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      1 // Copyright 2011 the V8 project authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef V8_X64_CODE_STUBS_X64_H_
      6 #define V8_X64_CODE_STUBS_X64_H_
      7 
      8 namespace v8 {
      9 namespace internal {
     10 
     11 
     12 void ArrayNativeCode(MacroAssembler* masm, Label* call_generic_code);
     13 
     14 
     15 class StringHelper : public AllStatic {
     16  public:
     17   // Generate code for copying characters using the rep movs instruction.
     18   // Copies rcx characters from rsi to rdi. Copying of overlapping regions is
     19   // not supported.
     20   static void GenerateCopyCharacters(MacroAssembler* masm,
     21                                      Register dest,
     22                                      Register src,
     23                                      Register count,
     24                                      String::Encoding encoding);
     25 
     26   // Compares two flat one-byte strings and returns result in rax.
     27   static void GenerateCompareFlatOneByteStrings(
     28       MacroAssembler* masm, Register left, Register right, Register scratch1,
     29       Register scratch2, Register scratch3, Register scratch4);
     30 
     31   // Compares two flat one-byte strings for equality and returns result in rax.
     32   static void GenerateFlatOneByteStringEquals(MacroAssembler* masm,
     33                                               Register left, Register right,
     34                                               Register scratch1,
     35                                               Register scratch2);
     36 
     37  private:
     38   static void GenerateOneByteCharsCompareLoop(
     39       MacroAssembler* masm, Register left, Register right, Register length,
     40       Register scratch, Label* chars_not_equal,
     41       Label::Distance near_jump = Label::kFar);
     42 
     43   DISALLOW_IMPLICIT_CONSTRUCTORS(StringHelper);
     44 };
     45 
     46 
     47 class NameDictionaryLookupStub: public PlatformCodeStub {
     48  public:
     49   enum LookupMode { POSITIVE_LOOKUP, NEGATIVE_LOOKUP };
     50 
     51   NameDictionaryLookupStub(Isolate* isolate, Register dictionary,
     52                            Register result, Register index, LookupMode mode)
     53       : PlatformCodeStub(isolate) {
     54     minor_key_ = DictionaryBits::encode(dictionary.code()) |
     55                  ResultBits::encode(result.code()) |
     56                  IndexBits::encode(index.code()) | LookupModeBits::encode(mode);
     57   }
     58 
     59   static void GenerateNegativeLookup(MacroAssembler* masm,
     60                                      Label* miss,
     61                                      Label* done,
     62                                      Register properties,
     63                                      Handle<Name> name,
     64                                      Register r0);
     65 
     66   static void GeneratePositiveLookup(MacroAssembler* masm,
     67                                      Label* miss,
     68                                      Label* done,
     69                                      Register elements,
     70                                      Register name,
     71                                      Register r0,
     72                                      Register r1);
     73 
     74   bool SometimesSetsUpAFrame() override { return false; }
     75 
     76  private:
     77   static const int kInlinedProbes = 4;
     78   static const int kTotalProbes = 20;
     79 
     80   static const int kCapacityOffset =
     81       NameDictionary::kHeaderSize +
     82       NameDictionary::kCapacityIndex * kPointerSize;
     83 
     84   static const int kElementsStartOffset =
     85       NameDictionary::kHeaderSize +
     86       NameDictionary::kElementsStartIndex * kPointerSize;
     87 
     88   Register dictionary() const {
     89     return Register::from_code(DictionaryBits::decode(minor_key_));
     90   }
     91 
     92   Register result() const {
     93     return Register::from_code(ResultBits::decode(minor_key_));
     94   }
     95 
     96   Register index() const {
     97     return Register::from_code(IndexBits::decode(minor_key_));
     98   }
     99 
    100   LookupMode mode() const { return LookupModeBits::decode(minor_key_); }
    101 
    102   class DictionaryBits: public BitField<int, 0, 4> {};
    103   class ResultBits: public BitField<int, 4, 4> {};
    104   class IndexBits: public BitField<int, 8, 4> {};
    105   class LookupModeBits: public BitField<LookupMode, 12, 1> {};
    106 
    107   DEFINE_NULL_CALL_INTERFACE_DESCRIPTOR();
    108   DEFINE_PLATFORM_CODE_STUB(NameDictionaryLookup, PlatformCodeStub);
    109 };
    110 
    111 
    112 class RecordWriteStub: public PlatformCodeStub {
    113  public:
    114   RecordWriteStub(Isolate* isolate, Register object, Register value,
    115                   Register address, RememberedSetAction remembered_set_action,
    116                   SaveFPRegsMode fp_mode)
    117       : PlatformCodeStub(isolate),
    118         regs_(object,   // An input reg.
    119               address,  // An input reg.
    120               value) {  // One scratch reg.
    121     minor_key_ = ObjectBits::encode(object.code()) |
    122                  ValueBits::encode(value.code()) |
    123                  AddressBits::encode(address.code()) |
    124                  RememberedSetActionBits::encode(remembered_set_action) |
    125                  SaveFPRegsModeBits::encode(fp_mode);
    126   }
    127 
    128   RecordWriteStub(uint32_t key, Isolate* isolate)
    129       : PlatformCodeStub(key, isolate), regs_(object(), address(), value()) {}
    130 
    131   enum Mode {
    132     STORE_BUFFER_ONLY,
    133     INCREMENTAL,
    134     INCREMENTAL_COMPACTION
    135   };
    136 
    137   bool SometimesSetsUpAFrame() override { return false; }
    138 
    139   static const byte kTwoByteNopInstruction = 0x3c;  // Cmpb al, #imm8.
    140   static const byte kTwoByteJumpInstruction = 0xeb;  // Jmp #imm8.
    141 
    142   static const byte kFiveByteNopInstruction = 0x3d;  // Cmpl eax, #imm32.
    143   static const byte kFiveByteJumpInstruction = 0xe9;  // Jmp #imm32.
    144 
    145   static Mode GetMode(Code* stub) {
    146     byte first_instruction = stub->instruction_start()[0];
    147     byte second_instruction = stub->instruction_start()[2];
    148 
    149     if (first_instruction == kTwoByteJumpInstruction) {
    150       return INCREMENTAL;
    151     }
    152 
    153     DCHECK(first_instruction == kTwoByteNopInstruction);
    154 
    155     if (second_instruction == kFiveByteJumpInstruction) {
    156       return INCREMENTAL_COMPACTION;
    157     }
    158 
    159     DCHECK(second_instruction == kFiveByteNopInstruction);
    160 
    161     return STORE_BUFFER_ONLY;
    162   }
    163 
    164   static void Patch(Code* stub, Mode mode) {
    165     switch (mode) {
    166       case STORE_BUFFER_ONLY:
    167         DCHECK(GetMode(stub) == INCREMENTAL ||
    168                GetMode(stub) == INCREMENTAL_COMPACTION);
    169         stub->instruction_start()[0] = kTwoByteNopInstruction;
    170         stub->instruction_start()[2] = kFiveByteNopInstruction;
    171         break;
    172       case INCREMENTAL:
    173         DCHECK(GetMode(stub) == STORE_BUFFER_ONLY);
    174         stub->instruction_start()[0] = kTwoByteJumpInstruction;
    175         break;
    176       case INCREMENTAL_COMPACTION:
    177         DCHECK(GetMode(stub) == STORE_BUFFER_ONLY);
    178         stub->instruction_start()[0] = kTwoByteNopInstruction;
    179         stub->instruction_start()[2] = kFiveByteJumpInstruction;
    180         break;
    181     }
    182     DCHECK(GetMode(stub) == mode);
    183     Assembler::FlushICache(stub->GetIsolate(), stub->instruction_start(), 7);
    184   }
    185 
    186   DEFINE_NULL_CALL_INTERFACE_DESCRIPTOR();
    187 
    188  private:
    189   // This is a helper class for freeing up 3 scratch registers, where the third
    190   // is always rcx (needed for shift operations).  The input is two registers
    191   // that must be preserved and one scratch register provided by the caller.
    192   class RegisterAllocation {
    193    public:
    194     RegisterAllocation(Register object,
    195                        Register address,
    196                        Register scratch0)
    197         : object_orig_(object),
    198           address_orig_(address),
    199           scratch0_orig_(scratch0),
    200           object_(object),
    201           address_(address),
    202           scratch0_(scratch0) {
    203       DCHECK(!AreAliased(scratch0, object, address, no_reg));
    204       scratch1_ = GetRegThatIsNotRcxOr(object_, address_, scratch0_);
    205       if (scratch0.is(rcx)) {
    206         scratch0_ = GetRegThatIsNotRcxOr(object_, address_, scratch1_);
    207       }
    208       if (object.is(rcx)) {
    209         object_ = GetRegThatIsNotRcxOr(address_, scratch0_, scratch1_);
    210       }
    211       if (address.is(rcx)) {
    212         address_ = GetRegThatIsNotRcxOr(object_, scratch0_, scratch1_);
    213       }
    214       DCHECK(!AreAliased(scratch0_, object_, address_, rcx));
    215     }
    216 
    217     void Save(MacroAssembler* masm) {
    218       DCHECK(!address_orig_.is(object_));
    219       DCHECK(object_.is(object_orig_) || address_.is(address_orig_));
    220       DCHECK(!AreAliased(object_, address_, scratch1_, scratch0_));
    221       DCHECK(!AreAliased(object_orig_, address_, scratch1_, scratch0_));
    222       DCHECK(!AreAliased(object_, address_orig_, scratch1_, scratch0_));
    223       // We don't have to save scratch0_orig_ because it was given to us as
    224       // a scratch register.  But if we had to switch to a different reg then
    225       // we should save the new scratch0_.
    226       if (!scratch0_.is(scratch0_orig_)) masm->Push(scratch0_);
    227       if (!rcx.is(scratch0_orig_) &&
    228           !rcx.is(object_orig_) &&
    229           !rcx.is(address_orig_)) {
    230         masm->Push(rcx);
    231       }
    232       masm->Push(scratch1_);
    233       if (!address_.is(address_orig_)) {
    234         masm->Push(address_);
    235         masm->movp(address_, address_orig_);
    236       }
    237       if (!object_.is(object_orig_)) {
    238         masm->Push(object_);
    239         masm->movp(object_, object_orig_);
    240       }
    241     }
    242 
    243     void Restore(MacroAssembler* masm) {
    244       // These will have been preserved the entire time, so we just need to move
    245       // them back.  Only in one case is the orig_ reg different from the plain
    246       // one, since only one of them can alias with rcx.
    247       if (!object_.is(object_orig_)) {
    248         masm->movp(object_orig_, object_);
    249         masm->Pop(object_);
    250       }
    251       if (!address_.is(address_orig_)) {
    252         masm->movp(address_orig_, address_);
    253         masm->Pop(address_);
    254       }
    255       masm->Pop(scratch1_);
    256       if (!rcx.is(scratch0_orig_) &&
    257           !rcx.is(object_orig_) &&
    258           !rcx.is(address_orig_)) {
    259         masm->Pop(rcx);
    260       }
    261       if (!scratch0_.is(scratch0_orig_)) masm->Pop(scratch0_);
    262     }
    263 
    264     // If we have to call into C then we need to save and restore all caller-
    265     // saved registers that were not already preserved.
    266 
    267     // The three scratch registers (incl. rcx) will be restored by other means
    268     // so we don't bother pushing them here.  Rbx, rbp and r12-15 are callee
    269     // save and don't need to be preserved.
    270     void SaveCallerSaveRegisters(MacroAssembler* masm, SaveFPRegsMode mode) {
    271       masm->PushCallerSaved(mode, scratch0_, scratch1_, rcx);
    272     }
    273 
    274     inline void RestoreCallerSaveRegisters(MacroAssembler*masm,
    275                                            SaveFPRegsMode mode) {
    276       masm->PopCallerSaved(mode, scratch0_, scratch1_, rcx);
    277     }
    278 
    279     inline Register object() { return object_; }
    280     inline Register address() { return address_; }
    281     inline Register scratch0() { return scratch0_; }
    282     inline Register scratch1() { return scratch1_; }
    283 
    284    private:
    285     Register object_orig_;
    286     Register address_orig_;
    287     Register scratch0_orig_;
    288     Register object_;
    289     Register address_;
    290     Register scratch0_;
    291     Register scratch1_;
    292     // Third scratch register is always rcx.
    293 
    294     Register GetRegThatIsNotRcxOr(Register r1,
    295                                   Register r2,
    296                                   Register r3) {
    297       for (int i = 0; i < Register::kNumRegisters; i++) {
    298         Register candidate = Register::from_code(i);
    299         if (candidate.IsAllocatable()) {
    300           if (candidate.is(rcx)) continue;
    301           if (candidate.is(r1)) continue;
    302           if (candidate.is(r2)) continue;
    303           if (candidate.is(r3)) continue;
    304           return candidate;
    305         }
    306       }
    307       UNREACHABLE();
    308       return no_reg;
    309     }
    310     friend class RecordWriteStub;
    311   };
    312 
    313   enum OnNoNeedToInformIncrementalMarker {
    314     kReturnOnNoNeedToInformIncrementalMarker,
    315     kUpdateRememberedSetOnNoNeedToInformIncrementalMarker
    316   };
    317 
    318   Major MajorKey() const final { return RecordWrite; }
    319 
    320   void Generate(MacroAssembler* masm) override;
    321   void GenerateIncremental(MacroAssembler* masm, Mode mode);
    322   void CheckNeedsToInformIncrementalMarker(
    323       MacroAssembler* masm,
    324       OnNoNeedToInformIncrementalMarker on_no_need,
    325       Mode mode);
    326   void InformIncrementalMarker(MacroAssembler* masm);
    327 
    328   void Activate(Code* code) override {
    329     code->GetHeap()->incremental_marking()->ActivateGeneratedStub(code);
    330   }
    331 
    332   Register object() const {
    333     return Register::from_code(ObjectBits::decode(minor_key_));
    334   }
    335 
    336   Register value() const {
    337     return Register::from_code(ValueBits::decode(minor_key_));
    338   }
    339 
    340   Register address() const {
    341     return Register::from_code(AddressBits::decode(minor_key_));
    342   }
    343 
    344   RememberedSetAction remembered_set_action() const {
    345     return RememberedSetActionBits::decode(minor_key_);
    346   }
    347 
    348   SaveFPRegsMode save_fp_regs_mode() const {
    349     return SaveFPRegsModeBits::decode(minor_key_);
    350   }
    351 
    352   class ObjectBits: public BitField<int, 0, 4> {};
    353   class ValueBits: public BitField<int, 4, 4> {};
    354   class AddressBits: public BitField<int, 8, 4> {};
    355   class RememberedSetActionBits: public BitField<RememberedSetAction, 12, 1> {};
    356   class SaveFPRegsModeBits: public BitField<SaveFPRegsMode, 13, 1> {};
    357 
    358   Label slow_;
    359   RegisterAllocation regs_;
    360 
    361   DISALLOW_COPY_AND_ASSIGN(RecordWriteStub);
    362 };
    363 
    364 
    365 }  // namespace internal
    366 }  // namespace v8
    367 
    368 #endif  // V8_X64_CODE_STUBS_X64_H_
    369