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

src/ia32/code-stubs-ia32.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_IA32)
+
+#include "bootstrapper.h"
+#include "code-stubs-ia32.h"
+#include "codegen-inl.h"
+#include "regexp-macro-assembler.h"
+
+namespace v8 {
+namespace internal {
+
+#define __ ACCESS_MASM(masm)
+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 esi.
+  Label gc;
+  __ AllocateInNewSpace(JSFunction::kSize, eax, ebx, ecx, &gc, TAG_OBJECT);
+
+  // Get the function info from the stack.
+  __ mov(edx, Operand(esp, 1 * kPointerSize));
+
+  // Compute the function map in the current global context and set that
+  // as the map of the allocated object.
+  __ mov(ecx, Operand(esi, Context::SlotOffset(Context::GLOBAL_INDEX)));
+  __ mov(ecx, FieldOperand(ecx, GlobalObject::kGlobalContextOffset));
+  __ mov(ecx, Operand(ecx, Context::SlotOffset(Context::FUNCTION_MAP_INDEX)));
+  __ mov(FieldOperand(eax, JSObject::kMapOffset), ecx);
+
+  // Initialize the rest of the function. We don't have to update the
+  // write barrier because the allocated object is in new space.
+  __ mov(ebx, Immediate(Factory::empty_fixed_array()));
+  __ mov(FieldOperand(eax, JSObject::kPropertiesOffset), ebx);
+  __ mov(FieldOperand(eax, JSObject::kElementsOffset), ebx);
+  __ mov(FieldOperand(eax, JSFunction::kPrototypeOrInitialMapOffset),
+         Immediate(Factory::the_hole_value()));
+  __ mov(FieldOperand(eax, JSFunction::kSharedFunctionInfoOffset), edx);
+  __ mov(FieldOperand(eax, JSFunction::kContextOffset), esi);
+  __ mov(FieldOperand(eax, JSFunction::kLiteralsOffset), ebx);
+
+  // Initialize the code pointer in the function to be the one
+  // found in the shared function info object.
+  __ mov(edx, FieldOperand(edx, SharedFunctionInfo::kCodeOffset));
+  __ lea(edx, FieldOperand(edx, Code::kHeaderSize));
+  __ mov(FieldOperand(eax, JSFunction::kCodeEntryOffset), edx);
+
+  // Return and remove the on-stack parameter.
+  __ ret(1 * kPointerSize);
+
+  // Create a new closure through the slower runtime call.
+  __ bind(&gc);
+  __ pop(ecx);  // Temporarily remove return address.
+  __ pop(edx);
+  __ push(esi);
+  __ push(edx);
+  __ push(ecx);  // Restore return address.
+  __ 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;
+  __ AllocateInNewSpace((length * kPointerSize) + FixedArray::kHeaderSize,
+                        eax, ebx, ecx, &gc, TAG_OBJECT);
+
+  // Get the function from the stack.
+  __ mov(ecx, Operand(esp, 1 * kPointerSize));
+
+  // Setup the object header.
+  __ mov(FieldOperand(eax, HeapObject::kMapOffset), Factory::context_map());
+  __ mov(FieldOperand(eax, Context::kLengthOffset),
+         Immediate(Smi::FromInt(length)));
+
+  // Setup the fixed slots.
+  __ xor_(ebx, Operand(ebx));  // Set to NULL.
+  __ mov(Operand(eax, Context::SlotOffset(Context::CLOSURE_INDEX)), ecx);
+  __ mov(Operand(eax, Context::SlotOffset(Context::FCONTEXT_INDEX)), eax);
+  __ mov(Operand(eax, Context::SlotOffset(Context::PREVIOUS_INDEX)), ebx);
+  __ mov(Operand(eax, Context::SlotOffset(Context::EXTENSION_INDEX)), ebx);
+
+  // Copy the global object from the surrounding context. We go through the
+  // context in the function (ecx) to match the allocation behavior we have
+  // in the runtime system (see Heap::AllocateFunctionContext).
+  __ mov(ebx, FieldOperand(ecx, JSFunction::kContextOffset));
+  __ mov(ebx, Operand(ebx, Context::SlotOffset(Context::GLOBAL_INDEX)));
+  __ mov(Operand(eax, Context::SlotOffset(Context::GLOBAL_INDEX)), ebx);
+
+  // Initialize the rest of the slots to undefined.
+  __ mov(ebx, Factory::undefined_value());
+  for (int i = Context::MIN_CONTEXT_SLOTS; i < length; i++) {
+    __ mov(Operand(eax, Context::SlotOffset(i)), ebx);
+  }
+
+  // Return and remove the on-stack parameter.
+  __ mov(esi, Operand(eax));
+  __ ret(1 * kPointerSize);
+
+  // Need to collect. Call into runtime system.
+  __ bind(&gc);
+  __ TailCallRuntime(Runtime::kNewContext, 1, 1);
+}
+
+
+void FastCloneShallowArrayStub::Generate(MacroAssembler* masm) {
+  // Stack layout on entry:
+  //
+  // [esp + kPointerSize]: constant elements.
+  // [esp + (2 * kPointerSize)]: literal index.
+  // [esp + (3 * 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 ecx and check if we need to create a
+  // boilerplate.
+  Label slow_case;
+  __ mov(ecx, Operand(esp, 3 * kPointerSize));
+  __ mov(eax, Operand(esp, 2 * kPointerSize));
+  STATIC_ASSERT(kPointerSize == 4);
+  STATIC_ASSERT(kSmiTagSize == 1);
+  STATIC_ASSERT(kSmiTag == 0);
+  __ mov(ecx, CodeGenerator::FixedArrayElementOperand(ecx, eax));
+  __ cmp(ecx, Factory::undefined_value());
+  __ j(equal, &slow_case);
+
+  if (FLAG_debug_code) {
+    const char* message;
+    Handle<Map> expected_map;
+    if (mode_ == CLONE_ELEMENTS) {
+      message = "Expected (writable) fixed array";
+      expected_map = Factory::fixed_array_map();
+    } else {
+      ASSERT(mode_ == COPY_ON_WRITE_ELEMENTS);
+      message = "Expected copy-on-write fixed array";
+      expected_map = Factory::fixed_cow_array_map();
+    }
+    __ push(ecx);
+    __ mov(ecx, FieldOperand(ecx, JSArray::kElementsOffset));
+    __ cmp(FieldOperand(ecx, HeapObject::kMapOffset), expected_map);
+    __ Assert(equal, message);
+    __ pop(ecx);
+  }
+
+  // Allocate both the JS array and the elements array in one big
+  // allocation. This avoids multiple limit checks.
+  __ AllocateInNewSpace(size, eax, ebx, edx, &slow_case, TAG_OBJECT);
+
+  // Copy the JS array part.
+  for (int i = 0; i < JSArray::kSize; i += kPointerSize) {
+    if ((i != JSArray::kElementsOffset) || (length_ == 0)) {
+      __ mov(ebx, FieldOperand(ecx, i));
+      __ mov(FieldOperand(eax, i), ebx);
+    }
+  }
+
+  if (length_ > 0) {
+    // Get hold of the elements array of the boilerplate and setup the
+    // elements pointer in the resulting object.
+    __ mov(ecx, FieldOperand(ecx, JSArray::kElementsOffset));
+    __ lea(edx, Operand(eax, JSArray::kSize));
+    __ mov(FieldOperand(eax, JSArray::kElementsOffset), edx);
+
+    // Copy the elements array.
+    for (int i = 0; i < elements_size; i += kPointerSize) {
+      __ mov(ebx, FieldOperand(ecx, i));
+      __ mov(FieldOperand(edx, i), ebx);
+    }
+  }
+
+  // Return and remove the on-stack parameters.
+  __ ret(3 * kPointerSize);
+
+  __ bind(&slow_case);
+  __ TailCallRuntime(Runtime::kCreateArrayLiteralShallow, 3, 1);
+}
+
+
+// NOTE: The stub does not handle the inlined cases (Smis, Booleans, undefined).
+void ToBooleanStub::Generate(MacroAssembler* masm) {
+  Label false_result, true_result, not_string;
+  __ mov(eax, Operand(esp, 1 * kPointerSize));
+
+  // 'null' => false.
+  __ cmp(eax, Factory::null_value());
+  __ j(equal, &false_result);
+
+  // Get the map and type of the heap object.
+  __ mov(edx, FieldOperand(eax, HeapObject::kMapOffset));
+  __ movzx_b(ecx, FieldOperand(edx, Map::kInstanceTypeOffset));
+
+  // Undetectable => false.
+  __ test_b(FieldOperand(edx, Map::kBitFieldOffset),
+            1 << Map::kIsUndetectable);
+  __ j(not_zero, &false_result);
+
+  // JavaScript object => true.
+  __ CmpInstanceType(edx, FIRST_JS_OBJECT_TYPE);
+  __ j(above_equal, &true_result);
+
+  // String value => false iff empty.
+  __ CmpInstanceType(edx, FIRST_NONSTRING_TYPE);
+  __ j(above_equal, &not_string);
+  STATIC_ASSERT(kSmiTag == 0);
+  __ cmp(FieldOperand(eax, String::kLengthOffset), Immediate(0));
+  __ j(zero, &false_result);
+  __ jmp(&true_result);
+
+  __ bind(&not_string);
+  // HeapNumber => false iff +0, -0, or NaN.
+  __ cmp(edx, Factory::heap_number_map());
+  __ j(not_equal, &true_result);
+  __ fldz();
+  __ fld_d(FieldOperand(eax, HeapNumber::kValueOffset));
+  __ FCmp();
+  __ j(zero, &false_result);
+  // Fall through to |true_result|.
+
+  // Return 1/0 for true/false in eax.
+  __ bind(&true_result);
+  __ mov(eax, 1);
+  __ ret(1 * kPointerSize);
+  __ bind(&false_result);
+  __ mov(eax, 0);
+  __ ret(1 * kPointerSize);
+}
+
+
+const char* GenericBinaryOpStub::GetName() {
+  if (name_ != NULL) return name_;
+  const int kMaxNameLength = 100;
+  name_ = Bootstrapper::AllocateAutoDeletedArray(kMaxNameLength);
+  if (name_ == NULL) return "OOM";
+  const char* op_name = Token::Name(op_);
+  const char* overwrite_name;
+  switch (mode_) {
+    case NO_OVERWRITE: overwrite_name = "Alloc"; break;
+    case OVERWRITE_RIGHT: overwrite_name = "OverwriteRight"; break;
+    case OVERWRITE_LEFT: overwrite_name = "OverwriteLeft"; break;
+    default: overwrite_name = "UnknownOverwrite"; break;
+  }
+
+  OS::SNPrintF(Vector<char>(name_, kMaxNameLength),
+               "GenericBinaryOpStub_%s_%s%s_%s%s_%s_%s",
+               op_name,
+               overwrite_name,
+               (flags_ & NO_SMI_CODE_IN_STUB) ? "_NoSmiInStub" : "",
+               args_in_registers_ ? "RegArgs" : "StackArgs",
+               args_reversed_ ? "_R" : "",
+               static_operands_type_.ToString(),
+               BinaryOpIC::GetName(runtime_operands_type_));
+  return name_;
+}
+
+
+void GenericBinaryOpStub::GenerateCall(
+    MacroAssembler* masm,
+    Register left,
+    Register right) {
+  if (!ArgsInRegistersSupported()) {
+    // Pass arguments on the stack.
+    __ push(left);
+    __ push(right);
+  } else {
+    // The calling convention with registers is left in edx and right in eax.
+    Register left_arg = edx;
+    Register right_arg = eax;
+    if (!(left.is(left_arg) && right.is(right_arg))) {
+      if (left.is(right_arg) && right.is(left_arg)) {
+        if (IsOperationCommutative()) {
+          SetArgsReversed();
+        } else {
+          __ xchg(left, right);
+        }
+      } else if (left.is(left_arg)) {
+        __ mov(right_arg, right);
+      } else if (right.is(right_arg)) {
+        __ mov(left_arg, left);
+      } else if (left.is(right_arg)) {
+        if (IsOperationCommutative()) {
+          __ mov(left_arg, right);
+          SetArgsReversed();
+        } else {
+          // Order of moves important to avoid destroying left argument.
+          __ mov(left_arg, left);
+          __ mov(right_arg, right);
+        }
+      } else if (right.is(left_arg)) {
+        if (IsOperationCommutative()) {
+          __ mov(right_arg, left);
+          SetArgsReversed();
+        } else {
+          // Order of moves important to avoid destroying right argument.
+          __ mov(right_arg, right);
+          __ mov(left_arg, left);
+        }
+      } else {
+        // Order of moves is not important.
+        __ mov(left_arg, left);
+        __ mov(right_arg, right);
+      }
+    }
+
+    // Update flags to indicate that arguments are in registers.
+    SetArgsInRegisters();
+    __ IncrementCounter(&Counters::generic_binary_stub_calls_regs, 1);
+  }
+
+  // Call the stub.
+  __ CallStub(this);
+}
+
+
+void GenericBinaryOpStub::GenerateCall(
+    MacroAssembler* masm,
+    Register left,
+    Smi* right) {
+  if (!ArgsInRegistersSupported()) {
+    // Pass arguments on the stack.
+    __ push(left);
+    __ push(Immediate(right));
+  } else {
+    // The calling convention with registers is left in edx and right in eax.
+    Register left_arg = edx;
+    Register right_arg = eax;
+    if (left.is(left_arg)) {
+      __ mov(right_arg, Immediate(right));
+    } else if (left.is(right_arg) && IsOperationCommutative()) {
+      __ mov(left_arg, Immediate(right));
+      SetArgsReversed();
+    } else {
+      // For non-commutative operations, left and right_arg might be
+      // the same register.  Therefore, the order of the moves is
+      // important here in order to not overwrite left before moving
+      // it to left_arg.
+      __ mov(left_arg, left);
+      __ mov(right_arg, Immediate(right));
+    }
+
+    // Update flags to indicate that arguments are in registers.
+    SetArgsInRegisters();
+    __ IncrementCounter(&Counters::generic_binary_stub_calls_regs, 1);
+  }
+
+  // Call the stub.
+  __ CallStub(this);
+}
+
+
+void GenericBinaryOpStub::GenerateCall(
+    MacroAssembler* masm,
+    Smi* left,
+    Register right) {
+  if (!ArgsInRegistersSupported()) {
+    // Pass arguments on the stack.
+    __ push(Immediate(left));
+    __ push(right);
+  } else {
+    // The calling convention with registers is left in edx and right in eax.
+    Register left_arg = edx;
+    Register right_arg = eax;
+    if (right.is(right_arg)) {
+      __ mov(left_arg, Immediate(left));
+    } else if (right.is(left_arg) && IsOperationCommutative()) {
+      __ mov(right_arg, Immediate(left));
+      SetArgsReversed();
+    } else {
+      // For non-commutative operations, right and left_arg might be
+      // the same register.  Therefore, the order of the moves is
+      // important here in order to not overwrite right before moving
+      // it to right_arg.
+      __ mov(right_arg, right);
+      __ mov(left_arg, Immediate(left));
+    }
+    // Update flags to indicate that arguments are in registers.
+    SetArgsInRegisters();
+    __ IncrementCounter(&Counters::generic_binary_stub_calls_regs, 1);
+  }
+
+  // Call the stub.
+  __ CallStub(this);
+}
+
+
+class FloatingPointHelper : public AllStatic {
+ public:
+
+  enum ArgLocation {
+    ARGS_ON_STACK,
+    ARGS_IN_REGISTERS
+  };
+
+  // Code pattern for loading a floating point value. Input value must
+  // be either a smi or a heap number object (fp value). Requirements:
+  // operand in register number. Returns operand as floating point number
+  // on FPU stack.
+  static void LoadFloatOperand(MacroAssembler* masm, Register number);
+
+  // Code pattern for loading floating point values. Input values must
+  // be either smi or heap number objects (fp values). Requirements:
+  // operand_1 on TOS+1 or in edx, operand_2 on TOS+2 or in eax.
+  // Returns operands as floating point numbers on FPU stack.
+  static void LoadFloatOperands(MacroAssembler* masm,
+                                Register scratch,
+                                ArgLocation arg_location = ARGS_ON_STACK);
+
+  // Similar to LoadFloatOperand but assumes that both operands are smis.
+  // Expects operands in edx, eax.
+  static void LoadFloatSmis(MacroAssembler* masm, Register scratch);
+
+  // Test if operands are smi or number objects (fp). Requirements:
+  // operand_1 in eax, operand_2 in edx; falls through on float
+  // operands, jumps to the non_float label otherwise.
+  static void CheckFloatOperands(MacroAssembler* masm,
+                                 Label* non_float,
+                                 Register scratch);
+
+  // Takes the operands in edx and eax and loads them as integers in eax
+  // and ecx.
+  static void LoadAsIntegers(MacroAssembler* masm,
+                             TypeInfo type_info,
+                             bool use_sse3,
+                             Label* operand_conversion_failure);
+  static void LoadNumbersAsIntegers(MacroAssembler* masm,
+                                    TypeInfo type_info,
+                                    bool use_sse3,
+                                    Label* operand_conversion_failure);
+  static void LoadUnknownsAsIntegers(MacroAssembler* masm,
+                                     bool use_sse3,
+                                     Label* operand_conversion_failure);
+
+  // Test if operands are smis or heap numbers and load them
+  // into xmm0 and xmm1 if they are. Operands are in edx and eax.
+  // Leaves operands unchanged.
+  static void LoadSSE2Operands(MacroAssembler* masm);
+
+  // Test if operands are numbers (smi or HeapNumber objects), and load
+  // them into xmm0 and xmm1 if they are.  Jump to label not_numbers if
+  // either operand is not a number.  Operands are in edx and eax.
+  // Leaves operands unchanged.
+  static void LoadSSE2Operands(MacroAssembler* masm, Label* not_numbers);
+
+  // Similar to LoadSSE2Operands but assumes that both operands are smis.
+  // Expects operands in edx, eax.
+  static void LoadSSE2Smis(MacroAssembler* masm, Register scratch);
+};
+
+
+void GenericBinaryOpStub::GenerateSmiCode(MacroAssembler* masm, Label* slow) {
+  // 1. Move arguments into edx, eax except for DIV and MOD, which need the
+  // dividend in eax and edx free for the division.  Use eax, ebx for those.
+  Comment load_comment(masm, "-- Load arguments");
+  Register left = edx;
+  Register right = eax;
+  if (op_ == Token::DIV || op_ == Token::MOD) {
+    left = eax;
+    right = ebx;
+    if (HasArgsInRegisters()) {
+      __ mov(ebx, eax);
+      __ mov(eax, edx);
+    }
+  }
+  if (!HasArgsInRegisters()) {
+    __ mov(right, Operand(esp, 1 * kPointerSize));
+    __ mov(left, Operand(esp, 2 * kPointerSize));
+  }
+
+  if (static_operands_type_.IsSmi()) {
+    if (FLAG_debug_code) {
+      __ AbortIfNotSmi(left);
+      __ AbortIfNotSmi(right);
+    }
+    if (op_ == Token::BIT_OR) {
+      __ or_(right, Operand(left));
+      GenerateReturn(masm);
+      return;
+    } else if (op_ == Token::BIT_AND) {
+      __ and_(right, Operand(left));
+      GenerateReturn(masm);
+      return;
+    } else if (op_ == Token::BIT_XOR) {
+      __ xor_(right, Operand(left));
+      GenerateReturn(masm);
+      return;
+    }
+  }
+
+  // 2. Prepare the smi check of both operands by oring them together.
+  Comment smi_check_comment(masm, "-- Smi check arguments");
+  Label not_smis;
+  Register combined = ecx;
+  ASSERT(!left.is(combined) && !right.is(combined));
+  switch (op_) {
+    case Token::BIT_OR:
+      // Perform the operation into eax and smi check the result.  Preserve
+      // eax in case the result is not a smi.
+      ASSERT(!left.is(ecx) && !right.is(ecx));
+      __ mov(ecx, right);
+      __ or_(right, Operand(left));  // Bitwise or is commutative.
+      combined = right;
+      break;
+
+    case Token::BIT_XOR:
+    case Token::BIT_AND:
+    case Token::ADD:
+    case Token::SUB:
+    case Token::MUL:
+    case Token::DIV:
+    case Token::MOD:
+      __ mov(combined, right);
+      __ or_(combined, Operand(left));
+      break;
+
+    case Token::SHL:
+    case Token::SAR:
+    case Token::SHR:
+      // Move the right operand into ecx for the shift operation, use eax
+      // for the smi check register.
+      ASSERT(!left.is(ecx) && !right.is(ecx));
+      __ mov(ecx, right);
+      __ or_(right, Operand(left));
+      combined = right;
+      break;
+
+    default:
+      break;
+  }
+
+  // 3. Perform the smi check of the operands.
+  STATIC_ASSERT(kSmiTag == 0);  // Adjust zero check if not the case.
+  __ test(combined, Immediate(kSmiTagMask));
+  __ j(not_zero, &not_smis, not_taken);
+
+  // 4. Operands are both smis, perform the operation leaving the result in
+  // eax and check the result if necessary.
+  Comment perform_smi(masm, "-- Perform smi operation");
+  Label use_fp_on_smis;
+  switch (op_) {
+    case Token::BIT_OR:
+      // Nothing to do.
+      break;
+
+    case Token::BIT_XOR:
+      ASSERT(right.is(eax));
+      __ xor_(right, Operand(left));  // Bitwise xor is commutative.
+      break;
+
+    case Token::BIT_AND:
+      ASSERT(right.is(eax));
+      __ and_(right, Operand(left));  // Bitwise and is commutative.
+      break;
+
+    case Token::SHL:
+      // Remove tags from operands (but keep sign).
+      __ SmiUntag(left);
+      __ SmiUntag(ecx);
+      // Perform the operation.
+      __ shl_cl(left);
+      // Check that the *signed* result fits in a smi.
+      __ cmp(left, 0xc0000000);
+      __ j(sign, &use_fp_on_smis, not_taken);
+      // Tag the result and store it in register eax.
+      __ SmiTag(left);
+      __ mov(eax, left);
+      break;
+
+    case Token::SAR:
+      // Remove tags from operands (but keep sign).
+      __ SmiUntag(left);
+      __ SmiUntag(ecx);
+      // Perform the operation.
+      __ sar_cl(left);
+      // Tag the result and store it in register eax.
+      __ SmiTag(left);
+      __ mov(eax, left);
+      break;
+
+    case Token::SHR:
+      // Remove tags from operands (but keep sign).
+      __ SmiUntag(left);
+      __ SmiUntag(ecx);
+      // Perform the operation.
+      __ shr_cl(left);
+      // Check that the *unsigned* result fits in a smi.
+      // Neither of the two high-order bits can be set:
+      // - 0x80000000: high bit would be lost when smi tagging.
+      // - 0x40000000: this number would convert to negative when
+      // Smi tagging these two cases can only happen with shifts
+      // by 0 or 1 when handed a valid smi.
+      __ test(left, Immediate(0xc0000000));
+      __ j(not_zero, slow, not_taken);
+      // Tag the result and store it in register eax.
+      __ SmiTag(left);
+      __ mov(eax, left);
+      break;
+
+    case Token::ADD:
+      ASSERT(right.is(eax));
+      __ add(right, Operand(left));  // Addition is commutative.
+      __ j(overflow, &use_fp_on_smis, not_taken);
+      break;
+
+    case Token::SUB:
+      __ sub(left, Operand(right));
+      __ j(overflow, &use_fp_on_smis, not_taken);
+      __ mov(eax, left);
+      break;
+
+    case Token::MUL:
+      // If the smi tag is 0 we can just leave the tag on one operand.
+      STATIC_ASSERT(kSmiTag == 0);  // Adjust code below if not the case.
+      // We can't revert the multiplication if the result is not a smi
+      // so save the right operand.
+      __ mov(ebx, right);
+      // Remove tag from one of the operands (but keep sign).
+      __ SmiUntag(right);
+      // Do multiplication.
+      __ imul(right, Operand(left));  // Multiplication is commutative.
+      __ j(overflow, &use_fp_on_smis, not_taken);
+      // Check for negative zero result.  Use combined = left | right.
+      __ NegativeZeroTest(right, combined, &use_fp_on_smis);
+      break;
+
+    case Token::DIV:
+      // We can't revert the division if the result is not a smi so
+      // save the left operand.
+      __ mov(edi, left);
+      // Check for 0 divisor.
+      __ test(right, Operand(right));
+      __ j(zero, &use_fp_on_smis, not_taken);
+      // Sign extend left into edx:eax.
+      ASSERT(left.is(eax));
+      __ cdq();
+      // Divide edx:eax by right.
+      __ idiv(right);
+      // Check for the corner case of dividing the most negative smi by
+      // -1. We cannot use the overflow flag, since it is not set by idiv
+      // instruction.
+      STATIC_ASSERT(kSmiTag == 0 && kSmiTagSize == 1);
+      __ cmp(eax, 0x40000000);
+      __ j(equal, &use_fp_on_smis);
+      // Check for negative zero result.  Use combined = left | right.
+      __ NegativeZeroTest(eax, combined, &use_fp_on_smis);
+      // Check that the remainder is zero.
+      __ test(edx, Operand(edx));
+      __ j(not_zero, &use_fp_on_smis);
+      // Tag the result and store it in register eax.
+      __ SmiTag(eax);
+      break;
+
+    case Token::MOD:
+      // Check for 0 divisor.
+      __ test(right, Operand(right));
+      __ j(zero, &not_smis, not_taken);
+
+      // Sign extend left into edx:eax.
+      ASSERT(left.is(eax));
+      __ cdq();
+      // Divide edx:eax by right.
+      __ idiv(right);
+      // Check for negative zero result.  Use combined = left | right.
+      __ NegativeZeroTest(edx, combined, slow);
+      // Move remainder to register eax.
+      __ mov(eax, edx);
+      break;
+
+    default:
+      UNREACHABLE();
+  }
+
+  // 5. Emit return of result in eax.
+  GenerateReturn(masm);
+
+  // 6. For some operations emit inline code to perform floating point
+  // operations on known smis (e.g., if the result of the operation
+  // overflowed the smi range).
+  switch (op_) {
+    case Token::SHL: {
+      Comment perform_float(masm, "-- Perform float operation on smis");
+      __ bind(&use_fp_on_smis);
+      // Result we want is in left == edx, so we can put the allocated heap
+      // number in eax.
+      __ AllocateHeapNumber(eax, ecx, ebx, slow);
+      // Store the result in the HeapNumber and return.
+      if (CpuFeatures::IsSupported(SSE2)) {
+        CpuFeatures::Scope use_sse2(SSE2);
+        __ cvtsi2sd(xmm0, Operand(left));
+        __ movdbl(FieldOperand(eax, HeapNumber::kValueOffset), xmm0);
+      } else {
+        // It's OK to overwrite the right argument on the stack because we
+        // are about to return.
+        __ mov(Operand(esp, 1 * kPointerSize), left);
+        __ fild_s(Operand(esp, 1 * kPointerSize));
+        __ fstp_d(FieldOperand(eax, HeapNumber::kValueOffset));
+      }
+      GenerateReturn(masm);
+      break;
+    }
+
+    case Token::ADD:
+    case Token::SUB:
+    case Token::MUL:
+    case Token::DIV: {
+      Comment perform_float(masm, "-- Perform float operation on smis");
+      __ bind(&use_fp_on_smis);
+      // Restore arguments to edx, eax.
+      switch (op_) {
+        case Token::ADD:
+          // Revert right = right + left.
+          __ sub(right, Operand(left));
+          break;
+        case Token::SUB:
+          // Revert left = left - right.
+          __ add(left, Operand(right));
+          break;
+        case Token::MUL:
+          // Right was clobbered but a copy is in ebx.
+          __ mov(right, ebx);
+          break;
+        case Token::DIV:
+          // Left was clobbered but a copy is in edi.  Right is in ebx for
+          // division.
+          __ mov(edx, edi);
+          __ mov(eax, right);
+          break;
+        default: UNREACHABLE();
+          break;
+      }
+      __ AllocateHeapNumber(ecx, ebx, no_reg, slow);
+      if (CpuFeatures::IsSupported(SSE2)) {
+        CpuFeatures::Scope use_sse2(SSE2);
+        FloatingPointHelper::LoadSSE2Smis(masm, ebx);
+        switch (op_) {
+          case Token::ADD: __ addsd(xmm0, xmm1); break;
+          case Token::SUB: __ subsd(xmm0, xmm1); break;
+          case Token::MUL: __ mulsd(xmm0, xmm1); break;
+          case Token::DIV: __ divsd(xmm0, xmm1); break;
+          default: UNREACHABLE();
+        }
+        __ movdbl(FieldOperand(ecx, HeapNumber::kValueOffset), xmm0);
+      } else {  // SSE2 not available, use FPU.
+        FloatingPointHelper::LoadFloatSmis(masm, ebx);
+        switch (op_) {
+          case Token::ADD: __ faddp(1); break;
+          case Token::SUB: __ fsubp(1); break;
+          case Token::MUL: __ fmulp(1); break;
+          case Token::DIV: __ fdivp(1); break;
+          default: UNREACHABLE();
+        }
+        __ fstp_d(FieldOperand(ecx, HeapNumber::kValueOffset));
+      }
+      __ mov(eax, ecx);
+      GenerateReturn(masm);
+      break;
+    }
+
+    default:
+      break;
+  }
+
+  // 7. Non-smi operands, fall out to the non-smi code with the operands in
+  // edx and eax.
+  Comment done_comment(masm, "-- Enter non-smi code");
+  __ bind(&not_smis);
+  switch (op_) {
+    case Token::BIT_OR:
+    case Token::SHL:
+    case Token::SAR:
+    case Token::SHR:
+      // Right operand is saved in ecx and eax was destroyed by the smi
+      // check.
+      __ mov(eax, ecx);
+      break;
+
+    case Token::DIV:
+    case Token::MOD:
+      // Operands are in eax, ebx at this point.
+      __ mov(edx, eax);
+      __ mov(eax, ebx);
+      break;
+
+    default:
+      break;
+  }
+}
+
+
+void GenericBinaryOpStub::Generate(MacroAssembler* masm) {
+  Label call_runtime;
+
+  __ IncrementCounter(&Counters::generic_binary_stub_calls, 1);
+
+  // Generate fast case smi code if requested. This flag is set when the fast
+  // case smi code is not generated by the caller. Generating it here will speed
+  // up common operations.
+  if (ShouldGenerateSmiCode()) {
+    GenerateSmiCode(masm, &call_runtime);
+  } else if (op_ != Token::MOD) {  // MOD goes straight to runtime.
+    if (!HasArgsInRegisters()) {
+      GenerateLoadArguments(masm);
+    }
+  }
+
+  // Floating point case.
+  if (ShouldGenerateFPCode()) {
+    switch (op_) {
+      case Token::ADD:
+      case Token::SUB:
+      case Token::MUL:
+      case Token::DIV: {
+        if (runtime_operands_type_ == BinaryOpIC::DEFAULT &&
+            HasSmiCodeInStub()) {
+          // Execution reaches this point when the first non-smi argument occurs
+          // (and only if smi code is generated). This is the right moment to
+          // patch to HEAP_NUMBERS state. The transition is attempted only for
+          // the four basic operations. The stub stays in the DEFAULT state
+          // forever for all other operations (also if smi code is skipped).
+          GenerateTypeTransition(masm);
+          break;
+        }
+
+        Label not_floats;
+        if (CpuFeatures::IsSupported(SSE2)) {
+          CpuFeatures::Scope use_sse2(SSE2);
+          if (static_operands_type_.IsNumber()) {
+            if (FLAG_debug_code) {
+              // Assert at runtime that inputs are only numbers.
+              __ AbortIfNotNumber(edx);
+              __ AbortIfNotNumber(eax);
+            }
+            if (static_operands_type_.IsSmi()) {
+              if (FLAG_debug_code) {
+                __ AbortIfNotSmi(edx);
+                __ AbortIfNotSmi(eax);
+              }
+              FloatingPointHelper::LoadSSE2Smis(masm, ecx);
+            } else {
+              FloatingPointHelper::LoadSSE2Operands(masm);
+            }
+          } else {
+            FloatingPointHelper::LoadSSE2Operands(masm, &call_runtime);
+          }
+
+          switch (op_) {
+            case Token::ADD: __ addsd(xmm0, xmm1); break;
+            case Token::SUB: __ subsd(xmm0, xmm1); break;
+            case Token::MUL: __ mulsd(xmm0, xmm1); break;
+            case Token::DIV: __ divsd(xmm0, xmm1); break;
+            default: UNREACHABLE();
+          }
+          GenerateHeapResultAllocation(masm, &call_runtime);
+          __ movdbl(FieldOperand(eax, HeapNumber::kValueOffset), xmm0);
+          GenerateReturn(masm);
+        } else {  // SSE2 not available, use FPU.
+          if (static_operands_type_.IsNumber()) {
+            if (FLAG_debug_code) {
+              // Assert at runtime that inputs are only numbers.
+              __ AbortIfNotNumber(edx);
+              __ AbortIfNotNumber(eax);
+            }
+          } else {
+            FloatingPointHelper::CheckFloatOperands(masm, &call_runtime, ebx);
+          }
+          FloatingPointHelper::LoadFloatOperands(
+              masm,
+              ecx,
+              FloatingPointHelper::ARGS_IN_REGISTERS);
+          switch (op_) {
+            case Token::ADD: __ faddp(1); break;
+            case Token::SUB: __ fsubp(1); break;
+            case Token::MUL: __ fmulp(1); break;
+            case Token::DIV: __ fdivp(1); break;
+            default: UNREACHABLE();
+          }
+          Label after_alloc_failure;
+          GenerateHeapResultAllocation(masm, &after_alloc_failure);
+          __ fstp_d(FieldOperand(eax, HeapNumber::kValueOffset));
+          GenerateReturn(masm);
+          __ bind(&after_alloc_failure);
+          __ ffree();
+          __ jmp(&call_runtime);
+        }
+        __ bind(&not_floats);
+        if (runtime_operands_type_ == BinaryOpIC::DEFAULT &&
+            !HasSmiCodeInStub()) {
+          // Execution reaches this point when the first non-number argument
+          // occurs (and only if smi code is skipped from the stub, otherwise
+          // the patching has already been done earlier in this case branch).
+          // Try patching to STRINGS for ADD operation.
+          if (op_ == Token::ADD) {
+            GenerateTypeTransition(masm);
+          }
+        }
+        break;
+      }
+      case Token::MOD: {
+        // For MOD we go directly to runtime in the non-smi case.
+        break;
+      }
+      case Token::BIT_OR:
+      case Token::BIT_AND:
+      case Token::BIT_XOR:
+      case Token::SAR:
+      case Token::SHL:
+      case Token::SHR: {
+        Label non_smi_result;
+        FloatingPointHelper::LoadAsIntegers(masm,
+                                            static_operands_type_,
+                                            use_sse3_,
+                                            &call_runtime);
+        switch (op_) {
+          case Token::BIT_OR:  __ or_(eax, Operand(ecx)); break;
+          case Token::BIT_AND: __ and_(eax, Operand(ecx)); break;
+          case Token::BIT_XOR: __ xor_(eax, Operand(ecx)); break;
+          case Token::SAR: __ sar_cl(eax); break;
+          case Token::SHL: __ shl_cl(eax); break;
+          case Token::SHR: __ shr_cl(eax); break;
+          default: UNREACHABLE();
+        }
+        if (op_ == Token::SHR) {
+          // Check if result is non-negative and fits in a smi.
+          __ test(eax, Immediate(0xc0000000));
+          __ j(not_zero, &call_runtime);
+        } else {
+          // Check if result fits in a smi.
+          __ cmp(eax, 0xc0000000);
+          __ j(negative, &non_smi_result);
+        }
+        // Tag smi result and return.
+        __ SmiTag(eax);
+        GenerateReturn(masm);
+
+        // All ops except SHR return a signed int32 that we load in
+        // a HeapNumber.
+        if (op_ != Token::SHR) {
+          __ bind(&non_smi_result);
+          // Allocate a heap number if needed.
+          __ mov(ebx, Operand(eax));  // ebx: result
+          Label skip_allocation;
+          switch (mode_) {
+            case OVERWRITE_LEFT:
+            case OVERWRITE_RIGHT:
+              // If the operand was an object, we skip the
+              // allocation of a heap number.
+              __ mov(eax, Operand(esp, mode_ == OVERWRITE_RIGHT ?
+                                  1 * kPointerSize : 2 * kPointerSize));
+              __ test(eax, Immediate(kSmiTagMask));
+              __ j(not_zero, &skip_allocation, not_taken);
+              // Fall through!
+            case NO_OVERWRITE:
+              __ AllocateHeapNumber(eax, ecx, edx, &call_runtime);
+              __ bind(&skip_allocation);
+              break;
+            default: UNREACHABLE();
+          }
+          // Store the result in the HeapNumber and return.
+          if (CpuFeatures::IsSupported(SSE2)) {
+            CpuFeatures::Scope use_sse2(SSE2);
+            __ cvtsi2sd(xmm0, Operand(ebx));
+            __ movdbl(FieldOperand(eax, HeapNumber::kValueOffset), xmm0);
+          } else {
+            __ mov(Operand(esp, 1 * kPointerSize), ebx);
+            __ fild_s(Operand(esp, 1 * kPointerSize));
+            __ fstp_d(FieldOperand(eax, HeapNumber::kValueOffset));
+          }
+          GenerateReturn(masm);
+        }
+        break;
+      }
+      default: UNREACHABLE(); break;
+    }
+  }
+
+  // If all else fails, use the runtime system to get the correct
+  // result. If arguments was passed in registers now place them on the
+  // stack in the correct order below the return address.
+  __ bind(&call_runtime);
+  if (HasArgsInRegisters()) {
+    GenerateRegisterArgsPush(masm);
+  }
+
+  switch (op_) {
+    case Token::ADD: {
+      // Test for string arguments before calling runtime.
+      Label not_strings, not_string1, string1, string1_smi2;
+
+      // If this stub has already generated FP-specific code then the arguments
+      // are already in edx, eax
+      if (!ShouldGenerateFPCode() && !HasArgsInRegisters()) {
+        GenerateLoadArguments(masm);
+      }
+
+      // Registers containing left and right operands respectively.
+      Register lhs, rhs;
+      if (HasArgsReversed()) {
+        lhs = eax;
+        rhs = edx;
+      } else {
+        lhs = edx;
+        rhs = eax;
+      }
+
+      // Test if first argument is a string.
+      __ test(lhs, Immediate(kSmiTagMask));
+      __ j(zero, &not_string1);
+      __ CmpObjectType(lhs, FIRST_NONSTRING_TYPE, ecx);
+      __ j(above_equal, &not_string1);
+
+      // First argument is a string, test second.
+      __ test(rhs, Immediate(kSmiTagMask));
+      __ j(zero, &string1_smi2);
+      __ CmpObjectType(rhs, FIRST_NONSTRING_TYPE, ecx);
+      __ j(above_equal, &string1);
+
+      // First and second argument are strings. Jump to the string add stub.
+      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, rhs, edi, ebx, ecx, true, &string1);
+
+      // Replace second argument on stack and tailcall string add stub to make
+      // the result.
+      __ mov(Operand(esp, 1 * kPointerSize), edi);
+      __ TailCallStub(&string_add_stub);
+
+      // Only first argument is a string.
+      __ bind(&string1);
+      __ InvokeBuiltin(Builtins::STRING_ADD_LEFT, JUMP_FUNCTION);
+
+      // First argument was not a string, test second.
+      __ bind(&not_string1);
+      __ test(rhs, Immediate(kSmiTagMask));
+      __ j(zero, &not_strings);
+      __ CmpObjectType(rhs, FIRST_NONSTRING_TYPE, ecx);
+      __ j(above_equal, &not_strings);
+
+      // Only second argument is a string.
+      __ InvokeBuiltin(Builtins::STRING_ADD_RIGHT, JUMP_FUNCTION);
+
+      __ bind(&not_strings);
+      // Neither argument is a string.
+      __ InvokeBuiltin(Builtins::ADD, JUMP_FUNCTION);
+      break;
+    }
+    case Token::SUB:
+      __ InvokeBuiltin(Builtins::SUB, JUMP_FUNCTION);
+      break;
+    case Token::MUL:
+      __ InvokeBuiltin(Builtins::MUL, JUMP_FUNCTION);
+      break;
+    case Token::DIV:
+      __ InvokeBuiltin(Builtins::DIV, JUMP_FUNCTION);
+      break;
+    case Token::MOD:
+      __ InvokeBuiltin(Builtins::MOD, JUMP_FUNCTION);
+      break;
+    case Token::BIT_OR:
+      __ InvokeBuiltin(Builtins::BIT_OR, JUMP_FUNCTION);
+      break;
+    case Token::BIT_AND:
+      __ InvokeBuiltin(Builtins::BIT_AND, JUMP_FUNCTION);
+      break;
+    case Token::BIT_XOR:
+      __ InvokeBuiltin(Builtins::BIT_XOR, JUMP_FUNCTION);
+      break;
+    case Token::SAR:
+      __ InvokeBuiltin(Builtins::SAR, JUMP_FUNCTION);
+      break;
+    case Token::SHL:
+      __ InvokeBuiltin(Builtins::SHL, JUMP_FUNCTION);
+      break;
+    case Token::SHR:
+      __ InvokeBuiltin(Builtins::SHR, JUMP_FUNCTION);
+      break;
+    default:
+      UNREACHABLE();
+  }
+}
+
+
+void GenericBinaryOpStub::GenerateHeapResultAllocation(MacroAssembler* masm,
+                                                       Label* alloc_failure) {
+  Label skip_allocation;
+  OverwriteMode mode = mode_;
+  if (HasArgsReversed()) {
+    if (mode == OVERWRITE_RIGHT) {
+      mode = OVERWRITE_LEFT;
+    } else if (mode == OVERWRITE_LEFT) {
+      mode = OVERWRITE_RIGHT;
+    }
+  }
+  switch (mode) {
+    case OVERWRITE_LEFT: {
+      // If the argument in edx is already an object, we skip the
+      // allocation of a heap number.
+      __ test(edx, Immediate(kSmiTagMask));
+      __ j(not_zero, &skip_allocation, not_taken);
+      // Allocate a heap number for the result. Keep eax and edx intact
+      // for the possible runtime call.
+      __ AllocateHeapNumber(ebx, ecx, no_reg, alloc_failure);
+      // Now edx can be overwritten losing one of the arguments as we are
+      // now done and will not need it any more.
+      __ mov(edx, Operand(ebx));
+      __ bind(&skip_allocation);
+      // Use object in edx as a result holder
+      __ mov(eax, Operand(edx));
+      break;
+    }
+    case OVERWRITE_RIGHT:
+      // If the argument in eax is already an object, we skip the
+      // allocation of a heap number.
+      __ test(eax, Immediate(kSmiTagMask));
+      __ j(not_zero, &skip_allocation, not_taken);
+      // Fall through!
+    case NO_OVERWRITE:
+      // Allocate a heap number for the result. Keep eax and edx intact
+      // for the possible runtime call.
+      __ AllocateHeapNumber(ebx, ecx, no_reg, alloc_failure);
+      // Now eax can be overwritten losing one of the arguments as we are
+      // now done and will not need it any more.
+      __ mov(eax, ebx);
+      __ bind(&skip_allocation);
+      break;
+    default: UNREACHABLE();
+  }
+}
+
+
+void GenericBinaryOpStub::GenerateLoadArguments(MacroAssembler* masm) {
+  // If arguments are not passed in registers read them from the stack.
+  ASSERT(!HasArgsInRegisters());
+  __ mov(eax, Operand(esp, 1 * kPointerSize));
+  __ mov(edx, Operand(esp, 2 * kPointerSize));
+}
+
+
+void GenericBinaryOpStub::GenerateReturn(MacroAssembler* masm) {
+  // If arguments are not passed in registers remove them from the stack before
+  // returning.
+  if (!HasArgsInRegisters()) {
+    __ ret(2 * kPointerSize);  // Remove both operands
+  } else {
+    __ ret(0);
+  }
+}
+
+
+void GenericBinaryOpStub::GenerateRegisterArgsPush(MacroAssembler* masm) {
+  ASSERT(HasArgsInRegisters());
+  __ pop(ecx);
+  if (HasArgsReversed()) {
+    __ push(eax);
+    __ push(edx);
+  } else {
+    __ push(edx);
+    __ push(eax);
+  }
+  __ push(ecx);
+}
+
+
+void GenericBinaryOpStub::GenerateTypeTransition(MacroAssembler* masm) {
+  // Ensure the operands are on the stack.
+  if (HasArgsInRegisters()) {
+    GenerateRegisterArgsPush(masm);
+  }
+
+  __ pop(ecx);  // Save return address.
+
+  // Left and right arguments are now on top.
+  // Push this stub's key. Although the operation and the type info are
+  // encoded into the key, the encoding is opaque, so push them too.
+  __ push(Immediate(Smi::FromInt(MinorKey())));
+  __ push(Immediate(Smi::FromInt(op_)));
+  __ push(Immediate(Smi::FromInt(runtime_operands_type_)));
+
+  __ push(ecx);  // Push return address.
+
+  // Patch the caller to an appropriate specialized stub and return the
+  // operation result to the caller of the stub.
+  __ 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) {
+  // Input on stack:
+  // esp[4]: argument (should be number).
+  // esp[0]: return address.
+  // Test that eax is a number.
+  Label runtime_call;
+  Label runtime_call_clear_stack;
+  Label input_not_smi;
+  Label loaded;
+  __ mov(eax, Operand(esp, kPointerSize));
+  __ test(eax, Immediate(kSmiTagMask));
+  __ j(not_zero, &input_not_smi);
+  // Input is a smi. Untag and load it onto the FPU stack.
+  // Then load the low and high words of the double into ebx, edx.
+  STATIC_ASSERT(kSmiTagSize == 1);
+  __ sar(eax, 1);
+  __ sub(Operand(esp), Immediate(2 * kPointerSize));
+  __ mov(Operand(esp, 0), eax);
+  __ fild_s(Operand(esp, 0));
+  __ fst_d(Operand(esp, 0));
+  __ pop(edx);
+  __ pop(ebx);
+  __ jmp(&loaded);
+  __ bind(&input_not_smi);
+  // Check if input is a HeapNumber.
+  __ mov(ebx, FieldOperand(eax, HeapObject::kMapOffset));
+  __ cmp(Operand(ebx), Immediate(Factory::heap_number_map()));
+  __ j(not_equal, &runtime_call);
+  // Input is a HeapNumber. Push it on the FPU stack and load its
+  // low and high words into ebx, edx.
+  __ fld_d(FieldOperand(eax, HeapNumber::kValueOffset));
+  __ mov(edx, FieldOperand(eax, HeapNumber::kExponentOffset));
+  __ mov(ebx, FieldOperand(eax, HeapNumber::kMantissaOffset));
+
+  __ bind(&loaded);
+  // ST[0] == double value
+  // ebx = low 32 bits of double value
+  // edx = 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);
+  __ mov(ecx, ebx);
+  __ xor_(ecx, Operand(edx));
+  __ mov(eax, ecx);
+  __ sar(eax, 16);
+  __ xor_(ecx, Operand(eax));
+  __ mov(eax, ecx);
+  __ sar(eax, 8);
+  __ xor_(ecx, Operand(eax));
+  ASSERT(IsPowerOf2(TranscendentalCache::kCacheSize));
+  __ and_(Operand(ecx), Immediate(TranscendentalCache::kCacheSize - 1));
+
+  // ST[0] == double value.
+  // ebx = low 32 bits of double value.
+  // edx = high 32 bits of double value.
+  // ecx = TranscendentalCache::hash(double value).
+  __ mov(eax,
+         Immediate(ExternalReference::transcendental_cache_array_address()));
+  // Eax points to cache array.
+  __ mov(eax, Operand(eax, type_ * sizeof(TranscendentalCache::caches_[0])));
+  // Eax points to the cache for the type type_.
+  // If NULL, the cache hasn't been initialized yet, so go through runtime.
+  __ test(eax, Operand(eax));
+  __ j(zero, &runtime_call_clear_stack);
+#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 ecx'th entry in the cache, i.e., &eax[ecx*12].
+  __ lea(ecx, Operand(ecx, ecx, times_2, 0));
+  __ lea(ecx, Operand(eax, ecx, times_4, 0));
+  // Check if cache matches: Double value is stored in uint32_t[2] array.
+  Label cache_miss;
+  __ cmp(ebx, Operand(ecx, 0));
+  __ j(not_equal, &cache_miss);
+  __ cmp(edx, Operand(ecx, kIntSize));
+  __ j(not_equal, &cache_miss);
+  // Cache hit!
+  __ mov(eax, Operand(ecx, 2 * kIntSize));
+  __ fstp(0);
+  __ ret(kPointerSize);
+
+  __ bind(&cache_miss);
+  // Update cache with new value.
+  // We are short on registers, so use no_reg as scratch.
+  // This gives slightly larger code.
+  __ AllocateHeapNumber(eax, edi, no_reg, &runtime_call_clear_stack);
+  GenerateOperation(masm);
+  __ mov(Operand(ecx, 0), ebx);
+  __ mov(Operand(ecx, kIntSize), edx);
+  __ mov(Operand(ecx, 2 * kIntSize), eax);
+  __ fstp_d(FieldOperand(eax, HeapNumber::kValueOffset));
+  __ ret(kPointerSize);
+
+  __ bind(&runtime_call_clear_stack);
+  __ fstp(0);
+  __ 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 TranscendentalCacheStub::GenerateOperation(MacroAssembler* masm) {
+  // Only free register is edi.
+  Label done;
+  ASSERT(type_ == TranscendentalCache::SIN ||
+         type_ == TranscendentalCache::COS);
+  // More transcendental types can be added later.
+
+  // Both fsin and fcos require arguments in the range +/-2^63 and
+  // return NaN for infinities and NaN. They can share all code except
+  // the actual fsin/fcos operation.
+  Label in_range;
+  // If argument is outside the range -2^63..2^63, fsin/cos doesn't
+  // work. We must reduce it to the appropriate range.
+  __ mov(edi, edx);
+  __ and_(Operand(edi), Immediate(0x7ff00000));  // Exponent only.
+  int supported_exponent_limit =
+      (63 + HeapNumber::kExponentBias) << HeapNumber::kExponentShift;
+  __ cmp(Operand(edi), Immediate(supported_exponent_limit));
+  __ j(below, &in_range, taken);
+  // Check for infinity and NaN. Both return NaN for sin.
+  __ cmp(Operand(edi), Immediate(0x7ff00000));
+  Label non_nan_result;
+  __ j(not_equal, &non_nan_result, taken);
+  // Input is +/-Infinity or NaN. Result is NaN.
+  __ fstp(0);
+  // NaN is represented by 0x7ff8000000000000.
+  __ push(Immediate(0x7ff80000));
+  __ push(Immediate(0));
+  __ fld_d(Operand(esp, 0));
+  __ add(Operand(esp), Immediate(2 * kPointerSize));
+  __ jmp(&done);
+
+  __ bind(&non_nan_result);
+
+  // Use fpmod to restrict argument to the range +/-2*PI.
+  __ mov(edi, eax);  // Save eax before using fnstsw_ax.
+  __ fldpi();
+  __ fadd(0);
+  __ fld(1);
+  // FPU Stack: input, 2*pi, input.
+  {
+    Label no_exceptions;
+    __ fwait();
+    __ fnstsw_ax();
+    // Clear if Illegal Operand or Zero Division exceptions are set.
+    __ test(Operand(eax), Immediate(5));
+    __ j(zero, &no_exceptions);
+    __ fnclex();
+    __ bind(&no_exceptions);
+  }
+
+  // Compute st(0) % st(1)
+  {
+    Label partial_remainder_loop;
+    __ bind(&partial_remainder_loop);
+    __ fprem1();
+    __ fwait();
+    __ fnstsw_ax();
+    __ test(Operand(eax), Immediate(0x400 /* C2 */));
+    // If C2 is set, computation only has partial result. Loop to
+    // continue computation.
+    __ j(not_zero, &partial_remainder_loop);
+  }
+  // FPU Stack: input, 2*pi, input % 2*pi
+  __ fstp(2);
+  __ fstp(0);
+  __ mov(eax, edi);  // Restore eax (allocated HeapNumber pointer).
+
+  // FPU Stack: input % 2*pi
+  __ bind(&in_range);
+  switch (type_) {
+    case TranscendentalCache::SIN:
+      __ fsin();
+      break;
+    case TranscendentalCache::COS:
+      __ fcos();
+      break;
+    default:
+      UNREACHABLE();
+  }
+  __ bind(&done);
+}
+
+
+// Get the integer part of a heap number.  Surprisingly, all this bit twiddling
+// is faster than using the built-in instructions on floating point registers.
+// Trashes edi and ebx.  Dest is ecx.  Source cannot be ecx or one of the
+// trashed registers.
+void IntegerConvert(MacroAssembler* masm,
+                    Register source,
+                    TypeInfo type_info,
+                    bool use_sse3,
+                    Label* conversion_failure) {
+  ASSERT(!source.is(ecx) && !source.is(edi) && !source.is(ebx));
+  Label done, right_exponent, normal_exponent;
+  Register scratch = ebx;
+  Register scratch2 = edi;
+  if (type_info.IsInteger32() && CpuFeatures::IsEnabled(SSE2)) {
+    CpuFeatures::Scope scope(SSE2);
+    __ cvttsd2si(ecx, FieldOperand(source, HeapNumber::kValueOffset));
+    return;
+  }
+  if (!type_info.IsInteger32() || !use_sse3) {
+    // Get exponent word.
+    __ mov(scratch, FieldOperand(source, HeapNumber::kExponentOffset));
+    // Get exponent alone in scratch2.
+    __ mov(scratch2, scratch);
+    __ and_(scratch2, HeapNumber::kExponentMask);
+  }
+  if (use_sse3) {
+    CpuFeatures::Scope scope(SSE3);
+    if (!type_info.IsInteger32()) {
+      // Check whether the exponent is too big for a 64 bit signed integer.
+      static const uint32_t kTooBigExponent =
+          (HeapNumber::kExponentBias + 63) << HeapNumber::kExponentShift;
+      __ cmp(Operand(scratch2), Immediate(kTooBigExponent));
+      __ j(greater_equal, conversion_failure);
+    }
+    // Load x87 register with heap number.
+    __ fld_d(FieldOperand(source, HeapNumber::kValueOffset));
+    // Reserve space for 64 bit answer.
+    __ sub(Operand(esp), Immediate(sizeof(uint64_t)));  // Nolint.
+    // Do conversion, which cannot fail because we checked the exponent.
+    __ fisttp_d(Operand(esp, 0));
+    __ mov(ecx, Operand(esp, 0));  // Load low word of answer into ecx.
+    __ add(Operand(esp), Immediate(sizeof(uint64_t)));  // Nolint.
+  } else {
+    // Load ecx with zero.  We use this either for the final shift or
+    // for the answer.
+    __ xor_(ecx, Operand(ecx));
+    // Check whether the exponent matches a 32 bit signed int that cannot be
+    // represented by a Smi.  A non-smi 32 bit 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) << HeapNumber::kExponentShift;
+    __ cmp(Operand(scratch2), Immediate(non_smi_exponent));
+    // If we have a match of the int32-but-not-Smi exponent then skip some
+    // logic.
+    __ j(equal, &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.
+    __ j(less, &normal_exponent);
+
+    {
+      // Handle a big exponent.  The only reason we have this code is that the
+      // >>> operator has a tendency to generate numbers with an exponent of 31.
+      const uint32_t big_non_smi_exponent =
+          (HeapNumber::kExponentBias + 31) << HeapNumber::kExponentShift;
+      __ cmp(Operand(scratch2), Immediate(big_non_smi_exponent));
+      __ j(not_equal, conversion_failure);
+      // We have the big exponent, typically from >>>.  This means the number is
+      // in the range 2^31 to 2^32 - 1.  Get the top bits of the mantissa.
+      __ mov(scratch2, scratch);
+      __ and_(scratch2, HeapNumber::kMantissaMask);
+      // Put back the implicit 1.
+      __ or_(scratch2, 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 use the full unsigned range so we subtract 1 bit from the
+      // shift distance.
+      const int big_shift_distance = HeapNumber::kNonMantissaBitsInTopWord - 1;
+      __ shl(scratch2, big_shift_distance);
+      // Get the second half of the double.
+      __ mov(ecx, FieldOperand(source, HeapNumber::kMantissaOffset));
+      // Shift down 21 bits to get the most significant 11 bits or the low
+      // mantissa word.
+      __ shr(ecx, 32 - big_shift_distance);
+      __ or_(ecx, Operand(scratch2));
+      // We have the answer in ecx, but we may need to negate it.
+      __ test(scratch, Operand(scratch));
+      __ j(positive, &done);
+      __ neg(ecx);
+      __ jmp(&done);
+    }
+
+    __ bind(&normal_exponent);
+    // Exponent word in scratch, exponent part of exponent word in scratch2.
+    // Zero in ecx.
+    // 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) << HeapNumber::kExponentShift;
+    __ sub(Operand(scratch2), Immediate(zero_exponent));
+    // ecx already has a Smi zero.
+    __ j(less, &done);
+
+    // We have a shifted exponent between 0 and 30 in scratch2.
+    __ shr(scratch2, HeapNumber::kExponentShift);
+    __ mov(ecx, Immediate(30));
+    __ sub(ecx, Operand(scratch2));
+
+    __ bind(&right_exponent);
+    // Here ecx is the shift, scratch is the exponent word.
+    // Get the top bits of the mantissa.
+    __ and_(scratch, HeapNumber::kMantissaMask);
+    // Put back the implicit 1.
+    __ or_(scratch, 1 << HeapNumber::kExponentShift);
+    // Shift up the mantissa bits to take up the space the exponent used to
+    // take. We have kExponentShift + 1 significant bits int he low end of the
+    // word.  Shift them to the top bits.
+    const int shift_distance = HeapNumber::kNonMantissaBitsInTopWord - 2;
+    __ shl(scratch, shift_distance);
+    // 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.
+    __ mov(scratch2, FieldOperand(source, HeapNumber::kMantissaOffset));
+    // Shift down 22 bits to get the most significant 10 bits or the low
+    // mantissa word.
+    __ shr(scratch2, 32 - shift_distance);
+    __ or_(scratch2, Operand(scratch));
+    // Move down according to the exponent.
+    __ shr_cl(scratch2);
+    // Now the unsigned answer is in scratch2.  We need to move it to ecx and
+    // we may need to fix the sign.
+    Label negative;
+    __ xor_(ecx, Operand(ecx));
+    __ cmp(ecx, FieldOperand(source, HeapNumber::kExponentOffset));
+    __ j(greater, &negative);
+    __ mov(ecx, scratch2);
+    __ jmp(&done);
+    __ bind(&negative);
+    __ sub(ecx, Operand(scratch2));
+    __ bind(&done);
+  }
+}
+
+
+// Input: edx, eax are the left and right objects of a bit op.
+// Output: eax, ecx are left and right integers for a bit op.
+void FloatingPointHelper::LoadNumbersAsIntegers(MacroAssembler* masm,
+                                                TypeInfo type_info,
+                                                bool use_sse3,
+                                                Label* conversion_failure) {
+  // Check float operands.
+  Label arg1_is_object, check_undefined_arg1;
+  Label arg2_is_object, check_undefined_arg2;
+  Label load_arg2, done;
+
+  if (!type_info.IsDouble()) {
+    if (!type_info.IsSmi()) {
+      __ test(edx, Immediate(kSmiTagMask));
+      __ j(not_zero, &arg1_is_object);
+    } else {
+      if (FLAG_debug_code) __ AbortIfNotSmi(edx);
+    }
+    __ SmiUntag(edx);
+    __ jmp(&load_arg2);
+  }
+
+  __ bind(&arg1_is_object);
+
+  // Get the untagged integer version of the edx heap number in ecx.
+  IntegerConvert(masm, edx, type_info, use_sse3, conversion_failure);
+  __ mov(edx, ecx);
+
+  // Here edx has the untagged integer, eax has a Smi or a heap number.
+  __ bind(&load_arg2);
+  if (!type_info.IsDouble()) {
+    // Test if arg2 is a Smi.
+    if (!type_info.IsSmi()) {
+      __ test(eax, Immediate(kSmiTagMask));
+      __ j(not_zero, &arg2_is_object);
+    } else {
+      if (FLAG_debug_code) __ AbortIfNotSmi(eax);
+    }
+    __ SmiUntag(eax);
+    __ mov(ecx, eax);
+    __ jmp(&done);
+  }
+
+  __ bind(&arg2_is_object);
+
+  // Get the untagged integer version of the eax heap number in ecx.
+  IntegerConvert(masm, eax, type_info, use_sse3, conversion_failure);
+  __ bind(&done);
+  __ mov(eax, edx);
+}
+
+
+// Input: edx, eax are the left and right objects of a bit op.
+// Output: eax, ecx are left and right integers for a bit op.
+void FloatingPointHelper::LoadUnknownsAsIntegers(MacroAssembler* masm,
+                                                 bool use_sse3,
+                                                 Label* conversion_failure) {
+  // Check float operands.
+  Label arg1_is_object, check_undefined_arg1;
+  Label arg2_is_object, check_undefined_arg2;
+  Label load_arg2, done;
+
+  // Test if arg1 is a Smi.
+  __ test(edx, Immediate(kSmiTagMask));
+  __ j(not_zero, &arg1_is_object);
+
+  __ SmiUntag(edx);
+  __ jmp(&load_arg2);
+
+  // If the argument is undefined it converts to zero (ECMA-262, section 9.5).
+  __ bind(&check_undefined_arg1);
+  __ cmp(edx, Factory::undefined_value());
+  __ j(not_equal, conversion_failure);
+  __ mov(edx, Immediate(0));
+  __ jmp(&load_arg2);
+
+  __ bind(&arg1_is_object);
+  __ mov(ebx, FieldOperand(edx, HeapObject::kMapOffset));
+  __ cmp(ebx, Factory::heap_number_map());
+  __ j(not_equal, &check_undefined_arg1);
+
+  // Get the untagged integer version of the edx heap number in ecx.
+  IntegerConvert(masm,
+                 edx,
+                 TypeInfo::Unknown(),
+                 use_sse3,
+                 conversion_failure);
+  __ mov(edx, ecx);
+
+  // Here edx has the untagged integer, eax has a Smi or a heap number.
+  __ bind(&load_arg2);
+
+  // Test if arg2 is a Smi.
+  __ test(eax, Immediate(kSmiTagMask));
+  __ j(not_zero, &arg2_is_object);
+
+  __ SmiUntag(eax);
+  __ mov(ecx, eax);
+  __ jmp(&done);
+
+  // If the argument is undefined it converts to zero (ECMA-262, section 9.5).
+  __ bind(&check_undefined_arg2);
+  __ cmp(eax, Factory::undefined_value());
+  __ j(not_equal, conversion_failure);
+  __ mov(ecx, Immediate(0));
+  __ jmp(&done);
+
+  __ bind(&arg2_is_object);
+  __ mov(ebx, FieldOperand(eax, HeapObject::kMapOffset));
+  __ cmp(ebx, Factory::heap_number_map());
+  __ j(not_equal, &check_undefined_arg2);
+
+  // Get the untagged integer version of the eax heap number in ecx.
+  IntegerConvert(masm,
+                 eax,
+                 TypeInfo::Unknown(),
+                 use_sse3,
+                 conversion_failure);
+  __ bind(&done);
+  __ mov(eax, edx);
+}
+
+
+void FloatingPointHelper::LoadAsIntegers(MacroAssembler* masm,
+                                         TypeInfo type_info,
+                                         bool use_sse3,
+                                         Label* conversion_failure) {
+  if (type_info.IsNumber()) {
+    LoadNumbersAsIntegers(masm, type_info, use_sse3, conversion_failure);
+  } else {
+    LoadUnknownsAsIntegers(masm, use_sse3, conversion_failure);
+  }
+}
+
+
+void FloatingPointHelper::LoadFloatOperand(MacroAssembler* masm,
+                                           Register number) {
+  Label load_smi, done;
+
+  __ test(number, Immediate(kSmiTagMask));
+  __ j(zero, &load_smi, not_taken);
+  __ fld_d(FieldOperand(number, HeapNumber::kValueOffset));
+  __ jmp(&done);
+
+  __ bind(&load_smi);
+  __ SmiUntag(number);
+  __ push(number);
+  __ fild_s(Operand(esp, 0));
+  __ pop(number);
+
+  __ bind(&done);
+}
+
+
+void FloatingPointHelper::LoadSSE2Operands(MacroAssembler* masm) {
+  Label load_smi_edx, load_eax, load_smi_eax, done;
+  // Load operand in edx into xmm0.
+  __ test(edx, Immediate(kSmiTagMask));
+  __ j(zero, &load_smi_edx, not_taken);  // Argument in edx is a smi.
+  __ movdbl(xmm0, FieldOperand(edx, HeapNumber::kValueOffset));
+
+  __ bind(&load_eax);
+  // Load operand in eax into xmm1.
+  __ test(eax, Immediate(kSmiTagMask));
+  __ j(zero, &load_smi_eax, not_taken);  // Argument in eax is a smi.
+  __ movdbl(xmm1, FieldOperand(eax, HeapNumber::kValueOffset));
+  __ jmp(&done);
+
+  __ bind(&load_smi_edx);
+  __ SmiUntag(edx);  // Untag smi before converting to float.
+  __ cvtsi2sd(xmm0, Operand(edx));
+  __ SmiTag(edx);  // Retag smi for heap number overwriting test.
+  __ jmp(&load_eax);
+
+  __ bind(&load_smi_eax);
+  __ SmiUntag(eax);  // Untag smi before converting to float.
+  __ cvtsi2sd(xmm1, Operand(eax));
+  __ SmiTag(eax);  // Retag smi for heap number overwriting test.
+
+  __ bind(&done);
+}
+
+
+void FloatingPointHelper::LoadSSE2Operands(MacroAssembler* masm,
+                                           Label* not_numbers) {
+  Label load_smi_edx, load_eax, load_smi_eax, load_float_eax, done;
+  // Load operand in edx into xmm0, or branch to not_numbers.
+  __ test(edx, Immediate(kSmiTagMask));
+  __ j(zero, &load_smi_edx, not_taken);  // Argument in edx is a smi.
+  __ cmp(FieldOperand(edx, HeapObject::kMapOffset), Factory::heap_number_map());
+  __ j(not_equal, not_numbers);  // Argument in edx is not a number.
+  __ movdbl(xmm0, FieldOperand(edx, HeapNumber::kValueOffset));
+  __ bind(&load_eax);
+  // Load operand in eax into xmm1, or branch to not_numbers.
+  __ test(eax, Immediate(kSmiTagMask));
+  __ j(zero, &load_smi_eax, not_taken);  // Argument in eax is a smi.
+  __ cmp(FieldOperand(eax, HeapObject::kMapOffset), Factory::heap_number_map());
+  __ j(equal, &load_float_eax);
+  __ jmp(not_numbers);  // Argument in eax is not a number.
+  __ bind(&load_smi_edx);
+  __ SmiUntag(edx);  // Untag smi before converting to float.
+  __ cvtsi2sd(xmm0, Operand(edx));
+  __ SmiTag(edx);  // Retag smi for heap number overwriting test.
+  __ jmp(&load_eax);
+  __ bind(&load_smi_eax);
+  __ SmiUntag(eax);  // Untag smi before converting to float.
+  __ cvtsi2sd(xmm1, Operand(eax));
+  __ SmiTag(eax);  // Retag smi for heap number overwriting test.
+  __ jmp(&done);
+  __ bind(&load_float_eax);
+  __ movdbl(xmm1, FieldOperand(eax, HeapNumber::kValueOffset));
+  __ bind(&done);
+}
+
+
+void FloatingPointHelper::LoadSSE2Smis(MacroAssembler* masm,
+                                       Register scratch) {
+  const Register left = edx;
+  const Register right = eax;
+  __ mov(scratch, left);
+  ASSERT(!scratch.is(right));  // We're about to clobber scratch.
+  __ SmiUntag(scratch);
+  __ cvtsi2sd(xmm0, Operand(scratch));
+
+  __ mov(scratch, right);
+  __ SmiUntag(scratch);
+  __ cvtsi2sd(xmm1, Operand(scratch));
+}
+
+
+void FloatingPointHelper::LoadFloatOperands(MacroAssembler* masm,
+                                            Register scratch,
+                                            ArgLocation arg_location) {
+  Label load_smi_1, load_smi_2, done_load_1, done;
+  if (arg_location == ARGS_IN_REGISTERS) {
+    __ mov(scratch, edx);
+  } else {
+    __ mov(scratch, Operand(esp, 2 * kPointerSize));
+  }
+  __ test(scratch, Immediate(kSmiTagMask));
+  __ j(zero, &load_smi_1, not_taken);
+  __ fld_d(FieldOperand(scratch, HeapNumber::kValueOffset));
+  __ bind(&done_load_1);
+
+  if (arg_location == ARGS_IN_REGISTERS) {
+    __ mov(scratch, eax);
+  } else {
+    __ mov(scratch, Operand(esp, 1 * kPointerSize));
+  }
+  __ test(scratch, Immediate(kSmiTagMask));
+  __ j(zero, &load_smi_2, not_taken);
+  __ fld_d(FieldOperand(scratch, HeapNumber::kValueOffset));
+  __ jmp(&done);
+
+  __ bind(&load_smi_1);
+  __ SmiUntag(scratch);
+  __ push(scratch);
+  __ fild_s(Operand(esp, 0));
+  __ pop(scratch);
+  __ jmp(&done_load_1);
+
+  __ bind(&load_smi_2);
+  __ SmiUntag(scratch);
+  __ push(scratch);
+  __ fild_s(Operand(esp, 0));
+  __ pop(scratch);
+
+  __ bind(&done);
+}
+
+
+void FloatingPointHelper::LoadFloatSmis(MacroAssembler* masm,
+                                        Register scratch) {
+  const Register left = edx;
+  const Register right = eax;
+  __ mov(scratch, left);
+  ASSERT(!scratch.is(right));  // We're about to clobber scratch.
+  __ SmiUntag(scratch);
+  __ push(scratch);
+  __ fild_s(Operand(esp, 0));
+
+  __ mov(scratch, right);
+  __ SmiUntag(scratch);
+  __ mov(Operand(esp, 0), scratch);
+  __ fild_s(Operand(esp, 0));
+  __ pop(scratch);
+}
+
+
+void FloatingPointHelper::CheckFloatOperands(MacroAssembler* masm,
+                                             Label* non_float,
+                                             Register scratch) {
+  Label test_other, done;
+  // Test if both operands are floats or smi -> scratch=k_is_float;
+  // Otherwise scratch = k_not_float.
+  __ test(edx, Immediate(kSmiTagMask));
+  __ j(zero, &test_other, not_taken);  // argument in edx is OK
+  __ mov(scratch, FieldOperand(edx, HeapObject::kMapOffset));
+  __ cmp(scratch, Factory::heap_number_map());
+  __ j(not_equal, non_float);  // argument in edx is not a number -> NaN
+
+  __ bind(&test_other);
+  __ test(eax, Immediate(kSmiTagMask));
+  __ j(zero, &done);  // argument in eax is OK
+  __ mov(scratch, FieldOperand(eax, HeapObject::kMapOffset));
+  __ cmp(scratch, Factory::heap_number_map());
+  __ j(not_equal, non_float);  // argument in eax is not a number -> NaN
+
+  // Fall-through: Both operands are numbers.
+  __ bind(&done);
+}
+
+
+void GenericUnaryOpStub::Generate(MacroAssembler* masm) {
+  Label slow, done;
+
+  if (op_ == Token::SUB) {
+    // Check whether the value is a smi.
+    Label try_float;
+    __ test(eax, Immediate(kSmiTagMask));
+    __ j(not_zero, &try_float, not_taken);
+
+    if (negative_zero_ == kStrictNegativeZero) {
+      // Go slow case if the value of the expression is zero
+      // to make sure that we switch between 0 and -0.
+      __ test(eax, Operand(eax));
+      __ j(zero, &slow, not_taken);
+    }
+
+    // The value of the expression is a smi that is not zero.  Try
+    // optimistic subtraction '0 - value'.
+    Label undo;
+    __ mov(edx, Operand(eax));
+    __ Set(eax, Immediate(0));
+    __ sub(eax, Operand(edx));
+    __ j(no_overflow, &done, taken);
+
+    // Restore eax and go slow case.
+    __ bind(&undo);
+    __ mov(eax, Operand(edx));
+    __ jmp(&slow);
+
+    // Try floating point case.
+    __ bind(&try_float);
+    __ mov(edx, FieldOperand(eax, HeapObject::kMapOffset));
+    __ cmp(edx, Factory::heap_number_map());
+    __ j(not_equal, &slow);
+    if (overwrite_ == UNARY_OVERWRITE) {
+      __ mov(edx, FieldOperand(eax, HeapNumber::kExponentOffset));
+      __ xor_(edx, HeapNumber::kSignMask);  // Flip sign.
+      __ mov(FieldOperand(eax, HeapNumber::kExponentOffset), edx);
+    } else {
+      __ mov(edx, Operand(eax));
+      // edx: operand
+      __ AllocateHeapNumber(eax, ebx, ecx, &undo);
+      // eax: allocated 'empty' number
+      __ mov(ecx, FieldOperand(edx, HeapNumber::kExponentOffset));
+      __ xor_(ecx, HeapNumber::kSignMask);  // Flip sign.
+      __ mov(FieldOperand(eax, HeapNumber::kExponentOffset), ecx);
+      __ mov(ecx, FieldOperand(edx, HeapNumber::kMantissaOffset));
+      __ mov(FieldOperand(eax, HeapNumber::kMantissaOffset), ecx);
+    }
+  } else if (op_ == Token::BIT_NOT) {
+    // Check if the operand is a heap number.
+    __ mov(edx, FieldOperand(eax, HeapObject::kMapOffset));
+    __ cmp(edx, Factory::heap_number_map());
+    __ j(not_equal, &slow, not_taken);
+
+    // Convert the heap number in eax to an untagged integer in ecx.
+    IntegerConvert(masm,
+                   eax,
+                   TypeInfo::Unknown(),
+                   CpuFeatures::IsSupported(SSE3),
+                   &slow);
+
+    // Do the bitwise operation and check if the result fits in a smi.
+    Label try_float;
+    __ not_(ecx);
+    __ cmp(ecx, 0xc0000000);
+    __ j(sign, &try_float, not_taken);
+
+    // Tag the result as a smi and we're done.
+    STATIC_ASSERT(kSmiTagSize == 1);
+    __ lea(eax, Operand(ecx, times_2, kSmiTag));
+    __ jmp(&done);
+
+    // Try to store the result in a heap number.
+    __ bind(&try_float);
+    if (overwrite_ == UNARY_NO_OVERWRITE) {
+      // Allocate a fresh heap number, but don't overwrite eax until
+      // we're sure we can do it without going through the slow case
+      // that needs the value in eax.
+      __ AllocateHeapNumber(ebx, edx, edi, &slow);
+      __ mov(eax, Operand(ebx));
+    }
+    if (CpuFeatures::IsSupported(SSE2)) {
+      CpuFeatures::Scope use_sse2(SSE2);
+      __ cvtsi2sd(xmm0, Operand(ecx));
+      __ movdbl(FieldOperand(eax, HeapNumber::kValueOffset), xmm0);
+    } else {
+      __ push(ecx);
+      __ fild_s(Operand(esp, 0));
+      __ pop(ecx);
+      __ fstp_d(FieldOperand(eax, HeapNumber::kValueOffset));
+    }
+  } else {
+    UNIMPLEMENTED();
+  }
+
+  // Return from the stub.
+  __ bind(&done);
+  __ StubReturn(1);
+
+  // Handle the slow case by jumping to the JavaScript builtin.
+  __ bind(&slow);
+  __ pop(ecx);  // pop return address.
+  __ push(eax);
+  __ push(ecx);  // push return address
+  switch (op_) {
+    case Token::SUB:
+      __ InvokeBuiltin(Builtins::UNARY_MINUS, JUMP_FUNCTION);
+      break;
+    case Token::BIT_NOT:
+      __ InvokeBuiltin(Builtins::BIT_NOT, JUMP_FUNCTION);
+      break;
+    default:
+      UNREACHABLE();
+  }
+}
+
+
+void ArgumentsAccessStub::GenerateReadElement(MacroAssembler* masm) {
+  // The key is in edx and the parameter count is in eax.
+
+  // The displacement is used for skipping the frame pointer on the
+  // stack. It is the offset of the last parameter (if any) relative
+  // to the frame pointer.
+  static const int kDisplacement = 1 * kPointerSize;
+
+  // Check that the key is a smi.
+  Label slow;
+  __ test(edx, Immediate(kSmiTagMask));
+  __ j(not_zero, &slow, not_taken);
+
+  // Check if the calling frame is an arguments adaptor frame.
+  Label adaptor;
+  __ mov(ebx, Operand(ebp, StandardFrameConstants::kCallerFPOffset));
+  __ mov(ecx, Operand(ebx, StandardFrameConstants::kContextOffset));
+  __ cmp(Operand(ecx), Immediate(Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR)));
+  __ j(equal, &adaptor);
+
+  // Check index against formal parameters count limit passed in
+  // through register eax. Use unsigned comparison to get negative
+  // check for free.
+  __ cmp(edx, Operand(eax));
+  __ j(above_equal, &slow, not_taken);
+
+  // Read the argument from the stack and return it.
+  STATIC_ASSERT(kSmiTagSize == 1);
+  STATIC_ASSERT(kSmiTag == 0);  // Shifting code depends on these.
+  __ lea(ebx, Operand(ebp, eax, times_2, 0));
+  __ neg(edx);
+  __ mov(eax, Operand(ebx, edx, times_2, kDisplacement));
+  __ ret(0);
+
+  // 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);
+  __ mov(ecx, Operand(ebx, ArgumentsAdaptorFrameConstants::kLengthOffset));
+  __ cmp(edx, Operand(ecx));
+  __ j(above_equal, &slow, not_taken);
+
+  // Read the argument from the stack and return it.
+  STATIC_ASSERT(kSmiTagSize == 1);
+  STATIC_ASSERT(kSmiTag == 0);  // Shifting code depends on these.
+  __ lea(ebx, Operand(ebx, ecx, times_2, 0));
+  __ neg(edx);
+  __ mov(eax, Operand(ebx, edx, times_2, kDisplacement));
+  __ ret(0);
+
+  // Slow-case: Handle non-smi or out-of-bounds access to arguments
+  // by calling the runtime system.
+  __ bind(&slow);
+  __ pop(ebx);  // Return address.
+  __ push(edx);
+  __ push(ebx);
+  __ TailCallRuntime(Runtime::kGetArgumentsProperty, 1, 1);
+}
+
+
+void ArgumentsAccessStub::GenerateNewObject(MacroAssembler* masm) {
+  // esp[0] : return address
+  // esp[4] : number of parameters
+  // esp[8] : receiver displacement
+  // esp[16] : function
+
+  // The displacement is used for skipping the return address and the
+  // frame pointer on the stack. It is the offset of the last
+  // parameter (if any) relative to the frame pointer.
+  static const int kDisplacement = 2 * kPointerSize;
+
+  // Check if the calling frame is an arguments adaptor frame.
+  Label adaptor_frame, try_allocate, runtime;
+  __ mov(edx, Operand(ebp, StandardFrameConstants::kCallerFPOffset));
+  __ mov(ecx, Operand(edx, StandardFrameConstants::kContextOffset));
+  __ cmp(Operand(ecx), Immediate(Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR)));
+  __ j(equal, &adaptor_frame);
+
+  // Get the length from the frame.
+  __ mov(ecx, Operand(esp, 1 * kPointerSize));
+  __ jmp(&try_allocate);
+
+  // Patch the arguments.length and the parameters pointer.
+  __ bind(&adaptor_frame);
+  __ mov(ecx, Operand(edx, ArgumentsAdaptorFrameConstants::kLengthOffset));
+  __ mov(Operand(esp, 1 * kPointerSize), ecx);
+  __ lea(edx, Operand(edx, ecx, times_2, kDisplacement));
+  __ mov(Operand(esp, 2 * kPointerSize), edx);
+
+  // Try the new space allocation. Start out with computing the size of
+  // the arguments object and the elements array.
+  Label add_arguments_object;
+  __ bind(&try_allocate);
+  __ test(ecx, Operand(ecx));
+  __ j(zero, &add_arguments_object);
+  __ lea(ecx, Operand(ecx, times_2, FixedArray::kHeaderSize));
+  __ bind(&add_arguments_object);
+  __ add(Operand(ecx), Immediate(Heap::kArgumentsObjectSize));
+
+  // Do the allocation of both objects in one go.
+  __ AllocateInNewSpace(ecx, eax, edx, ebx, &runtime, TAG_OBJECT);
+
+  // Get the arguments boilerplate from the current (global) context.
+  int offset = Context::SlotOffset(Context::ARGUMENTS_BOILERPLATE_INDEX);
+  __ mov(edi, Operand(esi, Context::SlotOffset(Context::GLOBAL_INDEX)));
+  __ mov(edi, FieldOperand(edi, GlobalObject::kGlobalContextOffset));
+  __ mov(edi, Operand(edi, offset));
+
+  // Copy the JS object part.
+  for (int i = 0; i < JSObject::kHeaderSize; i += kPointerSize) {
+    __ mov(ebx, FieldOperand(edi, i));
+    __ mov(FieldOperand(eax, i), ebx);
+  }
+
+  // Setup the callee in-object property.
+  STATIC_ASSERT(Heap::arguments_callee_index == 0);
+  __ mov(ebx, Operand(esp, 3 * kPointerSize));
+  __ mov(FieldOperand(eax, JSObject::kHeaderSize), ebx);
+
+  // Get the length (smi tagged) and set that as an in-object property too.
+  STATIC_ASSERT(Heap::arguments_length_index == 1);
+  __ mov(ecx, Operand(esp, 1 * kPointerSize));
+  __ mov(FieldOperand(eax, JSObject::kHeaderSize + kPointerSize), ecx);
+
+  // If there are no actual arguments, we're done.
+  Label done;
+  __ test(ecx, Operand(ecx));
+  __ j(zero, &done);
+
+  // Get the parameters pointer from the stack.
+  __ mov(edx, Operand(esp, 2 * kPointerSize));
+
+  // Setup the elements pointer in the allocated arguments object and
+  // initialize the header in the elements fixed array.
+  __ lea(edi, Operand(eax, Heap::kArgumentsObjectSize));
+  __ mov(FieldOperand(eax, JSObject::kElementsOffset), edi);
+  __ mov(FieldOperand(edi, FixedArray::kMapOffset),
+         Immediate(Factory::fixed_array_map()));
+  __ mov(FieldOperand(edi, FixedArray::kLengthOffset), ecx);
+  // Untag the length for the loop below.
+  __ SmiUntag(ecx);
+
+  // Copy the fixed array slots.
+  Label loop;
+  __ bind(&loop);
+  __ mov(ebx, Operand(edx, -1 * kPointerSize));  // Skip receiver.
+  __ mov(FieldOperand(edi, FixedArray::kHeaderSize), ebx);
+  __ add(Operand(edi), Immediate(kPointerSize));
+  __ sub(Operand(edx), Immediate(kPointerSize));
+  __ dec(ecx);
+  __ j(not_zero, &loop);
+
+  // Return and remove the on-stack parameters.
+  __ bind(&done);
+  __ ret(3 * kPointerSize);
+
+  // 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.
+  //  esp[0]: return address
+  //  esp[4]: last_match_info (expected JSArray)
+  //  esp[8]: previous index
+  //  esp[12]: subject string
+  //  esp[16]: JSRegExp object
+
+  static const int kLastMatchInfoOffset = 1 * kPointerSize;
+  static const int kPreviousIndexOffset = 2 * kPointerSize;
+  static const int kSubjectOffset = 3 * kPointerSize;
+  static const int kJSRegExpOffset = 4 * kPointerSize;
+
+  Label runtime, invoke_regexp;
+
+  // 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(ebx, Operand::StaticVariable(address_of_regexp_stack_memory_size));
+  __ test(ebx, Operand(ebx));
+  __ j(zero, &runtime, not_taken);
+
+  // Check that the first argument is a JSRegExp object.
+  __ mov(eax, Operand(esp, kJSRegExpOffset));
+  STATIC_ASSERT(kSmiTag == 0);
+  __ test(eax, Immediate(kSmiTagMask));
+  __ j(zero, &runtime);
+  __ CmpObjectType(eax, JS_REGEXP_TYPE, ecx);
+  __ j(not_equal, &runtime);
+  // Check that the RegExp has been compiled (data contains a fixed array).
+  __ mov(ecx, FieldOperand(eax, JSRegExp::kDataOffset));
+  if (FLAG_debug_code) {
+    __ test(ecx, Immediate(kSmiTagMask));
+    __ Check(not_zero, "Unexpected type for RegExp data, FixedArray expected");
+    __ CmpObjectType(ecx, FIXED_ARRAY_TYPE, ebx);
+    __ Check(equal, "Unexpected type for RegExp data, FixedArray expected");
+  }
+
+  // ecx: RegExp data (FixedArray)
+  // Check the type of the RegExp. Only continue if type is JSRegExp::IRREGEXP.
+  __ mov(ebx, FieldOperand(ecx, JSRegExp::kDataTagOffset));
+  __ cmp(Operand(ebx), Immediate(Smi::FromInt(JSRegExp::IRREGEXP)));
+  __ j(not_equal, &runtime);
+
+  // ecx: RegExp data (FixedArray)
+  // Check that the number of captures fit in the static offsets vector buffer.
+  __ mov(edx, FieldOperand(ecx, 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(Operand(edx), Immediate(2));  // edx was a smi.
+  // Check that the static offsets vector buffer is large enough.
+  __ cmp(edx, OffsetsVector::kStaticOffsetsVectorSize);
+  __ j(above, &runtime);
+
+  // ecx: RegExp data (FixedArray)
+  // edx: Number of capture registers
+  // Check that the second argument is a string.
+  __ mov(eax, Operand(esp, kSubjectOffset));
+  __ test(eax, Immediate(kSmiTagMask));
+  __ j(zero, &runtime);
+  Condition is_string = masm->IsObjectStringType(eax, ebx, ebx);
+  __ j(NegateCondition(is_string), &runtime);
+  // Get the length of the string to ebx.
+  __ mov(ebx, FieldOperand(eax, String::kLengthOffset));
+
+  // ebx: Length of subject string as a smi
+  // ecx: RegExp data (FixedArray)
+  // edx: Number of capture registers
+  // Check that the third argument is a positive smi less than the subject
+  // string length. A negative value will be greater (unsigned comparison).
+  __ mov(eax, Operand(esp, kPreviousIndexOffset));
+  __ test(eax, Immediate(kSmiTagMask));
+  __ j(not_zero, &runtime);
+  __ cmp(eax, Operand(ebx));
+  __ j(above_equal, &runtime);
+
+  // ecx: RegExp data (FixedArray)
+  // edx: Number of capture registers
+  // Check that the fourth object is a JSArray object.
+  __ mov(eax, Operand(esp, kLastMatchInfoOffset));
+  __ test(eax, Immediate(kSmiTagMask));
+  __ j(zero, &runtime);
+  __ CmpObjectType(eax, JS_ARRAY_TYPE, ebx);
+  __ j(not_equal, &runtime);
+  // Check that the JSArray is in fast case.
+  __ mov(ebx, FieldOperand(eax, JSArray::kElementsOffset));
+  __ mov(eax, FieldOperand(ebx, HeapObject::kMapOffset));
+  __ cmp(eax, Factory::fixed_array_map());
+  __ j(not_equal, &runtime);
+  // Check that the last match info has space for the capture registers and the
+  // additional information.
+  __ mov(eax, FieldOperand(ebx, FixedArray::kLengthOffset));
+  __ SmiUntag(eax);
+  __ add(Operand(edx), Immediate(RegExpImpl::kLastMatchOverhead));
+  __ cmp(edx, Operand(eax));
+  __ j(greater, &runtime);
+
+  // ecx: RegExp data (FixedArray)
+  // Check the representation and encoding of the subject string.
+  Label seq_ascii_string, seq_two_byte_string, check_code;
+  __ mov(eax, Operand(esp, kSubjectOffset));
+  __ mov(ebx, FieldOperand(eax, HeapObject::kMapOffset));
+  __ movzx_b(ebx, FieldOperand(ebx, Map::kInstanceTypeOffset));
+  // First check for flat two byte string.
+  __ and_(ebx,
+          kIsNotStringMask | kStringRepresentationMask | kStringEncodingMask);
+  STATIC_ASSERT((kStringTag | kSeqStringTag | kTwoByteStringTag) == 0);
+  __ j(zero, &seq_two_byte_string);
+  // Any other flat string must be a flat ascii string.
+  __ test(Operand(ebx),
+          Immediate(kIsNotStringMask | kStringRepresentationMask));
+  __ j(zero, &seq_ascii_string);
+
+  // 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);
+  __ test(Operand(ebx),
+          Immediate(kIsNotStringMask | kExternalStringTag));
+  __ j(not_zero, &runtime);
+  // String is a cons string.
+  __ mov(edx, FieldOperand(eax, ConsString::kSecondOffset));
+  __ cmp(Operand(edx), Factory::empty_string());
+  __ j(not_equal, &runtime);
+  __ mov(eax, FieldOperand(eax, ConsString::kFirstOffset));
+  __ mov(ebx, FieldOperand(eax, HeapObject::kMapOffset));
+  // String is a cons string with empty second part.
+  // eax: first part of cons string.
+  // ebx: map of first part of cons string.
+  // Is first part a flat two byte string?
+  __ test_b(FieldOperand(ebx, Map::kInstanceTypeOffset),
+            kStringRepresentationMask | kStringEncodingMask);
+  STATIC_ASSERT((kSeqStringTag | kTwoByteStringTag) == 0);
+  __ j(zero, &seq_two_byte_string);
+  // Any other flat string must be ascii.
+  __ test_b(FieldOperand(ebx, Map::kInstanceTypeOffset),
+            kStringRepresentationMask);
+  __ j(not_zero, &runtime);
+
+  __ bind(&seq_ascii_string);
+  // eax: subject string (flat ascii)
+  // ecx: RegExp data (FixedArray)
+  __ mov(edx, FieldOperand(ecx, JSRegExp::kDataAsciiCodeOffset));
+  __ Set(edi, Immediate(1));  // Type is ascii.
+  __ jmp(&check_code);
+
+  __ bind(&seq_two_byte_string);
+  // eax: subject string (flat two byte)
+  // ecx: RegExp data (FixedArray)
+  __ mov(edx, FieldOperand(ecx, JSRegExp::kDataUC16CodeOffset));
+  __ Set(edi, Immediate(0));  // Type is two byte.
+
+  __ bind(&check_code);
+  // Check that the irregexp code has been generated for the actual string
+  // encoding. If it has, the field contains a code object otherwise it contains
+  // the hole.
+  __ CmpObjectType(edx, CODE_TYPE, ebx);
+  __ j(not_equal, &runtime);
+
+  // eax: subject string
+  // edx: code
+  // edi: encoding of subject string (1 if ascii, 0 if two_byte);
+  // Load used arguments before starting to push arguments for call to native
+  // RegExp code to avoid handling changing stack height.
+  __ mov(ebx, Operand(esp, kPreviousIndexOffset));
+  __ SmiUntag(ebx);  // Previous index from smi.
+
+  // eax: subject string
+  // ebx: previous index
+  // edx: code
+  // edi: encoding of subject string (1 if ascii 0 if two_byte);
+  // All checks done. Now push arguments for native regexp code.
+  __ IncrementCounter(&Counters::regexp_entry_native, 1);
+
+  static const int kRegExpExecuteArguments = 7;
+  __ PrepareCallCFunction(kRegExpExecuteArguments, ecx);
+
+  // Argument 7: Indicate that this is a direct call from JavaScript.
+  __ mov(Operand(esp, 6 * kPointerSize), Immediate(1));
+
+  // Argument 6: Start (high end) of backtracking stack memory area.
+  __ mov(ecx, Operand::StaticVariable(address_of_regexp_stack_memory_address));
+  __ add(ecx, Operand::StaticVariable(address_of_regexp_stack_memory_size));
+  __ mov(Operand(esp, 5 * kPointerSize), ecx);
+
+  // Argument 5: static offsets vector buffer.
+  __ mov(Operand(esp, 4 * kPointerSize),
+         Immediate(ExternalReference::address_of_static_offsets_vector()));
+
+  // Argument 4: End of string data
+  // Argument 3: Start of string data
+  Label setup_two_byte, setup_rest;
+  __ test(edi, Operand(edi));
+  __ mov(edi, FieldOperand(eax, String::kLengthOffset));
+  __ j(zero, &setup_two_byte);
+  __ SmiUntag(edi);
+  __ lea(ecx, FieldOperand(eax, edi, times_1, SeqAsciiString::kHeaderSize));
+  __ mov(Operand(esp, 3 * kPointerSize), ecx);  // Argument 4.
+  __ lea(ecx, FieldOperand(eax, ebx, times_1, SeqAsciiString::kHeaderSize));
+  __ mov(Operand(esp, 2 * kPointerSize), ecx);  // Argument 3.
+  __ jmp(&setup_rest);
+
+  __ bind(&setup_two_byte);
+  STATIC_ASSERT(kSmiTag == 0);
+  STATIC_ASSERT(kSmiTagSize == 1);  // edi is smi (powered by 2).
+  __ lea(ecx, FieldOperand(eax, edi, times_1, SeqTwoByteString::kHeaderSize));
+  __ mov(Operand(esp, 3 * kPointerSize), ecx);  // Argument 4.
+  __ lea(ecx, FieldOperand(eax, ebx, times_2, SeqTwoByteString::kHeaderSize));
+  __ mov(Operand(esp, 2 * kPointerSize), ecx);  // Argument 3.
+
+  __ bind(&setup_rest);
+
+  // Argument 2: Previous index.
+  __ mov(Operand(esp, 1 * kPointerSize), ebx);
+
+  // Argument 1: Subject string.
+  __ mov(Operand(esp, 0 * kPointerSize), eax);
+
+  // Locate the code entry and call it.
+  __ add(Operand(edx), Immediate(Code::kHeaderSize - kHeapObjectTag));
+  __ CallCFunction(edx, kRegExpExecuteArguments);
+
+  // Check the result.
+  Label success;
+  __ cmp(eax, NativeRegExpMacroAssembler::SUCCESS);
+  __ j(equal, &success, taken);
+  Label failure;
+  __ cmp(eax, NativeRegExpMacroAssembler::FAILURE);
+  __ j(equal, &failure, taken);
+  __ cmp(eax, NativeRegExpMacroAssembler::EXCEPTION);
+  // If not exception it can only be retry. Handle that in the runtime system.
+  __ j(not_equal, &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.
+  ExternalReference pending_exception(Top::k_pending_exception_address);
+  __ mov(eax,
+         Operand::StaticVariable(ExternalReference::the_hole_value_location()));
+  __ cmp(eax, Operand::StaticVariable(pending_exception));
+  __ j(equal, &runtime);
+  __ bind(&failure);
+  // For failure and exception return null.
+  __ mov(Operand(eax), Factory::null_value());
+  __ ret(4 * kPointerSize);
+
+  // Load RegExp data.
+  __ bind(&success);
+  __ mov(eax, Operand(esp, kJSRegExpOffset));
+  __ mov(ecx, FieldOperand(eax, JSRegExp::kDataOffset));
+  __ mov(edx, FieldOperand(ecx, JSRegExp::kIrregexpCaptureCountOffset));
+  // Calculate number of capture registers (number_of_captures + 1) * 2.
+  STATIC_ASSERT(kSmiTag == 0);
+  STATIC_ASSERT(kSmiTagSize + kSmiShiftSize == 1);
+  __ add(Operand(edx), Immediate(2));  // edx was a smi.
+
+  // edx: Number of capture registers
+  // Load last_match_info which is still known to be a fast case JSArray.
+  __ mov(eax, Operand(esp, kLastMatchInfoOffset));
+  __ mov(ebx, FieldOperand(eax, JSArray::kElementsOffset));
+
+  // ebx: last_match_info backing store (FixedArray)
+  // edx: number of capture registers
+  // Store the capture count.
+  __ SmiTag(edx);  // Number of capture registers to smi.
+  __ mov(FieldOperand(ebx, RegExpImpl::kLastCaptureCountOffset), edx);
+  __ SmiUntag(edx);  // Number of capture registers back from smi.
+  // Store last subject and last input.
+  __ mov(eax, Operand(esp, kSubjectOffset));
+  __ mov(FieldOperand(ebx, RegExpImpl::kLastSubjectOffset), eax);
+  __ mov(ecx, ebx);
+  __ RecordWrite(ecx, RegExpImpl::kLastSubjectOffset, eax, edi);
+  __ mov(eax, Operand(esp, kSubjectOffset));
+  __ mov(FieldOperand(ebx, RegExpImpl::kLastInputOffset), eax);
+  __ mov(ecx, ebx);
+  __ RecordWrite(ecx, RegExpImpl::kLastInputOffset, eax, edi);
+
+  // Get the static offsets vector filled by the native regexp code.
+  ExternalReference address_of_static_offsets_vector =
+      ExternalReference::address_of_static_offsets_vector();
+  __ mov(ecx, Immediate(address_of_static_offsets_vector));
+
+  // ebx: last_match_info backing store (FixedArray)
+  // ecx: offsets vector
+  // edx: number of capture registers
+  Label next_capture, done;
+  // Capture register counter starts from number of capture registers and
+  // counts down until wraping after zero.
+  __ bind(&next_capture);
+  __ sub(Operand(edx), Immediate(1));
+  __ j(negative, &done);
+  // Read the value from the static offsets vector buffer.
+  __ mov(edi, Operand(ecx, edx, times_int_size, 0));
+  __ SmiTag(edi);
+  // Store the smi value in the last match info.
+  __ mov(FieldOperand(ebx,
+                      edx,
+                      times_pointer_size,
+                      RegExpImpl::kFirstCaptureOffset),
+                      edi);
+  __ jmp(&next_capture);
+  __ bind(&done);
+
+  // Return last match info.
+  __ mov(eax, Operand(esp, kLastMatchInfoOffset));
+  __ ret(4 * kPointerSize);
+
+  // Do the runtime call to execute the regexp.
+  __ bind(&runtime);
+  __ TailCallRuntime(Runtime::kRegExpExec, 4, 1);
+#endif  // V8_INTERPRETED_REGEXP
+}
+
+
+void NumberToStringStub::GenerateLookupNumberStringCache(MacroAssembler* masm,
+                                                         Register object,
+                                                         Register result,
+                                                         Register scratch1,
+                                                         Register scratch2,
+                                                         bool object_is_smi,
+                                                         Label* not_found) {
+  // Use of registers. Register result is used as a temporary.
+  Register number_string_cache = result;
+  Register mask = scratch1;
+  Register scratch = scratch2;
+
+  // Load the number string cache.
+  ExternalReference roots_address = ExternalReference::roots_address();
+  __ mov(scratch, Immediate(Heap::kNumberStringCacheRootIndex));
+  __ mov(number_string_cache,
+         Operand::StaticArray(scratch, times_pointer_size, roots_address));
+  // Make the hash mask from the length of the number string cache. It
+  // contains two elements (number and string) for each cache entry.
+  __ mov(mask, FieldOperand(number_string_cache, FixedArray::kLengthOffset));
+  __ shr(mask, kSmiTagSize + 1);  // Untag length and divide it by two.
+  __ sub(Operand(mask), Immediate(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 smi_hash_calculated;
+  Label load_result_from_cache;
+  if (object_is_smi) {
+    __ mov(scratch, object);
+    __ SmiUntag(scratch);
+  } else {
+    Label not_smi, hash_calculated;
+    STATIC_ASSERT(kSmiTag == 0);
+    __ test(object, Immediate(kSmiTagMask));
+    __ j(not_zero, &not_smi);
+    __ mov(scratch, object);
+    __ SmiUntag(scratch);
+    __ jmp(&smi_hash_calculated);
+    __ bind(&not_smi);
+    __ cmp(FieldOperand(object, HeapObject::kMapOffset),
+           Factory::heap_number_map());
+    __ j(not_equal, not_found);
+    STATIC_ASSERT(8 == kDoubleSize);
+    __ mov(scratch, FieldOperand(object, HeapNumber::kValueOffset));
+    __ xor_(scratch, FieldOperand(object, HeapNumber::kValueOffset + 4));
+    // Object is heap number and hash is now in scratch. Calculate cache index.
+    __ and_(scratch, Operand(mask));
+    Register index = scratch;
+    Register probe = mask;
+    __ mov(probe,
+           FieldOperand(number_string_cache,
+                        index,
+                        times_twice_pointer_size,
+                        FixedArray::kHeaderSize));
+    __ test(probe, Immediate(kSmiTagMask));
+    __ j(zero, not_found);
+    if (CpuFeatures::IsSupported(SSE2)) {
+      CpuFeatures::Scope fscope(SSE2);
+      __ movdbl(xmm0, FieldOperand(object, HeapNumber::kValueOffset));
+      __ movdbl(xmm1, FieldOperand(probe, HeapNumber::kValueOffset));
+      __ ucomisd(xmm0, xmm1);
+    } else {
+      __ fld_d(FieldOperand(object, HeapNumber::kValueOffset));
+      __ fld_d(FieldOperand(probe, HeapNumber::kValueOffset));
+      __ FCmp();
+    }
+    __ j(parity_even, not_found);  // Bail out if NaN is involved.
+    __ j(not_equal, not_found);  // The cache did not contain this value.
+    __ jmp(&load_result_from_cache);
+  }
+
+  __ bind(&smi_hash_calculated);
+  // Object is smi and hash is now in scratch. Calculate cache index.
+  __ and_(scratch, Operand(mask));
+  Register index = scratch;
+  // Check if the entry is the smi we are looking for.
+  __ cmp(object,
+         FieldOperand(number_string_cache,
+                      index,
+                      times_twice_pointer_size,
+                      FixedArray::kHeaderSize));
+  __ j(not_equal, not_found);
+
+  // Get the result from the cache.
+  __ bind(&load_result_from_cache);
+  __ mov(result,
+         FieldOperand(number_string_cache,
+                      index,
+                      times_twice_pointer_size,
+                      FixedArray::kHeaderSize + kPointerSize));
+  __ IncrementCounter(&Counters::number_to_string_native, 1);
+}
+
+
+void NumberToStringStub::Generate(MacroAssembler* masm) {
+  Label runtime;
+
+  __ mov(ebx, Operand(esp, kPointerSize));
+
+  // Generate code to lookup number in the number string cache.
+  GenerateLookupNumberStringCache(masm, ebx, eax, ecx, edx, false, &runtime);
+  __ ret(1 * kPointerSize);
+
+  __ bind(&runtime);
+  // Handle number to string in the runtime system if not found in the cache.
+  __ TailCallRuntime(Runtime::kNumberToStringSkipCache, 1, 1);
+}
+
+
+static int NegativeComparisonResult(Condition cc) {
+  ASSERT(cc != equal);
+  ASSERT((cc == less) || (cc == less_equal)
+      || (cc == greater) || (cc == greater_equal));
+  return (cc == greater || cc == greater_equal) ? LESS : GREATER;
+}
+
+void CompareStub::Generate(MacroAssembler* masm) {
+  ASSERT(lhs_.is(no_reg) && rhs_.is(no_reg));
+
+  Label check_unequal_objects, done;
+
+  // 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.
+
+  // Identical objects can be compared fast, but there are some tricky cases
+  // for NaN and undefined.
+  {
+    Label not_identical;
+    __ cmp(eax, Operand(edx));
+    __ j(not_equal, &not_identical);
+
+    if (cc_ != equal) {
+      // Check for undefined.  undefined OP undefined is false even though
+      // undefined == undefined.
+      Label check_for_nan;
+      __ cmp(edx, Factory::undefined_value());
+      __ j(not_equal, &check_for_nan);
+      __ Set(eax, Immediate(Smi::FromInt(NegativeComparisonResult(cc_))));
+      __ ret(0);
+      __ bind(&check_for_nan);
+    }
+
+    // Test for NaN. Sadly, we can't just compare to Factory::nan_value(),
+    // so we do the second best thing - test it ourselves.
+    // Note: if cc_ != equal, never_nan_nan_ is not used.
+    if (never_nan_nan_ && (cc_ == equal)) {
+      __ Set(eax, Immediate(Smi::FromInt(EQUAL)));
+      __ ret(0);
+    } else {
+      Label heap_number;
+      __ cmp(FieldOperand(edx, HeapObject::kMapOffset),
+             Immediate(Factory::heap_number_map()));
+      __ j(equal, &heap_number);
+      if (cc_ != equal) {
+        // Call runtime on identical JSObjects.  Otherwise return equal.
+        __ CmpObjectType(eax, FIRST_JS_OBJECT_TYPE, ecx);
+        __ j(above_equal, &not_identical);
+      }
+      __ Set(eax, Immediate(Smi::FromInt(EQUAL)));
+      __ ret(0);
+
+      __ 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.
+      // We only accept QNaNs, which have bit 51 set.
+      // Read top bits of double representation (second word of value).
+
+      // Value is a QNaN if value & kQuietNaNMask == kQuietNaNMask, i.e.,
+      // all bits in the mask are set. We only need to check the word
+      // that contains the exponent and high bit of the mantissa.
+      STATIC_ASSERT(((kQuietNaNHighBitsMask << 1) & 0x80000000u) != 0);
+      __ mov(edx, FieldOperand(edx, HeapNumber::kExponentOffset));
+      __ xor_(eax, Operand(eax));
+      // Shift value and mask so kQuietNaNHighBitsMask applies to topmost
+      // bits.
+      __ add(edx, Operand(edx));
+      __ cmp(edx, kQuietNaNHighBitsMask << 1);
+      if (cc_ == equal) {
+        STATIC_ASSERT(EQUAL != 1);
+        __ setcc(above_equal, eax);
+        __ ret(0);
+      } else {
+        Label nan;
+        __ j(above_equal, &nan);
+        __ Set(eax, Immediate(Smi::FromInt(EQUAL)));
+        __ ret(0);
+        __ bind(&nan);
+        __ Set(eax, Immediate(Smi::FromInt(NegativeComparisonResult(cc_))));
+        __ ret(0);
+      }
+    }
+
+    __ bind(&not_identical);
+  }
+
+  // Strict equality can quickly decide whether objects are equal.
+  // Non-strict object equality is slower, so it is handled later in the stub.
+  if (cc_ == equal && strict_) {
+    Label slow;  // Fallthrough label.
+    Label not_smis;
+    // If we're doing a strict equality comparison, we don't have to do
+    // type conversion, so we generate code to do fast comparison for objects
+    // and oddballs. Non-smi numbers and strings still go through the usual
+    // slow-case code.
+    // If either is a Smi (we know that not both are), then they can only
+    // be equal if the other is a HeapNumber. If so, use the slow case.
+    STATIC_ASSERT(kSmiTag == 0);
+    ASSERT_EQ(0, Smi::FromInt(0));
+    __ mov(ecx, Immediate(kSmiTagMask));
+    __ and_(ecx, Operand(eax));
+    __ test(ecx, Operand(edx));
+    __ j(not_zero, &not_smis);
+    // One operand is a smi.
+
+    // Check whether the non-smi is a heap number.
+    STATIC_ASSERT(kSmiTagMask == 1);
+    // ecx still holds eax & kSmiTag, which is either zero or one.
+    __ sub(Operand(ecx), Immediate(0x01));
+    __ mov(ebx, edx);
+    __ xor_(ebx, Operand(eax));
+    __ and_(ebx, Operand(ecx));  // ebx holds either 0 or eax ^ edx.
+    __ xor_(ebx, Operand(eax));
+    // if eax was smi, ebx is now edx, else eax.
+
+    // Check if the non-smi operand is a heap number.
+    __ cmp(FieldOperand(ebx, HeapObject::kMapOffset),
+           Immediate(Factory::heap_number_map()));
+    // If heap number, handle it in the slow case.
+    __ j(equal, &slow);
+    // Return non-equal (ebx is not zero)
+    __ mov(eax, ebx);
+    __ ret(0);
+
+    __ bind(&not_smis);
+    // 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.
+
+    // Get the type of the first operand.
+    // If the first object is a JS object, we have done pointer comparison.
+    Label first_non_object;
+    STATIC_ASSERT(LAST_TYPE == JS_FUNCTION_TYPE);
+    __ CmpObjectType(eax, FIRST_JS_OBJECT_TYPE, ecx);
+    __ j(below, &first_non_object);
+
+    // Return non-zero (eax is not zero)
+    Label return_not_equal;
+    STATIC_ASSERT(kHeapObjectTag != 0);
+    __ bind(&return_not_equal);
+    __ ret(0);
+
+    __ bind(&first_non_object);
+    // Check for oddballs: true, false, null, undefined.
+    __ CmpInstanceType(ecx, ODDBALL_TYPE);
+    __ j(equal, &return_not_equal);
+
+    __ CmpObjectType(edx, FIRST_JS_OBJECT_TYPE, ecx);
+    __ j(above_equal, &return_not_equal);
+
+    // Check for oddballs: true, false, null, undefined.
+    __ CmpInstanceType(ecx, ODDBALL_TYPE);
+    __ j(equal, &return_not_equal);
+
+    // Fall through to the general case.
+    __ bind(&slow);
+  }
+
+  // Generate the number comparison code.
+  if (include_number_compare_) {
+    Label non_number_comparison;
+    Label unordered;
+    if (CpuFeatures::IsSupported(SSE2)) {
+      CpuFeatures::Scope use_sse2(SSE2);
+      CpuFeatures::Scope use_cmov(CMOV);
+
+      FloatingPointHelper::LoadSSE2Operands(masm, &non_number_comparison);
+      __ ucomisd(xmm0, xmm1);
+
+      // Don't base result on EFLAGS when a NaN is involved.
+      __ j(parity_even, &unordered, not_taken);
+      // Return a result of -1, 0, or 1, based on EFLAGS.
+      __ mov(eax, 0);  // equal
+      __ mov(ecx, Immediate(Smi::FromInt(1)));
+      __ cmov(above, eax, Operand(ecx));
+      __ mov(ecx, Immediate(Smi::FromInt(-1)));
+      __ cmov(below, eax, Operand(ecx));
+      __ ret(0);
+    } else {
+      FloatingPointHelper::CheckFloatOperands(
+          masm, &non_number_comparison, ebx);
+      FloatingPointHelper::LoadFloatOperand(masm, eax);
+      FloatingPointHelper::LoadFloatOperand(masm, edx);
+      __ FCmp();
+
+      // Don't base result on EFLAGS when a NaN is involved.
+      __ j(parity_even, &unordered, not_taken);
+
+      Label below_label, above_label;
+      // Return a result of -1, 0, or 1, based on EFLAGS.
+      __ j(below, &below_label, not_taken);
+      __ j(above, &above_label, not_taken);
+
+      __ xor_(eax, Operand(eax));
+      __ ret(0);
+
+      __ bind(&below_label);
+      __ mov(eax, Immediate(Smi::FromInt(-1)));
+      __ ret(0);
+
+      __ bind(&above_label);
+      __ mov(eax, Immediate(Smi::FromInt(1)));
+      __ ret(0);
+    }
+
+    // If one of the numbers was NaN, then the result is always false.
+    // The cc is never not-equal.
+    __ bind(&unordered);
+    ASSERT(cc_ != not_equal);
+    if (cc_ == less || cc_ == less_equal) {
+      __ mov(eax, Immediate(Smi::FromInt(1)));
+    } else {
+      __ mov(eax, Immediate(Smi::FromInt(-1)));
+    }
+    __ ret(0);
+
+    // The number comparison code did not provide a valid result.
+    __ bind(&non_number_comparison);
+  }
+
+  // Fast negative check for symbol-to-symbol equality.
+  Label check_for_strings;
+  if (cc_ == equal) {
+    BranchIfNonSymbol(masm, &check_for_strings, eax, ecx);
+    BranchIfNonSymbol(masm, &check_for_strings, edx, ecx);
+
+    // We've already checked for object identity, so if both operands
+    // are symbols they aren't equal. Register eax already holds a
+    // non-zero value, which indicates not equal, so just return.
+    __ ret(0);
+  }
+
+  __ bind(&check_for_strings);
+
+  __ JumpIfNotBothSequentialAsciiStrings(edx, eax, ecx, ebx,
+                                         &check_unequal_objects);
+
+  // Inline comparison of ascii strings.
+  StringCompareStub::GenerateCompareFlatAsciiStrings(masm,
+                                                     edx,
+                                                     eax,
+                                                     ecx,
+                                                     ebx,
+                                                     edi);
+#ifdef DEBUG
+  __ Abort("Unexpected fall-through from string comparison");
+#endif
+
+  __ bind(&check_unequal_objects);
+  if (cc_ == equal && !strict_) {
+    // Non-strict equality.  Objects are unequal if
+    // they are both JSObjects and not undetectable,
+    // and their pointers are different.
+    Label not_both_objects;
+    Label return_unequal;
+    // At most one is a smi, so we can test for smi by adding the two.
+    // A smi plus a heap object has the low bit set, a heap object plus
+    // a heap object has the low bit clear.
+    STATIC_ASSERT(kSmiTag == 0);
+    STATIC_ASSERT(kSmiTagMask == 1);
+    __ lea(ecx, Operand(eax, edx, times_1, 0));
+    __ test(ecx, Immediate(kSmiTagMask));
+    __ j(not_zero, &not_both_objects);
+    __ CmpObjectType(eax, FIRST_JS_OBJECT_TYPE, ecx);
+    __ j(below, &not_both_objects);
+    __ CmpObjectType(edx, FIRST_JS_OBJECT_TYPE, ebx);
+    __ j(below, &not_both_objects);
+    // We do not bail out after this point.  Both are JSObjects, and
+    // they are equal if and only if both are undetectable.
+    // The and of the undetectable flags is 1 if and only if they are equal.
+    __ test_b(FieldOperand(ecx, Map::kBitFieldOffset),
+              1 << Map::kIsUndetectable);
+    __ j(zero, &return_unequal);
+    __ test_b(FieldOperand(ebx, Map::kBitFieldOffset),
+              1 << Map::kIsUndetectable);
+    __ j(zero, &return_unequal);
+    // The objects are both undetectable, so they both compare as the value
+    // undefined, and are equal.
+    __ Set(eax, Immediate(EQUAL));
+    __ bind(&return_unequal);
+    // Return non-equal by returning the non-zero object pointer in eax,
+    // or return equal if we fell through to here.
+    __ ret(0);  // rax, rdx were pushed
+    __ bind(&not_both_objects);
+  }
+
+  // Push arguments below the return address.
+  __ pop(ecx);
+  __ push(edx);
+  __ push(eax);
+
+  // Figure out which native to call and setup the arguments.
+  Builtins::JavaScript builtin;
+  if (cc_ == equal) {
+    builtin = strict_ ? Builtins::STRICT_EQUALS : Builtins::EQUALS;
+  } else {
+    builtin = Builtins::COMPARE;
+    __ push(Immediate(Smi::FromInt(NegativeComparisonResult(cc_))));
+  }
+
+  // Restore return address on the stack.
+  __ push(ecx);
+
+  // Call the native; it returns -1 (less), 0 (equal), or 1 (greater)
+  // tagged as a small integer.
+  __ InvokeBuiltin(builtin, JUMP_FUNCTION);
+}
+
+
+void CompareStub::BranchIfNonSymbol(MacroAssembler* masm,
+                                    Label* label,
+                                    Register object,
+                                    Register scratch) {
+  __ test(object, Immediate(kSmiTagMask));
+  __ j(zero, label);
+  __ mov(scratch, FieldOperand(object, HeapObject::kMapOffset));
+  __ movzx_b(scratch, FieldOperand(scratch, Map::kInstanceTypeOffset));
+  __ and_(scratch, kIsSymbolMask | kIsNotStringMask);
+  __ cmp(scratch, kSymbolTag | kStringTag);
+  __ j(not_equal, label);
+}
+
+
+void StackCheckStub::Generate(MacroAssembler* masm) {
+  // Because builtins always remove the receiver from the stack, we
+  // have to fake one to avoid underflowing the stack. The receiver
+  // must be inserted below the return address on the stack so we
+  // temporarily store that in a register.
+  __ pop(eax);
+  __ push(Immediate(Smi::FromInt(0)));
+  __ push(eax);
+
+  // Do tail-call to runtime routine.
+  __ TailCallRuntime(Runtime::kStackGuard, 1, 1);
+}
+
+
+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.
+    // +1 ~ return address
+    Label receiver_is_value, receiver_is_js_object;
+    __ mov(eax, Operand(esp, (argc_ + 1) * kPointerSize));
+
+    // Check if receiver is a smi (which is a number value).
+    __ test(eax, Immediate(kSmiTagMask));
+    __ j(zero, &receiver_is_value, not_taken);
+
+    // Check if the receiver is a valid JS object.
+    __ CmpObjectType(eax, FIRST_JS_OBJECT_TYPE, edi);
+    __ j(above_equal, &receiver_is_js_object);
+
+    // Call the runtime to box the value.
+    __ bind(&receiver_is_value);
+    __ EnterInternalFrame();
+    __ push(eax);
+    __ InvokeBuiltin(Builtins::TO_OBJECT, CALL_FUNCTION);
+    __ LeaveInternalFrame();
+    __ mov(Operand(esp, (argc_ + 1) * kPointerSize), eax);
+
+    __ bind(&receiver_is_js_object);
+  }
+
+  // Get the function to call from the stack.
+  // +2 ~ receiver, return address
+  __ mov(edi, Operand(esp, (argc_ + 2) * kPointerSize));
+
+  // Check that the function really is a JavaScript function.
+  __ test(edi, Immediate(kSmiTagMask));
+  __ j(zero, &slow, not_taken);
+  // Goto slow case if we do not have a function.
+  __ CmpObjectType(edi, JS_FUNCTION_TYPE, ecx);
+  __ j(not_equal, &slow, not_taken);
+
+  // Fast-case: Just invoke the function.
+  ParameterCount actual(argc_);
+  __ InvokeFunction(edi, 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).
+  __ mov(Operand(esp, (argc_ + 1) * kPointerSize), edi);
+  __ Set(eax, Immediate(argc_));
+  __ Set(ebx, Immediate(0));
+  __ GetBuiltinEntry(edx, Builtins::CALL_NON_FUNCTION);
+  Handle<Code> adaptor(Builtins::builtin(Builtins::ArgumentsAdaptorTrampoline));
+  __ jmp(adaptor, RelocInfo::CODE_TARGET);
+}
+
+
+void CEntryStub::GenerateThrowTOS(MacroAssembler* masm) {
+  // eax 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.
+  ExternalReference handler_address(Top::k_handler_address);
+  __ mov(esp, Operand::StaticVariable(handler_address));
+
+  // Restore next handler and frame pointer, discard handler state.
+  STATIC_ASSERT(StackHandlerConstants::kNextOffset == 0);
+  __ pop(Operand::StaticVariable(handler_address));
+  STATIC_ASSERT(StackHandlerConstants::kFPOffset == 1 * kPointerSize);
+  __ pop(ebp);
+  __ pop(edx);  // Remove 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.
+  __ xor_(esi, Operand(esi));  // Tentatively set context pointer to NULL.
+  Label skip;
+  __ cmp(ebp, 0);
+  __ j(equal, &skip, not_taken);
+  __ mov(esi, Operand(ebp, StandardFrameConstants::kContextOffset));
+  __ bind(&skip);
+
+  STATIC_ASSERT(StackHandlerConstants::kPCOffset == 3 * kPointerSize);
+  __ ret(0);
+}
+
+
+// If true, a Handle<T> passed by value is passed and returned by
+// using the location_ field directly.  If false, it is passed and
+// returned as a pointer to a handle.
+#ifdef USING_BSD_ABI
+static const bool kPassHandlesDirectly = true;
+#else
+static const bool kPassHandlesDirectly = false;
+#endif
+
+
+void ApiGetterEntryStub::Generate(MacroAssembler* masm) {
+  Label empty_handle;
+  Label prologue;
+  Label promote_scheduled_exception;
+  __ EnterApiExitFrame(ExitFrame::MODE_NORMAL, kStackSpace, kArgc);
+  STATIC_ASSERT(kArgc == 4);
+  if (kPassHandlesDirectly) {
+    // When handles as passed directly we don't have to allocate extra
+    // space for and pass an out parameter.
+    __ mov(Operand(esp, 0 * kPointerSize), ebx);  // name.
+    __ mov(Operand(esp, 1 * kPointerSize), eax);  // arguments pointer.
+  } else {
+    // The function expects three arguments to be passed but we allocate
+    // four to get space for the output cell.  The argument slots are filled
+    // as follows:
+    //
+    //   3: output cell
+    //   2: arguments pointer
+    //   1: name
+    //   0: pointer to the output cell
+    //
+    // Note that this is one more "argument" than the function expects
+    // so the out cell will have to be popped explicitly after returning
+    // from the function.
+    __ mov(Operand(esp, 1 * kPointerSize), ebx);  // name.
+    __ mov(Operand(esp, 2 * kPointerSize), eax);  // arguments pointer.
+    __ mov(ebx, esp);
+    __ add(Operand(ebx), Immediate(3 * kPointerSize));
+    __ mov(Operand(esp, 0 * kPointerSize), ebx);  // output
+    __ mov(Operand(esp, 3 * kPointerSize), Immediate(0));  // out cell.
+  }
+  // Call the api function!
+  __ call(fun()->address(), RelocInfo::RUNTIME_ENTRY);
+  // Check if the function scheduled an exception.
+  ExternalReference scheduled_exception_address =
+      ExternalReference::scheduled_exception_address();
+  __ cmp(Operand::StaticVariable(scheduled_exception_address),
+         Immediate(Factory::the_hole_value()));
+  __ j(not_equal, &promote_scheduled_exception, not_taken);
+  if (!kPassHandlesDirectly) {
+    // The returned value is a pointer to the handle holding the result.
+    // Dereference this to get to the location.
+    __ mov(eax, Operand(eax, 0));
+  }
+  // Check if the result handle holds 0.
+  __ test(eax, Operand(eax));
+  __ j(zero, &empty_handle, not_taken);
+  // It was non-zero.  Dereference to get the result value.
+  __ mov(eax, Operand(eax, 0));
+  __ bind(&prologue);
+  __ LeaveExitFrame(ExitFrame::MODE_NORMAL);
+  __ ret(0);
+  __ bind(&promote_scheduled_exception);
+  __ TailCallRuntime(Runtime::kPromoteScheduledException, 0, 1);
+  __ bind(&empty_handle);
+  // It was zero; the result is undefined.
+  __ mov(eax, Factory::undefined_value());
+  __ jmp(&prologue);
+}
+
+
+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_scope,
+                              int /* alignment_skew */) {
+  // eax: result parameter for PerformGC, if any
+  // ebx: pointer to C function  (C callee-saved)
+  // ebp: frame pointer  (restored after C call)
+  // esp: stack pointer  (restored after C call)
+  // edi: number of arguments including receiver  (C callee-saved)
+  // esi: pointer to the first argument (C callee-saved)
+
+  // Result returned in eax, or eax+edx if result_size_ is 2.
+
+  // Check stack alignment.
+  if (FLAG_debug_code) {
+    __ CheckStackAlignment();
+  }
+
+  if (do_gc) {
+    // Pass failure code returned from last attempt as first argument to
+    // PerformGC. No need to use PrepareCallCFunction/CallCFunction here as the
+    // stack alignment is known to be correct. This function takes one argument
+    // which is passed on the stack, and we know that the stack has been
+    // prepared to pass at least one argument.
+    __ mov(Operand(esp, 0 * kPointerSize), eax);  // Result.
+    __ call(FUNCTION_ADDR(Runtime::PerformGC), RelocInfo::RUNTIME_ENTRY);
+  }
+
+  ExternalReference scope_depth =
+      ExternalReference::heap_always_allocate_scope_depth();
+  if (always_allocate_scope) {
+    __ inc(Operand::StaticVariable(scope_depth));
+  }
+
+  // Call C function.
+  __ mov(Operand(esp, 0 * kPointerSize), edi);  // argc.
+  __ mov(Operand(esp, 1 * kPointerSize), esi);  // argv.
+  __ call(Operand(ebx));
+  // Result is in eax or edx:eax - do not destroy these registers!
+
+  if (always_allocate_scope) {
+    __ dec(Operand::StaticVariable(scope_depth));
+  }
+
+  // Make sure we're not trying to return 'the hole' from the runtime
+  // call as this may lead to crashes in the IC code later.
+  if (FLAG_debug_code) {
+    Label okay;
+    __ cmp(eax, Factory::the_hole_value());
+    __ j(not_equal, &okay);
+    __ int3();
+    __ bind(&okay);
+  }
+
+  // Check for failure result.
+  Label failure_returned;
+  STATIC_ASSERT(((kFailureTag + 1) & kFailureTagMask) == 0);
+  __ lea(ecx, Operand(eax, 1));
+  // Lower 2 bits of ecx are 0 iff eax has failure tag.
+  __ test(ecx, Immediate(kFailureTagMask));
+  __ j(zero, &failure_returned, not_taken);
+
+  // Exit the JavaScript to C++ exit frame.
+  __ LeaveExitFrame(mode_);
+  __ ret(0);
+
+  // Handling of failure.
+  __ bind(&failure_returned);
+
+  Label retry;
+  // If the returned exception is RETRY_AFTER_GC continue at retry label
+  STATIC_ASSERT(Failure::RETRY_AFTER_GC == 0);
+  __ test(eax, Immediate(((1 << kFailureTypeTagSize) - 1) << kFailureTagSize));
+  __ j(zero, &retry, taken);
+
+  // Special handling of out of memory exceptions.
+  __ cmp(eax, reinterpret_cast<int32_t>(Failure::OutOfMemoryException()));
+  __ j(equal, throw_out_of_memory_exception);
+
+  // Retrieve the pending exception and clear the variable.
+  ExternalReference pending_exception_address(Top::k_pending_exception_address);
+  __ mov(eax, Operand::StaticVariable(pending_exception_address));
+  __ mov(edx,
+         Operand::StaticVariable(ExternalReference::the_hole_value_location()));
+  __ mov(Operand::StaticVariable(pending_exception_address), edx);
+
+  // Special handling of termination exceptions which are uncatchable
+  // by javascript code.
+  __ cmp(eax, Factory::termination_exception());
+  __ j(equal, throw_termination_exception);
+
+  // Handle normal exception.
+  __ jmp(throw_normal_exception);
+
+  // Retry.
+  __ bind(&retry);
+}
+
+
+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.
+  ExternalReference handler_address(Top::k_handler_address);
+  __ mov(esp, Operand::StaticVariable(handler_address));
+
+  // 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;
+  __ cmp(Operand(esp, kStateOffset), Immediate(StackHandler::ENTRY));
+  __ j(equal, &done);
+  // Fetch the next handler in the list.
+  const int kNextOffset = StackHandlerConstants::kNextOffset;
+  __ mov(esp, Operand(esp, kNextOffset));
+  __ jmp(&loop);
+  __ bind(&done);
+
+  // Set the top handler address to next handler past the current ENTRY handler.
+  STATIC_ASSERT(StackHandlerConstants::kNextOffset == 0);
+  __ pop(Operand::StaticVariable(handler_address));
+
+  if (type == OUT_OF_MEMORY) {
+    // Set external caught exception to false.
+    ExternalReference external_caught(Top::k_external_caught_exception_address);
+    __ mov(eax, false);
+    __ mov(Operand::StaticVariable(external_caught), eax);
+
+    // Set pending exception and eax to out of memory exception.
+    ExternalReference pending_exception(Top::k_pending_exception_address);
+    __ mov(eax, reinterpret_cast<int32_t>(Failure::OutOfMemoryException()));
+    __ mov(Operand::StaticVariable(pending_exception), eax);
+  }
+
+  // Clear the context pointer.
+  __ xor_(esi, Operand(esi));
+
+  // Restore fp from handler and discard handler state.
+  STATIC_ASSERT(StackHandlerConstants::kFPOffset == 1 * kPointerSize);
+  __ pop(ebp);
+  __ pop(edx);  // State.
+
+  STATIC_ASSERT(StackHandlerConstants::kPCOffset == 3 * kPointerSize);
+  __ ret(0);
+}
+
+
+void CEntryStub::Generate(MacroAssembler* masm) {
+  // eax: number of arguments including receiver
+  // ebx: pointer to C function  (C callee-saved)
+  // ebp: frame pointer  (restored after C call)
+  // esp: stack pointer  (restored after C call)
+  // esi: current context (C callee-saved)
+  // edi: JS function of the caller (C callee-saved)
+
+  // 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 (twice).
+
+  // Enter the exit frame that transitions from JavaScript to C++.
+  __ EnterExitFrame(mode_);
+
+  // eax: result parameter for PerformGC, if any (setup below)
+  // ebx: pointer to builtin function  (C callee-saved)
+  // ebp: frame pointer  (restored after C call)
+  // esp: stack pointer  (restored after C call)
+  // edi: number of arguments including receiver (C callee-saved)
+  // esi: argv pointer (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);
+
+  // Do space-specific GC and retry runtime call.
+  GenerateCore(masm,
+               &throw_normal_exception,
+               &throw_termination_exception,
+               &throw_out_of_memory_exception,
+               true,
+               false);
+
+  // Do full GC and retry runtime call one final time.
+  Failure* failure = Failure::InternalError();
+  __ mov(eax, Immediate(reinterpret_cast<int32_t>(failure)));
+  GenerateCore(masm,
+               &throw_normal_exception,
+               &throw_termination_exception,
+               &throw_out_of_memory_exception,
+               true,
+               true);
+
+  __ 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) {
+  Label invoke, exit;
+#ifdef ENABLE_LOGGING_AND_PROFILING
+  Label not_outermost_js, not_outermost_js_2;
+#endif
+
+  // Setup frame.
+  __ push(ebp);
+  __ mov(ebp, Operand(esp));
+
+  // Push marker in two places.
+  int marker = is_construct ? StackFrame::ENTRY_CONSTRUCT : StackFrame::ENTRY;
+  __ push(Immediate(Smi::FromInt(marker)));  // context slot
+  __ push(Immediate(Smi::FromInt(marker)));  // function slot
+  // Save callee-saved registers (C calling conventions).
+  __ push(edi);
+  __ push(esi);
+  __ push(ebx);
+
+  // Save copies of the top frame descriptor on the stack.
+  ExternalReference c_entry_fp(Top::k_c_entry_fp_address);
+  __ push(Operand::StaticVariable(c_entry_fp));
+
+#ifdef ENABLE_LOGGING_AND_PROFILING
+  // If this is the outermost JS call, set js_entry_sp value.
+  ExternalReference js_entry_sp(Top::k_js_entry_sp_address);
+  __ cmp(Operand::StaticVariable(js_entry_sp), Immediate(0));
+  __ j(not_equal, &not_outermost_js);
+  __ mov(Operand::StaticVariable(js_entry_sp), ebp);
+  __ bind(&not_outermost_js);
+#endif
+
+  // Call a faked try-block that does the invoke.
+  __ call(&invoke);
+
+  // Caught exception: Store result (exception) in the pending
+  // exception field in the JSEnv and return a failure sentinel.
+  ExternalReference pending_exception(Top::k_pending_exception_address);
+  __ mov(Operand::StaticVariable(pending_exception), eax);
+  __ mov(eax, reinterpret_cast<int32_t>(Failure::Exception()));
+  __ jmp(&exit);
+
+  // Invoke: Link this frame into the handler chain.
+  __ bind(&invoke);
+  __ PushTryHandler(IN_JS_ENTRY, JS_ENTRY_HANDLER);
+
+  // Clear any pending exceptions.
+  __ mov(edx,
+         Operand::StaticVariable(ExternalReference::the_hole_value_location()));
+  __ mov(Operand::StaticVariable(pending_exception), edx);
+
+  // Fake a receiver (NULL).
+  __ push(Immediate(0));  // receiver
+
+  // Invoke the function by calling through JS entry trampoline
+  // builtin and pop the faked function when we return. Notice that we
+  // cannot store a reference to the trampoline code directly in this
+  // stub, because the builtin stubs may not have been generated yet.
+  if (is_construct) {
+    ExternalReference construct_entry(Builtins::JSConstructEntryTrampoline);
+    __ mov(edx, Immediate(construct_entry));
+  } else {
+    ExternalReference entry(Builtins::JSEntryTrampoline);
+    __ mov(edx, Immediate(entry));
+  }
+  __ mov(edx, Operand(edx, 0));  // deref address
+  __ lea(edx, FieldOperand(edx, Code::kHeaderSize));
+  __ call(Operand(edx));
+
+  // Unlink this frame from the handler chain.
+  __ pop(Operand::StaticVariable(ExternalReference(Top::k_handler_address)));
+  // Pop next_sp.
+  __ add(Operand(esp), Immediate(StackHandlerConstants::kSize - kPointerSize));
+
+#ifdef ENABLE_LOGGING_AND_PROFILING
+  // If current EBP value is the same as js_entry_sp value, it means that
+  // the current function is the outermost.
+  __ cmp(ebp, Operand::StaticVariable(js_entry_sp));
+  __ j(not_equal, &not_outermost_js_2);
+  __ mov(Operand::StaticVariable(js_entry_sp), Immediate(0));
+  __ bind(&not_outermost_js_2);
+#endif
+
+  // Restore the top frame descriptor from the stack.
+  __ bind(&exit);
+  __ pop(Operand::StaticVariable(ExternalReference(Top::k_c_entry_fp_address)));
+
+  // Restore callee-saved registers (C calling conventions).
+  __ pop(ebx);
+  __ pop(esi);
+  __ pop(edi);
+  __ add(Operand(esp), Immediate(2 * kPointerSize));  // remove markers
+
+  // Restore frame pointer and return.
+  __ pop(ebp);
+  __ ret(0);
+}
+
+
+void InstanceofStub::Generate(MacroAssembler* masm) {
+  // Get the object - go slow case if it's a smi.
+  Label slow;
+  __ mov(eax, Operand(esp, 2 * kPointerSize));  // 2 ~ return address, function
+  __ test(eax, Immediate(kSmiTagMask));
+  __ j(zero, &slow, not_taken);
+
+  // Check that the left hand is a JS object.
+  __ IsObjectJSObjectType(eax, eax, edx, &slow);
+
+  // Get the prototype of the function.
+  __ mov(edx, Operand(esp, 1 * kPointerSize));  // 1 ~ return address
+  // edx is function, eax is map.
+
+  // Look up the function and the map in the instanceof cache.
+  Label miss;
+  ExternalReference roots_address = ExternalReference::roots_address();
+  __ mov(ecx, Immediate(Heap::kInstanceofCacheFunctionRootIndex));
+  __ cmp(edx, Operand::StaticArray(ecx, times_pointer_size, roots_address));
+  __ j(not_equal, &miss);
+  __ mov(ecx, Immediate(Heap::kInstanceofCacheMapRootIndex));
+  __ cmp(eax, Operand::StaticArray(ecx, times_pointer_size, roots_address));
+  __ j(not_equal, &miss);
+  __ mov(ecx, Immediate(Heap::kInstanceofCacheAnswerRootIndex));
+  __ mov(eax, Operand::StaticArray(ecx, times_pointer_size, roots_address));
+  __ ret(2 * kPointerSize);
+
+  __ bind(&miss);
+  __ TryGetFunctionPrototype(edx, ebx, ecx, &slow);
+
+  // Check that the function prototype is a JS object.
+  __ test(ebx, Immediate(kSmiTagMask));
+  __ j(zero, &slow, not_taken);
+  __ IsObjectJSObjectType(ebx, ecx, ecx, &slow);
+
+  // Register mapping:
+  //   eax is object map.
+  //   edx is function.
+  //   ebx is function prototype.
+  __ mov(ecx, Immediate(Heap::kInstanceofCacheMapRootIndex));
+  __ mov(Operand::StaticArray(ecx, times_pointer_size, roots_address), eax);
+  __ mov(ecx, Immediate(Heap::kInstanceofCacheFunctionRootIndex));
+  __ mov(Operand::StaticArray(ecx, times_pointer_size, roots_address), edx);
+
+  __ mov(ecx, FieldOperand(eax, Map::kPrototypeOffset));
+
+  // Loop through the prototype chain looking for the function prototype.
+  Label loop, is_instance, is_not_instance;
+  __ bind(&loop);
+  __ cmp(ecx, Operand(ebx));
+  __ j(equal, &is_instance);
+  __ cmp(Operand(ecx), Immediate(Factory::null_value()));
+  __ j(equal, &is_not_instance);
+  __ mov(ecx, FieldOperand(ecx, HeapObject::kMapOffset));
+  __ mov(ecx, FieldOperand(ecx, Map::kPrototypeOffset));
+  __ jmp(&loop);
+
+  __ bind(&is_instance);
+  __ Set(eax, Immediate(0));
+  __ mov(ecx, Immediate(Heap::kInstanceofCacheAnswerRootIndex));
+  __ mov(Operand::StaticArray(ecx, times_pointer_size, roots_address), eax);
+  __ ret(2 * kPointerSize);
+
+  __ bind(&is_not_instance);
+  __ Set(eax, Immediate(Smi::FromInt(1)));
+  __ mov(ecx, Immediate(Heap::kInstanceofCacheAnswerRootIndex));
+  __ mov(Operand::StaticArray(ecx, times_pointer_size, roots_address), eax);
+  __ ret(2 * kPointerSize);
+
+  // Slow-case: Go through the JavaScript implementation.
+  __ bind(&slow);
+  __ InvokeBuiltin(Builtins::INSTANCE_OF, JUMP_FUNCTION);
+}
+
+
+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_) < (1 << 12));
+  ASSERT(lhs_.is(no_reg) && rhs_.is(no_reg));
+  return ConditionField::encode(static_cast<unsigned>(cc_))
+         | RegisterField::encode(false)   // lhs_ and rhs_ are not used
+         | StrictField::encode(strict_)
+         | NeverNanNanField::encode(cc_ == equal ? never_nan_nan_ : false)
+         | IncludeNumberCompareField::encode(include_number_compare_);
+}
+
+
+// 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(no_reg) && rhs_.is(no_reg));
+
+  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 less: cc_name = "LT"; break;
+    case greater: cc_name = "GT"; break;
+    case less_equal: cc_name = "LE"; break;
+    case greater_equal: cc_name = "GE"; break;
+    case equal: cc_name = "EQ"; break;
+    case not_equal: cc_name = "NE"; break;
+    default: cc_name = "UnknownCondition"; break;
+  }
+
+  const char* strict_name = "";
+  if (strict_ && (cc_ == equal || cc_ == not_equal)) {
+    strict_name = "_STRICT";
+  }
+
+  const char* never_nan_nan_name = "";
+  if (never_nan_nan_ && (cc_ == equal || cc_ == not_equal)) {
+    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",
+               cc_name,
+               strict_name,
+               never_nan_nan_name,
+               include_number_compare_name);
+  return name_;
+}
+
+
+// -------------------------------------------------------------------------
+// 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.
+  STATIC_ASSERT(kSmiTag == 0);
+  __ test(object_, Immediate(kSmiTagMask));
+  __ j(zero, receiver_not_string_);
+
+  // Fetch the instance type of the receiver into result register.
+  __ mov(result_, FieldOperand(object_, HeapObject::kMapOffset));
+  __ movzx_b(result_, FieldOperand(result_, Map::kInstanceTypeOffset));
+  // If the receiver is not a string trigger the non-string case.
+  __ test(result_, Immediate(kIsNotStringMask));
+  __ j(not_zero, receiver_not_string_);
+
+  // If the index is non-smi trigger the non-smi case.
+  STATIC_ASSERT(kSmiTag == 0);
+  __ test(index_, Immediate(kSmiTagMask));
+  __ j(not_zero, &index_not_smi_);
+
+  // Put smi-tagged index into scratch register.
+  __ mov(scratch_, index_);
+  __ bind(&got_smi_index_);
+
+  // Check for index out of range.
+  __ cmp(scratch_, FieldOperand(object_, String::kLengthOffset));
+  __ j(above_equal, index_out_of_range_);
+
+  // We need special handling for non-flat strings.
+  STATIC_ASSERT(kSeqStringTag == 0);
+  __ test(result_, Immediate(kStringRepresentationMask));
+  __ j(zero, &flat_string);
+
+  // Handle non-flat strings.
+  __ test(result_, Immediate(kIsConsStringMask));
+  __ j(zero, &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.
+  __ cmp(FieldOperand(object_, ConsString::kSecondOffset),
+         Immediate(Factory::empty_string()));
+  __ j(not_equal, &call_runtime_);
+  // Get the first of the two strings and load its instance type.
+  __ mov(object_, FieldOperand(object_, ConsString::kFirstOffset));
+  __ mov(result_, FieldOperand(object_, HeapObject::kMapOffset));
+  __ movzx_b(result_, FieldOperand(result_, Map::kInstanceTypeOffset));
+  // If the first cons component is also non-flat, then go to runtime.
+  STATIC_ASSERT(kSeqStringTag == 0);
+  __ test(result_, Immediate(kStringRepresentationMask));
+  __ j(not_zero, &call_runtime_);
+
+  // Check for 1-byte or 2-byte string.
+  __ bind(&flat_string);
+  STATIC_ASSERT(kAsciiStringTag != 0);
+  __ test(result_, Immediate(kStringEncodingMask));
+  __ j(not_zero, &ascii_string);
+
+  // 2-byte string.
+  // Load the 2-byte character code into the result register.
+  STATIC_ASSERT(kSmiTag == 0 && kSmiTagSize == 1);
+  __ movzx_w(result_, FieldOperand(object_,
+                                   scratch_, times_1,  // Scratch is smi-tagged.
+                                   SeqTwoByteString::kHeaderSize));
+  __ jmp(&got_char_code);
+
+  // ASCII string.
+  // Load the byte into the result register.
+  __ bind(&ascii_string);
+  __ SmiUntag(scratch_);
+  __ movzx_b(result_, FieldOperand(object_,
+                                   scratch_, times_1,
+                                   SeqAsciiString::kHeaderSize));
+  __ bind(&got_char_code);
+  __ SmiTag(result_);
+  __ 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_, Factory::heap_number_map(), index_not_number_, true);
+  call_helper.BeforeCall(masm);
+  __ push(object_);
+  __ push(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);
+  }
+  if (!scratch_.is(eax)) {
+    // Save the conversion result before the pop instructions below
+    // have a chance to overwrite it.
+    __ mov(scratch_, eax);
+  }
+  __ pop(index_);
+  __ pop(object_);
+  // Reload the instance type.
+  __ mov(result_, FieldOperand(object_, HeapObject::kMapOffset));
+  __ movzx_b(result_, FieldOperand(result_, Map::kInstanceTypeOffset));
+  call_helper.AfterCall(masm);
+  // If index is still not a smi, it must be out of range.
+  STATIC_ASSERT(kSmiTag == 0);
+  __ test(scratch_, Immediate(kSmiTagMask));
+  __ j(not_zero, 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_);
+  __ push(index_);
+  __ CallRuntime(Runtime::kStringCharCodeAt, 2);
+  if (!result_.is(eax)) {
+    __ mov(result_, eax);
+  }
+  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));
+  __ test(code_,
+          Immediate(kSmiTagMask |
+                    ((~String::kMaxAsciiCharCode) << kSmiTagSize)));
+  __ j(not_zero, &slow_case_, not_taken);
+
+  __ Set(result_, Immediate(Factory::single_character_string_cache()));
+  STATIC_ASSERT(kSmiTag == 0);
+  STATIC_ASSERT(kSmiTagSize == 1);
+  STATIC_ASSERT(kSmiShiftSize == 0);
+  // At this point code register contains smi tagged ascii char code.
+  __ mov(result_, FieldOperand(result_,
+                               code_, times_half_pointer_size,
+                               FixedArray::kHeaderSize));
+  __ cmp(result_, Factory::undefined_value());
+  __ j(equal, &slow_case_, not_taken);
+  __ 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);
+  if (!result_.is(eax)) {
+    __ mov(result_, eax);
+  }
+  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);
+}
+
+
+void StringAddStub::Generate(MacroAssembler* masm) {
+  Label string_add_runtime;
+
+  // Load the two arguments.
+  __ mov(eax, Operand(esp, 2 * kPointerSize));  // First argument.
+  __ mov(edx, Operand(esp, 1 * kPointerSize));  // Second argument.
+
+  // Make sure that both arguments are strings if not known in advance.
+  if (string_check_) {
+    __ test(eax, Immediate(kSmiTagMask));
+    __ j(zero, &string_add_runtime);
+    __ CmpObjectType(eax, FIRST_NONSTRING_TYPE, ebx);
+    __ j(above_equal, &string_add_runtime);
+
+    // First argument is a a string, test second.
+    __ test(edx, Immediate(kSmiTagMask));
+    __ j(zero, &string_add_runtime);
+    __ CmpObjectType(edx, FIRST_NONSTRING_TYPE, ebx);
+    __ j(above_equal, &string_add_runtime);
+  }
+
+  // Both arguments are strings.
+  // eax: first string
+  // edx: second string
+  // Check if either of the strings are empty. In that case return the other.
+  Label second_not_zero_length, both_not_zero_length;
+  __ mov(ecx, FieldOperand(edx, String::kLengthOffset));
+  STATIC_ASSERT(kSmiTag == 0);
+  __ test(ecx, Operand(ecx));
+  __ j(not_zero, &second_not_zero_length);
+  // Second string is empty, result is first string which is already in eax.
+  __ IncrementCounter(&Counters::string_add_native, 1);
+  __ ret(2 * kPointerSize);
+  __ bind(&second_not_zero_length);
+  __ mov(ebx, FieldOperand(eax, String::kLengthOffset));
+  STATIC_ASSERT(kSmiTag == 0);
+  __ test(ebx, Operand(ebx));
+  __ j(not_zero, &both_not_zero_length);
+  // First string is empty, result is second string which is in edx.
+  __ mov(eax, edx);
+  __ IncrementCounter(&Counters::string_add_native, 1);
+  __ ret(2 * kPointerSize);
+
+  // Both strings are non-empty.
+  // eax: first string
+  // ebx: length of first string as a smi
+  // ecx: length of second string as a smi
+  // edx: second string
+  // Look at the length of the result of adding the two strings.
+  Label string_add_flat_result, longer_than_two;
+  __ bind(&both_not_zero_length);
+  __ add(ebx, Operand(ecx));
+  STATIC_ASSERT(Smi::kMaxValue == String::kMaxLength);
+  // Handle exceptionally long strings in the runtime system.
+  __ j(overflow, &string_add_runtime);
+  // Use the runtime system when adding two one character strings, as it
+  // contains optimizations for this specific case using the symbol table.
+  __ cmp(Operand(ebx), Immediate(Smi::FromInt(2)));
+  __ j(not_equal, &longer_than_two);
+
+  // Check that both strings are non-external ascii strings.
+  __ JumpIfNotBothSequentialAsciiStrings(eax, edx, ebx, ecx,
+                                         &string_add_runtime);
+
+  // Get the two characters forming the sub string.
+  __ movzx_b(ebx, FieldOperand(eax, SeqAsciiString::kHeaderSize));
+  __ movzx_b(ecx, FieldOperand(edx, 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, make_flat_ascii_string;
+  StringHelper::GenerateTwoCharacterSymbolTableProbe(
+      masm, ebx, ecx, eax, edx, edi, &make_two_character_string);
+  __ IncrementCounter(&Counters::string_add_native, 1);
+  __ ret(2 * kPointerSize);
+
+  __ bind(&make_two_character_string);
+  __ Set(ebx, Immediate(Smi::FromInt(2)));
+  __ jmp(&make_flat_ascii_string);
+
+  __ bind(&longer_than_two);
+  // Check if resulting string will be flat.
+  __ cmp(Operand(ebx), Immediate(Smi::FromInt(String::kMinNonFlatLength)));
+  __ j(below, &string_add_flat_result);
+
+  // 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.
+  Label non_ascii, allocated, ascii_data;
+  __ mov(edi, FieldOperand(eax, HeapObject::kMapOffset));
+  __ movzx_b(ecx, FieldOperand(edi, Map::kInstanceTypeOffset));
+  __ mov(edi, FieldOperand(edx, HeapObject::kMapOffset));
+  __ movzx_b(edi, FieldOperand(edi, Map::kInstanceTypeOffset));
+  __ and_(ecx, Operand(edi));
+  STATIC_ASSERT(kStringEncodingMask == kAsciiStringTag);
+  __ test(ecx, Immediate(kAsciiStringTag));
+  __ j(zero, &non_ascii);
+  __ bind(&ascii_data);
+  // Allocate an acsii cons string.
+  __ AllocateAsciiConsString(ecx, edi, no_reg, &string_add_runtime);
+  __ bind(&allocated);
+  // Fill the fields of the cons string.
+  if (FLAG_debug_code) __ AbortIfNotSmi(ebx);
+  __ mov(FieldOperand(ecx, ConsString::kLengthOffset), ebx);
+  __ mov(FieldOperand(ecx, ConsString::kHashFieldOffset),
+         Immediate(String::kEmptyHashField));
+  __ mov(FieldOperand(ecx, ConsString::kFirstOffset), eax);
+  __ mov(FieldOperand(ecx, ConsString::kSecondOffset), edx);
+  __ mov(eax, ecx);
+  __ IncrementCounter(&Counters::string_add_native, 1);
+  __ ret(2 * kPointerSize);
+  __ bind(&non_ascii);
+  // At least one of the strings is two-byte. Check whether it happens
+  // to contain only ascii characters.
+  // ecx: first instance type AND second instance type.
+  // edi: second instance type.
+  __ test(ecx, Immediate(kAsciiDataHintMask));
+  __ j(not_zero, &ascii_data);
+  __ mov(ecx, FieldOperand(eax, HeapObject::kMapOffset));
+  __ movzx_b(ecx, FieldOperand(ecx, Map::kInstanceTypeOffset));
+  __ xor_(edi, Operand(ecx));
+  STATIC_ASSERT(kAsciiStringTag != 0 && kAsciiDataHintTag != 0);
+  __ and_(edi, kAsciiStringTag | kAsciiDataHintTag);
+  __ cmp(edi, kAsciiStringTag | kAsciiDataHintTag);
+  __ j(equal, &ascii_data);
+  // Allocate a two byte cons string.
+  __ AllocateConsString(ecx, edi, no_reg, &string_add_runtime);
+  __ jmp(&allocated);
+
+  // Handle creating a flat result. First check that both strings are not
+  // external strings.
+  // eax: first string
+  // ebx: length of resulting flat string as a smi
+  // edx: second string
+  __ bind(&string_add_flat_result);
+  __ mov(ecx, FieldOperand(eax, HeapObject::kMapOffset));
+  __ movzx_b(ecx, FieldOperand(ecx, Map::kInstanceTypeOffset));
+  __ and_(ecx, kStringRepresentationMask);
+  __ cmp(ecx, kExternalStringTag);
+  __ j(equal, &string_add_runtime);
+  __ mov(ecx, FieldOperand(edx, HeapObject::kMapOffset));
+  __ movzx_b(ecx, FieldOperand(ecx, Map::kInstanceTypeOffset));
+  __ and_(ecx, kStringRepresentationMask);
+  __ cmp(ecx, kExternalStringTag);
+  __ j(equal, &string_add_runtime);
+  // Now check if both strings are ascii strings.
+  // eax: first string
+  // ebx: length of resulting flat string as a smi
+  // edx: second string
+  Label non_ascii_string_add_flat_result;
+  STATIC_ASSERT(kStringEncodingMask == kAsciiStringTag);
+  __ mov(ecx, FieldOperand(eax, HeapObject::kMapOffset));
+  __ test_b(FieldOperand(ecx, Map::kInstanceTypeOffset), kAsciiStringTag);
+  __ j(zero, &non_ascii_string_add_flat_result);
+  __ mov(ecx, FieldOperand(edx, HeapObject::kMapOffset));
+  __ test_b(FieldOperand(ecx, Map::kInstanceTypeOffset), kAsciiStringTag);
+  __ j(zero, &string_add_runtime);
+
+  __ bind(&make_flat_ascii_string);
+  // Both strings are ascii strings.  As they are short they are both flat.
+  // ebx: length of resulting flat string as a smi
+  __ SmiUntag(ebx);
+  __ AllocateAsciiString(eax, ebx, ecx, edx, edi, &string_add_runtime);
+  // eax: result string
+  __ mov(ecx, eax);
+  // Locate first character of result.
+  __ add(Operand(ecx), Immediate(SeqAsciiString::kHeaderSize - kHeapObjectTag));
+  // Load first argument and locate first character.
+  __ mov(edx, Operand(esp, 2 * kPointerSize));
+  __ mov(edi, FieldOperand(edx, String::kLengthOffset));
+  __ SmiUntag(edi);
+  __ add(Operand(edx), Immediate(SeqAsciiString::kHeaderSize - kHeapObjectTag));
+  // eax: result string
+  // ecx: first character of result
+  // edx: first char of first argument
+  // edi: length of first argument
+  StringHelper::GenerateCopyCharacters(masm, ecx, edx, edi, ebx, true);
+  // Load second argument and locate first character.
+  __ mov(edx, Operand(esp, 1 * kPointerSize));
+  __ mov(edi, FieldOperand(edx, String::kLengthOffset));
+  __ SmiUntag(edi);
+  __ add(Operand(edx), Immediate(SeqAsciiString::kHeaderSize - kHeapObjectTag));
+  // eax: result string
+  // ecx: next character of result
+  // edx: first char of second argument
+  // edi: length of second argument
+  StringHelper::GenerateCopyCharacters(masm, ecx, edx, edi, ebx, true);
+  __ IncrementCounter(&Counters::string_add_native, 1);
+  __ ret(2 * kPointerSize);
+
+  // Handle creating a flat two byte result.
+  // eax: first string - known to be two byte
+  // ebx: length of resulting flat string as a smi
+  // edx: second string
+  __ bind(&non_ascii_string_add_flat_result);
+  __ mov(ecx, FieldOperand(edx, HeapObject::kMapOffset));
+  __ test_b(FieldOperand(ecx, Map::kInstanceTypeOffset), kAsciiStringTag);
+  __ j(not_zero, &string_add_runtime);
+  // Both strings are two byte strings. As they are short they are both
+  // flat.
+  __ SmiUntag(ebx);
+  __ AllocateTwoByteString(eax, ebx, ecx, edx, edi, &string_add_runtime);
+  // eax: result string
+  __ mov(ecx, eax);
+  // Locate first character of result.
+  __ add(Operand(ecx),
+         Immediate(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
+  // Load first argument and locate first character.
+  __ mov(edx, Operand(esp, 2 * kPointerSize));
+  __ mov(edi, FieldOperand(edx, String::kLengthOffset));
+  __ SmiUntag(edi);
+  __ add(Operand(edx),
+         Immediate(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
+  // eax: result string
+  // ecx: first character of result
+  // edx: first char of first argument
+  // edi: length of first argument
+  StringHelper::GenerateCopyCharacters(masm, ecx, edx, edi, ebx, false);
+  // Load second argument and locate first character.
+  __ mov(edx, Operand(esp, 1 * kPointerSize));
+  __ mov(edi, FieldOperand(edx, String::kLengthOffset));
+  __ SmiUntag(edi);
+  __ add(Operand(edx), Immediate(SeqAsciiString::kHeaderSize - kHeapObjectTag));
+  // eax: result string
+  // ecx: next character of result
+  // edx: first char of second argument
+  // edi: length of second argument
+  StringHelper::GenerateCopyCharacters(masm, ecx, edx, edi, ebx, false);
+  __ IncrementCounter(&Counters::string_add_native, 1);
+  __ ret(2 * kPointerSize);
+
+  // Just jump to runtime to add the two strings.
+  __ bind(&string_add_runtime);
+  __ TailCallRuntime(Runtime::kStringAdd, 2, 1);
+}
+
+
+void StringHelper::GenerateCopyCharacters(MacroAssembler* masm,
+                                          Register dest,
+                                          Register src,
+                                          Register count,
+                                          Register scratch,
+                                          bool ascii) {
+  Label loop;
+  __ bind(&loop);
+  // This loop just copies one character at a time, as it is only used for very
+  // short strings.
+  if (ascii) {
+    __ mov_b(scratch, Operand(src, 0));
+    __ mov_b(Operand(dest, 0), scratch);
+    __ add(Operand(src), Immediate(1));
+    __ add(Operand(dest), Immediate(1));
+  } else {
+    __ mov_w(scratch, Operand(src, 0));
+    __ mov_w(Operand(dest, 0), scratch);
+    __ add(Operand(src), Immediate(2));
+    __ add(Operand(dest), Immediate(2));
+  }
+  __ sub(Operand(count), Immediate(1));
+  __ j(not_zero, &loop);
+}
+
+
+void StringHelper::GenerateCopyCharactersREP(MacroAssembler* masm,
+                                             Register dest,
+                                             Register src,
+                                             Register count,
+                                             Register scratch,
+                                             bool ascii) {
+  // Copy characters using rep movs of doublewords.
+  // The destination is aligned on a 4 byte boundary because we are
+  // copying to the beginning of a newly allocated string.
+  ASSERT(dest.is(edi));  // rep movs destination
+  ASSERT(src.is(esi));  // rep movs source
+  ASSERT(count.is(ecx));  // rep movs count
+  ASSERT(!scratch.is(dest));
+  ASSERT(!scratch.is(src));
+  ASSERT(!scratch.is(count));
+
+  // Nothing to do for zero characters.
+  Label done;
+  __ test(count, Operand(count));
+  __ j(zero, &done);
+
+  // Make count the number of bytes to copy.
+  if (!ascii) {
+    __ shl(count, 1);
+  }
+
+  // Don't enter the rep movs if there are less than 4 bytes to copy.
+  Label last_bytes;
+  __ test(count, Immediate(~3));
+  __ j(zero, &last_bytes);
+
+  // Copy from edi to esi using rep movs instruction.
+  __ mov(scratch, count);
+  __ sar(count, 2);  // Number of doublewords to copy.
+  __ cld();
+  __ rep_movs();
+
+  // Find number of bytes left.
+  __ mov(count, scratch);
+  __ and_(count, 3);
+
+  // Check if there are more bytes to copy.
+  __ bind(&last_bytes);
+  __ test(count, Operand(count));
+  __ j(zero, &done);
+
+  // Copy remaining characters.
+  Label loop;
+  __ bind(&loop);
+  __ mov_b(scratch, Operand(src, 0));
+  __ mov_b(Operand(dest, 0), scratch);
+  __ add(Operand(src), Immediate(1));
+  __ add(Operand(dest), Immediate(1));
+  __ sub(Operand(count), Immediate(1));
+  __ j(not_zero, &loop);
+
+  __ bind(&done);
+}
+
+
+void StringHelper::GenerateTwoCharacterSymbolTableProbe(MacroAssembler* masm,
+                                                        Register c1,
+                                                        Register c2,
+                                                        Register scratch1,
+                                                        Register scratch2,
+                                                        Register scratch3,
+                                                        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;
+  __ mov(scratch, c1);
+  __ sub(Operand(scratch), Immediate(static_cast<int>('0')));
+  __ cmp(Operand(scratch), Immediate(static_cast<int>('9' - '0')));
+  __ j(above, &not_array_index);
+  __ mov(scratch, c2);
+  __ sub(Operand(scratch), Immediate(static_cast<int>('0')));
+  __ cmp(Operand(scratch), Immediate(static_cast<int>('9' - '0')));
+  __ j(below_equal, not_found);
+
+  __ bind(&not_array_index);
+  // Calculate the two character string hash.
+  Register hash = scratch1;
+  GenerateHashInit(masm, hash, c1, scratch);
+  GenerateHashAddCharacter(masm, hash, c2, scratch);
+  GenerateHashGetHash(masm, hash, scratch);
+
+  // Collect the two characters in a register.
+  Register chars = c1;
+  __ shl(c2, kBitsPerByte);
+  __ or_(chars, Operand(c2));
+
+  // chars: two character string, char 1 in byte 0 and char 2 in byte 1.
+  // hash:  hash of two character string.
+
+  // Load the symbol table.
+  Register symbol_table = c2;
+  ExternalReference roots_address = ExternalReference::roots_address();
+  __ mov(scratch, Immediate(Heap::kSymbolTableRootIndex));
+  __ mov(symbol_table,
+         Operand::StaticArray(scratch, times_pointer_size, roots_address));
+
+  // Calculate capacity mask from the symbol table capacity.
+  Register mask = scratch2;
+  __ mov(mask, FieldOperand(symbol_table, SymbolTable::kCapacityOffset));
+  __ SmiUntag(mask);
+  __ sub(Operand(mask), Immediate(1));
+
+  // Registers
+  // chars:        two character string, char 1 in byte 0 and char 2 in byte 1.
+  // hash:         hash of two character string
+  // symbol_table: symbol table
+  // mask:         capacity mask
+  // scratch:      -
+
+  // Perform a number of probes in the symbol table.
+  static const int kProbes = 4;
+  Label found_in_symbol_table;
+  Label next_probe[kProbes], next_probe_pop_mask[kProbes];
+  for (int i = 0; i < kProbes; i++) {
+    // Calculate entry in symbol table.
+    __ mov(scratch, hash);
+    if (i > 0) {
+      __ add(Operand(scratch), Immediate(SymbolTable::GetProbeOffset(i)));
+    }
+    __ and_(scratch, Operand(mask));
+
+    // Load the entry from the symbol table.
+    Register candidate = scratch;  // Scratch register contains candidate.
+    STATIC_ASSERT(SymbolTable::kEntrySize == 1);
+    __ mov(candidate,
+           FieldOperand(symbol_table,
+                        scratch,
+                        times_pointer_size,
+                        SymbolTable::kElementsStartOffset));
+
+    // If entry is undefined no string with this hash can be found.
+    __ cmp(candidate, Factory::undefined_value());
+    __ j(equal, not_found);
+
+    // If length is not 2 the string is not a candidate.
+    __ cmp(FieldOperand(candidate, String::kLengthOffset),
+           Immediate(Smi::FromInt(2)));
+    __ j(not_equal, &next_probe[i]);
+
+    // As we are out of registers save the mask on the stack and use that
+    // register as a temporary.
+    __ push(mask);
+    Register temp = mask;
+
+    // Check that the candidate is a non-external ascii string.
+    __ mov(temp, FieldOperand(candidate, HeapObject::kMapOffset));
+    __ movzx_b(temp, FieldOperand(temp, Map::kInstanceTypeOffset));
+    __ JumpIfInstanceTypeIsNotSequentialAscii(
+        temp, temp, &next_probe_pop_mask[i]);
+
+    // Check if the two characters match.
+    __ mov(temp, FieldOperand(candidate, SeqAsciiString::kHeaderSize));
+    __ and_(temp, 0x0000ffff);
+    __ cmp(chars, Operand(temp));
+    __ j(equal, &found_in_symbol_table);
+    __ bind(&next_probe_pop_mask[i]);
+    __ pop(mask);
+    __ 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);
+  __ pop(mask);  // Pop saved mask from the stack.
+  if (!result.is(eax)) {
+    __ mov(eax, result);
+  }
+}
+
+
+void StringHelper::GenerateHashInit(MacroAssembler* masm,
+                                    Register hash,
+                                    Register character,
+                                    Register scratch) {
+  // hash = character + (character << 10);
+  __ mov(hash, character);
+  __ shl(hash, 10);
+  __ add(hash, Operand(character));
+  // hash ^= hash >> 6;
+  __ mov(scratch, hash);
+  __ sar(scratch, 6);
+  __ xor_(hash, Operand(scratch));
+}
+
+
+void StringHelper::GenerateHashAddCharacter(MacroAssembler* masm,
+                                            Register hash,
+                                            Register character,
+                                            Register scratch) {
+  // hash += character;
+  __ add(hash, Operand(character));
+  // hash += hash << 10;
+  __ mov(scratch, hash);
+  __ shl(scratch, 10);
+  __ add(hash, Operand(scratch));
+  // hash ^= hash >> 6;
+  __ mov(scratch, hash);
+  __ sar(scratch, 6);
+  __ xor_(hash, Operand(scratch));
+}
+
+
+void StringHelper::GenerateHashGetHash(MacroAssembler* masm,
+                                       Register hash,
+                                       Register scratch) {
+  // hash += hash << 3;
+  __ mov(scratch, hash);
+  __ shl(scratch, 3);
+  __ add(hash, Operand(scratch));
+  // hash ^= hash >> 11;
+  __ mov(scratch, hash);
+  __ sar(scratch, 11);
+  __ xor_(hash, Operand(scratch));
+  // hash += hash << 15;
+  __ mov(scratch, hash);
+  __ shl(scratch, 15);
+  __ add(hash, Operand(scratch));
+
+  // if (hash == 0) hash = 27;
+  Label hash_not_zero;
+  __ test(hash, Operand(hash));
+  __ j(not_zero, &hash_not_zero);
+  __ mov(hash, Immediate(27));
+  __ bind(&hash_not_zero);
+}
+
+
+void SubStringStub::Generate(MacroAssembler* masm) {
+  Label runtime;
+
+  // Stack frame on entry.
+  //  esp[0]: return address
+  //  esp[4]: to
+  //  esp[8]: from
+  //  esp[12]: string
+
+  // Make sure first argument is a string.
+  __ mov(eax, Operand(esp, 3 * kPointerSize));
+  STATIC_ASSERT(kSmiTag == 0);
+  __ test(eax, Immediate(kSmiTagMask));
+  __ j(zero, &runtime);
+  Condition is_string = masm->IsObjectStringType(eax, ebx, ebx);
+  __ j(NegateCondition(is_string), &runtime);
+
+  // eax: string
+  // ebx: instance type
+
+  // Calculate length of sub string using the smi values.
+  Label result_longer_than_two;
+  __ mov(ecx, Operand(esp, 1 * kPointerSize));  // To index.
+  __ test(ecx, Immediate(kSmiTagMask));
+  __ j(not_zero, &runtime);
+  __ mov(edx, Operand(esp, 2 * kPointerSize));  // From index.
+  __ test(edx, Immediate(kSmiTagMask));
+  __ j(not_zero, &runtime);
+  __ sub(ecx, Operand(edx));
+  __ cmp(ecx, FieldOperand(eax, String::kLengthOffset));
+  Label return_eax;
+  __ j(equal, &return_eax);
+  // 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.
+  __ SmiUntag(ecx);  // Result length is no longer smi.
+  __ cmp(ecx, 2);
+  __ j(greater, &result_longer_than_two);
+  __ j(less, &runtime);
+
+  // Sub string of length 2 requested.
+  // eax: string
+  // ebx: instance type
+  // ecx: sub string length (value is 2)
+  // edx: from index (smi)
+  __ JumpIfInstanceTypeIsNotSequentialAscii(ebx, ebx, &runtime);
+
+  // Get the two characters forming the sub string.
+  __ SmiUntag(edx);  // From index is no longer smi.
+  __ movzx_b(ebx, FieldOperand(eax, edx, times_1, SeqAsciiString::kHeaderSize));
+  __ movzx_b(ecx,
+             FieldOperand(eax, edx, times_1, SeqAsciiString::kHeaderSize + 1));
+
+  // Try to lookup two character string in symbol table.
+  Label make_two_character_string;
+  StringHelper::GenerateTwoCharacterSymbolTableProbe(
+      masm, ebx, ecx, eax, edx, edi, &make_two_character_string);
+  __ ret(3 * kPointerSize);
+
+  __ bind(&make_two_character_string);
+  // Setup registers for allocating the two character string.
+  __ mov(eax, Operand(esp, 3 * kPointerSize));
+  __ mov(ebx, FieldOperand(eax, HeapObject::kMapOffset));
+  __ movzx_b(ebx, FieldOperand(ebx, Map::kInstanceTypeOffset));
+  __ Set(ecx, Immediate(2));
+
+  __ bind(&result_longer_than_two);
+  // eax: string
+  // ebx: instance type
+  // ecx: result string length
+  // Check for flat ascii string
+  Label non_ascii_flat;
+  __ JumpIfInstanceTypeIsNotSequentialAscii(ebx, ebx, &non_ascii_flat);
+
+  // Allocate the result.
+  __ AllocateAsciiString(eax, ecx, ebx, edx, edi, &runtime);
+
+  // eax: result string
+  // ecx: result string length
+  __ mov(edx, esi);  // esi used by following code.
+  // Locate first character of result.
+  __ mov(edi, eax);
+  __ add(Operand(edi), Immediate(SeqAsciiString::kHeaderSize - kHeapObjectTag));
+  // Load string argument and locate character of sub string start.
+  __ mov(esi, Operand(esp, 3 * kPointerSize));
+  __ add(Operand(esi), Immediate(SeqAsciiString::kHeaderSize - kHeapObjectTag));
+  __ mov(ebx, Operand(esp, 2 * kPointerSize));  // from
+  __ SmiUntag(ebx);
+  __ add(esi, Operand(ebx));
+
+  // eax: result string
+  // ecx: result length
+  // edx: original value of esi
+  // edi: first character of result
+  // esi: character of sub string start
+  StringHelper::GenerateCopyCharactersREP(masm, edi, esi, ecx, ebx, true);
+  __ mov(esi, edx);  // Restore esi.
+  __ IncrementCounter(&Counters::sub_string_native, 1);
+  __ ret(3 * kPointerSize);
+
+  __ bind(&non_ascii_flat);
+  // eax: string
+  // ebx: instance type & kStringRepresentationMask | kStringEncodingMask
+  // ecx: result string length
+  // Check for flat two byte string
+  __ cmp(ebx, kSeqStringTag | kTwoByteStringTag);
+  __ j(not_equal, &runtime);
+
+  // Allocate the result.
+  __ AllocateTwoByteString(eax, ecx, ebx, edx, edi, &runtime);
+
+  // eax: result string
+  // ecx: result string length
+  __ mov(edx, esi);  // esi used by following code.
+  // Locate first character of result.
+  __ mov(edi, eax);
+  __ add(Operand(edi),
+         Immediate(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
+  // Load string argument and locate character of sub string start.
+  __ mov(esi, Operand(esp, 3 * kPointerSize));
+  __ add(Operand(esi),
+         Immediate(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
+  __ mov(ebx, Operand(esp, 2 * kPointerSize));  // from
+  // As from is a smi it is 2 times the value which matches the size of a two
+  // byte character.
+  STATIC_ASSERT(kSmiTag == 0);
+  STATIC_ASSERT(kSmiTagSize + kSmiShiftSize == 1);
+  __ add(esi, Operand(ebx));
+
+  // eax: result string
+  // ecx: result length
+  // edx: original value of esi
+  // edi: first character of result
+  // esi: character of sub string start
+  StringHelper::GenerateCopyCharactersREP(masm, edi, esi, ecx, ebx, false);
+  __ mov(esi, edx);  // Restore esi.
+
+  __ bind(&return_eax);
+  __ IncrementCounter(&Counters::sub_string_native, 1);
+  __ ret(3 * kPointerSize);
+
+  // 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) {
+  Label result_not_equal;
+  Label result_greater;
+  Label compare_lengths;
+
+  __ IncrementCounter(&Counters::string_compare_native, 1);
+
+  // Find minimum length.
+  Label left_shorter;
+  __ mov(scratch1, FieldOperand(left, String::kLengthOffset));
+  __ mov(scratch3, scratch1);
+  __ sub(scratch3, FieldOperand(right, String::kLengthOffset));
+
+  Register length_delta = scratch3;
+
+  __ j(less_equal, &left_shorter);
+  // Right string is shorter. Change scratch1 to be length of right string.
+  __ sub(scratch1, Operand(length_delta));
+  __ bind(&left_shorter);
+
+  Register min_length = scratch1;
+
+  // If either length is zero, just compare lengths.
+  __ test(min_length, Operand(min_length));
+  __ j(zero, &compare_lengths);
+
+  // Change index to run from -min_length to -1 by adding min_length
+  // to string start. This means that loop ends when index reaches zero,
+  // which doesn't need an additional compare.
+  __ SmiUntag(min_length);
+  __ lea(left,
+         FieldOperand(left,
+                      min_length, times_1,
+                      SeqAsciiString::kHeaderSize));
+  __ lea(right,
+         FieldOperand(right,
+                      min_length, times_1,
+                      SeqAsciiString::kHeaderSize));
+  __ neg(min_length);
+
+  Register index = min_length;  // index = -min_length;
+
+  {
+    // Compare loop.
+    Label loop;
+    __ bind(&loop);
+    // Compare characters.
+    __ mov_b(scratch2, Operand(left, index, times_1, 0));
+    __ cmpb(scratch2, Operand(right, index, times_1, 0));
+    __ j(not_equal, &result_not_equal);
+    __ add(Operand(index), Immediate(1));
+    __ j(not_zero, &loop);
+  }
+
+  // Compare lengths -  strings up to min-length are equal.
+  __ bind(&compare_lengths);
+  __ test(length_delta, Operand(length_delta));
+  __ j(not_zero, &result_not_equal);
+
+  // Result is EQUAL.
+  STATIC_ASSERT(EQUAL == 0);
+  STATIC_ASSERT(kSmiTag == 0);
+  __ Set(eax, Immediate(Smi::FromInt(EQUAL)));
+  __ ret(0);
+
+  __ bind(&result_not_equal);
+  __ j(greater, &result_greater);
+
+  // Result is LESS.
+  __ Set(eax, Immediate(Smi::FromInt(LESS)));
+  __ ret(0);
+
+  // Result is GREATER.
+  __ bind(&result_greater);
+  __ Set(eax, Immediate(Smi::FromInt(GREATER)));
+  __ ret(0);
+}
+
+
+void StringCompareStub::Generate(MacroAssembler* masm) {
+  Label runtime;
+
+  // Stack frame on entry.
+  //  esp[0]: return address
+  //  esp[4]: right string
+  //  esp[8]: left string
+
+  __ mov(edx, Operand(esp, 2 * kPointerSize));  // left
+  __ mov(eax, Operand(esp, 1 * kPointerSize));  // right
+
+  Label not_same;
+  __ cmp(edx, Operand(eax));
+  __ j(not_equal, &not_same);
+  STATIC_ASSERT(EQUAL == 0);
+  STATIC_ASSERT(kSmiTag == 0);
+  __ Set(eax, Immediate(Smi::FromInt(EQUAL)));
+  __ IncrementCounter(&Counters::string_compare_native, 1);
+  __ ret(2 * kPointerSize);
+
+  __ bind(&not_same);
+
+  // Check that both objects are sequential ascii strings.
+  __ JumpIfNotBothSequentialAsciiStrings(edx, eax, ecx, ebx, &runtime);
+
+  // Compare flat ascii strings.
+  // Drop arguments from the stack.
+  __ pop(ecx);
+  __ add(Operand(esp), Immediate(2 * kPointerSize));
+  __ push(ecx);
+  GenerateCompareFlatAsciiStrings(masm, edx, eax, ecx, ebx, edi);
+
+  // Call the runtime; it returns -1 (less), 0 (equal), or 1 (greater)
+  // tagged as a small integer.
+  __ bind(&runtime);
+  __ TailCallRuntime(Runtime::kStringCompare, 2, 1);
+}
+
+#undef __
+
+} }  // namespace v8::internal
+
+#endif  // V8_TARGET_ARCH_IA32