1 /*
2  * Copyright (C) 2012 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #include "disassembler_arm.h"
18 
19 #include <inttypes.h>
20 
21 #include <ostream>
22 #include <sstream>
23 
24 #include "arch/arm/registers_arm.h"
25 #include "base/logging.h"
26 #include "base/stringprintf.h"
27 #include "thread.h"
28 
29 namespace art {
30 namespace arm {
31 
Dump(std::ostream & os,const uint8_t * begin)32 size_t DisassemblerArm::Dump(std::ostream& os, const uint8_t* begin) {
33   if ((reinterpret_cast<intptr_t>(begin) & 1) == 0) {
34     DumpArm(os, begin);
35     return 4;
36   } else {
37     // remove thumb specifier bits
38     begin = reinterpret_cast<const uint8_t*>(reinterpret_cast<uintptr_t>(begin) & ~1);
39     return DumpThumb16(os, begin);
40   }
41 }
42 
Dump(std::ostream & os,const uint8_t * begin,const uint8_t * end)43 void DisassemblerArm::Dump(std::ostream& os, const uint8_t* begin, const uint8_t* end) {
44   if ((reinterpret_cast<intptr_t>(begin) & 1) == 0) {
45     for (const uint8_t* cur = begin; cur < end; cur += 4) {
46       DumpArm(os, cur);
47     }
48   } else {
49     // remove thumb specifier bits
50     begin = reinterpret_cast<const uint8_t*>(reinterpret_cast<uintptr_t>(begin) & ~1);
51     end = reinterpret_cast<const uint8_t*>(reinterpret_cast<uintptr_t>(end) & ~1);
52     for (const uint8_t* cur = begin; cur < end;) {
53       cur += DumpThumb16(os, cur);
54     }
55   }
56 }
57 
58 static const char* kConditionCodeNames[] = {
59   "eq",  // 0000 - equal
60   "ne",  // 0001 - not-equal
61   "cs",  // 0010 - carry-set, greater than, equal or unordered
62   "cc",  // 0011 - carry-clear, less than
63   "mi",  // 0100 - minus, negative
64   "pl",  // 0101 - plus, positive or zero
65   "vs",  // 0110 - overflow
66   "vc",  // 0111 - no overflow
67   "hi",  // 1000 - unsigned higher
68   "ls",  // 1001 - unsigned lower or same
69   "ge",  // 1010 - signed greater than or equal
70   "lt",  // 1011 - signed less than
71   "gt",  // 1100 - signed greater than
72   "le",  // 1101 - signed less than or equal
73   "",    // 1110 - always
74   "nv",  // 1111 - never (mostly obsolete, but might be a clue that we're mistranslating)
75 };
76 
DumpCond(std::ostream & os,uint32_t cond)77 void DisassemblerArm::DumpCond(std::ostream& os, uint32_t cond) {
78   if (cond < 15) {
79     os << kConditionCodeNames[cond];
80   } else {
81     os << "Unexpected condition: " << cond;
82   }
83 }
84 
DumpMemoryDomain(std::ostream & os,uint32_t domain)85 void DisassemblerArm::DumpMemoryDomain(std::ostream& os, uint32_t domain) {
86   switch (domain) {
87     case 15U /* 0b1111 */: os << "sy"; break;
88     case 14U /* 0b1110 */: os << "st"; break;
89     case 11U /* 0b1011 */: os << "ish"; break;
90     case 10U /* 0b1010 */: os << "ishst"; break;
91     case  7U /* 0b0111 */: os << "nsh"; break;
92     case  6U /* 0b0110 */: os << "nshst"; break;
93     case  3U /* 0b0011 */: os << "osh"; break;
94     case  2U /* 0b0010 */: os << "oshst"; break;
95   }
96 }
97 
DumpBranchTarget(std::ostream & os,const uint8_t * instr_ptr,int32_t imm32)98 void DisassemblerArm::DumpBranchTarget(std::ostream& os, const uint8_t* instr_ptr, int32_t imm32) {
99   os << StringPrintf("%+d (", imm32) << FormatInstructionPointer(instr_ptr + imm32) << ")";
100 }
101 
ReadU16(const uint8_t * ptr)102 static uint32_t ReadU16(const uint8_t* ptr) {
103   return ptr[0] | (ptr[1] << 8);
104 }
105 
ReadU32(const uint8_t * ptr)106 static uint32_t ReadU32(const uint8_t* ptr) {
107   return ptr[0] | (ptr[1] << 8) | (ptr[2] << 16) | (ptr[3] << 24);
108 }
109 
110 static const char* kDataProcessingOperations[] = {
111   "and", "eor", "sub", "rsb", "add", "adc", "sbc", "rsc",
112   "tst", "teq", "cmp", "cmn", "orr", "mov", "bic", "mvn",
113 };
114 
115 static const char* kThumbDataProcessingOperations[] = {
116   "and", "eor", "lsl", "lsr", "asr", "adc", "sbc", "ror",
117   "tst", "rsb", "cmp", "cmn", "orr", "mul", "bic", "mvn",
118 };
119 
120 static const char* const kThumb2ShiftOperations[] = {
121     "lsl", "lsr", "asr", "ror"
122 };
123 
124 static const char* kThumbReverseOperations[] = {
125     "rev", "rev16", "rbit", "revsh"
126 };
127 
128 struct ArmRegister {
ArmRegisterart::arm::ArmRegister129   explicit ArmRegister(uint32_t r_in) : r(r_in) { CHECK_LE(r_in, 15U); }
ArmRegisterart::arm::ArmRegister130   ArmRegister(uint32_t instruction, uint32_t at_bit) : r((instruction >> at_bit) & 0xf) {
131     CHECK_LE(r, 15U);
132   }
133   uint32_t r;
134 };
operator <<(std::ostream & os,const ArmRegister & r)135 std::ostream& operator<<(std::ostream& os, const ArmRegister& r) {
136   if (r.r == 13) {
137     os << "sp";
138   } else if (r.r == 14) {
139     os << "lr";
140   } else if (r.r == 15) {
141     os << "pc";
142   } else {
143     os << "r" << r.r;
144   }
145   return os;
146 }
147 
148 struct ThumbRegister : ArmRegister {
ThumbRegisterart::arm::ThumbRegister149   ThumbRegister(uint16_t instruction, uint16_t at_bit) : ArmRegister((instruction >> at_bit) & 0x7) {}
150 };
151 
152 struct RmLslImm2 {
RmLslImm2art::arm::RmLslImm2153   explicit RmLslImm2(uint32_t instr) : imm2((instr >> 4) & 0x3), rm(instr & 0xf) {}
154   uint32_t imm2;
155   ArmRegister rm;
156 };
operator <<(std::ostream & os,const RmLslImm2 & r)157 std::ostream& operator<<(std::ostream& os, const RmLslImm2& r) {
158   os << r.rm;
159   if (r.imm2 != 0) {
160     os << ", lsl #" << r.imm2;
161   }
162   return os;
163 }
164 
165 struct ShiftedImmediate {
ShiftedImmediateart::arm::ShiftedImmediate166   explicit ShiftedImmediate(uint32_t instruction) {
167     uint32_t rotate = ((instruction >> 8) & 0xf);
168     uint32_t imm = (instruction & 0xff);
169     value = (imm >> (2 * rotate)) | (imm << (32 - (2 * rotate)));
170   }
171   uint32_t value;
172 };
operator <<(std::ostream & os,const ShiftedImmediate & rhs)173 std::ostream& operator<<(std::ostream& os, const ShiftedImmediate& rhs) {
174   os << "#" << rhs.value;
175   return os;
176 }
177 
178 struct RegisterList {
RegisterListart::arm::RegisterList179   explicit RegisterList(uint32_t instruction) : register_list(instruction & 0xffff) {}
180   uint32_t register_list;
181 };
operator <<(std::ostream & os,const RegisterList & rhs)182 std::ostream& operator<<(std::ostream& os, const RegisterList& rhs) {
183   if (rhs.register_list == 0) {
184     os << "<no register list?>";
185     return os;
186   }
187   os << "{";
188   bool first = true;
189   for (size_t i = 0; i < 16; i++) {
190     if ((rhs.register_list & (1 << i)) != 0) {
191       if (first) {
192         first = false;
193       } else {
194         os << ", ";
195       }
196       os << ArmRegister(i);
197     }
198   }
199   os << "}";
200   return os;
201 }
202 
203 struct FpRegister {
FpRegisterart::arm::FpRegister204   explicit FpRegister(uint32_t instr, uint16_t at_bit, uint16_t extra_at_bit) {
205     size = (instr >> 8) & 1;
206     uint32_t Vn = (instr >> at_bit) & 0xF;
207     uint32_t N = (instr >> extra_at_bit) & 1;
208     r = (size != 0 ? ((N << 4) | Vn) : ((Vn << 1) | N));
209   }
FpRegisterart::arm::FpRegister210   explicit FpRegister(uint32_t instr, uint16_t at_bit, uint16_t extra_at_bit,
211                       uint32_t forced_size) {
212     size = forced_size;
213     uint32_t Vn = (instr >> at_bit) & 0xF;
214     uint32_t N = (instr >> extra_at_bit) & 1;
215     r = (size != 0 ? ((N << 4) | Vn) : ((Vn << 1) | N));
216   }
FpRegisterart::arm::FpRegister217   FpRegister(const FpRegister& other, uint32_t offset)
218       : size(other.size), r(other.r + offset) {}
219 
220   uint32_t size;  // 0 = f32, 1 = f64
221   uint32_t r;
222 };
operator <<(std::ostream & os,const FpRegister & rhs)223 std::ostream& operator<<(std::ostream& os, const FpRegister& rhs) {
224   return os << ((rhs.size != 0) ? "d" : "s") << rhs.r;
225 }
226 
227 struct FpRegisterRange {
FpRegisterRangeart::arm::FpRegisterRange228   explicit FpRegisterRange(uint32_t instr)
229       : first(instr, 12, 22), imm8(instr & 0xFF) {}
230   FpRegister first;
231   uint32_t imm8;
232 };
operator <<(std::ostream & os,const FpRegisterRange & rhs)233 std::ostream& operator<<(std::ostream& os, const FpRegisterRange& rhs) {
234   os << "{" << rhs.first;
235   int count = (rhs.first.size != 0 ? ((rhs.imm8 + 1u) >> 1) : rhs.imm8);
236   if (count > 1) {
237     os << "-" << FpRegister(rhs.first, count - 1);
238   }
239   if (rhs.imm8 == 0) {
240     os << " (EMPTY)";
241   } else if (rhs.first.size != 0 && (rhs.imm8 & 1) != 0) {
242     os << rhs.first << " (HALF)";
243   }
244   os << "}";
245   return os;
246 }
247 
DumpArm(std::ostream & os,const uint8_t * instr_ptr)248 void DisassemblerArm::DumpArm(std::ostream& os, const uint8_t* instr_ptr) {
249   uint32_t instruction = ReadU32(instr_ptr);
250   uint32_t cond = (instruction >> 28) & 0xf;
251   uint32_t op1 = (instruction >> 25) & 0x7;
252   std::string opcode;
253   std::string suffixes;
254   std::ostringstream args;
255   switch (op1) {
256     case 0:
257     case 1:  // Data processing instructions.
258       {
259         if ((instruction & 0x0ff000f0) == 0x01200070) {  // BKPT
260           opcode = "bkpt";
261           uint32_t imm12 = (instruction >> 8) & 0xfff;
262           uint32_t imm4 = (instruction & 0xf);
263           args << '#' << ((imm12 << 4) | imm4);
264           break;
265         }
266         if ((instruction & 0x0fffffd0) == 0x012fff10) {  // BX and BLX (register)
267           opcode = (((instruction >> 5) & 1) ? "blx" : "bx");
268           args << ArmRegister(instruction & 0xf);
269           break;
270         }
271         bool i = (instruction & (1 << 25)) != 0;
272         bool s = (instruction & (1 << 20)) != 0;
273         uint32_t op = (instruction >> 21) & 0xf;
274         opcode = kDataProcessingOperations[op];
275         bool implicit_s = ((op & ~3) == 8);  // TST, TEQ, CMP, and CMN.
276         bool is_mov = op == 13U /* 0b1101 */ || op == 15U /* 0b1111 */;
277         if (is_mov) {
278           // Show only Rd and Rm.
279           if (s) {
280              suffixes += 's';
281            }
282            args << ArmRegister(instruction, 12) << ", ";
283            if (i) {
284               args << ShiftedImmediate(instruction);
285             } else {
286               // TODO: Shifted register.
287               args << ArmRegister(instruction, 16) << ", " << ArmRegister(instruction, 0);
288             }
289         } else {
290           if (implicit_s) {
291             // Rd is unused (and not shown), and we don't show the 's' suffix either.
292           } else {
293             if (s) {
294               suffixes += 's';
295             }
296             args << ArmRegister(instruction, 12) << ", ";
297           }
298           if (i) {
299             args << ArmRegister(instruction, 16) << ", " << ShiftedImmediate(instruction);
300           } else {
301             // TODO: Shifted register.
302             args << ArmRegister(instruction, 16) << ", " << ArmRegister(instruction, 0);
303           }
304         }
305       }
306       break;
307     case 2:  // Load/store word and unsigned byte.
308       {
309         bool p = (instruction & (1 << 24)) != 0;
310         bool b = (instruction & (1 << 22)) != 0;
311         bool w = (instruction & (1 << 21)) != 0;
312         bool l = (instruction & (1 << 20)) != 0;
313         opcode = StringPrintf("%s%s", (l ? "ldr" : "str"), (b ? "b" : ""));
314         args << ArmRegister(instruction, 12) << ", ";
315         ArmRegister rn(instruction, 16);
316         if (rn.r == 0xf) {
317           UNIMPLEMENTED(FATAL) << "literals";
318         } else {
319           bool wback = !p || w;
320           uint32_t offset = (instruction & 0xfff);
321           if (p && !wback) {
322             args << "[" << rn << ", #" << offset << "]";
323           } else if (p && wback) {
324             args << "[" << rn << ", #" << offset << "]!";
325           } else if (!p && wback) {
326             args << "[" << rn << "], #" << offset;
327           } else {
328             LOG(FATAL) << p << " " << w;
329           }
330           if (rn.r == 9) {
331             args << "  ; ";
332             Thread::DumpThreadOffset<4>(args, offset);
333           }
334         }
335       }
336       break;
337     case 4:  // Load/store multiple.
338       {
339         bool p = (instruction & (1 << 24)) != 0;
340         bool u = (instruction & (1 << 23)) != 0;
341         bool w = (instruction & (1 << 21)) != 0;
342         bool l = (instruction & (1 << 20)) != 0;
343         opcode = StringPrintf("%s%c%c", (l ? "ldm" : "stm"), (u ? 'i' : 'd'), (p ? 'b' : 'a'));
344         args << ArmRegister(instruction, 16) << (w ? "!" : "") << ", " << RegisterList(instruction);
345       }
346       break;
347     case 5:  // Branch/branch with link.
348       {
349         bool bl = (instruction & (1 << 24)) != 0;
350         opcode = (bl ? "bl" : "b");
351         int32_t imm26 = (instruction & 0xffffff) << 2;
352         int32_t imm32 = (imm26 << 6) >> 6;  // Sign extend.
353         DumpBranchTarget(args, instr_ptr + 8, imm32);
354       }
355       break;
356     default:
357       opcode = "???";
358       break;
359     }
360     opcode += kConditionCodeNames[cond];
361     opcode += suffixes;
362     // TODO: a more complete ARM disassembler could generate wider opcodes.
363     os << FormatInstructionPointer(instr_ptr)
364        << StringPrintf(": %08x\t%-7s ", instruction, opcode.c_str())
365        << args.str() << '\n';
366 }
367 
ThumbExpand(int32_t imm12)368 int32_t ThumbExpand(int32_t imm12) {
369   if ((imm12 & 0xC00) == 0) {
370     switch ((imm12 >> 8) & 3) {
371       case 0:
372         return imm12 & 0xFF;
373       case 1:
374         return ((imm12 & 0xFF) << 16) | (imm12 & 0xFF);
375       case 2:
376         return ((imm12 & 0xFF) << 24) | ((imm12 & 0xFF) << 8);
377       default:  // 3
378         return ((imm12 & 0xFF) << 24) | ((imm12 & 0xFF) << 16) | ((imm12 & 0xFF) << 8) |
379             (imm12 & 0xFF);
380     }
381   } else {
382     uint32_t val = 0x80 | (imm12 & 0x7F);
383     int32_t rotate = (imm12 >> 7) & 0x1F;
384     return (val >> rotate) | (val << (32 - rotate));
385   }
386 }
387 
VFPExpand32(uint32_t imm8)388 uint32_t VFPExpand32(uint32_t imm8) {
389   CHECK_EQ(imm8 & 0xffu, imm8);
390   uint32_t bit_a = (imm8 >> 7) & 1;
391   uint32_t bit_b = (imm8 >> 6) & 1;
392   uint32_t slice = imm8 & 0x3f;
393   return (bit_a << 31) | ((1 << 30) - (bit_b << 25)) | (slice << 19);
394 }
395 
VFPExpand64(uint32_t imm8)396 static uint64_t VFPExpand64(uint32_t imm8) {
397   CHECK_EQ(imm8 & 0xffu, imm8);
398   uint64_t bit_a = (imm8 >> 7) & 1;
399   uint64_t bit_b = (imm8 >> 6) & 1;
400   uint64_t slice = imm8 & 0x3f;
401   return (bit_a << 63) | ((UINT64_C(1) << 62) - (bit_b << 54)) | (slice << 48);
402 }
403 
404 enum T2LitType {
405   kT2LitInvalid,
406   kT2LitUByte,
407   kT2LitSByte,
408   kT2LitUHalf,
409   kT2LitSHalf,
410   kT2LitUWord,
411   kT2LitSWord,
412   kT2LitHexWord,
413   kT2LitULong,
414   kT2LitSLong,
415   kT2LitHexLong,
416 };
operator <<(std::ostream & os,T2LitType type)417 std::ostream& operator<<(std::ostream& os, T2LitType type) {
418   return os << static_cast<int>(type);
419 }
420 
DumpThumb2Literal(std::ostream & args,const uint8_t * instr_ptr,uint32_t U,uint32_t imm32,T2LitType type)421 void DumpThumb2Literal(std::ostream& args, const uint8_t* instr_ptr, uint32_t U, uint32_t imm32,
422                        T2LitType type) {
423   // Literal offsets (imm32) are not required to be aligned so we may need unaligned access.
424   typedef const int16_t unaligned_int16_t __attribute__ ((aligned (1)));
425   typedef const uint16_t unaligned_uint16_t __attribute__ ((aligned (1)));
426   typedef const int32_t unaligned_int32_t __attribute__ ((aligned (1)));
427   typedef const uint32_t unaligned_uint32_t __attribute__ ((aligned (1)));
428   typedef const int64_t unaligned_int64_t __attribute__ ((aligned (1)));
429   typedef const uint64_t unaligned_uint64_t __attribute__ ((aligned (1)));
430 
431   uintptr_t pc = RoundDown(reinterpret_cast<intptr_t>(instr_ptr) + 4, 4);
432   uintptr_t lit_adr = U ? pc + imm32 : pc - imm32;
433   args << "  ; ";
434   switch (type) {
435     case kT2LitUByte:
436       args << *reinterpret_cast<const uint8_t*>(lit_adr);
437       break;
438     case kT2LitSByte:
439       args << *reinterpret_cast<const int8_t*>(lit_adr);
440       break;
441     case kT2LitUHalf:
442       args << *reinterpret_cast<const unaligned_uint16_t*>(lit_adr);
443       break;
444     case kT2LitSHalf:
445       args << *reinterpret_cast<const unaligned_int16_t*>(lit_adr);
446       break;
447     case kT2LitUWord:
448       args << *reinterpret_cast<const unaligned_uint32_t*>(lit_adr);
449       break;
450     case kT2LitSWord:
451       args << *reinterpret_cast<const unaligned_int32_t*>(lit_adr);
452       break;
453     case kT2LitHexWord:
454       args << StringPrintf("0x%08x", *reinterpret_cast<const unaligned_uint32_t*>(lit_adr));
455       break;
456     case kT2LitULong:
457       args << *reinterpret_cast<const unaligned_uint64_t*>(lit_adr);
458       break;
459     case kT2LitSLong:
460       args << *reinterpret_cast<const unaligned_int64_t*>(lit_adr);
461       break;
462     case kT2LitHexLong:
463       args << StringPrintf("0x%" PRIx64, *reinterpret_cast<unaligned_int64_t*>(lit_adr));
464       break;
465     default:
466       LOG(FATAL) << "Invalid type: " << type;
467       break;
468   }
469 }
470 
DumpThumb32(std::ostream & os,const uint8_t * instr_ptr)471 size_t DisassemblerArm::DumpThumb32(std::ostream& os, const uint8_t* instr_ptr) {
472   uint32_t instr = (ReadU16(instr_ptr) << 16) | ReadU16(instr_ptr + 2);
473   // |111|1 1|1000000|0000|1111110000000000|
474   // |5 3|2 1|0987654|3  0|5    0    5    0|
475   // |---|---|-------|----|----------------|
476   // |332|2 2|2222222|1111|1111110000000000|
477   // |1 9|8 7|6543210|9  6|5    0    5    0|
478   // |---|---|-------|----|----------------|
479   // |111|op1| op2   |    |                |
480   uint32_t op1 = (instr >> 27) & 3;
481   if (op1 == 0) {
482     return DumpThumb16(os, instr_ptr);
483   }
484 
485   uint32_t op2 = (instr >> 20) & 0x7F;
486   std::ostringstream opcode;
487   std::ostringstream args;
488   switch (op1) {
489     case 0:
490       break;
491     case 1:
492       if ((op2 & 0x64) == 0) {  // 00x x0xx
493         // |111|11|10|00|0|00|0000|1111110000000000|
494         // |5 3|21|09|87|6|54|3  0|5    0    5    0|
495         // |---|--|--|--|-|--|----|----------------|
496         // |332|22|22|22|2|22|1111|1111110000000000|
497         // |1 9|87|65|43|2|10|9  6|5    0    5    0|
498         // |---|--|--|--|-|--|----|----------------|
499         // |111|01|00|op|0|WL| Rn |                |
500         // |111|01| op2      |    |                |
501         // STM - 111 01 00-01-0-W0 nnnn rrrrrrrrrrrrrrrr
502         // LDM - 111 01 00-01-0-W1 nnnn rrrrrrrrrrrrrrrr
503         // PUSH- 111 01 00-01-0-10 1101 0M0rrrrrrrrrrrrr
504         // POP - 111 01 00-01-0-11 1101 PM0rrrrrrrrrrrrr
505         uint32_t op = (instr >> 23) & 3;
506         uint32_t W = (instr >> 21) & 1;
507         uint32_t L = (instr >> 20) & 1;
508         ArmRegister Rn(instr, 16);
509         if (op == 1 || op == 2) {
510           if (op == 1) {
511             if (L == 0) {
512               opcode << "stm";
513               args << Rn << (W == 0 ? "" : "!") << ", ";
514             } else {
515               if (Rn.r != 13) {
516                 opcode << "ldm";
517                 args << Rn << (W == 0 ? "" : "!") << ", ";
518               } else {
519                 opcode << "pop";
520               }
521             }
522           } else {
523             if (L == 0) {
524               if (Rn.r != 13) {
525                 opcode << "stmdb";
526                 args << Rn << (W == 0 ? "" : "!") << ", ";
527               } else {
528                 opcode << "push";
529               }
530             } else {
531               opcode << "ldmdb";
532               args << Rn << (W == 0 ? "" : "!") << ", ";
533             }
534           }
535           args << RegisterList(instr);
536         }
537       } else if ((op2 & 0x64) == 4) {  // 00x x1xx
538         uint32_t op3 = (instr >> 23) & 3;
539         uint32_t op4 = (instr >> 20) & 3;
540         // uint32_t op5 = (instr >> 4) & 0xF;
541         ArmRegister Rn(instr, 16);
542         ArmRegister Rt(instr, 12);
543         ArmRegister Rd(instr, 8);
544         uint32_t imm8 = instr & 0xFF;
545         if ((op3 & 2) == 2) {     // 1x
546           int W = (instr >> 21) & 1;
547           int U = (instr >> 23) & 1;
548           int P = (instr >> 24) & 1;
549 
550           if ((op4 & 1) == 1) {
551             opcode << "ldrd";
552           } else {
553             opcode << "strd";
554           }
555           args << Rt << "," << Rd << ", [" << Rn;
556           const char *sign = U ? "+" : "-";
557           if (P == 0 && W == 1) {
558             args << "], #" << sign << (imm8 << 2);
559           } else {
560             args << ", #" << sign << (imm8 << 2) << "]";
561             if (W == 1) {
562               args << "!";
563             }
564           }
565         } else {                  // 0x
566           switch (op4) {
567             case 0:
568               if (op3 == 0) {   // op3 is 00, op4 is 00
569                 opcode << "strex";
570                 args << Rd << ", " << Rt << ", [" << Rn << ", #" << (imm8 << 2) << "]";
571                 if (Rd.r == 13 || Rd.r == 15 || Rt.r == 13 || Rt.r == 15 || Rn.r == 15 ||
572                     Rd.r == Rn.r || Rd.r == Rt.r) {
573                   args << " (UNPREDICTABLE)";
574                 }
575               } else {          // op3 is 01, op4 is 00
576                 // this is one of strexb, strexh or strexd
577                 int op5 = (instr >> 4) & 0xf;
578                 switch (op5) {
579                   case 4:
580                   case 5:
581                     opcode << ((op5 == 4) ? "strexb" : "strexh");
582                     Rd = ArmRegister(instr, 0);
583                     args << Rd << ", " << Rt << ", [" << Rn << "]";
584                     if (Rd.r == 13 || Rd.r == 15 || Rt.r == 13 || Rt.r == 15 || Rn.r == 15 ||
585                         Rd.r == Rn.r || Rd.r == Rt.r || (instr & 0xf00) != 0xf00) {
586                       args << " (UNPREDICTABLE)";
587                     }
588                     break;
589                   case 7:
590                     opcode << "strexd";
591                     ArmRegister Rt2 = Rd;
592                     Rd = ArmRegister(instr, 0);
593                     args << Rd << ", " << Rt << ", " << Rt2 << ", [" << Rn << "]";
594                     if (Rd.r == 13 || Rd.r == 15 || Rt.r == 13 || Rt.r == 15 ||
595                         Rt2.r == 13 || Rt2.r == 15 || Rn.r == 15 ||
596                         Rd.r == Rn.r || Rd.r == Rt.r || Rd.r == Rt2.r) {
597                       args << " (UNPREDICTABLE)";
598                     }
599                     break;
600                 }
601               }
602               break;
603             case 1:
604               if (op3 == 0) {   // op3 is 00, op4 is 01
605                 opcode << "ldrex";
606                 args << Rt << ", [" << Rn << ", #" << (imm8 << 2) << "]";
607                 if (Rt.r == 13 || Rt.r == 15 || Rn.r == 15 || (instr & 0xf00) != 0xf00) {
608                   args << " (UNPREDICTABLE)";
609                 }
610               } else {          // op3 is 01, op4 is 01
611                 // this is one of strexb, strexh or strexd
612                 int op5 = (instr >> 4) & 0xf;
613                 switch (op5) {
614                   case 0:
615                     opcode << "tbb";
616                     break;
617                   case 1:
618                     opcode << "tbh";
619                     break;
620                   case 4:
621                   case 5:
622                     opcode << ((op5 == 4) ? "ldrexb" : "ldrexh");
623                     args << Rt << ", [" << Rn << "]";
624                     if (Rt.r == 13 || Rt.r == 15 || Rn.r == 15 || (instr & 0xf0f) != 0xf0f) {
625                       args << " (UNPREDICTABLE)";
626                     }
627                     break;
628                   case 7:
629                     opcode << "ldrexd";
630                     args << Rt << ", " << Rd /* Rt2 */ << ", [" << Rn << "]";
631                     if (Rt.r == 13 || Rt.r == 15 || Rd.r == 13 /* Rt2 */ || Rd.r == 15 /* Rt2 */ ||
632                         Rn.r == 15 || (instr & 0x00f) != 0x00f) {
633                       args << " (UNPREDICTABLE)";
634                     }
635                     break;
636                 }
637               }
638               break;
639             case 2:     // op3 is 0x, op4 is 10
640             case 3:   // op3 is 0x, op4 is 11
641               if (op4 == 2) {
642                 opcode << "strd";
643               } else {
644                 opcode << "ldrd";
645               }
646               int W = (instr >> 21) & 1;
647               int U = (instr >> 23) & 1;
648               int P = (instr >> 24) & 1;
649 
650               args << Rt << "," << Rd << ", [" << Rn;
651               const char *sign = U ? "+" : "-";
652               if (P == 0 && W == 1) {
653                 args << "], #" << sign << imm8;
654               } else {
655                 args << ", #" << sign << imm8 << "]";
656                 if (W == 1) {
657                   args << "!";
658                 }
659               }
660               break;
661           }
662         }
663 
664       } else if ((op2 & 0x60) == 0x20) {  // 01x xxxx
665         // Data-processing (shifted register)
666         // |111|1110|0000|0|0000|1111|1100|00|00|0000|
667         // |5 3|2109|8765|4|3  0|5   |10 8|7 |5 |3  0|
668         // |---|----|----|-|----|----|----|--|--|----|
669         // |332|2222|2222|2|1111|1111|1100|00|00|0000|
670         // |1 9|8765|4321|0|9  6|5   |10 8|7 |5 |3  0|
671         // |---|----|----|-|----|----|----|--|--|----|
672         // |111|0101| op3|S| Rn |imm3| Rd |i2|ty| Rm |
673         uint32_t op3 = (instr >> 21) & 0xF;
674         uint32_t S = (instr >> 20) & 1;
675         uint32_t imm3 = ((instr >> 12) & 0x7);
676         uint32_t imm2 = ((instr >> 6) & 0x3);
677         uint32_t imm5 = ((imm3 << 2) | imm2);
678         uint32_t shift_type = ((instr >> 4) & 0x3);
679         ArmRegister Rd(instr, 8);
680         ArmRegister Rn(instr, 16);
681         ArmRegister Rm(instr, 0);
682         switch (op3) {
683           case 0x0:
684             if (Rd.r != 0xF) {
685               opcode << "and";
686             } else {
687               if (S != 1U) {
688                 opcode << "UNKNOWN TST-" << S;
689                 break;
690               }
691               opcode << "tst";
692               S = 0;  // don't print 's'
693             }
694             break;
695           case 0x1: opcode << "bic"; break;
696           case 0x2:
697             if (Rn.r != 0xF) {
698               opcode << "orr";
699             } else {
700               // TODO: use canonical form if there is a shift (lsl, ...).
701               opcode << "mov";
702             }
703             break;
704           case 0x3:
705             if (Rn.r != 0xF) {
706               opcode << "orn";
707             } else {
708               opcode << "mvn";
709             }
710             break;
711           case 0x4:
712             if (Rd.r != 0xF) {
713               opcode << "eor";
714             } else {
715               if (S != 1U) {
716                 opcode << "UNKNOWN TEQ-" << S;
717                 break;
718               }
719               opcode << "teq";
720               S = 0;  // don't print 's'
721             }
722             break;
723           case 0x6: opcode << "pkh"; break;
724           case 0x8:
725             if (Rd.r != 0xF) {
726               opcode << "add";
727             } else {
728               if (S != 1U) {
729                 opcode << "UNKNOWN CMN-" << S;
730                 break;
731               }
732               opcode << "cmn";
733               S = 0;  // don't print 's'
734             }
735             break;
736           case 0xA: opcode << "adc"; break;
737           case 0xB: opcode << "sbc"; break;
738           case 0xD:
739             if (Rd.r != 0xF) {
740               opcode << "sub";
741             } else {
742               if (S != 1U) {
743                 opcode << "UNKNOWN CMP-" << S;
744                 break;
745               }
746               opcode << "cmp";
747               S = 0;  // don't print 's'
748             }
749             break;
750           case 0xE: opcode << "rsb"; break;
751           default: opcode << "UNKNOWN DPSR-" << op3; break;
752         }
753 
754         if (S == 1) {
755           opcode << "s";
756         }
757         opcode << ".w";
758 
759         if (Rd.r != 0xF) {
760           args << Rd << ", ";
761         }
762         if (Rn.r != 0xF) {
763           args << Rn << ", ";
764         }
765         args << Rm;
766 
767         // Shift operand.
768         bool noShift = (imm5 == 0 && shift_type != 0x3);
769         if (!noShift) {
770           args << ", ";
771           switch (shift_type) {
772             case 0x0: args << "lsl"; break;
773             case 0x1: args << "lsr"; break;
774             case 0x2: args << "asr"; break;
775             case 0x3:
776               if (imm5 == 0) {
777                 args << "rrx";
778               } else {
779                 args << "ror";
780               }
781               break;
782           }
783           if (shift_type != 0x3 /* rrx */) {
784             args << StringPrintf(" #%d", (0 != imm5 || 0 == shift_type) ? imm5 : 32);
785           }
786         }
787 
788       } else if ((op2 & 0x40) == 0x40) {  // 1xx xxxx
789         // Co-processor instructions
790         // |111|1|11|000000|0000|1111|1100|000|0  |0000|
791         // |5 3|2|10|987654|3  0|54 2|10 8|7 5|4  |   0|
792         // |---|-|--|------|----|----|----|---|---|----|
793         // |332|2|22|222222|1111|1111|1100|000|0  |0000|
794         // |1 9|8|76|543210|9  6|54 2|10 8|7 5|4  |   0|
795         // |---|-|--|------|----|----|----|---|---|----|
796         // |111| |11| op3  | Rn |    |copr|   |op4|    |
797         uint32_t op3 = (instr >> 20) & 0x3F;
798         uint32_t coproc = (instr >> 8) & 0xF;
799         uint32_t op4 = (instr >> 4) & 0x1;
800 
801         if (coproc == 0xA || coproc == 0xB) {   // 101x
802           if (op3 < 0x20 && (op3 & ~5) != 0) {     // 0xxxxx and not 000x0x
803             // Extension register load/store instructions
804             // |1111|110|00000|0000|1111|110|0|00000000|
805             // |5  2|1 9|87654|3  0|5  2|1 9|8|7      0|
806             // |----|---|-----|----|----|---|-|--------|
807             // |3322|222|22222|1111|1111|110|0|00000000|
808             // |1  8|7 5|4   0|9  6|5  2|1 9|8|7      0|
809             // |----|---|-----|----|----|---|-|--------|
810             // |1110|110|PUDWL| Rn | Vd |101|S|  imm8  |
811             uint32_t P = (instr >> 24) & 1;
812             uint32_t U = (instr >> 23) & 1;
813             uint32_t W = (instr >> 21) & 1;
814             if (P == U && W == 1) {
815               opcode << "UNDEFINED";
816             } else {
817               uint32_t L = (instr >> 20) & 1;
818               uint32_t S = (instr >> 8) & 1;
819               ArmRegister Rn(instr, 16);
820               if (P == 1 && W == 0) {  // VLDR
821                 FpRegister d(instr, 12, 22);
822                 uint32_t imm8 = instr & 0xFF;
823                 opcode << (L == 1 ? "vldr" : "vstr");
824                 args << d << ", [" << Rn << ", #" << ((U == 1) ? "" : "-")
825                      << (imm8 << 2) << "]";
826                 if (Rn.r == 15 && U == 1) {
827                   DumpThumb2Literal(args, instr_ptr, U, imm8 << 2, kT2LitHexLong);
828                 }
829               } else if (Rn.r == 13 && W == 1 && U == L) {  // VPUSH/VPOP
830                 opcode << (L == 1 ? "vpop" : "vpush");
831                 args << FpRegisterRange(instr);
832               } else {  // VLDM
833                 opcode << (L == 1 ? "vldm" : "vstm");
834                 args << Rn << ((W == 1) ? "!" : "") << ", "
835                      << FpRegisterRange(instr);
836               }
837               opcode << (S == 1 ? ".f64" : ".f32");
838             }
839           } else if ((op3 >> 1) == 2) {      // 00010x
840             if ((instr & 0xD0) == 0x10) {
841               // 64bit transfers between ARM core and extension registers.
842               uint32_t L = (instr >> 20) & 1;
843               uint32_t S = (instr >> 8) & 1;
844               ArmRegister Rt2(instr, 16);
845               ArmRegister Rt(instr, 12);
846               FpRegister m(instr, 0, 5);
847               opcode << "vmov" << (S ? ".f64" : ".f32");
848               if (L == 1) {
849                 args << Rt << ", " << Rt2 << ", ";
850               }
851               if (S) {
852                 args << m;
853               } else {
854                 args << m << ", " << FpRegister(m, 1);
855               }
856               if (L == 0) {
857                 args << ", " << Rt << ", " << Rt2;
858               }
859               if (Rt.r == 15 || Rt.r == 13 || Rt2.r == 15 || Rt2.r == 13 ||
860                   (S == 0 && m.r == 31) || (L == 1 && Rt.r == Rt2.r)) {
861                 args << " (UNPREDICTABLE)";
862               }
863             }
864           } else if ((op3 >> 4) == 2 && op4 == 0) {     // 10xxxx, op = 0
865             // fp data processing
866             // VMLA, VMLS, VMUL, VNMUL, VADD, VSUB, VDIV, VMOV, ...
867             // |1111|1100|0|0|00|0000|1111|110|0|0|0|0|0|0000|
868             // |5  2|1  8|7|6|54|3  0|5  2|1 9|8|7|6|5|4|3  0|
869             // |----|----|-|-|--|----|----|---|-|-|-|-|-|----|
870             // |3322|2222|2|2|22|1111|1111|110|0|0|0|0|0|0000|
871             // |1  8|7  4|3|2|10|9  6|5  2|1 9|8|7|6|5|4|3  0|
872             // |----|----|-|-|--|----|----|---|-|-|-|-|-|----|
873             // |1110|1110|  op3 | Vn | Vd |101|S|N|Q|M|0| Vm |
874             // |1110|1110|0|D|00| Vn | Vd |101|S|N|0|M|0| Vm | VMLA
875             // |1110|1110|0|D|00| Vn | Vd |101|S|N|1|M|0| Vm | VMLS
876             // |1110|1110|0|D|10| Vn | Vd |101|S|N|0|M|0| Vm | VMUL
877             // |1110|1110|0|D|10| Vn | Vd |101|S|N|1|M|0| Vm | VNMUL
878             // |1110|1110|0|D|11| Vn | Vd |101|S|N|0|M|0| Vm | VADD
879             // |1110|1110|0|D|11| Vn | Vd |101|S|N|1|M|0| Vm | VSUB
880             // |1110|1110|1|D|00| Vn | Vd |101|S|N|0|M|0| Vm | VDIV
881             // |1110|1110|1|D|11| iH | Vd |101|S|0|0|0|0| iL | VMOV (imm)
882             // |1110|1110|1|D|11|op5 | Vd |101|S|.|1|M|0| Vm | ... (see below)
883             uint32_t S = (instr >> 8) & 1;
884             uint32_t Q = (instr >> 6) & 1;
885             FpRegister d(instr, 12, 22);
886             FpRegister n(instr, 16, 7);
887             FpRegister m(instr, 0, 5);
888             if ((op3 & 0xB) == 0) {  // 100x00
889               opcode << (Q == 0 ? "vmla" : "vmls") << (S != 0 ? ".f64" : ".f32");
890               args << d << ", " << n << ", " << m;
891             } else if ((op3 & 0xB) == 0x2) {  // 100x10
892               opcode << (Q == 0 ? "vmul" : "vnmul") << (S != 0 ? ".f64" : ".f32");
893               args << d << ", " << n << ", " << m;
894             } else if ((op3 & 0xB) == 0x3) {  // 100x11
895               opcode << (Q == 0 ? "vadd" : "vsub") << (S != 0 ? ".f64" : ".f32");
896               args << d << ", " << n << ", " << m;
897             } else if ((op3 & 0xB) == 0x8 && Q == 0) {  // 101x00, Q == 0
898               opcode << "vdiv" << (S != 0 ? ".f64" : ".f32");
899               args << d << ", " << n << ", " << m;
900             } else if ((op3 & 0xB) == 0xB && Q == 0) {  // 101x11, Q == 0
901               uint32_t imm8 = ((instr & 0xf0000u) >> 12) | (instr & 0xfu);
902               opcode << "vmov" << (S != 0 ? ".f64" : ".f32");
903               args << d << ", " << (S != 0 ? StringPrintf("0x%016" PRIx64, VFPExpand64(imm8))
904                                            : StringPrintf("0x%08x", VFPExpand32(imm8)));
905               if ((instr & 0xa0) != 0) {
906                 args << " (UNPREDICTABLE)";
907               }
908             } else if ((op3 & 0xB) == 0xB && Q == 1) {  // 101x11, Q == 1
909               // VNEG, VSQRT, VCMP, VCMPE, VCVT (floating-point conversion)
910               // |1111|1100|0|0|00|0000|1111|110|0|0 |0|0|0|0000|
911               // |5  2|1  8|7|6|54|3  0|5  2|1 9|8|7 |6|5|4|3  0|
912               // |----|----|-|-|--|----|----|---|-|- |-|-|-|----|
913               // |3322|2222|2|2|22|1111|1111|110|0|0 |0|0|0|0000|
914               // |1  8|7  4|3|2|10|9  6|5  2|1 9|8|7 |6|5|4|3  0|
915               // |----|----|-|-|--|----|----|---|-|- |-|-|-|----|
916               // |1110|1110|1|D|11|0000| Vd |101|S|0 |1|M|0| Vm | VMOV (reg)
917               // |1110|1110|1|D|11|0000| Vd |101|S|1 |1|M|0| Vm | VABS
918               // |1110|1110|1|D|11|0001| Vd |101|S|0 |1|M|0| Vm | VNEG
919               // |1110|1110|1|D|11|0001| Vd |101|S|1 |1|M|0| Vm | VSQRT
920               // |1110|1110|1|D|11|0100| Vd |101|S|op|1|M|0| Vm | VCMP
921               // |1110|1110|1|D|11|0101| Vd |101|S|op|1|0|0|0000| VCMPE
922               // |1110|1110|1|D|11|op5 | Vd |101|S|op|1|M|0| Vm | VCVT
923               uint32_t op5 = (instr >> 16) & 0xF;
924               uint32_t op = (instr >> 7) & 1;
925               // Register types in VCVT instructions rely on the combination of op5 and S.
926               FpRegister Dd(instr, 12, 22, 1);
927               FpRegister Sd(instr, 12, 22, 0);
928               FpRegister Dm(instr, 0, 5, 1);
929               FpRegister Sm(instr, 0, 5, 0);
930               if (op5 == 0) {
931                 opcode << (op == 0 ? "vmov" : "vabs") << (S != 0 ? ".f64" : ".f32");
932                 args << d << ", " << m;
933               } else if (op5 == 1) {
934                 opcode << (op != 0 ? "vsqrt" : "vneg") << (S != 0 ? ".f64" : ".f32");
935                 args << d << ", " << m;
936               } else if (op5 == 4) {
937                 opcode << "vcmp" << (S != 0 ? ".f64" : ".f32");
938                 args << d << ", " << m;
939                 if (op != 0) {
940                   args << " (quiet nan)";
941                 }
942               } else if (op5 == 5) {
943                 opcode << "vcmpe" << (S != 0 ? ".f64" : ".f32");
944                 args << d << ", #0.0";
945                 if (op != 0) {
946                   args << " (quiet nan)";
947                 }
948                 if ((instr & 0x2f) != 0) {
949                   args << " (UNPREDICTABLE)";
950                 }
951               } else if (op5 == 0xD) {
952                 if (S == 1) {
953                   // vcvt{r}.s32.f64
954                   opcode << "vcvt" << (op == 0 ? "r" : "") << ".s32.f64";
955                   args << Sd << ", " << Dm;
956                 } else {
957                   // vcvt{r}.s32.f32
958                   opcode << "vcvt" << (op == 0 ? "r" : "") << ".s32.f32";
959                   args << Sd << ", " << Sm;
960                 }
961               } else if (op5 == 0xC) {
962                 if (S == 1) {
963                   // vcvt{r}.u32.f64
964                   opcode << "vcvt" << (op == 0 ? "r" : "") << ".u32.f64";
965                   args << Sd << ", " << Dm;
966                 } else {
967                   // vcvt{r}.u32.f32
968                   opcode << "vcvt" << (op == 0 ? "r" : "") << ".u32.f32";
969                   args << Sd << ", " << Sm;
970                 }
971               } else if (op5 == 0x8) {
972                 if (S == 1) {
973                   // vcvt.f64.<Tm>
974                   opcode << "vcvt.f64." << (op == 0 ? "u" : "s") << "32";
975                   args << Dd << ", " << Sm;
976                 } else {
977                   // vcvt.f32.<Tm>
978                   opcode << "vcvt.f32." << (op == 0 ? "u" : "s") << "32";
979                   args << Sd << ", " << Sm;
980                 }
981               } else if (op5 == 0x7) {
982                 if (op == 1) {
983                   if (S == 1) {
984                     // vcvt.f64.f32
985                     opcode << "vcvt.f64.f32";
986                     args << Dd << ", " << Sm;
987                   } else {
988                     // vcvt.f32.f64
989                     opcode << "vcvt.f32.f64";
990                     args << Sd << ", " << Dm;
991                   }
992                 }
993               } else if ((op5 & 0xa) == 0xa) {
994                 opcode << "vcvt";
995                 args << "[undecoded: floating <-> fixed]";
996               }
997             }
998           } else if ((op3 >> 4) == 2 && op4 == 1) {     // 10xxxx, op = 1
999             if (coproc == 10 && (op3 & 0xE) == 0) {
1000               // VMOV (between ARM core register and single-precision register)
1001               // |1111|1100|000|0 |0000|1111|1100|0|00|0|0000|
1002               // |5   |1  8|7 5|4 |3  0|5  2|1  8|7|65|4|3  0|
1003               // |----|----|---|- |----|----|----|-|--|-|----|
1004               // |3322|2222|222|2 |1111|1111|1100|0|00|0|0000|
1005               // |1  8|7  4|3 1|0 |9  6|5  2|1  8|7|65|4|3  0|
1006               // |----|----|---|- |----|----|----|-|--|-|----|
1007               // |1110|1110|000|op| Vn | Rt |1010|N|00|1|0000|
1008               uint32_t op = op3 & 1;
1009               ArmRegister Rt(instr, 12);
1010               FpRegister n(instr, 16, 7);
1011               opcode << "vmov.f32";
1012               if (op) {
1013                 args << Rt << ", " << n;
1014               } else {
1015                 args << n << ", " << Rt;
1016               }
1017               if (Rt.r == 13 || Rt.r == 15 || (instr & 0x6F) != 0) {
1018                 args << " (UNPREDICTABLE)";
1019               }
1020             } else if (coproc == 10 && op3 == 0x2F) {
1021               // VMRS
1022               // |1111|11000000|0000|1111|1100|000|0|0000|
1023               // |5   |1      4|3  0|5  2|1  8|7 5|4|3  0|
1024               // |----|--------|----|----|----|---|-|----|
1025               // |3322|22222222|1111|1111|1100|000|0|0000|
1026               // |1  8|7      0|9  6|5  2|1  8|7 5|4|3  0|
1027               // |----|--------|----|----|----|---|-|----|
1028               // |1110|11101111|reg | Rt |1010|000|1|0000| - last 7 0s are (0)
1029               uint32_t spec_reg = (instr >> 16) & 0xF;
1030               ArmRegister Rt(instr, 12);
1031               opcode << "vmrs";
1032               if (spec_reg == 1) {
1033                 if (Rt.r == 15) {
1034                   args << "APSR_nzcv, FPSCR";
1035                 } else if (Rt.r == 13) {
1036                   args << Rt << ", FPSCR (UNPREDICTABLE)";
1037                 } else {
1038                   args << Rt << ", FPSCR";
1039                 }
1040               } else {
1041                 args << "(PRIVILEGED)";
1042               }
1043             } else if (coproc == 11 && (op3 & 0x9) != 8) {
1044               // VMOV (ARM core register to scalar or vice versa; 8/16/32-bit)
1045             }
1046           }
1047         }
1048       }
1049       break;
1050     case 2:
1051       if ((instr & 0x8000) == 0 && (op2 & 0x20) == 0) {
1052         // Data-processing (modified immediate)
1053         // |111|11|10|0000|0|0000|1|111|1100|00000000|
1054         // |5 3|21|09|8765|4|3  0|5|4 2|10 8|7 5    0|
1055         // |---|--|--|----|-|----|-|---|----|--------|
1056         // |332|22|22|2222|2|1111|1|111|1100|00000000|
1057         // |1 9|87|65|4321|0|9  6|5|4 2|10 8|7 5    0|
1058         // |---|--|--|----|-|----|-|---|----|--------|
1059         // |111|10|i0| op3|S| Rn |0|iii| Rd |iiiiiiii|
1060         //  111 10 x0 xxxx x xxxx opxxx xxxx xxxxxxxx
1061         uint32_t i = (instr >> 26) & 1;
1062         uint32_t op3 = (instr >> 21) & 0xF;
1063         uint32_t S = (instr >> 20) & 1;
1064         ArmRegister Rn(instr, 16);
1065         uint32_t imm3 = (instr >> 12) & 7;
1066         ArmRegister Rd(instr, 8);
1067         uint32_t imm8 = instr & 0xFF;
1068         int32_t imm32 = (i << 11) | (imm3 << 8) | imm8;
1069         if (Rn.r == 0xF && (op3 == 0x2 || op3 == 0x3)) {
1070           if (op3 == 0x2) {
1071             opcode << "mov";
1072             if (S == 1) {
1073               opcode << "s";
1074             }
1075             opcode << ".w";
1076           } else {
1077             opcode << "mvn";
1078             if (S == 1) {
1079               opcode << "s";
1080             }
1081           }
1082           args << Rd << ", #" << ThumbExpand(imm32);
1083         } else if (Rd.r == 0xF && S == 1 &&
1084                    (op3 == 0x0 || op3 == 0x4 || op3 == 0x8 || op3 == 0xD)) {
1085           if (op3 == 0x0) {
1086             opcode << "tst";
1087           } else if (op3 == 0x4) {
1088             opcode << "teq";
1089           } else if (op3 == 0x8) {
1090             opcode << "cmn.w";
1091           } else {
1092             opcode << "cmp.w";
1093           }
1094           args << Rn << ", #" << ThumbExpand(imm32);
1095         } else {
1096           switch (op3) {
1097             case 0x0: opcode << "and"; break;
1098             case 0x1: opcode << "bic"; break;
1099             case 0x2: opcode << "orr"; break;
1100             case 0x3: opcode << "orn"; break;
1101             case 0x4: opcode << "eor"; break;
1102             case 0x8: opcode << "add"; break;
1103             case 0xA: opcode << "adc"; break;
1104             case 0xB: opcode << "sbc"; break;
1105             case 0xD: opcode << "sub"; break;
1106             case 0xE: opcode << "rsb"; break;
1107             default: opcode << "UNKNOWN DPMI-" << op3; break;
1108           }
1109           if (S == 1) {
1110             opcode << "s";
1111           }
1112           args << Rd << ", " << Rn << ", #" << ThumbExpand(imm32);
1113         }
1114       } else if ((instr & 0x8000) == 0 && (op2 & 0x20) != 0) {
1115         // Data-processing (plain binary immediate)
1116         // |111|11|10|00000|0000|1|111110000000000|
1117         // |5 3|21|09|87654|3  0|5|4   0    5    0|
1118         // |---|--|--|-----|----|-|---------------|
1119         // |332|22|22|22222|1111|1|111110000000000|
1120         // |1 9|87|65|43210|9  6|5|4   0    5    0|
1121         // |---|--|--|-----|----|-|---------------|
1122         // |111|10|x1| op3 | Rn |0|xxxxxxxxxxxxxxx|
1123         uint32_t op3 = (instr >> 20) & 0x1F;
1124         switch (op3) {
1125           case 0x00: case 0x0A: {
1126             // ADD/SUB.W Rd, Rn #imm12 - 111 10 i1 0101 0 nnnn 0 iii dddd iiiiiiii
1127             ArmRegister Rd(instr, 8);
1128             ArmRegister Rn(instr, 16);
1129             uint32_t i = (instr >> 26) & 1;
1130             uint32_t imm3 = (instr >> 12) & 0x7;
1131             uint32_t imm8 = instr & 0xFF;
1132             uint32_t imm12 = (i << 11) | (imm3 << 8) | imm8;
1133             if (Rn.r != 0xF) {
1134               opcode << (op3 == 0 ? "addw" : "subw");
1135               args << Rd << ", " << Rn << ", #" << imm12;
1136             } else {
1137               opcode << "adr";
1138               args << Rd << ", ";
1139               DumpBranchTarget(args, instr_ptr + 4, (op3 == 0) ? imm12 : -imm12);
1140             }
1141             break;
1142           }
1143           case 0x04: case 0x0C: {
1144             // MOVW/T Rd, #imm16     - 111 10 i0 0010 0 iiii 0 iii dddd iiiiiiii
1145             ArmRegister Rd(instr, 8);
1146             uint32_t i = (instr >> 26) & 1;
1147             uint32_t imm3 = (instr >> 12) & 0x7;
1148             uint32_t imm8 = instr & 0xFF;
1149             uint32_t Rn = (instr >> 16) & 0xF;
1150             uint32_t imm16 = (Rn << 12) | (i << 11) | (imm3 << 8) | imm8;
1151             opcode << (op3 == 0x04 ? "movw" : "movt");
1152             args << Rd << ", #" << imm16;
1153             break;
1154           }
1155           case 0x16: {
1156             // BFI Rd, Rn, #lsb, #width - 111 10 0 11 011 0 nnnn 0 iii dddd ii 0 iiiii
1157             ArmRegister Rd(instr, 8);
1158             ArmRegister Rn(instr, 16);
1159             uint32_t msb = instr & 0x1F;
1160             uint32_t imm2 = (instr >> 6) & 0x3;
1161             uint32_t imm3 = (instr >> 12) & 0x7;
1162             uint32_t lsb = (imm3 << 2) | imm2;
1163             uint32_t width = msb - lsb + 1;
1164             if (Rn.r != 0xF) {
1165               opcode << "bfi";
1166               args << Rd << ", " << Rn << ", #" << lsb << ", #" << width;
1167             } else {
1168               opcode << "bfc";
1169               args << Rd << ", #" << lsb << ", #" << width;
1170             }
1171             break;
1172           }
1173           default:
1174             break;
1175         }
1176       } else {
1177         // Branches and miscellaneous control
1178         // |111|11|1000000|0000|1|111|1100|00000000|
1179         // |5 3|21|0987654|3  0|5|4 2|10 8|7 5    0|
1180         // |---|--|-------|----|-|---|----|--------|
1181         // |332|22|2222222|1111|1|111|1100|00000000|
1182         // |1 9|87|6543210|9  6|5|4 2|10 8|7 5    0|
1183         // |---|--|-------|----|-|---|----|--------|
1184         // |111|10| op2   |    |1|op3|op4 |        |
1185 
1186         uint32_t op3 = (instr >> 12) & 7;
1187         // uint32_t op4 = (instr >> 8) & 0xF;
1188         switch (op3) {
1189           case 0:
1190             if ((op2 & 0x38) != 0x38) {
1191               // Conditional branch
1192               // |111|11|1|0000|000000|1|1|1 |1|1 |10000000000|
1193               // |5 3|21|0|9876|543  0|5|4|3 |2|1 |0    5    0|
1194               // |---|--|-|----|------|-|-|--|-|--|-----------|
1195               // |332|22|2|2222|221111|1|1|1 |1|1 |10000000000|
1196               // |1 9|87|6|5432|109  6|5|4|3 |2|1 |0    5    0|
1197               // |---|--|-|----|------|-|-|--|-|--|-----------|
1198               // |111|10|S|cond| imm6 |1|0|J1|0|J2| imm11     |
1199               uint32_t S = (instr >> 26) & 1;
1200               uint32_t J2 = (instr >> 11) & 1;
1201               uint32_t J1 = (instr >> 13) & 1;
1202               uint32_t imm6 = (instr >> 16) & 0x3F;
1203               uint32_t imm11 = instr & 0x7FF;
1204               uint32_t cond = (instr >> 22) & 0xF;
1205               int32_t imm32 = (S << 20) |  (J2 << 19) | (J1 << 18) | (imm6 << 12) | (imm11 << 1);
1206               imm32 = (imm32 << 11) >> 11;  // sign extend 21bit immediate
1207               opcode << "b";
1208               DumpCond(opcode, cond);
1209               opcode << ".w";
1210               DumpBranchTarget(args, instr_ptr + 4, imm32);
1211             } else if (op2 == 0x3B) {
1212               // Miscellaneous control instructions
1213               uint32_t op5 = (instr >> 4) & 0xF;
1214               switch (op5) {
1215                 case 4: opcode << "dsb"; DumpMemoryDomain(args, instr & 0xF); break;
1216                 case 5: opcode << "dmb"; DumpMemoryDomain(args, instr & 0xF); break;
1217                 case 6: opcode << "isb"; DumpMemoryDomain(args, instr & 0xF); break;
1218               }
1219             }
1220             break;
1221           case 2:
1222             if ((op2 & 0x38) == 0x38) {
1223               if (op2 == 0x7F) {
1224                 opcode << "udf";
1225               }
1226               break;
1227             }
1228             FALLTHROUGH_INTENDED;  // Else deliberate fall-through to B.
1229           case 1: case 3: {
1230             // B
1231             // |111|11|1|0000|000000|11|1 |1|1 |10000000000|
1232             // |5 3|21|0|9876|543  0|54|3 |2|1 |0    5    0|
1233             // |---|--|-|----|------|--|--|-|--|-----------|
1234             // |332|22|2|2222|221111|11|1 |1|1 |10000000000|
1235             // |1 9|87|6|5  2|10   6|54|3 |2|1 |0    5    0|
1236             // |---|--|-|----|------|--|--|-|--|-----------|
1237             // |111|10|S|cond| imm6 |10|J1|0|J2| imm11     |
1238             // |111|10|S| imm10     |10|J1|1|J2| imm11     |
1239             uint32_t S = (instr >> 26) & 1;
1240             uint32_t cond = (instr >> 22) & 0xF;
1241             uint32_t J2 = (instr >> 11) & 1;
1242             uint32_t form = (instr >> 12) & 1;
1243             uint32_t J1 = (instr >> 13) & 1;
1244             uint32_t imm10 = (instr >> 16) & 0x3FF;
1245             uint32_t imm6  = (instr >> 16) & 0x3F;
1246             uint32_t imm11 = instr & 0x7FF;
1247             opcode << "b";
1248             int32_t imm32;
1249             if (form == 0) {
1250               DumpCond(opcode, cond);
1251               imm32 = (S << 20) | (J2 << 19) | (J1 << 18) | (imm6 << 12) | (imm11 << 1);
1252               imm32 = (imm32 << 11) >> 11;  // sign extend 21 bit immediate.
1253             } else {
1254               uint32_t I1 = ~(J1 ^ S);
1255               uint32_t I2 = ~(J2 ^ S);
1256               imm32 = (S << 24) | (I1 << 23) | (I2 << 22) | (imm10 << 12) | (imm11 << 1);
1257               imm32 = (imm32 << 8) >> 8;  // sign extend 24 bit immediate.
1258             }
1259             opcode << ".w";
1260             DumpBranchTarget(args, instr_ptr + 4, imm32);
1261             break;
1262           }
1263           case 4: case 6: case 5: case 7: {
1264             // BL, BLX (immediate)
1265             // |111|11|1|0000000000|11|1 |1|1 |10000000000|
1266             // |5 3|21|0|9876543  0|54|3 |2|1 |0    5    0|
1267             // |---|--|-|----------|--|--|-|--|-----------|
1268             // |332|22|2|2222221111|11|1 |1|1 |10000000000|
1269             // |1 9|87|6|5    0   6|54|3 |2|1 |0    5    0|
1270             // |---|--|-|----------|--|--|-|--|-----------|
1271             // |111|10|S| imm10    |11|J1|L|J2| imm11     |
1272             uint32_t S = (instr >> 26) & 1;
1273             uint32_t J2 = (instr >> 11) & 1;
1274             uint32_t L = (instr >> 12) & 1;
1275             uint32_t J1 = (instr >> 13) & 1;
1276             uint32_t imm10 = (instr >> 16) & 0x3FF;
1277             uint32_t imm11 = instr & 0x7FF;
1278             if (L == 0) {
1279               opcode << "bx";
1280             } else {
1281               opcode << "blx";
1282             }
1283             uint32_t I1 = ~(J1 ^ S);
1284             uint32_t I2 = ~(J2 ^ S);
1285             int32_t imm32 = (S << 24) | (I1 << 23) | (I2 << 22) | (imm10 << 12) | (imm11 << 1);
1286             imm32 = (imm32 << 8) >> 8;  // sign extend 24 bit immediate.
1287             DumpBranchTarget(args, instr_ptr + 4, imm32);
1288             break;
1289           }
1290         }
1291       }
1292       break;
1293     case 3:
1294       switch (op2) {
1295         case 0x07: case 0x0F: case 0x17: case 0x1F: {  // Explicitly UNDEFINED, A6.3.
1296           opcode << "UNDEFINED";
1297           break;
1298         }
1299         case 0x06: case 0x0E: {  // "Store single data item" undefined opcodes, A6.3.10.
1300           opcode << "UNDEFINED [store]";
1301           break;
1302         }
1303         case 0x15: case 0x1D: {  // "Load word" undefined opcodes, A6.3.7.
1304           opcode << "UNDEFINED [load]";
1305           break;
1306         }
1307         case 0x10: case 0x12: case 0x14: case 0x16: case 0x18: case 0x1A: case 0x1C: case 0x1E: {
1308           opcode << "UNKNOWN " << op2 << " [SIMD]";
1309           break;
1310         }
1311         case 0x01: case 0x00: case 0x09: case 0x08:   // {LD,ST}RB{,T}
1312         case 0x03: case 0x02: case 0x0B: case 0x0A:   // {LD,ST}RH{,T}
1313         case 0x05: case 0x04: case 0x0D: case 0x0C:   // {LD,ST}R{,T}
1314         case 0x11:            case 0x19:              // LDRSB{,T} (no signed store)
1315         case 0x13:            case 0x1B: {            // LDRSH{,T} (no signed store)
1316           // Load:
1317           // (Store is the same except that l==0 and always s==0 below.)
1318           //                       00s.whl (sign, word, half, load)
1319           // LDR{S}B  imm12: 11111|00s1001| Rn | Rt |imm12             (0x09)
1320           // LDR{S}B   imm8: 11111|00s0001| Rn | Rt |1PUW|imm8         (0x01)
1321           // LDR{S}BT  imm8: 11111|00s0001| Rn | Rt |1110|imm8         (0x01)
1322           // LDR{S}B    lit: 11111|00sU001|1111| Rt |imm12             (0x01/0x09)
1323           // LDR{S}B    reg: 11111|00s0001| Rn | Rt |000000|imm2| Rm   (0x01)
1324           // LDR{S}H  imm12: 11111|00s1011| Rn | Rt |imm12             (0x0B)
1325           // LDR{S}H   imm8: 11111|00s0011| Rn | Rt |1PUW|imm8         (0x03)
1326           // LDR{S}HT  imm8: 11111|00s0011| Rn | Rt |1110|imm8         (0x03)
1327           // LDR{S}H    lit: 11111|00sU011|1111| Rt |imm12             (0x03/0x0B)
1328           // LDR{S}H    reg: 11111|00s0011| Rn | Rt |000000|imm2| Rm   (0x03)
1329           // LDR      imm12: 11111|0001101| Rn | Rt |imm12             (0x0D)
1330           // LDR       imm8: 11111|0000101| Rn | Rt |1PUW|imm8         (0x05)
1331           // LDRT      imm8: 11111|0000101| Rn | Rt |1110|imm8         (0x05)
1332           // LDR        lit: 11111|000U101|1111| Rt |imm12             (0x05/0x0D)
1333           // LDR        reg: 11111|0000101| Rn | Rt |000000|imm2| Rm   (0x05)
1334           //
1335           // If Rt == 15, instead of load we have preload:
1336           // PLD{W}   imm12: 11111|00010W1| Rn |1111|imm12             (0x09/0x0B)
1337           // PLD{W}    imm8: 11111|00000W1| Rn |1111|1100|imm8         (0x01/0x03); -imm8
1338           // PLD        lit: 11111|000U001|1111|1111|imm12             (0x01/0x09)
1339           // PLD{W}     reg: 11111|00000W1| Rn |1111|000000|imm2| Rm   (0x01/0x03)
1340           // PLI      imm12: 11111|0011001| Rn |1111|imm12             (0x19)
1341           // PLI       imm8: 11111|0010001| Rn |1111|1100|imm8         (0x11); -imm8
1342           // PLI        lit: 11111|001U001|1111|1111|imm12             (0x01/0x09)
1343           // PLI        reg: 11111|0010001| Rn |1111|000000|imm2| Rm   (0x01/0x03)
1344 
1345           bool is_load = HasBitSet(instr, 20);
1346           bool is_half = HasBitSet(instr, 21);  // W for PLD/PLDW.
1347           bool is_word = HasBitSet(instr, 22);
1348           bool is_signed = HasBitSet(instr, 24);
1349           ArmRegister Rn(instr, 16);
1350           ArmRegister Rt(instr, 12);
1351           uint32_t imm12 = instr & 0xFFF;
1352           uint32_t U = (instr >> 23) & 1;  // U for imm12
1353           uint32_t imm8 = instr & 0xFF;
1354           uint32_t op4 = (instr >> 8) & 0xF;  // 1PUW for imm8
1355           if (Rt.r == PC && is_load && !is_word) {
1356             // PLD, PLDW, PLI
1357             const char* pld_pli = (is_signed ? "pli" : "pld");
1358             const char* w = (is_half ? "w" : "");
1359             if (is_signed && !is_half) {
1360               opcode << "UNDEFINED [PLI+W]";
1361             } else if (Rn.r == PC || U != 0u) {
1362               opcode << pld_pli << w;
1363               args << "[" << Rn << ", #" << (U != 0u ? "" : "-") << imm12 << "]";
1364               if (Rn.r == PC && is_half) {
1365                 args << " (UNPREDICTABLE)";
1366               }
1367             } else if ((instr & 0xFC0) == 0) {
1368               opcode << pld_pli << w;
1369               RmLslImm2 Rm(instr);
1370               args << "[" << Rn << ", " << Rm << "]";
1371             } else if (op4 == 0xC) {
1372               opcode << pld_pli << w;
1373               args << "[" << Rn << ", #-" << imm8 << "]";
1374             } else {
1375               opcode << "UNDEFINED [~" << pld_pli << "]";
1376             }
1377             break;
1378           }
1379           const char* ldr_str = is_load ? "ldr" : "str";
1380           const char* sign = is_signed ? "s" : "";
1381           const char* type = is_word ? "" : is_half ? "h" : "b";
1382           bool unpred = (Rt.r == SP && !is_word) || (Rt.r == PC && !is_load);
1383           if (Rn.r == PC && !is_load) {
1384             opcode << "UNDEFINED [STR-lit]";
1385             unpred = false;
1386           } else if (Rn.r == PC || U != 0u) {
1387             // Load/store with imm12 (load literal if Rn.r == PC; there's no store literal).
1388             opcode << ldr_str << sign << type << ".w";
1389             args << Rt << ", [" << Rn << ", #" << (U != 0u ? "" : "-") << imm12 << "]";
1390             if (Rn.r == TR && is_load) {
1391               args << "  ; ";
1392               Thread::DumpThreadOffset<4>(args, imm12);
1393             } else if (Rn.r == PC) {
1394               T2LitType lit_type[] = {
1395                   kT2LitUByte, kT2LitUHalf, kT2LitHexWord, kT2LitInvalid,
1396                   kT2LitUByte, kT2LitUHalf, kT2LitHexWord, kT2LitInvalid,
1397                   kT2LitSByte, kT2LitSHalf, kT2LitInvalid, kT2LitInvalid,
1398                   kT2LitSByte, kT2LitSHalf, kT2LitInvalid, kT2LitInvalid,
1399               };
1400               DCHECK_LT(op2 >> 1, arraysize(lit_type));
1401               DCHECK_NE(lit_type[op2 >> 1], kT2LitInvalid);
1402               DumpThumb2Literal(args, instr_ptr, U, imm12, lit_type[op2 >> 1]);
1403             }
1404           } else if ((instr & 0xFC0) == 0) {
1405             opcode << ldr_str << sign << type << ".w";
1406             RmLslImm2 Rm(instr);
1407             args << Rt << ", [" << Rn << ", " << Rm << "]";
1408             unpred = unpred || (Rm.rm.r == SP) || (Rm.rm.r == PC);
1409           } else if (is_word && Rn.r == SP && imm8 == 4 && op4 == (is_load ? 0xB : 0xD)) {
1410             opcode << (is_load ? "pop" : "push") << ".w";
1411             args << Rn;
1412             unpred = unpred || (Rn.r == SP);
1413           } else if ((op4 & 5) == 0) {
1414             opcode << "UNDEFINED [P = W = 0 for " << ldr_str << "]";
1415             unpred = false;
1416           } else {
1417             uint32_t P = (instr >> 10) & 1;
1418             U = (instr >> 9) & 1;
1419             uint32_t W = (instr >> 8) & 1;
1420             bool pre_index = (P != 0 && W == 1);
1421             bool post_index = (P == 0 && W == 1);
1422             const char* t = (P != 0 && U != 0 && W == 0) ? "t" : "";  // Unprivileged load/store?
1423             opcode << ldr_str << sign << type << t << ".w";
1424             args << Rt << ", [" << Rn << (post_index ? "]" : "") << ", #" << (U != 0 ? "" : "-")
1425                 << imm8 << (post_index ? "" : "]") << (pre_index ? "!" : "");
1426             unpred = (W != 0 && Rn.r == Rt.r);
1427           }
1428           if (unpred) {
1429             args << " (UNPREDICTABLE)";
1430           }
1431           break;
1432         }
1433         case 0x29: {  // 0101001
1434           // |111|11|1000000|0000|1111|1100|00|0 0|0000|
1435           // |5 3|21|0     4|3  0|5  2|1  8|76|5 4|3  0|
1436           // |---|--|-------|----|----|----|--|---|----|
1437           // |332|22|2222222|1111|1111|1100|00|0 0|0000|
1438           // |1 9|87|6     0|9  6|5  2|1  8|76|5 4|3  0|
1439           // |---|--|-------|----|----|----|--|---|----|
1440           // |111|11|0101001| Rm |1111| Rd |11|op3| Rm |
1441           // REV   - 111 11 0101001 mmmm 1111 dddd 1000 mmmm
1442           // REV16 - 111 11 0101001 mmmm 1111 dddd 1001 mmmm
1443           // RBIT  - 111 11 0101001 mmmm 1111 dddd 1010 mmmm
1444           // REVSH - 111 11 0101001 mmmm 1111 dddd 1011 mmmm
1445           if ((instr & 0xf0c0) == 0xf080) {
1446             uint32_t op3 = (instr >> 4) & 3;
1447             opcode << kThumbReverseOperations[op3];
1448             ArmRegister Rm(instr, 0);
1449             ArmRegister Rd(instr, 8);
1450             args << Rd << ", " << Rm;
1451             ArmRegister Rm2(instr, 16);
1452             if (Rm.r != Rm2.r || Rm.r == 13 || Rm.r == 15 || Rd.r == 13 || Rd.r == 15) {
1453               args << " (UNPREDICTABLE)";
1454             }
1455           }  // else unknown instruction
1456           break;
1457         }
1458       default:      // more formats
1459         if ((op2 >> 4) == 2) {      // 010xxxx
1460           // data processing (register)
1461           if ((instr & 0x0080f0f0) == 0x0000f000) {
1462             // LSL, LSR, ASR, ROR
1463             uint32_t shift_op = (instr >> 21) & 3;
1464             uint32_t S = (instr >> 20) & 1;
1465             ArmRegister Rd(instr, 8);
1466             ArmRegister Rn(instr, 16);
1467             ArmRegister Rm(instr, 0);
1468             opcode << kThumb2ShiftOperations[shift_op] << (S != 0 ? "s" : "");
1469             args << Rd << ", " << Rn << ", " << Rm;
1470           }
1471         } else if ((op2 >> 3) == 6) {       // 0110xxx
1472           // Multiply, multiply accumulate, and absolute difference
1473           op1 = (instr >> 20) & 0x7;
1474           op2 = (instr >> 4) & 0x1;
1475           ArmRegister Ra(instr, 12);
1476           ArmRegister Rn(instr, 16);
1477           ArmRegister Rm(instr, 0);
1478           ArmRegister Rd(instr, 8);
1479           switch (op1) {
1480           case 0:
1481             if (op2 == 0) {
1482               if (Ra.r == 0xf) {
1483                 opcode << "mul";
1484                 args << Rd << ", " << Rn << ", " << Rm;
1485               } else {
1486                 opcode << "mla";
1487                 args << Rd << ", " << Rn << ", " << Rm << ", " << Ra;
1488               }
1489             } else {
1490               opcode << "mls";
1491               args << Rd << ", " << Rn << ", " << Rm << ", " << Ra;
1492             }
1493             break;
1494           case 1:
1495           case 2:
1496           case 3:
1497           case 4:
1498           case 5:
1499           case 6:
1500               break;        // do these sometime
1501           }
1502         } else if ((op2 >> 3) == 7) {       // 0111xxx
1503           // Long multiply, long multiply accumulate, and divide
1504           op1 = (instr >> 20) & 0x7;
1505           op2 = (instr >> 4) & 0xf;
1506           ArmRegister Rn(instr, 16);
1507           ArmRegister Rm(instr, 0);
1508           ArmRegister Rd(instr, 8);
1509           ArmRegister RdHi(instr, 8);
1510           ArmRegister RdLo(instr, 12);
1511           switch (op1) {
1512           case 0:
1513             opcode << "smull";
1514             args << RdLo << ", " << RdHi << ", " << Rn << ", " << Rm;
1515             break;
1516           case 1:
1517             opcode << "sdiv";
1518             args << Rd << ", " << Rn << ", " << Rm;
1519             break;
1520           case 2:
1521             opcode << "umull";
1522             args << RdLo << ", " << RdHi << ", " << Rn << ", " << Rm;
1523             break;
1524           case 3:
1525             opcode << "udiv";
1526             args << Rd << ", " << Rn << ", " << Rm;
1527             break;
1528           case 4:
1529           case 5:
1530           case 6:
1531             break;      // TODO: when we generate these...
1532           }
1533         }
1534       }
1535       break;
1536     default:
1537       break;
1538   }
1539 
1540   // Apply any IT-block conditions to the opcode if necessary.
1541   if (!it_conditions_.empty()) {
1542     opcode << it_conditions_.back();
1543     it_conditions_.pop_back();
1544   }
1545   if (opcode.str().size() == 0) {
1546     opcode << "UNKNOWN " << op2;
1547   }
1548 
1549   os << FormatInstructionPointer(instr_ptr)
1550      << StringPrintf(": %08x\t%-7s ", instr, opcode.str().c_str())
1551      << args.str() << '\n';
1552   return 4;
1553 }  // NOLINT(readability/fn_size)
1554 
DumpThumb16(std::ostream & os,const uint8_t * instr_ptr)1555 size_t DisassemblerArm::DumpThumb16(std::ostream& os, const uint8_t* instr_ptr) {
1556   uint16_t instr = ReadU16(instr_ptr);
1557   bool is_32bit = ((instr & 0xF000) == 0xF000) || ((instr & 0xF800) == 0xE800);
1558   if (is_32bit) {
1559     return DumpThumb32(os, instr_ptr);
1560   } else {
1561     std::ostringstream opcode;
1562     std::ostringstream args;
1563     uint16_t opcode1 = instr >> 10;
1564     if (opcode1 < 0x10) {
1565       // shift (immediate), add, subtract, move, and compare
1566       uint16_t opcode2 = instr >> 9;
1567       switch (opcode2) {
1568         case 0x0: case 0x1: case 0x2: case 0x3: case 0x4: case 0x5: case 0x6: case 0x7:
1569         case 0x8: case 0x9: case 0xA: case 0xB: {
1570           // Logical shift left     - 00 000xx iii mmm ddd
1571           // Logical shift right    - 00 001xx iii mmm ddd
1572           // Arithmetic shift right - 00 010xx iii mmm ddd
1573           uint16_t imm5 = (instr >> 6) & 0x1F;
1574           ThumbRegister rm(instr, 3);
1575           ThumbRegister Rd(instr, 0);
1576           if (opcode2 <= 3) {
1577             opcode << "lsls";
1578           } else if (opcode2 <= 7) {
1579             opcode << "lsrs";
1580           } else {
1581             opcode << "asrs";
1582           }
1583           args << Rd << ", " << rm << ", #" << imm5;
1584           break;
1585         }
1586         case 0xC: case 0xD: case 0xE: case 0xF: {
1587           // Add register        - 00 01100 mmm nnn ddd
1588           // Sub register        - 00 01101 mmm nnn ddd
1589           // Add 3-bit immediate - 00 01110 iii nnn ddd
1590           // Sub 3-bit immediate - 00 01111 iii nnn ddd
1591           uint16_t imm3_or_Rm = (instr >> 6) & 7;
1592           ThumbRegister Rn(instr, 3);
1593           ThumbRegister Rd(instr, 0);
1594           if ((opcode2 & 2) != 0 && imm3_or_Rm == 0) {
1595             opcode << "mov";
1596           } else {
1597             if ((opcode2 & 1) == 0) {
1598               opcode << "adds";
1599             } else {
1600               opcode << "subs";
1601             }
1602           }
1603           args << Rd << ", " << Rn;
1604           if ((opcode2 & 2) == 0) {
1605             ArmRegister Rm(imm3_or_Rm);
1606             args << ", " << Rm;
1607           } else if (imm3_or_Rm != 0) {
1608             args << ", #" << imm3_or_Rm;
1609           }
1610           break;
1611         }
1612         case 0x10: case 0x11: case 0x12: case 0x13:
1613         case 0x14: case 0x15: case 0x16: case 0x17:
1614         case 0x18: case 0x19: case 0x1A: case 0x1B:
1615         case 0x1C: case 0x1D: case 0x1E: case 0x1F: {
1616           // MOVS Rd, #imm8 - 00100 ddd iiiiiiii
1617           // CMP  Rn, #imm8 - 00101 nnn iiiiiiii
1618           // ADDS Rn, #imm8 - 00110 nnn iiiiiiii
1619           // SUBS Rn, #imm8 - 00111 nnn iiiiiiii
1620           ThumbRegister Rn(instr, 8);
1621           uint16_t imm8 = instr & 0xFF;
1622           switch (opcode2 >> 2) {
1623             case 4: opcode << "movs"; break;
1624             case 5: opcode << "cmp"; break;
1625             case 6: opcode << "adds"; break;
1626             case 7: opcode << "subs"; break;
1627           }
1628           args << Rn << ", #" << imm8;
1629           break;
1630         }
1631         default:
1632           break;
1633       }
1634     } else if (opcode1 == 0x10) {
1635       // Data-processing
1636       uint16_t opcode2 = (instr >> 6) & 0xF;
1637       ThumbRegister rm(instr, 3);
1638       ThumbRegister rdn(instr, 0);
1639       opcode << kThumbDataProcessingOperations[opcode2];
1640       args << rdn << ", " << rm;
1641     } else if (opcode1 == 0x11) {
1642       // Special data instructions and branch and exchange
1643       uint16_t opcode2 = (instr >> 6) & 0x0F;
1644       switch (opcode2) {
1645         case 0x0: case 0x1: case 0x2: case 0x3: {
1646           // Add low registers  - 010001 0000 xxxxxx
1647           // Add high registers - 010001 0001/001x xxxxxx
1648           uint16_t DN = (instr >> 7) & 1;
1649           ArmRegister rm(instr, 3);
1650           uint16_t Rdn = instr & 7;
1651           ArmRegister DN_Rdn((DN << 3) | Rdn);
1652           opcode << "add";
1653           args << DN_Rdn << ", " << rm;
1654           break;
1655         }
1656         case 0x8: case 0x9: case 0xA: case 0xB: {
1657           // Move low registers  - 010001 1000 xxxxxx
1658           // Move high registers - 010001 1001/101x xxxxxx
1659           uint16_t DN = (instr >> 7) & 1;
1660           ArmRegister rm(instr, 3);
1661           uint16_t Rdn = instr & 7;
1662           ArmRegister DN_Rdn((DN << 3) | Rdn);
1663           opcode << "mov";
1664           args << DN_Rdn << ", " << rm;
1665           break;
1666         }
1667         case 0x5: case 0x6: case 0x7: {
1668           // Compare high registers - 010001 0101/011x xxxxxx
1669           uint16_t N = (instr >> 7) & 1;
1670           ArmRegister rm(instr, 3);
1671           uint16_t Rn = instr & 7;
1672           ArmRegister N_Rn((N << 3) | Rn);
1673           opcode << "cmp";
1674           args << N_Rn << ", " << rm;
1675           break;
1676         }
1677         case 0xC: case 0xD: case 0xE: case 0xF: {
1678           // Branch and exchange           - 010001 110x xxxxxx
1679           // Branch with link and exchange - 010001 111x xxxxxx
1680           ArmRegister rm(instr, 3);
1681           opcode << ((opcode2 & 0x2) == 0 ? "bx" : "blx");
1682           args << rm;
1683           break;
1684         }
1685         default:
1686           break;
1687       }
1688     } else if (opcode1 == 0x12 || opcode1 == 0x13) {  // 01001x
1689       ThumbRegister Rt(instr, 8);
1690       uint16_t imm8 = instr & 0xFF;
1691       opcode << "ldr";
1692       args << Rt << ", [pc, #" << (imm8 << 2) << "]";
1693     } else if ((opcode1 >= 0x14 && opcode1 <= 0x17) ||  // 0101xx
1694                (opcode1 >= 0x18 && opcode1 <= 0x1f) ||  // 011xxx
1695                (opcode1 >= 0x20 && opcode1 <= 0x27)) {  // 100xxx
1696       // Load/store single data item
1697       uint16_t opA = (instr >> 12) & 0xF;
1698       if (opA == 0x5) {
1699         uint16_t opB = (instr >> 9) & 0x7;
1700         ThumbRegister Rm(instr, 6);
1701         ThumbRegister Rn(instr, 3);
1702         ThumbRegister Rt(instr, 0);
1703         switch (opB) {
1704           case 0: opcode << "str"; break;
1705           case 1: opcode << "strh"; break;
1706           case 2: opcode << "strb"; break;
1707           case 3: opcode << "ldrsb"; break;
1708           case 4: opcode << "ldr"; break;
1709           case 5: opcode << "ldrh"; break;
1710           case 6: opcode << "ldrb"; break;
1711           case 7: opcode << "ldrsh"; break;
1712         }
1713         args << Rt << ", [" << Rn << ", " << Rm << "]";
1714       } else if (opA == 9) {
1715         uint16_t opB = (instr >> 11) & 1;
1716         ThumbRegister Rt(instr, 8);
1717         uint16_t imm8 = instr & 0xFF;
1718         opcode << (opB == 0 ? "str" : "ldr");
1719         args << Rt << ", [sp, #" << (imm8 << 2) << "]";
1720       } else {
1721         uint16_t imm5 = (instr >> 6) & 0x1F;
1722         uint16_t opB = (instr >> 11) & 1;
1723         ThumbRegister Rn(instr, 3);
1724         ThumbRegister Rt(instr, 0);
1725         switch (opA) {
1726           case 6:
1727             imm5 <<= 2;
1728             opcode << (opB == 0 ? "str" : "ldr");
1729             break;
1730           case 7:
1731             imm5 <<= 0;
1732             opcode << (opB == 0 ? "strb" : "ldrb");
1733             break;
1734           case 8:
1735             imm5 <<= 1;
1736             opcode << (opB == 0 ? "strh" : "ldrh");
1737             break;
1738         }
1739         args << Rt << ", [" << Rn << ", #" << imm5 << "]";
1740       }
1741     } else if (opcode1 >= 0x34 && opcode1 <= 0x37) {  // 1101xx
1742       int8_t imm8 = instr & 0xFF;
1743       uint32_t cond = (instr >> 8) & 0xF;
1744       opcode << "b";
1745       DumpCond(opcode, cond);
1746       DumpBranchTarget(args, instr_ptr + 4, (imm8 << 1));
1747     } else if ((instr & 0xF800) == 0xA800) {
1748       // Generate SP-relative address
1749       ThumbRegister rd(instr, 8);
1750       int imm8 = instr & 0xFF;
1751       opcode << "add";
1752       args << rd << ", sp, #" << (imm8 << 2);
1753     } else if ((instr & 0xF000) == 0xB000) {
1754       // Miscellaneous 16-bit instructions
1755       uint16_t opcode2 = (instr >> 5) & 0x7F;
1756       switch (opcode2) {
1757         case 0x00: case 0x01: case 0x02: case 0x03: case 0x04: case 0x05: case 0x06: case 0x07: {
1758           // Add immediate to SP        - 1011 00000 ii iiiii
1759           // Subtract immediate from SP - 1011 00001 ii iiiii
1760           int imm7 = instr & 0x7F;
1761           opcode << ((opcode2 & 4) == 0 ? "add" : "sub");
1762           args << "sp, sp, #" << (imm7 << 2);
1763           break;
1764         }
1765         case 0x08: case 0x09: case 0x0A: case 0x0B:  // 0001xxx
1766         case 0x0C: case 0x0D: case 0x0E: case 0x0F:
1767         case 0x18: case 0x19: case 0x1A: case 0x1B:  // 0011xxx
1768         case 0x1C: case 0x1D: case 0x1E: case 0x1F:
1769         case 0x48: case 0x49: case 0x4A: case 0x4B:  // 1001xxx
1770         case 0x4C: case 0x4D: case 0x4E: case 0x4F:
1771         case 0x58: case 0x59: case 0x5A: case 0x5B:  // 1011xxx
1772         case 0x5C: case 0x5D: case 0x5E: case 0x5F: {
1773           // CBNZ, CBZ
1774           uint16_t op = (instr >> 11) & 1;
1775           uint16_t i = (instr >> 9) & 1;
1776           uint16_t imm5 = (instr >> 3) & 0x1F;
1777           ThumbRegister Rn(instr, 0);
1778           opcode << (op != 0 ? "cbnz" : "cbz");
1779           uint32_t imm32 = (i << 6) | (imm5 << 1);
1780           args << Rn << ", ";
1781           DumpBranchTarget(args, instr_ptr + 4, imm32);
1782           break;
1783         }
1784         case 0x20: case 0x21: case 0x22: case 0x23: case 0x24: case 0x25: case 0x26: case 0x27:
1785         case 0x28: case 0x29: case 0x2A: case 0x2B: case 0x2C: case 0x2D: case 0x2E: case 0x2F: {
1786           opcode << "push";
1787           args << RegisterList((instr & 0xFF) | ((instr & 0x100) << 6));
1788           break;
1789         }
1790         case 0x60: case 0x61: case 0x62: case 0x63: case 0x64: case 0x65: case 0x66: case 0x67:
1791         case 0x68: case 0x69: case 0x6A: case 0x6B: case 0x6C: case 0x6D: case 0x6E: case 0x6F: {
1792           opcode << "pop";
1793           args << RegisterList((instr & 0xFF) | ((instr & 0x100) << 7));
1794           break;
1795         }
1796         case 0x70: case 0x71: case 0x72: case 0x73: case 0x74: case 0x75: case 0x76: case 0x77: {
1797           opcode << "bkpt";
1798           args << "#" << (instr & 0xFF);
1799           break;
1800         }
1801         case 0x50: case 0x51:    // 101000x
1802         case 0x52: case 0x53:    // 101001x
1803         case 0x56: case 0x57: {  // 101011x
1804           uint16_t op = (instr >> 6) & 3;
1805           opcode << kThumbReverseOperations[op];
1806           ThumbRegister Rm(instr, 3);
1807           ThumbRegister Rd(instr, 0);
1808           args << Rd << ", " << Rm;
1809           break;
1810         }
1811         case 0x78: case 0x79: case 0x7A: case 0x7B:  // 1111xxx
1812         case 0x7C: case 0x7D: case 0x7E: case 0x7F: {
1813           // If-Then, and hints
1814           uint16_t opA = (instr >> 4) & 0xF;
1815           uint16_t opB = instr & 0xF;
1816           if (opB == 0) {
1817             switch (opA) {
1818               case 0: opcode << "nop"; break;
1819               case 1: opcode << "yield"; break;
1820               case 2: opcode << "wfe";  break;
1821               case 3: opcode << "sev"; break;
1822               default: break;
1823             }
1824           } else {
1825             uint32_t first_cond = opA;
1826             uint32_t mask = opB;
1827             opcode << "it";
1828 
1829             // Flesh out the base "it" opcode with the specific collection of 't's and 'e's,
1830             // and store up the actual condition codes we'll want to add to the next few opcodes.
1831             size_t count = 3 - CTZ(mask);
1832             it_conditions_.resize(count + 2);  // Plus the implicit 't', plus the "" for the IT itself.
1833             for (size_t i = 0; i < count; ++i) {
1834               bool positive_cond = ((first_cond & 1) != 0);
1835               bool positive_mask = ((mask & (1 << (3 - i))) != 0);
1836               if (positive_mask == positive_cond) {
1837                 opcode << 't';
1838                 it_conditions_[i] = kConditionCodeNames[first_cond];
1839               } else {
1840                 opcode << 'e';
1841                 it_conditions_[i] = kConditionCodeNames[first_cond ^ 1];
1842               }
1843             }
1844             it_conditions_[count] = kConditionCodeNames[first_cond];  // The implicit 't'.
1845 
1846             it_conditions_[count + 1] = "";  // No condition code for the IT itself...
1847             DumpCond(args, first_cond);  // ...because it's considered an argument.
1848           }
1849           break;
1850         }
1851         default:
1852           break;
1853       }
1854     } else if (((instr & 0xF000) == 0x5000) || ((instr & 0xE000) == 0x6000) ||
1855         ((instr & 0xE000) == 0x8000)) {
1856       // Load/store single data item
1857       uint16_t opA = instr >> 12;
1858       // uint16_t opB = (instr >> 9) & 7;
1859       switch (opA) {
1860         case 0x6: {
1861           // STR Rt, [Rn, #imm] - 01100 iiiii nnn ttt
1862           // LDR Rt, [Rn, #imm] - 01101 iiiii nnn ttt
1863           uint16_t imm5 = (instr >> 6) & 0x1F;
1864           ThumbRegister Rn(instr, 3);
1865           ThumbRegister Rt(instr, 0);
1866           opcode << ((instr & 0x800) == 0 ? "str" : "ldr");
1867           args << Rt << ", [" << Rn << ", #" << (imm5 << 2) << "]";
1868           break;
1869         }
1870         case 0x9: {
1871           // STR Rt, [SP, #imm] - 01100 ttt iiiiiiii
1872           // LDR Rt, [SP, #imm] - 01101 ttt iiiiiiii
1873           uint16_t imm8 = instr & 0xFF;
1874           ThumbRegister Rt(instr, 8);
1875           opcode << ((instr & 0x800) == 0 ? "str" : "ldr");
1876           args << Rt << ", [sp, #" << (imm8 << 2) << "]";
1877           break;
1878         }
1879         default:
1880           break;
1881       }
1882     } else if (opcode1 == 0x38 || opcode1 == 0x39) {
1883       uint16_t imm11 = instr & 0x7FFF;
1884       int32_t imm32 = imm11 << 1;
1885       imm32 = (imm32 << 20) >> 20;  // sign extend 12 bit immediate
1886       opcode << "b";
1887       DumpBranchTarget(args, instr_ptr + 4, imm32);
1888     }
1889 
1890     // Apply any IT-block conditions to the opcode if necessary.
1891     if (!it_conditions_.empty()) {
1892       opcode << it_conditions_.back();
1893       it_conditions_.pop_back();
1894     }
1895 
1896     os << FormatInstructionPointer(instr_ptr)
1897        << StringPrintf(": %04x    \t%-7s ", instr, opcode.str().c_str())
1898        << args.str() << '\n';
1899   }
1900   return 2;
1901 }
1902 
1903 }  // namespace arm
1904 }  // namespace art
1905