case MTVSRD: {
+      Format(instr, "mtfprd  'Dt, 'ra");
+      break;
+    }
+    case MTVSRWA: {
+      Format(instr, "mtfprwa 'Dt, 'ra");
+      break;
+    }
+    case MTVSRWZ: {
+      Format(instr, "mtfprwz 'Dt, 'ra");
+      break;
+    }
+#endif
+    default: {
+      Unknown(instr);  // not used by V8
+    }
+  }
+}
+
+
+void Decoder::DecodeExt4(Instruction* instr) {
+  switch (instr->Bits(5, 1) << 1) {
+    case FDIV: {
+      Format(instr, "fdiv'.   'Dt, 'Da, 'Db");
+      return;
+    }
+    case FSUB: {
+      Format(instr, "fsub'.   'Dt, 'Da, 'Db");
+      return;
+    }
+    case FADD: {
+      Format(instr, "fadd'.   'Dt, 'Da, 'Db");
+      return;
+    }
+    case FSQRT: {
+      Format(instr, "fsqrt'.  'Dt, 'Db");
+      return;
+    }
+    case FSEL: {
+      Format(instr, "fsel'.   'Dt, 'Da, 'Dc, 'Db");
+      return;
+    }
+    case FMUL: {
+      Format(instr, "fmul'.   'Dt, 'Da, 'Dc");
+      return;
+    }
+    case FMSUB: {
+      Format(instr, "fmsub'.  'Dt, 'Da, 'Dc, 'Db");
+      return;
+    }
+    case FMADD: {
+      Format(instr, "fmadd'.  'Dt, 'Da, 'Dc, 'Db");
+      return;
+    }
+  }
+
+  switch (instr->Bits(10, 1) << 1) {
+    case FCMPU: {
+      Format(instr, "fcmpu   'Da, 'Db");
+      break;
+    }
+    case FRSP: {
+      Format(instr, "frsp'.   'Dt, 'Db");
+      break;
+    }
+    case FCFID: {
+      Format(instr, "fcfid'.  'Dt, 'Db");
+      break;
+    }
+    case FCTID: {
+      Format(instr, "fctid   'Dt, 'Db");
+      break;
+    }
+    case FCTIDZ: {
+      Format(instr, "fctidz  'Dt, 'Db");
+      break;
+    }
+    case FCTIW: {
+      Format(instr, "fctiw'. 'Dt, 'Db");
+      break;
+    }
+    case FCTIWZ: {
+      Format(instr, "fctiwz'. 'Dt, 'Db");
+      break;
+    }
+    case FMR: {
+      Format(instr, "fmr'.    'Dt, 'Db");
+      break;
+    }
+    case MTFSFI: {
+      Format(instr, "mtfsfi'.  ?,?");
+      break;
+    }
+    case MFFS: {
+      Format(instr, "mffs'.   'Dt");
+      break;
+    }
+    case MTFSF: {
+      Format(instr, "mtfsf'.  'Db ?,?,?");
+      break;
+    }
+    case FABS: {
+      Format(instr, "fabs'.   'Dt, 'Db");
+      break;
+    }
+    case FRIM: {
+      Format(instr, "frim    'Dt, 'Db");
+      break;
+    }
+    case FNEG: {
+      Format(instr, "fneg'.   'Dt, 'Db");
+      break;
+    }
+    default: {
+      Unknown(instr);  // not used by V8
+    }
+  }
+}
+
+
+void Decoder::DecodeExt5(Instruction* instr) {
+  switch (instr->Bits(4, 2) << 2) {
+    case RLDICL: {
+      Format(instr, "rldicl'. 'ra, 'rs, 'sh, 'mb");
+      return;
+    }
+    case RLDICR: {
+      Format(instr, "rldicr'. 'ra, 'rs, 'sh, 'me");
+      return;
+    }
+    case RLDIC: {
+      Format(instr, "rldic'.  'ra, 'rs, 'sh, 'mb");
+      return;
+    }
+    case RLDIMI: {
+      Format(instr, "rldimi'. 'ra, 'rs, 'sh, 'mb");
+      return;
+    }
+  }
+  switch (instr->Bits(4, 1) << 1) {
+    case RLDCL: {
+      Format(instr, "rldcl'.  'ra, 'rs, 'sb, 'mb");
+      return;
+    }
+  }
+  Unknown(instr);  // not used by V8
+}
+
+#undef VERIFIY
+
+// 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_ += SNPrintF(out_buffer_ + out_buffer_pos_, "%08x       ",
+                              instr->InstructionBits());
+
+  switch (instr->OpcodeValue() << 26) {
+    case TWI: {
+      PrintSoftwareInterrupt(instr->SvcValue());
+      break;
+    }
+    case MULLI: {
+      UnknownFormat(instr, "mulli");
+      break;
+    }
+    case SUBFIC: {
+      Format(instr, "subfic  'rt, 'ra, 'int16");
+      break;
+    }
+    case CMPLI: {
+#if V8_TARGET_ARCH_PPC64
+      if (instr->Bit(21)) {
+#endif
+        Format(instr, "cmpli   'ra, 'uint16");
+#if V8_TARGET_ARCH_PPC64
+      } else {
+        Format(instr, "cmplwi  'ra, 'uint16");
+      }
+#endif
+      break;
+    }
+    case CMPI: {
+#if V8_TARGET_ARCH_PPC64
+      if (instr->Bit(21)) {
+#endif
+        Format(instr, "cmpi    'ra, 'int16");
+#if V8_TARGET_ARCH_PPC64
+      } else {
+        Format(instr, "cmpwi   'ra, 'int16");
+      }
+#endif
+      break;
+    }
+    case ADDIC: {
+      Format(instr, "addic   'rt, 'ra, 'int16");
+      break;
+    }
+    case ADDICx: {
+      UnknownFormat(instr, "addicx");
+      break;
+    }
+    case ADDI: {
+      if (instr->RAValue() == 0) {
+        // this is load immediate
+        Format(instr, "li      'rt, 'int16");
+      } else {
+        Format(instr, "addi    'rt, 'ra, 'int16");
+      }
+      break;
+    }
+    case ADDIS: {
+      if (instr->RAValue() == 0) {
+        Format(instr, "lis     'rt, 'int16");
+      } else {
+        Format(instr, "addis   'rt, 'ra, 'int16");
+      }
+      break;
+    }
+    case BCX: {
+      int bo = instr->Bits(25, 21) << 21;
+      int bi = instr->Bits(20, 16);
+      switch (bi) {
+        case 2:
+        case 30:
+          if (BT == bo) {
+            Format(instr, "beq'l'a 'target16");
+            break;
+          }
+          if (BF == bo) {
+            Format(instr, "bne'l'a 'target16");
+            break;
+          }
+          Format(instr, "bc'l'a 'target16");
+          break;
+        case 29:
+          if (BT == bo) {
+            Format(instr, "bgt'l'a 'target16");
+            break;
+          }
+          if (BF == bo) {
+            Format(instr, "ble'l'a 'target16");
+            break;
+          }
+          Format(instr, "bc'l'a 'target16");
+          break;
+        case 28:
+          if (BT == bo) {
+            Format(instr, "blt'l'a 'target16");
+            break;
+          }
+          if (BF == bo) {
+            Format(instr, "bge'l'a 'target16");
+            break;
+          }
+          Format(instr, "bc'l'a 'target16");
+          break;
+        default:
+          Format(instr, "bc'l'a 'target16");
+          break;
+      }
+      break;
+    }
+    case SC: {
+      UnknownFormat(instr, "sc");
+      break;
+    }
+    case BX: {
+      Format(instr, "b'l'a 'target26");
+      break;
+    }
+    case EXT1: {
+      DecodeExt1(instr);
+      break;
+    }
+    case RLWIMIX: {
+      Format(instr, "rlwimi'. 'ra, 'rs, 'sh, 'me, 'mb");
+      break;
+    }
+    case RLWINMX: {
+      Format(instr, "rlwinm'. 'ra, 'rs, 'sh, 'me, 'mb");
+      break;
+    }
+    case RLWNMX: {
+      Format(instr, "rlwnm'.  'ra, 'rs, 'rb, 'me, 'mb");
+      break;
+    }
+    case ORI: {
+      Format(instr, "ori     'ra, 'rs, 'uint16");
+      break;
+    }
+    case ORIS: {
+      Format(instr, "oris    'ra, 'rs, 'uint16");
+      break;
+    }
+    case XORI: {
+      Format(instr, "xori    'ra, 'rs, 'uint16");
+      break;
+    }
+    case XORIS: {
+      Format(instr, "xoris   'ra, 'rs, 'uint16");
+      break;
+    }
+    case ANDIx: {
+      Format(instr, "andi.   'ra, 'rs, 'uint16");
+      break;
+    }
+    case ANDISx: {
+      Format(instr, "andis.  'ra, 'rs, 'uint16");
+      break;
+    }
+    case EXT2: {
+      DecodeExt2(instr);
+      break;
+    }
+    case LWZ: {
+      Format(instr, "lwz     'rt, 'int16('ra)");
+      break;
+    }
+    case LWZU: {
+      Format(instr, "lwzu    'rt, 'int16('ra)");
+      break;
+    }
+    case LBZ: {
+      Format(instr, "lbz     'rt, 'int16('ra)");
+      break;
+    }
+    case LBZU: {
+      Format(instr, "lbzu    'rt, 'int16('ra)");
+      break;
+    }
+    case STW: {
+      Format(instr, "stw     'rs, 'int16('ra)");
+      break;
+    }
+    case STWU: {
+      Format(instr, "stwu    'rs, 'int16('ra)");
+      break;
+    }
+    case STB: {
+      Format(instr, "stb     'rs, 'int16('ra)");
+      break;
+    }
+    case STBU: {
+      Format(instr, "stbu    'rs, 'int16('ra)");
+      break;
+    }
+    case LHZ: {
+      Format(instr, "lhz     'rt, 'int16('ra)");
+      break;
+    }
+    case LHZU: {
+      Format(instr, "lhzu    'rt, 'int16('ra)");
+      break;
+    }
+    case LHA: {
+      Format(instr, "lha     'rt, 'int16('ra)");
+      break;
+    }
+    case LHAU: {
+      Format(instr, "lhau    'rt, 'int16('ra)");
+      break;
+    }
+    case STH: {
+      Format(instr, "sth 'rs, 'int16('ra)");
+      break;
+    }
+    case STHU: {
+      Format(instr, "sthu 'rs, 'int16('ra)");
+      break;
+    }
+    case LMW: {
+      UnknownFormat(instr, "lmw");
+      break;
+    }
+    case STMW: {
+      UnknownFormat(instr, "stmw");
+      break;
+    }
+    case LFS: {
+      Format(instr, "lfs     'Dt, 'int16('ra)");
+      break;
+    }
+    case LFSU: {
+      Format(instr, "lfsu    'Dt, 'int16('ra)");
+      break;
+    }
+    case LFD: {
+      Format(instr, "lfd     'Dt, 'int16('ra)");
+      break;
+    }
+    case LFDU: {
+      Format(instr, "lfdu    'Dt, 'int16('ra)");
+      break;
+    }
+    case STFS: {
+      Format(instr, "stfs    'Dt, 'int16('ra)");
+      break;
+    }
+    case STFSU: {
+      Format(instr, "stfsu   'Dt, 'int16('ra)");
+      break;
+    }
+    case STFD: {
+      Format(instr, "stfd    'Dt, 'int16('ra)");
+      break;
+    }
+    case STFDU: {
+      Format(instr, "stfdu   'Dt, 'int16('ra)");
+      break;
+    }
+    case EXT3:
+    case EXT4: {
+      DecodeExt4(instr);
+      break;
+    }
+    case EXT5: {
+      DecodeExt5(instr);
+      break;
+    }
+#if V8_TARGET_ARCH_PPC64
+    case LD: {
+      switch (instr->Bits(1, 0)) {
+        case 0:
+          Format(instr, "ld      'rt, 'd('ra)");
+          break;
+        case 1:
+          Format(instr, "ldu     'rt, 'd('ra)");
+          break;
+        case 2:
+          Format(instr, "lwa     'rt, 'd('ra)");
+          break;
+      }
+      break;
+    }
+    case STD: {  // could be STD or STDU
+      if (instr->Bit(0) == 0) {
+        Format(instr, "std     'rs, 'd('ra)");
+      } else {
+        Format(instr, "stdu    'rs, 'd('ra)");
+      }
+      break;
+    }
+#endif
+
+    case FAKE_OPCODE: {
+      if (instr->Bits(MARKER_SUBOPCODE_BIT, MARKER_SUBOPCODE_BIT) == 1) {
+        int marker_code = instr->Bits(STUB_MARKER_HIGH_BIT, 0);
+        DCHECK(marker_code < F_NEXT_AVAILABLE_STUB_MARKER);
+        MarkerFormat(instr, "stub-marker ", marker_code);
+      } else {
+        int fake_opcode = instr->Bits(FAKE_OPCODE_HIGH_BIT, 0);
+        MarkerFormat(instr, "faker-opcode ", fake_opcode);
+      }
+      break;
+    }
+    default: {
+      Unknown(instr);
+      break;
+    }
+  }
+
+  return Instruction::kInstrSize;
+}
+}
+}  // namespace v8::internal
+
+
+//------------------------------------------------------------------------------
+
+namespace disasm {
+
+
+const char* NameConverter::NameOfAddress(byte* addr) const {
+  v8::internal::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::NameOfByteCPURegister(int reg) const {
+  UNREACHABLE();  // PPC does not have the concept of a byte register
+  return "nobytereg";
+}
+
+
+const char* NameConverter::NameOfXMMRegister(int reg) const {
+  UNREACHABLE();  // PPC does not have any XMM registers
+  return "noxmmreg";
+}
+
+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 PPC 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);
+    v8::internal::PrintF(f, "%p    %08x      %s\n", prev_pc,
+                         *reinterpret_cast<int32_t*>(prev_pc), buffer.start());
+  }
+}
+
+
+}  // namespace disasm
+
+#endif  // V8_TARGET_ARCH_PPC