// 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.

#include "vm/globals.h"
#if defined(TARGET_ARCH_ARM)

#include "vm/assembler.h"
#include "vm/cpu.h"
#include "vm/longjump.h"
#include "vm/runtime_entry.h"
#include "vm/simulator.h"
#include "vm/stack_frame.h"
#include "vm/stub_code.h"

// An extra check since we are assuming the existence of /proc/cpuinfo below.
#if !defined(USING_SIMULATOR) && !defined(__linux__) && !defined(ANDROID)
#error ARM cross-compile only supported on Linux
#endif

namespace dart {

DEFINE_FLAG(bool, print_stop_message, true, "Print stop message.");
DECLARE_FLAG(bool, inline_alloc);

// Instruction encoding bits.
enum {
  H   = 1 << 5,   // halfword (or byte)
  L   = 1 << 20,  // load (or store)
  S   = 1 << 20,  // set condition code (or leave unchanged)
  W   = 1 << 21,  // writeback base register (or leave unchanged)
  A   = 1 << 21,  // accumulate in multiply instruction (or not)
  B   = 1 << 22,  // unsigned byte (or word)
  D   = 1 << 22,  // high/lo bit of start of s/d register range
  N   = 1 << 22,  // long (or short)
  U   = 1 << 23,  // positive (or negative) offset/index
  P   = 1 << 24,  // offset/pre-indexed addressing (or post-indexed addressing)
  I   = 1 << 25,  // immediate shifter operand (or not)

  B0 = 1,
  B1 = 1 << 1,
  B2 = 1 << 2,
  B3 = 1 << 3,
  B4 = 1 << 4,
  B5 = 1 << 5,
  B6 = 1 << 6,
  B7 = 1 << 7,
  B8 = 1 << 8,
  B9 = 1 << 9,
  B10 = 1 << 10,
  B11 = 1 << 11,
  B12 = 1 << 12,
  B16 = 1 << 16,
  B17 = 1 << 17,
  B18 = 1 << 18,
  B19 = 1 << 19,
  B20 = 1 << 20,
  B21 = 1 << 21,
  B22 = 1 << 22,
  B23 = 1 << 23,
  B24 = 1 << 24,
  B25 = 1 << 25,
  B26 = 1 << 26,
  B27 = 1 << 27,
};


uint32_t Address::encoding3() const {
  if (kind_ == Immediate) {
    uint32_t offset = encoding_ & kOffset12Mask;
    ASSERT(offset < 256);
    return (encoding_ & ~kOffset12Mask) | B22 |
           ((offset & 0xf0) << 4) | (offset & 0xf);
  }
  ASSERT(kind_ == IndexRegister);
  return encoding_;
}


uint32_t Address::vencoding() const {
  ASSERT(kind_ == Immediate);
  uint32_t offset = encoding_ & kOffset12Mask;
  ASSERT(offset < (1 << 10));  // In the range 0 to +1020.
  ASSERT(Utils::IsAligned(offset, 4));  // Multiple of 4.
  int mode = encoding_ & ((8|4|1) << 21);
  ASSERT((mode == Offset) || (mode == NegOffset));
  uint32_t vencoding = (encoding_ & (0xf << kRnShift)) | (offset >> 2);
  if (mode == Offset) {
    vencoding |= 1 << 23;
  }
  return vencoding;
}


void Assembler::InitializeMemoryWithBreakpoints(uword data, intptr_t length) {
  ASSERT(Utils::IsAligned(data, 4));
  ASSERT(Utils::IsAligned(length, 4));
  const uword end = data + length;
  while (data < end) {
    *reinterpret_cast<int32_t*>(data) = Instr::kBreakPointInstruction;
    data += 4;
  }
}


void Assembler::Emit(int32_t value) {
  AssemblerBuffer::EnsureCapacity ensured(&buffer_);
  buffer_.Emit<int32_t>(value);
}


void Assembler::EmitType01(Condition cond,
                           int type,
                           Opcode opcode,
                           int set_cc,
                           Register rn,
                           Register rd,
                           Operand o) {
  ASSERT(rd != kNoRegister);
  ASSERT(cond != kNoCondition);
  int32_t encoding = static_cast<int32_t>(cond) << kConditionShift |
                     type << kTypeShift |
                     static_cast<int32_t>(opcode) << kOpcodeShift |
                     set_cc << kSShift |
                     static_cast<int32_t>(rn) << kRnShift |
                     static_cast<int32_t>(rd) << kRdShift |
                     o.encoding();
  Emit(encoding);
}


void Assembler::EmitType5(Condition cond, int32_t offset, bool link) {
  ASSERT(cond != kNoCondition);
  int32_t encoding = static_cast<int32_t>(cond) << kConditionShift |
                     5 << kTypeShift |
                     (link ? 1 : 0) << kLinkShift;
  Emit(Assembler::EncodeBranchOffset(offset, encoding));
}


void Assembler::EmitMemOp(Condition cond,
                          bool load,
                          bool byte,
                          Register rd,
                          Address ad) {
  ASSERT(rd != kNoRegister);
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B26 | (ad.kind() == Address::Immediate ? 0 : B25) |
                     (load ? L : 0) |
                     (byte ? B : 0) |
                     (static_cast<int32_t>(rd) << kRdShift) |
                     ad.encoding();
  Emit(encoding);
}


void Assembler::EmitMemOpAddressMode3(Condition cond,
                                      int32_t mode,
                                      Register rd,
                                      Address ad) {
  ASSERT(rd != kNoRegister);
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     mode |
                     (static_cast<int32_t>(rd) << kRdShift) |
                     ad.encoding3();
  Emit(encoding);
}


void Assembler::EmitMultiMemOp(Condition cond,
                               BlockAddressMode am,
                               bool load,
                               Register base,
                               RegList regs) {
  ASSERT(base != kNoRegister);
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B27 |
                     am |
                     (load ? L : 0) |
                     (static_cast<int32_t>(base) << kRnShift) |
                     regs;
  Emit(encoding);
}


void Assembler::EmitShiftImmediate(Condition cond,
                                   Shift opcode,
                                   Register rd,
                                   Register rm,
                                   Operand o) {
  ASSERT(cond != kNoCondition);
  ASSERT(o.type() == 1);
  int32_t encoding = static_cast<int32_t>(cond) << kConditionShift |
                     static_cast<int32_t>(MOV) << kOpcodeShift |
                     static_cast<int32_t>(rd) << kRdShift |
                     o.encoding() << kShiftImmShift |
                     static_cast<int32_t>(opcode) << kShiftShift |
                     static_cast<int32_t>(rm);
  Emit(encoding);
}


void Assembler::EmitShiftRegister(Condition cond,
                                  Shift opcode,
                                  Register rd,
                                  Register rm,
                                  Operand o) {
  ASSERT(cond != kNoCondition);
  ASSERT(o.type() == 0);
  int32_t encoding = static_cast<int32_t>(cond) << kConditionShift |
                     static_cast<int32_t>(MOV) << kOpcodeShift |
                     static_cast<int32_t>(rd) << kRdShift |
                     o.encoding() << kShiftRegisterShift |
                     static_cast<int32_t>(opcode) << kShiftShift |
                     B4 |
                     static_cast<int32_t>(rm);
  Emit(encoding);
}


void Assembler::and_(Register rd, Register rn, Operand o, Condition cond) {
  EmitType01(cond, o.type(), AND, 0, rn, rd, o);
}


void Assembler::eor(Register rd, Register rn, Operand o, Condition cond) {
  EmitType01(cond, o.type(), EOR, 0, rn, rd, o);
}


void Assembler::sub(Register rd, Register rn, Operand o, Condition cond) {
  EmitType01(cond, o.type(), SUB, 0, rn, rd, o);
}

void Assembler::rsb(Register rd, Register rn, Operand o, Condition cond) {
  EmitType01(cond, o.type(), RSB, 0, rn, rd, o);
}

void Assembler::rsbs(Register rd, Register rn, Operand o, Condition cond) {
  EmitType01(cond, o.type(), RSB, 1, rn, rd, o);
}


void Assembler::add(Register rd, Register rn, Operand o, Condition cond) {
  EmitType01(cond, o.type(), ADD, 0, rn, rd, o);
}


void Assembler::adds(Register rd, Register rn, Operand o, Condition cond) {
  EmitType01(cond, o.type(), ADD, 1, rn, rd, o);
}


void Assembler::subs(Register rd, Register rn, Operand o, Condition cond) {
  EmitType01(cond, o.type(), SUB, 1, rn, rd, o);
}


void Assembler::adc(Register rd, Register rn, Operand o, Condition cond) {
  EmitType01(cond, o.type(), ADC, 0, rn, rd, o);
}


void Assembler::adcs(Register rd, Register rn, Operand o, Condition cond) {
  EmitType01(cond, o.type(), ADC, 1, rn, rd, o);
}


void Assembler::sbc(Register rd, Register rn, Operand o, Condition cond) {
  EmitType01(cond, o.type(), SBC, 0, rn, rd, o);
}


void Assembler::sbcs(Register rd, Register rn, Operand o, Condition cond) {
  EmitType01(cond, o.type(), SBC, 1, rn, rd, o);
}


void Assembler::rsc(Register rd, Register rn, Operand o, Condition cond) {
  EmitType01(cond, o.type(), RSC, 0, rn, rd, o);
}


void Assembler::tst(Register rn, Operand o, Condition cond) {
  EmitType01(cond, o.type(), TST, 1, rn, R0, o);
}


void Assembler::teq(Register rn, Operand o, Condition cond) {
  EmitType01(cond, o.type(), TEQ, 1, rn, R0, o);
}


void Assembler::cmp(Register rn, Operand o, Condition cond) {
  EmitType01(cond, o.type(), CMP, 1, rn, R0, o);
}


void Assembler::cmn(Register rn, Operand o, Condition cond) {
  EmitType01(cond, o.type(), CMN, 1, rn, R0, o);
}


void Assembler::orr(Register rd, Register rn, Operand o, Condition cond) {
  EmitType01(cond, o.type(), ORR, 0, rn, rd, o);
}


void Assembler::orrs(Register rd, Register rn, Operand o, Condition cond) {
  EmitType01(cond, o.type(), ORR, 1, rn, rd, o);
}


void Assembler::mov(Register rd, Operand o, Condition cond) {
  EmitType01(cond, o.type(), MOV, 0, R0, rd, o);
}


void Assembler::movs(Register rd, Operand o, Condition cond) {
  EmitType01(cond, o.type(), MOV, 1, R0, rd, o);
}


void Assembler::bic(Register rd, Register rn, Operand o, Condition cond) {
  EmitType01(cond, o.type(), BIC, 0, rn, rd, o);
}


void Assembler::bics(Register rd, Register rn, Operand o, Condition cond) {
  EmitType01(cond, o.type(), BIC, 1, rn, rd, o);
}


void Assembler::mvn(Register rd, Operand o, Condition cond) {
  EmitType01(cond, o.type(), MVN, 0, R0, rd, o);
}


void Assembler::mvns(Register rd, Operand o, Condition cond) {
  EmitType01(cond, o.type(), MVN, 1, R0, rd, o);
}


void Assembler::clz(Register rd, Register rm, Condition cond) {
  ASSERT(rd != kNoRegister);
  ASSERT(rm != kNoRegister);
  ASSERT(cond != kNoCondition);
  ASSERT(rd != PC);
  ASSERT(rm != PC);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B24 | B22 | B21 | (0xf << 16) |
                     (static_cast<int32_t>(rd) << kRdShift) |
                     (0xf << 8) | B4 | static_cast<int32_t>(rm);
  Emit(encoding);
}


void Assembler::movw(Register rd, uint16_t imm16, Condition cond) {
  ASSERT(cond != kNoCondition);
  int32_t encoding = static_cast<int32_t>(cond) << kConditionShift |
                     B25 | B24 | ((imm16 >> 12) << 16) |
                     static_cast<int32_t>(rd) << kRdShift | (imm16 & 0xfff);
  Emit(encoding);
}


void Assembler::movt(Register rd, uint16_t imm16, Condition cond) {
  ASSERT(cond != kNoCondition);
  int32_t encoding = static_cast<int32_t>(cond) << kConditionShift |
                     B25 | B24 | B22 | ((imm16 >> 12) << 16) |
                     static_cast<int32_t>(rd) << kRdShift | (imm16 & 0xfff);
  Emit(encoding);
}


void Assembler::EmitMulOp(Condition cond, int32_t opcode,
                          Register rd, Register rn,
                          Register rm, Register rs) {
  ASSERT(rd != kNoRegister);
  ASSERT(rn != kNoRegister);
  ASSERT(rm != kNoRegister);
  ASSERT(rs != kNoRegister);
  ASSERT(cond != kNoCondition);
  int32_t encoding = opcode |
      (static_cast<int32_t>(cond) << kConditionShift) |
      (static_cast<int32_t>(rn) << kRnShift) |
      (static_cast<int32_t>(rd) << kRdShift) |
      (static_cast<int32_t>(rs) << kRsShift) |
      B7 | B4 |
      (static_cast<int32_t>(rm) << kRmShift);
  Emit(encoding);
}


void Assembler::mul(Register rd, Register rn, Register rm, Condition cond) {
  // Assembler registers rd, rn, rm are encoded as rn, rm, rs.
  EmitMulOp(cond, 0, R0, rd, rn, rm);
}


// Like mul, but sets condition flags.
void Assembler::muls(Register rd, Register rn, Register rm, Condition cond) {
  EmitMulOp(cond, B20, R0, rd, rn, rm);
}


void Assembler::mla(Register rd, Register rn,
                    Register rm, Register ra, Condition cond) {
  // rd <- ra + rn * rm.
  if (TargetCPUFeatures::arm_version() == ARMv7) {
    // Assembler registers rd, rn, rm, ra are encoded as rn, rm, rs, rd.
    EmitMulOp(cond, B21, ra, rd, rn, rm);
  } else {
    mul(IP, rn, rm, cond);
    add(rd, ra, Operand(IP), cond);
  }
}


void Assembler::mls(Register rd, Register rn,
                    Register rm, Register ra, Condition cond) {
  // rd <- ra - rn * rm.
  if (TargetCPUFeatures::arm_version() == ARMv7) {
    // Assembler registers rd, rn, rm, ra are encoded as rn, rm, rs, rd.
    EmitMulOp(cond, B22 | B21, ra, rd, rn, rm);
  } else {
    mul(IP, rn, rm, cond);
    sub(rd, ra, Operand(IP), cond);
  }
}


void Assembler::smull(Register rd_lo, Register rd_hi,
                      Register rn, Register rm, Condition cond) {
  ASSERT(TargetCPUFeatures::arm_version() == ARMv7);
  // Assembler registers rd_lo, rd_hi, rn, rm are encoded as rd, rn, rm, rs.
  EmitMulOp(cond, B23 | B22, rd_lo, rd_hi, rn, rm);
}


void Assembler::umull(Register rd_lo, Register rd_hi,
                      Register rn, Register rm, Condition cond) {
  ASSERT(TargetCPUFeatures::arm_version() == ARMv7);
  // Assembler registers rd_lo, rd_hi, rn, rm are encoded as rd, rn, rm, rs.
  EmitMulOp(cond, B23, rd_lo, rd_hi, rn, rm);
}


void Assembler::smlal(Register rd_lo, Register rd_hi,
                      Register rn, Register rm, Condition cond) {
  ASSERT(TargetCPUFeatures::arm_version() == ARMv7);
  // Assembler registers rd_lo, rd_hi, rn, rm are encoded as rd, rn, rm, rs.
  EmitMulOp(cond, B23 | B22 | B21, rd_lo, rd_hi, rn, rm);
}


void Assembler::umlal(Register rd_lo, Register rd_hi,
                      Register rn, Register rm, Condition cond) {
  ASSERT(TargetCPUFeatures::arm_version() == ARMv7);
  // Assembler registers rd_lo, rd_hi, rn, rm are encoded as rd, rn, rm, rs.
  EmitMulOp(cond, B23 | B21, rd_lo, rd_hi, rn, rm);
}


void Assembler::EmitDivOp(Condition cond, int32_t opcode,
                          Register rd, Register rn, Register rm) {
  ASSERT(TargetCPUFeatures::integer_division_supported());
  ASSERT(rd != kNoRegister);
  ASSERT(rn != kNoRegister);
  ASSERT(rm != kNoRegister);
  ASSERT(cond != kNoCondition);
  int32_t encoding = opcode |
    (static_cast<int32_t>(cond) << kConditionShift) |
    (static_cast<int32_t>(rn) << kDivRnShift) |
    (static_cast<int32_t>(rd) << kDivRdShift) |
    B26 | B25 | B24 | B20 | B4 |
    (static_cast<int32_t>(rm) << kDivRmShift);
  Emit(encoding);
}


void Assembler::sdiv(Register rd, Register rn, Register rm, Condition cond) {
  EmitDivOp(cond, 0, rd, rn, rm);
}


void Assembler::udiv(Register rd, Register rn, Register rm, Condition cond) {
  EmitDivOp(cond, B21 , rd, rn, rm);
}


void Assembler::ldr(Register rd, Address ad, Condition cond) {
  EmitMemOp(cond, true, false, rd, ad);
}


void Assembler::str(Register rd, Address ad, Condition cond) {
  EmitMemOp(cond, false, false, rd, ad);
}


void Assembler::ldrb(Register rd, Address ad, Condition cond) {
  EmitMemOp(cond, true, true, rd, ad);
}


void Assembler::strb(Register rd, Address ad, Condition cond) {
  EmitMemOp(cond, false, true, rd, ad);
}


void Assembler::ldrh(Register rd, Address ad, Condition cond) {
  EmitMemOpAddressMode3(cond, L | B7 | H | B4, rd, ad);
}


void Assembler::strh(Register rd, Address ad, Condition cond) {
  EmitMemOpAddressMode3(cond, B7 | H | B4, rd, ad);
}


void Assembler::ldrsb(Register rd, Address ad, Condition cond) {
  EmitMemOpAddressMode3(cond, L | B7 | B6 | B4, rd, ad);
}


void Assembler::ldrsh(Register rd, Address ad, Condition cond) {
  EmitMemOpAddressMode3(cond, L | B7 | B6 | H | B4, rd, ad);
}


void Assembler::ldrd(Register rd, Address ad, Condition cond) {
  ASSERT((rd % 2) == 0);
  EmitMemOpAddressMode3(cond, B7 | B6 | B4, rd, ad);
}


void Assembler::strd(Register rd, Address ad, Condition cond) {
  ASSERT((rd % 2) == 0);
  EmitMemOpAddressMode3(cond, B7 | B6 | B5 | B4, rd, ad);
}


void Assembler::ldm(BlockAddressMode am, Register base, RegList regs,
                    Condition cond) {
  ASSERT(regs != 0);
  EmitMultiMemOp(cond, am, true, base, regs);
  if (TargetCPUFeatures::arm_version() == ARMv5TE) {
    nop();
  }
}


void Assembler::stm(BlockAddressMode am, Register base, RegList regs,
                    Condition cond) {
  ASSERT(regs != 0);
  EmitMultiMemOp(cond, am, false, base, regs);
}


void Assembler::ldrex(Register rt, Register rn, Condition cond) {
  ASSERT(rn != kNoRegister);
  ASSERT(rt != kNoRegister);
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B24 |
                     B23 |
                     L   |
                     (static_cast<int32_t>(rn) << kLdExRnShift) |
                     (static_cast<int32_t>(rt) << kLdExRtShift) |
                     B11 | B10 | B9 | B8 | B7 | B4 | B3 | B2 | B1 | B0;
  Emit(encoding);
}


void Assembler::strex(Register rd, Register rt, Register rn, Condition cond) {
  ASSERT(rn != kNoRegister);
  ASSERT(rd != kNoRegister);
  ASSERT(rt != kNoRegister);
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B24 |
                     B23 |
                     (static_cast<int32_t>(rn) << kStrExRnShift) |
                     (static_cast<int32_t>(rd) << kStrExRdShift) |
                     B11 | B10 | B9 | B8 | B7 | B4 |
                     (static_cast<int32_t>(rt) << kStrExRtShift);
  Emit(encoding);
}


void Assembler::clrex() {
  int32_t encoding = (kSpecialCondition << kConditionShift) |
                     B26 | B24 | B22 | B21 | B20 | (0xff << 12) | B4 | 0xf;
  Emit(encoding);
}


void Assembler::nop(Condition cond) {
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B25 | B24 | B21 | (0xf << 12);
  Emit(encoding);
}


void Assembler::vmovsr(SRegister sn, Register rt, Condition cond) {
  ASSERT(TargetCPUFeatures::vfp_supported());
  ASSERT(sn != kNoSRegister);
  ASSERT(rt != kNoRegister);
  ASSERT(rt != SP);
  ASSERT(rt != PC);
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B27 | B26 | B25 |
                     ((static_cast<int32_t>(sn) >> 1)*B16) |
                     (static_cast<int32_t>(rt)*B12) | B11 | B9 |
                     ((static_cast<int32_t>(sn) & 1)*B7) | B4;
  Emit(encoding);
}


void Assembler::vmovrs(Register rt, SRegister sn, Condition cond) {
  ASSERT(TargetCPUFeatures::vfp_supported());
  ASSERT(sn != kNoSRegister);
  ASSERT(rt != kNoRegister);
  ASSERT(rt != SP);
  ASSERT(rt != PC);
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B27 | B26 | B25 | B20 |
                     ((static_cast<int32_t>(sn) >> 1)*B16) |
                     (static_cast<int32_t>(rt)*B12) | B11 | B9 |
                     ((static_cast<int32_t>(sn) & 1)*B7) | B4;
  Emit(encoding);
}


void Assembler::vmovsrr(SRegister sm, Register rt, Register rt2,
                        Condition cond) {
  ASSERT(TargetCPUFeatures::vfp_supported());
  ASSERT(sm != kNoSRegister);
  ASSERT(sm != S31);
  ASSERT(rt != kNoRegister);
  ASSERT(rt != SP);
  ASSERT(rt != PC);
  ASSERT(rt2 != kNoRegister);
  ASSERT(rt2 != SP);
  ASSERT(rt2 != PC);
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B27 | B26 | B22 |
                     (static_cast<int32_t>(rt2)*B16) |
                     (static_cast<int32_t>(rt)*B12) | B11 | B9 |
                     ((static_cast<int32_t>(sm) & 1)*B5) | B4 |
                     (static_cast<int32_t>(sm) >> 1);
  Emit(encoding);
}


void Assembler::vmovrrs(Register rt, Register rt2, SRegister sm,
                        Condition cond) {
  ASSERT(TargetCPUFeatures::vfp_supported());
  ASSERT(sm != kNoSRegister);
  ASSERT(sm != S31);
  ASSERT(rt != kNoRegister);
  ASSERT(rt != SP);
  ASSERT(rt != PC);
  ASSERT(rt2 != kNoRegister);
  ASSERT(rt2 != SP);
  ASSERT(rt2 != PC);
  ASSERT(rt != rt2);
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B27 | B26 | B22 | B20 |
                     (static_cast<int32_t>(rt2)*B16) |
                     (static_cast<int32_t>(rt)*B12) | B11 | B9 |
                     ((static_cast<int32_t>(sm) & 1)*B5) | B4 |
                     (static_cast<int32_t>(sm) >> 1);
  Emit(encoding);
}


void Assembler::vmovdrr(DRegister dm, Register rt, Register rt2,
                        Condition cond) {
  ASSERT(TargetCPUFeatures::vfp_supported());
  ASSERT(dm != kNoDRegister);
  ASSERT(rt != kNoRegister);
  ASSERT(rt != SP);
  ASSERT(rt != PC);
  ASSERT(rt2 != kNoRegister);
  ASSERT(rt2 != SP);
  ASSERT(rt2 != PC);
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B27 | B26 | B22 |
                     (static_cast<int32_t>(rt2)*B16) |
                     (static_cast<int32_t>(rt)*B12) | B11 | B9 | B8 |
                     ((static_cast<int32_t>(dm) >> 4)*B5) | B4 |
                     (static_cast<int32_t>(dm) & 0xf);
  Emit(encoding);
}


void Assembler::vmovrrd(Register rt, Register rt2, DRegister dm,
                        Condition cond) {
  ASSERT(TargetCPUFeatures::vfp_supported());
  ASSERT(dm != kNoDRegister);
  ASSERT(rt != kNoRegister);
  ASSERT(rt != SP);
  ASSERT(rt != PC);
  ASSERT(rt2 != kNoRegister);
  ASSERT(rt2 != SP);
  ASSERT(rt2 != PC);
  ASSERT(rt != rt2);
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B27 | B26 | B22 | B20 |
                     (static_cast<int32_t>(rt2)*B16) |
                     (static_cast<int32_t>(rt)*B12) | B11 | B9 | B8 |
                     ((static_cast<int32_t>(dm) >> 4)*B5) | B4 |
                     (static_cast<int32_t>(dm) & 0xf);
  Emit(encoding);
}


void Assembler::vldrs(SRegister sd, Address ad, Condition cond) {
  ASSERT(TargetCPUFeatures::vfp_supported());
  ASSERT(sd != kNoSRegister);
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B27 | B26 | B24 | B20 |
                     ((static_cast<int32_t>(sd) & 1)*B22) |
                     ((static_cast<int32_t>(sd) >> 1)*B12) |
                     B11 | B9 | ad.vencoding();
  Emit(encoding);
}


void Assembler::vstrs(SRegister sd, Address ad, Condition cond) {
  ASSERT(TargetCPUFeatures::vfp_supported());
  ASSERT(static_cast<Register>(ad.encoding_ & (0xf << kRnShift)) != PC);
  ASSERT(sd != kNoSRegister);
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B27 | B26 | B24 |
                     ((static_cast<int32_t>(sd) & 1)*B22) |
                     ((static_cast<int32_t>(sd) >> 1)*B12) |
                     B11 | B9 | ad.vencoding();
  Emit(encoding);
}


void Assembler::vldrd(DRegister dd, Address ad, Condition cond) {
  ASSERT(TargetCPUFeatures::vfp_supported());
  ASSERT(dd != kNoDRegister);
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B27 | B26 | B24 | B20 |
                     ((static_cast<int32_t>(dd) >> 4)*B22) |
                     ((static_cast<int32_t>(dd) & 0xf)*B12) |
                     B11 | B9 | B8 | ad.vencoding();
  Emit(encoding);
}


void Assembler::vstrd(DRegister dd, Address ad, Condition cond) {
  ASSERT(TargetCPUFeatures::vfp_supported());
  ASSERT(static_cast<Register>(ad.encoding_ & (0xf << kRnShift)) != PC);
  ASSERT(dd != kNoDRegister);
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B27 | B26 | B24 |
                     ((static_cast<int32_t>(dd) >> 4)*B22) |
                     ((static_cast<int32_t>(dd) & 0xf)*B12) |
                     B11 | B9 | B8 | ad.vencoding();
  Emit(encoding);
}

void Assembler::EmitMultiVSMemOp(Condition cond,
                                BlockAddressMode am,
                                bool load,
                                Register base,
                                SRegister start,
                                uint32_t count) {
  ASSERT(TargetCPUFeatures::vfp_supported());
  ASSERT(base != kNoRegister);
  ASSERT(cond != kNoCondition);
  ASSERT(start != kNoSRegister);
  ASSERT(static_cast<int32_t>(start) + count <= kNumberOfSRegisters);

  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B27 | B26 | B11 | B9 |
                     am |
                     (load ? L : 0) |
                     (static_cast<int32_t>(base) << kRnShift) |
                     ((static_cast<int32_t>(start) & 0x1) ? D : 0) |
                     ((static_cast<int32_t>(start) >> 1) << 12) |
                     count;
  Emit(encoding);
}


void Assembler::EmitMultiVDMemOp(Condition cond,
                                BlockAddressMode am,
                                bool load,
                                Register base,
                                DRegister start,
                                int32_t count) {
  ASSERT(TargetCPUFeatures::vfp_supported());
  ASSERT(base != kNoRegister);
  ASSERT(cond != kNoCondition);
  ASSERT(start != kNoDRegister);
  ASSERT(static_cast<int32_t>(start) + count <= kNumberOfDRegisters);
  const int armv5te = TargetCPUFeatures::arm_version() == ARMv5TE ? 1 : 0;

  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B27 | B26 | B11 | B9 | B8 |
                     am |
                     (load ? L : 0) |
                     (static_cast<int32_t>(base) << kRnShift) |
                     ((static_cast<int32_t>(start) & 0x10) ? D : 0) |
                     ((static_cast<int32_t>(start) & 0xf) << 12) |
                     (count << 1) | armv5te;
  Emit(encoding);
}


void Assembler::vldms(BlockAddressMode am, Register base,
                      SRegister first, SRegister last, Condition cond) {
  ASSERT((am == IA) || (am == IA_W) || (am == DB_W));
  ASSERT(last > first);
  EmitMultiVSMemOp(cond, am, true, base, first, last - first + 1);
}


void Assembler::vstms(BlockAddressMode am, Register base,
                      SRegister first, SRegister last, Condition cond) {
  ASSERT((am == IA) || (am == IA_W) || (am == DB_W));
  ASSERT(last > first);
  EmitMultiVSMemOp(cond, am, false, base, first, last - first + 1);
}


void Assembler::vldmd(BlockAddressMode am, Register base,
                      DRegister first, intptr_t count, Condition cond) {
  ASSERT((am == IA) || (am == IA_W) || (am == DB_W));
  ASSERT(count <= 16);
  ASSERT(first + count <= kNumberOfDRegisters);
  EmitMultiVDMemOp(cond, am, true, base, first, count);
}


void Assembler::vstmd(BlockAddressMode am, Register base,
                      DRegister first, intptr_t count, Condition cond) {
  ASSERT((am == IA) || (am == IA_W) || (am == DB_W));
  ASSERT(count <= 16);
  ASSERT(first + count <= kNumberOfDRegisters);
  EmitMultiVDMemOp(cond, am, false, base, first, count);
}


void Assembler::EmitVFPsss(Condition cond, int32_t opcode,
                           SRegister sd, SRegister sn, SRegister sm) {
  ASSERT(TargetCPUFeatures::vfp_supported());
  ASSERT(sd != kNoSRegister);
  ASSERT(sn != kNoSRegister);
  ASSERT(sm != kNoSRegister);
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B27 | B26 | B25 | B11 | B9 | opcode |
                     ((static_cast<int32_t>(sd) & 1)*B22) |
                     ((static_cast<int32_t>(sn) >> 1)*B16) |
                     ((static_cast<int32_t>(sd) >> 1)*B12) |
                     ((static_cast<int32_t>(sn) & 1)*B7) |
                     ((static_cast<int32_t>(sm) & 1)*B5) |
                     (static_cast<int32_t>(sm) >> 1);
  Emit(encoding);
}


void Assembler::EmitVFPddd(Condition cond, int32_t opcode,
                           DRegister dd, DRegister dn, DRegister dm) {
  ASSERT(TargetCPUFeatures::vfp_supported());
  ASSERT(dd != kNoDRegister);
  ASSERT(dn != kNoDRegister);
  ASSERT(dm != kNoDRegister);
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B27 | B26 | B25 | B11 | B9 | B8 | opcode |
                     ((static_cast<int32_t>(dd) >> 4)*B22) |
                     ((static_cast<int32_t>(dn) & 0xf)*B16) |
                     ((static_cast<int32_t>(dd) & 0xf)*B12) |
                     ((static_cast<int32_t>(dn) >> 4)*B7) |
                     ((static_cast<int32_t>(dm) >> 4)*B5) |
                     (static_cast<int32_t>(dm) & 0xf);
  Emit(encoding);
}


void Assembler::vmovs(SRegister sd, SRegister sm, Condition cond) {
  EmitVFPsss(cond, B23 | B21 | B20 | B6, sd, S0, sm);
}


void Assembler::vmovd(DRegister dd, DRegister dm, Condition cond) {
  EmitVFPddd(cond, B23 | B21 | B20 | B6, dd, D0, dm);
}


bool Assembler::vmovs(SRegister sd, float s_imm, Condition cond) {
  if (TargetCPUFeatures::arm_version() != ARMv7) {
    return false;
  }
  uint32_t imm32 = bit_cast<uint32_t, float>(s_imm);
  if (((imm32 & ((1 << 19) - 1)) == 0) &&
      ((((imm32 >> 25) & ((1 << 6) - 1)) == (1 << 5)) ||
       (((imm32 >> 25) & ((1 << 6) - 1)) == ((1 << 5) -1)))) {
    uint8_t imm8 = ((imm32 >> 31) << 7) | (((imm32 >> 29) & 1) << 6) |
        ((imm32 >> 19) & ((1 << 6) -1));
    EmitVFPsss(cond, B23 | B21 | B20 | ((imm8 >> 4)*B16) | (imm8 & 0xf),
               sd, S0, S0);
    return true;
  }
  return false;
}


bool Assembler::vmovd(DRegister dd, double d_imm, Condition cond) {
  if (TargetCPUFeatures::arm_version() != ARMv7) {
    return false;
  }
  uint64_t imm64 = bit_cast<uint64_t, double>(d_imm);
  if (((imm64 & ((1LL << 48) - 1)) == 0) &&
      ((((imm64 >> 54) & ((1 << 9) - 1)) == (1 << 8)) ||
       (((imm64 >> 54) & ((1 << 9) - 1)) == ((1 << 8) -1)))) {
    uint8_t imm8 = ((imm64 >> 63) << 7) | (((imm64 >> 61) & 1) << 6) |
        ((imm64 >> 48) & ((1 << 6) -1));
    EmitVFPddd(cond, B23 | B21 | B20 | ((imm8 >> 4)*B16) | B8 | (imm8 & 0xf),
               dd, D0, D0);
    return true;
  }
  return false;
}


void Assembler::vadds(SRegister sd, SRegister sn, SRegister sm,
                      Condition cond) {
  EmitVFPsss(cond, B21 | B20, sd, sn, sm);
}


void Assembler::vaddd(DRegister dd, DRegister dn, DRegister dm,
                      Condition cond) {
  EmitVFPddd(cond, B21 | B20, dd, dn, dm);
}


void Assembler::vsubs(SRegister sd, SRegister sn, SRegister sm,
                      Condition cond) {
  EmitVFPsss(cond, B21 | B20 | B6, sd, sn, sm);
}


void Assembler::vsubd(DRegister dd, DRegister dn, DRegister dm,
                      Condition cond) {
  EmitVFPddd(cond, B21 | B20 | B6, dd, dn, dm);
}


void Assembler::vmuls(SRegister sd, SRegister sn, SRegister sm,
                      Condition cond) {
  EmitVFPsss(cond, B21, sd, sn, sm);
}


void Assembler::vmuld(DRegister dd, DRegister dn, DRegister dm,
                      Condition cond) {
  EmitVFPddd(cond, B21, dd, dn, dm);
}


void Assembler::vmlas(SRegister sd, SRegister sn, SRegister sm,
                      Condition cond) {
  EmitVFPsss(cond, 0, sd, sn, sm);
}


void Assembler::vmlad(DRegister dd, DRegister dn, DRegister dm,
                      Condition cond) {
  EmitVFPddd(cond, 0, dd, dn, dm);
}


void Assembler::vmlss(SRegister sd, SRegister sn, SRegister sm,
                      Condition cond) {
  EmitVFPsss(cond, B6, sd, sn, sm);
}


void Assembler::vmlsd(DRegister dd, DRegister dn, DRegister dm,
                      Condition cond) {
  EmitVFPddd(cond, B6, dd, dn, dm);
}


void Assembler::vdivs(SRegister sd, SRegister sn, SRegister sm,
                      Condition cond) {
  EmitVFPsss(cond, B23, sd, sn, sm);
}


void Assembler::vdivd(DRegister dd, DRegister dn, DRegister dm,
                      Condition cond) {
  EmitVFPddd(cond, B23, dd, dn, dm);
}


void Assembler::vabss(SRegister sd, SRegister sm, Condition cond) {
  EmitVFPsss(cond, B23 | B21 | B20 | B7 | B6, sd, S0, sm);
}


void Assembler::vabsd(DRegister dd, DRegister dm, Condition cond) {
  EmitVFPddd(cond, B23 | B21 | B20 | B7 | B6, dd, D0, dm);
}


void Assembler::vnegs(SRegister sd, SRegister sm, Condition cond) {
  EmitVFPsss(cond, B23 | B21 | B20 | B16 | B6, sd, S0, sm);
}


void Assembler::vnegd(DRegister dd, DRegister dm, Condition cond) {
  EmitVFPddd(cond, B23 | B21 | B20 | B16 | B6, dd, D0, dm);
}


void Assembler::vsqrts(SRegister sd, SRegister sm, Condition cond) {
  EmitVFPsss(cond, B23 | B21 | B20 | B16 | B7 | B6, sd, S0, sm);
}

void Assembler::vsqrtd(DRegister dd, DRegister dm, Condition cond) {
  EmitVFPddd(cond, B23 | B21 | B20 | B16 | B7 | B6, dd, D0, dm);
}


void Assembler::EmitVFPsd(Condition cond, int32_t opcode,
                          SRegister sd, DRegister dm) {
  ASSERT(TargetCPUFeatures::vfp_supported());
  ASSERT(sd != kNoSRegister);
  ASSERT(dm != kNoDRegister);
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B27 | B26 | B25 | B11 | B9 | opcode |
                     ((static_cast<int32_t>(sd) & 1)*B22) |
                     ((static_cast<int32_t>(sd) >> 1)*B12) |
                     ((static_cast<int32_t>(dm) >> 4)*B5) |
                     (static_cast<int32_t>(dm) & 0xf);
  Emit(encoding);
}


void Assembler::EmitVFPds(Condition cond, int32_t opcode,
                          DRegister dd, SRegister sm) {
  ASSERT(TargetCPUFeatures::vfp_supported());
  ASSERT(dd != kNoDRegister);
  ASSERT(sm != kNoSRegister);
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B27 | B26 | B25 | B11 | B9 | opcode |
                     ((static_cast<int32_t>(dd) >> 4)*B22) |
                     ((static_cast<int32_t>(dd) & 0xf)*B12) |
                     ((static_cast<int32_t>(sm) & 1)*B5) |
                     (static_cast<int32_t>(sm) >> 1);
  Emit(encoding);
}


void Assembler::vcvtsd(SRegister sd, DRegister dm, Condition cond) {
  EmitVFPsd(cond, B23 | B21 | B20 | B18 | B17 | B16 | B8 | B7 | B6, sd, dm);
}


void Assembler::vcvtds(DRegister dd, SRegister sm, Condition cond) {
  EmitVFPds(cond, B23 | B21 | B20 | B18 | B17 | B16 | B7 | B6, dd, sm);
}


void Assembler::vcvtis(SRegister sd, SRegister sm, Condition cond) {
  EmitVFPsss(cond, B23 | B21 | B20 | B19 | B18 | B16 | B7 | B6, sd, S0, sm);
}


void Assembler::vcvtid(SRegister sd, DRegister dm, Condition cond) {
  EmitVFPsd(cond, B23 | B21 | B20 | B19 | B18 | B16 | B8 | B7 | B6, sd, dm);
}


void Assembler::vcvtsi(SRegister sd, SRegister sm, Condition cond) {
  EmitVFPsss(cond, B23 | B21 | B20 | B19 | B7 | B6, sd, S0, sm);
}


void Assembler::vcvtdi(DRegister dd, SRegister sm, Condition cond) {
  EmitVFPds(cond, B23 | B21 | B20 | B19 | B8 | B7 | B6, dd, sm);
}


void Assembler::vcvtus(SRegister sd, SRegister sm, Condition cond) {
  EmitVFPsss(cond, B23 | B21 | B20 | B19 | B18 | B7 | B6, sd, S0, sm);
}


void Assembler::vcvtud(SRegister sd, DRegister dm, Condition cond) {
  EmitVFPsd(cond, B23 | B21 | B20 | B19 | B18 | B8 | B7 | B6, sd, dm);
}


void Assembler::vcvtsu(SRegister sd, SRegister sm, Condition cond) {
  EmitVFPsss(cond, B23 | B21 | B20 | B19 | B6, sd, S0, sm);
}


void Assembler::vcvtdu(DRegister dd, SRegister sm, Condition cond) {
  EmitVFPds(cond, B23 | B21 | B20 | B19 | B8 | B6, dd, sm);
}


void Assembler::vcmps(SRegister sd, SRegister sm, Condition cond) {
  EmitVFPsss(cond, B23 | B21 | B20 | B18 | B6, sd, S0, sm);
}


void Assembler::vcmpd(DRegister dd, DRegister dm, Condition cond) {
  EmitVFPddd(cond, B23 | B21 | B20 | B18 | B6, dd, D0, dm);
}


void Assembler::vcmpsz(SRegister sd, Condition cond) {
  EmitVFPsss(cond, B23 | B21 | B20 | B18 | B16 | B6, sd, S0, S0);
}


void Assembler::vcmpdz(DRegister dd, Condition cond) {
  EmitVFPddd(cond, B23 | B21 | B20 | B18 | B16 | B6, dd, D0, D0);
}


void Assembler::vmstat(Condition cond) {  // VMRS APSR_nzcv, FPSCR
  ASSERT(TargetCPUFeatures::vfp_supported());
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B27 | B26 | B25 | B23 | B22 | B21 | B20 | B16 |
                     (static_cast<int32_t>(PC)*B12) |
                     B11 | B9 | B4;
  Emit(encoding);
}


static inline int ShiftOfOperandSize(OperandSize size) {
  switch (size) {
    case kByte:
    case kUnsignedByte:
      return 0;
    case kHalfword:
    case kUnsignedHalfword:
      return 1;
    case kWord:
    case kUnsignedWord:
      return 2;
    case kWordPair:
      return 3;
    case kSWord:
    case kDWord:
      return 0;
    default:
      UNREACHABLE();
      break;
  }

  UNREACHABLE();
  return -1;
}


void Assembler::EmitSIMDqqq(int32_t opcode, OperandSize size,
                            QRegister qd, QRegister qn, QRegister qm) {
  ASSERT(TargetCPUFeatures::neon_supported());
  int sz = ShiftOfOperandSize(size);
  int32_t encoding =
      (static_cast<int32_t>(kSpecialCondition) << kConditionShift) |
      B25 | B6 |
      opcode | ((sz & 0x3) * B20) |
      ((static_cast<int32_t>(qd * 2) >> 4)*B22) |
      ((static_cast<int32_t>(qn * 2) & 0xf)*B16) |
      ((static_cast<int32_t>(qd * 2) & 0xf)*B12) |
      ((static_cast<int32_t>(qn * 2) >> 4)*B7) |
      ((static_cast<int32_t>(qm * 2) >> 4)*B5) |
      (static_cast<int32_t>(qm * 2) & 0xf);
  Emit(encoding);
}


void Assembler::EmitSIMDddd(int32_t opcode, OperandSize size,
                            DRegister dd, DRegister dn, DRegister dm) {
  ASSERT(TargetCPUFeatures::neon_supported());
  int sz = ShiftOfOperandSize(size);
  int32_t encoding =
      (static_cast<int32_t>(kSpecialCondition) << kConditionShift) |
      B25 |
      opcode | ((sz & 0x3) * B20) |
      ((static_cast<int32_t>(dd) >> 4)*B22) |
      ((static_cast<int32_t>(dn) & 0xf)*B16) |
      ((static_cast<int32_t>(dd) & 0xf)*B12) |
      ((static_cast<int32_t>(dn) >> 4)*B7) |
      ((static_cast<int32_t>(dm) >> 4)*B5) |
      (static_cast<int32_t>(dm) & 0xf);
  Emit(encoding);
}


void Assembler::vmovq(QRegister qd, QRegister qm) {
  EmitSIMDqqq(B21 | B8 | B4, kByte, qd, qm, qm);
}


void Assembler::vaddqi(OperandSize sz,
                       QRegister qd, QRegister qn, QRegister qm) {
  EmitSIMDqqq(B11, sz, qd, qn, qm);
}


void Assembler::vaddqs(QRegister qd, QRegister qn, QRegister qm) {
  EmitSIMDqqq(B11 | B10 | B8, kSWord, qd, qn, qm);
}


void Assembler::vsubqi(OperandSize sz,
                       QRegister qd, QRegister qn, QRegister qm) {
  EmitSIMDqqq(B24 | B11, sz, qd, qn, qm);
}


void Assembler::vsubqs(QRegister qd, QRegister qn, QRegister qm) {
  EmitSIMDqqq(B21 | B11 | B10 | B8, kSWord, qd, qn, qm);
}


void Assembler::vmulqi(OperandSize sz,
                       QRegister qd, QRegister qn, QRegister qm) {
  EmitSIMDqqq(B11 | B8 | B4, sz, qd, qn, qm);
}


void Assembler::vmulqs(QRegister qd, QRegister qn, QRegister qm) {
  EmitSIMDqqq(B24 | B11 | B10 | B8 | B4, kSWord, qd, qn, qm);
}


void Assembler::vshlqi(OperandSize sz,
                       QRegister qd, QRegister qm, QRegister qn) {
  EmitSIMDqqq(B25 | B10, sz, qd, qn, qm);
}


void Assembler::vshlqu(OperandSize sz,
                       QRegister qd, QRegister qm, QRegister qn) {
  EmitSIMDqqq(B25 | B24 | B10, sz, qd, qn, qm);
}


void Assembler::veorq(QRegister qd, QRegister qn, QRegister qm) {
  EmitSIMDqqq(B24 | B8 | B4, kByte, qd, qn, qm);
}


void Assembler::vorrq(QRegister qd, QRegister qn, QRegister qm) {
  EmitSIMDqqq(B21 | B8 | B4, kByte, qd, qn, qm);
}


void Assembler::vornq(QRegister qd, QRegister qn, QRegister qm) {
  EmitSIMDqqq(B21 | B20 | B8 | B4, kByte, qd, qn, qm);
}


void Assembler::vandq(QRegister qd, QRegister qn, QRegister qm) {
  EmitSIMDqqq(B8 | B4, kByte, qd, qn, qm);
}


void Assembler::vmvnq(QRegister qd, QRegister qm) {
  EmitSIMDqqq(B25 | B24 | B23 | B10 | B8 | B7, kWordPair, qd, Q0, qm);
}


void Assembler::vminqs(QRegister qd, QRegister qn, QRegister qm) {
  EmitSIMDqqq(B21 | B11 | B10 | B9 | B8, kSWord, qd, qn, qm);
}


void Assembler::vmaxqs(QRegister qd, QRegister qn, QRegister qm) {
  EmitSIMDqqq(B11 | B10 | B9 | B8, kSWord, qd, qn, qm);
}


void Assembler::vabsqs(QRegister qd, QRegister qm) {
  EmitSIMDqqq(B24 | B23 | B21 | B20 | B19 | B16 | B10 | B9 | B8, kSWord,
              qd, Q0, qm);
}


void Assembler::vnegqs(QRegister qd, QRegister qm) {
  EmitSIMDqqq(B24 | B23 | B21 | B20 | B19 | B16 | B10 | B9 | B8 | B7, kSWord,
              qd, Q0, qm);
}


void Assembler::vrecpeqs(QRegister qd, QRegister qm) {
  EmitSIMDqqq(B24 | B23 | B21 | B20 | B19 | B17 | B16 | B10 | B8, kSWord,
              qd, Q0, qm);
}


void Assembler::vrecpsqs(QRegister qd, QRegister qn, QRegister qm) {
  EmitSIMDqqq(B11 | B10 | B9 | B8 | B4, kSWord, qd, qn, qm);
}


void Assembler::vrsqrteqs(QRegister qd, QRegister qm) {
  EmitSIMDqqq(B24 | B23 | B21 | B20 | B19 | B17 | B16 | B10 | B8 | B7,
              kSWord, qd, Q0, qm);
}


void Assembler::vrsqrtsqs(QRegister qd, QRegister qn, QRegister qm) {
  EmitSIMDqqq(B21 | B11 | B10 | B9 | B8 | B4, kSWord, qd, qn, qm);
}


void Assembler::vdup(OperandSize sz, QRegister qd, DRegister dm, int idx) {
  ASSERT((sz != kDWord) && (sz != kSWord) && (sz != kWordPair));
  int code = 0;

  switch (sz) {
    case kByte:
    case kUnsignedByte: {
      ASSERT((idx >= 0) && (idx < 8));
      code = 1 | (idx << 1);
      break;
    }
    case kHalfword:
    case kUnsignedHalfword: {
      ASSERT((idx >= 0) && (idx < 4));
      code = 2 | (idx << 2);
      break;
    }
    case kWord:
    case kUnsignedWord: {
      ASSERT((idx >= 0) && (idx < 2));
      code = 4 | (idx << 3);
      break;
    }
    default: {
      break;
    }
  }

  EmitSIMDddd(B24 | B23 | B11 | B10 | B6, kWordPair,
              static_cast<DRegister>(qd * 2),
              static_cast<DRegister>(code & 0xf),
              dm);
}


void Assembler::vtbl(DRegister dd, DRegister dn, int len, DRegister dm) {
  ASSERT((len >= 1) && (len <= 4));
  EmitSIMDddd(B24 | B23 | B11 | ((len - 1) * B8), kWordPair, dd, dn, dm);
}


void Assembler::vzipqw(QRegister qd, QRegister qm) {
  EmitSIMDqqq(B24 | B23 | B21 | B20 | B19 | B17 | B8 | B7, kByte, qd, Q0, qm);
}


void Assembler::vceqqi(OperandSize sz,
                      QRegister qd, QRegister qn, QRegister qm) {
  EmitSIMDqqq(B24 | B11 | B4, sz, qd, qn, qm);
}


void Assembler::vceqqs(QRegister qd, QRegister qn, QRegister qm) {
  EmitSIMDqqq(B11 | B10 | B9, kSWord, qd, qn, qm);
}


void Assembler::vcgeqi(OperandSize sz,
                      QRegister qd, QRegister qn, QRegister qm) {
  EmitSIMDqqq(B9 | B8 | B4, sz, qd, qn, qm);
}


void Assembler::vcugeqi(OperandSize sz,
                      QRegister qd, QRegister qn, QRegister qm) {
  EmitSIMDqqq(B24 | B9 | B8 | B4, sz, qd, qn, qm);
}


void Assembler::vcgeqs(QRegister qd, QRegister qn, QRegister qm) {
  EmitSIMDqqq(B24 | B11 | B10 | B9, kSWord, qd, qn, qm);
}


void Assembler::vcgtqi(OperandSize sz,
                      QRegister qd, QRegister qn, QRegister qm) {
  EmitSIMDqqq(B9 | B8, sz, qd, qn, qm);
}


void Assembler::vcugtqi(OperandSize sz,
                      QRegister qd, QRegister qn, QRegister qm) {
  EmitSIMDqqq(B24 | B9 | B8, sz, qd, qn, qm);
}


void Assembler::vcgtqs(QRegister qd, QRegister qn, QRegister qm) {
  EmitSIMDqqq(B24 | B21 | B11 | B10 | B9, kSWord, qd, qn, qm);
}


void Assembler::svc(uint32_t imm24, Condition cond) {
  ASSERT(cond != kNoCondition);
  ASSERT(imm24 < (1 << 24));
  int32_t encoding = (cond << kConditionShift) | B27 | B26 | B25 | B24 | imm24;
  Emit(encoding);
}


void Assembler::bkpt(uint16_t imm16) {
  // bkpt requires that the cond field is AL.
  int32_t encoding = (AL << kConditionShift) | B24 | B21 |
                     ((imm16 >> 4) << 8) | B6 | B5 | B4 | (imm16 & 0xf);
  Emit(encoding);
}


void Assembler::b(Label* label, Condition cond) {
  EmitBranch(cond, label, false);
}


void Assembler::bl(Label* label, Condition cond) {
  EmitBranch(cond, label, true);
}


void Assembler::bx(Register rm, Condition cond) {
  ASSERT(rm != kNoRegister);
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B24 | B21 | (0xfff << 8) | B4 |
                     (static_cast<int32_t>(rm) << kRmShift);
  Emit(encoding);
}


void Assembler::blx(Register rm, Condition cond) {
  ASSERT(rm != kNoRegister);
  ASSERT(cond != kNoCondition);
  int32_t encoding = (static_cast<int32_t>(cond) << kConditionShift) |
                     B24 | B21 | (0xfff << 8) | B5 | B4 |
                     (static_cast<int32_t>(rm) << kRmShift);
  Emit(encoding);
}


void Assembler::MarkExceptionHandler(Label* label) {
  EmitType01(AL, 1, TST, 1, PC, R0, Operand(0));
  Label l;
  b(&l);
  EmitBranch(AL, label, false);
  Bind(&l);
}


void Assembler::Drop(intptr_t stack_elements) {
  ASSERT(stack_elements >= 0);
  if (stack_elements > 0) {
    AddImmediate(SP, SP, stack_elements * kWordSize);
  }
}


// Uses a code sequence that can easily be decoded.
void Assembler::LoadWordFromPoolOffset(Register rd,
                                       int32_t offset,
                                       Condition cond) {
  ASSERT(rd != PP);
  int32_t offset_mask = 0;
  if (Address::CanHoldLoadOffset(kWord, offset, &offset_mask)) {
    ldr(rd, Address(PP, offset), cond);
  } else {
    int32_t offset_hi = offset & ~offset_mask;  // signed
    uint32_t offset_lo = offset & offset_mask;  // unsigned
    // Inline a simplified version of AddImmediate(rd, PP, offset_hi).
    Operand o;
    if (Operand::CanHold(offset_hi, &o)) {
      add(rd, PP, o, cond);
    } else {
      LoadImmediate(rd, offset_hi, cond);
      add(rd, PP, Operand(LR), cond);
    }
    ldr(rd, Address(rd, offset_lo), cond);
  }
}


void Assembler::LoadPoolPointer() {
  const intptr_t object_pool_pc_dist =
     Instructions::HeaderSize() - Instructions::object_pool_offset() +
     CodeSize() + Instr::kPCReadOffset;
  LoadFromOffset(kWord, PP, PC, -object_pool_pc_dist);
}


void Assembler::LoadObject(Register rd, const Object& object, Condition cond) {
  // Smis and VM heap objects are never relocated; do not use object pool.
  if (object.IsSmi()) {
    LoadImmediate(rd, reinterpret_cast<int32_t>(object.raw()), cond);
  } else if (object.InVMHeap()) {
    // Make sure that class CallPattern is able to decode this load immediate.
    const int32_t object_raw = reinterpret_cast<int32_t>(object.raw());
    LoadImmediate(rd, object_raw, cond);
  } else {
    // Make sure that class CallPattern is able to decode this load from the
    // object pool.
    const int32_t offset =
        Array::data_offset() + 4*AddObject(object) - kHeapObjectTag;
    LoadWordFromPoolOffset(rd, offset, cond);
  }
}


void Assembler::PushObject(const Object& object) {
  LoadObject(IP, object);
  Push(IP);
}


void Assembler::CompareObject(Register rn, const Object& object) {
  ASSERT(rn != IP);
  if (object.IsSmi()) {
    CompareImmediate(rn, reinterpret_cast<int32_t>(object.raw()));
  } else {
    LoadObject(IP, object);
    cmp(rn, Operand(IP));
  }
}


// Preserves object and value registers.
void Assembler::StoreIntoObjectFilterNoSmi(Register object,
                                           Register value,
                                           Label* no_update) {
  COMPILE_ASSERT((kNewObjectAlignmentOffset == kWordSize) &&
                 (kOldObjectAlignmentOffset == 0));

  // Write-barrier triggers if the value is in the new space (has bit set) and
  // the object is in the old space (has bit cleared).
  // To check that, we compute value & ~object and skip the write barrier
  // if the bit is not set. We can't destroy the object.
  bic(IP, value, Operand(object));
  tst(IP, Operand(kNewObjectAlignmentOffset));
  b(no_update, EQ);
}


// Preserves object and value registers.
void Assembler::StoreIntoObjectFilter(Register object,
                                      Register value,
                                      Label* no_update) {
  // For the value we are only interested in the new/old bit and the tag bit.
  // And the new bit with the tag bit. The resulting bit will be 0 for a Smi.
  and_(IP, value, Operand(value, LSL, kObjectAlignmentLog2 - 1));
  // And the result with the negated space bit of the object.
  bic(IP, IP, Operand(object));
  tst(IP, Operand(kNewObjectAlignmentOffset));
  b(no_update, EQ);
}


void Assembler::StoreIntoObject(Register object,
                                const Address& dest,
                                Register value,
                                bool can_value_be_smi) {
  ASSERT(object != value);
  str(value, dest);
  Label done;
  if (can_value_be_smi) {
    StoreIntoObjectFilter(object, value, &done);
  } else {
    StoreIntoObjectFilterNoSmi(object, value, &done);
  }
  // A store buffer update is required.
  RegList regs = (1 << LR);
  if (value != R0) {
    regs |= (1 << R0);  // Preserve R0.
  }
  PushList(regs);
  if (object != R0) {
    mov(R0, Operand(object));
  }
  StubCode* stub_code = Isolate::Current()->stub_code();
  BranchLink(&stub_code->UpdateStoreBufferLabel());
  PopList(regs);
  Bind(&done);
}


void Assembler::StoreIntoObjectOffset(Register object,
                                      int32_t offset,
                                      Register value,
                                      bool can_value_be_smi) {
  int32_t ignored = 0;
  if (Address::CanHoldStoreOffset(kWord, offset - kHeapObjectTag, &ignored)) {
    StoreIntoObject(
        object, FieldAddress(object, offset), value, can_value_be_smi);
  } else {
    AddImmediate(IP, object, offset - kHeapObjectTag);
    StoreIntoObject(object, Address(IP), value, can_value_be_smi);
  }
}


void Assembler::StoreIntoObjectNoBarrier(Register object,
                                         const Address& dest,
                                         Register value) {
  str(value, dest);
#if defined(DEBUG)
  Label done;
  StoreIntoObjectFilter(object, value, &done);
  Stop("Store buffer update is required");
  Bind(&done);
#endif  // defined(DEBUG)
  // No store buffer update.
}


void Assembler::StoreIntoObjectNoBarrierOffset(Register object,
                                               int32_t offset,
                                               Register value) {
  int32_t ignored = 0;
  if (Address::CanHoldStoreOffset(kWord, offset - kHeapObjectTag, &ignored)) {
    StoreIntoObjectNoBarrier(object, FieldAddress(object, offset), value);
  } else {
    AddImmediate(IP, object, offset - kHeapObjectTag);
    StoreIntoObjectNoBarrier(object, Address(IP), value);
  }
}


void Assembler::StoreIntoObjectNoBarrier(Register object,
                                         const Address& dest,
                                         const Object& value) {
  ASSERT(value.IsSmi() || value.InVMHeap() ||
         (value.IsOld() && value.IsNotTemporaryScopedHandle()));
  // No store buffer update.
  LoadObject(IP, value);
  str(IP, dest);
}


void Assembler::StoreIntoObjectNoBarrierOffset(Register object,
                                               int32_t offset,
                                               const Object& value) {
  int32_t ignored = 0;
  if (Address::CanHoldStoreOffset(kWord, offset - kHeapObjectTag, &ignored)) {
    StoreIntoObjectNoBarrier(object, FieldAddress(object, offset), value);
  } else {
    AddImmediate(IP, object, offset - kHeapObjectTag);
    StoreIntoObjectNoBarrier(object, Address(IP), value);
  }
}


void Assembler::LoadClassId(Register result, Register object, Condition cond) {
  ASSERT(RawObject::kClassIdTagPos == 16);
  ASSERT(RawObject::kClassIdTagSize == 16);
  const intptr_t class_id_offset = Object::tags_offset() +
      RawObject::kClassIdTagPos / kBitsPerByte;
  ldrh(result, FieldAddress(object, class_id_offset), cond);
}


void Assembler::LoadClassById(Register result, Register class_id) {
  ASSERT(result != class_id);
  ldr(result, FieldAddress(CTX, Context::isolate_offset()));
  const intptr_t table_offset_in_isolate =
      Isolate::class_table_offset() + ClassTable::table_offset();
  LoadFromOffset(kWord, result, result, table_offset_in_isolate);
  ldr(result, Address(result, class_id, LSL, 2));
}


void Assembler::LoadClass(Register result, Register object, Register scratch) {
  ASSERT(scratch != result);
  LoadClassId(scratch, object);

  ldr(result, FieldAddress(CTX, Context::isolate_offset()));
  const intptr_t table_offset_in_isolate =
      Isolate::class_table_offset() + ClassTable::table_offset();
  LoadFromOffset(kWord, result, result, table_offset_in_isolate);
  ldr(result, Address(result, scratch, LSL, 2));
}


void Assembler::CompareClassId(Register object,
                               intptr_t class_id,
                               Register scratch) {
  LoadClassId(scratch, object);
  CompareImmediate(scratch, class_id);
}


void Assembler::LoadTaggedClassIdMayBeSmi(Register result, Register object) {
  tst(object, Operand(kSmiTagMask));
  LoadImmediate(result, Smi::RawValue(kSmiCid), EQ);
  LoadClassId(result, object, NE);
  SmiTag(result, NE);
}


static bool CanEncodeBranchOffset(int32_t offset) {
  ASSERT(Utils::IsAligned(offset, 4));
  return Utils::IsInt(Utils::CountOneBits(kBranchOffsetMask), offset);
}


int32_t Assembler::EncodeBranchOffset(int32_t offset, int32_t inst) {
  // The offset is off by 8 due to the way the ARM CPUs read PC.
  offset -= Instr::kPCReadOffset;

  if (!CanEncodeBranchOffset(offset)) {
    ASSERT(!use_far_branches());
    Isolate::Current()->long_jump_base()->Jump(
        1, Object::branch_offset_error());
  }

  // Properly preserve only the bits supported in the instruction.
  offset >>= 2;
  offset &= kBranchOffsetMask;
  return (inst & ~kBranchOffsetMask) | offset;
}


int Assembler::DecodeBranchOffset(int32_t inst) {
  // Sign-extend, left-shift by 2, then add 8.
  return ((((inst & kBranchOffsetMask) << 8) >> 6) + Instr::kPCReadOffset);
}


static int32_t DecodeARMv7LoadImmediate(int32_t movt, int32_t movw) {
  int32_t offset = 0;
  offset |= (movt & 0xf0000) << 12;
  offset |= (movt & 0xfff) << 16;
  offset |= (movw & 0xf0000) >> 4;
  offset |= movw & 0xfff;
  return offset;
}


static int32_t DecodeARMv6LoadImmediate(int32_t mov, int32_t or1,
                                        int32_t or2, int32_t or3) {
  int32_t offset = 0;
  offset |= (mov & 0xff) << 24;
  offset |= (or1 & 0xff) << 16;
  offset |= (or2 & 0xff) << 8;
  offset |= (or3 & 0xff);
  return offset;
}


class PatchFarBranch : public AssemblerFixup {
 public:
  PatchFarBranch() {}

  void Process(const MemoryRegion& region, intptr_t position) {
    const ARMVersion version = TargetCPUFeatures::arm_version();
    if ((version == ARMv5TE) || (version == ARMv6)) {
      ProcessARMv6(region, position);
    } else {
      ASSERT(version == ARMv7);
      ProcessARMv7(region, position);
    }
  }

 private:
  void ProcessARMv6(const MemoryRegion& region, intptr_t position) {
    const int32_t mov = region.Load<int32_t>(position);
    const int32_t or1 = region.Load<int32_t>(position + 1*Instr::kInstrSize);
    const int32_t or2 = region.Load<int32_t>(position + 2*Instr::kInstrSize);
    const int32_t or3 = region.Load<int32_t>(position + 3*Instr::kInstrSize);
    const int32_t bx = region.Load<int32_t>(position + 4*Instr::kInstrSize);

    if (((mov & 0xffffff00) == 0xe3a0c400) &&  // mov IP, (byte3 rot 4)
        ((or1 & 0xffffff00) == 0xe38cc800) &&  // orr IP, IP, (byte2 rot 8)
        ((or2 & 0xffffff00) == 0xe38ccc00) &&  // orr IP, IP, (byte1 rot 12)
        ((or3 & 0xffffff00) == 0xe38cc000)) {  // orr IP, IP, byte0
      const int32_t offset = DecodeARMv6LoadImmediate(mov, or1, or2, or3);
      const int32_t dest = region.start() + offset;
      const int32_t dest0 = (dest & 0x000000ff);
      const int32_t dest1 = (dest & 0x0000ff00) >> 8;
      const int32_t dest2 = (dest & 0x00ff0000) >> 16;
      const int32_t dest3 = (dest & 0xff000000) >> 24;
      const int32_t patched_mov = 0xe3a0c400 | dest3;
      const int32_t patched_or1 = 0xe38cc800 | dest2;
      const int32_t patched_or2 = 0xe38ccc00 | dest1;
      const int32_t patched_or3 = 0xe38cc000 | dest0;

      region.Store<int32_t>(position + 0 * Instr::kInstrSize, patched_mov);
      region.Store<int32_t>(position + 1 * Instr::kInstrSize, patched_or1);
      region.Store<int32_t>(position + 2 * Instr::kInstrSize, patched_or2);
      region.Store<int32_t>(position + 3 * Instr::kInstrSize, patched_or3);
      return;
    }

    // If the offset loading instructions aren't there, we must have replaced
    // the far branch with a near one, and so these instructions
    // should be NOPs.
    ASSERT((or1 == Instr::kNopInstruction) &&
           (or2 == Instr::kNopInstruction) &&
           (or3 == Instr::kNopInstruction) &&
           (bx == Instr::kNopInstruction));
  }


  void ProcessARMv7(const MemoryRegion& region, intptr_t position) {
    const int32_t movw = region.Load<int32_t>(position);
    const int32_t movt = region.Load<int32_t>(position + Instr::kInstrSize);
    const int32_t bx = region.Load<int32_t>(position + 2 * Instr::kInstrSize);

    if (((movt & 0xfff0f000) == 0xe340c000) &&  // movt IP, high
        ((movw & 0xfff0f000) == 0xe300c000)) {   // movw IP, low
      const int32_t offset = DecodeARMv7LoadImmediate(movt, movw);
      const int32_t dest = region.start() + offset;
      const uint16_t dest_high = Utils::High16Bits(dest);
      const uint16_t dest_low = Utils::Low16Bits(dest);
      const int32_t patched_movt =
          0xe340c000 | ((dest_high >> 12) << 16) | (dest_high & 0xfff);
      const int32_t patched_movw =
          0xe300c000 | ((dest_low >> 12) << 16) | (dest_low & 0xfff);

      region.Store<int32_t>(position, patched_movw);
      region.Store<int32_t>(position + Instr::kInstrSize, patched_movt);
      return;
    }

    // If the offset loading instructions aren't there, we must have replaced
    // the far branch with a near one, and so these instructions
    // should be NOPs.
    ASSERT((movt == Instr::kNopInstruction) &&
           (bx == Instr::kNopInstruction));
  }

  virtual bool IsPointerOffset() const { return false; }
};


void Assembler::EmitFarBranch(Condition cond, int32_t offset, bool link) {
  buffer_.EmitFixup(new PatchFarBranch());
  LoadPatchableImmediate(IP, offset);
  if (link) {
    blx(IP, cond);
  } else {
    bx(IP, cond);
  }
}


void Assembler::EmitBranch(Condition cond, Label* label, bool link) {
  if (label->IsBound()) {
    const int32_t dest = label->Position() - buffer_.Size();
    if (use_far_branches() && !CanEncodeBranchOffset(dest)) {
      EmitFarBranch(cond, label->Position(), link);
    } else {
      EmitType5(cond, dest, link);
    }
  } else {
    const intptr_t position = buffer_.Size();
    if (use_far_branches()) {
      const int32_t dest = label->position_;
      EmitFarBranch(cond, dest, link);
    } else {
      // Use the offset field of the branch instruction for linking the sites.
      EmitType5(cond, label->position_, link);
    }
    label->LinkTo(position);
  }
}


void Assembler::BindARMv6(Label* label) {
  ASSERT(!label->IsBound());
  intptr_t bound_pc = buffer_.Size();
  while (label->IsLinked()) {
    const int32_t position = label->Position();
    int32_t dest = bound_pc - position;
    if (use_far_branches() && !CanEncodeBranchOffset(dest)) {
      // Far branches are enabled and we can't encode the branch offset.

      // Grab instructions that load the offset.
      const int32_t mov =
          buffer_.Load<int32_t>(position);
      const int32_t or1 =
          buffer_.Load<int32_t>(position + 1 * Instr::kInstrSize);
      const int32_t or2 =
          buffer_.Load<int32_t>(position + 2 * Instr::kInstrSize);
      const int32_t or3 =
          buffer_.Load<int32_t>(position + 3 * Instr::kInstrSize);

      // Change from relative to the branch to relative to the assembler
      // buffer.
      dest = buffer_.Size();
      const int32_t dest0 = (dest & 0x000000ff);
      const int32_t dest1 = (dest & 0x0000ff00) >> 8;
      const int32_t dest2 = (dest & 0x00ff0000) >> 16;
      const int32_t dest3 = (dest & 0xff000000) >> 24;
      const int32_t patched_mov = 0xe3a0c400 | dest3;
      const int32_t patched_or1 = 0xe38cc800 | dest2;
      const int32_t patched_or2 = 0xe38ccc00 | dest1;
      const int32_t patched_or3 = 0xe38cc000 | dest0;

      // Rewrite the instructions.
      buffer_.Store<int32_t>(position + 0 * Instr::kInstrSize, patched_mov);
      buffer_.Store<int32_t>(position + 1 * Instr::kInstrSize, patched_or1);
      buffer_.Store<int32_t>(position + 2 * Instr::kInstrSize, patched_or2);
      buffer_.Store<int32_t>(position + 3 * Instr::kInstrSize, patched_or3);
      label->position_ = DecodeARMv6LoadImmediate(mov, or1, or2, or3);
    } else if (use_far_branches() && CanEncodeBranchOffset(dest)) {
      // Grab instructions that load the offset, and the branch.
      const int32_t mov =
          buffer_.Load<int32_t>(position);
      const int32_t or1 =
          buffer_.Load<int32_t>(position + 1 * Instr::kInstrSize);
      const int32_t or2 =
          buffer_.Load<int32_t>(position + 2 * Instr::kInstrSize);
      const int32_t or3 =
          buffer_.Load<int32_t>(position + 3 * Instr::kInstrSize);
      const int32_t branch =
          buffer_.Load<int32_t>(position + 4 * Instr::kInstrSize);

      // Grab the branch condition, and encode the link bit.
      const int32_t cond = branch & 0xf0000000;
      const int32_t link = (branch & 0x20) << 19;

      // Encode the branch and the offset.
      const int32_t new_branch = cond | link | 0x0a000000;
      const int32_t encoded = EncodeBranchOffset(dest, new_branch);

      // Write the encoded branch instruction followed by two nops.
      buffer_.Store<int32_t>(position, encoded);
      buffer_.Store<int32_t>(position + 1 * Instr::kInstrSize,
          Instr::kNopInstruction);
      buffer_.Store<int32_t>(position + 2 * Instr::kInstrSize,
          Instr::kNopInstruction);
      buffer_.Store<int32_t>(position + 3 * Instr::kInstrSize,
          Instr::kNopInstruction);
      buffer_.Store<int32_t>(position + 4 * Instr::kInstrSize,
          Instr::kNopInstruction);

      label->position_ = DecodeARMv6LoadImmediate(mov, or1, or2, or3);
    } else {
      int32_t next = buffer_.Load<int32_t>(position);
      int32_t encoded = Assembler::EncodeBranchOffset(dest, next);
      buffer_.Store<int32_t>(position, encoded);
      label->position_ = Assembler::DecodeBranchOffset(next);
    }
  }
  label->BindTo(bound_pc);
}


void Assembler::BindARMv7(Label* label) {
  ASSERT(!label->IsBound());
  intptr_t bound_pc = buffer_.Size();
  while (label->IsLinked()) {
    const int32_t position = label->Position();
    int32_t dest = bound_pc - position;
    if (use_far_branches() && !CanEncodeBranchOffset(dest)) {
      // Far branches are enabled and we can't encode the branch offset.

      // Grab instructions that load the offset.
      const int32_t movw =
          buffer_.Load<int32_t>(position + 0 * Instr::kInstrSize);
      const int32_t movt =
          buffer_.Load<int32_t>(position + 1 * Instr::kInstrSize);

      // Change from relative to the branch to relative to the assembler
      // buffer.
      dest = buffer_.Size();
      const uint16_t dest_high = Utils::High16Bits(dest);
      const uint16_t dest_low = Utils::Low16Bits(dest);
      const int32_t patched_movt =
          0xe340c000 | ((dest_high >> 12) << 16) | (dest_high & 0xfff);
      const int32_t patched_movw =
          0xe300c000 | ((dest_low >> 12) << 16) | (dest_low & 0xfff);

      // Rewrite the instructions.
      buffer_.Store<int32_t>(position + 0 * Instr::kInstrSize, patched_movw);
      buffer_.Store<int32_t>(position + 1 * Instr::kInstrSize, patched_movt);
      label->position_ = DecodeARMv7LoadImmediate(movt, movw);
    } else if (use_far_branches() && CanEncodeBranchOffset(dest)) {
      // Far branches are enabled, but we can encode the branch offset.

      // Grab instructions that load the offset, and the branch.
      const int32_t movw =
          buffer_.Load<int32_t>(position + 0 * Instr::kInstrSize);
      const int32_t movt =
          buffer_.Load<int32_t>(position + 1 * Instr::kInstrSize);
      const int32_t branch =
          buffer_.Load<int32_t>(position + 2 * Instr::kInstrSize);

      // Grab the branch condition, and encode the link bit.
      const int32_t cond = branch & 0xf0000000;
      const int32_t link = (branch & 0x20) << 19;

      // Encode the branch and the offset.
      const int32_t new_branch = cond | link | 0x0a000000;
      const int32_t encoded = EncodeBranchOffset(dest, new_branch);

      // Write the encoded branch instruction followed by two nops.
      buffer_.Store<int32_t>(position + 0 * Instr::kInstrSize,
          encoded);
      buffer_.Store<int32_t>(position + 1 * Instr::kInstrSize,
          Instr::kNopInstruction);
      buffer_.Store<int32_t>(position + 2 * Instr::kInstrSize,
          Instr::kNopInstruction);

      label->position_ = DecodeARMv7LoadImmediate(movt, movw);
    } else {
      int32_t next = buffer_.Load<int32_t>(position);
      int32_t encoded = Assembler::EncodeBranchOffset(dest, next);
      buffer_.Store<int32_t>(position, encoded);
      label->position_ = Assembler::DecodeBranchOffset(next);
    }
  }
  label->BindTo(bound_pc);
}


void Assembler::Bind(Label* label) {
  const ARMVersion version = TargetCPUFeatures::arm_version();
  if ((version == ARMv5TE) || (version == ARMv6)) {
    BindARMv6(label);
  } else {
    ASSERT(version == ARMv7);
    BindARMv7(label);
  }
}


OperandSize Address::OperandSizeFor(intptr_t cid) {
  switch (cid) {
    case kArrayCid:
    case kImmutableArrayCid:
      return kWord;
    case kOneByteStringCid:
      return kByte;
    case kTwoByteStringCid:
      return kHalfword;
    case kTypedDataInt8ArrayCid:
      return kByte;
    case kTypedDataUint8ArrayCid:
    case kTypedDataUint8ClampedArrayCid:
    case kExternalTypedDataUint8ArrayCid:
    case kExternalTypedDataUint8ClampedArrayCid:
      return kUnsignedByte;
    case kTypedDataInt16ArrayCid:
      return kHalfword;
    case kTypedDataUint16ArrayCid:
      return kUnsignedHalfword;
    case kTypedDataInt32ArrayCid:
      return kWord;
    case kTypedDataUint32ArrayCid:
      return kUnsignedWord;
    case kTypedDataInt64ArrayCid:
    case kTypedDataUint64ArrayCid:
      UNREACHABLE();
      return kByte;
    case kTypedDataFloat32ArrayCid:
      return kSWord;
    case kTypedDataFloat64ArrayCid:
      return kDWord;
    case kTypedDataFloat32x4ArrayCid:
    case kTypedDataInt32x4ArrayCid:
    case kTypedDataFloat64x2ArrayCid:
      return kRegList;
    case kTypedDataInt8ArrayViewCid:
      UNREACHABLE();
      return kByte;
    default:
      UNREACHABLE();
      return kByte;
  }
}


bool Address::CanHoldLoadOffset(OperandSize size,
                                int32_t offset,
                                int32_t* offset_mask) {
  switch (size) {
    case kByte:
    case kHalfword:
    case kUnsignedHalfword:
    case kWordPair: {
      *offset_mask = 0xff;
      return Utils::IsAbsoluteUint(8, offset);  // Addressing mode 3.
    }
    case kUnsignedByte:
    case kWord:
    case kUnsignedWord: {
      *offset_mask = 0xfff;
      return Utils::IsAbsoluteUint(12, offset);  // Addressing mode 2.
    }
    case kSWord:
    case kDWord: {
      *offset_mask = 0x3fc;  // Multiple of 4.
      // VFP addressing mode.
      return (Utils::IsAbsoluteUint(10, offset) && Utils::IsAligned(offset, 4));
    }
    case kRegList: {
      *offset_mask = 0x0;
      return offset == 0;
    }
    default: {
      UNREACHABLE();
      return false;
    }
  }
}


bool Address::CanHoldStoreOffset(OperandSize size,
                                 int32_t offset,
                                 int32_t* offset_mask) {
  switch (size) {
    case kHalfword:
    case kUnsignedHalfword:
    case kWordPair: {
      *offset_mask = 0xff;
      return Utils::IsAbsoluteUint(8, offset);  // Addressing mode 3.
    }
    case kByte:
    case kUnsignedByte:
    case kWord:
    case kUnsignedWord: {
      *offset_mask = 0xfff;
      return Utils::IsAbsoluteUint(12, offset);  // Addressing mode 2.
    }
    case kSWord:
    case kDWord: {
      *offset_mask = 0x3fc;  // Multiple of 4.
      // VFP addressing mode.
      return (Utils::IsAbsoluteUint(10, offset) && Utils::IsAligned(offset, 4));
    }
    case kRegList: {
      *offset_mask = 0x0;
      return offset == 0;
    }
    default: {
      UNREACHABLE();
      return false;
    }
  }
}


void Assembler::Push(Register rd, Condition cond) {
  str(rd, Address(SP, -kWordSize, Address::PreIndex), cond);
}


void Assembler::Pop(Register rd, Condition cond) {
  ldr(rd, Address(SP, kWordSize, Address::PostIndex), cond);
}


void Assembler::PushList(RegList regs, Condition cond) {
  stm(DB_W, SP, regs, cond);
}


void Assembler::PopList(RegList regs, Condition cond) {
  ldm(IA_W, SP, regs, cond);
}


void Assembler::MoveRegister(Register rd, Register rm, Condition cond) {
  if (rd != rm) {
    mov(rd, Operand(rm), cond);
  }
}


void Assembler::Lsl(Register rd, Register rm, uint32_t shift_imm,
                    Condition cond) {
  ASSERT(shift_imm != 0);  // Do not use Lsl if no shift is wanted.
  mov(rd, Operand(rm, LSL, shift_imm), cond);
}


void Assembler::Lsl(Register rd, Register rm, Register rs, Condition cond) {
  mov(rd, Operand(rm, LSL, rs), cond);
}


void Assembler::Lsr(Register rd, Register rm, uint32_t shift_imm,
                    Condition cond) {
  ASSERT(shift_imm != 0);  // Do not use Lsr if no shift is wanted.
  if (shift_imm == 32) shift_imm = 0;  // Comply to UAL syntax.
  mov(rd, Operand(rm, LSR, shift_imm), cond);
}


void Assembler::Lsr(Register rd, Register rm, Register rs, Condition cond) {
  mov(rd, Operand(rm, LSR, rs), cond);
}


void Assembler::Asr(Register rd, Register rm, uint32_t shift_imm,
                    Condition cond) {
  ASSERT(shift_imm != 0);  // Do not use Asr if no shift is wanted.
  if (shift_imm == 32) shift_imm = 0;  // Comply to UAL syntax.
  mov(rd, Operand(rm, ASR, shift_imm), cond);
}


void Assembler::Asr(Register rd, Register rm, Register rs, Condition cond) {
  mov(rd, Operand(rm, ASR, rs), cond);
}


void Assembler::Ror(Register rd, Register rm, uint32_t shift_imm,
                    Condition cond) {
  ASSERT(shift_imm != 0);  // Use Rrx instruction.
  mov(rd, Operand(rm, ROR, shift_imm), cond);
}


void Assembler::Ror(Register rd, Register rm, Register rs, Condition cond) {
  mov(rd, Operand(rm, ROR, rs), cond);
}


void Assembler::Rrx(Register rd, Register rm, Condition cond) {
  mov(rd, Operand(rm, ROR, 0), cond);
}


void Assembler::SignFill(Register rd, Register rm, Condition cond) {
  Asr(rd, rm, 31, cond);
}


void Assembler::Vreciprocalqs(QRegister qd, QRegister qm) {
  ASSERT(qm != QTMP);
  ASSERT(qd != QTMP);

  // Reciprocal estimate.
  vrecpeqs(qd, qm);
  // 2 Newton-Raphson steps.
  vrecpsqs(QTMP, qm, qd);
  vmulqs(qd, qd, QTMP);
  vrecpsqs(QTMP, qm, qd);
  vmulqs(qd, qd, QTMP);
}


void Assembler::VreciprocalSqrtqs(QRegister qd, QRegister qm) {
  ASSERT(qm != QTMP);
  ASSERT(qd != QTMP);

  // Reciprocal square root estimate.
  vrsqrteqs(qd, qm);
  // 2 Newton-Raphson steps. xn+1 = xn * (3 - Q1*xn^2) / 2.
  // First step.
  vmulqs(QTMP, qd, qd);  // QTMP <- xn^2
  vrsqrtsqs(QTMP, qm, QTMP);  // QTMP <- (3 - Q1*QTMP) / 2.
  vmulqs(qd, qd, QTMP);  // xn+1 <- xn * QTMP
  // Second step.
  vmulqs(QTMP, qd, qd);
  vrsqrtsqs(QTMP, qm, QTMP);
  vmulqs(qd, qd, QTMP);
}


void Assembler::Vsqrtqs(QRegister qd, QRegister qm, QRegister temp) {
  ASSERT(temp != QTMP);
  ASSERT(qm != QTMP);
  ASSERT(qd != QTMP);

  if (temp != kNoQRegister) {
    vmovq(temp, qm);
    qm = temp;
  }

  VreciprocalSqrtqs(qd, qm);
  vmovq(qm, qd);
  Vreciprocalqs(qd, qm);
}


void Assembler::Vdivqs(QRegister qd, QRegister qn, QRegister qm) {
  ASSERT(qd != QTMP);
  ASSERT(qn != QTMP);
  ASSERT(qm != QTMP);

  Vreciprocalqs(qd, qm);
  vmulqs(qd, qn, qd);
}


void Assembler::Branch(const ExternalLabel* label, Condition cond) {
  LoadImmediate(IP, label->address(), cond);  // Address is never patched.
  bx(IP, cond);
}


void Assembler::BranchPatchable(const ExternalLabel* label) {
  // Use a fixed size code sequence, since a function prologue may be patched
  // with this branch sequence.
  // Contrarily to BranchLinkPatchable, BranchPatchable requires an instruction
  // cache flush upon patching.
  LoadPatchableImmediate(IP, label->address());
  bx(IP);
}


void Assembler::BranchLink(const ExternalLabel* label) {
  LoadImmediate(IP, label->address());  // Target address is never patched.
  blx(IP);  // Use blx instruction so that the return branch prediction works.
}


void Assembler::BranchLinkPatchable(const ExternalLabel* label) {
  // Make sure that class CallPattern is able to patch the label referred
  // to by this code sequence.
  // For added code robustness, use 'blx lr' in a patchable sequence and
  // use 'blx ip' in a non-patchable sequence (see other BranchLink flavors).
  const int32_t offset =
      Array::data_offset() + 4*AddExternalLabel(label) - kHeapObjectTag;
  LoadWordFromPoolOffset(LR, offset);
  blx(LR);  // Use blx instruction so that the return branch prediction works.
}


void Assembler::BranchLinkOffset(Register base, int32_t offset) {
  ASSERT(base != PC);
  ASSERT(base != IP);
  LoadFromOffset(kWord, IP, base, offset);
  blx(IP);  // Use blx instruction so that the return branch prediction works.
}


void Assembler::LoadPatchableImmediate(
    Register rd, int32_t value, Condition cond) {
  const ARMVersion version = TargetCPUFeatures::arm_version();
  if ((version == ARMv5TE) || (version == ARMv6)) {
    // This sequence is patched in a few places, and should remain fixed.
    const uint32_t byte0 = (value & 0x000000ff);
    const uint32_t byte1 = (value & 0x0000ff00) >> 8;
    const uint32_t byte2 = (value & 0x00ff0000) >> 16;
    const uint32_t byte3 = (value & 0xff000000) >> 24;
    mov(rd, Operand(4, byte3), cond);
    orr(rd, rd, Operand(8, byte2), cond);
    orr(rd, rd, Operand(12, byte1), cond);
    orr(rd, rd, Operand(byte0), cond);
  } else {
    ASSERT(version == ARMv7);
    const uint16_t value_low = Utils::Low16Bits(value);
    const uint16_t value_high = Utils::High16Bits(value);
    movw(rd, value_low, cond);
    movt(rd, value_high, cond);
  }
}


void Assembler::LoadDecodableImmediate(
    Register rd, int32_t value, Condition cond) {
  const ARMVersion version = TargetCPUFeatures::arm_version();
  if ((version == ARMv5TE) || (version == ARMv6)) {
    LoadPatchableImmediate(rd, value, cond);
  } else {
    ASSERT(version == ARMv7);
    movw(rd, Utils::Low16Bits(value), cond);
    const uint16_t value_high = Utils::High16Bits(value);
    if (value_high != 0) {
      movt(rd, value_high, cond);
    }
  }
}


void Assembler::LoadImmediate(Register rd, int32_t value, Condition cond) {
  Operand o;
  if (Operand::CanHold(value, &o)) {
    mov(rd, o, cond);
  } else if (Operand::CanHold(~value, &o)) {
    mvn(rd, o, cond);
  } else {
    LoadDecodableImmediate(rd, value, cond);
  }
}


void Assembler::LoadSImmediate(SRegister sd, float value, Condition cond) {
  if (!vmovs(sd, value, cond)) {
    LoadImmediate(IP, bit_cast<int32_t, float>(value), cond);
    vmovsr(sd, IP, cond);
  }
}


void Assembler::LoadDImmediate(DRegister dd,
                               double value,
                               Register scratch,
                               Condition cond) {
  ASSERT(scratch != PC);
  ASSERT(scratch != IP);
  if (!vmovd(dd, value, cond)) {
    // A scratch register and IP are needed to load an arbitrary double.
    ASSERT(scratch != kNoRegister);
    int64_t imm64 = bit_cast<int64_t, double>(value);
    LoadImmediate(IP, Utils::Low32Bits(imm64), cond);
    LoadImmediate(scratch, Utils::High32Bits(imm64), cond);
    vmovdrr(dd, IP, scratch, cond);
  }
}


void Assembler::LoadFromOffset(OperandSize size,
                               Register reg,
                               Register base,
                               int32_t offset,
                               Condition cond) {
  int32_t offset_mask = 0;
  if (!Address::CanHoldLoadOffset(size, offset, &offset_mask)) {
    ASSERT(base != IP);
    AddImmediate(IP, base, offset & ~offset_mask, cond);
    base = IP;
    offset = offset & offset_mask;
  }
  switch (size) {
    case kByte:
      ldrsb(reg, Address(base, offset), cond);
      break;
    case kUnsignedByte:
      ldrb(reg, Address(base, offset), cond);
      break;
    case kHalfword:
      ldrsh(reg, Address(base, offset), cond);
      break;
    case kUnsignedHalfword:
      ldrh(reg, Address(base, offset), cond);
      break;
    case kWord:
      ldr(reg, Address(base, offset), cond);
      break;
    case kWordPair:
      ldrd(reg, Address(base, offset), cond);
      break;
    default:
      UNREACHABLE();
  }
}


void Assembler::StoreToOffset(OperandSize size,
                              Register reg,
                              Register base,
                              int32_t offset,
                              Condition cond) {
  int32_t offset_mask = 0;
  if (!Address::CanHoldStoreOffset(size, offset, &offset_mask)) {
    ASSERT(reg != IP);
    ASSERT(base != IP);
    AddImmediate(IP, base, offset & ~offset_mask, cond);
    base = IP;
    offset = offset & offset_mask;
  }
  switch (size) {
    case kByte:
      strb(reg, Address(base, offset), cond);
      break;
    case kHalfword:
      strh(reg, Address(base, offset), cond);
      break;
    case kWord:
      str(reg, Address(base, offset), cond);
      break;
    case kWordPair:
      strd(reg, Address(base, offset), cond);
      break;
    default:
      UNREACHABLE();
  }
}


void Assembler::LoadSFromOffset(SRegister reg,
                                Register base,
                                int32_t offset,
                                Condition cond) {
  int32_t offset_mask = 0;
  if (!Address::CanHoldLoadOffset(kSWord, offset, &offset_mask)) {
    ASSERT(base != IP);
    AddImmediate(IP, base, offset & ~offset_mask, cond);
    base = IP;
    offset = offset & offset_mask;
  }
  vldrs(reg, Address(base, offset), cond);
}


void Assembler::StoreSToOffset(SRegister reg,
                               Register base,
                               int32_t offset,
                               Condition cond) {
  int32_t offset_mask = 0;
  if (!Address::CanHoldStoreOffset(kSWord, offset, &offset_mask)) {
    ASSERT(base != IP);
    AddImmediate(IP, base, offset & ~offset_mask, cond);
    base = IP;
    offset = offset & offset_mask;
  }
  vstrs(reg, Address(base, offset), cond);
}


void Assembler::LoadDFromOffset(DRegister reg,
                                Register base,
                                int32_t offset,
                                Condition cond) {
  int32_t offset_mask = 0;
  if (!Address::CanHoldLoadOffset(kDWord, offset, &offset_mask)) {
    ASSERT(base != IP);
    AddImmediate(IP, base, offset & ~offset_mask, cond);
    base = IP;
    offset = offset & offset_mask;
  }
  vldrd(reg, Address(base, offset), cond);
}


void Assembler::StoreDToOffset(DRegister reg,
                               Register base,
                               int32_t offset,
                               Condition cond) {
  int32_t offset_mask = 0;
  if (!Address::CanHoldStoreOffset(kDWord, offset, &offset_mask)) {
    ASSERT(base != IP);
    AddImmediate(IP, base, offset & ~offset_mask, cond);
    base = IP;
    offset = offset & offset_mask;
  }
  vstrd(reg, Address(base, offset), cond);
}


void Assembler::LoadMultipleDFromOffset(DRegister first,
                                        intptr_t count,
                                        Register base,
                                        int32_t offset) {
  ASSERT(base != IP);
  AddImmediate(IP, base, offset);
  vldmd(IA, IP, first, count);
}

void Assembler::StoreMultipleDToOffset(DRegister first,
                                       intptr_t count,
                                       Register base,
                                       int32_t offset) {
  ASSERT(base != IP);
  AddImmediate(IP, base, offset);
  vstmd(IA, IP, first, count);
}


void Assembler::CopyDoubleField(
    Register dst, Register src, Register tmp1, Register tmp2, DRegister dtmp) {
  if (TargetCPUFeatures::vfp_supported()) {
    LoadDFromOffset(dtmp, src, Double::value_offset() - kHeapObjectTag);
    StoreDToOffset(dtmp, dst, Double::value_offset() - kHeapObjectTag);
  } else {
    LoadFromOffset(kWord, tmp1, src,
        Double::value_offset() - kHeapObjectTag);
    LoadFromOffset(kWord, tmp2, src,
        Double::value_offset() + kWordSize - kHeapObjectTag);
    StoreToOffset(kWord, tmp1, dst,
        Double::value_offset() - kHeapObjectTag);
    StoreToOffset(kWord, tmp2, dst,
        Double::value_offset() + kWordSize - kHeapObjectTag);
  }
}


void Assembler::CopyFloat32x4Field(
    Register dst, Register src, Register tmp1, Register tmp2, DRegister dtmp) {
  if (TargetCPUFeatures::neon_supported()) {
    LoadMultipleDFromOffset(dtmp, 2, src,
        Float32x4::value_offset() - kHeapObjectTag);
    StoreMultipleDToOffset(dtmp, 2, dst,
        Float32x4::value_offset() - kHeapObjectTag);
  } else {
    LoadFromOffset(kWord, tmp1, src,
        (Float32x4::value_offset() + 0 * kWordSize) - kHeapObjectTag);
    LoadFromOffset(kWord, tmp2, src,
        (Float32x4::value_offset() + 1 * kWordSize) - kHeapObjectTag);
    StoreToOffset(kWord, tmp1, dst,
        (Float32x4::value_offset() + 0 * kWordSize) - kHeapObjectTag);
    StoreToOffset(kWord, tmp2, dst,
        (Float32x4::value_offset() + 1 * kWordSize) - kHeapObjectTag);

    LoadFromOffset(kWord, tmp1, src,
        (Float32x4::value_offset() + 2 * kWordSize) - kHeapObjectTag);
    LoadFromOffset(kWord, tmp2, src,
        (Float32x4::value_offset() + 3 * kWordSize) - kHeapObjectTag);
    StoreToOffset(kWord, tmp1, dst,
        (Float32x4::value_offset() + 2 * kWordSize) - kHeapObjectTag);
    StoreToOffset(kWord, tmp2, dst,
        (Float32x4::value_offset() + 3 * kWordSize) - kHeapObjectTag);
  }
}


void Assembler::CopyFloat64x2Field(
    Register dst, Register src, Register tmp1, Register tmp2, DRegister dtmp) {
  if (TargetCPUFeatures::neon_supported()) {
    LoadMultipleDFromOffset(dtmp, 2, src,
        Float64x2::value_offset() - kHeapObjectTag);
    StoreMultipleDToOffset(dtmp, 2, dst,
        Float64x2::value_offset() - kHeapObjectTag);
  } else {
    LoadFromOffset(kWord, tmp1, src,
        (Float64x2::value_offset() + 0 * kWordSize) - kHeapObjectTag);
    LoadFromOffset(kWord, tmp2, src,
        (Float64x2::value_offset() + 1 * kWordSize) - kHeapObjectTag);
    StoreToOffset(kWord, tmp1, dst,
        (Float64x2::value_offset() + 0 * kWordSize) - kHeapObjectTag);
    StoreToOffset(kWord, tmp2, dst,
        (Float64x2::value_offset() + 1 * kWordSize) - kHeapObjectTag);

    LoadFromOffset(kWord, tmp1, src,
        (Float64x2::value_offset() + 2 * kWordSize) - kHeapObjectTag);
    LoadFromOffset(kWord, tmp2, src,
        (Float64x2::value_offset() + 3 * kWordSize) - kHeapObjectTag);
    StoreToOffset(kWord, tmp1, dst,
        (Float64x2::value_offset() + 2 * kWordSize) - kHeapObjectTag);
    StoreToOffset(kWord, tmp2, dst,
        (Float64x2::value_offset() + 3 * kWordSize) - kHeapObjectTag);
  }
}


void Assembler::AddImmediate(Register rd, int32_t value, Condition cond) {
  AddImmediate(rd, rd, value, cond);
}


void Assembler::AddImmediate(Register rd, Register rn, int32_t value,
                             Condition cond) {
  if (value == 0) {
    if (rd != rn) {
      mov(rd, Operand(rn), cond);
    }
    return;
  }
  // We prefer to select the shorter code sequence rather than selecting add for
  // positive values and sub for negatives ones, which would slightly improve
  // the readability of generated code for some constants.
  Operand o;
  if (Operand::CanHold(value, &o)) {
    add(rd, rn, o, cond);
  } else if (Operand::CanHold(-value, &o)) {
    sub(rd, rn, o, cond);
  } else {
    ASSERT(rn != IP);
    if (Operand::CanHold(~value, &o)) {
      mvn(IP, o, cond);
      add(rd, rn, Operand(IP), cond);
    } else if (Operand::CanHold(~(-value), &o)) {
      mvn(IP, o, cond);
      sub(rd, rn, Operand(IP), cond);
    } else {
      LoadDecodableImmediate(IP, value, cond);
      add(rd, rn, Operand(IP), cond);
    }
  }
}


void Assembler::AddImmediateSetFlags(Register rd, Register rn, int32_t value,
                                    Condition cond) {
  Operand o;
  if (Operand::CanHold(value, &o)) {
    // Handles value == kMinInt32.
    adds(rd, rn, o, cond);
  } else if (Operand::CanHold(-value, &o)) {
    ASSERT(value != kMinInt32);  // Would cause erroneous overflow detection.
    subs(rd, rn, o, cond);
  } else {
    ASSERT(rn != IP);
    if (Operand::CanHold(~value, &o)) {
      mvn(IP, o, cond);
      adds(rd, rn, Operand(IP), cond);
    } else if (Operand::CanHold(~(-value), &o)) {
      ASSERT(value != kMinInt32);  // Would cause erroneous overflow detection.
      mvn(IP, o, cond);
      subs(rd, rn, Operand(IP), cond);
    } else {
      LoadDecodableImmediate(IP, value, cond);
      adds(rd, rn, Operand(IP), cond);
    }
  }
}


void Assembler::SubImmediateSetFlags(Register rd, Register rn, int32_t value,
                                    Condition cond) {
  Operand o;
  if (Operand::CanHold(value, &o)) {
    // Handles value == kMinInt32.
    subs(rd, rn, o, cond);
  } else if (Operand::CanHold(-value, &o)) {
    ASSERT(value != kMinInt32);  // Would cause erroneous overflow detection.
    adds(rd, rn, o, cond);
  } else {
    ASSERT(rn != IP);
    if (Operand::CanHold(~value, &o)) {
      mvn(IP, o, cond);
      subs(rd, rn, Operand(IP), cond);
    } else if (Operand::CanHold(~(-value), &o)) {
      ASSERT(value != kMinInt32);  // Would cause erroneous overflow detection.
      mvn(IP, o, cond);
      adds(rd, rn, Operand(IP), cond);
    } else {
      LoadDecodableImmediate(IP, value, cond);
      subs(rd, rn, Operand(IP), cond);
    }
  }
}


void Assembler::AndImmediate(Register rd, Register rs, int32_t imm,
                             Condition cond) {
  Operand o;
  if (Operand::CanHold(imm, &o)) {
    and_(rd, rs, Operand(o), cond);
  } else {
    LoadImmediate(TMP, imm, cond);
    and_(rd, rs, Operand(TMP), cond);
  }
}


void Assembler::CompareImmediate(Register rn, int32_t value, Condition cond) {
  Operand o;
  if (Operand::CanHold(value, &o)) {
    cmp(rn, o, cond);
  } else {
    ASSERT(rn != IP);
    LoadImmediate(IP, value, cond);
    cmp(rn, Operand(IP), cond);
  }
}


void Assembler::TestImmediate(Register rn, int32_t imm, Condition cond) {
  Operand o;
  if (Operand::CanHold(imm, &o)) {
    tst(rn, o, cond);
  } else {
    LoadImmediate(IP, imm);
    tst(rn, Operand(IP), cond);
  }
}

void Assembler::IntegerDivide(Register result, Register left, Register right,
                              DRegister tmpl, DRegister tmpr) {
  ASSERT(tmpl != tmpr);
  if (TargetCPUFeatures::integer_division_supported()) {
    sdiv(result, left, right);
  } else {
    SRegister stmpl = static_cast<SRegister>(2 * tmpl);
    SRegister stmpr = static_cast<SRegister>(2 * tmpr);
    vmovsr(stmpl, left);
    vcvtdi(tmpl, stmpl);  // left is in tmpl.
    vmovsr(stmpr, right);
    vcvtdi(tmpr, stmpr);  // right is in tmpr.
    vdivd(tmpr, tmpl, tmpr);
    vcvtid(stmpr, tmpr);
    vmovrs(result, stmpr);
  }
}


// If we aren't on ARMv7, there is no smull, and we have to check for overflow
// manually.
void Assembler::CheckMultSignedOverflow(Register left,
                                        Register right,
                                        Register tmp,
                                        DRegister dtmp0, DRegister dtmp1,
                                        Label* overflow) {
  Label done, left_neg, left_pos_right_neg, left_neg_right_pos;

  CompareImmediate(left, 0);
  b(&left_neg, LT);
  b(&done, EQ);
  CompareImmediate(right, 0);
  b(&left_pos_right_neg, LT);
  b(&done, EQ);

  // Both positive.
  LoadImmediate(tmp, INT_MAX);
  IntegerDivide(tmp, tmp, left, dtmp0, dtmp1);
  cmp(tmp, Operand(right));
  b(overflow, LT);
  b(&done);

  // left positive, right non-positive.
  Bind(&left_pos_right_neg);
  LoadImmediate(tmp, INT_MIN);
  IntegerDivide(tmp, tmp, left, dtmp0, dtmp1);
  cmp(tmp, Operand(right));
  b(overflow, GT);
  b(&done);

  Bind(&left_neg);
  CompareImmediate(right, 0);
  b(&left_neg_right_pos, GT);
  b(&done, EQ);

  // both negative.
  LoadImmediate(tmp, INT_MAX);
  IntegerDivide(tmp, tmp, left, dtmp0, dtmp1);
  cmp(tmp, Operand(right));
  b(overflow, GT);
  b(&done);

  // left non-positive, right positive.
  Bind(&left_neg_right_pos);
  LoadImmediate(tmp, INT_MIN);
  IntegerDivide(tmp, tmp, right, dtmp0, dtmp1);
  cmp(tmp, Operand(left));
  b(overflow, GT);

  Bind(&done);
}


static int NumRegsBelowFP(RegList regs) {
  int count = 0;
  for (int i = 0; i < FP; i++) {
    if ((regs & (1 << i)) != 0) {
      count++;
    }
  }
  return count;
}


void Assembler::EnterFrame(RegList regs, intptr_t frame_size) {
  if (prologue_offset_ == -1) {
    prologue_offset_ = CodeSize();
  }
  PushList(regs);
  if ((regs & (1 << FP)) != 0) {
    // Set FP to the saved previous FP.
    add(FP, SP, Operand(4 * NumRegsBelowFP(regs)));
  }
  AddImmediate(SP, -frame_size);
}


void Assembler::LeaveFrame(RegList regs) {
  ASSERT((regs & (1 << PC)) == 0);  // Must not pop PC.
  if ((regs & (1 << FP)) != 0) {
    // Use FP to set SP.
    sub(SP, FP, Operand(4 * NumRegsBelowFP(regs)));
  }
  PopList(regs);
}


void Assembler::Ret() {
  bx(LR);
}


void Assembler::ReserveAlignedFrameSpace(intptr_t frame_space) {
  // Reserve space for arguments and align frame before entering
  // the C++ world.
  AddImmediate(SP, -frame_space);
  if (OS::ActivationFrameAlignment() > 1) {
    bic(SP, SP, Operand(OS::ActivationFrameAlignment() - 1));
  }
}


void Assembler::EnterCallRuntimeFrame(intptr_t frame_space) {
  // Preserve volatile CPU registers.
  EnterFrame(kDartVolatileCpuRegs | (1 << FP) | (1 << LR), 0);

  // Preserve all volatile FPU registers.
  if (TargetCPUFeatures::vfp_supported()) {
    DRegister firstv = EvenDRegisterOf(kDartFirstVolatileFpuReg);
    DRegister lastv = OddDRegisterOf(kDartLastVolatileFpuReg);
    if ((lastv - firstv + 1) >= 16) {
      DRegister mid = static_cast<DRegister>(firstv + 16);
      vstmd(DB_W, SP, mid, lastv - mid + 1);
      vstmd(DB_W, SP, firstv, 16);
    } else {
      vstmd(DB_W, SP, firstv, lastv - firstv + 1);
    }
  }

  ReserveAlignedFrameSpace(frame_space);
}


void Assembler::LeaveCallRuntimeFrame() {
  // SP might have been modified to reserve space for arguments
  // and ensure proper alignment of the stack frame.
  // We need to restore it before restoring registers.
  const intptr_t kPushedFpuRegisterSize =
      TargetCPUFeatures::vfp_supported() ?
      kDartVolatileFpuRegCount * kFpuRegisterSize : 0;

  const intptr_t kPushedRegistersSize =
      kDartVolatileCpuRegCount * kWordSize + kPushedFpuRegisterSize;
  AddImmediate(SP, FP, -kPushedRegistersSize);

  // Restore all volatile FPU registers.
  if (TargetCPUFeatures::vfp_supported()) {
    DRegister firstv = EvenDRegisterOf(kDartFirstVolatileFpuReg);
    DRegister lastv = OddDRegisterOf(kDartLastVolatileFpuReg);
    if ((lastv - firstv + 1) >= 16) {
      DRegister mid = static_cast<DRegister>(firstv + 16);
      vldmd(IA_W, SP, firstv, 16);
      vldmd(IA_W, SP, mid, lastv - mid + 1);
    } else {
      vldmd(IA_W, SP, firstv, lastv - firstv + 1);
    }
  }

  // Restore volatile CPU registers.
  LeaveFrame(kDartVolatileCpuRegs | (1 << FP) | (1 << LR));
}


void Assembler::CallRuntime(const RuntimeEntry& entry,
                            intptr_t argument_count) {
  entry.Call(this, argument_count);
}


void Assembler::EnterDartFrame(intptr_t frame_size) {
  const intptr_t offset = CodeSize();

  // Save PC in frame for fast identification of corresponding code.
  // Note that callee-saved registers can be added to the register list.
  EnterFrame((1 << PP) | (1 << FP) | (1 << LR) | (1 << PC), 0);

  if (offset != 0) {
    // Adjust saved PC for any intrinsic code that could have been generated
    // before a frame is created. Use PP as temp register.
    ldr(PP, Address(FP, 2 * kWordSize));
    AddImmediate(PP, PP, -offset);
    str(PP, Address(FP, 2 * kWordSize));
  }

  // Setup pool pointer for this dart function.
  LoadPoolPointer();

  // Reserve space for locals.
  AddImmediate(SP, -frame_size);
}


// On entry to a function compiled for OSR, the caller's frame pointer, the
// stack locals, and any copied parameters are already in place.  The frame
// pointer is already set up.  The PC marker is not correct for the
// optimized function and there may be extra space for spill slots to
// allocate. We must also set up the pool pointer for the function.
void Assembler::EnterOsrFrame(intptr_t extra_size) {
  const intptr_t offset = CodeSize();

  Comment("EnterOsrFrame");
  mov(IP, Operand(PC));

  AddImmediate(IP, -offset);
  str(IP, Address(FP, kPcMarkerSlotFromFp * kWordSize));

  // Setup pool pointer for this dart function.
  LoadPoolPointer();

  AddImmediate(SP, -extra_size);
}


void Assembler::LeaveDartFrame() {
  LeaveFrame((1 << PP) | (1 << FP) | (1 << LR));
  // Adjust SP for PC pushed in EnterDartFrame.
  AddImmediate(SP, kWordSize);
}


void Assembler::EnterStubFrame(bool load_pp) {
  // Push 0 as saved PC for stub frames.
  mov(IP, Operand(LR));
  mov(LR, Operand(0));
  RegList regs = (1 << PP) | (1 << FP) | (1 << IP) | (1 << LR);
  EnterFrame(regs, 0);
  if (load_pp) {
    // Setup pool pointer for this stub.
    LoadPoolPointer();
  }
}


void Assembler::LeaveStubFrame() {
  LeaveFrame((1 << PP) | (1 << FP) | (1 << LR));
  // Adjust SP for null PC pushed in EnterStubFrame.
  AddImmediate(SP, kWordSize);
}


void Assembler::UpdateAllocationStats(intptr_t cid,
                                      Register temp_reg,
                                      Heap::Space space) {
  ASSERT(temp_reg != kNoRegister);
  ASSERT(temp_reg != TMP);
  ASSERT(cid > 0);
  Isolate* isolate = Isolate::Current();
  ClassTable* class_table = isolate->class_table();
  if (cid < kNumPredefinedCids) {
    const uword class_heap_stats_table_address =
        class_table->PredefinedClassHeapStatsTableAddress();
    const uword class_offset = cid * sizeof(ClassHeapStats);  // NOLINT
    const uword count_field_offset = (space == Heap::kNew) ?
      ClassHeapStats::allocated_since_gc_new_space_offset() :
      ClassHeapStats::allocated_since_gc_old_space_offset();
    LoadImmediate(temp_reg, class_heap_stats_table_address + class_offset);
    const Address& count_address = Address(temp_reg, count_field_offset);
    ldr(TMP, count_address);
    AddImmediate(TMP, 1);
    str(TMP, count_address);
  } else {
    ASSERT(temp_reg != kNoRegister);
    const uword class_offset = cid * sizeof(ClassHeapStats);  // NOLINT
    const uword count_field_offset = (space == Heap::kNew) ?
      ClassHeapStats::allocated_since_gc_new_space_offset() :
      ClassHeapStats::allocated_since_gc_old_space_offset();
    LoadImmediate(temp_reg, class_table->ClassStatsTableAddress());
    ldr(temp_reg, Address(temp_reg, 0));
    AddImmediate(temp_reg, class_offset);
    ldr(TMP, Address(temp_reg, count_field_offset));
    AddImmediate(TMP, 1);
    str(TMP, Address(temp_reg, count_field_offset));
  }
}


void Assembler::UpdateAllocationStatsWithSize(intptr_t cid,
                                              Register size_reg,
                                              Register temp_reg,
                                              Heap::Space space) {
  ASSERT(temp_reg != kNoRegister);
  ASSERT(temp_reg != TMP);
  ASSERT(cid > 0);
  Isolate* isolate = Isolate::Current();
  ClassTable* class_table = isolate->class_table();
  if (cid < kNumPredefinedCids) {
    const uword class_heap_stats_table_address =
        class_table->PredefinedClassHeapStatsTableAddress();
    const uword class_offset = cid * sizeof(ClassHeapStats);  // NOLINT
    const uword count_field_offset = (space == Heap::kNew) ?
      ClassHeapStats::allocated_since_gc_new_space_offset() :
      ClassHeapStats::allocated_since_gc_old_space_offset();
    const uword size_field_offset = (space == Heap::kNew) ?
      ClassHeapStats::allocated_size_since_gc_new_space_offset() :
      ClassHeapStats::allocated_size_since_gc_old_space_offset();
    LoadImmediate(temp_reg, class_heap_stats_table_address + class_offset);
    const Address& count_address = Address(temp_reg, count_field_offset);
    const Address& size_address = Address(temp_reg, size_field_offset);
    ldr(TMP, count_address);
    AddImmediate(TMP, 1);
    str(TMP, count_address);
    ldr(TMP, size_address);
    add(TMP, TMP, Operand(size_reg));
    str(TMP, size_address);
  } else {
    ASSERT(temp_reg != kNoRegister);
    const uword class_offset = cid * sizeof(ClassHeapStats);  // NOLINT
    const uword count_field_offset = (space == Heap::kNew) ?
      ClassHeapStats::allocated_since_gc_new_space_offset() :
      ClassHeapStats::allocated_since_gc_old_space_offset();
    const uword size_field_offset = (space == Heap::kNew) ?
      ClassHeapStats::allocated_size_since_gc_new_space_offset() :
      ClassHeapStats::allocated_size_since_gc_old_space_offset();
    LoadImmediate(temp_reg, class_table->ClassStatsTableAddress());
    ldr(temp_reg, Address(temp_reg, 0));
    AddImmediate(temp_reg, class_offset);
    ldr(TMP, Address(temp_reg, count_field_offset));
    AddImmediate(TMP, 1);
    str(TMP, Address(temp_reg, count_field_offset));
    ldr(TMP, Address(temp_reg, size_field_offset));
    add(TMP, TMP, Operand(size_reg));
    str(TMP, Address(temp_reg, size_field_offset));
  }
}


void Assembler::TryAllocate(const Class& cls,
                            Label* failure,
                            Register instance_reg,
                            Register temp_reg) {
  ASSERT(failure != NULL);
  if (FLAG_inline_alloc) {
    Heap* heap = Isolate::Current()->heap();
    const intptr_t instance_size = cls.instance_size();
    LoadImmediate(instance_reg, heap->TopAddress());
    ldr(instance_reg, Address(instance_reg, 0));
    AddImmediate(instance_reg, instance_size);

    // instance_reg: potential next object start.
    LoadImmediate(IP, heap->EndAddress());
    ldr(IP, Address(IP, 0));
    cmp(IP, Operand(instance_reg));
    // fail if heap end unsigned less than or equal to instance_reg.
    b(failure, LS);

    // Successfully allocated the object, now update top to point to
    // next object start and store the class in the class field of object.
    LoadImmediate(IP, heap->TopAddress());
    str(instance_reg, Address(IP, 0));

    ASSERT(instance_size >= kHeapObjectTag);
    AddImmediate(instance_reg, -instance_size + kHeapObjectTag);
    UpdateAllocationStats(cls.id(), temp_reg);

    uword tags = 0;
    tags = RawObject::SizeTag::update(instance_size, tags);
    ASSERT(cls.id() != kIllegalCid);
    tags = RawObject::ClassIdTag::update(cls.id(), tags);
    LoadImmediate(IP, tags);
    str(IP, FieldAddress(instance_reg, Object::tags_offset()));
  } else {
    b(failure);
  }
}


void Assembler::Stop(const char* message) {
  if (FLAG_print_stop_message) {
    StubCode* stub_code = Isolate::Current()->stub_code();
    PushList((1 << R0) | (1 << IP) | (1 << LR));  // Preserve R0, IP, LR.
    LoadImmediate(R0, reinterpret_cast<int32_t>(message));
    // PrintStopMessage() preserves all registers.
    BranchLink(&stub_code->PrintStopMessageLabel());  // Passing message in R0.
    PopList((1 << R0) | (1 << IP) | (1 << LR));  // Restore R0, IP, LR.
  }
  // Emit the message address before the svc instruction, so that we can
  // 'unstop' and continue execution in the simulator or jump to the next
  // instruction in gdb.
  Label stop;
  b(&stop);
  Emit(reinterpret_cast<int32_t>(message));
  Bind(&stop);
  svc(kStopMessageSvcCode);
}


int32_t Assembler::AddObject(const Object& obj) {
  ASSERT(obj.IsNotTemporaryScopedHandle());
  ASSERT(obj.IsOld());
  if (object_pool_.IsNull()) {
    // The object pool cannot be used in the vm isolate.
    ASSERT(Isolate::Current() != Dart::vm_isolate());
    object_pool_ = GrowableObjectArray::New(Heap::kOld);
  }
  for (intptr_t i = 0; i < object_pool_.Length(); i++) {
    if (object_pool_.At(i) == obj.raw()) {
      return i;
    }
  }
  object_pool_.Add(obj, Heap::kOld);
  return object_pool_.Length() - 1;
}


int32_t Assembler::AddExternalLabel(const ExternalLabel* label) {
  if (object_pool_.IsNull()) {
    // The object pool cannot be used in the vm isolate.
    ASSERT(Isolate::Current() != Dart::vm_isolate());
    object_pool_ = GrowableObjectArray::New(Heap::kOld);
  }
  const word address = label->address();
  ASSERT(Utils::IsAligned(address, 4));
  // The address is stored in the object array as a RawSmi.
  const Smi& smi = Smi::Handle(Smi::New(address >> kSmiTagShift));
  // Do not reuse an existing entry, since each reference may be patched
  // independently.
  object_pool_.Add(smi, Heap::kOld);
  return object_pool_.Length() - 1;
}


static const char* cpu_reg_names[kNumberOfCpuRegisters] = {
  "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
  "r8", "ctx", "pp", "fp", "ip", "sp", "lr", "pc",
};


const char* Assembler::RegisterName(Register reg) {
  ASSERT((0 <= reg) && (reg < kNumberOfCpuRegisters));
  return cpu_reg_names[reg];
}


static const char* fpu_reg_names[kNumberOfFpuRegisters] = {
  "q0", "q1", "q2", "q3", "q4", "q5", "q6", "q7",
#if defined(VFPv3_D32)
  "q8", "q9", "q10", "q11", "q12", "q13", "q14", "q15",
#endif
};


const char* Assembler::FpuRegisterName(FpuRegister reg) {
  ASSERT((0 <= reg) && (reg < kNumberOfFpuRegisters));
  return fpu_reg_names[reg];
}

}  // namespace dart

#endif  // defined TARGET_ARCH_ARM