text: // Copyright 2012 the V8 project authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #include "src/v8.h"
  
  #if V8_TARGET_ARCH_ARM
  
  #include "src/base/bits.h"
  #include "src/bootstrapper.h"
  #include "src/code-stubs.h"
  #include "src/codegen.h"
  #include "src/ic/handler-compiler.h"
  #include "src/ic/ic.h"
  #include "src/isolate.h"
  #include "src/jsregexp.h"
  #include "src/regexp-macro-assembler.h"
  #include "src/runtime/runtime.h"
  
  namespace v8 {
  namespace internal {
  
  
  static void InitializeArrayConstructorDescriptor(
      Isolate* isolate, CodeStubDescriptor* descriptor,
      int constant_stack_parameter_count) {
    Address deopt_handler = Runtime::FunctionForId(
        Runtime::kArrayConstructor)->entry;
  
    if (constant_stack_parameter_count == 0) {
      descriptor->Initialize(deopt_handler, constant_stack_parameter_count,
                             JS_FUNCTION_STUB_MODE);
    } else {
      descriptor->Initialize(r0, deopt_handler, constant_stack_parameter_count,
                             JS_FUNCTION_STUB_MODE, PASS_ARGUMENTS);
    }
  }
  
  
  static void InitializeInternalArrayConstructorDescriptor(
      Isolate* isolate, CodeStubDescriptor* descriptor,
      int constant_stack_parameter_count) {
    Address deopt_handler = Runtime::FunctionForId(
        Runtime::kInternalArrayConstructor)->entry;
  
    if (constant_stack_parameter_count == 0) {
      descriptor->Initialize(deopt_handler, constant_stack_parameter_count,
                             JS_FUNCTION_STUB_MODE);
    } else {
      descriptor->Initialize(r0, deopt_handler, constant_stack_parameter_count,
                             JS_FUNCTION_STUB_MODE, PASS_ARGUMENTS);
    }
  }
  
  
  void ArrayNoArgumentConstructorStub::InitializeDescriptor(
      CodeStubDescriptor* descriptor) {
    InitializeArrayConstructorDescriptor(isolate(), descriptor, 0);
  }
  
  
  void ArraySingleArgumentConstructorStub::InitializeDescriptor(
      CodeStubDescriptor* descriptor) {
    InitializeArrayConstructorDescriptor(isolate(), descriptor, 1);
  }
  
  
  void ArrayNArgumentsConstructorStub::InitializeDescriptor(
      CodeStubDescriptor* descriptor) {
    InitializeArrayConstructorDescriptor(isolate(), descriptor, -1);
  }
  
  
  void InternalArrayNoArgumentConstructorStub::InitializeDescriptor(
      CodeStubDescriptor* descriptor) {
    InitializeInternalArrayConstructorDescriptor(isolate(), descriptor, 0);
  }
  
  
  void InternalArraySingleArgumentConstructorStub::InitializeDescriptor(
      CodeStubDescriptor* descriptor) {
    InitializeInternalArrayConstructorDescriptor(isolate(), descriptor, 1);
  }
  
  
  void InternalArrayNArgumentsConstructorStub::InitializeDescriptor(
      CodeStubDescriptor* descriptor) {
    InitializeInternalArrayConstructorDescriptor(isolate(), descriptor, -1);
  }
  
  
  #define __ ACCESS_MASM(masm)
  
  
  static void EmitIdenticalObjectComparison(MacroAssembler* masm,
                                            Label* slow,
                                            Condition cond);
  static void EmitSmiNonsmiComparison(MacroAssembler* masm,
                                      Register lhs,
                                      Register rhs,
                                      Label* lhs_not_nan,
                                      Label* slow,
                                      bool strict);
  static void EmitStrictTwoHeapObjectCompare(MacroAssembler* masm,
                                             Register lhs,
                                             Register rhs);
  
  
  void HydrogenCodeStub::GenerateLightweightMiss(MacroAssembler* masm,
                                                 ExternalReference miss) {
    // Update the static counter each time a new code stub is generated.
    isolate()->counters()->code_stubs()->Increment();
  
    CallInterfaceDescriptor descriptor = GetCallInterfaceDescriptor();
    int param_count = descriptor.GetEnvironmentParameterCount();
    {
      // Call the runtime system in a fresh internal frame.
      FrameAndConstantPoolScope scope(masm, StackFrame::INTERNAL);
      DCHECK(param_count == 0 ||
             r0.is(descriptor.GetEnvironmentParameterRegister(param_count - 1)));
      // Push arguments
      for (int i = 0; i < param_count; ++i) {
        __ push(descriptor.GetEnvironmentParameterRegister(i));
      }
      __ CallExternalReference(miss, param_count);
    }
  
    __ Ret();
  }
  
  
  void DoubleToIStub::Generate(MacroAssembler* masm) {
    Label out_of_range, only_low, negate, done;
    Register input_reg = source();
    Register result_reg = destination();
    DCHECK(is_truncating());
  
    int double_offset = offset();
    // Account for saved regs if input is sp.
    if (input_reg.is(sp)) double_offset += 3 * kPointerSize;
  
    Register scratch = GetRegisterThatIsNotOneOf(input_reg, result_reg);
    Register scratch_low =
        GetRegisterThatIsNotOneOf(input_reg, result_reg, scratch);
    Register scratch_high =
        GetRegisterThatIsNotOneOf(input_reg, result_reg, scratch, scratch_low);
    LowDwVfpRegister double_scratch = kScratchDoubleReg;
  
    __ Push(scratch_high, scratch_low, scratch);
  
    if (!skip_fastpath()) {
      // Load double input.
      __ vldr(double_scratch, MemOperand(input_reg, double_offset));
      __ vmov(scratch_low, scratch_high, double_scratch);
  
      // Do fast-path convert from double to int.
      __ vcvt_s32_f64(double_scratch.low(), double_scratch);
      __ vmov(result_reg, double_scratch.low());
  
      // If result is not saturated (0x7fffffff or 0x80000000), we are done.
      __ sub(scratch, result_reg, Operand(1));
      __ cmp(scratch, Operand(0x7ffffffe));
      __ b(lt, &done);
    } else {
      // We've already done MacroAssembler::TryFastTruncatedDoubleToILoad, so we
      // know exponent > 31, so we can skip the vcvt_s32_f64 which will saturate.
      if (double_offset == 0) {
        __ ldm(ia, input_reg, scratch_low.bit() | scratch_high.bit());
      } else {
        __ ldr(scratch_low, MemOperand(input_reg, double_offset));
        __ ldr(scratch_high, MemOperand(input_reg, double_offset + kIntSize));
      }
    }
  
    __ Ubfx(scratch, scratch_high,
           HeapNumber::kExponentShift, HeapNumber::kExponentBits);
    // Load scratch with exponent - 1. This is faster than loading
    // with exponent because Bias + 1 = 1024 which is an *ARM* immediate value.
    STATIC_ASSERT(HeapNumber::kExponentBias + 1 == 1024);
    __ sub(scratch, scratch, Operand(HeapNumber::kExponentBias + 1));
    // If exponent is greater than or equal to 84, the 32 less significant
    // bits are 0s (2^84 = 1, 52 significant bits, 32 uncoded bits),
    // the result is 0.
    // Compare exponent with 84 (compare exponent - 1 with 83).
    __ cmp(scratch, Operand(83));
    __ b(ge, &out_of_range);
  
    // If we reach this code, 31 <= exponent <= 83.
    // So, we don't have to handle cases where 0 <= exponent <= 20 for
    // which we would need to shift right the high part of the mantissa.
    // Scratch contains exponent - 1.
    // Load scratch with 52 - exponent (load with 51 - (exponent - 1)).
    __ rsb(scratch, scratch, Operand(51), SetCC);
    __ b(ls, &only_low);
    // 21 <= exponent <= 51, shift scratch_low and scratch_high
    // to generate the result.
    __ mov(scratch_low, Operand(scratch_low, LSR, scratch));
    // Scratch contains: 52 - exponent.
    // We needs: exponent - 20.
    // So we use: 32 - scratch = 32 - 52 + exponent = exponent - 20.
    __ rsb(scratch, scratch, Operand(32));
    __ Ubfx(result_reg, scratch_high,
            0, HeapNumber::kMantissaBitsInTopWord);
    // Set the implicit 1 before the mantissa part in scratch_high.
    __ orr(result_reg, result_reg,
           Operand(1 << HeapNumber::kMantissaBitsInTopWord));
    __ orr(result_reg, scratch_low, Operand(result_reg, LSL, scratch));
    __ b(&negate);
  
    __ bind(&out_of_range);
    __ mov(result_reg, Operand::Zero());
    __ b(&done);
  
    __ bind(&only_low);
    // 52 <= exponent <= 83, shift only scratch_low.
    // On entry, scratch contains: 52 - exponent.
    __ rsb(scratch, scratch, Operand::Zero());
    __ mov(result_reg, Operand(scratch_low, LSL, scratch));
  
    __ bind(&negate);
    // If input was positive, scratch_high ASR 31 equals 0 and
    // scratch_high LSR 31 equals zero.
    // New result = (result eor 0) + 0 = result.
    // If the input was negative, we have to negate the result.
    // Input_high ASR 31 equals 0xffffffff and scratch_high LSR 31 equals 1.
    // New result = (result eor 0xffffffff) + 1 = 0 - result.
    __ eor(result_reg, result_reg, Operand(scratch_high, ASR, 31));
    __ add(result_reg, result_reg, Operand(scratch_high, LSR, 31));
  
    __ bind(&done);
  
    __ Pop(scratch_high, scratch_low, scratch);
    __ Ret();
  }
  
  
  void WriteInt32ToHeapNumberStub::GenerateFixedRegStubsAheadOfTime(
      Isolate* isolate) {
    WriteInt32ToHeapNumberStub stub1(isolate, r1, r0, r2);
    WriteInt32ToHeapNumberStub stub2(isolate, r2, r0, r3);
    stub1.GetCode();
    stub2.GetCode();
  }
  
  
  // See comment for class.
  void WriteInt32ToHeapNumberStub::Generate(MacroAssembler* masm) {
    Label max_negative_int;
    // the_int_ has the answer which is a signed int32 but not a Smi.
    // We test for the special value that has a different exponent.  This test
    // has the neat side effect of setting the flags according to the sign.
    STATIC_ASSERT(HeapNumber::kSignMask == 0x80000000u);
    __ cmp(the_int(), Operand(0x80000000u));
    __ b(eq, &max_negative_int);
    // Set up the correct exponent in scratch_.  All non-Smi int32s have the same.
    // A non-Smi integer is 1.xxx * 2^30 so the exponent is 30 (biased).
    uint32_t non_smi_exponent =
        (HeapNumber::kExponentBias + 30) << HeapNumber::kExponentShift;
    __ mov(scratch(), Operand(non_smi_exponent));
    // Set the sign bit in scratch_ if the value was negative.
    __ orr(scratch(), scratch(), Operand(HeapNumber::kSignMask), LeaveCC, cs);
    // Subtract from 0 if the value was negative.
    __ rsb(the_int(), the_int(), Operand::Zero(), LeaveCC, cs);
    // We should be masking the implict first digit of the mantissa away here,
    // but it just ends up combining harmlessly with the last digit of the
    // exponent that happens to be 1.  The sign bit is 0 so we shift 10 to get
    // the most significant 1 to hit the last bit of the 12 bit sign and exponent.
    DCHECK(((1 << HeapNumber::kExponentShift) & non_smi_exponent) != 0);
    const int shift_distance = HeapNumber::kNonMantissaBitsInTopWord - 2;
    __ orr(scratch(), scratch(), Operand(the_int(), LSR, shift_distance));
    __ str(scratch(),
           FieldMemOperand(the_heap_number(), HeapNumber::kExponentOffset));
    __ mov(scratch(), Operand(the_int(), LSL, 32 - shift_distance));
    __ str(scratch(),
           FieldMemOperand(the_heap_number(), HeapNumber::kMantissaOffset));
    __ Ret();
  
    __ bind(&max_negative_int);
    // The max negative int32 is stored as a positive number in the mantissa of
    // a double because it uses a sign bit instead of using two's complement.
    // The actual mantissa bits stored are all 0 because the implicit most
    // significant 1 bit is not stored.
    non_smi_exponent += 1 << HeapNumber::kExponentShift;
    __ mov(ip, Operand(HeapNumber::kSignMask | non_smi_exponent));
    __ str(ip, FieldMemOperand(the_heap_number(), HeapNumber::kExponentOffset));
    __ mov(ip, Operand::Zero());
    __ str(ip, FieldMemOperand(the_heap_number(), HeapNumber::kMantissaOffset));
    __ Ret();
  }
  
  
  // Handle the case where the lhs and rhs are the same object.
  // Equality is almost reflexive (everything but NaN), so this is a test
  // for "identity and not NaN".
  static void EmitIdenticalObjectComparison(MacroAssembler* masm,
                                            Label* slow,
                                            Condition cond) {
    Label not_identical;
    Label heap_number, return_equal;
    __ cmp(r0, r1);
    __ b(ne, &not_identical);
  
    // Test for NaN. Sadly, we can't just compare to Factory::nan_value(),
    // so we do the second best thing - test it ourselves.
    // They are both equal and they are not both Smis so both of them are not
    // Smis.  If it's not a heap number, then return equal.
    if (cond == lt || cond == gt) {
      __ CompareObjectType(r0, r4, r4, FIRST_SPEC_OBJECT_TYPE);
      __ b(ge, slow);
    } else {
      __ CompareObjectType(r0, r4, r4, HEAP_NUMBER_TYPE);
      __ b(eq, &heap_number);
      // Comparing JS objects with <=, >= is complicated.
      if (cond != eq) {
        __ cmp(r4, Operand(FIRST_SPEC_OBJECT_TYPE));
        __ b(ge, slow);
        // Normally here we fall through to return_equal, but undefined is
        // special: (undefined == undefined) == true, but
        // (undefined <= undefined) == false!  See ECMAScript 11.8.5.
        if (cond == le || cond == ge) {
          __ cmp(r4, Operand(ODDBALL_TYPE));
          __ b(ne, &return_equal);
          __ LoadRoot(r2, Heap::kUndefinedValueRootIndex);
          __ cmp(r0, r2);
          __ b(ne, &return_equal);
          if (cond == le) {
            // undefined <= undefined should fail.
            __ mov(r0, Operand(GREATER));
          } else  {
            // undefined >= undefined should fail.
            __ mov(r0, Operand(LESS));
          }
          __ Ret();
        }
      }
    }
  
    __ bind(&return_equal);
    if (cond == lt) {
      __ mov(r0, Operand(GREATER));  // Things aren't less than themselves.
    } else if (cond == gt) {
      __ mov(r0, Operand(LESS));     // Things aren't greater than themselves.
    } else {
      __ mov(r0, Operand(EQUAL));    // Things are <=, >=, ==, === themselves.
    }
    __ Ret();
  
    // For less and greater we don't have to check for NaN since the result of
    // x < x is false regardless.  For the others here is some code to check
    // for NaN.
    if (cond != lt && cond != gt) {
      __ bind(&heap_number);
      // It is a heap number, so return non-equal if it's NaN and equal if it's
      // not NaN.
  
      // The representation of NaN values has all exponent bits (52..62) set,
      // and not all mantissa bits (0..51) clear.
      // Read top bits of double representation (second word of value).
      __ ldr(r2, FieldMemOperand(r0, HeapNumber::kExponentOffset));
      // Test that exponent bits are all set.
      __ Sbfx(r3, r2, HeapNumber::kExponentShift, HeapNumber::kExponentBits);
      // NaNs have all-one exponents so they sign extend to -1.
      __ cmp(r3, Operand(-1));
      __ b(ne, &return_equal);
  
      // Shift out flag and all exponent bits, retaining only mantissa.
      __ mov(r2, Operand(r2, LSL, HeapNumber::kNonMantissaBitsInTopWord));
      // Or with all low-bits of mantissa.
      __ ldr(r3, FieldMemOperand(r0, HeapNumber::kMantissaOffset));
      __ orr(r0, r3, Operand(r2), SetCC);
      // For equal we already have the right value in r0:  Return zero (equal)
      // if all bits in mantissa are zero (it's an Infinity) and non-zero if
      // not (it's a NaN).  For <= and >= we need to load r0 with the failing
      // value if it's a NaN.
      if (cond != eq) {
        // All-zero means Infinity means equal.
        __ Ret(eq);
        if (cond == le) {
          __ mov(r0, Operand(GREATER));  // NaN <= NaN should fail.
        } else {
          __ mov(r0, Operand(LESS));     // NaN >= NaN should fail.
        }
      }
      __ Ret();
    }
    // No fall through here.
  
    __ bind(&not_identical);
  }
  
  
  // See comment at call site.
  static void EmitSmiNonsmiComparison(MacroAssembler* masm,
                                      Register lhs,
                                      Register rhs,
                                      Label* lhs_not_nan,
                                      Label* slow,
                                      bool strict) {
    DCHECK((lhs.is(r0) && rhs.is(r1)) ||
           (lhs.is(r1) && rhs.is(r0)));
  
    Label rhs_is_smi;
    __ JumpIfSmi(rhs, &rhs_is_smi);
  
    // Lhs is a Smi.  Check whether the rhs is a heap number.
    __ CompareObjectType(rhs, r4, r4, HEAP_NUMBER_TYPE);
    if (strict) {
      // If rhs is not a number and lhs is a Smi then strict equality cannot
      // succeed.  Return non-equal
      // If rhs is r0 then there is already a non zero value in it.
      if (!rhs.is(r0)) {
        __ mov(r0, Operand(NOT_EQUAL), LeaveCC, ne);
      }
      __ Ret(ne);
    } else {
      // Smi compared non-strictly with a non-Smi non-heap-number.  Call
      // the runtime.
      __ b(ne, slow);
    }
  
    // Lhs is a smi, rhs is a number.
    // Convert lhs to a double in d7.
    __ SmiToDouble(d7, lhs);
    // Load the double from rhs, tagged HeapNumber r0, to d6.
    __ vldr(d6, rhs, HeapNumber::kValueOffset - kHeapObjectTag);
  
    // We now have both loaded as doubles but we can skip the lhs nan check
    // since it's a smi.
    __ jmp(lhs_not_nan);
  
    __ bind(&rhs_is_smi);
    // Rhs is a smi.  Check whether the non-smi lhs is a heap number.
    __ CompareObjectType(lhs, r4, r4, HEAP_NUMBER_TYPE);
    if (strict) {
      // If lhs is not a number and rhs is a smi then strict equality cannot
      // succeed.  Return non-equal.
      // If lhs is r0 then there is already a non zero value in it.
      if (!lhs.is(r0)) {
        __ mov(r0, Operand(NOT_EQUAL), LeaveCC, ne);
      }
      __ Ret(ne);
    } else {
      // Smi compared non-strictly with a non-smi non-heap-number.  Call
      // the runtime.
      __ b(ne, slow);
    }
  
    // Rhs is a smi, lhs is a heap number.
    // Load the double from lhs, tagged HeapNumber r1, to d7.
    __ vldr(d7, lhs, HeapNumber::kValueOffset - kHeapObjectTag);
    // Convert rhs to a double in d6              .
    __ SmiToDouble(d6, rhs);
    // Fall through to both_loaded_as_doubles.
  }
  
  
  // See comment at call site.
  static void EmitStrictTwoHeapObjectCompare(MacroAssembler* masm,
                                             Register lhs,
                                             Register rhs) {
      DCHECK((lhs.is(r0) && rhs.is(r1)) ||
             (lhs.is(r1) && rhs.is(r0)));
  
      // If either operand is a JS object or an oddball value, then they are
      // not equal since their pointers are different.
      // There is no test for undetectability in strict equality.
      STATIC_ASSERT(LAST_TYPE == LAST_SPEC_OBJECT_TYPE);
      Label first_non_object;
      // Get the type of the first operand into r2 and compare it with
      // FIRST_SPEC_OBJECT_TYPE.
      __ CompareObjectType(rhs, r2, r2, FIRST_SPEC_OBJECT_TYPE);
      __ b(lt, &first_non_object);
  
      // Return non-zero (r0 is not zero)
      Label return_not_equal;
      __ bind(&return_not_equal);
      __ Ret();
  
      __ bind(&first_non_object);
      // Check for oddballs: true, false, null, undefined.
      __ cmp(r2, Operand(ODDBALL_TYPE));
      __ b(eq, &return_not_equal);
  
      __ CompareObjectType(lhs, r3, r3, FIRST_SPEC_OBJECT_TYPE);
      __ b(ge, &return_not_equal);
  
      // Check for oddballs: true, false, null, undefined.
      __ cmp(r3, Operand(ODDBALL_TYPE));
      __ b(eq, &return_not_equal);
  
      // Now that we have the types we might as well check for
      // internalized-internalized.
      STATIC_ASSERT(kInternalizedTag == 0 && kStringTag == 0);
      __ orr(r2, r2, Operand(r3));
      __ tst(r2, Operand(kIsNotStringMask | kIsNotInternalizedMask));
      __ b(eq, &return_not_equal);
  }
  
  
  // See comment at call site.
  static void EmitCheckForTwoHeapNumbers(MacroAssembler* masm,
                                         Register lhs,
                                         Register rhs,
                                         Label* both_loaded_as_doubles,
                                         Label* not_heap_numbers,
                                         Label* slow) {
    DCHECK((lhs.is(r0) && rhs.is(r1)) ||
           (lhs.is(r1) && rhs.is(r0)));
  
    __ CompareObjectType(rhs, r3, r2, HEAP_NUMBER_TYPE);
    __ b(ne, not_heap_numbers);
    __ ldr(r2, FieldMemOperand(lhs, HeapObject::kMapOffset));
    __ cmp(r2, r3);
    __ b(ne, slow);  // First was a heap number, second wasn't.  Go slow case.
  
    // Both are heap numbers.  Load them up then jump to the code we have
    // for that.
    __ vldr(d6, rhs, HeapNumber::kValueOffset - kHeapObjectTag);
    __ vldr(d7, lhs, HeapNumber::kValueOffset - kHeapObjectTag);
    __ jmp(both_loaded_as_doubles);
  }
  
  
  // Fast negative check for internalized-to-internalized equality.
  static void EmitCheckForInternalizedStringsOrObjects(MacroAssembler* masm,
                                                       Register lhs,
                                                       Register rhs,
                                                       Label* possible_strings,
                                                       Label* not_both_strings) {
    DCHECK((lhs.is(r0) && rhs.is(r1)) ||
           (lhs.is(r1) && rhs.is(r0)));
  
    // r2 is object type of rhs.
    Label object_test;
    STATIC_ASSERT(kInternalizedTag == 0 && kStringTag == 0);
    __ tst(r2, Operand(kIsNotStringMask));
    __ b(ne, &object_test);
    __ tst(r2, Operand(kIsNotInternalizedMask));
    __ b(ne, possible_strings);
    __ CompareObjectType(lhs, r3, r3, FIRST_NONSTRING_TYPE);
    __ b(ge, not_both_strings);
    __ tst(r3, Operand(kIsNotInternalizedMask));
    __ b(ne, possible_strings);
  
    // Both are internalized.  We already checked they weren't the same pointer
    // so they are not equal.
    __ mov(r0, Operand(NOT_EQUAL));
    __ Ret();
  
    __ bind(&object_test);
    __ cmp(r2, Operand(FIRST_SPEC_OBJECT_TYPE));
    __ b(lt, not_both_strings);
    __ CompareObjectType(lhs, r2, r3, FIRST_SPEC_OBJECT_TYPE);
    __ b(lt, not_both_strings);
    // If both objects are undetectable, they are equal. Otherwise, they
    // are not equal, since they are different objects and an object is not
    // equal to undefined.
    __ ldr(r3, FieldMemOperand(rhs, HeapObject::kMapOffset));
    __ ldrb(r2, FieldMemOperand(r2, Map::kBitFieldOffset));
    __ ldrb(r3, FieldMemOperand(r3, Map::kBitFieldOffset));
    __ and_(r0, r2, Operand(r3));
    __ and_(r0, r0, Operand(1 << Map::kIsUndetectable));
    __ eor(r0, r0, Operand(1 << Map::kIsUndetectable));
    __ Ret();
  }
  
  
  static void CompareICStub_CheckInputType(MacroAssembler* masm, Register input,
                                           Register scratch,
                                           CompareICState::State expected,
                                           Label* fail) {
    Label ok;
    if (expected == CompareICState::SMI) {
      __ JumpIfNotSmi(input, fail);
    } else if (expected == CompareICState::NUMBER) {
      __ JumpIfSmi(input, &ok);
      __ CheckMap(input, scratch, Heap::kHeapNumberMapRootIndex, fail,
                  DONT_DO_SMI_CHECK);
    }
    // We could be strict about internalized/non-internalized here, but as long as
    // hydrogen doesn't care, the stub doesn't have to care either.
    __ bind(&ok);
  }
  
  
  // On entry r1 and r2 are the values to be compared.
  // On exit r0 is 0, positive or negative to indicate the result of
  // the comparison.
  void CompareICStub::GenerateGeneric(MacroAssembler* masm) {
    Register lhs = r1;
    Register rhs = r0;
    Condition cc = GetCondition();
  
    Label miss;
    CompareICStub_CheckInputType(masm, lhs, r2, left(), &miss);
    CompareICStub_CheckInputType(masm, rhs, r3, right(), &miss);
  
    Label slow;  // Call builtin.
    Label not_smis, both_loaded_as_doubles, lhs_not_nan;
  
    Label not_two_smis, smi_done;
    __ orr(r2, r1, r0);
    __ JumpIfNotSmi(r2, &not_two_smis);
    __ mov(r1, Operand(r1, ASR, 1));
    __ sub(r0, r1, Operand(r0, ASR, 1));
    __ Ret();
    __ bind(&not_two_smis);
  
    // NOTICE! This code is only reached after a smi-fast-case check, so
    // it is certain that at least one operand isn't a smi.
  
    // Handle the case where the objects are identical.  Either returns the answer
    // or goes to slow.  Only falls through if the objects were not identical.
    EmitIdenticalObjectComparison(masm, &slow, cc);
  
    // If either is a Smi (we know that not both are), then they can only
    // be strictly equal if the other is a HeapNumber.
    STATIC_ASSERT(kSmiTag == 0);
    DCHECK_EQ(0, Smi::FromInt(0));
    __ and_(r2, lhs, Operand(rhs));
    __ JumpIfNotSmi(r2, &not_smis);
    // One operand is a smi.  EmitSmiNonsmiComparison generates code that can:
    // 1) Return the answer.
    // 2) Go to slow.
    // 3) Fall through to both_loaded_as_doubles.
    // 4) Jump to lhs_not_nan.
    // In cases 3 and 4 we have found out we were dealing with a number-number
    // comparison.  If VFP3 is supported the double values of the numbers have
    // been loaded into d7 and d6.  Otherwise, the double values have been loaded
    // into r0, r1, r2, and r3.
    EmitSmiNonsmiComparison(masm, lhs, rhs, &lhs_not_nan, &slow, strict());
  
    __ bind(&both_loaded_as_doubles);
    // The arguments have been converted to doubles and stored in d6 and d7, if
    // VFP3 is supported, or in r0, r1, r2, and r3.
    __ bind(&lhs_not_nan);
    Label no_nan;
    // ARMv7 VFP3 instructions to implement double precision comparison.
    __ VFPCompareAndSetFlags(d7, d6);
    Label nan;
    __ b(vs, &nan);
    __ mov(r0, Operand(EQUAL), LeaveCC, eq);
    __ mov(r0, Operand(LESS), LeaveCC, lt);
    __ mov(r0, Operand(GREATER), LeaveCC, gt);
    __ Ret();
  
    __ bind(&nan);
    // If one of the sides was a NaN then the v flag is set.  Load r0 with
    // whatever it takes to make the comparison fail, since comparisons with NaN
    // always fail.
    if (cc == lt || cc == le) {
      __ mov(r0, Operand(GREATER));
    } else {
      __ mov(r0, Operand(LESS));
    }
    __ Ret();
  
    __ bind(&not_smis);
    // At this point we know we are dealing with two different objects,
    // and neither of them is a Smi.  The objects are in rhs_ and lhs_.
    if (strict()) {
      // This returns non-equal for some object types, or falls through if it
      // was not lucky.
      EmitStrictTwoHeapObjectCompare(masm, lhs, rhs);
    }
  
    Label check_for_internalized_strings;
    Label flat_string_check;
    // Check for heap-number-heap-number comparison.  Can jump to slow case,
    // or load both doubles into r0, r1, r2, r3 and jump to the code that handles
    // that case.  If the inputs are not doubles then jumps to
    // check_for_internalized_strings.
    // In this case r2 will contain the type of rhs_.  Never falls through.
    EmitCheckForTwoHeapNumbers(masm,
                               lhs,
                               rhs,
                               &both_loaded_as_doubles,
                               &check_for_internalized_strings,
                               &flat_string_check);
  
    __ bind(&check_for_internalized_strings);
    // In the strict case the EmitStrictTwoHeapObjectCompare already took care of
    // internalized strings.
    if (cc == eq && !strict()) {
      // Returns an answer for two internalized strings or two detectable objects.
      // Otherwise jumps to string case or not both strings case.
      // Assumes that r2 is the type of rhs_ on entry.
      EmitCheckForInternalizedStringsOrObjects(
          masm, lhs, rhs, &flat_string_check, &slow);
    }
  
    // Check for both being sequential one-byte strings,
    // and inline if that is the case.
    __ bind(&flat_string_check);
  
    __ JumpIfNonSmisNotBothSequentialOneByteStrings(lhs, rhs, r2, r3, &slow);
  
    __ IncrementCounter(isolate()->counters()->string_compare_native(), 1, r2,
                        r3);
    if (cc == eq) {
      StringHelper::GenerateFlatOneByteStringEquals(masm, lhs, rhs, r2, r3, r4);
    } else {
      StringHelper::GenerateCompareFlatOneByteStrings(masm, lhs, rhs, r2, r3, r4,
                                                      r5);
    }
    // Never falls through to here.
  
    __ bind(&slow);
  
    __ Push(lhs, rhs);
    // Figure out which native to call and setup the arguments.
    Builtins::JavaScript native;
    if (cc == eq) {
      native = strict() ? Builtins::STRICT_EQUALS : Builtins::EQUALS;
    } else {
      native = Builtins::COMPARE;
      int ncr;  // NaN compare result
      if (cc == lt || cc == le) {
        ncr = GREATER;
      } else {
        DCHECK(cc == gt || cc == ge);  // remaining cases
        ncr = LESS;
      }
      __ mov(r0, Operand(Smi::FromInt(ncr)));
      __ push(r0);
    }
  
    // Call the native; it returns -1 (less), 0 (equal), or 1 (greater)
    // tagged as a small integer.
    __ InvokeBuiltin(native, JUMP_FUNCTION);
  
    __ bind(&miss);
    GenerateMiss(masm);
  }
  
  
  void StoreBufferOverflowStub::Generate(MacroAssembler* masm) {
    // We don't allow a GC during a store buffer overflow so there is no need to
    // store the registers in any particular way, but we do have to store and
    // restore them.
    __ stm(db_w, sp, kCallerSaved | lr.bit());
  
    const Register scratch = r1;
  
    if (save_doubles()) {
      __ SaveFPRegs(sp, scratch);
    }
    const int argument_count = 1;
    const int fp_argument_count = 0;
  
    AllowExternalCallThatCantCauseGC scope(masm);
    __ PrepareCallCFunction(argument_count, fp_argument_count, scratch);
    __ mov(r0, Operand(ExternalReference::isolate_address(isolate())));
    __ CallCFunction(
        ExternalReference::store_buffer_overflow_function(isolate()),
        argument_count);
    if (save_doubles()) {
      __ RestoreFPRegs(sp, scratch);
    }
    __ ldm(ia_w, sp, kCallerSaved | pc.bit());  // Also pop pc to get Ret(0).
  }
  
  
  void MathPowStub::Generate(MacroAssembler* masm) {
    const Register base = r1;
    const Register exponent = MathPowTaggedDescriptor::exponent();
    DCHECK(exponent.is(r2));
    const Register heapnumbermap = r5;
    const Register heapnumber = r0;
    const DwVfpRegister double_base = d0;
    const DwVfpRegister double_exponent = d1;
    const DwVfpRegister double_result = d2;
    const DwVfpRegister double_scratch = d3;
    const SwVfpRegister single_scratch = s6;
    const Register scratch = r9;
    const Register scratch2 = r4;
  
    Label call_runtime, done, int_exponent;
    if (exponent_type() == ON_STACK) {
      Label base_is_smi, unpack_exponent;
      // The exponent and base are supplied as arguments on the stack.
      // This can only happen if the stub is called from non-optimized code.
      // Load input parameters from stack to double registers.
      __ ldr(base, MemOperand(sp, 1 * kPointerSize));
      __ ldr(exponent, MemOperand(sp, 0 * kPointerSize));
  
      __ LoadRoot(heapnumbermap, Heap::kHeapNumberMapRootIndex);
  
      __ UntagAndJumpIfSmi(scratch, base, &base_is_smi);
      __ ldr(scratch, FieldMemOperand(base, JSObject::kMapOffset));
      __ cmp(scratch, heapnumbermap);
      __ b(ne, &call_runtime);
  
      __ vldr(double_base, FieldMemOperand(base, HeapNumber::kValueOffset));
      __ jmp(&unpack_exponent);
  
      __ bind(&base_is_smi);
      __ vmov(single_scratch, scratch);
      __ vcvt_f64_s32(double_base, single_scratch);
      __ bind(&unpack_exponent);
  
      __ UntagAndJumpIfSmi(scratch, exponent, &int_exponent);
  
      __ ldr(scratch, FieldMemOperand(exponent, JSObject::kMapOffset));
      __ cmp(scratch, heapnumbermap);
      __ b(ne, &call_runtime);
      __ vldr(double_exponent,
              FieldMemOperand(exponent, HeapNumber::kValueOffset));
    } else if (exponent_type() == TAGGED) {
      // Base is already in double_base.
      __ UntagAndJumpIfSmi(scratch, exponent, &int_exponent);
  
      __ vldr(double_exponent,
              FieldMemOperand(exponent, HeapNumber::kValueOffset));
    }
  
    if (exponent_type() != INTEGER) {
      Label int_exponent_convert;
      // Detect integer exponents stored as double.
      __ vcvt_u32_f64(single_scratch, double_exponent);
      // We do not check for NaN or Infinity here because comparing numbers on
      // ARM correctly distinguishes NaNs.  We end up calling the built-in.
      __ vcvt_f64_u32(double_scratch, single_scratch);
      __ VFPCompareAndSetFlags(double_scratch, double_exponent);
      __ b(eq, &int_exponent_convert);
  
      if (exponent_type() == ON_STACK) {
        // Detect square root case.  Crankshaft detects constant +/-0.5 at
        // compile time and uses DoMathPowHalf instead.  We then skip this check
        // for non-constant cases of +/-0.5 as these hardly occur.
        Label not_plus_half;
  
        // Test for 0.5.
        __ vmov(double_scratch, 0.5, scratch);
        __ VFPCompareAndSetFlags(double_exponent, double_scratch);
        __ b(ne, &not_plus_half);
  
        // Calculates square root of base.  Check for the special case of
        // Math.pow(-Infinity, 0.5) == Infinity (ECMA spec, 15.8.2.13).
        __ vmov(double_scratch, -V8_INFINITY, scratch);
        __ VFPCompareAndSetFlags(double_base, double_scratch);
        __ vneg(double_result, double_scratch, eq);
        __ b(eq, &done);
  
        // Add +0 to convert -0 to +0.
        __ vadd(double_scratch, double_base, kDoubleRegZero);
        __ vsqrt(double_result, double_scratch);
        __ jmp(&done);
  
        __ bind(&not_plus_half);
        __ vmov(double_scratch, -0.5, scratch);
        __ VFPCompareAndSetFlags(double_exponent, double_scratch);
        __ b(ne, &call_runtime);
  
        // Calculates square root of base.  Check for the special case of
        // Math.pow(-Infinity, -0.5) == 0 (ECMA spec, 15.8.2.13).
        __ vmov(double_scratch, -V8_INFINITY, scratch);
        __ VFPCompareAndSetFlags(double_base, double_scratch);
        __ vmov(double_result, kDoubleRegZero, eq);
        __ b(eq, &done);
  
        // Add +0 to convert -0 to +0.
        __ vadd(double_scratch, double_base, kDoubleRegZero);
        __ vmov(double_result, 1.0, scratch);
        __ vsqrt(double_scratch, double_scratch);
        __ vdiv(double_result, double_result, double_scratch);
        __ jmp(&done);
      }
  
      __ push(lr);
      {
        AllowExternalCallThatCantCauseGC scope(masm);
        __ PrepareCallCFunction(0, 2, scratch);
        __ MovToFloatParameters(double_base, double_exponent);
        __ CallCFunction(
            ExternalReference::power_double_double_function(isolate()),
            0, 2);
      }
      __ pop(lr);
      __ MovFromFloatResult(double_result);
      __ jmp(&done);
  
      __ bind(&int_exponent_convert);
      __ vcvt_u32_f64(single_scratch, double_exponent);
      __ vmov(scratch, single_scratch);
    }
  
    // Calculate power with integer exponent.
    __ bind(&int_exponent);
  
    // Get two copies of exponent in the registers scratch and exponent.
    if (exponent_type() == INTEGER) {
      __ mov(scratch, exponent);
    } else {
      // Exponent has previously been stored into scratch as untagged integer.
      __ mov(exponent, scratch);
    }
    __ vmov(double_scratch, double_base);  // Back up base.
    __ vmov(double_result, 1.0, scratch2);
  
    // Get absolute value of exponent.
    __ cmp(scratch, Operand::Zero());
    __ mov(scratch2, Operand::Zero(), LeaveCC, mi);
    __ sub(scratch, scratch2, scratch, LeaveCC, mi);
  
    Label while_true;
    __ bind(&while_true);
    __ mov(scratch, Operand(scratch, ASR, 1), SetCC);
    __ vmul(double_result, double_result, double_scratch, cs);
    __ vmul(double_scratch, double_scratch, double_scratch, ne);
    __ b(ne, &while_true);
  
    __ cmp(exponent, Operand::Zero());
    __ b(ge, &done);
    __ vmov(double_scratch, 1.0, scratch);
    __ vdiv(double_result, double_scratch, double_result);
    // Test whether result is zero.  Bail out to check for subnormal result.
    // Due to subnormals, x^-y == (1/x)^y does not hold in all cases.
    __ VFPCompareAndSetFlags(double_result, 0.0);
    __ b(ne, &done);
    // double_exponent may not containe the exponent value if the input was a
    // smi.  We set it with exponent value before bailing out.
    __ vmov(single_scratch, exponent);
    __ vcvt_f64_s32(double_exponent, single_scratch);
  
    // Returning or bailing out.
    Counters* counters = isolate()->counters();
    if (exponent_type() == ON_STACK) {
      // The arguments are still on the stack.
      __ bind(&call_runtime);
      __ TailCallRuntime(Runtime::kMathPowRT, 2, 1);
  
      // The stub is called from non-optimized code, which expects the result
      // as heap number in exponent.
      __ bind(&done);
      __ AllocateHeapNumber(
          heapnumber, scratch, scratch2, heapnumbermap, &call_runtime);
      __ vstr(double_result,
              FieldMemOperand(heapnumber, HeapNumber::kValueOffset));
      DCHECK(heapnumber.is(r0));
      __ IncrementCounter(counters->math_pow(), 1, scratch, scratch2);
      __ Ret(2);
    } else {
      __ push(lr);
      {
        AllowExternalCallThatCantCauseGC scope(masm);
        __ PrepareCallCFunction(0, 2, scratch);
        __ MovToFloatParameters(double_base, double_exponent);
        __ CallCFunction(
            ExternalReference::power_double_double_function(isolate()),
            0, 2);
      }
      __ pop(lr);
      __ MovFromFloatResult(double_result);
  
      __ bind(&done);
      __ IncrementCounter(counters->math_pow(), 1, scratch, scratch2);
      __ Ret();
    }
  }
  
  
  bool CEntryStub::NeedsImmovableCode() {
    return true;
  }
  
  
  void CodeStub::GenerateStubsAheadOfTime(Isolate* isolate) {
    CEntryStub::GenerateAheadOfTime(isolate);
    WriteInt32ToHeapNumberStub::GenerateFixedRegStubsAheadOfTime(isolate);
    StoreBufferOverflowStub::GenerateFixedRegStubsAheadOfTime(isolate);
    StubFailureTrampolineStub::GenerateAheadOfTime(isolate);
    ArrayConstructorStubBase::GenerateStubsAheadOfTime(isolate);
    CreateAllocationSiteStub::GenerateAheadOfTime(isolate);
    BinaryOpICStub::GenerateAheadOfTime(isolate);
    BinaryOpICWithAllocationSiteStub::GenerateAheadOfTime(isolate);
  }
  
  
  void CodeStub::GenerateFPStubs(Isolate* isolate) {
    // Generate if not already in cache.
    SaveFPRegsMode mode = kSaveFPRegs;
    CEntryStub(isolate, 1, mode).GetCode();
    StoreBufferOverflowStub(isolate, mode).GetCode();
    isolate->set_fp_stubs_generated(true);
  }
  
  
  void CEntryStub::GenerateAheadOfTime(Isolate* isolate) {
    CEntryStub stub(isolate, 1, kDontSaveFPRegs);
    stub.GetCode();
  }
  
  
  void CEntryStub::Generate(MacroAssembler* masm) {
    // Called from JavaScript; parameters are on stack as if calling JS function.
    // r0: number of arguments including receiver
    // r1: pointer to builtin function
    // fp: frame pointer  (restored after C call)
    // sp: stack pointer  (restored as callee's sp after C call)
    // cp: current context  (C callee-saved)
  
    ProfileEntryHookStub::MaybeCallEntryHook(masm);
  
    __ mov(r5, Operand(r1));
  
    // Compute the argv pointer in a callee-saved register.
    __ add(r1, sp, Operand(r0, LSL, kPointerSizeLog2));
    __ sub(r1, r1, Operand(kPointerSize));
  
    // Enter the exit frame that transitions from JavaScript to C++.
    FrameScope scope(masm, StackFrame::MANUAL);
    __ EnterExitFrame(save_doubles());
  
    // Store a copy of argc in callee-saved registers for later.
    __ mov(r4, Operand(r0));
  
    // r0, r4: number of arguments including receiver  (C callee-saved)
    // r1: pointer to the first argument (C callee-saved)
    // r5: pointer to builtin function  (C callee-saved)
  
    // Result returned in r0 or r0+r1 by default.
  
  #if V8_HOST_ARCH_ARM
    int frame_alignment = MacroAssembler::ActivationFrameAlignment();
    int frame_alignment_mask = frame_alignment - 1;
    if (FLAG_debug_code) {
      if (frame_alignment > kPointerSize) {
        Label alignment_as_expected;
        DCHECK(base::bits::IsPowerOfTwo32(frame_alignment));
        __ tst(sp, Operand(frame_alignment_mask));
        __ b(eq, &alignment_as_expected);
        // Don't use Check here, as it will call Runtime_Abort re-entering here.
        __ stop("Unexpected alignment");
        __ bind(&alignment_as_expected);
      }
    }
  #endif
  
    // Call C built-in.
    // r0 = argc, r1 = argv
    __ mov(r2, Operand(ExternalReference::isolate_address(isolate())));
  
    // To let the GC traverse the return address of the exit frames, we need to
    // know where the return address is. The CEntryStub is unmovable, so
    // we can store the address on the stack to be able to find it again and
    // we never have to restore it, because it will not change.
    // Compute the return address in lr to return to after the jump below. Pc is
    // already at '+ 8' from the current instruction but return is after three
    // instructions so add another 4 to pc to get the return address.
    {
      // Prevent literal pool emission before return address.
      Assembler::BlockConstPoolScope block_const_pool(masm);
      __ add(lr, pc, Operand(4));
      __ str(lr, MemOperand(sp, 0));
      __ Call(r5);
    }
  
    __ VFPEnsureFPSCRState(r2);
  
    // Runtime functions should not return 'the hole'.  Allowing it to escape may
    // lead to crashes in the IC code later.
    if (FLAG_debug_code) {
      Label okay;
      __ CompareRoot(r0, Heap::kTheHoleValueRootIndex);
      __ b(ne, &okay);
      __ stop("The hole escaped");
      __ bind(&okay);
    }
  
    // Check result for exception sentinel.
    Label exception_returned;
    __ CompareRoot(r0, Heap::kExceptionRootIndex);
    __ b(eq, &exception_returned);
  
    ExternalReference pending_exception_address(
        Isolate::kPendingExceptionAddress, isolate());
  
    // Check that there is no pending exception, otherwise we
    // should have returned the exception sentinel.
    if (FLAG_debug_code) {
      Label okay;
      __ mov(r2, Operand(pending_exception_address));
      __ ldr(r2, MemOperand(r2));
      __ CompareRoot(r2, Heap::kTheHoleValueRootIndex);
      // Cannot use check here as it attempts to generate call into runtime.
      __ b(eq, &okay);
      __ stop("Unexpected pending exception");
      __ bind(&okay);
    }
  
    // Exit C frame and return.
    // r0:r1: result
    // sp: stack pointer
    // fp: frame pointer
    // Callee-saved register r4 still holds argc.
    __ LeaveExitFrame(save_doubles(), r4, true);
    __ mov(pc, lr);
  
    // Handling of exception.
    __ bind(&exception_returned);
  
    // Retrieve the pending exception.
    __ mov(r2, Operand(pending_exception_address));
    __ ldr(r0, MemOperand(r2));
  
    // Clear the pending exception.
    __ LoadRoot(r3, Heap::kTheHoleValueRootIndex);
    __ str(r3, MemOperand(r2));
  
    // Special handling of termination exceptions which are uncatchable
    // by javascript code.
    Label throw_termination_exception;
    __ CompareRoot(r0, Heap::kTerminationExceptionRootIndex);
    __ b(eq, &throw_termination_exception);
  
    // Handle normal exception.
    __ Throw(r0);
  
    __ bind(&throw_termination_exception);
    __ ThrowUncatchable(r0);
  }
  
  
  void JSEntryStub::Generate(MacroAssembler* masm) {
    // r0: code entry
    // r1: function
    // r2: receiver
    // r3: argc
    // [sp+0]: argv
  
    Label invoke, handler_entry, exit;
  
    ProfileEntryHookStub::MaybeCallEntryHook(masm);
  
    // Called from C, so do not pop argc and args on exit (preserve sp)
    // No need to save register-passed args
    // Save callee-saved registers (incl. cp and fp), sp, and lr
    __ stm(db_w, sp, kCalleeSaved | lr.bit());
  
    // Save callee-saved vfp registers.
    __ vstm(db_w, sp, kFirstCalleeSavedDoubleReg, kLastCalleeSavedDoubleReg);
    // Set up the reserved register for 0.0.
    __ vmov(kDoubleRegZero, 0.0);
    __ VFPEnsureFPSCRState(r4);
  
    // Get address of argv, see stm above.
    // r0: code entry
    // r1: function
    // r2: receiver
    // r3: argc
  
    // Set up argv in r4.
    int offset_to_argv = (kNumCalleeSaved + 1) * kPointerSize;
    offset_to_argv += kNumDoubleCalleeSaved * kDoubleSize;
    __ ldr(r4, MemOperand(sp, offset_to_argv));
  
    // Push a frame with special values setup to mark it as an entry frame.
    // r0: code entry
    // r1: function
    // r2: receiver
    // r3: argc
    // r4: argv
    int marker = type();
    if (FLAG_enable_ool_constant_pool) {
      __ mov(r8, Operand(isolate()->factory()->empty_constant_pool_array()));
    }
    __ mov(r7, Operand(Smi::FromInt(marker)));
    __ mov(r6, Operand(Smi::FromInt(marker)));
    __ mov(r5,
           Operand(ExternalReference(Isolate::kCEntryFPAddress, isolate())));
    __ ldr(r5, MemOperand(r5));
    __ mov(ip, Operand(-1));  // Push a bad frame pointer to fail if it is used.
    __ stm(db_w, sp, r5.bit() | r6.bit() | r7.bit() |
                     (FLAG_enable_ool_constant_pool ? r8.bit() : 0) |
                     ip.bit());
  
    // Set up frame pointer for the frame to be pushed.
    __ add(fp, sp, Operand(-EntryFrameConstants::kCallerFPOffset));
  
    // If this is the outermost JS call, set js_entry_sp value.
    Label non_outermost_js;
    ExternalReference js_entry_sp(Isolate::kJSEntrySPAddress, isolate());
    __ mov(r5, Operand(ExternalReference(js_entry_sp)));
    __ ldr(r6, MemOperand(r5));
    __ cmp(r6, Operand::Zero());
    __ b(ne, &non_outermost_js);
    __ str(fp, MemOperand(r5));
    __ mov(ip, Operand(Smi::FromInt(StackFrame::OUTERMOST_JSENTRY_FRAME)));
    Label cont;
    __ b(&cont);
    __ bind(&non_outermost_js);
    __ mov(ip, Operand(Smi::FromInt(StackFrame::INNER_JSENTRY_FRAME)));
    __ bind(&cont);
    __ push(ip);
  
    // Jump to a faked try block that does the invoke, with a faked catch
    // block that sets the pending exception.
    __ jmp(&invoke);
  
    // Block literal pool emission whilst taking the position of the handler
    // entry. This avoids making the assumption that literal pools are always
    // emitted after an instruction is emitted, rather than before.
    {
      Assembler::BlockConstPoolScope block_const_pool(masm);
      __ bind(&handler_entry);
      handler_offset_ = handler_entry.pos();
      // Caught exception: Store result (exception) in the pending exception
      // field in the JSEnv and return a failure sentinel.  Coming in here the
      // fp will be invalid because the PushTryHandler below sets it to 0 to
      // signal the existence of the JSEntry frame.
      __ mov(ip, Operand(ExternalReference(Isolate::kPendingExceptionAddress,
                                           isolate())));
    }
    __ str(r0, MemOperand(ip));
    __ LoadRoot(r0, Heap::kExceptionRootIndex);
    __ b(&exit);
  
    // Invoke: Link this frame into the handler chain.  There's only one
    // handler block in this code object, so its index is 0.
    __ bind(&invoke);
    // Must preserve r0-r4, r5-r6 are available.
    __ PushTryHandler(StackHandler::JS_ENTRY, 0);
    // If an exception not caught by another handler occurs, this handler
    // returns control to the code after the bl(&invoke) above, which
    // restores all kCalleeSaved registers (including cp and fp) to their
    // saved values before returning a failure to C.
  
    // Clear any pending exceptions.
    __ mov(r5, Operand(isolate()->factory()->the_hole_value()));
    __ mov(ip, Operand(ExternalReference(Isolate::kPendingExceptionAddress,
                                         isolate())));
    __ str(r5, MemOperand(ip));
  
    // Invoke the function by calling through JS entry trampoline builtin.
    // Notice that we cannot store a reference to the trampoline code directly in
    // this stub, because runtime stubs are not traversed when doing GC.
  
    // Expected registers by Builtins::JSEntryTrampoline
    // r0: code entry
    // r1: function
    // r2: receiver
    // r3: argc
    // r4: argv
    if (type() == StackFrame::ENTRY_CONSTRUCT) {
      ExternalReference construct_entry(Builtins::kJSConstructEntryTrampoline,
                                        isolate());
      __ mov(ip, Operand(construct_entry));
    } else {
      ExternalReference entry(Builtins::kJSEntryTrampoline, isolate());
      __ mov(ip, Operand(entry));
    }
    __ ldr(ip, MemOperand(ip));  // deref address
    __ add(ip, ip, Operand(Code::kHeaderSize - kHeapObjectTag));
  
    // Branch and link to JSEntryTrampoline.
    __ Call(ip);
  
    // Unlink this frame from the handler chain.
    __ PopTryHandler();
  
    __ bind(&exit);  // r0 holds result
    // Check if the current stack frame is marked as the outermost JS frame.
    Label non_outermost_js_2;
    __ pop(r5);
    __ cmp(r5, Operand(Smi::FromInt(StackFrame::OUTERMOST_JSENTRY_FRAME)));
    __ b(ne, &non_outermost_js_2);
    __ mov(r6, Operand::Zero());
    __ mov(r5, Operand(ExternalReference(js_entry_sp)));
    __ str(r6, MemOperand(r5));
    __ bind(&non_outermost_js_2);
  
    // Restore the top frame descriptors from the stack.
    __ pop(r3);
    __ mov(ip,
           Operand(ExternalReference(Isolate::kCEntryFPAddress, isolate())));
    __ str(r3, MemOperand(ip));
  
    // Reset the stack to the callee saved registers.
    __ add(sp, sp, Operand(-EntryFrameConstants::kCallerFPOffset));
  
    // Restore callee-saved registers and return.
  #ifdef DEBUG
    if (FLAG_debug_code) {
      __ mov(lr, Operand(pc));
    }
  #endif
  
    // Restore callee-saved vfp registers.
    __ vldm(ia_w, sp, kFirstCalleeSavedDoubleReg, kLastCalleeSavedDoubleReg);
  
    __ ldm(ia_w, sp, kCalleeSaved | pc.bit());
  }
  
  
  // Uses registers r0 to r4.
  // Expected input (depending on whether args are in registers or on the stack):
  // * object: r0 or at sp + 1 * kPointerSize.
  // * function: r1 or at sp.
  //
  // An inlined call site may have been generated before calling this stub.
  // In this case the offset to the inline sites to patch are passed in r5 and r6.
  // (See LCodeGen::DoInstanceOfKnownGlobal)
  void InstanceofStub::Generate(MacroAssembler* masm) {
    // Call site inlining and patching implies arguments in registers.
    DCHECK(HasArgsInRegisters() || !HasCallSiteInlineCheck());
  
    // Fixed register usage throughout the stub:
    const Register object = r0;  // Object (lhs).
    Register map = r3;  // Map of the object.
    const Register function = r1;  // Function (rhs).
    const Register prototype = r4;  // Prototype of the function.
    const Register scratch = r2;
  
    Label slow, loop, is_instance, is_not_instance, not_js_object;
  
    if (!HasArgsInRegisters()) {
      __ ldr(object, MemOperand(sp, 1 * kPointerSize));
      __ ldr(function, MemOperand(sp, 0));
    }
  
    // Check that the left hand is a JS object and load map.
    __ JumpIfSmi(object, &not_js_object);
    __ IsObjectJSObjectType(object, map, scratch, &not_js_object);
  
    // If there is a call site cache don't look in the global cache, but do the
    // real lookup and update the call site cache.
    if (!HasCallSiteInlineCheck() && !ReturnTrueFalseObject()) {
      Label miss;
      __ CompareRoot(function, Heap::kInstanceofCacheFunctionRootIndex);
      __ b(ne, &miss);
      __ CompareRoot(map, Heap::kInstanceofCacheMapRootIndex);
      __ b(ne, &miss);
      __ LoadRoot(r0, Heap::kInstanceofCacheAnswerRootIndex);
      __ Ret(HasArgsInRegisters() ? 0 : 2);
  
      __ bind(&miss);
    }
  
    // Get the prototype of the function.
    __ TryGetFunctionPrototype(function, prototype, scratch, &slow, true);
  
    // Check that the function prototype is a JS object.
    __ JumpIfSmi(prototype, &slow);
    __ IsObjectJSObjectType(prototype, scratch, scratch, &slow);
  
    // Update the global instanceof or call site inlined cache with the current
    // map and function. The cached answer will be set when it is known below.
    if (!HasCallSiteInlineCheck()) {
      __ StoreRoot(function, Heap::kInstanceofCacheFunctionRootIndex);
      __ StoreRoot(map, Heap::kInstanceofCacheMapRootIndex);
    } else {
      DCHECK(HasArgsInRegisters());
      // Patch the (relocated) inlined map check.
  
      // The map_load_offset was stored in r5
      //   (See LCodeGen::DoDeferredLInstanceOfKnownGlobal).
      const Register map_load_offset = r5;
      __ sub(r9, lr, map_load_offset);
      // Get the map location in r5 and patch it.
      __ GetRelocatedValueLocation(r9, map_load_offset, scratch);
      __ ldr(map_load_offset, MemOperand(map_load_offset));
      __ str(map, FieldMemOperand(map_load_offset, Cell::kValueOffset));
    }
  
    // Register mapping: r3 is object map and r4 is function prototype.
    // Get prototype of object into r2.
    __ ldr(scratch, FieldMemOperand(map, Map::kPrototypeOffset));
  
    // We don't need map any more. Use it as a scratch register.
    Register scratch2 = map;
    map = no_reg;
  
    // Loop through the prototype chain looking for the function prototype.
    __ LoadRoot(scratch2, Heap::kNullValueRootIndex);
    __ bind(&loop);
    __ cmp(scratch, Operand(prototype));
    __ b(eq, &is_instance);
    __ cmp(scratch, scratch2);
    __ b(eq, &is_not_instance);
    __ ldr(scratch, FieldMemOperand(scratch, HeapObject::kMapOffset));
    __ ldr(scratch, FieldMemOperand(scratch, Map::kPrototypeOffset));
    __ jmp(&loop);
    Factory* factory = isolate()->factory();
  
    __ bind(&is_instance);
    if (!HasCallSiteInlineCheck()) {
      __ mov(r0, Operand(Smi::FromInt(0)));
      __ StoreRoot(r0, Heap::kInstanceofCacheAnswerRootIndex);
      if (ReturnTrueFalseObject()) {
        __ Move(r0, factory->true_value());
      }
    } else {
      // Patch the call site to return true.
      __ LoadRoot(r0, Heap::kTrueValueRootIndex);
      // The bool_load_offset was stored in r6
      //   (See LCodeGen::DoDeferredLInstanceOfKnownGlobal).
      const Register bool_load_offset = r6;
      __ sub(r9, lr, bool_load_offset);
      // Get the boolean result location in scratch and patch it.
      __ GetRelocatedValueLocation(r9, scratch, scratch2);
      __ str(r0, MemOperand(scratch));
  
      if (!ReturnTrueFalseObject()) {
        __ mov(r0, Operand(Smi::FromInt(0)));
      }
    }
    __ Ret(HasArgsInRegisters() ? 0 : 2);
  
    __ bind(&is_not_instance);
    if (!HasCallSiteInlineCheck()) {
      __ mov(r0, Operand(Smi::FromInt(1)));
      __ StoreRoot(r0, Heap::kInstanceofCacheAnswerRootIndex);
      if (ReturnTrueFalseObject()) {
        __ Move(r0, factory->false_value());
      }
    } else {
      // Patch the call site to return false.
      __ LoadRoot(r0, Heap::kFalseValueRootIndex);
      // The bool_load_offset was stored in r6
      //   (See LCodeGen::DoDeferredLInstanceOfKnownGlobal).
      const Register bool_load_offset = r6;
      __ sub(r9, lr, bool_load_offset);
      ;
      // Get the boolean result location in scratch and patch it.
      __ GetRelocatedValueLocation(r9, scratch, scratch2);
      __ str(r0, MemOperand(scratch));
  
      if (!ReturnTrueFalseObject()) {
        __ mov(r0, Operand(Smi::FromInt(1)));
      }
    }
    __ Ret(HasArgsInRegisters() ? 0 : 2);
  
    Label object_not_null, object_not_null_or_smi;
    __ bind(&not_js_object);
    // Before null, smi and string value checks, check that the rhs is a function
    // as for a non-function rhs an exception needs to be thrown.
    __ JumpIfSmi(function, &slow);
    __ CompareObjectType(function, scratch2, scratch, JS_FUNCTION_TYPE);
    __ b(ne, &slow);
  
    // Null is not instance of anything.
    __ cmp(scratch, Operand(isolate()->factory()->null_value()));
    __ b(ne, &object_not_null);
    if (ReturnTrueFalseObject()) {
      __ Move(r0, factory->false_value());
    } else {
      __ mov(r0, Operand(Smi::FromInt(1)));
    }
    __ Ret(HasArgsInRegisters() ? 0 : 2);
  
    __ bind(&object_not_null);
    // Smi values are not instances of anything.
    __ JumpIfNotSmi(object, &object_not_null_or_smi);
    if (ReturnTrueFalseObject()) {
      __ Move(r0, factory->false_value());
    } else {
      __ mov(r0, Operand(Smi::FromInt(1)));
    }
    __ Ret(HasArgsInRegisters() ? 0 : 2);
  
    __ bind(&object_not_null_or_smi);
    // String values are not instances of anything.
    __ IsObjectJSStringType(object, scratch, &slow);
    if (ReturnTrueFalseObject()) {
      __ Move(r0, factory->false_value());
    } else {
      __ mov(r0, Operand(Smi::FromInt(1)));
    }
    __ Ret(HasArgsInRegisters() ? 0 : 2);
  
    // Slow-case.  Tail call builtin.
    __ bind(&slow);
    if (!ReturnTrueFalseObject()) {
      if (HasArgsInRegisters()) {
        __ Push(r0, r1);
      }
    __ InvokeBuiltin(Builtins::INSTANCE_OF, JUMP_FUNCTION);
    } else {
      {
        FrameAndConstantPoolScope scope(masm, StackFrame::INTERNAL);
        __ Push(r0, r1);
        __ InvokeBuiltin(Builtins::INSTANCE_OF, CALL_FUNCTION);
      }
      __ cmp(r0, Operand::Zero());
      __ LoadRoot(r0, Heap::kTrueValueRootIndex, eq);
      __ LoadRoot(r0, Heap::kFalseValueRootIndex, ne);
      __ Ret(HasArgsInRegisters() ? 0 : 2);
    }
  }
  
  
  void FunctionPrototypeStub::Generate(MacroAssembler* masm) {
    Label miss;
    Register receiver = LoadDescriptor::ReceiverRegister();
  
    NamedLoadHandlerCompiler::GenerateLoadFunctionPrototype(masm, receiver, r3,
                                                            r4, &miss);
    __ bind(&miss);
    PropertyAccessCompiler::TailCallBuiltin(
        masm, PropertyAccessCompiler::MissBuiltin(Code::LOAD_IC));
  }
  
  
  void ArgumentsAccessStub::GenerateReadElement(MacroAssembler* masm) {
    // The displacement is the offset of the last parameter (if any)
    // relative to the frame pointer.
    const int kDisplacement =
        StandardFrameConstants::kCallerSPOffset - kPointerSize;
    DCHECK(r1.is(ArgumentsAccessReadDescriptor::index()));
    DCHECK(r0.is(ArgumentsAccessReadDescriptor::parameter_count()));
  
    // Check that the key is a smi.
    Label slow;
    __ JumpIfNotSmi(r1, &slow);
  
    // Check if the calling frame is an arguments adaptor frame.
    Label adaptor;
    __ ldr(r2, MemOperand(fp, StandardFrameConstants::kCallerFPOffset));
    __ ldr(r3, MemOperand(r2, StandardFrameConstants::kContextOffset));
    __ cmp(r3, Operand(Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR)));
    __ b(eq, &adaptor);
  
    // Check index against formal parameters count limit passed in
    // through register r0. Use unsigned comparison to get negative
    // check for free.
    __ cmp(r1, r0);
    __ b(hs, &slow);
  
    // Read the argument from the stack and return it.
    __ sub(r3, r0, r1);
    __ add(r3, fp, Operand::PointerOffsetFromSmiKey(r3));
    __ ldr(r0, MemOperand(r3, kDisplacement));
    __ Jump(lr);
  
    // Arguments adaptor case: Check index against actual arguments
    // limit found in the arguments adaptor frame. Use unsigned
    // comparison to get negative check for free.
    __ bind(&adaptor);
    __ ldr(r0, MemOperand(r2, ArgumentsAdaptorFrameConstants::kLengthOffset));
    __ cmp(r1, r0);
    __ b(cs, &slow);
  
    // Read the argument from the adaptor frame and return it.
    __ sub(r3, r0, r1);
    __ add(r3, r2, Operand::PointerOffsetFromSmiKey(r3));
    __ ldr(r0, MemOperand(r3, kDisplacement));
    __ Jump(lr);
  
    // Slow-case: Handle non-smi or out-of-bounds access to arguments
    // by calling the runtime system.
    __ bind(&slow);
    __ push(r1);
    __ TailCallRuntime(Runtime::kGetArgumentsProperty, 1, 1);
  }
  
  
  void ArgumentsAccessStub::GenerateNewSloppySlow(MacroAssembler* masm) {
    // sp[0] : number of parameters
    // sp[4] : receiver displacement
    // sp[8] : function
  
    // Check if the calling frame is an arguments adaptor frame.
    Label runtime;
    __ ldr(r3, MemOperand(fp, StandardFrameConstants::kCallerFPOffset));
    __ ldr(r2, MemOperand(r3, StandardFrameConstants::kContextOffset));
    __ cmp(r2, Operand(Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR)));
    __ b(ne, &runtime);
  
    // Patch the arguments.length and the parameters pointer in the current frame.
    __ ldr(r2, MemOperand(r3, ArgumentsAdaptorFrameConstants::kLengthOffset));
    __ str(r2, MemOperand(sp, 0 * kPointerSize));
    __ add(r3, r3, Operand(r2, LSL, 1));
    __ add(r3, r3, Operand(StandardFrameConstants::kCallerSPOffset));
    __ str(r3, MemOperand(sp, 1 * kPointerSize));
  
    __ bind(&runtime);
    __ TailCallRuntime(Runtime::kNewSloppyArguments, 3, 1);
  }
  
  
  void ArgumentsAccessStub::GenerateNewSloppyFast(MacroAssembler* masm) {
    // Stack layout:
    //  sp[0] : number of parameters (tagged)
    //  sp[4] : address of receiver argument
    //  sp[8] : function
    // Registers used over whole function:
    //  r6 : allocated object (tagged)
    //  r9 : mapped parameter count (tagged)
  
    __ ldr(r1, MemOperand(sp, 0 * kPointerSize));
    // r1 = parameter count (tagged)
  
    // Check if the calling frame is an arguments adaptor frame.
    Label runtime;
    Label adaptor_frame, try_allocate;
    __ ldr(r3, MemOperand(fp, StandardFrameConstants::kCallerFPOffset));
    __ ldr(r2, MemOperand(r3, StandardFrameConstants::kContextOffset));
    __ cmp(r2, Operand(Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR)));
    __ b(eq, &adaptor_frame);
  
    // No adaptor, parameter count = argument count.
    __ mov(r2, r1);
    __ b(&try_allocate);
  
    // We have an adaptor frame. Patch the parameters pointer.
    __ bind(&adaptor_frame);
    __ ldr(r2, MemOperand(r3, ArgumentsAdaptorFrameConstants::kLengthOffset));
    __ add(r3, r3, Operand(r2, LSL, 1));
    __ add(r3, r3, Operand(StandardFrameConstants::kCallerSPOffset));
    __ str(r3, MemOperand(sp, 1 * kPointerSize));
  
    // r1 = parameter count (tagged)
    // r2 = argument count (tagged)
    // Compute the mapped parameter count = min(r1, r2) in r1.
    __ cmp(r1, Operand(r2));
    __ mov(r1, Operand(r2), LeaveCC, gt);
  
    __ bind(&try_allocate);
  
    // Compute the sizes of backing store, parameter map, and arguments object.
    // 1. Parameter map, has 2 extra words containing context and backing store.
    const int kParameterMapHeaderSize =
        FixedArray::kHeaderSize + 2 * kPointerSize;
    // If there are no mapped parameters, we do not need the parameter_map.
    __ cmp(r1, Operand(Smi::FromInt(0)));
    __ mov(r9, Operand::Zero(), LeaveCC, eq);
    __ mov(r9, Operand(r1, LSL, 1), LeaveCC, ne);
    __ add(r9, r9, Operand(kParameterMapHeaderSize), LeaveCC, ne);
  
    // 2. Backing store.
    __ add(r9, r9, Operand(r2, LSL, 1));
    __ add(r9, r9, Operand(FixedArray::kHeaderSize));
  
    // 3. Arguments object.
    __ add(r9, r9, Operand(Heap::kSloppyArgumentsObjectSize));
  
    // Do the allocation of all three objects in one go.
    __ Allocate(r9, r0, r3, r4, &runtime, TAG_OBJECT);
  
    // r0 = address of new object(s) (tagged)
    // r2 = argument count (smi-tagged)
    // Get the arguments boilerplate from the current native context into r4.
    const int kNormalOffset =
        Context::SlotOffset(Context::SLOPPY_ARGUMENTS_MAP_INDEX);
    const int kAliasedOffset =
        Context::SlotOffset(Context::ALIASED_ARGUMENTS_MAP_INDEX);
  
    __ ldr(r4, MemOperand(cp, Context::SlotOffset(Context::GLOBAL_OBJECT_INDEX)));
    __ ldr(r4, FieldMemOperand(r4, GlobalObject::kNativeContextOffset));
    __ cmp(r1, Operand::Zero());
    __ ldr(r4, MemOperand(r4, kNormalOffset), eq);
    __ ldr(r4, MemOperand(r4, kAliasedOffset), ne);
  
    // r0 = address of new object (tagged)
    // r1 = mapped parameter count (tagged)
    // r2 = argument count (smi-tagged)
    // r4 = address of arguments map (tagged)
    __ str(r4, FieldMemOperand(r0, JSObject::kMapOffset));
    __ LoadRoot(r3, Heap::kEmptyFixedArrayRootIndex);
    __ str(r3, FieldMemOperand(r0, JSObject::kPropertiesOffset));
    __ str(r3, FieldMemOperand(r0, JSObject::kElementsOffset));
  
    // Set up the callee in-object property.
    STATIC_ASSERT(Heap::kArgumentsCalleeIndex == 1);
    __ ldr(r3, MemOperand(sp, 2 * kPointerSize));
    __ AssertNotSmi(r3);
    const int kCalleeOffset = JSObject::kHeaderSize +
        Heap::kArgumentsCalleeIndex * kPointerSize;
    __ str(r3, FieldMemOperand(r0, kCalleeOffset));
  
    // Use the length (smi tagged) and set that as an in-object property too.
    __ AssertSmi(r2);
    STATIC_ASSERT(Heap::kArgumentsLengthIndex == 0);
    const int kLengthOffset = JSObject::kHeaderSize +
        Heap::kArgumentsLengthIndex * kPointerSize;
    __ str(r2, FieldMemOperand(r0, kLengthOffset));
  
    // Set up the elements pointer in the allocated arguments object.
    // If we allocated a parameter map, r4 will point there, otherwise
    // it will point to the backing store.
    __ add(r4, r0, Operand(Heap::kSloppyArgumentsObjectSize));
    __ str(r4, FieldMemOperand(r0, JSObject::kElementsOffset));
  
    // r0 = address of new object (tagged)
    // r1 = mapped parameter count (tagged)
    // r2 = argument count (tagged)
    // r4 = address of parameter map or backing store (tagged)
    // Initialize parameter map. If there are no mapped arguments, we're done.
    Label skip_parameter_map;
    __ cmp(r1, Operand(Smi::FromInt(0)));
    // Move backing store address to r3, because it is
    // expected there when filling in the unmapped arguments.
    __ mov(r3, r4, LeaveCC, eq);
    __ b(eq, &skip_parameter_map);
  
    __ LoadRoot(r6, Heap::kSloppyArgumentsElementsMapRootIndex);
    __ str(r6, FieldMemOperand(r4, FixedArray::kMapOffset));
    __ add(r6, r1, Operand(Smi::FromInt(2)));
    __ str(r6, FieldMemOperand(r4, FixedArray::kLengthOffset));
    __ str(cp, FieldMemOperand(r4, FixedArray::kHeaderSize + 0 * kPointerSize));
    __ add(r6, r4, Operand(r1, LSL, 1));
    __ add(r6, r6, Operand(kParameterMapHeaderSize));
    __ str(r6, FieldMemOperand(r4, FixedArray::kHeaderSize + 1 * kPointerSize));
  
    // Copy the parameter slots and the holes in the arguments.
    // We need to fill in mapped_parameter_count slots. They index the context,
    // where parameters are stored in reverse order, at
    //   MIN_CONTEXT_SLOTS .. MIN_CONTEXT_SLOTS+parameter_count-1
    // The mapped parameter thus need to get indices
    //   MIN_CONTEXT_SLOTS+parameter_count-1 ..
    //       MIN_CONTEXT_SLOTS+parameter_count-mapped_parameter_count
    // We loop from right to left.
    Label parameters_loop, parameters_test;
    __ mov(r6, r1);
    __ ldr(r9, MemOperand(sp, 0 * kPointerSize));
    __ add(r9, r9, Operand(Smi::FromInt(Context::MIN_CONTEXT_SLOTS)));
    __ sub(r9, r9, Operand(r1));
    __ LoadRoot(r5, Heap::kTheHoleValueRootIndex);
    __ add(r3, r4, Operand(r6, LSL, 1));
    __ add(r3, r3, Operand(kParameterMapHeaderSize));
  
    // r6 = loop variable (tagged)
    // r1 = mapping index (tagged)
    // r3 = address of backing store (tagged)
    // r4 = address of parameter map (tagged), which is also the address of new
    //      object + Heap::kSloppyArgumentsObjectSize (tagged)
    // r0 = temporary scratch (a.o., for address calculation)
    // r5 = the hole value
    __ jmp(&parameters_test);
  
    __ bind(&parameters_loop);
    __ sub(r6, r6, Operand(Smi::FromInt(1)));
    __ mov(r0, Operand(r6, LSL, 1));
    __ add(r0, r0, Operand(kParameterMapHeaderSize - kHeapObjectTag));
    __ str(r9, MemOperand(r4, r0));
    __ sub(r0, r0, Operand(kParameterMapHeaderSize - FixedArray::kHeaderSize));
    __ str(r5, MemOperand(r3, r0));
    __ add(r9, r9, Operand(Smi::FromInt(1)));
    __ bind(&parameters_test);
    __ cmp(r6, Operand(Smi::FromInt(0)));
    __ b(ne, &parameters_loop);
  
    // Restore r0 = new object (tagged)
    __ sub(r0, r4, Operand(Heap::kSloppyArgumentsObjectSize));
  
    __ bind(&skip_parameter_map);
    // r0 = address of new object (tagged)
    // r2 = argument count (tagged)
    // r3 = address of backing store (tagged)
    // r5 = scratch
    // Copy arguments header and remaining slots (if there are any).
    __ LoadRoot(r5, Heap::kFixedArrayMapRootIndex);
    __ str(r5, FieldMemOperand(r3, FixedArray::kMapOffset));
    __ str(r2, FieldMemOperand(r3, FixedArray::kLengthOffset));
  
    Label arguments_loop, arguments_test;
    __ mov(r9, r1);
    __ ldr(r4, MemOperand(sp, 1 * kPointerSize));
    __ sub(r4, r4, Operand(r9, LSL, 1));
    __ jmp(&arguments_test);
  
    __ bind(&arguments_loop);
    __ sub(r4, r4, Operand(kPointerSize));
    __ ldr(r6, MemOperand(r4, 0));
    __ add(r5, r3, Operand(r9, LSL, 1));
    __ str(r6, FieldMemOperand(r5, FixedArray::kHeaderSize));
    __ add(r9, r9, Operand(Smi::FromInt(1)));
  
    __ bind(&arguments_test);
    __ cmp(r9, Operand(r2));
    __ b(lt, &arguments_loop);
  
    // Return and remove the on-stack parameters.
    __ add(sp, sp, Operand(3 * kPointerSize));
    __ Ret();
  
    // Do the runtime call to allocate the arguments object.
    // r0 = address of new object (tagged)
    // r2 = argument count (tagged)
    __ bind(&runtime);
    __ str(r2, MemOperand(sp, 0 * kPointerSize));  // Patch argument count.
    __ TailCallRuntime(Runtime::kNewSloppyArguments, 3, 1);
  }
  
  
  void LoadIndexedInterceptorStub::Generate(MacroAssembler* masm) {
    // Return address is in lr.
    Label slow;
  
    Register receiver = LoadDescriptor::ReceiverRegister();
    Register key = LoadDescriptor::NameRegister();
  
    // Check that the key is an array index, that is Uint32.
    __ NonNegativeSmiTst(key);
    __ b(ne, &slow);
  
    // Everything is fine, call runtime.
    __ Push(receiver, key);  // Receiver, key.
  
    // Perform tail call to the entry.
    __ TailCallExternalReference(
        ExternalReference(IC_Utility(IC::kLoadElementWithInterceptor),
                          masm->isolate()),
        2, 1);
  
    __ bind(&slow);
    PropertyAccessCompiler::TailCallBuiltin(
        masm, PropertyAccessCompiler::MissBuiltin(Code::KEYED_LOAD_IC));
  }
  
  
  void ArgumentsAccessStub::GenerateNewStrict(MacroAssembler* masm) {
    // sp[0] : number of parameters
    // sp[4] : receiver displacement
    // sp[8] : function
    // Check if the calling frame is an arguments adaptor frame.
    Label adaptor_frame, try_allocate, runtime;
    __ ldr(r2, MemOperand(fp, StandardFrameConstants::kCallerFPOffset));
    __ ldr(r3, MemOperand(r2, StandardFrameConstants::kContextOffset));
    __ cmp(r3, Operand(Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR)));
    __ b(eq, &adaptor_frame);
  
    // Get the length from the frame.
    __ ldr(r1, MemOperand(sp, 0));
    __ b(&try_allocate);
  
    // Patch the arguments.length and the parameters pointer.
    __ bind(&adaptor_frame);
    __ ldr(r1, MemOperand(r2, ArgumentsAdaptorFrameConstants::kLengthOffset));
    __ str(r1, MemOperand(sp, 0));
    __ add(r3, r2, Operand::PointerOffsetFromSmiKey(r1));
    __ add(r3, r3, Operand(StandardFrameConstants::kCallerSPOffset));
    __ str(r3, MemOperand(sp, 1 * kPointerSize));
  
    // Try the new space allocation. Start out with computing the size
    // of the arguments object and the elements array in words.
    Label add_arguments_object;
    __ bind(&try_allocate);
    __ SmiUntag(r1, SetCC);
    __ b(eq, &add_arguments_object);
    __ add(r1, r1, Operand(FixedArray::kHeaderSize / kPointerSize));
    __ bind(&add_arguments_object);
    __ add(r1, r1, Operand(Heap::kStrictArgumentsObjectSize / kPointerSize));
  
    // Do the allocation of both objects in one go.
    __ Allocate(r1, r0, r2, r3, &runtime,
                static_cast<AllocationFlags>(TAG_OBJECT | SIZE_IN_WORDS));
  
    // Get the arguments boilerplate from the current native context.
    __ ldr(r4, MemOperand(cp, Context::SlotOffset(Context::GLOBAL_OBJECT_INDEX)));
    __ ldr(r4, FieldMemOperand(r4, GlobalObject::kNativeContextOffset));
    __ ldr(r4, MemOperand(
                   r4, Context::SlotOffset(Context::STRICT_ARGUMENTS_MAP_INDEX)));
  
    __ str(r4, FieldMemOperand(r0, JSObject::kMapOffset));
    __ LoadRoot(r3, Heap::kEmptyFixedArrayRootIndex);
    __ str(r3, FieldMemOperand(r0, JSObject::kPropertiesOffset));
    __ str(r3, FieldMemOperand(r0, JSObject::kElementsOffset));
  
    // Get the length (smi tagged) and set that as an in-object property too.
    STATIC_ASSERT(Heap::kArgumentsLengthIndex == 0);
    __ ldr(r1, MemOperand(sp, 0 * kPointerSize));
    __ AssertSmi(r1);
    __ str(r1, FieldMemOperand(r0, JSObject::kHeaderSize +
        Heap::kArgumentsLengthIndex * kPointerSize));
  
    // If there are no actual arguments, we're done.
    Label done;
    __ cmp(r1, Operand::Zero());
    __ b(eq, &done);
  
    // Get the parameters pointer from the stack.
    __ ldr(r2, MemOperand(sp, 1 * kPointerSize));
  
    // Set up the elements pointer in the allocated arguments object and
    // initialize the header in the elements fixed array.
    __ add(r4, r0, Operand(Heap::kStrictArgumentsObjectSize));
    __ str(r4, FieldMemOperand(r0, JSObject::kElementsOffset));
    __ LoadRoot(r3, Heap::kFixedArrayMapRootIndex);
    __ str(r3, FieldMemOperand(r4, FixedArray::kMapOffset));
    __ str(r1, FieldMemOperand(r4, FixedArray::kLengthOffset));
    __ SmiUntag(r1);
  
    // Copy the fixed array slots.
    Label loop;
    // Set up r4 to point to the first array slot.
    __ add(r4, r4, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
    __ bind(&loop);
    // Pre-decrement r2 with kPointerSize on each iteration.
    // Pre-decrement in order to skip receiver.
    __ ldr(r3, MemOperand(r2, kPointerSize, NegPreIndex));
    // Post-increment r4 with kPointerSize on each iteration.
    __ str(r3, MemOperand(r4, kPointerSize, PostIndex));
    __ sub(r1, r1, Operand(1));
    __ cmp(r1, Operand::Zero());
    __ b(ne, &loop);
  
    // Return and remove the on-stack parameters.
    __ bind(&done);
    __ add(sp, sp, Operand(3 * kPointerSize));
    __ Ret();
  
    // Do the runtime call to allocate the arguments object.
    __ bind(&runtime);
    __ TailCallRuntime(Runtime::kNewStrictArguments, 3, 1);
  }
  
  
  void RegExpExecStub::Generate(MacroAssembler* masm) {
    // Just jump directly to runtime if native RegExp is not selected at compile
    // time or if regexp entry in generated code is turned off runtime switch or
    // at compilation.
  #ifdef V8_INTERPRETED_REGEXP
    __ TailCallRuntime(Runtime::kRegExpExecRT, 4, 1);
  #else  // V8_INTERPRETED_REGEXP
  
    // Stack frame on entry.
    //  sp[0]: last_match_info (expected JSArray)
    //  sp[4]: previous index
    //  sp[8]: subject string
    //  sp[12]: JSRegExp object
  
    const int kLastMatchInfoOffset = 0 * kPointerSize;
    const int kPreviousIndexOffset = 1 * kPointerSize;
    const int kSubjectOffset = 2 * kPointerSize;
    const int kJSRegExpOffset = 3 * kPointerSize;
  
    Label runtime;
    // Allocation of registers for this function. These are in callee save
    // registers and will be preserved by the call to the native RegExp code, as
    // this code is called using the normal C calling convention. When calling
    // directly from generated code the native RegExp code will not do a GC and
    // therefore the content of these registers are safe to use after the call.
    Register subject = r4;
    Register regexp_data = r5;
    Register last_match_info_elements = no_reg;  // will be r6;
  
    // Ensure that a RegExp stack is allocated.
    ExternalReference address_of_regexp_stack_memory_address =
        ExternalReference::address_of_regexp_stack_memory_address(isolate());
    ExternalReference address_of_regexp_stack_memory_size =
        ExternalReference::address_of_regexp_stack_memory_size(isolate());
    __ mov(r0, Operand(address_of_regexp_stack_memory_size));
    __ ldr(r0, MemOperand(r0, 0));
    __ cmp(r0, Operand::Zero());
    __ b(eq, &runtime);
  
    // Check that the first argument is a JSRegExp object.
    __ ldr(r0, MemOperand(sp, kJSRegExpOffset));
    __ JumpIfSmi(r0, &runtime);
    __ CompareObjectType(r0, r1, r1, JS_REGEXP_TYPE);
    __ b(ne, &runtime);
  
    // Check that the RegExp has been compiled (data contains a fixed array).
    __ ldr(regexp_data, FieldMemOperand(r0, JSRegExp::kDataOffset));
    if (FLAG_debug_code) {
      __ SmiTst(regexp_data);
      __ Check(ne, kUnexpectedTypeForRegExpDataFixedArrayExpected);
      __ CompareObjectType(regexp_data, r0, r0, FIXED_ARRAY_TYPE);
      __ Check(eq, kUnexpectedTypeForRegExpDataFixedArrayExpected);
    }
  
    // regexp_data: RegExp data (FixedArray)
    // Check the type of the RegExp. Only continue if type is JSRegExp::IRREGEXP.
    __ ldr(r0, FieldMemOperand(regexp_data, JSRegExp::kDataTagOffset));
    __ cmp(r0, Operand(Smi::FromInt(JSRegExp::IRREGEXP)));
    __ b(ne, &runtime);
  
    // regexp_data: RegExp data (FixedArray)
    // Check that the number of captures fit in the static offsets vector buffer.
    __ ldr(r2,
           FieldMemOperand(regexp_data, JSRegExp::kIrregexpCaptureCountOffset));
    // Check (number_of_captures + 1) * 2 <= offsets vector size
    // Or          number_of_captures * 2 <= offsets vector size - 2
    // Multiplying by 2 comes for free since r2 is smi-tagged.
    STATIC_ASSERT(kSmiTag == 0);
    STATIC_ASSERT(kSmiTagSize + kSmiShiftSize == 1);
    STATIC_ASSERT(Isolate::kJSRegexpStaticOffsetsVectorSize >= 2);
    __ cmp(r2, Operand(Isolate::kJSRegexpStaticOffsetsVectorSize - 2));
    __ b(hi, &runtime);
  
    // Reset offset for possibly sliced string.
    __ mov(r9, Operand::Zero());
    __ ldr(subject, MemOperand(sp, kSubjectOffset));
    __ JumpIfSmi(subject, &runtime);
    __ mov(r3, subject);  // Make a copy of the original subject string.
    __ ldr(r0, FieldMemOperand(subject, HeapObject::kMapOffset));
    __ ldrb(r0, FieldMemOperand(r0, Map::kInstanceTypeOffset));
    // subject: subject string
    // r3: subject string
    // r0: subject string instance type
    // regexp_data: RegExp data (FixedArray)
    // Handle subject string according to its encoding and representation:
    // (1) Sequential string?  If yes, go to (5).
    // (2) Anything but sequential or cons?  If yes, go to (6).
    // (3) Cons string.  If the string is flat, replace subject with first string.
    //     Otherwise bailout.
    // (4) Is subject external?  If yes, go to (7).
    // (5) Sequential string.  Load regexp code according to encoding.
    // (E) Carry on.
    /// [...]
  
    // Deferred code at the end of the stub:
    // (6) Not a long external string?  If yes, go to (8).
    // (7) External string.  Make it, offset-wise, look like a sequential string.
    //     Go to (5).
    // (8) Short external string or not a string?  If yes, bail out to runtime.
    // (9) Sliced string.  Replace subject with parent.  Go to (4).
  
    Label seq_string /* 5 */, external_string /* 7 */,
          check_underlying /* 4 */, not_seq_nor_cons /* 6 */,
          not_long_external /* 8 */;
  
    // (1) Sequential string?  If yes, go to (5).
    __ and_(r1,
            r0,
            Operand(kIsNotStringMask |
                    kStringRepresentationMask |
                    kShortExternalStringMask),
            SetCC);
    STATIC_ASSERT((kStringTag | kSeqStringTag) == 0);
    __ b(eq, &seq_string);  // Go to (5).
  
    // (2) Anything but sequential or cons?  If yes, go to (6).
    STATIC_ASSERT(kConsStringTag < kExternalStringTag);
    STATIC_ASSERT(kSlicedStringTag > kExternalStringTag);
    STATIC_ASSERT(kIsNotStringMask > kExternalStringTag);
    STATIC_ASSERT(kShortExternalStringTag > kExternalStringTag);
    __ cmp(r1, Operand(kExternalStringTag));
    __ b(ge, &not_seq_nor_cons);  // Go to (6).
  
    // (3) Cons string.  Check that it's flat.
    // Replace subject with first string and reload instance type.
    __ ldr(r0, FieldMemOperand(subject, ConsString::kSecondOffset));
    __ CompareRoot(r0, Heap::kempty_stringRootIndex);
    __ b(ne, &runtime);
    __ ldr(subject, FieldMemOperand(subject, ConsString::kFirstOffset));
  
    // (4) Is subject external?  If yes, go to (7).
    __ bind(&check_underlying);
    __ ldr(r0, FieldMemOperand(subject, HeapObject::kMapOffset));
    __ ldrb(r0, FieldMemOperand(r0, Map::kInstanceTypeOffset));
    STATIC_ASSERT(kSeqStringTag == 0);
    __ tst(r0, Operand(kStringRepresentationMask));
    // The underlying external string is never a short external string.
    STATIC_ASSERT(ExternalString::kMaxShortLength < ConsString::kMinLength);
    STATIC_ASSERT(ExternalString::kMaxShortLength < SlicedString::kMinLength);
    __ b(ne, &external_string);  // Go to (7).
  
    // (5) Sequential string.  Load regexp code according to encoding.
    __ bind(&seq_string);
    // subject: sequential subject string (or look-alike, external string)
    // r3: original subject string
    // Load previous index and check range before r3 is overwritten.  We have to
    // use r3 instead of subject here because subject might have been only made
    // to look like a sequential string when it actually is an external string.
    __ ldr(r1, MemOperand(sp, kPreviousIndexOffset));
    __ JumpIfNotSmi(r1, &runtime);
    __ ldr(r3, FieldMemOperand(r3, String::kLengthOffset));
    __ cmp(r3, Operand(r1));
    __ b(ls, &runtime);
    __ SmiUntag(r1);
  
    STATIC_ASSERT(4 == kOneByteStringTag);
    STATIC_ASSERT(kTwoByteStringTag == 0);
    __ and_(r0, r0, Operand(kStringEncodingMask));
    __ mov(r3, Operand(r0, ASR, 2), SetCC);
    __ ldr(r6, FieldMemOperand(regexp_data, JSRegExp::kDataOneByteCodeOffset),
           ne);
    __ ldr(r6, FieldMemOperand(regexp_data, JSRegExp::kDataUC16CodeOffset), eq);
  
    // (E) Carry on.  String handling is done.
    // r6: irregexp code
    // Check that the irregexp code has been generated for the actual string
    // encoding. If it has, the field contains a code object otherwise it contains
    // a smi (code flushing support).
    __ JumpIfSmi(r6, &runtime);
  
    // r1: previous index
    // r3: encoding of subject string (1 if one_byte, 0 if two_byte);
    // r6: code
    // subject: Subject string
    // regexp_data: RegExp data (FixedArray)
    // All checks done. Now push arguments for native regexp code.
    __ IncrementCounter(isolate()->counters()->regexp_entry_native(), 1, r0, r2);
  
    // Isolates: note we add an additional parameter here (isolate pointer).
    const int kRegExpExecuteArguments = 9;
    const int kParameterRegisters = 4;
    __ EnterExitFrame(false, kRegExpExecuteArguments - kParameterRegisters);
  
    // Stack pointer now points to cell where return address is to be written.
    // Arguments are before that on the stack or in registers.
  
    // Argument 9 (sp[20]): Pass current isolate address.
    __ mov(r0, Operand(ExternalReference::isolate_address(isolate())));
    __ str(r0, MemOperand(sp, 5 * kPointerSize));
  
    // Argument 8 (sp[16]): Indicate that this is a direct call from JavaScript.
    __ mov(r0, Operand(1));
    __ str(r0, MemOperand(sp, 4 * kPointerSize));
  
    // Argument 7 (sp[12]): Start (high end) of backtracking stack memory area.
    __ mov(r0, Operand(address_of_regexp_stack_memory_address));
    __ ldr(r0, MemOperand(r0, 0));
    __ mov(r2, Operand(address_of_regexp_stack_memory_size));
    __ ldr(r2, MemOperand(r2, 0));
    __ add(r0, r0, Operand(r2));
    __ str(r0, MemOperand(sp, 3 * kPointerSize));
  
    // Argument 6: Set the number of capture registers to zero to force global
    // regexps to behave as non-global.  This does not affect non-global regexps.
    __ mov(r0, Operand::Zero());
    __ str(r0, MemOperand(sp, 2 * kPointerSize));
  
    // Argument 5 (sp[4]): static offsets vector buffer.
    __ mov(r0,
           Operand(ExternalReference::address_of_static_offsets_vector(
               isolate())));
    __ str(r0, MemOperand(sp, 1 * kPointerSize));
  
    // For arguments 4 and 3 get string length, calculate start of string data and
    // calculate the shift of the index (0 for one-byte and 1 for two-byte).
    __ add(r7, subject, Operand(SeqString::kHeaderSize - kHeapObjectTag));
    __ eor(r3, r3, Operand(1));
    // Load the length from the original subject string from the previous stack
    // frame. Therefore we have to use fp, which points exactly to two pointer
    // sizes below the previous sp. (Because creating a new stack frame pushes
    // the previous fp onto the stack and moves up sp by 2 * kPointerSize.)
    __ ldr(subject, MemOperand(fp, kSubjectOffset + 2 * kPointerSize));
    // If slice offset is not 0, load the length from the original sliced string.
    // Argument 4, r3: End of string data
    // Argument 3, r2: Start of string data
    // Prepare start and end index of the input.
    __ add(r9, r7, Operand(r9, LSL, r3));
    __ add(r2, r9, Operand(r1, LSL, r3));
  
    __ ldr(r7, FieldMemOperand(subject, String::kLengthOffset));
    __ SmiUntag(r7);
    __ add(r3, r9, Operand(r7, LSL, r3));
  
    // Argument 2 (r1): Previous index.
    // Already there
  
    // Argument 1 (r0): Subject string.
    __ mov(r0, subject);
  
    // Locate the code entry and call it.
    __ add(r6, r6, Operand(Code::kHeaderSize - kHeapObjectTag));
    DirectCEntryStub stub(isolate());
    stub.GenerateCall(masm, r6);
  
    __ LeaveExitFrame(false, no_reg, true);
  
    last_match_info_elements = r6;
  
    // r0: result
    // subject: subject string (callee saved)
    // regexp_data: RegExp data (callee saved)
    // last_match_info_elements: Last match info elements (callee saved)
    // Check the result.
    Label success;
    __ cmp(r0, Operand(1));
    // We expect exactly one result since we force the called regexp to behave
    // as non-global.
    __ b(eq, &success);
    Label failure;
    __ cmp(r0, Operand(NativeRegExpMacroAssembler::FAILURE));
    __ b(eq, &failure);
    __ cmp(r0, Operand(NativeRegExpMacroAssembler::EXCEPTION));
    // If not exception it can only be retry. Handle that in the runtime system.
    __ b(ne, &runtime);
    // Result must now be exception. If there is no pending exception already a
    // stack overflow (on the backtrack stack) was detected in RegExp code but
    // haven't created the exception yet. Handle that in the runtime system.
    // TODO(592): Rerunning the RegExp to get the stack overflow exception.
    __ mov(r1, Operand(isolate()->factory()->the_hole_value()));
    __ mov(r2, Operand(ExternalReference(Isolate::kPendingExceptionAddress,
                                         isolate())));
    __ ldr(r0, MemOperand(r2, 0));
    __ cmp(r0, r1);
    __ b(eq, &runtime);
  
    __ str(r1, MemOperand(r2, 0));  // Clear pending exception.
  
    // Check if the exception is a termination. If so, throw as uncatchable.
    __ CompareRoot(r0, Heap::kTerminationExceptionRootIndex);
  
    Label termination_exception;
    __ b(eq, &termination_exception);
  
    __ Throw(r0);
  
    __ bind(&termination_exception);
    __ ThrowUncatchable(r0);
  
    __ bind(&failure);
    // For failure and exception return null.
    __ mov(r0, Operand(isolate()->factory()->null_value()));
    __ add(sp, sp, Operand(4 * kPointerSize));
    __ Ret();
  
    // Process the result from the native regexp code.
    __ bind(&success);
    __ ldr(r1,
           FieldMemOperand(regexp_data, JSRegExp::kIrregexpCaptureCountOffset));
    // Calculate number of capture registers (number_of_captures + 1) * 2.
    // Multiplying by 2 comes for free since r1 is smi-tagged.
    STATIC_ASSERT(kSmiTag == 0);
    STATIC_ASSERT(kSmiTagSize + kSmiShiftSize == 1);
    __ add(r1, r1, Operand(2));  // r1 was a smi.
  
    __ ldr(r0, MemOperand(sp, kLastMatchInfoOffset));
    __ JumpIfSmi(r0, &runtime);
    __ CompareObjectType(r0, r2, r2, JS_ARRAY_TYPE);
    __ b(ne, &runtime);
    // Check that the JSArray is in fast case.
    __ ldr(last_match_info_elements,
           FieldMemOperand(r0, JSArray::kElementsOffset));
    __ ldr(r0, FieldMemOperand(last_match_info_elements, HeapObject::kMapOffset));
    __ CompareRoot(r0, Heap::kFixedArrayMapRootIndex);
    __ b(ne, &runtime);
    // Check that the last match info has space for the capture registers and the
    // additional information.
    __ ldr(r0,
           FieldMemOperand(last_match_info_elements, FixedArray::kLengthOffset));
    __ add(r2, r1, Operand(RegExpImpl::kLastMatchOverhead));
    __ cmp(r2, Operand::SmiUntag(r0));
    __ b(gt, &runtime);
  
    // r1: number of capture registers
    // r4: subject string
    // Store the capture count.
    __ SmiTag(r2, r1);
    __ str(r2, FieldMemOperand(last_match_info_elements,
                               RegExpImpl::kLastCaptureCountOffset));
    // Store last subject and last input.
    __ str(subject,
           FieldMemOperand(last_match_info_elements,
                           RegExpImpl::kLastSubjectOffset));
    __ mov(r2, subject);
    __ RecordWriteField(last_match_info_elements,
                        RegExpImpl::kLastSubjectOffset,
                        subject,
                        r3,
                        kLRHasNotBeenSaved,
                        kDontSaveFPRegs);
    __ mov(subject, r2);
    __ str(subject,
           FieldMemOperand(last_match_info_elements,
                           RegExpImpl::kLastInputOffset));
    __ RecordWriteField(last_match_info_elements,
                        RegExpImpl::kLastInputOffset,
                        subject,
                        r3,
                        kLRHasNotBeenSaved,
                        kDontSaveFPRegs);
  
    // Get the static offsets vector filled by the native regexp code.
    ExternalReference address_of_static_offsets_vector =
        ExternalReference::address_of_static_offsets_vector(isolate());
    __ mov(r2, Operand(address_of_static_offsets_vector));
  
    // r1: number of capture registers
    // r2: offsets vector
    Label next_capture, done;
    // Capture register counter starts from number of capture registers and
    // counts down until wraping after zero.
    __ add(r0,
           last_match_info_elements,
           Operand(RegExpImpl::kFirstCaptureOffset - kHeapObjectTag));
    __ bind(&next_capture);
    __ sub(r1, r1, Operand(1), SetCC);
    __ b(mi, &done);
    // Read the value from the static offsets vector buffer.
    __ ldr(r3, MemOperand(r2, kPointerSize, PostIndex));
    // Store the smi value in the last match info.
    __ SmiTag(r3);
    __ str(r3, MemOperand(r0, kPointerSize, PostIndex));
    __ jmp(&next_capture);
    __ bind(&done);
  
    // Return last match info.
    __ ldr(r0, MemOperand(sp, kLastMatchInfoOffset));
    __ add(sp, sp, Operand(4 * kPointerSize));
    __ Ret();
  
    // Do the runtime call to execute the regexp.
    __ bind(&runtime);
    __ TailCallRuntime(Runtime::kRegExpExecRT, 4, 1);
  
    // Deferred code for string handling.
    // (6) Not a long external string?  If yes, go to (8).
    __ bind(&not_seq_nor_cons);
    // Compare flags are still set.
    __ b(gt, &not_long_external);  // Go to (8).
  
    // (7) External string.  Make it, offset-wise, look like a sequential string.
    __ bind(&external_string);
    __ ldr(r0, FieldMemOperand(subject, HeapObject::kMapOffset));
    __ ldrb(r0, FieldMemOperand(r0, Map::kInstanceTypeOffset));
    if (FLAG_debug_code) {
      // Assert that we do not have a cons or slice (indirect strings) here.
      // Sequential strings have already been ruled out.
      __ tst(r0, Operand(kIsIndirectStringMask));
      __ Assert(eq, kExternalStringExpectedButNotFound);
    }
    __ ldr(subject,
           FieldMemOperand(subject, ExternalString::kResourceDataOffset));
    // Move the pointer so that offset-wise, it looks like a sequential string.
    STATIC_ASSERT(SeqTwoByteString::kHeaderSize == SeqOneByteString::kHeaderSize);
    __ sub(subject,
           subject,
           Operand(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
    __ jmp(&seq_string);    // Go to (5).
  
    // (8) Short external string or not a string?  If yes, bail out to runtime.
    __ bind(&not_long_external);
    STATIC_ASSERT(kNotStringTag != 0 && kShortExternalStringTag !=0);
    __ tst(r1, Operand(kIsNotStringMask | kShortExternalStringMask));
    __ b(ne, &runtime);
  
    // (9) Sliced string.  Replace subject with parent.  Go to (4).
    // Load offset into r9 and replace subject string with parent.
    __ ldr(r9, FieldMemOperand(subject, SlicedString::kOffsetOffset));
    __ SmiUntag(r9);
    __ ldr(subject, FieldMemOperand(subject, SlicedString::kParentOffset));
    __ jmp(&check_underlying);  // Go to (4).
  #endif  // V8_INTERPRETED_REGEXP
  }
  
  
  static void GenerateRecordCallTarget(MacroAssembler* masm) {
    // Cache the called function in a feedback vector slot.  Cache states
    // are uninitialized, monomorphic (indicated by a JSFunction), and
    // megamorphic.
    // r0 : number of arguments to the construct function
    // r1 : the function to call
    // r2 : Feedback vector
    // r3 : slot in feedback vector (Smi)
    Label initialize, done, miss, megamorphic, not_array_function;
  
    DCHECK_EQ(*TypeFeedbackVector::MegamorphicSentinel(masm->isolate()),
              masm->isolate()->heap()->megamorphic_symbol());
    DCHECK_EQ(*TypeFeedbackVector::UninitializedSentinel(masm->isolate()),
              masm->isolate()->heap()->uninitialized_symbol());
  
    // Load the cache state into r4.
    __ add(r4, r2, Operand::PointerOffsetFromSmiKey(r3));
    __ ldr(r4, FieldMemOperand(r4, FixedArray::kHeaderSize));
  
    // A monomorphic cache hit or an already megamorphic state: invoke the
    // function without changing the state.
    __ cmp(r4, r1);
    __ b(eq, &done);
  
    if (!FLAG_pretenuring_call_new) {
      // If we came here, we need to see if we are the array function.
      // If we didn't have a matching function, and we didn't find the megamorph
      // sentinel, then we have in the slot either some other function or an
      // AllocationSite. Do a map check on the object in ecx.
      __ ldr(r5, FieldMemOperand(r4, 0));
      __ CompareRoot(r5, Heap::kAllocationSiteMapRootIndex);
      __ b(ne, &miss);
  
      // Make sure the function is the Array() function
      __ LoadGlobalFunction(Context::ARRAY_FUNCTION_INDEX, r4);
      __ cmp(r1, r4);
      __ b(ne, &megamorphic);
      __ jmp(&done);
    }
  
    __ bind(&miss);
  
    // A monomorphic miss (i.e, here the cache is not uninitialized) goes
    // megamorphic.
    __ CompareRoot(r4, Heap::kUninitializedSymbolRootIndex);
    __ b(eq, &initialize);
    // MegamorphicSentinel is an immortal immovable object (undefined) so no
    // write-barrier is needed.
    __ bind(&megamorphic);
    __ add(r4, r2, Operand::PointerOffsetFromSmiKey(r3));
    __ LoadRoot(ip, Heap::kMegamorphicSymbolRootIndex);
    __ str(ip, FieldMemOperand(r4, FixedArray::kHeaderSize));
    __ jmp(&done);
  
    // An uninitialized cache is patched with the function
    __ bind(&initialize);
  
    if (!FLAG_pretenuring_call_new) {
      // Make sure the function is the Array() function
      __ LoadGlobalFunction(Context::ARRAY_FUNCTION_INDEX, r4);
      __ cmp(r1, r4);
      __ b(ne, &not_array_function);
  
      // The target function is the Array constructor,
      // Create an AllocationSite if we don't already have it, store it in the
      // slot.
      {
        FrameAndConstantPoolScope scope(masm, StackFrame::INTERNAL);
  
        // Arguments register must be smi-tagged to call out.
        __ SmiTag(r0);
        __ Push(r3, r2, r1, r0);
  
        CreateAllocationSiteStub create_stub(masm->isolate());
        __ CallStub(&create_stub);
  
        __ Pop(r3, r2, r1, r0);
        __ SmiUntag(r0);
      }
      __ b(&done);
  
      __ bind(&not_array_function);
    }
  
    __ add(r4, r2, Operand::PointerOffsetFromSmiKey(r3));
    __ add(r4, r4, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
    __ str(r1, MemOperand(r4, 0));
  
    __ Push(r4, r2, r1);
    __ RecordWrite(r2, r4, r1, kLRHasNotBeenSaved, kDontSaveFPRegs,
                   EMIT_REMEMBERED_SET, OMIT_SMI_CHECK);
    __ Pop(r4, r2, r1);
  
    __ bind(&done);
  }
  
  
  static void EmitContinueIfStrictOrNative(MacroAssembler* masm, Label* cont) {
    // Do not transform the receiver for strict mode functions.
    __ ldr(r3, FieldMemOperand(r1, JSFunction::kSharedFunctionInfoOffset));
    __ ldr(r4, FieldMemOperand(r3, SharedFunctionInfo::kCompilerHintsOffset));
    __ tst(r4, Operand(1 << (SharedFunctionInfo::kStrictModeFunction +
                             kSmiTagSize)));
    __ b(ne, cont);
  
    // Do not transform the receiver for native (Compilerhints already in r3).
    __ tst(r4, Operand(1 << (SharedFunctionInfo::kNative + kSmiTagSize)));
    __ b(ne, cont);
  }
  
  
  static void EmitSlowCase(MacroAssembler* masm,
                           int argc,
                           Label* non_function) {
    // Check for function proxy.
    __ cmp(r4, Operand(JS_FUNCTION_PROXY_TYPE));
    __ b(ne, non_function);
    __ push(r1);  // put proxy as additional argument
    __ mov(r0, Operand(argc + 1, RelocInfo::NONE32));
    __ mov(r2, Operand::Zero());
    __ GetBuiltinFunction(r1, Builtins::CALL_FUNCTION_PROXY);
    {
      Handle<Code> adaptor =
          masm->isolate()->builtins()->ArgumentsAdaptorTrampoline();
      __ Jump(adaptor, RelocInfo::CODE_TARGET);
    }
  
    // CALL_NON_FUNCTION expects the non-function callee as receiver (instead
    // of the original receiver from the call site).
    __ bind(non_function);
    __ str(r1, MemOperand(sp, argc * kPointerSize));
    __ mov(r0, Operand(argc));  // Set up the number of arguments.
    __ mov(r2, Operand::Zero());
    __ GetBuiltinFunction(r1, Builtins::CALL_NON_FUNCTION);
    __ Jump(masm->isolate()->builtins()->ArgumentsAdaptorTrampoline(),
            RelocInfo::CODE_TARGET);
  }
  
  
  static void EmitWrapCase(MacroAssembler* masm, int argc, Label* cont) {
    // Wrap the receiver and patch it back onto the stack.
    { FrameAndConstantPoolScope frame_scope(masm, StackFrame::INTERNAL);
      __ Push(r1, r3);
      __ InvokeBuiltin(Builtins::TO_OBJECT, CALL_FUNCTION);
      __ pop(r1);
    }
    __ str(r0, MemOperand(sp, argc * kPointerSize));
    __ jmp(cont);
  }
  
  
  static void CallFunctionNoFeedback(MacroAssembler* masm,
                                     int argc, bool needs_checks,
                                     bool call_as_method) {
    // r1 : the function to call
    Label slow, non_function, wrap, cont;
  
    if (needs_checks) {
      // Check that the function is really a JavaScript function.
      // r1: pushed function (to be verified)
      __ JumpIfSmi(r1, &non_function);
  
      // Goto slow case if we do not have a function.
      __ CompareObjectType(r1, r4, r4, JS_FUNCTION_TYPE);
      __ b(ne, &slow);
    }
  
    // Fast-case: Invoke the function now.
    // r1: pushed function
    ParameterCount actual(argc);
  
    if (call_as_method) {
      if (needs_checks) {
        EmitContinueIfStrictOrNative(masm, &cont);
      }
  
      // Compute the receiver in sloppy mode.
      __ ldr(r3, MemOperand(sp, argc * kPointerSize));
  
      if (needs_checks) {
        __ JumpIfSmi(r3, &wrap);
        __ CompareObjectType(r3, r4, r4, FIRST_SPEC_OBJECT_TYPE);
        __ b(lt, &wrap);
      } else {
        __ jmp(&wrap);
      }
  
      __ bind(&cont);
    }
  
    __ InvokeFunction(r1, actual, JUMP_FUNCTION, NullCallWrapper());
  
    if (needs_checks) {
      // Slow-case: Non-function called.
      __ bind(&slow);
      EmitSlowCase(masm, argc, &non_function);
    }
  
    if (call_as_method) {
      __ bind(&wrap);
      EmitWrapCase(masm, argc, &cont);
    }
  }
  
  
  void CallFunctionStub::Generate(MacroAssembler* masm) {
    CallFunctionNoFeedback(masm, argc(), NeedsChecks(), CallAsMethod());
  }
  
  
  void CallConstructStub::Generate(MacroAssembler* masm) {
    // r0 : number of arguments
    // r1 : the function to call
    // r2 : feedback vector
    // r3 : (only if r2 is not the megamorphic symbol) slot in feedback
    //      vector (Smi)
    Label slow, non_function_call;
  
    // Check that the function is not a smi.
    __ JumpIfSmi(r1, &non_function_call);
    // Check that the function is a JSFunction.
    __ CompareObjectType(r1, r4, r4, JS_FUNCTION_TYPE);
    __ b(ne, &slow);
  
    if (RecordCallTarget()) {
      GenerateRecordCallTarget(masm);
  
      __ add(r5, r2, Operand::PointerOffsetFromSmiKey(r3));
      if (FLAG_pretenuring_call_new) {
        // Put the AllocationSite from the feedback vector into r2.
        // By adding kPointerSize we encode that we know the AllocationSite
        // entry is at the feedback vector slot given by r3 + 1.
        __ ldr(r2, FieldMemOperand(r5, FixedArray::kHeaderSize + kPointerSize));
      } else {
        Label feedback_register_initialized;
        // Put the AllocationSite from the feedback vector into r2, or undefined.
        __ ldr(r2, FieldMemOperand(r5, FixedArray::kHeaderSize));
        __ ldr(r5, FieldMemOperand(r2, AllocationSite::kMapOffset));
        __ CompareRoot(r5, Heap::kAllocationSiteMapRootIndex);
        __ b(eq, &feedback_register_initialized);
        __ LoadRoot(r2, Heap::kUndefinedValueRootIndex);
        __ bind(&feedback_register_initialized);
      }
  
      __ AssertUndefinedOrAllocationSite(r2, r5);
    }
  
    // Jump to the function-specific construct stub.
    Register jmp_reg = r4;
    __ ldr(jmp_reg, FieldMemOperand(r1, JSFunction::kSharedFunctionInfoOffset));
    __ ldr(jmp_reg, FieldMemOperand(jmp_reg,
                                    SharedFunctionInfo::kConstructStubOffset));
    __ add(pc, jmp_reg, Operand(Code::kHeaderSize - kHeapObjectTag));
  
    // r0: number of arguments
    // r1: called object
    // r4: object type
    Label do_call;
    __ bind(&slow);
    __ cmp(r4, Operand(JS_FUNCTION_PROXY_TYPE));
    __ b(ne, &non_function_call);
    __ GetBuiltinFunction(r1, Builtins::CALL_FUNCTION_PROXY_AS_CONSTRUCTOR);
    __ jmp(&do_call);
  
    __ bind(&non_function_call);
    __ GetBuiltinFunction(r1, Builtins::CALL_NON_FUNCTION_AS_CONSTRUCTOR);
    __ bind(&do_call);
    // Set expected number of arguments to zero (not changing r0).
    __ mov(r2, Operand::Zero());
    __ Jump(masm->isolate()->builtins()->ArgumentsAdaptorTrampoline(),
            RelocInfo::CODE_TARGET);
  }
  
  
  static void EmitLoadTypeFeedbackVector(MacroAssembler* masm, Register vector) {
    __ ldr(vector, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
    __ ldr(vector, FieldMemOperand(vector,
                                   JSFunction::kSharedFunctionInfoOffset));
    __ ldr(vector, FieldMemOperand(vector,
                                   SharedFunctionInfo::kFeedbackVectorOffset));
  }
  
  
  void CallIC_ArrayStub::Generate(MacroAssembler* masm) {
    // r1 - function
    // r3 - slot id
    Label miss;
    int argc = arg_count();
    ParameterCount actual(argc);
  
    EmitLoadTypeFeedbackVector(masm, r2);
  
    __ LoadGlobalFunction(Context::ARRAY_FUNCTION_INDEX, r4);
    __ cmp(r1, r4);
    __ b(ne, &miss);
  
    __ mov(r0, Operand(arg_count()));
    __ add(r4, r2, Operand::PointerOffsetFromSmiKey(r3));
    __ ldr(r4, FieldMemOperand(r4, FixedArray::kHeaderSize));
  
    // Verify that r4 contains an AllocationSite
    __ ldr(r5, FieldMemOperand(r4, HeapObject::kMapOffset));
    __ CompareRoot(r5, Heap::kAllocationSiteMapRootIndex);
    __ b(ne, &miss);
  
    __ mov(r2, r4);
    ArrayConstructorStub stub(masm->isolate(), arg_count());
    __ TailCallStub(&stub);
  
    __ bind(&miss);
    GenerateMiss(masm);
  
    // The slow case, we need this no matter what to complete a call after a miss.
    CallFunctionNoFeedback(masm,
                           arg_count(),
                           true,
                           CallAsMethod());
  
    // Unreachable.
    __ stop("Unexpected code address");
  }
  
  
  void CallICStub::Generate(MacroAssembler* masm) {
    // r1 - function
    // r3 - slot id (Smi)
    Label extra_checks_or_miss, slow_start;
    Label slow, non_function, wrap, cont;
    Label have_js_function;
    int argc = arg_count();
    ParameterCount actual(argc);
  
    EmitLoadTypeFeedbackVector(masm, r2);
  
    // The checks. First, does r1 match the recorded monomorphic target?
    __ add(r4, r2, Operand::PointerOffsetFromSmiKey(r3));
    __ ldr(r4, FieldMemOperand(r4, FixedArray::kHeaderSize));
    __ cmp(r1, r4);
    __ b(ne, &extra_checks_or_miss);
  
    __ bind(&have_js_function);
    if (CallAsMethod()) {
      EmitContinueIfStrictOrNative(masm, &cont);
      // Compute the receiver in sloppy mode.
      __ ldr(r3, MemOperand(sp, argc * kPointerSize));
  
      __ JumpIfSmi(r3, &wrap);
      __ CompareObjectType(r3, r4, r4, FIRST_SPEC_OBJECT_TYPE);
      __ b(lt, &wrap);
  
      __ bind(&cont);
    }
  
    __ InvokeFunction(r1, actual, JUMP_FUNCTION, NullCallWrapper());
  
    __ bind(&slow);
    EmitSlowCase(masm, argc, &non_function);
  
    if (CallAsMethod()) {
      __ bind(&wrap);
      EmitWrapCase(masm, argc, &cont);
    }
  
    __ bind(&extra_checks_or_miss);
    Label miss;
  
    __ CompareRoot(r4, Heap::kMegamorphicSymbolRootIndex);
    __ b(eq, &slow_start);
    __ CompareRoot(r4, Heap::kUninitializedSymbolRootIndex);
    __ b(eq, &miss);
  
    if (!FLAG_trace_ic) {
      // We are going megamorphic. If the feedback is a JSFunction, it is fine
      // to handle it here. More complex cases are dealt with in the runtime.
      __ AssertNotSmi(r4);
      __ CompareObjectType(r4, r5, r5, JS_FUNCTION_TYPE);
      __ b(ne, &miss);
      __ add(r4, r2, Operand::PointerOffsetFromSmiKey(r3));
      __ LoadRoot(ip, Heap::kMegamorphicSymbolRootIndex);
      __ str(ip, FieldMemOperand(r4, FixedArray::kHeaderSize));
      __ jmp(&slow_start);
    }
  
    // We are here because tracing is on or we are going monomorphic.
    __ bind(&miss);
    GenerateMiss(masm);
  
    // the slow case
    __ bind(&slow_start);
    // Check that the function is really a JavaScript function.
    // r1: pushed function (to be verified)
    __ JumpIfSmi(r1, &non_function);
  
    // Goto slow case if we do not have a function.
    __ CompareObjectType(r1, r4, r4, JS_FUNCTION_TYPE);
    __ b(ne, &slow);
    __ jmp(&have_js_function);
  }
  
  
  void CallICStub::GenerateMiss(MacroAssembler* masm) {
    // Get the receiver of the function from the stack; 1 ~ return address.
    __ ldr(r4, MemOperand(sp, (arg_count() + 1) * kPointerSize));
  
    {
      FrameAndConstantPoolScope scope(masm, StackFrame::INTERNAL);
  
      // Push the receiver and the function and feedback info.
      __ Push(r4, r1, r2, r3);
  
      // Call the entry.
      IC::UtilityId id = GetICState() == DEFAULT ? IC::kCallIC_Miss
                                                 : IC::kCallIC_Customization_Miss;
  
      ExternalReference miss = ExternalReference(IC_Utility(id),
                                                 masm->isolate());
      __ CallExternalReference(miss, 4);
  
      // Move result to edi and exit the internal frame.
      __ mov(r1, r0);
    }
  }
  
  
  // StringCharCodeAtGenerator
  void StringCharCodeAtGenerator::GenerateFast(MacroAssembler* masm) {
    // If the receiver is a smi trigger the non-string case.
    __ JumpIfSmi(object_, receiver_not_string_);
  
    // Fetch the instance type of the receiver into result register.
    __ ldr(result_, FieldMemOperand(object_, HeapObject::kMapOffset));
    __ ldrb(result_, FieldMemOperand(result_, Map::kInstanceTypeOffset));
    // If the receiver is not a string trigger the non-string case.
    __ tst(result_, Operand(kIsNotStringMask));
    __ b(ne, receiver_not_string_);
  
    // If the index is non-smi trigger the non-smi case.
    __ JumpIfNotSmi(index_, &index_not_smi_);
    __ bind(&got_smi_index_);
  
    // Check for index out of range.
    __ ldr(ip, FieldMemOperand(object_, String::kLengthOffset));
    __ cmp(ip, Operand(index_));
    __ b(ls, index_out_of_range_);
  
    __ SmiUntag(index_);
  
    StringCharLoadGenerator::Generate(masm,
                                      object_,
                                      index_,
                                      result_,
                                      &call_runtime_);
  
    __ SmiTag(result_);
    __ bind(&exit_);
  }
  
  
  void StringCharCodeAtGenerator::GenerateSlow(
      MacroAssembler* masm,
      const RuntimeCallHelper& call_helper) {
    __ Abort(kUnexpectedFallthroughToCharCodeAtSlowCase);
  
    // Index is not a smi.
    __ bind(&index_not_smi_);
    // If index is a heap number, try converting it to an integer.
    __ CheckMap(index_,
                result_,
                Heap::kHeapNumberMapRootIndex,
                index_not_number_,
                DONT_DO_SMI_CHECK);
    call_helper.BeforeCall(masm);
    __ push(object_);
    __ push(index_);  // Consumed by runtime conversion function.
    if (index_flags_ == STRING_INDEX_IS_NUMBER) {
      __ CallRuntime(Runtime::kNumberToIntegerMapMinusZero, 1);
    } else {
      DCHECK(index_flags_ == STRING_INDEX_IS_ARRAY_INDEX);
      // NumberToSmi discards numbers that are not exact integers.
      __ CallRuntime(Runtime::kNumberToSmi, 1);
    }
    // Save the conversion result before the pop instructions below
    // have a chance to overwrite it.
    __ Move(index_, r0);
    __ pop(object_);
    // Reload the instance type.
    __ ldr(result_, FieldMemOperand(object_, HeapObject::kMapOffset));
    __ ldrb(result_, FieldMemOperand(result_, Map::kInstanceTypeOffset));
    call_helper.AfterCall(masm);
    // If index is still not a smi, it must be out of range.
    __ JumpIfNotSmi(index_, index_out_of_range_);
    // Otherwise, return to the fast path.
    __ jmp(&got_smi_index_);
  
    // Call runtime. We get here when the receiver is a string and the
    // index is a number, but the code of getting the actual character
    // is too complex (e.g., when the string needs to be flattened).
    __ bind(&call_runtime_);
    call_helper.BeforeCall(masm);
    __ SmiTag(index_);
    __ Push(object_, index_);
    __ CallRuntime(Runtime::kStringCharCodeAtRT, 2);
    __ Move(result_, r0);
    call_helper.AfterCall(masm);
    __ jmp(&exit_);
  
    __ Abort(kUnexpectedFallthroughFromCharCodeAtSlowCase);
  }
  
  
  // -------------------------------------------------------------------------
  // StringCharFromCodeGenerator
  
  void StringCharFromCodeGenerator::GenerateFast(MacroAssembler* masm) {
    // Fast case of Heap::LookupSingleCharacterStringFromCode.
    STATIC_ASSERT(kSmiTag == 0);
    STATIC_ASSERT(kSmiShiftSize == 0);
    DCHECK(base::bits::IsPowerOfTwo32(String::kMaxOneByteCharCode + 1));
    __ tst(code_,
           Operand(kSmiTagMask |
                   ((~String::kMaxOneByteCharCode) << kSmiTagSize)));
    __ b(ne, &slow_case_);
  
    __ LoadRoot(result_, Heap::kSingleCharacterStringCacheRootIndex);
    // At this point code register contains smi tagged one-byte char code.
    __ add(result_, result_, Operand::PointerOffsetFromSmiKey(code_));
    __ ldr(result_, FieldMemOperand(result_, FixedArray::kHeaderSize));
    __ CompareRoot(result_, Heap::kUndefinedValueRootIndex);
    __ b(eq, &slow_case_);
    __ bind(&exit_);
  }
  
  
  void StringCharFromCodeGenerator::GenerateSlow(
      MacroAssembler* masm,
      const RuntimeCallHelper& call_helper) {
    __ Abort(kUnexpectedFallthroughToCharFromCodeSlowCase);
  
    __ bind(&slow_case_);
    call_helper.BeforeCall(masm);
    __ push(code_);
    __ CallRuntime(Runtime::kCharFromCode, 1);
    __ Move(result_, r0);
    call_helper.AfterCall(masm);
    __ jmp(&exit_);
  
    __ Abort(kUnexpectedFallthroughFromCharFromCodeSlowCase);
  }
  
  
  enum CopyCharactersFlags { COPY_ONE_BYTE = 1, DEST_ALWAYS_ALIGNED = 2 };
  
  
  void StringHelper::GenerateCopyCharacters(MacroAssembler* masm,
                                            Register dest,
                                            Register src,
                                            Register count,
                                            Register scratch,
                                            String::Encoding encoding) {
    if (FLAG_debug_code) {
      // Check that destination is word aligned.
      __ tst(dest, Operand(kPointerAlignmentMask));
      __ Check(eq, kDestinationOfCopyNotAligned);
    }
  
    // Assumes word reads and writes are little endian.
    // Nothing to do for zero characters.
    Label done;
    if (encoding == String::TWO_BYTE_ENCODING) {
      __ add(count, count, Operand(count), SetCC);
    }
  
    Register limit = count;  // Read until dest equals this.
    __ add(limit, dest, Operand(count));
  
    Label loop_entry, loop;
    // Copy bytes from src to dest until dest hits limit.
    __ b(&loop_entry);
    __ bind(&loop);
    __ ldrb(scratch, MemOperand(src, 1, PostIndex), lt);
    __ strb(scratch, MemOperand(dest, 1, PostIndex));
    __ bind(&loop_entry);
    __ cmp(dest, Operand(limit));
    __ b(lt, &loop);
  
    __ bind(&done);
  }
  
  
  void SubStringStub::Generate(MacroAssembler* masm) {
    Label runtime;
  
    // Stack frame on entry.
    //  lr: return address
    //  sp[0]: to
    //  sp[4]: from
    //  sp[8]: string
  
    // This stub is called from the native-call %_SubString(...), so
    // nothing can be assumed about the arguments. It is tested that:
    //  "string" is a sequential string,
    //  both "from" and "to" are smis, and
    //  0 <= from <= to <= string.length.
    // If any of these assumptions fail, we call the runtime system.
  
    const int kToOffset = 0 * kPointerSize;
    const int kFromOffset = 1 * kPointerSize;
    const int kStringOffset = 2 * kPointerSize;
  
    __ Ldrd(r2, r3, MemOperand(sp, kToOffset));
    STATIC_ASSERT(kFromOffset == kToOffset + 4);
    STATIC_ASSERT(kSmiTag == 0);
    STATIC_ASSERT(kSmiTagSize + kSmiShiftSize == 1);
  
    // Arithmetic shift right by one un-smi-tags. In this case we rotate right
    // instead because we bail out on non-smi values: ROR and ASR are equivalent
    // for smis but they set the flags in a way that's easier to optimize.
    __ mov(r2, Operand(r2, ROR, 1), SetCC);
    __ mov(r3, Operand(r3, ROR, 1), SetCC, cc);
    // If either to or from had the smi tag bit set, then C is set now, and N
    // has the same value: we rotated by 1, so the bottom bit is now the top bit.
    // We want to bailout to runtime here if From is negative.  In that case, the
    // next instruction is not executed and we fall through to bailing out to
    // runtime.
    // Executed if both r2 and r3 are untagged integers.
    __ sub(r2, r2, Operand(r3), SetCC, cc);
    // One of the above un-smis or the above SUB could have set N==1.
    __ b(mi, &runtime);  // Either "from" or "to" is not an smi, or from > to.
  
    // Make sure first argument is a string.
    __ ldr(r0, MemOperand(sp, kStringOffset));
    __ JumpIfSmi(r0, &runtime);
    Condition is_string = masm->IsObjectStringType(r0, r1);
    __ b(NegateCondition(is_string), &runtime);
  
    Label single_char;
    __ cmp(r2, Operand(1));
    __ b(eq, &single_char);
  
    // Short-cut for the case of trivial substring.
    Label return_r0;
    // r0: original string
    // r2: result string length
    __ ldr(r4, FieldMemOperand(r0, String::kLengthOffset));
    __ cmp(r2, Operand(r4, ASR, 1));
    // Return original string.
    __ b(eq, &return_r0);
    // Longer than original string's length or negative: unsafe arguments.
    __ b(hi, &runtime);
    // Shorter than original string's length: an actual substring.
  
    // Deal with different string types: update the index if necessary
    // and put the underlying string into r5.
    // r0: original string
    // r1: instance type
    // r2: length
    // r3: from index (untagged)
    Label underlying_unpacked, sliced_string, seq_or_external_string;
    // If the string is not indirect, it can only be sequential or external.
    STATIC_ASSERT(kIsIndirectStringMask == (kSlicedStringTag & kConsStringTag));
    STATIC_ASSERT(kIsIndirectStringMask != 0);
    __ tst(r1, Operand(kIsIndirectStringMask));
    __ b(eq, &seq_or_external_string);
  
    __ tst(r1, Operand(kSlicedNotConsMask));
    __ b(ne, &sliced_string);
    // Cons string.  Check whether it is flat, then fetch first part.
    __ ldr(r5, FieldMemOperand(r0, ConsString::kSecondOffset));
    __ CompareRoot(r5, Heap::kempty_stringRootIndex);
    __ b(ne, &runtime);
    __ ldr(r5, FieldMemOperand(r0, ConsString::kFirstOffset));
    // Update instance type.
    __ ldr(r1, FieldMemOperand(r5, HeapObject::kMapOffset));
    __ ldrb(r1, FieldMemOperand(r1, Map::kInstanceTypeOffset));
    __ jmp(&underlying_unpacked);
  
    __ bind(&sliced_string);
    // Sliced string.  Fetch parent and correct start index by offset.
    __ ldr(r5, FieldMemOperand(r0, SlicedString::kParentOffset));
    __ ldr(r4, FieldMemOperand(r0, SlicedString::kOffsetOffset));
    __ add(r3, r3, Operand(r4, ASR, 1));  // Add offset to index.
    // Update instance type.
    __ ldr(r1, FieldMemOperand(r5, HeapObject::kMapOffset));
    __ ldrb(r1, FieldMemOperand(r1, Map::kInstanceTypeOffset));
    __ jmp(&underlying_unpacked);
  
    __ bind(&seq_or_external_string);
    // Sequential or external string.  Just move string to the expected register.
    __ mov(r5, r0);
  
    __ bind(&underlying_unpacked);
  
    if (FLAG_string_slices) {
      Label copy_routine;
      // r5: underlying subject string
      // r1: instance type of underlying subject string
      // r2: length
      // r3: adjusted start index (untagged)
      __ cmp(r2, Operand(SlicedString::kMinLength));
      // Short slice.  Copy instead of slicing.
      __ b(lt, &copy_routine);
      // Allocate new sliced string.  At this point we do not reload the instance
      // type including the string encoding because we simply rely on the info
      // provided by the original string.  It does not matter if the original
      // string's encoding is wrong because we always have to recheck encoding of
      // the newly created string's parent anyways due to externalized strings.
      Label two_byte_slice, set_slice_header;
      STATIC_ASSERT((kStringEncodingMask & kOneByteStringTag) != 0);
      STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
      __ tst(r1, Operand(kStringEncodingMask));
      __ b(eq, &two_byte_slice);
      __ AllocateOneByteSlicedString(r0, r2, r6, r4, &runtime);
      __ jmp(&set_slice_header);
      __ bind(&two_byte_slice);
      __ AllocateTwoByteSlicedString(r0, r2, r6, r4, &runtime);
      __ bind(&set_slice_header);
      __ mov(r3, Operand(r3, LSL, 1));
      __ str(r5, FieldMemOperand(r0, SlicedString::kParentOffset));
      __ str(r3, FieldMemOperand(r0, SlicedString::kOffsetOffset));
      __ jmp(&return_r0);
  
      __ bind(&copy_routine);
    }
  
    // r5: underlying subject string
    // r1: instance type of underlying subject string
    // r2: length
    // r3: adjusted start index (untagged)
    Label two_byte_sequential, sequential_string, allocate_result;
    STATIC_ASSERT(kExternalStringTag != 0);
    STATIC_ASSERT(kSeqStringTag == 0);
    __ tst(r1, Operand(kExternalStringTag));
    __ b(eq, &sequential_string);
  
    // Handle external string.
    // Rule out short external strings.
    STATIC_ASSERT(kShortExternalStringTag != 0);
    __ tst(r1, Operand(kShortExternalStringTag));
    __ b(ne, &runtime);
    __ ldr(r5, FieldMemOperand(r5, ExternalString::kResourceDataOffset));
    // r5 already points to the first character of underlying string.
    __ jmp(&allocate_result);
  
    __ bind(&sequential_string);
    // Locate first character of underlying subject string.
    STATIC_ASSERT(SeqTwoByteString::kHeaderSize == SeqOneByteString::kHeaderSize);
    __ add(r5, r5, Operand(SeqOneByteString::kHeaderSize - kHeapObjectTag));
  
    __ bind(&allocate_result);
    // Sequential acii string.  Allocate the result.
    STATIC_ASSERT((kOneByteStringTag & kStringEncodingMask) != 0);
    __ tst(r1, Operand(kStringEncodingMask));
    __ b(eq, &two_byte_sequential);
  
    // Allocate and copy the resulting one-byte string.
    __ AllocateOneByteString(r0, r2, r4, r6, r1, &runtime);
  
    // Locate first character of substring to copy.
    __ add(r5, r5, r3);
    // Locate first character of result.
    __ add(r1, r0, Operand(SeqOneByteString::kHeaderSize - kHeapObjectTag));
  
    // r0: result string
    // r1: first character of result string
    // r2: result string length
    // r5: first character of substring to copy
    STATIC_ASSERT((SeqOneByteString::kHeaderSize & kObjectAlignmentMask) == 0);
    StringHelper::GenerateCopyCharacters(
        masm, r1, r5, r2, r3, String::ONE_BYTE_ENCODING);
    __ jmp(&return_r0);
  
    // Allocate and copy the resulting two-byte string.
    __ bind(&two_byte_sequential);
    __ AllocateTwoByteString(r0, r2, r4, r6, r1, &runtime);
  
    // Locate first character of substring to copy.
    STATIC_ASSERT(kSmiTagSize == 1 && kSmiTag == 0);
    __ add(r5, r5, Operand(r3, LSL, 1));
    // Locate first character of result.
    __ add(r1, r0, Operand(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
  
    // r0: result string.
    // r1: first character of result.
    // r2: result length.
    // r5: first character of substring to copy.
    STATIC_ASSERT((SeqTwoByteString::kHeaderSize & kObjectAlignmentMask) == 0);
    StringHelper::GenerateCopyCharacters(
        masm, r1, r5, r2, r3, String::TWO_BYTE_ENCODING);
  
    __ bind(&return_r0);
    Counters* counters = isolate()->counters();
    __ IncrementCounter(counters->sub_string_native(), 1, r3, r4);
    __ Drop(3);
    __ Ret();
  
    // Just jump to runtime to create the sub string.
    __ bind(&runtime);
    __ TailCallRuntime(Runtime::kSubString, 3, 1);
  
    __ bind(&single_char);
    // r0: original string
    // r1: instance type
    // r2: length
    // r3: from index (untagged)
    __ SmiTag(r3, r3);
    StringCharAtGenerator generator(
        r0, r3, r2, r0, &runtime, &runtime, &runtime, STRING_INDEX_IS_NUMBER);
    generator.GenerateFast(masm);
    __ Drop(3);
    __ Ret();
    generator.SkipSlow(masm, &runtime);
  }
  
  
  void StringHelper::GenerateFlatOneByteStringEquals(
      MacroAssembler* masm, Register left, Register right, Register scratch1,
      Register scratch2, Register scratch3) {
    Register length = scratch1;
  
    // Compare lengths.
    Label strings_not_equal, check_zero_length;
    __ ldr(length, FieldMemOperand(left, String::kLengthOffset));
    __ ldr(scratch2, FieldMemOperand(right, String::kLengthOffset));
    __ cmp(length, scratch2);
    __ b(eq, &check_zero_length);
    __ bind(&strings_not_equal);
    __ mov(r0, Operand(Smi::FromInt(NOT_EQUAL)));
    __ Ret();
  
    // Check if the length is zero.
    Label compare_chars;
    __ bind(&check_zero_length);
    STATIC_ASSERT(kSmiTag == 0);
    __ cmp(length, Operand::Zero());
    __ b(ne, &compare_chars);
    __ mov(r0, Operand(Smi::FromInt(EQUAL)));
    __ Ret();
  
    // Compare characters.
    __ bind(&compare_chars);
    GenerateOneByteCharsCompareLoop(masm, left, right, length, scratch2, scratch3,
                                    &strings_not_equal);
  
    // Characters are equal.
    __ mov(r0, Operand(Smi::FromInt(EQUAL)));
    __ Ret();
  }
  
  
  void StringHelper::GenerateCompareFlatOneByteStrings(
      MacroAssembler* masm, Register left, Register right, Register scratch1,
      Register scratch2, Register scratch3, Register scratch4) {
    Label result_not_equal, compare_lengths;
    // Find minimum length and length difference.
    __ ldr(scratch1, FieldMemOperand(left, String::kLengthOffset));
    __ ldr(scratch2, FieldMemOperand(right, String::kLengthOffset));
    __ sub(scratch3, scratch1, Operand(scratch2), SetCC);
    Register length_delta = scratch3;
    __ mov(scratch1, scratch2, LeaveCC, gt);
    Register min_length = scratch1;
    STATIC_ASSERT(kSmiTag == 0);
    __ cmp(min_length, Operand::Zero());
    __ b(eq, &compare_lengths);
  
    // Compare loop.
    GenerateOneByteCharsCompareLoop(masm, left, right, min_length, scratch2,
                                    scratch4, &result_not_equal);
  
    // Compare lengths - strings up to min-length are equal.
    __ bind(&compare_lengths);
    DCHECK(Smi::FromInt(EQUAL) == static_cast<Smi*>(0));
    // Use length_delta as result if it's zero.
    __ mov(r0, Operand(length_delta), SetCC);
    __ bind(&result_not_equal);
    // Conditionally update the result based either on length_delta or
    // the last comparion performed in the loop above.
    __ mov(r0, Operand(Smi::FromInt(GREATER)), LeaveCC, gt);
    __ mov(r0, Operand(Smi::FromInt(LESS)), LeaveCC, lt);
    __ Ret();
  }
  
  
  void StringHelper::GenerateOneByteCharsCompareLoop(
      MacroAssembler* masm, Register left, Register right, Register length,
      Register scratch1, Register scratch2, Label* chars_not_equal) {
    // Change index to run from -length to -1 by adding length to string
    // start. This means that loop ends when index reaches zero, which
    // doesn't need an additional compare.
    __ SmiUntag(length);
    __ add(scratch1, length,
           Operand(SeqOneByteString::kHeaderSize - kHeapObjectTag));
    __ add(left, left, Operand(scratch1));
    __ add(right, right, Operand(scratch1));
    __ rsb(length, length, Operand::Zero());
    Register index = length;  // index = -length;
  
    // Compare loop.
    Label loop;
    __ bind(&loop);
    __ ldrb(scratch1, MemOperand(left, index));
    __ ldrb(scratch2, MemOperand(right, index));
    __ cmp(scratch1, scratch2);
    __ b(ne, chars_not_equal);
    __ add(index, index, Operand(1), SetCC);
    __ b(ne, &loop);
  }
  
  
  void StringCompareStub::Generate(MacroAssembler* masm) {
    Label runtime;
  
    Counters* counters = isolate()->counters();
  
    // Stack frame on entry.
    //  sp[0]: right string
    //  sp[4]: left string
    __ Ldrd(r0 , r1, MemOperand(sp));  // Load right in r0, left in r1.
  
    Label not_same;
    __ cmp(r0, r1);
    __ b(ne, &not_same);
    STATIC_ASSERT(EQUAL == 0);
    STATIC_ASSERT(kSmiTag == 0);
    __ mov(r0, Operand(Smi::FromInt(EQUAL)));
    __ IncrementCounter(counters->string_compare_native(), 1, r1, r2);
    __ add(sp, sp, Operand(2 * kPointerSize));
    __ Ret();
  
    __ bind(&not_same);
  
    // Check that both objects are sequential one-byte strings.
    __ JumpIfNotBothSequentialOneByteStrings(r1, r0, r2, r3, &runtime);
  
    // Compare flat one-byte strings natively. Remove arguments from stack first.
    __ IncrementCounter(counters->string_compare_native(), 1, r2, r3);
    __ add(sp, sp, Operand(2 * kPointerSize));
    StringHelper::GenerateCompareFlatOneByteStrings(masm, r1, r0, r2, r3, r4, r5);
  
    // Call the runtime; it returns -1 (less), 0 (equal), or 1 (greater)
    // tagged as a small integer.
    __ bind(&runtime);
    __ TailCallRuntime(Runtime::kStringCompare, 2, 1);
  }
  
  
  void BinaryOpICWithAllocationSiteStub::Generate(MacroAssembler* masm) {
    // ----------- S t a t e -------------
    //  -- r1    : left
    //  -- r0    : right
    //  -- lr    : return address
    // -----------------------------------
  
    // Load r2 with the allocation site.  We stick an undefined dummy value here
    // and replace it with the real allocation site later when we instantiate this
    // stub in BinaryOpICWithAllocationSiteStub::GetCodeCopyFromTemplate().
    __ Move(r2, handle(isolate()->heap()->undefined_value()));
  
    // Make sure that we actually patched the allocation site.
    if (FLAG_debug_code) {
      __ tst(r2, Operand(kSmiTagMask));
      __ Assert(ne, kExpectedAllocationSite);
      __ push(r2);
      __ ldr(r2, FieldMemOperand(r2, HeapObject::kMapOffset));
      __ LoadRoot(ip, Heap::kAllocationSiteMapRootIndex);
      __ cmp(r2, ip);
      __ pop(r2);
      __ Assert(eq, kExpectedAllocationSite);
    }
  
    // Tail call into the stub that handles binary operations with allocation
    // sites.
    BinaryOpWithAllocationSiteStub stub(isolate(), state());
    __ TailCallStub(&stub);
  }
  
  
  void CompareICStub::GenerateSmis(MacroAssembler* masm) {
    DCHECK(state() == CompareICState::SMI);
    Label miss;
    __ orr(r2, r1, r0);
    __ JumpIfNotSmi(r2, &miss);
  
    if (GetCondition() == eq) {
      // For equality we do not care about the sign of the result.
      __ sub(r0, r0, r1, SetCC);
    } else {
      // Untag before subtracting to avoid handling overflow.
      __ SmiUntag(r1);
      __ sub(r0, r1, Operand::SmiUntag(r0));
    }
    __ Ret();
  
    __ bind(&miss);
    GenerateMiss(masm);
  }
  
  
  void CompareICStub::GenerateNumbers(MacroAssembler* masm) {
    DCHECK(state() == CompareICState::NUMBER);
  
    Label generic_stub;
    Label unordered, maybe_undefined1, maybe_undefined2;
    Label miss;
  
    if (left() == CompareICState::SMI) {
      __ JumpIfNotSmi(r1, &miss);
    }
    if (right() == CompareICState::SMI) {
      __ JumpIfNotSmi(r0, &miss);
    }
  
    // Inlining the double comparison and falling back to the general compare
    // stub if NaN is involved.
    // Load left and right operand.
    Label done, left, left_smi, right_smi;
    __ JumpIfSmi(r0, &right_smi);
    __ CheckMap(r0, r2, Heap::kHeapNumberMapRootIndex, &maybe_undefined1,
                DONT_DO_SMI_CHECK);
    __ sub(r2, r0, Operand(kHeapObjectTag));
    __ vldr(d1, r2, HeapNumber::kValueOffset);
    __ b(&left);
    __ bind(&right_smi);
    __ SmiToDouble(d1, r0);
  
    __ bind(&left);
    __ JumpIfSmi(r1, &left_smi);
    __ CheckMap(r1, r2, Heap::kHeapNumberMapRootIndex, &maybe_undefined2,
                DONT_DO_SMI_CHECK);
    __ sub(r2, r1, Operand(kHeapObjectTag));
    __ vldr(d0, r2, HeapNumber::kValueOffset);
    __ b(&done);
    __ bind(&left_smi);
    __ SmiToDouble(d0, r1);
  
    __ bind(&done);
    // Compare operands.
    __ VFPCompareAndSetFlags(d0, d1);
  
    // Don't base result on status bits when a NaN is involved.
    __ b(vs, &unordered);
  
    // Return a result of -1, 0, or 1, based on status bits.
    __ mov(r0, Operand(EQUAL), LeaveCC, eq);
    __ mov(r0, Operand(LESS), LeaveCC, lt);
    __ mov(r0, Operand(GREATER), LeaveCC, gt);
    __ Ret();
  
    __ bind(&unordered);
    __ bind(&generic_stub);
    CompareICStub stub(isolate(), op(), CompareICState::GENERIC,
                       CompareICState::GENERIC, CompareICState::GENERIC);
    __ Jump(stub.GetCode(), RelocInfo::CODE_TARGET);
  
    __ bind(&maybe_undefined1);
    if (Token::IsOrderedRelationalCompareOp(op())) {
      __ CompareRoot(r0, Heap::kUndefinedValueRootIndex);
      __ b(ne, &miss);
      __ JumpIfSmi(r1, &unordered);
      __ CompareObjectType(r1, r2, r2, HEAP_NUMBER_TYPE);
      __ b(ne, &maybe_undefined2);
      __ jmp(&unordered);
    }
  
    __ bind(&maybe_undefined2);
    if (Token::IsOrderedRelationalCompareOp(op())) {
      __ CompareRoot(r1, Heap::kUndefinedValueRootIndex);
      __ b(eq, &unordered);
    }
  
    __ bind(&miss);
    GenerateMiss(masm);
  }
  
  
  void CompareICStub::GenerateInternalizedStrings(MacroAssembler* masm) {
    DCHECK(state() == CompareICState::INTERNALIZED_STRING);
    Label miss;
  
    // Registers containing left and right operands respectively.
    Register left = r1;
    Register right = r0;
    Register tmp1 = r2;
    Register tmp2 = r3;
  
    // Check that both operands are heap objects.
    __ JumpIfEitherSmi(left, right, &miss);
  
    // Check that both operands are internalized strings.
    __ ldr(tmp1, FieldMemOperand(left, HeapObject::kMapOffset));
    __ ldr(tmp2, FieldMemOperand(right, HeapObject::kMapOffset));
    __ ldrb(tmp1, FieldMemOperand(tmp1, Map::kInstanceTypeOffset));
    __ ldrb(tmp2, FieldMemOperand(tmp2, Map::kInstanceTypeOffset));
    STATIC_ASSERT(kInternalizedTag == 0 && kStringTag == 0);
    __ orr(tmp1, tmp1, Operand(tmp2));
    __ tst(tmp1, Operand(kIsNotStringMask | kIsNotInternalizedMask));
    __ b(ne, &miss);
  
    // Internalized strings are compared by identity.
    __ cmp(left, right);
    // Make sure r0 is non-zero. At this point input operands are
    // guaranteed to be non-zero.
    DCHECK(right.is(r0));
    STATIC_ASSERT(EQUAL == 0);
    STATIC_ASSERT(kSmiTag == 0);
    __ mov(r0, Operand(Smi::FromInt(EQUAL)), LeaveCC, eq);
    __ Ret();
  
    __ bind(&miss);
    GenerateMiss(masm);
  }
  
  
  void CompareICStub::GenerateUniqueNames(MacroAssembler* masm) {
    DCHECK(state() == CompareICState::UNIQUE_NAME);
    DCHECK(GetCondition() == eq);
    Label miss;
  
    // Registers containing left and right operands respectively.
    Register left = r1;
    Register right = r0;
    Register tmp1 = r2;
    Register tmp2 = r3;
  
    // Check that both operands are heap objects.
    __ JumpIfEitherSmi(left, right, &miss);
  
    // Check that both operands are unique names. This leaves the instance
    // types loaded in tmp1 and tmp2.
    __ ldr(tmp1, FieldMemOperand(left, HeapObject::kMapOffset));
    __ ldr(tmp2, FieldMemOperand(right, HeapObject::kMapOffset));
    __ ldrb(tmp1, FieldMemOperand(tmp1, Map::kInstanceTypeOffset));
    __ ldrb(tmp2, FieldMemOperand(tmp2, Map::kInstanceTypeOffset));
  
    __ JumpIfNotUniqueNameInstanceType(tmp1, &miss);
    __ JumpIfNotUniqueNameInstanceType(tmp2, &miss);
  
    // Unique names are compared by identity.
    __ cmp(left, right);
    // Make sure r0 is non-zero. At this point input operands are
    // guaranteed to be non-zero.
    DCHECK(right.is(r0));
    STATIC_ASSERT(EQUAL == 0);
    STATIC_ASSERT(kSmiTag == 0);
    __ mov(r0, Operand(Smi::FromInt(EQUAL)), LeaveCC, eq);
    __ Ret();
  
    __ bind(&miss);
    GenerateMiss(masm);
  }
  
  
  void CompareICStub::GenerateStrings(MacroAssembler* masm) {
    DCHECK(state() == CompareICState::STRING);
    Label miss;
  
    bool equality = Token::IsEqualityOp(op());
  
    // Registers containing left and right operands respectively.
    Register left = r1;
    Register right = r0;
    Register tmp1 = r2;
    Register tmp2 = r3;
    Register tmp3 = r4;
    Register tmp4 = r5;
  
    // Check that both operands are heap objects.
    __ JumpIfEitherSmi(left, right, &miss);
  
    // Check that both operands are strings. This leaves the instance
    // types loaded in tmp1 and tmp2.
    __ ldr(tmp1, FieldMemOperand(left, HeapObject::kMapOffset));
    __ ldr(tmp2, FieldMemOperand(right, HeapObject::kMapOffset));
    __ ldrb(tmp1, FieldMemOperand(tmp1, Map::kInstanceTypeOffset));
    __ ldrb(tmp2, FieldMemOperand(tmp2, Map::kInstanceTypeOffset));
    STATIC_ASSERT(kNotStringTag != 0);
    __ orr(tmp3, tmp1, tmp2);
    __ tst(tmp3, Operand(kIsNotStringMask));
    __ b(ne, &miss);
  
    // Fast check for identical strings.
    __ cmp(left, right);
    STATIC_ASSERT(EQUAL == 0);
    STATIC_ASSERT(kSmiTag == 0);
    __ mov(r0, Operand(Smi::FromInt(EQUAL)), LeaveCC, eq);
    __ Ret(eq);
  
    // Handle not identical strings.
  
    // Check that both strings are internalized strings. If they are, we're done
    // because we already know they are not identical. We know they are both
    // strings.
    if (equality) {
      DCHECK(GetCondition() == eq);
      STATIC_ASSERT(kInternalizedTag == 0);
      __ orr(tmp3, tmp1, Operand(tmp2));
      __ tst(tmp3, Operand(kIsNotInternalizedMask));
      // Make sure r0 is non-zero. At this point input operands are
      // guaranteed to be non-zero.
      DCHECK(right.is(r0));
      __ Ret(eq);
    }
  
    // Check that both strings are sequential one-byte.
    Label runtime;
    __ JumpIfBothInstanceTypesAreNotSequentialOneByte(tmp1, tmp2, tmp3, tmp4,
                                                      &runtime);
  
    // Compare flat one-byte strings. Returns when done.
    if (equality) {
      StringHelper::GenerateFlatOneByteStringEquals(masm, left, right, tmp1, tmp2,
                                                    tmp3);
    } else {
      StringHelper::GenerateCompareFlatOneByteStrings(masm, left, right, tmp1,
                                                      tmp2, tmp3, tmp4);
    }
  
    // Handle more complex cases in runtime.
    __ bind(&runtime);
    __ Push(left, right);
    if (equality) {
      __ TailCallRuntime(Runtime::kStringEquals, 2, 1);
    } else {
      __ TailCallRuntime(Runtime::kStringCompare, 2, 1);
    }
  
    __ bind(&miss);
    GenerateMiss(masm);
  }
  
  
  void CompareICStub::GenerateObjects(MacroAssembler* masm) {
    DCHECK(state() == CompareICState::OBJECT);
    Label miss;
    __ and_(r2, r1, Operand(r0));
    __ JumpIfSmi(r2, &miss);
  
    __ CompareObjectType(r0, r2, r2, JS_OBJECT_TYPE);
    __ b(ne, &miss);
    __ CompareObjectType(r1, r2, r2, JS_OBJECT_TYPE);
    __ b(ne, &miss);
  
    DCHECK(GetCondition() == eq);
    __ sub(r0, r0, Operand(r1));
    __ Ret();
  
    __ bind(&miss);
    GenerateMiss(masm);
  }
  
  
  void CompareICStub::GenerateKnownObjects(MacroAssembler* masm) {
    Label miss;
    __ and_(r2, r1, Operand(r0));
    __ JumpIfSmi(r2, &miss);
    __ ldr(r2, FieldMemOperand(r0, HeapObject::kMapOffset));
    __ ldr(r3, FieldMemOperand(r1, HeapObject::kMapOffset));
    __ cmp(r2, Operand(known_map_));
    __ b(ne, &miss);
    __ cmp(r3, Operand(known_map_));
    __ b(ne, &miss);
  
    __ sub(r0, r0, Operand(r1));
    __ Ret();
  
    __ bind(&miss);
    GenerateMiss(masm);
  }
  
  
  void CompareICStub::GenerateMiss(MacroAssembler* masm) {
    {
      // Call the runtime system in a fresh internal frame.
      ExternalReference miss =
          ExternalReference(IC_Utility(IC::kCompareIC_Miss), isolate());
  
      FrameAndConstantPoolScope scope(masm, StackFrame::INTERNAL);
      __ Push(r1, r0);
      __ Push(lr, r1, r0);
      __ mov(ip, Operand(Smi::FromInt(op())));
      __ push(ip);
      __ CallExternalReference(miss, 3);
      // Compute the entry point of the rewritten stub.
      __ add(r2, r0, Operand(Code::kHeaderSize - kHeapObjectTag));
      // Restore registers.
      __ pop(lr);
      __ Pop(r1, r0);
    }
  
    __ Jump(r2);
  }
  
  
  void DirectCEntryStub::Generate(MacroAssembler* masm) {
    // Place the return address on the stack, making the call
    // GC safe. The RegExp backend also relies on this.
    __ str(lr, MemOperand(sp, 0));
    __ blx(ip);  // Call the C++ function.
    __ VFPEnsureFPSCRState(r2);
    __ ldr(pc, MemOperand(sp, 0));
  }
  
  
  void DirectCEntryStub::GenerateCall(MacroAssembler* masm,
                                      Register target) {
    intptr_t code =
        reinterpret_cast<intptr_t>(GetCode().location());
    __ Move(ip, target);
    __ mov(lr, Operand(code, RelocInfo::CODE_TARGET));
    __ blx(lr);  // Call the stub.
  }
  
  
  void NameDictionaryLookupStub::GenerateNegativeLookup(MacroAssembler* masm,
                                                        Label* miss,
                                                        Label* done,
                                                        Register receiver,
                                                        Register properties,
                                                        Handle<Name> name,
                                                        Register scratch0) {
    DCHECK(name->IsUniqueName());
    // If names of slots in range from 1 to kProbes - 1 for the hash value are
    // not equal to the name and kProbes-th slot is not used (its name is the
    // undefined value), it guarantees the hash table doesn't contain the
    // property. It's true even if some slots represent deleted properties
    // (their names are the hole value).
    for (int i = 0; i < kInlinedProbes; i++) {
      // scratch0 points to properties hash.
      // Compute the masked index: (hash + i + i * i) & mask.
      Register index = scratch0;
      // Capacity is smi 2^n.
      __ ldr(index, FieldMemOperand(properties, kCapacityOffset));
      __ sub(index, index, Operand(1));
      __ and_(index, index, Operand(
          Smi::FromInt(name->Hash() + NameDictionary::GetProbeOffset(i))));
  
      // Scale the index by multiplying by the entry size.
      DCHECK(NameDictionary::kEntrySize == 3);
      __ add(index, index, Operand(index, LSL, 1));  // index *= 3.
  
      Register entity_name = scratch0;
      // Having undefined at this place means the name is not contained.
      DCHECK_EQ(kSmiTagSize, 1);
      Register tmp = properties;
      __ add(tmp, properties, Operand(index, LSL, 1));
      __ ldr(entity_name, FieldMemOperand(tmp, kElementsStartOffset));
  
      DCHECK(!tmp.is(entity_name));
      __ LoadRoot(tmp, Heap::kUndefinedValueRootIndex);
      __ cmp(entity_name, tmp);
      __ b(eq, done);
  
      // Load the hole ready for use below:
      __ LoadRoot(tmp, Heap::kTheHoleValueRootIndex);
  
      // Stop if found the property.
      __ cmp(entity_name, Operand(Handle<Name>(name)));
      __ b(eq, miss);
  
      Label good;
      __ cmp(entity_name, tmp);
      __ b(eq, &good);
  
      // Check if the entry name is not a unique name.
      __ ldr(entity_name, FieldMemOperand(entity_name, HeapObject::kMapOffset));
      __ ldrb(entity_name,
              FieldMemOperand(entity_name, Map::kInstanceTypeOffset));
      __ JumpIfNotUniqueNameInstanceType(entity_name, miss);
      __ bind(&good);
  
      // Restore the properties.
      __ ldr(properties,
             FieldMemOperand(receiver, JSObject::kPropertiesOffset));
    }
  
    const int spill_mask =
        (lr.bit() | r6.bit() | r5.bit() | r4.bit() | r3.bit() |
         r2.bit() | r1.bit() | r0.bit());
  
    __ stm(db_w, sp, spill_mask);
    __ ldr(r0, FieldMemOperand(receiver, JSObject::kPropertiesOffset));
    __ mov(r1, Operand(Handle<Name>(name)));
    NameDictionaryLookupStub stub(masm->isolate(), NEGATIVE_LOOKUP);
    __ CallStub(&stub);
    __ cmp(r0, Operand::Zero());
    __ ldm(ia_w, sp, spill_mask);
  
    __ b(eq, done);
    __ b(ne, miss);
  }
  
  
  // Probe the name dictionary in the |elements| register. Jump to the
  // |done| label if a property with the given name is found. Jump to
  // the |miss| label otherwise.
  // If lookup was successful |scratch2| will be equal to elements + 4 * index.
  void NameDictionaryLookupStub::GeneratePositiveLookup(MacroAssembler* masm,
                                                        Label* miss,
                                                        Label* done,
                                                        Register elements,
                                                        Register name,
                                                        Register scratch1,
                                                        Register scratch2) {
    DCHECK(!elements.is(scratch1));
    DCHECK(!elements.is(scratch2));
    DCHECK(!name.is(scratch1));
    DCHECK(!name.is(scratch2));
  
    __ AssertName(name);
  
    // Compute the capacity mask.
    __ ldr(scratch1, FieldMemOperand(elements, kCapacityOffset));
    __ SmiUntag(scratch1);
    __ sub(scratch1, scratch1, Operand(1));
  
    // Generate an unrolled loop that performs a few probes before
    // giving up. Measurements done on Gmail indicate that 2 probes
    // cover ~93% of loads from dictionaries.
    for (int i = 0; i < kInlinedProbes; i++) {
      // Compute the masked index: (hash + i + i * i) & mask.
      __ ldr(scratch2, FieldMemOperand(name, Name::kHashFieldOffset));
      if (i > 0) {
        // Add the probe offset (i + i * i) left shifted to avoid right shifting
        // the hash in a separate instruction. The value hash + i + i * i is right
        // shifted in the following and instruction.
        DCHECK(NameDictionary::GetProbeOffset(i) <
               1 << (32 - Name::kHashFieldOffset));
        __ add(scratch2, scratch2, Operand(
            NameDictionary::GetProbeOffset(i) << Name::kHashShift));
      }
      __ and_(scratch2, scratch1, Operand(scratch2, LSR, Name::kHashShift));
  
      // Scale the index by multiplying by the element size.
      DCHECK(NameDictionary::kEntrySize == 3);
      // scratch2 = scratch2 * 3.
      __ add(scratch2, scratch2, Operand(scratch2, LSL, 1));
  
      // Check if the key is identical to the name.
      __ add(scratch2, elements, Operand(scratch2, LSL, 2));
      __ ldr(ip, FieldMemOperand(scratch2, kElementsStartOffset));
      __ cmp(name, Operand(ip));
      __ b(eq, done);
    }
  
    const int spill_mask =
        (lr.bit() | r6.bit() | r5.bit() | r4.bit() |
         r3.bit() | r2.bit() | r1.bit() | r0.bit()) &
        ~(scratch1.bit() | scratch2.bit());
  
    __ stm(db_w, sp, spill_mask);
    if (name.is(r0)) {
      DCHECK(!elements.is(r1));
      __ Move(r1, name);
      __ Move(r0, elements);
    } else {
      __ Move(r0, elements);
      __ Move(r1, name);
    }
    NameDictionaryLookupStub stub(masm->isolate(), POSITIVE_LOOKUP);
    __ CallStub(&stub);
    __ cmp(r0, Operand::Zero());
    __ mov(scratch2, Operand(r2));
    __ ldm(ia_w, sp, spill_mask);
  
    __ b(ne, done);
    __ b(eq, miss);
  }
  
  
  void NameDictionaryLookupStub::Generate(MacroAssembler* masm) {
    // This stub overrides SometimesSetsUpAFrame() to return false.  That means
    // we cannot call anything that could cause a GC from this stub.
    // Registers:
    //  result: NameDictionary to probe
    //  r1: key
    //  dictionary: NameDictionary to probe.
    //  index: will hold an index of entry if lookup is successful.
    //         might alias with result_.
    // Returns:
    //  result_ is zero if lookup failed, non zero otherwise.
  
    Register result = r0;
    Register dictionary = r0;
    Register key = r1;
    Register index = r2;
    Register mask = r3;
    Register hash = r4;
    Register undefined = r5;
    Register entry_key = r6;
  
    Label in_dictionary, maybe_in_dictionary, not_in_dictionary;
  
    __ ldr(mask, FieldMemOperand(dictionary, kCapacityOffset));
    __ SmiUntag(mask);
    __ sub(mask, mask, Operand(1));
  
    __ ldr(hash, FieldMemOperand(key, Name::kHashFieldOffset));
  
    __ LoadRoot(undefined, Heap::kUndefinedValueRootIndex);
  
    for (int i = kInlinedProbes; i < kTotalProbes; i++) {
      // Compute the masked index: (hash + i + i * i) & mask.
      // Capacity is smi 2^n.
      if (i > 0) {
        // Add the probe offset (i + i * i) left shifted to avoid right shifting
        // the hash in a separate instruction. The value hash + i + i * i is right
        // shifted in the following and instruction.
        DCHECK(NameDictionary::GetProbeOffset(i) <
               1 << (32 - Name::kHashFieldOffset));
        __ add(index, hash, Operand(
            NameDictionary::GetProbeOffset(i) << Name::kHashShift));
      } else {
        __ mov(index, Operand(hash));
      }
      __ and_(index, mask, Operand(index, LSR, Name::kHashShift));
  
      // Scale the index by multiplying by the entry size.
      DCHECK(NameDictionary::kEntrySize == 3);
      __ add(index, index, Operand(index, LSL, 1));  // index *= 3.
  
      DCHECK_EQ(kSmiTagSize, 1);
      __ add(index, dictionary, Operand(index, LSL, 2));
      __ ldr(entry_key, FieldMemOperand(index, kElementsStartOffset));
  
      // Having undefined at this place means the name is not contained.
      __ cmp(entry_key, Operand(undefined));
      __ b(eq, &not_in_dictionary);
  
      // Stop if found the property.
      __ cmp(entry_key, Operand(key));
      __ b(eq, &in_dictionary);
  
      if (i != kTotalProbes - 1 && mode() == NEGATIVE_LOOKUP) {
        // Check if the entry name is not a unique name.
        __ ldr(entry_key, FieldMemOperand(entry_key, HeapObject::kMapOffset));
        __ ldrb(entry_key,
                FieldMemOperand(entry_key, Map::kInstanceTypeOffset));
        __ JumpIfNotUniqueNameInstanceType(entry_key, &maybe_in_dictionary);
      }
    }
  
    __ bind(&maybe_in_dictionary);
    // If we are doing negative lookup then probing failure should be
    // treated as a lookup success. For positive lookup probing failure
    // should be treated as lookup failure.
    if (mode() == POSITIVE_LOOKUP) {
      __ mov(result, Operand::Zero());
      __ Ret();
    }
  
    __ bind(&in_dictionary);
    __ mov(result, Operand(1));
    __ Ret();
  
    __ bind(&not_in_dictionary);
    __ mov(result, Operand::Zero());
    __ Ret();
  }
  
  
  void StoreBufferOverflowStub::GenerateFixedRegStubsAheadOfTime(
      Isolate* isolate) {
    StoreBufferOverflowStub stub1(isolate, kDontSaveFPRegs);
    stub1.GetCode();
    // Hydrogen code stubs need stub2 at snapshot time.
    StoreBufferOverflowStub stub2(isolate, kSaveFPRegs);
    stub2.GetCode();
  }
  
  
  // Takes the input in 3 registers: address_ value_ and object_.  A pointer to
  // the value has just been written into the object, now this stub makes sure
  // we keep the GC informed.  The word in the object where the value has been
  // written is in the address register.
  void RecordWriteStub::Generate(MacroAssembler* masm) {
    Label skip_to_incremental_noncompacting;
    Label skip_to_incremental_compacting;
  
    // The first two instructions are generated with labels so as to get the
    // offset fixed up correctly by the bind(Label*) call.  We patch it back and
    // forth between a compare instructions (a nop in this position) and the
    // real branch when we start and stop incremental heap marking.
    // See RecordWriteStub::Patch for details.
    {
      // Block literal pool emission, as the position of these two instructions
      // is assumed by the patching code.
      Assembler::BlockConstPoolScope block_const_pool(masm);
      __ b(&skip_to_incremental_noncompacting);
      __ b(&skip_to_incremental_compacting);
    }
  
    if (remembered_set_action() == EMIT_REMEMBERED_SET) {
      __ RememberedSetHelper(object(), address(), value(), save_fp_regs_mode(),
                             MacroAssembler::kReturnAtEnd);
    }
    __ Ret();
  
    __ bind(&skip_to_incremental_noncompacting);
    GenerateIncremental(masm, INCREMENTAL);
  
    __ bind(&skip_to_incremental_compacting);
    GenerateIncremental(masm, INCREMENTAL_COMPACTION);
  
    // Initial mode of the stub is expected to be STORE_BUFFER_ONLY.
    // Will be checked in IncrementalMarking::ActivateGeneratedStub.
    DCHECK(Assembler::GetBranchOffset(masm->instr_at(0)) < (1 << 12));
    DCHECK(Assembler::GetBranchOffset(masm->instr_at(4)) < (1 << 12));
    PatchBranchIntoNop(masm, 0);
    PatchBranchIntoNop(masm, Assembler::kInstrSize);
  }
  
  
  void RecordWriteStub::GenerateIncremental(MacroAssembler* masm, Mode mode) {
    regs_.Save(masm);
  
    if (remembered_set_action() == EMIT_REMEMBERED_SET) {
      Label dont_need_remembered_set;
  
      __ ldr(regs_.scratch0(), MemOperand(regs_.address(), 0));
      __ JumpIfNotInNewSpace(regs_.scratch0(),  // Value.
                             regs_.scratch0(),
                             &dont_need_remembered_set);
  
      __ CheckPageFlag(regs_.object(),
                       regs_.scratch0(),
                       1 << MemoryChunk::SCAN_ON_SCAVENGE,
                       ne,
                       &dont_need_remembered_set);
  
      // First notify the incremental marker if necessary, then update the
      // remembered set.
      CheckNeedsToInformIncrementalMarker(
          masm, kUpdateRememberedSetOnNoNeedToInformIncrementalMarker, mode);
      InformIncrementalMarker(masm);
      regs_.Restore(masm);
      __ RememberedSetHelper(object(), address(), value(), save_fp_regs_mode(),
                             MacroAssembler::kReturnAtEnd);
  
      __ bind(&dont_need_remembered_set);
    }
  
    CheckNeedsToInformIncrementalMarker(
        masm, kReturnOnNoNeedToInformIncrementalMarker, mode);
    InformIncrementalMarker(masm);
    regs_.Restore(masm);
    __ Ret();
  }
  
  
  void RecordWriteStub::InformIncrementalMarker(MacroAssembler* masm) {
    regs_.SaveCallerSaveRegisters(masm, save_fp_regs_mode());
    int argument_count = 3;
    __ PrepareCallCFunction(argument_count, regs_.scratch0());
    Register address =
        r0.is(regs_.address()) ? regs_.scratch0() : regs_.address();
    DCHECK(!address.is(regs_.object()));
    DCHECK(!address.is(r0));
    __ Move(address, regs_.address());
    __ Move(r0, regs_.object());
    __ Move(r1, address);
    __ mov(r2, Operand(ExternalReference::isolate_address(isolate())));
  
    AllowExternalCallThatCantCauseGC scope(masm);
    __ CallCFunction(
        ExternalReference::incremental_marking_record_write_function(isolate()),
        argument_count);
    regs_.RestoreCallerSaveRegisters(masm, save_fp_regs_mode());
  }
  
  
  void RecordWriteStub::CheckNeedsToInformIncrementalMarker(
      MacroAssembler* masm,
      OnNoNeedToInformIncrementalMarker on_no_need,
      Mode mode) {
    Label on_black;
    Label need_incremental;
    Label need_incremental_pop_scratch;
  
    __ and_(regs_.scratch0(), regs_.object(), Operand(~Page::kPageAlignmentMask));
    __ ldr(regs_.scratch1(),
           MemOperand(regs_.scratch0(),
                      MemoryChunk::kWriteBarrierCounterOffset));
    __ sub(regs_.scratch1(), regs_.scratch1(), Operand(1), SetCC);
    __ str(regs_.scratch1(),
           MemOperand(regs_.scratch0(),
                      MemoryChunk::kWriteBarrierCounterOffset));
    __ b(mi, &need_incremental);
  
    // Let's look at the color of the object:  If it is not black we don't have
    // to inform the incremental marker.
    __ JumpIfBlack(regs_.object(), regs_.scratch0(), regs_.scratch1(), &on_black);
  
    regs_.Restore(masm);
    if (on_no_need == kUpdateRememberedSetOnNoNeedToInformIncrementalMarker) {
      __ RememberedSetHelper(object(), address(), value(), save_fp_regs_mode(),
                             MacroAssembler::kReturnAtEnd);
    } else {
      __ Ret();
    }
  
    __ bind(&on_black);
  
    // Get the value from the slot.
    __ ldr(regs_.scratch0(), MemOperand(regs_.address(), 0));
  
    if (mode == INCREMENTAL_COMPACTION) {
      Label ensure_not_white;
  
      __ CheckPageFlag(regs_.scratch0(),  // Contains value.
                       regs_.scratch1(),  // Scratch.
                       MemoryChunk::kEvacuationCandidateMask,
                       eq,
                       &ensure_not_white);
  
      __ CheckPageFlag(regs_.object(),
                       regs_.scratch1(),  // Scratch.
                       MemoryChunk::kSkipEvacuationSlotsRecordingMask,
                       eq,
                       &need_incremental);
  
      __ bind(&ensure_not_white);
    }
  
    // We need extra registers for this, so we push the object and the address
    // register temporarily.
    __ Push(regs_.object(), regs_.address());
    __ EnsureNotWhite(regs_.scratch0(),  // The value.
                      regs_.scratch1(),  // Scratch.
                      regs_.object(),  // Scratch.
                      regs_.address(),  // Scratch.
                      &need_incremental_pop_scratch);
    __ Pop(regs_.object(), regs_.address());
  
    regs_.Restore(masm);
    if (on_no_need == kUpdateRememberedSetOnNoNeedToInformIncrementalMarker) {
      __ RememberedSetHelper(object(), address(), value(), save_fp_regs_mode(),
                             MacroAssembler::kReturnAtEnd);
    } else {
      __ Ret();
    }
  
    __ bind(&need_incremental_pop_scratch);
    __ Pop(regs_.object(), regs_.address());
  
    __ bind(&need_incremental);
  
    // Fall through when we need to inform the incremental marker.
  }
  
  
  void StoreArrayLiteralElementStub::Generate(MacroAssembler* masm) {
    // ----------- S t a t e -------------
    //  -- r0    : element value to store
    //  -- r3    : element index as smi
    //  -- sp[0] : array literal index in function as smi
    //  -- sp[4] : array literal
    // clobbers r1, r2, r4
    // -----------------------------------
  
    Label element_done;
    Label double_elements;
    Label smi_element;
    Label slow_elements;
    Label fast_elements;
  
    // Get array literal index, array literal and its map.
    __ ldr(r4, MemOperand(sp, 0 * kPointerSize));
    __ ldr(r1, MemOperand(sp, 1 * kPointerSize));
    __ ldr(r2, FieldMemOperand(r1, JSObject::kMapOffset));
  
    __ CheckFastElements(r2, r5, &double_elements);
    // FAST_*_SMI_ELEMENTS or FAST_*_ELEMENTS
    __ JumpIfSmi(r0, &smi_element);
    __ CheckFastSmiElements(r2, r5, &fast_elements);
  
    // Store into the array literal requires a elements transition. Call into
    // the runtime.
    __ bind(&slow_elements);
    // call.
    __ Push(r1, r3, r0);
    __ ldr(r5, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
    __ ldr(r5, FieldMemOperand(r5, JSFunction::kLiteralsOffset));
    __ Push(r5, r4);
    __ TailCallRuntime(Runtime::kStoreArrayLiteralElement, 5, 1);
  
    // Array literal has ElementsKind of FAST_*_ELEMENTS and value is an object.
    __ bind(&fast_elements);
    __ ldr(r5, FieldMemOperand(r1, JSObject::kElementsOffset));
    __ add(r6, r5, Operand::PointerOffsetFromSmiKey(r3));
    __ add(r6, r6, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
    __ str(r0, MemOperand(r6, 0));
    // Update the write barrier for the array store.
    __ RecordWrite(r5, r6, r0, kLRHasNotBeenSaved, kDontSaveFPRegs,
                   EMIT_REMEMBERED_SET, OMIT_SMI_CHECK);
    __ Ret();
  
    // Array literal has ElementsKind of FAST_*_SMI_ELEMENTS or FAST_*_ELEMENTS,
    // and value is Smi.
    __ bind(&smi_element);
    __ ldr(r5, FieldMemOperand(r1, JSObject::kElementsOffset));
    __ add(r6, r5, Operand::PointerOffsetFromSmiKey(r3));
    __ str(r0, FieldMemOperand(r6, FixedArray::kHeaderSize));
    __ Ret();
  
    // Array literal has ElementsKind of FAST_DOUBLE_ELEMENTS.
    __ bind(&double_elements);
    __ ldr(r5, FieldMemOperand(r1, JSObject::kElementsOffset));
    __ StoreNumberToDoubleElements(r0, r3, r5, r6, d0, &slow_elements);
    __ Ret();
  }
  
  
  void StubFailureTrampolineStub::Generate(MacroAssembler* masm) {
    CEntryStub ces(isolate(), 1, kSaveFPRegs);
    __ Call(ces.GetCode(), RelocInfo::CODE_TARGET);
    int parameter_count_offset =
        StubFailureTrampolineFrame::kCallerStackParameterCountFrameOffset;
    __ ldr(r1, MemOperand(fp, parameter_count_offset));
    if (function_mode() == JS_FUNCTION_STUB_MODE) {
      __ add(r1, r1, Operand(1));
    }
    masm->LeaveFrame(StackFrame::STUB_FAILURE_TRAMPOLINE);
    __ mov(r1, Operand(r1, LSL, kPointerSizeLog2));
    __ add(sp, sp, r1);
    __ Ret();
  }
  
  
  void LoadICTrampolineStub::Generate(MacroAssembler* masm) {
    EmitLoadTypeFeedbackVector(masm, VectorLoadICDescriptor::VectorRegister());
    VectorLoadStub stub(isolate(), state());
    __ Jump(stub.GetCode(), RelocInfo::CODE_TARGET);
  }
  
  
  void KeyedLoadICTrampolineStub::Generate(MacroAssembler* masm) {
    EmitLoadTypeFeedbackVector(masm, VectorLoadICDescriptor::VectorRegister());
    VectorKeyedLoadStub stub(isolate());
    __ Jump(stub.GetCode(), RelocInfo::CODE_TARGET);
  }
  
  
  void ProfileEntryHookStub::MaybeCallEntryHook(MacroAssembler* masm) {
    if (masm->isolate()->function_entry_hook() != NULL) {
      ProfileEntryHookStub stub(masm->isolate());
      int code_size = masm->CallStubSize(&stub) + 2 * Assembler::kInstrSize;
      PredictableCodeSizeScope predictable(masm, code_size);
      __ push(lr);
      __ CallStub(&stub);
      __ pop(lr);
    }
  }
  
  
  void ProfileEntryHookStub::Generate(MacroAssembler* masm) {
    // The entry hook is a "push lr" instruction, followed by a call.
    const int32_t kReturnAddressDistanceFromFunctionStart =
        3 * Assembler::kInstrSize;
  
    // This should contain all kCallerSaved registers.
    const RegList kSavedRegs =
        1 <<  0 |  // r0
        1 <<  1 |  // r1
        1 <<  2 |  // r2
        1 <<  3 |  // r3
        1 <<  5 |  // r5
        1 <<  9;   // r9
    // We also save lr, so the count here is one higher than the mask indicates.
    const int32_t kNumSavedRegs = 7;
  
    DCHECK((kCallerSaved & kSavedRegs) == kCallerSaved);
  
    // Save all caller-save registers as this may be called from anywhere.
    __ stm(db_w, sp, kSavedRegs | lr.bit());
  
    // Compute the function's address for the first argument.
    __ sub(r0, lr, Operand(kReturnAddressDistanceFromFunctionStart));
  
    // The caller's return address is above the saved temporaries.
    // Grab that for the second argument to the hook.
    __ add(r1, sp, Operand(kNumSavedRegs * kPointerSize));
  
    // Align the stack if necessary.
    int frame_alignment = masm->ActivationFrameAlignment();
    if (frame_alignment > kPointerSize) {
      __ mov(r5, sp);
      DCHECK(base::bits::IsPowerOfTwo32(frame_alignment));
      __ and_(sp, sp, Operand(-frame_alignment));
    }
  
  #if V8_HOST_ARCH_ARM
    int32_t entry_hook =
        reinterpret_cast<int32_t>(isolate()->function_entry_hook());
    __ mov(ip, Operand(entry_hook));
  #else
    // Under the simulator we need to indirect the entry hook through a
    // trampoline function at a known address.
    // It additionally takes an isolate as a third parameter
    __ mov(r2, Operand(ExternalReference::isolate_address(isolate())));
  
    ApiFunction dispatcher(FUNCTION_ADDR(EntryHookTrampoline));
    __ mov(ip, Operand(ExternalReference(&dispatcher,
                                         ExternalReference::BUILTIN_CALL,
                                         isolate())));
  #endif
    __ Call(ip);
  
    // Restore the stack pointer if needed.
    if (frame_alignment > kPointerSize) {
      __ mov(sp, r5);
    }
  
    // Also pop pc to get Ret(0).
    __ ldm(ia_w, sp, kSavedRegs | pc.bit());
  }
  
  
  template<class T>
  static void CreateArrayDispatch(MacroAssembler* masm,
                                  AllocationSiteOverrideMode mode) {
    if (mode == DISABLE_ALLOCATION_SITES) {
      T stub(masm->isolate(), GetInitialFastElementsKind(), mode);
      __ TailCallStub(&stub);
    } else if (mode == DONT_OVERRIDE) {
      int last_index = GetSequenceIndexFromFastElementsKind(
          TERMINAL_FAST_ELEMENTS_KIND);
      for (int i = 0; i <= last_index; ++i) {
        ElementsKind kind = GetFastElementsKindFromSequenceIndex(i);
        __ cmp(r3, Operand(kind));
        T stub(masm->isolate(), kind);
        __ TailCallStub(&stub, eq);
      }
  
      // If we reached this point there is a problem.
      __ Abort(kUnexpectedElementsKindInArrayConstructor);
    } else {
      UNREACHABLE();
    }
  }
  
  
  static void CreateArrayDispatchOneArgument(MacroAssembler* masm,
                                             AllocationSiteOverrideMode mode) {
    // r2 - allocation site (if mode != DISABLE_ALLOCATION_SITES)
    // r3 - kind (if mode != DISABLE_ALLOCATION_SITES)
    // r0 - number of arguments
    // r1 - constructor?
    // sp[0] - last argument
    Label normal_sequence;
    if (mode == DONT_OVERRIDE) {
      DCHECK(FAST_SMI_ELEMENTS == 0);
      DCHECK(FAST_HOLEY_SMI_ELEMENTS == 1);
      DCHECK(FAST_ELEMENTS == 2);
      DCHECK(FAST_HOLEY_ELEMENTS == 3);
      DCHECK(FAST_DOUBLE_ELEMENTS == 4);
      DCHECK(FAST_HOLEY_DOUBLE_ELEMENTS == 5);
  
      // is the low bit set? If so, we are holey and that is good.
      __ tst(r3, Operand(1));
      __ b(ne, &normal_sequence);
    }
  
    // look at the first argument
    __ ldr(r5, MemOperand(sp, 0));
    __ cmp(r5, Operand::Zero());
    __ b(eq, &normal_sequence);
  
    if (mode == DISABLE_ALLOCATION_SITES) {
      ElementsKind initial = GetInitialFastElementsKind();
      ElementsKind holey_initial = GetHoleyElementsKind(initial);
  
      ArraySingleArgumentConstructorStub stub_holey(masm->isolate(),
                                                    holey_initial,
                                                    DISABLE_ALLOCATION_SITES);
      __ TailCallStub(&stub_holey);
  
      __ bind(&normal_sequence);
      ArraySingleArgumentConstructorStub stub(masm->isolate(),
                                              initial,
                                              DISABLE_ALLOCATION_SITES);
      __ TailCallStub(&stub);
    } else if (mode == DONT_OVERRIDE) {
      // We are going to create a holey array, but our kind is non-holey.
      // Fix kind and retry (only if we have an allocation site in the slot).
      __ add(r3, r3, Operand(1));
  
      if (FLAG_debug_code) {
        __ ldr(r5, FieldMemOperand(r2, 0));
        __ CompareRoot(r5, Heap::kAllocationSiteMapRootIndex);
        __ Assert(eq, kExpectedAllocationSite);
      }
  
      // Save the resulting elements kind in type info. We can't just store r3
      // in the AllocationSite::transition_info field because elements kind is
      // restricted to a portion of the field...upper bits need to be left alone.
      STATIC_ASSERT(AllocationSite::ElementsKindBits::kShift == 0);
      __ ldr(r4, FieldMemOperand(r2, AllocationSite::kTransitionInfoOffset));
      __ add(r4, r4, Operand(Smi::FromInt(kFastElementsKindPackedToHoley)));
      __ str(r4, FieldMemOperand(r2, AllocationSite::kTransitionInfoOffset));
  
      __ bind(&normal_sequence);
      int last_index = GetSequenceIndexFromFastElementsKind(
          TERMINAL_FAST_ELEMENTS_KIND);
      for (int i = 0; i <= last_index; ++i) {
        ElementsKind kind = GetFastElementsKindFromSequenceIndex(i);
        __ cmp(r3, Operand(kind));
        ArraySingleArgumentConstructorStub stub(masm->isolate(), kind);
        __ TailCallStub(&stub, eq);
      }
  
      // If we reached this point there is a problem.
      __ Abort(kUnexpectedElementsKindInArrayConstructor);
    } else {
      UNREACHABLE();
    }
  }
  
  
  template<class T>
  static void ArrayConstructorStubAheadOfTimeHelper(Isolate* isolate) {
    int to_index = GetSequenceIndexFromFastElementsKind(
        TERMINAL_FAST_ELEMENTS_KIND);
    for (int i = 0; i <= to_index; ++i) {
      ElementsKind kind = GetFastElementsKindFromSequenceIndex(i);
      T stub(isolate, kind);
      stub.GetCode();
      if (AllocationSite::GetMode(kind) != DONT_TRACK_ALLOCATION_SITE) {
        T stub1(isolate, kind, DISABLE_ALLOCATION_SITES);
        stub1.GetCode();
      }
    }
  }
  
  
  void ArrayConstructorStubBase::GenerateStubsAheadOfTime(Isolate* isolate) {
    ArrayConstructorStubAheadOfTimeHelper<ArrayNoArgumentConstructorStub>(
        isolate);
    ArrayConstructorStubAheadOfTimeHelper<ArraySingleArgumentConstructorStub>(
        isolate);
    ArrayConstructorStubAheadOfTimeHelper<ArrayNArgumentsConstructorStub>(
        isolate);
  }
  
  
  void InternalArrayConstructorStubBase::GenerateStubsAheadOfTime(
      Isolate* isolate) {
    ElementsKind kinds[2] = { FAST_ELEMENTS, FAST_HOLEY_ELEMENTS };
    for (int i = 0; i < 2; i++) {
      // For internal arrays we only need a few things
      InternalArrayNoArgumentConstructorStub stubh1(isolate, kinds[i]);
      stubh1.GetCode();
      InternalArraySingleArgumentConstructorStub stubh2(isolate, kinds[i]);
      stubh2.GetCode();
      InternalArrayNArgumentsConstructorStub stubh3(isolate, kinds[i]);
      stubh3.GetCode();
    }
  }
  
  
  void ArrayConstructorStub::GenerateDispatchToArrayStub(
      MacroAssembler* masm,
      AllocationSiteOverrideMode mode) {
    if (argument_count() == ANY) {
      Label not_zero_case, not_one_case;
      __ tst(r0, r0);
      __ b(ne, &not_zero_case);
      CreateArrayDispatch<ArrayNoArgumentConstructorStub>(masm, mode);
  
      __ bind(&not_zero_case);
      __ cmp(r0, Operand(1));
      __ b(gt, &not_one_case);
      CreateArrayDispatchOneArgument(masm, mode);
  
      __ bind(&not_one_case);
      CreateArrayDispatch<ArrayNArgumentsConstructorStub>(masm, mode);
    } else if (argument_count() == NONE) {
      CreateArrayDispatch<ArrayNoArgumentConstructorStub>(masm, mode);
    } else if (argument_count() == ONE) {
      CreateArrayDispatchOneArgument(masm, mode);
    } else if (argument_count() == MORE_THAN_ONE) {
      CreateArrayDispatch<ArrayNArgumentsConstructorStub>(masm, mode);
    } else {
      UNREACHABLE();
    }
  }
  
  
  void ArrayConstructorStub::Generate(MacroAssembler* masm) {
    // ----------- S t a t e -------------
    //  -- r0 : argc (only if argument_count() == ANY)
    //  -- r1 : constructor
    //  -- r2 : AllocationSite or undefined
    //  -- sp[0] : return address
    //  -- sp[4] : last argument
    // -----------------------------------
  
    if (FLAG_debug_code) {
      // The array construct code is only set for the global and natives
      // builtin Array functions which always have maps.
  
      // Initial map for the builtin Array function should be a map.
      __ ldr(r4, FieldMemOperand(r1, JSFunction::kPrototypeOrInitialMapOffset));
      // Will both indicate a NULL and a Smi.
      __ tst(r4, Operand(kSmiTagMask));
      __ Assert(ne, kUnexpectedInitialMapForArrayFunction);
      __ CompareObjectType(r4, r4, r5, MAP_TYPE);
      __ Assert(eq, kUnexpectedInitialMapForArrayFunction);
  
      // We should either have undefined in r2 or a valid AllocationSite
      __ AssertUndefinedOrAllocationSite(r2, r4);
    }
  
    Label no_info;
    // Get the elements kind and case on that.
    __ CompareRoot(r2, Heap::kUndefinedValueRootIndex);
    __ b(eq, &no_info);
  
    __ ldr(r3, FieldMemOperand(r2, AllocationSite::kTransitionInfoOffset));
    __ SmiUntag(r3);
    STATIC_ASSERT(AllocationSite::ElementsKindBits::kShift == 0);
    __ and_(r3, r3, Operand(AllocationSite::ElementsKindBits::kMask));
    GenerateDispatchToArrayStub(masm, DONT_OVERRIDE);
  
    __ bind(&no_info);
    GenerateDispatchToArrayStub(masm, DISABLE_ALLOCATION_SITES);
  }
  
  
  void InternalArrayConstructorStub::GenerateCase(
      MacroAssembler* masm, ElementsKind kind) {
    __ cmp(r0, Operand(1));
  
    InternalArrayNoArgumentConstructorStub stub0(isolate(), kind);
    __ TailCallStub(&stub0, lo);
  
    InternalArrayNArgumentsConstructorStub stubN(isolate(), kind);
    __ TailCallStub(&stubN, hi);
  
    if (IsFastPackedElementsKind(kind)) {
      // We might need to create a holey array
      // look at the first argument
      __ ldr(r3, MemOperand(sp, 0));
      __ cmp(r3, Operand::Zero());
  
      InternalArraySingleArgumentConstructorStub
          stub1_holey(isolate(), GetHoleyElementsKind(kind));
      __ TailCallStub(&stub1_holey, ne);
    }
  
    InternalArraySingleArgumentConstructorStub stub1(isolate(), kind);
    __ TailCallStub(&stub1);
  }
  
  
  void InternalArrayConstructorStub::Generate(MacroAssembler* masm) {
    // ----------- S t a t e -------------
    //  -- r0 : argc
    //  -- r1 : constructor
    //  -- sp[0] : return address
    //  -- sp[4] : last argument
    // -----------------------------------
  
    if (FLAG_debug_code) {
      // The array construct code is only set for the global and natives
      // builtin Array functions which always have maps.
  
      // Initial map for the builtin Array function should be a map.
      __ ldr(r3, FieldMemOperand(r1, JSFunction::kPrototypeOrInitialMapOffset));
      // Will both indicate a NULL and a Smi.
      __ tst(r3, Operand(kSmiTagMask));
      __ Assert(ne, kUnexpectedInitialMapForArrayFunction);
      __ CompareObjectType(r3, r3, r4, MAP_TYPE);
      __ Assert(eq, kUnexpectedInitialMapForArrayFunction);
    }
  
    // Figure out the right elements kind
    __ ldr(r3, FieldMemOperand(r1, JSFunction::kPrototypeOrInitialMapOffset));
    // Load the map's "bit field 2" into |result|. We only need the first byte,
    // but the following bit field extraction takes care of that anyway.
    __ ldr(r3, FieldMemOperand(r3, Map::kBitField2Offset));
    // Retrieve elements_kind from bit field 2.
    __ DecodeField<Map::ElementsKindBits>(r3);
  
    if (FLAG_debug_code) {
      Label done;
      __ cmp(r3, Operand(FAST_ELEMENTS));
      __ b(eq, &done);
      __ cmp(r3, Operand(FAST_HOLEY_ELEMENTS));
      __ Assert(eq,
                kInvalidElementsKindForInternalArrayOrInternalPackedArray);
      __ bind(&done);
    }
  
    Label fast_elements_case;
    __ cmp(r3, Operand(FAST_ELEMENTS));
    __ b(eq, &fast_elements_case);
    GenerateCase(masm, FAST_HOLEY_ELEMENTS);
  
    __ bind(&fast_elements_case);
    GenerateCase(masm, FAST_ELEMENTS);
  }
  
  
  void CallApiFunctionStub::Generate(MacroAssembler* masm) {
    // ----------- S t a t e -------------
    //  -- r0                  : callee
    //  -- r4                  : call_data
    //  -- r2                  : holder
    //  -- r1                  : api_function_address
    //  -- cp                  : context
    //  --
    //  -- sp[0]               : last argument
    //  -- ...
    //  -- sp[(argc - 1)* 4]   : first argument
    //  -- sp[argc * 4]        : receiver
    // -----------------------------------
  
    Register callee = r0;
    Register call_data = r4;
    Register holder = r2;
    Register api_function_address = r1;
    Register context = cp;
  
    int argc = this->argc();
    bool is_store = this->is_store();
    bool call_data_undefined = this->call_data_undefined();
  
    typedef FunctionCallbackArguments FCA;
  
    STATIC_ASSERT(FCA::kContextSaveIndex == 6);
    STATIC_ASSERT(FCA::kCalleeIndex == 5);
    STATIC_ASSERT(FCA::kDataIndex == 4);
    STATIC_ASSERT(FCA::kReturnValueOffset == 3);
    STATIC_ASSERT(FCA::kReturnValueDefaultValueIndex == 2);
    STATIC_ASSERT(FCA::kIsolateIndex == 1);
    STATIC_ASSERT(FCA::kHolderIndex == 0);
    STATIC_ASSERT(FCA::kArgsLength == 7);
  
    // context save
    __ push(context);
    // load context from callee
    __ ldr(context, FieldMemOperand(callee, JSFunction::kContextOffset));
  
    // callee
    __ push(callee);
  
    // call data
    __ push(call_data);
  
    Register scratch = call_data;
    if (!call_data_undefined) {
      __ LoadRoot(scratch, Heap::kUndefinedValueRootIndex);
    }
    // return value
    __ push(scratch);
    // return value default
    __ push(scratch);
    // isolate
    __ mov(scratch,
           Operand(ExternalReference::isolate_address(isolate())));
    __ push(scratch);
    // holder
    __ push(holder);
  
    // Prepare arguments.
    __ mov(scratch, sp);
  
    // Allocate the v8::Arguments structure in the arguments' space since
    // it's not controlled by GC.
    const int kApiStackSpace = 4;
  
    FrameScope frame_scope(masm, StackFrame::MANUAL);
    __ EnterExitFrame(false, kApiStackSpace);
  
    DCHECK(!api_function_address.is(r0) && !scratch.is(r0));
    // r0 = FunctionCallbackInfo&
    // Arguments is after the return address.
    __ add(r0, sp, Operand(1 * kPointerSize));
    // FunctionCallbackInfo::implicit_args_
    __ str(scratch, MemOperand(r0, 0 * kPointerSize));
    // FunctionCallbackInfo::values_
    __ add(ip, scratch, Operand((FCA::kArgsLength - 1 + argc) * kPointerSize));
    __ str(ip, MemOperand(r0, 1 * kPointerSize));
    // FunctionCallbackInfo::length_ = argc
    __ mov(ip, Operand(argc));
    __ str(ip, MemOperand(r0, 2 * kPointerSize));
    // FunctionCallbackInfo::is_construct_call = 0
    __ mov(ip, Operand::Zero());
    __ str(ip, MemOperand(r0, 3 * kPointerSize));
  
    const int kStackUnwindSpace = argc + FCA::kArgsLength + 1;
    ExternalReference thunk_ref =
        ExternalReference::invoke_function_callback(isolate());
  
    AllowExternalCallThatCantCauseGC scope(masm);
    MemOperand context_restore_operand(
        fp, (2 + FCA::kContextSaveIndex) * kPointerSize);
    // Stores return the first js argument
    int return_value_offset = 0;
    if (is_store) {
      return_value_offset = 2 + FCA::kArgsLength;
    } else {
      return_value_offset = 2 + FCA::kReturnValueOffset;
    }
    MemOperand return_value_operand(fp, return_value_offset * kPointerSize);
  
    __ CallApiFunctionAndReturn(api_function_address,
                                thunk_ref,
                                kStackUnwindSpace,
                                return_value_operand,
                                &context_restore_operand);
  }
  
  
  void CallApiGetterStub::Generate(MacroAssembler* masm) {
    // ----------- S t a t e -------------
    //  -- sp[0]                  : name
    //  -- sp[4 - kArgsLength*4]  : PropertyCallbackArguments object
    //  -- ...
    //  -- r2                     : api_function_address
    // -----------------------------------
  
    Register api_function_address = ApiGetterDescriptor::function_address();
    DCHECK(api_function_address.is(r2));
  
    __ mov(r0, sp);  // r0 = Handle<Name>
    __ add(r1, r0, Operand(1 * kPointerSize));  // r1 = PCA
  
    const int kApiStackSpace = 1;
    FrameScope frame_scope(masm, StackFrame::MANUAL);
    __ EnterExitFrame(false, kApiStackSpace);
  
    // Create PropertyAccessorInfo instance on the stack above the exit frame with
    // r1 (internal::Object** args_) as the data.
    __ str(r1, MemOperand(sp, 1 * kPointerSize));
    __ add(r1, sp, Operand(1 * kPointerSize));  // r1 = AccessorInfo&
  
    const int kStackUnwindSpace = PropertyCallbackArguments::kArgsLength + 1;
  
    ExternalReference thunk_ref =
        ExternalReference::invoke_accessor_getter_callback(isolate());
    __ CallApiFunctionAndReturn(api_function_address,
                                thunk_ref,
                                kStackUnwindSpace,
                                MemOperand(fp, 6 * kPointerSize),
                                NULL);
  }
  
  
  #undef __
  
  } }  // namespace v8::internal
  
  #endif  // V8_TARGET_ARCH_ARM
  