CSE2410 Fall 2014 Bounce

// 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

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// 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

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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#ifndef V8_MIPS_MACRO_ASSEMBLER_MIPS_H_

#define V8_MIPS_MACRO_ASSEMBLER_MIPS_H_

#include "assembler.h"

#include "mips/assembler-mips.h"

#include "v8globals.h"

namespace v8 {

namespace internal {

// Forward declaration.

class JumpTarget;

// Reserved Register Usage Summary.

//

// Registers t8, t9, and at are reserved for use by the MacroAssembler.

//

// The programmer should know that the MacroAssembler may clobber these three,

// but won't touch other registers except in special cases.

//

// Per the MIPS ABI, register t9 must be used for indirect function call

// via 'jalr t9' or 'jr t9' instructions. This is relied upon by gcc when

// trying to update gp register for position-independent-code. Whenever

// MIPS generated code calls C code, it must be via t9 register.

// Flags used for LeaveExitFrame function.

enum LeaveExitFrameMode {

  EMIT_RETURN = true,

  NO_EMIT_RETURN = false

};

// Flags used for AllocateHeapNumber

enum TaggingMode {

  // Tag the result.

  TAG_RESULT,

  // Don't tag

  DONT_TAG_RESULT

};

// Flags used for the ObjectToDoubleFPURegister function.

enum ObjectToDoubleFlags {

  // No special flags.

  NO_OBJECT_TO_DOUBLE_FLAGS = 0,

  // Object is known to be a non smi.

  OBJECT_NOT_SMI = 1 << 0,

  // Don't load NaNs or infinities, branch to the non number case instead.

  AVOID_NANS_AND_INFINITIES = 1 << 1

};

// Allow programmer to use Branch Delay Slot of Branches, Jumps, Calls.

enum BranchDelaySlot {

  USE_DELAY_SLOT,

  PROTECT

};

// Flags used for the li macro-assembler function.

enum LiFlags {

  // If the constant value can be represented in just 16 bits, then

  // optimize the li to use a single instruction, rather than lui/ori pair.

  OPTIMIZE_SIZE = 0,

  // Always use 2 instructions (lui/ori pair), even if the constant could

  // be loaded with just one, so that this value is patchable later.

  CONSTANT_SIZE = 1

};

enum RememberedSetAction { EMIT_REMEMBERED_SET, OMIT_REMEMBERED_SET };

enum SmiCheck { INLINE_SMI_CHECK, OMIT_SMI_CHECK };

enum RAStatus { kRAHasNotBeenSaved, kRAHasBeenSaved };

Register GetRegisterThatIsNotOneOf(Register reg1,

                                   Register reg2 = no_reg,

                                   Register reg3 = no_reg,

                                   Register reg4 = no_reg,

                                   Register reg5 = no_reg,

                                   Register reg6 = no_reg);

bool AreAliased(Register r1, Register r2, Register r3, Register r4);

// -----------------------------------------------------------------------------

// Static helper functions.

inline MemOperand ContextOperand(Register context, int index) {

  return MemOperand(context, Context::SlotOffset(index));

}

inline MemOperand GlobalObjectOperand()  {

  return ContextOperand(cp, Context::GLOBAL_OBJECT_INDEX);

}

// Generate a MemOperand for loading a field from an object.

inline MemOperand FieldMemOperand(Register object, int offset) {

  return MemOperand(object, offset - kHeapObjectTag);

}

// Generate a MemOperand for storing arguments 5..N on the stack

// when calling CallCFunction().

inline MemOperand CFunctionArgumentOperand(int index) {

  ASSERT(index > kCArgSlotCount);

  // Argument 5 takes the slot just past the four Arg-slots.

  int offset = (index - 5) * kPointerSize + kCArgsSlotsSize;

  return MemOperand(sp, offset);

}

// MacroAssembler implements a collection of frequently used macros.

class MacroAssembler: public Assembler {

 public:

  // The isolate parameter can be NULL if the macro assembler should

  // not use isolate-dependent functionality. In this case, it's the

  // responsibility of the caller to never invoke such function on the

  // macro assembler.

  MacroAssembler(Isolate* isolate, void* buffer, int size);

  // Arguments macros.

#define COND_TYPED_ARGS Condition cond, Register r1, const Operand& r2

#define COND_ARGS cond, r1, r2

  // Cases when relocation is not needed.

#define DECLARE_NORELOC_PROTOTYPE(Name, target_type) \

  void Name(target_type target, BranchDelaySlot bd = PROTECT); \

  inline void Name(BranchDelaySlot bd, target_type target) { \

    Name(target, bd); \

  } \

  void Name(target_type target, \

            COND_TYPED_ARGS, \

            BranchDelaySlot bd = PROTECT); \

  inline void Name(BranchDelaySlot bd, \

                   target_type target, \

                   COND_TYPED_ARGS) { \

    Name(target, COND_ARGS, bd); \

  }

#define DECLARE_BRANCH_PROTOTYPES(Name) \

  DECLARE_NORELOC_PROTOTYPE(Name, Label*) \

  DECLARE_NORELOC_PROTOTYPE(Name, int16_t)

  DECLARE_BRANCH_PROTOTYPES(Branch)

  DECLARE_BRANCH_PROTOTYPES(BranchAndLink)

#undef DECLARE_BRANCH_PROTOTYPES

#undef COND_TYPED_ARGS

#undef COND_ARGS

  // Jump, Call, and Ret pseudo instructions implementing inter-working.

#define COND_ARGS Condition cond = al, Register rs = zero_reg, \

  const Operand& rt = Operand(zero_reg), BranchDelaySlot bd = PROTECT

  void Jump(Register target, COND_ARGS);

  void Jump(intptr_t target, RelocInfo::Mode rmode, COND_ARGS);

  void Jump(Address target, RelocInfo::Mode rmode, COND_ARGS);

  void Jump(Handle<Code> code, RelocInfo::Mode rmode, COND_ARGS);

  static int CallSize(Register target, COND_ARGS);

  void Call(Register target, COND_ARGS);

  static int CallSize(Address target, RelocInfo::Mode rmode, COND_ARGS);

  void Call(Address target, RelocInfo::Mode rmode, COND_ARGS);

  int CallSize(Handle<Code> code,

               RelocInfo::Mode rmode = RelocInfo::CODE_TARGET,

               TypeFeedbackId ast_id = TypeFeedbackId::None(),

               COND_ARGS);

  void Call(Handle<Code> code,

            RelocInfo::Mode rmode = RelocInfo::CODE_TARGET,

            TypeFeedbackId ast_id = TypeFeedbackId::None(),

            COND_ARGS);

  void Ret(COND_ARGS);

  inline void Ret(BranchDelaySlot bd, Condition cond = al,

    Register rs = zero_reg, const Operand& rt = Operand(zero_reg)) {

    Ret(cond, rs, rt, bd);

  }

  void Branch(Label* L,

              Condition cond,

              Register rs,

              Heap::RootListIndex index,

              BranchDelaySlot bdslot = PROTECT);

#undef COND_ARGS

  // Emit code to discard a non-negative number of pointer-sized elements

  // from the stack, clobbering only the sp register.

  void Drop(int count,

            Condition cond = cc_always,

            Register reg = no_reg,

            const Operand& op = Operand(no_reg));

  // Trivial case of DropAndRet that utilizes the delay slot and only emits

  // 2 instructions.

  void DropAndRet(int drop);

  void DropAndRet(int drop,

                  Condition cond,

                  Register reg,

                  const Operand& op);

  // Swap two registers.  If the scratch register is omitted then a slightly

  // less efficient form using xor instead of mov is emitted.

  void Swap(Register reg1, Register reg2, Register scratch = no_reg);

  void Call(Label* target);

  inline void Move(Register dst, Register src) {

    if (!dst.is(src)) {

      mov(dst, src);

    }

  }

  inline void Move(FPURegister dst, FPURegister src) {

    if (!dst.is(src)) {

      mov_d(dst, src);

    }

  }

  inline void Move(Register dst_low, Register dst_high, FPURegister src) {

    mfc1(dst_low, src);

    mfc1(dst_high, FPURegister::from_code(src.code() + 1));

  }

  inline void FmoveHigh(Register dst_high, FPURegister src) {

    mfc1(dst_high, FPURegister::from_code(src.code() + 1));

  }

  inline void FmoveLow(Register dst_low, FPURegister src) {

    mfc1(dst_low, src);

  }

  inline void Move(FPURegister dst, Register src_low, Register src_high) {

    mtc1(src_low, dst);

    mtc1(src_high, FPURegister::from_code(dst.code() + 1));

  }

  // Conditional move.

  void Move(FPURegister dst, double imm);

  void Movz(Register rd, Register rs, Register rt);

  void Movn(Register rd, Register rs, Register rt);

  void Movt(Register rd, Register rs, uint16_t cc = 0);

  void Movf(Register rd, Register rs, uint16_t cc = 0);

  void Clz(Register rd, Register rs);

  // Jump unconditionally to given label.

  // We NEED a nop in the branch delay slot, as it used by v8, for example in

  // CodeGenerator::ProcessDeferred().

  // Currently the branch delay slot is filled by the MacroAssembler.

  // Use rather b(Label) for code generation.

  void jmp(Label* L) {

    Branch(L);

  }

  // Load an object from the root table.

  void LoadRoot(Register destination,

                Heap::RootListIndex index);

  void LoadRoot(Register destination,

                Heap::RootListIndex index,

                Condition cond, Register src1, const Operand& src2);

  // Store an object to the root table.

  void StoreRoot(Register source,

                 Heap::RootListIndex index);

  void StoreRoot(Register source,

                 Heap::RootListIndex index,

                 Condition cond, Register src1, const Operand& src2);

  void LoadHeapObject(Register dst, Handle<HeapObject> object);

  void LoadObject(Register result, Handle<Object> object) {

    AllowDeferredHandleDereference heap_object_check;

    if (object->IsHeapObject()) {

      LoadHeapObject(result, Handle<HeapObject>::cast(object));

    } else {

      li(result, object);

    }

  }

  // ---------------------------------------------------------------------------

  // GC Support

  void IncrementalMarkingRecordWriteHelper(Register object,

                                           Register value,

                                           Register address);

  enum RememberedSetFinalAction {

    kReturnAtEnd,

    kFallThroughAtEnd

  };

  // Record in the remembered set the fact that we have a pointer to new space

  // at the address pointed to by the addr register.  Only works if addr is not

  // in new space.

  void RememberedSetHelper(Register object,  // Used for debug code.

                           Register addr,

                           Register scratch,

                           SaveFPRegsMode save_fp,

                           RememberedSetFinalAction and_then);

  void CheckPageFlag(Register object,

                     Register scratch,

                     int mask,

                     Condition cc,

                     Label* condition_met);

  void CheckMapDeprecated(Handle<Map> map,

                          Register scratch,

                          Label* if_deprecated);

  // Check if object is in new space.  Jumps if the object is not in new space.

  // The register scratch can be object itself, but it will be clobbered.

  void JumpIfNotInNewSpace(Register object,

                           Register scratch,

                           Label* branch) {

    InNewSpace(object, scratch, ne, branch);

  }

  // Check if object is in new space.  Jumps if the object is in new space.

  // The register scratch can be object itself, but scratch will be clobbered.

  void JumpIfInNewSpace(Register object,

                        Register scratch,

                        Label* branch) {

    InNewSpace(object, scratch, eq, branch);

  }

  // Check if an object has a given incremental marking color.

  void HasColor(Register object,

                Register scratch0,

                Register scratch1,

                Label* has_color,

                int first_bit,

                int second_bit);

  void JumpIfBlack(Register object,

                   Register scratch0,

                   Register scratch1,

                   Label* on_black);

  // Checks the color of an object.  If the object is already grey or black

  // then we just fall through, since it is already live.  If it is white and

  // we can determine that it doesn't need to be scanned, then we just mark it

  // black and fall through.  For the rest we jump to the label so the

  // incremental marker can fix its assumptions.

  void EnsureNotWhite(Register object,

                      Register scratch1,

                      Register scratch2,

                      Register scratch3,

                      Label* object_is_white_and_not_data);

  // Detects conservatively whether an object is data-only, i.e. it does need to

  // be scanned by the garbage collector.

  void JumpIfDataObject(Register value,

                        Register scratch,

                        Label* not_data_object);

  // Notify the garbage collector that we wrote a pointer into an object.

  // |object| is the object being stored into, |value| is the object being

  // stored.  value and scratch registers are clobbered by the operation.

  // The offset is the offset from the start of the object, not the offset from

  // the tagged HeapObject pointer.  For use with FieldOperand(reg, off).

  void RecordWriteField(

      Register object,

      int offset,

      Register value,

      Register scratch,

      RAStatus ra_status,

      SaveFPRegsMode save_fp,

      RememberedSetAction remembered_set_action = EMIT_REMEMBERED_SET,

      SmiCheck smi_check = INLINE_SMI_CHECK);

  // As above, but the offset has the tag presubtracted.  For use with

  // MemOperand(reg, off).

  inline void RecordWriteContextSlot(

      Register context,

      int offset,

      Register value,

      Register scratch,

      RAStatus ra_status,

      SaveFPRegsMode save_fp,

      RememberedSetAction remembered_set_action = EMIT_REMEMBERED_SET,

      SmiCheck smi_check = INLINE_SMI_CHECK) {

    RecordWriteField(context,

                     offset + kHeapObjectTag,

                     value,

                     scratch,

                     ra_status,

                     save_fp,

                     remembered_set_action,

                     smi_check);

  }

  // For a given |object| notify the garbage collector that the slot |address|

  // has been written.  |value| is the object being stored. The value and

  // address registers are clobbered by the operation.

  void RecordWrite(

      Register object,

      Register address,

      Register value,

      RAStatus ra_status,

      SaveFPRegsMode save_fp,

      RememberedSetAction remembered_set_action = EMIT_REMEMBERED_SET,

      SmiCheck smi_check = INLINE_SMI_CHECK);

  // ---------------------------------------------------------------------------

  // Inline caching support.

  // Generate code for checking access rights - used for security checks

  // on access to global objects across environments. The holder register

  // is left untouched, whereas both scratch registers are clobbered.

  void CheckAccessGlobalProxy(Register holder_reg,

                              Register scratch,

                              Label* miss);

  void GetNumberHash(Register reg0, Register scratch);

  void LoadFromNumberDictionary(Label* miss,

                                Register elements,

                                Register key,

                                Register result,

                                Register reg0,

                                Register reg1,

                                Register reg2);

  inline void MarkCode(NopMarkerTypes type) {

    nop(type);

  }

  // Check if the given instruction is a 'type' marker.

  // i.e. check if it is a sll zero_reg, zero_reg, <type> (referenced as

  // nop(type)). These instructions are generated to mark special location in

  // the code, like some special IC code.

  static inline bool IsMarkedCode(Instr instr, int type) {

    ASSERT((FIRST_IC_MARKER <= type) && (type < LAST_CODE_MARKER));

    return IsNop(instr, type);

  }

  static inline int GetCodeMarker(Instr instr) {

    uint32_t opcode = ((instr & kOpcodeMask));

    uint32_t rt = ((instr & kRtFieldMask) >> kRtShift);

    uint32_t rs = ((instr & kRsFieldMask) >> kRsShift);

    uint32_t sa = ((instr & kSaFieldMask) >> kSaShift);

    // Return <n> if we have a sll zero_reg, zero_reg, n

    // else return -1.

    bool sllzz = (opcode == SLL &&

                  rt == static_cast<uint32_t>(ToNumber(zero_reg)) &&

                  rs == static_cast<uint32_t>(ToNumber(zero_reg)));

    int type =

        (sllzz && FIRST_IC_MARKER <= sa && sa < LAST_CODE_MARKER) ? sa : -1;

    ASSERT((type == -1) ||

           ((FIRST_IC_MARKER <= type) && (type < LAST_CODE_MARKER)));

    return type;

  }

  // ---------------------------------------------------------------------------

  // Allocation support.

  // Allocate an object in new space or old pointer space. The object_size is

  // specified either in bytes or in words if the allocation flag SIZE_IN_WORDS

  // is passed. If the space is exhausted control continues at the gc_required

  // label. The allocated object is returned in result. If the flag

  // tag_allocated_object is true the result is tagged as as a heap object.

  // All registers are clobbered also when control continues at the gc_required

  // label.

  void Allocate(int object_size,

                Register result,

                Register scratch1,

                Register scratch2,

                Label* gc_required,

                AllocationFlags flags);

  void Allocate(Register object_size,

                Register result,

                Register scratch1,

                Register scratch2,

                Label* gc_required,

                AllocationFlags flags);

  // Undo allocation in new space. The object passed and objects allocated after

  // it will no longer be allocated. The caller must make sure that no pointers

  // are left to the object(s) no longer allocated as they would be invalid when

  // allocation is undone.

  void UndoAllocationInNewSpace(Register object, Register scratch);

  void AllocateTwoByteString(Register result,

                             Register length,

                             Register scratch1,

                             Register scratch2,

                             Register scratch3,

                             Label* gc_required);

  void AllocateAsciiString(Register result,

                           Register length,

                           Register scratch1,

                           Register scratch2,

                           Register scratch3,

                           Label* gc_required);

  void AllocateTwoByteConsString(Register result,

                                 Register length,

                                 Register scratch1,

                                 Register scratch2,

                                 Label* gc_required);

  void AllocateAsciiConsString(Register result,

                               Register length,

                               Register scratch1,

                               Register scratch2,

                               Label* gc_required);

  void AllocateTwoByteSlicedString(Register result,

                                   Register length,

                                   Register scratch1,

                                   Register scratch2,

                                   Label* gc_required);

  void AllocateAsciiSlicedString(Register result,

                                 Register length,

                                 Register scratch1,

                                 Register scratch2,

                                 Label* gc_required);

  // Allocates a heap number or jumps to the gc_required label if the young

  // space is full and a scavenge is needed. All registers are clobbered also

  // when control continues at the gc_required label.

  void AllocateHeapNumber(Register result,

                          Register scratch1,

                          Register scratch2,

                          Register heap_number_map,

                          Label* gc_required,

                          TaggingMode tagging_mode = TAG_RESULT);

  void AllocateHeapNumberWithValue(Register result,

                                   FPURegister value,

                                   Register scratch1,

                                   Register scratch2,

                                   Label* gc_required);

  // ---------------------------------------------------------------------------

  // Instruction macros.

#define DEFINE_INSTRUCTION(instr)                                              \

  void instr(Register rd, Register rs, const Operand& rt);                     \

  void instr(Register rd, Register rs, Register rt) {                          \

    instr(rd, rs, Operand(rt));                                                \

  }                                                                            \

  void instr(Register rs, Register rt, int32_t j) {                            \

    instr(rs, rt, Operand(j));                                                 \

  }

#define DEFINE_INSTRUCTION2(instr)                                             \

  void instr(Register rs, const Operand& rt);                                  \

  void instr(Register rs, Register rt) {                                       \

    instr(rs, Operand(rt));                                                    \

  }                                                                            \

  void instr(Register rs, int32_t j) {                                         \

    instr(rs, Operand(j));                                                     \

  }

  DEFINE_INSTRUCTION(Addu);

  DEFINE_INSTRUCTION(Subu);

  DEFINE_INSTRUCTION(Mul);

  DEFINE_INSTRUCTION2(Mult);

  DEFINE_INSTRUCTION2(Multu);

  DEFINE_INSTRUCTION2(Div);

  DEFINE_INSTRUCTION2(Divu);

  DEFINE_INSTRUCTION(And);

  DEFINE_INSTRUCTION(Or);

  DEFINE_INSTRUCTION(Xor);

  DEFINE_INSTRUCTION(Nor);

  DEFINE_INSTRUCTION2(Neg);

  DEFINE_INSTRUCTION(Slt);

  DEFINE_INSTRUCTION(Sltu);

  // MIPS32 R2 instruction macro.

  DEFINE_INSTRUCTION(Ror);

#undef DEFINE_INSTRUCTION

#undef DEFINE_INSTRUCTION2

  // ---------------------------------------------------------------------------

  // Pseudo-instructions.

  void mov(Register rd, Register rt) { or_(rd, rt, zero_reg); }

  // Load int32 in the rd register.

  void li(Register rd, Operand j, LiFlags mode = OPTIMIZE_SIZE);

  inline void li(Register rd, int32_t j, LiFlags mode = OPTIMIZE_SIZE) {

    li(rd, Operand(j), mode);

  }

  inline void li(Register dst, Handle<Object> value,

                 LiFlags mode = OPTIMIZE_SIZE) {

    li(dst, Operand(value), mode);

  }

  // Push multiple registers on the stack.

  // Registers are saved in numerical order, with higher numbered registers

  // saved in higher memory addresses.

  void MultiPush(RegList regs);

  void MultiPushReversed(RegList regs);

  void MultiPushFPU(RegList regs);

  void MultiPushReversedFPU(RegList regs);

  void push(Register src) {

    Addu(sp, sp, Operand(-kPointerSize));

    sw(src, MemOperand(sp, 0));

  }

  void Push(Register src) { push(src); }

  // Push a handle.

  void Push(Handle<Object> handle);

  void Push(Smi* smi) { Push(Handle<Smi>(smi, isolate())); }

  // Push two registers. Pushes leftmost register first (to highest address).

  void Push(Register src1, Register src2) {

    Subu(sp, sp, Operand(2 * kPointerSize));

    sw(src1, MemOperand(sp, 1 * kPointerSize));

    sw(src2, MemOperand(sp, 0 * kPointerSize));

  }

  // Push three registers. Pushes leftmost register first (to highest address).

  void Push(Register src1, Register src2, Register src3) {

    Subu(sp, sp, Operand(3 * kPointerSize));

    sw(src1, MemOperand(sp, 2 * kPointerSize));

    sw(src2, MemOperand(sp, 1 * kPointerSize));

    sw(src3, MemOperand(sp, 0 * kPointerSize));

  }

  // Push four registers. Pushes leftmost register first (to highest address).

  void Push(Register src1, Register src2, Register src3, Register src4) {

    Subu(sp, sp, Operand(4 * kPointerSize));

    sw(src1, MemOperand(sp, 3 * kPointerSize));

    sw(src2, MemOperand(sp, 2 * kPointerSize));

    sw(src3, MemOperand(sp, 1 * kPointerSize));

    sw(src4, MemOperand(sp, 0 * kPointerSize));

  }

  void Push(Register src, Condition cond, Register tst1, Register tst2) {

    // Since we don't have conditional execution we use a Branch.

    Branch(3, cond, tst1, Operand(tst2));

    Subu(sp, sp, Operand(kPointerSize));

    sw(src, MemOperand(sp, 0));

  }

  // Pops multiple values from the stack and load them in the

  // registers specified in regs. Pop order is the opposite as in MultiPush.

  void MultiPop(RegList regs);

  void MultiPopReversed(RegList regs);

  void MultiPopFPU(RegList regs);

  void MultiPopReversedFPU(RegList regs);

  void pop(Register dst) {

    lw(dst, MemOperand(sp, 0));

    Addu(sp, sp, Operand(kPointerSize));

  }

  void Pop(Register dst) { pop(dst); }

  // Pop two registers. Pops rightmost register first (from lower address).

  void Pop(Register src1, Register src2) {

    ASSERT(!src1.is(src2));

    lw(src2, MemOperand(sp, 0 * kPointerSize));

    lw(src1, MemOperand(sp, 1 * kPointerSize));

    Addu(sp, sp, 2 * kPointerSize);

  }

  // Pop three registers. Pops rightmost register first (from lower address).

  void Pop(Register src1, Register src2, Register src3) {

    lw(src3, MemOperand(sp, 0 * kPointerSize));

    lw(src2, MemOperand(sp, 1 * kPointerSize));

    lw(src1, MemOperand(sp, 2 * kPointerSize));

    Addu(sp, sp, 3 * kPointerSize);

  }

  void Pop(uint32_t count = 1) {

    Addu(sp, sp, Operand(count * kPointerSize));

  }

  // Push and pop the registers that can hold pointers, as defined by the

  // RegList constant kSafepointSavedRegisters.

  void PushSafepointRegisters();

  void PopSafepointRegisters();

  void PushSafepointRegistersAndDoubles();

  void PopSafepointRegistersAndDoubles();

  // Store value in register src in the safepoint stack slot for

  // register dst.

  void StoreToSafepointRegisterSlot(Register src, Register dst);

  void StoreToSafepointRegistersAndDoublesSlot(Register src, Register dst);

  // Load the value of the src register from its safepoint stack slot

  // into register dst.

  void LoadFromSafepointRegisterSlot(Register dst, Register src);

  // Flush the I-cache from asm code. You should use CPU::FlushICache from C.

  // Does not handle errors.

  void FlushICache(Register address, unsigned instructions);

  // MIPS32 R2 instruction macro.

  void Ins(Register rt, Register rs, uint16_t pos, uint16_t size);

  void Ext(Register rt, Register rs, uint16_t pos, uint16_t size);

  // ---------------------------------------------------------------------------

  // FPU macros. These do not handle special cases like NaN or +- inf.

  // Convert unsigned word to double.

  void Cvt_d_uw(FPURegister fd, FPURegister fs, FPURegister scratch);

  void Cvt_d_uw(FPURegister fd, Register rs, FPURegister scratch);

  // Convert double to unsigned word.

  void Trunc_uw_d(FPURegister fd, FPURegister fs, FPURegister scratch);

  void Trunc_uw_d(FPURegister fd, Register rs, FPURegister scratch);

  void Trunc_w_d(FPURegister fd, FPURegister fs);

  void Round_w_d(FPURegister fd, FPURegister fs);

  void Floor_w_d(FPURegister fd, FPURegister fs);

  void Ceil_w_d(FPURegister fd, FPURegister fs);

  // Wrapper function for the different cmp/branch types.

  void BranchF(Label* target,

               Label* nan,

               Condition cc,

               FPURegister cmp1,

               FPURegister cmp2,

               BranchDelaySlot bd = PROTECT);

  // Alternate (inline) version for better readability with USE_DELAY_SLOT.

  inline void BranchF(BranchDelaySlot bd,

                      Label* target,

                      Label* nan,

                      Condition cc,

                      FPURegister cmp1,

                      FPURegister cmp2) {

    BranchF(target, nan, cc, cmp1, cmp2, bd);

  };

  // Truncates a double using a specific rounding mode, and writes the value

  // to the result register.

  // The except_flag will contain any exceptions caused by the instruction.

  // If check_inexact is kDontCheckForInexactConversion, then the inexact

  // exception is masked.

  void EmitFPUTruncate(FPURoundingMode rounding_mode,

                       Register result,

                       DoubleRegister double_input,

                       Register scratch,

                       DoubleRegister double_scratch,

                       Register except_flag,

                       CheckForInexactConversion check_inexact

                           = kDontCheckForInexactConversion);

  // Performs a truncating conversion of a floating point number as used by

  // the JS bitwise operations. See ECMA-262 9.5: ToInt32. Goes to 'done' if it

  // succeeds, otherwise falls through if result is saturated. On return

  // 'result' either holds answer, or is clobbered on fall through.

  //

  // Only public for the test code in test-code-stubs-arm.cc.

  void TryInlineTruncateDoubleToI(Register result,

                                  DoubleRegister input,

                                  Label* done);

  // Performs a truncating conversion of a floating point number as used by

  // the JS bitwise operations. See ECMA-262 9.5: ToInt32.

  // Exits with 'result' holding the answer.

  void TruncateDoubleToI(Register result, DoubleRegister double_input);

  // Performs a truncating conversion of a heap number as used by

  // the JS bitwise operations. See ECMA-262 9.5: ToInt32. 'result' and 'input'

  // must be different registers. Exits with 'result' holding the answer.

  void TruncateHeapNumberToI(Register result, Register object);

  // Converts the smi or heap number in object to an int32 using the rules

  // for ToInt32 as described in ECMAScript 9.5.: the value is truncated

  // and brought into the range -2^31 .. +2^31 - 1. 'result' and 'input' must be

  // different registers.

  void TruncateNumberToI(Register object,

                         Register result,

                         Register heap_number_map,

                         Register scratch,

                         Label* not_int32);

  // Loads the number from object into dst register.

  // If |object| is neither smi nor heap number, |not_number| is jumped to

  // with |object| still intact.

  void LoadNumber(Register object,

                  FPURegister dst,

                  Register heap_number_map,

                  Register scratch,

                  Label* not_number);

  // Loads the number from object into double_dst in the double format.

  // Control will jump to not_int32 if the value cannot be exactly represented

  // by a 32-bit integer.

  // Floating point value in the 32-bit integer range that are not exact integer

  // won't be loaded.

  void LoadNumberAsInt32Double(Register object,

                               DoubleRegister double_dst,

                               Register heap_number_map,

                               Register scratch1,

                               Register scratch2,

                               FPURegister double_scratch,

                               Label* not_int32);

  // Loads the number from object into dst as a 32-bit integer.

  // Control will jump to not_int32 if the object cannot be exactly represented

  // by a 32-bit integer.

  // Floating point value in the 32-bit integer range that are not exact integer

  // won't be converted.

  void LoadNumberAsInt32(Register object,

                         Register dst,

                         Register heap_number_map,

                         Register scratch1,

                         Register scratch2,

                         FPURegister double_scratch0,

                         FPURegister double_scratch1,

                         Label* not_int32);

  // Enter exit frame.

  // argc - argument count to be dropped by LeaveExitFrame.

  // save_doubles - saves FPU registers on stack, currently disabled.

  // stack_space - extra stack space.

  void EnterExitFrame(bool save_doubles,

                      int stack_space = 0);

  // Leave the current exit frame.

  void LeaveExitFrame(bool save_doubles,

                      Register arg_count,

                      bool restore_context,

                      bool do_return = NO_EMIT_RETURN);

  // Get the actual activation frame alignment for target environment.

  static int ActivationFrameAlignment();

  // Make sure the stack is aligned. Only emits code in debug mode.

  void AssertStackIsAligned();

  void LoadContext(Register dst, int context_chain_length);

  // Conditionally load the cached Array transitioned map of type

  // transitioned_kind from the native context if the map in register

  // map_in_out is the cached Array map in the native context of

  // expected_kind.

  void LoadTransitionedArrayMapConditional(

      ElementsKind expected_kind,

      ElementsKind transitioned_kind,

      Register map_in_out,

      Register scratch,

      Label* no_map_match);

  // Load the initial map for new Arrays from a JSFunction.

  void LoadInitialArrayMap(Register function_in,

                           Register scratch,

                           Register map_out,

                           bool can_have_holes);

  void LoadGlobalFunction(int index, Register function);

  void LoadArrayFunction(Register function);

  // Load the initial map from the global function. The registers

  // function and map can be the same, function is then overwritten.

  void LoadGlobalFunctionInitialMap(Register function,

                                    Register map,

                                    Register scratch);

  void InitializeRootRegister() {

    ExternalReference roots_array_start =

        ExternalReference::roots_array_start(isolate());

    li(kRootRegister, Operand(roots_array_start));

  }

  // -------------------------------------------------------------------------

  // JavaScript invokes.

  // Set up call kind marking in t1. The method takes t1 as an

  // explicit first parameter to make the code more readable at the

  // call sites.

  void SetCallKind(Register dst, CallKind kind);

  // Invoke the JavaScript function code by either calling or jumping.

  void InvokeCode(Register code,

                  const ParameterCount& expected,

                  const ParameterCount& actual,

                  InvokeFlag flag,

                  const CallWrapper& call_wrapper,

                  CallKind call_kind);

  void InvokeCode(Handle<Code> code,

                  const ParameterCount& expected,

                  const ParameterCount& actual,

                  RelocInfo::Mode rmode,

                  InvokeFlag flag,

                  CallKind call_kind);

  // Invoke the JavaScript function in the given register. Changes the

  // current context to the context in the function before invoking.

  void InvokeFunction(Register function,

                      const ParameterCount& actual,

                      InvokeFlag flag,

                      const CallWrapper& call_wrapper,

                      CallKind call_kind);

  void InvokeFunction(Handle<JSFunction> function,

                      const ParameterCount& expected,

                      const ParameterCount& actual,

                      InvokeFlag flag,

                      const CallWrapper& call_wrapper,

                      CallKind call_kind);

  void IsObjectJSObjectType(Register heap_object,

                            Register map,

                            Register scratch,

                            Label* fail);

  void IsInstanceJSObjectType(Register map,

                              Register scratch,

                              Label* fail);

  void IsObjectJSStringType(Register object,

                            Register scratch,

                            Label* fail);

  void IsObjectNameType(Register object,

                        Register scratch,

                        Label* fail);

#ifdef ENABLE_DEBUGGER_SUPPORT

  // -------------------------------------------------------------------------

  // Debugger Support.

  void DebugBreak();

#endif

  // -------------------------------------------------------------------------

  // Exception handling.

  // Push a new try handler and link into try handler chain.

  void PushTryHandler(StackHandler::Kind kind, int handler_index);

  // Unlink the stack handler on top of the stack from the try handler chain.

  // Must preserve the result register.

  void PopTryHandler();

  // Passes thrown value to the handler of top of the try handler chain.

  void Throw(Register value);

  // Propagates an uncatchable exception to the top of the current JS stack's

  // handler chain.

  void ThrowUncatchable(Register value);

  // Copies a fixed number of fields of heap objects from src to dst.

  void CopyFields(Register dst, Register src, RegList temps, int field_count);

  // Copies a number of bytes from src to dst. All registers are clobbered. On

  // exit src and dst will point to the place just after where the last byte was

  // read or written and length will be zero.

  void CopyBytes(Register src,

                 Register dst,

                 Register length,

                 Register scratch);

  // Initialize fields with filler values.  Fields starting at |start_offset|

  // not including end_offset are overwritten with the value in |filler|.  At

  // the end the loop, |start_offset| takes the value of |end_offset|.

  void InitializeFieldsWithFiller(Register start_offset,

                                  Register end_offset,

                                  Register filler);

  // -------------------------------------------------------------------------

  // Support functions.

  // Try to get function prototype of a function and puts the value in

  // the result register. Checks that the function really is a

  // function and jumps to the miss label if the fast checks fail. The

  // function register will be untouched; the other registers may be

  // clobbered.

  void TryGetFunctionPrototype(Register function,

                               Register result,

                               Register scratch,

                               Label* miss,

                               bool miss_on_bound_function = false);

  void GetObjectType(Register function,

                     Register map,

                     Register type_reg);

  // Check if a map for a JSObject indicates that the object has fast elements.

  // Jump to the specified label if it does not.

  void CheckFastElements(Register map,

                         Register scratch,

                         Label* fail);

  // Check if a map for a JSObject indicates that the object can have both smi

  // and HeapObject elements.  Jump to the specified label if it does not.

  void CheckFastObjectElements(Register map,

                               Register scratch,

                               Label* fail);

  // Check if a map for a JSObject indicates that the object has fast smi only

  // elements.  Jump to the specified label if it does not.

  void CheckFastSmiElements(Register map,

                            Register scratch,

                            Label* fail);

  // Check to see if maybe_number can be stored as a double in

  // FastDoubleElements. If it can, store it at the index specified by key in

  // the FastDoubleElements array elements. Otherwise jump to fail.

  void StoreNumberToDoubleElements(Register value_reg,

                                   Register key_reg,

                                   Register elements_reg,

                                   Register scratch1,

                                   Register scratch2,

                                   Register scratch3,

                                   Label* fail,

                                   int elements_offset = 0);

  // Compare an object's map with the specified map and its transitioned

  // elements maps if mode is ALLOW_ELEMENT_TRANSITION_MAPS. Jumps to

  // "branch_to" if the result of the comparison is "cond". If multiple map

  // compares are required, the compare sequences branches to early_success.

  void CompareMapAndBranch(Register obj,

                           Register scratch,

                           Handle<Map> map,

                           Label* early_success,

                           Condition cond,

                           Label* branch_to);

  // As above, but the map of the object is already loaded into the register

  // which is preserved by the code generated.

  void CompareMapAndBranch(Register obj_map,

                           Handle<Map> map,

                           Label* early_success,

                           Condition cond,

                           Label* branch_to);

  // Check if the map of an object is equal to a specified map and branch to

  // label if not. Skip the smi check if not required (object is known to be a

  // heap object). If mode is ALLOW_ELEMENT_TRANSITION_MAPS, then also match

  // against maps that are ElementsKind transition maps of the specificed map.

  void CheckMap(Register obj,

                Register scratch,

                Handle<Map> map,

                Label* fail,

                SmiCheckType smi_check_type);

  void CheckMap(Register obj,

                Register scratch,

                Heap::RootListIndex index,

                Label* fail,

                SmiCheckType smi_check_type);

  // Check if the map of an object is equal to a specified map and branch to a

  // specified target if equal. Skip the smi check if not required (object is

  // known to be a heap object)

  void DispatchMap(Register obj,

                   Register scratch,

                   Handle<Map> map,

                   Handle<Code> success,

                   SmiCheckType smi_check_type);

  // Generates code for reporting that an illegal operation has

  // occurred.

  void IllegalOperation(int num_arguments);

  // Load and check the instance type of an object for being a string.

  // Loads the type into the second argument register.

  // Returns a condition that will be enabled if the object was a string.

  Condition IsObjectStringType(Register obj,

                               Register type,

                               Register result) {

    lw(type, FieldMemOperand(obj, HeapObject::kMapOffset));

    lbu(type, FieldMemOperand(type, Map::kInstanceTypeOffset));

    And(type, type, Operand(kIsNotStringMask));

    ASSERT_EQ(0, kStringTag);

    return eq;

  }

  // Picks out an array index from the hash field.

  // Register use:

  //   hash - holds the index's hash. Clobbered.

  //   index - holds the overwritten index on exit.

  void IndexFromHash(Register hash, Register index);

  // Get the number of least significant bits from a register.

  void GetLeastBitsFromSmi(Register dst, Register src, int num_least_bits);

  void GetLeastBitsFromInt32(Register dst, Register src, int mun_least_bits);

  // Load the value of a number object into a FPU double register. If the

  // object is not a number a jump to the label not_number is performed

  // and the FPU double register is unchanged.

  void ObjectToDoubleFPURegister(

      Register object,

      FPURegister value,

      Register scratch1,

      Register scratch2,

      Register heap_number_map,

      Label* not_number,

      ObjectToDoubleFlags flags = NO_OBJECT_TO_DOUBLE_FLAGS);

  // Load the value of a smi object into a FPU double register. The register

  // scratch1 can be the same register as smi in which case smi will hold the

  // untagged value afterwards.

  void SmiToDoubleFPURegister(Register smi,

                              FPURegister value,

                              Register scratch1);

  // -------------------------------------------------------------------------

  // Overflow handling functions.

  // Usage: first call the appropriate arithmetic function, then call one of the

  // jump functions with the overflow_dst register as the second parameter.

  void AdduAndCheckForOverflow(Register dst,

                               Register left,

                               Register right,

                               Register overflow_dst,

                               Register scratch = at);

  void SubuAndCheckForOverflow(Register dst,

                               Register left,

                               Register right,

                               Register overflow_dst,

                               Register scratch = at);

  void BranchOnOverflow(Label* label,

                        Register overflow_check,

                        BranchDelaySlot bd = PROTECT) {

    Branch(label, lt, overflow_check, Operand(zero_reg), bd);

  }

  void BranchOnNoOverflow(Label* label,

                          Register overflow_check,

                          BranchDelaySlot bd = PROTECT) {

    Branch(label, ge, overflow_check, Operand(zero_reg), bd);

  }

  void RetOnOverflow(Register overflow_check, BranchDelaySlot bd = PROTECT) {

    Ret(lt, overflow_check, Operand(zero_reg), bd);

  }

  void RetOnNoOverflow(Register overflow_check, BranchDelaySlot bd = PROTECT) {

    Ret(ge, overflow_check, Operand(zero_reg), bd);

  }

  // -------------------------------------------------------------------------

  // Runtime calls.

  // See comments at the beginning of CEntryStub::Generate.

  inline void PrepareCEntryArgs(int num_args) {

    li(s0, num_args);

    li(s1, (num_args - 1) * kPointerSize);

  }

  inline void PrepareCEntryFunction(const ExternalReference& ref) {

    li(s2, Operand(ref));

  }

  // Call a code stub.

  void CallStub(CodeStub* stub,

                TypeFeedbackId ast_id = TypeFeedbackId::None(),

                Condition cond = cc_always,

                Register r1 = zero_reg,

                const Operand& r2 = Operand(zero_reg),

                BranchDelaySlot bd = PROTECT);

  // Tail call a code stub (jump).

  void TailCallStub(CodeStub* stub);

  void CallJSExitStub(CodeStub* stub);

  // Call a runtime routine.

  void CallRuntime(const Runtime::Function* f,

                   int num_arguments,

                   SaveFPRegsMode save_doubles = kDontSaveFPRegs);

  void CallRuntimeSaveDoubles(Runtime::FunctionId id) {

    const Runtime::Function* function = Runtime::FunctionForId(id);

    CallRuntime(function, function->nargs, kSaveFPRegs);

  }

  // Convenience function: Same as above, but takes the fid instead.

  void CallRuntime(Runtime::FunctionId id, int num_arguments) {

    CallRuntime(Runtime::FunctionForId(id), num_arguments);

  }

  // Convenience function: call an external reference.

  void CallExternalReference(const ExternalReference& ext,

                             int num_arguments,

                             BranchDelaySlot bd = PROTECT);

  // Tail call of a runtime routine (jump).

  // Like JumpToExternalReference, but also takes care of passing the number

  // of parameters.

  void TailCallExternalReference(const ExternalReference& ext,

                                 int num_arguments,

                                 int result_size);

  // Convenience function: tail call a runtime routine (jump).

  void TailCallRuntime(Runtime::FunctionId fid,

                       int num_arguments,

                       int result_size);

  int CalculateStackPassedWords(int num_reg_arguments,

                                int num_double_arguments);

  // Before calling a C-function from generated code, align arguments on stack

  // and add space for the four mips argument slots.

  // After aligning the frame, non-register arguments must be stored on the

  // stack, after the argument-slots using helper: CFunctionArgumentOperand().

  // The argument count assumes all arguments are word sized.

  // Some compilers/platforms require the stack to be aligned when calling

  // C++ code.

  // Needs a scratch register to do some arithmetic. This register will be

  // trashed.

  void PrepareCallCFunction(int num_reg_arguments,

                            int num_double_registers,

                            Register scratch);

  void PrepareCallCFunction(int num_reg_arguments,

                            Register scratch);

  // Arguments 1-4 are placed in registers a0 thru a3 respectively.

  // Arguments 5..n are stored to stack using following:

  //  sw(t0, CFunctionArgumentOperand(5));

  // Calls a C function and cleans up the space for arguments allocated

  // by PrepareCallCFunction. The called function is not allowed to trigger a

  // garbage collection, since that might move the code and invalidate the

  // return address (unless this is somehow accounted for by the called

  // function).

  void CallCFunction(ExternalReference function, int num_arguments);

  void CallCFunction(Register function, int num_arguments);

  void CallCFunction(ExternalReference function,

                     int num_reg_arguments,

                     int num_double_arguments);

  void CallCFunction(Register function,

                     int num_reg_arguments,

                     int num_double_arguments);

  void GetCFunctionDoubleResult(const DoubleRegister dst);

  // There are two ways of passing double arguments on MIPS, depending on

  // whether soft or hard floating point ABI is used. These functions

  // abstract parameter passing for the three different ways we call

  // C functions from generated code.

  void SetCallCDoubleArguments(DoubleRegister dreg);

  void SetCallCDoubleArguments(DoubleRegister dreg1, DoubleRegister dreg2);

  void SetCallCDoubleArguments(DoubleRegister dreg, Register reg);

  // Calls an API function.  Allocates HandleScope, extracts returned value

  // from handle and propagates exceptions.  Restores context.  stack_space

  // - space to be unwound on exit (includes the call JS arguments space and

  // the additional space allocated for the fast call).

  void CallApiFunctionAndReturn(ExternalReference function,

                                Address function_address,

                                ExternalReference thunk_ref,

                                Register thunk_last_arg,

                                int stack_space,

                                MemOperand return_value_operand,

                                MemOperand* context_restore_operand);

  // Jump to the builtin routine.

  void JumpToExternalReference(const ExternalReference& builtin,

                               BranchDelaySlot bd = PROTECT);

  // Invoke specified builtin JavaScript function. Adds an entry to

  // the unresolved list if the name does not resolve.

  void InvokeBuiltin(Builtins::JavaScript id,

                     InvokeFlag flag,

                     const CallWrapper& call_wrapper = NullCallWrapper());

  // Store the code object for the given builtin in the target register and

  // setup the function in a1.

  void GetBuiltinEntry(Register target, Builtins::JavaScript id);

  // Store the function for the given builtin in the target register.

  void GetBuiltinFunction(Register target, Builtins::JavaScript id);

  struct Unresolved {

    int pc;

    uint32_t flags;  // See Bootstrapper::FixupFlags decoders/encoders.

    const char* name;

  };

  Handle<Object> CodeObject() {

    ASSERT(!code_object_.is_null());

    return code_object_;

  }

  // -------------------------------------------------------------------------

  // StatsCounter support.

  void SetCounter(StatsCounter* counter, int value,

                  Register scratch1, Register scratch2);

  void IncrementCounter(StatsCounter* counter, int value,

                        Register scratch1, Register scratch2);

  void DecrementCounter(StatsCounter* counter, int value,

                        Register scratch1, Register scratch2);

  // -------------------------------------------------------------------------

  // Debugging.

  // Calls Abort(msg) if the condition cc is not satisfied.

  // Use --debug_code to enable.

  void Assert(Condition cc, BailoutReason reason, Register rs, Operand rt);

  void AssertFastElements(Register elements);

  // Like Assert(), but always enabled.

  void Check(Condition cc, BailoutReason reason, Register rs, Operand rt);

  // Print a message to stdout and abort execution.

  void Abort(BailoutReason msg);

  // Verify restrictions about code generated in stubs.

  void set_generating_stub(bool value) { generating_stub_ = value; }

  bool generating_stub() { return generating_stub_; }

  void set_allow_stub_calls(bool value) { allow_stub_calls_ = value; }

  bool allow_stub_calls() { return allow_stub_calls_; }

  void set_has_frame(bool value) { has_frame_ = value; }

  bool has_frame() { return has_frame_; }

  inline bool AllowThisStubCall(CodeStub* stub);

  // ---------------------------------------------------------------------------

  // Number utilities.

  // Check whether the value of reg is a power of two and not zero. If not

  // control continues at the label not_power_of_two. If reg is a power of two

  // the register scratch contains the value of (reg - 1) when control falls

  // through.

  void JumpIfNotPowerOfTwoOrZero(Register reg,

                                 Register scratch,

                                 Label* not_power_of_two_or_zero);

  // -------------------------------------------------------------------------

  // Smi utilities.

  void SmiTag(Register reg) {

    Addu(reg, reg, reg);

  }

  // Test for overflow < 0: use BranchOnOverflow() or BranchOnNoOverflow().

  void SmiTagCheckOverflow(Register reg, Register overflow);

  void SmiTagCheckOverflow(Register dst, Register src, Register overflow);

  void SmiTag(Register dst, Register src) {

    Addu(dst, src, src);

  }

  void SmiUntag(Register reg) {

    sra(reg, reg, kSmiTagSize);

  }

  void SmiUntag(Register dst, Register src) {

    sra(dst, src, kSmiTagSize);

  }

  // Untag the source value into destination and jump if source is a smi.

  // Souce and destination can be the same register.

  void UntagAndJumpIfSmi(Register dst, Register src, Label* smi_case);

  // Untag the source value into destination and jump if source is not a smi.

  // Souce and destination can be the same register.

  void UntagAndJumpIfNotSmi(Register dst, Register src, Label* non_smi_case);

  // Jump the register contains a smi.

  void JumpIfSmi(Register value,

                 Label* smi_label,

                 Register scratch = at,

                 BranchDelaySlot bd = PROTECT);

  // Jump if the register contains a non-smi.

  void JumpIfNotSmi(Register value,

                    Label* not_smi_label,

                    Register scratch = at,

                    BranchDelaySlot bd = PROTECT);

  // Jump if either of the registers contain a non-smi.

  void JumpIfNotBothSmi(Register reg1, Register reg2, Label* on_not_both_smi);

  // Jump if either of the registers contain a smi.

  void JumpIfEitherSmi(Register reg1, Register reg2, Label* on_either_smi);

  // Abort execution if argument is a smi, enabled via --debug-code.

  void AssertNotSmi(Register object);

  void AssertSmi(Register object);

  // Abort execution if argument is not a string, enabled via --debug-code.

  void AssertString(Register object);

  // Abort execution if argument is not a name, enabled via --debug-code.

  void AssertName(Register object);