Contribution of PowerPC port.

src/ppc/constants-ppc.h

+// Copyright 2011 the V8 project authors. All rights reserved.
+//
+// Copyright IBM Corp. 2012, 2013. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_PPC_CONSTANTS_PPC_H_
+#define V8_PPC_CONSTANTS_PPC_H_
+
+namespace v8 {
+namespace internal {
+
+// Number of registers
+const int kNumRegisters = 32;
+
+// FP support.
+const int kNumFPDoubleRegisters = 32;
+const int kNumFPRegisters = kNumFPDoubleRegisters;
+
+const int kNoRegister = -1;
+
+// sign-extend the least significant 16-bits of value <imm>
+#define SIGN_EXT_IMM16(imm) ((static_cast<int>(imm) << 16) >> 16)
+
+// sign-extend the least significant 26-bits of value <imm>
+#define SIGN_EXT_IMM26(imm) ((static_cast<int>(imm) << 6) >> 6)
+
+// -----------------------------------------------------------------------------
+// Conditions.
+
+// Defines constants and accessor classes to assemble, disassemble and
+// simulate PPC instructions.
+//
+// Section references in the code refer to the "PowerPC Microprocessor
+// Family: The Programmer.s Reference Guide" from 10/95
+// https://www-01.ibm.com/chips/techlib/techlib.nsf/techdocs/852569B20050FF778525699600741775/$file/prg.pdf
+//
+
+// Constants for specific fields are defined in their respective named enums.
+// General constants are in an anonymous enum in class Instr.
+enum Condition {
+  kNoCondition = -1,
+  eq         =  0,         // Equal.
+  ne         =  1,         // Not equal.
+  ge         =  2,         // Greater or equal.
+  lt         =  3,         // Less than.
+  gt         =  4,         // Greater than.
+  le         =  5,         // Less then or equal
+  unordered  =  6,         // Floating-point unordered
+  ordered    =  7,
+  overflow   =  8,         // Summary overflow
+  nooverflow =  9,
+  al         = 10          // Always.
+};
+
+
+inline Condition NegateCondition(Condition cond) {
+  DCHECK(cond != al);
+  return static_cast<Condition>(cond ^ ne);
+}
+
+
+// Commute a condition such that {a cond b == b cond' a}.
+inline Condition CommuteCondition(Condition cond) {
+  switch (cond) {
+    case lt:
+      return gt;
+    case gt:
+      return lt;
+    case ge:
+      return le;
+    case le:
+      return ge;
+    default:
+      return cond;
+  }
+}
+
+// -----------------------------------------------------------------------------
+// Instructions encoding.
+
+// Instr is merely used by the Assembler to distinguish 32bit integers
+// representing instructions from usual 32 bit values.
+// Instruction objects are pointers to 32bit values, and provide methods to
+// access the various ISA fields.
+typedef int32_t Instr;
+
+// Opcodes as defined in section 4.2 table 34 (32bit PowerPC)
+enum Opcode {
+  TWI     =  3 << 26,  // Trap Word Immediate
+  MULLI   =  7 << 26,  // Multiply Low Immediate
+  SUBFIC  =  8 << 26,  // Subtract from Immediate Carrying
+  CMPLI   = 10 << 26,  // Compare Logical Immediate
+  CMPI    = 11 << 26,  // Compare Immediate
+  ADDIC   = 12 << 26,  // Add Immediate Carrying
+  ADDICx  = 13 << 26,  // Add Immediate Carrying and Record
+  ADDI    = 14 << 26,  // Add Immediate
+  ADDIS   = 15 << 26,  // Add Immediate Shifted
+  BCX     = 16 << 26,  // Branch Conditional
+  SC      = 17 << 26,  // System Call
+  BX      = 18 << 26,  // Branch
+  EXT1    = 19 << 26,  // Extended code set 1
+  RLWIMIX = 20 << 26,  // Rotate Left Word Immediate then Mask Insert
+  RLWINMX = 21 << 26,  // Rotate Left Word Immediate then AND with Mask
+  RLWNMX  = 23 << 26,  // Rotate Left Word then AND with Mask
+  ORI     = 24 << 26,  // OR Immediate
+  ORIS    = 25 << 26,  // OR Immediate Shifted
+  XORI    = 26 << 26,  // XOR Immediate
+  XORIS   = 27 << 26,  // XOR Immediate Shifted
+  ANDIx   = 28 << 26,  // AND Immediate
+  ANDISx  = 29 << 26,  // AND Immediate Shifted
+  EXT5    = 30 << 26,  // Extended code set 5 - 64bit only
+  EXT2    = 31 << 26,  // Extended code set 2
+  LWZ     = 32 << 26,  // Load Word and Zero
+  LWZU    = 33 << 26,  // Load Word with Zero Update
+  LBZ     = 34 << 26,  // Load Byte and Zero
+  LBZU    = 35 << 26,  // Load Byte and Zero with Update
+  STW     = 36 << 26,  // Store
+  STWU    = 37 << 26,  // Store Word with Update
+  STB     = 38 << 26,  // Store Byte
+  STBU    = 39 << 26,  // Store Byte with Update
+  LHZ     = 40 << 26,  // Load Half and Zero
+  LHZU    = 41 << 26,  // Load Half and Zero with Update
+  LHA     = 42 << 26,  // Load Half Algebraic
+  LHAU    = 43 << 26,  // Load Half Algebraic with Update
+  STH     = 44 << 26,  // Store Half
+  STHU    = 45 << 26,  // Store Half with Update
+  LMW     = 46 << 26,  // Load Multiple Word
+  STMW    = 47 << 26,  // Store Multiple Word
+  LFS     = 48 << 26,  // Load Floating-Point Single
+  LFSU    = 49 << 26,  // Load Floating-Point Single with Update
+  LFD     = 50 << 26,  // Load Floating-Point Double
+  LFDU    = 51 << 26,  // Load Floating-Point Double with Update
+  STFS    = 52 << 26,  // Store Floating-Point Single
+  STFSU   = 53 << 26,  // Store Floating-Point Single with Update
+  STFD    = 54 << 26,  // Store Floating-Point Double
+  STFDU   = 55 << 26,  // Store Floating-Point Double with Update
+  LD      = 58 << 26,  // Load Double Word
+  EXT3    = 59 << 26,  // Extended code set 3
+  STD     = 62 << 26,  // Store Double Word (optionally with Update)
+  EXT4    = 63 << 26   // Extended code set 4
+};
+
+// Bits 10-1
+enum OpcodeExt1 {
+  MCRF   = 0 << 1,    // Move Condition Register Field
+  BCLRX  = 16 << 1,   // Branch Conditional Link Register
+  CRNOR  = 33 << 1,   // Condition Register NOR)
+  RFI    = 50 << 1,   // Return from Interrupt
+  CRANDC = 129 << 1,  // Condition Register AND with Complement
+  ISYNC  = 150 << 1,  // Instruction Synchronize
+  CRXOR  = 193 << 1,  // Condition Register XOR
+  CRNAND = 225 << 1,  // Condition Register NAND
+  CRAND  = 257 << 1,  // Condition Register AND
+  CREQV  = 289 << 1,  // Condition Register Equivalent
+  CRORC  = 417 << 1,  // Condition Register OR with Complement
+  CROR   = 449 << 1,  // Condition Register OR
+  BCCTRX = 528 << 1   // Branch Conditional to Count Register
+};
+
+// Bits 9-1 or 10-1
+enum OpcodeExt2 {
+  CMP = 0 << 1,
+  TW = 4 << 1,
+  SUBFCX = 8 << 1,
+  ADDCX = 10 << 1,
+  MULHWUX = 11 << 1,
+  MFCR = 19 << 1,
+  LWARX = 20 << 1,
+  LDX = 21 << 1,
+  LWZX = 23 << 1,    // load word zero w/ x-form
+  SLWX = 24 << 1,
+  CNTLZWX = 26 << 1,
+  SLDX = 27 << 1,
+  ANDX = 28 << 1,
+  CMPL = 32 << 1,
+  SUBFX = 40 << 1,
+  MFVSRD = 51 << 1,  // Move From VSR Doubleword
+  LDUX = 53 << 1,
+  DCBST = 54 << 1,
+  LWZUX = 55 << 1,   // load word zero w/ update x-form
+  CNTLZDX = 58 << 1,
+  ANDCX = 60 << 1,
+  MULHWX = 75 << 1,
+  DCBF = 86 << 1,
+  LBZX = 87 << 1,    // load byte zero w/ x-form
+  NEGX = 104 << 1,
+  MFVSRWZ = 115 << 1,  // Move From VSR Word And Zero
+  LBZUX = 119 << 1,  // load byte zero w/ update x-form
+  NORX = 124 << 1,
+  SUBFEX = 136 << 1,
+  ADDEX = 138 << 1,
+  STDX = 149 << 1,
+  STWX = 151 << 1,    // store word w/ x-form
+  MTVSRD = 179 << 1,  // Move To VSR Doubleword
+  STDUX = 181 << 1,
+  STWUX = 183 << 1,   // store word w/ update x-form
+/*
+  MTCRF
+  MTMSR
+  STWCXx
+  SUBFZEX
+*/
+  ADDZEX = 202 << 1,  // Add to Zero Extended
+/*
+  MTSR
+*/
+  MTVSRWA = 211 << 1,  // Move To VSR Word Algebraic
+  STBX = 215 << 1,    // store byte w/ x-form
+  MULLD  = 233 << 1,  // Multiply Low Double Word
+  MULLW  = 235 << 1,  // Multiply Low Word
+  MTVSRWZ = 243 << 1,  // Move To VSR Word And Zero
+  STBUX = 247 << 1,   // store byte w/ update x-form
+  ADDX = 266 << 1,    // Add
+  LHZX = 279 << 1,    // load half-word zero w/ x-form
+  LHZUX = 311 << 1,   // load half-word zero w/ update x-form
+  LHAX =343 << 1,     // load half-word algebraic w/ x-form
+  LHAUX = 375 << 1,   // load half-word algebraic w/ update x-form
+  XORX = 316 << 1,    // Exclusive OR
+  MFSPR = 339 <<1,    // Move from Special-Purpose-Register
+  STHX = 407 << 1,    // store half-word w/ x-form
+  STHUX = 439 << 1,   // store half-word w/ update x-form
+  ORX = 444 << 1,     // Or
+  MTSPR = 467 <<1,    // Move to Special-Purpose-Register
+  DIVD  = 489 << 1,   // Divide Double Word
+  DIVW  = 491 << 1,   // Divide Word
+
+  // Below represent bits 10-1  (any value >= 512)
+  LFSX = 535 << 1,    // load float-single w/ x-form
+  SRWX = 536 << 1,    // Shift Right Word
+  SRDX = 539 << 1,    // Shift Right Double Word
+  LFSUX = 567 << 1,   // load float-single w/ update x-form
+  SYNC = 598 << 1,    // Synchronize
+  LFDX = 599 << 1,    // load float-double w/ x-form
+  LFDUX = 631 << 1,   // load float-double w/ update X-form
+  STFSX = 663 << 1,   // store float-single w/ x-form
+  STFSUX = 695 << 1,  // store float-single w/ update x-form
+  STFDX = 727 << 1,   // store float-double w/ x-form
+  STFDUX = 759 << 1,  // store float-double w/ update x-form
+  SRAW = 792 << 1,    // Shift Right Algebraic Word
+  SRAD = 794 << 1,    // Shift Right Algebraic Double Word
+  SRAWIX = 824 << 1,  // Shift Right Algebraic Word Immediate
+  SRADIX = 413 << 2,  // Shift Right Algebraic Double Word Immediate
+  EXTSH = 922 << 1,   // Extend Sign Halfword
+  EXTSB = 954 << 1,   // Extend Sign Byte
+  ICBI = 982 << 1,    // Instruction Cache Block Invalidate
+  EXTSW = 986 << 1    // Extend Sign Word
+};
+
+// Some use Bits 10-1 and other only 5-1 for the opcode
+enum OpcodeExt4 {
+  // Bits 5-1
+  FDIV   = 18 << 1,   // Floating Divide
+  FSUB   = 20 << 1,   // Floating Subtract
+  FADD   = 21 << 1,   // Floating Add
+  FSQRT  = 22 << 1,   // Floating Square Root
+  FSEL   = 23 << 1,   // Floating Select
+  FMUL   = 25 << 1,   // Floating Multiply
+  FMSUB  = 28 << 1,   // Floating Multiply-Subtract
+  FMADD  = 29 << 1,   // Floating Multiply-Add
+
+  // Bits 10-1
+  FCMPU  =   0 << 1,  // Floating Compare Unordered
+  FRSP   =  12 << 1,  // Floating-Point Rounding
+  FCTIW  =  14 << 1,  // Floating Convert to Integer Word X-form
+  FCTIWZ =  15 << 1,  // Floating Convert to Integer Word with Round to Zero
+  FNEG   =  40 << 1,  // Floating Negate
+  MCRFS  =  64 << 1,  // Move to Condition Register from FPSCR
+  FMR    =  72 << 1,  // Floating Move Register
+  MTFSFI = 134 << 1,  // Move to FPSCR Field Immediate
+  FABS   = 264 << 1,  // Floating Absolute Value
+  FRIM   = 488 << 1,  // Floating Round to Integer Minus
+  MFFS   = 583 << 1,  // move from FPSCR x-form
+  MTFSF  = 711 << 1,  // move to FPSCR fields XFL-form
+  FCFID  = 846 << 1,  // Floating convert from integer doubleword
+  FCTID  = 814 << 1,  // Floating convert from integer doubleword
+  FCTIDZ = 815 << 1   // Floating convert from integer doubleword
+};
+
+enum OpcodeExt5 {
+  // Bits 4-2
+  RLDICL = 0 << 1,    // Rotate Left Double Word Immediate then Clear Left
+  RLDICR = 2 << 1,    // Rotate Left Double Word Immediate then Clear Right
+  RLDIC  = 4 << 1,    // Rotate Left Double Word Immediate then Clear
+  RLDIMI = 6 << 1,    // Rotate Left Double Word Immediate then Mask Insert
+  // Bits 4-1
+  RLDCL  = 8 << 1,    // Rotate Left Double Word then Clear Left
+  RLDCR  = 9 << 1     // Rotate Left Double Word then Clear Right
+};
+
+// Instruction encoding bits and masks.
+enum {
+  // Instruction encoding bit
+  B1  = 1 << 1,
+  B4  = 1 << 4,
+  B5  = 1 << 5,
+  B7  = 1 << 7,
+  B8  = 1 << 8,
+  B9  = 1 << 9,
+  B12 = 1 << 12,
+  B18 = 1 << 18,
+  B19 = 1 << 19,
+  B20 = 1 << 20,
+  B22 = 1 << 22,
+  B23 = 1 << 23,
+  B24 = 1 << 24,
+  B25 = 1 << 25,
+  B26 = 1 << 26,
+  B27 = 1 << 27,
+  B28 = 1 << 28,
+
+  B6  = 1 << 6,
+  B10 = 1 << 10,
+  B11 = 1 << 11,
+  B16 = 1 << 16,
+  B17 = 1 << 17,
+  B21 = 1 << 21,
+
+  // Instruction bit masks
+  kCondMask   = 0x1F << 21,
+  kOff12Mask  = (1 << 12) - 1,
+  kImm24Mask  = (1 << 24) - 1,
+  kOff16Mask  = (1 << 16) - 1,
+  kImm16Mask  = (1 << 16) - 1,
+  kImm26Mask  = (1 << 26) - 1,
+  kBOfieldMask = 0x1f << 21,
+  kOpcodeMask = 0x3f << 26,
+  kExt1OpcodeMask = 0x3ff << 1,
+  kExt2OpcodeMask = 0x1f << 1,
+  kExt5OpcodeMask = 0x3 << 2,
+  kBOMask = 0x1f << 21,
+  kBIMask = 0x1F << 16,
+  kBDMask = 0x14 << 2,
+  kAAMask = 0x01 << 1,
+  kLKMask = 0x01,
+  kRCMask = 0x01,
+  kTOMask = 0x1f << 21
+};
+
+// the following is to differentiate different faked opcodes for
+// the BOGUS PPC instruction we invented (when bit 25 is 0) or to mark
+// different stub code (when bit 25 is 1)
+//   - use primary opcode 1 for undefined instruction
+//   - use bit 25 to indicate whether the opcode is for fake-arm
+//     instr or stub-marker
+//   - use the least significant 6-bit to indicate FAKE_OPCODE_T or
+//     MARKER_T
+#define FAKE_OPCODE 1 << 26
+#define MARKER_SUBOPCODE_BIT 25
+#define MARKER_SUBOPCODE 1 << MARKER_SUBOPCODE_BIT
+#define FAKER_SUBOPCODE 0 << MARKER_SUBOPCODE_BIT
+
+enum FAKE_OPCODE_T {
+  fBKPT = 14,
+
+  fLastFaker  // can't be more than 128 (2^^7)
+};
+#define FAKE_OPCODE_HIGH_BIT 7  // fake opcode has to fall into bit 0~7
+#define F_NEXT_AVAILABLE_STUB_MARKER 369  // must be less than 2^^9 (512)
+#define STUB_MARKER_HIGH_BIT 9  // stub marker has to fall into bit 0~9
+// -----------------------------------------------------------------------------
+// Addressing modes and instruction variants.
+
+// Overflow Exception
+enum OEBit {
+  SetOE   = 1 << 10,  // Set overflow exception
+  LeaveOE = 0 << 10   // No overflow exception
+};
+
+// Record bit
+enum RCBit {  // Bit 0
+  SetRC   = 1,  // LT,GT,EQ,SO
+  LeaveRC = 0   // None
+};
+
+// Link bit
+enum LKBit {  // Bit 0
+  SetLK   = 1,  // Load effective address of next instruction
+  LeaveLK = 0   // No action
+};
+
+enum BOfield {  // Bits 25-21
+  DCBNZF =  0 << 21,  // Decrement CTR; branch if CTR != 0 and condition false
+  DCBEZF =  2 << 21,  // Decrement CTR; branch if CTR == 0 and condition false
+  BF     =  4 << 21,  // Branch if condition false
+  DCBNZT =  8 << 21,  // Decrement CTR; branch if CTR != 0 and condition true
+  DCBEZT = 10 << 21,  // Decrement CTR; branch if CTR == 0 and condition true
+  BT     = 12 << 21,  // Branch if condition true
+  DCBNZ  = 16 << 21,  // Decrement CTR; branch if CTR != 0
+  DCBEZ  = 18 << 21,  // Decrement CTR; branch if CTR == 0
+  BA     = 20 << 21   // Branch always
+};
+
+#if V8_OS_AIX
+#undef CR_LT
+#undef CR_GT
+#undef CR_EQ
+#undef CR_SO
+#endif
+
+enum CRBit {
+  CR_LT = 0,
+  CR_GT = 1,
+  CR_EQ = 2,
+  CR_SO = 3,
+  CR_FU = 3
+};
+
+#define CRWIDTH 4
+
+// -----------------------------------------------------------------------------
+// Supervisor Call (svc) specific support.
+
+// Special Software Interrupt codes when used in the presence of the PPC
+// simulator.
+// svc (formerly swi) provides a 24bit immediate value. Use bits 22:0 for
+// standard SoftwareInterrupCode. Bit 23 is reserved for the stop feature.
+enum SoftwareInterruptCodes {
+  // transition to C code
+  kCallRtRedirected= 0x10,
+  // break point
+  kBreakpoint= 0x821008,  // bits23-0 of 0x7d821008 = twge r2, r2
+  // stop
+  kStopCode = 1 << 23,
+  // info
+  kInfo     = 0x9ff808    // bits23-0 of 0x7d9ff808 = twge r31, r31
+};
+const uint32_t kStopCodeMask = kStopCode - 1;
+const uint32_t kMaxStopCode = kStopCode - 1;
+const int32_t  kDefaultStopCode = -1;
+
+// FP rounding modes.
+enum FPRoundingMode {
+  RN = 0,   // Round to Nearest.
+  RZ = 1,   // Round towards zero.
+  RP = 2,   // Round towards Plus Infinity.
+  RM = 3,   // Round towards Minus Infinity.
+
+  // Aliases.
+  kRoundToNearest = RN,
+  kRoundToZero = RZ,
+  kRoundToPlusInf = RP,
+  kRoundToMinusInf = RM
+};
+
+const uint32_t kFPRoundingModeMask = 3;
+
+enum CheckForInexactConversion {
+  kCheckForInexactConversion,
+  kDontCheckForInexactConversion
+};
+
+// -----------------------------------------------------------------------------
+// Specific instructions, constants, and masks.
+// These constants are declared in assembler-arm.cc, as they use named registers
+// and other constants.
+
+
+// add(sp, sp, 4) instruction (aka Pop())
+extern const Instr kPopInstruction;
+
+// str(r, MemOperand(sp, 4, NegPreIndex), al) instruction (aka push(r))
+// register r is not encoded.
+extern const Instr kPushRegPattern;
+
+// ldr(r, MemOperand(sp, 4, PostIndex), al) instruction (aka pop(r))
+// register r is not encoded.
+extern const Instr kPopRegPattern;
+
+// use TWI to indicate redirection call for simulation mode
+const Instr rtCallRedirInstr = TWI;
+
+// -----------------------------------------------------------------------------
+// Instruction abstraction.
+
+// The class Instruction enables access to individual fields defined in the PPC
+// architecture instruction set encoding.
+// Note that the Assembler uses typedef int32_t Instr.
+//
+// Example: Test whether the instruction at ptr does set the condition code
+// bits.
+//
+// bool InstructionSetsConditionCodes(byte* ptr) {
+//   Instruction* instr = Instruction::At(ptr);
+//   int type = instr->TypeValue();
+//   return ((type == 0) || (type == 1)) && instr->HasS();
+// }
+//
+class Instruction {
+ public:
+  enum {
+    kInstrSize = 4,
+    kInstrSizeLog2 = 2,
+    kPCReadOffset = 8
+  };
+
+  // Helper macro to define static accessors.
+  // We use the cast to char* trick to bypass the strict anti-aliasing rules.
+  #define DECLARE_STATIC_TYPED_ACCESSOR(return_type, Name)                     \
+    static inline return_type Name(Instr instr) {                              \
+      char* temp = reinterpret_cast<char*>(&instr);                            \
+      return reinterpret_cast<Instruction*>(temp)->Name();                     \
+    }
+
+  #define DECLARE_STATIC_ACCESSOR(Name) DECLARE_STATIC_TYPED_ACCESSOR(int, Name)
+
+  // Get the raw instruction bits.
+  inline Instr InstructionBits() const {
+    return *reinterpret_cast<const Instr*>(this);
+  }
+
+  // Set the raw instruction bits to value.
+  inline void SetInstructionBits(Instr value) {
+    *reinterpret_cast<Instr*>(this) = value;
+  }
+
+  // Read one particular bit out of the instruction bits.
+  inline int Bit(int nr) const {
+    return (InstructionBits() >> nr) & 1;
+  }
+
+  // Read a bit field's value out of the instruction bits.
+  inline int Bits(int hi, int lo) const {
+    return (InstructionBits() >> lo) & ((2 << (hi - lo)) - 1);
+  }
+
+  // Read a bit field out of the instruction bits.
+  inline int BitField(int hi, int lo) const {
+    return InstructionBits() & (((2 << (hi - lo)) - 1) << lo);
+  }
+
+  // Static support.
+
+  // Read one particular bit out of the instruction bits.
+  static inline int Bit(Instr instr, int nr) {
+    return (instr >> nr) & 1;
+  }
+
+  // Read the value of a bit field out of the instruction bits.
+  static inline int Bits(Instr instr, int hi, int lo) {
+    return (instr >> lo) & ((2 << (hi - lo)) - 1);
+  }
+
+
+  // Read a bit field out of the instruction bits.
+  static inline int BitField(Instr instr, int hi, int lo) {
+    return instr & (((2 << (hi - lo)) - 1) << lo);
+  }
+
+  inline int RSValue() const { return Bits(25, 21); }
+  inline int RTValue() const { return Bits(25, 21); }
+  inline int RAValue() const { return Bits(20, 16); }
+  DECLARE_STATIC_ACCESSOR(RAValue);
+  inline int RBValue() const { return Bits(15, 11); }
+  DECLARE_STATIC_ACCESSOR(RBValue);
+  inline int RCValue() const { return Bits(10, 6); }
+  DECLARE_STATIC_ACCESSOR(RCValue);
+
+  inline int OpcodeValue() const {
+    return static_cast<Opcode>(Bits(31, 26));
+  }
+  inline Opcode OpcodeField() const {
+    return static_cast<Opcode>(BitField(24, 21));
+  }
+
+  // Fields used in Software interrupt instructions
+  inline SoftwareInterruptCodes SvcValue() const {
+    return static_cast<SoftwareInterruptCodes>(Bits(23, 0));
+  }
+
+  // Instructions are read of out a code stream. The only way to get a
+  // reference to an instruction is to convert a pointer. There is no way
+  // to allocate or create instances of class Instruction.
+  // Use the At(pc) function to create references to Instruction.
+  static Instruction* At(byte* pc) {
+    return reinterpret_cast<Instruction*>(pc);
+  }
+
+
+ private:
+  // We need to prevent the creation of instances of class Instruction.
+  DISALLOW_IMPLICIT_CONSTRUCTORS(Instruction);
+};
+
+
+// Helper functions for converting between register numbers and names.
+class Registers {
+ public:
+  // Return the name of the register.
+  static const char* Name(int reg);
+
+  // Lookup the register number for the name provided.
+  static int Number(const char* name);
+
+  struct RegisterAlias {
+    int reg;
+    const char* name;
+  };
+
+ private:
+  static const char* names_[kNumRegisters];
+  static const RegisterAlias aliases_[];
+};
+
+// Helper functions for converting between FP register numbers and names.
+class FPRegisters {
+ public:
+  // Return the name of the register.
+  static const char* Name(int reg);
+
+  // Lookup the register number for the name provided.
+  static int Number(const char* name);
+
+ private:
+  static const char* names_[kNumFPRegisters];
+};
+
+} }  // namespace v8::internal
+
+#endif  // V8_PPC_CONSTANTS_PPC_H_