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_ARM_CONSTANTS_ARM_H_
6 #define V8_ARM_CONSTANTS_ARM_H_
7 
8 // ARM EABI is required.
9 #if defined(__arm__) && !defined(__ARM_EABI__)
10 #error ARM EABI support is required.
11 #endif
12 
13 namespace v8 {
14 namespace internal {
15 
16 // Constant pool marker.
17 // Use UDF, the permanently undefined instruction.
18 const int kConstantPoolMarkerMask = 0xfff000f0;
19 const int kConstantPoolMarker = 0xe7f000f0;
20 const int kConstantPoolLengthMaxMask = 0xffff;
EncodeConstantPoolLength(int length)21 inline int EncodeConstantPoolLength(int length) {
22   DCHECK((length & kConstantPoolLengthMaxMask) == length);
23   return ((length & 0xfff0) << 4) | (length & 0xf);
24 }
DecodeConstantPoolLength(int instr)25 inline int DecodeConstantPoolLength(int instr) {
26   DCHECK((instr & kConstantPoolMarkerMask) == kConstantPoolMarker);
27   return ((instr >> 4) & 0xfff0) | (instr & 0xf);
28 }
29 
30 // Used in code age prologue - ldr(pc, MemOperand(pc, -4))
31 const int kCodeAgeJumpInstruction = 0xe51ff004;
32 
33 // Number of registers in normal ARM mode.
34 const int kNumRegisters = 16;
35 
36 // VFP support.
37 const int kNumVFPSingleRegisters = 32;
38 const int kNumVFPDoubleRegisters = 32;
39 const int kNumVFPRegisters = kNumVFPSingleRegisters + kNumVFPDoubleRegisters;
40 
41 // PC is register 15.
42 const int kPCRegister = 15;
43 const int kNoRegister = -1;
44 
45 // -----------------------------------------------------------------------------
46 // Conditions.
47 
48 // Defines constants and accessor classes to assemble, disassemble and
49 // simulate ARM instructions.
50 //
51 // Section references in the code refer to the "ARM Architecture Reference
52 // Manual" from July 2005 (available at http://www.arm.com/miscPDFs/14128.pdf)
53 //
54 // Constants for specific fields are defined in their respective named enums.
55 // General constants are in an anonymous enum in class Instr.
56 
57 // Values for the condition field as defined in section A3.2
58 enum Condition {
59   kNoCondition = -1,
60 
61   eq =  0 << 28,                 // Z set            Equal.
62   ne =  1 << 28,                 // Z clear          Not equal.
63   cs =  2 << 28,                 // C set            Unsigned higher or same.
64   cc =  3 << 28,                 // C clear          Unsigned lower.
65   mi =  4 << 28,                 // N set            Negative.
66   pl =  5 << 28,                 // N clear          Positive or zero.
67   vs =  6 << 28,                 // V set            Overflow.
68   vc =  7 << 28,                 // V clear          No overflow.
69   hi =  8 << 28,                 // C set, Z clear   Unsigned higher.
70   ls =  9 << 28,                 // C clear or Z set Unsigned lower or same.
71   ge = 10 << 28,                 // N == V           Greater or equal.
72   lt = 11 << 28,                 // N != V           Less than.
73   gt = 12 << 28,                 // Z clear, N == V  Greater than.
74   le = 13 << 28,                 // Z set or N != V  Less then or equal
75   al = 14 << 28,                 //                  Always.
76 
77   kSpecialCondition = 15 << 28,  // Special condition (refer to section A3.2.1).
78   kNumberOfConditions = 16,
79 
80   // Aliases.
81   hs = cs,                       // C set            Unsigned higher or same.
82   lo = cc                        // C clear          Unsigned lower.
83 };
84 
85 
NegateCondition(Condition cond)86 inline Condition NegateCondition(Condition cond) {
87   DCHECK(cond != al);
88   return static_cast<Condition>(cond ^ ne);
89 }
90 
91 
92 // Commute a condition such that {a cond b == b cond' a}.
CommuteCondition(Condition cond)93 inline Condition CommuteCondition(Condition cond) {
94   switch (cond) {
95     case lo:
96       return hi;
97     case hi:
98       return lo;
99     case hs:
100       return ls;
101     case ls:
102       return hs;
103     case lt:
104       return gt;
105     case gt:
106       return lt;
107     case ge:
108       return le;
109     case le:
110       return ge;
111     default:
112       return cond;
113   }
114 }
115 
116 
117 // -----------------------------------------------------------------------------
118 // Instructions encoding.
119 
120 // Instr is merely used by the Assembler to distinguish 32bit integers
121 // representing instructions from usual 32 bit values.
122 // Instruction objects are pointers to 32bit values, and provide methods to
123 // access the various ISA fields.
124 typedef int32_t Instr;
125 
126 
127 // Opcodes for Data-processing instructions (instructions with a type 0 and 1)
128 // as defined in section A3.4
129 enum Opcode {
130   AND =  0 << 21,  // Logical AND.
131   EOR =  1 << 21,  // Logical Exclusive OR.
132   SUB =  2 << 21,  // Subtract.
133   RSB =  3 << 21,  // Reverse Subtract.
134   ADD =  4 << 21,  // Add.
135   ADC =  5 << 21,  // Add with Carry.
136   SBC =  6 << 21,  // Subtract with Carry.
137   RSC =  7 << 21,  // Reverse Subtract with Carry.
138   TST =  8 << 21,  // Test.
139   TEQ =  9 << 21,  // Test Equivalence.
140   CMP = 10 << 21,  // Compare.
141   CMN = 11 << 21,  // Compare Negated.
142   ORR = 12 << 21,  // Logical (inclusive) OR.
143   MOV = 13 << 21,  // Move.
144   BIC = 14 << 21,  // Bit Clear.
145   MVN = 15 << 21   // Move Not.
146 };
147 
148 
149 // The bits for bit 7-4 for some type 0 miscellaneous instructions.
150 enum MiscInstructionsBits74 {
151   // With bits 22-21 01.
152   BX   =  1 << 4,
153   BXJ  =  2 << 4,
154   BLX  =  3 << 4,
155   BKPT =  7 << 4,
156 
157   // With bits 22-21 11.
158   CLZ  =  1 << 4
159 };
160 
161 
162 // Instruction encoding bits and masks.
163 enum {
164   H   = 1 << 5,   // Halfword (or byte).
165   S6  = 1 << 6,   // Signed (or unsigned).
166   L   = 1 << 20,  // Load (or store).
167   S   = 1 << 20,  // Set condition code (or leave unchanged).
168   W   = 1 << 21,  // Writeback base register (or leave unchanged).
169   A   = 1 << 21,  // Accumulate in multiply instruction (or not).
170   B   = 1 << 22,  // Unsigned byte (or word).
171   N   = 1 << 22,  // Long (or short).
172   U   = 1 << 23,  // Positive (or negative) offset/index.
173   P   = 1 << 24,  // Offset/pre-indexed addressing (or post-indexed addressing).
174   I   = 1 << 25,  // Immediate shifter operand (or not).
175 
176   B4  = 1 << 4,
177   B5  = 1 << 5,
178   B6  = 1 << 6,
179   B7  = 1 << 7,
180   B8  = 1 << 8,
181   B9  = 1 << 9,
182   B12 = 1 << 12,
183   B16 = 1 << 16,
184   B18 = 1 << 18,
185   B19 = 1 << 19,
186   B20 = 1 << 20,
187   B21 = 1 << 21,
188   B22 = 1 << 22,
189   B23 = 1 << 23,
190   B24 = 1 << 24,
191   B25 = 1 << 25,
192   B26 = 1 << 26,
193   B27 = 1 << 27,
194   B28 = 1 << 28,
195 
196   // Instruction bit masks.
197   kCondMask   = 15 << 28,
198   kALUMask    = 0x6f << 21,
199   kRdMask     = 15 << 12,  // In str instruction.
200   kCoprocessorMask = 15 << 8,
201   kOpCodeMask = 15 << 21,  // In data-processing instructions.
202   kImm24Mask  = (1 << 24) - 1,
203   kImm16Mask  = (1 << 16) - 1,
204   kImm8Mask  = (1 << 8) - 1,
205   kOff12Mask  = (1 << 12) - 1,
206   kOff8Mask  = (1 << 8) - 1
207 };
208 
209 
210 // -----------------------------------------------------------------------------
211 // Addressing modes and instruction variants.
212 
213 // Condition code updating mode.
214 enum SBit {
215   SetCC   = 1 << 20,  // Set condition code.
216   LeaveCC = 0 << 20   // Leave condition code unchanged.
217 };
218 
219 
220 // Status register selection.
221 enum SRegister {
222   CPSR = 0 << 22,
223   SPSR = 1 << 22
224 };
225 
226 
227 // Shifter types for Data-processing operands as defined in section A5.1.2.
228 enum ShiftOp {
229   LSL = 0 << 5,   // Logical shift left.
230   LSR = 1 << 5,   // Logical shift right.
231   ASR = 2 << 5,   // Arithmetic shift right.
232   ROR = 3 << 5,   // Rotate right.
233 
234   // RRX is encoded as ROR with shift_imm == 0.
235   // Use a special code to make the distinction. The RRX ShiftOp is only used
236   // as an argument, and will never actually be encoded. The Assembler will
237   // detect it and emit the correct ROR shift operand with shift_imm == 0.
238   RRX = -1,
239   kNumberOfShifts = 4
240 };
241 
242 
243 // Status register fields.
244 enum SRegisterField {
245   CPSR_c = CPSR | 1 << 16,
246   CPSR_x = CPSR | 1 << 17,
247   CPSR_s = CPSR | 1 << 18,
248   CPSR_f = CPSR | 1 << 19,
249   SPSR_c = SPSR | 1 << 16,
250   SPSR_x = SPSR | 1 << 17,
251   SPSR_s = SPSR | 1 << 18,
252   SPSR_f = SPSR | 1 << 19
253 };
254 
255 // Status register field mask (or'ed SRegisterField enum values).
256 typedef uint32_t SRegisterFieldMask;
257 
258 
259 // Memory operand addressing mode.
260 enum AddrMode {
261   // Bit encoding P U W.
262   Offset       = (8|4|0) << 21,  // Offset (without writeback to base).
263   PreIndex     = (8|4|1) << 21,  // Pre-indexed addressing with writeback.
264   PostIndex    = (0|4|0) << 21,  // Post-indexed addressing with writeback.
265   NegOffset    = (8|0|0) << 21,  // Negative offset (without writeback to base).
266   NegPreIndex  = (8|0|1) << 21,  // Negative pre-indexed with writeback.
267   NegPostIndex = (0|0|0) << 21   // Negative post-indexed with writeback.
268 };
269 
270 
271 // Load/store multiple addressing mode.
272 enum BlockAddrMode {
273   // Bit encoding P U W .
274   da           = (0|0|0) << 21,  // Decrement after.
275   ia           = (0|4|0) << 21,  // Increment after.
276   db           = (8|0|0) << 21,  // Decrement before.
277   ib           = (8|4|0) << 21,  // Increment before.
278   da_w         = (0|0|1) << 21,  // Decrement after with writeback to base.
279   ia_w         = (0|4|1) << 21,  // Increment after with writeback to base.
280   db_w         = (8|0|1) << 21,  // Decrement before with writeback to base.
281   ib_w         = (8|4|1) << 21,  // Increment before with writeback to base.
282 
283   // Alias modes for comparison when writeback does not matter.
284   da_x         = (0|0|0) << 21,  // Decrement after.
285   ia_x         = (0|4|0) << 21,  // Increment after.
286   db_x         = (8|0|0) << 21,  // Decrement before.
287   ib_x         = (8|4|0) << 21,  // Increment before.
288 
289   kBlockAddrModeMask = (8|4|1) << 21
290 };
291 
292 
293 // Coprocessor load/store operand size.
294 enum LFlag {
295   Long  = 1 << 22,  // Long load/store coprocessor.
296   Short = 0 << 22   // Short load/store coprocessor.
297 };
298 
299 
300 // NEON data type
301 enum NeonDataType {
302   NeonS8 = 0x1,   // U = 0, imm3 = 0b001
303   NeonS16 = 0x2,  // U = 0, imm3 = 0b010
304   NeonS32 = 0x4,  // U = 0, imm3 = 0b100
305   NeonU8 = 1 << 24 | 0x1,   // U = 1, imm3 = 0b001
306   NeonU16 = 1 << 24 | 0x2,  // U = 1, imm3 = 0b010
307   NeonU32 = 1 << 24 | 0x4,   // U = 1, imm3 = 0b100
308   NeonDataTypeSizeMask = 0x7,
309   NeonDataTypeUMask = 1 << 24
310 };
311 
312 enum NeonListType {
313   nlt_1 = 0x7,
314   nlt_2 = 0xA,
315   nlt_3 = 0x6,
316   nlt_4 = 0x2
317 };
318 
319 enum NeonSize {
320   Neon8 = 0x0,
321   Neon16 = 0x1,
322   Neon32 = 0x2,
323   Neon64 = 0x3
324 };
325 
326 // -----------------------------------------------------------------------------
327 // Supervisor Call (svc) specific support.
328 
329 // Special Software Interrupt codes when used in the presence of the ARM
330 // simulator.
331 // svc (formerly swi) provides a 24bit immediate value. Use bits 22:0 for
332 // standard SoftwareInterrupCode. Bit 23 is reserved for the stop feature.
333 enum SoftwareInterruptCodes {
334   // transition to C code
335   kCallRtRedirected= 0x10,
336   // break point
337   kBreakpoint= 0x20,
338   // stop
339   kStopCode = 1 << 23
340 };
341 const uint32_t kStopCodeMask = kStopCode - 1;
342 const uint32_t kMaxStopCode = kStopCode - 1;
343 const int32_t  kDefaultStopCode = -1;
344 
345 
346 // Type of VFP register. Determines register encoding.
347 enum VFPRegPrecision {
348   kSinglePrecision = 0,
349   kDoublePrecision = 1
350 };
351 
352 
353 // VFP FPSCR constants.
354 enum VFPConversionMode {
355   kFPSCRRounding = 0,
356   kDefaultRoundToZero = 1
357 };
358 
359 // This mask does not include the "inexact" or "input denormal" cumulative
360 // exceptions flags, because we usually don't want to check for it.
361 const uint32_t kVFPExceptionMask = 0xf;
362 const uint32_t kVFPInvalidOpExceptionBit = 1 << 0;
363 const uint32_t kVFPOverflowExceptionBit = 1 << 2;
364 const uint32_t kVFPUnderflowExceptionBit = 1 << 3;
365 const uint32_t kVFPInexactExceptionBit = 1 << 4;
366 const uint32_t kVFPFlushToZeroMask = 1 << 24;
367 const uint32_t kVFPDefaultNaNModeControlBit = 1 << 25;
368 
369 const uint32_t kVFPNConditionFlagBit = 1 << 31;
370 const uint32_t kVFPZConditionFlagBit = 1 << 30;
371 const uint32_t kVFPCConditionFlagBit = 1 << 29;
372 const uint32_t kVFPVConditionFlagBit = 1 << 28;
373 
374 
375 // VFP rounding modes. See ARM DDI 0406B Page A2-29.
376 enum VFPRoundingMode {
377   RN = 0 << 22,   // Round to Nearest.
378   RP = 1 << 22,   // Round towards Plus Infinity.
379   RM = 2 << 22,   // Round towards Minus Infinity.
380   RZ = 3 << 22,   // Round towards zero.
381 
382   // Aliases.
383   kRoundToNearest = RN,
384   kRoundToPlusInf = RP,
385   kRoundToMinusInf = RM,
386   kRoundToZero = RZ
387 };
388 
389 const uint32_t kVFPRoundingModeMask = 3 << 22;
390 
391 enum CheckForInexactConversion {
392   kCheckForInexactConversion,
393   kDontCheckForInexactConversion
394 };
395 
396 // -----------------------------------------------------------------------------
397 // Hints.
398 
399 // Branch hints are not used on the ARM.  They are defined so that they can
400 // appear in shared function signatures, but will be ignored in ARM
401 // implementations.
402 enum Hint { no_hint };
403 
404 // Hints are not used on the arm.  Negating is trivial.
NegateHint(Hint ignored)405 inline Hint NegateHint(Hint ignored) { return no_hint; }
406 
407 
408 // -----------------------------------------------------------------------------
409 // Instruction abstraction.
410 
411 // The class Instruction enables access to individual fields defined in the ARM
412 // architecture instruction set encoding as described in figure A3-1.
413 // Note that the Assembler uses typedef int32_t Instr.
414 //
415 // Example: Test whether the instruction at ptr does set the condition code
416 // bits.
417 //
418 // bool InstructionSetsConditionCodes(byte* ptr) {
419 //   Instruction* instr = Instruction::At(ptr);
420 //   int type = instr->TypeValue();
421 //   return ((type == 0) || (type == 1)) && instr->HasS();
422 // }
423 //
424 class Instruction {
425  public:
426   enum {
427     kInstrSize = 4,
428     kInstrSizeLog2 = 2,
429     kPCReadOffset = 8
430   };
431 
432   // Helper macro to define static accessors.
433   // We use the cast to char* trick to bypass the strict anti-aliasing rules.
434   #define DECLARE_STATIC_TYPED_ACCESSOR(return_type, Name)                     \
435     static inline return_type Name(Instr instr) {                              \
436       char* temp = reinterpret_cast<char*>(&instr);                            \
437       return reinterpret_cast<Instruction*>(temp)->Name();                     \
438     }
439 
440   #define DECLARE_STATIC_ACCESSOR(Name) DECLARE_STATIC_TYPED_ACCESSOR(int, Name)
441 
442   // Get the raw instruction bits.
InstructionBits()443   inline Instr InstructionBits() const {
444     return *reinterpret_cast<const Instr*>(this);
445   }
446 
447   // Set the raw instruction bits to value.
SetInstructionBits(Instr value)448   inline void SetInstructionBits(Instr value) {
449     *reinterpret_cast<Instr*>(this) = value;
450   }
451 
452   // Read one particular bit out of the instruction bits.
Bit(int nr)453   inline int Bit(int nr) const {
454     return (InstructionBits() >> nr) & 1;
455   }
456 
457   // Read a bit field's value out of the instruction bits.
Bits(int hi,int lo)458   inline int Bits(int hi, int lo) const {
459     return (InstructionBits() >> lo) & ((2 << (hi - lo)) - 1);
460   }
461 
462   // Read a bit field out of the instruction bits.
BitField(int hi,int lo)463   inline int BitField(int hi, int lo) const {
464     return InstructionBits() & (((2 << (hi - lo)) - 1) << lo);
465   }
466 
467   // Static support.
468 
469   // Read one particular bit out of the instruction bits.
Bit(Instr instr,int nr)470   static inline int Bit(Instr instr, int nr) {
471     return (instr >> nr) & 1;
472   }
473 
474   // Read the value of a bit field out of the instruction bits.
Bits(Instr instr,int hi,int lo)475   static inline int Bits(Instr instr, int hi, int lo) {
476     return (instr >> lo) & ((2 << (hi - lo)) - 1);
477   }
478 
479 
480   // Read a bit field out of the instruction bits.
BitField(Instr instr,int hi,int lo)481   static inline int BitField(Instr instr, int hi, int lo) {
482     return instr & (((2 << (hi - lo)) - 1) << lo);
483   }
484 
485 
486   // Accessors for the different named fields used in the ARM encoding.
487   // The naming of these accessor corresponds to figure A3-1.
488   //
489   // Two kind of accessors are declared:
490   // - <Name>Field() will return the raw field, i.e. the field's bits at their
491   //   original place in the instruction encoding.
492   //   e.g. if instr is the 'addgt r0, r1, r2' instruction, encoded as
493   //   0xC0810002 ConditionField(instr) will return 0xC0000000.
494   // - <Name>Value() will return the field value, shifted back to bit 0.
495   //   e.g. if instr is the 'addgt r0, r1, r2' instruction, encoded as
496   //   0xC0810002 ConditionField(instr) will return 0xC.
497 
498 
499   // Generally applicable fields
ConditionValue()500   inline Condition ConditionValue() const {
501     return static_cast<Condition>(Bits(31, 28));
502   }
ConditionField()503   inline Condition ConditionField() const {
504     return static_cast<Condition>(BitField(31, 28));
505   }
506   DECLARE_STATIC_TYPED_ACCESSOR(Condition, ConditionValue);
507   DECLARE_STATIC_TYPED_ACCESSOR(Condition, ConditionField);
508 
TypeValue()509   inline int TypeValue() const { return Bits(27, 25); }
SpecialValue()510   inline int SpecialValue() const { return Bits(27, 23); }
511 
RnValue()512   inline int RnValue() const { return Bits(19, 16); }
513   DECLARE_STATIC_ACCESSOR(RnValue);
RdValue()514   inline int RdValue() const { return Bits(15, 12); }
515   DECLARE_STATIC_ACCESSOR(RdValue);
516 
CoprocessorValue()517   inline int CoprocessorValue() const { return Bits(11, 8); }
518   // Support for VFP.
519   // Vn(19-16) | Vd(15-12) |  Vm(3-0)
VnValue()520   inline int VnValue() const { return Bits(19, 16); }
VmValue()521   inline int VmValue() const { return Bits(3, 0); }
VdValue()522   inline int VdValue() const { return Bits(15, 12); }
NValue()523   inline int NValue() const { return Bit(7); }
MValue()524   inline int MValue() const { return Bit(5); }
DValue()525   inline int DValue() const { return Bit(22); }
RtValue()526   inline int RtValue() const { return Bits(15, 12); }
PValue()527   inline int PValue() const { return Bit(24); }
UValue()528   inline int UValue() const { return Bit(23); }
Opc1Value()529   inline int Opc1Value() const { return (Bit(23) << 2) | Bits(21, 20); }
Opc2Value()530   inline int Opc2Value() const { return Bits(19, 16); }
Opc3Value()531   inline int Opc3Value() const { return Bits(7, 6); }
SzValue()532   inline int SzValue() const { return Bit(8); }
VLValue()533   inline int VLValue() const { return Bit(20); }
VCValue()534   inline int VCValue() const { return Bit(8); }
VAValue()535   inline int VAValue() const { return Bits(23, 21); }
VBValue()536   inline int VBValue() const { return Bits(6, 5); }
VFPNRegValue(VFPRegPrecision pre)537   inline int VFPNRegValue(VFPRegPrecision pre) {
538     return VFPGlueRegValue(pre, 16, 7);
539   }
VFPMRegValue(VFPRegPrecision pre)540   inline int VFPMRegValue(VFPRegPrecision pre) {
541     return VFPGlueRegValue(pre, 0, 5);
542   }
VFPDRegValue(VFPRegPrecision pre)543   inline int VFPDRegValue(VFPRegPrecision pre) {
544     return VFPGlueRegValue(pre, 12, 22);
545   }
546 
547   // Fields used in Data processing instructions
OpcodeValue()548   inline int OpcodeValue() const {
549     return static_cast<Opcode>(Bits(24, 21));
550   }
OpcodeField()551   inline Opcode OpcodeField() const {
552     return static_cast<Opcode>(BitField(24, 21));
553   }
SValue()554   inline int SValue() const { return Bit(20); }
555     // with register
RmValue()556   inline int RmValue() const { return Bits(3, 0); }
557   DECLARE_STATIC_ACCESSOR(RmValue);
ShiftValue()558   inline int ShiftValue() const { return static_cast<ShiftOp>(Bits(6, 5)); }
ShiftField()559   inline ShiftOp ShiftField() const {
560     return static_cast<ShiftOp>(BitField(6, 5));
561   }
RegShiftValue()562   inline int RegShiftValue() const { return Bit(4); }
RsValue()563   inline int RsValue() const { return Bits(11, 8); }
ShiftAmountValue()564   inline int ShiftAmountValue() const { return Bits(11, 7); }
565     // with immediate
RotateValue()566   inline int RotateValue() const { return Bits(11, 8); }
567   DECLARE_STATIC_ACCESSOR(RotateValue);
Immed8Value()568   inline int Immed8Value() const { return Bits(7, 0); }
569   DECLARE_STATIC_ACCESSOR(Immed8Value);
Immed4Value()570   inline int Immed4Value() const { return Bits(19, 16); }
ImmedMovwMovtValue()571   inline int ImmedMovwMovtValue() const {
572       return Immed4Value() << 12 | Offset12Value(); }
573   DECLARE_STATIC_ACCESSOR(ImmedMovwMovtValue);
574 
575   // Fields used in Load/Store instructions
PUValue()576   inline int PUValue() const { return Bits(24, 23); }
PUField()577   inline int PUField() const { return BitField(24, 23); }
BValue()578   inline int  BValue() const { return Bit(22); }
WValue()579   inline int  WValue() const { return Bit(21); }
LValue()580   inline int  LValue() const { return Bit(20); }
581     // with register uses same fields as Data processing instructions above
582     // with immediate
Offset12Value()583   inline int Offset12Value() const { return Bits(11, 0); }
584     // multiple
RlistValue()585   inline int RlistValue() const { return Bits(15, 0); }
586     // extra loads and stores
SignValue()587   inline int SignValue() const { return Bit(6); }
HValue()588   inline int HValue() const { return Bit(5); }
ImmedHValue()589   inline int ImmedHValue() const { return Bits(11, 8); }
ImmedLValue()590   inline int ImmedLValue() const { return Bits(3, 0); }
591 
592   // Fields used in Branch instructions
LinkValue()593   inline int LinkValue() const { return Bit(24); }
SImmed24Value()594   inline int SImmed24Value() const { return ((InstructionBits() << 8) >> 8); }
595 
596   // Fields used in Software interrupt instructions
SvcValue()597   inline SoftwareInterruptCodes SvcValue() const {
598     return static_cast<SoftwareInterruptCodes>(Bits(23, 0));
599   }
600 
601   // Test for special encodings of type 0 instructions (extra loads and stores,
602   // as well as multiplications).
IsSpecialType0()603   inline bool IsSpecialType0() const { return (Bit(7) == 1) && (Bit(4) == 1); }
604 
605   // Test for miscellaneous instructions encodings of type 0 instructions.
IsMiscType0()606   inline bool IsMiscType0() const { return (Bit(24) == 1)
607                                            && (Bit(23) == 0)
608                                            && (Bit(20) == 0)
609                                            && ((Bit(7) == 0)); }
610 
611   // Test for a nop instruction, which falls under type 1.
IsNopType1()612   inline bool IsNopType1() const { return Bits(24, 0) == 0x0120F000; }
613 
614   // Test for a stop instruction.
IsStop()615   inline bool IsStop() const {
616     return (TypeValue() == 7) && (Bit(24) == 1) && (SvcValue() >= kStopCode);
617   }
618 
619   // Special accessors that test for existence of a value.
HasS()620   inline bool HasS()    const { return SValue() == 1; }
HasB()621   inline bool HasB()    const { return BValue() == 1; }
HasW()622   inline bool HasW()    const { return WValue() == 1; }
HasL()623   inline bool HasL()    const { return LValue() == 1; }
HasU()624   inline bool HasU()    const { return UValue() == 1; }
HasSign()625   inline bool HasSign() const { return SignValue() == 1; }
HasH()626   inline bool HasH()    const { return HValue() == 1; }
HasLink()627   inline bool HasLink() const { return LinkValue() == 1; }
628 
629   // Decoding the double immediate in the vmov instruction.
630   double DoubleImmedVmov() const;
631 
632   // Instructions are read of out a code stream. The only way to get a
633   // reference to an instruction is to convert a pointer. There is no way
634   // to allocate or create instances of class Instruction.
635   // Use the At(pc) function to create references to Instruction.
At(byte * pc)636   static Instruction* At(byte* pc) {
637     return reinterpret_cast<Instruction*>(pc);
638   }
639 
640 
641  private:
642   // Join split register codes, depending on single or double precision.
643   // four_bit is the position of the least-significant bit of the four
644   // bit specifier. one_bit is the position of the additional single bit
645   // specifier.
VFPGlueRegValue(VFPRegPrecision pre,int four_bit,int one_bit)646   inline int VFPGlueRegValue(VFPRegPrecision pre, int four_bit, int one_bit) {
647     if (pre == kSinglePrecision) {
648       return (Bits(four_bit + 3, four_bit) << 1) | Bit(one_bit);
649     }
650     return (Bit(one_bit) << 4) | Bits(four_bit + 3, four_bit);
651   }
652 
653   // We need to prevent the creation of instances of class Instruction.
654   DISALLOW_IMPLICIT_CONSTRUCTORS(Instruction);
655 };
656 
657 
658 // Helper functions for converting between register numbers and names.
659 class Registers {
660  public:
661   // Return the name of the register.
662   static const char* Name(int reg);
663 
664   // Lookup the register number for the name provided.
665   static int Number(const char* name);
666 
667   struct RegisterAlias {
668     int reg;
669     const char* name;
670   };
671 
672  private:
673   static const char* names_[kNumRegisters];
674   static const RegisterAlias aliases_[];
675 };
676 
677 // Helper functions for converting between VFP register numbers and names.
678 class VFPRegisters {
679  public:
680   // Return the name of the register.
681   static const char* Name(int reg, bool is_double);
682 
683   // Lookup the register number for the name provided.
684   // Set flag pointed by is_double to true if register
685   // is double-precision.
686   static int Number(const char* name, bool* is_double);
687 
688  private:
689   static const char* names_[kNumVFPRegisters];
690 };
691 
692 
693 } }  // namespace v8::internal
694 
695 #endif  // V8_ARM_CONSTANTS_ARM_H_
696