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      1 // Copyright 2012 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_ARM_CODE_STUBS_ARM_H_
      6 #define V8_ARM_CODE_STUBS_ARM_H_
      7 
      8 #include "src/arm/frames-arm.h"
      9 
     10 namespace v8 {
     11 namespace internal {
     12 
     13 
     14 void ArrayNativeCode(MacroAssembler* masm, Label* call_generic_code);
     15 
     16 
     17 class StringHelper : public AllStatic {
     18  public:
     19   // Compares two flat one-byte strings and returns result in r0.
     20   static void GenerateCompareFlatOneByteStrings(
     21       MacroAssembler* masm, Register left, Register right, Register scratch1,
     22       Register scratch2, Register scratch3, Register scratch4);
     23 
     24   // Compares two flat one-byte strings for equality and returns result in r0.
     25   static void GenerateFlatOneByteStringEquals(MacroAssembler* masm,
     26                                               Register left, Register right,
     27                                               Register scratch1,
     28                                               Register scratch2,
     29                                               Register scratch3);
     30 
     31  private:
     32   static void GenerateOneByteCharsCompareLoop(
     33       MacroAssembler* masm, Register left, Register right, Register length,
     34       Register scratch1, Register scratch2, Label* chars_not_equal);
     35 
     36   DISALLOW_IMPLICIT_CONSTRUCTORS(StringHelper);
     37 };
     38 
     39 
     40 class RecordWriteStub: public PlatformCodeStub {
     41  public:
     42   RecordWriteStub(Isolate* isolate,
     43                   Register object,
     44                   Register value,
     45                   Register address,
     46                   RememberedSetAction remembered_set_action,
     47                   SaveFPRegsMode fp_mode)
     48       : PlatformCodeStub(isolate),
     49         regs_(object,   // An input reg.
     50               address,  // An input reg.
     51               value) {  // One scratch reg.
     52     minor_key_ = ObjectBits::encode(object.code()) |
     53                  ValueBits::encode(value.code()) |
     54                  AddressBits::encode(address.code()) |
     55                  RememberedSetActionBits::encode(remembered_set_action) |
     56                  SaveFPRegsModeBits::encode(fp_mode);
     57   }
     58 
     59   RecordWriteStub(uint32_t key, Isolate* isolate)
     60       : PlatformCodeStub(key, isolate), regs_(object(), address(), value()) {}
     61 
     62   enum Mode {
     63     STORE_BUFFER_ONLY,
     64     INCREMENTAL,
     65     INCREMENTAL_COMPACTION
     66   };
     67 
     68   bool SometimesSetsUpAFrame() override { return false; }
     69 
     70   static void PatchBranchIntoNop(MacroAssembler* masm, int pos) {
     71     masm->instr_at_put(pos, (masm->instr_at(pos) & ~B27) | (B24 | B20));
     72     DCHECK(Assembler::IsTstImmediate(masm->instr_at(pos)));
     73   }
     74 
     75   static void PatchNopIntoBranch(MacroAssembler* masm, int pos) {
     76     masm->instr_at_put(pos, (masm->instr_at(pos) & ~(B24 | B20)) | B27);
     77     DCHECK(Assembler::IsBranch(masm->instr_at(pos)));
     78   }
     79 
     80   static Mode GetMode(Code* stub) {
     81     Instr first_instruction = Assembler::instr_at(stub->instruction_start());
     82     Instr second_instruction = Assembler::instr_at(stub->instruction_start() +
     83                                                    Assembler::kInstrSize);
     84 
     85     if (Assembler::IsBranch(first_instruction)) {
     86       return INCREMENTAL;
     87     }
     88 
     89     DCHECK(Assembler::IsTstImmediate(first_instruction));
     90 
     91     if (Assembler::IsBranch(second_instruction)) {
     92       return INCREMENTAL_COMPACTION;
     93     }
     94 
     95     DCHECK(Assembler::IsTstImmediate(second_instruction));
     96 
     97     return STORE_BUFFER_ONLY;
     98   }
     99 
    100   static void Patch(Code* stub, Mode mode) {
    101     MacroAssembler masm(stub->GetIsolate(), stub->instruction_start(),
    102                         stub->instruction_size(), CodeObjectRequired::kNo);
    103     switch (mode) {
    104       case STORE_BUFFER_ONLY:
    105         DCHECK(GetMode(stub) == INCREMENTAL ||
    106                GetMode(stub) == INCREMENTAL_COMPACTION);
    107         PatchBranchIntoNop(&masm, 0);
    108         PatchBranchIntoNop(&masm, Assembler::kInstrSize);
    109         break;
    110       case INCREMENTAL:
    111         DCHECK(GetMode(stub) == STORE_BUFFER_ONLY);
    112         PatchNopIntoBranch(&masm, 0);
    113         break;
    114       case INCREMENTAL_COMPACTION:
    115         DCHECK(GetMode(stub) == STORE_BUFFER_ONLY);
    116         PatchNopIntoBranch(&masm, Assembler::kInstrSize);
    117         break;
    118     }
    119     DCHECK(GetMode(stub) == mode);
    120     Assembler::FlushICache(stub->GetIsolate(), stub->instruction_start(),
    121                            2 * Assembler::kInstrSize);
    122   }
    123 
    124   DEFINE_NULL_CALL_INTERFACE_DESCRIPTOR();
    125 
    126  private:
    127   // This is a helper class for freeing up 3 scratch registers.  The input is
    128   // two registers that must be preserved and one scratch register provided by
    129   // the caller.
    130   class RegisterAllocation {
    131    public:
    132     RegisterAllocation(Register object,
    133                        Register address,
    134                        Register scratch0)
    135         : object_(object),
    136           address_(address),
    137           scratch0_(scratch0) {
    138       DCHECK(!AreAliased(scratch0, object, address, no_reg));
    139       scratch1_ = GetRegisterThatIsNotOneOf(object_, address_, scratch0_);
    140     }
    141 
    142     void Save(MacroAssembler* masm) {
    143       DCHECK(!AreAliased(object_, address_, scratch1_, scratch0_));
    144       // We don't have to save scratch0_ because it was given to us as
    145       // a scratch register.
    146       masm->push(scratch1_);
    147     }
    148 
    149     void Restore(MacroAssembler* masm) {
    150       masm->pop(scratch1_);
    151     }
    152 
    153     // If we have to call into C then we need to save and restore all caller-
    154     // saved registers that were not already preserved.  The scratch registers
    155     // will be restored by other means so we don't bother pushing them here.
    156     void SaveCallerSaveRegisters(MacroAssembler* masm, SaveFPRegsMode mode) {
    157       masm->stm(db_w, sp, (kCallerSaved | lr.bit()) & ~scratch1_.bit());
    158       if (mode == kSaveFPRegs) {
    159         masm->SaveFPRegs(sp, scratch0_);
    160       }
    161     }
    162 
    163     inline void RestoreCallerSaveRegisters(MacroAssembler*masm,
    164                                            SaveFPRegsMode mode) {
    165       if (mode == kSaveFPRegs) {
    166         masm->RestoreFPRegs(sp, scratch0_);
    167       }
    168       masm->ldm(ia_w, sp, (kCallerSaved | lr.bit()) & ~scratch1_.bit());
    169     }
    170 
    171     inline Register object() { return object_; }
    172     inline Register address() { return address_; }
    173     inline Register scratch0() { return scratch0_; }
    174     inline Register scratch1() { return scratch1_; }
    175 
    176    private:
    177     Register object_;
    178     Register address_;
    179     Register scratch0_;
    180     Register scratch1_;
    181 
    182     friend class RecordWriteStub;
    183   };
    184 
    185   enum OnNoNeedToInformIncrementalMarker {
    186     kReturnOnNoNeedToInformIncrementalMarker,
    187     kUpdateRememberedSetOnNoNeedToInformIncrementalMarker
    188   };
    189 
    190   inline Major MajorKey() const final { return RecordWrite; }
    191 
    192   void Generate(MacroAssembler* masm) override;
    193   void GenerateIncremental(MacroAssembler* masm, Mode mode);
    194   void CheckNeedsToInformIncrementalMarker(
    195       MacroAssembler* masm,
    196       OnNoNeedToInformIncrementalMarker on_no_need,
    197       Mode mode);
    198   void InformIncrementalMarker(MacroAssembler* masm);
    199 
    200   void Activate(Code* code) override {
    201     code->GetHeap()->incremental_marking()->ActivateGeneratedStub(code);
    202   }
    203 
    204   Register object() const {
    205     return Register::from_code(ObjectBits::decode(minor_key_));
    206   }
    207 
    208   Register value() const {
    209     return Register::from_code(ValueBits::decode(minor_key_));
    210   }
    211 
    212   Register address() const {
    213     return Register::from_code(AddressBits::decode(minor_key_));
    214   }
    215 
    216   RememberedSetAction remembered_set_action() const {
    217     return RememberedSetActionBits::decode(minor_key_);
    218   }
    219 
    220   SaveFPRegsMode save_fp_regs_mode() const {
    221     return SaveFPRegsModeBits::decode(minor_key_);
    222   }
    223 
    224   class ObjectBits: public BitField<int, 0, 4> {};
    225   class ValueBits: public BitField<int, 4, 4> {};
    226   class AddressBits: public BitField<int, 8, 4> {};
    227   class RememberedSetActionBits: public BitField<RememberedSetAction, 12, 1> {};
    228   class SaveFPRegsModeBits: public BitField<SaveFPRegsMode, 13, 1> {};
    229 
    230   Label slow_;
    231   RegisterAllocation regs_;
    232 
    233   DISALLOW_COPY_AND_ASSIGN(RecordWriteStub);
    234 };
    235 
    236 
    237 // Trampoline stub to call into native code. To call safely into native code
    238 // in the presence of compacting GC (which can move code objects) we need to
    239 // keep the code which called into native pinned in the memory. Currently the
    240 // simplest approach is to generate such stub early enough so it can never be
    241 // moved by GC
    242 class DirectCEntryStub: public PlatformCodeStub {
    243  public:
    244   explicit DirectCEntryStub(Isolate* isolate) : PlatformCodeStub(isolate) {}
    245   void GenerateCall(MacroAssembler* masm, Register target);
    246 
    247  private:
    248   bool NeedsImmovableCode() override { return true; }
    249 
    250   DEFINE_NULL_CALL_INTERFACE_DESCRIPTOR();
    251   DEFINE_PLATFORM_CODE_STUB(DirectCEntry, PlatformCodeStub);
    252 };
    253 
    254 
    255 class NameDictionaryLookupStub: public PlatformCodeStub {
    256  public:
    257   enum LookupMode { POSITIVE_LOOKUP, NEGATIVE_LOOKUP };
    258 
    259   NameDictionaryLookupStub(Isolate* isolate, LookupMode mode)
    260       : PlatformCodeStub(isolate) {
    261     minor_key_ = LookupModeBits::encode(mode);
    262   }
    263 
    264   static void GenerateNegativeLookup(MacroAssembler* masm,
    265                                      Label* miss,
    266                                      Label* done,
    267                                      Register receiver,
    268                                      Register properties,
    269                                      Handle<Name> name,
    270                                      Register scratch0);
    271 
    272   bool SometimesSetsUpAFrame() override { return false; }
    273 
    274  private:
    275   static const int kInlinedProbes = 4;
    276   static const int kTotalProbes = 20;
    277 
    278   static const int kCapacityOffset =
    279       NameDictionary::kHeaderSize +
    280       NameDictionary::kCapacityIndex * kPointerSize;
    281 
    282   static const int kElementsStartOffset =
    283       NameDictionary::kHeaderSize +
    284       NameDictionary::kElementsStartIndex * kPointerSize;
    285 
    286   LookupMode mode() const { return LookupModeBits::decode(minor_key_); }
    287 
    288   class LookupModeBits: public BitField<LookupMode, 0, 1> {};
    289 
    290   DEFINE_NULL_CALL_INTERFACE_DESCRIPTOR();
    291   DEFINE_PLATFORM_CODE_STUB(NameDictionaryLookup, PlatformCodeStub);
    292 };
    293 
    294 }  // namespace internal
    295 }  // namespace v8
    296 
    297 #endif  // V8_ARM_CODE_STUBS_ARM_H_
    298