runtime/vm/assembler_ia32.h

// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

#ifndef VM_ASSEMBLER_IA32_H_
#define VM_ASSEMBLER_IA32_H_

#ifndef VM_ASSEMBLER_H_
#error Do not include assembler_ia32.h directly; use assembler.h instead.
#endif

#include "platform/assert.h"
#include "platform/utils.h"
#include "vm/constants_ia32.h"

namespace dart {

// Forward declarations.
class RuntimeEntry;
class StubEntry;

class Immediate : public ValueObject {
 public:
  explicit Immediate(int32_t value) : value_(value) { }

  Immediate(const Immediate& other) : ValueObject(), value_(other.value_) { }

  int32_t value() const { return value_; }

  bool is_int8() const { return Utils::IsInt(8, value_); }
  bool is_uint8() const { return Utils::IsUint(8, value_); }
  bool is_uint16() const { return Utils::IsUint(16, value_); }

 private:
  const int32_t value_;

  // TODO(5411081): Add DISALLOW_COPY_AND_ASSIGN(Immediate) once the mac
  // build issue is resolved.
  // And remove the unnecessary copy constructor.
};


class Operand : public ValueObject {
 public:
  uint8_t mod() const {
    return (encoding_at(0) >> 6) & 3;
  }

  Register rm() const {
    return static_cast<Register>(encoding_at(0) & 7);
  }

  ScaleFactor scale() const {
    return static_cast<ScaleFactor>((encoding_at(1) >> 6) & 3);
  }

  Register index() const {
    return static_cast<Register>((encoding_at(1) >> 3) & 7);
  }

  Register base() const {
    return static_cast<Register>(encoding_at(1) & 7);
  }

  int8_t disp8() const {
    ASSERT(length_ >= 2);
    return static_cast<int8_t>(encoding_[length_ - 1]);
  }

  int32_t disp32() const {
    ASSERT(length_ >= 5);
    return bit_copy<int32_t>(encoding_[length_ - 4]);
  }

  Operand(const Operand& other) : ValueObject(), length_(other.length_) {
    memmove(&encoding_[0], &other.encoding_[0], other.length_);
  }

  Operand& operator=(const Operand& other) {
    length_ = other.length_;
    memmove(&encoding_[0], &other.encoding_[0], other.length_);
    return *this;
  }

  bool Equals(const Operand& other) const {
    if (length_ != other.length_) return false;
    for (uint8_t i = 0; i < length_; i++) {
      if (encoding_[i] != other.encoding_[i]) return false;
    }
    return true;
  }

 protected:
  Operand() : length_(0) { }  // Needed by subclass Address.

  void SetModRM(int mod, Register rm) {
    ASSERT((mod & ~3) == 0);
    encoding_[0] = (mod << 6) | rm;
    length_ = 1;
  }

  void SetSIB(ScaleFactor scale, Register index, Register base) {
    ASSERT(length_ == 1);
    ASSERT((scale & ~3) == 0);
    encoding_[1] = (scale << 6) | (index << 3) | base;
    length_ = 2;
  }

  void SetDisp8(int8_t disp) {
    ASSERT(length_ == 1 || length_ == 2);
    encoding_[length_++] = static_cast<uint8_t>(disp);
  }

  void SetDisp32(int32_t disp) {
    ASSERT(length_ == 1 || length_ == 2);
    intptr_t disp_size = sizeof(disp);
    memmove(&encoding_[length_], &disp, disp_size);
    length_ += disp_size;
  }

 private:
  uint8_t length_;
  uint8_t encoding_[6];
  uint8_t padding_;

  explicit Operand(Register reg) { SetModRM(3, reg); }

  // Get the operand encoding byte at the given index.
  uint8_t encoding_at(intptr_t index) const {
    ASSERT(index >= 0 && index < length_);
    return encoding_[index];
  }

  // Returns whether or not this operand is really the given register in
  // disguise. Used from the assembler to generate better encodings.
  bool IsRegister(Register reg) const {
    return ((encoding_[0] & 0xF8) == 0xC0)  // Addressing mode is register only.
        && ((encoding_[0] & 0x07) == reg);  // Register codes match.
  }

  friend class Assembler;
};


class Address : public Operand {
 public:
  Address(Register base, int32_t disp) {
    if (disp == 0 && base != EBP) {
      SetModRM(0, base);
      if (base == ESP) SetSIB(TIMES_1, ESP, base);
    } else if (Utils::IsInt(8, disp)) {
      SetModRM(1, base);
      if (base == ESP) SetSIB(TIMES_1, ESP, base);
      SetDisp8(disp);
    } else {
      SetModRM(2, base);
      if (base == ESP) SetSIB(TIMES_1, ESP, base);
      SetDisp32(disp);
    }
  }

  Address(Register index, ScaleFactor scale, int32_t disp) {
    ASSERT(index != ESP);  // Illegal addressing mode.
    SetModRM(0, ESP);
    SetSIB(scale, index, EBP);
    SetDisp32(disp);
  }

  // This addressing mode does not exist.
  Address(Register index, ScaleFactor scale, Register r);

  Address(Register base, Register index, ScaleFactor scale, int32_t disp) {
    ASSERT(index != ESP);  // Illegal addressing mode.
    if (disp == 0 && base != EBP) {
      SetModRM(0, ESP);
      SetSIB(scale, index, base);
    } else if (Utils::IsInt(8, disp)) {
      SetModRM(1, ESP);
      SetSIB(scale, index, base);
      SetDisp8(disp);
    } else {
      SetModRM(2, ESP);
      SetSIB(scale, index, base);
      SetDisp32(disp);
    }
  }

  // This addressing mode does not exist.
  Address(Register base, Register index, ScaleFactor scale, Register r);

  Address(const Address& other) : Operand(other) { }

  Address& operator=(const Address& other) {
    Operand::operator=(other);
    return *this;
  }

  static Address Absolute(const uword addr) {
    Address result;
    result.SetModRM(0, EBP);
    result.SetDisp32(addr);
    return result;
  }

 private:
  Address() { }  // Needed by Address::Absolute.
};


class FieldAddress : public Address {
 public:
  FieldAddress(Register base, int32_t disp)
      : Address(base, disp - kHeapObjectTag) { }

  // This addressing mode does not exist.
  FieldAddress(Register base, Register r);

  FieldAddress(Register base, Register index, ScaleFactor scale, int32_t disp)
      : Address(base, index, scale, disp - kHeapObjectTag) { }

  // This addressing mode does not exist.
  FieldAddress(Register base, Register index, ScaleFactor scale, Register r);

  FieldAddress(const FieldAddress& other) : Address(other) { }

  FieldAddress& operator=(const FieldAddress& other) {
    Address::operator=(other);
    return *this;
  }
};


class Label : public ValueObject {
 public:
  Label() : position_(0), unresolved_(0) {
#ifdef DEBUG
    for (int i = 0; i < kMaxUnresolvedBranches; i++) {
      unresolved_near_positions_[i] = -1;
    }
#endif  // DEBUG
  }

  ~Label() {
    // Assert if label is being destroyed with unresolved branches pending.
    ASSERT(!IsLinked());
    ASSERT(!HasNear());
  }

  // Returns the position for bound labels. Cannot be used for unused or linked
  // labels.
  intptr_t Position() const {
    ASSERT(IsBound());
    return -position_ - kWordSize;
  }

  intptr_t LinkPosition() const {
    ASSERT(IsLinked());
    return position_ - kWordSize;
  }

  intptr_t NearPosition() {
    ASSERT(HasNear());
    return unresolved_near_positions_[--unresolved_];
  }

  bool IsBound() const { return position_ < 0; }
  bool IsUnused() const { return (position_ == 0) && (unresolved_ == 0); }
  bool IsLinked() const { return position_ > 0; }
  bool HasNear() const { return unresolved_ != 0; }

 private:
  void BindTo(intptr_t position) {
    ASSERT(!IsBound());
    ASSERT(!HasNear());
    position_ = -position - kWordSize;
    ASSERT(IsBound());
  }

  void LinkTo(intptr_t position) {
    ASSERT(!IsBound());
    position_ = position + kWordSize;
    ASSERT(IsLinked());
  }

  void NearLinkTo(intptr_t position) {
    ASSERT(!IsBound());
    ASSERT(unresolved_ < kMaxUnresolvedBranches);
    unresolved_near_positions_[unresolved_++] = position;
  }

  static const int kMaxUnresolvedBranches = 20;

  intptr_t position_;
  intptr_t unresolved_;
  intptr_t unresolved_near_positions_[kMaxUnresolvedBranches];

  friend class Assembler;
  DISALLOW_COPY_AND_ASSIGN(Label);
};


class Assembler : public ValueObject {
 public:
  explicit Assembler(bool use_far_branches = false)
      : buffer_(),
        prologue_offset_(-1),
        jit_cookie_(0),
        comments_(),
        code_(Code::ZoneHandle()) {
    // This mode is only needed and implemented for MIPS and ARM.
    ASSERT(!use_far_branches);
  }
  ~Assembler() { }

  static const bool kNearJump = true;
  static const bool kFarJump = false;

  /*
   * Emit Machine Instructions.
   */
  void call(Register reg);
  void call(const Address& address);
  void call(Label* label);
  void call(const ExternalLabel* label);

  static const intptr_t kCallExternalLabelSize = 5;

  void pushl(Register reg);
  void pushl(const Address& address);
  void pushl(const Immediate& imm);

  void popl(Register reg);
  void popl(const Address& address);

  void pushal();
  void popal();

  void setcc(Condition condition, ByteRegister dst);

  void movl(Register dst, const Immediate& src);
  void movl(Register dst, Register src);

  void movl(Register dst, const Address& src);
  void movl(const Address& dst, Register src);
  void movl(const Address& dst, const Immediate& imm);

  void movzxb(Register dst, ByteRegister src);
  void movzxb(Register dst, const Address& src);
  void movsxb(Register dst, ByteRegister src);
  void movsxb(Register dst, const Address& src);
  void movb(Register dst, const Address& src);
  void movb(const Address& dst, ByteRegister src);
  void movb(const Address& dst, const Immediate& imm);

  void movzxw(Register dst, Register src);
  void movzxw(Register dst, const Address& src);
  void movsxw(Register dst, Register src);
  void movsxw(Register dst, const Address& src);
  void movw(Register dst, const Address& src);
  void movw(const Address& dst, Register src);
  void movw(const Address& dst, const Immediate& imm);

  void leal(Register dst, const Address& src);

  void cmovno(Register dst, Register src);
  void cmove(Register dst, Register src);
  void cmovne(Register dst, Register src);
  void cmovs(Register dst, Register src);
  void cmovns(Register dst, Register src);

  void cmovgel(Register dst, Register src);
  void cmovlessl(Register dst, Register src);

  void rep_movsb();

  void movss(XmmRegister dst, const Address& src);
  void movss(const Address& dst, XmmRegister src);
  void movss(XmmRegister dst, XmmRegister src);

  void movd(XmmRegister dst, Register src);
  void movd(Register dst, XmmRegister src);

  void movq(const Address& dst, XmmRegister src);
  void movq(XmmRegister dst, const Address& src);

  void addss(XmmRegister dst, XmmRegister src);
  void addss(XmmRegister dst, const Address& src);
  void subss(XmmRegister dst, XmmRegister src);
  void subss(XmmRegister dst, const Address& src);
  void mulss(XmmRegister dst, XmmRegister src);
  void mulss(XmmRegister dst, const Address& src);
  void divss(XmmRegister dst, XmmRegister src);
  void divss(XmmRegister dst, const Address& src);

  void movsd(XmmRegister dst, const Address& src);
  void movsd(const Address& dst, XmmRegister src);
  void movsd(XmmRegister dst, XmmRegister src);

  void movaps(XmmRegister dst, XmmRegister src);

  void movups(XmmRegister dst, const Address& src);
  void movups(const Address& dst, XmmRegister src);

  void addsd(XmmRegister dst, XmmRegister src);
  void addsd(XmmRegister dst, const Address& src);
  void subsd(XmmRegister dst, XmmRegister src);
  void subsd(XmmRegister dst, const Address& src);
  void mulsd(XmmRegister dst, XmmRegister src);
  void mulsd(XmmRegister dst, const Address& src);
  void divsd(XmmRegister dst, XmmRegister src);
  void divsd(XmmRegister dst, const Address& src);

  void addpl(XmmRegister dst, XmmRegister src);
  void subpl(XmmRegister dst, XmmRegister src);
  void addps(XmmRegister dst, XmmRegister src);
  void subps(XmmRegister dst, XmmRegister src);
  void divps(XmmRegister dst, XmmRegister src);
  void mulps(XmmRegister dst, XmmRegister src);
  void minps(XmmRegister dst, XmmRegister src);
  void maxps(XmmRegister dst, XmmRegister src);
  void andps(XmmRegister dst, XmmRegister src);
  void andps(XmmRegister dst, const Address& src);
  void orps(XmmRegister dst, XmmRegister src);
  void notps(XmmRegister dst);
  void negateps(XmmRegister dst);
  void absps(XmmRegister dst);
  void zerowps(XmmRegister dst);
  void cmppseq(XmmRegister dst, XmmRegister src);
  void cmppsneq(XmmRegister dst, XmmRegister src);
  void cmppslt(XmmRegister dst, XmmRegister src);
  void cmppsle(XmmRegister dst, XmmRegister src);
  void cmppsnlt(XmmRegister dst, XmmRegister src);
  void cmppsnle(XmmRegister dst, XmmRegister src);
  void sqrtps(XmmRegister dst);
  void rsqrtps(XmmRegister dst);
  void reciprocalps(XmmRegister dst);
  void movhlps(XmmRegister dst, XmmRegister src);
  void movlhps(XmmRegister dst, XmmRegister src);
  void unpcklps(XmmRegister dst, XmmRegister src);
  void unpckhps(XmmRegister dst, XmmRegister src);
  void unpcklpd(XmmRegister dst, XmmRegister src);
  void unpckhpd(XmmRegister dst, XmmRegister src);

  void set1ps(XmmRegister dst, Register tmp, const Immediate& imm);
  void shufps(XmmRegister dst, XmmRegister src, const Immediate& mask);

  void addpd(XmmRegister dst, XmmRegister src);
  void negatepd(XmmRegister dst);
  void subpd(XmmRegister dst, XmmRegister src);
  void mulpd(XmmRegister dst, XmmRegister src);
  void divpd(XmmRegister dst, XmmRegister src);
  void abspd(XmmRegister dst);
  void minpd(XmmRegister dst, XmmRegister src);
  void maxpd(XmmRegister dst, XmmRegister src);
  void sqrtpd(XmmRegister dst);
  void cvtps2pd(XmmRegister dst, XmmRegister src);
  void cvtpd2ps(XmmRegister dst, XmmRegister src);
  void shufpd(XmmRegister dst, XmmRegister src, const Immediate& mask);

  void cvtsi2ss(XmmRegister dst, Register src);
  void cvtsi2sd(XmmRegister dst, Register src);

  void cvtss2si(Register dst, XmmRegister src);
  void cvtss2sd(XmmRegister dst, XmmRegister src);

  void cvtsd2si(Register dst, XmmRegister src);
  void cvtsd2ss(XmmRegister dst, XmmRegister src);

  void cvttss2si(Register dst, XmmRegister src);
  void cvttsd2si(Register dst, XmmRegister src);

  void cvtdq2pd(XmmRegister dst, XmmRegister src);

  void comiss(XmmRegister a, XmmRegister b);
  void comisd(XmmRegister a, XmmRegister b);

  void movmskpd(Register dst, XmmRegister src);
  void movmskps(Register dst, XmmRegister src);

  void sqrtsd(XmmRegister dst, XmmRegister src);
  void sqrtss(XmmRegister dst, XmmRegister src);

  void xorpd(XmmRegister dst, const Address& src);
  void xorpd(XmmRegister dst, XmmRegister src);
  void xorps(XmmRegister dst, const Address& src);
  void xorps(XmmRegister dst, XmmRegister src);

  void andpd(XmmRegister dst, const Address& src);
  void andpd(XmmRegister dst, XmmRegister src);

  void orpd(XmmRegister dst, XmmRegister src);

  void pextrd(Register dst, XmmRegister src, const Immediate& imm);
  void pmovsxdq(XmmRegister dst, XmmRegister src);
  void pcmpeqq(XmmRegister dst, XmmRegister src);

  void pxor(XmmRegister dst, XmmRegister src);

  enum RoundingMode {
    kRoundToNearest = 0x0,
    kRoundDown      = 0x1,
    kRoundUp        = 0x2,
    kRoundToZero    = 0x3
  };
  void roundsd(XmmRegister dst, XmmRegister src, RoundingMode mode);

  void flds(const Address& src);
  void fstps(const Address& dst);

  void fldl(const Address& src);
  void fstpl(const Address& dst);

  void fnstcw(const Address& dst);
  void fldcw(const Address& src);

  void fistpl(const Address& dst);
  void fistps(const Address& dst);
  void fildl(const Address& src);
  void filds(const Address& src);

  void fincstp();
  void ffree(intptr_t value);

  void fsin();
  void fcos();
  void fsincos();
  void fptan();

  void xchgl(Register dst, Register src);

  void cmpl(Register reg, const Immediate& imm);
  void cmpl(Register reg0, Register reg1);
  void cmpl(Register reg, const Address& address);

  void cmpl(const Address& address, Register reg);
  void cmpl(const Address& address, const Immediate& imm);
  void cmpw(Register reg, const Address& address);
  void cmpw(const Address& address, const Immediate& imm);
  void cmpb(const Address& address, const Immediate& imm);

  void testl(Register reg1, Register reg2);
  void testl(Register reg, const Immediate& imm);
  void testb(const Address& address, const Immediate& imm);

  void andl(Register dst, const Immediate& imm);
  void andl(Register dst, Register src);
  void andl(Register dst, const Address& address);

  void orl(Register dst, const Immediate& imm);
  void orl(Register dst, Register src);
  void orl(Register dst, const Address& address);
  void orl(const Address& address, Register dst);

  void xorl(Register dst, const Immediate& imm);
  void xorl(Register dst, Register src);
  void xorl(Register dst, const Address& address);

  void addl(Register dst, Register src);
  void addl(Register reg, const Immediate& imm);
  void addl(Register reg, const Address& address);

  void addl(const Address& address, Register reg);
  void addl(const Address& address, const Immediate& imm);

  void adcl(Register dst, Register src);
  void adcl(Register reg, const Immediate& imm);
  void adcl(Register dst, const Address& address);
  void adcl(const Address& dst, Register src);

  void subl(Register dst, Register src);
  void subl(Register reg, const Immediate& imm);
  void subl(Register reg, const Address& address);
  void subl(const Address& address, Register reg);

  void cdq();

  void idivl(Register reg);

  void divl(Register reg);

  void imull(Register dst, Register src);
  void imull(Register reg, const Immediate& imm);
  void imull(Register reg, const Address& address);

  void imull(Register reg);
  void imull(const Address& address);

  void mull(Register reg);
  void mull(const Address& address);

  void sbbl(Register dst, Register src);
  void sbbl(Register reg, const Immediate& imm);
  void sbbl(Register reg, const Address& address);
  void sbbl(const Address& address, Register reg);

  void incl(Register reg);
  void incl(const Address& address);

  void decl(Register reg);
  void decl(const Address& address);

  void shll(Register reg, const Immediate& imm);
  void shll(Register operand, Register shifter);
  void shll(const Address& operand, Register shifter);
  void shrl(Register reg, const Immediate& imm);
  void shrl(Register operand, Register shifter);
  void sarl(Register reg, const Immediate& imm);
  void sarl(Register operand, Register shifter);
  void sarl(const Address& address, Register shifter);
  void shldl(Register dst, Register src, Register shifter);
  void shldl(Register dst, Register src, const Immediate& imm);
  void shldl(const Address& operand, Register src, Register shifter);
  void shrdl(Register dst, Register src, Register shifter);
  void shrdl(Register dst, Register src, const Immediate& imm);
  void shrdl(const Address& dst, Register src, Register shifter);

  void negl(Register reg);
  void notl(Register reg);

  void bsrl(Register dst, Register src);

  void bt(Register base, Register offset);

  void enter(const Immediate& imm);
  void leave();

  void ret();
  void ret(const Immediate& imm);

  // 'size' indicates size in bytes and must be in the range 1..8.
  void nop(int size = 1);
  void int3();
  void hlt();

  static uword GetBreakInstructionFiller() {
    return 0xCCCCCCCC;
  }

  // Note: verified_mem mode forces far jumps.
  void j(Condition condition, Label* label, bool near = kFarJump);
  void j(Condition condition, const ExternalLabel* label);

  void jmp(Register reg);
  // Note: verified_mem mode forces far jumps.
  void jmp(Label* label, bool near = kFarJump);
  void jmp(const ExternalLabel* label);

  void lock();
  void cmpxchgl(const Address& address, Register reg);

  void cpuid();

  /*
   * Macros for High-level operations and implemented on all architectures.
   */

  void CompareRegisters(Register a, Register b);

  // Issues a move instruction if 'to' is not the same as 'from'.
  void MoveRegister(Register to, Register from);
  void PopRegister(Register r);

  void AddImmediate(Register reg, const Immediate& imm);
  void SubImmediate(Register reg, const Immediate& imm);

  void Drop(intptr_t stack_elements);

  void LoadIsolate(Register dst);

  void LoadObject(Register dst, const Object& object);

  // If 'object' is a large Smi, xor it with a per-assembler cookie value to
  // prevent user-controlled immediates from appearing in the code stream.
  void LoadObjectSafely(Register dst, const Object& object);

  void PushObject(const Object& object);
  void CompareObject(Register reg, const Object& object);
  void LoadDoubleConstant(XmmRegister dst, double value);

  // When storing into a heap object field, knowledge of the previous content
  // is expressed through these constants.
  enum FieldContent {
    kEmptyOrSmiOrNull,  // Empty = garbage/zapped in release/debug mode.
    kHeapObjectOrSmi,
    kOnlySmi,
  };

  void StoreIntoObject(Register object,  // Object we are storing into.
                       const Address& dest,  // Where we are storing into.
                       Register value,  // Value we are storing.
                       bool can_value_be_smi = true);

  void StoreIntoObjectNoBarrier(Register object,
                                const Address& dest,
                                Register value,
                                FieldContent old_content = kHeapObjectOrSmi);
  void InitializeFieldNoBarrier(Register object,
                                const Address& dest,
                                Register value) {
    return StoreIntoObjectNoBarrier(object, dest, value, kEmptyOrSmiOrNull);
  }
  void StoreIntoObjectNoBarrier(Register object,
                                const Address& dest,
                                const Object& value,
                                FieldContent old_content = kHeapObjectOrSmi);
  void InitializeFieldNoBarrier(Register object,
                                const Address& dest,
                                const Object& value) {
    return StoreIntoObjectNoBarrier(object, dest, value, kEmptyOrSmiOrNull);
  }

  // Stores a Smi value into a heap object field that always contains a Smi.
  void StoreIntoSmiField(const Address& dest, Register value);
  void ZeroInitSmiField(const Address& dest);
  // Increments a Smi field. Leaves flags in same state as an 'addl'.
  void IncrementSmiField(const Address& dest, int32_t increment);

  void DoubleNegate(XmmRegister d);
  void FloatNegate(XmmRegister f);

  void DoubleAbs(XmmRegister reg);

  void LockCmpxchgl(const Address& address, Register reg) {
    lock();
    cmpxchgl(address, reg);
  }

  void EnterFrame(intptr_t frame_space);
  void LeaveFrame();
  void ReserveAlignedFrameSpace(intptr_t frame_space);

  // Create a frame for calling into runtime that preserves all volatile
  // registers.  Frame's RSP is guaranteed to be correctly aligned and
  // frame_space bytes are reserved under it.
  void EnterCallRuntimeFrame(intptr_t frame_space);
  void LeaveCallRuntimeFrame();

  void CallRuntime(const RuntimeEntry& entry, intptr_t argument_count);

  void Call(const StubEntry& stub_entry);

  void Jmp(const StubEntry& stub_entry);
  void J(Condition condition, const StubEntry& stub_entry);

  /*
   * Loading and comparing classes of objects.
   */
  void LoadClassId(Register result, Register object);

  void LoadClassById(Register result, Register class_id);

  void LoadClass(Register result, Register object, Register scratch);

  void CompareClassId(Register object, intptr_t class_id, Register scratch);

  void LoadClassIdMayBeSmi(Register result, Register object);
  void LoadTaggedClassIdMayBeSmi(Register result, Register object);

  void SmiUntagOrCheckClass(Register object,
                            intptr_t class_id,
                            Register scratch,
                            Label* is_smi);

  void ComputeRange(Register result,
                    Register value,
                    Register lo_temp,
                    Register hi_temp,
                    Label* miss);

  void UpdateRangeFeedback(Register value,
                           intptr_t index,
                           Register ic_data,
                           Register scratch1,
                           Register scratch2,
                           Register scratch3,
                           Label* miss);

  static Address ElementAddressForIntIndex(bool is_external,
                                           intptr_t cid,
                                           intptr_t index_scale,
                                           Register array,
                                           intptr_t index);

  static Address ElementAddressForRegIndex(bool is_external,
                                           intptr_t cid,
                                           intptr_t index_scale,
                                           Register array,
                                           Register index);

  static Address VMTagAddress() {
    return Address(THR, Thread::vm_tag_offset());
  }

  /*
   * Misc. functionality
   */
  void SmiTag(Register reg) {
    addl(reg, reg);
  }

  void SmiUntag(Register reg) {
    sarl(reg, Immediate(kSmiTagSize));
  }

  intptr_t PreferredLoopAlignment() { return 16; }
  void Align(intptr_t alignment, intptr_t offset);
  void Bind(Label* label);
  void Jump(Label* label) { jmp(label); }

  // Address of code at offset.
  uword CodeAddress(intptr_t offset) {
    return buffer_.Address(offset);
  }

  intptr_t CodeSize() const { return buffer_.Size(); }
  intptr_t prologue_offset() const { return prologue_offset_; }

  // Count the fixups that produce a pointer offset, without processing
  // the fixups.
  intptr_t CountPointerOffsets() const {
    return buffer_.CountPointerOffsets();
  }
  const ZoneGrowableArray<intptr_t>& GetPointerOffsets() const {
    return buffer_.pointer_offsets();
  }

  ObjectPoolWrapper& object_pool_wrapper() { return object_pool_wrapper_; }

  RawObjectPool* MakeObjectPool() {
    return object_pool_wrapper_.MakeObjectPool();
  }

  void FinalizeInstructions(const MemoryRegion& region) {
    buffer_.FinalizeInstructions(region);
  }

  // Set up a Dart frame on entry with a frame pointer and PC information to
  // enable easy access to the RawInstruction object of code corresponding
  // to this frame.
  // The dart frame layout is as follows:
  //   ....
  //   ret PC
  //   saved EBP     <=== EBP
  //   pc (used to derive the RawInstruction Object of the dart code)
  //   locals space  <=== ESP
  //   .....
  // This code sets this up with the sequence:
  //   pushl ebp
  //   movl ebp, esp
  //   call L
  //   L: <code to adjust saved pc if there is any intrinsification code>
  //   .....
  void EnterDartFrame(intptr_t frame_size);

  // Set up a Dart frame for a function compiled for on-stack replacement.
  // The frame layout is a normal Dart frame, but the frame is partially set
  // up on entry (it is the frame of the unoptimized code).
  void EnterOsrFrame(intptr_t extra_size);

  // Set up a stub frame so that the stack traversal code can easily identify
  // a stub frame.
  // The stub frame layout is as follows:
  //   ....
  //   ret PC
  //   saved EBP
  //   0 (used to indicate frame is a stub frame)
  //   .....
  // This code sets this up with the sequence:
  //   pushl ebp
  //   movl ebp, esp
  //   pushl immediate(0)
  //   .....
  void EnterStubFrame();
  static const intptr_t kEnterStubFramePushedWords = 2;

  // Instruction pattern from entrypoint is used in dart frame prologs
  // to set up the frame and save a PC which can be used to figure out the
  // RawInstruction object corresponding to the code running in the frame.
  // entrypoint:
  //   pushl ebp          (size is 1 byte)
  //   movl ebp, esp      (size is 2 bytes)
  //   call L             (size is 5 bytes)
  //   L:
  static const intptr_t kEntryPointToPcMarkerOffset = 8;
  static intptr_t EntryPointToPcMarkerOffset() {
    return kEntryPointToPcMarkerOffset;
  }

  // If allocation tracing for |cid| is enabled, will jump to |trace| label,
  // which will allocate in the runtime where tracing occurs.
  void MaybeTraceAllocation(intptr_t cid,
                            Register temp_reg,
                            Label* trace,
                            bool near_jump,
                            bool inline_isolate = true);

  void UpdateAllocationStats(intptr_t cid,
                             Register temp_reg,
                             Heap::Space space,
                             bool inline_isolate = true);

  void UpdateAllocationStatsWithSize(intptr_t cid,
                                     Register size_reg,
                                     Register temp_reg,
                                     Heap::Space space,
                                     bool inline_isolate = true);
  void UpdateAllocationStatsWithSize(intptr_t cid,
                                     intptr_t instance_size,
                                     Register temp_reg,
                                     Heap::Space space,
                                     bool inline_isolate = true);

  // Inlined allocation of an instance of class 'cls', code has no runtime
  // calls. Jump to 'failure' if the instance cannot be allocated here.
  // Allocated instance is returned in 'instance_reg'.
  // Only the tags field of the object is initialized.
  void TryAllocate(const Class& cls,
                   Label* failure,
                   bool near_jump,
                   Register instance_reg,
                   Register temp_reg);

  void TryAllocateArray(intptr_t cid,
                        intptr_t instance_size,
                        Label* failure,
                        bool near_jump,
                        Register instance,
                        Register end_address,
                        Register temp);

  // Debugging and bringup support.
  void Stop(const char* message);
  void Unimplemented(const char* message);
  void Untested(const char* message);
  void Unreachable(const char* message);

  static void InitializeMemoryWithBreakpoints(uword data, intptr_t length);

  void Comment(const char* format, ...) PRINTF_ATTRIBUTE(2, 3);
  static bool EmittingComments();

  const Code::Comments& GetCodeComments() const;

  static const char* RegisterName(Register reg);
  static const char* FpuRegisterName(FpuRegister reg);

  // Smis that do not fit into 17 bits (16 bits of payload) are unsafe.
  static bool IsSafeSmi(const Object& object) {
    if (!object.IsSmi()) {
      return false;
    }

    if (Utils::IsInt(17, reinterpret_cast<intptr_t>(object.raw()))) {
      return true;
    }

    // Single bit smis (powers of two) and corresponding masks are safe.
    const intptr_t value = Smi::Cast(object).Value();
    if (Utils::IsPowerOfTwo(value) || Utils::IsPowerOfTwo(value + 1)) {
      return true;
    }

    return false;
  }
  static bool IsSafe(const Object& object) {
    return !object.IsSmi() || IsSafeSmi(object);
  }

  void set_code_object(const Code& code) {
    code_ ^= code.raw();
  }

  void PushCodeObject();

 private:
  class CodeComment : public ZoneAllocated {
   public:
    CodeComment(intptr_t pc_offset, const String& comment)
        : pc_offset_(pc_offset), comment_(comment) { }

    intptr_t pc_offset() const { return pc_offset_; }
    const String& comment() const { return comment_; }

   private:
    intptr_t pc_offset_;
    const String& comment_;

    DISALLOW_COPY_AND_ASSIGN(CodeComment);
  };


  inline void EmitUint8(uint8_t value);
  inline void EmitInt32(int32_t value);
  inline void EmitRegisterOperand(int rm, int reg);
  inline void EmitXmmRegisterOperand(int rm, XmmRegister reg);
  inline void EmitFixup(AssemblerFixup* fixup);
  inline void EmitOperandSizeOverride();

  void EmitOperand(int rm, const Operand& operand);
  void EmitImmediate(const Immediate& imm);
  void EmitComplex(int rm, const Operand& operand, const Immediate& immediate);
  void EmitLabel(Label* label, intptr_t instruction_size);
  void EmitLabelLink(Label* label);
  void EmitNearLabelLink(Label* label);

  void EmitGenericShift(int rm, Register reg, const Immediate& imm);
  void EmitGenericShift(int rm, const Operand& operand, Register shifter);

  void StoreIntoObjectFilter(Register object, Register value, Label* no_update);

  // Shorter filtering sequence that assumes that value is not a smi.
  void StoreIntoObjectFilterNoSmi(Register object,
                                  Register value,
                                  Label* no_update);
#if defined(DEBUG)
  void VerifyUninitialized(const Address& address);
  void VerifyObjectOrSmi(const Address& address);
  void VerifySmi(const Address& address, const char* stop_msg = "Expected Smi");
#endif  // DEBUG
  // Like VerifiedMemory::Verify(address, kWordSize) and ::Write, but also,
  // in DEBUG mode, verifies that 'address' has content of type 'old_content'.
  void VerifyHeapWord(const Address& address, FieldContent old_content);
  void VerifiedWrite(const Address& dest,
                     Register value,
                     FieldContent old_content);
  void UnverifiedStoreOldObject(const Address& dest, const Object& value);

  int32_t jit_cookie();

  AssemblerBuffer buffer_;
  ObjectPoolWrapper object_pool_wrapper_;
  intptr_t prologue_offset_;
  int32_t jit_cookie_;
  GrowableArray<CodeComment*> comments_;
  Code& code_;

  DISALLOW_ALLOCATION();
  DISALLOW_COPY_AND_ASSIGN(Assembler);
};


inline void Assembler::EmitUint8(uint8_t value) {
  buffer_.Emit<uint8_t>(value);
}


inline void Assembler::EmitInt32(int32_t value) {
  buffer_.Emit<int32_t>(value);
}


inline void Assembler::EmitRegisterOperand(int rm, int reg) {
  ASSERT(rm >= 0 && rm < 8);
  buffer_.Emit<uint8_t>(0xC0 + (rm << 3) + reg);
}


inline void Assembler::EmitXmmRegisterOperand(int rm, XmmRegister reg) {
  EmitRegisterOperand(rm, static_cast<Register>(reg));
}


inline void Assembler::EmitFixup(AssemblerFixup* fixup) {
  buffer_.EmitFixup(fixup);
}


inline void Assembler::EmitOperandSizeOverride() {
  EmitUint8(0x66);
}

}  // namespace dart

#endif  // VM_ASSEMBLER_IA32_H_