src/arm/code-stubs-arm.h - v8/v8.git - Git at Google

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // 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
 //       disclaimer in the documentation and/or other materials provided
 //       with the distribution.
 //     * Neither the name of Google Inc. nor the names of its
 //       contributors may be used to endorse or promote products derived
 //       from this software without specific prior written permission.
 //
 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 #ifndef V8_ARM_CODE_STUBS_ARM_H_
 #define V8_ARM_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() { }

   // Compares two flat ASCII strings and returns result in r0.
   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 r0.
   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,
                                             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)
       : the_int_(the_int),
         the_heap_number_(the_heap_number),
         scratch_(scratch) { }

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

  private:
   Register the_int_;
   Register the_heap_number_;
   Register scratch_;

   // 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> {};

   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());
   }

   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) {
     masm->instr_at_put(pos, (masm->instr_at(pos) & ~B27) | (B24 | B20));
     ASSERT(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);
     ASSERT(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;
     }

     ASSERT(Assembler::IsTstImmediate(first_instruction));

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

     ASSERT(Assembler::IsTstImmediate(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, 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, Assembler::kInstrSize);
         break;
     }
     ASSERT(GetMode(stub) == mode);
     CPU::FlushICache(stub->instruction_start(), 2 * 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->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_;

     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, 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> {};

   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.
 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 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_ARM_CODE_STUBS_ARM_H_
	// Copyright 2012 the V8 project authors. All rights reserved.
	// Redistribution and use in source and binary forms, with or without
	// 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
	// disclaimer in the documentation and/or other materials provided
	// with the distribution.
	// * Neither the name of Google Inc. nor the names of its
	// contributors may be used to endorse or promote products derived
	// from this software without specific prior written permission.
	//
	// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

	#ifndef V8_ARM_CODE_STUBS_ARM_H_
	#define V8_ARM_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() { }

	// Compares two flat ASCII strings and returns result in r0.
	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 r0.
	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,
	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)
	: the_int_(the_int),
	the_heap_number_(the_heap_number),
	scratch_(scratch) { }

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

	private:
	Register the_int_;
	Register the_heap_number_;
	Register scratch_;

	// 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> {};

	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());
	}

	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) {
	masm->instr_at_put(pos, (masm->instr_at(pos) & ~B27) \| (B24 \| B20));
	ASSERT(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);
	ASSERT(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;
	}

	ASSERT(Assembler::IsTstImmediate(first_instruction));

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

	ASSERT(Assembler::IsTstImmediate(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, 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, Assembler::kInstrSize);
	break;
	}
	ASSERT(GetMode(stub) == mode);
	CPU::FlushICache(stub->instruction_start(), 2 * 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->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_;

	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, 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> {};

	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.
	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 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_ARM_CODE_STUBS_ARM_H_