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1 // Copyright 2011 the V8 project authors. All rights reserved.
2 // Redistribution and use in source and binary forms, with or without
3 // modification, are permitted provided that the following conditions are
4 // met:
5 //
6 //     * Redistributions of source code must retain the above copyright
7 //       notice, this list of conditions and the following disclaimer.
8 //     * Redistributions in binary form must reproduce the above
9 //       copyright notice, this list of conditions and the following
10 //       disclaimer in the documentation and/or other materials provided
11 //       with the distribution.
12 //     * Neither the name of Google Inc. nor the names of its
13 //       contributors may be used to endorse or promote products derived
14 //       from this software without specific prior written permission.
15 //
16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 
28 // A Disassembler object is used to disassemble a block of code instruction by
29 // instruction. The default implementation of the NameConverter object can be
30 // overriden to modify register names or to do symbol lookup on addresses.
31 //
32 // The example below will disassemble a block of code and print it to stdout.
33 //
34 //   NameConverter converter;
35 //   Disassembler d(converter);
36 //   for (byte* pc = begin; pc < end;) {
37 //     v8::internal::EmbeddedVector<char, 256> buffer;
38 //     byte* prev_pc = pc;
39 //     pc += d.InstructionDecode(buffer, pc);
40 //     printf("%p    %08x      %s\n",
41 //            prev_pc, *reinterpret_cast<int32_t*>(prev_pc), buffer);
42 //   }
43 //
44 // The Disassembler class also has a convenience method to disassemble a block
45 // of code into a FILE*, meaning that the above functionality could also be
46 // achieved by just calling Disassembler::Disassemble(stdout, begin, end);
47 
48 
49 #include <assert.h>
50 #include <stdio.h>
51 #include <stdarg.h>
52 #include <string.h>
53 #ifndef WIN32
54 #include <stdint.h>
55 #endif
56 
57 #include "v8.h"
58 
59 #if defined(V8_TARGET_ARCH_ARM)
60 
61 #include "constants-arm.h"
62 #include "disasm.h"
63 #include "macro-assembler.h"
64 #include "platform.h"
65 
66 
67 namespace v8 {
68 namespace internal {
69 
70 
71 //------------------------------------------------------------------------------
72 
73 // Decoder decodes and disassembles instructions into an output buffer.
74 // It uses the converter to convert register names and call destinations into
75 // more informative description.
76 class Decoder {
77  public:
Decoder(const disasm::NameConverter & converter,Vector<char> out_buffer)78   Decoder(const disasm::NameConverter& converter,
79           Vector<char> out_buffer)
80     : converter_(converter),
81       out_buffer_(out_buffer),
82       out_buffer_pos_(0) {
83     out_buffer_[out_buffer_pos_] = '\0';
84   }
85 
~Decoder()86   ~Decoder() {}
87 
88   // Writes one disassembled instruction into 'buffer' (0-terminated).
89   // Returns the length of the disassembled machine instruction in bytes.
90   int InstructionDecode(byte* instruction);
91 
92   static bool IsConstantPoolAt(byte* instr_ptr);
93   static int ConstantPoolSizeAt(byte* instr_ptr);
94 
95  private:
96   // Bottleneck functions to print into the out_buffer.
97   void PrintChar(const char ch);
98   void Print(const char* str);
99 
100   // Printing of common values.
101   void PrintRegister(int reg);
102   void PrintSRegister(int reg);
103   void PrintDRegister(int reg);
104   int FormatVFPRegister(Instruction* instr, const char* format);
105   void PrintMovwMovt(Instruction* instr);
106   int FormatVFPinstruction(Instruction* instr, const char* format);
107   void PrintCondition(Instruction* instr);
108   void PrintShiftRm(Instruction* instr);
109   void PrintShiftImm(Instruction* instr);
110   void PrintShiftSat(Instruction* instr);
111   void PrintPU(Instruction* instr);
112   void PrintSoftwareInterrupt(SoftwareInterruptCodes svc);
113 
114   // Handle formatting of instructions and their options.
115   int FormatRegister(Instruction* instr, const char* option);
116   int FormatOption(Instruction* instr, const char* option);
117   void Format(Instruction* instr, const char* format);
118   void Unknown(Instruction* instr);
119 
120   // Each of these functions decodes one particular instruction type, a 3-bit
121   // field in the instruction encoding.
122   // Types 0 and 1 are combined as they are largely the same except for the way
123   // they interpret the shifter operand.
124   void DecodeType01(Instruction* instr);
125   void DecodeType2(Instruction* instr);
126   void DecodeType3(Instruction* instr);
127   void DecodeType4(Instruction* instr);
128   void DecodeType5(Instruction* instr);
129   void DecodeType6(Instruction* instr);
130   // Type 7 includes special Debugger instructions.
131   int DecodeType7(Instruction* instr);
132   // For VFP support.
133   void DecodeTypeVFP(Instruction* instr);
134   void DecodeType6CoprocessorIns(Instruction* instr);
135 
136   void DecodeVMOVBetweenCoreAndSinglePrecisionRegisters(Instruction* instr);
137   void DecodeVCMP(Instruction* instr);
138   void DecodeVCVTBetweenDoubleAndSingle(Instruction* instr);
139   void DecodeVCVTBetweenFloatingPointAndInteger(Instruction* instr);
140 
141   const disasm::NameConverter& converter_;
142   Vector<char> out_buffer_;
143   int out_buffer_pos_;
144 
145   DISALLOW_COPY_AND_ASSIGN(Decoder);
146 };
147 
148 
149 // Support for assertions in the Decoder formatting functions.
150 #define STRING_STARTS_WITH(string, compare_string) \
151   (strncmp(string, compare_string, strlen(compare_string)) == 0)
152 
153 
154 // Append the ch to the output buffer.
PrintChar(const char ch)155 void Decoder::PrintChar(const char ch) {
156   out_buffer_[out_buffer_pos_++] = ch;
157 }
158 
159 
160 // Append the str to the output buffer.
Print(const char * str)161 void Decoder::Print(const char* str) {
162   char cur = *str++;
163   while (cur != '\0' && (out_buffer_pos_ < (out_buffer_.length() - 1))) {
164     PrintChar(cur);
165     cur = *str++;
166   }
167   out_buffer_[out_buffer_pos_] = 0;
168 }
169 
170 
171 // These condition names are defined in a way to match the native disassembler
172 // formatting. See for example the command "objdump -d <binary file>".
173 static const char* cond_names[kNumberOfConditions] = {
174   "eq", "ne", "cs" , "cc" , "mi" , "pl" , "vs" , "vc" ,
175   "hi", "ls", "ge", "lt", "gt", "le", "", "invalid",
176 };
177 
178 
179 // Print the condition guarding the instruction.
PrintCondition(Instruction * instr)180 void Decoder::PrintCondition(Instruction* instr) {
181   Print(cond_names[instr->ConditionValue()]);
182 }
183 
184 
185 // Print the register name according to the active name converter.
PrintRegister(int reg)186 void Decoder::PrintRegister(int reg) {
187   Print(converter_.NameOfCPURegister(reg));
188 }
189 
190 // Print the VFP S register name according to the active name converter.
PrintSRegister(int reg)191 void Decoder::PrintSRegister(int reg) {
192   Print(VFPRegisters::Name(reg, false));
193 }
194 
195 // Print the  VFP D register name according to the active name converter.
PrintDRegister(int reg)196 void Decoder::PrintDRegister(int reg) {
197   Print(VFPRegisters::Name(reg, true));
198 }
199 
200 
201 // These shift names are defined in a way to match the native disassembler
202 // formatting. See for example the command "objdump -d <binary file>".
203 static const char* const shift_names[kNumberOfShifts] = {
204   "lsl", "lsr", "asr", "ror"
205 };
206 
207 
208 // Print the register shift operands for the instruction. Generally used for
209 // data processing instructions.
PrintShiftRm(Instruction * instr)210 void Decoder::PrintShiftRm(Instruction* instr) {
211   ShiftOp shift = instr->ShiftField();
212   int shift_index = instr->ShiftValue();
213   int shift_amount = instr->ShiftAmountValue();
214   int rm = instr->RmValue();
215 
216   PrintRegister(rm);
217 
218   if ((instr->RegShiftValue() == 0) && (shift == LSL) && (shift_amount == 0)) {
219     // Special case for using rm only.
220     return;
221   }
222   if (instr->RegShiftValue() == 0) {
223     // by immediate
224     if ((shift == ROR) && (shift_amount == 0)) {
225       Print(", RRX");
226       return;
227     } else if (((shift == LSR) || (shift == ASR)) && (shift_amount == 0)) {
228       shift_amount = 32;
229     }
230     out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_,
231                                     ", %s #%d",
232                                     shift_names[shift_index],
233                                     shift_amount);
234   } else {
235     // by register
236     int rs = instr->RsValue();
237     out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_,
238                                     ", %s ", shift_names[shift_index]);
239     PrintRegister(rs);
240   }
241 }
242 
243 
244 // Print the immediate operand for the instruction. Generally used for data
245 // processing instructions.
PrintShiftImm(Instruction * instr)246 void Decoder::PrintShiftImm(Instruction* instr) {
247   int rotate = instr->RotateValue() * 2;
248   int immed8 = instr->Immed8Value();
249   int imm = (immed8 >> rotate) | (immed8 << (32 - rotate));
250   out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_,
251                                   "#%d", imm);
252 }
253 
254 
255 // Print the optional shift and immediate used by saturating instructions.
PrintShiftSat(Instruction * instr)256 void Decoder::PrintShiftSat(Instruction* instr) {
257   int shift = instr->Bits(11, 7);
258   if (shift > 0) {
259     out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_,
260                                     ", %s #%d",
261                                     shift_names[instr->Bit(6) * 2],
262                                     instr->Bits(11, 7));
263   }
264 }
265 
266 
267 // Print PU formatting to reduce complexity of FormatOption.
PrintPU(Instruction * instr)268 void Decoder::PrintPU(Instruction* instr) {
269   switch (instr->PUField()) {
270     case da_x: {
271       Print("da");
272       break;
273     }
274     case ia_x: {
275       Print("ia");
276       break;
277     }
278     case db_x: {
279       Print("db");
280       break;
281     }
282     case ib_x: {
283       Print("ib");
284       break;
285     }
286     default: {
287       UNREACHABLE();
288       break;
289     }
290   }
291 }
292 
293 
294 // Print SoftwareInterrupt codes. Factoring this out reduces the complexity of
295 // the FormatOption method.
PrintSoftwareInterrupt(SoftwareInterruptCodes svc)296 void Decoder::PrintSoftwareInterrupt(SoftwareInterruptCodes svc) {
297   switch (svc) {
298     case kCallRtRedirected:
299       Print("call rt redirected");
300       return;
301     case kBreakpoint:
302       Print("breakpoint");
303       return;
304     default:
305       if (svc >= kStopCode) {
306         out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_,
307                                         "%d - 0x%x",
308                                         svc & kStopCodeMask,
309                                         svc & kStopCodeMask);
310       } else {
311         out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_,
312                                         "%d",
313                                         svc);
314       }
315       return;
316   }
317 }
318 
319 
320 // Handle all register based formatting in this function to reduce the
321 // complexity of FormatOption.
FormatRegister(Instruction * instr,const char * format)322 int Decoder::FormatRegister(Instruction* instr, const char* format) {
323   ASSERT(format[0] == 'r');
324   if (format[1] == 'n') {  // 'rn: Rn register
325     int reg = instr->RnValue();
326     PrintRegister(reg);
327     return 2;
328   } else if (format[1] == 'd') {  // 'rd: Rd register
329     int reg = instr->RdValue();
330     PrintRegister(reg);
331     return 2;
332   } else if (format[1] == 's') {  // 'rs: Rs register
333     int reg = instr->RsValue();
334     PrintRegister(reg);
335     return 2;
336   } else if (format[1] == 'm') {  // 'rm: Rm register
337     int reg = instr->RmValue();
338     PrintRegister(reg);
339     return 2;
340   } else if (format[1] == 't') {  // 'rt: Rt register
341     int reg = instr->RtValue();
342     PrintRegister(reg);
343     return 2;
344   } else if (format[1] == 'l') {
345     // 'rlist: register list for load and store multiple instructions
346     ASSERT(STRING_STARTS_WITH(format, "rlist"));
347     int rlist = instr->RlistValue();
348     int reg = 0;
349     Print("{");
350     // Print register list in ascending order, by scanning the bit mask.
351     while (rlist != 0) {
352       if ((rlist & 1) != 0) {
353         PrintRegister(reg);
354         if ((rlist >> 1) != 0) {
355           Print(", ");
356         }
357       }
358       reg++;
359       rlist >>= 1;
360     }
361     Print("}");
362     return 5;
363   }
364   UNREACHABLE();
365   return -1;
366 }
367 
368 
369 // Handle all VFP register based formatting in this function to reduce the
370 // complexity of FormatOption.
FormatVFPRegister(Instruction * instr,const char * format)371 int Decoder::FormatVFPRegister(Instruction* instr, const char* format) {
372   ASSERT((format[0] == 'S') || (format[0] == 'D'));
373 
374   VFPRegPrecision precision =
375       format[0] == 'D' ? kDoublePrecision : kSinglePrecision;
376 
377   int retval = 2;
378   int reg = -1;
379   if (format[1] == 'n') {
380     reg = instr->VFPNRegValue(precision);
381   } else if (format[1] == 'm') {
382     reg = instr->VFPMRegValue(precision);
383   } else if (format[1] == 'd') {
384     reg = instr->VFPDRegValue(precision);
385     if (format[2] == '+') {
386       int immed8 = instr->Immed8Value();
387       if (format[0] == 'S') reg += immed8 - 1;
388       if (format[0] == 'D') reg += (immed8 / 2 - 1);
389     }
390     if (format[2] == '+') retval = 3;
391   } else {
392     UNREACHABLE();
393   }
394 
395   if (precision == kSinglePrecision) {
396     PrintSRegister(reg);
397   } else {
398     PrintDRegister(reg);
399   }
400 
401   return retval;
402 }
403 
404 
FormatVFPinstruction(Instruction * instr,const char * format)405 int Decoder::FormatVFPinstruction(Instruction* instr, const char* format) {
406     Print(format);
407     return 0;
408 }
409 
410 
411 // Print the movw or movt instruction.
PrintMovwMovt(Instruction * instr)412 void Decoder::PrintMovwMovt(Instruction* instr) {
413   int imm = instr->ImmedMovwMovtValue();
414   int rd = instr->RdValue();
415   PrintRegister(rd);
416   out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_,
417                                   ", #%d", imm);
418 }
419 
420 
421 // FormatOption takes a formatting string and interprets it based on
422 // the current instructions. The format string points to the first
423 // character of the option string (the option escape has already been
424 // consumed by the caller.)  FormatOption returns the number of
425 // characters that were consumed from the formatting string.
FormatOption(Instruction * instr,const char * format)426 int Decoder::FormatOption(Instruction* instr, const char* format) {
427   switch (format[0]) {
428     case 'a': {  // 'a: accumulate multiplies
429       if (instr->Bit(21) == 0) {
430         Print("ul");
431       } else {
432         Print("la");
433       }
434       return 1;
435     }
436     case 'b': {  // 'b: byte loads or stores
437       if (instr->HasB()) {
438         Print("b");
439       }
440       return 1;
441     }
442     case 'c': {  // 'cond: conditional execution
443       ASSERT(STRING_STARTS_WITH(format, "cond"));
444       PrintCondition(instr);
445       return 4;
446     }
447     case 'd': {  // 'd: vmov double immediate.
448       double d = instr->DoubleImmedVmov();
449       out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_,
450                                       "#%g", d);
451       return 1;
452     }
453     case 'f': {  // 'f: bitfield instructions - v7 and above.
454       uint32_t lsbit = instr->Bits(11, 7);
455       uint32_t width = instr->Bits(20, 16) + 1;
456       if (instr->Bit(21) == 0) {
457         // BFC/BFI:
458         // Bits 20-16 represent most-significant bit. Covert to width.
459         width -= lsbit;
460         ASSERT(width > 0);
461       }
462       ASSERT((width + lsbit) <= 32);
463       out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_,
464                                       "#%d, #%d", lsbit, width);
465       return 1;
466     }
467     case 'h': {  // 'h: halfword operation for extra loads and stores
468       if (instr->HasH()) {
469         Print("h");
470       } else {
471         Print("b");
472       }
473       return 1;
474     }
475     case 'i': {  // 'i: immediate value from adjacent bits.
476       // Expects tokens in the form imm%02d@%02d, i.e. imm05@07, imm10@16
477       int width = (format[3] - '0') * 10 + (format[4] - '0');
478       int lsb   = (format[6] - '0') * 10 + (format[7] - '0');
479 
480       ASSERT((width >= 1) && (width <= 32));
481       ASSERT((lsb >= 0) && (lsb <= 31));
482       ASSERT((width + lsb) <= 32);
483 
484       out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_,
485                                       "%d",
486                                       instr->Bits(width + lsb - 1, lsb));
487       return 8;
488     }
489     case 'l': {  // 'l: branch and link
490       if (instr->HasLink()) {
491         Print("l");
492       }
493       return 1;
494     }
495     case 'm': {
496       if (format[1] == 'w') {
497         // 'mw: movt/movw instructions.
498         PrintMovwMovt(instr);
499         return 2;
500       }
501       if (format[1] == 'e') {  // 'memop: load/store instructions.
502         ASSERT(STRING_STARTS_WITH(format, "memop"));
503         if (instr->HasL()) {
504           Print("ldr");
505         } else {
506           if ((instr->Bits(27, 25) == 0) && (instr->Bit(20) == 0) &&
507               (instr->Bits(7, 6) == 3) && (instr->Bit(4) == 1)) {
508             if (instr->Bit(5) == 1) {
509               Print("strd");
510             } else {
511               Print("ldrd");
512             }
513             return 5;
514           }
515           Print("str");
516         }
517         return 5;
518       }
519       // 'msg: for simulator break instructions
520       ASSERT(STRING_STARTS_WITH(format, "msg"));
521       byte* str =
522           reinterpret_cast<byte*>(instr->InstructionBits() & 0x0fffffff);
523       out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_,
524                                       "%s", converter_.NameInCode(str));
525       return 3;
526     }
527     case 'o': {
528       if ((format[3] == '1') && (format[4] == '2')) {
529         // 'off12: 12-bit offset for load and store instructions
530         ASSERT(STRING_STARTS_WITH(format, "off12"));
531         out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_,
532                                         "%d", instr->Offset12Value());
533         return 5;
534       } else if (format[3] == '0') {
535         // 'off0to3and8to19 16-bit immediate encoded in bits 19-8 and 3-0.
536         ASSERT(STRING_STARTS_WITH(format, "off0to3and8to19"));
537         out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_,
538                                         "%d",
539                                         (instr->Bits(19, 8) << 4) +
540                                         instr->Bits(3, 0));
541         return 15;
542       }
543       // 'off8: 8-bit offset for extra load and store instructions
544       ASSERT(STRING_STARTS_WITH(format, "off8"));
545       int offs8 = (instr->ImmedHValue() << 4) | instr->ImmedLValue();
546       out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_,
547                                       "%d", offs8);
548       return 4;
549     }
550     case 'p': {  // 'pu: P and U bits for load and store instructions
551       ASSERT(STRING_STARTS_WITH(format, "pu"));
552       PrintPU(instr);
553       return 2;
554     }
555     case 'r': {
556       return FormatRegister(instr, format);
557     }
558     case 's': {
559       if (format[1] == 'h') {  // 'shift_op or 'shift_rm or 'shift_sat.
560         if (format[6] == 'o') {  // 'shift_op
561           ASSERT(STRING_STARTS_WITH(format, "shift_op"));
562           if (instr->TypeValue() == 0) {
563             PrintShiftRm(instr);
564           } else {
565             ASSERT(instr->TypeValue() == 1);
566             PrintShiftImm(instr);
567           }
568           return 8;
569         } else if (format[6] == 's') {  // 'shift_sat.
570           ASSERT(STRING_STARTS_WITH(format, "shift_sat"));
571           PrintShiftSat(instr);
572           return 9;
573         } else {  // 'shift_rm
574           ASSERT(STRING_STARTS_WITH(format, "shift_rm"));
575           PrintShiftRm(instr);
576           return 8;
577         }
578       } else if (format[1] == 'v') {  // 'svc
579         ASSERT(STRING_STARTS_WITH(format, "svc"));
580         PrintSoftwareInterrupt(instr->SvcValue());
581         return 3;
582       } else if (format[1] == 'i') {  // 'sign: signed extra loads and stores
583         ASSERT(STRING_STARTS_WITH(format, "sign"));
584         if (instr->HasSign()) {
585           Print("s");
586         }
587         return 4;
588       }
589       // 's: S field of data processing instructions
590       if (instr->HasS()) {
591         Print("s");
592       }
593       return 1;
594     }
595     case 't': {  // 'target: target of branch instructions
596       ASSERT(STRING_STARTS_WITH(format, "target"));
597       int off = (instr->SImmed24Value() << 2) + 8;
598       out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_,
599                                       "%+d -> %s",
600                                       off,
601                                       converter_.NameOfAddress(
602                                         reinterpret_cast<byte*>(instr) + off));
603       return 6;
604     }
605     case 'u': {  // 'u: signed or unsigned multiplies
606       // The manual gets the meaning of bit 22 backwards in the multiply
607       // instruction overview on page A3.16.2.  The instructions that
608       // exist in u and s variants are the following:
609       // smull A4.1.87
610       // umull A4.1.129
611       // umlal A4.1.128
612       // smlal A4.1.76
613       // For these 0 means u and 1 means s.  As can be seen on their individual
614       // pages.  The other 18 mul instructions have the bit set or unset in
615       // arbitrary ways that are unrelated to the signedness of the instruction.
616       // None of these 18 instructions exist in both a 'u' and an 's' variant.
617 
618       if (instr->Bit(22) == 0) {
619         Print("u");
620       } else {
621         Print("s");
622       }
623       return 1;
624     }
625     case 'v': {
626       return FormatVFPinstruction(instr, format);
627     }
628     case 'S':
629     case 'D': {
630       return FormatVFPRegister(instr, format);
631     }
632     case 'w': {  // 'w: W field of load and store instructions
633       if (instr->HasW()) {
634         Print("!");
635       }
636       return 1;
637     }
638     default: {
639       UNREACHABLE();
640       break;
641     }
642   }
643   UNREACHABLE();
644   return -1;
645 }
646 
647 
648 // Format takes a formatting string for a whole instruction and prints it into
649 // the output buffer. All escaped options are handed to FormatOption to be
650 // parsed further.
Format(Instruction * instr,const char * format)651 void Decoder::Format(Instruction* instr, const char* format) {
652   char cur = *format++;
653   while ((cur != 0) && (out_buffer_pos_ < (out_buffer_.length() - 1))) {
654     if (cur == '\'') {  // Single quote is used as the formatting escape.
655       format += FormatOption(instr, format);
656     } else {
657       out_buffer_[out_buffer_pos_++] = cur;
658     }
659     cur = *format++;
660   }
661   out_buffer_[out_buffer_pos_]  = '\0';
662 }
663 
664 
665 // The disassembler may end up decoding data inlined in the code. We do not want
666 // it to crash if the data does not ressemble any known instruction.
667 #define VERIFY(condition) \
668 if(!(condition)) {        \
669   Unknown(instr);         \
670   return;                 \
671 }
672 
673 
674 // For currently unimplemented decodings the disassembler calls Unknown(instr)
675 // which will just print "unknown" of the instruction bits.
Unknown(Instruction * instr)676 void Decoder::Unknown(Instruction* instr) {
677   Format(instr, "unknown");
678 }
679 
680 
DecodeType01(Instruction * instr)681 void Decoder::DecodeType01(Instruction* instr) {
682   int type = instr->TypeValue();
683   if ((type == 0) && instr->IsSpecialType0()) {
684     // multiply instruction or extra loads and stores
685     if (instr->Bits(7, 4) == 9) {
686       if (instr->Bit(24) == 0) {
687         // multiply instructions
688         if (instr->Bit(23) == 0) {
689           if (instr->Bit(21) == 0) {
690             // The MUL instruction description (A 4.1.33) refers to Rd as being
691             // the destination for the operation, but it confusingly uses the
692             // Rn field to encode it.
693             Format(instr, "mul'cond's 'rn, 'rm, 'rs");
694           } else {
695             // The MLA instruction description (A 4.1.28) refers to the order
696             // of registers as "Rd, Rm, Rs, Rn". But confusingly it uses the
697             // Rn field to encode the Rd register and the Rd field to encode
698             // the Rn register.
699             Format(instr, "mla'cond's 'rn, 'rm, 'rs, 'rd");
700           }
701         } else {
702           // The signed/long multiply instructions use the terms RdHi and RdLo
703           // when referring to the target registers. They are mapped to the Rn
704           // and Rd fields as follows:
705           // RdLo == Rd field
706           // RdHi == Rn field
707           // The order of registers is: <RdLo>, <RdHi>, <Rm>, <Rs>
708           Format(instr, "'um'al'cond's 'rd, 'rn, 'rm, 'rs");
709         }
710       } else {
711         Unknown(instr);  // not used by V8
712       }
713     } else if ((instr->Bit(20) == 0) && ((instr->Bits(7, 4) & 0xd) == 0xd)) {
714       // ldrd, strd
715       switch (instr->PUField()) {
716         case da_x: {
717           if (instr->Bit(22) == 0) {
718             Format(instr, "'memop'cond's 'rd, ['rn], -'rm");
719           } else {
720             Format(instr, "'memop'cond's 'rd, ['rn], #-'off8");
721           }
722           break;
723         }
724         case ia_x: {
725           if (instr->Bit(22) == 0) {
726             Format(instr, "'memop'cond's 'rd, ['rn], +'rm");
727           } else {
728             Format(instr, "'memop'cond's 'rd, ['rn], #+'off8");
729           }
730           break;
731         }
732         case db_x: {
733           if (instr->Bit(22) == 0) {
734             Format(instr, "'memop'cond's 'rd, ['rn, -'rm]'w");
735           } else {
736             Format(instr, "'memop'cond's 'rd, ['rn, #-'off8]'w");
737           }
738           break;
739         }
740         case ib_x: {
741           if (instr->Bit(22) == 0) {
742             Format(instr, "'memop'cond's 'rd, ['rn, +'rm]'w");
743           } else {
744             Format(instr, "'memop'cond's 'rd, ['rn, #+'off8]'w");
745           }
746           break;
747         }
748         default: {
749           // The PU field is a 2-bit field.
750           UNREACHABLE();
751           break;
752         }
753       }
754     } else {
755       // extra load/store instructions
756       switch (instr->PUField()) {
757         case da_x: {
758           if (instr->Bit(22) == 0) {
759             Format(instr, "'memop'cond'sign'h 'rd, ['rn], -'rm");
760           } else {
761             Format(instr, "'memop'cond'sign'h 'rd, ['rn], #-'off8");
762           }
763           break;
764         }
765         case ia_x: {
766           if (instr->Bit(22) == 0) {
767             Format(instr, "'memop'cond'sign'h 'rd, ['rn], +'rm");
768           } else {
769             Format(instr, "'memop'cond'sign'h 'rd, ['rn], #+'off8");
770           }
771           break;
772         }
773         case db_x: {
774           if (instr->Bit(22) == 0) {
775             Format(instr, "'memop'cond'sign'h 'rd, ['rn, -'rm]'w");
776           } else {
777             Format(instr, "'memop'cond'sign'h 'rd, ['rn, #-'off8]'w");
778           }
779           break;
780         }
781         case ib_x: {
782           if (instr->Bit(22) == 0) {
783             Format(instr, "'memop'cond'sign'h 'rd, ['rn, +'rm]'w");
784           } else {
785             Format(instr, "'memop'cond'sign'h 'rd, ['rn, #+'off8]'w");
786           }
787           break;
788         }
789         default: {
790           // The PU field is a 2-bit field.
791           UNREACHABLE();
792           break;
793         }
794       }
795       return;
796     }
797   } else if ((type == 0) && instr->IsMiscType0()) {
798     if (instr->Bits(22, 21) == 1) {
799       switch (instr->BitField(7, 4)) {
800         case BX:
801           Format(instr, "bx'cond 'rm");
802           break;
803         case BLX:
804           Format(instr, "blx'cond 'rm");
805           break;
806         case BKPT:
807           Format(instr, "bkpt 'off0to3and8to19");
808           break;
809         default:
810           Unknown(instr);  // not used by V8
811           break;
812       }
813     } else if (instr->Bits(22, 21) == 3) {
814       switch (instr->BitField(7, 4)) {
815         case CLZ:
816           Format(instr, "clz'cond 'rd, 'rm");
817           break;
818         default:
819           Unknown(instr);  // not used by V8
820           break;
821       }
822     } else {
823       Unknown(instr);  // not used by V8
824     }
825   } else {
826     switch (instr->OpcodeField()) {
827       case AND: {
828         Format(instr, "and'cond's 'rd, 'rn, 'shift_op");
829         break;
830       }
831       case EOR: {
832         Format(instr, "eor'cond's 'rd, 'rn, 'shift_op");
833         break;
834       }
835       case SUB: {
836         Format(instr, "sub'cond's 'rd, 'rn, 'shift_op");
837         break;
838       }
839       case RSB: {
840         Format(instr, "rsb'cond's 'rd, 'rn, 'shift_op");
841         break;
842       }
843       case ADD: {
844         Format(instr, "add'cond's 'rd, 'rn, 'shift_op");
845         break;
846       }
847       case ADC: {
848         Format(instr, "adc'cond's 'rd, 'rn, 'shift_op");
849         break;
850       }
851       case SBC: {
852         Format(instr, "sbc'cond's 'rd, 'rn, 'shift_op");
853         break;
854       }
855       case RSC: {
856         Format(instr, "rsc'cond's 'rd, 'rn, 'shift_op");
857         break;
858       }
859       case TST: {
860         if (instr->HasS()) {
861           Format(instr, "tst'cond 'rn, 'shift_op");
862         } else {
863           Format(instr, "movw'cond 'mw");
864         }
865         break;
866       }
867       case TEQ: {
868         if (instr->HasS()) {
869           Format(instr, "teq'cond 'rn, 'shift_op");
870         } else {
871           // Other instructions matching this pattern are handled in the
872           // miscellaneous instructions part above.
873           UNREACHABLE();
874         }
875         break;
876       }
877       case CMP: {
878         if (instr->HasS()) {
879           Format(instr, "cmp'cond 'rn, 'shift_op");
880         } else {
881           Format(instr, "movt'cond 'mw");
882         }
883         break;
884       }
885       case CMN: {
886         if (instr->HasS()) {
887           Format(instr, "cmn'cond 'rn, 'shift_op");
888         } else {
889           // Other instructions matching this pattern are handled in the
890           // miscellaneous instructions part above.
891           UNREACHABLE();
892         }
893         break;
894       }
895       case ORR: {
896         Format(instr, "orr'cond's 'rd, 'rn, 'shift_op");
897         break;
898       }
899       case MOV: {
900         Format(instr, "mov'cond's 'rd, 'shift_op");
901         break;
902       }
903       case BIC: {
904         Format(instr, "bic'cond's 'rd, 'rn, 'shift_op");
905         break;
906       }
907       case MVN: {
908         Format(instr, "mvn'cond's 'rd, 'shift_op");
909         break;
910       }
911       default: {
912         // The Opcode field is a 4-bit field.
913         UNREACHABLE();
914         break;
915       }
916     }
917   }
918 }
919 
920 
DecodeType2(Instruction * instr)921 void Decoder::DecodeType2(Instruction* instr) {
922   switch (instr->PUField()) {
923     case da_x: {
924       if (instr->HasW()) {
925         Unknown(instr);  // not used in V8
926         return;
927       }
928       Format(instr, "'memop'cond'b 'rd, ['rn], #-'off12");
929       break;
930     }
931     case ia_x: {
932       if (instr->HasW()) {
933         Unknown(instr);  // not used in V8
934         return;
935       }
936       Format(instr, "'memop'cond'b 'rd, ['rn], #+'off12");
937       break;
938     }
939     case db_x: {
940       Format(instr, "'memop'cond'b 'rd, ['rn, #-'off12]'w");
941       break;
942     }
943     case ib_x: {
944       Format(instr, "'memop'cond'b 'rd, ['rn, #+'off12]'w");
945       break;
946     }
947     default: {
948       // The PU field is a 2-bit field.
949       UNREACHABLE();
950       break;
951     }
952   }
953 }
954 
955 
DecodeType3(Instruction * instr)956 void Decoder::DecodeType3(Instruction* instr) {
957   switch (instr->PUField()) {
958     case da_x: {
959       VERIFY(!instr->HasW());
960       Format(instr, "'memop'cond'b 'rd, ['rn], -'shift_rm");
961       break;
962     }
963     case ia_x: {
964       if (instr->HasW()) {
965         VERIFY(instr->Bits(5, 4) == 0x1);
966         if (instr->Bit(22) == 0x1) {
967           Format(instr, "usat 'rd, #'imm05@16, 'rm'shift_sat");
968         } else {
969           UNREACHABLE();  // SSAT.
970         }
971       } else {
972         Format(instr, "'memop'cond'b 'rd, ['rn], +'shift_rm");
973       }
974       break;
975     }
976     case db_x: {
977       Format(instr, "'memop'cond'b 'rd, ['rn, -'shift_rm]'w");
978       break;
979     }
980     case ib_x: {
981       if (instr->HasW() && (instr->Bits(6, 4) == 0x5)) {
982         uint32_t widthminus1 = static_cast<uint32_t>(instr->Bits(20, 16));
983         uint32_t lsbit = static_cast<uint32_t>(instr->Bits(11, 7));
984         uint32_t msbit = widthminus1 + lsbit;
985         if (msbit <= 31) {
986           if (instr->Bit(22)) {
987             Format(instr, "ubfx'cond 'rd, 'rm, 'f");
988           } else {
989             Format(instr, "sbfx'cond 'rd, 'rm, 'f");
990           }
991         } else {
992           UNREACHABLE();
993         }
994       } else if (!instr->HasW() && (instr->Bits(6, 4) == 0x1)) {
995         uint32_t lsbit = static_cast<uint32_t>(instr->Bits(11, 7));
996         uint32_t msbit = static_cast<uint32_t>(instr->Bits(20, 16));
997         if (msbit >= lsbit) {
998           if (instr->RmValue() == 15) {
999             Format(instr, "bfc'cond 'rd, 'f");
1000           } else {
1001             Format(instr, "bfi'cond 'rd, 'rm, 'f");
1002           }
1003         } else {
1004           UNREACHABLE();
1005         }
1006       } else {
1007         Format(instr, "'memop'cond'b 'rd, ['rn, +'shift_rm]'w");
1008       }
1009       break;
1010     }
1011     default: {
1012       // The PU field is a 2-bit field.
1013       UNREACHABLE();
1014       break;
1015     }
1016   }
1017 }
1018 
1019 
DecodeType4(Instruction * instr)1020 void Decoder::DecodeType4(Instruction* instr) {
1021   if (instr->Bit(22) != 0) {
1022     // Privileged mode currently not supported.
1023     Unknown(instr);
1024   } else {
1025     if (instr->HasL()) {
1026       Format(instr, "ldm'cond'pu 'rn'w, 'rlist");
1027     } else {
1028       Format(instr, "stm'cond'pu 'rn'w, 'rlist");
1029     }
1030   }
1031 }
1032 
1033 
DecodeType5(Instruction * instr)1034 void Decoder::DecodeType5(Instruction* instr) {
1035   Format(instr, "b'l'cond 'target");
1036 }
1037 
1038 
DecodeType6(Instruction * instr)1039 void Decoder::DecodeType6(Instruction* instr) {
1040   DecodeType6CoprocessorIns(instr);
1041 }
1042 
1043 
DecodeType7(Instruction * instr)1044 int Decoder::DecodeType7(Instruction* instr) {
1045   if (instr->Bit(24) == 1) {
1046     if (instr->SvcValue() >= kStopCode) {
1047       Format(instr, "stop'cond 'svc");
1048       // Also print the stop message. Its address is encoded
1049       // in the following 4 bytes.
1050       out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_,
1051                                       "\n  %p  %08x       stop message: %s",
1052                                       reinterpret_cast<int32_t*>(instr
1053                                                      + Instruction::kInstrSize),
1054                                       *reinterpret_cast<char**>(instr
1055                                                     + Instruction::kInstrSize),
1056                                       *reinterpret_cast<char**>(instr
1057                                                     + Instruction::kInstrSize));
1058       // We have decoded 2 * Instruction::kInstrSize bytes.
1059       return 2 * Instruction::kInstrSize;
1060     } else {
1061       Format(instr, "svc'cond 'svc");
1062     }
1063   } else {
1064     DecodeTypeVFP(instr);
1065   }
1066   return Instruction::kInstrSize;
1067 }
1068 
1069 
1070 // void Decoder::DecodeTypeVFP(Instruction* instr)
1071 // vmov: Sn = Rt
1072 // vmov: Rt = Sn
1073 // vcvt: Dd = Sm
1074 // vcvt: Sd = Dm
1075 // Dd = vabs(Dm)
1076 // Dd = vneg(Dm)
1077 // Dd = vadd(Dn, Dm)
1078 // Dd = vsub(Dn, Dm)
1079 // Dd = vmul(Dn, Dm)
1080 // Dd = vdiv(Dn, Dm)
1081 // vcmp(Dd, Dm)
1082 // vmrs
1083 // vmsr
1084 // Dd = vsqrt(Dm)
DecodeTypeVFP(Instruction * instr)1085 void Decoder::DecodeTypeVFP(Instruction* instr) {
1086   VERIFY((instr->TypeValue() == 7) && (instr->Bit(24) == 0x0) );
1087   VERIFY(instr->Bits(11, 9) == 0x5);
1088 
1089   if (instr->Bit(4) == 0) {
1090     if (instr->Opc1Value() == 0x7) {
1091       // Other data processing instructions
1092       if ((instr->Opc2Value() == 0x0) && (instr->Opc3Value() == 0x1)) {
1093         // vmov register to register.
1094         if (instr->SzValue() == 0x1) {
1095           Format(instr, "vmov.f64'cond 'Dd, 'Dm");
1096         } else {
1097           Format(instr, "vmov.f32'cond 'Sd, 'Sm");
1098         }
1099       } else if ((instr->Opc2Value() == 0x0) && (instr->Opc3Value() == 0x3)) {
1100         // vabs
1101         Format(instr, "vabs.f64'cond 'Dd, 'Dm");
1102       } else if ((instr->Opc2Value() == 0x1) && (instr->Opc3Value() == 0x1)) {
1103         // vneg
1104         Format(instr, "vneg.f64'cond 'Dd, 'Dm");
1105       } else if ((instr->Opc2Value() == 0x7) && (instr->Opc3Value() == 0x3)) {
1106         DecodeVCVTBetweenDoubleAndSingle(instr);
1107       } else if ((instr->Opc2Value() == 0x8) && (instr->Opc3Value() & 0x1)) {
1108         DecodeVCVTBetweenFloatingPointAndInteger(instr);
1109       } else if (((instr->Opc2Value() >> 1) == 0x6) &&
1110                  (instr->Opc3Value() & 0x1)) {
1111         DecodeVCVTBetweenFloatingPointAndInteger(instr);
1112       } else if (((instr->Opc2Value() == 0x4) || (instr->Opc2Value() == 0x5)) &&
1113                  (instr->Opc3Value() & 0x1)) {
1114         DecodeVCMP(instr);
1115       } else if (((instr->Opc2Value() == 0x1)) && (instr->Opc3Value() == 0x3)) {
1116         Format(instr, "vsqrt.f64'cond 'Dd, 'Dm");
1117       } else if (instr->Opc3Value() == 0x0) {
1118         if (instr->SzValue() == 0x1) {
1119           Format(instr, "vmov.f64'cond 'Dd, 'd");
1120         } else {
1121           Unknown(instr);  // Not used by V8.
1122         }
1123       } else {
1124         Unknown(instr);  // Not used by V8.
1125       }
1126     } else if (instr->Opc1Value() == 0x3) {
1127       if (instr->SzValue() == 0x1) {
1128         if (instr->Opc3Value() & 0x1) {
1129           Format(instr, "vsub.f64'cond 'Dd, 'Dn, 'Dm");
1130         } else {
1131           Format(instr, "vadd.f64'cond 'Dd, 'Dn, 'Dm");
1132         }
1133       } else {
1134         Unknown(instr);  // Not used by V8.
1135       }
1136     } else if ((instr->Opc1Value() == 0x2) && !(instr->Opc3Value() & 0x1)) {
1137       if (instr->SzValue() == 0x1) {
1138         Format(instr, "vmul.f64'cond 'Dd, 'Dn, 'Dm");
1139       } else {
1140         Unknown(instr);  // Not used by V8.
1141       }
1142     } else if ((instr->Opc1Value() == 0x4) && !(instr->Opc3Value() & 0x1)) {
1143       if (instr->SzValue() == 0x1) {
1144         Format(instr, "vdiv.f64'cond 'Dd, 'Dn, 'Dm");
1145       } else {
1146         Unknown(instr);  // Not used by V8.
1147       }
1148     } else {
1149       Unknown(instr);  // Not used by V8.
1150     }
1151   } else {
1152     if ((instr->VCValue() == 0x0) &&
1153         (instr->VAValue() == 0x0)) {
1154       DecodeVMOVBetweenCoreAndSinglePrecisionRegisters(instr);
1155     } else if ((instr->VCValue() == 0x0) &&
1156                (instr->VAValue() == 0x7) &&
1157                (instr->Bits(19, 16) == 0x1)) {
1158       if (instr->VLValue() == 0) {
1159         if (instr->Bits(15, 12) == 0xF) {
1160           Format(instr, "vmsr'cond FPSCR, APSR");
1161         } else {
1162           Format(instr, "vmsr'cond FPSCR, 'rt");
1163         }
1164       } else {
1165         if (instr->Bits(15, 12) == 0xF) {
1166           Format(instr, "vmrs'cond APSR, FPSCR");
1167         } else {
1168           Format(instr, "vmrs'cond 'rt, FPSCR");
1169         }
1170       }
1171     }
1172   }
1173 }
1174 
1175 
DecodeVMOVBetweenCoreAndSinglePrecisionRegisters(Instruction * instr)1176 void Decoder::DecodeVMOVBetweenCoreAndSinglePrecisionRegisters(
1177     Instruction* instr) {
1178   VERIFY((instr->Bit(4) == 1) && (instr->VCValue() == 0x0) &&
1179          (instr->VAValue() == 0x0));
1180 
1181   bool to_arm_register = (instr->VLValue() == 0x1);
1182 
1183   if (to_arm_register) {
1184     Format(instr, "vmov'cond 'rt, 'Sn");
1185   } else {
1186     Format(instr, "vmov'cond 'Sn, 'rt");
1187   }
1188 }
1189 
1190 
DecodeVCMP(Instruction * instr)1191 void Decoder::DecodeVCMP(Instruction* instr) {
1192   VERIFY((instr->Bit(4) == 0) && (instr->Opc1Value() == 0x7));
1193   VERIFY(((instr->Opc2Value() == 0x4) || (instr->Opc2Value() == 0x5)) &&
1194          (instr->Opc3Value() & 0x1));
1195 
1196   // Comparison.
1197   bool dp_operation = (instr->SzValue() == 1);
1198   bool raise_exception_for_qnan = (instr->Bit(7) == 0x1);
1199 
1200   if (dp_operation && !raise_exception_for_qnan) {
1201     if (instr->Opc2Value() == 0x4) {
1202       Format(instr, "vcmp.f64'cond 'Dd, 'Dm");
1203     } else if (instr->Opc2Value() == 0x5) {
1204       Format(instr, "vcmp.f64'cond 'Dd, #0.0");
1205     } else {
1206       Unknown(instr);  // invalid
1207     }
1208   } else {
1209     Unknown(instr);  // Not used by V8.
1210   }
1211 }
1212 
1213 
DecodeVCVTBetweenDoubleAndSingle(Instruction * instr)1214 void Decoder::DecodeVCVTBetweenDoubleAndSingle(Instruction* instr) {
1215   VERIFY((instr->Bit(4) == 0) && (instr->Opc1Value() == 0x7));
1216   VERIFY((instr->Opc2Value() == 0x7) && (instr->Opc3Value() == 0x3));
1217 
1218   bool double_to_single = (instr->SzValue() == 1);
1219 
1220   if (double_to_single) {
1221     Format(instr, "vcvt.f32.f64'cond 'Sd, 'Dm");
1222   } else {
1223     Format(instr, "vcvt.f64.f32'cond 'Dd, 'Sm");
1224   }
1225 }
1226 
1227 
DecodeVCVTBetweenFloatingPointAndInteger(Instruction * instr)1228 void Decoder::DecodeVCVTBetweenFloatingPointAndInteger(Instruction* instr) {
1229   VERIFY((instr->Bit(4) == 0) && (instr->Opc1Value() == 0x7));
1230   VERIFY(((instr->Opc2Value() == 0x8) && (instr->Opc3Value() & 0x1)) ||
1231          (((instr->Opc2Value() >> 1) == 0x6) && (instr->Opc3Value() & 0x1)));
1232 
1233   bool to_integer = (instr->Bit(18) == 1);
1234   bool dp_operation = (instr->SzValue() == 1);
1235   if (to_integer) {
1236     bool unsigned_integer = (instr->Bit(16) == 0);
1237 
1238     if (dp_operation) {
1239       if (unsigned_integer) {
1240         Format(instr, "vcvt.u32.f64'cond 'Sd, 'Dm");
1241       } else {
1242         Format(instr, "vcvt.s32.f64'cond 'Sd, 'Dm");
1243       }
1244     } else {
1245       if (unsigned_integer) {
1246         Format(instr, "vcvt.u32.f32'cond 'Sd, 'Sm");
1247       } else {
1248         Format(instr, "vcvt.s32.f32'cond 'Sd, 'Sm");
1249       }
1250     }
1251   } else {
1252     bool unsigned_integer = (instr->Bit(7) == 0);
1253 
1254     if (dp_operation) {
1255       if (unsigned_integer) {
1256         Format(instr, "vcvt.f64.u32'cond 'Dd, 'Sm");
1257       } else {
1258         Format(instr, "vcvt.f64.s32'cond 'Dd, 'Sm");
1259       }
1260     } else {
1261       if (unsigned_integer) {
1262         Format(instr, "vcvt.f32.u32'cond 'Sd, 'Sm");
1263       } else {
1264         Format(instr, "vcvt.f32.s32'cond 'Sd, 'Sm");
1265       }
1266     }
1267   }
1268 }
1269 
1270 
1271 // Decode Type 6 coprocessor instructions.
1272 // Dm = vmov(Rt, Rt2)
1273 // <Rt, Rt2> = vmov(Dm)
1274 // Ddst = MEM(Rbase + 4*offset).
1275 // MEM(Rbase + 4*offset) = Dsrc.
DecodeType6CoprocessorIns(Instruction * instr)1276 void Decoder::DecodeType6CoprocessorIns(Instruction* instr) {
1277   VERIFY(instr->TypeValue() == 6);
1278 
1279   if (instr->CoprocessorValue() == 0xA) {
1280     switch (instr->OpcodeValue()) {
1281       case 0x8:
1282       case 0xA:
1283         if (instr->HasL()) {
1284           Format(instr, "vldr'cond 'Sd, ['rn - 4*'imm08@00]");
1285         } else {
1286           Format(instr, "vstr'cond 'Sd, ['rn - 4*'imm08@00]");
1287         }
1288         break;
1289       case 0xC:
1290       case 0xE:
1291         if (instr->HasL()) {
1292           Format(instr, "vldr'cond 'Sd, ['rn + 4*'imm08@00]");
1293         } else {
1294           Format(instr, "vstr'cond 'Sd, ['rn + 4*'imm08@00]");
1295         }
1296         break;
1297       case 0x4:
1298       case 0x5:
1299       case 0x6:
1300       case 0x7:
1301       case 0x9:
1302       case 0xB: {
1303         bool to_vfp_register = (instr->VLValue() == 0x1);
1304         if (to_vfp_register) {
1305           Format(instr, "vldm'cond'pu 'rn'w, {'Sd-'Sd+}");
1306         } else {
1307           Format(instr, "vstm'cond'pu 'rn'w, {'Sd-'Sd+}");
1308         }
1309         break;
1310       }
1311       default:
1312         Unknown(instr);  // Not used by V8.
1313     }
1314   } else if (instr->CoprocessorValue() == 0xB) {
1315     switch (instr->OpcodeValue()) {
1316       case 0x2:
1317         // Load and store double to two GP registers
1318         if (instr->Bits(7, 4) != 0x1) {
1319           Unknown(instr);  // Not used by V8.
1320         } else if (instr->HasL()) {
1321           Format(instr, "vmov'cond 'rt, 'rn, 'Dm");
1322         } else {
1323           Format(instr, "vmov'cond 'Dm, 'rt, 'rn");
1324         }
1325         break;
1326       case 0x8:
1327         if (instr->HasL()) {
1328           Format(instr, "vldr'cond 'Dd, ['rn - 4*'imm08@00]");
1329         } else {
1330           Format(instr, "vstr'cond 'Dd, ['rn - 4*'imm08@00]");
1331         }
1332         break;
1333       case 0xC:
1334         if (instr->HasL()) {
1335           Format(instr, "vldr'cond 'Dd, ['rn + 4*'imm08@00]");
1336         } else {
1337           Format(instr, "vstr'cond 'Dd, ['rn + 4*'imm08@00]");
1338         }
1339         break;
1340       case 0x4:
1341       case 0x5:
1342       case 0x9: {
1343         bool to_vfp_register = (instr->VLValue() == 0x1);
1344         if (to_vfp_register) {
1345           Format(instr, "vldm'cond'pu 'rn'w, {'Dd-'Dd+}");
1346         } else {
1347           Format(instr, "vstm'cond'pu 'rn'w, {'Dd-'Dd+}");
1348         }
1349         break;
1350       }
1351       default:
1352         Unknown(instr);  // Not used by V8.
1353     }
1354   } else {
1355     Unknown(instr);  // Not used by V8.
1356   }
1357 }
1358 
1359 #undef VERIFIY
1360 
IsConstantPoolAt(byte * instr_ptr)1361 bool Decoder::IsConstantPoolAt(byte* instr_ptr) {
1362   int instruction_bits = *(reinterpret_cast<int*>(instr_ptr));
1363   return (instruction_bits & kConstantPoolMarkerMask) == kConstantPoolMarker;
1364 }
1365 
1366 
ConstantPoolSizeAt(byte * instr_ptr)1367 int Decoder::ConstantPoolSizeAt(byte* instr_ptr) {
1368   if (IsConstantPoolAt(instr_ptr)) {
1369     int instruction_bits = *(reinterpret_cast<int*>(instr_ptr));
1370     return instruction_bits & kConstantPoolLengthMask;
1371   } else {
1372     return -1;
1373   }
1374 }
1375 
1376 
1377 // Disassemble the instruction at *instr_ptr into the output buffer.
InstructionDecode(byte * instr_ptr)1378 int Decoder::InstructionDecode(byte* instr_ptr) {
1379   Instruction* instr = Instruction::At(instr_ptr);
1380   // Print raw instruction bytes.
1381   out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_,
1382                                   "%08x       ",
1383                                   instr->InstructionBits());
1384   if (instr->ConditionField() == kSpecialCondition) {
1385     Unknown(instr);
1386     return Instruction::kInstrSize;
1387   }
1388   int instruction_bits = *(reinterpret_cast<int*>(instr_ptr));
1389   if ((instruction_bits & kConstantPoolMarkerMask) == kConstantPoolMarker) {
1390     out_buffer_pos_ += OS::SNPrintF(out_buffer_ + out_buffer_pos_,
1391                                     "constant pool begin (length %d)",
1392                                     instruction_bits &
1393                                     kConstantPoolLengthMask);
1394     return Instruction::kInstrSize;
1395   }
1396   switch (instr->TypeValue()) {
1397     case 0:
1398     case 1: {
1399       DecodeType01(instr);
1400       break;
1401     }
1402     case 2: {
1403       DecodeType2(instr);
1404       break;
1405     }
1406     case 3: {
1407       DecodeType3(instr);
1408       break;
1409     }
1410     case 4: {
1411       DecodeType4(instr);
1412       break;
1413     }
1414     case 5: {
1415       DecodeType5(instr);
1416       break;
1417     }
1418     case 6: {
1419       DecodeType6(instr);
1420       break;
1421     }
1422     case 7: {
1423       return DecodeType7(instr);
1424     }
1425     default: {
1426       // The type field is 3-bits in the ARM encoding.
1427       UNREACHABLE();
1428       break;
1429     }
1430   }
1431   return Instruction::kInstrSize;
1432 }
1433 
1434 
1435 } }  // namespace v8::internal
1436 
1437 
1438 
1439 //------------------------------------------------------------------------------
1440 
1441 namespace disasm {
1442 
1443 
NameOfAddress(byte * addr) const1444 const char* NameConverter::NameOfAddress(byte* addr) const {
1445   v8::internal::OS::SNPrintF(tmp_buffer_, "%p", addr);
1446   return tmp_buffer_.start();
1447 }
1448 
1449 
NameOfConstant(byte * addr) const1450 const char* NameConverter::NameOfConstant(byte* addr) const {
1451   return NameOfAddress(addr);
1452 }
1453 
1454 
NameOfCPURegister(int reg) const1455 const char* NameConverter::NameOfCPURegister(int reg) const {
1456   return v8::internal::Registers::Name(reg);
1457 }
1458 
1459 
NameOfByteCPURegister(int reg) const1460 const char* NameConverter::NameOfByteCPURegister(int reg) const {
1461   UNREACHABLE();  // ARM does not have the concept of a byte register
1462   return "nobytereg";
1463 }
1464 
1465 
NameOfXMMRegister(int reg) const1466 const char* NameConverter::NameOfXMMRegister(int reg) const {
1467   UNREACHABLE();  // ARM does not have any XMM registers
1468   return "noxmmreg";
1469 }
1470 
1471 
NameInCode(byte * addr) const1472 const char* NameConverter::NameInCode(byte* addr) const {
1473   // The default name converter is called for unknown code. So we will not try
1474   // to access any memory.
1475   return "";
1476 }
1477 
1478 
1479 //------------------------------------------------------------------------------
1480 
Disassembler(const NameConverter & converter)1481 Disassembler::Disassembler(const NameConverter& converter)
1482     : converter_(converter) {}
1483 
1484 
~Disassembler()1485 Disassembler::~Disassembler() {}
1486 
1487 
InstructionDecode(v8::internal::Vector<char> buffer,byte * instruction)1488 int Disassembler::InstructionDecode(v8::internal::Vector<char> buffer,
1489                                     byte* instruction) {
1490   v8::internal::Decoder d(converter_, buffer);
1491   return d.InstructionDecode(instruction);
1492 }
1493 
1494 
ConstantPoolSizeAt(byte * instruction)1495 int Disassembler::ConstantPoolSizeAt(byte* instruction) {
1496   return v8::internal::Decoder::ConstantPoolSizeAt(instruction);
1497 }
1498 
1499 
Disassemble(FILE * f,byte * begin,byte * end)1500 void Disassembler::Disassemble(FILE* f, byte* begin, byte* end) {
1501   NameConverter converter;
1502   Disassembler d(converter);
1503   for (byte* pc = begin; pc < end;) {
1504     v8::internal::EmbeddedVector<char, 128> buffer;
1505     buffer[0] = '\0';
1506     byte* prev_pc = pc;
1507     pc += d.InstructionDecode(buffer, pc);
1508     fprintf(f, "%p    %08x      %s\n",
1509             prev_pc, *reinterpret_cast<int32_t*>(prev_pc), buffer.start());
1510   }
1511 }
1512 
1513 
1514 }  // namespace disasm
1515 
1516 #endif  // V8_TARGET_ARCH_ARM
1517