src/mips/code-stubs-mips.h

// Copyright 2011 the V8 project authors. All rights reserved.
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// 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
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//       with the distribution.
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//       contributors may be used to endorse or promote products derived
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//
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#ifndef V8_MIPS_CODE_STUBS_ARM_H_
#define V8_MIPS_CODE_STUBS_ARM_H_

#include "ic-inl.h"


namespace v8 {
namespace internal {


void ArrayNativeCode(MacroAssembler* masm, Label* call_generic_code);


// Compute a transcendental math function natively, or call the
// TranscendentalCache runtime function.
class TranscendentalCacheStub: public PlatformCodeStub {
 public:
  enum ArgumentType {
    TAGGED = 0 << TranscendentalCache::kTranscendentalTypeBits,
    UNTAGGED = 1 << TranscendentalCache::kTranscendentalTypeBits
  };

  TranscendentalCacheStub(TranscendentalCache::Type type,
                          ArgumentType argument_type)
      : type_(type), argument_type_(argument_type) { }
  void Generate(MacroAssembler* masm);
 private:
  TranscendentalCache::Type type_;
  ArgumentType argument_type_;
  void GenerateCallCFunction(MacroAssembler* masm, Register scratch);

  Major MajorKey() { return TranscendentalCache; }
  int MinorKey() { return type_ | argument_type_; }
  Runtime::FunctionId RuntimeFunction();
};


class StoreBufferOverflowStub: public PlatformCodeStub {
 public:
  explicit StoreBufferOverflowStub(SaveFPRegsMode save_fp)
      : save_doubles_(save_fp) {}

  void Generate(MacroAssembler* masm);

  virtual bool IsPregenerated() { return true; }
  static void GenerateFixedRegStubsAheadOfTime(Isolate* isolate);
  virtual bool SometimesSetsUpAFrame() { return false; }

 private:
  SaveFPRegsMode save_doubles_;

  Major MajorKey() { return StoreBufferOverflow; }
  int MinorKey() { return (save_doubles_ == kSaveFPRegs) ? 1 : 0; }
};


class StringHelper : public AllStatic {
 public:
  // Generate code for copying characters using a simple loop. This should only
  // be used in places where the number of characters is small and the
  // additional setup and checking in GenerateCopyCharactersLong adds too much
  // overhead. Copying of overlapping regions is not supported.
  // Dest register ends at the position after the last character written.
  static void GenerateCopyCharacters(MacroAssembler* masm,
                                     Register dest,
                                     Register src,
                                     Register count,
                                     Register scratch,
                                     bool ascii);

  // Generate code for copying a large number of characters. This function
  // is allowed to spend extra time setting up conditions to make copying
  // faster. Copying of overlapping regions is not supported.
  // Dest register ends at the position after the last character written.
  static void GenerateCopyCharactersLong(MacroAssembler* masm,
                                         Register dest,
                                         Register src,
                                         Register count,
                                         Register scratch1,
                                         Register scratch2,
                                         Register scratch3,
                                         Register scratch4,
                                         Register scratch5,
                                         int flags);


  // Probe the string table for a two character string. If the string is
  // not found by probing a jump to the label not_found is performed. This jump
  // does not guarantee that the string is not in the string table. If the
  // string is found the code falls through with the string in register r0.
  // Contents of both c1 and c2 registers are modified. At the exit c1 is
  // guaranteed to contain halfword with low and high bytes equal to
  // initial contents of c1 and c2 respectively.
  static void GenerateTwoCharacterStringTableProbe(MacroAssembler* masm,
                                                   Register c1,
                                                   Register c2,
                                                   Register scratch1,
                                                   Register scratch2,
                                                   Register scratch3,
                                                   Register scratch4,
                                                   Register scratch5,
                                                   Label* not_found);

  // Generate string hash.
  static void GenerateHashInit(MacroAssembler* masm,
                               Register hash,
                               Register character);

  static void GenerateHashAddCharacter(MacroAssembler* masm,
                                       Register hash,
                                       Register character);

  static void GenerateHashGetHash(MacroAssembler* masm,
                                  Register hash);

 private:
  DISALLOW_IMPLICIT_CONSTRUCTORS(StringHelper);
};


class StringAddStub: public PlatformCodeStub {
 public:
  explicit StringAddStub(StringAddFlags flags) : flags_(flags) {}

 private:
  Major MajorKey() { return StringAdd; }
  int MinorKey() { return flags_; }

  void Generate(MacroAssembler* masm);

  void GenerateConvertArgument(MacroAssembler* masm,
                               int stack_offset,
                               Register arg,
                               Register scratch1,
                               Register scratch2,
                               Register scratch3,
                               Register scratch4,
                               Label* slow);

  void GenerateRegisterArgsPush(MacroAssembler* masm);
  void GenerateRegisterArgsPop(MacroAssembler* masm);

  const StringAddFlags flags_;
};


class SubStringStub: public PlatformCodeStub {
 public:
  SubStringStub() {}

 private:
  Major MajorKey() { return SubString; }
  int MinorKey() { return 0; }

  void Generate(MacroAssembler* masm);
};


class StringCompareStub: public PlatformCodeStub {
 public:
  StringCompareStub() { }

  // Compare two flat ASCII strings and returns result in v0.
  static void GenerateCompareFlatAsciiStrings(MacroAssembler* masm,
                                              Register left,
                                              Register right,
                                              Register scratch1,
                                              Register scratch2,
                                              Register scratch3,
                                              Register scratch4);

  // Compares two flat ASCII strings for equality and returns result
  // in v0.
  static void GenerateFlatAsciiStringEquals(MacroAssembler* masm,
                                            Register left,
                                            Register right,
                                            Register scratch1,
                                            Register scratch2,
                                            Register scratch3);

 private:
  virtual Major MajorKey() { return StringCompare; }
  virtual int MinorKey() { return 0; }
  virtual void Generate(MacroAssembler* masm);

  static void GenerateAsciiCharsCompareLoop(MacroAssembler* masm,
                                            Register left,
                                            Register right,
                                            Register length,
                                            Register scratch1,
                                            Register scratch2,
                                            Register scratch3,
                                            Label* chars_not_equal);
};


// This stub can convert a signed int32 to a heap number (double).  It does
// not work for int32s that are in Smi range!  No GC occurs during this stub
// so you don't have to set up the frame.
class WriteInt32ToHeapNumberStub : public PlatformCodeStub {
 public:
  WriteInt32ToHeapNumberStub(Register the_int,
                             Register the_heap_number,
                             Register scratch,
                             Register scratch2)
      : the_int_(the_int),
        the_heap_number_(the_heap_number),
        scratch_(scratch),
        sign_(scratch2) {
    ASSERT(IntRegisterBits::is_valid(the_int_.code()));
    ASSERT(HeapNumberRegisterBits::is_valid(the_heap_number_.code()));
    ASSERT(ScratchRegisterBits::is_valid(scratch_.code()));
    ASSERT(SignRegisterBits::is_valid(sign_.code()));
  }

  bool IsPregenerated();
  static void GenerateFixedRegStubsAheadOfTime(Isolate* isolate);

 private:
  Register the_int_;
  Register the_heap_number_;
  Register scratch_;
  Register sign_;

  // Minor key encoding in 16 bits.
  class IntRegisterBits: public BitField<int, 0, 4> {};
  class HeapNumberRegisterBits: public BitField<int, 4, 4> {};
  class ScratchRegisterBits: public BitField<int, 8, 4> {};
  class SignRegisterBits: public BitField<int, 12, 4> {};

  Major MajorKey() { return WriteInt32ToHeapNumber; }
  int MinorKey() {
    // Encode the parameters in a unique 16 bit value.
    return IntRegisterBits::encode(the_int_.code())
           | HeapNumberRegisterBits::encode(the_heap_number_.code())
           | ScratchRegisterBits::encode(scratch_.code())
           | SignRegisterBits::encode(sign_.code());
  }

  void Generate(MacroAssembler* masm);
};


class NumberToStringStub: public PlatformCodeStub {
 public:
  NumberToStringStub() { }

  // Generate code to do a lookup in the number string cache. If the number in
  // the register object is found in the cache the generated code falls through
  // with the result in the result register. The object and the result register
  // can be the same. If the number is not found in the cache the code jumps to
  // the label not_found with only the content of register object unchanged.
  static void GenerateLookupNumberStringCache(MacroAssembler* masm,
                                              Register object,
                                              Register result,
                                              Register scratch1,
                                              Register scratch2,
                                              Register scratch3,
                                              Label* not_found);

 private:
  Major MajorKey() { return NumberToString; }
  int MinorKey() { return 0; }

  void Generate(MacroAssembler* masm);
};


class RecordWriteStub: public PlatformCodeStub {
 public:
  RecordWriteStub(Register object,
                  Register value,
                  Register address,
                  RememberedSetAction remembered_set_action,
                  SaveFPRegsMode fp_mode)
      : object_(object),
        value_(value),
        address_(address),
        remembered_set_action_(remembered_set_action),
        save_fp_regs_mode_(fp_mode),
        regs_(object,   // An input reg.
              address,  // An input reg.
              value) {  // One scratch reg.
  }

  enum Mode {
    STORE_BUFFER_ONLY,
    INCREMENTAL,
    INCREMENTAL_COMPACTION
  };

  virtual bool IsPregenerated();
  static void GenerateFixedRegStubsAheadOfTime(Isolate* isolate);
  virtual bool SometimesSetsUpAFrame() { return false; }

  static void PatchBranchIntoNop(MacroAssembler* masm, int pos) {
    const unsigned offset = masm->instr_at(pos) & kImm16Mask;
    masm->instr_at_put(pos, BNE | (zero_reg.code() << kRsShift) |
        (zero_reg.code() << kRtShift) | (offset & kImm16Mask));
    ASSERT(Assembler::IsBne(masm->instr_at(pos)));
  }

  static void PatchNopIntoBranch(MacroAssembler* masm, int pos) {
    const unsigned offset = masm->instr_at(pos) & kImm16Mask;
    masm->instr_at_put(pos, BEQ | (zero_reg.code() << kRsShift) |
        (zero_reg.code() << kRtShift) | (offset & kImm16Mask));
    ASSERT(Assembler::IsBeq(masm->instr_at(pos)));
  }

  static Mode GetMode(Code* stub) {
    Instr first_instruction = Assembler::instr_at(stub->instruction_start());
    Instr second_instruction = Assembler::instr_at(stub->instruction_start() +
                                                   2 * Assembler::kInstrSize);

    if (Assembler::IsBeq(first_instruction)) {
      return INCREMENTAL;
    }

    ASSERT(Assembler::IsBne(first_instruction));

    if (Assembler::IsBeq(second_instruction)) {
      return INCREMENTAL_COMPACTION;
    }

    ASSERT(Assembler::IsBne(second_instruction));

    return STORE_BUFFER_ONLY;
  }

  static void Patch(Code* stub, Mode mode) {
    MacroAssembler masm(NULL,
                        stub->instruction_start(),
                        stub->instruction_size());
    switch (mode) {
      case STORE_BUFFER_ONLY:
        ASSERT(GetMode(stub) == INCREMENTAL ||
               GetMode(stub) == INCREMENTAL_COMPACTION);
        PatchBranchIntoNop(&masm, 0);
        PatchBranchIntoNop(&masm, 2 * Assembler::kInstrSize);
        break;
      case INCREMENTAL:
        ASSERT(GetMode(stub) == STORE_BUFFER_ONLY);
        PatchNopIntoBranch(&masm, 0);
        break;
      case INCREMENTAL_COMPACTION:
        ASSERT(GetMode(stub) == STORE_BUFFER_ONLY);
        PatchNopIntoBranch(&masm, 2 * Assembler::kInstrSize);
        break;
    }
    ASSERT(GetMode(stub) == mode);
    CPU::FlushICache(stub->instruction_start(), 4 * Assembler::kInstrSize);
  }

 private:
  // This is a helper class for freeing up 3 scratch registers.  The input is
  // two registers that must be preserved and one scratch register provided by
  // the caller.
  class RegisterAllocation {
   public:
    RegisterAllocation(Register object,
                       Register address,
                       Register scratch0)
        : object_(object),
          address_(address),
          scratch0_(scratch0) {
      ASSERT(!AreAliased(scratch0, object, address, no_reg));
      scratch1_ = GetRegThatIsNotOneOf(object_, address_, scratch0_);
    }

    void Save(MacroAssembler* masm) {
      ASSERT(!AreAliased(object_, address_, scratch1_, scratch0_));
      // We don't have to save scratch0_ because it was given to us as
      // a scratch register.
      masm->push(scratch1_);
    }

    void Restore(MacroAssembler* masm) {
      masm->pop(scratch1_);
    }

    // If we have to call into C then we need to save and restore all caller-
    // saved registers that were not already preserved.  The scratch registers
    // will be restored by other means so we don't bother pushing them here.
    void SaveCallerSaveRegisters(MacroAssembler* masm, SaveFPRegsMode mode) {
      masm->MultiPush((kJSCallerSaved | ra.bit()) & ~scratch1_.bit());
      if (mode == kSaveFPRegs) {
        masm->MultiPushFPU(kCallerSavedFPU);
      }
    }

    inline void RestoreCallerSaveRegisters(MacroAssembler*masm,
                                           SaveFPRegsMode mode) {
      if (mode == kSaveFPRegs) {
        masm->MultiPopFPU(kCallerSavedFPU);
      }
      masm->MultiPop((kJSCallerSaved | ra.bit()) & ~scratch1_.bit());
    }

    inline Register object() { return object_; }
    inline Register address() { return address_; }
    inline Register scratch0() { return scratch0_; }
    inline Register scratch1() { return scratch1_; }

   private:
    Register object_;
    Register address_;
    Register scratch0_;
    Register scratch1_;

    Register GetRegThatIsNotOneOf(Register r1,
                                  Register r2,
                                  Register r3) {
      for (int i = 0; i < Register::NumAllocatableRegisters(); i++) {
        Register candidate = Register::FromAllocationIndex(i);
        if (candidate.is(r1)) continue;
        if (candidate.is(r2)) continue;
        if (candidate.is(r3)) continue;
        return candidate;
      }
      UNREACHABLE();
      return no_reg;
    }
    friend class RecordWriteStub;
  };

  enum OnNoNeedToInformIncrementalMarker {
    kReturnOnNoNeedToInformIncrementalMarker,
    kUpdateRememberedSetOnNoNeedToInformIncrementalMarker
  };

  void Generate(MacroAssembler* masm);
  void GenerateIncremental(MacroAssembler* masm, Mode mode);
  void CheckNeedsToInformIncrementalMarker(
      MacroAssembler* masm,
      OnNoNeedToInformIncrementalMarker on_no_need,
      Mode mode);
  void InformIncrementalMarker(MacroAssembler* masm, Mode mode);

  Major MajorKey() { return RecordWrite; }

  int MinorKey() {
    return ObjectBits::encode(object_.code()) |
        ValueBits::encode(value_.code()) |
        AddressBits::encode(address_.code()) |
        RememberedSetActionBits::encode(remembered_set_action_) |
        SaveFPRegsModeBits::encode(save_fp_regs_mode_);
  }

  void Activate(Code* code) {
    code->GetHeap()->incremental_marking()->ActivateGeneratedStub(code);
  }

  class ObjectBits: public BitField<int, 0, 5> {};
  class ValueBits: public BitField<int, 5, 5> {};
  class AddressBits: public BitField<int, 10, 5> {};
  class RememberedSetActionBits: public BitField<RememberedSetAction, 15, 1> {};
  class SaveFPRegsModeBits: public BitField<SaveFPRegsMode, 16, 1> {};

  Register object_;
  Register value_;
  Register address_;
  RememberedSetAction remembered_set_action_;
  SaveFPRegsMode save_fp_regs_mode_;
  Label slow_;
  RegisterAllocation regs_;
};


// Enter C code from generated RegExp code in a way that allows
// the C code to fix the return address in case of a GC.
// Currently only needed on ARM and MIPS.
class RegExpCEntryStub: public PlatformCodeStub {
 public:
  RegExpCEntryStub() {}
  virtual ~RegExpCEntryStub() {}
  void Generate(MacroAssembler* masm);

 private:
  Major MajorKey() { return RegExpCEntry; }
  int MinorKey() { return 0; }

  bool NeedsImmovableCode() { return true; }
};

// Trampoline stub to call into native code. To call safely into native code
// in the presence of compacting GC (which can move code objects) we need to
// keep the code which called into native pinned in the memory. Currently the
// simplest approach is to generate such stub early enough so it can never be
// moved by GC
class DirectCEntryStub: public PlatformCodeStub {
 public:
  DirectCEntryStub() {}
  void Generate(MacroAssembler* masm);
  void GenerateCall(MacroAssembler* masm, Register target);

 private:
  Major MajorKey() { return DirectCEntry; }
  int MinorKey() { return 0; }

  bool NeedsImmovableCode() { return true; }
};

class FloatingPointHelper : public AllStatic {
 public:
  enum Destination {
    kFPURegisters,
    kCoreRegisters
  };


  // Loads smis from a0 and a1 (right and left in binary operations) into
  // floating point registers. Depending on the destination the values ends up
  // either f14 and f12 or in a2/a3 and a0/a1 respectively. If the destination
  // is floating point registers FPU must be supported. If core registers are
  // requested when FPU is supported f12 and f14 will be scratched.
  static void LoadSmis(MacroAssembler* masm,
                       Destination destination,
                       Register scratch1,
                       Register scratch2);

  // Convert 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.
  static void ConvertNumberToInt32(MacroAssembler* masm,
                                   Register object,
                                   Register dst,
                                   Register heap_number_map,
                                   Register scratch1,
                                   Register scratch2,
                                   Register scratch3,
                                   FPURegister double_scratch,
                                   Label* not_int32);

  // Converts the integer (untagged smi) in |int_scratch| to a double, storing
  // the result either in |double_dst| or |dst2:dst1|, depending on
  // |destination|.
  // Warning: The value in |int_scratch| will be changed in the process!
  static void ConvertIntToDouble(MacroAssembler* masm,
                                 Register int_scratch,
                                 Destination destination,
                                 FPURegister double_dst,
                                 Register dst1,
                                 Register dst2,
                                 Register scratch2,
                                 FPURegister single_scratch);

  // Load 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.
  static void LoadNumberAsInt32Double(MacroAssembler* masm,
                                      Register object,
                                      Destination destination,
                                      FPURegister double_dst,
                                      FPURegister double_scratch,
                                      Register dst1,
                                      Register dst2,
                                      Register heap_number_map,
                                      Register scratch1,
                                      Register scratch2,
                                      FPURegister single_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.
  // scratch3 is not used when FPU is supported.
  static void LoadNumberAsInt32(MacroAssembler* masm,
                                Register object,
                                Register dst,
                                Register heap_number_map,
                                Register scratch1,
                                Register scratch2,
                                Register scratch3,
                                FPURegister double_scratch0,
                                FPURegister double_scratch1,
                                Label* not_int32);

  // Generates code to call a C function to do a double operation using core
  // registers. (Used when FPU is not supported.)
  // This code never falls through, but returns with a heap number containing
  // the result in v0.
  // Register heapnumber_result must be a heap number in which the
  // result of the operation will be stored.
  // Requires the following layout on entry:
  // 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).
  static void CallCCodeForDoubleOperation(MacroAssembler* masm,
                                          Token::Value op,
                                          Register heap_number_result,
                                          Register scratch);

  // Loads the objects from |object| into floating point registers.
  // Depending on |destination| the value ends up either in |dst| or
  // in |dst1|/|dst2|. If |destination| is kFPURegisters, then FPU
  // must be supported. If kCoreRegisters are requested and FPU is
  // supported, |dst| will be scratched. If |object| is neither smi nor
  // heap number, |not_number| is jumped to with |object| still intact.
  static void LoadNumber(MacroAssembler* masm,
                         FloatingPointHelper::Destination destination,
                         Register object,
                         FPURegister dst,
                         Register dst1,
                         Register dst2,
                         Register heap_number_map,
                         Register scratch1,
                         Register scratch2,
                         Label* not_number);
};


class NameDictionaryLookupStub: public PlatformCodeStub {
 public:
  enum LookupMode { POSITIVE_LOOKUP, NEGATIVE_LOOKUP };

  explicit NameDictionaryLookupStub(LookupMode mode) : mode_(mode) { }

  void Generate(MacroAssembler* masm);

  static void GenerateNegativeLookup(MacroAssembler* masm,
                                     Label* miss,
                                     Label* done,
                                     Register receiver,
                                     Register properties,
                                     Handle<Name> name,
                                     Register scratch0);

  static void GeneratePositiveLookup(MacroAssembler* masm,
                                     Label* miss,
                                     Label* done,
                                     Register elements,
                                     Register name,
                                     Register r0,
                                     Register r1);

  virtual bool SometimesSetsUpAFrame() { return false; }

 private:
  static const int kInlinedProbes = 4;
  static const int kTotalProbes = 20;

  static const int kCapacityOffset =
      NameDictionary::kHeaderSize +
      NameDictionary::kCapacityIndex * kPointerSize;

  static const int kElementsStartOffset =
      NameDictionary::kHeaderSize +
      NameDictionary::kElementsStartIndex * kPointerSize;

  Major MajorKey() { return NameDictionaryLookup; }

  int MinorKey() {
    return LookupModeBits::encode(mode_);
  }

  class LookupModeBits: public BitField<LookupMode, 0, 1> {};

  LookupMode mode_;
};


} }  // namespace v8::internal

#endif  // V8_MIPS_CODE_STUBS_ARM_H_