root/src/mips/code-stubs-mips.cc

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DEFINITIONS

This source file includes following definitions.
  1. EmitCheckForHeapNumber
  2. Generate
  3. Generate
  4. Generate
  5. Generate
  6. GenerateFastCloneShallowArrayCommon
  7. Generate
  8. Generate
  9. zeros_
  10. MajorKey
  11. MinorKey
  12. Generate
  13. LoadSmis
  14. LoadOperands
  15. LoadNumber
  16. ConvertNumberToInt32
  17. ConvertIntToDouble
  18. LoadNumberAsInt32Double
  19. LoadNumberAsInt32
  20. DoubleIs32BitInteger
  21. CallCCodeForDoubleOperation
  22. IsPregenerated
  23. GenerateFixedRegStubsAheadOfTime
  24. Generate
  25. EmitIdenticalObjectComparison
  26. EmitSmiNonsmiComparison
  27. EmitNanCheck
  28. EmitTwoNonNanDoubleComparison
  29. EmitStrictTwoHeapObjectCompare
  30. EmitCheckForTwoHeapNumbers
  31. EmitCheckForSymbolsOrObjects
  32. GenerateLookupNumberStringCache
  33. Generate
  34. Generate
  35. Generate
  36. CheckOddball
  37. GenerateTypeTransition
  38. Generate
  39. PrintName
  40. Generate
  41. GenerateTypeTransition
  42. GenerateSmiStub
  43. GenerateSmiStubSub
  44. GenerateSmiStubBitNot
  45. GenerateSmiCodeSub
  46. GenerateSmiCodeBitNot
  47. GenerateHeapNumberStub
  48. GenerateHeapNumberStubSub
  49. GenerateHeapNumberStubBitNot
  50. GenerateHeapNumberCodeSub
  51. GenerateHeapNumberCodeBitNot
  52. GenerateGenericStub
  53. GenerateGenericStubSub
  54. GenerateGenericStubBitNot
  55. GenerateGenericCodeFallback
  56. GenerateTypeTransition
  57. GenerateTypeTransitionWithSavedArgs
  58. Generate
  59. PrintName
  60. GenerateSmiSmiOperation
  61. GenerateFPOperation
  62. GenerateSmiCode
  63. GenerateSmiStub
  64. GenerateStringStub
  65. GenerateBothStringStub
  66. GenerateInt32Stub
  67. GenerateOddballStub
  68. GenerateHeapNumberStub
  69. GenerateGeneric
  70. GenerateAddStrings
  71. GenerateCallRuntime
  72. GenerateHeapResultAllocation
  73. GenerateRegisterArgsPush
  74. Generate
  75. GenerateCallCFunction
  76. RuntimeFunction
  77. Generate
  78. Generate
  79. Generate
  80. NeedsImmovableCode
  81. IsPregenerated
  82. GenerateStubsAheadOfTime
  83. GenerateFPStubs
  84. GenerateAheadOfTime
  85. GenerateCore
  86. Generate
  87. GenerateBody
  88. Generate
  89. left
  90. right
  91. GenerateReadElement
  92. GenerateNewNonStrictSlow
  93. GenerateNewNonStrictFast
  94. GenerateNewStrict
  95. Generate
  96. Generate
  97. GenerateRecordCallTarget
  98. Generate
  99. Generate
  100. PrintName
  101. MinorKey
  102. GenerateFast
  103. GenerateSlow
  104. GenerateFast
  105. GenerateSlow
  106. GenerateFast
  107. GenerateSlow
  108. GenerateCopyCharacters
  109. GenerateCopyCharactersLong
  110. GenerateTwoCharacterSymbolTableProbe
  111. GenerateHashInit
  112. GenerateHashAddCharacter
  113. GenerateHashGetHash
  114. Generate
  115. GenerateFlatAsciiStringEquals
  116. GenerateCompareFlatAsciiStrings
  117. GenerateAsciiCharsCompareLoop
  118. Generate
  119. Generate
  120. GenerateConvertArgument
  121. GenerateSmis
  122. GenerateHeapNumbers
  123. GenerateSymbols
  124. GenerateStrings
  125. GenerateObjects
  126. GenerateKnownObjects
  127. GenerateMiss
  128. Generate
  129. GenerateCall
  130. GenerateCall
  131. GenerateNegativeLookup
  132. GeneratePositiveLookup
  133. Generate
  134. IsPregenerated
  135. IsPregenerated
  136. GenerateFixedRegStubsAheadOfTime
  137. GenerateFixedRegStubsAheadOfTime
  138. Generate
  139. GenerateIncremental
  140. InformIncrementalMarker
  141. CheckNeedsToInformIncrementalMarker
  142. Generate

// Copyright 2012 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_MIPS)

#include "bootstrapper.h"
#include "code-stubs.h"
#include "codegen.h"
#include "regexp-macro-assembler.h"

namespace v8 {
namespace internal {


#define __ ACCESS_MASM(masm)

static void EmitIdenticalObjectComparison(MacroAssembler* masm,
                                          Label* slow,
                                          Condition cc,
                                          bool never_nan_nan);
static void EmitSmiNonsmiComparison(MacroAssembler* masm,
                                    Register lhs,
                                    Register rhs,
                                    Label* rhs_not_nan,
                                    Label* slow,
                                    bool strict);
static void EmitTwoNonNanDoubleComparison(MacroAssembler* masm, Condition cc);
static void EmitStrictTwoHeapObjectCompare(MacroAssembler* masm,
                                           Register lhs,
                                           Register rhs);


// Check if the operand is a heap number.
static void EmitCheckForHeapNumber(MacroAssembler* masm, Register operand,
                                   Register scratch1, Register scratch2,
                                   Label* not_a_heap_number) {
  __ lw(scratch1, FieldMemOperand(operand, HeapObject::kMapOffset));
  __ LoadRoot(scratch2, Heap::kHeapNumberMapRootIndex);
  __ Branch(not_a_heap_number, ne, scratch1, Operand(scratch2));
}


void ToNumberStub::Generate(MacroAssembler* masm) {
  // The ToNumber stub takes one argument in a0.
  Label check_heap_number, call_builtin;
  __ JumpIfNotSmi(a0, &check_heap_number);
  __ Ret(USE_DELAY_SLOT);
  __ mov(v0, a0);

  __ bind(&check_heap_number);
  EmitCheckForHeapNumber(masm, a0, a1, t0, &call_builtin);
  __ Ret(USE_DELAY_SLOT);
  __ mov(v0, a0);

  __ bind(&call_builtin);
  __ push(a0);
  __ InvokeBuiltin(Builtins::TO_NUMBER, JUMP_FUNCTION);
}


void FastNewClosureStub::Generate(MacroAssembler* masm) {
  // Create a new closure from the given function info in new
  // space. Set the context to the current context in cp.
  Counters* counters = masm->isolate()->counters();

  Label gc;

  // Pop the function info from the stack.
  __ pop(a3);

  // Attempt to allocate new JSFunction in new space.
  __ AllocateInNewSpace(JSFunction::kSize,
                        v0,
                        a1,
                        a2,
                        &gc,
                        TAG_OBJECT);

  __ IncrementCounter(counters->fast_new_closure_total(), 1, t2, t3);

  int map_index = (language_mode_ == CLASSIC_MODE)
      ? Context::FUNCTION_MAP_INDEX
      : Context::STRICT_MODE_FUNCTION_MAP_INDEX;

  // Compute the function map in the current global context and set that
  // as the map of the allocated object.
  __ lw(a2, MemOperand(cp, Context::SlotOffset(Context::GLOBAL_INDEX)));
  __ lw(a2, FieldMemOperand(a2, GlobalObject::kGlobalContextOffset));
  __ lw(t1, MemOperand(a2, Context::SlotOffset(map_index)));
  __ sw(t1, FieldMemOperand(v0, HeapObject::kMapOffset));

  // Initialize the rest of the function. We don't have to update the
  // write barrier because the allocated object is in new space.
  __ LoadRoot(a1, Heap::kEmptyFixedArrayRootIndex);
  __ LoadRoot(t1, Heap::kTheHoleValueRootIndex);
  __ sw(a1, FieldMemOperand(v0, JSObject::kPropertiesOffset));
  __ sw(a1, FieldMemOperand(v0, JSObject::kElementsOffset));
  __ sw(t1, FieldMemOperand(v0, JSFunction::kPrototypeOrInitialMapOffset));
  __ sw(a3, FieldMemOperand(v0, JSFunction::kSharedFunctionInfoOffset));
  __ sw(cp, FieldMemOperand(v0, JSFunction::kContextOffset));
  __ sw(a1, FieldMemOperand(v0, JSFunction::kLiteralsOffset));

  // Initialize the code pointer in the function to be the one
  // found in the shared function info object.
  // But first check if there is an optimized version for our context.
  Label check_optimized;
  Label install_unoptimized;
  if (FLAG_cache_optimized_code) {
    __ lw(a1,
          FieldMemOperand(a3, SharedFunctionInfo::kOptimizedCodeMapOffset));
    __ And(at, a1, a1);
    __ Branch(&check_optimized, ne, at, Operand(zero_reg));
  }
  __ bind(&install_unoptimized);
  __ LoadRoot(t0, Heap::kUndefinedValueRootIndex);
  __ sw(t0, FieldMemOperand(v0, JSFunction::kNextFunctionLinkOffset));
  __ lw(a3, FieldMemOperand(a3, SharedFunctionInfo::kCodeOffset));
  __ Addu(a3, a3, Operand(Code::kHeaderSize - kHeapObjectTag));

  // Return result. The argument function info has been popped already.
  __ sw(a3, FieldMemOperand(v0, JSFunction::kCodeEntryOffset));
  __ Ret();

  __ bind(&check_optimized);

  __ IncrementCounter(counters->fast_new_closure_try_optimized(), 1, t2, t3);

  // a2 holds global context, a1 points to fixed array of 3-element entries
  // (global context, optimized code, literals).
  // The optimized code map must never be empty, so check the first elements.
  Label install_optimized;
  // Speculatively move code object into t0.
  __ lw(t0, FieldMemOperand(a1, FixedArray::kHeaderSize + kPointerSize));
  __ lw(t1, FieldMemOperand(a1, FixedArray::kHeaderSize));
  __ Branch(&install_optimized, eq, a2, Operand(t1));

  // Iterate through the rest of map backwards.  t0 holds an index as a Smi.
  Label loop;
  __ lw(t0, FieldMemOperand(a1, FixedArray::kLengthOffset));
  __ bind(&loop);
  // Do not double check first entry.

  __ Branch(&install_unoptimized, eq, t0,
            Operand(Smi::FromInt(SharedFunctionInfo::kEntryLength)));
  __ Subu(t0, t0, Operand(
      Smi::FromInt(SharedFunctionInfo::kEntryLength)));  // Skip an entry.
  __ Addu(t1, a1, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
  __ sll(at, t0, kPointerSizeLog2 - kSmiTagSize);
  __ Addu(t1, t1, Operand(at));
  __ lw(t1, MemOperand(t1));
  __ Branch(&loop, ne, a2, Operand(t1));
  // Hit: fetch the optimized code.
  __ Addu(t1, a1, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
  __ sll(at, t0, kPointerSizeLog2 - kSmiTagSize);
  __ Addu(t1, t1, Operand(at));
  __ Addu(t1, t1, Operand(kPointerSize));
  __ lw(t0, MemOperand(t1));

  __ bind(&install_optimized);
  __ IncrementCounter(counters->fast_new_closure_install_optimized(),
                      1, t2, t3);

  // TODO(fschneider): Idea: store proper code pointers in the map and either
  // unmangle them on marking or do nothing as the whole map is discarded on
  // major GC anyway.
  __ Addu(t0, t0, Operand(Code::kHeaderSize - kHeapObjectTag));
  __ sw(t0, FieldMemOperand(v0, JSFunction::kCodeEntryOffset));

  // Now link a function into a list of optimized functions.
  __ lw(t0, ContextOperand(a2, Context::OPTIMIZED_FUNCTIONS_LIST));

  __ sw(t0, FieldMemOperand(v0, JSFunction::kNextFunctionLinkOffset));
  // No need for write barrier as JSFunction (eax) is in the new space.

  __ sw(v0, ContextOperand(a2, Context::OPTIMIZED_FUNCTIONS_LIST));
  // Store JSFunction (eax) into edx before issuing write barrier as
  // it clobbers all the registers passed.
  __ mov(t0, v0);
  __ RecordWriteContextSlot(
      a2,
      Context::SlotOffset(Context::OPTIMIZED_FUNCTIONS_LIST),
      t0,
      a1,
      kRAHasNotBeenSaved,
      kDontSaveFPRegs);

  // Return result. The argument function info has been popped already.
  __ Ret();

  // Create a new closure through the slower runtime call.
  __ bind(&gc);
  __ LoadRoot(t0, Heap::kFalseValueRootIndex);
  __ Push(cp, a3, t0);
  __ TailCallRuntime(Runtime::kNewClosure, 3, 1);
}


void FastNewContextStub::Generate(MacroAssembler* masm) {
  // Try to allocate the context in new space.
  Label gc;
  int length = slots_ + Context::MIN_CONTEXT_SLOTS;

  // Attempt to allocate the context in new space.
  __ AllocateInNewSpace(FixedArray::SizeFor(length),
                        v0,
                        a1,
                        a2,
                        &gc,
                        TAG_OBJECT);

  // Load the function from the stack.
  __ lw(a3, MemOperand(sp, 0));

  // Set up the object header.
  __ LoadRoot(a1, Heap::kFunctionContextMapRootIndex);
  __ li(a2, Operand(Smi::FromInt(length)));
  __ sw(a2, FieldMemOperand(v0, FixedArray::kLengthOffset));
  __ sw(a1, FieldMemOperand(v0, HeapObject::kMapOffset));

  // Set up the fixed slots, copy the global object from the previous context.
  __ lw(a2, MemOperand(cp, Context::SlotOffset(Context::GLOBAL_INDEX)));
  __ li(a1, Operand(Smi::FromInt(0)));
  __ sw(a3, MemOperand(v0, Context::SlotOffset(Context::CLOSURE_INDEX)));
  __ sw(cp, MemOperand(v0, Context::SlotOffset(Context::PREVIOUS_INDEX)));
  __ sw(a1, MemOperand(v0, Context::SlotOffset(Context::EXTENSION_INDEX)));
  __ sw(a2, MemOperand(v0, Context::SlotOffset(Context::GLOBAL_INDEX)));

  // Initialize the rest of the slots to undefined.
  __ LoadRoot(a1, Heap::kUndefinedValueRootIndex);
  for (int i = Context::MIN_CONTEXT_SLOTS; i < length; i++) {
    __ sw(a1, MemOperand(v0, Context::SlotOffset(i)));
  }

  // Remove the on-stack argument and return.
  __ mov(cp, v0);
  __ DropAndRet(1);

  // Need to collect. Call into runtime system.
  __ bind(&gc);
  __ TailCallRuntime(Runtime::kNewFunctionContext, 1, 1);
}


void FastNewBlockContextStub::Generate(MacroAssembler* masm) {
  // Stack layout on entry:
  //
  // [sp]: function.
  // [sp + kPointerSize]: serialized scope info

  // Try to allocate the context in new space.
  Label gc;
  int length = slots_ + Context::MIN_CONTEXT_SLOTS;
  __ AllocateInNewSpace(FixedArray::SizeFor(length),
                        v0, a1, a2, &gc, TAG_OBJECT);

  // Load the function from the stack.
  __ lw(a3, MemOperand(sp, 0));

  // Load the serialized scope info from the stack.
  __ lw(a1, MemOperand(sp, 1 * kPointerSize));

  // Set up the object header.
  __ LoadRoot(a2, Heap::kBlockContextMapRootIndex);
  __ sw(a2, FieldMemOperand(v0, HeapObject::kMapOffset));
  __ li(a2, Operand(Smi::FromInt(length)));
  __ sw(a2, FieldMemOperand(v0, FixedArray::kLengthOffset));

  // If this block context is nested in the global context we get a smi
  // sentinel instead of a function. The block context should get the
  // canonical empty function of the global context as its closure which
  // we still have to look up.
  Label after_sentinel;
  __ JumpIfNotSmi(a3, &after_sentinel);
  if (FLAG_debug_code) {
    const char* message = "Expected 0 as a Smi sentinel";
    __ Assert(eq, message, a3, Operand(zero_reg));
  }
  __ lw(a3, GlobalObjectOperand());
  __ lw(a3, FieldMemOperand(a3, GlobalObject::kGlobalContextOffset));
  __ lw(a3, ContextOperand(a3, Context::CLOSURE_INDEX));
  __ bind(&after_sentinel);

  // Set up the fixed slots, copy the global object from the previous context.
  __ lw(a2, ContextOperand(cp, Context::GLOBAL_INDEX));
  __ sw(a3, ContextOperand(v0, Context::CLOSURE_INDEX));
  __ sw(cp, ContextOperand(v0, Context::PREVIOUS_INDEX));
  __ sw(a1, ContextOperand(v0, Context::EXTENSION_INDEX));
  __ sw(a2, ContextOperand(v0, Context::GLOBAL_INDEX));

  // Initialize the rest of the slots to the hole value.
  __ LoadRoot(a1, Heap::kTheHoleValueRootIndex);
  for (int i = 0; i < slots_; i++) {
    __ sw(a1, ContextOperand(v0, i + Context::MIN_CONTEXT_SLOTS));
  }

  // Remove the on-stack argument and return.
  __ mov(cp, v0);
  __ DropAndRet(2);

  // Need to collect. Call into runtime system.
  __ bind(&gc);
  __ TailCallRuntime(Runtime::kPushBlockContext, 2, 1);
}


static void GenerateFastCloneShallowArrayCommon(
    MacroAssembler* masm,
    int length,
    FastCloneShallowArrayStub::Mode mode,
    Label* fail) {
  // Registers on entry:
  // a3: boilerplate literal array.
  ASSERT(mode != FastCloneShallowArrayStub::CLONE_ANY_ELEMENTS);

  // All sizes here are multiples of kPointerSize.
  int elements_size = 0;
  if (length > 0) {
    elements_size = mode == FastCloneShallowArrayStub::CLONE_DOUBLE_ELEMENTS
        ? FixedDoubleArray::SizeFor(length)
        : FixedArray::SizeFor(length);
  }
  int size = JSArray::kSize + elements_size;

  // Allocate both the JS array and the elements array in one big
  // allocation. This avoids multiple limit checks.
  __ AllocateInNewSpace(size,
                        v0,
                        a1,
                        a2,
                        fail,
                        TAG_OBJECT);

  // Copy the JS array part.
  for (int i = 0; i < JSArray::kSize; i += kPointerSize) {
    if ((i != JSArray::kElementsOffset) || (length == 0)) {
      __ lw(a1, FieldMemOperand(a3, i));
      __ sw(a1, FieldMemOperand(v0, i));
    }
  }

  if (length > 0) {
    // Get hold of the elements array of the boilerplate and setup the
    // elements pointer in the resulting object.
    __ lw(a3, FieldMemOperand(a3, JSArray::kElementsOffset));
    __ Addu(a2, v0, Operand(JSArray::kSize));
    __ sw(a2, FieldMemOperand(v0, JSArray::kElementsOffset));

    // Copy the elements array.
    ASSERT((elements_size % kPointerSize) == 0);
    __ CopyFields(a2, a3, a1.bit(), elements_size / kPointerSize);
  }
}

void FastCloneShallowArrayStub::Generate(MacroAssembler* masm) {
  // Stack layout on entry:
  //
  // [sp]: constant elements.
  // [sp + kPointerSize]: literal index.
  // [sp + (2 * kPointerSize)]: literals array.

  // Load boilerplate object into r3 and check if we need to create a
  // boilerplate.
  Label slow_case;
  __ lw(a3, MemOperand(sp, 2 * kPointerSize));
  __ lw(a0, MemOperand(sp, 1 * kPointerSize));
  __ Addu(a3, a3, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
  __ sll(t0, a0, kPointerSizeLog2 - kSmiTagSize);
  __ Addu(t0, a3, t0);
  __ lw(a3, MemOperand(t0));
  __ LoadRoot(t1, Heap::kUndefinedValueRootIndex);
  __ Branch(&slow_case, eq, a3, Operand(t1));

  FastCloneShallowArrayStub::Mode mode = mode_;
  if (mode == CLONE_ANY_ELEMENTS) {
    Label double_elements, check_fast_elements;
    __ lw(v0, FieldMemOperand(a3, JSArray::kElementsOffset));
    __ lw(v0, FieldMemOperand(v0, HeapObject::kMapOffset));
    __ LoadRoot(t1, Heap::kFixedCOWArrayMapRootIndex);
    __ Branch(&check_fast_elements, ne, v0, Operand(t1));
    GenerateFastCloneShallowArrayCommon(masm, 0,
                                        COPY_ON_WRITE_ELEMENTS, &slow_case);
    // Return and remove the on-stack parameters.
    __ DropAndRet(3);

    __ bind(&check_fast_elements);
    __ LoadRoot(t1, Heap::kFixedArrayMapRootIndex);
    __ Branch(&double_elements, ne, v0, Operand(t1));
    GenerateFastCloneShallowArrayCommon(masm, length_,
                                        CLONE_ELEMENTS, &slow_case);
    // Return and remove the on-stack parameters.
    __ DropAndRet(3);

    __ bind(&double_elements);
    mode = CLONE_DOUBLE_ELEMENTS;
    // Fall through to generate the code to handle double elements.
  }

  if (FLAG_debug_code) {
    const char* message;
    Heap::RootListIndex expected_map_index;
    if (mode == CLONE_ELEMENTS) {
      message = "Expected (writable) fixed array";
      expected_map_index = Heap::kFixedArrayMapRootIndex;
    } else if (mode == CLONE_DOUBLE_ELEMENTS) {
      message = "Expected (writable) fixed double array";
      expected_map_index = Heap::kFixedDoubleArrayMapRootIndex;
    } else {
      ASSERT(mode == COPY_ON_WRITE_ELEMENTS);
      message = "Expected copy-on-write fixed array";
      expected_map_index = Heap::kFixedCOWArrayMapRootIndex;
    }
    __ push(a3);
    __ lw(a3, FieldMemOperand(a3, JSArray::kElementsOffset));
    __ lw(a3, FieldMemOperand(a3, HeapObject::kMapOffset));
    __ LoadRoot(at, expected_map_index);
    __ Assert(eq, message, a3, Operand(at));
    __ pop(a3);
  }

  GenerateFastCloneShallowArrayCommon(masm, length_, mode, &slow_case);

  // Return and remove the on-stack parameters.
  __ DropAndRet(3);

  __ bind(&slow_case);
  __ TailCallRuntime(Runtime::kCreateArrayLiteralShallow, 3, 1);
}


void FastCloneShallowObjectStub::Generate(MacroAssembler* masm) {
  // Stack layout on entry:
  //
  // [sp]: object literal flags.
  // [sp + kPointerSize]: constant properties.
  // [sp + (2 * kPointerSize)]: literal index.
  // [sp + (3 * kPointerSize)]: literals array.

  // Load boilerplate object into a3 and check if we need to create a
  // boilerplate.
  Label slow_case;
  __ lw(a3, MemOperand(sp, 3 * kPointerSize));
  __ lw(a0, MemOperand(sp, 2 * kPointerSize));
  __ Addu(a3, a3, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
  __ sll(t0, a0, kPointerSizeLog2 - kSmiTagSize);
  __ Addu(a3, t0, a3);
  __ lw(a3, MemOperand(a3));
  __ LoadRoot(t0, Heap::kUndefinedValueRootIndex);
  __ Branch(&slow_case, eq, a3, Operand(t0));

  // Check that the boilerplate contains only fast properties and we can
  // statically determine the instance size.
  int size = JSObject::kHeaderSize + length_ * kPointerSize;
  __ lw(a0, FieldMemOperand(a3, HeapObject::kMapOffset));
  __ lbu(a0, FieldMemOperand(a0, Map::kInstanceSizeOffset));
  __ Branch(&slow_case, ne, a0, Operand(size >> kPointerSizeLog2));

  // Allocate the JS object and copy header together with all in-object
  // properties from the boilerplate.
  __ AllocateInNewSpace(size, v0, a1, a2, &slow_case, TAG_OBJECT);
  for (int i = 0; i < size; i += kPointerSize) {
    __ lw(a1, FieldMemOperand(a3, i));
    __ sw(a1, FieldMemOperand(v0, i));
  }

  // Return and remove the on-stack parameters.
  __ DropAndRet(4);

  __ bind(&slow_case);
  __ TailCallRuntime(Runtime::kCreateObjectLiteralShallow, 4, 1);
}


// Takes a Smi and converts to an IEEE 64 bit floating point value in two
// registers.  The format is 1 sign bit, 11 exponent bits (biased 1023) and
// 52 fraction bits (20 in the first word, 32 in the second).  Zeros is a
// scratch register.  Destroys the source register.  No GC occurs during this
// stub so you don't have to set up the frame.
class ConvertToDoubleStub : public CodeStub {
 public:
  ConvertToDoubleStub(Register result_reg_1,
                      Register result_reg_2,
                      Register source_reg,
                      Register scratch_reg)
      : result1_(result_reg_1),
        result2_(result_reg_2),
        source_(source_reg),
        zeros_(scratch_reg) { }

 private:
  Register result1_;
  Register result2_;
  Register source_;
  Register zeros_;

  // Minor key encoding in 16 bits.
  class ModeBits: public BitField<OverwriteMode, 0, 2> {};
  class OpBits: public BitField<Token::Value, 2, 14> {};

  Major MajorKey() { return ConvertToDouble; }
  int MinorKey() {
    // Encode the parameters in a unique 16 bit value.
    return  result1_.code() +
           (result2_.code() << 4) +
           (source_.code() << 8) +
           (zeros_.code() << 12);
  }

  void Generate(MacroAssembler* masm);
};


void ConvertToDoubleStub::Generate(MacroAssembler* masm) {
#ifndef BIG_ENDIAN_FLOATING_POINT
  Register exponent = result1_;
  Register mantissa = result2_;
#else
  Register exponent = result2_;
  Register mantissa = result1_;
#endif
  Label not_special;
  // Convert from Smi to integer.
  __ sra(source_, source_, kSmiTagSize);
  // Move sign bit from source to destination.  This works because the sign bit
  // in the exponent word of the double has the same position and polarity as
  // the 2's complement sign bit in a Smi.
  STATIC_ASSERT(HeapNumber::kSignMask == 0x80000000u);
  __ And(exponent, source_, Operand(HeapNumber::kSignMask));
  // Subtract from 0 if source was negative.
  __ subu(at, zero_reg, source_);
  __ Movn(source_, at, exponent);

  // We have -1, 0 or 1, which we treat specially. Register source_ contains
  // absolute value: it is either equal to 1 (special case of -1 and 1),
  // greater than 1 (not a special case) or less than 1 (special case of 0).
  __ Branch(&not_special, gt, source_, Operand(1));

  // For 1 or -1 we need to or in the 0 exponent (biased to 1023).
  const uint32_t exponent_word_for_1 =
      HeapNumber::kExponentBias << HeapNumber::kExponentShift;
  // Safe to use 'at' as dest reg here.
  __ Or(at, exponent, Operand(exponent_word_for_1));
  __ Movn(exponent, at, source_);  // Write exp when source not 0.
  // 1, 0 and -1 all have 0 for the second word.
  __ Ret(USE_DELAY_SLOT);
  __ mov(mantissa, zero_reg);

  __ bind(&not_special);
  // Count leading zeros.
  // Gets the wrong answer for 0, but we already checked for that case above.
  __ Clz(zeros_, source_);
  // Compute exponent and or it into the exponent register.
  // We use mantissa as a scratch register here.
  __ li(mantissa, Operand(31 + HeapNumber::kExponentBias));
  __ subu(mantissa, mantissa, zeros_);
  __ sll(mantissa, mantissa, HeapNumber::kExponentShift);
  __ Or(exponent, exponent, mantissa);

  // Shift up the source chopping the top bit off.
  __ Addu(zeros_, zeros_, Operand(1));
  // This wouldn't work for 1.0 or -1.0 as the shift would be 32 which means 0.
  __ sllv(source_, source_, zeros_);
  // Compute lower part of fraction (last 12 bits).
  __ sll(mantissa, source_, HeapNumber::kMantissaBitsInTopWord);
  // And the top (top 20 bits).
  __ srl(source_, source_, 32 - HeapNumber::kMantissaBitsInTopWord);

  __ Ret(USE_DELAY_SLOT);
  __ or_(exponent, exponent, source_);
}


void FloatingPointHelper::LoadSmis(MacroAssembler* masm,
                                   FloatingPointHelper::Destination destination,
                                   Register scratch1,
                                   Register scratch2) {
  if (CpuFeatures::IsSupported(FPU)) {
    CpuFeatures::Scope scope(FPU);
    __ sra(scratch1, a0, kSmiTagSize);
    __ mtc1(scratch1, f14);
    __ cvt_d_w(f14, f14);
    __ sra(scratch1, a1, kSmiTagSize);
    __ mtc1(scratch1, f12);
    __ cvt_d_w(f12, f12);
    if (destination == kCoreRegisters) {
      __ Move(a2, a3, f14);
      __ Move(a0, a1, f12);
    }
  } else {
    ASSERT(destination == kCoreRegisters);
    // Write Smi from a0 to a3 and a2 in double format.
    __ mov(scratch1, a0);
    ConvertToDoubleStub stub1(a3, a2, scratch1, scratch2);
    __ push(ra);
    __ Call(stub1.GetCode());
    // Write Smi from a1 to a1 and a0 in double format.
    __ mov(scratch1, a1);
    ConvertToDoubleStub stub2(a1, a0, scratch1, scratch2);
    __ Call(stub2.GetCode());
    __ pop(ra);
  }
}


void FloatingPointHelper::LoadOperands(
    MacroAssembler* masm,
    FloatingPointHelper::Destination destination,
    Register heap_number_map,
    Register scratch1,
    Register scratch2,
    Label* slow) {

  // Load right operand (a0) to f12 or a2/a3.
  LoadNumber(masm, destination,
             a0, f14, a2, a3, heap_number_map, scratch1, scratch2, slow);

  // Load left operand (a1) to f14 or a0/a1.
  LoadNumber(masm, destination,
             a1, f12, a0, a1, heap_number_map, scratch1, scratch2, slow);
}


void FloatingPointHelper::LoadNumber(MacroAssembler* masm,
                                     Destination destination,
                                     Register object,
                                     FPURegister dst,
                                     Register dst1,
                                     Register dst2,
                                     Register heap_number_map,
                                     Register scratch1,
                                     Register scratch2,
                                     Label* not_number) {
  if (FLAG_debug_code) {
    __ AbortIfNotRootValue(heap_number_map,
                           Heap::kHeapNumberMapRootIndex,
                           "HeapNumberMap register clobbered.");
  }

  Label is_smi, done;

  // Smi-check
  __ UntagAndJumpIfSmi(scratch1, object, &is_smi);
  // Heap number check
  __ JumpIfNotHeapNumber(object, heap_number_map, scratch1, not_number);

  // Handle loading a double from a heap number.
  if (CpuFeatures::IsSupported(FPU) &&
      destination == kFPURegisters) {
    CpuFeatures::Scope scope(FPU);
    // Load the double from tagged HeapNumber to double register.

    // ARM uses a workaround here because of the unaligned HeapNumber
    // kValueOffset. On MIPS this workaround is built into ldc1 so there's no
    // point in generating even more instructions.
    __ ldc1(dst, FieldMemOperand(object, HeapNumber::kValueOffset));
  } else {
    ASSERT(destination == kCoreRegisters);
    // Load the double from heap number to dst1 and dst2 in double format.
    __ lw(dst1, FieldMemOperand(object, HeapNumber::kValueOffset));
    __ lw(dst2, FieldMemOperand(object,
        HeapNumber::kValueOffset + kPointerSize));
  }
  __ Branch(&done);

  // Handle loading a double from a smi.
  __ bind(&is_smi);
  if (CpuFeatures::IsSupported(FPU)) {
    CpuFeatures::Scope scope(FPU);
    // Convert smi to double using FPU instructions.
    __ mtc1(scratch1, dst);
    __ cvt_d_w(dst, dst);
    if (destination == kCoreRegisters) {
      // Load the converted smi to dst1 and dst2 in double format.
      __ Move(dst1, dst2, dst);
    }
  } else {
    ASSERT(destination == kCoreRegisters);
    // Write smi to dst1 and dst2 double format.
    __ mov(scratch1, object);
    ConvertToDoubleStub stub(dst2, dst1, scratch1, scratch2);
    __ push(ra);
    __ Call(stub.GetCode());
    __ pop(ra);
  }

  __ bind(&done);
}


void FloatingPointHelper::ConvertNumberToInt32(MacroAssembler* masm,
                                               Register object,
                                               Register dst,
                                               Register heap_number_map,
                                               Register scratch1,
                                               Register scratch2,
                                               Register scratch3,
                                               FPURegister double_scratch,
                                               Label* not_number) {
  if (FLAG_debug_code) {
    __ AbortIfNotRootValue(heap_number_map,
                           Heap::kHeapNumberMapRootIndex,
                           "HeapNumberMap register clobbered.");
  }
  Label done;
  Label not_in_int32_range;

  __ UntagAndJumpIfSmi(dst, object, &done);
  __ lw(scratch1, FieldMemOperand(object, HeapNumber::kMapOffset));
  __ Branch(not_number, ne, scratch1, Operand(heap_number_map));
  __ ConvertToInt32(object,
                    dst,
                    scratch1,
                    scratch2,
                    double_scratch,
                    &not_in_int32_range);
  __ jmp(&done);

  __ bind(&not_in_int32_range);
  __ lw(scratch1, FieldMemOperand(object, HeapNumber::kExponentOffset));
  __ lw(scratch2, FieldMemOperand(object, HeapNumber::kMantissaOffset));

  __ EmitOutOfInt32RangeTruncate(dst,
                                 scratch1,
                                 scratch2,
                                 scratch3);

  __ bind(&done);
}


void FloatingPointHelper::ConvertIntToDouble(MacroAssembler* masm,
                                             Register int_scratch,
                                             Destination destination,
                                             FPURegister double_dst,
                                             Register dst1,
                                             Register dst2,
                                             Register scratch2,
                                             FPURegister single_scratch) {
  ASSERT(!int_scratch.is(scratch2));
  ASSERT(!int_scratch.is(dst1));
  ASSERT(!int_scratch.is(dst2));

  Label done;

  if (CpuFeatures::IsSupported(FPU)) {
    CpuFeatures::Scope scope(FPU);
    __ mtc1(int_scratch, single_scratch);
    __ cvt_d_w(double_dst, single_scratch);
    if (destination == kCoreRegisters) {
      __ Move(dst1, dst2, double_dst);
    }
  } else {
    Label fewer_than_20_useful_bits;
    // Expected output:
    // |         dst2            |         dst1            |
    // | s |   exp   |              mantissa               |

    // Check for zero.
    __ mov(dst2, int_scratch);
    __ mov(dst1, int_scratch);
    __ Branch(&done, eq, int_scratch, Operand(zero_reg));

    // Preload the sign of the value.
    __ And(dst2, int_scratch, Operand(HeapNumber::kSignMask));
    // Get the absolute value of the object (as an unsigned integer).
    Label skip_sub;
    __ Branch(&skip_sub, ge, dst2, Operand(zero_reg));
    __ Subu(int_scratch, zero_reg, int_scratch);
    __ bind(&skip_sub);

    // Get mantissa[51:20].

    // Get the position of the first set bit.
    __ Clz(dst1, int_scratch);
    __ li(scratch2, 31);
    __ Subu(dst1, scratch2, dst1);

    // Set the exponent.
    __ Addu(scratch2, dst1, Operand(HeapNumber::kExponentBias));
    __ Ins(dst2, scratch2,
        HeapNumber::kExponentShift, HeapNumber::kExponentBits);

    // Clear the first non null bit.
    __ li(scratch2, Operand(1));
    __ sllv(scratch2, scratch2, dst1);
    __ li(at, -1);
    __ Xor(scratch2, scratch2, at);
    __ And(int_scratch, int_scratch, scratch2);

    // Get the number of bits to set in the lower part of the mantissa.
    __ Subu(scratch2, dst1, Operand(HeapNumber::kMantissaBitsInTopWord));
    __ Branch(&fewer_than_20_useful_bits, lt, scratch2, Operand(zero_reg));
    // Set the higher 20 bits of the mantissa.
    __ srlv(at, int_scratch, scratch2);
    __ or_(dst2, dst2, at);
    __ li(at, 32);
    __ subu(scratch2, at, scratch2);
    __ sllv(dst1, int_scratch, scratch2);
    __ Branch(&done);

    __ bind(&fewer_than_20_useful_bits);
    __ li(at, HeapNumber::kMantissaBitsInTopWord);
    __ subu(scratch2, at, dst1);
    __ sllv(scratch2, int_scratch, scratch2);
    __ Or(dst2, dst2, scratch2);
    // Set dst1 to 0.
    __ mov(dst1, zero_reg);
  }
  __ bind(&done);
}


void FloatingPointHelper::LoadNumberAsInt32Double(MacroAssembler* masm,
                                                  Register object,
                                                  Destination destination,
                                                  DoubleRegister double_dst,
                                                  Register dst1,
                                                  Register dst2,
                                                  Register heap_number_map,
                                                  Register scratch1,
                                                  Register scratch2,
                                                  FPURegister single_scratch,
                                                  Label* not_int32) {
  ASSERT(!scratch1.is(object) && !scratch2.is(object));
  ASSERT(!scratch1.is(scratch2));
  ASSERT(!heap_number_map.is(object) &&
         !heap_number_map.is(scratch1) &&
         !heap_number_map.is(scratch2));

  Label done, obj_is_not_smi;

  __ JumpIfNotSmi(object, &obj_is_not_smi);
  __ SmiUntag(scratch1, object);
  ConvertIntToDouble(masm, scratch1, destination, double_dst, dst1, dst2,
                     scratch2, single_scratch);
  __ Branch(&done);

  __ bind(&obj_is_not_smi);
  if (FLAG_debug_code) {
    __ AbortIfNotRootValue(heap_number_map,
                           Heap::kHeapNumberMapRootIndex,
                           "HeapNumberMap register clobbered.");
  }
  __ JumpIfNotHeapNumber(object, heap_number_map, scratch1, not_int32);

  // Load the number.
  if (CpuFeatures::IsSupported(FPU)) {
    CpuFeatures::Scope scope(FPU);
    // Load the double value.
    __ ldc1(double_dst, FieldMemOperand(object, HeapNumber::kValueOffset));

    Register except_flag = scratch2;
    __ EmitFPUTruncate(kRoundToZero,
                       single_scratch,
                       double_dst,
                       scratch1,
                       except_flag,
                       kCheckForInexactConversion);

    // Jump to not_int32 if the operation did not succeed.
    __ Branch(not_int32, ne, except_flag, Operand(zero_reg));

    if (destination == kCoreRegisters) {
      __ Move(dst1, dst2, double_dst);
    }

  } else {
    ASSERT(!scratch1.is(object) && !scratch2.is(object));
    // Load the double value in the destination registers.
    __ lw(dst2, FieldMemOperand(object, HeapNumber::kExponentOffset));
    __ lw(dst1, FieldMemOperand(object, HeapNumber::kMantissaOffset));

    // Check for 0 and -0.
    __ And(scratch1, dst1, Operand(~HeapNumber::kSignMask));
    __ Or(scratch1, scratch1, Operand(dst2));
    __ Branch(&done, eq, scratch1, Operand(zero_reg));

    // Check that the value can be exactly represented by a 32-bit integer.
    // Jump to not_int32 if that's not the case.
    DoubleIs32BitInteger(masm, dst1, dst2, scratch1, scratch2, not_int32);

    // dst1 and dst2 were trashed. Reload the double value.
    __ lw(dst2, FieldMemOperand(object, HeapNumber::kExponentOffset));
    __ lw(dst1, FieldMemOperand(object, HeapNumber::kMantissaOffset));
  }

  __ bind(&done);
}


void FloatingPointHelper::LoadNumberAsInt32(MacroAssembler* masm,
                                            Register object,
                                            Register dst,
                                            Register heap_number_map,
                                            Register scratch1,
                                            Register scratch2,
                                            Register scratch3,
                                            DoubleRegister double_scratch,
                                            Label* not_int32) {
  ASSERT(!dst.is(object));
  ASSERT(!scratch1.is(object) && !scratch2.is(object) && !scratch3.is(object));
  ASSERT(!scratch1.is(scratch2) &&
         !scratch1.is(scratch3) &&
         !scratch2.is(scratch3));

  Label done;

  __ UntagAndJumpIfSmi(dst, object, &done);

  if (FLAG_debug_code) {
    __ AbortIfNotRootValue(heap_number_map,
                           Heap::kHeapNumberMapRootIndex,
                           "HeapNumberMap register clobbered.");
  }
  __ JumpIfNotHeapNumber(object, heap_number_map, scratch1, not_int32);

  // Object is a heap number.
  // Convert the floating point value to a 32-bit integer.
  if (CpuFeatures::IsSupported(FPU)) {
    CpuFeatures::Scope scope(FPU);
    // Load the double value.
    __ ldc1(double_scratch, FieldMemOperand(object, HeapNumber::kValueOffset));

    FPURegister single_scratch = double_scratch.low();
    Register except_flag = scratch2;
    __ EmitFPUTruncate(kRoundToZero,
                       single_scratch,
                       double_scratch,
                       scratch1,
                       except_flag,
                       kCheckForInexactConversion);

    // Jump to not_int32 if the operation did not succeed.
    __ Branch(not_int32, ne, except_flag, Operand(zero_reg));
    // Get the result in the destination register.
    __ mfc1(dst, single_scratch);

  } else {
    // Load the double value in the destination registers.
    __ lw(scratch2, FieldMemOperand(object, HeapNumber::kExponentOffset));
    __ lw(scratch1, FieldMemOperand(object, HeapNumber::kMantissaOffset));

    // Check for 0 and -0.
    __ And(dst, scratch1, Operand(~HeapNumber::kSignMask));
    __ Or(dst, scratch2, Operand(dst));
    __ Branch(&done, eq, dst, Operand(zero_reg));

    DoubleIs32BitInteger(masm, scratch1, scratch2, dst, scratch3, not_int32);

    // Registers state after DoubleIs32BitInteger.
    // dst: mantissa[51:20].
    // scratch2: 1

    // Shift back the higher bits of the mantissa.
    __ srlv(dst, dst, scratch3);
    // Set the implicit first bit.
    __ li(at, 32);
    __ subu(scratch3, at, scratch3);
    __ sllv(scratch2, scratch2, scratch3);
    __ Or(dst, dst, scratch2);
    // Set the sign.
    __ lw(scratch1, FieldMemOperand(object, HeapNumber::kExponentOffset));
    __ And(scratch1, scratch1, Operand(HeapNumber::kSignMask));
    Label skip_sub;
    __ Branch(&skip_sub, ge, scratch1, Operand(zero_reg));
    __ Subu(dst, zero_reg, dst);
    __ bind(&skip_sub);
  }

  __ bind(&done);
}


void FloatingPointHelper::DoubleIs32BitInteger(MacroAssembler* masm,
                                               Register src1,
                                               Register src2,
                                               Register dst,
                                               Register scratch,
                                               Label* not_int32) {
  // Get exponent alone in scratch.
  __ Ext(scratch,
         src1,
         HeapNumber::kExponentShift,
         HeapNumber::kExponentBits);

  // Substract the bias from the exponent.
  __ Subu(scratch, scratch, Operand(HeapNumber::kExponentBias));

  // src1: higher (exponent) part of the double value.
  // src2: lower (mantissa) part of the double value.
  // scratch: unbiased exponent.

  // Fast cases. Check for obvious non 32-bit integer values.
  // Negative exponent cannot yield 32-bit integers.
  __ Branch(not_int32, lt, scratch, Operand(zero_reg));
  // Exponent greater than 31 cannot yield 32-bit integers.
  // Also, a positive value with an exponent equal to 31 is outside of the
  // signed 32-bit integer range.
  // Another way to put it is that if (exponent - signbit) > 30 then the
  // number cannot be represented as an int32.
  Register tmp = dst;
  __ srl(at, src1, 31);
  __ subu(tmp, scratch, at);
  __ Branch(not_int32, gt, tmp, Operand(30));
  // - Bits [21:0] in the mantissa are not null.
  __ And(tmp, src2, 0x3fffff);
  __ Branch(not_int32, ne, tmp, Operand(zero_reg));

  // Otherwise the exponent needs to be big enough to shift left all the
  // non zero bits left. So we need the (30 - exponent) last bits of the
  // 31 higher bits of the mantissa to be null.
  // Because bits [21:0] are null, we can check instead that the
  // (32 - exponent) last bits of the 32 higher bits of the mantissa are null.

  // Get the 32 higher bits of the mantissa in dst.
  __ Ext(dst,
         src2,
         HeapNumber::kMantissaBitsInTopWord,
         32 - HeapNumber::kMantissaBitsInTopWord);
  __ sll(at, src1, HeapNumber::kNonMantissaBitsInTopWord);
  __ or_(dst, dst, at);

  // Create the mask and test the lower bits (of the higher bits).
  __ li(at, 32);
  __ subu(scratch, at, scratch);
  __ li(src2, 1);
  __ sllv(src1, src2, scratch);
  __ Subu(src1, src1, Operand(1));
  __ And(src1, dst, src1);
  __ Branch(not_int32, ne, src1, Operand(zero_reg));
}


void FloatingPointHelper::CallCCodeForDoubleOperation(
    MacroAssembler* masm,
    Token::Value op,
    Register heap_number_result,
    Register scratch) {
  // Using core registers:
  // a0: Left value (least significant part of mantissa).
  // a1: Left value (sign, exponent, top of mantissa).
  // a2: Right value (least significant part of mantissa).
  // a3: Right value (sign, exponent, top of mantissa).

  // Assert that heap_number_result is saved.
  // We currently always use s0 to pass it.
  ASSERT(heap_number_result.is(s0));

  // Push the current return address before the C call.
  __ push(ra);
  __ PrepareCallCFunction(4, scratch);  // Two doubles are 4 arguments.
  if (!IsMipsSoftFloatABI) {
    CpuFeatures::Scope scope(FPU);
    // We are not using MIPS FPU instructions, and parameters for the runtime
    // function call are prepaired in a0-a3 registers, but function we are
    // calling is compiled with hard-float flag and expecting hard float ABI
    // (parameters in f12/f14 registers). We need to copy parameters from
    // a0-a3 registers to f12/f14 register pairs.
    __ Move(f12, a0, a1);
    __ Move(f14, a2, a3);
  }
  {
    AllowExternalCallThatCantCauseGC scope(masm);
    __ CallCFunction(
        ExternalReference::double_fp_operation(op, masm->isolate()), 0, 2);
  }
  // Store answer in the overwritable heap number.
  if (!IsMipsSoftFloatABI) {
    CpuFeatures::Scope scope(FPU);
    // Double returned in register f0.
    __ sdc1(f0, FieldMemOperand(heap_number_result, HeapNumber::kValueOffset));
  } else {
    // Double returned in registers v0 and v1.
    __ sw(v1, FieldMemOperand(heap_number_result, HeapNumber::kExponentOffset));
    __ sw(v0, FieldMemOperand(heap_number_result, HeapNumber::kMantissaOffset));
  }
  // Place heap_number_result in v0 and return to the pushed return address.
  __ pop(ra);
  __ Ret(USE_DELAY_SLOT);
  __ mov(v0, heap_number_result);
}


bool WriteInt32ToHeapNumberStub::IsPregenerated() {
  // These variants are compiled ahead of time.  See next method.
  if (the_int_.is(a1) &&
      the_heap_number_.is(v0) &&
      scratch_.is(a2) &&
      sign_.is(a3)) {
    return true;
  }
  if (the_int_.is(a2) &&
      the_heap_number_.is(v0) &&
      scratch_.is(a3) &&
      sign_.is(a0)) {
    return true;
  }
  // Other register combinations are generated as and when they are needed,
  // so it is unsafe to call them from stubs (we can't generate a stub while
  // we are generating a stub).
  return false;
}


void WriteInt32ToHeapNumberStub::GenerateFixedRegStubsAheadOfTime() {
  WriteInt32ToHeapNumberStub stub1(a1, v0, a2, a3);
  WriteInt32ToHeapNumberStub stub2(a2, v0, a3, a0);
  stub1.GetCode()->set_is_pregenerated(true);
  stub2.GetCode()->set_is_pregenerated(true);
}


// See comment for class, this does NOT work for int32's that are in Smi range.
void WriteInt32ToHeapNumberStub::Generate(MacroAssembler* masm) {
  Label max_negative_int;
  // the_int_ has the answer which is a signed int32 but not a Smi.
  // We test for the special value that has a different exponent.
  STATIC_ASSERT(HeapNumber::kSignMask == 0x80000000u);
  // Test sign, and save for later conditionals.
  __ And(sign_, the_int_, Operand(0x80000000u));
  __ Branch(&max_negative_int, eq, the_int_, Operand(0x80000000u));

  // Set up the correct exponent in scratch_.  All non-Smi int32s have the same.
  // A non-Smi integer is 1.xxx * 2^30 so the exponent is 30 (biased).
  uint32_t non_smi_exponent =
      (HeapNumber::kExponentBias + 30) << HeapNumber::kExponentShift;
  __ li(scratch_, Operand(non_smi_exponent));
  // Set the sign bit in scratch_ if the value was negative.
  __ or_(scratch_, scratch_, sign_);
  // Subtract from 0 if the value was negative.
  __ subu(at, zero_reg, the_int_);
  __ Movn(the_int_, at, sign_);
  // We should be masking the implict first digit of the mantissa away here,
  // but it just ends up combining harmlessly with the last digit of the
  // exponent that happens to be 1.  The sign bit is 0 so we shift 10 to get
  // the most significant 1 to hit the last bit of the 12 bit sign and exponent.
  ASSERT(((1 << HeapNumber::kExponentShift) & non_smi_exponent) != 0);
  const int shift_distance = HeapNumber::kNonMantissaBitsInTopWord - 2;
  __ srl(at, the_int_, shift_distance);
  __ or_(scratch_, scratch_, at);
  __ sw(scratch_, FieldMemOperand(the_heap_number_,
                                   HeapNumber::kExponentOffset));
  __ sll(scratch_, the_int_, 32 - shift_distance);
  __ sw(scratch_, FieldMemOperand(the_heap_number_,
                                   HeapNumber::kMantissaOffset));
  __ Ret();

  __ bind(&max_negative_int);
  // The max negative int32 is stored as a positive number in the mantissa of
  // a double because it uses a sign bit instead of using two's complement.
  // The actual mantissa bits stored are all 0 because the implicit most
  // significant 1 bit is not stored.
  non_smi_exponent += 1 << HeapNumber::kExponentShift;
  __ li(scratch_, Operand(HeapNumber::kSignMask | non_smi_exponent));
  __ sw(scratch_,
        FieldMemOperand(the_heap_number_, HeapNumber::kExponentOffset));
  __ mov(scratch_, zero_reg);
  __ sw(scratch_,
        FieldMemOperand(the_heap_number_, HeapNumber::kMantissaOffset));
  __ Ret();
}


// Handle the case where the lhs and rhs are the same object.
// Equality is almost reflexive (everything but NaN), so this is a test
// for "identity and not NaN".
static void EmitIdenticalObjectComparison(MacroAssembler* masm,
                                          Label* slow,
                                          Condition cc,
                                          bool never_nan_nan) {
  Label not_identical;
  Label heap_number, return_equal;
  Register exp_mask_reg = t5;

  __ Branch(&not_identical, ne, a0, Operand(a1));

  // The two objects are identical. If we know that one of them isn't NaN then
  // we now know they test equal.
  if (cc != eq || !never_nan_nan) {
    __ li(exp_mask_reg, Operand(HeapNumber::kExponentMask));

    // Test for NaN. Sadly, we can't just compare to factory->nan_value(),
    // so we do the second best thing - test it ourselves.
    // They are both equal and they are not both Smis so both of them are not
    // Smis. If it's not a heap number, then return equal.
    if (cc == less || cc == greater) {
      __ GetObjectType(a0, t4, t4);
      __ Branch(slow, greater, t4, Operand(FIRST_SPEC_OBJECT_TYPE));
    } else {
      __ GetObjectType(a0, t4, t4);
      __ Branch(&heap_number, eq, t4, Operand(HEAP_NUMBER_TYPE));
      // Comparing JS objects with <=, >= is complicated.
      if (cc != eq) {
      __ Branch(slow, greater, t4, Operand(FIRST_SPEC_OBJECT_TYPE));
        // Normally here we fall through to return_equal, but undefined is
        // special: (undefined == undefined) == true, but
        // (undefined <= undefined) == false!  See ECMAScript 11.8.5.
        if (cc == less_equal || cc == greater_equal) {
          __ Branch(&return_equal, ne, t4, Operand(ODDBALL_TYPE));
          __ LoadRoot(t2, Heap::kUndefinedValueRootIndex);
          __ Branch(&return_equal, ne, a0, Operand(t2));
          if (cc == le) {
            // undefined <= undefined should fail.
            __ li(v0, Operand(GREATER));
          } else  {
            // undefined >= undefined should fail.
            __ li(v0, Operand(LESS));
          }
          __ Ret();
        }
      }
    }
  }

  __ bind(&return_equal);

  if (cc == less) {
    __ li(v0, Operand(GREATER));  // Things aren't less than themselves.
  } else if (cc == greater) {
    __ li(v0, Operand(LESS));     // Things aren't greater than themselves.
  } else {
    __ mov(v0, zero_reg);         // Things are <=, >=, ==, === themselves.
  }
  __ Ret();

  if (cc != eq || !never_nan_nan) {
    // For less and greater we don't have to check for NaN since the result of
    // x < x is false regardless.  For the others here is some code to check
    // for NaN.
    if (cc != lt && cc != gt) {
      __ bind(&heap_number);
      // It is a heap number, so return non-equal if it's NaN and equal if it's
      // not NaN.

      // The representation of NaN values has all exponent bits (52..62) set,
      // and not all mantissa bits (0..51) clear.
      // Read top bits of double representation (second word of value).
      __ lw(t2, FieldMemOperand(a0, HeapNumber::kExponentOffset));
      // Test that exponent bits are all set.
      __ And(t3, t2, Operand(exp_mask_reg));
      // If all bits not set (ne cond), then not a NaN, objects are equal.
      __ Branch(&return_equal, ne, t3, Operand(exp_mask_reg));

      // Shift out flag and all exponent bits, retaining only mantissa.
      __ sll(t2, t2, HeapNumber::kNonMantissaBitsInTopWord);
      // Or with all low-bits of mantissa.
      __ lw(t3, FieldMemOperand(a0, HeapNumber::kMantissaOffset));
      __ Or(v0, t3, Operand(t2));
      // For equal we already have the right value in v0:  Return zero (equal)
      // if all bits in mantissa are zero (it's an Infinity) and non-zero if
      // not (it's a NaN).  For <= and >= we need to load v0 with the failing
      // value if it's a NaN.
      if (cc != eq) {
        // All-zero means Infinity means equal.
        __ Ret(eq, v0, Operand(zero_reg));
        if (cc == le) {
          __ li(v0, Operand(GREATER));  // NaN <= NaN should fail.
        } else {
          __ li(v0, Operand(LESS));     // NaN >= NaN should fail.
        }
      }
      __ Ret();
    }
    // No fall through here.
  }

  __ bind(&not_identical);
}


static void EmitSmiNonsmiComparison(MacroAssembler* masm,
                                    Register lhs,
                                    Register rhs,
                                    Label* both_loaded_as_doubles,
                                    Label* slow,
                                    bool strict) {
  ASSERT((lhs.is(a0) && rhs.is(a1)) ||
         (lhs.is(a1) && rhs.is(a0)));

  Label lhs_is_smi;
  __ JumpIfSmi(lhs, &lhs_is_smi);
  // Rhs is a Smi.
  // Check whether the non-smi is a heap number.
  __ GetObjectType(lhs, t4, t4);
  if (strict) {
    // If lhs was not a number and rhs was a Smi then strict equality cannot
    // succeed. Return non-equal (lhs is already not zero).
    __ Ret(USE_DELAY_SLOT, ne, t4, Operand(HEAP_NUMBER_TYPE));
    __ mov(v0, lhs);
  } else {
    // Smi compared non-strictly with a non-Smi non-heap-number. Call
    // the runtime.
    __ Branch(slow, ne, t4, Operand(HEAP_NUMBER_TYPE));
  }

  // Rhs is a smi, lhs is a number.
  // Convert smi rhs to double.
  if (CpuFeatures::IsSupported(FPU)) {
    CpuFeatures::Scope scope(FPU);
    __ sra(at, rhs, kSmiTagSize);
    __ mtc1(at, f14);
    __ cvt_d_w(f14, f14);
    __ ldc1(f12, FieldMemOperand(lhs, HeapNumber::kValueOffset));
  } else {
    // Load lhs to a double in a2, a3.
    __ lw(a3, FieldMemOperand(lhs, HeapNumber::kValueOffset + 4));
    __ lw(a2, FieldMemOperand(lhs, HeapNumber::kValueOffset));

    // Write Smi from rhs to a1 and a0 in double format. t5 is scratch.
    __ mov(t6, rhs);
    ConvertToDoubleStub stub1(a1, a0, t6, t5);
    __ push(ra);
    __ Call(stub1.GetCode());

    __ pop(ra);
  }

  // We now have both loaded as doubles.
  __ jmp(both_loaded_as_doubles);

  __ bind(&lhs_is_smi);
  // Lhs is a Smi.  Check whether the non-smi is a heap number.
  __ GetObjectType(rhs, t4, t4);
  if (strict) {
    // If lhs was not a number and rhs was a Smi then strict equality cannot
    // succeed. Return non-equal.
    __ Ret(USE_DELAY_SLOT, ne, t4, Operand(HEAP_NUMBER_TYPE));
    __ li(v0, Operand(1));
  } else {
    // Smi compared non-strictly with a non-Smi non-heap-number. Call
    // the runtime.
    __ Branch(slow, ne, t4, Operand(HEAP_NUMBER_TYPE));
  }

  // Lhs is a smi, rhs is a number.
  // Convert smi lhs to double.
  if (CpuFeatures::IsSupported(FPU)) {
    CpuFeatures::Scope scope(FPU);
    __ sra(at, lhs, kSmiTagSize);
    __ mtc1(at, f12);
    __ cvt_d_w(f12, f12);
    __ ldc1(f14, FieldMemOperand(rhs, HeapNumber::kValueOffset));
  } else {
    // Convert lhs to a double format. t5 is scratch.
    __ mov(t6, lhs);
    ConvertToDoubleStub stub2(a3, a2, t6, t5);
    __ push(ra);
    __ Call(stub2.GetCode());
    __ pop(ra);
    // Load rhs to a double in a1, a0.
    if (rhs.is(a0)) {
      __ lw(a1, FieldMemOperand(rhs, HeapNumber::kValueOffset + 4));
      __ lw(a0, FieldMemOperand(rhs, HeapNumber::kValueOffset));
    } else {
      __ lw(a0, FieldMemOperand(rhs, HeapNumber::kValueOffset));
      __ lw(a1, FieldMemOperand(rhs, HeapNumber::kValueOffset + 4));
    }
  }
  // Fall through to both_loaded_as_doubles.
}


void EmitNanCheck(MacroAssembler* masm, Condition cc) {
  bool exp_first = (HeapNumber::kExponentOffset == HeapNumber::kValueOffset);
  if (CpuFeatures::IsSupported(FPU)) {
    CpuFeatures::Scope scope(FPU);
    // Lhs and rhs are already loaded to f12 and f14 register pairs.
    __ Move(t0, t1, f14);
    __ Move(t2, t3, f12);
  } else {
    // Lhs and rhs are already loaded to GP registers.
    __ mov(t0, a0);  // a0 has LS 32 bits of rhs.
    __ mov(t1, a1);  // a1 has MS 32 bits of rhs.
    __ mov(t2, a2);  // a2 has LS 32 bits of lhs.
    __ mov(t3, a3);  // a3 has MS 32 bits of lhs.
  }
  Register rhs_exponent = exp_first ? t0 : t1;
  Register lhs_exponent = exp_first ? t2 : t3;
  Register rhs_mantissa = exp_first ? t1 : t0;
  Register lhs_mantissa = exp_first ? t3 : t2;
  Label one_is_nan, neither_is_nan;
  Label lhs_not_nan_exp_mask_is_loaded;

  Register exp_mask_reg = t4;
  __ li(exp_mask_reg, HeapNumber::kExponentMask);
  __ and_(t5, lhs_exponent, exp_mask_reg);
  __ Branch(&lhs_not_nan_exp_mask_is_loaded, ne, t5, Operand(exp_mask_reg));

  __ sll(t5, lhs_exponent, HeapNumber::kNonMantissaBitsInTopWord);
  __ Branch(&one_is_nan, ne, t5, Operand(zero_reg));

  __ Branch(&one_is_nan, ne, lhs_mantissa, Operand(zero_reg));

  __ li(exp_mask_reg, HeapNumber::kExponentMask);
  __ bind(&lhs_not_nan_exp_mask_is_loaded);
  __ and_(t5, rhs_exponent, exp_mask_reg);

  __ Branch(&neither_is_nan, ne, t5, Operand(exp_mask_reg));

  __ sll(t5, rhs_exponent, HeapNumber::kNonMantissaBitsInTopWord);
  __ Branch(&one_is_nan, ne, t5, Operand(zero_reg));

  __ Branch(&neither_is_nan, eq, rhs_mantissa, Operand(zero_reg));

  __ bind(&one_is_nan);
  // NaN comparisons always fail.
  // Load whatever we need in v0 to make the comparison fail.

  if (cc == lt || cc == le) {
    __ li(v0, Operand(GREATER));
  } else {
    __ li(v0, Operand(LESS));
  }
  __ Ret();

  __ bind(&neither_is_nan);
}


static void EmitTwoNonNanDoubleComparison(MacroAssembler* masm, Condition cc) {
  // f12 and f14 have the two doubles.  Neither is a NaN.
  // Call a native function to do a comparison between two non-NaNs.
  // Call C routine that may not cause GC or other trouble.
  // We use a call_was and return manually because we need arguments slots to
  // be freed.

  Label return_result_not_equal, return_result_equal;
  if (cc == eq) {
    // Doubles are not equal unless they have the same bit pattern.
    // Exception: 0 and -0.
    bool exp_first = (HeapNumber::kExponentOffset == HeapNumber::kValueOffset);
    if (CpuFeatures::IsSupported(FPU)) {
      CpuFeatures::Scope scope(FPU);
      // Lhs and rhs are already loaded to f12 and f14 register pairs.
      __ Move(t0, t1, f14);
      __ Move(t2, t3, f12);
    } else {
      // Lhs and rhs are already loaded to GP registers.
      __ mov(t0, a0);  // a0 has LS 32 bits of rhs.
      __ mov(t1, a1);  // a1 has MS 32 bits of rhs.
      __ mov(t2, a2);  // a2 has LS 32 bits of lhs.
      __ mov(t3, a3);  // a3 has MS 32 bits of lhs.
    }
    Register rhs_exponent = exp_first ? t0 : t1;
    Register lhs_exponent = exp_first ? t2 : t3;
    Register rhs_mantissa = exp_first ? t1 : t0;
    Register lhs_mantissa = exp_first ? t3 : t2;

    __ xor_(v0, rhs_mantissa, lhs_mantissa);
    __ Branch(&return_result_not_equal, ne, v0, Operand(zero_reg));

    __ subu(v0, rhs_exponent, lhs_exponent);
    __ Branch(&return_result_equal, eq, v0, Operand(zero_reg));
    // 0, -0 case.
    __ sll(rhs_exponent, rhs_exponent, kSmiTagSize);
    __ sll(lhs_exponent, lhs_exponent, kSmiTagSize);
    __ or_(t4, rhs_exponent, lhs_exponent);
    __ or_(t4, t4, rhs_mantissa);

    __ Branch(&return_result_not_equal, ne, t4, Operand(zero_reg));

    __ bind(&return_result_equal);

    __ li(v0, Operand(EQUAL));
    __ Ret();
  }

  __ bind(&return_result_not_equal);

  if (!CpuFeatures::IsSupported(FPU)) {
    __ push(ra);
    __ PrepareCallCFunction(0, 2, t4);
    if (!IsMipsSoftFloatABI) {
      // We are not using MIPS FPU instructions, and parameters for the runtime
      // function call are prepaired in a0-a3 registers, but function we are
      // calling is compiled with hard-float flag and expecting hard float ABI
      // (parameters in f12/f14 registers). We need to copy parameters from
      // a0-a3 registers to f12/f14 register pairs.
      __ Move(f12, a0, a1);
      __ Move(f14, a2, a3);
    }

    AllowExternalCallThatCantCauseGC scope(masm);
    __ CallCFunction(ExternalReference::compare_doubles(masm->isolate()),
       0, 2);
    __ pop(ra);  // Because this function returns int, result is in v0.
    __ Ret();
  } else {
    CpuFeatures::Scope scope(FPU);
    Label equal, less_than;
    __ BranchF(&equal, NULL, eq, f12, f14);
    __ BranchF(&less_than, NULL, lt, f12, f14);

    // Not equal, not less, not NaN, must be greater.

    __ li(v0, Operand(GREATER));
    __ Ret();

    __ bind(&equal);
    __ li(v0, Operand(EQUAL));
    __ Ret();

    __ bind(&less_than);
    __ li(v0, Operand(LESS));
    __ Ret();
  }
}


static void EmitStrictTwoHeapObjectCompare(MacroAssembler* masm,
                                           Register lhs,
                                           Register rhs) {
    // If either operand is a JS object or an oddball value, then they are
    // not equal since their pointers are different.
    // There is no test for undetectability in strict equality.
    STATIC_ASSERT(LAST_TYPE == LAST_SPEC_OBJECT_TYPE);
    Label first_non_object;
    // Get the type of the first operand into a2 and compare it with
    // FIRST_SPEC_OBJECT_TYPE.
    __ GetObjectType(lhs, a2, a2);
    __ Branch(&first_non_object, less, a2, Operand(FIRST_SPEC_OBJECT_TYPE));

    // Return non-zero.
    Label return_not_equal;
    __ bind(&return_not_equal);
    __ Ret(USE_DELAY_SLOT);
    __ li(v0, Operand(1));

    __ bind(&first_non_object);
    // Check for oddballs: true, false, null, undefined.
    __ Branch(&return_not_equal, eq, a2, Operand(ODDBALL_TYPE));

    __ GetObjectType(rhs, a3, a3);
    __ Branch(&return_not_equal, greater, a3, Operand(FIRST_SPEC_OBJECT_TYPE));

    // Check for oddballs: true, false, null, undefined.
    __ Branch(&return_not_equal, eq, a3, Operand(ODDBALL_TYPE));

    // Now that we have the types we might as well check for symbol-symbol.
    // Ensure that no non-strings have the symbol bit set.
    STATIC_ASSERT(LAST_TYPE < kNotStringTag + kIsSymbolMask);
    STATIC_ASSERT(kSymbolTag != 0);
    __ And(t2, a2, Operand(a3));
    __ And(t0, t2, Operand(kIsSymbolMask));
    __ Branch(&return_not_equal, ne, t0, Operand(zero_reg));
}


static void EmitCheckForTwoHeapNumbers(MacroAssembler* masm,
                                       Register lhs,
                                       Register rhs,
                                       Label* both_loaded_as_doubles,
                                       Label* not_heap_numbers,
                                       Label* slow) {
  __ GetObjectType(lhs, a3, a2);
  __ Branch(not_heap_numbers, ne, a2, Operand(HEAP_NUMBER_TYPE));
  __ lw(a2, FieldMemOperand(rhs, HeapObject::kMapOffset));
  // If first was a heap number & second wasn't, go to slow case.
  __ Branch(slow, ne, a3, Operand(a2));

  // Both are heap numbers. Load them up then jump to the code we have
  // for that.
  if (CpuFeatures::IsSupported(FPU)) {
    CpuFeatures::Scope scope(FPU);
    __ ldc1(f12, FieldMemOperand(lhs, HeapNumber::kValueOffset));
    __ ldc1(f14, FieldMemOperand(rhs, HeapNumber::kValueOffset));
  } else {
    __ lw(a2, FieldMemOperand(lhs, HeapNumber::kValueOffset));
    __ lw(a3, FieldMemOperand(lhs, HeapNumber::kValueOffset + 4));
    if (rhs.is(a0)) {
      __ lw(a1, FieldMemOperand(rhs, HeapNumber::kValueOffset + 4));
      __ lw(a0, FieldMemOperand(rhs, HeapNumber::kValueOffset));
    } else {
      __ lw(a0, FieldMemOperand(rhs, HeapNumber::kValueOffset));
      __ lw(a1, FieldMemOperand(rhs, HeapNumber::kValueOffset + 4));
    }
  }
  __ jmp(both_loaded_as_doubles);
}


// Fast negative check for symbol-to-symbol equality.
static void EmitCheckForSymbolsOrObjects(MacroAssembler* masm,
                                         Register lhs,
                                         Register rhs,
                                         Label* possible_strings,
                                         Label* not_both_strings) {
  ASSERT((lhs.is(a0) && rhs.is(a1)) ||
         (lhs.is(a1) && rhs.is(a0)));

  // a2 is object type of lhs.
  // Ensure that no non-strings have the symbol bit set.
  Label object_test;
  STATIC_ASSERT(kSymbolTag != 0);
  __ And(at, a2, Operand(kIsNotStringMask));
  __ Branch(&object_test, ne, at, Operand(zero_reg));
  __ And(at, a2, Operand(kIsSymbolMask));
  __ Branch(possible_strings, eq, at, Operand(zero_reg));
  __ GetObjectType(rhs, a3, a3);
  __ Branch(not_both_strings, ge, a3, Operand(FIRST_NONSTRING_TYPE));
  __ And(at, a3, Operand(kIsSymbolMask));
  __ Branch(possible_strings, eq, at, Operand(zero_reg));

  // Both are symbols. We already checked they weren't the same pointer
  // so they are not equal.
  __ Ret(USE_DELAY_SLOT);
  __ li(v0, Operand(1));   // Non-zero indicates not equal.

  __ bind(&object_test);
  __ Branch(not_both_strings, lt, a2, Operand(FIRST_SPEC_OBJECT_TYPE));
  __ GetObjectType(rhs, a2, a3);
  __ Branch(not_both_strings, lt, a3, Operand(FIRST_SPEC_OBJECT_TYPE));

  // If both objects are undetectable, they are equal.  Otherwise, they
  // are not equal, since they are different objects and an object is not
  // equal to undefined.
  __ lw(a3, FieldMemOperand(lhs, HeapObject::kMapOffset));
  __ lbu(a2, FieldMemOperand(a2, Map::kBitFieldOffset));
  __ lbu(a3, FieldMemOperand(a3, Map::kBitFieldOffset));
  __ and_(a0, a2, a3);
  __ And(a0, a0, Operand(1 << Map::kIsUndetectable));
  __ Ret(USE_DELAY_SLOT);
  __ xori(v0, a0, 1 << Map::kIsUndetectable);
}


void NumberToStringStub::GenerateLookupNumberStringCache(MacroAssembler* masm,
                                                         Register object,
                                                         Register result,
                                                         Register scratch1,
                                                         Register scratch2,
                                                         Register scratch3,
                                                         bool object_is_smi,
                                                         Label* not_found) {
  // Use of registers. Register result is used as a temporary.
  Register number_string_cache = result;
  Register mask = scratch3;

  // Load the number string cache.
  __ LoadRoot(number_string_cache, Heap::kNumberStringCacheRootIndex);

  // Make the hash mask from the length of the number string cache. It
  // contains two elements (number and string) for each cache entry.
  __ lw(mask, FieldMemOperand(number_string_cache, FixedArray::kLengthOffset));
  // Divide length by two (length is a smi).
  __ sra(mask, mask, kSmiTagSize + 1);
  __ Addu(mask, mask, -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.
  Isolate* isolate = masm->isolate();
  Label is_smi;
  Label load_result_from_cache;
  if (!object_is_smi) {
    __ JumpIfSmi(object, &is_smi);
    if (CpuFeatures::IsSupported(FPU)) {
      CpuFeatures::Scope scope(FPU);
      __ CheckMap(object,
                  scratch1,
                  Heap::kHeapNumberMapRootIndex,
                  not_found,
                  DONT_DO_SMI_CHECK);

      STATIC_ASSERT(8 == kDoubleSize);
      __ Addu(scratch1,
              object,
              Operand(HeapNumber::kValueOffset - kHeapObjectTag));
      __ lw(scratch2, MemOperand(scratch1, kPointerSize));
      __ lw(scratch1, MemOperand(scratch1, 0));
      __ Xor(scratch1, scratch1, Operand(scratch2));
      __ And(scratch1, scratch1, Operand(mask));

      // Calculate address of entry in string cache: each entry consists
      // of two pointer sized fields.
      __ sll(scratch1, scratch1, kPointerSizeLog2 + 1);
      __ Addu(scratch1, number_string_cache, scratch1);

      Register probe = mask;
      __ lw(probe,
             FieldMemOperand(scratch1, FixedArray::kHeaderSize));
      __ JumpIfSmi(probe, not_found);
      __ ldc1(f12, FieldMemOperand(object, HeapNumber::kValueOffset));
      __ ldc1(f14, FieldMemOperand(probe, HeapNumber::kValueOffset));
      __ BranchF(&load_result_from_cache, NULL, eq, f12, f14);
      __ Branch(not_found);
    } else {
      // Note that there is no cache check for non-FPU case, even though
      // it seems there could be. May be a tiny opimization for non-FPU
      // cores.
      __ Branch(not_found);
    }
  }

  __ bind(&is_smi);
  Register scratch = scratch1;
  __ sra(scratch, object, 1);   // Shift away the tag.
  __ And(scratch, mask, Operand(scratch));

  // Calculate address of entry in string cache: each entry consists
  // of two pointer sized fields.
  __ sll(scratch, scratch, kPointerSizeLog2 + 1);
  __ Addu(scratch, number_string_cache, scratch);

  // Check if the entry is the smi we are looking for.
  Register probe = mask;
  __ lw(probe, FieldMemOperand(scratch, FixedArray::kHeaderSize));
  __ Branch(not_found, ne, object, Operand(probe));

  // Get the result from the cache.
  __ bind(&load_result_from_cache);
  __ lw(result,
         FieldMemOperand(scratch, FixedArray::kHeaderSize + kPointerSize));

  __ IncrementCounter(isolate->counters()->number_to_string_native(),
                      1,
                      scratch1,
                      scratch2);
}


void NumberToStringStub::Generate(MacroAssembler* masm) {
  Label runtime;

  __ lw(a1, MemOperand(sp, 0));

  // Generate code to lookup number in the number string cache.
  GenerateLookupNumberStringCache(masm, a1, v0, a2, a3, t0, false, &runtime);
  __ DropAndRet(1);

  __ bind(&runtime);
  // Handle number to string in the runtime system if not found in the cache.
  __ TailCallRuntime(Runtime::kNumberToString, 1, 1);
}


// On entry lhs_ (lhs) and rhs_ (rhs) are the things to be compared.
// On exit, v0 is 0, positive, or negative (smi) to indicate the result
// of the comparison.
void CompareStub::Generate(MacroAssembler* masm) {
  Label slow;  // Call builtin.
  Label not_smis, both_loaded_as_doubles;


  if (include_smi_compare_) {
    Label not_two_smis, smi_done;
    __ Or(a2, a1, a0);
    __ JumpIfNotSmi(a2, &not_two_smis);
    __ sra(a1, a1, 1);
    __ sra(a0, a0, 1);
    __ Ret(USE_DELAY_SLOT);
    __ subu(v0, a1, a0);
    __ bind(&not_two_smis);
  } else if (FLAG_debug_code) {
    __ Or(a2, a1, a0);
    __ And(a2, a2, kSmiTagMask);
    __ Assert(ne, "CompareStub: unexpected smi operands.",
        a2, Operand(zero_reg));
  }


  // NOTICE! This code is only reached after a smi-fast-case check, so
  // it is certain that at least one operand isn't a smi.

  // Handle the case where the objects are identical.  Either returns the answer
  // or goes to slow.  Only falls through if the objects were not identical.
  EmitIdenticalObjectComparison(masm, &slow, cc_, never_nan_nan_);

  // If either is a Smi (we know that not both are), then they can only
  // be strictly equal if the other is a HeapNumber.
  STATIC_ASSERT(kSmiTag == 0);
  ASSERT_EQ(0, Smi::FromInt(0));
  __ And(t2, lhs_, Operand(rhs_));
  __ JumpIfNotSmi(t2, &not_smis, t0);
  // One operand is a smi. EmitSmiNonsmiComparison generates code that can:
  // 1) Return the answer.
  // 2) Go to slow.
  // 3) Fall through to both_loaded_as_doubles.
  // 4) Jump to rhs_not_nan.
  // In cases 3 and 4 we have found out we were dealing with a number-number
  // comparison and the numbers have been loaded into f12 and f14 as doubles,
  // or in GP registers (a0, a1, a2, a3) depending on the presence of the FPU.
  EmitSmiNonsmiComparison(masm, lhs_, rhs_,
                          &both_loaded_as_doubles, &slow, strict_);

  __ bind(&both_loaded_as_doubles);
  // f12, f14 are the double representations of the left hand side
  // and the right hand side if we have FPU. Otherwise a2, a3 represent
  // left hand side and a0, a1 represent right hand side.

  Isolate* isolate = masm->isolate();
  if (CpuFeatures::IsSupported(FPU)) {
    CpuFeatures::Scope scope(FPU);
    Label nan;
    __ li(t0, Operand(LESS));
    __ li(t1, Operand(GREATER));
    __ li(t2, Operand(EQUAL));

    // Check if either rhs or lhs is NaN.
    __ BranchF(NULL, &nan, eq, f12, f14);

    // Check if LESS condition is satisfied. If true, move conditionally
    // result to v0.
    __ c(OLT, D, f12, f14);
    __ Movt(v0, t0);
    // Use previous check to store conditionally to v0 oposite condition
    // (GREATER). If rhs is equal to lhs, this will be corrected in next
    // check.
    __ Movf(v0, t1);
    // Check if EQUAL condition is satisfied. If true, move conditionally
    // result to v0.
    __ c(EQ, D, f12, f14);
    __ Movt(v0, t2);

    __ Ret();

    __ bind(&nan);
    // NaN comparisons always fail.
    // Load whatever we need in v0 to make the comparison fail.
    if (cc_ == lt || cc_ == le) {
      __ li(v0, Operand(GREATER));
    } else {
      __ li(v0, Operand(LESS));
    }
    __ Ret();
  } else {
    // Checks for NaN in the doubles we have loaded.  Can return the answer or
    // fall through if neither is a NaN.  Also binds rhs_not_nan.
    EmitNanCheck(masm, cc_);

    // Compares two doubles that are not NaNs. Returns the answer.
    // Never falls through.
    EmitTwoNonNanDoubleComparison(masm, cc_);
  }

  __ bind(&not_smis);
  // At this point we know we are dealing with two different objects,
  // and neither of them is a Smi. The objects are in lhs_ and rhs_.
  if (strict_) {
    // This returns non-equal for some object types, or falls through if it
    // was not lucky.
    EmitStrictTwoHeapObjectCompare(masm, lhs_, rhs_);
  }

  Label check_for_symbols;
  Label flat_string_check;
  // Check for heap-number-heap-number comparison. Can jump to slow case,
  // or load both doubles and jump to the code that handles
  // that case. If the inputs are not doubles then jumps to check_for_symbols.
  // In this case a2 will contain the type of lhs_.
  EmitCheckForTwoHeapNumbers(masm,
                             lhs_,
                             rhs_,
                             &both_loaded_as_doubles,
                             &check_for_symbols,
                             &flat_string_check);

  __ bind(&check_for_symbols);
  if (cc_ == eq && !strict_) {
    // Returns an answer for two symbols or two detectable objects.
    // Otherwise jumps to string case or not both strings case.
    // Assumes that a2 is the type of lhs_ on entry.
    EmitCheckForSymbolsOrObjects(masm, lhs_, rhs_, &flat_string_check, &slow);
  }

  // Check for both being sequential ASCII strings, and inline if that is the
  // case.
  __ bind(&flat_string_check);

  __ JumpIfNonSmisNotBothSequentialAsciiStrings(lhs_, rhs_, a2, a3, &slow);

  __ IncrementCounter(isolate->counters()->string_compare_native(), 1, a2, a3);
  if (cc_ == eq) {
    StringCompareStub::GenerateFlatAsciiStringEquals(masm,
                                                     lhs_,
                                                     rhs_,
                                                     a2,
                                                     a3,
                                                     t0);
  } else {
    StringCompareStub::GenerateCompareFlatAsciiStrings(masm,
                                                       lhs_,
                                                       rhs_,
                                                       a2,
                                                       a3,
                                                       t0,
                                                       t1);
  }
  // Never falls through to here.

  __ bind(&slow);
  // Prepare for call to builtin. Push object pointers, a0 (lhs) first,
  // a1 (rhs) second.
  __ Push(lhs_, rhs_);
  // Figure out which native to call and setup the arguments.
  Builtins::JavaScript native;
  if (cc_ == eq) {
    native = strict_ ? Builtins::STRICT_EQUALS : Builtins::EQUALS;
  } else {
    native = Builtins::COMPARE;
    int ncr;  // NaN compare result.
    if (cc_ == lt || cc_ == le) {
      ncr = GREATER;
    } else {
      ASSERT(cc_ == gt || cc_ == ge);  // Remaining cases.
      ncr = LESS;
    }
    __ li(a0, Operand(Smi::FromInt(ncr)));
    __ push(a0);
  }

  // Call the native; it returns -1 (less), 0 (equal), or 1 (greater)
  // tagged as a small integer.
  __ InvokeBuiltin(native, JUMP_FUNCTION);
}


// The stub expects its argument in the tos_ register and returns its result in
// it, too: zero for false, and a non-zero value for true.
void ToBooleanStub::Generate(MacroAssembler* masm) {
  // This stub uses FPU instructions.
  CpuFeatures::Scope scope(FPU);

  Label patch;
  const Register map = t5.is(tos_) ? t3 : t5;

  // undefined -> false.
  CheckOddball(masm, UNDEFINED, Heap::kUndefinedValueRootIndex, false);

  // Boolean -> its value.
  CheckOddball(masm, BOOLEAN, Heap::kFalseValueRootIndex, false);
  CheckOddball(masm, BOOLEAN, Heap::kTrueValueRootIndex, true);

  // 'null' -> false.
  CheckOddball(masm, NULL_TYPE, Heap::kNullValueRootIndex, false);

  if (types_.Contains(SMI)) {
    // Smis: 0 -> false, all other -> true
    __ And(at, tos_, kSmiTagMask);
    // tos_ contains the correct return value already
    __ Ret(eq, at, Operand(zero_reg));
  } else if (types_.NeedsMap()) {
    // If we need a map later and have a Smi -> patch.
    __ JumpIfSmi(tos_, &patch);
  }

  if (types_.NeedsMap()) {
    __ lw(map, FieldMemOperand(tos_, HeapObject::kMapOffset));

    if (types_.CanBeUndetectable()) {
      __ lbu(at, FieldMemOperand(map, Map::kBitFieldOffset));
      __ And(at, at, Operand(1 << Map::kIsUndetectable));
      // Undetectable -> false.
      __ Movn(tos_, zero_reg, at);
      __ Ret(ne, at, Operand(zero_reg));
    }
  }

  if (types_.Contains(SPEC_OBJECT)) {
    // Spec object -> true.
    __ lbu(at, FieldMemOperand(map, Map::kInstanceTypeOffset));
    // tos_ contains the correct non-zero return value already.
    __ Ret(ge, at, Operand(FIRST_SPEC_OBJECT_TYPE));
  }

  if (types_.Contains(STRING)) {
    // String value -> false iff empty.
    __ lbu(at, FieldMemOperand(map, Map::kInstanceTypeOffset));
    Label skip;
    __ Branch(&skip, ge, at, Operand(FIRST_NONSTRING_TYPE));
    __ Ret(USE_DELAY_SLOT);  // the string length is OK as the return value
    __ lw(tos_, FieldMemOperand(tos_, String::kLengthOffset));
    __ bind(&skip);
  }

  if (types_.Contains(HEAP_NUMBER)) {
    // Heap number -> false iff +0, -0, or NaN.
    Label not_heap_number;
    __ LoadRoot(at, Heap::kHeapNumberMapRootIndex);
    __ Branch(&not_heap_number, ne, map, Operand(at));
    Label zero_or_nan, number;
    __ ldc1(f2, FieldMemOperand(tos_, HeapNumber::kValueOffset));
    __ BranchF(&number, &zero_or_nan, ne, f2, kDoubleRegZero);
    // "tos_" is a register, and contains a non zero value by default.
    // Hence we only need to overwrite "tos_" with zero to return false for
    // FP_ZERO or FP_NAN cases. Otherwise, by default it returns true.
    __ bind(&zero_or_nan);
    __ mov(tos_, zero_reg);
    __ bind(&number);
    __ Ret();
    __ bind(&not_heap_number);
  }

  __ bind(&patch);
  GenerateTypeTransition(masm);
}


void ToBooleanStub::CheckOddball(MacroAssembler* masm,
                                 Type type,
                                 Heap::RootListIndex value,
                                 bool result) {
  if (types_.Contains(type)) {
    // If we see an expected oddball, return its ToBoolean value tos_.
    __ LoadRoot(at, value);
    __ Subu(at, at, tos_);  // This is a check for equality for the movz below.
    // The value of a root is never NULL, so we can avoid loading a non-null
    // value into tos_ when we want to return 'true'.
    if (!result) {
      __ Movz(tos_, zero_reg, at);
    }
    __ Ret(eq, at, Operand(zero_reg));
  }
}


void ToBooleanStub::GenerateTypeTransition(MacroAssembler* masm) {
  __ Move(a3, tos_);
  __ li(a2, Operand(Smi::FromInt(tos_.code())));
  __ li(a1, Operand(Smi::FromInt(types_.ToByte())));
  __ Push(a3, a2, a1);
  // Patch the caller to an appropriate specialized stub and return the
  // operation result to the caller of the stub.
  __ TailCallExternalReference(
      ExternalReference(IC_Utility(IC::kToBoolean_Patch), masm->isolate()),
      3,
      1);
}


void StoreBufferOverflowStub::Generate(MacroAssembler* masm) {
  // We don't allow a GC during a store buffer overflow so there is no need to
  // store the registers in any particular way, but we do have to store and
  // restore them.
  __ MultiPush(kJSCallerSaved | ra.bit());
  if (save_doubles_ == kSaveFPRegs) {
    CpuFeatures::Scope scope(FPU);
    __ MultiPushFPU(kCallerSavedFPU);
  }
  const int argument_count = 1;
  const int fp_argument_count = 0;
  const Register scratch = a1;

  AllowExternalCallThatCantCauseGC scope(masm);
  __ PrepareCallCFunction(argument_count, fp_argument_count, scratch);
  __ li(a0, Operand(ExternalReference::isolate_address()));
  __ CallCFunction(
      ExternalReference::store_buffer_overflow_function(masm->isolate()),
      argument_count);
  if (save_doubles_ == kSaveFPRegs) {
    CpuFeatures::Scope scope(FPU);
    __ MultiPopFPU(kCallerSavedFPU);
  }

  __ MultiPop(kJSCallerSaved | ra.bit());
  __ Ret();
}


void UnaryOpStub::PrintName(StringStream* stream) {
  const char* op_name = Token::Name(op_);
  const char* overwrite_name = NULL;  // Make g++ happy.
  switch (mode_) {
    case UNARY_NO_OVERWRITE: overwrite_name = "Alloc"; break;
    case UNARY_OVERWRITE: overwrite_name = "Overwrite"; break;
  }
  stream->Add("UnaryOpStub_%s_%s_%s",
              op_name,
              overwrite_name,
              UnaryOpIC::GetName(operand_type_));
}


// TODO(svenpanne): Use virtual functions instead of switch.
void UnaryOpStub::Generate(MacroAssembler* masm) {
  switch (operand_type_) {
    case UnaryOpIC::UNINITIALIZED:
      GenerateTypeTransition(masm);
      break;
    case UnaryOpIC::SMI:
      GenerateSmiStub(masm);
      break;
    case UnaryOpIC::HEAP_NUMBER:
      GenerateHeapNumberStub(masm);
      break;
    case UnaryOpIC::GENERIC:
      GenerateGenericStub(masm);
      break;
  }
}


void UnaryOpStub::GenerateTypeTransition(MacroAssembler* masm) {
  // Argument is in a0 and v0 at this point, so we can overwrite a0.
  __ li(a2, Operand(Smi::FromInt(op_)));
  __ li(a1, Operand(Smi::FromInt(mode_)));
  __ li(a0, Operand(Smi::FromInt(operand_type_)));
  __ Push(v0, a2, a1, a0);

  __ TailCallExternalReference(
      ExternalReference(IC_Utility(IC::kUnaryOp_Patch), masm->isolate()), 4, 1);
}


// TODO(svenpanne): Use virtual functions instead of switch.
void UnaryOpStub::GenerateSmiStub(MacroAssembler* masm) {
  switch (op_) {
    case Token::SUB:
      GenerateSmiStubSub(masm);
      break;
    case Token::BIT_NOT:
      GenerateSmiStubBitNot(masm);
      break;
    default:
      UNREACHABLE();
  }
}


void UnaryOpStub::GenerateSmiStubSub(MacroAssembler* masm) {
  Label non_smi, slow;
  GenerateSmiCodeSub(masm, &non_smi, &slow);
  __ bind(&non_smi);
  __ bind(&slow);
  GenerateTypeTransition(masm);
}


void UnaryOpStub::GenerateSmiStubBitNot(MacroAssembler* masm) {
  Label non_smi;
  GenerateSmiCodeBitNot(masm, &non_smi);
  __ bind(&non_smi);
  GenerateTypeTransition(masm);
}


void UnaryOpStub::GenerateSmiCodeSub(MacroAssembler* masm,
                                     Label* non_smi,
                                     Label* slow) {
  __ JumpIfNotSmi(a0, non_smi);

  // The result of negating zero or the smallest negative smi is not a smi.
  __ And(t0, a0, ~0x80000000);
  __ Branch(slow, eq, t0, Operand(zero_reg));

  // Return '0 - value'.
  __ Ret(USE_DELAY_SLOT);
  __ subu(v0, zero_reg, a0);
}


void UnaryOpStub::GenerateSmiCodeBitNot(MacroAssembler* masm,
                                        Label* non_smi) {
  __ JumpIfNotSmi(a0, non_smi);

  // Flip bits and revert inverted smi-tag.
  __ Neg(v0, a0);
  __ And(v0, v0, ~kSmiTagMask);
  __ Ret();
}


// TODO(svenpanne): Use virtual functions instead of switch.
void UnaryOpStub::GenerateHeapNumberStub(MacroAssembler* masm) {
  switch (op_) {
    case Token::SUB:
      GenerateHeapNumberStubSub(masm);
      break;
    case Token::BIT_NOT:
      GenerateHeapNumberStubBitNot(masm);
      break;
    default:
      UNREACHABLE();
  }
}


void UnaryOpStub::GenerateHeapNumberStubSub(MacroAssembler* masm) {
  Label non_smi, slow, call_builtin;
  GenerateSmiCodeSub(masm, &non_smi, &call_builtin);
  __ bind(&non_smi);
  GenerateHeapNumberCodeSub(masm, &slow);
  __ bind(&slow);
  GenerateTypeTransition(masm);
  __ bind(&call_builtin);
  GenerateGenericCodeFallback(masm);
}


void UnaryOpStub::GenerateHeapNumberStubBitNot(MacroAssembler* masm) {
  Label non_smi, slow;
  GenerateSmiCodeBitNot(masm, &non_smi);
  __ bind(&non_smi);
  GenerateHeapNumberCodeBitNot(masm, &slow);
  __ bind(&slow);
  GenerateTypeTransition(masm);
}


void UnaryOpStub::GenerateHeapNumberCodeSub(MacroAssembler* masm,
                                            Label* slow) {
  EmitCheckForHeapNumber(masm, a0, a1, t2, slow);
  // a0 is a heap number.  Get a new heap number in a1.
  if (mode_ == UNARY_OVERWRITE) {
    __ lw(a2, FieldMemOperand(a0, HeapNumber::kExponentOffset));
    __ Xor(a2, a2, Operand(HeapNumber::kSignMask));  // Flip sign.
    __ sw(a2, FieldMemOperand(a0, HeapNumber::kExponentOffset));
  } else {
    Label slow_allocate_heapnumber, heapnumber_allocated;
    __ AllocateHeapNumber(a1, a2, a3, t2, &slow_allocate_heapnumber);
    __ jmp(&heapnumber_allocated);

    __ bind(&slow_allocate_heapnumber);
    {
      FrameScope scope(masm, StackFrame::INTERNAL);
      __ push(a0);
      __ CallRuntime(Runtime::kNumberAlloc, 0);
      __ mov(a1, v0);
      __ pop(a0);
    }

    __ bind(&heapnumber_allocated);
    __ lw(a3, FieldMemOperand(a0, HeapNumber::kMantissaOffset));
    __ lw(a2, FieldMemOperand(a0, HeapNumber::kExponentOffset));
    __ sw(a3, FieldMemOperand(a1, HeapNumber::kMantissaOffset));
    __ Xor(a2, a2, Operand(HeapNumber::kSignMask));  // Flip sign.
    __ sw(a2, FieldMemOperand(a1, HeapNumber::kExponentOffset));
    __ mov(v0, a1);
  }
  __ Ret();
}


void UnaryOpStub::GenerateHeapNumberCodeBitNot(
    MacroAssembler* masm,
    Label* slow) {
  Label impossible;

  EmitCheckForHeapNumber(masm, a0, a1, t2, slow);
  // Convert the heap number in a0 to an untagged integer in a1.
  __ ConvertToInt32(a0, a1, a2, a3, f0, slow);

  // Do the bitwise operation and check if the result fits in a smi.
  Label try_float;
  __ Neg(a1, a1);
  __ Addu(a2, a1, Operand(0x40000000));
  __ Branch(&try_float, lt, a2, Operand(zero_reg));

  // Tag the result as a smi and we're done.
  __ SmiTag(v0, a1);
  __ Ret();

  // Try to store the result in a heap number.
  __ bind(&try_float);
  if (mode_ == UNARY_NO_OVERWRITE) {
    Label slow_allocate_heapnumber, heapnumber_allocated;
    // Allocate a new heap number without zapping v0, which we need if it fails.
    __ AllocateHeapNumber(a2, a3, t0, t2, &slow_allocate_heapnumber);
    __ jmp(&heapnumber_allocated);

    __ bind(&slow_allocate_heapnumber);
    {
      FrameScope scope(masm, StackFrame::INTERNAL);
      __ push(v0);  // Push the heap number, not the untagged int32.
      __ CallRuntime(Runtime::kNumberAlloc, 0);
      __ mov(a2, v0);  // Move the new heap number into a2.
      // Get the heap number into v0, now that the new heap number is in a2.
      __ pop(v0);
    }

    // Convert the heap number in v0 to an untagged integer in a1.
    // This can't go slow-case because it's the same number we already
    // converted once again.
    __ ConvertToInt32(v0, a1, a3, t0, f0, &impossible);
    // Negate the result.
    __ Xor(a1, a1, -1);

    __ bind(&heapnumber_allocated);
    __ mov(v0, a2);  // Move newly allocated heap number to v0.
  }

  if (CpuFeatures::IsSupported(FPU)) {
    // Convert the int32 in a1 to the heap number in v0. a2 is corrupted.
    CpuFeatures::Scope scope(FPU);
    __ mtc1(a1, f0);
    __ cvt_d_w(f0, f0);
    __ sdc1(f0, FieldMemOperand(v0, HeapNumber::kValueOffset));
    __ Ret();
  } else {
    // WriteInt32ToHeapNumberStub does not trigger GC, so we do not
    // have to set up a frame.
    WriteInt32ToHeapNumberStub stub(a1, v0, a2, a3);
    __ Jump(stub.GetCode(), RelocInfo::CODE_TARGET);
  }

  __ bind(&impossible);
  if (FLAG_debug_code) {
    __ stop("Incorrect assumption in bit-not stub");
  }
}


// TODO(svenpanne): Use virtual functions instead of switch.
void UnaryOpStub::GenerateGenericStub(MacroAssembler* masm) {
  switch (op_) {
    case Token::SUB:
      GenerateGenericStubSub(masm);
      break;
    case Token::BIT_NOT:
      GenerateGenericStubBitNot(masm);
      break;
    default:
      UNREACHABLE();
  }
}


void UnaryOpStub::GenerateGenericStubSub(MacroAssembler* masm) {
  Label non_smi, slow;
  GenerateSmiCodeSub(masm, &non_smi, &slow);
  __ bind(&non_smi);
  GenerateHeapNumberCodeSub(masm, &slow);
  __ bind(&slow);
  GenerateGenericCodeFallback(masm);
}


void UnaryOpStub::GenerateGenericStubBitNot(MacroAssembler* masm) {
  Label non_smi, slow;
  GenerateSmiCodeBitNot(masm, &non_smi);
  __ bind(&non_smi);
  GenerateHeapNumberCodeBitNot(masm, &slow);
  __ bind(&slow);
  GenerateGenericCodeFallback(masm);
}


void UnaryOpStub::GenerateGenericCodeFallback(
    MacroAssembler* masm) {
  // Handle the slow case by jumping to the JavaScript builtin.
  __ push(a0);
  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 BinaryOpStub::GenerateTypeTransition(MacroAssembler* masm) {
  Label get_result;

  __ Push(a1, a0);

  __ li(a2, Operand(Smi::FromInt(MinorKey())));
  __ li(a1, Operand(Smi::FromInt(op_)));
  __ li(a0, Operand(Smi::FromInt(operands_type_)));
  __ Push(a2, a1, a0);

  __ TailCallExternalReference(
      ExternalReference(IC_Utility(IC::kBinaryOp_Patch),
                        masm->isolate()),
      5,
      1);
}


void BinaryOpStub::GenerateTypeTransitionWithSavedArgs(
    MacroAssembler* masm) {
  UNIMPLEMENTED();
}


void BinaryOpStub::Generate(MacroAssembler* masm) {
  // Explicitly allow generation of nested stubs. It is safe here because
  // generation code does not use any raw pointers.
  AllowStubCallsScope allow_stub_calls(masm, true);
  switch (operands_type_) {
    case BinaryOpIC::UNINITIALIZED:
      GenerateTypeTransition(masm);
      break;
    case BinaryOpIC::SMI:
      GenerateSmiStub(masm);
      break;
    case BinaryOpIC::INT32:
      GenerateInt32Stub(masm);
      break;
    case BinaryOpIC::HEAP_NUMBER:
      GenerateHeapNumberStub(masm);
      break;
    case BinaryOpIC::ODDBALL:
      GenerateOddballStub(masm);
      break;
    case BinaryOpIC::BOTH_STRING:
      GenerateBothStringStub(masm);
      break;
    case BinaryOpIC::STRING:
      GenerateStringStub(masm);
      break;
    case BinaryOpIC::GENERIC:
      GenerateGeneric(masm);
      break;
    default:
      UNREACHABLE();
  }
}


void BinaryOpStub::PrintName(StringStream* stream) {
  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;
  }
  stream->Add("BinaryOpStub_%s_%s_%s",
              op_name,
              overwrite_name,
              BinaryOpIC::GetName(operands_type_));
}



void BinaryOpStub::GenerateSmiSmiOperation(MacroAssembler* masm) {
  Register left = a1;
  Register right = a0;

  Register scratch1 = t0;
  Register scratch2 = t1;

  ASSERT(right.is(a0));
  STATIC_ASSERT(kSmiTag == 0);

  Label not_smi_result;
  switch (op_) {
    case Token::ADD:
      __ AdduAndCheckForOverflow(v0, left, right, scratch1);
      __ RetOnNoOverflow(scratch1);
      // No need to revert anything - right and left are intact.
      break;
    case Token::SUB:
      __ SubuAndCheckForOverflow(v0, left, right, scratch1);
      __ RetOnNoOverflow(scratch1);
      // No need to revert anything - right and left are intact.
      break;
    case Token::MUL: {
      // Remove tag from one of the operands. This way the multiplication result
      // will be a smi if it fits the smi range.
      __ SmiUntag(scratch1, right);
      // Do multiplication.
      // lo = lower 32 bits of scratch1 * left.
      // hi = higher 32 bits of scratch1 * left.
      __ Mult(left, scratch1);
      // Check for overflowing the smi range - no overflow if higher 33 bits of
      // the result are identical.
      __ mflo(scratch1);
      __ mfhi(scratch2);
      __ sra(scratch1, scratch1, 31);
      __ Branch(&not_smi_result, ne, scratch1, Operand(scratch2));
      // Go slow on zero result to handle -0.
      __ mflo(v0);
      __ Ret(ne, v0, Operand(zero_reg));
      // We need -0 if we were multiplying a negative number with 0 to get 0.
      // We know one of them was zero.
      __ Addu(scratch2, right, left);
      Label skip;
      // ARM uses the 'pl' condition, which is 'ge'.
      // Negating it results in 'lt'.
      __ Branch(&skip, lt, scratch2, Operand(zero_reg));
      ASSERT(Smi::FromInt(0) == 0);
      __ Ret(USE_DELAY_SLOT);
      __ mov(v0, zero_reg);  // Return smi 0 if the non-zero one was positive.
      __ bind(&skip);
      // We fall through here if we multiplied a negative number with 0, because
      // that would mean we should produce -0.
      }
      break;
    case Token::DIV: {
      Label done;
      __ SmiUntag(scratch2, right);
      __ SmiUntag(scratch1, left);
      __ Div(scratch1, scratch2);
      // A minor optimization: div may be calculated asynchronously, so we check
      // for division by zero before getting the result.
      __ Branch(&not_smi_result, eq, scratch2, Operand(zero_reg));
      // If the result is 0, we need to make sure the dividsor (right) is
      // positive, otherwise it is a -0 case.
      // Quotient is in 'lo', remainder is in 'hi'.
      // Check for no remainder first.
      __ mfhi(scratch1);
      __ Branch(&not_smi_result, ne, scratch1, Operand(zero_reg));
      __ mflo(scratch1);
      __ Branch(&done, ne, scratch1, Operand(zero_reg));
      __ Branch(&not_smi_result, lt, scratch2, Operand(zero_reg));
      __ bind(&done);
      // Check that the signed result fits in a Smi.
      __ Addu(scratch2, scratch1, Operand(0x40000000));
      __ Branch(&not_smi_result, lt, scratch2, Operand(zero_reg));
      __ SmiTag(v0, scratch1);
      __ Ret();
      }
      break;
    case Token::MOD: {
      Label done;
      __ SmiUntag(scratch2, right);
      __ SmiUntag(scratch1, left);
      __ Div(scratch1, scratch2);
      // A minor optimization: div may be calculated asynchronously, so we check
      // for division by 0 before calling mfhi.
      // Check for zero on the right hand side.
      __ Branch(&not_smi_result, eq, scratch2, Operand(zero_reg));
      // If the result is 0, we need to make sure the dividend (left) is
      // positive (or 0), otherwise it is a -0 case.
      // Remainder is in 'hi'.
      __ mfhi(scratch2);
      __ Branch(&done, ne, scratch2, Operand(zero_reg));
      __ Branch(&not_smi_result, lt, scratch1, Operand(zero_reg));
      __ bind(&done);
      // Check that the signed result fits in a Smi.
      __ Addu(scratch1, scratch2, Operand(0x40000000));
      __ Branch(&not_smi_result, lt, scratch1, Operand(zero_reg));
      __ SmiTag(v0, scratch2);
      __ Ret();
      }
      break;
    case Token::BIT_OR:
      __ Ret(USE_DELAY_SLOT);
      __ or_(v0, left, right);
      break;
    case Token::BIT_AND:
      __ Ret(USE_DELAY_SLOT);
      __ and_(v0, left, right);
      break;
    case Token::BIT_XOR:
      __ Ret(USE_DELAY_SLOT);
      __ xor_(v0, left, right);
      break;
    case Token::SAR:
      // Remove tags from right operand.
      __ GetLeastBitsFromSmi(scratch1, right, 5);
      __ srav(scratch1, left, scratch1);
      // Smi tag result.
      __ And(v0, scratch1, ~kSmiTagMask);
      __ Ret();
      break;
    case Token::SHR:
      // Remove tags from operands. We can't do this on a 31 bit number
      // because then the 0s get shifted into bit 30 instead of bit 31.
      __ SmiUntag(scratch1, left);
      __ GetLeastBitsFromSmi(scratch2, right, 5);
      __ srlv(v0, scratch1, scratch2);
      // Unsigned shift is not allowed to produce a negative number, so
      // check the sign bit and the sign bit after Smi tagging.
      __ And(scratch1, v0, Operand(0xc0000000));
      __ Branch(&not_smi_result, ne, scratch1, Operand(zero_reg));
      // Smi tag result.
      __ SmiTag(v0);
      __ Ret();
      break;
    case Token::SHL:
      // Remove tags from operands.
      __ SmiUntag(scratch1, left);
      __ GetLeastBitsFromSmi(scratch2, right, 5);
      __ sllv(scratch1, scratch1, scratch2);
      // Check that the signed result fits in a Smi.
      __ Addu(scratch2, scratch1, Operand(0x40000000));
      __ Branch(&not_smi_result, lt, scratch2, Operand(zero_reg));
      __ SmiTag(v0, scratch1);
      __ Ret();
      break;
    default:
      UNREACHABLE();
  }
  __ bind(&not_smi_result);
}


void BinaryOpStub::GenerateFPOperation(MacroAssembler* masm,
                                       bool smi_operands,
                                       Label* not_numbers,
                                       Label* gc_required) {
  Register left = a1;
  Register right = a0;
  Register scratch1 = t3;
  Register scratch2 = t5;
  Register scratch3 = t0;

  ASSERT(smi_operands || (not_numbers != NULL));
  if (smi_operands && FLAG_debug_code) {
    __ AbortIfNotSmi(left);
    __ AbortIfNotSmi(right);
  }

  Register heap_number_map = t2;
  __ LoadRoot(heap_number_map, Heap::kHeapNumberMapRootIndex);

  switch (op_) {
    case Token::ADD:
    case Token::SUB:
    case Token::MUL:
    case Token::DIV:
    case Token::MOD: {
      // Load left and right operands into f12 and f14 or a0/a1 and a2/a3
      // depending on whether FPU is available or not.
      FloatingPointHelper::Destination destination =
          CpuFeatures::IsSupported(FPU) &&
          op_ != Token::MOD ?
              FloatingPointHelper::kFPURegisters :
              FloatingPointHelper::kCoreRegisters;

      // Allocate new heap number for result.
      Register result = s0;
      GenerateHeapResultAllocation(
          masm, result, heap_number_map, scratch1, scratch2, gc_required);

      // Load the operands.
      if (smi_operands) {
        FloatingPointHelper::LoadSmis(masm, destination, scratch1, scratch2);
      } else {
        FloatingPointHelper::LoadOperands(masm,
                                          destination,
                                          heap_number_map,
                                          scratch1,
                                          scratch2,
                                          not_numbers);
      }

      // Calculate the result.
      if (destination == FloatingPointHelper::kFPURegisters) {
        // Using FPU registers:
        // f12: Left value.
        // f14: Right value.
        CpuFeatures::Scope scope(FPU);
        switch (op_) {
        case Token::ADD:
          __ add_d(f10, f12, f14);
          break;
        case Token::SUB:
          __ sub_d(f10, f12, f14);
          break;
        case Token::MUL:
          __ mul_d(f10, f12, f14);
          break;
        case Token::DIV:
          __ div_d(f10, f12, f14);
          break;
        default:
          UNREACHABLE();
        }

        // ARM uses a workaround here because of the unaligned HeapNumber
        // kValueOffset. On MIPS this workaround is built into sdc1 so
        // there's no point in generating even more instructions.
        __ sdc1(f10, FieldMemOperand(result, HeapNumber::kValueOffset));
        __ Ret(USE_DELAY_SLOT);
        __ mov(v0, result);
      } else {
        // Call the C function to handle the double operation.
        FloatingPointHelper::CallCCodeForDoubleOperation(masm,
                                                         op_,
                                                         result,
                                                         scratch1);
        if (FLAG_debug_code) {
          __ stop("Unreachable code.");
        }
      }
      break;
    }
    case Token::BIT_OR:
    case Token::BIT_XOR:
    case Token::BIT_AND:
    case Token::SAR:
    case Token::SHR:
    case Token::SHL: {
      if (smi_operands) {
        __ SmiUntag(a3, left);
        __ SmiUntag(a2, right);
      } else {
        // Convert operands to 32-bit integers. Right in a2 and left in a3.
        FloatingPointHelper::ConvertNumberToInt32(masm,
                                                  left,
                                                  a3,
                                                  heap_number_map,
                                                  scratch1,
                                                  scratch2,
                                                  scratch3,
                                                  f0,
                                                  not_numbers);
        FloatingPointHelper::ConvertNumberToInt32(masm,
                                                  right,
                                                  a2,
                                                  heap_number_map,
                                                  scratch1,
                                                  scratch2,
                                                  scratch3,
                                                  f0,
                                                  not_numbers);
      }
      Label result_not_a_smi;
      switch (op_) {
        case Token::BIT_OR:
          __ Or(a2, a3, Operand(a2));
          break;
        case Token::BIT_XOR:
          __ Xor(a2, a3, Operand(a2));
          break;
        case Token::BIT_AND:
          __ And(a2, a3, Operand(a2));
          break;
        case Token::SAR:
          // Use only the 5 least significant bits of the shift count.
          __ GetLeastBitsFromInt32(a2, a2, 5);
          __ srav(a2, a3, a2);
          break;
        case Token::SHR:
          // Use only the 5 least significant bits of the shift count.
          __ GetLeastBitsFromInt32(a2, a2, 5);
          __ srlv(a2, a3, a2);
          // SHR is special because it is required to produce a positive answer.
          // The code below for writing into heap numbers isn't capable of
          // writing the register as an unsigned int so we go to slow case if we
          // hit this case.
          if (CpuFeatures::IsSupported(FPU)) {
            __ Branch(&result_not_a_smi, lt, a2, Operand(zero_reg));
          } else {
            __ Branch(not_numbers, lt, a2, Operand(zero_reg));
          }
          break;
        case Token::SHL:
          // Use only the 5 least significant bits of the shift count.
          __ GetLeastBitsFromInt32(a2, a2, 5);
          __ sllv(a2, a3, a2);
          break;
        default:
          UNREACHABLE();
      }
      // Check that the *signed* result fits in a smi.
      __ Addu(a3, a2, Operand(0x40000000));
      __ Branch(&result_not_a_smi, lt, a3, Operand(zero_reg));
      __ SmiTag(v0, a2);
      __ Ret();

      // Allocate new heap number for result.
      __ bind(&result_not_a_smi);
      Register result = t1;
      if (smi_operands) {
        __ AllocateHeapNumber(
            result, scratch1, scratch2, heap_number_map, gc_required);
      } else {
        GenerateHeapResultAllocation(
            masm, result, heap_number_map, scratch1, scratch2, gc_required);
      }

      // a2: Answer as signed int32.
      // t1: Heap number to write answer into.

      // Nothing can go wrong now, so move the heap number to v0, which is the
      // result.
      __ mov(v0, t1);

      if (CpuFeatures::IsSupported(FPU)) {
        // Convert the int32 in a2 to the heap number in a0. As
        // mentioned above SHR needs to always produce a positive result.
        CpuFeatures::Scope scope(FPU);
        __ mtc1(a2, f0);
        if (op_ == Token::SHR) {
          __ Cvt_d_uw(f0, f0, f22);
        } else {
          __ cvt_d_w(f0, f0);
        }
        // ARM uses a workaround here because of the unaligned HeapNumber
        // kValueOffset. On MIPS this workaround is built into sdc1 so
        // there's no point in generating even more instructions.
        __ sdc1(f0, FieldMemOperand(v0, HeapNumber::kValueOffset));
        __ Ret();
      } else {
        // Tail call that writes the int32 in a2 to the heap number in v0, using
        // a3 and a0 as scratch. v0 is preserved and returned.
        WriteInt32ToHeapNumberStub stub(a2, v0, a3, a0);
        __ TailCallStub(&stub);
      }
      break;
    }
    default:
      UNREACHABLE();
  }
}


// Generate the smi code. If the operation on smis are successful this return is
// generated. If the result is not a smi and heap number allocation is not
// requested the code falls through. If number allocation is requested but a
// heap number cannot be allocated the code jumps to the lable gc_required.
void BinaryOpStub::GenerateSmiCode(
    MacroAssembler* masm,
    Label* use_runtime,
    Label* gc_required,
    SmiCodeGenerateHeapNumberResults allow_heapnumber_results) {
  Label not_smis;

  Register left = a1;
  Register right = a0;
  Register scratch1 = t3;

  // Perform combined smi check on both operands.
  __ Or(scratch1, left, Operand(right));
  STATIC_ASSERT(kSmiTag == 0);
  __ JumpIfNotSmi(scratch1, &not_smis);

  // If the smi-smi operation results in a smi return is generated.
  GenerateSmiSmiOperation(masm);

  // If heap number results are possible generate the result in an allocated
  // heap number.
  if (allow_heapnumber_results == ALLOW_HEAPNUMBER_RESULTS) {
    GenerateFPOperation(masm, true, use_runtime, gc_required);
  }
  __ bind(&not_smis);
}


void BinaryOpStub::GenerateSmiStub(MacroAssembler* masm) {
  Label not_smis, call_runtime;

  if (result_type_ == BinaryOpIC::UNINITIALIZED ||
      result_type_ == BinaryOpIC::SMI) {
    // Only allow smi results.
    GenerateSmiCode(masm, &call_runtime, NULL, NO_HEAPNUMBER_RESULTS);
  } else {
    // Allow heap number result and don't make a transition if a heap number
    // cannot be allocated.
    GenerateSmiCode(masm,
                    &call_runtime,
                    &call_runtime,
                    ALLOW_HEAPNUMBER_RESULTS);
  }

  // Code falls through if the result is not returned as either a smi or heap
  // number.
  GenerateTypeTransition(masm);

  __ bind(&call_runtime);
  GenerateCallRuntime(masm);
}


void BinaryOpStub::GenerateStringStub(MacroAssembler* masm) {
  ASSERT(operands_type_ == BinaryOpIC::STRING);
  // Try to add arguments as strings, otherwise, transition to the generic
  // BinaryOpIC type.
  GenerateAddStrings(masm);
  GenerateTypeTransition(masm);
}


void BinaryOpStub::GenerateBothStringStub(MacroAssembler* masm) {
  Label call_runtime;
  ASSERT(operands_type_ == BinaryOpIC::BOTH_STRING);
  ASSERT(op_ == Token::ADD);
  // If both arguments are strings, call the string add stub.
  // Otherwise, do a transition.

  // Registers containing left and right operands respectively.
  Register left = a1;
  Register right = a0;

  // Test if left operand is a string.
  __ JumpIfSmi(left, &call_runtime);
  __ GetObjectType(left, a2, a2);
  __ Branch(&call_runtime, ge, a2, Operand(FIRST_NONSTRING_TYPE));

  // Test if right operand is a string.
  __ JumpIfSmi(right, &call_runtime);
  __ GetObjectType(right, a2, a2);
  __ Branch(&call_runtime, ge, a2, Operand(FIRST_NONSTRING_TYPE));

  StringAddStub string_add_stub(NO_STRING_CHECK_IN_STUB);
  GenerateRegisterArgsPush(masm);
  __ TailCallStub(&string_add_stub);

  __ bind(&call_runtime);
  GenerateTypeTransition(masm);
}


void BinaryOpStub::GenerateInt32Stub(MacroAssembler* masm) {
  ASSERT(operands_type_ == BinaryOpIC::INT32);

  Register left = a1;
  Register right = a0;
  Register scratch1 = t3;
  Register scratch2 = t5;
  FPURegister double_scratch = f0;
  FPURegister single_scratch = f6;

  Register heap_number_result = no_reg;
  Register heap_number_map = t2;
  __ LoadRoot(heap_number_map, Heap::kHeapNumberMapRootIndex);

  Label call_runtime;
  // Labels for type transition, used for wrong input or output types.
  // Both label are currently actually bound to the same position. We use two
  // different label to differentiate the cause leading to type transition.
  Label transition;

  // Smi-smi fast case.
  Label skip;
  __ Or(scratch1, left, right);
  __ JumpIfNotSmi(scratch1, &skip);
  GenerateSmiSmiOperation(masm);
  // Fall through if the result is not a smi.
  __ bind(&skip);

  switch (op_) {
    case Token::ADD:
    case Token::SUB:
    case Token::MUL:
    case Token::DIV:
    case Token::MOD: {
      // Load both operands and check that they are 32-bit integer.
      // Jump to type transition if they are not. The registers a0 and a1 (right
      // and left) are preserved for the runtime call.
      FloatingPointHelper::Destination destination =
          (CpuFeatures::IsSupported(FPU) && op_ != Token::MOD)
              ? FloatingPointHelper::kFPURegisters
              : FloatingPointHelper::kCoreRegisters;

      FloatingPointHelper::LoadNumberAsInt32Double(masm,
                                                   right,
                                                   destination,
                                                   f14,
                                                   a2,
                                                   a3,
                                                   heap_number_map,
                                                   scratch1,
                                                   scratch2,
                                                   f2,
                                                   &transition);
      FloatingPointHelper::LoadNumberAsInt32Double(masm,
                                                   left,
                                                   destination,
                                                   f12,
                                                   t0,
                                                   t1,
                                                   heap_number_map,
                                                   scratch1,
                                                   scratch2,
                                                   f2,
                                                   &transition);

      if (destination == FloatingPointHelper::kFPURegisters) {
        CpuFeatures::Scope scope(FPU);
        Label return_heap_number;
        switch (op_) {
          case Token::ADD:
            __ add_d(f10, f12, f14);
            break;
          case Token::SUB:
            __ sub_d(f10, f12, f14);
            break;
          case Token::MUL:
            __ mul_d(f10, f12, f14);
            break;
          case Token::DIV:
            __ div_d(f10, f12, f14);
            break;
          default:
            UNREACHABLE();
        }

        if (op_ != Token::DIV) {
          // These operations produce an integer result.
          // Try to return a smi if we can.
          // Otherwise return a heap number if allowed, or jump to type
          // transition.

          Register except_flag = scratch2;
          __ EmitFPUTruncate(kRoundToZero,
                             single_scratch,
                             f10,
                             scratch1,
                             except_flag);

          if (result_type_ <= BinaryOpIC::INT32) {
            // If except_flag != 0, result does not fit in a 32-bit integer.
            __ Branch(&transition, ne, except_flag, Operand(zero_reg));
          }

          // Check if the result fits in a smi.
          __ mfc1(scratch1, single_scratch);
          __ Addu(scratch2, scratch1, Operand(0x40000000));
          // If not try to return a heap number.
          __ Branch(&return_heap_number, lt, scratch2, Operand(zero_reg));
          // Check for minus zero. Return heap number for minus zero.
          Label not_zero;
          __ Branch(&not_zero, ne, scratch1, Operand(zero_reg));
          __ mfc1(scratch2, f11);
          __ And(scratch2, scratch2, HeapNumber::kSignMask);
          __ Branch(&return_heap_number, ne, scratch2, Operand(zero_reg));
          __ bind(&not_zero);

          // Tag the result and return.
          __ SmiTag(v0, scratch1);
          __ Ret();
        } else {
          // DIV just falls through to allocating a heap number.
        }

        __ bind(&return_heap_number);
        // Return a heap number, or fall through to type transition or runtime
        // call if we can't.
        if (result_type_ >= ((op_ == Token::DIV) ? BinaryOpIC::HEAP_NUMBER
                                                 : BinaryOpIC::INT32)) {
          // We are using FPU registers so s0 is available.
          heap_number_result = s0;
          GenerateHeapResultAllocation(masm,
                                       heap_number_result,
                                       heap_number_map,
                                       scratch1,
                                       scratch2,
                                       &call_runtime);
          __ mov(v0, heap_number_result);
          __ sdc1(f10, FieldMemOperand(v0, HeapNumber::kValueOffset));
          __ Ret();
        }

        // A DIV operation expecting an integer result falls through
        // to type transition.

      } else {
        // We preserved a0 and a1 to be able to call runtime.
        // Save the left value on the stack.
        __ Push(t1, t0);

        Label pop_and_call_runtime;

        // Allocate a heap number to store the result.
        heap_number_result = s0;
        GenerateHeapResultAllocation(masm,
                                     heap_number_result,
                                     heap_number_map,
                                     scratch1,
                                     scratch2,
                                     &pop_and_call_runtime);

        // Load the left value from the value saved on the stack.
        __ Pop(a1, a0);

        // Call the C function to handle the double operation.
        FloatingPointHelper::CallCCodeForDoubleOperation(
            masm, op_, heap_number_result, scratch1);
        if (FLAG_debug_code) {
          __ stop("Unreachable code.");
        }

        __ bind(&pop_and_call_runtime);
        __ Drop(2);
        __ Branch(&call_runtime);
      }

      break;
    }

    case Token::BIT_OR:
    case Token::BIT_XOR:
    case Token::BIT_AND:
    case Token::SAR:
    case Token::SHR:
    case Token::SHL: {
      Label return_heap_number;
      Register scratch3 = t1;
      // Convert operands to 32-bit integers. Right in a2 and left in a3. The
      // registers a0 and a1 (right and left) are preserved for the runtime
      // call.
      FloatingPointHelper::LoadNumberAsInt32(masm,
                                             left,
                                             a3,
                                             heap_number_map,
                                             scratch1,
                                             scratch2,
                                             scratch3,
                                             f0,
                                             &transition);
      FloatingPointHelper::LoadNumberAsInt32(masm,
                                             right,
                                             a2,
                                             heap_number_map,
                                             scratch1,
                                             scratch2,
                                             scratch3,
                                             f0,
                                             &transition);

      // The ECMA-262 standard specifies that, for shift operations, only the
      // 5 least significant bits of the shift value should be used.
      switch (op_) {
        case Token::BIT_OR:
          __ Or(a2, a3, Operand(a2));
          break;
        case Token::BIT_XOR:
          __ Xor(a2, a3, Operand(a2));
          break;
        case Token::BIT_AND:
          __ And(a2, a3, Operand(a2));
          break;
        case Token::SAR:
          __ And(a2, a2, Operand(0x1f));
          __ srav(a2, a3, a2);
          break;
        case Token::SHR:
          __ And(a2, a2, Operand(0x1f));
          __ srlv(a2, a3, a2);
          // SHR is special because it is required to produce a positive answer.
          // We only get a negative result if the shift value (a2) is 0.
          // This result cannot be respresented as a signed 32-bit integer, try
          // to return a heap number if we can.
          // The non FPU code does not support this special case, so jump to
          // runtime if we don't support it.
          if (CpuFeatures::IsSupported(FPU)) {
            __ Branch((result_type_ <= BinaryOpIC::INT32)
                        ? &transition
                        : &return_heap_number,
                       lt,
                       a2,
                       Operand(zero_reg));
          } else {
            __ Branch((result_type_ <= BinaryOpIC::INT32)
                        ? &transition
                        : &call_runtime,
                       lt,
                       a2,
                       Operand(zero_reg));
          }
          break;
        case Token::SHL:
          __ And(a2, a2, Operand(0x1f));
          __ sllv(a2, a3, a2);
          break;
        default:
          UNREACHABLE();
      }

      // Check if the result fits in a smi.
      __ Addu(scratch1, a2, Operand(0x40000000));
      // If not try to return a heap number. (We know the result is an int32.)
      __ Branch(&return_heap_number, lt, scratch1, Operand(zero_reg));
      // Tag the result and return.
      __ SmiTag(v0, a2);
      __ Ret();

      __ bind(&return_heap_number);
      heap_number_result = t1;
      GenerateHeapResultAllocation(masm,
                                   heap_number_result,
                                   heap_number_map,
                                   scratch1,
                                   scratch2,
                                   &call_runtime);

      if (CpuFeatures::IsSupported(FPU)) {
        CpuFeatures::Scope scope(FPU);

        if (op_ != Token::SHR) {
          // Convert the result to a floating point value.
          __ mtc1(a2, double_scratch);
          __ cvt_d_w(double_scratch, double_scratch);
        } else {
          // The result must be interpreted as an unsigned 32-bit integer.
          __ mtc1(a2, double_scratch);
          __ Cvt_d_uw(double_scratch, double_scratch, single_scratch);
        }

        // Store the result.
        __ mov(v0, heap_number_result);
        __ sdc1(double_scratch, FieldMemOperand(v0, HeapNumber::kValueOffset));
        __ Ret();
      } else {
        // Tail call that writes the int32 in a2 to the heap number in v0, using
        // a3 and a0 as scratch. v0 is preserved and returned.
        __ mov(v0, t1);
        WriteInt32ToHeapNumberStub stub(a2, v0, a3, a0);
        __ TailCallStub(&stub);
      }

      break;
    }

    default:
      UNREACHABLE();
  }

  // We never expect DIV to yield an integer result, so we always generate
  // type transition code for DIV operations expecting an integer result: the
  // code will fall through to this type transition.
  if (transition.is_linked() ||
      ((op_ == Token::DIV) && (result_type_ <= BinaryOpIC::INT32))) {
    __ bind(&transition);
    GenerateTypeTransition(masm);
  }

  __ bind(&call_runtime);
  GenerateCallRuntime(masm);
}


void BinaryOpStub::GenerateOddballStub(MacroAssembler* masm) {
  Label call_runtime;

  if (op_ == Token::ADD) {
    // Handle string addition here, because it is the only operation
    // that does not do a ToNumber conversion on the operands.
    GenerateAddStrings(masm);
  }

  // Convert oddball arguments to numbers.
  Label check, done;
  __ LoadRoot(t0, Heap::kUndefinedValueRootIndex);
  __ Branch(&check, ne, a1, Operand(t0));
  if (Token::IsBitOp(op_)) {
    __ li(a1, Operand(Smi::FromInt(0)));
  } else {
    __ LoadRoot(a1, Heap::kNanValueRootIndex);
  }
  __ jmp(&done);
  __ bind(&check);
  __ LoadRoot(t0, Heap::kUndefinedValueRootIndex);
  __ Branch(&done, ne, a0, Operand(t0));
  if (Token::IsBitOp(op_)) {
    __ li(a0, Operand(Smi::FromInt(0)));
  } else {
    __ LoadRoot(a0, Heap::kNanValueRootIndex);
  }
  __ bind(&done);

  GenerateHeapNumberStub(masm);
}


void BinaryOpStub::GenerateHeapNumberStub(MacroAssembler* masm) {
  Label call_runtime;
  GenerateFPOperation(masm, false, &call_runtime, &call_runtime);

  __ bind(&call_runtime);
  GenerateCallRuntime(masm);
}


void BinaryOpStub::GenerateGeneric(MacroAssembler* masm) {
  Label call_runtime, call_string_add_or_runtime;

  GenerateSmiCode(masm, &call_runtime, &call_runtime, ALLOW_HEAPNUMBER_RESULTS);

  GenerateFPOperation(masm, false, &call_string_add_or_runtime, &call_runtime);

  __ bind(&call_string_add_or_runtime);
  if (op_ == Token::ADD) {
    GenerateAddStrings(masm);
  }

  __ bind(&call_runtime);
  GenerateCallRuntime(masm);
}


void BinaryOpStub::GenerateAddStrings(MacroAssembler* masm) {
  ASSERT(op_ == Token::ADD);
  Label left_not_string, call_runtime;

  Register left = a1;
  Register right = a0;

  // Check if left argument is a string.
  __ JumpIfSmi(left, &left_not_string);
  __ GetObjectType(left, a2, a2);
  __ Branch(&left_not_string, ge, a2, Operand(FIRST_NONSTRING_TYPE));

  StringAddStub string_add_left_stub(NO_STRING_CHECK_LEFT_IN_STUB);
  GenerateRegisterArgsPush(masm);
  __ TailCallStub(&string_add_left_stub);

  // Left operand is not a string, test right.
  __ bind(&left_not_string);
  __ JumpIfSmi(right, &call_runtime);
  __ GetObjectType(right, a2, a2);
  __ Branch(&call_runtime, ge, a2, Operand(FIRST_NONSTRING_TYPE));

  StringAddStub string_add_right_stub(NO_STRING_CHECK_RIGHT_IN_STUB);
  GenerateRegisterArgsPush(masm);
  __ TailCallStub(&string_add_right_stub);

  // At least one argument is not a string.
  __ bind(&call_runtime);
}


void BinaryOpStub::GenerateCallRuntime(MacroAssembler* masm) {
  GenerateRegisterArgsPush(masm);
  switch (op_) {
    case Token::ADD:
      __ 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::SHR:
      __ InvokeBuiltin(Builtins::SHR, JUMP_FUNCTION);
      break;
    case Token::SHL:
      __ InvokeBuiltin(Builtins::SHL, JUMP_FUNCTION);
      break;
    default:
      UNREACHABLE();
  }
}


void BinaryOpStub::GenerateHeapResultAllocation(
    MacroAssembler* masm,
    Register result,
    Register heap_number_map,
    Register scratch1,
    Register scratch2,
    Label* gc_required) {

  // Code below will scratch result if allocation fails. To keep both arguments
  // intact for the runtime call result cannot be one of these.
  ASSERT(!result.is(a0) && !result.is(a1));

  if (mode_ == OVERWRITE_LEFT || mode_ == OVERWRITE_RIGHT) {
    Label skip_allocation, allocated;
    Register overwritable_operand = mode_ == OVERWRITE_LEFT ? a1 : a0;
    // If the overwritable operand is already an object, we skip the
    // allocation of a heap number.
    __ JumpIfNotSmi(overwritable_operand, &skip_allocation);
    // Allocate a heap number for the result.
    __ AllocateHeapNumber(
        result, scratch1, scratch2, heap_number_map, gc_required);
    __ Branch(&allocated);
    __ bind(&skip_allocation);
    // Use object holding the overwritable operand for result.
    __ mov(result, overwritable_operand);
    __ bind(&allocated);
  } else {
    ASSERT(mode_ == NO_OVERWRITE);
    __ AllocateHeapNumber(
        result, scratch1, scratch2, heap_number_map, gc_required);
  }
}


void BinaryOpStub::GenerateRegisterArgsPush(MacroAssembler* masm) {
  __ Push(a1, a0);
}



void TranscendentalCacheStub::Generate(MacroAssembler* masm) {
  // Untagged case: double input in f4, double result goes
  //   into f4.
  // Tagged case: tagged input on top of stack and in a0,
  //   tagged result (heap number) goes into v0.

  Label input_not_smi;
  Label loaded;
  Label calculate;
  Label invalid_cache;
  const Register scratch0 = t5;
  const Register scratch1 = t3;
  const Register cache_entry = a0;
  const bool tagged = (argument_type_ == TAGGED);

  if (CpuFeatures::IsSupported(FPU)) {
    CpuFeatures::Scope scope(FPU);

    if (tagged) {
      // Argument is a number and is on stack and in a0.
      // Load argument and check if it is a smi.
      __ JumpIfNotSmi(a0, &input_not_smi);

      // Input is a smi. Convert to double and load the low and high words
      // of the double into a2, a3.
      __ sra(t0, a0, kSmiTagSize);
      __ mtc1(t0, f4);
      __ cvt_d_w(f4, f4);
      __ Move(a2, a3, f4);
      __ Branch(&loaded);

      __ bind(&input_not_smi);
      // Check if input is a HeapNumber.
      __ CheckMap(a0,
                  a1,
                  Heap::kHeapNumberMapRootIndex,
                  &calculate,
                  DONT_DO_SMI_CHECK);
      // Input is a HeapNumber. Store the
      // low and high words into a2, a3.
      __ lw(a2, FieldMemOperand(a0, HeapNumber::kValueOffset));
      __ lw(a3, FieldMemOperand(a0, HeapNumber::kValueOffset + 4));
    } else {
      // Input is untagged double in f4. Output goes to f4.
      __ Move(a2, a3, f4);
    }
    __ bind(&loaded);
    // a2 = low 32 bits of double value.
    // a3 = 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);
    __ Xor(a1, a2, a3);
    __ sra(t0, a1, 16);
    __ Xor(a1, a1, t0);
    __ sra(t0, a1, 8);
    __ Xor(a1, a1, t0);
    ASSERT(IsPowerOf2(TranscendentalCache::SubCache::kCacheSize));
    __ And(a1, a1, Operand(TranscendentalCache::SubCache::kCacheSize - 1));

    // a2 = low 32 bits of double value.
    // a3 = high 32 bits of double value.
    // a1 = TranscendentalCache::hash(double value).
    __ li(cache_entry, Operand(
        ExternalReference::transcendental_cache_array_address(
            masm->isolate())));
    // a0 points to cache array.
    __ lw(cache_entry, MemOperand(cache_entry, type_ * sizeof(
        Isolate::Current()->transcendental_cache()->caches_[0])));
    // a0 points to the cache for the type type_.
    // If NULL, the cache hasn't been initialized yet, so go through runtime.
    __ Branch(&invalid_cache, eq, cache_entry, Operand(zero_reg));

#ifdef DEBUG
    // Check that the layout of cache elements match expectations.
    { TranscendentalCache::SubCache::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 a1'st entry in the cache, i.e., &a0[a1*12].
    __ sll(t0, a1, 1);
    __ Addu(a1, a1, t0);
    __ sll(t0, a1, 2);
    __ Addu(cache_entry, cache_entry, t0);

    // Check if cache matches: Double value is stored in uint32_t[2] array.
    __ lw(t0, MemOperand(cache_entry, 0));
    __ lw(t1, MemOperand(cache_entry, 4));
    __ lw(t2, MemOperand(cache_entry, 8));
    __ Branch(&calculate, ne, a2, Operand(t0));
    __ Branch(&calculate, ne, a3, Operand(t1));
    // Cache hit. Load result, cleanup and return.
    Counters* counters = masm->isolate()->counters();
    __ IncrementCounter(
        counters->transcendental_cache_hit(), 1, scratch0, scratch1);
    if (tagged) {
      // Pop input value from stack and load result into v0.
      __ Drop(1);
      __ mov(v0, t2);
    } else {
      // Load result into f4.
      __ ldc1(f4, FieldMemOperand(t2, HeapNumber::kValueOffset));
    }
    __ Ret();
  }  // if (CpuFeatures::IsSupported(FPU))

  __ bind(&calculate);
  Counters* counters = masm->isolate()->counters();
  __ IncrementCounter(
      counters->transcendental_cache_miss(), 1, scratch0, scratch1);
  if (tagged) {
    __ bind(&invalid_cache);
    __ TailCallExternalReference(ExternalReference(RuntimeFunction(),
                                                   masm->isolate()),
                                 1,
                                 1);
  } else {
    if (!CpuFeatures::IsSupported(FPU)) UNREACHABLE();
    CpuFeatures::Scope scope(FPU);

    Label no_update;
    Label skip_cache;

    // Call C function to calculate the result and update the cache.
    // Register a0 holds precalculated cache entry address; preserve
    // it on the stack and pop it into register cache_entry after the
    // call.
    __ Push(cache_entry, a2, a3);
    GenerateCallCFunction(masm, scratch0);
    __ GetCFunctionDoubleResult(f4);

    // Try to update the cache. If we cannot allocate a
    // heap number, we return the result without updating.
    __ Pop(cache_entry, a2, a3);
    __ LoadRoot(t1, Heap::kHeapNumberMapRootIndex);
    __ AllocateHeapNumber(t2, scratch0, scratch1, t1, &no_update);
    __ sdc1(f4, FieldMemOperand(t2, HeapNumber::kValueOffset));

    __ sw(a2, MemOperand(cache_entry, 0 * kPointerSize));
    __ sw(a3, MemOperand(cache_entry, 1 * kPointerSize));
    __ sw(t2, MemOperand(cache_entry, 2 * kPointerSize));

    __ Ret(USE_DELAY_SLOT);
    __ mov(v0, cache_entry);

    __ bind(&invalid_cache);
    // The cache is invalid. Call runtime which will recreate the
    // cache.
    __ LoadRoot(t1, Heap::kHeapNumberMapRootIndex);
    __ AllocateHeapNumber(a0, scratch0, scratch1, t1, &skip_cache);
    __ sdc1(f4, FieldMemOperand(a0, HeapNumber::kValueOffset));
    {
      FrameScope scope(masm, StackFrame::INTERNAL);
      __ push(a0);
      __ CallRuntime(RuntimeFunction(), 1);
    }
    __ ldc1(f4, FieldMemOperand(v0, HeapNumber::kValueOffset));
    __ Ret();

    __ bind(&skip_cache);
    // Call C function to calculate the result and answer directly
    // without updating the cache.
    GenerateCallCFunction(masm, scratch0);
    __ GetCFunctionDoubleResult(f4);
    __ bind(&no_update);

    // We return the value in f4 without adding it to the cache, but
    // we cause a scavenging GC so that future allocations will succeed.
    {
      FrameScope scope(masm, StackFrame::INTERNAL);

      // Allocate an aligned object larger than a HeapNumber.
      ASSERT(4 * kPointerSize >= HeapNumber::kSize);
      __ li(scratch0, Operand(4 * kPointerSize));
      __ push(scratch0);
      __ CallRuntimeSaveDoubles(Runtime::kAllocateInNewSpace);
    }
    __ Ret();
  }
}


void TranscendentalCacheStub::GenerateCallCFunction(MacroAssembler* masm,
                                                    Register scratch) {
  __ push(ra);
  __ PrepareCallCFunction(2, scratch);
  if (IsMipsSoftFloatABI) {
    __ Move(a0, a1, f4);
  } else {
    __ mov_d(f12, f4);
  }
  AllowExternalCallThatCantCauseGC scope(masm);
  Isolate* isolate = masm->isolate();
  switch (type_) {
    case TranscendentalCache::SIN:
      __ CallCFunction(
          ExternalReference::math_sin_double_function(isolate),
          0, 1);
      break;
    case TranscendentalCache::COS:
      __ CallCFunction(
          ExternalReference::math_cos_double_function(isolate),
          0, 1);
      break;
    case TranscendentalCache::TAN:
      __ CallCFunction(ExternalReference::math_tan_double_function(isolate),
          0, 1);
      break;
    case TranscendentalCache::LOG:
      __ CallCFunction(
          ExternalReference::math_log_double_function(isolate),
          0, 1);
      break;
    default:
      UNIMPLEMENTED();
      break;
  }
  __ pop(ra);
}


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;
    case TranscendentalCache::TAN: return Runtime::kMath_tan;
    case TranscendentalCache::LOG: return Runtime::kMath_log;
    default:
      UNIMPLEMENTED();
      return Runtime::kAbort;
  }
}


void StackCheckStub::Generate(MacroAssembler* masm) {
  __ TailCallRuntime(Runtime::kStackGuard, 0, 1);
}


void InterruptStub::Generate(MacroAssembler* masm) {
  __ TailCallRuntime(Runtime::kInterrupt, 0, 1);
}


void MathPowStub::Generate(MacroAssembler* masm) {
  CpuFeatures::Scope fpu_scope(FPU);
  const Register base = a1;
  const Register exponent = a2;
  const Register heapnumbermap = t1;
  const Register heapnumber = v0;
  const DoubleRegister double_base = f2;
  const DoubleRegister double_exponent = f4;
  const DoubleRegister double_result = f0;
  const DoubleRegister double_scratch = f6;
  const FPURegister single_scratch = f8;
  const Register scratch = t5;
  const Register scratch2 = t3;

  Label call_runtime, done, int_exponent;
  if (exponent_type_ == ON_STACK) {
    Label base_is_smi, unpack_exponent;
    // The exponent and base are supplied as arguments on the stack.
    // This can only happen if the stub is called from non-optimized code.
    // Load input parameters from stack to double registers.
    __ lw(base, MemOperand(sp, 1 * kPointerSize));
    __ lw(exponent, MemOperand(sp, 0 * kPointerSize));

    __ LoadRoot(heapnumbermap, Heap::kHeapNumberMapRootIndex);

    __ UntagAndJumpIfSmi(scratch, base, &base_is_smi);
    __ lw(scratch, FieldMemOperand(base, JSObject::kMapOffset));
    __ Branch(&call_runtime, ne, scratch, Operand(heapnumbermap));

    __ ldc1(double_base, FieldMemOperand(base, HeapNumber::kValueOffset));
    __ jmp(&unpack_exponent);

    __ bind(&base_is_smi);
    __ mtc1(scratch, single_scratch);
    __ cvt_d_w(double_base, single_scratch);
    __ bind(&unpack_exponent);

    __ UntagAndJumpIfSmi(scratch, exponent, &int_exponent);

    __ lw(scratch, FieldMemOperand(exponent, JSObject::kMapOffset));
    __ Branch(&call_runtime, ne, scratch, Operand(heapnumbermap));
    __ ldc1(double_exponent,
            FieldMemOperand(exponent, HeapNumber::kValueOffset));
  } else if (exponent_type_ == TAGGED) {
    // Base is already in double_base.
    __ UntagAndJumpIfSmi(scratch, exponent, &int_exponent);

    __ ldc1(double_exponent,
            FieldMemOperand(exponent, HeapNumber::kValueOffset));
  }

  if (exponent_type_ != INTEGER) {
    Label int_exponent_convert;
    // Detect integer exponents stored as double.
    __ EmitFPUTruncate(kRoundToMinusInf,
                       single_scratch,
                       double_exponent,
                       scratch,
                       scratch2,
                       kCheckForInexactConversion);
    // scratch2 == 0 means there was no conversion error.
    __ Branch(&int_exponent_convert, eq, scratch2, Operand(zero_reg));

    if (exponent_type_ == ON_STACK) {
      // Detect square root case.  Crankshaft detects constant +/-0.5 at
      // compile time and uses DoMathPowHalf instead.  We then skip this check
      // for non-constant cases of +/-0.5 as these hardly occur.
      Label not_plus_half;

      // Test for 0.5.
      __ Move(double_scratch, 0.5);
      __ BranchF(USE_DELAY_SLOT,
                 &not_plus_half,
                 NULL,
                 ne,
                 double_exponent,
                 double_scratch);
      // double_scratch can be overwritten in the delay slot.
      // Calculates square root of base.  Check for the special case of
      // Math.pow(-Infinity, 0.5) == Infinity (ECMA spec, 15.8.2.13).
      __ Move(double_scratch, -V8_INFINITY);
      __ BranchF(USE_DELAY_SLOT, &done, NULL, eq, double_base, double_scratch);
      __ neg_d(double_result, double_scratch);

      // Add +0 to convert -0 to +0.
      __ add_d(double_scratch, double_base, kDoubleRegZero);
      __ sqrt_d(double_result, double_scratch);
      __ jmp(&done);

      __ bind(&not_plus_half);
      __ Move(double_scratch, -0.5);
      __ BranchF(USE_DELAY_SLOT,
                 &call_runtime,
                 NULL,
                 ne,
                 double_exponent,
                 double_scratch);
      // double_scratch can be overwritten in the delay slot.
      // Calculates square root of base.  Check for the special case of
      // Math.pow(-Infinity, -0.5) == 0 (ECMA spec, 15.8.2.13).
      __ Move(double_scratch, -V8_INFINITY);
      __ BranchF(USE_DELAY_SLOT, &done, NULL, eq, double_base, double_scratch);
      __ Move(double_result, kDoubleRegZero);

      // Add +0 to convert -0 to +0.
      __ add_d(double_scratch, double_base, kDoubleRegZero);
      __ Move(double_result, 1);
      __ sqrt_d(double_scratch, double_scratch);
      __ div_d(double_result, double_result, double_scratch);
      __ jmp(&done);
    }

    __ push(ra);
    {
      AllowExternalCallThatCantCauseGC scope(masm);
      __ PrepareCallCFunction(0, 2, scratch);
      __ SetCallCDoubleArguments(double_base, double_exponent);
      __ CallCFunction(
          ExternalReference::power_double_double_function(masm->isolate()),
          0, 2);
    }
    __ pop(ra);
    __ GetCFunctionDoubleResult(double_result);
    __ jmp(&done);

    __ bind(&int_exponent_convert);
    __ mfc1(scratch, single_scratch);
  }

  // Calculate power with integer exponent.
  __ bind(&int_exponent);

  // Get two copies of exponent in the registers scratch and exponent.
  if (exponent_type_ == INTEGER) {
    __ mov(scratch, exponent);
  } else {
    // Exponent has previously been stored into scratch as untagged integer.
    __ mov(exponent, scratch);
  }

  __ mov_d(double_scratch, double_base);  // Back up base.
  __ Move(double_result, 1.0);

  // Get absolute value of exponent.
  Label positive_exponent;
  __ Branch(&positive_exponent, ge, scratch, Operand(zero_reg));
  __ Subu(scratch, zero_reg, scratch);
  __ bind(&positive_exponent);

  Label while_true, no_carry, loop_end;
  __ bind(&while_true);

  __ And(scratch2, scratch, 1);

  __ Branch(&no_carry, eq, scratch2, Operand(zero_reg));
  __ mul_d(double_result, double_result, double_scratch);
  __ bind(&no_carry);

  __ sra(scratch, scratch, 1);

  __ Branch(&loop_end, eq, scratch, Operand(zero_reg));
  __ mul_d(double_scratch, double_scratch, double_scratch);

  __ Branch(&while_true);

  __ bind(&loop_end);

  __ Branch(&done, ge, exponent, Operand(zero_reg));
  __ Move(double_scratch, 1.0);
  __ div_d(double_result, double_scratch, double_result);
  // Test whether result is zero.  Bail out to check for subnormal result.
  // Due to subnormals, x^-y == (1/x)^y does not hold in all cases.
  __ BranchF(&done, NULL, ne, double_result, kDoubleRegZero);

  // double_exponent may not contain the exponent value if the input was a
  // smi.  We set it with exponent value before bailing out.
  __ mtc1(exponent, single_scratch);
  __ cvt_d_w(double_exponent, single_scratch);

  // Returning or bailing out.
  Counters* counters = masm->isolate()->counters();
  if (exponent_type_ == ON_STACK) {
    // The arguments are still on the stack.
    __ bind(&call_runtime);
    __ TailCallRuntime(Runtime::kMath_pow_cfunction, 2, 1);

    // The stub is called from non-optimized code, which expects the result
    // as heap number in exponent.
    __ bind(&done);
    __ AllocateHeapNumber(
        heapnumber, scratch, scratch2, heapnumbermap, &call_runtime);
    __ sdc1(double_result,
            FieldMemOperand(heapnumber, HeapNumber::kValueOffset));
    ASSERT(heapnumber.is(v0));
    __ IncrementCounter(counters->math_pow(), 1, scratch, scratch2);
    __ DropAndRet(2);
  } else {
    __ push(ra);
    {
      AllowExternalCallThatCantCauseGC scope(masm);
      __ PrepareCallCFunction(0, 2, scratch);
      __ SetCallCDoubleArguments(double_base, double_exponent);
      __ CallCFunction(
          ExternalReference::power_double_double_function(masm->isolate()),
          0, 2);
    }
    __ pop(ra);
    __ GetCFunctionDoubleResult(double_result);

    __ bind(&done);
    __ IncrementCounter(counters->math_pow(), 1, scratch, scratch2);
    __ Ret();
  }
}


bool CEntryStub::NeedsImmovableCode() {
  return true;
}


bool CEntryStub::IsPregenerated() {
  return (!save_doubles_ || ISOLATE->fp_stubs_generated()) &&
          result_size_ == 1;
}


void CodeStub::GenerateStubsAheadOfTime() {
  CEntryStub::GenerateAheadOfTime();
  WriteInt32ToHeapNumberStub::GenerateFixedRegStubsAheadOfTime();
  StoreBufferOverflowStub::GenerateFixedRegStubsAheadOfTime();
  RecordWriteStub::GenerateFixedRegStubsAheadOfTime();
}


void CodeStub::GenerateFPStubs() {
  CEntryStub save_doubles(1, kSaveFPRegs);
  Handle<Code> code = save_doubles.GetCode();
  code->set_is_pregenerated(true);
  StoreBufferOverflowStub stub(kSaveFPRegs);
  stub.GetCode()->set_is_pregenerated(true);
  code->GetIsolate()->set_fp_stubs_generated(true);
}


void CEntryStub::GenerateAheadOfTime() {
  CEntryStub stub(1, kDontSaveFPRegs);
  Handle<Code> code = stub.GetCode();
  code->set_is_pregenerated(true);
}


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) {
  // v0: result parameter for PerformGC, if any
  // s0: number of arguments including receiver (C callee-saved)
  // s1: pointer to the first argument          (C callee-saved)
  // s2: pointer to builtin function            (C callee-saved)

  Isolate* isolate = masm->isolate();

  if (do_gc) {
    // Move result passed in v0 into a0 to call PerformGC.
    __ mov(a0, v0);
    __ PrepareCallCFunction(1, 0, a1);
    __ CallCFunction(ExternalReference::perform_gc_function(isolate), 1, 0);
  }

  ExternalReference scope_depth =
      ExternalReference::heap_always_allocate_scope_depth(isolate);
  if (always_allocate) {
    __ li(a0, Operand(scope_depth));
    __ lw(a1, MemOperand(a0));
    __ Addu(a1, a1, Operand(1));
    __ sw(a1, MemOperand(a0));
  }

  // Prepare arguments for C routine.
  // a0 = argc
  __ mov(a0, s0);
  // a1 = argv (set in the delay slot after find_ra below).

  // We are calling compiled C/C++ code. a0 and a1 hold our two arguments. We
  // also need to reserve the 4 argument slots on the stack.

  __ AssertStackIsAligned();

  __ li(a2, Operand(ExternalReference::isolate_address()));

  // To let the GC traverse the return address of the exit frames, we need to
  // know where the return address is. The CEntryStub is unmovable, so
  // we can store the address on the stack to be able to find it again and
  // we never have to restore it, because it will not change.
  { Assembler::BlockTrampolinePoolScope block_trampoline_pool(masm);
    // This branch-and-link sequence is needed to find the current PC on mips,
    // saved to the ra register.
    // Use masm-> here instead of the double-underscore macro since extra
    // coverage code can interfere with the proper calculation of ra.
    Label find_ra;
    masm->bal(&find_ra);  // bal exposes branch delay slot.
    masm->mov(a1, s1);
    masm->bind(&find_ra);

    // Adjust the value in ra to point to the correct return location, 2nd
    // instruction past the real call into C code (the jalr(t9)), and push it.
    // This is the return address of the exit frame.
    const int kNumInstructionsToJump = 5;
    masm->Addu(ra, ra, kNumInstructionsToJump * kPointerSize);
    masm->sw(ra, MemOperand(sp));  // This spot was reserved in EnterExitFrame.
    // Stack space reservation moved to the branch delay slot below.
    // Stack is still aligned.

    // Call the C routine.
    masm->mov(t9, s2);  // Function pointer to t9 to conform to ABI for PIC.
    masm->jalr(t9);
    // Set up sp in the delay slot.
    masm->addiu(sp, sp, -kCArgsSlotsSize);
    // Make sure the stored 'ra' points to this position.
    ASSERT_EQ(kNumInstructionsToJump,
              masm->InstructionsGeneratedSince(&find_ra));
  }

  if (always_allocate) {
    // It's okay to clobber a2 and a3 here. v0 & v1 contain result.
    __ li(a2, Operand(scope_depth));
    __ lw(a3, MemOperand(a2));
    __ Subu(a3, a3, Operand(1));
    __ sw(a3, MemOperand(a2));
  }

  // Check for failure result.
  Label failure_returned;
  STATIC_ASSERT(((kFailureTag + 1) & kFailureTagMask) == 0);
  __ addiu(a2, v0, 1);
  __ andi(t0, a2, kFailureTagMask);
  __ Branch(USE_DELAY_SLOT, &failure_returned, eq, t0, Operand(zero_reg));
  // Restore stack (remove arg slots) in branch delay slot.
  __ addiu(sp, sp, kCArgsSlotsSize);


  // Exit C frame and return.
  // v0:v1: result
  // sp: stack pointer
  // fp: frame pointer
  __ LeaveExitFrame(save_doubles_, s0, true);

  // Check if we should retry or throw exception.
  Label retry;
  __ bind(&failure_returned);
  STATIC_ASSERT(Failure::RETRY_AFTER_GC == 0);
  __ andi(t0, v0, ((1 << kFailureTypeTagSize) - 1) << kFailureTagSize);
  __ Branch(&retry, eq, t0, Operand(zero_reg));

  // Special handling of out of memory exceptions.
  Failure* out_of_memory = Failure::OutOfMemoryException();
  __ Branch(USE_DELAY_SLOT,
            throw_out_of_memory_exception,
            eq,
            v0,
            Operand(reinterpret_cast<int32_t>(out_of_memory)));
  // If we throw the OOM exception, the value of a3 doesn't matter.
  // Any instruction can be in the delay slot that's not a jump.

  // Retrieve the pending exception and clear the variable.
  __ LoadRoot(a3, Heap::kTheHoleValueRootIndex);
  __ li(t0, Operand(ExternalReference(Isolate::kPendingExceptionAddress,
                                      isolate)));
  __ lw(v0, MemOperand(t0));
  __ sw(a3, MemOperand(t0));

  // Special handling of termination exceptions which are uncatchable
  // by javascript code.
  __ LoadRoot(t0, Heap::kTerminationExceptionRootIndex);
  __ Branch(throw_termination_exception, eq, v0, Operand(t0));

  // Handle normal exception.
  __ jmp(throw_normal_exception);

  __ bind(&retry);
  // Last failure (v0) will be moved to (a0) for parameter when retrying.
}


void CEntryStub::Generate(MacroAssembler* masm) {
  // Called from JavaScript; parameters are on stack as if calling JS function
  // s0: number of arguments including receiver
  // s1: size of arguments excluding receiver
  // s2: pointer to builtin function
  // fp: frame pointer    (restored after C call)
  // sp: stack pointer    (restored as callee's sp after C call)
  // cp: current context  (C callee-saved)

  // NOTE: Invocations of builtins may return failure objects
  // instead of a proper result. The builtin entry handles
  // this by performing a garbage collection and retrying the
  // builtin once.

  // NOTE: s0-s2 hold the arguments of this function instead of a0-a2.
  // The reason for this is that these arguments would need to be saved anyway
  // so it's faster to set them up directly.
  // See MacroAssembler::PrepareCEntryArgs and PrepareCEntryFunction.

  // Compute the argv pointer in a callee-saved register.
  __ Addu(s1, sp, s1);

  // Enter the exit frame that transitions from JavaScript to C++.
  FrameScope scope(masm, StackFrame::MANUAL);
  __ EnterExitFrame(save_doubles_);

  // s0: number of arguments (C callee-saved)
  // s1: pointer to first argument (C callee-saved)
  // s2: pointer to builtin function (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();
  __ li(v0, Operand(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);
  // Set external caught exception to false.
  Isolate* isolate = masm->isolate();
  ExternalReference external_caught(Isolate::kExternalCaughtExceptionAddress,
                                    isolate);
  __ li(a0, Operand(false, RelocInfo::NONE));
  __ li(a2, Operand(external_caught));
  __ sw(a0, MemOperand(a2));

  // Set pending exception and v0 to out of memory exception.
  Failure* out_of_memory = Failure::OutOfMemoryException();
  __ li(v0, Operand(reinterpret_cast<int32_t>(out_of_memory)));
  __ li(a2, Operand(ExternalReference(Isolate::kPendingExceptionAddress,
                                      isolate)));
  __ sw(v0, MemOperand(a2));
  // Fall through to the next label.

  __ bind(&throw_termination_exception);
  __ ThrowUncatchable(v0);

  __ bind(&throw_normal_exception);
  __ Throw(v0);
}


void JSEntryStub::GenerateBody(MacroAssembler* masm, bool is_construct) {
  Label invoke, handler_entry, exit;
  Isolate* isolate = masm->isolate();

  // Registers:
  // a0: entry address
  // a1: function
  // a2: receiver
  // a3: argc
  //
  // Stack:
  // 4 args slots
  // args

  // Save callee saved registers on the stack.
  __ MultiPush(kCalleeSaved | ra.bit());

  if (CpuFeatures::IsSupported(FPU)) {
    CpuFeatures::Scope scope(FPU);
    // Save callee-saved FPU registers.
    __ MultiPushFPU(kCalleeSavedFPU);
    // Set up the reserved register for 0.0.
    __ Move(kDoubleRegZero, 0.0);
  }


  // Load argv in s0 register.
  int offset_to_argv = (kNumCalleeSaved + 1) * kPointerSize;
  if (CpuFeatures::IsSupported(FPU)) {
    offset_to_argv += kNumCalleeSavedFPU * kDoubleSize;
  }

  __ InitializeRootRegister();
  __ lw(s0, MemOperand(sp, offset_to_argv + kCArgsSlotsSize));

  // We build an EntryFrame.
  __ li(t3, Operand(-1));  // Push a bad frame pointer to fail if it is used.
  int marker = is_construct ? StackFrame::ENTRY_CONSTRUCT : StackFrame::ENTRY;
  __ li(t2, Operand(Smi::FromInt(marker)));
  __ li(t1, Operand(Smi::FromInt(marker)));
  __ li(t0, Operand(ExternalReference(Isolate::kCEntryFPAddress,
                                      isolate)));
  __ lw(t0, MemOperand(t0));
  __ Push(t3, t2, t1, t0);
  // Set up frame pointer for the frame to be pushed.
  __ addiu(fp, sp, -EntryFrameConstants::kCallerFPOffset);

  // Registers:
  // a0: entry_address
  // a1: function
  // a2: receiver_pointer
  // a3: argc
  // s0: argv
  //
  // Stack:
  // caller fp          |
  // function slot      | entry frame
  // context slot       |
  // bad fp (0xff...f)  |
  // callee saved registers + ra
  // 4 args slots
  // args

  // If this is the outermost JS call, set js_entry_sp value.
  Label non_outermost_js;
  ExternalReference js_entry_sp(Isolate::kJSEntrySPAddress, isolate);
  __ li(t1, Operand(ExternalReference(js_entry_sp)));
  __ lw(t2, MemOperand(t1));
  __ Branch(&non_outermost_js, ne, t2, Operand(zero_reg));
  __ sw(fp, MemOperand(t1));
  __ li(t0, Operand(Smi::FromInt(StackFrame::OUTERMOST_JSENTRY_FRAME)));
  Label cont;
  __ b(&cont);
  __ nop();   // Branch delay slot nop.
  __ bind(&non_outermost_js);
  __ li(t0, Operand(Smi::FromInt(StackFrame::INNER_JSENTRY_FRAME)));
  __ bind(&cont);
  __ push(t0);

  // Jump to a faked try block that does the invoke, with a faked catch
  // block that sets the pending exception.
  __ jmp(&invoke);
  __ bind(&handler_entry);
  handler_offset_ = handler_entry.pos();
  // Caught exception: Store result (exception) in the pending exception
  // field in the JSEnv and return a failure sentinel.  Coming in here the
  // fp will be invalid because the PushTryHandler below sets it to 0 to
  // signal the existence of the JSEntry frame.
  __ li(t0, Operand(ExternalReference(Isolate::kPendingExceptionAddress,
                                      isolate)));
  __ sw(v0, MemOperand(t0));  // We come back from 'invoke'. result is in v0.
  __ li(v0, Operand(reinterpret_cast<int32_t>(Failure::Exception())));
  __ b(&exit);  // b exposes branch delay slot.
  __ nop();   // Branch delay slot nop.

  // Invoke: Link this frame into the handler chain.  There's only one
  // handler block in this code object, so its index is 0.
  __ bind(&invoke);
  __ PushTryHandler(StackHandler::JS_ENTRY, 0);
  // If an exception not caught by another handler occurs, this handler
  // returns control to the code after the bal(&invoke) above, which
  // restores all kCalleeSaved registers (including cp and fp) to their
  // saved values before returning a failure to C.

  // Clear any pending exceptions.
  __ LoadRoot(t1, Heap::kTheHoleValueRootIndex);
  __ li(t0, Operand(ExternalReference(Isolate::kPendingExceptionAddress,
                                      isolate)));
  __ sw(t1, MemOperand(t0));

  // Invoke the function by calling through JS entry trampoline builtin.
  // Notice that we cannot store a reference to the trampoline code directly in
  // this stub, because runtime stubs are not traversed when doing GC.

  // Registers:
  // a0: entry_address
  // a1: function
  // a2: receiver_pointer
  // a3: argc
  // s0: argv
  //
  // Stack:
  // handler frame
  // entry frame
  // callee saved registers + ra
  // 4 args slots
  // args

  if (is_construct) {
    ExternalReference construct_entry(Builtins::kJSConstructEntryTrampoline,
                                      isolate);
    __ li(t0, Operand(construct_entry));
  } else {
    ExternalReference entry(Builtins::kJSEntryTrampoline, masm->isolate());
    __ li(t0, Operand(entry));
  }
  __ lw(t9, MemOperand(t0));  // Deref address.

  // Call JSEntryTrampoline.
  __ addiu(t9, t9, Code::kHeaderSize - kHeapObjectTag);
  __ Call(t9);

  // Unlink this frame from the handler chain.
  __ PopTryHandler();

  __ bind(&exit);  // v0 holds result
  // Check if the current stack frame is marked as the outermost JS frame.
  Label non_outermost_js_2;
  __ pop(t1);
  __ Branch(&non_outermost_js_2,
            ne,
            t1,
            Operand(Smi::FromInt(StackFrame::OUTERMOST_JSENTRY_FRAME)));
  __ li(t1, Operand(ExternalReference(js_entry_sp)));
  __ sw(zero_reg, MemOperand(t1));
  __ bind(&non_outermost_js_2);

  // Restore the top frame descriptors from the stack.
  __ pop(t1);
  __ li(t0, Operand(ExternalReference(Isolate::kCEntryFPAddress,
                                      isolate)));
  __ sw(t1, MemOperand(t0));

  // Reset the stack to the callee saved registers.
  __ addiu(sp, sp, -EntryFrameConstants::kCallerFPOffset);

  if (CpuFeatures::IsSupported(FPU)) {
    CpuFeatures::Scope scope(FPU);
    // Restore callee-saved fpu registers.
    __ MultiPopFPU(kCalleeSavedFPU);
  }

  // Restore callee saved registers from the stack.
  __ MultiPop(kCalleeSaved | ra.bit());
  // Return.
  __ Jump(ra);
}


// Uses registers a0 to t0.
// Expected input (depending on whether args are in registers or on the stack):
// * object: a0 or at sp + 1 * kPointerSize.
// * function: a1 or at sp.
//
// An inlined call site may have been generated before calling this stub.
// In this case the offset to the inline site to patch is passed on the stack,
// in the safepoint slot for register t0.
void InstanceofStub::Generate(MacroAssembler* masm) {
  // Call site inlining and patching implies arguments in registers.
  ASSERT(HasArgsInRegisters() || !HasCallSiteInlineCheck());
  // ReturnTrueFalse is only implemented for inlined call sites.
  ASSERT(!ReturnTrueFalseObject() || HasCallSiteInlineCheck());

  // Fixed register usage throughout the stub:
  const Register object = a0;  // Object (lhs).
  Register map = a3;  // Map of the object.
  const Register function = a1;  // Function (rhs).
  const Register prototype = t0;  // Prototype of the function.
  const Register inline_site = t5;
  const Register scratch = a2;

  const int32_t kDeltaToLoadBoolResult = 5 * kPointerSize;

  Label slow, loop, is_instance, is_not_instance, not_js_object;

  if (!HasArgsInRegisters()) {
    __ lw(object, MemOperand(sp, 1 * kPointerSize));
    __ lw(function, MemOperand(sp, 0));
  }

  // Check that the left hand is a JS object and load map.
  __ JumpIfSmi(object, &not_js_object);
  __ IsObjectJSObjectType(object, map, scratch, &not_js_object);

  // If there is a call site cache don't look in the global cache, but do the
  // real lookup and update the call site cache.
  if (!HasCallSiteInlineCheck()) {
    Label miss;
    __ LoadRoot(at, Heap::kInstanceofCacheFunctionRootIndex);
    __ Branch(&miss, ne, function, Operand(at));
    __ LoadRoot(at, Heap::kInstanceofCacheMapRootIndex);
    __ Branch(&miss, ne, map, Operand(at));
    __ LoadRoot(v0, Heap::kInstanceofCacheAnswerRootIndex);
    __ DropAndRet(HasArgsInRegisters() ? 0 : 2);

    __ bind(&miss);
  }

  // Get the prototype of the function.
  __ TryGetFunctionPrototype(function, prototype, scratch, &slow, true);

  // Check that the function prototype is a JS object.
  __ JumpIfSmi(prototype, &slow);
  __ IsObjectJSObjectType(prototype, scratch, scratch, &slow);

  // Update the global instanceof or call site inlined cache with the current
  // map and function. The cached answer will be set when it is known below.
  if (!HasCallSiteInlineCheck()) {
    __ StoreRoot(function, Heap::kInstanceofCacheFunctionRootIndex);
    __ StoreRoot(map, Heap::kInstanceofCacheMapRootIndex);
  } else {
    ASSERT(HasArgsInRegisters());
    // Patch the (relocated) inlined map check.

    // The offset was stored in t0 safepoint slot.
    // (See LCodeGen::DoDeferredLInstanceOfKnownGlobal).
    __ LoadFromSafepointRegisterSlot(scratch, t0);
    __ Subu(inline_site, ra, scratch);
    // Get the map location in scratch and patch it.
    __ GetRelocatedValue(inline_site, scratch, v1);  // v1 used as scratch.
    __ sw(map, FieldMemOperand(scratch, JSGlobalPropertyCell::kValueOffset));
  }

  // Register mapping: a3 is object map and t0 is function prototype.
  // Get prototype of object into a2.
  __ lw(scratch, FieldMemOperand(map, Map::kPrototypeOffset));

  // We don't need map any more. Use it as a scratch register.
  Register scratch2 = map;
  map = no_reg;

  // Loop through the prototype chain looking for the function prototype.
  __ LoadRoot(scratch2, Heap::kNullValueRootIndex);
  __ bind(&loop);
  __ Branch(&is_instance, eq, scratch, Operand(prototype));
  __ Branch(&is_not_instance, eq, scratch, Operand(scratch2));
  __ lw(scratch, FieldMemOperand(scratch, HeapObject::kMapOffset));
  __ lw(scratch, FieldMemOperand(scratch, Map::kPrototypeOffset));
  __ Branch(&loop);

  __ bind(&is_instance);
  ASSERT(Smi::FromInt(0) == 0);
  if (!HasCallSiteInlineCheck()) {
    __ mov(v0, zero_reg);
    __ StoreRoot(v0, Heap::kInstanceofCacheAnswerRootIndex);
  } else {
    // Patch the call site to return true.
    __ LoadRoot(v0, Heap::kTrueValueRootIndex);
    __ Addu(inline_site, inline_site, Operand(kDeltaToLoadBoolResult));
    // Get the boolean result location in scratch and patch it.
    __ PatchRelocatedValue(inline_site, scratch, v0);

    if (!ReturnTrueFalseObject()) {
      ASSERT_EQ(Smi::FromInt(0), 0);
      __ mov(v0, zero_reg);
    }
  }
  __ DropAndRet(HasArgsInRegisters() ? 0 : 2);

  __ bind(&is_not_instance);
  if (!HasCallSiteInlineCheck()) {
    __ li(v0, Operand(Smi::FromInt(1)));
    __ StoreRoot(v0, Heap::kInstanceofCacheAnswerRootIndex);
  } else {
    // Patch the call site to return false.
    __ LoadRoot(v0, Heap::kFalseValueRootIndex);
    __ Addu(inline_site, inline_site, Operand(kDeltaToLoadBoolResult));
    // Get the boolean result location in scratch and patch it.
    __ PatchRelocatedValue(inline_site, scratch, v0);

    if (!ReturnTrueFalseObject()) {
      __ li(v0, Operand(Smi::FromInt(1)));
    }
  }

  __ DropAndRet(HasArgsInRegisters() ? 0 : 2);

  Label object_not_null, object_not_null_or_smi;
  __ bind(&not_js_object);
  // Before null, smi and string value checks, check that the rhs is a function
  // as for a non-function rhs an exception needs to be thrown.
  __ JumpIfSmi(function, &slow);
  __ GetObjectType(function, scratch2, scratch);
  __ Branch(&slow, ne, scratch, Operand(JS_FUNCTION_TYPE));

  // Null is not instance of anything.
  __ Branch(&object_not_null,
            ne,
            scratch,
            Operand(masm->isolate()->factory()->null_value()));
  __ li(v0, Operand(Smi::FromInt(1)));
  __ DropAndRet(HasArgsInRegisters() ? 0 : 2);

  __ bind(&object_not_null);
  // Smi values are not instances of anything.
  __ JumpIfNotSmi(object, &object_not_null_or_smi);
  __ li(v0, Operand(Smi::FromInt(1)));
  __ DropAndRet(HasArgsInRegisters() ? 0 : 2);

  __ bind(&object_not_null_or_smi);
  // String values are not instances of anything.
  __ IsObjectJSStringType(object, scratch, &slow);
  __ li(v0, Operand(Smi::FromInt(1)));
  __ DropAndRet(HasArgsInRegisters() ? 0 : 2);

  // Slow-case.  Tail call builtin.
  __ bind(&slow);
  if (!ReturnTrueFalseObject()) {
    if (HasArgsInRegisters()) {
      __ Push(a0, a1);
    }
  __ InvokeBuiltin(Builtins::INSTANCE_OF, JUMP_FUNCTION);
  } else {
    {
      FrameScope scope(masm, StackFrame::INTERNAL);
      __ Push(a0, a1);
      __ InvokeBuiltin(Builtins::INSTANCE_OF, CALL_FUNCTION);
    }
    __ mov(a0, v0);
    __ LoadRoot(v0, Heap::kTrueValueRootIndex);
    __ DropAndRet(HasArgsInRegisters() ? 0 : 2, eq, a0, Operand(zero_reg));
    __ LoadRoot(v0, Heap::kFalseValueRootIndex);
    __ DropAndRet(HasArgsInRegisters() ? 0 : 2);
  }
}


Register InstanceofStub::left() { return a0; }


Register InstanceofStub::right() { return a1; }


void ArgumentsAccessStub::GenerateReadElement(MacroAssembler* masm) {
  // The displacement is the offset of the last parameter (if any)
  // relative to the frame pointer.
  const int kDisplacement =
      StandardFrameConstants::kCallerSPOffset - kPointerSize;

  // Check that the key is a smiGenerateReadElement.
  Label slow;
  __ JumpIfNotSmi(a1, &slow);

  // Check if the calling frame is an arguments adaptor frame.
  Label adaptor;
  __ lw(a2, MemOperand(fp, StandardFrameConstants::kCallerFPOffset));
  __ lw(a3, MemOperand(a2, StandardFrameConstants::kContextOffset));
  __ Branch(&adaptor,
            eq,
            a3,
            Operand(Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR)));

  // Check index (a1) against formal parameters count limit passed in
  // through register a0. Use unsigned comparison to get negative
  // check for free.
  __ Branch(&slow, hs, a1, Operand(a0));

  // Read the argument from the stack and return it.
  __ subu(a3, a0, a1);
  __ sll(t3, a3, kPointerSizeLog2 - kSmiTagSize);
  __ Addu(a3, fp, Operand(t3));
  __ lw(v0, MemOperand(a3, kDisplacement));
  __ Ret();

  // Arguments adaptor case: Check index (a1) against actual arguments
  // limit found in the arguments adaptor frame. Use unsigned
  // comparison to get negative check for free.
  __ bind(&adaptor);
  __ lw(a0, MemOperand(a2, ArgumentsAdaptorFrameConstants::kLengthOffset));
  __ Branch(&slow, Ugreater_equal, a1, Operand(a0));

  // Read the argument from the adaptor frame and return it.
  __ subu(a3, a0, a1);
  __ sll(t3, a3, kPointerSizeLog2 - kSmiTagSize);
  __ Addu(a3, a2, Operand(t3));
  __ lw(v0, MemOperand(a3, kDisplacement));
  __ Ret();

  // Slow-case: Handle non-smi or out-of-bounds access to arguments
  // by calling the runtime system.
  __ bind(&slow);
  __ push(a1);
  __ TailCallRuntime(Runtime::kGetArgumentsProperty, 1, 1);
}


void ArgumentsAccessStub::GenerateNewNonStrictSlow(MacroAssembler* masm) {
  // sp[0] : number of parameters
  // sp[4] : receiver displacement
  // sp[8] : function
  // Check if the calling frame is an arguments adaptor frame.
  Label runtime;
  __ lw(a3, MemOperand(fp, StandardFrameConstants::kCallerFPOffset));
  __ lw(a2, MemOperand(a3, StandardFrameConstants::kContextOffset));
  __ Branch(&runtime,
            ne,
            a2,
            Operand(Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR)));

  // Patch the arguments.length and the parameters pointer in the current frame.
  __ lw(a2, MemOperand(a3, ArgumentsAdaptorFrameConstants::kLengthOffset));
  __ sw(a2, MemOperand(sp, 0 * kPointerSize));
  __ sll(t3, a2, 1);
  __ Addu(a3, a3, Operand(t3));
  __ addiu(a3, a3, StandardFrameConstants::kCallerSPOffset);
  __ sw(a3, MemOperand(sp, 1 * kPointerSize));

  __ bind(&runtime);
  __ TailCallRuntime(Runtime::kNewArgumentsFast, 3, 1);
}


void ArgumentsAccessStub::GenerateNewNonStrictFast(MacroAssembler* masm) {
  // Stack layout:
  //  sp[0] : number of parameters (tagged)
  //  sp[4] : address of receiver argument
  //  sp[8] : function
  // Registers used over whole function:
  //  t2 : allocated object (tagged)
  //  t5 : mapped parameter count (tagged)

  __ lw(a1, MemOperand(sp, 0 * kPointerSize));
  // a1 = parameter count (tagged)

  // Check if the calling frame is an arguments adaptor frame.
  Label runtime;
  Label adaptor_frame, try_allocate;
  __ lw(a3, MemOperand(fp, StandardFrameConstants::kCallerFPOffset));
  __ lw(a2, MemOperand(a3, StandardFrameConstants::kContextOffset));
  __ Branch(&adaptor_frame,
            eq,
            a2,
            Operand(Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR)));

  // No adaptor, parameter count = argument count.
  __ mov(a2, a1);
  __ b(&try_allocate);
  __ nop();   // Branch delay slot nop.

  // We have an adaptor frame. Patch the parameters pointer.
  __ bind(&adaptor_frame);
  __ lw(a2, MemOperand(a3, ArgumentsAdaptorFrameConstants::kLengthOffset));
  __ sll(t6, a2, 1);
  __ Addu(a3, a3, Operand(t6));
  __ Addu(a3, a3, Operand(StandardFrameConstants::kCallerSPOffset));
  __ sw(a3, MemOperand(sp, 1 * kPointerSize));

  // a1 = parameter count (tagged)
  // a2 = argument count (tagged)
  // Compute the mapped parameter count = min(a1, a2) in a1.
  Label skip_min;
  __ Branch(&skip_min, lt, a1, Operand(a2));
  __ mov(a1, a2);
  __ bind(&skip_min);

  __ bind(&try_allocate);

  // Compute the sizes of backing store, parameter map, and arguments object.
  // 1. Parameter map, has 2 extra words containing context and backing store.
  const int kParameterMapHeaderSize =
      FixedArray::kHeaderSize + 2 * kPointerSize;
  // If there are no mapped parameters, we do not need the parameter_map.
  Label param_map_size;
  ASSERT_EQ(0, Smi::FromInt(0));
  __ Branch(USE_DELAY_SLOT, &param_map_size, eq, a1, Operand(zero_reg));
  __ mov(t5, zero_reg);  // In delay slot: param map size = 0 when a1 == 0.
  __ sll(t5, a1, 1);
  __ addiu(t5, t5, kParameterMapHeaderSize);
  __ bind(&param_map_size);

  // 2. Backing store.
  __ sll(t6, a2, 1);
  __ Addu(t5, t5, Operand(t6));
  __ Addu(t5, t5, Operand(FixedArray::kHeaderSize));

  // 3. Arguments object.
  __ Addu(t5, t5, Operand(Heap::kArgumentsObjectSize));

  // Do the allocation of all three objects in one go.
  __ AllocateInNewSpace(t5, v0, a3, t0, &runtime, TAG_OBJECT);

  // v0 = address of new object(s) (tagged)
  // a2 = argument count (tagged)
  // Get the arguments boilerplate from the current (global) context into t0.
  const int kNormalOffset =
      Context::SlotOffset(Context::ARGUMENTS_BOILERPLATE_INDEX);
  const int kAliasedOffset =
      Context::SlotOffset(Context::ALIASED_ARGUMENTS_BOILERPLATE_INDEX);

  __ lw(t0, MemOperand(cp, Context::SlotOffset(Context::GLOBAL_INDEX)));
  __ lw(t0, FieldMemOperand(t0, GlobalObject::kGlobalContextOffset));
  Label skip2_ne, skip2_eq;
  __ Branch(&skip2_ne, ne, a1, Operand(zero_reg));
  __ lw(t0, MemOperand(t0, kNormalOffset));
  __ bind(&skip2_ne);

  __ Branch(&skip2_eq, eq, a1, Operand(zero_reg));
  __ lw(t0, MemOperand(t0, kAliasedOffset));
  __ bind(&skip2_eq);

  // v0 = address of new object (tagged)
  // a1 = mapped parameter count (tagged)
  // a2 = argument count (tagged)
  // t0 = address of boilerplate object (tagged)
  // Copy the JS object part.
  for (int i = 0; i < JSObject::kHeaderSize; i += kPointerSize) {
    __ lw(a3, FieldMemOperand(t0, i));
    __ sw(a3, FieldMemOperand(v0, i));
  }

  // Set up the callee in-object property.
  STATIC_ASSERT(Heap::kArgumentsCalleeIndex == 1);
  __ lw(a3, MemOperand(sp, 2 * kPointerSize));
  const int kCalleeOffset = JSObject::kHeaderSize +
      Heap::kArgumentsCalleeIndex * kPointerSize;
  __ sw(a3, FieldMemOperand(v0, kCalleeOffset));

  // Use the length (smi tagged) and set that as an in-object property too.
  STATIC_ASSERT(Heap::kArgumentsLengthIndex == 0);
  const int kLengthOffset = JSObject::kHeaderSize +
      Heap::kArgumentsLengthIndex * kPointerSize;
  __ sw(a2, FieldMemOperand(v0, kLengthOffset));

  // Set up the elements pointer in the allocated arguments object.
  // If we allocated a parameter map, t0 will point there, otherwise
  // it will point to the backing store.
  __ Addu(t0, v0, Operand(Heap::kArgumentsObjectSize));
  __ sw(t0, FieldMemOperand(v0, JSObject::kElementsOffset));

  // v0 = address of new object (tagged)
  // a1 = mapped parameter count (tagged)
  // a2 = argument count (tagged)
  // t0 = address of parameter map or backing store (tagged)
  // Initialize parameter map. If there are no mapped arguments, we're done.
  Label skip_parameter_map;
  Label skip3;
  __ Branch(&skip3, ne, a1, Operand(Smi::FromInt(0)));
  // Move backing store address to a3, because it is
  // expected there when filling in the unmapped arguments.
  __ mov(a3, t0);
  __ bind(&skip3);

  __ Branch(&skip_parameter_map, eq, a1, Operand(Smi::FromInt(0)));

  __ LoadRoot(t2, Heap::kNonStrictArgumentsElementsMapRootIndex);
  __ sw(t2, FieldMemOperand(t0, FixedArray::kMapOffset));
  __ Addu(t2, a1, Operand(Smi::FromInt(2)));
  __ sw(t2, FieldMemOperand(t0, FixedArray::kLengthOffset));
  __ sw(cp, FieldMemOperand(t0, FixedArray::kHeaderSize + 0 * kPointerSize));
  __ sll(t6, a1, 1);
  __ Addu(t2, t0, Operand(t6));
  __ Addu(t2, t2, Operand(kParameterMapHeaderSize));
  __ sw(t2, FieldMemOperand(t0, FixedArray::kHeaderSize + 1 * kPointerSize));

  // Copy the parameter slots and the holes in the arguments.
  // We need to fill in mapped_parameter_count slots. They index the context,
  // where parameters are stored in reverse order, at
  //   MIN_CONTEXT_SLOTS .. MIN_CONTEXT_SLOTS+parameter_count-1
  // The mapped parameter thus need to get indices
  //   MIN_CONTEXT_SLOTS+parameter_count-1 ..
  //       MIN_CONTEXT_SLOTS+parameter_count-mapped_parameter_count
  // We loop from right to left.
  Label parameters_loop, parameters_test;
  __ mov(t2, a1);
  __ lw(t5, MemOperand(sp, 0 * kPointerSize));
  __ Addu(t5, t5, Operand(Smi::FromInt(Context::MIN_CONTEXT_SLOTS)));
  __ Subu(t5, t5, Operand(a1));
  __ LoadRoot(t3, Heap::kTheHoleValueRootIndex);
  __ sll(t6, t2, 1);
  __ Addu(a3, t0, Operand(t6));
  __ Addu(a3, a3, Operand(kParameterMapHeaderSize));

  // t2 = loop variable (tagged)
  // a1 = mapping index (tagged)
  // a3 = address of backing store (tagged)
  // t0 = address of parameter map (tagged)
  // t1 = temporary scratch (a.o., for address calculation)
  // t3 = the hole value
  __ jmp(&parameters_test);

  __ bind(&parameters_loop);
  __ Subu(t2, t2, Operand(Smi::FromInt(1)));
  __ sll(t1, t2, 1);
  __ Addu(t1, t1, Operand(kParameterMapHeaderSize - kHeapObjectTag));
  __ Addu(t6, t0, t1);
  __ sw(t5, MemOperand(t6));
  __ Subu(t1, t1, Operand(kParameterMapHeaderSize - FixedArray::kHeaderSize));
  __ Addu(t6, a3, t1);
  __ sw(t3, MemOperand(t6));
  __ Addu(t5, t5, Operand(Smi::FromInt(1)));
  __ bind(&parameters_test);
  __ Branch(&parameters_loop, ne, t2, Operand(Smi::FromInt(0)));

  __ bind(&skip_parameter_map);
  // a2 = argument count (tagged)
  // a3 = address of backing store (tagged)
  // t1 = scratch
  // Copy arguments header and remaining slots (if there are any).
  __ LoadRoot(t1, Heap::kFixedArrayMapRootIndex);
  __ sw(t1, FieldMemOperand(a3, FixedArray::kMapOffset));
  __ sw(a2, FieldMemOperand(a3, FixedArray::kLengthOffset));

  Label arguments_loop, arguments_test;
  __ mov(t5, a1);
  __ lw(t0, MemOperand(sp, 1 * kPointerSize));
  __ sll(t6, t5, 1);
  __ Subu(t0, t0, Operand(t6));
  __ jmp(&arguments_test);

  __ bind(&arguments_loop);
  __ Subu(t0, t0, Operand(kPointerSize));
  __ lw(t2, MemOperand(t0, 0));
  __ sll(t6, t5, 1);
  __ Addu(t1, a3, Operand(t6));
  __ sw(t2, FieldMemOperand(t1, FixedArray::kHeaderSize));
  __ Addu(t5, t5, Operand(Smi::FromInt(1)));

  __ bind(&arguments_test);
  __ Branch(&arguments_loop, lt, t5, Operand(a2));

  // Return and remove the on-stack parameters.
  __ DropAndRet(3);

  // Do the runtime call to allocate the arguments object.
  // a2 = argument count (tagged)
  __ bind(&runtime);
  __ sw(a2, MemOperand(sp, 0 * kPointerSize));  // Patch argument count.
  __ TailCallRuntime(Runtime::kNewArgumentsFast, 3, 1);
}


void ArgumentsAccessStub::GenerateNewStrict(MacroAssembler* masm) {
  // sp[0] : number of parameters
  // sp[4] : receiver displacement
  // sp[8] : function
  // Check if the calling frame is an arguments adaptor frame.
  Label adaptor_frame, try_allocate, runtime;
  __ lw(a2, MemOperand(fp, StandardFrameConstants::kCallerFPOffset));
  __ lw(a3, MemOperand(a2, StandardFrameConstants::kContextOffset));
  __ Branch(&adaptor_frame,
            eq,
            a3,
            Operand(Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR)));

  // Get the length from the frame.
  __ lw(a1, MemOperand(sp, 0));
  __ Branch(&try_allocate);

  // Patch the arguments.length and the parameters pointer.
  __ bind(&adaptor_frame);
  __ lw(a1, MemOperand(a2, ArgumentsAdaptorFrameConstants::kLengthOffset));
  __ sw(a1, MemOperand(sp, 0));
  __ sll(at, a1, kPointerSizeLog2 - kSmiTagSize);
  __ Addu(a3, a2, Operand(at));

  __ Addu(a3, a3, Operand(StandardFrameConstants::kCallerSPOffset));
  __ sw(a3, MemOperand(sp, 1 * kPointerSize));

  // Try the new space allocation. Start out with computing the size
  // of the arguments object and the elements array in words.
  Label add_arguments_object;
  __ bind(&try_allocate);
  __ Branch(&add_arguments_object, eq, a1, Operand(zero_reg));
  __ srl(a1, a1, kSmiTagSize);

  __ Addu(a1, a1, Operand(FixedArray::kHeaderSize / kPointerSize));
  __ bind(&add_arguments_object);
  __ Addu(a1, a1, Operand(Heap::kArgumentsObjectSizeStrict / kPointerSize));

  // Do the allocation of both objects in one go.
  __ AllocateInNewSpace(a1,
                        v0,
                        a2,
                        a3,
                        &runtime,
                        static_cast<AllocationFlags>(TAG_OBJECT |
                                                     SIZE_IN_WORDS));

  // Get the arguments boilerplate from the current (global) context.
  __ lw(t0, MemOperand(cp, Context::SlotOffset(Context::GLOBAL_INDEX)));
  __ lw(t0, FieldMemOperand(t0, GlobalObject::kGlobalContextOffset));
  __ lw(t0, MemOperand(t0, Context::SlotOffset(
      Context::STRICT_MODE_ARGUMENTS_BOILERPLATE_INDEX)));

  // Copy the JS object part.
  __ CopyFields(v0, t0, a3.bit(), JSObject::kHeaderSize / kPointerSize);

  // Get the length (smi tagged) and set that as an in-object property too.
  STATIC_ASSERT(Heap::kArgumentsLengthIndex == 0);
  __ lw(a1, MemOperand(sp, 0 * kPointerSize));
  __ sw(a1, FieldMemOperand(v0, JSObject::kHeaderSize +
      Heap::kArgumentsLengthIndex * kPointerSize));

  Label done;
  __ Branch(&done, eq, a1, Operand(zero_reg));

  // Get the parameters pointer from the stack.
  __ lw(a2, MemOperand(sp, 1 * kPointerSize));

  // Set up the elements pointer in the allocated arguments object and
  // initialize the header in the elements fixed array.
  __ Addu(t0, v0, Operand(Heap::kArgumentsObjectSizeStrict));
  __ sw(t0, FieldMemOperand(v0, JSObject::kElementsOffset));
  __ LoadRoot(a3, Heap::kFixedArrayMapRootIndex);
  __ sw(a3, FieldMemOperand(t0, FixedArray::kMapOffset));
  __ sw(a1, FieldMemOperand(t0, FixedArray::kLengthOffset));
  // Untag the length for the loop.
  __ srl(a1, a1, kSmiTagSize);

  // Copy the fixed array slots.
  Label loop;
  // Set up t0 to point to the first array slot.
  __ Addu(t0, t0, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
  __ bind(&loop);
  // Pre-decrement a2 with kPointerSize on each iteration.
  // Pre-decrement in order to skip receiver.
  __ Addu(a2, a2, Operand(-kPointerSize));
  __ lw(a3, MemOperand(a2));
  // Post-increment t0 with kPointerSize on each iteration.
  __ sw(a3, MemOperand(t0));
  __ Addu(t0, t0, Operand(kPointerSize));
  __ Subu(a1, a1, Operand(1));
  __ Branch(&loop, ne, a1, Operand(zero_reg));

  // Return and remove the on-stack parameters.
  __ bind(&done);
  __ DropAndRet(3);

  // Do the runtime call to allocate the arguments object.
  __ bind(&runtime);
  __ TailCallRuntime(Runtime::kNewStrictArgumentsFast, 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

  // Stack frame on entry.
  //  sp[0]: last_match_info (expected JSArray)
  //  sp[4]: previous index
  //  sp[8]: subject string
  //  sp[12]: JSRegExp object

  const int kLastMatchInfoOffset = 0 * kPointerSize;
  const int kPreviousIndexOffset = 1 * kPointerSize;
  const int kSubjectOffset = 2 * kPointerSize;
  const int kJSRegExpOffset = 3 * kPointerSize;

  Isolate* isolate = masm->isolate();

  Label runtime, invoke_regexp;

  // Allocation of registers for this function. These are in callee save
  // registers and will be preserved by the call to the native RegExp code, as
  // this code is called using the normal C calling convention. When calling
  // directly from generated code the native RegExp code will not do a GC and
  // therefore the content of these registers are safe to use after the call.
  // MIPS - using s0..s2, since we are not using CEntry Stub.
  Register subject = s0;
  Register regexp_data = s1;
  Register last_match_info_elements = s2;

  // Ensure that a RegExp stack is allocated.
  ExternalReference address_of_regexp_stack_memory_address =
      ExternalReference::address_of_regexp_stack_memory_address(
          isolate);
  ExternalReference address_of_regexp_stack_memory_size =
      ExternalReference::address_of_regexp_stack_memory_size(isolate);
  __ li(a0, Operand(address_of_regexp_stack_memory_size));
  __ lw(a0, MemOperand(a0, 0));
  __ Branch(&runtime, eq, a0, Operand(zero_reg));

  // Check that the first argument is a JSRegExp object.
  __ lw(a0, MemOperand(sp, kJSRegExpOffset));
  STATIC_ASSERT(kSmiTag == 0);
  __ JumpIfSmi(a0, &runtime);
  __ GetObjectType(a0, a1, a1);
  __ Branch(&runtime, ne, a1, Operand(JS_REGEXP_TYPE));

  // Check that the RegExp has been compiled (data contains a fixed array).
  __ lw(regexp_data, FieldMemOperand(a0, JSRegExp::kDataOffset));
  if (FLAG_debug_code) {
    __ And(t0, regexp_data, Operand(kSmiTagMask));
    __ Check(nz,
             "Unexpected type for RegExp data, FixedArray expected",
             t0,
             Operand(zero_reg));
    __ GetObjectType(regexp_data, a0, a0);
    __ Check(eq,
             "Unexpected type for RegExp data, FixedArray expected",
             a0,
             Operand(FIXED_ARRAY_TYPE));
  }

  // regexp_data: RegExp data (FixedArray)
  // Check the type of the RegExp. Only continue if type is JSRegExp::IRREGEXP.
  __ lw(a0, FieldMemOperand(regexp_data, JSRegExp::kDataTagOffset));
  __ Branch(&runtime, ne, a0, Operand(Smi::FromInt(JSRegExp::IRREGEXP)));

  // regexp_data: RegExp data (FixedArray)
  // Check that the number of captures fit in the static offsets vector buffer.
  __ lw(a2,
         FieldMemOperand(regexp_data, JSRegExp::kIrregexpCaptureCountOffset));
  // Calculate number of capture registers (number_of_captures + 1) * 2. This
  // uses the asumption that smis are 2 * their untagged value.
  STATIC_ASSERT(kSmiTag == 0);
  STATIC_ASSERT(kSmiTagSize + kSmiShiftSize == 1);
  __ Addu(a2, a2, Operand(2));  // a2 was a smi.
  // Check that the static offsets vector buffer is large enough.
  __ Branch(&runtime, hi, a2, Operand(OffsetsVector::kStaticOffsetsVectorSize));

  // a2: Number of capture registers
  // regexp_data: RegExp data (FixedArray)
  // Check that the second argument is a string.
  __ lw(subject, MemOperand(sp, kSubjectOffset));
  __ JumpIfSmi(subject, &runtime);
  __ GetObjectType(subject, a0, a0);
  __ And(a0, a0, Operand(kIsNotStringMask));
  STATIC_ASSERT(kStringTag == 0);
  __ Branch(&runtime, ne, a0, Operand(zero_reg));

  // Get the length of the string to r3.
  __ lw(a3, FieldMemOperand(subject, String::kLengthOffset));

  // a2: Number of capture registers
  // a3: Length of subject string as a smi
  // subject: Subject string
  // regexp_data: RegExp data (FixedArray)
  // Check that the third argument is a positive smi less than the subject
  // string length. A negative value will be greater (unsigned comparison).
  __ lw(a0, MemOperand(sp, kPreviousIndexOffset));
  __ JumpIfNotSmi(a0, &runtime);
  __ Branch(&runtime, ls, a3, Operand(a0));

  // a2: Number of capture registers
  // subject: Subject string
  // regexp_data: RegExp data (FixedArray)
  // Check that the fourth object is a JSArray object.
  __ lw(a0, MemOperand(sp, kLastMatchInfoOffset));
  __ JumpIfSmi(a0, &runtime);
  __ GetObjectType(a0, a1, a1);
  __ Branch(&runtime, ne, a1, Operand(JS_ARRAY_TYPE));
  // Check that the JSArray is in fast case.
  __ lw(last_match_info_elements,
         FieldMemOperand(a0, JSArray::kElementsOffset));
  __ lw(a0, FieldMemOperand(last_match_info_elements, HeapObject::kMapOffset));
  __ Branch(&runtime, ne, a0, Operand(
      isolate->factory()->fixed_array_map()));
  // Check that the last match info has space for the capture registers and the
  // additional information.
  __ lw(a0,
         FieldMemOperand(last_match_info_elements, FixedArray::kLengthOffset));
  __ Addu(a2, a2, Operand(RegExpImpl::kLastMatchOverhead));
  __ sra(at, a0, kSmiTagSize);  // Untag length for comparison.
  __ Branch(&runtime, gt, a2, Operand(at));

  // Reset offset for possibly sliced string.
  __ mov(t0, zero_reg);
  // subject: Subject string
  // regexp_data: RegExp data (FixedArray)
  // Check the representation and encoding of the subject string.
  Label seq_string;
  __ lw(a0, FieldMemOperand(subject, HeapObject::kMapOffset));
  __ lbu(a0, FieldMemOperand(a0, Map::kInstanceTypeOffset));
  // First check for flat string.  None of the following string type tests will
  // succeed if subject is not a string or a short external string.
  __ And(a1,
         a0,
         Operand(kIsNotStringMask |
                 kStringRepresentationMask |
                 kShortExternalStringMask));
  STATIC_ASSERT((kStringTag | kSeqStringTag) == 0);
  __ Branch(&seq_string, eq, a1, Operand(zero_reg));

  // subject: Subject string
  // a0: instance type if Subject string
  // regexp_data: RegExp data (FixedArray)
  // a1: whether subject is a string and if yes, its string representation
  // Check for flat cons string or sliced 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.
  // In the case of a sliced string its offset has to be taken into account.
  Label cons_string, external_string, check_encoding;
  STATIC_ASSERT(kConsStringTag < kExternalStringTag);
  STATIC_ASSERT(kSlicedStringTag > kExternalStringTag);
  STATIC_ASSERT(kIsNotStringMask > kExternalStringTag);
  STATIC_ASSERT(kShortExternalStringTag > kExternalStringTag);
  __ Branch(&cons_string, lt, a1, Operand(kExternalStringTag));
  __ Branch(&external_string, eq, a1, Operand(kExternalStringTag));

  // Catch non-string subject or short external string.
  STATIC_ASSERT(kNotStringTag != 0 && kShortExternalStringTag !=0);
  __ And(at, a1, Operand(kIsNotStringMask | kShortExternalStringMask));
  __ Branch(&runtime, ne, at, Operand(zero_reg));

  // String is sliced.
  __ lw(t0, FieldMemOperand(subject, SlicedString::kOffsetOffset));
  __ sra(t0, t0, kSmiTagSize);
  __ lw(subject, FieldMemOperand(subject, SlicedString::kParentOffset));
  // t5: offset of sliced string, smi-tagged.
  __ jmp(&check_encoding);
  // String is a cons string, check whether it is flat.
  __ bind(&cons_string);
  __ lw(a0, FieldMemOperand(subject, ConsString::kSecondOffset));
  __ LoadRoot(a1, Heap::kEmptyStringRootIndex);
  __ Branch(&runtime, ne, a0, Operand(a1));
  __ lw(subject, FieldMemOperand(subject, ConsString::kFirstOffset));
  // Is first part of cons or parent of slice a flat string?
  __ bind(&check_encoding);
  __ lw(a0, FieldMemOperand(subject, HeapObject::kMapOffset));
  __ lbu(a0, FieldMemOperand(a0, Map::kInstanceTypeOffset));
  STATIC_ASSERT(kSeqStringTag == 0);
  __ And(at, a0, Operand(kStringRepresentationMask));
  __ Branch(&external_string, ne, at, Operand(zero_reg));

  __ bind(&seq_string);
  // subject: Subject string
  // regexp_data: RegExp data (FixedArray)
  // a0: Instance type of subject string
  STATIC_ASSERT(kStringEncodingMask == 4);
  STATIC_ASSERT(kAsciiStringTag == 4);
  STATIC_ASSERT(kTwoByteStringTag == 0);
  // Find the code object based on the assumptions above.
  __ And(a0, a0, Operand(kStringEncodingMask));  // Non-zero for ASCII.
  __ lw(t9, FieldMemOperand(regexp_data, JSRegExp::kDataAsciiCodeOffset));
  __ sra(a3, a0, 2);  // a3 is 1 for ASCII, 0 for UC16 (used below).
  __ lw(t1, FieldMemOperand(regexp_data, JSRegExp::kDataUC16CodeOffset));
  __ Movz(t9, t1, a0);  // If UC16 (a0 is 0), replace t9 w/kDataUC16CodeOffset.

  // Check that the irregexp code has been generated for the actual string
  // encoding. If it has, the field contains a code object otherwise it contains
  // a smi (code flushing support).
  __ JumpIfSmi(t9, &runtime);

  // a3: encoding of subject string (1 if ASCII, 0 if two_byte);
  // t9: code
  // subject: Subject string
  // regexp_data: RegExp data (FixedArray)
  // Load used arguments before starting to push arguments for call to native
  // RegExp code to avoid handling changing stack height.
  __ lw(a1, MemOperand(sp, kPreviousIndexOffset));
  __ sra(a1, a1, kSmiTagSize);  // Untag the Smi.

  // a1: previous index
  // a3: encoding of subject string (1 if ASCII, 0 if two_byte);
  // t9: code
  // subject: Subject string
  // regexp_data: RegExp data (FixedArray)
  // All checks done. Now push arguments for native regexp code.
  __ IncrementCounter(isolate->counters()->regexp_entry_native(),
                      1, a0, a2);

  // Isolates: note we add an additional parameter here (isolate pointer).
  const int kRegExpExecuteArguments = 9;
  const int kParameterRegisters = 4;
  __ EnterExitFrame(false, kRegExpExecuteArguments - kParameterRegisters);

  // Stack pointer now points to cell where return address is to be written.
  // Arguments are before that on the stack or in registers, meaning we
  // treat the return address as argument 5. Thus every argument after that
  // needs to be shifted back by 1. Since DirectCEntryStub will handle
  // allocating space for the c argument slots, we don't need to calculate
  // that into the argument positions on the stack. This is how the stack will
  // look (sp meaning the value of sp at this moment):
  // [sp + 5] - Argument 9
  // [sp + 4] - Argument 8
  // [sp + 3] - Argument 7
  // [sp + 2] - Argument 6
  // [sp + 1] - Argument 5
  // [sp + 0] - saved ra

  // Argument 9: Pass current isolate address.
  // CFunctionArgumentOperand handles MIPS stack argument slots.
  __ li(a0, Operand(ExternalReference::isolate_address()));
  __ sw(a0, MemOperand(sp, 5 * kPointerSize));

  // Argument 8: Indicate that this is a direct call from JavaScript.
  __ li(a0, Operand(1));
  __ sw(a0, MemOperand(sp, 4 * kPointerSize));

  // Argument 7: Start (high end) of backtracking stack memory area.
  __ li(a0, Operand(address_of_regexp_stack_memory_address));
  __ lw(a0, MemOperand(a0, 0));
  __ li(a2, Operand(address_of_regexp_stack_memory_size));
  __ lw(a2, MemOperand(a2, 0));
  __ addu(a0, a0, a2);
  __ sw(a0, MemOperand(sp, 3 * kPointerSize));

  // Argument 6: Set the number of capture registers to zero to force global
  // regexps to behave as non-global.  This does not affect non-global regexps.
  __ mov(a0, zero_reg);
  __ sw(a0, MemOperand(sp, 2 * kPointerSize));

  // Argument 5: static offsets vector buffer.
  __ li(a0, Operand(
        ExternalReference::address_of_static_offsets_vector(isolate)));
  __ sw(a0, MemOperand(sp, 1 * kPointerSize));

  // For arguments 4 and 3 get string length, calculate start of string data
  // and calculate the shift of the index (0 for ASCII and 1 for two byte).
  __ Addu(t2, subject, Operand(SeqString::kHeaderSize - kHeapObjectTag));
  __ Xor(a3, a3, Operand(1));  // 1 for 2-byte str, 0 for 1-byte.
  // Load the length from the original subject string from the previous stack
  // frame. Therefore we have to use fp, which points exactly to two pointer
  // sizes below the previous sp. (Because creating a new stack frame pushes
  // the previous fp onto the stack and moves up sp by 2 * kPointerSize.)
  __ lw(subject, MemOperand(fp, kSubjectOffset + 2 * kPointerSize));
  // If slice offset is not 0, load the length from the original sliced string.
  // Argument 4, a3: End of string data
  // Argument 3, a2: Start of string data
  // Prepare start and end index of the input.
  __ sllv(t1, t0, a3);
  __ addu(t0, t2, t1);
  __ sllv(t1, a1, a3);
  __ addu(a2, t0, t1);

  __ lw(t2, FieldMemOperand(subject, String::kLengthOffset));
  __ sra(t2, t2, kSmiTagSize);
  __ sllv(t1, t2, a3);
  __ addu(a3, t0, t1);
  // Argument 2 (a1): Previous index.
  // Already there

  // Argument 1 (a0): Subject string.
  __ mov(a0, subject);

  // Locate the code entry and call it.
  __ Addu(t9, t9, Operand(Code::kHeaderSize - kHeapObjectTag));
  DirectCEntryStub stub;
  stub.GenerateCall(masm, t9);

  __ LeaveExitFrame(false, no_reg);

  // v0: result
  // subject: subject string (callee saved)
  // regexp_data: RegExp data (callee saved)
  // last_match_info_elements: Last match info elements (callee saved)

  // Check the result.

  Label success;
  __ Branch(&success, eq, v0, Operand(1));
  // We expect exactly one result since we force the called regexp to behave
  // as non-global.
  Label failure;
  __ Branch(&failure, eq, v0, Operand(NativeRegExpMacroAssembler::FAILURE));
  // If not exception it can only be retry. Handle that in the runtime system.
  __ Branch(&runtime, ne, v0, Operand(NativeRegExpMacroAssembler::EXCEPTION));
  // 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.
  __ li(a1, Operand(isolate->factory()->the_hole_value()));
  __ li(a2, Operand(ExternalReference(Isolate::kPendingExceptionAddress,
                                      isolate)));
  __ lw(v0, MemOperand(a2, 0));
  __ Branch(&runtime, eq, v0, Operand(a1));

  __ sw(a1, MemOperand(a2, 0));  // Clear pending exception.

  // Check if the exception is a termination. If so, throw as uncatchable.
  __ LoadRoot(a0, Heap::kTerminationExceptionRootIndex);
  Label termination_exception;
  __ Branch(&termination_exception, eq, v0, Operand(a0));

  __ Throw(v0);

  __ bind(&termination_exception);
  __ ThrowUncatchable(v0);

  __ bind(&failure);
  // For failure and exception return null.
  __ li(v0, Operand(isolate->factory()->null_value()));
  __ DropAndRet(4);

  // Process the result from the native regexp code.
  __ bind(&success);
  __ lw(a1,
         FieldMemOperand(regexp_data, JSRegExp::kIrregexpCaptureCountOffset));
  // Calculate number of capture registers (number_of_captures + 1) * 2.
  STATIC_ASSERT(kSmiTag == 0);
  STATIC_ASSERT(kSmiTagSize + kSmiShiftSize == 1);
  __ Addu(a1, a1, Operand(2));  // a1 was a smi.

  // a1: number of capture registers
  // subject: subject string
  // Store the capture count.
  __ sll(a2, a1, kSmiTagSize + kSmiShiftSize);  // To smi.
  __ sw(a2, FieldMemOperand(last_match_info_elements,
                             RegExpImpl::kLastCaptureCountOffset));
  // Store last subject and last input.
  __ sw(subject,
         FieldMemOperand(last_match_info_elements,
                         RegExpImpl::kLastSubjectOffset));
  __ mov(a2, subject);
  __ RecordWriteField(last_match_info_elements,
                      RegExpImpl::kLastSubjectOffset,
                      a2,
                      t3,
                      kRAHasNotBeenSaved,
                      kDontSaveFPRegs);
  __ sw(subject,
         FieldMemOperand(last_match_info_elements,
                         RegExpImpl::kLastInputOffset));
  __ RecordWriteField(last_match_info_elements,
                      RegExpImpl::kLastInputOffset,
                      subject,
                      t3,
                      kRAHasNotBeenSaved,
                      kDontSaveFPRegs);

  // Get the static offsets vector filled by the native regexp code.
  ExternalReference address_of_static_offsets_vector =
      ExternalReference::address_of_static_offsets_vector(isolate);
  __ li(a2, Operand(address_of_static_offsets_vector));

  // a1: number of capture registers
  // a2: offsets vector
  Label next_capture, done;
  // Capture register counter starts from number of capture registers and
  // counts down until wrapping after zero.
  __ Addu(a0,
         last_match_info_elements,
         Operand(RegExpImpl::kFirstCaptureOffset - kHeapObjectTag));
  __ bind(&next_capture);
  __ Subu(a1, a1, Operand(1));
  __ Branch(&done, lt, a1, Operand(zero_reg));
  // Read the value from the static offsets vector buffer.
  __ lw(a3, MemOperand(a2, 0));
  __ addiu(a2, a2, kPointerSize);
  // Store the smi value in the last match info.
  __ sll(a3, a3, kSmiTagSize);  // Convert to Smi.
  __ sw(a3, MemOperand(a0, 0));
  __ Branch(&next_capture, USE_DELAY_SLOT);
  __ addiu(a0, a0, kPointerSize);  // In branch delay slot.

  __ bind(&done);

  // Return last match info.
  __ lw(v0, MemOperand(sp, kLastMatchInfoOffset));
  __ DropAndRet(4);

  // External string.  Short external strings have already been ruled out.
  // a0: scratch
  __ bind(&external_string);
  __ lw(a0, FieldMemOperand(subject, HeapObject::kMapOffset));
  __ lbu(a0, FieldMemOperand(a0, Map::kInstanceTypeOffset));
  if (FLAG_debug_code) {
    // Assert that we do not have a cons or slice (indirect strings) here.
    // Sequential strings have already been ruled out.
    __ And(at, a0, Operand(kIsIndirectStringMask));
    __ Assert(eq,
              "external string expected, but not found",
              at,
              Operand(zero_reg));
  }
  __ lw(subject,
        FieldMemOperand(subject, ExternalString::kResourceDataOffset));
  // Move the pointer so that offset-wise, it looks like a sequential string.
  STATIC_ASSERT(SeqTwoByteString::kHeaderSize == SeqAsciiString::kHeaderSize);
  __ Subu(subject,
          subject,
          SeqTwoByteString::kHeaderSize - kHeapObjectTag);
  __ jmp(&seq_string);

  // Do the runtime call to execute the regexp.
  __ bind(&runtime);
  __ TailCallRuntime(Runtime::kRegExpExec, 4, 1);
#endif  // V8_INTERPRETED_REGEXP
}


void RegExpConstructResultStub::Generate(MacroAssembler* masm) {
  const int kMaxInlineLength = 100;
  Label slowcase;
  Label done;
  __ lw(a1, MemOperand(sp, kPointerSize * 2));
  STATIC_ASSERT(kSmiTag == 0);
  STATIC_ASSERT(kSmiTagSize == 1);
  __ JumpIfNotSmi(a1, &slowcase);
  __ Branch(&slowcase, hi, a1, Operand(Smi::FromInt(kMaxInlineLength)));
  // Smi-tagging is equivalent to multiplying by 2.
  // Allocate RegExpResult followed by FixedArray with size in ebx.
  // JSArray:   [Map][empty properties][Elements][Length-smi][index][input]
  // Elements:  [Map][Length][..elements..]
  // Size of JSArray with two in-object properties and the header of a
  // FixedArray.
  int objects_size =
      (JSRegExpResult::kSize + FixedArray::kHeaderSize) / kPointerSize;
  __ srl(t1, a1, kSmiTagSize + kSmiShiftSize);
  __ Addu(a2, t1, Operand(objects_size));
  __ AllocateInNewSpace(
      a2,  // In: Size, in words.
      v0,  // Out: Start of allocation (tagged).
      a3,  // Scratch register.
      t0,  // Scratch register.
      &slowcase,
      static_cast<AllocationFlags>(TAG_OBJECT | SIZE_IN_WORDS));
  // v0: Start of allocated area, object-tagged.
  // a1: Number of elements in array, as smi.
  // t1: Number of elements, untagged.

  // Set JSArray map to global.regexp_result_map().
  // Set empty properties FixedArray.
  // Set elements to point to FixedArray allocated right after the JSArray.
  // Interleave operations for better latency.
  __ lw(a2, ContextOperand(cp, Context::GLOBAL_INDEX));
  __ Addu(a3, v0, Operand(JSRegExpResult::kSize));
  __ li(t0, Operand(masm->isolate()->factory()->empty_fixed_array()));
  __ lw(a2, FieldMemOperand(a2, GlobalObject::kGlobalContextOffset));
  __ sw(a3, FieldMemOperand(v0, JSObject::kElementsOffset));
  __ lw(a2, ContextOperand(a2, Context::REGEXP_RESULT_MAP_INDEX));
  __ sw(t0, FieldMemOperand(v0, JSObject::kPropertiesOffset));
  __ sw(a2, FieldMemOperand(v0, HeapObject::kMapOffset));

  // Set input, index and length fields from arguments.
  __ lw(a1, MemOperand(sp, kPointerSize * 0));
  __ lw(a2, MemOperand(sp, kPointerSize * 1));
  __ lw(t2, MemOperand(sp, kPointerSize * 2));
  __ sw(a1, FieldMemOperand(v0, JSRegExpResult::kInputOffset));
  __ sw(a2, FieldMemOperand(v0, JSRegExpResult::kIndexOffset));
  __ sw(t2, FieldMemOperand(v0, JSArray::kLengthOffset));

  // Fill out the elements FixedArray.
  // v0: JSArray, tagged.
  // a3: FixedArray, tagged.
  // t1: Number of elements in array, untagged.

  // Set map.
  __ li(a2, Operand(masm->isolate()->factory()->fixed_array_map()));
  __ sw(a2, FieldMemOperand(a3, HeapObject::kMapOffset));
  // Set FixedArray length.
  __ sll(t2, t1, kSmiTagSize);
  __ sw(t2, FieldMemOperand(a3, FixedArray::kLengthOffset));
  // Fill contents of fixed-array with the-hole.
  __ li(a2, Operand(masm->isolate()->factory()->the_hole_value()));
  __ Addu(a3, a3, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
  // Fill fixed array elements with hole.
  // v0: JSArray, tagged.
  // a2: the hole.
  // a3: Start of elements in FixedArray.
  // t1: Number of elements to fill.
  Label loop;
  __ sll(t1, t1, kPointerSizeLog2);  // Convert num elements to num bytes.
  __ addu(t1, t1, a3);  // Point past last element to store.
  __ bind(&loop);
  __ Branch(&done, ge, a3, Operand(t1));  // Break when a3 past end of elem.
  __ sw(a2, MemOperand(a3));
  __ Branch(&loop, USE_DELAY_SLOT);
  __ addiu(a3, a3, kPointerSize);  // In branch delay slot.

  __ bind(&done);
  __ DropAndRet(3);

  __ bind(&slowcase);
  __ TailCallRuntime(Runtime::kRegExpConstructResult, 3, 1);
}


static void GenerateRecordCallTarget(MacroAssembler* masm) {
  // Cache the called function in a global property cell.  Cache states
  // are uninitialized, monomorphic (indicated by a JSFunction), and
  // megamorphic.
  // a1 : the function to call
  // a2 : cache cell for call target
  Label done;

  ASSERT_EQ(*TypeFeedbackCells::MegamorphicSentinel(masm->isolate()),
            masm->isolate()->heap()->undefined_value());
  ASSERT_EQ(*TypeFeedbackCells::UninitializedSentinel(masm->isolate()),
            masm->isolate()->heap()->the_hole_value());

  // Load the cache state into a3.
  __ lw(a3, FieldMemOperand(a2, JSGlobalPropertyCell::kValueOffset));

  // A monomorphic cache hit or an already megamorphic state: invoke the
  // function without changing the state.
  __ Branch(&done, eq, a3, Operand(a1));
  __ LoadRoot(at, Heap::kUndefinedValueRootIndex);
  __ Branch(&done, eq, a3, Operand(at));

  // A monomorphic miss (i.e, here the cache is not uninitialized) goes
  // megamorphic.
  __ LoadRoot(at, Heap::kTheHoleValueRootIndex);

  __ Branch(USE_DELAY_SLOT, &done, eq, a3, Operand(at));
  // An uninitialized cache is patched with the function.
  // Store a1 in the delay slot. This may or may not get overwritten depending
  // on the result of the comparison.
  __ sw(a1, FieldMemOperand(a2, JSGlobalPropertyCell::kValueOffset));
  // No need for a write barrier here - cells are rescanned.

  // MegamorphicSentinel is an immortal immovable object (undefined) so no
  // write-barrier is needed.
  __ LoadRoot(at, Heap::kUndefinedValueRootIndex);
  __ sw(at, FieldMemOperand(a2, JSGlobalPropertyCell::kValueOffset));

  __ bind(&done);
}


void CallFunctionStub::Generate(MacroAssembler* masm) {
  // a1 : the function to call
  // a2 : cache cell for call target
  Label slow, non_function;

  // The receiver might implicitly be the global object. This is
  // indicated by passing the hole as the receiver to the call
  // function stub.
  if (ReceiverMightBeImplicit()) {
    Label call;
    // Get the receiver from the stack.
    // function, receiver [, arguments]
    __ lw(t0, MemOperand(sp, argc_ * kPointerSize));
    // Call as function is indicated with the hole.
    __ LoadRoot(at, Heap::kTheHoleValueRootIndex);
    __ Branch(&call, ne, t0, Operand(at));
    // Patch the receiver on the stack with the global receiver object.
    __ lw(a3, MemOperand(cp, Context::SlotOffset(Context::GLOBAL_INDEX)));
    __ lw(a3, FieldMemOperand(a3, GlobalObject::kGlobalReceiverOffset));
    __ sw(a3, MemOperand(sp, argc_ * kPointerSize));
    __ bind(&call);
  }

  // Check that the function is really a JavaScript function.
  // a1: pushed function (to be verified)
  __ JumpIfSmi(a1, &non_function);
  // Get the map of the function object.
  __ GetObjectType(a1, a3, a3);
  __ Branch(&slow, ne, a3, Operand(JS_FUNCTION_TYPE));

  if (RecordCallTarget()) {
    GenerateRecordCallTarget(masm);
  }

  // Fast-case: Invoke the function now.
  // a1: pushed function
  ParameterCount actual(argc_);

  if (ReceiverMightBeImplicit()) {
    Label call_as_function;
    __ LoadRoot(at, Heap::kTheHoleValueRootIndex);
    __ Branch(&call_as_function, eq, t0, Operand(at));
    __ InvokeFunction(a1,
                      actual,
                      JUMP_FUNCTION,
                      NullCallWrapper(),
                      CALL_AS_METHOD);
    __ bind(&call_as_function);
  }
  __ InvokeFunction(a1,
                    actual,
                    JUMP_FUNCTION,
                    NullCallWrapper(),
                    CALL_AS_FUNCTION);

  // Slow-case: Non-function called.
  __ bind(&slow);
  if (RecordCallTarget()) {
    // If there is a call target cache, mark it megamorphic in the
    // non-function case.  MegamorphicSentinel is an immortal immovable
    // object (undefined) so no write barrier is needed.
    ASSERT_EQ(*TypeFeedbackCells::MegamorphicSentinel(masm->isolate()),
              masm->isolate()->heap()->undefined_value());
    __ LoadRoot(at, Heap::kUndefinedValueRootIndex);
    __ sw(at, FieldMemOperand(a2, JSGlobalPropertyCell::kValueOffset));
  }
  // Check for function proxy.
  __ Branch(&non_function, ne, a3, Operand(JS_FUNCTION_PROXY_TYPE));
  __ push(a1);  // Put proxy as additional argument.
  __ li(a0, Operand(argc_ + 1, RelocInfo::NONE));
  __ li(a2, Operand(0, RelocInfo::NONE));
  __ GetBuiltinEntry(a3, Builtins::CALL_FUNCTION_PROXY);
  __ SetCallKind(t1, CALL_AS_METHOD);
  {
    Handle<Code> adaptor =
      masm->isolate()->builtins()->ArgumentsAdaptorTrampoline();
    __ Jump(adaptor, RelocInfo::CODE_TARGET);
  }

  // CALL_NON_FUNCTION expects the non-function callee as receiver (instead
  // of the original receiver from the call site).
  __ bind(&non_function);
  __ sw(a1, MemOperand(sp, argc_ * kPointerSize));
  __ li(a0, Operand(argc_));  // Set up the number of arguments.
  __ mov(a2, zero_reg);
  __ GetBuiltinEntry(a3, Builtins::CALL_NON_FUNCTION);
  __ SetCallKind(t1, CALL_AS_METHOD);
  __ Jump(masm->isolate()->builtins()->ArgumentsAdaptorTrampoline(),
          RelocInfo::CODE_TARGET);
}


void CallConstructStub::Generate(MacroAssembler* masm) {
  // a0 : number of arguments
  // a1 : the function to call
  // a2 : cache cell for call target
  Label slow, non_function_call;

  // Check that the function is not a smi.
  __ JumpIfSmi(a1, &non_function_call);
  // Check that the function is a JSFunction.
  __ GetObjectType(a1, a3, a3);
  __ Branch(&slow, ne, a3, Operand(JS_FUNCTION_TYPE));

  if (RecordCallTarget()) {
    GenerateRecordCallTarget(masm);
  }

  // Jump to the function-specific construct stub.
  __ lw(a2, FieldMemOperand(a1, JSFunction::kSharedFunctionInfoOffset));
  __ lw(a2, FieldMemOperand(a2, SharedFunctionInfo::kConstructStubOffset));
  __ Addu(at, a2, Operand(Code::kHeaderSize - kHeapObjectTag));
  __ Jump(at);

  // a0: number of arguments
  // a1: called object
  // a3: object type
  Label do_call;
  __ bind(&slow);
  __ Branch(&non_function_call, ne, a3, Operand(JS_FUNCTION_PROXY_TYPE));
  __ GetBuiltinEntry(a3, Builtins::CALL_FUNCTION_PROXY_AS_CONSTRUCTOR);
  __ jmp(&do_call);

  __ bind(&non_function_call);
  __ GetBuiltinEntry(a3, Builtins::CALL_NON_FUNCTION_AS_CONSTRUCTOR);
  __ bind(&do_call);
  // Set expected number of arguments to zero (not changing r0).
  __ li(a2, Operand(0, RelocInfo::NONE));
  __ SetCallKind(t1, CALL_AS_METHOD);
  __ Jump(masm->isolate()->builtins()->ArgumentsAdaptorTrampoline(),
          RelocInfo::CODE_TARGET);
}


// Unfortunately you have to run without snapshots to see most of these
// names in the profile since most compare stubs end up in the snapshot.
void CompareStub::PrintName(StringStream* stream) {
  ASSERT((lhs_.is(a0) && rhs_.is(a1)) ||
         (lhs_.is(a1) && rhs_.is(a0)));
  const char* cc_name;
  switch (cc_) {
    case lt: cc_name = "LT"; break;
    case gt: cc_name = "GT"; break;
    case le: cc_name = "LE"; break;
    case ge: cc_name = "GE"; break;
    case eq: cc_name = "EQ"; break;
    case ne: cc_name = "NE"; break;
    default: cc_name = "UnknownCondition"; break;
  }
  bool is_equality = cc_ == eq || cc_ == ne;
  stream->Add("CompareStub_%s", cc_name);
  stream->Add(lhs_.is(a0) ? "_a0" : "_a1");
  stream->Add(rhs_.is(a0) ? "_a0" : "_a1");
  if (strict_ && is_equality) stream->Add("_STRICT");
  if (never_nan_nan_ && is_equality) stream->Add("_NO_NAN");
  if (!include_number_compare_) stream->Add("_NO_NUMBER");
  if (!include_smi_compare_) stream->Add("_NO_SMI");
}


int CompareStub::MinorKey() {
  // Encode the two parameters in a unique 16 bit value.
  ASSERT(static_cast<unsigned>(cc_) < (1 << 14));
  ASSERT((lhs_.is(a0) && rhs_.is(a1)) ||
         (lhs_.is(a1) && rhs_.is(a0)));
  return ConditionField::encode(static_cast<unsigned>(cc_))
         | RegisterField::encode(lhs_.is(a0))
         | StrictField::encode(strict_)
         | NeverNanNanField::encode(cc_ == eq ? never_nan_nan_ : false)
         | IncludeSmiCompareField::encode(include_smi_compare_);
}


// StringCharCodeAtGenerator.
void StringCharCodeAtGenerator::GenerateFast(MacroAssembler* masm) {
  Label flat_string;
  Label ascii_string;
  Label got_char_code;
  Label sliced_string;

  ASSERT(!t0.is(index_));
  ASSERT(!t0.is(result_));
  ASSERT(!t0.is(object_));

  // If the receiver is a smi trigger the non-string case.
  __ JumpIfSmi(object_, receiver_not_string_);

  // Fetch the instance type of the receiver into result register.
  __ lw(result_, FieldMemOperand(object_, HeapObject::kMapOffset));
  __ lbu(result_, FieldMemOperand(result_, Map::kInstanceTypeOffset));
  // If the receiver is not a string trigger the non-string case.
  __ And(t0, result_, Operand(kIsNotStringMask));
  __ Branch(receiver_not_string_, ne, t0, Operand(zero_reg));

  // If the index is non-smi trigger the non-smi case.
  __ JumpIfNotSmi(index_, &index_not_smi_);

  __ bind(&got_smi_index_);

  // Check for index out of range.
  __ lw(t0, FieldMemOperand(object_, String::kLengthOffset));
  __ Branch(index_out_of_range_, ls, t0, Operand(index_));

  __ sra(index_, index_, kSmiTagSize);

  StringCharLoadGenerator::Generate(masm,
                                    object_,
                                    index_,
                                    result_,
                                    &call_runtime_);

  __ sll(result_, result_, kSmiTagSize);
  __ bind(&exit_);
}


void StringCharCodeAtGenerator::GenerateSlow(
    MacroAssembler* masm,
    const RuntimeCallHelper& call_helper) {
  __ Abort("Unexpected fallthrough to CharCodeAt slow case");

  // Index is not a smi.
  __ bind(&index_not_smi_);
  // If index is a heap number, try converting it to an integer.
  __ CheckMap(index_,
              result_,
              Heap::kHeapNumberMapRootIndex,
              index_not_number_,
              DONT_DO_SMI_CHECK);
  call_helper.BeforeCall(masm);
  // Consumed by runtime conversion function:
  __ Push(object_, index_);
  if (index_flags_ == STRING_INDEX_IS_NUMBER) {
    __ CallRuntime(Runtime::kNumberToIntegerMapMinusZero, 1);
  } else {
    ASSERT(index_flags_ == STRING_INDEX_IS_ARRAY_INDEX);
    // NumberToSmi discards numbers that are not exact integers.
    __ CallRuntime(Runtime::kNumberToSmi, 1);
  }

  // Save the conversion result before the pop instructions below
  // have a chance to overwrite it.

  __ Move(index_, v0);
  __ pop(object_);
  // Reload the instance type.
  __ lw(result_, FieldMemOperand(object_, HeapObject::kMapOffset));
  __ lbu(result_, FieldMemOperand(result_, Map::kInstanceTypeOffset));
  call_helper.AfterCall(masm);
  // If index is still not a smi, it must be out of range.
  __ JumpIfNotSmi(index_, index_out_of_range_);
  // Otherwise, return to the fast path.
  __ Branch(&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);
  __ sll(index_, index_, kSmiTagSize);
  __ Push(object_, index_);
  __ CallRuntime(Runtime::kStringCharCodeAt, 2);

  __ Move(result_, v0);

  call_helper.AfterCall(masm);
  __ jmp(&exit_);

  __ Abort("Unexpected fallthrough from CharCodeAt slow case");
}


// -------------------------------------------------------------------------
// StringCharFromCodeGenerator

void StringCharFromCodeGenerator::GenerateFast(MacroAssembler* masm) {
  // Fast case of Heap::LookupSingleCharacterStringFromCode.

  ASSERT(!t0.is(result_));
  ASSERT(!t0.is(code_));

  STATIC_ASSERT(kSmiTag == 0);
  STATIC_ASSERT(kSmiShiftSize == 0);
  ASSERT(IsPowerOf2(String::kMaxAsciiCharCode + 1));
  __ And(t0,
         code_,
         Operand(kSmiTagMask |
                 ((~String::kMaxAsciiCharCode) << kSmiTagSize)));
  __ Branch(&slow_case_, ne, t0, Operand(zero_reg));

  __ LoadRoot(result_, Heap::kSingleCharacterStringCacheRootIndex);
  // At this point code register contains smi tagged ASCII char code.
  STATIC_ASSERT(kSmiTag == 0);
  __ sll(t0, code_, kPointerSizeLog2 - kSmiTagSize);
  __ Addu(result_, result_, t0);
  __ lw(result_, FieldMemOperand(result_, FixedArray::kHeaderSize));
  __ LoadRoot(t0, Heap::kUndefinedValueRootIndex);
  __ Branch(&slow_case_, eq, result_, Operand(t0));
  __ bind(&exit_);
}


void StringCharFromCodeGenerator::GenerateSlow(
    MacroAssembler* masm,
    const RuntimeCallHelper& call_helper) {
  __ Abort("Unexpected fallthrough to CharFromCode slow case");

  __ bind(&slow_case_);
  call_helper.BeforeCall(masm);
  __ push(code_);
  __ CallRuntime(Runtime::kCharFromCode, 1);
  __ Move(result_, v0);

  call_helper.AfterCall(masm);
  __ Branch(&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 StringHelper::GenerateCopyCharacters(MacroAssembler* masm,
                                          Register dest,
                                          Register src,
                                          Register count,
                                          Register scratch,
                                          bool ascii) {
  Label loop;
  Label done;
  // This loop just copies one character at a time, as it is only used for
  // very short strings.
  if (!ascii) {
    __ addu(count, count, count);
  }
  __ Branch(&done, eq, count, Operand(zero_reg));
  __ addu(count, dest, count);  // Count now points to the last dest byte.

  __ bind(&loop);
  __ lbu(scratch, MemOperand(src));
  __ addiu(src, src, 1);
  __ sb(scratch, MemOperand(dest));
  __ addiu(dest, dest, 1);
  __ Branch(&loop, lt, dest, Operand(count));

  __ bind(&done);
}


enum CopyCharactersFlags {
  COPY_ASCII = 1,
  DEST_ALWAYS_ALIGNED = 2
};


void StringHelper::GenerateCopyCharactersLong(MacroAssembler* masm,
                                              Register dest,
                                              Register src,
                                              Register count,
                                              Register scratch1,
                                              Register scratch2,
                                              Register scratch3,
                                              Register scratch4,
                                              Register scratch5,
                                              int flags) {
  bool ascii = (flags & COPY_ASCII) != 0;
  bool dest_always_aligned = (flags & DEST_ALWAYS_ALIGNED) != 0;

  if (dest_always_aligned && FLAG_debug_code) {
    // Check that destination is actually word aligned if the flag says
    // that it is.
    __ And(scratch4, dest, Operand(kPointerAlignmentMask));
    __ Check(eq,
             "Destination of copy not aligned.",
             scratch4,
             Operand(zero_reg));
  }

  const int kReadAlignment = 4;
  const int kReadAlignmentMask = kReadAlignment - 1;
  // Ensure that reading an entire aligned word containing the last character
  // of a string will not read outside the allocated area (because we pad up
  // to kObjectAlignment).
  STATIC_ASSERT(kObjectAlignment >= kReadAlignment);
  // Assumes word reads and writes are little endian.
  // Nothing to do for zero characters.
  Label done;

  if (!ascii) {
    __ addu(count, count, count);
  }
  __ Branch(&done, eq, count, Operand(zero_reg));

  Label byte_loop;
  // Must copy at least eight bytes, otherwise just do it one byte at a time.
  __ Subu(scratch1, count, Operand(8));
  __ Addu(count, dest, Operand(count));
  Register limit = count;  // Read until src equals this.
  __ Branch(&byte_loop, lt, scratch1, Operand(zero_reg));

  if (!dest_always_aligned) {
    // Align dest by byte copying. Copies between zero and three bytes.
    __ And(scratch4, dest, Operand(kReadAlignmentMask));
    Label dest_aligned;
    __ Branch(&dest_aligned, eq, scratch4, Operand(zero_reg));
    Label aligned_loop;
    __ bind(&aligned_loop);
    __ lbu(scratch1, MemOperand(src));
    __ addiu(src, src, 1);
    __ sb(scratch1, MemOperand(dest));
    __ addiu(dest, dest, 1);
    __ addiu(scratch4, scratch4, 1);
    __ Branch(&aligned_loop, le, scratch4, Operand(kReadAlignmentMask));
    __ bind(&dest_aligned);
  }

  Label simple_loop;

  __ And(scratch4, src, Operand(kReadAlignmentMask));
  __ Branch(&simple_loop, eq, scratch4, Operand(zero_reg));

  // Loop for src/dst that are not aligned the same way.
  // This loop uses lwl and lwr instructions. These instructions
  // depend on the endianness, and the implementation assumes little-endian.
  {
    Label loop;
    __ bind(&loop);
    __ lwr(scratch1, MemOperand(src));
    __ Addu(src, src, Operand(kReadAlignment));
    __ lwl(scratch1, MemOperand(src, -1));
    __ sw(scratch1, MemOperand(dest));
    __ Addu(dest, dest, Operand(kReadAlignment));
    __ Subu(scratch2, limit, dest);
    __ Branch(&loop, ge, scratch2, Operand(kReadAlignment));
  }

  __ Branch(&byte_loop);

  // Simple loop.
  // Copy words from src to dest, until less than four bytes left.
  // Both src and dest are word aligned.
  __ bind(&simple_loop);
  {
    Label loop;
    __ bind(&loop);
    __ lw(scratch1, MemOperand(src));
    __ Addu(src, src, Operand(kReadAlignment));
    __ sw(scratch1, MemOperand(dest));
    __ Addu(dest, dest, Operand(kReadAlignment));
    __ Subu(scratch2, limit, dest);
    __ Branch(&loop, ge, scratch2, Operand(kReadAlignment));
  }

  // Copy bytes from src to dest until dest hits limit.
  __ bind(&byte_loop);
  // Test if dest has already reached the limit.
  __ Branch(&done, ge, dest, Operand(limit));
  __ lbu(scratch1, MemOperand(src));
  __ addiu(src, src, 1);
  __ sb(scratch1, MemOperand(dest));
  __ addiu(dest, dest, 1);
  __ Branch(&byte_loop);

  __ bind(&done);
}


void StringHelper::GenerateTwoCharacterSymbolTableProbe(MacroAssembler* masm,
                                                        Register c1,
                                                        Register c2,
                                                        Register scratch1,
                                                        Register scratch2,
                                                        Register scratch3,
                                                        Register scratch4,
                                                        Register scratch5,
                                                        Label* not_found) {
  // Register scratch3 is the general scratch register in this function.
  Register scratch = scratch3;

  // Make sure that both characters are not digits as such strings has a
  // different hash algorithm. Don't try to look for these in the symbol table.
  Label not_array_index;
  __ Subu(scratch, c1, Operand(static_cast<int>('0')));
  __ Branch(&not_array_index,
            Ugreater,
            scratch,
            Operand(static_cast<int>('9' - '0')));
  __ Subu(scratch, c2, Operand(static_cast<int>('0')));

  // If check failed combine both characters into single halfword.
  // This is required by the contract of the method: code at the
  // not_found branch expects this combination in c1 register.
  Label tmp;
  __ sll(scratch1, c2, kBitsPerByte);
  __ Branch(&tmp, Ugreater, scratch, Operand(static_cast<int>('9' - '0')));
  __ Or(c1, c1, scratch1);
  __ bind(&tmp);
  __ Branch(
      not_found, Uless_equal, scratch, Operand(static_cast<int>('9' - '0')));

  __ bind(&not_array_index);
  // Calculate the two character string hash.
  Register hash = scratch1;
  StringHelper::GenerateHashInit(masm, hash, c1);
  StringHelper::GenerateHashAddCharacter(masm, hash, c2);
  StringHelper::GenerateHashGetHash(masm, hash);

  // Collect the two characters in a register.
  Register chars = c1;
  __ sll(scratch, c2, kBitsPerByte);
  __ Or(chars, chars, scratch);

  // chars: two character string, char 1 in byte 0 and char 2 in byte 1.
  // hash:  hash of two character string.

  // Load symbol table.
  // Load address of first element of the symbol table.
  Register symbol_table = c2;
  __ LoadRoot(symbol_table, Heap::kSymbolTableRootIndex);

  Register undefined = scratch4;
  __ LoadRoot(undefined, Heap::kUndefinedValueRootIndex);

  // Calculate capacity mask from the symbol table capacity.
  Register mask = scratch2;
  __ lw(mask, FieldMemOperand(symbol_table, SymbolTable::kCapacityOffset));
  __ sra(mask, mask, 1);
  __ Addu(mask, mask, -1);

  // Calculate untagged address of the first element of the symbol table.
  Register first_symbol_table_element = symbol_table;
  __ Addu(first_symbol_table_element, symbol_table,
         Operand(SymbolTable::kElementsStartOffset - kHeapObjectTag));

  // Registers.
  // chars: two character string, char 1 in byte 0 and char 2 in byte 1.
  // hash:  hash of two character string
  // mask:  capacity mask
  // first_symbol_table_element: address of the first element of
  //                             the symbol table
  // undefined: the undefined object
  // scratch: -

  // Perform a number of probes in the symbol table.
  const int kProbes = 4;
  Label found_in_symbol_table;
  Label next_probe[kProbes];
  Register candidate = scratch5;  // Scratch register contains candidate.
  for (int i = 0; i < kProbes; i++) {
    // Calculate entry in symbol table.
    if (i > 0) {
      __ Addu(candidate, hash, Operand(SymbolTable::GetProbeOffset(i)));
    } else {
      __ mov(candidate, hash);
    }

    __ And(candidate, candidate, Operand(mask));

    // Load the entry from the symble table.
    STATIC_ASSERT(SymbolTable::kEntrySize == 1);
    __ sll(scratch, candidate, kPointerSizeLog2);
    __ Addu(scratch, scratch, first_symbol_table_element);
    __ lw(candidate, MemOperand(scratch));

    // If entry is undefined no string with this hash can be found.
    Label is_string;
    __ GetObjectType(candidate, scratch, scratch);
    __ Branch(&is_string, ne, scratch, Operand(ODDBALL_TYPE));

    __ Branch(not_found, eq, undefined, Operand(candidate));
    // Must be the hole (deleted entry).
    if (FLAG_debug_code) {
      __ LoadRoot(scratch, Heap::kTheHoleValueRootIndex);
      __ Assert(eq, "oddball in symbol table is not undefined or the hole",
          scratch, Operand(candidate));
    }
    __ jmp(&next_probe[i]);

    __ bind(&is_string);

    // Check that the candidate is a non-external ASCII string.  The instance
    // type is still in the scratch register from the CompareObjectType
    // operation.
    __ JumpIfInstanceTypeIsNotSequentialAscii(scratch, scratch, &next_probe[i]);

    // If length is not 2 the string is not a candidate.
    __ lw(scratch, FieldMemOperand(candidate, String::kLengthOffset));
    __ Branch(&next_probe[i], ne, scratch, Operand(Smi::FromInt(2)));

    // Check if the two characters match.
    // Assumes that word load is little endian.
    __ lhu(scratch, FieldMemOperand(candidate, SeqAsciiString::kHeaderSize));
    __ Branch(&found_in_symbol_table, eq, chars, Operand(scratch));
    __ 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 = candidate;
  __ bind(&found_in_symbol_table);
  __ mov(v0, result);
}


void StringHelper::GenerateHashInit(MacroAssembler* masm,
                                    Register hash,
                                    Register character) {
  // hash = seed + character + ((seed + character) << 10);
  __ LoadRoot(hash, Heap::kHashSeedRootIndex);
  // Untag smi seed and add the character.
  __ SmiUntag(hash);
  __ addu(hash, hash, character);
  __ sll(at, hash, 10);
  __ addu(hash, hash, at);
  // hash ^= hash >> 6;
  __ srl(at, hash, 6);
  __ xor_(hash, hash, at);
}


void StringHelper::GenerateHashAddCharacter(MacroAssembler* masm,
                                            Register hash,
                                            Register character) {
  // hash += character;
  __ addu(hash, hash, character);
  // hash += hash << 10;
  __ sll(at, hash, 10);
  __ addu(hash, hash, at);
  // hash ^= hash >> 6;
  __ srl(at, hash, 6);
  __ xor_(hash, hash, at);
}


void StringHelper::GenerateHashGetHash(MacroAssembler* masm,
                                       Register hash) {
  // hash += hash << 3;
  __ sll(at, hash, 3);
  __ addu(hash, hash, at);
  // hash ^= hash >> 11;
  __ srl(at, hash, 11);
  __ xor_(hash, hash, at);
  // hash += hash << 15;
  __ sll(at, hash, 15);
  __ addu(hash, hash, at);

  __ li(at, Operand(String::kHashBitMask));
  __ and_(hash, hash, at);

  // if (hash == 0) hash = 27;
  __ ori(at, zero_reg, StringHasher::kZeroHash);
  __ Movz(hash, at, hash);
}


void SubStringStub::Generate(MacroAssembler* masm) {
  Label runtime;
  // Stack frame on entry.
  //  ra: return address
  //  sp[0]: to
  //  sp[4]: from
  //  sp[8]: string

  // This stub is called from the native-call %_SubString(...), so
  // nothing can be assumed about the arguments. It is tested that:
  //  "string" is a sequential string,
  //  both "from" and "to" are smis, and
  //  0 <= from <= to <= string.length.
  // If any of these assumptions fail, we call the runtime system.

  const int kToOffset = 0 * kPointerSize;
  const int kFromOffset = 1 * kPointerSize;
  const int kStringOffset = 2 * kPointerSize;

  __ lw(a2, MemOperand(sp, kToOffset));
  __ lw(a3, MemOperand(sp, kFromOffset));
  STATIC_ASSERT(kFromOffset == kToOffset + 4);
  STATIC_ASSERT(kSmiTag == 0);
  STATIC_ASSERT(kSmiTagSize + kSmiShiftSize == 1);

  // Utilize delay slots. SmiUntag doesn't emit a jump, everything else is
  // safe in this case.
  __ UntagAndJumpIfNotSmi(a2, a2, &runtime);
  __ UntagAndJumpIfNotSmi(a3, a3, &runtime);
  // Both a2 and a3 are untagged integers.

  __ Branch(&runtime, lt, a3, Operand(zero_reg));  // From < 0.

  __ Branch(&runtime, gt, a3, Operand(a2));  // Fail if from > to.
  __ Subu(a2, a2, a3);

  // Make sure first argument is a string.
  __ lw(v0, MemOperand(sp, kStringOffset));
  __ JumpIfSmi(v0, &runtime);
  __ lw(a1, FieldMemOperand(v0, HeapObject::kMapOffset));
  __ lbu(a1, FieldMemOperand(a1, Map::kInstanceTypeOffset));
  __ And(t0, a1, Operand(kIsNotStringMask));

  __ Branch(&runtime, ne, t0, Operand(zero_reg));

  // Short-cut for the case of trivial substring.
  Label return_v0;
  // v0: original string
  // a2: result string length
  __ lw(t0, FieldMemOperand(v0, String::kLengthOffset));
  __ sra(t0, t0, 1);
  // Return original string.
  __ Branch(&return_v0, eq, a2, Operand(t0));
  // Longer than original string's length or negative: unsafe arguments.
  __ Branch(&runtime, hi, a2, Operand(t0));
  // Shorter than original string's length: an actual substring.

  // Deal with different string types: update the index if necessary
  // and put the underlying string into t1.
  // v0: original string
  // a1: instance type
  // a2: length
  // a3: from index (untagged)
  Label underlying_unpacked, sliced_string, seq_or_external_string;
  // If the string is not indirect, it can only be sequential or external.
  STATIC_ASSERT(kIsIndirectStringMask == (kSlicedStringTag & kConsStringTag));
  STATIC_ASSERT(kIsIndirectStringMask != 0);
  __ And(t0, a1, Operand(kIsIndirectStringMask));
  __ Branch(USE_DELAY_SLOT, &seq_or_external_string, eq, t0, Operand(zero_reg));
  // t0 is used as a scratch register and can be overwritten in either case.
  __ And(t0, a1, Operand(kSlicedNotConsMask));
  __ Branch(&sliced_string, ne, t0, Operand(zero_reg));
  // Cons string.  Check whether it is flat, then fetch first part.
  __ lw(t1, FieldMemOperand(v0, ConsString::kSecondOffset));
  __ LoadRoot(t0, Heap::kEmptyStringRootIndex);
  __ Branch(&runtime, ne, t1, Operand(t0));
  __ lw(t1, FieldMemOperand(v0, ConsString::kFirstOffset));
  // Update instance type.
  __ lw(a1, FieldMemOperand(t1, HeapObject::kMapOffset));
  __ lbu(a1, FieldMemOperand(a1, Map::kInstanceTypeOffset));
  __ jmp(&underlying_unpacked);

  __ bind(&sliced_string);
  // Sliced string.  Fetch parent and correct start index by offset.
  __ lw(t1, FieldMemOperand(v0, SlicedString::kParentOffset));
  __ lw(t0, FieldMemOperand(v0, SlicedString::kOffsetOffset));
  __ sra(t0, t0, 1);  // Add offset to index.
  __ Addu(a3, a3, t0);
  // Update instance type.
  __ lw(a1, FieldMemOperand(t1, HeapObject::kMapOffset));
  __ lbu(a1, FieldMemOperand(a1, Map::kInstanceTypeOffset));
  __ jmp(&underlying_unpacked);

  __ bind(&seq_or_external_string);
  // Sequential or external string.  Just move string to the expected register.
  __ mov(t1, v0);

  __ bind(&underlying_unpacked);

  if (FLAG_string_slices) {
    Label copy_routine;
    // t1: underlying subject string
    // a1: instance type of underlying subject string
    // a2: length
    // a3: adjusted start index (untagged)
    // Short slice.  Copy instead of slicing.
    __ Branch(&copy_routine, lt, a2, Operand(SlicedString::kMinLength));
    // Allocate new sliced string.  At this point we do not reload the instance
    // type including the string encoding because we simply rely on the info
    // provided by the original string.  It does not matter if the original
    // string's encoding is wrong because we always have to recheck encoding of
    // the newly created string's parent anyways due to externalized strings.
    Label two_byte_slice, set_slice_header;
    STATIC_ASSERT((kStringEncodingMask & kAsciiStringTag) != 0);
    STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
    __ And(t0, a1, Operand(kStringEncodingMask));
    __ Branch(&two_byte_slice, eq, t0, Operand(zero_reg));
    __ AllocateAsciiSlicedString(v0, a2, t2, t3, &runtime);
    __ jmp(&set_slice_header);
    __ bind(&two_byte_slice);
    __ AllocateTwoByteSlicedString(v0, a2, t2, t3, &runtime);
    __ bind(&set_slice_header);
    __ sll(a3, a3, 1);
    __ sw(t1, FieldMemOperand(v0, SlicedString::kParentOffset));
    __ sw(a3, FieldMemOperand(v0, SlicedString::kOffsetOffset));
    __ jmp(&return_v0);

    __ bind(&copy_routine);
  }

  // t1: underlying subject string
  // a1: instance type of underlying subject string
  // a2: length
  // a3: adjusted start index (untagged)
  Label two_byte_sequential, sequential_string, allocate_result;
  STATIC_ASSERT(kExternalStringTag != 0);
  STATIC_ASSERT(kSeqStringTag == 0);
  __ And(t0, a1, Operand(kExternalStringTag));
  __ Branch(&sequential_string, eq, t0, Operand(zero_reg));

  // Handle external string.
  // Rule out short external strings.
  STATIC_CHECK(kShortExternalStringTag != 0);
  __ And(t0, a1, Operand(kShortExternalStringTag));
  __ Branch(&runtime, ne, t0, Operand(zero_reg));
  __ lw(t1, FieldMemOperand(t1, ExternalString::kResourceDataOffset));
  // t1 already points to the first character of underlying string.
  __ jmp(&allocate_result);

  __ bind(&sequential_string);
  // Locate first character of underlying subject string.
  STATIC_ASSERT(SeqTwoByteString::kHeaderSize == SeqAsciiString::kHeaderSize);
  __ Addu(t1, t1, Operand(SeqAsciiString::kHeaderSize - kHeapObjectTag));

  __ bind(&allocate_result);
  // Sequential acii string.  Allocate the result.
  STATIC_ASSERT((kAsciiStringTag & kStringEncodingMask) != 0);
  __ And(t0, a1, Operand(kStringEncodingMask));
  __ Branch(&two_byte_sequential, eq, t0, Operand(zero_reg));

  // Allocate and copy the resulting ASCII string.
  __ AllocateAsciiString(v0, a2, t0, t2, t3, &runtime);

  // Locate first character of substring to copy.
  __ Addu(t1, t1, a3);

  // Locate first character of result.
  __ Addu(a1, v0, Operand(SeqAsciiString::kHeaderSize - kHeapObjectTag));

  // v0: result string
  // a1: first character of result string
  // a2: result string length
  // t1: first character of substring to copy
  STATIC_ASSERT((SeqAsciiString::kHeaderSize & kObjectAlignmentMask) == 0);
  StringHelper::GenerateCopyCharactersLong(
      masm, a1, t1, a2, a3, t0, t2, t3, t4, COPY_ASCII | DEST_ALWAYS_ALIGNED);
  __ jmp(&return_v0);

  // Allocate and copy the resulting two-byte string.
  __ bind(&two_byte_sequential);
  __ AllocateTwoByteString(v0, a2, t0, t2, t3, &runtime);

  // Locate first character of substring to copy.
  STATIC_ASSERT(kSmiTagSize == 1 && kSmiTag == 0);
  __ sll(t0, a3, 1);
  __ Addu(t1, t1, t0);
  // Locate first character of result.
  __ Addu(a1, v0, Operand(SeqTwoByteString::kHeaderSize - kHeapObjectTag));

  // v0: result string.
  // a1: first character of result.
  // a2: result length.
  // t1: first character of substring to copy.
  STATIC_ASSERT((SeqTwoByteString::kHeaderSize & kObjectAlignmentMask) == 0);
  StringHelper::GenerateCopyCharactersLong(
      masm, a1, t1, a2, a3, t0, t2, t3, t4, DEST_ALWAYS_ALIGNED);

  __ bind(&return_v0);
  Counters* counters = masm->isolate()->counters();
  __ IncrementCounter(counters->sub_string_native(), 1, a3, t0);
  __ DropAndRet(3);

  // Just jump to runtime to create the sub string.
  __ bind(&runtime);
  __ TailCallRuntime(Runtime::kSubString, 3, 1);
}


void StringCompareStub::GenerateFlatAsciiStringEquals(MacroAssembler* masm,
                                                      Register left,
                                                      Register right,
                                                      Register scratch1,
                                                      Register scratch2,
                                                      Register scratch3) {
  Register length = scratch1;

  // Compare lengths.
  Label strings_not_equal, check_zero_length;
  __ lw(length, FieldMemOperand(left, String::kLengthOffset));
  __ lw(scratch2, FieldMemOperand(right, String::kLengthOffset));
  __ Branch(&check_zero_length, eq, length, Operand(scratch2));
  __ bind(&strings_not_equal);
  __ li(v0, Operand(Smi::FromInt(NOT_EQUAL)));
  __ Ret();

  // Check if the length is zero.
  Label compare_chars;
  __ bind(&check_zero_length);
  STATIC_ASSERT(kSmiTag == 0);
  __ Branch(&compare_chars, ne, length, Operand(zero_reg));
  __ li(v0, Operand(Smi::FromInt(EQUAL)));
  __ Ret();

  // Compare characters.
  __ bind(&compare_chars);

  GenerateAsciiCharsCompareLoop(masm,
                                left, right, length, scratch2, scratch3, v0,
                                &strings_not_equal);

  // Characters are equal.
  __ li(v0, Operand(Smi::FromInt(EQUAL)));
  __ Ret();
}


void StringCompareStub::GenerateCompareFlatAsciiStrings(MacroAssembler* masm,
                                                        Register left,
                                                        Register right,
                                                        Register scratch1,
                                                        Register scratch2,
                                                        Register scratch3,
                                                        Register scratch4) {
  Label result_not_equal, compare_lengths;
  // Find minimum length and length difference.
  __ lw(scratch1, FieldMemOperand(left, String::kLengthOffset));
  __ lw(scratch2, FieldMemOperand(right, String::kLengthOffset));
  __ Subu(scratch3, scratch1, Operand(scratch2));
  Register length_delta = scratch3;
  __ slt(scratch4, scratch2, scratch1);
  __ Movn(scratch1, scratch2, scratch4);
  Register min_length = scratch1;
  STATIC_ASSERT(kSmiTag == 0);
  __ Branch(&compare_lengths, eq, min_length, Operand(zero_reg));

  // Compare loop.
  GenerateAsciiCharsCompareLoop(masm,
                                left, right, min_length, scratch2, scratch4, v0,
                                &result_not_equal);

  // Compare lengths - strings up to min-length are equal.
  __ bind(&compare_lengths);
  ASSERT(Smi::FromInt(EQUAL) == static_cast<Smi*>(0));
  // Use length_delta as result if it's zero.
  __ mov(scratch2, length_delta);
  __ mov(scratch4, zero_reg);
  __ mov(v0, zero_reg);

  __ bind(&result_not_equal);
  // Conditionally update the result based either on length_delta or
  // the last comparion performed in the loop above.
  Label ret;
  __ Branch(&ret, eq, scratch2, Operand(scratch4));
  __ li(v0, Operand(Smi::FromInt(GREATER)));
  __ Branch(&ret, gt, scratch2, Operand(scratch4));
  __ li(v0, Operand(Smi::FromInt(LESS)));
  __ bind(&ret);
  __ Ret();
}


void StringCompareStub::GenerateAsciiCharsCompareLoop(
    MacroAssembler* masm,
    Register left,
    Register right,
    Register length,
    Register scratch1,
    Register scratch2,
    Register scratch3,
    Label* chars_not_equal) {
  // Change index to run from -length to -1 by adding length to string
  // start. This means that loop ends when index reaches zero, which
  // doesn't need an additional compare.
  __ SmiUntag(length);
  __ Addu(scratch1, length,
          Operand(SeqAsciiString::kHeaderSize - kHeapObjectTag));
  __ Addu(left, left, Operand(scratch1));
  __ Addu(right, right, Operand(scratch1));
  __ Subu(length, zero_reg, length);
  Register index = length;  // index = -length;


  // Compare loop.
  Label loop;
  __ bind(&loop);
  __ Addu(scratch3, left, index);
  __ lbu(scratch1, MemOperand(scratch3));
  __ Addu(scratch3, right, index);
  __ lbu(scratch2, MemOperand(scratch3));
  __ Branch(chars_not_equal, ne, scratch1, Operand(scratch2));
  __ Addu(index, index, 1);
  __ Branch(&loop, ne, index, Operand(zero_reg));
}


void StringCompareStub::Generate(MacroAssembler* masm) {
  Label runtime;

  Counters* counters = masm->isolate()->counters();

  // Stack frame on entry.
  //  sp[0]: right string
  //  sp[4]: left string
  __ lw(a1, MemOperand(sp, 1 * kPointerSize));  // Left.
  __ lw(a0, MemOperand(sp, 0 * kPointerSize));  // Right.

  Label not_same;
  __ Branch(&not_same, ne, a0, Operand(a1));
  STATIC_ASSERT(EQUAL == 0);
  STATIC_ASSERT(kSmiTag == 0);
  __ li(v0, Operand(Smi::FromInt(EQUAL)));
  __ IncrementCounter(counters->string_compare_native(), 1, a1, a2);
  __ DropAndRet(2);

  __ bind(&not_same);

  // Check that both objects are sequential ASCII strings.
  __ JumpIfNotBothSequentialAsciiStrings(a1, a0, a2, a3, &runtime);

  // Compare flat ASCII strings natively. Remove arguments from stack first.
  __ IncrementCounter(counters->string_compare_native(), 1, a2, a3);
  __ Addu(sp, sp, Operand(2 * kPointerSize));
  GenerateCompareFlatAsciiStrings(masm, a1, a0, a2, a3, t0, t1);

  __ bind(&runtime);
  __ TailCallRuntime(Runtime::kStringCompare, 2, 1);
}


void StringAddStub::Generate(MacroAssembler* masm) {
  Label call_runtime, call_builtin;
  Builtins::JavaScript builtin_id = Builtins::ADD;

  Counters* counters = masm->isolate()->counters();

  // Stack on entry:
  // sp[0]: second argument (right).
  // sp[4]: first argument (left).

  // Load the two arguments.
  __ lw(a0, MemOperand(sp, 1 * kPointerSize));  // First argument.
  __ lw(a1, MemOperand(sp, 0 * kPointerSize));  // Second argument.

  // Make sure that both arguments are strings if not known in advance.
  if (flags_ == NO_STRING_ADD_FLAGS) {
    __ JumpIfEitherSmi(a0, a1, &call_runtime);
    // Load instance types.
    __ lw(t0, FieldMemOperand(a0, HeapObject::kMapOffset));
    __ lw(t1, FieldMemOperand(a1, HeapObject::kMapOffset));
    __ lbu(t0, FieldMemOperand(t0, Map::kInstanceTypeOffset));
    __ lbu(t1, FieldMemOperand(t1, Map::kInstanceTypeOffset));
    STATIC_ASSERT(kStringTag == 0);
    // If either is not a string, go to runtime.
    __ Or(t4, t0, Operand(t1));
    __ And(t4, t4, Operand(kIsNotStringMask));
    __ Branch(&call_runtime, ne, t4, Operand(zero_reg));
  } else {
    // Here at least one of the arguments is definitely a string.
    // We convert the one that is not known to be a string.
    if ((flags_ & NO_STRING_CHECK_LEFT_IN_STUB) == 0) {
      ASSERT((flags_ & NO_STRING_CHECK_RIGHT_IN_STUB) != 0);
      GenerateConvertArgument(
          masm, 1 * kPointerSize, a0, a2, a3, t0, t1, &call_builtin);
      builtin_id = Builtins::STRING_ADD_RIGHT;
    } else if ((flags_ & NO_STRING_CHECK_RIGHT_IN_STUB) == 0) {
      ASSERT((flags_ & NO_STRING_CHECK_LEFT_IN_STUB) != 0);
      GenerateConvertArgument(
          masm, 0 * kPointerSize, a1, a2, a3, t0, t1, &call_builtin);
      builtin_id = Builtins::STRING_ADD_LEFT;
    }
  }

  // Both arguments are strings.
  // a0: first string
  // a1: second string
  // t0: first string instance type (if flags_ == NO_STRING_ADD_FLAGS)
  // t1: second string instance type (if flags_ == NO_STRING_ADD_FLAGS)
  {
    Label strings_not_empty;
    // Check if either of the strings are empty. In that case return the other.
    // These tests use zero-length check on string-length whch is an Smi.
    // Assert that Smi::FromInt(0) is really 0.
    STATIC_ASSERT(kSmiTag == 0);
    ASSERT(Smi::FromInt(0) == 0);
    __ lw(a2, FieldMemOperand(a0, String::kLengthOffset));
    __ lw(a3, FieldMemOperand(a1, String::kLengthOffset));
    __ mov(v0, a0);       // Assume we'll return first string (from a0).
    __ Movz(v0, a1, a2);  // If first is empty, return second (from a1).
    __ slt(t4, zero_reg, a2);   // if (a2 > 0) t4 = 1.
    __ slt(t5, zero_reg, a3);   // if (a3 > 0) t5 = 1.
    __ and_(t4, t4, t5);        // Branch if both strings were non-empty.
    __ Branch(&strings_not_empty, ne, t4, Operand(zero_reg));

    __ IncrementCounter(counters->string_add_native(), 1, a2, a3);
    __ DropAndRet(2);

    __ bind(&strings_not_empty);
  }

  // Untag both string-lengths.
  __ sra(a2, a2, kSmiTagSize);
  __ sra(a3, a3, kSmiTagSize);

  // Both strings are non-empty.
  // a0: first string
  // a1: second string
  // a2: length of first string
  // a3: length of second string
  // t0: first string instance type (if flags_ == NO_STRING_ADD_FLAGS)
  // t1: second string instance type (if flags_ == NO_STRING_ADD_FLAGS)
  // Look at the length of the result of adding the two strings.
  Label string_add_flat_result, longer_than_two;
  // Adding two lengths can't overflow.
  STATIC_ASSERT(String::kMaxLength < String::kMaxLength * 2);
  __ Addu(t2, a2, Operand(a3));
  // Use the symbol table when adding two one character strings, as it
  // helps later optimizations to return a symbol here.
  __ Branch(&longer_than_two, ne, t2, Operand(2));

  // Check that both strings are non-external ASCII strings.
  if (flags_ != NO_STRING_ADD_FLAGS) {
    __ lw(t0, FieldMemOperand(a0, HeapObject::kMapOffset));
    __ lw(t1, FieldMemOperand(a1, HeapObject::kMapOffset));
    __ lbu(t0, FieldMemOperand(t0, Map::kInstanceTypeOffset));
    __ lbu(t1, FieldMemOperand(t1, Map::kInstanceTypeOffset));
  }
  __ JumpIfBothInstanceTypesAreNotSequentialAscii(t0, t1, t2, t3,
                                                 &call_runtime);

  // Get the two characters forming the sub string.
  __ lbu(a2, FieldMemOperand(a0, SeqAsciiString::kHeaderSize));
  __ lbu(a3, FieldMemOperand(a1, SeqAsciiString::kHeaderSize));

  // Try to lookup two character string in symbol table. If it is not found
  // just allocate a new one.
  Label make_two_character_string;
  StringHelper::GenerateTwoCharacterSymbolTableProbe(
      masm, a2, a3, t2, t3, t0, t1, t5, &make_two_character_string);
  __ IncrementCounter(counters->string_add_native(), 1, a2, a3);
  __ DropAndRet(2);

  __ bind(&make_two_character_string);
  // Resulting string has length 2 and first chars of two strings
  // are combined into single halfword in a2 register.
  // So we can fill resulting string without two loops by a single
  // halfword store instruction (which assumes that processor is
  // in a little endian mode).
  __ li(t2, Operand(2));
  __ AllocateAsciiString(v0, t2, t0, t1, t5, &call_runtime);
  __ sh(a2, FieldMemOperand(v0, SeqAsciiString::kHeaderSize));
  __ IncrementCounter(counters->string_add_native(), 1, a2, a3);
  __ DropAndRet(2);

  __ bind(&longer_than_two);
  // Check if resulting string will be flat.
  __ Branch(&string_add_flat_result, lt, t2, Operand(ConsString::kMinLength));
  // Handle exceptionally long strings in the runtime system.
  STATIC_ASSERT((String::kMaxLength & 0x80000000) == 0);
  ASSERT(IsPowerOf2(String::kMaxLength + 1));
  // kMaxLength + 1 is representable as shifted literal, kMaxLength is not.
  __ Branch(&call_runtime, hs, t2, Operand(String::kMaxLength + 1));

  // If result is not supposed to be flat, allocate a cons string object.
  // If both strings are ASCII the result is an ASCII cons string.
  if (flags_ != NO_STRING_ADD_FLAGS) {
    __ lw(t0, FieldMemOperand(a0, HeapObject::kMapOffset));
    __ lw(t1, FieldMemOperand(a1, HeapObject::kMapOffset));
    __ lbu(t0, FieldMemOperand(t0, Map::kInstanceTypeOffset));
    __ lbu(t1, FieldMemOperand(t1, Map::kInstanceTypeOffset));
  }
  Label non_ascii, allocated, ascii_data;
  STATIC_ASSERT(kTwoByteStringTag == 0);
  // Branch to non_ascii if either string-encoding field is zero (non-ASCII).
  __ And(t4, t0, Operand(t1));
  __ And(t4, t4, Operand(kStringEncodingMask));
  __ Branch(&non_ascii, eq, t4, Operand(zero_reg));

  // Allocate an ASCII cons string.
  __ bind(&ascii_data);
  __ AllocateAsciiConsString(v0, t2, t0, t1, &call_runtime);
  __ bind(&allocated);
  // Fill the fields of the cons string.
  __ sw(a0, FieldMemOperand(v0, ConsString::kFirstOffset));
  __ sw(a1, FieldMemOperand(v0, ConsString::kSecondOffset));
  __ IncrementCounter(counters->string_add_native(), 1, a2, a3);
  __ DropAndRet(2);

  __ bind(&non_ascii);
  // At least one of the strings is two-byte. Check whether it happens
  // to contain only ASCII characters.
  // t0: first instance type.
  // t1: second instance type.
  // Branch to if _both_ instances have kAsciiDataHintMask set.
  __ And(at, t0, Operand(kAsciiDataHintMask));
  __ and_(at, at, t1);
  __ Branch(&ascii_data, ne, at, Operand(zero_reg));

  __ xor_(t0, t0, t1);
  STATIC_ASSERT(kAsciiStringTag != 0 && kAsciiDataHintTag != 0);
  __ And(t0, t0, Operand(kAsciiStringTag | kAsciiDataHintTag));
  __ Branch(&ascii_data, eq, t0, Operand(kAsciiStringTag | kAsciiDataHintTag));

  // Allocate a two byte cons string.
  __ AllocateTwoByteConsString(v0, t2, t0, t1, &call_runtime);
  __ Branch(&allocated);

  // We cannot encounter sliced strings or cons strings here since:
  STATIC_ASSERT(SlicedString::kMinLength >= ConsString::kMinLength);
  // Handle creating a flat result from either external or sequential strings.
  // Locate the first characters' locations.
  // a0: first string
  // a1: second string
  // a2: length of first string
  // a3: length of second string
  // t0: first string instance type (if flags_ == NO_STRING_ADD_FLAGS)
  // t1: second string instance type (if flags_ == NO_STRING_ADD_FLAGS)
  // t2: sum of lengths.
  Label first_prepared, second_prepared;
  __ bind(&string_add_flat_result);
  if (flags_ != NO_STRING_ADD_FLAGS) {
    __ lw(t0, FieldMemOperand(a0, HeapObject::kMapOffset));
    __ lw(t1, FieldMemOperand(a1, HeapObject::kMapOffset));
    __ lbu(t0, FieldMemOperand(t0, Map::kInstanceTypeOffset));
    __ lbu(t1, FieldMemOperand(t1, Map::kInstanceTypeOffset));
  }
  // Check whether both strings have same encoding
  __ Xor(t3, t0, Operand(t1));
  __ And(t3, t3, Operand(kStringEncodingMask));
  __ Branch(&call_runtime, ne, t3, Operand(zero_reg));

  STATIC_ASSERT(kSeqStringTag == 0);
  __ And(t4, t0, Operand(kStringRepresentationMask));

  STATIC_ASSERT(SeqAsciiString::kHeaderSize == SeqTwoByteString::kHeaderSize);
  Label skip_first_add;
  __ Branch(&skip_first_add, ne, t4, Operand(zero_reg));
  __ Branch(USE_DELAY_SLOT, &first_prepared);
  __ addiu(t3, a0, SeqAsciiString::kHeaderSize - kHeapObjectTag);
  __ bind(&skip_first_add);
  // External string: rule out short external string and load string resource.
  STATIC_ASSERT(kShortExternalStringTag != 0);
  __ And(t4, t0, Operand(kShortExternalStringMask));
  __ Branch(&call_runtime, ne, t4, Operand(zero_reg));
  __ lw(t3, FieldMemOperand(a0, ExternalString::kResourceDataOffset));
  __ bind(&first_prepared);

  STATIC_ASSERT(kSeqStringTag == 0);
  __ And(t4, t1, Operand(kStringRepresentationMask));
  STATIC_ASSERT(SeqAsciiString::kHeaderSize == SeqTwoByteString::kHeaderSize);
  Label skip_second_add;
  __ Branch(&skip_second_add, ne, t4, Operand(zero_reg));
  __ Branch(USE_DELAY_SLOT, &second_prepared);
  __ addiu(a1, a1, SeqAsciiString::kHeaderSize - kHeapObjectTag);
  __ bind(&skip_second_add);
  // External string: rule out short external string and load string resource.
  STATIC_ASSERT(kShortExternalStringTag != 0);
  __ And(t4, t1, Operand(kShortExternalStringMask));
  __ Branch(&call_runtime, ne, t4, Operand(zero_reg));
  __ lw(a1, FieldMemOperand(a1, ExternalString::kResourceDataOffset));
  __ bind(&second_prepared);

  Label non_ascii_string_add_flat_result;
  // t3: first character of first string
  // a1: first character of second string
  // a2: length of first string
  // a3: length of second string
  // t2: sum of lengths.
  // Both strings have the same encoding.
  STATIC_ASSERT(kTwoByteStringTag == 0);
  __ And(t4, t1, Operand(kStringEncodingMask));
  __ Branch(&non_ascii_string_add_flat_result, eq, t4, Operand(zero_reg));

  __ AllocateAsciiString(v0, t2, t0, t1, t5, &call_runtime);
  __ Addu(t2, v0, Operand(SeqAsciiString::kHeaderSize - kHeapObjectTag));
  // v0: result string.
  // t3: first character of first string.
  // a1: first character of second string
  // a2: length of first string.
  // a3: length of second string.
  // t2: first character of result.

  StringHelper::GenerateCopyCharacters(masm, t2, t3, a2, t0, true);
  // t2: next character of result.
  StringHelper::GenerateCopyCharacters(masm, t2, a1, a3, t0, true);
  __ IncrementCounter(counters->string_add_native(), 1, a2, a3);
  __ DropAndRet(2);

  __ bind(&non_ascii_string_add_flat_result);
  __ AllocateTwoByteString(v0, t2, t0, t1, t5, &call_runtime);
  __ Addu(t2, v0, Operand(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
  // v0: result string.
  // t3: first character of first string.
  // a1: first character of second string.
  // a2: length of first string.
  // a3: length of second string.
  // t2: first character of result.
  StringHelper::GenerateCopyCharacters(masm, t2, t3, a2, t0, false);
  // t2: next character of result.
  StringHelper::GenerateCopyCharacters(masm, t2, a1, a3, t0, false);

  __ IncrementCounter(counters->string_add_native(), 1, a2, a3);
  __ DropAndRet(2);

  // Just jump to runtime to add the two strings.
  __ bind(&call_runtime);
  __ TailCallRuntime(Runtime::kStringAdd, 2, 1);

  if (call_builtin.is_linked()) {
    __ bind(&call_builtin);
    __ InvokeBuiltin(builtin_id, JUMP_FUNCTION);
  }
}


void StringAddStub::GenerateConvertArgument(MacroAssembler* masm,
                                            int stack_offset,
                                            Register arg,
                                            Register scratch1,
                                            Register scratch2,
                                            Register scratch3,
                                            Register scratch4,
                                            Label* slow) {
  // First check if the argument is already a string.
  Label not_string, done;
  __ JumpIfSmi(arg, &not_string);
  __ GetObjectType(arg, scratch1, scratch1);
  __ Branch(&done, lt, scratch1, Operand(FIRST_NONSTRING_TYPE));

  // Check the number to string cache.
  Label not_cached;
  __ bind(&not_string);
  // Puts the cached result into scratch1.
  NumberToStringStub::GenerateLookupNumberStringCache(masm,
                                                      arg,
                                                      scratch1,
                                                      scratch2,
                                                      scratch3,
                                                      scratch4,
                                                      false,
                                                      &not_cached);
  __ mov(arg, scratch1);
  __ sw(arg, MemOperand(sp, stack_offset));
  __ jmp(&done);

  // Check if the argument is a safe string wrapper.
  __ bind(&not_cached);
  __ JumpIfSmi(arg, slow);
  __ GetObjectType(arg, scratch1, scratch2);  // map -> scratch1.
  __ Branch(slow, ne, scratch2, Operand(JS_VALUE_TYPE));
  __ lbu(scratch2, FieldMemOperand(scratch1, Map::kBitField2Offset));
  __ li(scratch4, 1 << Map::kStringWrapperSafeForDefaultValueOf);
  __ And(scratch2, scratch2, scratch4);
  __ Branch(slow, ne, scratch2, Operand(scratch4));
  __ lw(arg, FieldMemOperand(arg, JSValue::kValueOffset));
  __ sw(arg, MemOperand(sp, stack_offset));

  __ bind(&done);
}


void ICCompareStub::GenerateSmis(MacroAssembler* masm) {
  ASSERT(state_ == CompareIC::SMIS);
  Label miss;
  __ Or(a2, a1, a0);
  __ JumpIfNotSmi(a2, &miss);

  if (GetCondition() == eq) {
    // For equality we do not care about the sign of the result.
    __ Subu(v0, a0, a1);
  } else {
    // Untag before subtracting to avoid handling overflow.
    __ SmiUntag(a1);
    __ SmiUntag(a0);
    __ Subu(v0, a1, a0);
  }
  __ Ret();

  __ bind(&miss);
  GenerateMiss(masm);
}


void ICCompareStub::GenerateHeapNumbers(MacroAssembler* masm) {
  ASSERT(state_ == CompareIC::HEAP_NUMBERS);

  Label generic_stub;
  Label unordered, maybe_undefined1, maybe_undefined2;
  Label miss;
  __ And(a2, a1, Operand(a0));
  __ JumpIfSmi(a2, &generic_stub);

  __ GetObjectType(a0, a2, a2);
  __ Branch(&maybe_undefined1, ne, a2, Operand(HEAP_NUMBER_TYPE));
  __ GetObjectType(a1, a2, a2);
  __ Branch(&maybe_undefined2, ne, a2, Operand(HEAP_NUMBER_TYPE));

  // Inlining the double comparison and falling back to the general compare
  // stub if NaN is involved or FPU is unsupported.
  if (CpuFeatures::IsSupported(FPU)) {
    CpuFeatures::Scope scope(FPU);

    // Load left and right operand.
    __ Subu(a2, a1, Operand(kHeapObjectTag));
    __ ldc1(f0, MemOperand(a2, HeapNumber::kValueOffset));
    __ Subu(a2, a0, Operand(kHeapObjectTag));
    __ ldc1(f2, MemOperand(a2, HeapNumber::kValueOffset));

    // Return a result of -1, 0, or 1, or use CompareStub for NaNs.
    Label fpu_eq, fpu_lt;
    // Test if equal, and also handle the unordered/NaN case.
    __ BranchF(&fpu_eq, &unordered, eq, f0, f2);

    // Test if less (unordered case is already handled).
    __ BranchF(&fpu_lt, NULL, lt, f0, f2);

    // Otherwise it's greater, so just fall thru, and return.
    __ li(v0, Operand(GREATER));
    __ Ret();

    __ bind(&fpu_eq);
    __ li(v0, Operand(EQUAL));
    __ Ret();

    __ bind(&fpu_lt);
    __ li(v0, Operand(LESS));
    __ Ret();
  }

  __ bind(&unordered);

  CompareStub stub(GetCondition(), strict(), NO_COMPARE_FLAGS, a1, a0);
  __ bind(&generic_stub);
  __ Jump(stub.GetCode(), RelocInfo::CODE_TARGET);

  __ bind(&maybe_undefined1);
  if (Token::IsOrderedRelationalCompareOp(op_)) {
    __ LoadRoot(at, Heap::kUndefinedValueRootIndex);
    __ Branch(&miss, ne, a0, Operand(at));
    __ GetObjectType(a1, a2, a2);
    __ Branch(&maybe_undefined2, ne, a2, Operand(HEAP_NUMBER_TYPE));
    __ jmp(&unordered);
  }

  __ bind(&maybe_undefined2);
  if (Token::IsOrderedRelationalCompareOp(op_)) {
    __ LoadRoot(at, Heap::kUndefinedValueRootIndex);
    __ Branch(&unordered, eq, a1, Operand(at));
  }

  __ bind(&miss);
  GenerateMiss(masm);
}


void ICCompareStub::GenerateSymbols(MacroAssembler* masm) {
  ASSERT(state_ == CompareIC::SYMBOLS);
  Label miss;

  // Registers containing left and right operands respectively.
  Register left = a1;
  Register right = a0;
  Register tmp1 = a2;
  Register tmp2 = a3;

  // Check that both operands are heap objects.
  __ JumpIfEitherSmi(left, right, &miss);

  // Check that both operands are symbols.
  __ lw(tmp1, FieldMemOperand(left, HeapObject::kMapOffset));
  __ lw(tmp2, FieldMemOperand(right, HeapObject::kMapOffset));
  __ lbu(tmp1, FieldMemOperand(tmp1, Map::kInstanceTypeOffset));
  __ lbu(tmp2, FieldMemOperand(tmp2, Map::kInstanceTypeOffset));
  STATIC_ASSERT(kSymbolTag != 0);
  __ And(tmp1, tmp1, Operand(tmp2));
  __ And(tmp1, tmp1, kIsSymbolMask);
  __ Branch(&miss, eq, tmp1, Operand(zero_reg));
  // Make sure a0 is non-zero. At this point input operands are
  // guaranteed to be non-zero.
  ASSERT(right.is(a0));
  STATIC_ASSERT(EQUAL == 0);
  STATIC_ASSERT(kSmiTag == 0);
  __ mov(v0, right);
  // Symbols are compared by identity.
  __ Ret(ne, left, Operand(right));
  __ li(v0, Operand(Smi::FromInt(EQUAL)));
  __ Ret();

  __ bind(&miss);
  GenerateMiss(masm);
}


void ICCompareStub::GenerateStrings(MacroAssembler* masm) {
  ASSERT(state_ == CompareIC::STRINGS);
  Label miss;

  bool equality = Token::IsEqualityOp(op_);

  // Registers containing left and right operands respectively.
  Register left = a1;
  Register right = a0;
  Register tmp1 = a2;
  Register tmp2 = a3;
  Register tmp3 = t0;
  Register tmp4 = t1;
  Register tmp5 = t2;

  // Check that both operands are heap objects.
  __ JumpIfEitherSmi(left, right, &miss);

  // Check that both operands are strings. This leaves the instance
  // types loaded in tmp1 and tmp2.
  __ lw(tmp1, FieldMemOperand(left, HeapObject::kMapOffset));
  __ lw(tmp2, FieldMemOperand(right, HeapObject::kMapOffset));
  __ lbu(tmp1, FieldMemOperand(tmp1, Map::kInstanceTypeOffset));
  __ lbu(tmp2, FieldMemOperand(tmp2, Map::kInstanceTypeOffset));
  STATIC_ASSERT(kNotStringTag != 0);
  __ Or(tmp3, tmp1, tmp2);
  __ And(tmp5, tmp3, Operand(kIsNotStringMask));
  __ Branch(&miss, ne, tmp5, Operand(zero_reg));

  // Fast check for identical strings.
  Label left_ne_right;
  STATIC_ASSERT(EQUAL == 0);
  STATIC_ASSERT(kSmiTag == 0);
  __ Branch(&left_ne_right, ne, left, Operand(right));
  __ Ret(USE_DELAY_SLOT);
  __ mov(v0, zero_reg);  // In the delay slot.
  __ bind(&left_ne_right);

  // Handle not identical strings.

  // Check that both strings are symbols. If they are, we're done
  // because we already know they are not identical.
  if (equality) {
    ASSERT(GetCondition() == eq);
    STATIC_ASSERT(kSymbolTag != 0);
    __ And(tmp3, tmp1, Operand(tmp2));
    __ And(tmp5, tmp3, Operand(kIsSymbolMask));
    Label is_symbol;
    __ Branch(&is_symbol, eq, tmp5, Operand(zero_reg));
    // Make sure a0 is non-zero. At this point input operands are
    // guaranteed to be non-zero.
    ASSERT(right.is(a0));
    __ Ret(USE_DELAY_SLOT);
    __ mov(v0, a0);  // In the delay slot.
    __ bind(&is_symbol);
  }

  // Check that both strings are sequential ASCII.
  Label runtime;
  __ JumpIfBothInstanceTypesAreNotSequentialAscii(
      tmp1, tmp2, tmp3, tmp4, &runtime);

  // Compare flat ASCII strings. Returns when done.
  if (equality) {
    StringCompareStub::GenerateFlatAsciiStringEquals(
        masm, left, right, tmp1, tmp2, tmp3);
  } else {
    StringCompareStub::GenerateCompareFlatAsciiStrings(
        masm, left, right, tmp1, tmp2, tmp3, tmp4);
  }

  // Handle more complex cases in runtime.
  __ bind(&runtime);
  __ Push(left, right);
  if (equality) {
    __ TailCallRuntime(Runtime::kStringEquals, 2, 1);
  } else {
    __ TailCallRuntime(Runtime::kStringCompare, 2, 1);
  }

  __ bind(&miss);
  GenerateMiss(masm);
}


void ICCompareStub::GenerateObjects(MacroAssembler* masm) {
  ASSERT(state_ == CompareIC::OBJECTS);
  Label miss;
  __ And(a2, a1, Operand(a0));
  __ JumpIfSmi(a2, &miss);

  __ GetObjectType(a0, a2, a2);
  __ Branch(&miss, ne, a2, Operand(JS_OBJECT_TYPE));
  __ GetObjectType(a1, a2, a2);
  __ Branch(&miss, ne, a2, Operand(JS_OBJECT_TYPE));

  ASSERT(GetCondition() == eq);
  __ Ret(USE_DELAY_SLOT);
  __ subu(v0, a0, a1);

  __ bind(&miss);
  GenerateMiss(masm);
}


void ICCompareStub::GenerateKnownObjects(MacroAssembler* masm) {
  Label miss;
  __ And(a2, a1, a0);
  __ JumpIfSmi(a2, &miss);
  __ lw(a2, FieldMemOperand(a0, HeapObject::kMapOffset));
  __ lw(a3, FieldMemOperand(a1, HeapObject::kMapOffset));
  __ Branch(&miss, ne, a2, Operand(known_map_));
  __ Branch(&miss, ne, a3, Operand(known_map_));

  __ Ret(USE_DELAY_SLOT);
  __ subu(v0, a0, a1);

  __ bind(&miss);
  GenerateMiss(masm);
}

void ICCompareStub::GenerateMiss(MacroAssembler* masm) {
  {
    // Call the runtime system in a fresh internal frame.
    ExternalReference miss =
        ExternalReference(IC_Utility(IC::kCompareIC_Miss), masm->isolate());
    FrameScope scope(masm, StackFrame::INTERNAL);
    __ Push(a1, a0);
    __ push(ra);
    __ Push(a1, a0);
    __ li(t0, Operand(Smi::FromInt(op_)));
    __ addiu(sp, sp, -kPointerSize);
    __ CallExternalReference(miss, 3, USE_DELAY_SLOT);
    __ sw(t0, MemOperand(sp));  // In the delay slot.
    // Compute the entry point of the rewritten stub.
    __ Addu(a2, v0, Operand(Code::kHeaderSize - kHeapObjectTag));
    // Restore registers.
    __ Pop(a1, a0, ra);
  }
  __ Jump(a2);
}


void DirectCEntryStub::Generate(MacroAssembler* masm) {
  // No need to pop or drop anything, LeaveExitFrame will restore the old
  // stack, thus dropping the allocated space for the return value.
  // The saved ra is after the reserved stack space for the 4 args.
  __ lw(t9, MemOperand(sp, kCArgsSlotsSize));

  if (FLAG_debug_code && FLAG_enable_slow_asserts) {
    // In case of an error the return address may point to a memory area
    // filled with kZapValue by the GC.
    // Dereference the address and check for this.
    __ lw(t0, MemOperand(t9));
    __ Assert(ne, "Received invalid return address.", t0,
        Operand(reinterpret_cast<uint32_t>(kZapValue)));
  }
  __ Jump(t9);
}


void DirectCEntryStub::GenerateCall(MacroAssembler* masm,
                                    ExternalReference function) {
  __ li(t9, Operand(function));
  this->GenerateCall(masm, t9);
}


void DirectCEntryStub::GenerateCall(MacroAssembler* masm,
                                    Register target) {
  __ Move(t9, target);
  __ AssertStackIsAligned();
  // Allocate space for arg slots.
  __ Subu(sp, sp, kCArgsSlotsSize);

  // Block the trampoline pool through the whole function to make sure the
  // number of generated instructions is constant.
  Assembler::BlockTrampolinePoolScope block_trampoline_pool(masm);

  // We need to get the current 'pc' value, which is not available on MIPS.
  Label find_ra;
  masm->bal(&find_ra);  // ra = pc + 8.
  masm->nop();  // Branch delay slot nop.
  masm->bind(&find_ra);

  const int kNumInstructionsToJump = 6;
  masm->addiu(ra, ra, kNumInstructionsToJump * kPointerSize);
  // Push return address (accessible to GC through exit frame pc).
  // This spot for ra was reserved in EnterExitFrame.
  masm->sw(ra, MemOperand(sp, kCArgsSlotsSize));
  masm->li(ra,
           Operand(reinterpret_cast<intptr_t>(GetCode().location()),
                   RelocInfo::CODE_TARGET),
           CONSTANT_SIZE);
  // Call the function.
  masm->Jump(t9);
  // Make sure the stored 'ra' points to this position.
  ASSERT_EQ(kNumInstructionsToJump, masm->InstructionsGeneratedSince(&find_ra));
}


void StringDictionaryLookupStub::GenerateNegativeLookup(MacroAssembler* masm,
                                                        Label* miss,
                                                        Label* done,
                                                        Register receiver,
                                                        Register properties,
                                                        Handle<String> name,
                                                        Register scratch0) {
  // If names of slots in range from 1 to kProbes - 1 for the hash value are
  // not equal to the name and kProbes-th slot is not used (its name is the
  // undefined value), it guarantees the hash table doesn't contain the
  // property. It's true even if some slots represent deleted properties
  // (their names are the hole value).
  for (int i = 0; i < kInlinedProbes; i++) {
    // scratch0 points to properties hash.
    // Compute the masked index: (hash + i + i * i) & mask.
    Register index = scratch0;
    // Capacity is smi 2^n.
    __ lw(index, FieldMemOperand(properties, kCapacityOffset));
    __ Subu(index, index, Operand(1));
    __ And(index, index, Operand(
        Smi::FromInt(name->Hash() + StringDictionary::GetProbeOffset(i))));

    // Scale the index by multiplying by the entry size.
    ASSERT(StringDictionary::kEntrySize == 3);
    __ sll(at, index, 1);
    __ Addu(index, index, at);

    Register entity_name = scratch0;
    // Having undefined at this place means the name is not contained.
    ASSERT_EQ(kSmiTagSize, 1);
    Register tmp = properties;
    __ sll(scratch0, index, 1);
    __ Addu(tmp, properties, scratch0);
    __ lw(entity_name, FieldMemOperand(tmp, kElementsStartOffset));

    ASSERT(!tmp.is(entity_name));
    __ LoadRoot(tmp, Heap::kUndefinedValueRootIndex);
    __ Branch(done, eq, entity_name, Operand(tmp));

    if (i != kInlinedProbes - 1) {
      // Load the hole ready for use below:
      __ LoadRoot(tmp, Heap::kTheHoleValueRootIndex);

      // Stop if found the property.
      __ Branch(miss, eq, entity_name, Operand(Handle<String>(name)));

      Label the_hole;
      __ Branch(&the_hole, eq, entity_name, Operand(tmp));

      // Check if the entry name is not a symbol.
      __ lw(entity_name, FieldMemOperand(entity_name, HeapObject::kMapOffset));
      __ lbu(entity_name,
             FieldMemOperand(entity_name, Map::kInstanceTypeOffset));
      __ And(scratch0, entity_name, Operand(kIsSymbolMask));
      __ Branch(miss, eq, scratch0, Operand(zero_reg));

      __ bind(&the_hole);

      // Restore the properties.
      __ lw(properties,
            FieldMemOperand(receiver, JSObject::kPropertiesOffset));
    }
  }

  const int spill_mask =
      (ra.bit() | t2.bit() | t1.bit() | t0.bit() | a3.bit() |
       a2.bit() | a1.bit() | a0.bit() | v0.bit());

  __ MultiPush(spill_mask);
  __ lw(a0, FieldMemOperand(receiver, JSObject::kPropertiesOffset));
  __ li(a1, Operand(Handle<String>(name)));
  StringDictionaryLookupStub stub(NEGATIVE_LOOKUP);
  __ CallStub(&stub);
  __ mov(at, v0);
  __ MultiPop(spill_mask);

  __ Branch(done, eq, at, Operand(zero_reg));
  __ Branch(miss, ne, at, Operand(zero_reg));
}


// Probe the string dictionary in the |elements| register. Jump to the
// |done| label if a property with the given name is found. Jump to
// the |miss| label otherwise.
// If lookup was successful |scratch2| will be equal to elements + 4 * index.
void StringDictionaryLookupStub::GeneratePositiveLookup(MacroAssembler* masm,
                                                        Label* miss,
                                                        Label* done,
                                                        Register elements,
                                                        Register name,
                                                        Register scratch1,
                                                        Register scratch2) {
  ASSERT(!elements.is(scratch1));
  ASSERT(!elements.is(scratch2));
  ASSERT(!name.is(scratch1));
  ASSERT(!name.is(scratch2));

  // Assert that name contains a string.
  if (FLAG_debug_code) __ AbortIfNotString(name);

  // Compute the capacity mask.
  __ lw(scratch1, FieldMemOperand(elements, kCapacityOffset));
  __ sra(scratch1, scratch1, kSmiTagSize);  // convert smi to int
  __ Subu(scratch1, scratch1, Operand(1));

  // Generate an unrolled loop that performs a few probes before
  // giving up. Measurements done on Gmail indicate that 2 probes
  // cover ~93% of loads from dictionaries.
  for (int i = 0; i < kInlinedProbes; i++) {
    // Compute the masked index: (hash + i + i * i) & mask.
    __ lw(scratch2, FieldMemOperand(name, String::kHashFieldOffset));
    if (i > 0) {
      // Add the probe offset (i + i * i) left shifted to avoid right shifting
      // the hash in a separate instruction. The value hash + i + i * i is right
      // shifted in the following and instruction.
      ASSERT(StringDictionary::GetProbeOffset(i) <
             1 << (32 - String::kHashFieldOffset));
      __ Addu(scratch2, scratch2, Operand(
           StringDictionary::GetProbeOffset(i) << String::kHashShift));
    }
    __ srl(scratch2, scratch2, String::kHashShift);
    __ And(scratch2, scratch1, scratch2);

    // Scale the index by multiplying by the element size.
    ASSERT(StringDictionary::kEntrySize == 3);
    // scratch2 = scratch2 * 3.

    __ sll(at, scratch2, 1);
    __ Addu(scratch2, scratch2, at);

    // Check if the key is identical to the name.
    __ sll(at, scratch2, 2);
    __ Addu(scratch2, elements, at);
    __ lw(at, FieldMemOperand(scratch2, kElementsStartOffset));
    __ Branch(done, eq, name, Operand(at));
  }

  const int spill_mask =
      (ra.bit() | t2.bit() | t1.bit() | t0.bit() |
       a3.bit() | a2.bit() | a1.bit() | a0.bit() | v0.bit()) &
      ~(scratch1.bit() | scratch2.bit());

  __ MultiPush(spill_mask);
  if (name.is(a0)) {
    ASSERT(!elements.is(a1));
    __ Move(a1, name);
    __ Move(a0, elements);
  } else {
    __ Move(a0, elements);
    __ Move(a1, name);
  }
  StringDictionaryLookupStub stub(POSITIVE_LOOKUP);
  __ CallStub(&stub);
  __ mov(scratch2, a2);
  __ mov(at, v0);
  __ MultiPop(spill_mask);

  __ Branch(done, ne, at, Operand(zero_reg));
  __ Branch(miss, eq, at, Operand(zero_reg));
}


void StringDictionaryLookupStub::Generate(MacroAssembler* masm) {
  // This stub overrides SometimesSetsUpAFrame() to return false.  That means
  // we cannot call anything that could cause a GC from this stub.
  // Registers:
  //  result: StringDictionary to probe
  //  a1: key
  //  : StringDictionary to probe.
  //  index_: will hold an index of entry if lookup is successful.
  //          might alias with result_.
  // Returns:
  //  result_ is zero if lookup failed, non zero otherwise.

  Register result = v0;
  Register dictionary = a0;
  Register key = a1;
  Register index = a2;
  Register mask = a3;
  Register hash = t0;
  Register undefined = t1;
  Register entry_key = t2;

  Label in_dictionary, maybe_in_dictionary, not_in_dictionary;

  __ lw(mask, FieldMemOperand(dictionary, kCapacityOffset));
  __ sra(mask, mask, kSmiTagSize);
  __ Subu(mask, mask, Operand(1));

  __ lw(hash, FieldMemOperand(key, String::kHashFieldOffset));

  __ LoadRoot(undefined, Heap::kUndefinedValueRootIndex);

  for (int i = kInlinedProbes; i < kTotalProbes; i++) {
    // Compute the masked index: (hash + i + i * i) & mask.
    // Capacity is smi 2^n.
    if (i > 0) {
      // Add the probe offset (i + i * i) left shifted to avoid right shifting
      // the hash in a separate instruction. The value hash + i + i * i is right
      // shifted in the following and instruction.
      ASSERT(StringDictionary::GetProbeOffset(i) <
             1 << (32 - String::kHashFieldOffset));
      __ Addu(index, hash, Operand(
           StringDictionary::GetProbeOffset(i) << String::kHashShift));
    } else {
      __ mov(index, hash);
    }
    __ srl(index, index, String::kHashShift);
    __ And(index, mask, index);

    // Scale the index by multiplying by the entry size.
    ASSERT(StringDictionary::kEntrySize == 3);
    // index *= 3.
    __ mov(at, index);
    __ sll(index, index, 1);
    __ Addu(index, index, at);


    ASSERT_EQ(kSmiTagSize, 1);
    __ sll(index, index, 2);
    __ Addu(index, index, dictionary);
    __ lw(entry_key, FieldMemOperand(index, kElementsStartOffset));

    // Having undefined at this place means the name is not contained.
    __ Branch(&not_in_dictionary, eq, entry_key, Operand(undefined));

    // Stop if found the property.
    __ Branch(&in_dictionary, eq, entry_key, Operand(key));

    if (i != kTotalProbes - 1 && mode_ == NEGATIVE_LOOKUP) {
      // Check if the entry name is not a symbol.
      __ lw(entry_key, FieldMemOperand(entry_key, HeapObject::kMapOffset));
      __ lbu(entry_key,
             FieldMemOperand(entry_key, Map::kInstanceTypeOffset));
      __ And(result, entry_key, Operand(kIsSymbolMask));
      __ Branch(&maybe_in_dictionary, eq, result, Operand(zero_reg));
    }
  }

  __ bind(&maybe_in_dictionary);
  // If we are doing negative lookup then probing failure should be
  // treated as a lookup success. For positive lookup probing failure
  // should be treated as lookup failure.
  if (mode_ == POSITIVE_LOOKUP) {
    __ Ret(USE_DELAY_SLOT);
    __ mov(result, zero_reg);
  }

  __ bind(&in_dictionary);
  __ Ret(USE_DELAY_SLOT);
  __ li(result, 1);

  __ bind(&not_in_dictionary);
  __ Ret(USE_DELAY_SLOT);
  __ mov(result, zero_reg);
}


struct AheadOfTimeWriteBarrierStubList {
  Register object, value, address;
  RememberedSetAction action;
};

#define REG(Name) { kRegister_ ## Name ## _Code }

static const AheadOfTimeWriteBarrierStubList kAheadOfTime[] = {
  // Used in RegExpExecStub.
  { REG(s2), REG(s0), REG(t3), EMIT_REMEMBERED_SET },
  { REG(s2), REG(a2), REG(t3), EMIT_REMEMBERED_SET },
  // Used in CompileArrayPushCall.
  // Also used in StoreIC::GenerateNormal via GenerateDictionaryStore.
  // Also used in KeyedStoreIC::GenerateGeneric.
  { REG(a3), REG(t0), REG(t1), EMIT_REMEMBERED_SET },
  // Used in CompileStoreGlobal.
  { REG(t0), REG(a1), REG(a2), OMIT_REMEMBERED_SET },
  // Used in StoreStubCompiler::CompileStoreField via GenerateStoreField.
  { REG(a1), REG(a2), REG(a3), EMIT_REMEMBERED_SET },
  { REG(a3), REG(a2), REG(a1), EMIT_REMEMBERED_SET },
  // Used in KeyedStoreStubCompiler::CompileStoreField via GenerateStoreField.
  { REG(a2), REG(a1), REG(a3), EMIT_REMEMBERED_SET },
  { REG(a3), REG(a1), REG(a2), EMIT_REMEMBERED_SET },
  // KeyedStoreStubCompiler::GenerateStoreFastElement.
  { REG(a3), REG(a2), REG(t0), EMIT_REMEMBERED_SET },
  { REG(a2), REG(a3), REG(t0), EMIT_REMEMBERED_SET },
  // ElementsTransitionGenerator::GenerateMapChangeElementTransition
  // and ElementsTransitionGenerator::GenerateSmiToDouble
  // and ElementsTransitionGenerator::GenerateDoubleToObject
  { REG(a2), REG(a3), REG(t5), EMIT_REMEMBERED_SET },
  { REG(a2), REG(a3), REG(t5), OMIT_REMEMBERED_SET },
  // ElementsTransitionGenerator::GenerateDoubleToObject
  { REG(t2), REG(a2), REG(a0), EMIT_REMEMBERED_SET },
  { REG(a2), REG(t2), REG(t5), EMIT_REMEMBERED_SET },
  // StoreArrayLiteralElementStub::Generate
  { REG(t1), REG(a0), REG(t2), EMIT_REMEMBERED_SET },
  // FastNewClosureStub::Generate
  { REG(a2), REG(t0), REG(a1), EMIT_REMEMBERED_SET },
  // Null termination.
  { REG(no_reg), REG(no_reg), REG(no_reg), EMIT_REMEMBERED_SET}
};

#undef REG


bool RecordWriteStub::IsPregenerated() {
  for (const AheadOfTimeWriteBarrierStubList* entry = kAheadOfTime;
       !entry->object.is(no_reg);
       entry++) {
    if (object_.is(entry->object) &&
        value_.is(entry->value) &&
        address_.is(entry->address) &&
        remembered_set_action_ == entry->action &&
        save_fp_regs_mode_ == kDontSaveFPRegs) {
      return true;
    }
  }
  return false;
}


bool StoreBufferOverflowStub::IsPregenerated() {
  return save_doubles_ == kDontSaveFPRegs || ISOLATE->fp_stubs_generated();
}


void StoreBufferOverflowStub::GenerateFixedRegStubsAheadOfTime() {
  StoreBufferOverflowStub stub1(kDontSaveFPRegs);
  stub1.GetCode()->set_is_pregenerated(true);
}


void RecordWriteStub::GenerateFixedRegStubsAheadOfTime() {
  for (const AheadOfTimeWriteBarrierStubList* entry = kAheadOfTime;
       !entry->object.is(no_reg);
       entry++) {
    RecordWriteStub stub(entry->object,
                         entry->value,
                         entry->address,
                         entry->action,
                         kDontSaveFPRegs);
    stub.GetCode()->set_is_pregenerated(true);
  }
}


// Takes the input in 3 registers: address_ value_ and object_.  A pointer to
// the value has just been written into the object, now this stub makes sure
// we keep the GC informed.  The word in the object where the value has been
// written is in the address register.
void RecordWriteStub::Generate(MacroAssembler* masm) {
  Label skip_to_incremental_noncompacting;
  Label skip_to_incremental_compacting;

  // The first two branch+nop instructions are generated with labels so as to
  // get the offset fixed up correctly by the bind(Label*) call.  We patch it
  // back and forth between a "bne zero_reg, zero_reg, ..." (a nop in this
  // position) and the "beq zero_reg, zero_reg, ..." when we start and stop
  // incremental heap marking.
  // See RecordWriteStub::Patch for details.
  __ beq(zero_reg, zero_reg, &skip_to_incremental_noncompacting);
  __ nop();
  __ beq(zero_reg, zero_reg, &skip_to_incremental_compacting);
  __ nop();

  if (remembered_set_action_ == EMIT_REMEMBERED_SET) {
    __ RememberedSetHelper(object_,
                           address_,
                           value_,
                           save_fp_regs_mode_,
                           MacroAssembler::kReturnAtEnd);
  }
  __ Ret();

  __ bind(&skip_to_incremental_noncompacting);
  GenerateIncremental(masm, INCREMENTAL);

  __ bind(&skip_to_incremental_compacting);
  GenerateIncremental(masm, INCREMENTAL_COMPACTION);

  // Initial mode of the stub is expected to be STORE_BUFFER_ONLY.
  // Will be checked in IncrementalMarking::ActivateGeneratedStub.

  PatchBranchIntoNop(masm, 0);
  PatchBranchIntoNop(masm, 2 * Assembler::kInstrSize);
}


void RecordWriteStub::GenerateIncremental(MacroAssembler* masm, Mode mode) {
  regs_.Save(masm);

  if (remembered_set_action_ == EMIT_REMEMBERED_SET) {
    Label dont_need_remembered_set;

    __ lw(regs_.scratch0(), MemOperand(regs_.address(), 0));
    __ JumpIfNotInNewSpace(regs_.scratch0(),  // Value.
                           regs_.scratch0(),
                           &dont_need_remembered_set);

    __ CheckPageFlag(regs_.object(),
                     regs_.scratch0(),
                     1 << MemoryChunk::SCAN_ON_SCAVENGE,
                     ne,
                     &dont_need_remembered_set);

    // First notify the incremental marker if necessary, then update the
    // remembered set.
    CheckNeedsToInformIncrementalMarker(
        masm, kUpdateRememberedSetOnNoNeedToInformIncrementalMarker, mode);
    InformIncrementalMarker(masm, mode);
    regs_.Restore(masm);
    __ RememberedSetHelper(object_,
                           address_,
                           value_,
                           save_fp_regs_mode_,
                           MacroAssembler::kReturnAtEnd);

    __ bind(&dont_need_remembered_set);
  }

  CheckNeedsToInformIncrementalMarker(
      masm, kReturnOnNoNeedToInformIncrementalMarker, mode);
  InformIncrementalMarker(masm, mode);
  regs_.Restore(masm);
  __ Ret();
}


void RecordWriteStub::InformIncrementalMarker(MacroAssembler* masm, Mode mode) {
  regs_.SaveCallerSaveRegisters(masm, save_fp_regs_mode_);
  int argument_count = 3;
  __ PrepareCallCFunction(argument_count, regs_.scratch0());
  Register address =
      a0.is(regs_.address()) ? regs_.scratch0() : regs_.address();
  ASSERT(!address.is(regs_.object()));
  ASSERT(!address.is(a0));
  __ Move(address, regs_.address());
  __ Move(a0, regs_.object());
  if (mode == INCREMENTAL_COMPACTION) {
    __ Move(a1, address);
  } else {
    ASSERT(mode == INCREMENTAL);
    __ lw(a1, MemOperand(address, 0));
  }
  __ li(a2, Operand(ExternalReference::isolate_address()));

  AllowExternalCallThatCantCauseGC scope(masm);
  if (mode == INCREMENTAL_COMPACTION) {
    __ CallCFunction(
        ExternalReference::incremental_evacuation_record_write_function(
            masm->isolate()),
        argument_count);
  } else {
    ASSERT(mode == INCREMENTAL);
    __ CallCFunction(
        ExternalReference::incremental_marking_record_write_function(
            masm->isolate()),
        argument_count);
  }
  regs_.RestoreCallerSaveRegisters(masm, save_fp_regs_mode_);
}


void RecordWriteStub::CheckNeedsToInformIncrementalMarker(
    MacroAssembler* masm,
    OnNoNeedToInformIncrementalMarker on_no_need,
    Mode mode) {
  Label on_black;
  Label need_incremental;
  Label need_incremental_pop_scratch;

  // Let's look at the color of the object:  If it is not black we don't have
  // to inform the incremental marker.
  __ JumpIfBlack(regs_.object(), regs_.scratch0(), regs_.scratch1(), &on_black);

  regs_.Restore(masm);
  if (on_no_need == kUpdateRememberedSetOnNoNeedToInformIncrementalMarker) {
    __ RememberedSetHelper(object_,
                           address_,
                           value_,
                           save_fp_regs_mode_,
                           MacroAssembler::kReturnAtEnd);
  } else {
    __ Ret();
  }

  __ bind(&on_black);

  // Get the value from the slot.
  __ lw(regs_.scratch0(), MemOperand(regs_.address(), 0));

  if (mode == INCREMENTAL_COMPACTION) {
    Label ensure_not_white;

    __ CheckPageFlag(regs_.scratch0(),  // Contains value.
                     regs_.scratch1(),  // Scratch.
                     MemoryChunk::kEvacuationCandidateMask,
                     eq,
                     &ensure_not_white);

    __ CheckPageFlag(regs_.object(),
                     regs_.scratch1(),  // Scratch.
                     MemoryChunk::kSkipEvacuationSlotsRecordingMask,
                     eq,
                     &need_incremental);

    __ bind(&ensure_not_white);
  }

  // We need extra registers for this, so we push the object and the address
  // register temporarily.
  __ Push(regs_.object(), regs_.address());
  __ EnsureNotWhite(regs_.scratch0(),  // The value.
                    regs_.scratch1(),  // Scratch.
                    regs_.object(),  // Scratch.
                    regs_.address(),  // Scratch.
                    &need_incremental_pop_scratch);
  __ Pop(regs_.object(), regs_.address());

  regs_.Restore(masm);
  if (on_no_need == kUpdateRememberedSetOnNoNeedToInformIncrementalMarker) {
    __ RememberedSetHelper(object_,
                           address_,
                           value_,
                           save_fp_regs_mode_,
                           MacroAssembler::kReturnAtEnd);
  } else {
    __ Ret();
  }

  __ bind(&need_incremental_pop_scratch);
  __ Pop(regs_.object(), regs_.address());

  __ bind(&need_incremental);

  // Fall through when we need to inform the incremental marker.
}


void StoreArrayLiteralElementStub::Generate(MacroAssembler* masm) {
  // ----------- S t a t e -------------
  //  -- a0    : element value to store
  //  -- a1    : array literal
  //  -- a2    : map of array literal
  //  -- a3    : element index as smi
  //  -- t0    : array literal index in function as smi
  // -----------------------------------

  Label element_done;
  Label double_elements;
  Label smi_element;
  Label slow_elements;
  Label fast_elements;

  __ CheckFastElements(a2, t1, &double_elements);
  // Check for FAST_*_SMI_ELEMENTS or FAST_*_ELEMENTS elements
  __ JumpIfSmi(a0, &smi_element);
  __ CheckFastSmiElements(a2, t1, &fast_elements);

  // Store into the array literal requires a elements transition. Call into
  // the runtime.
  __ bind(&slow_elements);
  // call.
  __ Push(a1, a3, a0);
  __ lw(t1, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
  __ lw(t1, FieldMemOperand(t1, JSFunction::kLiteralsOffset));
  __ Push(t1, t0);
  __ TailCallRuntime(Runtime::kStoreArrayLiteralElement, 5, 1);

  // Array literal has ElementsKind of FAST_*_ELEMENTS and value is an object.
  __ bind(&fast_elements);
  __ lw(t1, FieldMemOperand(a1, JSObject::kElementsOffset));
  __ sll(t2, a3, kPointerSizeLog2 - kSmiTagSize);
  __ Addu(t2, t1, t2);
  __ Addu(t2, t2, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
  __ sw(a0, MemOperand(t2, 0));
  // Update the write barrier for the array store.
  __ RecordWrite(t1, t2, a0, kRAHasNotBeenSaved, kDontSaveFPRegs,
                 EMIT_REMEMBERED_SET, OMIT_SMI_CHECK);
  __ Ret(USE_DELAY_SLOT);
  __ mov(v0, a0);

  // Array literal has ElementsKind of FAST_*_SMI_ELEMENTS or FAST_*_ELEMENTS,
  // and value is Smi.
  __ bind(&smi_element);
  __ lw(t1, FieldMemOperand(a1, JSObject::kElementsOffset));
  __ sll(t2, a3, kPointerSizeLog2 - kSmiTagSize);
  __ Addu(t2, t1, t2);
  __ sw(a0, FieldMemOperand(t2, FixedArray::kHeaderSize));
  __ Ret(USE_DELAY_SLOT);
  __ mov(v0, a0);

  // Array literal has ElementsKind of FAST_*_DOUBLE_ELEMENTS.
  __ bind(&double_elements);
  __ lw(t1, FieldMemOperand(a1, JSObject::kElementsOffset));
  __ StoreNumberToDoubleElements(a0, a3, a1, t1, t2, t3, t5, a2,
                                 &slow_elements);
  __ Ret(USE_DELAY_SLOT);
  __ mov(v0, a0);
}


#undef __

} }  // namespace v8::internal

#endif  // V8_TARGET_ARCH_MIPS

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