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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:
RecordWriteStub(Isolate * isolate,Register object,Register value,Register address,RememberedSetAction remembered_set_action,SaveFPRegsMode fp_mode)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 
RecordWriteStub(uint32_t key,Isolate * isolate)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 
SometimesSetsUpAFrame()68   bool SometimesSetsUpAFrame() override { return false; }
69 
PatchBranchIntoNop(MacroAssembler * masm,int pos)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 
PatchNopIntoBranch(MacroAssembler * masm,int pos)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 
GetMode(Code * stub)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 
Patch(Code * stub,Mode mode)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:
RegisterAllocation(Register object,Register address,Register scratch0)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 
Save(MacroAssembler * masm)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 
Restore(MacroAssembler * masm)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.
SaveCallerSaveRegisters(MacroAssembler * masm,SaveFPRegsMode mode)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 
RestoreCallerSaveRegisters(MacroAssembler * masm,SaveFPRegsMode mode)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 
object()171     inline Register object() { return object_; }
address()172     inline Register address() { return address_; }
scratch0()173     inline Register scratch0() { return scratch0_; }
scratch1()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 
MajorKey()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 
Activate(Code * code)200   void Activate(Code* code) override {
201     code->GetHeap()->incremental_marking()->ActivateGeneratedStub(code);
202   }
203 
object()204   Register object() const {
205     return Register::from_code(ObjectBits::decode(minor_key_));
206   }
207 
value()208   Register value() const {
209     return Register::from_code(ValueBits::decode(minor_key_));
210   }
211 
address()212   Register address() const {
213     return Register::from_code(AddressBits::decode(minor_key_));
214   }
215 
remembered_set_action()216   RememberedSetAction remembered_set_action() const {
217     return RememberedSetActionBits::decode(minor_key_);
218   }
219 
save_fp_regs_mode()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:
DirectCEntryStub(Isolate * isolate)244   explicit DirectCEntryStub(Isolate* isolate) : PlatformCodeStub(isolate) {}
245   void GenerateCall(MacroAssembler* masm, Register target);
246 
247  private:
NeedsImmovableCode()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 
NameDictionaryLookupStub(Isolate * isolate,LookupMode mode)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 
SometimesSetsUpAFrame()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 
mode()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