text: // Copyright 2012 the V8 project authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #ifndef V8_ARM_CODE_STUBS_ARM_H_
  #define V8_ARM_CODE_STUBS_ARM_H_
  
  #include "src/arm/frames-arm.h"
  
  namespace v8 {
  namespace internal {
  
  
  void ArrayNativeCode(MacroAssembler* masm, Label* call_generic_code);
  
  
  class StringHelper : public AllStatic {
   public:
    // Compares two flat one-byte strings and returns result in r0.
    static void GenerateCompareFlatOneByteStrings(
        MacroAssembler* masm, Register left, Register right, Register scratch1,
        Register scratch2, Register scratch3, Register scratch4);
  
    // Compares two flat one-byte strings for equality and returns result in r0.
    static void GenerateFlatOneByteStringEquals(MacroAssembler* masm,
                                                Register left, Register right,
                                                Register scratch1,
                                                Register scratch2,
                                                Register scratch3);
  
   private:
    static void GenerateOneByteCharsCompareLoop(
        MacroAssembler* masm, Register left, Register right, Register length,
        Register scratch1, Register scratch2, Label* chars_not_equal);
  
    DISALLOW_IMPLICIT_CONSTRUCTORS(StringHelper);
  };
  
  
  class RecordWriteStub: public PlatformCodeStub {
   public:
    RecordWriteStub(Isolate* isolate,
                    Register object,
                    Register value,
                    Register address,
                    RememberedSetAction remembered_set_action,
                    SaveFPRegsMode fp_mode)
        : PlatformCodeStub(isolate),
          regs_(object,   // An input reg.
                address,  // An input reg.
                value) {  // One scratch reg.
      minor_key_ = ObjectBits::encode(object.code()) |
                   ValueBits::encode(value.code()) |
                   AddressBits::encode(address.code()) |
                   RememberedSetActionBits::encode(remembered_set_action) |
                   SaveFPRegsModeBits::encode(fp_mode);
    }
  
    RecordWriteStub(uint32_t key, Isolate* isolate)
        : PlatformCodeStub(key, isolate), regs_(object(), address(), value()) {}
  
    enum Mode {
      STORE_BUFFER_ONLY,
      INCREMENTAL,
      INCREMENTAL_COMPACTION
    };
  
    bool SometimesSetsUpAFrame() override { return false; }
  
    static void PatchBranchIntoNop(MacroAssembler* masm, int pos) {
      masm->instr_at_put(pos, (masm->instr_at(pos) & ~B27) | (B24 | B20));
      DCHECK(Assembler::IsTstImmediate(masm->instr_at(pos)));
    }
  
    static void PatchNopIntoBranch(MacroAssembler* masm, int pos) {
      masm->instr_at_put(pos, (masm->instr_at(pos) & ~(B24 | B20)) | B27);
      DCHECK(Assembler::IsBranch(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() +
                                                     Assembler::kInstrSize);
  
      if (Assembler::IsBranch(first_instruction)) {
        return INCREMENTAL;
      }
  
      DCHECK(Assembler::IsTstImmediate(first_instruction));
  
      if (Assembler::IsBranch(second_instruction)) {
        return INCREMENTAL_COMPACTION;
      }
  
      DCHECK(Assembler::IsTstImmediate(second_instruction));
  
      return STORE_BUFFER_ONLY;
    }
  
    static void Patch(Code* stub, Mode mode) {
      MacroAssembler masm(stub->GetIsolate(), stub->instruction_start(),
                          stub->instruction_size(), CodeObjectRequired::kNo);
      switch (mode) {
        case STORE_BUFFER_ONLY:
          DCHECK(GetMode(stub) == INCREMENTAL ||
                 GetMode(stub) == INCREMENTAL_COMPACTION);
          PatchBranchIntoNop(&masm, 0);
          PatchBranchIntoNop(&masm, Assembler::kInstrSize);
          break;
        case INCREMENTAL:
          DCHECK(GetMode(stub) == STORE_BUFFER_ONLY);
          PatchNopIntoBranch(&masm, 0);
          break;
        case INCREMENTAL_COMPACTION:
          DCHECK(GetMode(stub) == STORE_BUFFER_ONLY);
          PatchNopIntoBranch(&masm, Assembler::kInstrSize);
          break;
      }
      DCHECK(GetMode(stub) == mode);
      Assembler::FlushICache(stub->GetIsolate(), stub->instruction_start(),
                             2 * Assembler::kInstrSize);
    }
  
    DEFINE_NULL_CALL_INTERFACE_DESCRIPTOR();
  
   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) {
        DCHECK(!AreAliased(scratch0, object, address, no_reg));
        scratch1_ = GetRegisterThatIsNotOneOf(object_, address_, scratch0_);
      }
  
      void Save(MacroAssembler* masm) {
        DCHECK(!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->stm(db_w, sp, (kCallerSaved | lr.bit()) & ~scratch1_.bit());
        if (mode == kSaveFPRegs) {
          masm->SaveFPRegs(sp, scratch0_);
        }
      }
  
      inline void RestoreCallerSaveRegisters(MacroAssembler*masm,
                                             SaveFPRegsMode mode) {
        if (mode == kSaveFPRegs) {
          masm->RestoreFPRegs(sp, scratch0_);
        }
        masm->ldm(ia_w, sp, (kCallerSaved | lr.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_;
  
      friend class RecordWriteStub;
    };
  
    enum OnNoNeedToInformIncrementalMarker {
      kReturnOnNoNeedToInformIncrementalMarker,
      kUpdateRememberedSetOnNoNeedToInformIncrementalMarker
    };
  
    inline Major MajorKey() const final { return RecordWrite; }
  
    void Generate(MacroAssembler* masm) override;
    void GenerateIncremental(MacroAssembler* masm, Mode mode);
    void CheckNeedsToInformIncrementalMarker(
        MacroAssembler* masm,
        OnNoNeedToInformIncrementalMarker on_no_need,
        Mode mode);
    void InformIncrementalMarker(MacroAssembler* masm);
  
    void Activate(Code* code) override;
  
    Register object() const {
      return Register::from_code(ObjectBits::decode(minor_key_));
    }
  
    Register value() const {
      return Register::from_code(ValueBits::decode(minor_key_));
    }
  
    Register address() const {
      return Register::from_code(AddressBits::decode(minor_key_));
    }
  
    RememberedSetAction remembered_set_action() const {
      return RememberedSetActionBits::decode(minor_key_);
    }
  
    SaveFPRegsMode save_fp_regs_mode() const {
      return SaveFPRegsModeBits::decode(minor_key_);
    }
  
    class ObjectBits: public BitField<int, 0, 4> {};
    class ValueBits: public BitField<int, 4, 4> {};
    class AddressBits: public BitField<int, 8, 4> {};
    class RememberedSetActionBits: public BitField<RememberedSetAction, 12, 1> {};
    class SaveFPRegsModeBits: public BitField<SaveFPRegsMode, 13, 1> {};
  
    Label slow_;
    RegisterAllocation regs_;
  
    DISALLOW_COPY_AND_ASSIGN(RecordWriteStub);
  };
  
  
  // 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:
    explicit DirectCEntryStub(Isolate* isolate) : PlatformCodeStub(isolate) {}
    void GenerateCall(MacroAssembler* masm, Register target);
  
   private:
    bool NeedsImmovableCode() override { return true; }
  
    DEFINE_NULL_CALL_INTERFACE_DESCRIPTOR();
    DEFINE_PLATFORM_CODE_STUB(DirectCEntry, PlatformCodeStub);
  };
  
  
  class NameDictionaryLookupStub: public PlatformCodeStub {
   public:
    enum LookupMode { POSITIVE_LOOKUP, NEGATIVE_LOOKUP };
  
    NameDictionaryLookupStub(Isolate* isolate, LookupMode mode)
        : PlatformCodeStub(isolate) {
      minor_key_ = LookupModeBits::encode(mode);
    }
  
    static void GenerateNegativeLookup(MacroAssembler* masm,
                                       Label* miss,
                                       Label* done,
                                       Register receiver,
                                       Register properties,
                                       Handle<Name> name,
                                       Register scratch0);
  
    bool SometimesSetsUpAFrame() override { 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;
  
    LookupMode mode() const { return LookupModeBits::decode(minor_key_); }
  
    class LookupModeBits: public BitField<LookupMode, 0, 1> {};
  
    DEFINE_NULL_CALL_INTERFACE_DESCRIPTOR();
    DEFINE_PLATFORM_CODE_STUB(NameDictionaryLookup, PlatformCodeStub);
  };
  
  }  // namespace internal
  }  // namespace v8
  
  #endif  // V8_ARM_CODE_STUBS_ARM_H_
  