Move code stubs from codegen*.* files to code-stub*.* files.

src/arm/code-stubs-arm.cc

+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "v8.h"
+
+#if defined(V8_TARGET_ARCH_ARM)
+
+#include "bootstrapper.h"
+#include "code-stubs-arm.h"
+#include "codegen-inl.h"
+#include "regexp-macro-assembler.h"
+
+namespace v8 {
+namespace internal {
+
+
+#define __ ACCESS_MASM(masm)
+
+static void EmitIdenticalObjectComparison(MacroAssembler* masm,
+                                          Label* slow,
+                                          Condition cc,
+                                          bool never_nan_nan);
+static void EmitSmiNonsmiComparison(MacroAssembler* masm,
+                                    Register lhs,
+                                    Register rhs,
+                                    Label* lhs_not_nan,
+                                    Label* slow,
+                                    bool strict);
+static void EmitTwoNonNanDoubleComparison(MacroAssembler* masm, Condition cc);
+static void EmitStrictTwoHeapObjectCompare(MacroAssembler* masm,
+                                           Register lhs,
+                                           Register rhs);
+
+
+void FastNewClosureStub::Generate(MacroAssembler* masm) {
+  // Create a new closure from the given function info in new
+  // space. Set the context to the current context in cp.
+  Label gc;
+
+  // Pop the function info from the stack.
+  __ pop(r3);
+
+  // Attempt to allocate new JSFunction in new space.
+  __ AllocateInNewSpace(JSFunction::kSize,
+                        r0,
+                        r1,
+                        r2,
+                        &gc,
+                        TAG_OBJECT);
+
+  // Compute the function map in the current global context and set that
+  // as the map of the allocated object.
+  __ ldr(r2, MemOperand(cp, Context::SlotOffset(Context::GLOBAL_INDEX)));
+  __ ldr(r2, FieldMemOperand(r2, GlobalObject::kGlobalContextOffset));
+  __ ldr(r2, MemOperand(r2, Context::SlotOffset(Context::FUNCTION_MAP_INDEX)));
+  __ str(r2, FieldMemOperand(r0, HeapObject::kMapOffset));
+
+  // Initialize the rest of the function. We don't have to update the
+  // write barrier because the allocated object is in new space.
+  __ LoadRoot(r1, Heap::kEmptyFixedArrayRootIndex);
+  __ LoadRoot(r2, Heap::kTheHoleValueRootIndex);
+  __ str(r1, FieldMemOperand(r0, JSObject::kPropertiesOffset));
+  __ str(r1, FieldMemOperand(r0, JSObject::kElementsOffset));
+  __ str(r2, FieldMemOperand(r0, JSFunction::kPrototypeOrInitialMapOffset));
+  __ str(r3, FieldMemOperand(r0, JSFunction::kSharedFunctionInfoOffset));
+  __ str(cp, FieldMemOperand(r0, JSFunction::kContextOffset));
+  __ str(r1, FieldMemOperand(r0, JSFunction::kLiteralsOffset));
+
+  // Initialize the code pointer in the function to be the one
+  // found in the shared function info object.
+  __ ldr(r3, FieldMemOperand(r3, SharedFunctionInfo::kCodeOffset));
+  __ add(r3, r3, Operand(Code::kHeaderSize - kHeapObjectTag));
+  __ str(r3, FieldMemOperand(r0, JSFunction::kCodeEntryOffset));
+
+  // Return result. The argument function info has been popped already.
+  __ Ret();
+
+  // Create a new closure through the slower runtime call.
+  __ bind(&gc);
+  __ Push(cp, r3);
+  __ TailCallRuntime(Runtime::kNewClosure, 2, 1);
+}
+
+
+void FastNewContextStub::Generate(MacroAssembler* masm) {
+  // Try to allocate the context in new space.
+  Label gc;
+  int length = slots_ + Context::MIN_CONTEXT_SLOTS;
+
+  // Attempt to allocate the context in new space.
+  __ AllocateInNewSpace(FixedArray::SizeFor(length),
+                        r0,
+                        r1,
+                        r2,
+                        &gc,
+                        TAG_OBJECT);
+
+  // Load the function from the stack.
+  __ ldr(r3, MemOperand(sp, 0));
+
+  // Setup the object header.
+  __ LoadRoot(r2, Heap::kContextMapRootIndex);
+  __ str(r2, FieldMemOperand(r0, HeapObject::kMapOffset));
+  __ mov(r2, Operand(Smi::FromInt(length)));
+  __ str(r2, FieldMemOperand(r0, FixedArray::kLengthOffset));
+
+  // Setup the fixed slots.
+  __ mov(r1, Operand(Smi::FromInt(0)));
+  __ str(r3, MemOperand(r0, Context::SlotOffset(Context::CLOSURE_INDEX)));
+  __ str(r0, MemOperand(r0, Context::SlotOffset(Context::FCONTEXT_INDEX)));
+  __ str(r1, MemOperand(r0, Context::SlotOffset(Context::PREVIOUS_INDEX)));
+  __ str(r1, MemOperand(r0, Context::SlotOffset(Context::EXTENSION_INDEX)));
+
+  // Copy the global object from the surrounding context.
+  __ ldr(r1, MemOperand(cp, Context::SlotOffset(Context::GLOBAL_INDEX)));
+  __ str(r1, MemOperand(r0, Context::SlotOffset(Context::GLOBAL_INDEX)));
+
+  // Initialize the rest of the slots to undefined.
+  __ LoadRoot(r1, Heap::kUndefinedValueRootIndex);
+  for (int i = Context::MIN_CONTEXT_SLOTS; i < length; i++) {
+    __ str(r1, MemOperand(r0, Context::SlotOffset(i)));
+  }
+
+  // Remove the on-stack argument and return.
+  __ mov(cp, r0);
+  __ pop();
+  __ Ret();
+
+  // Need to collect. Call into runtime system.
+  __ bind(&gc);
+  __ TailCallRuntime(Runtime::kNewContext, 1, 1);
+}
+
+
+void FastCloneShallowArrayStub::Generate(MacroAssembler* masm) {
+  // Stack layout on entry:
+  //
+  // [sp]: constant elements.
+  // [sp + kPointerSize]: literal index.
+  // [sp + (2 * kPointerSize)]: literals array.
+
+  // All sizes here are multiples of kPointerSize.
+  int elements_size = (length_ > 0) ? FixedArray::SizeFor(length_) : 0;
+  int size = JSArray::kSize + elements_size;
+
+  // Load boilerplate object into r3 and check if we need to create a
+  // boilerplate.
+  Label slow_case;
+  __ ldr(r3, MemOperand(sp, 2 * kPointerSize));
+  __ ldr(r0, MemOperand(sp, 1 * kPointerSize));
+  __ add(r3, r3, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
+  __ ldr(r3, MemOperand(r3, r0, LSL, kPointerSizeLog2 - kSmiTagSize));
+  __ LoadRoot(ip, Heap::kUndefinedValueRootIndex);
+  __ cmp(r3, ip);
+  __ b(eq, &slow_case);
+
+  if (FLAG_debug_code) {
+    const char* message;
+    Heap::RootListIndex expected_map_index;
+    if (mode_ == CLONE_ELEMENTS) {
+      message = "Expected (writable) fixed array";
+      expected_map_index = Heap::kFixedArrayMapRootIndex;
+    } else {
+      ASSERT(mode_ == COPY_ON_WRITE_ELEMENTS);
+      message = "Expected copy-on-write fixed array";
+      expected_map_index = Heap::kFixedCOWArrayMapRootIndex;
+    }
+    __ push(r3);
+    __ ldr(r3, FieldMemOperand(r3, JSArray::kElementsOffset));
+    __ ldr(r3, FieldMemOperand(r3, HeapObject::kMapOffset));
+    __ LoadRoot(ip, expected_map_index);
+    __ cmp(r3, ip);
+    __ Assert(eq, message);
+    __ pop(r3);
+  }
+
+  // Allocate both the JS array and the elements array in one big
+  // allocation. This avoids multiple limit checks.
+  __ AllocateInNewSpace(size,
+                        r0,
+                        r1,
+                        r2,
+                        &slow_case,
+                        TAG_OBJECT);
+
+  // Copy the JS array part.
+  for (int i = 0; i < JSArray::kSize; i += kPointerSize) {
+    if ((i != JSArray::kElementsOffset) || (length_ == 0)) {
+      __ ldr(r1, FieldMemOperand(r3, i));
+      __ str(r1, FieldMemOperand(r0, i));
+    }
+  }
+
+  if (length_ > 0) {
+    // Get hold of the elements array of the boilerplate and setup the
+    // elements pointer in the resulting object.
+    __ ldr(r3, FieldMemOperand(r3, JSArray::kElementsOffset));
+    __ add(r2, r0, Operand(JSArray::kSize));
+    __ str(r2, FieldMemOperand(r0, JSArray::kElementsOffset));
+
+    // Copy the elements array.
+    __ CopyFields(r2, r3, r1.bit(), elements_size / kPointerSize);
+  }
+
+  // Return and remove the on-stack parameters.
+  __ add(sp, sp, Operand(3 * kPointerSize));
+  __ Ret();
+
+  __ bind(&slow_case);
+  __ TailCallRuntime(Runtime::kCreateArrayLiteralShallow, 3, 1);
+}
+
+
+// Takes a Smi and converts to an IEEE 64 bit floating point value in two
+// registers.  The format is 1 sign bit, 11 exponent bits (biased 1023) and
+// 52 fraction bits (20 in the first word, 32 in the second).  Zeros is a
+// scratch register.  Destroys the source register.  No GC occurs during this
+// stub so you don't have to set up the frame.
+class ConvertToDoubleStub : public CodeStub {
+ public:
+  ConvertToDoubleStub(Register result_reg_1,
+                      Register result_reg_2,
+                      Register source_reg,
+                      Register scratch_reg)
+      : result1_(result_reg_1),
+        result2_(result_reg_2),
+        source_(source_reg),
+        zeros_(scratch_reg) { }
+
+ private:
+  Register result1_;
+  Register result2_;
+  Register source_;
+  Register zeros_;
+
+  // Minor key encoding in 16 bits.
+  class ModeBits: public BitField<OverwriteMode, 0, 2> {};
+  class OpBits: public BitField<Token::Value, 2, 14> {};
+
+  Major MajorKey() { return ConvertToDouble; }
+  int MinorKey() {
+    // Encode the parameters in a unique 16 bit value.
+    return  result1_.code() +
+           (result2_.code() << 4) +
+           (source_.code() << 8) +
+           (zeros_.code() << 12);
+  }
+
+  void Generate(MacroAssembler* masm);
+
+  const char* GetName() { return "ConvertToDoubleStub"; }
+
+#ifdef DEBUG
+  void Print() { PrintF("ConvertToDoubleStub\n"); }
+#endif
+};
+
+
+void ConvertToDoubleStub::Generate(MacroAssembler* masm) {
+#ifndef BIG_ENDIAN_FLOATING_POINT
+  Register exponent = result1_;
+  Register mantissa = result2_;
+#else
+  Register exponent = result2_;
+  Register mantissa = result1_;
+#endif
+  Label not_special;
+  // Convert from Smi to integer.
+  __ mov(source_, Operand(source_, ASR, kSmiTagSize));
+  // Move sign bit from source to destination.  This works because the sign bit
+  // in the exponent word of the double has the same position and polarity as
+  // the 2's complement sign bit in a Smi.
+  STATIC_ASSERT(HeapNumber::kSignMask == 0x80000000u);
+  __ and_(exponent, source_, Operand(HeapNumber::kSignMask), SetCC);
+  // Subtract from 0 if source was negative.
+  __ rsb(source_, source_, Operand(0), LeaveCC, ne);
+
+  // We have -1, 0 or 1, which we treat specially. Register source_ contains
+  // absolute value: it is either equal to 1 (special case of -1 and 1),
+  // greater than 1 (not a special case) or less than 1 (special case of 0).
+  __ cmp(source_, Operand(1));
+  __ b(gt, &not_special);
+
+  // For 1 or -1 we need to or in the 0 exponent (biased to 1023).
+  static const uint32_t exponent_word_for_1 =
+      HeapNumber::kExponentBias << HeapNumber::kExponentShift;
+  __ orr(exponent, exponent, Operand(exponent_word_for_1), LeaveCC, eq);
+  // 1, 0 and -1 all have 0 for the second word.
+  __ mov(mantissa, Operand(0));
+  __ Ret();
+
+  __ bind(&not_special);
+  // Count leading zeros.  Uses mantissa for a scratch register on pre-ARM5.
+  // Gets the wrong answer for 0, but we already checked for that case above.
+  __ CountLeadingZeros(zeros_, source_, mantissa);
+  // Compute exponent and or it into the exponent register.
+  // We use mantissa as a scratch register here.  Use a fudge factor to
+  // divide the constant 31 + HeapNumber::kExponentBias, 0x41d, into two parts
+  // that fit in the ARM's constant field.
+  int fudge = 0x400;
+  __ rsb(mantissa, zeros_, Operand(31 + HeapNumber::kExponentBias - fudge));
+  __ add(mantissa, mantissa, Operand(fudge));
+  __ orr(exponent,
+         exponent,
+         Operand(mantissa, LSL, HeapNumber::kExponentShift));
+  // Shift up the source chopping the top bit off.
+  __ add(zeros_, zeros_, Operand(1));
+  // This wouldn't work for 1.0 or -1.0 as the shift would be 32 which means 0.
+  __ mov(source_, Operand(source_, LSL, zeros_));
+  // Compute lower part of fraction (last 12 bits).
+  __ mov(mantissa, Operand(source_, LSL, HeapNumber::kMantissaBitsInTopWord));
+  // And the top (top 20 bits).
+  __ orr(exponent,
+         exponent,
+         Operand(source_, LSR, 32 - HeapNumber::kMantissaBitsInTopWord));
+  __ Ret();
+}
+
+
+// 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(0), 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.
+  ASSERT(((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(0));
+  __ 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 cc,
+                                          bool never_nan_nan) {
+  Label not_identical;
+  Label heap_number, return_equal;
+  __ cmp(r0, r1);
+  __ b(ne, &not_identical);
+
+  // The two objects are identical.  If we know that one of them isn't NaN then
+  // we now know they test equal.
+  if (cc != eq || !never_nan_nan) {
+    // 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 (cc == lt || cc == gt) {
+      __ CompareObjectType(r0, r4, r4, FIRST_JS_OBJECT_TYPE);
+      __ b(ge, slow);
+    } else {
+      __ CompareObjectType(r0, r4, r4, HEAP_NUMBER_TYPE);
+      __ b(eq, &heap_number);
+      // Comparing JS objects with <=, >= is complicated.
+      if (cc != eq) {
+        __ cmp(r4, Operand(FIRST_JS_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 (cc == le || cc == ge) {
+          __ cmp(r4, Operand(ODDBALL_TYPE));
+          __ b(ne, &return_equal);
+          __ LoadRoot(r2, Heap::kUndefinedValueRootIndex);
+          __ cmp(r0, r2);
+          __ b(ne, &return_equal);
+          if (cc == le) {
+            // undefined <= undefined should fail.
+            __ mov(r0, Operand(GREATER));
+          } else  {
+            // undefined >= undefined should fail.
+            __ mov(r0, Operand(LESS));
+          }
+          __ Ret();
+        }
+      }
+    }
+  }
+
+  __ bind(&return_equal);
+  if (cc == lt) {
+    __ mov(r0, Operand(GREATER));  // Things aren't less than themselves.
+  } else if (cc == gt) {
+    __ mov(r0, Operand(LESS));     // Things aren't greater than themselves.
+  } else {
+    __ mov(r0, Operand(EQUAL));    // Things are <=, >=, ==, === themselves.
+  }
+  __ Ret();
+
+  if (cc != eq || !never_nan_nan) {
+    // 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 (cc != lt && cc != 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 (cc != eq) {
+        // All-zero means Infinity means equal.
+        __ Ret(eq);
+        if (cc == 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) {
+  ASSERT((lhs.is(r0) && rhs.is(r1)) ||
+         (lhs.is(r1) && rhs.is(r0)));
+
+  Label rhs_is_smi;
+  __ tst(rhs, Operand(kSmiTagMask));
+  __ b(eq, &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.
+  if (CpuFeatures::IsSupported(VFP3)) {
+    // Convert lhs to a double in d7.
+    CpuFeatures::Scope scope(VFP3);
+    __ SmiToDoubleVFPRegister(lhs, d7, r7, s15);
+    // Load the double from rhs, tagged HeapNumber r0, to d6.
+    __ sub(r7, rhs, Operand(kHeapObjectTag));
+    __ vldr(d6, r7, HeapNumber::kValueOffset);
+  } else {
+    __ push(lr);
+    // Convert lhs to a double in r2, r3.
+    __ mov(r7, Operand(lhs));
+    ConvertToDoubleStub stub1(r3, r2, r7, r6);
+    __ Call(stub1.GetCode(), RelocInfo::CODE_TARGET);
+    // Load rhs to a double in r0, r1.
+    __ Ldrd(r0, r1, FieldMemOperand(rhs, HeapNumber::kValueOffset));
+    __ pop(lr);
+  }
+
+  // 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.
+  if (CpuFeatures::IsSupported(VFP3)) {
+    CpuFeatures::Scope scope(VFP3);
+    // Load the double from lhs, tagged HeapNumber r1, to d7.
+    __ sub(r7, lhs, Operand(kHeapObjectTag));
+    __ vldr(d7, r7, HeapNumber::kValueOffset);
+    // Convert rhs to a double in d6              .
+    __ SmiToDoubleVFPRegister(rhs, d6, r7, s13);
+  } else {
+    __ push(lr);
+    // Load lhs to a double in r2, r3.
+    __ Ldrd(r2, r3, FieldMemOperand(lhs, HeapNumber::kValueOffset));
+    // Convert rhs to a double in r0, r1.
+    __ mov(r7, Operand(rhs));
+    ConvertToDoubleStub stub2(r1, r0, r7, r6);
+    __ Call(stub2.GetCode(), RelocInfo::CODE_TARGET);
+    __ pop(lr);
+  }
+  // Fall through to both_loaded_as_doubles.
+}
+
+
+void EmitNanCheck(MacroAssembler* masm, Label* lhs_not_nan, Condition cc) {
+  bool exp_first = (HeapNumber::kExponentOffset == HeapNumber::kValueOffset);
+  Register rhs_exponent = exp_first ? r0 : r1;
+  Register lhs_exponent = exp_first ? r2 : r3;
+  Register rhs_mantissa = exp_first ? r1 : r0;
+  Register lhs_mantissa = exp_first ? r3 : r2;
+  Label one_is_nan, neither_is_nan;
+
+  __ Sbfx(r4,
+          lhs_exponent,
+          HeapNumber::kExponentShift,
+          HeapNumber::kExponentBits);
+  // NaNs have all-one exponents so they sign extend to -1.
+  __ cmp(r4, Operand(-1));
+  __ b(ne, lhs_not_nan);
+  __ mov(r4,
+         Operand(lhs_exponent, LSL, HeapNumber::kNonMantissaBitsInTopWord),
+         SetCC);
+  __ b(ne, &one_is_nan);
+  __ cmp(lhs_mantissa, Operand(0));
+  __ b(ne, &one_is_nan);
+
+  __ bind(lhs_not_nan);
+  __ Sbfx(r4,
+          rhs_exponent,
+          HeapNumber::kExponentShift,
+          HeapNumber::kExponentBits);
+  // NaNs have all-one exponents so they sign extend to -1.
+  __ cmp(r4, Operand(-1));
+  __ b(ne, &neither_is_nan);
+  __ mov(r4,
+         Operand(rhs_exponent, LSL, HeapNumber::kNonMantissaBitsInTopWord),
+         SetCC);
+  __ b(ne, &one_is_nan);
+  __ cmp(rhs_mantissa, Operand(0));
+  __ b(eq, &neither_is_nan);
+
+  __ bind(&one_is_nan);
+  // NaN comparisons always fail.
+  // Load whatever we need in r0 to make the comparison fail.
+  if (cc == lt || cc == le) {
+    __ mov(r0, Operand(GREATER));
+  } else {
+    __ mov(r0, Operand(LESS));
+  }
+  __ Ret();
+
+  __ bind(&neither_is_nan);
+}
+
+
+// See comment at call site.
+static void EmitTwoNonNanDoubleComparison(MacroAssembler* masm, Condition cc) {
+  bool exp_first = (HeapNumber::kExponentOffset == HeapNumber::kValueOffset);
+  Register rhs_exponent = exp_first ? r0 : r1;
+  Register lhs_exponent = exp_first ? r2 : r3;
+  Register rhs_mantissa = exp_first ? r1 : r0;
+  Register lhs_mantissa = exp_first ? r3 : r2;
+
+  // r0, r1, r2, r3 have the two doubles.  Neither is a NaN.
+  if (cc == eq) {
+    // Doubles are not equal unless they have the same bit pattern.
+    // Exception: 0 and -0.
+    __ cmp(rhs_mantissa, Operand(lhs_mantissa));
+    __ orr(r0, rhs_mantissa, Operand(lhs_mantissa), LeaveCC, ne);
+    // Return non-zero if the numbers are unequal.
+    __ Ret(ne);
+
+    __ sub(r0, rhs_exponent, Operand(lhs_exponent), SetCC);
+    // If exponents are equal then return 0.
+    __ Ret(eq);
+
+    // Exponents are unequal.  The only way we can return that the numbers
+    // are equal is if one is -0 and the other is 0.  We already dealt
+    // with the case where both are -0 or both are 0.
+    // We start by seeing if the mantissas (that are equal) or the bottom
+    // 31 bits of the rhs exponent are non-zero.  If so we return not
+    // equal.
+    __ orr(r4, lhs_mantissa, Operand(lhs_exponent, LSL, kSmiTagSize), SetCC);
+    __ mov(r0, Operand(r4), LeaveCC, ne);
+    __ Ret(ne);
+    // Now they are equal if and only if the lhs exponent is zero in its
+    // low 31 bits.
+    __ mov(r0, Operand(rhs_exponent, LSL, kSmiTagSize));
+    __ Ret();
+  } else {
+    // Call a native function to do a comparison between two non-NaNs.
+    // Call C routine that may not cause GC or other trouble.
+    __ push(lr);
+    __ PrepareCallCFunction(4, r5);  // Two doubles count as 4 arguments.
+    __ CallCFunction(ExternalReference::compare_doubles(), 4);
+    __ pop(pc);  // Return.
+  }
+}
+
+
+// See comment at call site.
+static void EmitStrictTwoHeapObjectCompare(MacroAssembler* masm,
+                                           Register lhs,
+                                           Register rhs) {
+    ASSERT((lhs.is(r0) && rhs.is(r1)) ||
+           (lhs.is(r1) && rhs.is(r0)));
+
+    // If either operand is a JSObject 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 == JS_FUNCTION_TYPE);
+    Label first_non_object;
+    // Get the type of the first operand into r2 and compare it with
+    // FIRST_JS_OBJECT_TYPE.
+    __ CompareObjectType(rhs, r2, r2, FIRST_JS_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_JS_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 symbol-symbol.
+    // Ensure that no non-strings have the symbol bit set.
+    STATIC_ASSERT(LAST_TYPE < kNotStringTag + kIsSymbolMask);
+    STATIC_ASSERT(kSymbolTag != 0);
+    __ and_(r2, r2, Operand(r3));
+    __ tst(r2, Operand(kIsSymbolMask));
+    __ b(ne, &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) {
+  ASSERT((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.
+  if (CpuFeatures::IsSupported(VFP3)) {
+    CpuFeatures::Scope scope(VFP3);
+    __ sub(r7, rhs, Operand(kHeapObjectTag));
+    __ vldr(d6, r7, HeapNumber::kValueOffset);
+    __ sub(r7, lhs, Operand(kHeapObjectTag));
+    __ vldr(d7, r7, HeapNumber::kValueOffset);
+  } else {
+    __ Ldrd(r2, r3, FieldMemOperand(lhs, HeapNumber::kValueOffset));
+    __ Ldrd(r0, r1, FieldMemOperand(rhs, HeapNumber::kValueOffset));
+  }
+  __ jmp(both_loaded_as_doubles);
+}
+
+
+// Fast negative check for symbol-to-symbol equality.
+static void EmitCheckForSymbolsOrObjects(MacroAssembler* masm,
+                                         Register lhs,
+                                         Register rhs,
+                                         Label* possible_strings,
+                                         Label* not_both_strings) {
+  ASSERT((lhs.is(r0) && rhs.is(r1)) ||
+         (lhs.is(r1) && rhs.is(r0)));
+
+  // r2 is object type of rhs.
+  // Ensure that no non-strings have the symbol bit set.
+  Label object_test;
+  STATIC_ASSERT(kSymbolTag != 0);
+  __ tst(r2, Operand(kIsNotStringMask));
+  __ b(ne, &object_test);
+  __ tst(r2, Operand(kIsSymbolMask));
+  __ b(eq, possible_strings);
+  __ CompareObjectType(lhs, r3, r3, FIRST_NONSTRING_TYPE);
+  __ b(ge, not_both_strings);
+  __ tst(r3, Operand(kIsSymbolMask));
+  __ b(eq, possible_strings);
+
+  // Both are symbols.  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_JS_OBJECT_TYPE));
+  __ b(lt, not_both_strings);
+  __ CompareObjectType(lhs, r2, r3, FIRST_JS_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();
+}
+
+
+void NumberToStringStub::GenerateLookupNumberStringCache(MacroAssembler* masm,
+                                                         Register object,
+                                                         Register result,
+                                                         Register scratch1,
+                                                         Register scratch2,
+                                                         Register scratch3,
+                                                         bool object_is_smi,
+                                                         Label* not_found) {
+  // Use of registers. Register result is used as a temporary.
+  Register number_string_cache = result;
+  Register mask = scratch3;
+
+  // Load the number string cache.
+  __ LoadRoot(number_string_cache, Heap::kNumberStringCacheRootIndex);
+
+  // Make the hash mask from the length of the number string cache. It
+  // contains two elements (number and string) for each cache entry.
+  __ ldr(mask, FieldMemOperand(number_string_cache, FixedArray::kLengthOffset));
+  // Divide length by two (length is a smi).
+  __ mov(mask, Operand(mask, ASR, kSmiTagSize + 1));
+  __ sub(mask, mask, Operand(1));  // Make mask.
+
+  // Calculate the entry in the number string cache. The hash value in the
+  // number string cache for smis is just the smi value, and the hash for
+  // doubles is the xor of the upper and lower words. See
+  // Heap::GetNumberStringCache.
+  Label is_smi;
+  Label load_result_from_cache;
+  if (!object_is_smi) {
+    __ BranchOnSmi(object, &is_smi);
+    if (CpuFeatures::IsSupported(VFP3)) {
+      CpuFeatures::Scope scope(VFP3);
+      __ CheckMap(object,
+                  scratch1,
+                  Heap::kHeapNumberMapRootIndex,
+                  not_found,
+                  true);
+
+      STATIC_ASSERT(8 == kDoubleSize);
+      __ add(scratch1,
+             object,
+             Operand(HeapNumber::kValueOffset - kHeapObjectTag));
+      __ ldm(ia, scratch1, scratch1.bit() | scratch2.bit());
+      __ eor(scratch1, scratch1, Operand(scratch2));
+      __ and_(scratch1, scratch1, Operand(mask));
+
+      // Calculate address of entry in string cache: each entry consists
+      // of two pointer sized fields.
+      __ add(scratch1,
+             number_string_cache,
+             Operand(scratch1, LSL, kPointerSizeLog2 + 1));
+
+      Register probe = mask;
+      __ ldr(probe,
+             FieldMemOperand(scratch1, FixedArray::kHeaderSize));
+      __ BranchOnSmi(probe, not_found);
+      __ sub(scratch2, object, Operand(kHeapObjectTag));
+      __ vldr(d0, scratch2, HeapNumber::kValueOffset);
+      __ sub(probe, probe, Operand(kHeapObjectTag));
+      __ vldr(d1, probe, HeapNumber::kValueOffset);
+      __ vcmp(d0, d1);
+      __ vmrs(pc);
+      __ b(ne, not_found);  // The cache did not contain this value.
+      __ b(&load_result_from_cache);
+    } else {
+      __ b(not_found);
+    }
+  }
+
+  __ bind(&is_smi);
+  Register scratch = scratch1;
+  __ and_(scratch, mask, Operand(object, ASR, 1));
+  // Calculate address of entry in string cache: each entry consists
+  // of two pointer sized fields.
+  __ add(scratch,
+         number_string_cache,
+         Operand(scratch, LSL, kPointerSizeLog2 + 1));
+
+  // Check if the entry is the smi we are looking for.
+  Register probe = mask;
+  __ ldr(probe, FieldMemOperand(scratch, FixedArray::kHeaderSize));
+  __ cmp(object, probe);
+  __ b(ne, not_found);
+
+  // Get the result from the cache.
+  __ bind(&load_result_from_cache);
+  __ ldr(result,
+         FieldMemOperand(scratch, FixedArray::kHeaderSize + kPointerSize));
+  __ IncrementCounter(&Counters::number_to_string_native,
+                      1,
+                      scratch1,
+                      scratch2);
+}
+
+
+void NumberToStringStub::Generate(MacroAssembler* masm) {
+  Label runtime;
+
+  __ ldr(r1, MemOperand(sp, 0));
+
+  // Generate code to lookup number in the number string cache.
+  GenerateLookupNumberStringCache(masm, r1, r0, r2, r3, r4, false, &runtime);
+  __ add(sp, sp, Operand(1 * kPointerSize));
+  __ Ret();
+
+  __ bind(&runtime);
+  // Handle number to string in the runtime system if not found in the cache.
+  __ TailCallRuntime(Runtime::kNumberToStringSkipCache, 1, 1);
+}
+
+
+void RecordWriteStub::Generate(MacroAssembler* masm) {
+  __ add(offset_, object_, Operand(offset_));
+  __ RecordWriteHelper(object_, offset_, scratch_);
+  __ Ret();
+}
+
+
+// On entry lhs_ and rhs_ are the values to be compared.
+// On exit r0 is 0, positive or negative to indicate the result of
+// the comparison.
+void CompareStub::Generate(MacroAssembler* masm) {
+  ASSERT((lhs_.is(r0) && rhs_.is(r1)) ||
+         (lhs_.is(r1) && rhs_.is(r0)));
+
+  Label slow;  // Call builtin.
+  Label not_smis, both_loaded_as_doubles, lhs_not_nan;
+
+  // 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_, never_nan_nan_);
+
+  // 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);
+  ASSERT_EQ(0, Smi::FromInt(0));
+  __ and_(r2, lhs_, Operand(rhs_));
+  __ tst(r2, Operand(kSmiTagMask));
+  __ b(ne, &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.
+  if (CpuFeatures::IsSupported(VFP3)) {
+    __ bind(&lhs_not_nan);
+    CpuFeatures::Scope scope(VFP3);
+    Label no_nan;
+    // ARMv7 VFP3 instructions to implement double precision comparison.
+    __ vcmp(d7, d6);
+    __ vmrs(pc);  // Move vector status bits to normal status bits.
+    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();
+  } else {
+    // Checks for NaN in the doubles we have loaded.  Can return the answer or
+    // fall through if neither is a NaN.  Also binds lhs_not_nan.
+    EmitNanCheck(masm, &lhs_not_nan, cc_);
+    // Compares two doubles in r0, r1, r2, r3 that are not NaNs.  Returns the
+    // answer.  Never falls through.
+    EmitTwoNonNanDoubleComparison(masm, cc_);
+  }
+
+  __ 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_symbols;
+  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_symbols.
+  // In this case r2 will contain the type of rhs_.  Never falls through.
+  EmitCheckForTwoHeapNumbers(masm,
+                             lhs_,
+                             rhs_,
+                             &both_loaded_as_doubles,
+                             &check_for_symbols,
+                             &flat_string_check);
+
+  __ bind(&check_for_symbols);
+  // In the strict case the EmitStrictTwoHeapObjectCompare already took care of
+  // symbols.
+  if (cc_ == eq && !strict_) {
+    // Returns an answer for two symbols or two detectable objects.
+    // Otherwise jumps to string case or not both strings case.
+    // Assumes that r2 is the type of rhs_ on entry.
+    EmitCheckForSymbolsOrObjects(masm, lhs_, rhs_, &flat_string_check, &slow);
+  }
+
+  // Check for both being sequential ASCII strings, and inline if that is the
+  // case.
+  __ bind(&flat_string_check);
+
+  __ JumpIfNonSmisNotBothSequentialAsciiStrings(lhs_, rhs_, r2, r3, &slow);
+
+  __ IncrementCounter(&Counters::string_compare_native, 1, r2, r3);
+  StringCompareStub::GenerateCompareFlatAsciiStrings(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 {
+      ASSERT(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_JS);
+}
+
+
+// This stub does not handle the inlined cases (Smis, Booleans, undefined).
+// The stub returns zero for false, and a non-zero value for true.
+void ToBooleanStub::Generate(MacroAssembler* masm) {
+  Label false_result;
+  Label not_heap_number;
+  Register scratch = r7;
+
+  // HeapNumber => false iff +0, -0, or NaN.
+  __ ldr(scratch, FieldMemOperand(tos_, HeapObject::kMapOffset));
+  __ LoadRoot(ip, Heap::kHeapNumberMapRootIndex);
+  __ cmp(scratch, ip);
+  __ b(&not_heap_number, ne);
+
+  __ sub(ip, tos_, Operand(kHeapObjectTag));
+  __ vldr(d1, ip, HeapNumber::kValueOffset);
+  __ vcmp(d1, 0.0);
+  __ vmrs(pc);
+  // "tos_" is a register, and contains a non zero value by default.
+  // Hence we only need to overwrite "tos_" with zero to return false for
+  // FP_ZERO or FP_NAN cases. Otherwise, by default it returns true.
+  __ mov(tos_, Operand(0), LeaveCC, eq);  // for FP_ZERO
+  __ mov(tos_, Operand(0), LeaveCC, vs);  // for FP_NAN
+  __ Ret();
+
+  __ bind(&not_heap_number);
+
+  // Check if the value is 'null'.
+  // 'null' => false.
+  __ LoadRoot(ip, Heap::kNullValueRootIndex);
+  __ cmp(tos_, ip);
+  __ b(&false_result, eq);
+
+  // It can be an undetectable object.
+  // Undetectable => false.
+  __ ldr(ip, FieldMemOperand(tos_, HeapObject::kMapOffset));
+  __ ldrb(scratch, FieldMemOperand(ip, Map::kBitFieldOffset));
+  __ and_(scratch, scratch, Operand(1 << Map::kIsUndetectable));
+  __ cmp(scratch, Operand(1 << Map::kIsUndetectable));
+  __ b(&false_result, eq);
+
+  // JavaScript object => true.
+  __ ldr(scratch, FieldMemOperand(tos_, HeapObject::kMapOffset));
+  __ ldrb(scratch, FieldMemOperand(scratch, Map::kInstanceTypeOffset));
+  __ cmp(scratch, Operand(FIRST_JS_OBJECT_TYPE));
+  // "tos_" is a register and contains a non-zero value.
+  // Hence we implicitly return true if the greater than
+  // condition is satisfied.
+  __ Ret(gt);
+
+  // Check for string
+  __ ldr(scratch, FieldMemOperand(tos_, HeapObject::kMapOffset));
+  __ ldrb(scratch, FieldMemOperand(scratch, Map::kInstanceTypeOffset));
+  __ cmp(scratch, Operand(FIRST_NONSTRING_TYPE));
+  // "tos_" is a register and contains a non-zero value.
+  // Hence we implicitly return true if the greater than
+  // condition is satisfied.
+  __ Ret(gt);
+
+  // String value => false iff empty, i.e., length is zero
+  __ ldr(tos_, FieldMemOperand(tos_, String::kLengthOffset));
+  // If length is zero, "tos_" contains zero ==> false.
+  // If length is not zero, "tos_" contains a non-zero value ==> true.
+  __ Ret();
+
+  // Return 0 in "tos_" for false .
+  __ bind(&false_result);
+  __ mov(tos_, Operand(0));
+  __ Ret();
+}
+
+
+// We fall into this code if the operands were Smis, but the result was
+// not (eg. overflow).  We branch into this code (to the not_smi label) if
+// the operands were not both Smi.  The operands are in r0 and r1.  In order
+// to call the C-implemented binary fp operation routines we need to end up
+// with the double precision floating point operands in r0 and r1 (for the
+// value in r1) and r2 and r3 (for the value in r0).
+void GenericBinaryOpStub::HandleBinaryOpSlowCases(
+    MacroAssembler* masm,
+    Label* not_smi,
+    Register lhs,
+    Register rhs,
+    const Builtins::JavaScript& builtin) {
+  Label slow, slow_reverse, do_the_call;
+  bool use_fp_registers = CpuFeatures::IsSupported(VFP3) && Token::MOD != op_;
+
+  ASSERT((lhs.is(r0) && rhs.is(r1)) || (lhs.is(r1) && rhs.is(r0)));
+  Register heap_number_map = r6;
+
+  if (ShouldGenerateSmiCode()) {
+    __ LoadRoot(heap_number_map, Heap::kHeapNumberMapRootIndex);
+
+    // Smi-smi case (overflow).
+    // Since both are Smis there is no heap number to overwrite, so allocate.
+    // The new heap number is in r5.  r3 and r7 are scratch.
+    __ AllocateHeapNumber(
+        r5, r3, r7, heap_number_map, lhs.is(r0) ? &slow_reverse : &slow);
+
+    // If we have floating point hardware, inline ADD, SUB, MUL, and DIV,
+    // using registers d7 and d6 for the double values.
+    if (CpuFeatures::IsSupported(VFP3)) {
+      CpuFeatures::Scope scope(VFP3);
+      __ mov(r7, Operand(rhs, ASR, kSmiTagSize));
+      __ vmov(s15, r7);
+      __ vcvt_f64_s32(d7, s15);
+      __ mov(r7, Operand(lhs, ASR, kSmiTagSize));
+      __ vmov(s13, r7);
+      __ vcvt_f64_s32(d6, s13);
+      if (!use_fp_registers) {
+        __ vmov(r2, r3, d7);
+        __ vmov(r0, r1, d6);
+      }
+    } else {
+      // Write Smi from rhs to r3 and r2 in double format.  r9 is scratch.
+      __ mov(r7, Operand(rhs));
+      ConvertToDoubleStub stub1(r3, r2, r7, r9);
+      __ push(lr);
+      __ Call(stub1.GetCode(), RelocInfo::CODE_TARGET);
+      // Write Smi from lhs to r1 and r0 in double format.  r9 is scratch.
+      __ mov(r7, Operand(lhs));
+      ConvertToDoubleStub stub2(r1, r0, r7, r9);
+      __ Call(stub2.GetCode(), RelocInfo::CODE_TARGET);
+      __ pop(lr);
+    }
+    __ jmp(&do_the_call);  // Tail call.  No return.
+  }
+
+  // We branch here if at least one of r0 and r1 is not a Smi.
+  __ bind(not_smi);
+  __ LoadRoot(heap_number_map, Heap::kHeapNumberMapRootIndex);
+
+  // After this point we have the left hand side in r1 and the right hand side
+  // in r0.
+  if (lhs.is(r0)) {
+    __ Swap(r0, r1, ip);
+  }
+
+  // The type transition also calculates the answer.
+  bool generate_code_to_calculate_answer = true;
+
+  if (ShouldGenerateFPCode()) {
+    if (runtime_operands_type_ == BinaryOpIC::DEFAULT) {
+      switch (op_) {
+        case Token::ADD:
+        case Token::SUB:
+        case Token::MUL:
+        case Token::DIV:
+          GenerateTypeTransition(masm);  // Tail call.
+          generate_code_to_calculate_answer = false;
+          break;
+
+        default:
+          break;
+      }
+    }
+
+    if (generate_code_to_calculate_answer) {
+      Label r0_is_smi, r1_is_smi, finished_loading_r0, finished_loading_r1;
+      if (mode_ == NO_OVERWRITE) {
+        // In the case where there is no chance of an overwritable float we may
+        // as well do the allocation immediately while r0 and r1 are untouched.
+        __ AllocateHeapNumber(r5, r3, r7, heap_number_map, &slow);
+      }
+
+      // Move r0 to a double in r2-r3.
+      __ tst(r0, Operand(kSmiTagMask));
+      __ b(eq, &r0_is_smi);  // It's a Smi so don't check it's a heap number.
+      __ ldr(r4, FieldMemOperand(r0, HeapObject::kMapOffset));
+      __ AssertRegisterIsRoot(heap_number_map, Heap::kHeapNumberMapRootIndex);
+      __ cmp(r4, heap_number_map);
+      __ b(ne, &slow);
+      if (mode_ == OVERWRITE_RIGHT) {
+        __ mov(r5, Operand(r0));  // Overwrite this heap number.
+      }
+      if (use_fp_registers) {
+        CpuFeatures::Scope scope(VFP3);
+        // Load the double from tagged HeapNumber r0 to d7.
+        __ sub(r7, r0, Operand(kHeapObjectTag));
+        __ vldr(d7, r7, HeapNumber::kValueOffset);
+      } else {
+        // Calling convention says that second double is in r2 and r3.
+        __ Ldrd(r2, r3, FieldMemOperand(r0, HeapNumber::kValueOffset));
+      }
+      __ jmp(&finished_loading_r0);
+      __ bind(&r0_is_smi);
+      if (mode_ == OVERWRITE_RIGHT) {
+        // We can't overwrite a Smi so get address of new heap number into r5.
+      __ AllocateHeapNumber(r5, r4, r7, heap_number_map, &slow);
+      }
+
+      if (CpuFeatures::IsSupported(VFP3)) {
+        CpuFeatures::Scope scope(VFP3);
+        // Convert smi in r0 to double in d7.
+        __ mov(r7, Operand(r0, ASR, kSmiTagSize));
+        __ vmov(s15, r7);
+        __ vcvt_f64_s32(d7, s15);
+        if (!use_fp_registers) {
+          __ vmov(r2, r3, d7);
+        }
+      } else {
+        // Write Smi from r0 to r3 and r2 in double format.
+        __ mov(r7, Operand(r0));
+        ConvertToDoubleStub stub3(r3, r2, r7, r4);
+        __ push(lr);
+        __ Call(stub3.GetCode(), RelocInfo::CODE_TARGET);
+        __ pop(lr);
+      }
+
+      // HEAP_NUMBERS stub is slower than GENERIC on a pair of smis.
+      // r0 is known to be a smi. If r1 is also a smi then switch to GENERIC.
+      Label r1_is_not_smi;
+      if (runtime_operands_type_ == BinaryOpIC::HEAP_NUMBERS) {
+        __ tst(r1, Operand(kSmiTagMask));
+        __ b(ne, &r1_is_not_smi);
+        GenerateTypeTransition(masm);  // Tail call.
+      }
+
+      __ bind(&finished_loading_r0);
+
+      // Move r1 to a double in r0-r1.
+      __ tst(r1, Operand(kSmiTagMask));
+      __ b(eq, &r1_is_smi);  // It's a Smi so don't check it's a heap number.
+      __ bind(&r1_is_not_smi);
+      __ ldr(r4, FieldMemOperand(r1, HeapNumber::kMapOffset));
+      __ AssertRegisterIsRoot(heap_number_map, Heap::kHeapNumberMapRootIndex);
+      __ cmp(r4, heap_number_map);
+      __ b(ne, &slow);
+      if (mode_ == OVERWRITE_LEFT) {
+        __ mov(r5, Operand(r1));  // Overwrite this heap number.
+      }
+      if (use_fp_registers) {
+        CpuFeatures::Scope scope(VFP3);
+        // Load the double from tagged HeapNumber r1 to d6.
+        __ sub(r7, r1, Operand(kHeapObjectTag));
+        __ vldr(d6, r7, HeapNumber::kValueOffset);
+      } else {
+        // Calling convention says that first double is in r0 and r1.
+        __ Ldrd(r0, r1, FieldMemOperand(r1, HeapNumber::kValueOffset));
+      }
+      __ jmp(&finished_loading_r1);
+      __ bind(&r1_is_smi);
+      if (mode_ == OVERWRITE_LEFT) {
+        // We can't overwrite a Smi so get address of new heap number into r5.
+      __ AllocateHeapNumber(r5, r4, r7, heap_number_map, &slow);
+      }
+
+      if (CpuFeatures::IsSupported(VFP3)) {
+        CpuFeatures::Scope scope(VFP3);
+        // Convert smi in r1 to double in d6.
+        __ mov(r7, Operand(r1, ASR, kSmiTagSize));
+        __ vmov(s13, r7);
+        __ vcvt_f64_s32(d6, s13);
+        if (!use_fp_registers) {
+          __ vmov(r0, r1, d6);
+        }
+      } else {
+        // Write Smi from r1 to r1 and r0 in double format.
+        __ mov(r7, Operand(r1));
+        ConvertToDoubleStub stub4(r1, r0, r7, r9);
+        __ push(lr);
+        __ Call(stub4.GetCode(), RelocInfo::CODE_TARGET);
+        __ pop(lr);
+      }
+
+      __ bind(&finished_loading_r1);
+    }
+
+    if (generate_code_to_calculate_answer || do_the_call.is_linked()) {
+      __ bind(&do_the_call);
+      // If we are inlining the operation using VFP3 instructions for
+      // add, subtract, multiply, or divide, the arguments are in d6 and d7.
+      if (use_fp_registers) {
+        CpuFeatures::Scope scope(VFP3);
+        // ARMv7 VFP3 instructions to implement
+        // double precision, add, subtract, multiply, divide.
+
+        if (Token::MUL == op_) {
+          __ vmul(d5, d6, d7);
+        } else if (Token::DIV == op_) {
+          __ vdiv(d5, d6, d7);
+        } else if (Token::ADD == op_) {
+          __ vadd(d5, d6, d7);
+        } else if (Token::SUB == op_) {
+          __ vsub(d5, d6, d7);
+        } else {
+          UNREACHABLE();
+        }
+        __ sub(r0, r5, Operand(kHeapObjectTag));
+        __ vstr(d5, r0, HeapNumber::kValueOffset);
+        __ add(r0, r0, Operand(kHeapObjectTag));
+        __ mov(pc, lr);
+      } else {
+        // If we did not inline the operation, then the arguments are in:
+        // r0: Left value (least significant part of mantissa).
+        // r1: Left value (sign, exponent, top of mantissa).
+        // r2: Right value (least significant part of mantissa).
+        // r3: Right value (sign, exponent, top of mantissa).
+        // r5: Address of heap number for result.
+
+        __ push(lr);   // For later.
+        __ PrepareCallCFunction(4, r4);  // Two doubles count as 4 arguments.
+        // Call C routine that may not cause GC or other trouble. r5 is callee
+        // save.
+        __ CallCFunction(ExternalReference::double_fp_operation(op_), 4);
+        // Store answer in the overwritable heap number.
+    #if !defined(USE_ARM_EABI)
+        // Double returned in fp coprocessor register 0 and 1, encoded as
+        // register cr8.  Offsets must be divisible by 4 for coprocessor so we
+        // need to substract the tag from r5.
+        __ sub(r4, r5, Operand(kHeapObjectTag));
+        __ stc(p1, cr8, MemOperand(r4, HeapNumber::kValueOffset));
+    #else
+        // Double returned in registers 0 and 1.
+        __ Strd(r0, r1, FieldMemOperand(r5, HeapNumber::kValueOffset));
+    #endif
+        __ mov(r0, Operand(r5));
+        // And we are done.
+        __ pop(pc);
+      }
+    }
+  }
+
+  if (!generate_code_to_calculate_answer &&
+      !slow_reverse.is_linked() &&
+      !slow.is_linked()) {
+    return;
+  }
+
+  if (lhs.is(r0)) {
+    __ b(&slow);
+    __ bind(&slow_reverse);
+    __ Swap(r0, r1, ip);
+  }
+
+  heap_number_map = no_reg;  // Don't use this any more from here on.
+
+  // We jump to here if something goes wrong (one param is not a number of any
+  // sort or new-space allocation fails).
+  __ bind(&slow);
+
+  // Push arguments to the stack
+  __ Push(r1, r0);
+
+  if (Token::ADD == op_) {
+    // Test for string arguments before calling runtime.
+    // r1 : first argument
+    // r0 : second argument
+    // sp[0] : second argument
+    // sp[4] : first argument
+
+    Label not_strings, not_string1, string1, string1_smi2;
+    __ tst(r1, Operand(kSmiTagMask));
+    __ b(eq, &not_string1);
+    __ CompareObjectType(r1, r2, r2, FIRST_NONSTRING_TYPE);
+    __ b(ge, &not_string1);
+
+    // First argument is a a string, test second.
+    __ tst(r0, Operand(kSmiTagMask));
+    __ b(eq, &string1_smi2);
+    __ CompareObjectType(r0, r2, r2, FIRST_NONSTRING_TYPE);
+    __ b(ge, &string1);
+
+    // First and second argument are strings.
+    StringAddStub string_add_stub(NO_STRING_CHECK_IN_STUB);
+    __ TailCallStub(&string_add_stub);
+
+    __ bind(&string1_smi2);
+    // First argument is a string, second is a smi. Try to lookup the number
+    // string for the smi in the number string cache.
+    NumberToStringStub::GenerateLookupNumberStringCache(
+        masm, r0, r2, r4, r5, r6, true, &string1);
+
+    // Replace second argument on stack and tailcall string add stub to make
+    // the result.
+    __ str(r2, MemOperand(sp, 0));
+    __ TailCallStub(&string_add_stub);
+
+    // Only first argument is a string.
+    __ bind(&string1);
+    __ InvokeBuiltin(Builtins::STRING_ADD_LEFT, JUMP_JS);
+
+    // First argument was not a string, test second.
+    __ bind(&not_string1);
+    __ tst(r0, Operand(kSmiTagMask));
+    __ b(eq, &not_strings);
+    __ CompareObjectType(r0, r2, r2, FIRST_NONSTRING_TYPE);
+    __ b(ge, &not_strings);
+
+    // Only second argument is a string.
+    __ InvokeBuiltin(Builtins::STRING_ADD_RIGHT, JUMP_JS);
+
+    __ bind(&not_strings);
+  }
+
+  __ InvokeBuiltin(builtin, JUMP_JS);  // Tail call.  No return.
+}
+
+
+// Tries to get a signed int32 out of a double precision floating point heap
+// number.  Rounds towards 0.  Fastest for doubles that are in the ranges
+// -0x7fffffff to -0x40000000 or 0x40000000 to 0x7fffffff.  This corresponds
+// almost to the range of signed int32 values that are not Smis.  Jumps to the
+// label 'slow' if the double isn't in the range -0x80000000.0 to 0x80000000.0
+// (excluding the endpoints).
+static void GetInt32(MacroAssembler* masm,
+                     Register source,
+                     Register dest,
+                     Register scratch,
+                     Register scratch2,
+                     Label* slow) {
+  Label right_exponent, done;
+  // Get exponent word.
+  __ ldr(scratch, FieldMemOperand(source, HeapNumber::kExponentOffset));
+  // Get exponent alone in scratch2.
+  __ Ubfx(scratch2,
+          scratch,
+          HeapNumber::kExponentShift,
+          HeapNumber::kExponentBits);
+  // Load dest with zero.  We use this either for the final shift or
+  // for the answer.
+  __ mov(dest, Operand(0));
+  // Check whether the exponent matches a 32 bit signed int that is not a Smi.
+  // A non-Smi integer is 1.xxx * 2^30 so the exponent is 30 (biased).  This is
+  // the exponent that we are fastest at and also the highest exponent we can
+  // handle here.
+  const uint32_t non_smi_exponent = HeapNumber::kExponentBias + 30;
+  // The non_smi_exponent, 0x41d, is too big for ARM's immediate field so we
+  // split it up to avoid a constant pool entry.  You can't do that in general
+  // for cmp because of the overflow flag, but we know the exponent is in the
+  // range 0-2047 so there is no overflow.
+  int fudge_factor = 0x400;
+  __ sub(scratch2, scratch2, Operand(fudge_factor));
+  __ cmp(scratch2, Operand(non_smi_exponent - fudge_factor));
+  // If we have a match of the int32-but-not-Smi exponent then skip some logic.
+  __ b(eq, &right_exponent);
+  // If the exponent is higher than that then go to slow case.  This catches
+  // numbers that don't fit in a signed int32, infinities and NaNs.
+  __ b(gt, slow);
+
+  // We know the exponent is smaller than 30 (biased).  If it is less than
+  // 0 (biased) then the number is smaller in magnitude than 1.0 * 2^0, ie
+  // it rounds to zero.
+  const uint32_t zero_exponent = HeapNumber::kExponentBias + 0;
+  __ sub(scratch2, scratch2, Operand(zero_exponent - fudge_factor), SetCC);
+  // Dest already has a Smi zero.
+  __ b(lt, &done);
+  if (!CpuFeatures::IsSupported(VFP3)) {
+    // We have an exponent between 0 and 30 in scratch2.  Subtract from 30 to
+    // get how much to shift down.
+    __ rsb(dest, scratch2, Operand(30));
+  }
+  __ bind(&right_exponent);
+  if (CpuFeatures::IsSupported(VFP3)) {
+    CpuFeatures::Scope scope(VFP3);
+    // ARMv7 VFP3 instructions implementing double precision to integer
+    // conversion using round to zero.
+    __ ldr(scratch2, FieldMemOperand(source, HeapNumber::kMantissaOffset));
+    __ vmov(d7, scratch2, scratch);
+    __ vcvt_s32_f64(s15, d7);
+    __ vmov(dest, s15);
+  } else {
+    // Get the top bits of the mantissa.
+    __ and_(scratch2, scratch, Operand(HeapNumber::kMantissaMask));
+    // Put back the implicit 1.
+    __ orr(scratch2, scratch2, Operand(1 << HeapNumber::kExponentShift));
+    // Shift up the mantissa bits to take up the space the exponent used to
+    // take. We just orred in the implicit bit so that took care of one and
+    // we want to leave the sign bit 0 so we subtract 2 bits from the shift
+    // distance.
+    const int shift_distance = HeapNumber::kNonMantissaBitsInTopWord - 2;
+    __ mov(scratch2, Operand(scratch2, LSL, shift_distance));
+    // Put sign in zero flag.
+    __ tst(scratch, Operand(HeapNumber::kSignMask));
+    // Get the second half of the double. For some exponents we don't
+    // actually need this because the bits get shifted out again, but
+    // it's probably slower to test than just to do it.
+    __ ldr(scratch, FieldMemOperand(source, HeapNumber::kMantissaOffset));
+    // Shift down 22 bits to get the last 10 bits.
+    __ orr(scratch, scratch2, Operand(scratch, LSR, 32 - shift_distance));
+    // Move down according to the exponent.
+    __ mov(dest, Operand(scratch, LSR, dest));
+    // Fix sign if sign bit was set.
+    __ rsb(dest, dest, Operand(0), LeaveCC, ne);
+  }
+  __ bind(&done);
+}
+
+// For bitwise ops where the inputs are not both Smis we here try to determine
+// whether both inputs are either Smis or at least heap numbers that can be
+// represented by a 32 bit signed value.  We truncate towards zero as required
+// by the ES spec.  If this is the case we do the bitwise op and see if the
+// result is a Smi.  If so, great, otherwise we try to find a heap number to
+// write the answer into (either by allocating or by overwriting).
+// On entry the operands are in lhs and rhs.  On exit the answer is in r0.
+void GenericBinaryOpStub::HandleNonSmiBitwiseOp(MacroAssembler* masm,
+                                                Register lhs,
+                                                Register rhs) {
+  Label slow, result_not_a_smi;
+  Label rhs_is_smi, lhs_is_smi;
+  Label done_checking_rhs, done_checking_lhs;
+
+  Register heap_number_map = r6;
+  __ LoadRoot(heap_number_map, Heap::kHeapNumberMapRootIndex);
+
+  __ tst(lhs, Operand(kSmiTagMask));
+  __ b(eq, &lhs_is_smi);  // It's a Smi so don't check it's a heap number.
+  __ ldr(r4, FieldMemOperand(lhs, HeapNumber::kMapOffset));
+  __ cmp(r4, heap_number_map);
+  __ b(ne, &slow);
+  GetInt32(masm, lhs, r3, r5, r4, &slow);
+  __ jmp(&done_checking_lhs);
+  __ bind(&lhs_is_smi);
+  __ mov(r3, Operand(lhs, ASR, 1));
+  __ bind(&done_checking_lhs);
+
+  __ tst(rhs, Operand(kSmiTagMask));
+  __ b(eq, &rhs_is_smi);  // It's a Smi so don't check it's a heap number.
+  __ ldr(r4, FieldMemOperand(rhs, HeapNumber::kMapOffset));
+  __ cmp(r4, heap_number_map);
+  __ b(ne, &slow);
+  GetInt32(masm, rhs, r2, r5, r4, &slow);
+  __ jmp(&done_checking_rhs);
+  __ bind(&rhs_is_smi);
+  __ mov(r2, Operand(rhs, ASR, 1));
+  __ bind(&done_checking_rhs);
+
+  ASSERT(((lhs.is(r0) && rhs.is(r1)) || (lhs.is(r1) && rhs.is(r0))));
+
+  // r0 and r1: Original operands (Smi or heap numbers).
+  // r2 and r3: Signed int32 operands.
+  switch (op_) {
+    case Token::BIT_OR:  __ orr(r2, r2, Operand(r3)); break;
+    case Token::BIT_XOR: __ eor(r2, r2, Operand(r3)); break;
+    case Token::BIT_AND: __ and_(r2, r2, Operand(r3)); break;
+    case Token::SAR:
+      // Use only the 5 least significant bits of the shift count.
+      __ and_(r2, r2, Operand(0x1f));
+      __ mov(r2, Operand(r3, ASR, r2));
+      break;
+    case Token::SHR:
+      // Use only the 5 least significant bits of the shift count.
+      __ and_(r2, r2, Operand(0x1f));
+      __ mov(r2, Operand(r3, LSR, r2), SetCC);
+      // SHR is special because it is required to produce a positive answer.
+      // The code below for writing into heap numbers isn't capable of writing
+      // the register as an unsigned int so we go to slow case if we hit this
+      // case.
+      if (CpuFeatures::IsSupported(VFP3)) {
+        __ b(mi, &result_not_a_smi);
+      } else {
+        __ b(mi, &slow);
+      }
+      break;
+    case Token::SHL:
+      // Use only the 5 least significant bits of the shift count.
+      __ and_(r2, r2, Operand(0x1f));
+      __ mov(r2, Operand(r3, LSL, r2));
+      break;
+    default: UNREACHABLE();
+  }
+  // check that the *signed* result fits in a smi
+  __ add(r3, r2, Operand(0x40000000), SetCC);
+  __ b(mi, &result_not_a_smi);
+  __ mov(r0, Operand(r2, LSL, kSmiTagSize));
+  __ Ret();
+
+  Label have_to_allocate, got_a_heap_number;
+  __ bind(&result_not_a_smi);
+  switch (mode_) {
+    case OVERWRITE_RIGHT: {
+      __ tst(rhs, Operand(kSmiTagMask));
+      __ b(eq, &have_to_allocate);
+      __ mov(r5, Operand(rhs));
+      break;
+    }
+    case OVERWRITE_LEFT: {
+      __ tst(lhs, Operand(kSmiTagMask));
+      __ b(eq, &have_to_allocate);
+      __ mov(r5, Operand(lhs));
+      break;
+    }
+    case NO_OVERWRITE: {
+      // Get a new heap number in r5.  r4 and r7 are scratch.
+      __ AllocateHeapNumber(r5, r4, r7, heap_number_map, &slow);
+    }
+    default: break;
+  }
+  __ bind(&got_a_heap_number);
+  // r2: Answer as signed int32.
+  // r5: Heap number to write answer into.
+
+  // Nothing can go wrong now, so move the heap number to r0, which is the
+  // result.
+  __ mov(r0, Operand(r5));
+
+  if (CpuFeatures::IsSupported(VFP3)) {
+    // Convert the int32 in r2 to the heap number in r0. r3 is corrupted.
+    CpuFeatures::Scope scope(VFP3);
+    __ vmov(s0, r2);
+    if (op_ == Token::SHR) {
+      __ vcvt_f64_u32(d0, s0);
+    } else {
+      __ vcvt_f64_s32(d0, s0);
+    }
+    __ sub(r3, r0, Operand(kHeapObjectTag));
+    __ vstr(d0, r3, HeapNumber::kValueOffset);
+    __ Ret();
+  } else {
+    // Tail call that writes the int32 in r2 to the heap number in r0, using
+    // r3 as scratch.  r0 is preserved and returned.
+    WriteInt32ToHeapNumberStub stub(r2, r0, r3);
+    __ TailCallStub(&stub);
+  }
+
+  if (mode_ != NO_OVERWRITE) {
+    __ bind(&have_to_allocate);
+    // Get a new heap number in r5.  r4 and r7 are scratch.
+    __ AllocateHeapNumber(r5, r4, r7, heap_number_map, &slow);
+    __ jmp(&got_a_heap_number);
+  }
+
+  // If all else failed then we go to the runtime system.
+  __ bind(&slow);
+  __ Push(lhs, rhs);  // Restore stack.
+  switch (op_) {
+    case Token::BIT_OR:
+      __ InvokeBuiltin(Builtins::BIT_OR, JUMP_JS);
+      break;
+    case Token::BIT_AND:
+      __ InvokeBuiltin(Builtins::BIT_AND, JUMP_JS);
+      break;
+    case Token::BIT_XOR:
+      __ InvokeBuiltin(Builtins::BIT_XOR, JUMP_JS);
+      break;
+    case Token::SAR:
+      __ InvokeBuiltin(Builtins::SAR, JUMP_JS);
+      break;
+    case Token::SHR:
+      __ InvokeBuiltin(Builtins::SHR, JUMP_JS);
+      break;
+    case Token::SHL:
+      __ InvokeBuiltin(Builtins::SHL, JUMP_JS);
+      break;
+    default:
+      UNREACHABLE();
+  }
+}
+
+
+
+
+// This function takes the known int in a register for the cases
+// where it doesn't know a good trick, and may deliver
+// a result that needs shifting.
+static void MultiplyByKnownIntInStub(
+    MacroAssembler* masm,
+    Register result,
+    Register source,
+    Register known_int_register,   // Smi tagged.
+    int known_int,
+    int* required_shift) {  // Including Smi tag shift
+  switch (known_int) {
+    case 3:
+      __ add(result, source, Operand(source, LSL, 1));
+      *required_shift = 1;
+      break;
+    case 5:
+      __ add(result, source, Operand(source, LSL, 2));
+      *required_shift = 1;
+      break;
+    case 6:
+      __ add(result, source, Operand(source, LSL, 1));
+      *required_shift = 2;
+      break;
+    case 7:
+      __ rsb(result, source, Operand(source, LSL, 3));
+      *required_shift = 1;
+      break;
+    case 9:
+      __ add(result, source, Operand(source, LSL, 3));
+      *required_shift = 1;
+      break;
+    case 10:
+      __ add(result, source, Operand(source, LSL, 2));
+      *required_shift = 2;
+      break;
+    default:
+      ASSERT(!IsPowerOf2(known_int));  // That would be very inefficient.
+      __ mul(result, source, known_int_register);
+      *required_shift = 0;
+  }
+}
+
+
+// This uses versions of the sum-of-digits-to-see-if-a-number-is-divisible-by-3
+// trick.  See http://en.wikipedia.org/wiki/Divisibility_rule
+// Takes the sum of the digits base (mask + 1) repeatedly until we have a
+// number from 0 to mask.  On exit the 'eq' condition flags are set if the
+// answer is exactly the mask.
+void IntegerModStub::DigitSum(MacroAssembler* masm,
+                              Register lhs,
+                              int mask,
+                              int shift,
+                              Label* entry) {
+  ASSERT(mask > 0);
+  ASSERT(mask <= 0xff);  // This ensures we don't need ip to use it.
+  Label loop;
+  __ bind(&loop);
+  __ and_(ip, lhs, Operand(mask));
+  __ add(lhs, ip, Operand(lhs, LSR, shift));
+  __ bind(entry);
+  __ cmp(lhs, Operand(mask));
+  __ b(gt, &loop);
+}
+
+
+void IntegerModStub::DigitSum(MacroAssembler* masm,
+                              Register lhs,
+                              Register scratch,
+                              int mask,
+                              int shift1,
+                              int shift2,
+                              Label* entry) {
+  ASSERT(mask > 0);
+  ASSERT(mask <= 0xff);  // This ensures we don't need ip to use it.
+  Label loop;
+  __ bind(&loop);
+  __ bic(scratch, lhs, Operand(mask));
+  __ and_(ip, lhs, Operand(mask));
+  __ add(lhs, ip, Operand(lhs, LSR, shift1));
+  __ add(lhs, lhs, Operand(scratch, LSR, shift2));
+  __ bind(entry);
+  __ cmp(lhs, Operand(mask));
+  __ b(gt, &loop);
+}
+
+
+// Splits the number into two halves (bottom half has shift bits).  The top
+// half is subtracted from the bottom half.  If the result is negative then
+// rhs is added.
+void IntegerModStub::ModGetInRangeBySubtraction(MacroAssembler* masm,
+                                                Register lhs,
+                                                int shift,
+                                                int rhs) {
+  int mask = (1 << shift) - 1;
+  __ and_(ip, lhs, Operand(mask));
+  __ sub(lhs, ip, Operand(lhs, LSR, shift), SetCC);
+  __ add(lhs, lhs, Operand(rhs), LeaveCC, mi);
+}
+
+
+void IntegerModStub::ModReduce(MacroAssembler* masm,
+                               Register lhs,
+                               int max,
+                               int denominator) {
+  int limit = denominator;
+  while (limit * 2 <= max) limit *= 2;
+  while (limit >= denominator) {
+    __ cmp(lhs, Operand(limit));
+    __ sub(lhs, lhs, Operand(limit), LeaveCC, ge);
+    limit >>= 1;
+  }
+}
+
+
+void IntegerModStub::ModAnswer(MacroAssembler* masm,
+                               Register result,
+                               Register shift_distance,
+                               Register mask_bits,
+                               Register sum_of_digits) {
+  __ add(result, mask_bits, Operand(sum_of_digits, LSL, shift_distance));
+  __ Ret();
+}
+
+
+// See comment for class.
+void IntegerModStub::Generate(MacroAssembler* masm) {
+  __ mov(lhs_, Operand(lhs_, LSR, shift_distance_));
+  __ bic(odd_number_, odd_number_, Operand(1));
+  __ mov(odd_number_, Operand(odd_number_, LSL, 1));
+  // We now have (odd_number_ - 1) * 2 in the register.
+  // Build a switch out of branches instead of data because it avoids
+  // having to teach the assembler about intra-code-object pointers
+  // that are not in relative branch instructions.
+  Label mod3, mod5, mod7, mod9, mod11, mod13, mod15, mod17, mod19;
+  Label mod21, mod23, mod25;
+  { Assembler::BlockConstPoolScope block_const_pool(masm);
+    __ add(pc, pc, Operand(odd_number_));
+    // When you read pc it is always 8 ahead, but when you write it you always
+    // write the actual value.  So we put in two nops to take up the slack.
+    __ nop();
+    __ nop();
+    __ b(&mod3);
+    __ b(&mod5);
+    __ b(&mod7);
+    __ b(&mod9);
+    __ b(&mod11);
+    __ b(&mod13);
+    __ b(&mod15);
+    __ b(&mod17);
+    __ b(&mod19);
+    __ b(&mod21);
+    __ b(&mod23);
+    __ b(&mod25);
+  }
+
+  // For each denominator we find a multiple that is almost only ones
+  // when expressed in binary.  Then we do the sum-of-digits trick for
+  // that number.  If the multiple is not 1 then we have to do a little
+  // more work afterwards to get the answer into the 0-denominator-1
+  // range.
+  DigitSum(masm, lhs_, 3, 2, &mod3);  // 3 = b11.
+  __ sub(lhs_, lhs_, Operand(3), LeaveCC, eq);
+  ModAnswer(masm, result_, shift_distance_, mask_bits_, lhs_);
+
+  DigitSum(masm, lhs_, 0xf, 4, &mod5);  // 5 * 3 = b1111.
+  ModGetInRangeBySubtraction(masm, lhs_, 2, 5);
+  ModAnswer(masm, result_, shift_distance_, mask_bits_, lhs_);
+
+  DigitSum(masm, lhs_, 7, 3, &mod7);  // 7 = b111.
+  __ sub(lhs_, lhs_, Operand(7), LeaveCC, eq);
+  ModAnswer(masm, result_, shift_distance_, mask_bits_, lhs_);
+
+  DigitSum(masm, lhs_, 0x3f, 6, &mod9);  // 7 * 9 = b111111.
+  ModGetInRangeBySubtraction(masm, lhs_, 3, 9);
+  ModAnswer(masm, result_, shift_distance_, mask_bits_, lhs_);
+
+  DigitSum(masm, lhs_, r5, 0x3f, 6, 3, &mod11);  // 5 * 11 = b110111.
+  ModReduce(masm, lhs_, 0x3f, 11);
+  ModAnswer(masm, result_, shift_distance_, mask_bits_, lhs_);
+
+  DigitSum(masm, lhs_, r5, 0xff, 8, 5, &mod13);  // 19 * 13 = b11110111.
+  ModReduce(masm, lhs_, 0xff, 13);
+  ModAnswer(masm, result_, shift_distance_, mask_bits_, lhs_);
+
+  DigitSum(masm, lhs_, 0xf, 4, &mod15);  // 15 = b1111.
+  __ sub(lhs_, lhs_, Operand(15), LeaveCC, eq);
+  ModAnswer(masm, result_, shift_distance_, mask_bits_, lhs_);
+
+  DigitSum(masm, lhs_, 0xff, 8, &mod17);  // 15 * 17 = b11111111.
+  ModGetInRangeBySubtraction(masm, lhs_, 4, 17);
+  ModAnswer(masm, result_, shift_distance_, mask_bits_, lhs_);
+
+  DigitSum(masm, lhs_, r5, 0xff, 8, 5, &mod19);  // 13 * 19 = b11110111.
+  ModReduce(masm, lhs_, 0xff, 19);
+  ModAnswer(masm, result_, shift_distance_, mask_bits_, lhs_);
+
+  DigitSum(masm, lhs_, 0x3f, 6, &mod21);  // 3 * 21 = b111111.
+  ModReduce(masm, lhs_, 0x3f, 21);
+  ModAnswer(masm, result_, shift_distance_, mask_bits_, lhs_);
+
+  DigitSum(masm, lhs_, r5, 0xff, 8, 7, &mod23);  // 11 * 23 = b11111101.
+  ModReduce(masm, lhs_, 0xff, 23);
+  ModAnswer(masm, result_, shift_distance_, mask_bits_, lhs_);
+
+  DigitSum(masm, lhs_, r5, 0x7f, 7, 6, &mod25);  // 5 * 25 = b1111101.
+  ModReduce(masm, lhs_, 0x7f, 25);
+  ModAnswer(masm, result_, shift_distance_, mask_bits_, lhs_);
+}
+
+
+void GenericBinaryOpStub::Generate(MacroAssembler* masm) {
+  // lhs_ : x
+  // rhs_ : y
+  // r0   : result
+
+  Register result = r0;
+  Register lhs = lhs_;
+  Register rhs = rhs_;
+
+  // This code can't cope with other register allocations yet.
+  ASSERT(result.is(r0) &&
+         ((lhs.is(r0) && rhs.is(r1)) ||
+          (lhs.is(r1) && rhs.is(r0))));
+
+  Register smi_test_reg = r7;
+  Register scratch = r9;
+
+  // All ops need to know whether we are dealing with two Smis.  Set up
+  // smi_test_reg to tell us that.
+  if (ShouldGenerateSmiCode()) {
+    __ orr(smi_test_reg, lhs, Operand(rhs));
+  }
+
+  switch (op_) {
+    case Token::ADD: {
+      Label not_smi;
+      // Fast path.
+      if (ShouldGenerateSmiCode()) {
+        STATIC_ASSERT(kSmiTag == 0);  // Adjust code below.
+        __ tst(smi_test_reg, Operand(kSmiTagMask));
+        __ b(ne, &not_smi);
+        __ add(r0, r1, Operand(r0), SetCC);  // Add y optimistically.
+        // Return if no overflow.
+        __ Ret(vc);
+        __ sub(r0, r0, Operand(r1));  // Revert optimistic add.
+      }
+      HandleBinaryOpSlowCases(masm, &not_smi, lhs, rhs, Builtins::ADD);
+      break;
+    }
+
+    case Token::SUB: {
+      Label not_smi;
+      // Fast path.
+      if (ShouldGenerateSmiCode()) {
+        STATIC_ASSERT(kSmiTag == 0);  // Adjust code below.
+        __ tst(smi_test_reg, Operand(kSmiTagMask));
+        __ b(ne, &not_smi);
+        if (lhs.is(r1)) {
+          __ sub(r0, r1, Operand(r0), SetCC);  // Subtract y optimistically.
+          // Return if no overflow.
+          __ Ret(vc);
+          __ sub(r0, r1, Operand(r0));  // Revert optimistic subtract.
+        } else {
+          __ sub(r0, r0, Operand(r1), SetCC);  // Subtract y optimistically.
+          // Return if no overflow.
+          __ Ret(vc);
+          __ add(r0, r0, Operand(r1));  // Revert optimistic subtract.
+        }
+      }
+      HandleBinaryOpSlowCases(masm, &not_smi, lhs, rhs, Builtins::SUB);
+      break;
+    }
+
+    case Token::MUL: {
+      Label not_smi, slow;
+      if (ShouldGenerateSmiCode()) {
+        STATIC_ASSERT(kSmiTag == 0);  // adjust code below
+        __ tst(smi_test_reg, Operand(kSmiTagMask));
+        Register scratch2 = smi_test_reg;
+        smi_test_reg = no_reg;
+        __ b(ne, &not_smi);
+        // Remove tag from one operand (but keep sign), so that result is Smi.
+        __ mov(ip, Operand(rhs, ASR, kSmiTagSize));
+        // Do multiplication
+        // scratch = lower 32 bits of ip * lhs.
+        __ smull(scratch, scratch2, lhs, ip);
+        // Go slow on overflows (overflow bit is not set).
+        __ mov(ip, Operand(scratch, ASR, 31));
+        // No overflow if higher 33 bits are identical.
+        __ cmp(ip, Operand(scratch2));
+        __ b(ne, &slow);
+        // Go slow on zero result to handle -0.
+        __ tst(scratch, Operand(scratch));
+        __ mov(result, Operand(scratch), LeaveCC, ne);
+        __ Ret(ne);
+        // We need -0 if we were multiplying a negative number with 0 to get 0.
+        // We know one of them was zero.
+        __ add(scratch2, rhs, Operand(lhs), SetCC);
+        __ mov(result, Operand(Smi::FromInt(0)), LeaveCC, pl);
+        __ Ret(pl);  // Return Smi 0 if the non-zero one was positive.
+        // Slow case.  We fall through here if we multiplied a negative number
+        // with 0, because that would mean we should produce -0.
+        __ bind(&slow);
+      }
+      HandleBinaryOpSlowCases(masm, &not_smi, lhs, rhs, Builtins::MUL);
+      break;
+    }
+
+    case Token::DIV:
+    case Token::MOD: {
+      Label not_smi;
+      if (ShouldGenerateSmiCode() && specialized_on_rhs_) {
+        Label lhs_is_unsuitable;
+        __ BranchOnNotSmi(lhs, &not_smi);
+        if (IsPowerOf2(constant_rhs_)) {
+          if (op_ == Token::MOD) {
+            __ and_(rhs,
+                    lhs,
+                    Operand(0x80000000u | ((constant_rhs_ << kSmiTagSize) - 1)),
+                    SetCC);
+            // We now have the answer, but if the input was negative we also
+            // have the sign bit.  Our work is done if the result is
+            // positive or zero:
+            if (!rhs.is(r0)) {
+              __ mov(r0, rhs, LeaveCC, pl);
+            }
+            __ Ret(pl);
+            // A mod of a negative left hand side must return a negative number.
+            // Unfortunately if the answer is 0 then we must return -0.  And we
+            // already optimistically trashed rhs so we may need to restore it.
+            __ eor(rhs, rhs, Operand(0x80000000u), SetCC);
+            // Next two instructions are conditional on the answer being -0.
+            __ mov(rhs, Operand(Smi::FromInt(constant_rhs_)), LeaveCC, eq);
+            __ b(eq, &lhs_is_unsuitable);
+            // We need to subtract the dividend.  Eg. -3 % 4 == -3.
+            __ sub(result, rhs, Operand(Smi::FromInt(constant_rhs_)));
+          } else {
+            ASSERT(op_ == Token::DIV);
+            __ tst(lhs,
+                   Operand(0x80000000u | ((constant_rhs_ << kSmiTagSize) - 1)));
+            __ b(ne, &lhs_is_unsuitable);  // Go slow on negative or remainder.
+            int shift = 0;
+            int d = constant_rhs_;
+            while ((d & 1) == 0) {
+              d >>= 1;
+              shift++;
+            }
+            __ mov(r0, Operand(lhs, LSR, shift));
+            __ bic(r0, r0, Operand(kSmiTagMask));
+          }
+        } else {
+          // Not a power of 2.
+          __ tst(lhs, Operand(0x80000000u));
+          __ b(ne, &lhs_is_unsuitable);
+          // Find a fixed point reciprocal of the divisor so we can divide by
+          // multiplying.
+          double divisor = 1.0 / constant_rhs_;
+          int shift = 32;
+          double scale = 4294967296.0;  // 1 << 32.
+          uint32_t mul;
+          // Maximise the precision of the fixed point reciprocal.
+          while (true) {
+            mul = static_cast<uint32_t>(scale * divisor);
+            if (mul >= 0x7fffffff) break;
+            scale *= 2.0;
+            shift++;
+          }
+          mul++;
+          Register scratch2 = smi_test_reg;
+          smi_test_reg = no_reg;
+          __ mov(scratch2, Operand(mul));
+          __ umull(scratch, scratch2, scratch2, lhs);
+          __ mov(scratch2, Operand(scratch2, LSR, shift - 31));
+          // scratch2 is lhs / rhs.  scratch2 is not Smi tagged.
+          // rhs is still the known rhs.  rhs is Smi tagged.
+          // lhs is still the unkown lhs.  lhs is Smi tagged.
+          int required_scratch_shift = 0;  // Including the Smi tag shift of 1.
+          // scratch = scratch2 * rhs.
+          MultiplyByKnownIntInStub(masm,
+                                   scratch,
+                                   scratch2,
+                                   rhs,
+                                   constant_rhs_,
+                                   &required_scratch_shift);
+          // scratch << required_scratch_shift is now the Smi tagged rhs *
+          // (lhs / rhs) where / indicates integer division.
+          if (op_ == Token::DIV) {
+            __ cmp(lhs, Operand(scratch, LSL, required_scratch_shift));
+            __ b(ne, &lhs_is_unsuitable);  // There was a remainder.
+            __ mov(result, Operand(scratch2, LSL, kSmiTagSize));
+          } else {
+            ASSERT(op_ == Token::MOD);
+            __ sub(result, lhs, Operand(scratch, LSL, required_scratch_shift));
+          }
+        }
+        __ Ret();
+        __ bind(&lhs_is_unsuitable);
+      } else if (op_ == Token::MOD &&
+                 runtime_operands_type_ != BinaryOpIC::HEAP_NUMBERS &&
+                 runtime_operands_type_ != BinaryOpIC::STRINGS) {
+        // Do generate a bit of smi code for modulus even though the default for
+        // modulus is not to do it, but as the ARM processor has no coprocessor
+        // support for modulus checking for smis makes sense.  We can handle
+        // 1 to 25 times any power of 2.  This covers over half the numbers from
+        // 1 to 100 including all of the first 25.  (Actually the constants < 10
+        // are handled above by reciprocal multiplication.  We only get here for
+        // those cases if the right hand side is not a constant or for cases
+        // like 192 which is 3*2^6 and ends up in the 3 case in the integer mod
+        // stub.)
+        Label slow;
+        Label not_power_of_2;
+        ASSERT(!ShouldGenerateSmiCode());
+        STATIC_ASSERT(kSmiTag == 0);  // Adjust code below.
+        // Check for two positive smis.
+        __ orr(smi_test_reg, lhs, Operand(rhs));
+        __ tst(smi_test_reg, Operand(0x80000000u | kSmiTagMask));
+        __ b(ne, &slow);
+        // Check that rhs is a power of two and not zero.
+        Register mask_bits = r3;
+        __ sub(scratch, rhs, Operand(1), SetCC);
+        __ b(mi, &slow);
+        __ and_(mask_bits, rhs, Operand(scratch), SetCC);
+        __ b(ne, &not_power_of_2);
+        // Calculate power of two modulus.
+        __ and_(result, lhs, Operand(scratch));
+        __ Ret();
+
+        __ bind(&not_power_of_2);
+        __ eor(scratch, scratch, Operand(mask_bits));
+        // At least two bits are set in the modulus.  The high one(s) are in
+        // mask_bits and the low one is scratch + 1.
+        __ and_(mask_bits, scratch, Operand(lhs));
+        Register shift_distance = scratch;
+        scratch = no_reg;
+
+        // The rhs consists of a power of 2 multiplied by some odd number.
+        // The power-of-2 part we handle by putting the corresponding bits
+        // from the lhs in the mask_bits register, and the power in the
+        // shift_distance register.  Shift distance is never 0 due to Smi
+        // tagging.
+        __ CountLeadingZeros(r4, shift_distance, shift_distance);
+        __ rsb(shift_distance, r4, Operand(32));
+
+        // Now we need to find out what the odd number is. The last bit is
+        // always 1.
+        Register odd_number = r4;
+        __ mov(odd_number, Operand(rhs, LSR, shift_distance));
+        __ cmp(odd_number, Operand(25));
+        __ b(gt, &slow);
+
+        IntegerModStub stub(
+            result, shift_distance, odd_number, mask_bits, lhs, r5);
+        __ Jump(stub.GetCode(), RelocInfo::CODE_TARGET);  // Tail call.
+
+        __ bind(&slow);
+      }
+      HandleBinaryOpSlowCases(
+          masm,
+          &not_smi,
+          lhs,
+          rhs,
+          op_ == Token::MOD ? Builtins::MOD : Builtins::DIV);
+      break;
+    }
+
+    case Token::BIT_OR:
+    case Token::BIT_AND:
+    case Token::BIT_XOR:
+    case Token::SAR:
+    case Token::SHR:
+    case Token::SHL: {
+      Label slow;
+      STATIC_ASSERT(kSmiTag == 0);  // adjust code below
+      __ tst(smi_test_reg, Operand(kSmiTagMask));
+      __ b(ne, &slow);
+      Register scratch2 = smi_test_reg;
+      smi_test_reg = no_reg;
+      switch (op_) {
+        case Token::BIT_OR:  __ orr(result, rhs, Operand(lhs)); break;
+        case Token::BIT_AND: __ and_(result, rhs, Operand(lhs)); break;
+        case Token::BIT_XOR: __ eor(result, rhs, Operand(lhs)); break;
+        case Token::SAR:
+          // Remove tags from right operand.
+          __ GetLeastBitsFromSmi(scratch2, rhs, 5);
+          __ mov(result, Operand(lhs, ASR, scratch2));
+          // Smi tag result.
+          __ bic(result, result, Operand(kSmiTagMask));
+          break;
+        case Token::SHR:
+          // Remove tags from operands.  We can't do this on a 31 bit number
+          // because then the 0s get shifted into bit 30 instead of bit 31.
+          __ mov(scratch, Operand(lhs, ASR, kSmiTagSize));  // x
+          __ GetLeastBitsFromSmi(scratch2, rhs, 5);
+          __ mov(scratch, Operand(scratch, LSR, scratch2));
+          // Unsigned shift is not allowed to produce a negative number, so
+          // check the sign bit and the sign bit after Smi tagging.
+          __ tst(scratch, Operand(0xc0000000));
+          __ b(ne, &slow);
+          // Smi tag result.
+          __ mov(result, Operand(scratch, LSL, kSmiTagSize));
+          break;
+        case Token::SHL:
+          // Remove tags from operands.
+          __ mov(scratch, Operand(lhs, ASR, kSmiTagSize));  // x
+          __ GetLeastBitsFromSmi(scratch2, rhs, 5);
+          __ mov(scratch, Operand(scratch, LSL, scratch2));
+          // Check that the signed result fits in a Smi.
+          __ add(scratch2, scratch, Operand(0x40000000), SetCC);
+          __ b(mi, &slow);
+          __ mov(result, Operand(scratch, LSL, kSmiTagSize));
+          break;
+        default: UNREACHABLE();
+      }
+      __ Ret();
+      __ bind(&slow);
+      HandleNonSmiBitwiseOp(masm, lhs, rhs);
+      break;
+    }
+
+    default: UNREACHABLE();
+  }
+  // This code should be unreachable.
+  __ stop("Unreachable");
+
+  // Generate an unreachable reference to the DEFAULT stub so that it can be
+  // found at the end of this stub when clearing ICs at GC.
+  // TODO(kaznacheev): Check performance impact and get rid of this.
+  if (runtime_operands_type_ != BinaryOpIC::DEFAULT) {
+    GenericBinaryOpStub uninit(MinorKey(), BinaryOpIC::DEFAULT);
+    __ CallStub(&uninit);
+  }
+}
+
+
+void GenericBinaryOpStub::GenerateTypeTransition(MacroAssembler* masm) {
+  Label get_result;
+
+  __ Push(r1, r0);
+
+  __ mov(r2, Operand(Smi::FromInt(MinorKey())));
+  __ mov(r1, Operand(Smi::FromInt(op_)));
+  __ mov(r0, Operand(Smi::FromInt(runtime_operands_type_)));
+  __ Push(r2, r1, r0);
+
+  __ TailCallExternalReference(
+      ExternalReference(IC_Utility(IC::kBinaryOp_Patch)),
+      5,
+      1);
+}
+
+
+Handle<Code> GetBinaryOpStub(int key, BinaryOpIC::TypeInfo type_info) {
+  GenericBinaryOpStub stub(key, type_info);
+  return stub.GetCode();
+}
+
+
+void TranscendentalCacheStub::Generate(MacroAssembler* masm) {
+  // Argument is a number and is on stack and in r0.
+  Label runtime_call;
+  Label input_not_smi;
+  Label loaded;
+
+  if (CpuFeatures::IsSupported(VFP3)) {
+    // Load argument and check if it is a smi.
+    __ BranchOnNotSmi(r0, &input_not_smi);
+
+    CpuFeatures::Scope scope(VFP3);
+    // Input is a smi. Convert to double and load the low and high words
+    // of the double into r2, r3.
+    __ IntegerToDoubleConversionWithVFP3(r0, r3, r2);
+    __ b(&loaded);
+
+    __ bind(&input_not_smi);
+    // Check if input is a HeapNumber.
+    __ CheckMap(r0,
+                r1,
+                Heap::kHeapNumberMapRootIndex,
+                &runtime_call,
+                true);
+    // Input is a HeapNumber. Load it to a double register and store the
+    // low and high words into r2, r3.
+    __ Ldrd(r2, r3, FieldMemOperand(r0, HeapNumber::kValueOffset));
+
+    __ bind(&loaded);
+    // r2 = low 32 bits of double value
+    // r3 = high 32 bits of double value
+    // Compute hash (the shifts are arithmetic):
+    //   h = (low ^ high); h ^= h >> 16; h ^= h >> 8; h = h & (cacheSize - 1);
+    __ eor(r1, r2, Operand(r3));
+    __ eor(r1, r1, Operand(r1, ASR, 16));
+    __ eor(r1, r1, Operand(r1, ASR, 8));
+    ASSERT(IsPowerOf2(TranscendentalCache::kCacheSize));
+    __ And(r1, r1, Operand(TranscendentalCache::kCacheSize - 1));
+
+    // r2 = low 32 bits of double value.
+    // r3 = high 32 bits of double value.
+    // r1 = TranscendentalCache::hash(double value).
+    __ mov(r0,
+           Operand(ExternalReference::transcendental_cache_array_address()));
+    // r0 points to cache array.
+    __ ldr(r0, MemOperand(r0, type_ * sizeof(TranscendentalCache::caches_[0])));
+    // r0 points to the cache for the type type_.
+    // If NULL, the cache hasn't been initialized yet, so go through runtime.
+    __ cmp(r0, Operand(0));
+    __ b(eq, &runtime_call);
+
+#ifdef DEBUG
+    // Check that the layout of cache elements match expectations.
+    { TranscendentalCache::Element test_elem[2];
+      char* elem_start = reinterpret_cast<char*>(&test_elem[0]);
+      char* elem2_start = reinterpret_cast<char*>(&test_elem[1]);
+      char* elem_in0 = reinterpret_cast<char*>(&(test_elem[0].in[0]));
+      char* elem_in1 = reinterpret_cast<char*>(&(test_elem[0].in[1]));
+      char* elem_out = reinterpret_cast<char*>(&(test_elem[0].output));
+      CHECK_EQ(12, elem2_start - elem_start);  // Two uint_32's and a pointer.
+      CHECK_EQ(0, elem_in0 - elem_start);
+      CHECK_EQ(kIntSize, elem_in1 - elem_start);
+      CHECK_EQ(2 * kIntSize, elem_out - elem_start);
+    }
+#endif
+
+    // Find the address of the r1'st entry in the cache, i.e., &r0[r1*12].
+    __ add(r1, r1, Operand(r1, LSL, 1));
+    __ add(r0, r0, Operand(r1, LSL, 2));
+    // Check if cache matches: Double value is stored in uint32_t[2] array.
+    __ ldm(ia, r0, r4.bit()| r5.bit() | r6.bit());
+    __ cmp(r2, r4);
+    __ b(ne, &runtime_call);
+    __ cmp(r3, r5);
+    __ b(ne, &runtime_call);
+    // Cache hit. Load result, pop argument and return.
+    __ mov(r0, Operand(r6));
+    __ pop();
+    __ Ret();
+  }
+
+  __ bind(&runtime_call);
+  __ TailCallExternalReference(ExternalReference(RuntimeFunction()), 1, 1);
+}
+
+
+Runtime::FunctionId TranscendentalCacheStub::RuntimeFunction() {
+  switch (type_) {
+    // Add more cases when necessary.
+    case TranscendentalCache::SIN: return Runtime::kMath_sin;
+    case TranscendentalCache::COS: return Runtime::kMath_cos;
+    default:
+      UNIMPLEMENTED();
+      return Runtime::kAbort;
+  }
+}
+
+
+void StackCheckStub::Generate(MacroAssembler* masm) {
+  // Do tail-call to runtime routine.  Runtime routines expect at least one
+  // argument, so give it a Smi.
+  __ mov(r0, Operand(Smi::FromInt(0)));
+  __ push(r0);
+  __ TailCallRuntime(Runtime::kStackGuard, 1, 1);
+
+  __ StubReturn(1);
+}
+
+
+void GenericUnaryOpStub::Generate(MacroAssembler* masm) {
+  Label slow, done;
+
+  Register heap_number_map = r6;
+  __ LoadRoot(heap_number_map, Heap::kHeapNumberMapRootIndex);
+
+  if (op_ == Token::SUB) {
+    // Check whether the value is a smi.
+    Label try_float;
+    __ tst(r0, Operand(kSmiTagMask));
+    __ b(ne, &try_float);
+
+    // Go slow case if the value of the expression is zero
+    // to make sure that we switch between 0 and -0.
+    if (negative_zero_ == kStrictNegativeZero) {
+      // If we have to check for zero, then we can check for the max negative
+      // smi while we are at it.
+      __ bic(ip, r0, Operand(0x80000000), SetCC);
+      __ b(eq, &slow);
+      __ rsb(r0, r0, Operand(0));
+      __ StubReturn(1);
+    } else {
+      // The value of the expression is a smi and 0 is OK for -0.  Try
+      // optimistic subtraction '0 - value'.
+      __ rsb(r0, r0, Operand(0), SetCC);
+      __ StubReturn(1, vc);
+      // We don't have to reverse the optimistic neg since the only case
+      // where we fall through is the minimum negative Smi, which is the case
+      // where the neg leaves the register unchanged.
+      __ jmp(&slow);  // Go slow on max negative Smi.
+    }
+
+    __ bind(&try_float);
+    __ ldr(r1, FieldMemOperand(r0, HeapObject::kMapOffset));
+    __ AssertRegisterIsRoot(heap_number_map, Heap::kHeapNumberMapRootIndex);
+    __ cmp(r1, heap_number_map);
+    __ b(ne, &slow);
+    // r0 is a heap number.  Get a new heap number in r1.
+    if (overwrite_ == UNARY_OVERWRITE) {
+      __ ldr(r2, FieldMemOperand(r0, HeapNumber::kExponentOffset));
+      __ eor(r2, r2, Operand(HeapNumber::kSignMask));  // Flip sign.
+      __ str(r2, FieldMemOperand(r0, HeapNumber::kExponentOffset));
+    } else {
+      __ AllocateHeapNumber(r1, r2, r3, r6, &slow);
+      __ ldr(r3, FieldMemOperand(r0, HeapNumber::kMantissaOffset));
+      __ ldr(r2, FieldMemOperand(r0, HeapNumber::kExponentOffset));
+      __ str(r3, FieldMemOperand(r1, HeapNumber::kMantissaOffset));
+      __ eor(r2, r2, Operand(HeapNumber::kSignMask));  // Flip sign.
+      __ str(r2, FieldMemOperand(r1, HeapNumber::kExponentOffset));
+      __ mov(r0, Operand(r1));
+    }
+  } else if (op_ == Token::BIT_NOT) {
+    // Check if the operand is a heap number.
+    __ ldr(r1, FieldMemOperand(r0, HeapObject::kMapOffset));
+    __ AssertRegisterIsRoot(heap_number_map, Heap::kHeapNumberMapRootIndex);
+    __ cmp(r1, heap_number_map);
+    __ b(ne, &slow);
+
+    // Convert the heap number is r0 to an untagged integer in r1.
+    GetInt32(masm, r0, r1, r2, r3, &slow);
+
+    // Do the bitwise operation (move negated) and check if the result
+    // fits in a smi.
+    Label try_float;
+    __ mvn(r1, Operand(r1));
+    __ add(r2, r1, Operand(0x40000000), SetCC);
+    __ b(mi, &try_float);
+    __ mov(r0, Operand(r1, LSL, kSmiTagSize));
+    __ b(&done);
+
+    __ bind(&try_float);
+    if (!overwrite_ == UNARY_OVERWRITE) {
+      // Allocate a fresh heap number, but don't overwrite r0 until
+      // we're sure we can do it without going through the slow case
+      // that needs the value in r0.
+      __ AllocateHeapNumber(r2, r3, r4, r6, &slow);
+      __ mov(r0, Operand(r2));
+    }
+
+    if (CpuFeatures::IsSupported(VFP3)) {
+      // Convert the int32 in r1 to the heap number in r0. r2 is corrupted.
+      CpuFeatures::Scope scope(VFP3);
+      __ vmov(s0, r1);
+      __ vcvt_f64_s32(d0, s0);
+      __ sub(r2, r0, Operand(kHeapObjectTag));
+      __ vstr(d0, r2, HeapNumber::kValueOffset);
+    } else {
+      // WriteInt32ToHeapNumberStub does not trigger GC, so we do not
+      // have to set up a frame.
+      WriteInt32ToHeapNumberStub stub(r1, r0, r2);
+      __ push(lr);
+      __ Call(stub.GetCode(), RelocInfo::CODE_TARGET);
+      __ pop(lr);
+    }
+  } else {
+    UNIMPLEMENTED();
+  }
+
+  __ bind(&done);
+  __ StubReturn(1);
+
+  // Handle the slow case by jumping to the JavaScript builtin.
+  __ bind(&slow);
+  __ push(r0);
+  switch (op_) {
+    case Token::SUB:
+      __ InvokeBuiltin(Builtins::UNARY_MINUS, JUMP_JS);
+      break;
+    case Token::BIT_NOT:
+      __ InvokeBuiltin(Builtins::BIT_NOT, JUMP_JS);
+      break;
+    default:
+      UNREACHABLE();
+  }
+}
+
+
+void CEntryStub::GenerateThrowTOS(MacroAssembler* masm) {
+  // r0 holds the exception.
+
+  // Adjust this code if not the case.
+  STATIC_ASSERT(StackHandlerConstants::kSize == 4 * kPointerSize);
+
+  // Drop the sp to the top of the handler.
+  __ mov(r3, Operand(ExternalReference(Top::k_handler_address)));
+  __ ldr(sp, MemOperand(r3));
+
+  // Restore the next handler and frame pointer, discard handler state.
+  STATIC_ASSERT(StackHandlerConstants::kNextOffset == 0);
+  __ pop(r2);
+  __ str(r2, MemOperand(r3));
+  STATIC_ASSERT(StackHandlerConstants::kFPOffset == 2 * kPointerSize);
+  __ ldm(ia_w, sp, r3.bit() | fp.bit());  // r3: discarded state.
+
+  // Before returning we restore the context from the frame pointer if
+  // not NULL.  The frame pointer is NULL in the exception handler of a
+  // JS entry frame.
+  __ cmp(fp, Operand(0));
+  // Set cp to NULL if fp is NULL.
+  __ mov(cp, Operand(0), LeaveCC, eq);
+  // Restore cp otherwise.
+  __ ldr(cp, MemOperand(fp, StandardFrameConstants::kContextOffset), ne);
+#ifdef DEBUG
+  if (FLAG_debug_code) {
+    __ mov(lr, Operand(pc));
+  }
+#endif
+  STATIC_ASSERT(StackHandlerConstants::kPCOffset == 3 * kPointerSize);
+  __ pop(pc);
+}
+
+
+void CEntryStub::GenerateThrowUncatchable(MacroAssembler* masm,
+                                          UncatchableExceptionType type) {
+  // Adjust this code if not the case.
+  STATIC_ASSERT(StackHandlerConstants::kSize == 4 * kPointerSize);
+
+  // Drop sp to the top stack handler.
+  __ mov(r3, Operand(ExternalReference(Top::k_handler_address)));
+  __ ldr(sp, MemOperand(r3));
+
+  // Unwind the handlers until the ENTRY handler is found.
+  Label loop, done;
+  __ bind(&loop);
+  // Load the type of the current stack handler.
+  const int kStateOffset = StackHandlerConstants::kStateOffset;
+  __ ldr(r2, MemOperand(sp, kStateOffset));
+  __ cmp(r2, Operand(StackHandler::ENTRY));
+  __ b(eq, &done);
+  // Fetch the next handler in the list.
+  const int kNextOffset = StackHandlerConstants::kNextOffset;
+  __ ldr(sp, MemOperand(sp, kNextOffset));
+  __ jmp(&loop);
+  __ bind(&done);
+
+  // Set the top handler address to next handler past the current ENTRY handler.
+  STATIC_ASSERT(StackHandlerConstants::kNextOffset == 0);
+  __ pop(r2);
+  __ str(r2, MemOperand(r3));
+
+  if (type == OUT_OF_MEMORY) {
+    // Set external caught exception to false.
+    ExternalReference external_caught(Top::k_external_caught_exception_address);
+    __ mov(r0, Operand(false));
+    __ mov(r2, Operand(external_caught));
+    __ str(r0, MemOperand(r2));
+
+    // Set pending exception and r0 to out of memory exception.
+    Failure* out_of_memory = Failure::OutOfMemoryException();
+    __ mov(r0, Operand(reinterpret_cast<int32_t>(out_of_memory)));
+    __ mov(r2, Operand(ExternalReference(Top::k_pending_exception_address)));
+    __ str(r0, MemOperand(r2));
+  }
+
+  // Stack layout at this point. See also StackHandlerConstants.
+  // sp ->   state (ENTRY)
+  //         fp
+  //         lr
+
+  // Discard handler state (r2 is not used) and restore frame pointer.
+  STATIC_ASSERT(StackHandlerConstants::kFPOffset == 2 * kPointerSize);
+  __ ldm(ia_w, sp, r2.bit() | fp.bit());  // r2: discarded state.
+  // Before returning we restore the context from the frame pointer if
+  // not NULL.  The frame pointer is NULL in the exception handler of a
+  // JS entry frame.
+  __ cmp(fp, Operand(0));
+  // Set cp to NULL if fp is NULL.
+  __ mov(cp, Operand(0), LeaveCC, eq);
+  // Restore cp otherwise.
+  __ ldr(cp, MemOperand(fp, StandardFrameConstants::kContextOffset), ne);
+#ifdef DEBUG
+  if (FLAG_debug_code) {
+    __ mov(lr, Operand(pc));
+  }
+#endif
+  STATIC_ASSERT(StackHandlerConstants::kPCOffset == 3 * kPointerSize);
+  __ pop(pc);
+}
+
+
+void CEntryStub::GenerateCore(MacroAssembler* masm,
+                              Label* throw_normal_exception,
+                              Label* throw_termination_exception,
+                              Label* throw_out_of_memory_exception,
+                              bool do_gc,
+                              bool always_allocate,
+                              int frame_alignment_skew) {
+  // r0: result parameter for PerformGC, if any
+  // r4: number of arguments including receiver  (C callee-saved)
+  // r5: pointer to builtin function  (C callee-saved)
+  // r6: pointer to the first argument (C callee-saved)
+
+  if (do_gc) {
+    // Passing r0.
+    __ PrepareCallCFunction(1, r1);
+    __ CallCFunction(ExternalReference::perform_gc_function(), 1);
+  }
+
+  ExternalReference scope_depth =
+      ExternalReference::heap_always_allocate_scope_depth();
+  if (always_allocate) {
+    __ mov(r0, Operand(scope_depth));
+    __ ldr(r1, MemOperand(r0));
+    __ add(r1, r1, Operand(1));
+    __ str(r1, MemOperand(r0));
+  }
+
+  // Call C built-in.
+  // r0 = argc, r1 = argv
+  __ mov(r0, Operand(r4));
+  __ mov(r1, Operand(r6));
+
+  int frame_alignment = MacroAssembler::ActivationFrameAlignment();
+  int frame_alignment_mask = frame_alignment - 1;
+#if defined(V8_HOST_ARCH_ARM)
+  if (FLAG_debug_code) {
+    if (frame_alignment > kPointerSize) {
+      Label alignment_as_expected;
+      ASSERT(IsPowerOf2(frame_alignment));
+      __ sub(r2, sp, Operand(frame_alignment_skew));
+      __ tst(r2, 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
+
+  // Just before the call (jump) below lr is pushed, so the actual alignment is
+  // adding one to the current skew.
+  int alignment_before_call =
+      (frame_alignment_skew + kPointerSize) & frame_alignment_mask;
+  if (alignment_before_call > 0) {
+    // Push until the alignment before the call is met.
+    __ mov(r2, Operand(0));
+    for (int i = alignment_before_call;
+        (i & frame_alignment_mask) != 0;
+        i += kPointerSize) {
+      __ push(r2);
+    }
+  }
+
+  // TODO(1242173): To let the GC traverse the return address of the exit
+  // frames, we need to know where the return address is. Right now,
+  // we push it on the stack to be able to find it again, but we never
+  // restore from it in case of changes, which makes it impossible to
+  // support moving the C entry code stub. This should be fixed, but currently
+  // this is OK because the CEntryStub gets generated so early in the V8 boot
+  // sequence that it is not moving ever.
+  masm->add(lr, pc, Operand(4));  // Compute return address: (pc + 8) + 4
+  masm->push(lr);
+  masm->Jump(r5);
+
+  // Restore sp back to before aligning the stack.
+  if (alignment_before_call > 0) {
+    __ add(sp, sp, Operand(alignment_before_call));
+  }
+
+  if (always_allocate) {
+    // It's okay to clobber r2 and r3 here. Don't mess with r0 and r1
+    // though (contain the result).
+    __ mov(r2, Operand(scope_depth));
+    __ ldr(r3, MemOperand(r2));
+    __ sub(r3, r3, Operand(1));
+    __ str(r3, MemOperand(r2));
+  }
+
+  // check for failure result
+  Label failure_returned;
+  STATIC_ASSERT(((kFailureTag + 1) & kFailureTagMask) == 0);
+  // Lower 2 bits of r2 are 0 iff r0 has failure tag.
+  __ add(r2, r0, Operand(1));
+  __ tst(r2, Operand(kFailureTagMask));
+  __ b(eq, &failure_returned);
+
+  // Exit C frame and return.
+  // r0:r1: result
+  // sp: stack pointer
+  // fp: frame pointer
+  __ LeaveExitFrame(mode_);
+
+  // check if we should retry or throw exception
+  Label retry;
+  __ bind(&failure_returned);
+  STATIC_ASSERT(Failure::RETRY_AFTER_GC == 0);
+  __ tst(r0, Operand(((1 << kFailureTypeTagSize) - 1) << kFailureTagSize));
+  __ b(eq, &retry);
+
+  // Special handling of out of memory exceptions.
+  Failure* out_of_memory = Failure::OutOfMemoryException();
+  __ cmp(r0, Operand(reinterpret_cast<int32_t>(out_of_memory)));
+  __ b(eq, throw_out_of_memory_exception);
+
+  // Retrieve the pending exception and clear the variable.
+  __ mov(ip, Operand(ExternalReference::the_hole_value_location()));
+  __ ldr(r3, MemOperand(ip));
+  __ mov(ip, Operand(ExternalReference(Top::k_pending_exception_address)));
+  __ ldr(r0, MemOperand(ip));
+  __ str(r3, MemOperand(ip));
+
+  // Special handling of termination exceptions which are uncatchable
+  // by javascript code.
+  __ cmp(r0, Operand(Factory::termination_exception()));
+  __ b(eq, throw_termination_exception);
+
+  // Handle normal exception.
+  __ jmp(throw_normal_exception);
+
+  __ bind(&retry);  // pass last failure (r0) as parameter (r0) when retrying
+}
+
+
+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)
+
+  // Result returned in r0 or r0+r1 by default.
+
+  // NOTE: Invocations of builtins may return failure objects
+  // instead of a proper result. The builtin entry handles
+  // this by performing a garbage collection and retrying the
+  // builtin once.
+
+  // Enter the exit frame that transitions from JavaScript to C++.
+  __ EnterExitFrame(mode_);
+
+  // r4: number of arguments (C callee-saved)
+  // r5: pointer to builtin function (C callee-saved)
+  // r6: pointer to first argument (C callee-saved)
+
+  Label throw_normal_exception;
+  Label throw_termination_exception;
+  Label throw_out_of_memory_exception;
+
+  // Call into the runtime system.
+  GenerateCore(masm,
+               &throw_normal_exception,
+               &throw_termination_exception,
+               &throw_out_of_memory_exception,
+               false,
+               false,
+               -kPointerSize);
+
+  // Do space-specific GC and retry runtime call.
+  GenerateCore(masm,
+               &throw_normal_exception,
+               &throw_termination_exception,
+               &throw_out_of_memory_exception,
+               true,
+               false,
+               0);
+
+  // Do full GC and retry runtime call one final time.
+  Failure* failure = Failure::InternalError();
+  __ mov(r0, Operand(reinterpret_cast<int32_t>(failure)));
+  GenerateCore(masm,
+               &throw_normal_exception,
+               &throw_termination_exception,
+               &throw_out_of_memory_exception,
+               true,
+               true,
+               kPointerSize);
+
+  __ bind(&throw_out_of_memory_exception);
+  GenerateThrowUncatchable(masm, OUT_OF_MEMORY);
+
+  __ bind(&throw_termination_exception);
+  GenerateThrowUncatchable(masm, TERMINATION);
+
+  __ bind(&throw_normal_exception);
+  GenerateThrowTOS(masm);
+}
+
+
+void JSEntryStub::GenerateBody(MacroAssembler* masm, bool is_construct) {
+  // r0: code entry
+  // r1: function
+  // r2: receiver
+  // r3: argc
+  // [sp+0]: argv
+
+  Label invoke, exit;
+
+  // 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());
+
+  // Get address of argv, see stm above.
+  // r0: code entry
+  // r1: function
+  // r2: receiver
+  // r3: argc
+  __ ldr(r4, MemOperand(sp, (kNumCalleeSaved + 1) * kPointerSize));  // 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
+  __ mov(r8, Operand(-1));  // Push a bad frame pointer to fail if it is used.
+  int marker = is_construct ? StackFrame::ENTRY_CONSTRUCT : StackFrame::ENTRY;
+  __ mov(r7, Operand(Smi::FromInt(marker)));
+  __ mov(r6, Operand(Smi::FromInt(marker)));
+  __ mov(r5, Operand(ExternalReference(Top::k_c_entry_fp_address)));
+  __ ldr(r5, MemOperand(r5));
+  __ Push(r8, r7, r6, r5);
+
+  // Setup frame pointer for the frame to be pushed.
+  __ add(fp, sp, Operand(-EntryFrameConstants::kCallerFPOffset));
+
+  // Call a faked try-block that does the invoke.
+  __ bl(&invoke);
+
+  // 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(Top::k_pending_exception_address)));
+  __ str(r0, MemOperand(ip));
+  __ mov(r0, Operand(reinterpret_cast<int32_t>(Failure::Exception())));
+  __ b(&exit);
+
+  // Invoke: Link this frame into the handler chain.
+  __ bind(&invoke);
+  // Must preserve r0-r4, r5-r7 are available.
+  __ PushTryHandler(IN_JS_ENTRY, JS_ENTRY_HANDLER);
+  // 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(ip, Operand(ExternalReference::the_hole_value_location()));
+  __ ldr(r5, MemOperand(ip));
+  __ mov(ip, Operand(ExternalReference(Top::k_pending_exception_address)));
+  __ 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 (is_construct) {
+    ExternalReference construct_entry(Builtins::JSConstructEntryTrampoline);
+    __ mov(ip, Operand(construct_entry));
+  } else {
+    ExternalReference entry(Builtins::JSEntryTrampoline);
+    __ mov(ip, Operand(entry));
+  }
+  __ ldr(ip, MemOperand(ip));  // deref address
+
+  // Branch and link to JSEntryTrampoline.  We don't use the double underscore
+  // macro for the add instruction because we don't want the coverage tool
+  // inserting instructions here after we read the pc.
+  __ mov(lr, Operand(pc));
+  masm->add(pc, ip, Operand(Code::kHeaderSize - kHeapObjectTag));
+
+  // Unlink this frame from the handler chain. When reading the
+  // address of the next handler, there is no need to use the address
+  // displacement since the current stack pointer (sp) points directly
+  // to the stack handler.
+  __ ldr(r3, MemOperand(sp, StackHandlerConstants::kNextOffset));
+  __ mov(ip, Operand(ExternalReference(Top::k_handler_address)));
+  __ str(r3, MemOperand(ip));
+  // No need to restore registers
+  __ add(sp, sp, Operand(StackHandlerConstants::kSize));
+
+
+  __ bind(&exit);  // r0 holds result
+  // Restore the top frame descriptors from the stack.
+  __ pop(r3);
+  __ mov(ip, Operand(ExternalReference(Top::k_c_entry_fp_address)));
+  __ 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
+  __ ldm(ia_w, sp, kCalleeSaved | pc.bit());
+}
+
+
+// This stub performs an instanceof, calling the builtin function if
+// necessary.  Uses r1 for the object, r0 for the function that it may
+// be an instance of (these are fetched from the stack).
+void InstanceofStub::Generate(MacroAssembler* masm) {
+  // Get the object - slow case for smis (we may need to throw an exception
+  // depending on the rhs).
+  Label slow, loop, is_instance, is_not_instance;
+  __ ldr(r0, MemOperand(sp, 1 * kPointerSize));
+  __ BranchOnSmi(r0, &slow);
+
+  // Check that the left hand is a JS object and put map in r3.
+  __ CompareObjectType(r0, r3, r2, FIRST_JS_OBJECT_TYPE);
+  __ b(lt, &slow);
+  __ cmp(r2, Operand(LAST_JS_OBJECT_TYPE));
+  __ b(gt, &slow);
+
+  // Get the prototype of the function (r4 is result, r2 is scratch).
+  __ ldr(r1, MemOperand(sp, 0));
+  // r1 is function, r3 is map.
+
+  // Look up the function and the map in the instanceof cache.
+  Label miss;
+  __ LoadRoot(ip, Heap::kInstanceofCacheFunctionRootIndex);
+  __ cmp(r1, ip);
+  __ b(ne, &miss);
+  __ LoadRoot(ip, Heap::kInstanceofCacheMapRootIndex);
+  __ cmp(r3, ip);
+  __ b(ne, &miss);
+  __ LoadRoot(r0, Heap::kInstanceofCacheAnswerRootIndex);
+  __ pop();
+  __ pop();
+  __ mov(pc, Operand(lr));
+
+  __ bind(&miss);
+  __ TryGetFunctionPrototype(r1, r4, r2, &slow);
+
+  // Check that the function prototype is a JS object.
+  __ BranchOnSmi(r4, &slow);
+  __ CompareObjectType(r4, r5, r5, FIRST_JS_OBJECT_TYPE);
+  __ b(lt, &slow);
+  __ cmp(r5, Operand(LAST_JS_OBJECT_TYPE));
+  __ b(gt, &slow);
+
+  __ StoreRoot(r1, Heap::kInstanceofCacheFunctionRootIndex);
+  __ StoreRoot(r3, Heap::kInstanceofCacheMapRootIndex);
+
+  // Register mapping: r3 is object map and r4 is function prototype.
+  // Get prototype of object into r2.
+  __ ldr(r2, FieldMemOperand(r3, Map::kPrototypeOffset));
+
+  // Loop through the prototype chain looking for the function prototype.
+  __ bind(&loop);
+  __ cmp(r2, Operand(r4));
+  __ b(eq, &is_instance);
+  __ LoadRoot(ip, Heap::kNullValueRootIndex);
+  __ cmp(r2, ip);
+  __ b(eq, &is_not_instance);
+  __ ldr(r2, FieldMemOperand(r2, HeapObject::kMapOffset));
+  __ ldr(r2, FieldMemOperand(r2, Map::kPrototypeOffset));
+  __ jmp(&loop);
+
+  __ bind(&is_instance);
+  __ mov(r0, Operand(Smi::FromInt(0)));
+  __ StoreRoot(r0, Heap::kInstanceofCacheAnswerRootIndex);
+  __ pop();
+  __ pop();
+  __ mov(pc, Operand(lr));  // Return.
+
+  __ bind(&is_not_instance);
+  __ mov(r0, Operand(Smi::FromInt(1)));
+  __ StoreRoot(r0, Heap::kInstanceofCacheAnswerRootIndex);
+  __ pop();
+  __ pop();
+  __ mov(pc, Operand(lr));  // Return.
+
+  // Slow-case.  Tail call builtin.
+  __ bind(&slow);
+  __ InvokeBuiltin(Builtins::INSTANCE_OF, JUMP_JS);
+}
+
+
+void ArgumentsAccessStub::GenerateReadElement(MacroAssembler* masm) {
+  // The displacement is the offset of the last parameter (if any)
+  // relative to the frame pointer.
+  static const int kDisplacement =
+      StandardFrameConstants::kCallerSPOffset - kPointerSize;
+
+  // Check that the key is a smi.
+  Label slow;
+  __ BranchOnNotSmi(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(cs, &slow);
+
+  // Read the argument from the stack and return it.
+  __ sub(r3, r0, r1);
+  __ add(r3, fp, Operand(r3, LSL, kPointerSizeLog2 - kSmiTagSize));
+  __ 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(r3, LSL, kPointerSizeLog2 - kSmiTagSize));
+  __ 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::GenerateNewObject(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(r1, LSL, kPointerSizeLog2 - kSmiTagSize));
+  __ 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);
+  __ cmp(r1, Operand(0));
+  __ b(eq, &add_arguments_object);
+  __ mov(r1, Operand(r1, LSR, kSmiTagSize));
+  __ add(r1, r1, Operand(FixedArray::kHeaderSize / kPointerSize));
+  __ bind(&add_arguments_object);
+  __ add(r1, r1, Operand(Heap::kArgumentsObjectSize / kPointerSize));
+
+  // Do the allocation of both objects in one go.
+  __ AllocateInNewSpace(
+      r1,
+      r0,
+      r2,
+      r3,
+      &runtime,
+      static_cast<AllocationFlags>(TAG_OBJECT | SIZE_IN_WORDS));
+
+  // Get the arguments boilerplate from the current (global) context.
+  int offset = Context::SlotOffset(Context::ARGUMENTS_BOILERPLATE_INDEX);
+  __ ldr(r4, MemOperand(cp, Context::SlotOffset(Context::GLOBAL_INDEX)));
+  __ ldr(r4, FieldMemOperand(r4, GlobalObject::kGlobalContextOffset));
+  __ ldr(r4, MemOperand(r4, offset));
+
+  // Copy the JS object part.
+  __ CopyFields(r0, r4, r3.bit(), JSObject::kHeaderSize / kPointerSize);
+
+  // Setup the callee in-object property.
+  STATIC_ASSERT(Heap::arguments_callee_index == 0);
+  __ ldr(r3, MemOperand(sp, 2 * kPointerSize));
+  __ str(r3, FieldMemOperand(r0, JSObject::kHeaderSize));
+
+  // Get the length (smi tagged) and set that as an in-object property too.
+  STATIC_ASSERT(Heap::arguments_length_index == 1);
+  __ ldr(r1, MemOperand(sp, 0 * kPointerSize));
+  __ str(r1, FieldMemOperand(r0, JSObject::kHeaderSize + kPointerSize));
+
+  // If there are no actual arguments, we're done.
+  Label done;
+  __ cmp(r1, Operand(0));
+  __ b(eq, &done);
+
+  // Get the parameters pointer from the stack.
+  __ ldr(r2, MemOperand(sp, 1 * kPointerSize));
+
+  // Setup the elements pointer in the allocated arguments object and
+  // initialize the header in the elements fixed array.
+  __ add(r4, r0, Operand(Heap::kArgumentsObjectSize));
+  __ str(r4, FieldMemOperand(r0, JSObject::kElementsOffset));
+  __ LoadRoot(r3, Heap::kFixedArrayMapRootIndex);
+  __ str(r3, FieldMemOperand(r4, FixedArray::kMapOffset));
+  __ str(r1, FieldMemOperand(r4, FixedArray::kLengthOffset));
+  __ mov(r1, Operand(r1, LSR, kSmiTagSize));  // Untag the length for the loop.
+
+  // Copy the fixed array slots.
+  Label loop;
+  // Setup 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(0));
+  __ 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::kNewArgumentsFast, 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::kRegExpExec, 4, 1);
+#else  // V8_INTERPRETED_REGEXP
+  if (!FLAG_regexp_entry_native) {
+    __ TailCallRuntime(Runtime::kRegExpExec, 4, 1);
+    return;
+  }
+
+  // Stack frame on entry.
+  //  sp[0]: last_match_info (expected JSArray)
+  //  sp[4]: previous index
+  //  sp[8]: subject string
+  //  sp[12]: JSRegExp object
+
+  static const int kLastMatchInfoOffset = 0 * kPointerSize;
+  static const int kPreviousIndexOffset = 1 * kPointerSize;
+  static const int kSubjectOffset = 2 * kPointerSize;
+  static const int kJSRegExpOffset = 3 * kPointerSize;
+
+  Label runtime, invoke_regexp;
+
+  // 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 = r6;
+
+  // Ensure that a RegExp stack is allocated.
+  ExternalReference address_of_regexp_stack_memory_address =
+      ExternalReference::address_of_regexp_stack_memory_address();
+  ExternalReference address_of_regexp_stack_memory_size =
+      ExternalReference::address_of_regexp_stack_memory_size();
+  __ mov(r0, Operand(address_of_regexp_stack_memory_size));
+  __ ldr(r0, MemOperand(r0, 0));
+  __ tst(r0, Operand(r0));
+  __ b(eq, &runtime);
+
+  // Check that the first argument is a JSRegExp object.
+  __ ldr(r0, MemOperand(sp, kJSRegExpOffset));
+  STATIC_ASSERT(kSmiTag == 0);
+  __ tst(r0, Operand(kSmiTagMask));
+  __ b(eq, &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) {
+    __ tst(regexp_data, Operand(kSmiTagMask));
+    __ Check(nz, "Unexpected type for RegExp data, FixedArray expected");
+    __ CompareObjectType(regexp_data, r0, r0, FIXED_ARRAY_TYPE);
+    __ Check(eq, "Unexpected type for RegExp data, FixedArray expected");
+  }
+
+  // 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));
+  // Calculate number of capture registers (number_of_captures + 1) * 2. This
+  // uses the asumption that smis are 2 * their untagged value.
+  STATIC_ASSERT(kSmiTag == 0);
+  STATIC_ASSERT(kSmiTagSize + kSmiShiftSize == 1);
+  __ add(r2, r2, Operand(2));  // r2 was a smi.
+  // Check that the static offsets vector buffer is large enough.
+  __ cmp(r2, Operand(OffsetsVector::kStaticOffsetsVectorSize));
+  __ b(hi, &runtime);
+
+  // r2: Number of capture registers
+  // regexp_data: RegExp data (FixedArray)
+  // Check that the second argument is a string.
+  __ ldr(subject, MemOperand(sp, kSubjectOffset));
+  __ tst(subject, Operand(kSmiTagMask));
+  __ b(eq, &runtime);
+  Condition is_string = masm->IsObjectStringType(subject, r0);
+  __ b(NegateCondition(is_string), &runtime);
+  // Get the length of the string to r3.
+  __ ldr(r3, FieldMemOperand(subject, String::kLengthOffset));
+
+  // r2: Number of capture registers
+  // r3: Length of subject string as a smi
+  // subject: Subject string
+  // regexp_data: RegExp data (FixedArray)
+  // Check that the third argument is a positive smi less than the subject
+  // string length. A negative value will be greater (unsigned comparison).
+  __ ldr(r0, MemOperand(sp, kPreviousIndexOffset));
+  __ tst(r0, Operand(kSmiTagMask));
+  __ b(ne, &runtime);
+  __ cmp(r3, Operand(r0));
+  __ b(ls, &runtime);
+
+  // r2: Number of capture registers
+  // subject: Subject string
+  // regexp_data: RegExp data (FixedArray)
+  // Check that the fourth object is a JSArray object.
+  __ ldr(r0, MemOperand(sp, kLastMatchInfoOffset));
+  __ tst(r0, Operand(kSmiTagMask));
+  __ b(eq, &runtime);
+  __ CompareObjectType(r0, r1, r1, 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));
+  __ LoadRoot(ip, Heap::kFixedArrayMapRootIndex);
+  __ cmp(r0, ip);
+  __ 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, r2, Operand(RegExpImpl::kLastMatchOverhead));
+  __ cmp(r2, Operand(r0, ASR, kSmiTagSize));
+  __ b(gt, &runtime);
+
+  // subject: Subject string
+  // regexp_data: RegExp data (FixedArray)
+  // Check the representation and encoding of the subject string.
+  Label seq_string;
+  __ ldr(r0, FieldMemOperand(subject, HeapObject::kMapOffset));
+  __ ldrb(r0, FieldMemOperand(r0, Map::kInstanceTypeOffset));
+  // First check for flat string.
+  __ tst(r0, Operand(kIsNotStringMask | kStringRepresentationMask));
+  STATIC_ASSERT((kStringTag | kSeqStringTag) == 0);
+  __ b(eq, &seq_string);
+
+  // subject: Subject string
+  // regexp_data: RegExp data (FixedArray)
+  // Check for flat cons string.
+  // A flat cons string is a cons string where the second part is the empty
+  // string. In that case the subject string is just the first part of the cons
+  // string. Also in this case the first part of the cons string is known to be
+  // a sequential string or an external string.
+  STATIC_ASSERT(kExternalStringTag !=0);
+  STATIC_ASSERT((kConsStringTag & kExternalStringTag) == 0);
+  __ tst(r0, Operand(kIsNotStringMask | kExternalStringTag));
+  __ b(ne, &runtime);
+  __ ldr(r0, FieldMemOperand(subject, ConsString::kSecondOffset));
+  __ LoadRoot(r1, Heap::kEmptyStringRootIndex);
+  __ cmp(r0, r1);
+  __ b(ne, &runtime);
+  __ ldr(subject, FieldMemOperand(subject, ConsString::kFirstOffset));
+  __ ldr(r0, FieldMemOperand(subject, HeapObject::kMapOffset));
+  __ ldrb(r0, FieldMemOperand(r0, Map::kInstanceTypeOffset));
+  // Is first part a flat string?
+  STATIC_ASSERT(kSeqStringTag == 0);
+  __ tst(r0, Operand(kStringRepresentationMask));
+  __ b(nz, &runtime);
+
+  __ bind(&seq_string);
+  // subject: Subject string
+  // regexp_data: RegExp data (FixedArray)
+  // r0: Instance type of subject string
+  STATIC_ASSERT(4 == kAsciiStringTag);
+  STATIC_ASSERT(kTwoByteStringTag == 0);
+  // Find the code object based on the assumptions above.
+  __ and_(r0, r0, Operand(kStringEncodingMask));
+  __ mov(r3, Operand(r0, ASR, 2), SetCC);
+  __ ldr(r7, FieldMemOperand(regexp_data, JSRegExp::kDataAsciiCodeOffset), ne);
+  __ ldr(r7, FieldMemOperand(regexp_data, JSRegExp::kDataUC16CodeOffset), eq);
+
+  // 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
+  // the hole.
+  __ CompareObjectType(r7, r0, r0, CODE_TYPE);
+  __ b(ne, &runtime);
+
+  // r3: encoding of subject string (1 if ascii, 0 if two_byte);
+  // r7: code
+  // subject: Subject string
+  // regexp_data: RegExp data (FixedArray)
+  // Load used arguments before starting to push arguments for call to native
+  // RegExp code to avoid handling changing stack height.
+  __ ldr(r1, MemOperand(sp, kPreviousIndexOffset));
+  __ mov(r1, Operand(r1, ASR, kSmiTagSize));
+
+  // r1: previous index
+  // r3: encoding of subject string (1 if ascii, 0 if two_byte);
+  // r7: code
+  // subject: Subject string
+  // regexp_data: RegExp data (FixedArray)
+  // All checks done. Now push arguments for native regexp code.
+  __ IncrementCounter(&Counters::regexp_entry_native, 1, r0, r2);
+
+  static const int kRegExpExecuteArguments = 7;
+  __ push(lr);
+  __ PrepareCallCFunction(kRegExpExecuteArguments, r0);
+
+  // Argument 7 (sp[8]): Indicate that this is a direct call from JavaScript.
+  __ mov(r0, Operand(1));
+  __ str(r0, MemOperand(sp, 2 * kPointerSize));
+
+  // Argument 6 (sp[4]): 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, 1 * kPointerSize));
+
+  // Argument 5 (sp[0]): static offsets vector buffer.
+  __ mov(r0, Operand(ExternalReference::address_of_static_offsets_vector()));
+  __ str(r0, MemOperand(sp, 0 * kPointerSize));
+
+  // For arguments 4 and 3 get string length, calculate start of string data and
+  // calculate the shift of the index (0 for ASCII and 1 for two byte).
+  __ ldr(r0, FieldMemOperand(subject, String::kLengthOffset));
+  __ mov(r0, Operand(r0, ASR, kSmiTagSize));
+  STATIC_ASSERT(SeqAsciiString::kHeaderSize == SeqTwoByteString::kHeaderSize);
+  __ add(r9, subject, Operand(SeqAsciiString::kHeaderSize - kHeapObjectTag));
+  __ eor(r3, r3, Operand(1));
+  // Argument 4 (r3): End of string data
+  // Argument 3 (r2): Start of string data
+  __ add(r2, r9, Operand(r1, LSL, r3));
+  __ add(r3, r9, Operand(r0, 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(r7, r7, Operand(Code::kHeaderSize - kHeapObjectTag));
+  __ CallCFunction(r7, kRegExpExecuteArguments);
+  __ pop(lr);
+
+  // 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(NativeRegExpMacroAssembler::SUCCESS));
+  __ 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(r0, Operand(ExternalReference::the_hole_value_location()));
+  __ ldr(r0, MemOperand(r0, 0));
+  __ mov(r1, Operand(ExternalReference(Top::k_pending_exception_address)));
+  __ ldr(r1, MemOperand(r1, 0));
+  __ cmp(r0, r1);
+  __ b(eq, &runtime);
+  __ bind(&failure);
+  // For failure and exception return null.
+  __ mov(r0, Operand(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.
+  STATIC_ASSERT(kSmiTag == 0);
+  STATIC_ASSERT(kSmiTagSize + kSmiShiftSize == 1);
+  __ add(r1, r1, Operand(2));  // r1 was a smi.
+
+  // r1: number of capture registers
+  // r4: subject string
+  // Store the capture count.
+  __ mov(r2, Operand(r1, LSL, kSmiTagSize + kSmiShiftSize));  // To smi.
+  __ str(r2, FieldMemOperand(last_match_info_elements,
+                             RegExpImpl::kLastCaptureCountOffset));
+  // Store last subject and last input.
+  __ mov(r3, last_match_info_elements);  // Moved up to reduce latency.
+  __ str(subject,
+         FieldMemOperand(last_match_info_elements,
+                         RegExpImpl::kLastSubjectOffset));
+  __ RecordWrite(r3, Operand(RegExpImpl::kLastSubjectOffset), r2, r7);
+  __ str(subject,
+         FieldMemOperand(last_match_info_elements,
+                         RegExpImpl::kLastInputOffset));
+  __ mov(r3, last_match_info_elements);
+  __ RecordWrite(r3, Operand(RegExpImpl::kLastInputOffset), r2, r7);
+
+  // Get the static offsets vector filled by the native regexp code.
+  ExternalReference address_of_static_offsets_vector =
+      ExternalReference::address_of_static_offsets_vector();
+  __ 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.
+  __ mov(r3, Operand(r3, LSL, kSmiTagSize));
+  __ 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::kRegExpExec, 4, 1);
+#endif  // V8_INTERPRETED_REGEXP
+}
+
+
+void CallFunctionStub::Generate(MacroAssembler* masm) {
+  Label slow;
+
+  // If the receiver might be a value (string, number or boolean) check for this
+  // and box it if it is.
+  if (ReceiverMightBeValue()) {
+    // Get the receiver from the stack.
+    // function, receiver [, arguments]
+    Label receiver_is_value, receiver_is_js_object;
+    __ ldr(r1, MemOperand(sp, argc_ * kPointerSize));
+
+    // Check if receiver is a smi (which is a number value).
+    __ BranchOnSmi(r1, &receiver_is_value);
+
+    // Check if the receiver is a valid JS object.
+    __ CompareObjectType(r1, r2, r2, FIRST_JS_OBJECT_TYPE);
+    __ b(ge, &receiver_is_js_object);
+
+    // Call the runtime to box the value.
+    __ bind(&receiver_is_value);
+    __ EnterInternalFrame();
+    __ push(r1);
+    __ InvokeBuiltin(Builtins::TO_OBJECT, CALL_JS);
+    __ LeaveInternalFrame();
+    __ str(r0, MemOperand(sp, argc_ * kPointerSize));
+
+    __ bind(&receiver_is_js_object);
+  }
+
+  // Get the function to call from the stack.
+  // function, receiver [, arguments]
+  __ ldr(r1, MemOperand(sp, (argc_ + 1) * kPointerSize));
+
+  // Check that the function is really a JavaScript function.
+  // r1: pushed function (to be verified)
+  __ BranchOnSmi(r1, &slow);
+  // Get the map of the function object.
+  __ CompareObjectType(r1, r2, r2, JS_FUNCTION_TYPE);
+  __ b(ne, &slow);
+
+  // Fast-case: Invoke the function now.
+  // r1: pushed function
+  ParameterCount actual(argc_);
+  __ InvokeFunction(r1, actual, JUMP_FUNCTION);
+
+  // Slow-case: Non-function called.
+  __ bind(&slow);
+  // CALL_NON_FUNCTION expects the non-function callee as receiver (instead
+  // of the original receiver from the call site).
+  __ str(r1, MemOperand(sp, argc_ * kPointerSize));
+  __ mov(r0, Operand(argc_));  // Setup the number of arguments.
+  __ mov(r2, Operand(0));
+  __ GetBuiltinEntry(r3, Builtins::CALL_NON_FUNCTION);
+  __ Jump(Handle<Code>(Builtins::builtin(Builtins::ArgumentsAdaptorTrampoline)),
+          RelocInfo::CODE_TARGET);
+}
+
+
+// Unfortunately you have to run without snapshots to see most of these
+// names in the profile since most compare stubs end up in the snapshot.
+const char* CompareStub::GetName() {
+  ASSERT((lhs_.is(r0) && rhs_.is(r1)) ||
+         (lhs_.is(r1) && rhs_.is(r0)));
+
+  if (name_ != NULL) return name_;
+  const int kMaxNameLength = 100;
+  name_ = Bootstrapper::AllocateAutoDeletedArray(kMaxNameLength);
+  if (name_ == NULL) return "OOM";
+
+  const char* cc_name;
+  switch (cc_) {
+    case lt: cc_name = "LT"; break;
+    case gt: cc_name = "GT"; break;
+    case le: cc_name = "LE"; break;
+    case ge: cc_name = "GE"; break;
+    case eq: cc_name = "EQ"; break;
+    case ne: cc_name = "NE"; break;
+    default: cc_name = "UnknownCondition"; break;
+  }
+
+  const char* lhs_name = lhs_.is(r0) ? "_r0" : "_r1";
+  const char* rhs_name = rhs_.is(r0) ? "_r0" : "_r1";
+
+  const char* strict_name = "";
+  if (strict_ && (cc_ == eq || cc_ == ne)) {
+    strict_name = "_STRICT";
+  }
+
+  const char* never_nan_nan_name = "";
+  if (never_nan_nan_ && (cc_ == eq || cc_ == ne)) {
+    never_nan_nan_name = "_NO_NAN";
+  }
+
+  const char* include_number_compare_name = "";
+  if (!include_number_compare_) {
+    include_number_compare_name = "_NO_NUMBER";
+  }
+
+  OS::SNPrintF(Vector<char>(name_, kMaxNameLength),
+               "CompareStub_%s%s%s%s%s%s",
+               cc_name,
+               lhs_name,
+               rhs_name,
+               strict_name,
+               never_nan_nan_name,
+               include_number_compare_name);
+  return name_;
+}
+
+
+int CompareStub::MinorKey() {
+  // Encode the three parameters in a unique 16 bit value. To avoid duplicate
+  // stubs the never NaN NaN condition is only taken into account if the
+  // condition is equals.
+  ASSERT((static_cast<unsigned>(cc_) >> 28) < (1 << 12));
+  ASSERT((lhs_.is(r0) && rhs_.is(r1)) ||
+         (lhs_.is(r1) && rhs_.is(r0)));
+  return ConditionField::encode(static_cast<unsigned>(cc_) >> 28)
+         | RegisterField::encode(lhs_.is(r0))
+         | StrictField::encode(strict_)
+         | NeverNanNanField::encode(cc_ == eq ? never_nan_nan_ : false)
+         | IncludeNumberCompareField::encode(include_number_compare_);
+}
+
+
+// StringCharCodeAtGenerator
+
+void StringCharCodeAtGenerator::GenerateFast(MacroAssembler* masm) {
+  Label flat_string;
+  Label ascii_string;
+  Label got_char_code;
+
+  // If the receiver is a smi trigger the non-string case.
+  __ BranchOnSmi(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.
+  __ BranchOnNotSmi(index_, &index_not_smi_);
+
+  // Put smi-tagged index into scratch register.
+  __ mov(scratch_, index_);
+  __ bind(&got_smi_index_);
+
+  // Check for index out of range.
+  __ ldr(ip, FieldMemOperand(object_, String::kLengthOffset));
+  __ cmp(ip, Operand(scratch_));
+  __ b(ls, index_out_of_range_);
+
+  // We need special handling for non-flat strings.
+  STATIC_ASSERT(kSeqStringTag == 0);
+  __ tst(result_, Operand(kStringRepresentationMask));
+  __ b(eq, &flat_string);
+
+  // Handle non-flat strings.
+  __ tst(result_, Operand(kIsConsStringMask));
+  __ b(eq, &call_runtime_);
+
+  // ConsString.
+  // Check whether the right hand side is the empty string (i.e. if
+  // this is really a flat string in a cons string). If that is not
+  // the case we would rather go to the runtime system now to flatten
+  // the string.
+  __ ldr(result_, FieldMemOperand(object_, ConsString::kSecondOffset));
+  __ LoadRoot(ip, Heap::kEmptyStringRootIndex);
+  __ cmp(result_, Operand(ip));
+  __ b(ne, &call_runtime_);
+  // Get the first of the two strings and load its instance type.
+  __ ldr(object_, FieldMemOperand(object_, ConsString::kFirstOffset));
+  __ ldr(result_, FieldMemOperand(object_, HeapObject::kMapOffset));
+  __ ldrb(result_, FieldMemOperand(result_, Map::kInstanceTypeOffset));
+  // If the first cons component is also non-flat, then go to runtime.
+  STATIC_ASSERT(kSeqStringTag == 0);
+  __ tst(result_, Operand(kStringRepresentationMask));
+  __ b(nz, &call_runtime_);
+
+  // Check for 1-byte or 2-byte string.
+  __ bind(&flat_string);
+  STATIC_ASSERT(kAsciiStringTag != 0);
+  __ tst(result_, Operand(kStringEncodingMask));
+  __ b(nz, &ascii_string);
+
+  // 2-byte string.
+  // Load the 2-byte character code into the result register. We can
+  // add without shifting since the smi tag size is the log2 of the
+  // number of bytes in a two-byte character.
+  STATIC_ASSERT(kSmiTag == 0 && kSmiTagSize == 1 && kSmiShiftSize == 0);
+  __ add(scratch_, object_, Operand(scratch_));
+  __ ldrh(result_, FieldMemOperand(scratch_, SeqTwoByteString::kHeaderSize));
+  __ jmp(&got_char_code);
+
+  // ASCII string.
+  // Load the byte into the result register.
+  __ bind(&ascii_string);
+  __ add(scratch_, object_, Operand(scratch_, LSR, kSmiTagSize));
+  __ ldrb(result_, FieldMemOperand(scratch_, SeqAsciiString::kHeaderSize));
+
+  __ bind(&got_char_code);
+  __ mov(result_, Operand(result_, LSL, kSmiTagSize));
+  __ bind(&exit_);
+}
+
+
+void StringCharCodeAtGenerator::GenerateSlow(
+    MacroAssembler* masm, const RuntimeCallHelper& call_helper) {
+  __ Abort("Unexpected fallthrough to CharCodeAt slow case");
+
+  // Index is not a smi.
+  __ bind(&index_not_smi_);
+  // If index is a heap number, try converting it to an integer.
+  __ CheckMap(index_,
+              scratch_,
+              Heap::kHeapNumberMapRootIndex,
+              index_not_number_,
+              true);
+  call_helper.BeforeCall(masm);
+  __ Push(object_, index_);
+  __ push(index_);  // Consumed by runtime conversion function.
+  if (index_flags_ == STRING_INDEX_IS_NUMBER) {
+    __ CallRuntime(Runtime::kNumberToIntegerMapMinusZero, 1);
+  } else {
+    ASSERT(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(scratch_, r0);
+  __ pop(index_);
+  __ 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.
+  __ BranchOnNotSmi(scratch_, 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);
+  __ Push(object_, index_);
+  __ CallRuntime(Runtime::kStringCharCodeAt, 2);
+  __ Move(result_, r0);
+  call_helper.AfterCall(masm);
+  __ jmp(&exit_);
+
+  __ Abort("Unexpected fallthrough from CharCodeAt slow case");
+}
+
+
+// -------------------------------------------------------------------------
+// StringCharFromCodeGenerator
+
+void StringCharFromCodeGenerator::GenerateFast(MacroAssembler* masm) {
+  // Fast case of Heap::LookupSingleCharacterStringFromCode.
+  STATIC_ASSERT(kSmiTag == 0);
+  STATIC_ASSERT(kSmiShiftSize == 0);
+  ASSERT(IsPowerOf2(String::kMaxAsciiCharCode + 1));
+  __ tst(code_,
+         Operand(kSmiTagMask |
+                 ((~String::kMaxAsciiCharCode) << kSmiTagSize)));
+  __ b(nz, &slow_case_);
+
+  __ LoadRoot(result_, Heap::kSingleCharacterStringCacheRootIndex);
+  // At this point code register contains smi tagged ascii char code.
+  STATIC_ASSERT(kSmiTag == 0);
+  __ add(result_, result_, Operand(code_, LSL, kPointerSizeLog2 - kSmiTagSize));
+  __ ldr(result_, FieldMemOperand(result_, FixedArray::kHeaderSize));
+  __ LoadRoot(ip, Heap::kUndefinedValueRootIndex);
+  __ cmp(result_, Operand(ip));
+  __ b(eq, &slow_case_);
+  __ bind(&exit_);
+}
+
+
+void StringCharFromCodeGenerator::GenerateSlow(
+    MacroAssembler* masm, const RuntimeCallHelper& call_helper) {
+  __ Abort("Unexpected fallthrough to CharFromCode slow case");
+
+  __ bind(&slow_case_);
+  call_helper.BeforeCall(masm);
+  __ push(code_);
+  __ CallRuntime(Runtime::kCharFromCode, 1);
+  __ Move(result_, r0);
+  call_helper.AfterCall(masm);
+  __ jmp(&exit_);
+
+  __ Abort("Unexpected fallthrough from CharFromCode slow case");
+}
+
+
+// -------------------------------------------------------------------------
+// StringCharAtGenerator
+
+void StringCharAtGenerator::GenerateFast(MacroAssembler* masm) {
+  char_code_at_generator_.GenerateFast(masm);
+  char_from_code_generator_.GenerateFast(masm);
+}
+
+
+void StringCharAtGenerator::GenerateSlow(
+    MacroAssembler* masm, const RuntimeCallHelper& call_helper) {
+  char_code_at_generator_.GenerateSlow(masm, call_helper);
+  char_from_code_generator_.GenerateSlow(masm, call_helper);
+}
+
+
+class StringHelper : public AllStatic {
+ public:
+  // Generate code for copying characters using a simple loop. This should only
+  // be used in places where the number of characters is small and the
+  // additional setup and checking in GenerateCopyCharactersLong adds too much
+  // overhead. Copying of overlapping regions is not supported.
+  // Dest register ends at the position after the last character written.
+  static void GenerateCopyCharacters(MacroAssembler* masm,
+                                     Register dest,
+                                     Register src,
+                                     Register count,
+                                     Register scratch,
+                                     bool ascii);
+
+  // Generate code for copying a large number of characters. This function
+  // is allowed to spend extra time setting up conditions to make copying
+  // faster. Copying of overlapping regions is not supported.
+  // Dest register ends at the position after the last character written.
+  static void GenerateCopyCharactersLong(MacroAssembler* masm,
+                                         Register dest,
+                                         Register src,
+                                         Register count,
+                                         Register scratch1,
+                                         Register scratch2,
+                                         Register scratch3,
+                                         Register scratch4,
+                                         Register scratch5,
+                                         int flags);
+
+
+  // Probe the symbol table for a two character string. If the string is
+  // not found by probing a jump to the label not_found is performed. This jump
+  // does not guarantee that the string is not in the symbol table. If the
+  // string is found the code falls through with the string in register r0.
+  // Contents of both c1 and c2 registers are modified. At the exit c1 is
+  // guaranteed to contain halfword with low and high bytes equal to
+  // initial contents of c1 and c2 respectively.
+  static void GenerateTwoCharacterSymbolTableProbe(MacroAssembler* masm,
+                                                   Register c1,
+                                                   Register c2,
+                                                   Register scratch1,
+                                                   Register scratch2,
+                                                   Register scratch3,
+                                                   Register scratch4,
+                                                   Register scratch5,
+                                                   Label* not_found);
+
+  // Generate string hash.
+  static void GenerateHashInit(MacroAssembler* masm,
+                               Register hash,
+                               Register character);
+
+  static void GenerateHashAddCharacter(MacroAssembler* masm,
+                                       Register hash,
+                                       Register character);
+
+  static void GenerateHashGetHash(MacroAssembler* masm,
+                                  Register hash);
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(StringHelper);
+};
+
+
+void StringHelper::GenerateCopyCharacters(MacroAssembler* masm,
+                                          Register dest,
+                                          Register src,
+                                          Register count,
+                                          Register scratch,
+                                          bool ascii) {
+  Label loop;
+  Label done;
+  // This loop just copies one character at a time, as it is only used for very
+  // short strings.
+  if (!ascii) {
+    __ add(count, count, Operand(count), SetCC);
+  } else {
+    __ cmp(count, Operand(0));
+  }
+  __ b(eq, &done);
+
+  __ bind(&loop);
+  __ ldrb(scratch, MemOperand(src, 1, PostIndex));
+  // Perform sub between load and dependent store to get the load time to
+  // complete.
+  __ sub(count, count, Operand(1), SetCC);
+  __ strb(scratch, MemOperand(dest, 1, PostIndex));
+  // last iteration.
+  __ b(gt, &loop);
+
+  __ bind(&done);
+}
+
+
+enum CopyCharactersFlags {
+  COPY_ASCII = 1,
+  DEST_ALWAYS_ALIGNED = 2
+};
+
+
+void StringHelper::GenerateCopyCharactersLong(MacroAssembler* masm,
+                                              Register dest,
+                                              Register src,
+                                              Register count,
+                                              Register scratch1,
+                                              Register scratch2,
+                                              Register scratch3,
+                                              Register scratch4,
+                                              Register scratch5,
+                                              int flags) {
+  bool ascii = (flags & COPY_ASCII) != 0;
+  bool dest_always_aligned = (flags & DEST_ALWAYS_ALIGNED) != 0;
+
+  if (dest_always_aligned && FLAG_debug_code) {
+    // Check that destination is actually word aligned if the flag says
+    // that it is.
+    __ tst(dest, Operand(kPointerAlignmentMask));
+    __ Check(eq, "Destination of copy not aligned.");
+  }
+
+  const int kReadAlignment = 4;
+  const int kReadAlignmentMask = kReadAlignment - 1;
+  // Ensure that reading an entire aligned word containing the last character
+  // of a string will not read outside the allocated area (because we pad up
+  // to kObjectAlignment).
+  STATIC_ASSERT(kObjectAlignment >= kReadAlignment);
+  // Assumes word reads and writes are little endian.
+  // Nothing to do for zero characters.
+  Label done;
+  if (!ascii) {
+    __ add(count, count, Operand(count), SetCC);
+  } else {
+    __ cmp(count, Operand(0));
+  }
+  __ b(eq, &done);
+
+  // Assume that you cannot read (or write) unaligned.
+  Label byte_loop;
+  // Must copy at least eight bytes, otherwise just do it one byte at a time.
+  __ cmp(count, Operand(8));
+  __ add(count, dest, Operand(count));
+  Register limit = count;  // Read until src equals this.
+  __ b(lt, &byte_loop);
+
+  if (!dest_always_aligned) {
+    // Align dest by byte copying. Copies between zero and three bytes.
+    __ and_(scratch4, dest, Operand(kReadAlignmentMask), SetCC);
+    Label dest_aligned;
+    __ b(eq, &dest_aligned);
+    __ cmp(scratch4, Operand(2));
+    __ ldrb(scratch1, MemOperand(src, 1, PostIndex));
+    __ ldrb(scratch2, MemOperand(src, 1, PostIndex), le);
+    __ ldrb(scratch3, MemOperand(src, 1, PostIndex), lt);
+    __ strb(scratch1, MemOperand(dest, 1, PostIndex));
+    __ strb(scratch2, MemOperand(dest, 1, PostIndex), le);
+    __ strb(scratch3, MemOperand(dest, 1, PostIndex), lt);
+    __ bind(&dest_aligned);
+  }
+
+  Label simple_loop;
+
+  __ sub(scratch4, dest, Operand(src));
+  __ and_(scratch4, scratch4, Operand(0x03), SetCC);
+  __ b(eq, &simple_loop);
+  // Shift register is number of bits in a source word that
+  // must be combined with bits in the next source word in order
+  // to create a destination word.
+
+  // Complex loop for src/dst that are not aligned the same way.
+  {
+    Label loop;
+    __ mov(scratch4, Operand(scratch4, LSL, 3));
+    Register left_shift = scratch4;
+    __ and_(src, src, Operand(~3));  // Round down to load previous word.
+    __ ldr(scratch1, MemOperand(src, 4, PostIndex));
+    // Store the "shift" most significant bits of scratch in the least
+    // signficant bits (i.e., shift down by (32-shift)).
+    __ rsb(scratch2, left_shift, Operand(32));
+    Register right_shift = scratch2;
+    __ mov(scratch1, Operand(scratch1, LSR, right_shift));
+
+    __ bind(&loop);
+    __ ldr(scratch3, MemOperand(src, 4, PostIndex));
+    __ sub(scratch5, limit, Operand(dest));
+    __ orr(scratch1, scratch1, Operand(scratch3, LSL, left_shift));
+    __ str(scratch1, MemOperand(dest, 4, PostIndex));
+    __ mov(scratch1, Operand(scratch3, LSR, right_shift));
+    // Loop if four or more bytes left to copy.
+    // Compare to eight, because we did the subtract before increasing dst.
+    __ sub(scratch5, scratch5, Operand(8), SetCC);
+    __ b(ge, &loop);
+  }
+  // There is now between zero and three bytes left to copy (negative that
+  // number is in scratch5), and between one and three bytes already read into
+  // scratch1 (eight times that number in scratch4). We may have read past
+  // the end of the string, but because objects are aligned, we have not read
+  // past the end of the object.
+  // Find the minimum of remaining characters to move and preloaded characters
+  // and write those as bytes.
+  __ add(scratch5, scratch5, Operand(4), SetCC);
+  __ b(eq, &done);
+  __ cmp(scratch4, Operand(scratch5, LSL, 3), ne);
+  // Move minimum of bytes read and bytes left to copy to scratch4.
+  __ mov(scratch5, Operand(scratch4, LSR, 3), LeaveCC, lt);
+  // Between one and three (value in scratch5) characters already read into
+  // scratch ready to write.
+  __ cmp(scratch5, Operand(2));
+  __ strb(scratch1, MemOperand(dest, 1, PostIndex));
+  __ mov(scratch1, Operand(scratch1, LSR, 8), LeaveCC, ge);
+  __ strb(scratch1, MemOperand(dest, 1, PostIndex), ge);
+  __ mov(scratch1, Operand(scratch1, LSR, 8), LeaveCC, gt);
+  __ strb(scratch1, MemOperand(dest, 1, PostIndex), gt);
+  // Copy any remaining bytes.
+  __ b(&byte_loop);
+
+  // Simple loop.
+  // Copy words from src to dst, until less than four bytes left.
+  // Both src and dest are word aligned.
+  __ bind(&simple_loop);
+  {
+    Label loop;
+    __ bind(&loop);
+    __ ldr(scratch1, MemOperand(src, 4, PostIndex));
+    __ sub(scratch3, limit, Operand(dest));
+    __ str(scratch1, MemOperand(dest, 4, PostIndex));
+    // Compare to 8, not 4, because we do the substraction before increasing
+    // dest.
+    __ cmp(scratch3, Operand(8));
+    __ b(ge, &loop);
+  }
+
+  // Copy bytes from src to dst until dst hits limit.
+  __ bind(&byte_loop);
+  __ cmp(dest, Operand(limit));
+  __ ldrb(scratch1, MemOperand(src, 1, PostIndex), lt);
+  __ b(ge, &done);
+  __ strb(scratch1, MemOperand(dest, 1, PostIndex));
+  __ b(&byte_loop);
+
+  __ bind(&done);
+}
+
+
+void StringHelper::GenerateTwoCharacterSymbolTableProbe(MacroAssembler* masm,
+                                                        Register c1,
+                                                        Register c2,
+                                                        Register scratch1,
+                                                        Register scratch2,
+                                                        Register scratch3,
+                                                        Register scratch4,
+                                                        Register scratch5,
+                                                        Label* not_found) {
+  // Register scratch3 is the general scratch register in this function.
+  Register scratch = scratch3;
+
+  // Make sure that both characters are not digits as such strings has a
+  // different hash algorithm. Don't try to look for these in the symbol table.
+  Label not_array_index;
+  __ sub(scratch, c1, Operand(static_cast<int>('0')));
+  __ cmp(scratch, Operand(static_cast<int>('9' - '0')));
+  __ b(hi, &not_array_index);
+  __ sub(scratch, c2, Operand(static_cast<int>('0')));
+  __ cmp(scratch, Operand(static_cast<int>('9' - '0')));
+
+  // If check failed combine both characters into single halfword.
+  // This is required by the contract of the method: code at the
+  // not_found branch expects this combination in c1 register
+  __ orr(c1, c1, Operand(c2, LSL, kBitsPerByte), LeaveCC, ls);
+  __ b(ls, not_found);
+
+  __ bind(&not_array_index);
+  // Calculate the two character string hash.
+  Register hash = scratch1;
+  StringHelper::GenerateHashInit(masm, hash, c1);
+  StringHelper::GenerateHashAddCharacter(masm, hash, c2);
+  StringHelper::GenerateHashGetHash(masm, hash);
+
+  // Collect the two characters in a register.
+  Register chars = c1;
+  __ orr(chars, chars, Operand(c2, LSL, kBitsPerByte));
+
+  // chars: two character string, char 1 in byte 0 and char 2 in byte 1.
+  // hash:  hash of two character string.
+
+  // Load symbol table
+  // Load address of first element of the symbol table.
+  Register symbol_table = c2;
+  __ LoadRoot(symbol_table, Heap::kSymbolTableRootIndex);
+
+  // Load undefined value
+  Register undefined = scratch4;
+  __ LoadRoot(undefined, Heap::kUndefinedValueRootIndex);
+
+  // Calculate capacity mask from the symbol table capacity.
+  Register mask = scratch2;
+  __ ldr(mask, FieldMemOperand(symbol_table, SymbolTable::kCapacityOffset));
+  __ mov(mask, Operand(mask, ASR, 1));
+  __ sub(mask, mask, Operand(1));
+
+  // Calculate untagged address of the first element of the symbol table.
+  Register first_symbol_table_element = symbol_table;
+  __ add(first_symbol_table_element, symbol_table,
+         Operand(SymbolTable::kElementsStartOffset - kHeapObjectTag));
+
+  // Registers
+  // chars: two character string, char 1 in byte 0 and char 2 in byte 1.
+  // hash:  hash of two character string
+  // mask:  capacity mask
+  // first_symbol_table_element: address of the first element of
+  //                             the symbol table
+  // scratch: -
+
+  // Perform a number of probes in the symbol table.
+  static const int kProbes = 4;
+  Label found_in_symbol_table;
+  Label next_probe[kProbes];
+  for (int i = 0; i < kProbes; i++) {
+    Register candidate = scratch5;  // Scratch register contains candidate.
+
+    // Calculate entry in symbol table.
+    if (i > 0) {
+      __ add(candidate, hash, Operand(SymbolTable::GetProbeOffset(i)));
+    } else {
+      __ mov(candidate, hash);
+    }
+
+    __ and_(candidate, candidate, Operand(mask));
+
+    // Load the entry from the symble table.
+    STATIC_ASSERT(SymbolTable::kEntrySize == 1);
+    __ ldr(candidate,
+           MemOperand(first_symbol_table_element,
+                      candidate,
+                      LSL,
+                      kPointerSizeLog2));
+
+    // If entry is undefined no string with this hash can be found.
+    __ cmp(candidate, undefined);
+    __ b(eq, not_found);
+
+    // If length is not 2 the string is not a candidate.
+    __ ldr(scratch, FieldMemOperand(candidate, String::kLengthOffset));
+    __ cmp(scratch, Operand(Smi::FromInt(2)));
+    __ b(ne, &next_probe[i]);
+
+    // Check that the candidate is a non-external ascii string.
+    __ ldr(scratch, FieldMemOperand(candidate, HeapObject::kMapOffset));
+    __ ldrb(scratch, FieldMemOperand(scratch, Map::kInstanceTypeOffset));
+    __ JumpIfInstanceTypeIsNotSequentialAscii(scratch, scratch,
+                                              &next_probe[i]);
+
+    // Check if the two characters match.
+    // Assumes that word load is little endian.
+    __ ldrh(scratch, FieldMemOperand(candidate, SeqAsciiString::kHeaderSize));
+    __ cmp(chars, scratch);
+    __ b(eq, &found_in_symbol_table);
+    __ bind(&next_probe[i]);
+  }
+
+  // No matching 2 character string found by probing.
+  __ jmp(not_found);
+
+  // Scratch register contains result when we fall through to here.
+  Register result = scratch;
+  __ bind(&found_in_symbol_table);
+  __ Move(r0, result);
+}
+
+
+void StringHelper::GenerateHashInit(MacroAssembler* masm,
+                                    Register hash,
+                                    Register character) {
+  // hash = character + (character << 10);
+  __ add(hash, character, Operand(character, LSL, 10));
+  // hash ^= hash >> 6;
+  __ eor(hash, hash, Operand(hash, ASR, 6));
+}
+
+
+void StringHelper::GenerateHashAddCharacter(MacroAssembler* masm,
+                                            Register hash,
+                                            Register character) {
+  // hash += character;
+  __ add(hash, hash, Operand(character));
+  // hash += hash << 10;
+  __ add(hash, hash, Operand(hash, LSL, 10));
+  // hash ^= hash >> 6;
+  __ eor(hash, hash, Operand(hash, ASR, 6));
+}
+
+
+void StringHelper::GenerateHashGetHash(MacroAssembler* masm,
+                                       Register hash) {
+  // hash += hash << 3;
+  __ add(hash, hash, Operand(hash, LSL, 3));
+  // hash ^= hash >> 11;
+  __ eor(hash, hash, Operand(hash, ASR, 11));
+  // hash += hash << 15;
+  __ add(hash, hash, Operand(hash, LSL, 15), SetCC);
+
+  // if (hash == 0) hash = 27;
+  __ mov(hash, Operand(27), LeaveCC, nz);
+}
+
+
+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.
+
+  static const int kToOffset = 0 * kPointerSize;
+  static const int kFromOffset = 1 * kPointerSize;
+  static const int kStringOffset = 2 * kPointerSize;
+
+
+  // Check bounds and smi-ness.
+  __ ldr(r7, MemOperand(sp, kToOffset));
+  __ ldr(r6, MemOperand(sp, kFromOffset));
+  STATIC_ASSERT(kSmiTag == 0);
+  STATIC_ASSERT(kSmiTagSize + kSmiShiftSize == 1);
+  // I.e., arithmetic shift right by one un-smi-tags.
+  __ mov(r2, Operand(r7, ASR, 1), SetCC);
+  __ mov(r3, Operand(r6, ASR, 1), SetCC, cc);
+  // If either r2 or r6 had the smi tag bit set, then carry is set now.
+  __ b(cs, &runtime);  // Either "from" or "to" is not a smi.
+  __ b(mi, &runtime);  // From is negative.
+
+  __ sub(r2, r2, Operand(r3), SetCC);
+  __ b(mi, &runtime);  // Fail if from > to.
+  // Special handling of sub-strings of length 1 and 2. One character strings
+  // are handled in the runtime system (looked up in the single character
+  // cache). Two character strings are looked for in the symbol cache.
+  __ cmp(r2, Operand(2));
+  __ b(lt, &runtime);
+
+  // r2: length
+  // r3: from index (untaged smi)
+  // r6: from (smi)
+  // r7: to (smi)
+
+  // Make sure first argument is a sequential (or flat) string.
+  __ ldr(r5, MemOperand(sp, kStringOffset));
+  STATIC_ASSERT(kSmiTag == 0);
+  __ tst(r5, Operand(kSmiTagMask));
+  __ b(eq, &runtime);
+  Condition is_string = masm->IsObjectStringType(r5, r1);
+  __ b(NegateCondition(is_string), &runtime);
+
+  // r1: instance type
+  // r2: length
+  // r3: from index (untaged smi)
+  // r5: string
+  // r6: from (smi)
+  // r7: to (smi)
+  Label seq_string;
+  __ and_(r4, r1, Operand(kStringRepresentationMask));
+  STATIC_ASSERT(kSeqStringTag < kConsStringTag);
+  STATIC_ASSERT(kConsStringTag < kExternalStringTag);
+  __ cmp(r4, Operand(kConsStringTag));
+  __ b(gt, &runtime);  // External strings go to runtime.
+  __ b(lt, &seq_string);  // Sequential strings are handled directly.
+
+  // Cons string. Try to recurse (once) on the first substring.
+  // (This adds a little more generality than necessary to handle flattened
+  // cons strings, but not much).
+  __ ldr(r5, FieldMemOperand(r5, ConsString::kFirstOffset));
+  __ ldr(r4, FieldMemOperand(r5, HeapObject::kMapOffset));
+  __ ldrb(r1, FieldMemOperand(r4, Map::kInstanceTypeOffset));
+  __ tst(r1, Operand(kStringRepresentationMask));
+  STATIC_ASSERT(kSeqStringTag == 0);
+  __ b(ne, &runtime);  // Cons and External strings go to runtime.
+
+  // Definitly a sequential string.
+  __ bind(&seq_string);
+
+  // r1: instance type.
+  // r2: length
+  // r3: from index (untaged smi)
+  // r5: string
+  // r6: from (smi)
+  // r7: to (smi)
+  __ ldr(r4, FieldMemOperand(r5, String::kLengthOffset));
+  __ cmp(r4, Operand(r7));
+  __ b(lt, &runtime);  // Fail if to > length.
+
+  // r1: instance type.
+  // r2: result string length.
+  // r3: from index (untaged smi)
+  // r5: string.
+  // r6: from offset (smi)
+  // Check for flat ascii string.
+  Label non_ascii_flat;
+  __ tst(r1, Operand(kStringEncodingMask));
+  STATIC_ASSERT(kTwoByteStringTag == 0);
+  __ b(eq, &non_ascii_flat);
+
+  Label result_longer_than_two;
+  __ cmp(r2, Operand(2));
+  __ b(gt, &result_longer_than_two);
+
+  // Sub string of length 2 requested.
+  // Get the two characters forming the sub string.
+  __ add(r5, r5, Operand(r3));
+  __ ldrb(r3, FieldMemOperand(r5, SeqAsciiString::kHeaderSize));
+  __ ldrb(r4, FieldMemOperand(r5, SeqAsciiString::kHeaderSize + 1));
+
+  // Try to lookup two character string in symbol table.
+  Label make_two_character_string;
+  StringHelper::GenerateTwoCharacterSymbolTableProbe(
+      masm, r3, r4, r1, r5, r6, r7, r9, &make_two_character_string);
+  __ IncrementCounter(&Counters::sub_string_native, 1, r3, r4);
+  __ add(sp, sp, Operand(3 * kPointerSize));
+  __ Ret();
+
+  // r2: result string length.
+  // r3: two characters combined into halfword in little endian byte order.
+  __ bind(&make_two_character_string);
+  __ AllocateAsciiString(r0, r2, r4, r5, r9, &runtime);
+  __ strh(r3, FieldMemOperand(r0, SeqAsciiString::kHeaderSize));
+  __ IncrementCounter(&Counters::sub_string_native, 1, r3, r4);
+  __ add(sp, sp, Operand(3 * kPointerSize));
+  __ Ret();
+
+  __ bind(&result_longer_than_two);
+
+  // Allocate the result.
+  __ AllocateAsciiString(r0, r2, r3, r4, r1, &runtime);
+
+  // r0: result string.
+  // r2: result string length.
+  // r5: string.
+  // r6: from offset (smi)
+  // Locate first character of result.
+  __ add(r1, r0, Operand(SeqAsciiString::kHeaderSize - kHeapObjectTag));
+  // Locate 'from' character of string.
+  __ add(r5, r5, Operand(SeqAsciiString::kHeaderSize - kHeapObjectTag));
+  __ add(r5, r5, Operand(r6, ASR, 1));
+
+  // r0: result string.
+  // r1: first character of result string.
+  // r2: result string length.
+  // r5: first character of sub string to copy.
+  STATIC_ASSERT((SeqAsciiString::kHeaderSize & kObjectAlignmentMask) == 0);
+  StringHelper::GenerateCopyCharactersLong(masm, r1, r5, r2, r3, r4, r6, r7, r9,
+                                           COPY_ASCII | DEST_ALWAYS_ALIGNED);
+  __ IncrementCounter(&Counters::sub_string_native, 1, r3, r4);
+  __ add(sp, sp, Operand(3 * kPointerSize));
+  __ Ret();
+
+  __ bind(&non_ascii_flat);
+  // r2: result string length.
+  // r5: string.
+  // r6: from offset (smi)
+  // Check for flat two byte string.
+
+  // Allocate the result.
+  __ AllocateTwoByteString(r0, r2, r1, r3, r4, &runtime);
+
+  // r0: result string.
+  // r2: result string length.
+  // r5: string.
+  // Locate first character of result.
+  __ add(r1, r0, Operand(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
+  // Locate 'from' character of string.
+    __ add(r5, r5, Operand(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
+  // As "from" is a smi it is 2 times the value which matches the size of a two
+  // byte character.
+  __ add(r5, r5, Operand(r6));
+
+  // r0: result string.
+  // r1: first character of result.
+  // r2: result length.
+  // r5: first character of string to copy.
+  STATIC_ASSERT((SeqTwoByteString::kHeaderSize & kObjectAlignmentMask) == 0);
+  StringHelper::GenerateCopyCharactersLong(masm, r1, r5, r2, r3, r4, r6, r7, r9,
+                                           DEST_ALWAYS_ALIGNED);
+  __ IncrementCounter(&Counters::sub_string_native, 1, r3, r4);
+  __ add(sp, sp, Operand(3 * kPointerSize));
+  __ Ret();
+
+  // Just jump to runtime to create the sub string.
+  __ bind(&runtime);
+  __ TailCallRuntime(Runtime::kSubString, 3, 1);
+}
+
+
+void StringCompareStub::GenerateCompareFlatAsciiStrings(MacroAssembler* masm,
+                                                        Register left,
+                                                        Register right,
+                                                        Register scratch1,
+                                                        Register scratch2,
+                                                        Register scratch3,
+                                                        Register scratch4) {
+  Label 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);
+  __ tst(min_length, Operand(min_length));
+  __ b(eq, &compare_lengths);
+
+  // Untag smi.
+  __ mov(min_length, Operand(min_length, ASR, kSmiTagSize));
+
+  // Setup registers so that we only need to increment one register
+  // in the loop.
+  __ add(scratch2, min_length,
+         Operand(SeqAsciiString::kHeaderSize - kHeapObjectTag));
+  __ add(left, left, Operand(scratch2));
+  __ add(right, right, Operand(scratch2));
+  // Registers left and right points to the min_length character of strings.
+  __ rsb(min_length, min_length, Operand(-1));
+  Register index = min_length;
+  // Index starts at -min_length.
+
+  {
+    // Compare loop.
+    Label loop;
+    __ bind(&loop);
+    // Compare characters.
+    __ add(index, index, Operand(1), SetCC);
+    __ ldrb(scratch2, MemOperand(left, index), ne);
+    __ ldrb(scratch4, MemOperand(right, index), ne);
+    // Skip to compare lengths with eq condition true.
+    __ b(eq, &compare_lengths);
+    __ cmp(scratch2, scratch4);
+    __ b(eq, &loop);
+    // Fallthrough with eq condition false.
+  }
+  // Compare lengths -  strings up to min-length are equal.
+  __ bind(&compare_lengths);
+  ASSERT(Smi::FromInt(EQUAL) == static_cast<Smi*>(0));
+  // Use zero length_delta as result.
+  __ mov(r0, Operand(length_delta), SetCC, eq);
+  // Fall through to here if characters compare not-equal.
+  __ mov(r0, Operand(Smi::FromInt(GREATER)), LeaveCC, gt);
+  __ mov(r0, Operand(Smi::FromInt(LESS)), LeaveCC, lt);
+  __ Ret();
+}
+
+
+void StringCompareStub::Generate(MacroAssembler* masm) {
+  Label runtime;
+
+  // Stack frame on entry.
+  //  sp[0]: right string
+  //  sp[4]: left string
+  __ ldr(r0, MemOperand(sp, 1 * kPointerSize));  // left
+  __ ldr(r1, MemOperand(sp, 0 * kPointerSize));  // right
+
+  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 ascii strings.
+  __ JumpIfNotBothSequentialAsciiStrings(r0, r1, r2, r3, &runtime);
+
+  // Compare flat ascii strings natively. Remove arguments from stack first.
+  __ IncrementCounter(&Counters::string_compare_native, 1, r2, r3);
+  __ add(sp, sp, Operand(2 * kPointerSize));
+  GenerateCompareFlatAsciiStrings(masm, r0, r1, 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 StringAddStub::Generate(MacroAssembler* masm) {
+  Label string_add_runtime;
+  // Stack on entry:
+  // sp[0]: second argument.
+  // sp[4]: first argument.
+
+  // Load the two arguments.
+  __ ldr(r0, MemOperand(sp, 1 * kPointerSize));  // First argument.
+  __ ldr(r1, MemOperand(sp, 0 * kPointerSize));  // Second argument.
+
+  // Make sure that both arguments are strings if not known in advance.
+  if (string_check_) {
+    STATIC_ASSERT(kSmiTag == 0);
+    __ JumpIfEitherSmi(r0, r1, &string_add_runtime);
+    // Load instance types.
+    __ ldr(r4, FieldMemOperand(r0, HeapObject::kMapOffset));
+    __ ldr(r5, FieldMemOperand(r1, HeapObject::kMapOffset));
+    __ ldrb(r4, FieldMemOperand(r4, Map::kInstanceTypeOffset));
+    __ ldrb(r5, FieldMemOperand(r5, Map::kInstanceTypeOffset));
+    STATIC_ASSERT(kStringTag == 0);
+    // If either is not a string, go to runtime.
+    __ tst(r4, Operand(kIsNotStringMask));
+    __ tst(r5, Operand(kIsNotStringMask), eq);
+    __ b(ne, &string_add_runtime);
+  }
+
+  // Both arguments are strings.
+  // r0: first string
+  // r1: second string
+  // r4: first string instance type (if string_check_)
+  // r5: second string instance type (if string_check_)
+  {
+    Label strings_not_empty;
+    // Check if either of the strings are empty. In that case return the other.
+    __ ldr(r2, FieldMemOperand(r0, String::kLengthOffset));
+    __ ldr(r3, FieldMemOperand(r1, String::kLengthOffset));
+    STATIC_ASSERT(kSmiTag == 0);
+    __ cmp(r2, Operand(Smi::FromInt(0)));  // Test if first string is empty.
+    __ mov(r0, Operand(r1), LeaveCC, eq);  // If first is empty, return second.
+    STATIC_ASSERT(kSmiTag == 0);
+     // Else test if second string is empty.
+    __ cmp(r3, Operand(Smi::FromInt(0)), ne);
+    __ b(ne, &strings_not_empty);  // If either string was empty, return r0.
+
+    __ IncrementCounter(&Counters::string_add_native, 1, r2, r3);
+    __ add(sp, sp, Operand(2 * kPointerSize));
+    __ Ret();
+
+    __ bind(&strings_not_empty);
+  }
+
+  __ mov(r2, Operand(r2, ASR, kSmiTagSize));
+  __ mov(r3, Operand(r3, ASR, kSmiTagSize));
+  // Both strings are non-empty.
+  // r0: first string
+  // r1: second string
+  // r2: length of first string
+  // r3: length of second string
+  // r4: first string instance type (if string_check_)
+  // r5: second string instance type (if string_check_)
+  // Look at the length of the result of adding the two strings.
+  Label string_add_flat_result, longer_than_two;
+  // Adding two lengths can't overflow.
+  STATIC_ASSERT(String::kMaxLength < String::kMaxLength * 2);
+  __ add(r6, r2, Operand(r3));
+  // Use the runtime system when adding two one character strings, as it
+  // contains optimizations for this specific case using the symbol table.
+  __ cmp(r6, Operand(2));
+  __ b(ne, &longer_than_two);
+
+  // Check that both strings are non-external ascii strings.
+  if (!string_check_) {
+    __ ldr(r4, FieldMemOperand(r0, HeapObject::kMapOffset));
+    __ ldr(r5, FieldMemOperand(r1, HeapObject::kMapOffset));
+    __ ldrb(r4, FieldMemOperand(r4, Map::kInstanceTypeOffset));
+    __ ldrb(r5, FieldMemOperand(r5, Map::kInstanceTypeOffset));
+  }
+  __ JumpIfBothInstanceTypesAreNotSequentialAscii(r4, r5, r6, r7,
+                                                  &string_add_runtime);
+
+  // Get the two characters forming the sub string.
+  __ ldrb(r2, FieldMemOperand(r0, SeqAsciiString::kHeaderSize));
+  __ ldrb(r3, FieldMemOperand(r1, SeqAsciiString::kHeaderSize));
+
+  // Try to lookup two character string in symbol table. If it is not found
+  // just allocate a new one.
+  Label make_two_character_string;
+  StringHelper::GenerateTwoCharacterSymbolTableProbe(
+      masm, r2, r3, r6, r7, r4, r5, r9, &make_two_character_string);
+  __ IncrementCounter(&Counters::string_add_native, 1, r2, r3);
+  __ add(sp, sp, Operand(2 * kPointerSize));
+  __ Ret();
+
+  __ bind(&make_two_character_string);
+  // Resulting string has length 2 and first chars of two strings
+  // are combined into single halfword in r2 register.
+  // So we can fill resulting string without two loops by a single
+  // halfword store instruction (which assumes that processor is
+  // in a little endian mode)
+  __ mov(r6, Operand(2));
+  __ AllocateAsciiString(r0, r6, r4, r5, r9, &string_add_runtime);
+  __ strh(r2, FieldMemOperand(r0, SeqAsciiString::kHeaderSize));
+  __ IncrementCounter(&Counters::string_add_native, 1, r2, r3);
+  __ add(sp, sp, Operand(2 * kPointerSize));
+  __ Ret();
+
+  __ bind(&longer_than_two);
+  // Check if resulting string will be flat.
+  __ cmp(r6, Operand(String::kMinNonFlatLength));
+  __ b(lt, &string_add_flat_result);
+  // Handle exceptionally long strings in the runtime system.
+  STATIC_ASSERT((String::kMaxLength & 0x80000000) == 0);
+  ASSERT(IsPowerOf2(String::kMaxLength + 1));
+  // kMaxLength + 1 is representable as shifted literal, kMaxLength is not.
+  __ cmp(r6, Operand(String::kMaxLength + 1));
+  __ b(hs, &string_add_runtime);
+
+  // If result is not supposed to be flat, allocate a cons string object.
+  // If both strings are ascii the result is an ascii cons string.
+  if (!string_check_) {
+    __ ldr(r4, FieldMemOperand(r0, HeapObject::kMapOffset));
+    __ ldr(r5, FieldMemOperand(r1, HeapObject::kMapOffset));
+    __ ldrb(r4, FieldMemOperand(r4, Map::kInstanceTypeOffset));
+    __ ldrb(r5, FieldMemOperand(r5, Map::kInstanceTypeOffset));
+  }
+  Label non_ascii, allocated, ascii_data;
+  STATIC_ASSERT(kTwoByteStringTag == 0);
+  __ tst(r4, Operand(kStringEncodingMask));
+  __ tst(r5, Operand(kStringEncodingMask), ne);
+  __ b(eq, &non_ascii);
+
+  // Allocate an ASCII cons string.
+  __ bind(&ascii_data);
+  __ AllocateAsciiConsString(r7, r6, r4, r5, &string_add_runtime);
+  __ bind(&allocated);
+  // Fill the fields of the cons string.
+  __ str(r0, FieldMemOperand(r7, ConsString::kFirstOffset));
+  __ str(r1, FieldMemOperand(r7, ConsString::kSecondOffset));
+  __ mov(r0, Operand(r7));
+  __ IncrementCounter(&Counters::string_add_native, 1, r2, r3);
+  __ add(sp, sp, Operand(2 * kPointerSize));
+  __ Ret();
+
+  __ bind(&non_ascii);
+  // At least one of the strings is two-byte. Check whether it happens
+  // to contain only ascii characters.
+  // r4: first instance type.
+  // r5: second instance type.
+  __ tst(r4, Operand(kAsciiDataHintMask));
+  __ tst(r5, Operand(kAsciiDataHintMask), ne);
+  __ b(ne, &ascii_data);
+  __ eor(r4, r4, Operand(r5));
+  STATIC_ASSERT(kAsciiStringTag != 0 && kAsciiDataHintTag != 0);
+  __ and_(r4, r4, Operand(kAsciiStringTag | kAsciiDataHintTag));
+  __ cmp(r4, Operand(kAsciiStringTag | kAsciiDataHintTag));
+  __ b(eq, &ascii_data);
+
+  // Allocate a two byte cons string.
+  __ AllocateTwoByteConsString(r7, r6, r4, r5, &string_add_runtime);
+  __ jmp(&allocated);
+
+  // Handle creating a flat result. First check that both strings are
+  // sequential and that they have the same encoding.
+  // r0: first string
+  // r1: second string
+  // r2: length of first string
+  // r3: length of second string
+  // r4: first string instance type (if string_check_)
+  // r5: second string instance type (if string_check_)
+  // r6: sum of lengths.
+  __ bind(&string_add_flat_result);
+  if (!string_check_) {
+    __ ldr(r4, FieldMemOperand(r0, HeapObject::kMapOffset));
+    __ ldr(r5, FieldMemOperand(r1, HeapObject::kMapOffset));
+    __ ldrb(r4, FieldMemOperand(r4, Map::kInstanceTypeOffset));
+    __ ldrb(r5, FieldMemOperand(r5, Map::kInstanceTypeOffset));
+  }
+  // Check that both strings are sequential.
+  STATIC_ASSERT(kSeqStringTag == 0);
+  __ tst(r4, Operand(kStringRepresentationMask));
+  __ tst(r5, Operand(kStringRepresentationMask), eq);
+  __ b(ne, &string_add_runtime);
+  // Now check if both strings have the same encoding (ASCII/Two-byte).
+  // r0: first string.
+  // r1: second string.
+  // r2: length of first string.
+  // r3: length of second string.
+  // r6: sum of lengths..
+  Label non_ascii_string_add_flat_result;
+  ASSERT(IsPowerOf2(kStringEncodingMask));  // Just one bit to test.
+  __ eor(r7, r4, Operand(r5));
+  __ tst(r7, Operand(kStringEncodingMask));
+  __ b(ne, &string_add_runtime);
+  // And see if it's ASCII or two-byte.
+  __ tst(r4, Operand(kStringEncodingMask));
+  __ b(eq, &non_ascii_string_add_flat_result);
+
+  // Both strings are sequential ASCII strings. We also know that they are
+  // short (since the sum of the lengths is less than kMinNonFlatLength).
+  // r6: length of resulting flat string
+  __ AllocateAsciiString(r7, r6, r4, r5, r9, &string_add_runtime);
+  // Locate first character of result.
+  __ add(r6, r7, Operand(SeqAsciiString::kHeaderSize - kHeapObjectTag));
+  // Locate first character of first argument.
+  __ add(r0, r0, Operand(SeqAsciiString::kHeaderSize - kHeapObjectTag));
+  // r0: first character of first string.
+  // r1: second string.
+  // r2: length of first string.
+  // r3: length of second string.
+  // r6: first character of result.
+  // r7: result string.
+  StringHelper::GenerateCopyCharacters(masm, r6, r0, r2, r4, true);
+
+  // Load second argument and locate first character.
+  __ add(r1, r1, Operand(SeqAsciiString::kHeaderSize - kHeapObjectTag));
+  // r1: first character of second string.
+  // r3: length of second string.
+  // r6: next character of result.
+  // r7: result string.
+  StringHelper::GenerateCopyCharacters(masm, r6, r1, r3, r4, true);
+  __ mov(r0, Operand(r7));
+  __ IncrementCounter(&Counters::string_add_native, 1, r2, r3);
+  __ add(sp, sp, Operand(2 * kPointerSize));
+  __ Ret();
+
+  __ bind(&non_ascii_string_add_flat_result);
+  // Both strings are sequential two byte strings.
+  // r0: first string.
+  // r1: second string.
+  // r2: length of first string.
+  // r3: length of second string.
+  // r6: sum of length of strings.
+  __ AllocateTwoByteString(r7, r6, r4, r5, r9, &string_add_runtime);
+  // r0: first string.
+  // r1: second string.
+  // r2: length of first string.
+  // r3: length of second string.
+  // r7: result string.
+
+  // Locate first character of result.
+  __ add(r6, r7, Operand(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
+  // Locate first character of first argument.
+  __ add(r0, r0, Operand(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
+
+  // r0: first character of first string.
+  // r1: second string.
+  // r2: length of first string.
+  // r3: length of second string.
+  // r6: first character of result.
+  // r7: result string.
+  StringHelper::GenerateCopyCharacters(masm, r6, r0, r2, r4, false);
+
+  // Locate first character of second argument.
+  __ add(r1, r1, Operand(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
+
+  // r1: first character of second string.
+  // r3: length of second string.
+  // r6: next character of result (after copy of first string).
+  // r7: result string.
+  StringHelper::GenerateCopyCharacters(masm, r6, r1, r3, r4, false);
+
+  __ mov(r0, Operand(r7));
+  __ IncrementCounter(&Counters::string_add_native, 1, r2, r3);
+  __ add(sp, sp, Operand(2 * kPointerSize));
+  __ Ret();
+
+  // Just jump to runtime to add the two strings.
+  __ bind(&string_add_runtime);
+  __ TailCallRuntime(Runtime::kStringAdd, 2, 1);
+}
+
+
+#undef __
+
+} }  // namespace v8::internal
+
+#endif  // V8_TARGET_ARCH_ARM