root/src/arm/assembler-arm.cc

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DEFINITIONS

This source file includes following definitions.
  1. CpuFeaturesImpliedByCompiler
  2. Probe
  3. IsCodedSpecially
  4. PatchCode
  5. PatchCodeWithCall
  6. emit_debug_code_
  7. GetCode
  8. Align
  9. CodeTargetAlign
  10. GetCondition
  11. IsBranch
  12. GetBranchOffset
  13. IsLdrRegisterImmediate
  14. GetLdrRegisterImmediateOffset
  15. SetLdrRegisterImmediateOffset
  16. IsStrRegisterImmediate
  17. SetStrRegisterImmediateOffset
  18. IsAddRegisterImmediate
  19. SetAddRegisterImmediateOffset
  20. GetRd
  21. GetRn
  22. GetRm
  23. IsPush
  24. IsPop
  25. IsStrRegFpOffset
  26. IsLdrRegFpOffset
  27. IsStrRegFpNegOffset
  28. IsLdrRegFpNegOffset
  29. IsLdrPcImmediateOffset
  30. IsTstImmediate
  31. IsCmpRegister
  32. IsCmpImmediate
  33. GetCmpImmediateRegister
  34. GetCmpImmediateRawImmediate
  35. target_at
  36. target_at_put
  37. print
  38. bind_to
  39. link_to
  40. bind
  41. next
  42. EncodeMovwImmediate
  43. fits_shifter
  44. must_use_constant_pool
  45. is_single_instruction
  46. addrmod1
  47. addrmod2
  48. addrmod3
  49. addrmod4
  50. addrmod5
  51. branch_offset
  52. label_at_put
  53. blx
  54. blx
  55. bx
  56. and_
  57. eor
  58. sub
  59. rsb
  60. add
  61. adc
  62. sbc
  63. rsc
  64. tst
  65. teq
  66. cmp
  67. cmp_raw_immediate
  68. cmn
  69. orr
  70. mov
  71. movw
  72. movt
  73. bic
  74. mvn
  75. mla
  76. mul
  77. smlal
  78. smull
  79. umlal
  80. umull
  81. clz
  82. usat
  83. ubfx
  84. sbfx
  85. bfc
  86. bfi
  87. mrs
  88. msr
  89. ldr
  90. str
  91. ldrb
  92. strb
  93. ldrh
  94. strh
  95. ldrsb
  96. ldrsh
  97. ldrd
  98. strd
  99. ldm
  100. stm
  101. stop
  102. bkpt
  103. svc
  104. cdp
  105. cdp2
  106. mcr
  107. mcr2
  108. mrc
  109. mrc2
  110. ldc
  111. ldc
  112. ldc2
  113. ldc2
  114. vldr
  115. vldr
  116. vldr
  117. vldr
  118. vstr
  119. vstr
  120. vstr
  121. vstr
  122. vldm
  123. vstm
  124. vldm
  125. vstm
  126. DoubleAsTwoUInt32
  127. FitsVMOVDoubleImmediate
  128. vmov
  129. vmov
  130. vmov
  131. vmov
  132. vmov
  133. vmov
  134. vmov
  135. IsSignedVFPType
  136. IsIntegerVFPType
  137. IsDoubleVFPType
  138. SplitRegCode
  139. EncodeVCVT
  140. vcvt_f64_s32
  141. vcvt_f32_s32
  142. vcvt_f64_u32
  143. vcvt_s32_f64
  144. vcvt_u32_f64
  145. vcvt_f64_f32
  146. vcvt_f32_f64
  147. vneg
  148. vabs
  149. vadd
  150. vsub
  151. vmul
  152. vdiv
  153. vcmp
  154. vcmp
  155. vmsr
  156. vmrs
  157. vsqrt
  158. nop
  159. IsNop
  160. ImmediateFitsAddrMode1Instruction
  161. RecordJSReturn
  162. RecordDebugBreakSlot
  163. RecordComment
  164. RecordConstPool
  165. GrowBuffer
  166. db
  167. dd
  168. RecordRelocInfo
  169. BlockConstPoolFor
  170. CheckConstPool

// Copyright (c) 1994-2006 Sun Microsystems Inc.
// 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.
//
// - Redistribution 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 Sun Microsystems or the names of 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.

// The original source code covered by the above license above has been
// modified significantly by Google Inc.
// Copyright 2011 the V8 project authors. All rights reserved.

#include "v8.h"

#if defined(V8_TARGET_ARCH_ARM)

#include "arm/assembler-arm-inl.h"
#include "serialize.h"

namespace v8 {
namespace internal {

#ifdef DEBUG
bool CpuFeatures::initialized_ = false;
#endif
unsigned CpuFeatures::supported_ = 0;
unsigned CpuFeatures::found_by_runtime_probing_ = 0;


// Get the CPU features enabled by the build. For cross compilation the
// preprocessor symbols CAN_USE_ARMV7_INSTRUCTIONS and CAN_USE_VFP_INSTRUCTIONS
// can be defined to enable ARMv7 and VFPv3 instructions when building the
// snapshot.
static uint64_t CpuFeaturesImpliedByCompiler() {
  uint64_t answer = 0;
#ifdef CAN_USE_ARMV7_INSTRUCTIONS
  answer |= 1u << ARMv7;
#endif  // def CAN_USE_ARMV7_INSTRUCTIONS
#ifdef CAN_USE_VFP_INSTRUCTIONS
  answer |= 1u << VFP3 | 1u << ARMv7;
#endif  // def CAN_USE_VFP_INSTRUCTIONS

#ifdef __arm__
  // If the compiler is allowed to use VFP then we can use VFP too in our code
  // generation even when generating snapshots. ARMv7 and hardware floating
  // point support implies VFPv3, see ARM DDI 0406B, page A1-6.
#if defined(CAN_USE_ARMV7_INSTRUCTIONS) && defined(__VFP_FP__) \
    && !defined(__SOFTFP__)
  answer |= 1u << VFP3 | 1u << ARMv7;
#endif  // defined(CAN_USE_ARMV7_INSTRUCTIONS) && defined(__VFP_FP__)
        // && !defined(__SOFTFP__)
#endif  // def __arm__

  return answer;
}


void CpuFeatures::Probe() {
  unsigned standard_features = static_cast<unsigned>(
      OS::CpuFeaturesImpliedByPlatform() | CpuFeaturesImpliedByCompiler());
  ASSERT(supported_ == 0 || supported_ == standard_features);
#ifdef DEBUG
  initialized_ = true;
#endif

  // Get the features implied by the OS and the compiler settings. This is the
  // minimal set of features which is also alowed for generated code in the
  // snapshot.
  supported_ |= standard_features;

  if (Serializer::enabled()) {
    // No probing for features if we might serialize (generate snapshot).
    return;
  }

#ifndef __arm__
  // For the simulator=arm build, use VFP when FLAG_enable_vfp3 is
  // enabled. VFPv3 implies ARMv7, see ARM DDI 0406B, page A1-6.
  if (FLAG_enable_vfp3) {
    supported_ |= 1u << VFP3 | 1u << ARMv7;
  }
  // For the simulator=arm build, use ARMv7 when FLAG_enable_armv7 is enabled
  if (FLAG_enable_armv7) {
    supported_ |= 1u << ARMv7;
  }
#else  // def __arm__
  // Probe for additional features not already known to be available.
  if (!IsSupported(VFP3) && OS::ArmCpuHasFeature(VFP3)) {
    // This implementation also sets the VFP flags if runtime
    // detection of VFP returns true. VFPv3 implies ARMv7, see ARM DDI
    // 0406B, page A1-6.
    supported_ |= 1u << VFP3 | 1u << ARMv7;
    found_by_runtime_probing_ |= 1u << VFP3 | 1u << ARMv7;
  }

  if (!IsSupported(ARMv7) && OS::ArmCpuHasFeature(ARMv7)) {
    supported_ |= 1u << ARMv7;
    found_by_runtime_probing_ |= 1u << ARMv7;
  }
#endif
}


// -----------------------------------------------------------------------------
// Implementation of RelocInfo

const int RelocInfo::kApplyMask = 0;


bool RelocInfo::IsCodedSpecially() {
  // The deserializer needs to know whether a pointer is specially coded.  Being
  // specially coded on ARM means that it is a movw/movt instruction.  We don't
  // generate those yet.
  return false;
}


void RelocInfo::PatchCode(byte* instructions, int instruction_count) {
  // Patch the code at the current address with the supplied instructions.
  Instr* pc = reinterpret_cast<Instr*>(pc_);
  Instr* instr = reinterpret_cast<Instr*>(instructions);
  for (int i = 0; i < instruction_count; i++) {
    *(pc + i) = *(instr + i);
  }

  // Indicate that code has changed.
  CPU::FlushICache(pc_, instruction_count * Assembler::kInstrSize);
}


// Patch the code at the current PC with a call to the target address.
// Additional guard instructions can be added if required.
void RelocInfo::PatchCodeWithCall(Address target, int guard_bytes) {
  // Patch the code at the current address with a call to the target.
  UNIMPLEMENTED();
}


// -----------------------------------------------------------------------------
// Implementation of Operand and MemOperand
// See assembler-arm-inl.h for inlined constructors

Operand::Operand(Handle<Object> handle) {
  rm_ = no_reg;
  // Verify all Objects referred by code are NOT in new space.
  Object* obj = *handle;
  ASSERT(!HEAP->InNewSpace(obj));
  if (obj->IsHeapObject()) {
    imm32_ = reinterpret_cast<intptr_t>(handle.location());
    rmode_ = RelocInfo::EMBEDDED_OBJECT;
  } else {
    // no relocation needed
    imm32_ =  reinterpret_cast<intptr_t>(obj);
    rmode_ = RelocInfo::NONE;
  }
}


Operand::Operand(Register rm, ShiftOp shift_op, int shift_imm) {
  ASSERT(is_uint5(shift_imm));
  ASSERT(shift_op != ROR || shift_imm != 0);  // use RRX if you mean it
  rm_ = rm;
  rs_ = no_reg;
  shift_op_ = shift_op;
  shift_imm_ = shift_imm & 31;
  if (shift_op == RRX) {
    // encoded as ROR with shift_imm == 0
    ASSERT(shift_imm == 0);
    shift_op_ = ROR;
    shift_imm_ = 0;
  }
}


Operand::Operand(Register rm, ShiftOp shift_op, Register rs) {
  ASSERT(shift_op != RRX);
  rm_ = rm;
  rs_ = no_reg;
  shift_op_ = shift_op;
  rs_ = rs;
}


MemOperand::MemOperand(Register rn, int32_t offset, AddrMode am) {
  rn_ = rn;
  rm_ = no_reg;
  offset_ = offset;
  am_ = am;
}

MemOperand::MemOperand(Register rn, Register rm, AddrMode am) {
  rn_ = rn;
  rm_ = rm;
  shift_op_ = LSL;
  shift_imm_ = 0;
  am_ = am;
}


MemOperand::MemOperand(Register rn, Register rm,
                       ShiftOp shift_op, int shift_imm, AddrMode am) {
  ASSERT(is_uint5(shift_imm));
  rn_ = rn;
  rm_ = rm;
  shift_op_ = shift_op;
  shift_imm_ = shift_imm & 31;
  am_ = am;
}


// -----------------------------------------------------------------------------
// Specific instructions, constants, and masks.

// add(sp, sp, 4) instruction (aka Pop())
const Instr kPopInstruction =
    al | PostIndex | 4 | LeaveCC | I | kRegister_sp_Code * B16 |
        kRegister_sp_Code * B12;
// str(r, MemOperand(sp, 4, NegPreIndex), al) instruction (aka push(r))
// register r is not encoded.
const Instr kPushRegPattern =
    al | B26 | 4 | NegPreIndex | kRegister_sp_Code * B16;
// ldr(r, MemOperand(sp, 4, PostIndex), al) instruction (aka pop(r))
// register r is not encoded.
const Instr kPopRegPattern =
    al | B26 | L | 4 | PostIndex | kRegister_sp_Code * B16;
// mov lr, pc
const Instr kMovLrPc = al | MOV | kRegister_pc_Code | kRegister_lr_Code * B12;
// ldr rd, [pc, #offset]
const Instr kLdrPCMask = kCondMask | 15 * B24 | 7 * B20 | 15 * B16;
const Instr kLdrPCPattern = al | 5 * B24 | L | kRegister_pc_Code * B16;
// blxcc rm
const Instr kBlxRegMask =
    15 * B24 | 15 * B20 | 15 * B16 | 15 * B12 | 15 * B8 | 15 * B4;
const Instr kBlxRegPattern =
    B24 | B21 | 15 * B16 | 15 * B12 | 15 * B8 | BLX;
const Instr kBlxIp = al | kBlxRegPattern | ip.code();
const Instr kMovMvnMask = 0x6d * B21 | 0xf * B16;
const Instr kMovMvnPattern = 0xd * B21;
const Instr kMovMvnFlip = B22;
const Instr kMovLeaveCCMask = 0xdff * B16;
const Instr kMovLeaveCCPattern = 0x1a0 * B16;
const Instr kMovwMask = 0xff * B20;
const Instr kMovwPattern = 0x30 * B20;
const Instr kMovwLeaveCCFlip = 0x5 * B21;
const Instr kCmpCmnMask = 0xdd * B20 | 0xf * B12;
const Instr kCmpCmnPattern = 0x15 * B20;
const Instr kCmpCmnFlip = B21;
const Instr kAddSubFlip = 0x6 * B21;
const Instr kAndBicFlip = 0xe * B21;

// A mask for the Rd register for push, pop, ldr, str instructions.
const Instr kLdrRegFpOffsetPattern =
    al | B26 | L | Offset | kRegister_fp_Code * B16;
const Instr kStrRegFpOffsetPattern =
    al | B26 | Offset | kRegister_fp_Code * B16;
const Instr kLdrRegFpNegOffsetPattern =
    al | B26 | L | NegOffset | kRegister_fp_Code * B16;
const Instr kStrRegFpNegOffsetPattern =
    al | B26 | NegOffset | kRegister_fp_Code * B16;
const Instr kLdrStrInstrTypeMask = 0xffff0000;
const Instr kLdrStrInstrArgumentMask = 0x0000ffff;
const Instr kLdrStrOffsetMask = 0x00000fff;


// Spare buffer.
static const int kMinimalBufferSize = 4*KB;


Assembler::Assembler(Isolate* arg_isolate, void* buffer, int buffer_size)
    : AssemblerBase(arg_isolate),
      positions_recorder_(this),
      emit_debug_code_(FLAG_debug_code) {
  if (buffer == NULL) {
    // Do our own buffer management.
    if (buffer_size <= kMinimalBufferSize) {
      buffer_size = kMinimalBufferSize;

      if (isolate()->assembler_spare_buffer() != NULL) {
        buffer = isolate()->assembler_spare_buffer();
        isolate()->set_assembler_spare_buffer(NULL);
      }
    }
    if (buffer == NULL) {
      buffer_ = NewArray<byte>(buffer_size);
    } else {
      buffer_ = static_cast<byte*>(buffer);
    }
    buffer_size_ = buffer_size;
    own_buffer_ = true;

  } else {
    // Use externally provided buffer instead.
    ASSERT(buffer_size > 0);
    buffer_ = static_cast<byte*>(buffer);
    buffer_size_ = buffer_size;
    own_buffer_ = false;
  }

  // Set up buffer pointers.
  ASSERT(buffer_ != NULL);
  pc_ = buffer_;
  reloc_info_writer.Reposition(buffer_ + buffer_size, pc_);
  num_pending_reloc_info_ = 0;
  next_buffer_check_ = 0;
  const_pool_blocked_nesting_ = 0;
  no_const_pool_before_ = 0;
  first_const_pool_use_ = -1;
  last_bound_pos_ = 0;
  ClearRecordedAstId();
}


Assembler::~Assembler() {
  ASSERT(const_pool_blocked_nesting_ == 0);
  if (own_buffer_) {
    if (isolate()->assembler_spare_buffer() == NULL &&
        buffer_size_ == kMinimalBufferSize) {
      isolate()->set_assembler_spare_buffer(buffer_);
    } else {
      DeleteArray(buffer_);
    }
  }
}


void Assembler::GetCode(CodeDesc* desc) {
  // Emit constant pool if necessary.
  CheckConstPool(true, false);
  ASSERT(num_pending_reloc_info_ == 0);

  // Set up code descriptor.
  desc->buffer = buffer_;
  desc->buffer_size = buffer_size_;
  desc->instr_size = pc_offset();
  desc->reloc_size = (buffer_ + buffer_size_) - reloc_info_writer.pos();
}


void Assembler::Align(int m) {
  ASSERT(m >= 4 && IsPowerOf2(m));
  while ((pc_offset() & (m - 1)) != 0) {
    nop();
  }
}


void Assembler::CodeTargetAlign() {
  // Preferred alignment of jump targets on some ARM chips.
  Align(8);
}


Condition Assembler::GetCondition(Instr instr) {
  return Instruction::ConditionField(instr);
}


bool Assembler::IsBranch(Instr instr) {
  return (instr & (B27 | B25)) == (B27 | B25);
}


int Assembler::GetBranchOffset(Instr instr) {
  ASSERT(IsBranch(instr));
  // Take the jump offset in the lower 24 bits, sign extend it and multiply it
  // with 4 to get the offset in bytes.
  return ((instr & kImm24Mask) << 8) >> 6;
}


bool Assembler::IsLdrRegisterImmediate(Instr instr) {
  return (instr & (B27 | B26 | B25 | B22 | B20)) == (B26 | B20);
}


int Assembler::GetLdrRegisterImmediateOffset(Instr instr) {
  ASSERT(IsLdrRegisterImmediate(instr));
  bool positive = (instr & B23) == B23;
  int offset = instr & kOff12Mask;  // Zero extended offset.
  return positive ? offset : -offset;
}


Instr Assembler::SetLdrRegisterImmediateOffset(Instr instr, int offset) {
  ASSERT(IsLdrRegisterImmediate(instr));
  bool positive = offset >= 0;
  if (!positive) offset = -offset;
  ASSERT(is_uint12(offset));
  // Set bit indicating whether the offset should be added.
  instr = (instr & ~B23) | (positive ? B23 : 0);
  // Set the actual offset.
  return (instr & ~kOff12Mask) | offset;
}


bool Assembler::IsStrRegisterImmediate(Instr instr) {
  return (instr & (B27 | B26 | B25 | B22 | B20)) == B26;
}


Instr Assembler::SetStrRegisterImmediateOffset(Instr instr, int offset) {
  ASSERT(IsStrRegisterImmediate(instr));
  bool positive = offset >= 0;
  if (!positive) offset = -offset;
  ASSERT(is_uint12(offset));
  // Set bit indicating whether the offset should be added.
  instr = (instr & ~B23) | (positive ? B23 : 0);
  // Set the actual offset.
  return (instr & ~kOff12Mask) | offset;
}


bool Assembler::IsAddRegisterImmediate(Instr instr) {
  return (instr & (B27 | B26 | B25 | B24 | B23 | B22 | B21)) == (B25 | B23);
}


Instr Assembler::SetAddRegisterImmediateOffset(Instr instr, int offset) {
  ASSERT(IsAddRegisterImmediate(instr));
  ASSERT(offset >= 0);
  ASSERT(is_uint12(offset));
  // Set the offset.
  return (instr & ~kOff12Mask) | offset;
}


Register Assembler::GetRd(Instr instr) {
  Register reg;
  reg.code_ = Instruction::RdValue(instr);
  return reg;
}


Register Assembler::GetRn(Instr instr) {
  Register reg;
  reg.code_ = Instruction::RnValue(instr);
  return reg;
}


Register Assembler::GetRm(Instr instr) {
  Register reg;
  reg.code_ = Instruction::RmValue(instr);
  return reg;
}


bool Assembler::IsPush(Instr instr) {
  return ((instr & ~kRdMask) == kPushRegPattern);
}


bool Assembler::IsPop(Instr instr) {
  return ((instr & ~kRdMask) == kPopRegPattern);
}


bool Assembler::IsStrRegFpOffset(Instr instr) {
  return ((instr & kLdrStrInstrTypeMask) == kStrRegFpOffsetPattern);
}


bool Assembler::IsLdrRegFpOffset(Instr instr) {
  return ((instr & kLdrStrInstrTypeMask) == kLdrRegFpOffsetPattern);
}


bool Assembler::IsStrRegFpNegOffset(Instr instr) {
  return ((instr & kLdrStrInstrTypeMask) == kStrRegFpNegOffsetPattern);
}


bool Assembler::IsLdrRegFpNegOffset(Instr instr) {
  return ((instr & kLdrStrInstrTypeMask) == kLdrRegFpNegOffsetPattern);
}


bool Assembler::IsLdrPcImmediateOffset(Instr instr) {
  // Check the instruction is indeed a
  // ldr<cond> <Rd>, [pc +/- offset_12].
  return (instr & (kLdrPCMask & ~kCondMask)) == 0x051f0000;
}


bool Assembler::IsTstImmediate(Instr instr) {
  return (instr & (B27 | B26 | I | kOpCodeMask | S | kRdMask)) ==
      (I | TST | S);
}


bool Assembler::IsCmpRegister(Instr instr) {
  return (instr & (B27 | B26 | I | kOpCodeMask | S | kRdMask | B4)) ==
      (CMP | S);
}


bool Assembler::IsCmpImmediate(Instr instr) {
  return (instr & (B27 | B26 | I | kOpCodeMask | S | kRdMask)) ==
      (I | CMP | S);
}


Register Assembler::GetCmpImmediateRegister(Instr instr) {
  ASSERT(IsCmpImmediate(instr));
  return GetRn(instr);
}


int Assembler::GetCmpImmediateRawImmediate(Instr instr) {
  ASSERT(IsCmpImmediate(instr));
  return instr & kOff12Mask;
}

// Labels refer to positions in the (to be) generated code.
// There are bound, linked, and unused labels.
//
// Bound labels refer to known positions in the already
// generated code. pos() is the position the label refers to.
//
// Linked labels refer to unknown positions in the code
// to be generated; pos() is the position of the last
// instruction using the label.


// The link chain is terminated by a negative code position (must be aligned)
const int kEndOfChain = -4;


int Assembler::target_at(int pos)  {
  Instr instr = instr_at(pos);
  if ((instr & ~kImm24Mask) == 0) {
    // Emitted label constant, not part of a branch.
    return instr - (Code::kHeaderSize - kHeapObjectTag);
  }
  ASSERT((instr & 7*B25) == 5*B25);  // b, bl, or blx imm24
  int imm26 = ((instr & kImm24Mask) << 8) >> 6;
  if ((Instruction::ConditionField(instr) == kSpecialCondition) &&
      ((instr & B24) != 0)) {
    // blx uses bit 24 to encode bit 2 of imm26
    imm26 += 2;
  }
  return pos + kPcLoadDelta + imm26;
}


void Assembler::target_at_put(int pos, int target_pos) {
  Instr instr = instr_at(pos);
  if ((instr & ~kImm24Mask) == 0) {
    ASSERT(target_pos == kEndOfChain || target_pos >= 0);
    // Emitted label constant, not part of a branch.
    // Make label relative to Code* of generated Code object.
    instr_at_put(pos, target_pos + (Code::kHeaderSize - kHeapObjectTag));
    return;
  }
  int imm26 = target_pos - (pos + kPcLoadDelta);
  ASSERT((instr & 7*B25) == 5*B25);  // b, bl, or blx imm24
  if (Instruction::ConditionField(instr) == kSpecialCondition) {
    // blx uses bit 24 to encode bit 2 of imm26
    ASSERT((imm26 & 1) == 0);
    instr = (instr & ~(B24 | kImm24Mask)) | ((imm26 & 2) >> 1)*B24;
  } else {
    ASSERT((imm26 & 3) == 0);
    instr &= ~kImm24Mask;
  }
  int imm24 = imm26 >> 2;
  ASSERT(is_int24(imm24));
  instr_at_put(pos, instr | (imm24 & kImm24Mask));
}


void Assembler::print(Label* L) {
  if (L->is_unused()) {
    PrintF("unused label\n");
  } else if (L->is_bound()) {
    PrintF("bound label to %d\n", L->pos());
  } else if (L->is_linked()) {
    Label l = *L;
    PrintF("unbound label");
    while (l.is_linked()) {
      PrintF("@ %d ", l.pos());
      Instr instr = instr_at(l.pos());
      if ((instr & ~kImm24Mask) == 0) {
        PrintF("value\n");
      } else {
        ASSERT((instr & 7*B25) == 5*B25);  // b, bl, or blx
        Condition cond = Instruction::ConditionField(instr);
        const char* b;
        const char* c;
        if (cond == kSpecialCondition) {
          b = "blx";
          c = "";
        } else {
          if ((instr & B24) != 0)
            b = "bl";
          else
            b = "b";

          switch (cond) {
            case eq: c = "eq"; break;
            case ne: c = "ne"; break;
            case hs: c = "hs"; break;
            case lo: c = "lo"; break;
            case mi: c = "mi"; break;
            case pl: c = "pl"; break;
            case vs: c = "vs"; break;
            case vc: c = "vc"; break;
            case hi: c = "hi"; break;
            case ls: c = "ls"; break;
            case ge: c = "ge"; break;
            case lt: c = "lt"; break;
            case gt: c = "gt"; break;
            case le: c = "le"; break;
            case al: c = ""; break;
            default:
              c = "";
              UNREACHABLE();
          }
        }
        PrintF("%s%s\n", b, c);
      }
      next(&l);
    }
  } else {
    PrintF("label in inconsistent state (pos = %d)\n", L->pos_);
  }
}


void Assembler::bind_to(Label* L, int pos) {
  ASSERT(0 <= pos && pos <= pc_offset());  // must have a valid binding position
  while (L->is_linked()) {
    int fixup_pos = L->pos();
    next(L);  // call next before overwriting link with target at fixup_pos
    target_at_put(fixup_pos, pos);
  }
  L->bind_to(pos);

  // Keep track of the last bound label so we don't eliminate any instructions
  // before a bound label.
  if (pos > last_bound_pos_)
    last_bound_pos_ = pos;
}


void Assembler::link_to(Label* L, Label* appendix) {
  if (appendix->is_linked()) {
    if (L->is_linked()) {
      // Append appendix to L's list.
      int fixup_pos;
      int link = L->pos();
      do {
        fixup_pos = link;
        link = target_at(fixup_pos);
      } while (link > 0);
      ASSERT(link == kEndOfChain);
      target_at_put(fixup_pos, appendix->pos());
    } else {
      // L is empty, simply use appendix.
      *L = *appendix;
    }
  }
  appendix->Unuse();  // appendix should not be used anymore
}


void Assembler::bind(Label* L) {
  ASSERT(!L->is_bound());  // label can only be bound once
  bind_to(L, pc_offset());
}


void Assembler::next(Label* L) {
  ASSERT(L->is_linked());
  int link = target_at(L->pos());
  if (link == kEndOfChain) {
    L->Unuse();
  } else {
    ASSERT(link >= 0);
    L->link_to(link);
  }
}


static Instr EncodeMovwImmediate(uint32_t immediate) {
  ASSERT(immediate < 0x10000);
  return ((immediate & 0xf000) << 4) | (immediate & 0xfff);
}


// Low-level code emission routines depending on the addressing mode.
// If this returns true then you have to use the rotate_imm and immed_8
// that it returns, because it may have already changed the instruction
// to match them!
static bool fits_shifter(uint32_t imm32,
                         uint32_t* rotate_imm,
                         uint32_t* immed_8,
                         Instr* instr) {
  // imm32 must be unsigned.
  for (int rot = 0; rot < 16; rot++) {
    uint32_t imm8 = (imm32 << 2*rot) | (imm32 >> (32 - 2*rot));
    if ((imm8 <= 0xff)) {
      *rotate_imm = rot;
      *immed_8 = imm8;
      return true;
    }
  }
  // If the opcode is one with a complementary version and the complementary
  // immediate fits, change the opcode.
  if (instr != NULL) {
    if ((*instr & kMovMvnMask) == kMovMvnPattern) {
      if (fits_shifter(~imm32, rotate_imm, immed_8, NULL)) {
        *instr ^= kMovMvnFlip;
        return true;
      } else if ((*instr & kMovLeaveCCMask) == kMovLeaveCCPattern) {
        if (CpuFeatures::IsSupported(ARMv7)) {
          if (imm32 < 0x10000) {
            *instr ^= kMovwLeaveCCFlip;
            *instr |= EncodeMovwImmediate(imm32);
            *rotate_imm = *immed_8 = 0;  // Not used for movw.
            return true;
          }
        }
      }
    } else if ((*instr & kCmpCmnMask) == kCmpCmnPattern) {
      if (fits_shifter(-static_cast<int>(imm32), rotate_imm, immed_8, NULL)) {
        *instr ^= kCmpCmnFlip;
        return true;
      }
    } else {
      Instr alu_insn = (*instr & kALUMask);
      if (alu_insn == ADD ||
          alu_insn == SUB) {
        if (fits_shifter(-static_cast<int>(imm32), rotate_imm, immed_8, NULL)) {
          *instr ^= kAddSubFlip;
          return true;
        }
      } else if (alu_insn == AND ||
                 alu_insn == BIC) {
        if (fits_shifter(~imm32, rotate_imm, immed_8, NULL)) {
          *instr ^= kAndBicFlip;
          return true;
        }
      }
    }
  }
  return false;
}


// We have to use the temporary register for things that can be relocated even
// if they can be encoded in the ARM's 12 bits of immediate-offset instruction
// space.  There is no guarantee that the relocated location can be similarly
// encoded.
bool Operand::must_use_constant_pool() const {
  if (rmode_ == RelocInfo::EXTERNAL_REFERENCE) {
#ifdef DEBUG
    if (!Serializer::enabled()) {
      Serializer::TooLateToEnableNow();
    }
#endif  // def DEBUG
    return Serializer::enabled();
  } else if (rmode_ == RelocInfo::NONE) {
    return false;
  }
  return true;
}


bool Operand::is_single_instruction(Instr instr) const {
  if (rm_.is_valid()) return true;
  uint32_t dummy1, dummy2;
  if (must_use_constant_pool() ||
      !fits_shifter(imm32_, &dummy1, &dummy2, &instr)) {
    // The immediate operand cannot be encoded as a shifter operand, or use of
    // constant pool is required. For a mov instruction not setting the
    // condition code additional instruction conventions can be used.
    if ((instr & ~kCondMask) == 13*B21) {  // mov, S not set
      if (must_use_constant_pool() ||
          !CpuFeatures::IsSupported(ARMv7)) {
        // mov instruction will be an ldr from constant pool (one instruction).
        return true;
      } else {
        // mov instruction will be a mov or movw followed by movt (two
        // instructions).
        return false;
      }
    } else {
      // If this is not a mov or mvn instruction there will always an additional
      // instructions - either mov or ldr. The mov might actually be two
      // instructions mov or movw followed by movt so including the actual
      // instruction two or three instructions will be generated.
      return false;
    }
  } else {
    // No use of constant pool and the immediate operand can be encoded as a
    // shifter operand.
    return true;
  }
}


void Assembler::addrmod1(Instr instr,
                         Register rn,
                         Register rd,
                         const Operand& x) {
  CheckBuffer();
  ASSERT((instr & ~(kCondMask | kOpCodeMask | S)) == 0);
  if (!x.rm_.is_valid()) {
    // Immediate.
    uint32_t rotate_imm;
    uint32_t immed_8;
    if (x.must_use_constant_pool() ||
        !fits_shifter(x.imm32_, &rotate_imm, &immed_8, &instr)) {
      // The immediate operand cannot be encoded as a shifter operand, so load
      // it first to register ip and change the original instruction to use ip.
      // However, if the original instruction is a 'mov rd, x' (not setting the
      // condition code), then replace it with a 'ldr rd, [pc]'.
      CHECK(!rn.is(ip));  // rn should never be ip, or will be trashed
      Condition cond = Instruction::ConditionField(instr);
      if ((instr & ~kCondMask) == 13*B21) {  // mov, S not set
        if (x.must_use_constant_pool() ||
            !CpuFeatures::IsSupported(ARMv7)) {
          RecordRelocInfo(x.rmode_, x.imm32_);
          ldr(rd, MemOperand(pc, 0), cond);
        } else {
          // Will probably use movw, will certainly not use constant pool.
          mov(rd, Operand(x.imm32_ & 0xffff), LeaveCC, cond);
          movt(rd, static_cast<uint32_t>(x.imm32_) >> 16, cond);
        }
      } else {
        // If this is not a mov or mvn instruction we may still be able to avoid
        // a constant pool entry by using mvn or movw.
        if (!x.must_use_constant_pool() &&
            (instr & kMovMvnMask) != kMovMvnPattern) {
          mov(ip, x, LeaveCC, cond);
        } else {
          RecordRelocInfo(x.rmode_, x.imm32_);
          ldr(ip, MemOperand(pc, 0), cond);
        }
        addrmod1(instr, rn, rd, Operand(ip));
      }
      return;
    }
    instr |= I | rotate_imm*B8 | immed_8;
  } else if (!x.rs_.is_valid()) {
    // Immediate shift.
    instr |= x.shift_imm_*B7 | x.shift_op_ | x.rm_.code();
  } else {
    // Register shift.
    ASSERT(!rn.is(pc) && !rd.is(pc) && !x.rm_.is(pc) && !x.rs_.is(pc));
    instr |= x.rs_.code()*B8 | x.shift_op_ | B4 | x.rm_.code();
  }
  emit(instr | rn.code()*B16 | rd.code()*B12);
  if (rn.is(pc) || x.rm_.is(pc)) {
    // Block constant pool emission for one instruction after reading pc.
    BlockConstPoolFor(1);
  }
}


void Assembler::addrmod2(Instr instr, Register rd, const MemOperand& x) {
  ASSERT((instr & ~(kCondMask | B | L)) == B26);
  int am = x.am_;
  if (!x.rm_.is_valid()) {
    // Immediate offset.
    int offset_12 = x.offset_;
    if (offset_12 < 0) {
      offset_12 = -offset_12;
      am ^= U;
    }
    if (!is_uint12(offset_12)) {
      // Immediate offset cannot be encoded, load it first to register ip
      // rn (and rd in a load) should never be ip, or will be trashed.
      ASSERT(!x.rn_.is(ip) && ((instr & L) == L || !rd.is(ip)));
      mov(ip, Operand(x.offset_), LeaveCC, Instruction::ConditionField(instr));
      addrmod2(instr, rd, MemOperand(x.rn_, ip, x.am_));
      return;
    }
    ASSERT(offset_12 >= 0);  // no masking needed
    instr |= offset_12;
  } else {
    // Register offset (shift_imm_ and shift_op_ are 0) or scaled
    // register offset the constructors make sure than both shift_imm_
    // and shift_op_ are initialized.
    ASSERT(!x.rm_.is(pc));
    instr |= B25 | x.shift_imm_*B7 | x.shift_op_ | x.rm_.code();
  }
  ASSERT((am & (P|W)) == P || !x.rn_.is(pc));  // no pc base with writeback
  emit(instr | am | x.rn_.code()*B16 | rd.code()*B12);
}


void Assembler::addrmod3(Instr instr, Register rd, const MemOperand& x) {
  ASSERT((instr & ~(kCondMask | L | S6 | H)) == (B4 | B7));
  ASSERT(x.rn_.is_valid());
  int am = x.am_;
  if (!x.rm_.is_valid()) {
    // Immediate offset.
    int offset_8 = x.offset_;
    if (offset_8 < 0) {
      offset_8 = -offset_8;
      am ^= U;
    }
    if (!is_uint8(offset_8)) {
      // Immediate offset cannot be encoded, load it first to register ip
      // rn (and rd in a load) should never be ip, or will be trashed.
      ASSERT(!x.rn_.is(ip) && ((instr & L) == L || !rd.is(ip)));
      mov(ip, Operand(x.offset_), LeaveCC, Instruction::ConditionField(instr));
      addrmod3(instr, rd, MemOperand(x.rn_, ip, x.am_));
      return;
    }
    ASSERT(offset_8 >= 0);  // no masking needed
    instr |= B | (offset_8 >> 4)*B8 | (offset_8 & 0xf);
  } else if (x.shift_imm_ != 0) {
    // Scaled register offset not supported, load index first
    // rn (and rd in a load) should never be ip, or will be trashed.
    ASSERT(!x.rn_.is(ip) && ((instr & L) == L || !rd.is(ip)));
    mov(ip, Operand(x.rm_, x.shift_op_, x.shift_imm_), LeaveCC,
        Instruction::ConditionField(instr));
    addrmod3(instr, rd, MemOperand(x.rn_, ip, x.am_));
    return;
  } else {
    // Register offset.
    ASSERT((am & (P|W)) == P || !x.rm_.is(pc));  // no pc index with writeback
    instr |= x.rm_.code();
  }
  ASSERT((am & (P|W)) == P || !x.rn_.is(pc));  // no pc base with writeback
  emit(instr | am | x.rn_.code()*B16 | rd.code()*B12);
}


void Assembler::addrmod4(Instr instr, Register rn, RegList rl) {
  ASSERT((instr & ~(kCondMask | P | U | W | L)) == B27);
  ASSERT(rl != 0);
  ASSERT(!rn.is(pc));
  emit(instr | rn.code()*B16 | rl);
}


void Assembler::addrmod5(Instr instr, CRegister crd, const MemOperand& x) {
  // Unindexed addressing is not encoded by this function.
  ASSERT_EQ((B27 | B26),
            (instr & ~(kCondMask | kCoprocessorMask | P | U | N | W | L)));
  ASSERT(x.rn_.is_valid() && !x.rm_.is_valid());
  int am = x.am_;
  int offset_8 = x.offset_;
  ASSERT((offset_8 & 3) == 0);  // offset must be an aligned word offset
  offset_8 >>= 2;
  if (offset_8 < 0) {
    offset_8 = -offset_8;
    am ^= U;
  }
  ASSERT(is_uint8(offset_8));  // unsigned word offset must fit in a byte
  ASSERT((am & (P|W)) == P || !x.rn_.is(pc));  // no pc base with writeback

  // Post-indexed addressing requires W == 1; different than in addrmod2/3.
  if ((am & P) == 0)
    am |= W;

  ASSERT(offset_8 >= 0);  // no masking needed
  emit(instr | am | x.rn_.code()*B16 | crd.code()*B12 | offset_8);
}


int Assembler::branch_offset(Label* L, bool jump_elimination_allowed) {
  int target_pos;
  if (L->is_bound()) {
    target_pos = L->pos();
  } else {
    if (L->is_linked()) {
      target_pos = L->pos();  // L's link
    } else {
      target_pos = kEndOfChain;
    }
    L->link_to(pc_offset());
  }

  // Block the emission of the constant pool, since the branch instruction must
  // be emitted at the pc offset recorded by the label.
  BlockConstPoolFor(1);
  return target_pos - (pc_offset() + kPcLoadDelta);
}


void Assembler::label_at_put(Label* L, int at_offset) {
  int target_pos;
  if (L->is_bound()) {
    target_pos = L->pos();
  } else {
    if (L->is_linked()) {
      target_pos = L->pos();  // L's link
    } else {
      target_pos = kEndOfChain;
    }
    L->link_to(at_offset);
    instr_at_put(at_offset, target_pos + (Code::kHeaderSize - kHeapObjectTag));
  }
}


// Branch instructions.
void Assembler::b(int branch_offset, Condition cond) {
  ASSERT((branch_offset & 3) == 0);
  int imm24 = branch_offset >> 2;
  ASSERT(is_int24(imm24));
  emit(cond | B27 | B25 | (imm24 & kImm24Mask));

  if (cond == al) {
    // Dead code is a good location to emit the constant pool.
    CheckConstPool(false, false);
  }
}


void Assembler::bl(int branch_offset, Condition cond) {
  positions_recorder()->WriteRecordedPositions();
  ASSERT((branch_offset & 3) == 0);
  int imm24 = branch_offset >> 2;
  ASSERT(is_int24(imm24));
  emit(cond | B27 | B25 | B24 | (imm24 & kImm24Mask));
}


void Assembler::blx(int branch_offset) {  // v5 and above
  positions_recorder()->WriteRecordedPositions();
  ASSERT((branch_offset & 1) == 0);
  int h = ((branch_offset & 2) >> 1)*B24;
  int imm24 = branch_offset >> 2;
  ASSERT(is_int24(imm24));
  emit(kSpecialCondition | B27 | B25 | h | (imm24 & kImm24Mask));
}


void Assembler::blx(Register target, Condition cond) {  // v5 and above
  positions_recorder()->WriteRecordedPositions();
  ASSERT(!target.is(pc));
  emit(cond | B24 | B21 | 15*B16 | 15*B12 | 15*B8 | BLX | target.code());
}


void Assembler::bx(Register target, Condition cond) {  // v5 and above, plus v4t
  positions_recorder()->WriteRecordedPositions();
  ASSERT(!target.is(pc));  // use of pc is actually allowed, but discouraged
  emit(cond | B24 | B21 | 15*B16 | 15*B12 | 15*B8 | BX | target.code());
}


// Data-processing instructions.

void Assembler::and_(Register dst, Register src1, const Operand& src2,
                     SBit s, Condition cond) {
  addrmod1(cond | AND | s, src1, dst, src2);
}


void Assembler::eor(Register dst, Register src1, const Operand& src2,
                    SBit s, Condition cond) {
  addrmod1(cond | EOR | s, src1, dst, src2);
}


void Assembler::sub(Register dst, Register src1, const Operand& src2,
                    SBit s, Condition cond) {
  addrmod1(cond | SUB | s, src1, dst, src2);
}


void Assembler::rsb(Register dst, Register src1, const Operand& src2,
                    SBit s, Condition cond) {
  addrmod1(cond | RSB | s, src1, dst, src2);
}


void Assembler::add(Register dst, Register src1, const Operand& src2,
                    SBit s, Condition cond) {
  addrmod1(cond | ADD | s, src1, dst, src2);
}


void Assembler::adc(Register dst, Register src1, const Operand& src2,
                    SBit s, Condition cond) {
  addrmod1(cond | ADC | s, src1, dst, src2);
}


void Assembler::sbc(Register dst, Register src1, const Operand& src2,
                    SBit s, Condition cond) {
  addrmod1(cond | SBC | s, src1, dst, src2);
}


void Assembler::rsc(Register dst, Register src1, const Operand& src2,
                    SBit s, Condition cond) {
  addrmod1(cond | RSC | s, src1, dst, src2);
}


void Assembler::tst(Register src1, const Operand& src2, Condition cond) {
  addrmod1(cond | TST | S, src1, r0, src2);
}


void Assembler::teq(Register src1, const Operand& src2, Condition cond) {
  addrmod1(cond | TEQ | S, src1, r0, src2);
}


void Assembler::cmp(Register src1, const Operand& src2, Condition cond) {
  addrmod1(cond | CMP | S, src1, r0, src2);
}


void Assembler::cmp_raw_immediate(
    Register src, int raw_immediate, Condition cond) {
  ASSERT(is_uint12(raw_immediate));
  emit(cond | I | CMP | S | src.code() << 16 | raw_immediate);
}


void Assembler::cmn(Register src1, const Operand& src2, Condition cond) {
  addrmod1(cond | CMN | S, src1, r0, src2);
}


void Assembler::orr(Register dst, Register src1, const Operand& src2,
                    SBit s, Condition cond) {
  addrmod1(cond | ORR | s, src1, dst, src2);
}


void Assembler::mov(Register dst, const Operand& src, SBit s, Condition cond) {
  if (dst.is(pc)) {
    positions_recorder()->WriteRecordedPositions();
  }
  // Don't allow nop instructions in the form mov rn, rn to be generated using
  // the mov instruction. They must be generated using nop(int/NopMarkerTypes)
  // or MarkCode(int/NopMarkerTypes) pseudo instructions.
  ASSERT(!(src.is_reg() && src.rm().is(dst) && s == LeaveCC && cond == al));
  addrmod1(cond | MOV | s, r0, dst, src);
}


void Assembler::movw(Register reg, uint32_t immediate, Condition cond) {
  ASSERT(immediate < 0x10000);
  mov(reg, Operand(immediate), LeaveCC, cond);
}


void Assembler::movt(Register reg, uint32_t immediate, Condition cond) {
  emit(cond | 0x34*B20 | reg.code()*B12 | EncodeMovwImmediate(immediate));
}


void Assembler::bic(Register dst, Register src1, const Operand& src2,
                    SBit s, Condition cond) {
  addrmod1(cond | BIC | s, src1, dst, src2);
}


void Assembler::mvn(Register dst, const Operand& src, SBit s, Condition cond) {
  addrmod1(cond | MVN | s, r0, dst, src);
}


// Multiply instructions.
void Assembler::mla(Register dst, Register src1, Register src2, Register srcA,
                    SBit s, Condition cond) {
  ASSERT(!dst.is(pc) && !src1.is(pc) && !src2.is(pc) && !srcA.is(pc));
  emit(cond | A | s | dst.code()*B16 | srcA.code()*B12 |
       src2.code()*B8 | B7 | B4 | src1.code());
}


void Assembler::mul(Register dst, Register src1, Register src2,
                    SBit s, Condition cond) {
  ASSERT(!dst.is(pc) && !src1.is(pc) && !src2.is(pc));
  // dst goes in bits 16-19 for this instruction!
  emit(cond | s | dst.code()*B16 | src2.code()*B8 | B7 | B4 | src1.code());
}


void Assembler::smlal(Register dstL,
                      Register dstH,
                      Register src1,
                      Register src2,
                      SBit s,
                      Condition cond) {
  ASSERT(!dstL.is(pc) && !dstH.is(pc) && !src1.is(pc) && !src2.is(pc));
  ASSERT(!dstL.is(dstH));
  emit(cond | B23 | B22 | A | s | dstH.code()*B16 | dstL.code()*B12 |
       src2.code()*B8 | B7 | B4 | src1.code());
}


void Assembler::smull(Register dstL,
                      Register dstH,
                      Register src1,
                      Register src2,
                      SBit s,
                      Condition cond) {
  ASSERT(!dstL.is(pc) && !dstH.is(pc) && !src1.is(pc) && !src2.is(pc));
  ASSERT(!dstL.is(dstH));
  emit(cond | B23 | B22 | s | dstH.code()*B16 | dstL.code()*B12 |
       src2.code()*B8 | B7 | B4 | src1.code());
}


void Assembler::umlal(Register dstL,
                      Register dstH,
                      Register src1,
                      Register src2,
                      SBit s,
                      Condition cond) {
  ASSERT(!dstL.is(pc) && !dstH.is(pc) && !src1.is(pc) && !src2.is(pc));
  ASSERT(!dstL.is(dstH));
  emit(cond | B23 | A | s | dstH.code()*B16 | dstL.code()*B12 |
       src2.code()*B8 | B7 | B4 | src1.code());
}


void Assembler::umull(Register dstL,
                      Register dstH,
                      Register src1,
                      Register src2,
                      SBit s,
                      Condition cond) {
  ASSERT(!dstL.is(pc) && !dstH.is(pc) && !src1.is(pc) && !src2.is(pc));
  ASSERT(!dstL.is(dstH));
  emit(cond | B23 | s | dstH.code()*B16 | dstL.code()*B12 |
       src2.code()*B8 | B7 | B4 | src1.code());
}


// Miscellaneous arithmetic instructions.
void Assembler::clz(Register dst, Register src, Condition cond) {
  // v5 and above.
  ASSERT(!dst.is(pc) && !src.is(pc));
  emit(cond | B24 | B22 | B21 | 15*B16 | dst.code()*B12 |
       15*B8 | CLZ | src.code());
}


// Saturating instructions.

// Unsigned saturate.
void Assembler::usat(Register dst,
                     int satpos,
                     const Operand& src,
                     Condition cond) {
  // v6 and above.
  ASSERT(CpuFeatures::IsSupported(ARMv7));
  ASSERT(!dst.is(pc) && !src.rm_.is(pc));
  ASSERT((satpos >= 0) && (satpos <= 31));
  ASSERT((src.shift_op_ == ASR) || (src.shift_op_ == LSL));
  ASSERT(src.rs_.is(no_reg));

  int sh = 0;
  if (src.shift_op_ == ASR) {
      sh = 1;
  }

  emit(cond | 0x6*B24 | 0xe*B20 | satpos*B16 | dst.code()*B12 |
       src.shift_imm_*B7 | sh*B6 | 0x1*B4 | src.rm_.code());
}


// Bitfield manipulation instructions.

// Unsigned bit field extract.
// Extracts #width adjacent bits from position #lsb in a register, and
// writes them to the low bits of a destination register.
//   ubfx dst, src, #lsb, #width
void Assembler::ubfx(Register dst,
                     Register src,
                     int lsb,
                     int width,
                     Condition cond) {
  // v7 and above.
  ASSERT(CpuFeatures::IsSupported(ARMv7));
  ASSERT(!dst.is(pc) && !src.is(pc));
  ASSERT((lsb >= 0) && (lsb <= 31));
  ASSERT((width >= 1) && (width <= (32 - lsb)));
  emit(cond | 0xf*B23 | B22 | B21 | (width - 1)*B16 | dst.code()*B12 |
       lsb*B7 | B6 | B4 | src.code());
}


// Signed bit field extract.
// Extracts #width adjacent bits from position #lsb in a register, and
// writes them to the low bits of a destination register. The extracted
// value is sign extended to fill the destination register.
//   sbfx dst, src, #lsb, #width
void Assembler::sbfx(Register dst,
                     Register src,
                     int lsb,
                     int width,
                     Condition cond) {
  // v7 and above.
  ASSERT(CpuFeatures::IsSupported(ARMv7));
  ASSERT(!dst.is(pc) && !src.is(pc));
  ASSERT((lsb >= 0) && (lsb <= 31));
  ASSERT((width >= 1) && (width <= (32 - lsb)));
  emit(cond | 0xf*B23 | B21 | (width - 1)*B16 | dst.code()*B12 |
       lsb*B7 | B6 | B4 | src.code());
}


// Bit field clear.
// Sets #width adjacent bits at position #lsb in the destination register
// to zero, preserving the value of the other bits.
//   bfc dst, #lsb, #width
void Assembler::bfc(Register dst, int lsb, int width, Condition cond) {
  // v7 and above.
  ASSERT(CpuFeatures::IsSupported(ARMv7));
  ASSERT(!dst.is(pc));
  ASSERT((lsb >= 0) && (lsb <= 31));
  ASSERT((width >= 1) && (width <= (32 - lsb)));
  int msb = lsb + width - 1;
  emit(cond | 0x1f*B22 | msb*B16 | dst.code()*B12 | lsb*B7 | B4 | 0xf);
}


// Bit field insert.
// Inserts #width adjacent bits from the low bits of the source register
// into position #lsb of the destination register.
//   bfi dst, src, #lsb, #width
void Assembler::bfi(Register dst,
                    Register src,
                    int lsb,
                    int width,
                    Condition cond) {
  // v7 and above.
  ASSERT(CpuFeatures::IsSupported(ARMv7));
  ASSERT(!dst.is(pc) && !src.is(pc));
  ASSERT((lsb >= 0) && (lsb <= 31));
  ASSERT((width >= 1) && (width <= (32 - lsb)));
  int msb = lsb + width - 1;
  emit(cond | 0x1f*B22 | msb*B16 | dst.code()*B12 | lsb*B7 | B4 |
       src.code());
}


// Status register access instructions.
void Assembler::mrs(Register dst, SRegister s, Condition cond) {
  ASSERT(!dst.is(pc));
  emit(cond | B24 | s | 15*B16 | dst.code()*B12);
}


void Assembler::msr(SRegisterFieldMask fields, const Operand& src,
                    Condition cond) {
  ASSERT(fields >= B16 && fields < B20);  // at least one field set
  Instr instr;
  if (!src.rm_.is_valid()) {
    // Immediate.
    uint32_t rotate_imm;
    uint32_t immed_8;
    if (src.must_use_constant_pool() ||
        !fits_shifter(src.imm32_, &rotate_imm, &immed_8, NULL)) {
      // Immediate operand cannot be encoded, load it first to register ip.
      RecordRelocInfo(src.rmode_, src.imm32_);
      ldr(ip, MemOperand(pc, 0), cond);
      msr(fields, Operand(ip), cond);
      return;
    }
    instr = I | rotate_imm*B8 | immed_8;
  } else {
    ASSERT(!src.rs_.is_valid() && src.shift_imm_ == 0);  // only rm allowed
    instr = src.rm_.code();
  }
  emit(cond | instr | B24 | B21 | fields | 15*B12);
}


// Load/Store instructions.
void Assembler::ldr(Register dst, const MemOperand& src, Condition cond) {
  if (dst.is(pc)) {
    positions_recorder()->WriteRecordedPositions();
  }
  addrmod2(cond | B26 | L, dst, src);
}


void Assembler::str(Register src, const MemOperand& dst, Condition cond) {
  addrmod2(cond | B26, src, dst);
}


void Assembler::ldrb(Register dst, const MemOperand& src, Condition cond) {
  addrmod2(cond | B26 | B | L, dst, src);
}


void Assembler::strb(Register src, const MemOperand& dst, Condition cond) {
  addrmod2(cond | B26 | B, src, dst);
}


void Assembler::ldrh(Register dst, const MemOperand& src, Condition cond) {
  addrmod3(cond | L | B7 | H | B4, dst, src);
}


void Assembler::strh(Register src, const MemOperand& dst, Condition cond) {
  addrmod3(cond | B7 | H | B4, src, dst);
}


void Assembler::ldrsb(Register dst, const MemOperand& src, Condition cond) {
  addrmod3(cond | L | B7 | S6 | B4, dst, src);
}


void Assembler::ldrsh(Register dst, const MemOperand& src, Condition cond) {
  addrmod3(cond | L | B7 | S6 | H | B4, dst, src);
}


void Assembler::ldrd(Register dst1, Register dst2,
                     const MemOperand& src, Condition cond) {
  ASSERT(CpuFeatures::IsEnabled(ARMv7));
  ASSERT(src.rm().is(no_reg));
  ASSERT(!dst1.is(lr));  // r14.
  ASSERT_EQ(0, dst1.code() % 2);
  ASSERT_EQ(dst1.code() + 1, dst2.code());
  addrmod3(cond | B7 | B6 | B4, dst1, src);
}


void Assembler::strd(Register src1, Register src2,
                     const MemOperand& dst, Condition cond) {
  ASSERT(dst.rm().is(no_reg));
  ASSERT(!src1.is(lr));  // r14.
  ASSERT_EQ(0, src1.code() % 2);
  ASSERT_EQ(src1.code() + 1, src2.code());
  ASSERT(CpuFeatures::IsEnabled(ARMv7));
  addrmod3(cond | B7 | B6 | B5 | B4, src1, dst);
}

// Load/Store multiple instructions.
void Assembler::ldm(BlockAddrMode am,
                    Register base,
                    RegList dst,
                    Condition cond) {
  // ABI stack constraint: ldmxx base, {..sp..}  base != sp  is not restartable.
  ASSERT(base.is(sp) || (dst & sp.bit()) == 0);

  addrmod4(cond | B27 | am | L, base, dst);

  // Emit the constant pool after a function return implemented by ldm ..{..pc}.
  if (cond == al && (dst & pc.bit()) != 0) {
    // There is a slight chance that the ldm instruction was actually a call,
    // in which case it would be wrong to return into the constant pool; we
    // recognize this case by checking if the emission of the pool was blocked
    // at the pc of the ldm instruction by a mov lr, pc instruction; if this is
    // the case, we emit a jump over the pool.
    CheckConstPool(true, no_const_pool_before_ == pc_offset() - kInstrSize);
  }
}


void Assembler::stm(BlockAddrMode am,
                    Register base,
                    RegList src,
                    Condition cond) {
  addrmod4(cond | B27 | am, base, src);
}


// Exception-generating instructions and debugging support.
// Stops with a non-negative code less than kNumOfWatchedStops support
// enabling/disabling and a counter feature. See simulator-arm.h .
void Assembler::stop(const char* msg, Condition cond, int32_t code) {
#ifndef __arm__
  ASSERT(code >= kDefaultStopCode);
  {
    // The Simulator will handle the stop instruction and get the message
    // address. It expects to find the address just after the svc instruction.
    BlockConstPoolScope block_const_pool(this);
    if (code >= 0) {
      svc(kStopCode + code, cond);
    } else {
      svc(kStopCode + kMaxStopCode, cond);
    }
    emit(reinterpret_cast<Instr>(msg));
  }
#else  // def __arm__
#ifdef CAN_USE_ARMV5_INSTRUCTIONS
  if (cond != al) {
    Label skip;
    b(&skip, NegateCondition(cond));
    bkpt(0);
    bind(&skip);
  } else {
    bkpt(0);
  }
#else  // ndef CAN_USE_ARMV5_INSTRUCTIONS
  svc(0x9f0001, cond);
#endif  // ndef CAN_USE_ARMV5_INSTRUCTIONS
#endif  // def __arm__
}


void Assembler::bkpt(uint32_t imm16) {  // v5 and above
  ASSERT(is_uint16(imm16));
  emit(al | B24 | B21 | (imm16 >> 4)*B8 | BKPT | (imm16 & 0xf));
}


void Assembler::svc(uint32_t imm24, Condition cond) {
  ASSERT(is_uint24(imm24));
  emit(cond | 15*B24 | imm24);
}


// Coprocessor instructions.
void Assembler::cdp(Coprocessor coproc,
                    int opcode_1,
                    CRegister crd,
                    CRegister crn,
                    CRegister crm,
                    int opcode_2,
                    Condition cond) {
  ASSERT(is_uint4(opcode_1) && is_uint3(opcode_2));
  emit(cond | B27 | B26 | B25 | (opcode_1 & 15)*B20 | crn.code()*B16 |
       crd.code()*B12 | coproc*B8 | (opcode_2 & 7)*B5 | crm.code());
}


void Assembler::cdp2(Coprocessor coproc,
                     int opcode_1,
                     CRegister crd,
                     CRegister crn,
                     CRegister crm,
                     int opcode_2) {  // v5 and above
  cdp(coproc, opcode_1, crd, crn, crm, opcode_2, kSpecialCondition);
}


void Assembler::mcr(Coprocessor coproc,
                    int opcode_1,
                    Register rd,
                    CRegister crn,
                    CRegister crm,
                    int opcode_2,
                    Condition cond) {
  ASSERT(is_uint3(opcode_1) && is_uint3(opcode_2));
  emit(cond | B27 | B26 | B25 | (opcode_1 & 7)*B21 | crn.code()*B16 |
       rd.code()*B12 | coproc*B8 | (opcode_2 & 7)*B5 | B4 | crm.code());
}


void Assembler::mcr2(Coprocessor coproc,
                     int opcode_1,
                     Register rd,
                     CRegister crn,
                     CRegister crm,
                     int opcode_2) {  // v5 and above
  mcr(coproc, opcode_1, rd, crn, crm, opcode_2, kSpecialCondition);
}


void Assembler::mrc(Coprocessor coproc,
                    int opcode_1,
                    Register rd,
                    CRegister crn,
                    CRegister crm,
                    int opcode_2,
                    Condition cond) {
  ASSERT(is_uint3(opcode_1) && is_uint3(opcode_2));
  emit(cond | B27 | B26 | B25 | (opcode_1 & 7)*B21 | L | crn.code()*B16 |
       rd.code()*B12 | coproc*B8 | (opcode_2 & 7)*B5 | B4 | crm.code());
}


void Assembler::mrc2(Coprocessor coproc,
                     int opcode_1,
                     Register rd,
                     CRegister crn,
                     CRegister crm,
                     int opcode_2) {  // v5 and above
  mrc(coproc, opcode_1, rd, crn, crm, opcode_2, kSpecialCondition);
}


void Assembler::ldc(Coprocessor coproc,
                    CRegister crd,
                    const MemOperand& src,
                    LFlag l,
                    Condition cond) {
  addrmod5(cond | B27 | B26 | l | L | coproc*B8, crd, src);
}


void Assembler::ldc(Coprocessor coproc,
                    CRegister crd,
                    Register rn,
                    int option,
                    LFlag l,
                    Condition cond) {
  // Unindexed addressing.
  ASSERT(is_uint8(option));
  emit(cond | B27 | B26 | U | l | L | rn.code()*B16 | crd.code()*B12 |
       coproc*B8 | (option & 255));
}


void Assembler::ldc2(Coprocessor coproc,
                     CRegister crd,
                     const MemOperand& src,
                     LFlag l) {  // v5 and above
  ldc(coproc, crd, src, l, kSpecialCondition);
}


void Assembler::ldc2(Coprocessor coproc,
                     CRegister crd,
                     Register rn,
                     int option,
                     LFlag l) {  // v5 and above
  ldc(coproc, crd, rn, option, l, kSpecialCondition);
}


// Support for VFP.

void Assembler::vldr(const DwVfpRegister dst,
                     const Register base,
                     int offset,
                     const Condition cond) {
  // Ddst = MEM(Rbase + offset).
  // Instruction details available in ARM DDI 0406A, A8-628.
  // cond(31-28) | 1101(27-24)| U001(23-20) | Rbase(19-16) |
  // Vdst(15-12) | 1011(11-8) | offset
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  int u = 1;
  if (offset < 0) {
    offset = -offset;
    u = 0;
  }

  ASSERT(offset >= 0);
  if ((offset % 4) == 0 && (offset / 4) < 256) {
    emit(cond | u*B23 | 0xD1*B20 | base.code()*B16 | dst.code()*B12 |
         0xB*B8 | ((offset / 4) & 255));
  } else {
    // Larger offsets must be handled by computing the correct address
    // in the ip register.
    ASSERT(!base.is(ip));
    if (u == 1) {
      add(ip, base, Operand(offset));
    } else {
      sub(ip, base, Operand(offset));
    }
    emit(cond | 0xD1*B20 | ip.code()*B16 | dst.code()*B12 | 0xB*B8);
  }
}


void Assembler::vldr(const DwVfpRegister dst,
                     const MemOperand& operand,
                     const Condition cond) {
  ASSERT(!operand.rm().is_valid());
  ASSERT(operand.am_ == Offset);
  vldr(dst, operand.rn(), operand.offset(), cond);
}


void Assembler::vldr(const SwVfpRegister dst,
                     const Register base,
                     int offset,
                     const Condition cond) {
  // Sdst = MEM(Rbase + offset).
  // Instruction details available in ARM DDI 0406A, A8-628.
  // cond(31-28) | 1101(27-24)| U001(23-20) | Rbase(19-16) |
  // Vdst(15-12) | 1010(11-8) | offset
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  int u = 1;
  if (offset < 0) {
    offset = -offset;
    u = 0;
  }
  int sd, d;
  dst.split_code(&sd, &d);
  ASSERT(offset >= 0);

  if ((offset % 4) == 0 && (offset / 4) < 256) {
  emit(cond | u*B23 | d*B22 | 0xD1*B20 | base.code()*B16 | sd*B12 |
       0xA*B8 | ((offset / 4) & 255));
  } else {
    // Larger offsets must be handled by computing the correct address
    // in the ip register.
    ASSERT(!base.is(ip));
    if (u == 1) {
      add(ip, base, Operand(offset));
    } else {
      sub(ip, base, Operand(offset));
    }
    emit(cond | d*B22 | 0xD1*B20 | ip.code()*B16 | sd*B12 | 0xA*B8);
  }
}


void Assembler::vldr(const SwVfpRegister dst,
                     const MemOperand& operand,
                     const Condition cond) {
  ASSERT(!operand.rm().is_valid());
  ASSERT(operand.am_ == Offset);
  vldr(dst, operand.rn(), operand.offset(), cond);
}


void Assembler::vstr(const DwVfpRegister src,
                     const Register base,
                     int offset,
                     const Condition cond) {
  // MEM(Rbase + offset) = Dsrc.
  // Instruction details available in ARM DDI 0406A, A8-786.
  // cond(31-28) | 1101(27-24)| U000(23-20) | | Rbase(19-16) |
  // Vsrc(15-12) | 1011(11-8) | (offset/4)
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  int u = 1;
  if (offset < 0) {
    offset = -offset;
    u = 0;
  }
  ASSERT(offset >= 0);
  if ((offset % 4) == 0 && (offset / 4) < 256) {
    emit(cond | u*B23 | 0xD0*B20 | base.code()*B16 | src.code()*B12 |
         0xB*B8 | ((offset / 4) & 255));
  } else {
    // Larger offsets must be handled by computing the correct address
    // in the ip register.
    ASSERT(!base.is(ip));
    if (u == 1) {
      add(ip, base, Operand(offset));
    } else {
      sub(ip, base, Operand(offset));
    }
    emit(cond | 0xD0*B20 | ip.code()*B16 | src.code()*B12 | 0xB*B8);
  }
}


void Assembler::vstr(const DwVfpRegister src,
                     const MemOperand& operand,
                     const Condition cond) {
  ASSERT(!operand.rm().is_valid());
  ASSERT(operand.am_ == Offset);
  vstr(src, operand.rn(), operand.offset(), cond);
}


void Assembler::vstr(const SwVfpRegister src,
                     const Register base,
                     int offset,
                     const Condition cond) {
  // MEM(Rbase + offset) = SSrc.
  // Instruction details available in ARM DDI 0406A, A8-786.
  // cond(31-28) | 1101(27-24)| U000(23-20) | Rbase(19-16) |
  // Vdst(15-12) | 1010(11-8) | (offset/4)
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  int u = 1;
  if (offset < 0) {
    offset = -offset;
    u = 0;
  }
  int sd, d;
  src.split_code(&sd, &d);
  ASSERT(offset >= 0);
  if ((offset % 4) == 0 && (offset / 4) < 256) {
    emit(cond | u*B23 | d*B22 | 0xD0*B20 | base.code()*B16 | sd*B12 |
         0xA*B8 | ((offset / 4) & 255));
  } else {
    // Larger offsets must be handled by computing the correct address
    // in the ip register.
    ASSERT(!base.is(ip));
    if (u == 1) {
      add(ip, base, Operand(offset));
    } else {
      sub(ip, base, Operand(offset));
    }
    emit(cond | d*B22 | 0xD0*B20 | ip.code()*B16 | sd*B12 | 0xA*B8);
  }
}


void Assembler::vstr(const SwVfpRegister src,
                     const MemOperand& operand,
                     const Condition cond) {
  ASSERT(!operand.rm().is_valid());
  ASSERT(operand.am_ == Offset);
  vldr(src, operand.rn(), operand.offset(), cond);
}


void  Assembler::vldm(BlockAddrMode am,
                      Register base,
                      DwVfpRegister first,
                      DwVfpRegister last,
                      Condition cond) {
  // Instruction details available in ARM DDI 0406A, A8-626.
  // cond(31-28) | 110(27-25)| PUDW1(24-20) | Rbase(19-16) |
  // first(15-12) | 1010(11-8) | (count * 2)
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  ASSERT_LE(first.code(), last.code());
  ASSERT(am == ia || am == ia_w || am == db_w);
  ASSERT(!base.is(pc));

  int sd, d;
  first.split_code(&sd, &d);
  int count = last.code() - first.code() + 1;
  emit(cond | B27 | B26 | am | d*B22 | B20 | base.code()*B16 | sd*B12 |
       0xB*B8 | count*2);
}


void  Assembler::vstm(BlockAddrMode am,
                      Register base,
                      DwVfpRegister first,
                      DwVfpRegister last,
                      Condition cond) {
  // Instruction details available in ARM DDI 0406A, A8-784.
  // cond(31-28) | 110(27-25)| PUDW0(24-20) | Rbase(19-16) |
  // first(15-12) | 1011(11-8) | (count * 2)
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  ASSERT_LE(first.code(), last.code());
  ASSERT(am == ia || am == ia_w || am == db_w);
  ASSERT(!base.is(pc));

  int sd, d;
  first.split_code(&sd, &d);
  int count = last.code() - first.code() + 1;
  emit(cond | B27 | B26 | am | d*B22 | base.code()*B16 | sd*B12 |
       0xB*B8 | count*2);
}

void  Assembler::vldm(BlockAddrMode am,
                      Register base,
                      SwVfpRegister first,
                      SwVfpRegister last,
                      Condition cond) {
  // Instruction details available in ARM DDI 0406A, A8-626.
  // cond(31-28) | 110(27-25)| PUDW1(24-20) | Rbase(19-16) |
  // first(15-12) | 1010(11-8) | (count/2)
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  ASSERT_LE(first.code(), last.code());
  ASSERT(am == ia || am == ia_w || am == db_w);
  ASSERT(!base.is(pc));

  int sd, d;
  first.split_code(&sd, &d);
  int count = last.code() - first.code() + 1;
  emit(cond | B27 | B26 | am | d*B22 | B20 | base.code()*B16 | sd*B12 |
       0xA*B8 | count);
}


void  Assembler::vstm(BlockAddrMode am,
                      Register base,
                      SwVfpRegister first,
                      SwVfpRegister last,
                      Condition cond) {
  // Instruction details available in ARM DDI 0406A, A8-784.
  // cond(31-28) | 110(27-25)| PUDW0(24-20) | Rbase(19-16) |
  // first(15-12) | 1011(11-8) | (count/2)
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  ASSERT_LE(first.code(), last.code());
  ASSERT(am == ia || am == ia_w || am == db_w);
  ASSERT(!base.is(pc));

  int sd, d;
  first.split_code(&sd, &d);
  int count = last.code() - first.code() + 1;
  emit(cond | B27 | B26 | am | d*B22 | base.code()*B16 | sd*B12 |
       0xA*B8 | count);
}

static void DoubleAsTwoUInt32(double d, uint32_t* lo, uint32_t* hi) {
  uint64_t i;
  memcpy(&i, &d, 8);

  *lo = i & 0xffffffff;
  *hi = i >> 32;
}

// Only works for little endian floating point formats.
// We don't support VFP on the mixed endian floating point platform.
static bool FitsVMOVDoubleImmediate(double d, uint32_t *encoding) {
  ASSERT(CpuFeatures::IsEnabled(VFP3));

  // VMOV can accept an immediate of the form:
  //
  //  +/- m * 2^(-n) where 16 <= m <= 31 and 0 <= n <= 7
  //
  // The immediate is encoded using an 8-bit quantity, comprised of two
  // 4-bit fields. For an 8-bit immediate of the form:
  //
  //  [abcdefgh]
  //
  // where a is the MSB and h is the LSB, an immediate 64-bit double can be
  // created of the form:
  //
  //  [aBbbbbbb,bbcdefgh,00000000,00000000,
  //      00000000,00000000,00000000,00000000]
  //
  // where B = ~b.
  //

  uint32_t lo, hi;
  DoubleAsTwoUInt32(d, &lo, &hi);

  // The most obvious constraint is the long block of zeroes.
  if ((lo != 0) || ((hi & 0xffff) != 0)) {
    return false;
  }

  // Bits 62:55 must be all clear or all set.
  if (((hi & 0x3fc00000) != 0) && ((hi & 0x3fc00000) != 0x3fc00000)) {
    return false;
  }

  // Bit 63 must be NOT bit 62.
  if (((hi ^ (hi << 1)) & (0x40000000)) == 0) {
    return false;
  }

  // Create the encoded immediate in the form:
  //  [00000000,0000abcd,00000000,0000efgh]
  *encoding  = (hi >> 16) & 0xf;      // Low nybble.
  *encoding |= (hi >> 4) & 0x70000;   // Low three bits of the high nybble.
  *encoding |= (hi >> 12) & 0x80000;  // Top bit of the high nybble.

  return true;
}


void Assembler::vmov(const DwVfpRegister dst,
                     double imm,
                     const Condition cond) {
  // Dd = immediate
  // Instruction details available in ARM DDI 0406B, A8-640.
  ASSERT(CpuFeatures::IsEnabled(VFP3));

  uint32_t enc;
  if (FitsVMOVDoubleImmediate(imm, &enc)) {
    // The double can be encoded in the instruction.
    emit(cond | 0xE*B24 | 0xB*B20 | dst.code()*B12 | 0xB*B8 | enc);
  } else {
    // Synthesise the double from ARM immediates. This could be implemented
    // using vldr from a constant pool.
    uint32_t lo, hi;
    DoubleAsTwoUInt32(imm, &lo, &hi);

    if (lo == hi) {
      // If the lo and hi parts of the double are equal, the literal is easier
      // to create. This is the case with 0.0.
      mov(ip, Operand(lo));
      vmov(dst, ip, ip);
    } else {
      // Move the low part of the double into the lower of the corresponsing S
      // registers of D register dst.
      mov(ip, Operand(lo));
      vmov(dst.low(), ip, cond);

      // Move the high part of the double into the higher of the corresponsing S
      // registers of D register dst.
      mov(ip, Operand(hi));
      vmov(dst.high(), ip, cond);
    }
  }
}


void Assembler::vmov(const SwVfpRegister dst,
                     const SwVfpRegister src,
                     const Condition cond) {
  // Sd = Sm
  // Instruction details available in ARM DDI 0406B, A8-642.
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  int sd, d, sm, m;
  dst.split_code(&sd, &d);
  src.split_code(&sm, &m);
  emit(cond | 0xE*B24 | d*B22 | 0xB*B20 | sd*B12 | 0xA*B8 | B6 | m*B5 | sm);
}


void Assembler::vmov(const DwVfpRegister dst,
                     const DwVfpRegister src,
                     const Condition cond) {
  // Dd = Dm
  // Instruction details available in ARM DDI 0406B, A8-642.
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  emit(cond | 0xE*B24 | 0xB*B20 |
       dst.code()*B12 | 0x5*B9 | B8 | B6 | src.code());
}


void Assembler::vmov(const DwVfpRegister dst,
                     const Register src1,
                     const Register src2,
                     const Condition cond) {
  // Dm = <Rt,Rt2>.
  // Instruction details available in ARM DDI 0406A, A8-646.
  // cond(31-28) | 1100(27-24)| 010(23-21) | op=0(20) | Rt2(19-16) |
  // Rt(15-12) | 1011(11-8) | 00(7-6) | M(5) | 1(4) | Vm
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  ASSERT(!src1.is(pc) && !src2.is(pc));
  emit(cond | 0xC*B24 | B22 | src2.code()*B16 |
       src1.code()*B12 | 0xB*B8 | B4 | dst.code());
}


void Assembler::vmov(const Register dst1,
                     const Register dst2,
                     const DwVfpRegister src,
                     const Condition cond) {
  // <Rt,Rt2> = Dm.
  // Instruction details available in ARM DDI 0406A, A8-646.
  // cond(31-28) | 1100(27-24)| 010(23-21) | op=1(20) | Rt2(19-16) |
  // Rt(15-12) | 1011(11-8) | 00(7-6) | M(5) | 1(4) | Vm
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  ASSERT(!dst1.is(pc) && !dst2.is(pc));
  emit(cond | 0xC*B24 | B22 | B20 | dst2.code()*B16 |
       dst1.code()*B12 | 0xB*B8 | B4 | src.code());
}


void Assembler::vmov(const SwVfpRegister dst,
                     const Register src,
                     const Condition cond) {
  // Sn = Rt.
  // Instruction details available in ARM DDI 0406A, A8-642.
  // cond(31-28) | 1110(27-24)| 000(23-21) | op=0(20) | Vn(19-16) |
  // Rt(15-12) | 1010(11-8) | N(7)=0 | 00(6-5) | 1(4) | 0000(3-0)
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  ASSERT(!src.is(pc));
  int sn, n;
  dst.split_code(&sn, &n);
  emit(cond | 0xE*B24 | sn*B16 | src.code()*B12 | 0xA*B8 | n*B7 | B4);
}


void Assembler::vmov(const Register dst,
                     const SwVfpRegister src,
                     const Condition cond) {
  // Rt = Sn.
  // Instruction details available in ARM DDI 0406A, A8-642.
  // cond(31-28) | 1110(27-24)| 000(23-21) | op=1(20) | Vn(19-16) |
  // Rt(15-12) | 1010(11-8) | N(7)=0 | 00(6-5) | 1(4) | 0000(3-0)
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  ASSERT(!dst.is(pc));
  int sn, n;
  src.split_code(&sn, &n);
  emit(cond | 0xE*B24 | B20 | sn*B16 | dst.code()*B12 | 0xA*B8 | n*B7 | B4);
}


// Type of data to read from or write to VFP register.
// Used as specifier in generic vcvt instruction.
enum VFPType { S32, U32, F32, F64 };


static bool IsSignedVFPType(VFPType type) {
  switch (type) {
    case S32:
      return true;
    case U32:
      return false;
    default:
      UNREACHABLE();
      return false;
  }
}


static bool IsIntegerVFPType(VFPType type) {
  switch (type) {
    case S32:
    case U32:
      return true;
    case F32:
    case F64:
      return false;
    default:
      UNREACHABLE();
      return false;
  }
}


static bool IsDoubleVFPType(VFPType type) {
  switch (type) {
    case F32:
      return false;
    case F64:
      return true;
    default:
      UNREACHABLE();
      return false;
  }
}


// Split five bit reg_code based on size of reg_type.
//  32-bit register codes are Vm:M
//  64-bit register codes are M:Vm
// where Vm is four bits, and M is a single bit.
static void SplitRegCode(VFPType reg_type,
                         int reg_code,
                         int* vm,
                         int* m) {
  ASSERT((reg_code >= 0) && (reg_code <= 31));
  if (IsIntegerVFPType(reg_type) || !IsDoubleVFPType(reg_type)) {
    // 32 bit type.
    *m  = reg_code & 0x1;
    *vm = reg_code >> 1;
  } else {
    // 64 bit type.
    *m  = (reg_code & 0x10) >> 4;
    *vm = reg_code & 0x0F;
  }
}


// Encode vcvt.src_type.dst_type instruction.
static Instr EncodeVCVT(const VFPType dst_type,
                        const int dst_code,
                        const VFPType src_type,
                        const int src_code,
                        VFPConversionMode mode,
                        const Condition cond) {
  ASSERT(src_type != dst_type);
  int D, Vd, M, Vm;
  SplitRegCode(src_type, src_code, &Vm, &M);
  SplitRegCode(dst_type, dst_code, &Vd, &D);

  if (IsIntegerVFPType(dst_type) || IsIntegerVFPType(src_type)) {
    // Conversion between IEEE floating point and 32-bit integer.
    // Instruction details available in ARM DDI 0406B, A8.6.295.
    // cond(31-28) | 11101(27-23)| D(22) | 11(21-20) | 1(19) | opc2(18-16) |
    // Vd(15-12) | 101(11-9) | sz(8) | op(7) | 1(6) | M(5) | 0(4) | Vm(3-0)
    ASSERT(!IsIntegerVFPType(dst_type) || !IsIntegerVFPType(src_type));

    int sz, opc2, op;

    if (IsIntegerVFPType(dst_type)) {
      opc2 = IsSignedVFPType(dst_type) ? 0x5 : 0x4;
      sz = IsDoubleVFPType(src_type) ? 0x1 : 0x0;
      op = mode;
    } else {
      ASSERT(IsIntegerVFPType(src_type));
      opc2 = 0x0;
      sz = IsDoubleVFPType(dst_type) ? 0x1 : 0x0;
      op = IsSignedVFPType(src_type) ? 0x1 : 0x0;
    }

    return (cond | 0xE*B24 | B23 | D*B22 | 0x3*B20 | B19 | opc2*B16 |
            Vd*B12 | 0x5*B9 | sz*B8 | op*B7 | B6 | M*B5 | Vm);
  } else {
    // Conversion between IEEE double and single precision.
    // Instruction details available in ARM DDI 0406B, A8.6.298.
    // cond(31-28) | 11101(27-23)| D(22) | 11(21-20) | 0111(19-16) |
    // Vd(15-12) | 101(11-9) | sz(8) | 1(7) | 1(6) | M(5) | 0(4) | Vm(3-0)
    int sz = IsDoubleVFPType(src_type) ? 0x1 : 0x0;
    return (cond | 0xE*B24 | B23 | D*B22 | 0x3*B20 | 0x7*B16 |
            Vd*B12 | 0x5*B9 | sz*B8 | B7 | B6 | M*B5 | Vm);
  }
}


void Assembler::vcvt_f64_s32(const DwVfpRegister dst,
                             const SwVfpRegister src,
                             VFPConversionMode mode,
                             const Condition cond) {
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  emit(EncodeVCVT(F64, dst.code(), S32, src.code(), mode, cond));
}


void Assembler::vcvt_f32_s32(const SwVfpRegister dst,
                             const SwVfpRegister src,
                             VFPConversionMode mode,
                             const Condition cond) {
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  emit(EncodeVCVT(F32, dst.code(), S32, src.code(), mode, cond));
}


void Assembler::vcvt_f64_u32(const DwVfpRegister dst,
                             const SwVfpRegister src,
                             VFPConversionMode mode,
                             const Condition cond) {
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  emit(EncodeVCVT(F64, dst.code(), U32, src.code(), mode, cond));
}


void Assembler::vcvt_s32_f64(const SwVfpRegister dst,
                             const DwVfpRegister src,
                             VFPConversionMode mode,
                             const Condition cond) {
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  emit(EncodeVCVT(S32, dst.code(), F64, src.code(), mode, cond));
}


void Assembler::vcvt_u32_f64(const SwVfpRegister dst,
                             const DwVfpRegister src,
                             VFPConversionMode mode,
                             const Condition cond) {
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  emit(EncodeVCVT(U32, dst.code(), F64, src.code(), mode, cond));
}


void Assembler::vcvt_f64_f32(const DwVfpRegister dst,
                             const SwVfpRegister src,
                             VFPConversionMode mode,
                             const Condition cond) {
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  emit(EncodeVCVT(F64, dst.code(), F32, src.code(), mode, cond));
}


void Assembler::vcvt_f32_f64(const SwVfpRegister dst,
                             const DwVfpRegister src,
                             VFPConversionMode mode,
                             const Condition cond) {
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  emit(EncodeVCVT(F32, dst.code(), F64, src.code(), mode, cond));
}


void Assembler::vneg(const DwVfpRegister dst,
                     const DwVfpRegister src,
                     const Condition cond) {
  emit(cond | 0xE*B24 | 0xB*B20 | B16 | dst.code()*B12 |
       0x5*B9 | B8 | B6 | src.code());
}


void Assembler::vabs(const DwVfpRegister dst,
                     const DwVfpRegister src,
                     const Condition cond) {
  emit(cond | 0xE*B24 | 0xB*B20 | dst.code()*B12 |
       0x5*B9 | B8 | 0x3*B6 | src.code());
}


void Assembler::vadd(const DwVfpRegister dst,
                     const DwVfpRegister src1,
                     const DwVfpRegister src2,
                     const Condition cond) {
  // Dd = vadd(Dn, Dm) double precision floating point addition.
  // Dd = D:Vd; Dm=M:Vm; Dn=N:Vm.
  // Instruction details available in ARM DDI 0406A, A8-536.
  // cond(31-28) | 11100(27-23)| D=?(22) | 11(21-20) | Vn(19-16) |
  // Vd(15-12) | 101(11-9) | sz(8)=1 | N(7)=0 | 0(6) | M=?(5) | 0(4) | Vm(3-0)
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  emit(cond | 0xE*B24 | 0x3*B20 | src1.code()*B16 |
       dst.code()*B12 | 0x5*B9 | B8 | src2.code());
}


void Assembler::vsub(const DwVfpRegister dst,
                     const DwVfpRegister src1,
                     const DwVfpRegister src2,
                     const Condition cond) {
  // Dd = vsub(Dn, Dm) double precision floating point subtraction.
  // Dd = D:Vd; Dm=M:Vm; Dn=N:Vm.
  // Instruction details available in ARM DDI 0406A, A8-784.
  // cond(31-28) | 11100(27-23)| D=?(22) | 11(21-20) | Vn(19-16) |
  // Vd(15-12) | 101(11-9) | sz(8)=1 | N(7)=0 | 1(6) | M=?(5) | 0(4) | Vm(3-0)
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  emit(cond | 0xE*B24 | 0x3*B20 | src1.code()*B16 |
       dst.code()*B12 | 0x5*B9 | B8 | B6 | src2.code());
}


void Assembler::vmul(const DwVfpRegister dst,
                     const DwVfpRegister src1,
                     const DwVfpRegister src2,
                     const Condition cond) {
  // Dd = vmul(Dn, Dm) double precision floating point multiplication.
  // Dd = D:Vd; Dm=M:Vm; Dn=N:Vm.
  // Instruction details available in ARM DDI 0406A, A8-784.
  // cond(31-28) | 11100(27-23)| D=?(22) | 10(21-20) | Vn(19-16) |
  // Vd(15-12) | 101(11-9) | sz(8)=1 | N(7)=0 | 0(6) | M=?(5) | 0(4) | Vm(3-0)
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  emit(cond | 0xE*B24 | 0x2*B20 | src1.code()*B16 |
       dst.code()*B12 | 0x5*B9 | B8 | src2.code());
}


void Assembler::vdiv(const DwVfpRegister dst,
                     const DwVfpRegister src1,
                     const DwVfpRegister src2,
                     const Condition cond) {
  // Dd = vdiv(Dn, Dm) double precision floating point division.
  // Dd = D:Vd; Dm=M:Vm; Dn=N:Vm.
  // Instruction details available in ARM DDI 0406A, A8-584.
  // cond(31-28) | 11101(27-23)| D=?(22) | 00(21-20) | Vn(19-16) |
  // Vd(15-12) | 101(11-9) | sz(8)=1 | N(7)=? | 0(6) | M=?(5) | 0(4) | Vm(3-0)
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  emit(cond | 0xE*B24 | B23 | src1.code()*B16 |
       dst.code()*B12 | 0x5*B9 | B8 | src2.code());
}


void Assembler::vcmp(const DwVfpRegister src1,
                     const DwVfpRegister src2,
                     const Condition cond) {
  // vcmp(Dd, Dm) double precision floating point comparison.
  // Instruction details available in ARM DDI 0406A, A8-570.
  // cond(31-28) | 11101 (27-23)| D=?(22) | 11 (21-20) | 0100 (19-16) |
  // Vd(15-12) | 101(11-9) | sz(8)=1 | E(7)=0 | 1(6) | M(5)=? | 0(4) | Vm(3-0)
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  emit(cond | 0xE*B24 |B23 | 0x3*B20 | B18 |
       src1.code()*B12 | 0x5*B9 | B8 | B6 | src2.code());
}


void Assembler::vcmp(const DwVfpRegister src1,
                     const double src2,
                     const Condition cond) {
  // vcmp(Dd, Dm) double precision floating point comparison.
  // Instruction details available in ARM DDI 0406A, A8-570.
  // cond(31-28) | 11101 (27-23)| D=?(22) | 11 (21-20) | 0101 (19-16) |
  // Vd(15-12) | 101(11-9) | sz(8)=1 | E(7)=0 | 1(6) | M(5)=? | 0(4) | 0000(3-0)
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  ASSERT(src2 == 0.0);
  emit(cond | 0xE*B24 |B23 | 0x3*B20 | B18 | B16 |
       src1.code()*B12 | 0x5*B9 | B8 | B6);
}


void Assembler::vmsr(Register dst, Condition cond) {
  // Instruction details available in ARM DDI 0406A, A8-652.
  // cond(31-28) | 1110 (27-24) | 1110(23-20)| 0001 (19-16) |
  // Rt(15-12) | 1010 (11-8) | 0(7) | 00 (6-5) | 1(4) | 0000(3-0)
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  emit(cond | 0xE*B24 | 0xE*B20 |  B16 |
       dst.code()*B12 | 0xA*B8 | B4);
}


void Assembler::vmrs(Register dst, Condition cond) {
  // Instruction details available in ARM DDI 0406A, A8-652.
  // cond(31-28) | 1110 (27-24) | 1111(23-20)| 0001 (19-16) |
  // Rt(15-12) | 1010 (11-8) | 0(7) | 00 (6-5) | 1(4) | 0000(3-0)
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  emit(cond | 0xE*B24 | 0xF*B20 |  B16 |
       dst.code()*B12 | 0xA*B8 | B4);
}


void Assembler::vsqrt(const DwVfpRegister dst,
                      const DwVfpRegister src,
                      const Condition cond) {
  // cond(31-28) | 11101 (27-23)| D=?(22) | 11 (21-20) | 0001 (19-16) |
  // Vd(15-12) | 101(11-9) | sz(8)=1 | 11 (7-6) | M(5)=? | 0(4) | Vm(3-0)
  ASSERT(CpuFeatures::IsEnabled(VFP3));
  emit(cond | 0xE*B24 | B23 | 0x3*B20 | B16 |
       dst.code()*B12 | 0x5*B9 | B8 | 3*B6 | src.code());
}


// Pseudo instructions.
void Assembler::nop(int type) {
  // This is mov rx, rx.
  ASSERT(0 <= type && type <= 14);  // mov pc, pc is not a nop.
  emit(al | 13*B21 | type*B12 | type);
}


bool Assembler::IsNop(Instr instr, int type) {
  // Check for mov rx, rx where x = type.
  ASSERT(0 <= type && type <= 14);  // mov pc, pc is not a nop.
  return instr == (al | 13*B21 | type*B12 | type);
}


bool Assembler::ImmediateFitsAddrMode1Instruction(int32_t imm32) {
  uint32_t dummy1;
  uint32_t dummy2;
  return fits_shifter(imm32, &dummy1, &dummy2, NULL);
}


// Debugging.
void Assembler::RecordJSReturn() {
  positions_recorder()->WriteRecordedPositions();
  CheckBuffer();
  RecordRelocInfo(RelocInfo::JS_RETURN);
}


void Assembler::RecordDebugBreakSlot() {
  positions_recorder()->WriteRecordedPositions();
  CheckBuffer();
  RecordRelocInfo(RelocInfo::DEBUG_BREAK_SLOT);
}


void Assembler::RecordComment(const char* msg) {
  if (FLAG_code_comments) {
    CheckBuffer();
    RecordRelocInfo(RelocInfo::COMMENT, reinterpret_cast<intptr_t>(msg));
  }
}


void Assembler::RecordConstPool(int size) {
  // We only need this for debugger support, to correctly compute offsets in the
  // code.
#ifdef ENABLE_DEBUGGER_SUPPORT
  RecordRelocInfo(RelocInfo::CONST_POOL, static_cast<intptr_t>(size));
#endif
}

void Assembler::GrowBuffer() {
  if (!own_buffer_) FATAL("external code buffer is too small");

  // Compute new buffer size.
  CodeDesc desc;  // the new buffer
  if (buffer_size_ < 4*KB) {
    desc.buffer_size = 4*KB;
  } else if (buffer_size_ < 1*MB) {
    desc.buffer_size = 2*buffer_size_;
  } else {
    desc.buffer_size = buffer_size_ + 1*MB;
  }
  CHECK_GT(desc.buffer_size, 0);  // no overflow

  // Set up new buffer.
  desc.buffer = NewArray<byte>(desc.buffer_size);

  desc.instr_size = pc_offset();
  desc.reloc_size = (buffer_ + buffer_size_) - reloc_info_writer.pos();

  // Copy the data.
  int pc_delta = desc.buffer - buffer_;
  int rc_delta = (desc.buffer + desc.buffer_size) - (buffer_ + buffer_size_);
  memmove(desc.buffer, buffer_, desc.instr_size);
  memmove(reloc_info_writer.pos() + rc_delta,
          reloc_info_writer.pos(), desc.reloc_size);

  // Switch buffers.
  DeleteArray(buffer_);
  buffer_ = desc.buffer;
  buffer_size_ = desc.buffer_size;
  pc_ += pc_delta;
  reloc_info_writer.Reposition(reloc_info_writer.pos() + rc_delta,
                               reloc_info_writer.last_pc() + pc_delta);

  // None of our relocation types are pc relative pointing outside the code
  // buffer nor pc absolute pointing inside the code buffer, so there is no need
  // to relocate any emitted relocation entries.

  // Relocate pending relocation entries.
  for (int i = 0; i < num_pending_reloc_info_; i++) {
    RelocInfo& rinfo = pending_reloc_info_[i];
    ASSERT(rinfo.rmode() != RelocInfo::COMMENT &&
           rinfo.rmode() != RelocInfo::POSITION);
    if (rinfo.rmode() != RelocInfo::JS_RETURN) {
      rinfo.set_pc(rinfo.pc() + pc_delta);
    }
  }
}


void Assembler::db(uint8_t data) {
  // No relocation info should be pending while using db. db is used
  // to write pure data with no pointers and the constant pool should
  // be emitted before using db.
  ASSERT(num_pending_reloc_info_ == 0);
  CheckBuffer();
  *reinterpret_cast<uint8_t*>(pc_) = data;
  pc_ += sizeof(uint8_t);
}


void Assembler::dd(uint32_t data) {
  // No relocation info should be pending while using dd. dd is used
  // to write pure data with no pointers and the constant pool should
  // be emitted before using dd.
  ASSERT(num_pending_reloc_info_ == 0);
  CheckBuffer();
  *reinterpret_cast<uint32_t*>(pc_) = data;
  pc_ += sizeof(uint32_t);
}


void Assembler::RecordRelocInfo(RelocInfo::Mode rmode, intptr_t data) {
  // We do not try to reuse pool constants.
  RelocInfo rinfo(pc_, rmode, data, NULL);
  if (((rmode >= RelocInfo::JS_RETURN) &&
       (rmode <= RelocInfo::DEBUG_BREAK_SLOT)) ||
      (rmode == RelocInfo::CONST_POOL)) {
    // Adjust code for new modes.
    ASSERT(RelocInfo::IsDebugBreakSlot(rmode)
           || RelocInfo::IsJSReturn(rmode)
           || RelocInfo::IsComment(rmode)
           || RelocInfo::IsPosition(rmode)
           || RelocInfo::IsConstPool(rmode));
    // These modes do not need an entry in the constant pool.
  } else {
    ASSERT(num_pending_reloc_info_ < kMaxNumPendingRelocInfo);
    if (num_pending_reloc_info_ == 0) {
      first_const_pool_use_ = pc_offset();
    }
    pending_reloc_info_[num_pending_reloc_info_++] = rinfo;
    // Make sure the constant pool is not emitted in place of the next
    // instruction for which we just recorded relocation info.
    BlockConstPoolFor(1);
  }
  if (rinfo.rmode() != RelocInfo::NONE) {
    // Don't record external references unless the heap will be serialized.
    if (rmode == RelocInfo::EXTERNAL_REFERENCE) {
#ifdef DEBUG
      if (!Serializer::enabled()) {
        Serializer::TooLateToEnableNow();
      }
#endif
      if (!Serializer::enabled() && !emit_debug_code()) {
        return;
      }
    }
    ASSERT(buffer_space() >= kMaxRelocSize);  // too late to grow buffer here
    if (rmode == RelocInfo::CODE_TARGET_WITH_ID) {
      RelocInfo reloc_info_with_ast_id(pc_, rmode, RecordedAstId(), NULL);
      ClearRecordedAstId();
      reloc_info_writer.Write(&reloc_info_with_ast_id);
    } else {
      reloc_info_writer.Write(&rinfo);
    }
  }
}


void Assembler::BlockConstPoolFor(int instructions) {
  int pc_limit = pc_offset() + instructions * kInstrSize;
  if (no_const_pool_before_ < pc_limit) {
    // If there are some pending entries, the constant pool cannot be blocked
    // further than first_const_pool_use_ + kMaxDistToPool
    ASSERT((num_pending_reloc_info_ == 0) ||
           (pc_limit < (first_const_pool_use_ + kMaxDistToPool)));
    no_const_pool_before_ = pc_limit;
  }

  if (next_buffer_check_ < no_const_pool_before_) {
    next_buffer_check_ = no_const_pool_before_;
  }
}


void Assembler::CheckConstPool(bool force_emit, bool require_jump) {
  // Some short sequence of instruction mustn't be broken up by constant pool
  // emission, such sequences are protected by calls to BlockConstPoolFor and
  // BlockConstPoolScope.
  if (is_const_pool_blocked()) {
    // Something is wrong if emission is forced and blocked at the same time.
    ASSERT(!force_emit);
    return;
  }

  // There is nothing to do if there are no pending constant pool entries.
  if (num_pending_reloc_info_ == 0)  {
    // Calculate the offset of the next check.
    next_buffer_check_ = pc_offset() + kCheckPoolInterval;
    return;
  }

  // We emit a constant pool when:
  //  * requested to do so by parameter force_emit (e.g. after each function).
  //  * the distance to the first instruction accessing the constant pool is
  //    kAvgDistToPool or more.
  //  * no jump is required and the distance to the first instruction accessing
  //    the constant pool is at least kMaxDistToPool / 2.
  ASSERT(first_const_pool_use_ >= 0);
  int dist = pc_offset() - first_const_pool_use_;
  if (!force_emit && dist < kAvgDistToPool &&
      (require_jump || (dist < (kMaxDistToPool / 2)))) {
    return;
  }

  // Check that the code buffer is large enough before emitting the constant
  // pool (include the jump over the pool and the constant pool marker and
  // the gap to the relocation information).
  int jump_instr = require_jump ? kInstrSize : 0;
  int size = jump_instr + kInstrSize + num_pending_reloc_info_ * kPointerSize;
  int needed_space = size + kGap;
  while (buffer_space() <= needed_space) GrowBuffer();

  {
    // Block recursive calls to CheckConstPool.
    BlockConstPoolScope block_const_pool(this);
    RecordComment("[ Constant Pool");
    RecordConstPool(size);

    // Emit jump over constant pool if necessary.
    Label after_pool;
    if (require_jump) {
      b(&after_pool);
    }

    // Put down constant pool marker "Undefined instruction" as specified by
    // A5.6 (ARMv7) Instruction set encoding.
    emit(kConstantPoolMarker | num_pending_reloc_info_);

    // Emit constant pool entries.
    for (int i = 0; i < num_pending_reloc_info_; i++) {
      RelocInfo& rinfo = pending_reloc_info_[i];
      ASSERT(rinfo.rmode() != RelocInfo::COMMENT &&
             rinfo.rmode() != RelocInfo::POSITION &&
             rinfo.rmode() != RelocInfo::STATEMENT_POSITION &&
             rinfo.rmode() != RelocInfo::CONST_POOL);

      Instr instr = instr_at(rinfo.pc());
      // Instruction to patch must be 'ldr rd, [pc, #offset]' with offset == 0.
      ASSERT(IsLdrPcImmediateOffset(instr) &&
             GetLdrRegisterImmediateOffset(instr) == 0);

      int delta = pc_ - rinfo.pc() - kPcLoadDelta;
      // 0 is the smallest delta:
      //   ldr rd, [pc, #0]
      //   constant pool marker
      //   data
      ASSERT(is_uint12(delta));

      instr_at_put(rinfo.pc(), SetLdrRegisterImmediateOffset(instr, delta));
      emit(rinfo.data());
    }

    num_pending_reloc_info_ = 0;
    first_const_pool_use_ = -1;

    RecordComment("]");

    if (after_pool.is_linked()) {
      bind(&after_pool);
    }
  }

  // Since a constant pool was just emitted, move the check offset forward by
  // the standard interval.
  next_buffer_check_ = pc_offset() + kCheckPoolInterval;
}


} }  // namespace v8::internal

#endif  // V8_TARGET_ARCH_ARM

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