xref: /llvm-project/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp (revision 3987a61c16f64982e0364bbdc4203345ff9f6030)
1 //===- ARMDisassembler.cpp - Disassembler for ARM/Thumb ISA -----*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #define DEBUG_TYPE "arm-disassembler"
11 
12 #include "ARMDisassembler.h"
13 #include "ARM.h"
14 #include "ARMRegisterInfo.h"
15 #include "MCTargetDesc/ARMAddressingModes.h"
16 #include "MCTargetDesc/ARMBaseInfo.h"
17 #include "llvm/MC/EDInstInfo.h"
18 #include "llvm/MC/MCInst.h"
19 #include "llvm/MC/MCExpr.h"
20 #include "llvm/MC/MCContext.h"
21 #include "llvm/Target/TargetRegistry.h"
22 #include "llvm/Support/Debug.h"
23 #include "llvm/Support/MemoryObject.h"
24 #include "llvm/Support/ErrorHandling.h"
25 #include "llvm/Support/raw_ostream.h"
26 
27 // Forward declare these because the autogenerated code will reference them.
28 // Definitions are further down.
29 static bool DecodeGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
30                                    uint64_t Address, const void *Decoder);
31 static bool DecodeGPRnopcRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
32                                    uint64_t Address, const void *Decoder);
33 static bool DecodetGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
34                                    uint64_t Address, const void *Decoder);
35 static bool DecodetcGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
36                                    uint64_t Address, const void *Decoder);
37 static bool DecoderGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
38                                    uint64_t Address, const void *Decoder);
39 static bool DecodeSPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
40                                    uint64_t Address, const void *Decoder);
41 static bool DecodeDPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
42                                    uint64_t Address, const void *Decoder);
43 static bool DecodeDPR_8RegisterClass(llvm::MCInst &Inst, unsigned RegNo,
44                                    uint64_t Address, const void *Decoder);
45 static bool DecodeDPR_VFP2RegisterClass(llvm::MCInst &Inst, unsigned RegNo,
46                                    uint64_t Address, const void *Decoder);
47 static bool DecodeQPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
48                                    uint64_t Address, const void *Decoder);
49 
50 static bool DecodePredicateOperand(llvm::MCInst &Inst, unsigned Val,
51                                uint64_t Address, const void *Decoder);
52 static bool DecodeCCOutOperand(llvm::MCInst &Inst, unsigned Val,
53                                uint64_t Address, const void *Decoder);
54 static bool DecodeSOImmOperand(llvm::MCInst &Inst, unsigned Val,
55                                uint64_t Address, const void *Decoder);
56 static bool DecodeBLTargetOperand(llvm::MCInst &Inst, unsigned Val,
57                                uint64_t Address, const void *Decoder);
58 static bool DecodeRegListOperand(llvm::MCInst &Inst, unsigned Val,
59                                uint64_t Address, const void *Decoder);
60 static bool DecodeSPRRegListOperand(llvm::MCInst &Inst, unsigned Val,
61                                uint64_t Address, const void *Decoder);
62 static bool DecodeDPRRegListOperand(llvm::MCInst &Inst, unsigned Val,
63                                uint64_t Address, const void *Decoder);
64 
65 static bool DecodeBitfieldMaskOperand(llvm::MCInst &Inst, unsigned Insn,
66                                uint64_t Address, const void *Decoder);
67 static bool DecodeCopMemInstruction(llvm::MCInst &Inst, unsigned Insn,
68                                uint64_t Address, const void *Decoder);
69 static bool DecodeAddrMode2IdxInstruction(llvm::MCInst &Inst, unsigned Insn,
70                                uint64_t Address, const void *Decoder);
71 static bool DecodeSORegMemOperand(llvm::MCInst &Inst, unsigned Insn,
72                                uint64_t Address, const void *Decoder);
73 static bool DecodeAddrMode3Instruction(llvm::MCInst &Inst, unsigned Insn,
74                                uint64_t Address, const void *Decoder);
75 static bool DecodeSORegImmOperand(llvm::MCInst &Inst, unsigned Insn,
76                                uint64_t Address, const void *Decoder);
77 static bool DecodeSORegRegOperand(llvm::MCInst &Inst, unsigned Insn,
78                                uint64_t Address, const void *Decoder);
79 
80 static bool DecodeMemMultipleWritebackInstruction(llvm::MCInst & Inst,
81                                                   unsigned Insn,
82                                                   uint64_t Adddress,
83                                                   const void *Decoder);
84 static bool DecodeSMLAInstruction(llvm::MCInst &Inst, unsigned Insn,
85                                uint64_t Address, const void *Decoder);
86 static bool DecodeCPSInstruction(llvm::MCInst &Inst, unsigned Insn,
87                                uint64_t Address, const void *Decoder);
88 static bool DecodeAddrModeImm12Operand(llvm::MCInst &Inst, unsigned Val,
89                                uint64_t Address, const void *Decoder);
90 static bool DecodeAddrMode5Operand(llvm::MCInst &Inst, unsigned Val,
91                                uint64_t Address, const void *Decoder);
92 static bool DecodeAddrMode7Operand(llvm::MCInst &Inst, unsigned Val,
93                                uint64_t Address, const void *Decoder);
94 static bool DecodeBranchImmInstruction(llvm::MCInst &Inst, unsigned Insn,
95                                uint64_t Address, const void *Decoder);
96 static bool DecodeVCVTImmOperand(llvm::MCInst &Inst, unsigned Val,
97                                uint64_t Address, const void *Decoder);
98 static bool DecodeAddrMode6Operand(llvm::MCInst &Inst, unsigned Val,
99                                uint64_t Address, const void *Decoder);
100 static bool DecodeVLDInstruction(llvm::MCInst &Inst, unsigned Val,
101                                uint64_t Address, const void *Decoder);
102 static bool DecodeVSTInstruction(llvm::MCInst &Inst, unsigned Val,
103                                uint64_t Address, const void *Decoder);
104 static bool DecodeVLD1DupInstruction(llvm::MCInst &Inst, unsigned Val,
105                                uint64_t Address, const void *Decoder);
106 static bool DecodeVLD2DupInstruction(llvm::MCInst &Inst, unsigned Val,
107                                uint64_t Address, const void *Decoder);
108 static bool DecodeVLD3DupInstruction(llvm::MCInst &Inst, unsigned Val,
109                                uint64_t Address, const void *Decoder);
110 static bool DecodeVLD4DupInstruction(llvm::MCInst &Inst, unsigned Val,
111                                uint64_t Address, const void *Decoder);
112 static bool DecodeNEONModImmInstruction(llvm::MCInst &Inst, unsigned Val,
113                                uint64_t Address, const void *Decoder);
114 static bool DecodeVSHLMaxInstruction(llvm::MCInst &Inst, unsigned Val,
115                                uint64_t Address, const void *Decoder);
116 static bool DecodeShiftRight8Imm(llvm::MCInst &Inst, unsigned Val,
117                                uint64_t Address, const void *Decoder);
118 static bool DecodeShiftRight16Imm(llvm::MCInst &Inst, unsigned Val,
119                                uint64_t Address, const void *Decoder);
120 static bool DecodeShiftRight32Imm(llvm::MCInst &Inst, unsigned Val,
121                                uint64_t Address, const void *Decoder);
122 static bool DecodeShiftRight64Imm(llvm::MCInst &Inst, unsigned Val,
123                                uint64_t Address, const void *Decoder);
124 static bool DecodeTBLInstruction(llvm::MCInst &Inst, unsigned Insn,
125                                uint64_t Address, const void *Decoder);
126 static bool DecodeVFPfpImm(llvm::MCInst &Inst, unsigned Val,
127                                uint64_t Address, const void *Decoder);
128 static bool DecodePostIdxReg(llvm::MCInst &Inst, unsigned Insn,
129                                uint64_t Address, const void *Decoder);
130 static bool DecodeCoprocessor(llvm::MCInst &Inst, unsigned Insn,
131                                uint64_t Address, const void *Decoder);
132 static bool DecodeAddrMode3Offset(llvm::MCInst &Inst, unsigned Insn,
133                                uint64_t Address, const void *Decoder);
134 static bool DecodeMemBarrierOption(llvm::MCInst &Inst, unsigned Insn,
135                                uint64_t Address, const void *Decoder);
136 static bool DecodeMSRMask(llvm::MCInst &Inst, unsigned Insn,
137                                uint64_t Address, const void *Decoder);
138 static bool DecodeDoubleRegLoad(llvm::MCInst &Inst, unsigned Insn,
139                                uint64_t Address, const void *Decoder);
140 static bool DecodeDoubleRegStore(llvm::MCInst &Inst, unsigned Insn,
141                                uint64_t Address, const void *Decoder);
142 static bool DecodeSTRPreImm(llvm::MCInst &Inst, unsigned Insn,
143                                uint64_t Address, const void *Decoder);
144 static bool DecodeSTRPreReg(llvm::MCInst &Inst, unsigned Insn,
145                                uint64_t Address, const void *Decoder);
146 
147 
148 static bool DecodeThumbAddSpecialReg(llvm::MCInst &Inst, uint16_t Insn,
149                                uint64_t Address, const void *Decoder);
150 static bool DecodeThumbBROperand(llvm::MCInst &Inst, unsigned Val,
151                                uint64_t Address, const void *Decoder);
152 static bool DecodeT2BROperand(llvm::MCInst &Inst, unsigned Val,
153                                uint64_t Address, const void *Decoder);
154 static bool DecodeThumbCmpBROperand(llvm::MCInst &Inst, unsigned Val,
155                                uint64_t Address, const void *Decoder);
156 static bool DecodeThumbAddrModeRR(llvm::MCInst &Inst, unsigned Val,
157                                uint64_t Address, const void *Decoder);
158 static bool DecodeThumbAddrModeIS(llvm::MCInst &Inst, unsigned Val,
159                                uint64_t Address, const void *Decoder);
160 static bool DecodeThumbAddrModePC(llvm::MCInst &Inst, unsigned Val,
161                                uint64_t Address, const void *Decoder);
162 static bool DecodeThumbAddrModeSP(llvm::MCInst &Inst, unsigned Val,
163                                uint64_t Address, const void *Decoder);
164 static bool DecodeT2AddrModeSOReg(llvm::MCInst &Inst, unsigned Val,
165                                uint64_t Address, const void *Decoder);
166 static bool DecodeT2LoadShift(llvm::MCInst &Inst, unsigned Val,
167                                uint64_t Address, const void *Decoder);
168 static bool DecodeT2Imm8S4(llvm::MCInst &Inst, unsigned Val,
169                                uint64_t Address, const void *Decoder);
170 static bool DecodeT2AddrModeImm8s4(llvm::MCInst &Inst, unsigned Val,
171                                uint64_t Address, const void *Decoder);
172 static bool DecodeT2Imm8(llvm::MCInst &Inst, unsigned Val,
173                                uint64_t Address, const void *Decoder);
174 static bool DecodeT2AddrModeImm8(llvm::MCInst &Inst, unsigned Val,
175                                uint64_t Address, const void *Decoder);
176 static bool DecodeThumbAddSPImm(llvm::MCInst &Inst, uint16_t Val,
177                                uint64_t Address, const void *Decoder);
178 static bool DecodeThumbAddSPReg(llvm::MCInst &Inst, uint16_t Insn,
179                                 uint64_t Address, const void *Decoder);
180 static bool DecodeThumbCPS(llvm::MCInst &Inst, uint16_t Insn,
181                                 uint64_t Address, const void *Decoder);
182 static bool DecodeThumbBLXOffset(llvm::MCInst &Inst, unsigned Insn,
183                                 uint64_t Address, const void *Decoder);
184 static bool DecodeT2AddrModeImm12(llvm::MCInst &Inst, unsigned Val,
185                                 uint64_t Address, const void *Decoder);
186 static bool DecodeThumbSRImm(llvm::MCInst &Inst, unsigned Val,
187                                 uint64_t Address, const void *Decoder);
188 static bool DecodeThumb2BCCInstruction(llvm::MCInst &Inst, unsigned Val,
189                                 uint64_t Address, const void *Decoder);
190 static bool DecodeT2SOImm(llvm::MCInst &Inst, unsigned Val,
191                                 uint64_t Address, const void *Decoder);
192 static bool DecodeThumbBCCTargetOperand(llvm::MCInst &Inst, unsigned Val,
193                                 uint64_t Address, const void *Decoder);
194 static bool DecodeThumbBLTargetOperand(llvm::MCInst &Inst, unsigned Val,
195                                 uint64_t Address, const void *Decoder);
196 
197 #include "ARMGenDisassemblerTables.inc"
198 #include "ARMGenInstrInfo.inc"
199 #include "ARMGenEDInfo.inc"
200 
201 using namespace llvm;
202 
203 static MCDisassembler *createARMDisassembler(const Target &T) {
204   return new ARMDisassembler;
205 }
206 
207 static MCDisassembler *createThumbDisassembler(const Target &T) {
208   return new ThumbDisassembler;
209 }
210 
211 EDInstInfo *ARMDisassembler::getEDInfo() const {
212   return instInfoARM;
213 }
214 
215 EDInstInfo *ThumbDisassembler::getEDInfo() const {
216   return instInfoARM;
217 }
218 
219 
220 bool ARMDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
221                                      const MemoryObject &Region,
222                                      uint64_t Address,raw_ostream &os) const {
223   uint8_t bytes[4];
224 
225   // We want to read exactly 4 bytes of data.
226   if (Region.readBytes(Address, 4, (uint8_t*)bytes, NULL) == -1)
227     return false;
228 
229   // Encoded as a small-endian 32-bit word in the stream.
230   uint32_t insn = (bytes[3] << 24) |
231                   (bytes[2] << 16) |
232                   (bytes[1] <<  8) |
233                   (bytes[0] <<  0);
234 
235   // Calling the auto-generated decoder function.
236   bool result = decodeARMInstruction32(MI, insn, Address, this);
237   if (result) {
238     Size = 4;
239     return true;
240   }
241 
242   // Instructions that are shared between ARM and Thumb modes.
243   // FIXME: This shouldn't really exist.  It's an artifact of the
244   // fact that we fail to encode a few instructions properly for Thumb.
245   MI.clear();
246   result = decodeCommonInstruction32(MI, insn, Address, this);
247   if (result) {
248     Size = 4;
249     return true;
250   }
251 
252   // VFP and NEON instructions, similarly, are shared between ARM
253   // and Thumb modes.
254   MI.clear();
255   result = decodeVFPInstruction32(MI, insn, Address, this);
256   if (result) {
257     Size = 4;
258     return true;
259   }
260 
261   MI.clear();
262   result = decodeNEONDataInstruction32(MI, insn, Address, this);
263   if (result) {
264     Size = 4;
265     // Add a fake predicate operand, because we share these instruction
266     // definitions with Thumb2 where these instructions are predicable.
267     if (!DecodePredicateOperand(MI, 0xE, Address, this)) return false;
268     return true;
269   }
270 
271   MI.clear();
272   result = decodeNEONLoadStoreInstruction32(MI, insn, Address, this);
273   if (result) {
274     Size = 4;
275     // Add a fake predicate operand, because we share these instruction
276     // definitions with Thumb2 where these instructions are predicable.
277     if (!DecodePredicateOperand(MI, 0xE, Address, this)) return false;
278     return true;
279   }
280 
281   MI.clear();
282   result = decodeNEONDupInstruction32(MI, insn, Address, this);
283   if (result) {
284     Size = 4;
285     // Add a fake predicate operand, because we share these instruction
286     // definitions with Thumb2 where these instructions are predicable.
287     if (!DecodePredicateOperand(MI, 0xE, Address, this)) return false;
288     return true;
289   }
290 
291   MI.clear();
292 
293   return false;
294 }
295 
296 namespace llvm {
297 extern MCInstrDesc ARMInsts[];
298 }
299 
300 // Thumb1 instructions don't have explicit S bits.  Rather, they
301 // implicitly set CPSR.  Since it's not represented in the encoding, the
302 // auto-generated decoder won't inject the CPSR operand.  We need to fix
303 // that as a post-pass.
304 static void AddThumb1SBit(MCInst &MI, bool InITBlock) {
305   const MCOperandInfo *OpInfo = ARMInsts[MI.getOpcode()].OpInfo;
306   MCInst::iterator I = MI.begin();
307   for (unsigned i = 0, e = MI.size(); i < e; ++i, ++I) {
308     if (OpInfo[i].isOptionalDef() && OpInfo[i].RegClass == ARM::CCRRegClassID) {
309       MI.insert(I, MCOperand::CreateReg(InITBlock ? 0 : ARM::CPSR));
310       return;
311     }
312   }
313 
314   if (OpInfo[MI.size()].isOptionalDef() &&
315       OpInfo[MI.size()].RegClass == ARM::CCRRegClassID)
316     MI.insert(MI.end(), MCOperand::CreateReg(InITBlock ? 0 : ARM::CPSR));
317 }
318 
319 // Most Thumb instructions don't have explicit predicates in the
320 // encoding, but rather get their predicates from IT context.  We need
321 // to fix up the predicate operands using this context information as a
322 // post-pass.
323 void ThumbDisassembler::AddThumbPredicate(MCInst &MI) const {
324   // A few instructions actually have predicates encoded in them.  Don't
325   // try to overwrite it if we're seeing one of those.
326   switch (MI.getOpcode()) {
327     case ARM::tBcc:
328     case ARM::t2Bcc:
329       return;
330     default:
331       break;
332   }
333 
334   // If we're in an IT block, base the predicate on that.  Otherwise,
335   // assume a predicate of AL.
336   unsigned CC;
337   if (!ITBlock.empty()) {
338     CC = ITBlock.back();
339     ITBlock.pop_back();
340   } else
341     CC = ARMCC::AL;
342 
343   const MCOperandInfo *OpInfo = ARMInsts[MI.getOpcode()].OpInfo;
344   MCInst::iterator I = MI.begin();
345   for (unsigned i = 0, e = MI.size(); i < e; ++i, ++I) {
346     if (OpInfo[i].isPredicate()) {
347       I = MI.insert(I, MCOperand::CreateImm(CC));
348       ++I;
349       if (CC == ARMCC::AL)
350         MI.insert(I, MCOperand::CreateReg(0));
351       else
352         MI.insert(I, MCOperand::CreateReg(ARM::CPSR));
353       return;
354     }
355   }
356 
357   MI.insert(MI.end(), MCOperand::CreateImm(CC));
358   if (CC == ARMCC::AL)
359     MI.insert(MI.end(), MCOperand::CreateReg(0));
360   else
361     MI.insert(MI.end(), MCOperand::CreateReg(ARM::CPSR));
362 }
363 
364 // Thumb VFP instructions are a special case.  Because we share their
365 // encodings between ARM and Thumb modes, and they are predicable in ARM
366 // mode, the auto-generated decoder will give them an (incorrect)
367 // predicate operand.  We need to rewrite these operands based on the IT
368 // context as a post-pass.
369 void ThumbDisassembler::UpdateThumbVFPPredicate(MCInst &MI) const {
370   unsigned CC;
371   if (!ITBlock.empty()) {
372     CC = ITBlock.back();
373     ITBlock.pop_back();
374   } else
375     CC = ARMCC::AL;
376 
377   const MCOperandInfo *OpInfo = ARMInsts[MI.getOpcode()].OpInfo;
378   MCInst::iterator I = MI.begin();
379   for (unsigned i = 0, e = MI.size(); i < e; ++i, ++I) {
380     if (OpInfo[i].isPredicate() ) {
381       I->setImm(CC);
382       ++I;
383       if (CC == ARMCC::AL)
384         I->setReg(0);
385       else
386         I->setReg(ARM::CPSR);
387       return;
388     }
389   }
390 }
391 
392 
393 bool ThumbDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
394                                        const MemoryObject &Region,
395                                        uint64_t Address,raw_ostream &os) const {
396   uint8_t bytes[4];
397 
398   // We want to read exactly 2 bytes of data.
399   if (Region.readBytes(Address, 2, (uint8_t*)bytes, NULL) == -1)
400     return false;
401 
402   uint16_t insn16 = (bytes[1] << 8) | bytes[0];
403   bool result = decodeThumbInstruction16(MI, insn16, Address, this);
404   if (result) {
405     Size = 2;
406     bool InITBlock = !ITBlock.empty();
407     AddThumbPredicate(MI);
408     AddThumb1SBit(MI, InITBlock);
409     return true;
410   }
411 
412   MI.clear();
413   result = decodeThumb2Instruction16(MI, insn16, Address, this);
414   if (result) {
415     Size = 2;
416     AddThumbPredicate(MI);
417 
418     // If we find an IT instruction, we need to parse its condition
419     // code and mask operands so that we can apply them correctly
420     // to the subsequent instructions.
421     if (MI.getOpcode() == ARM::t2IT) {
422       unsigned firstcond = MI.getOperand(0).getImm();
423       uint32_t mask = MI.getOperand(1).getImm();
424       unsigned zeros = CountTrailingZeros_32(mask);
425       mask >>= zeros+1;
426 
427       for (unsigned i = 0; i < 4 - (zeros+1); ++i) {
428         if (firstcond ^ (mask & 1))
429           ITBlock.push_back(firstcond ^ 1);
430         else
431           ITBlock.push_back(firstcond);
432         mask >>= 1;
433       }
434       ITBlock.push_back(firstcond);
435     }
436 
437     return true;
438   }
439 
440   // We want to read exactly 4 bytes of data.
441   if (Region.readBytes(Address, 4, (uint8_t*)bytes, NULL) == -1)
442     return false;
443 
444   uint32_t insn32 = (bytes[3] <<  8) |
445                     (bytes[2] <<  0) |
446                     (bytes[1] << 24) |
447                     (bytes[0] << 16);
448   MI.clear();
449   result = decodeThumbInstruction32(MI, insn32, Address, this);
450   if (result) {
451     Size = 4;
452     bool InITBlock = ITBlock.size();
453     AddThumbPredicate(MI);
454     AddThumb1SBit(MI, InITBlock);
455     return true;
456   }
457 
458   MI.clear();
459   result = decodeThumb2Instruction32(MI, insn32, Address, this);
460   if (result) {
461     Size = 4;
462     AddThumbPredicate(MI);
463     return true;
464   }
465 
466   MI.clear();
467   result = decodeCommonInstruction32(MI, insn32, Address, this);
468   if (result) {
469     Size = 4;
470     AddThumbPredicate(MI);
471     return true;
472   }
473 
474   MI.clear();
475   result = decodeVFPInstruction32(MI, insn32, Address, this);
476   if (result) {
477     Size = 4;
478     UpdateThumbVFPPredicate(MI);
479     return true;
480   }
481 
482   MI.clear();
483   if (fieldFromInstruction32(insn32, 24, 4) == 0xF) {
484     uint32_t NEONDataInsn = insn32;
485     NEONDataInsn &= 0xF0FFFFFF; // Clear bits 27-24
486     NEONDataInsn |= (NEONDataInsn & 0x10000000) >> 4; // Move bit 28 to bit 24
487     NEONDataInsn |= 0x12000000; // Set bits 28 and 25
488     result = decodeNEONDataInstruction32(MI, NEONDataInsn, Address, this);
489     if (result) {
490       Size = 4;
491       AddThumbPredicate(MI);
492       return true;
493     }
494   }
495 
496   MI.clear();
497   result = decodeNEONLoadStoreInstruction32(MI, insn32, Address, this);
498   if (result) {
499     Size = 4;
500     AddThumbPredicate(MI);
501     return true;
502   }
503 
504   MI.clear();
505   result = decodeNEONDupInstruction32(MI, insn32, Address, this);
506   if (result) {
507     Size = 4;
508     AddThumbPredicate(MI);
509     return true;
510   }
511 
512   return false;
513 }
514 
515 
516 extern "C" void LLVMInitializeARMDisassembler() {
517   TargetRegistry::RegisterMCDisassembler(TheARMTarget,
518                                          createARMDisassembler);
519   TargetRegistry::RegisterMCDisassembler(TheThumbTarget,
520                                          createThumbDisassembler);
521 }
522 
523 static const unsigned GPRDecoderTable[] = {
524   ARM::R0, ARM::R1, ARM::R2, ARM::R3,
525   ARM::R4, ARM::R5, ARM::R6, ARM::R7,
526   ARM::R8, ARM::R9, ARM::R10, ARM::R11,
527   ARM::R12, ARM::SP, ARM::LR, ARM::PC
528 };
529 
530 static bool DecodeGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
531                                    uint64_t Address, const void *Decoder) {
532   if (RegNo > 15)
533     return false;
534 
535   unsigned Register = GPRDecoderTable[RegNo];
536   Inst.addOperand(MCOperand::CreateReg(Register));
537   return true;
538 }
539 
540 static bool DecodeGPRnopcRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
541                                        uint64_t Address, const void *Decoder) {
542   if (RegNo == 15) return false;
543   return DecodeGPRRegisterClass(Inst, RegNo, Address, Decoder);
544 }
545 
546 static bool DecodetGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
547                                    uint64_t Address, const void *Decoder) {
548   if (RegNo > 7)
549     return false;
550   return DecodeGPRRegisterClass(Inst, RegNo, Address, Decoder);
551 }
552 
553 static bool DecodetcGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
554                                    uint64_t Address, const void *Decoder) {
555   unsigned Register = 0;
556   switch (RegNo) {
557     case 0:
558       Register = ARM::R0;
559       break;
560     case 1:
561       Register = ARM::R1;
562       break;
563     case 2:
564       Register = ARM::R2;
565       break;
566     case 3:
567       Register = ARM::R3;
568       break;
569     case 9:
570       Register = ARM::R9;
571       break;
572     case 12:
573       Register = ARM::R12;
574       break;
575     default:
576       return false;
577     }
578 
579   Inst.addOperand(MCOperand::CreateReg(Register));
580   return true;
581 }
582 
583 static bool DecoderGPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
584                                    uint64_t Address, const void *Decoder) {
585   if (RegNo == 13 || RegNo == 15) return false;
586   return DecodeGPRRegisterClass(Inst, RegNo, Address, Decoder);
587 }
588 
589 static const unsigned SPRDecoderTable[] = {
590      ARM::S0,  ARM::S1,  ARM::S2,  ARM::S3,
591      ARM::S4,  ARM::S5,  ARM::S6,  ARM::S7,
592      ARM::S8,  ARM::S9, ARM::S10, ARM::S11,
593     ARM::S12, ARM::S13, ARM::S14, ARM::S15,
594     ARM::S16, ARM::S17, ARM::S18, ARM::S19,
595     ARM::S20, ARM::S21, ARM::S22, ARM::S23,
596     ARM::S24, ARM::S25, ARM::S26, ARM::S27,
597     ARM::S28, ARM::S29, ARM::S30, ARM::S31
598 };
599 
600 static bool DecodeSPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
601                                    uint64_t Address, const void *Decoder) {
602   if (RegNo > 31)
603     return false;
604 
605   unsigned Register = SPRDecoderTable[RegNo];
606   Inst.addOperand(MCOperand::CreateReg(Register));
607   return true;
608 }
609 
610 static const unsigned DPRDecoderTable[] = {
611      ARM::D0,  ARM::D1,  ARM::D2,  ARM::D3,
612      ARM::D4,  ARM::D5,  ARM::D6,  ARM::D7,
613      ARM::D8,  ARM::D9, ARM::D10, ARM::D11,
614     ARM::D12, ARM::D13, ARM::D14, ARM::D15,
615     ARM::D16, ARM::D17, ARM::D18, ARM::D19,
616     ARM::D20, ARM::D21, ARM::D22, ARM::D23,
617     ARM::D24, ARM::D25, ARM::D26, ARM::D27,
618     ARM::D28, ARM::D29, ARM::D30, ARM::D31
619 };
620 
621 static bool DecodeDPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
622                                    uint64_t Address, const void *Decoder) {
623   if (RegNo > 31)
624     return false;
625 
626   unsigned Register = DPRDecoderTable[RegNo];
627   Inst.addOperand(MCOperand::CreateReg(Register));
628   return true;
629 }
630 
631 static bool DecodeDPR_8RegisterClass(llvm::MCInst &Inst, unsigned RegNo,
632                                    uint64_t Address, const void *Decoder) {
633   if (RegNo > 7)
634     return false;
635   return DecodeDPRRegisterClass(Inst, RegNo, Address, Decoder);
636 }
637 
638 static bool DecodeDPR_VFP2RegisterClass(llvm::MCInst &Inst, unsigned RegNo,
639                                    uint64_t Address, const void *Decoder) {
640   if (RegNo > 15)
641     return false;
642   return DecodeDPRRegisterClass(Inst, RegNo, Address, Decoder);
643 }
644 
645 static const unsigned QPRDecoderTable[] = {
646      ARM::Q0,  ARM::Q1,  ARM::Q2,  ARM::Q3,
647      ARM::Q4,  ARM::Q5,  ARM::Q6,  ARM::Q7,
648      ARM::Q8,  ARM::Q9, ARM::Q10, ARM::Q11,
649     ARM::Q12, ARM::Q13, ARM::Q14, ARM::Q15
650 };
651 
652 
653 static bool DecodeQPRRegisterClass(llvm::MCInst &Inst, unsigned RegNo,
654                                    uint64_t Address, const void *Decoder) {
655   if (RegNo > 31)
656     return false;
657   RegNo >>= 1;
658 
659   unsigned Register = QPRDecoderTable[RegNo];
660   Inst.addOperand(MCOperand::CreateReg(Register));
661   return true;
662 }
663 
664 static bool DecodePredicateOperand(llvm::MCInst &Inst, unsigned Val,
665                                uint64_t Address, const void *Decoder) {
666   if (Val == 0xF) return false;
667   // AL predicate is not allowed on Thumb1 branches.
668   if (Inst.getOpcode() == ARM::tBcc && Val == 0xE)
669     return false;
670   Inst.addOperand(MCOperand::CreateImm(Val));
671   if (Val == ARMCC::AL) {
672     Inst.addOperand(MCOperand::CreateReg(0));
673   } else
674     Inst.addOperand(MCOperand::CreateReg(ARM::CPSR));
675   return true;
676 }
677 
678 static bool DecodeCCOutOperand(llvm::MCInst &Inst, unsigned Val,
679                                uint64_t Address, const void *Decoder) {
680   if (Val)
681     Inst.addOperand(MCOperand::CreateReg(ARM::CPSR));
682   else
683     Inst.addOperand(MCOperand::CreateReg(0));
684   return true;
685 }
686 
687 static bool DecodeSOImmOperand(llvm::MCInst &Inst, unsigned Val,
688                                uint64_t Address, const void *Decoder) {
689   uint32_t imm = Val & 0xFF;
690   uint32_t rot = (Val & 0xF00) >> 7;
691   uint32_t rot_imm = (imm >> rot) | (imm << (32-rot));
692   Inst.addOperand(MCOperand::CreateImm(rot_imm));
693   return true;
694 }
695 
696 static bool DecodeBLTargetOperand(llvm::MCInst &Inst, unsigned Val,
697                                uint64_t Address, const void *Decoder) {
698   Val <<= 2;
699   Inst.addOperand(MCOperand::CreateImm(SignExtend32<26>(Val)));
700   return true;
701 }
702 
703 static bool DecodeSORegImmOperand(llvm::MCInst &Inst, unsigned Val,
704                                uint64_t Address, const void *Decoder) {
705 
706   unsigned Rm = fieldFromInstruction32(Val, 0, 4);
707   unsigned type = fieldFromInstruction32(Val, 5, 2);
708   unsigned imm = fieldFromInstruction32(Val, 7, 5);
709 
710   // Register-immediate
711   if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder)) return false;
712 
713   ARM_AM::ShiftOpc Shift = ARM_AM::lsl;
714   switch (type) {
715     case 0:
716       Shift = ARM_AM::lsl;
717       break;
718     case 1:
719       Shift = ARM_AM::lsr;
720       break;
721     case 2:
722       Shift = ARM_AM::asr;
723       break;
724     case 3:
725       Shift = ARM_AM::ror;
726       break;
727   }
728 
729   if (Shift == ARM_AM::ror && imm == 0)
730     Shift = ARM_AM::rrx;
731 
732   unsigned Op = Shift | (imm << 3);
733   Inst.addOperand(MCOperand::CreateImm(Op));
734 
735   return true;
736 }
737 
738 static bool DecodeSORegRegOperand(llvm::MCInst &Inst, unsigned Val,
739                                uint64_t Address, const void *Decoder) {
740 
741   unsigned Rm = fieldFromInstruction32(Val, 0, 4);
742   unsigned type = fieldFromInstruction32(Val, 5, 2);
743   unsigned Rs = fieldFromInstruction32(Val, 8, 4);
744 
745   // Register-register
746   if (!DecodeGPRnopcRegisterClass(Inst, Rm, Address, Decoder)) return false;
747   if (!DecodeGPRnopcRegisterClass(Inst, Rs, Address, Decoder)) return false;
748 
749   ARM_AM::ShiftOpc Shift = ARM_AM::lsl;
750   switch (type) {
751     case 0:
752       Shift = ARM_AM::lsl;
753       break;
754     case 1:
755       Shift = ARM_AM::lsr;
756       break;
757     case 2:
758       Shift = ARM_AM::asr;
759       break;
760     case 3:
761       Shift = ARM_AM::ror;
762       break;
763   }
764 
765   Inst.addOperand(MCOperand::CreateImm(Shift));
766 
767   return true;
768 }
769 
770 static bool DecodeRegListOperand(llvm::MCInst &Inst, unsigned Val,
771                                  uint64_t Address, const void *Decoder) {
772   // Empty register lists are not allowed.
773   if (CountPopulation_32(Val) == 0) return false;
774   for (unsigned i = 0; i < 16; ++i) {
775     if (Val & (1 << i)) {
776       if (!DecodeGPRRegisterClass(Inst, i, Address, Decoder)) return false;
777     }
778   }
779 
780   return true;
781 }
782 
783 static bool DecodeSPRRegListOperand(llvm::MCInst &Inst, unsigned Val,
784                                  uint64_t Address, const void *Decoder) {
785   unsigned Vd = fieldFromInstruction32(Val, 8, 4);
786   unsigned regs = Val & 0xFF;
787 
788   if (!DecodeSPRRegisterClass(Inst, Vd, Address, Decoder)) return false;
789   for (unsigned i = 0; i < (regs - 1); ++i) {
790     if (!DecodeSPRRegisterClass(Inst, ++Vd, Address, Decoder)) return false;
791   }
792 
793   return true;
794 }
795 
796 static bool DecodeDPRRegListOperand(llvm::MCInst &Inst, unsigned Val,
797                                  uint64_t Address, const void *Decoder) {
798   unsigned Vd = fieldFromInstruction32(Val, 8, 4);
799   unsigned regs = (Val & 0xFF) / 2;
800 
801   if (!DecodeDPRRegisterClass(Inst, Vd, Address, Decoder)) return false;
802   for (unsigned i = 0; i < (regs - 1); ++i) {
803     if (!DecodeDPRRegisterClass(Inst, ++Vd, Address, Decoder)) return false;
804   }
805 
806   return true;
807 }
808 
809 static bool DecodeBitfieldMaskOperand(llvm::MCInst &Inst, unsigned Val,
810                                       uint64_t Address, const void *Decoder) {
811   // This operand encodes a mask of contiguous zeros between a specified MSB
812   // and LSB.  To decode it, we create the mask of all bits MSB-and-lower,
813   // the mask of all bits LSB-and-lower, and then xor them to create
814   // the mask of that's all ones on [msb, lsb].  Finally we not it to
815   // create the final mask.
816   unsigned msb = fieldFromInstruction32(Val, 5, 5);
817   unsigned lsb = fieldFromInstruction32(Val, 0, 5);
818   uint32_t msb_mask = (1 << (msb+1)) - 1;
819   uint32_t lsb_mask = (1 << lsb) - 1;
820   Inst.addOperand(MCOperand::CreateImm(~(msb_mask ^ lsb_mask)));
821   return true;
822 }
823 
824 static bool DecodeCopMemInstruction(llvm::MCInst &Inst, unsigned Insn,
825                                   uint64_t Address, const void *Decoder) {
826   unsigned pred = fieldFromInstruction32(Insn, 28, 4);
827   unsigned CRd = fieldFromInstruction32(Insn, 12, 4);
828   unsigned coproc = fieldFromInstruction32(Insn, 8, 4);
829   unsigned imm = fieldFromInstruction32(Insn, 0, 8);
830   unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
831   unsigned U = fieldFromInstruction32(Insn, 23, 1);
832 
833   switch (Inst.getOpcode()) {
834     case ARM::LDC_OFFSET:
835     case ARM::LDC_PRE:
836     case ARM::LDC_POST:
837     case ARM::LDC_OPTION:
838     case ARM::LDCL_OFFSET:
839     case ARM::LDCL_PRE:
840     case ARM::LDCL_POST:
841     case ARM::LDCL_OPTION:
842     case ARM::STC_OFFSET:
843     case ARM::STC_PRE:
844     case ARM::STC_POST:
845     case ARM::STC_OPTION:
846     case ARM::STCL_OFFSET:
847     case ARM::STCL_PRE:
848     case ARM::STCL_POST:
849     case ARM::STCL_OPTION:
850       if (coproc == 0xA || coproc == 0xB)
851         return false;
852       break;
853     default:
854       break;
855   }
856 
857   Inst.addOperand(MCOperand::CreateImm(coproc));
858   Inst.addOperand(MCOperand::CreateImm(CRd));
859   if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
860   switch (Inst.getOpcode()) {
861     case ARM::LDC_OPTION:
862     case ARM::LDCL_OPTION:
863     case ARM::LDC2_OPTION:
864     case ARM::LDC2L_OPTION:
865     case ARM::STC_OPTION:
866     case ARM::STCL_OPTION:
867     case ARM::STC2_OPTION:
868     case ARM::STC2L_OPTION:
869     case ARM::LDCL_POST:
870     case ARM::STCL_POST:
871       break;
872     default:
873       Inst.addOperand(MCOperand::CreateReg(0));
874       break;
875   }
876 
877   unsigned P = fieldFromInstruction32(Insn, 24, 1);
878   unsigned W = fieldFromInstruction32(Insn, 21, 1);
879 
880   bool writeback = (P == 0) || (W == 1);
881   unsigned idx_mode = 0;
882   if (P && writeback)
883     idx_mode = ARMII::IndexModePre;
884   else if (!P && writeback)
885     idx_mode = ARMII::IndexModePost;
886 
887   switch (Inst.getOpcode()) {
888     case ARM::LDCL_POST:
889     case ARM::STCL_POST:
890       imm |= U << 8;
891     case ARM::LDC_OPTION:
892     case ARM::LDCL_OPTION:
893     case ARM::LDC2_OPTION:
894     case ARM::LDC2L_OPTION:
895     case ARM::STC_OPTION:
896     case ARM::STCL_OPTION:
897     case ARM::STC2_OPTION:
898     case ARM::STC2L_OPTION:
899       Inst.addOperand(MCOperand::CreateImm(imm));
900       break;
901     default:
902       if (U)
903         Inst.addOperand(MCOperand::CreateImm(
904             ARM_AM::getAM2Opc(ARM_AM::add, imm, ARM_AM::lsl, idx_mode)));
905       else
906         Inst.addOperand(MCOperand::CreateImm(
907             ARM_AM::getAM2Opc(ARM_AM::sub, imm, ARM_AM::lsl, idx_mode)));
908       break;
909   }
910 
911   switch (Inst.getOpcode()) {
912     case ARM::LDC_OFFSET:
913     case ARM::LDC_PRE:
914     case ARM::LDC_POST:
915     case ARM::LDC_OPTION:
916     case ARM::LDCL_OFFSET:
917     case ARM::LDCL_PRE:
918     case ARM::LDCL_POST:
919     case ARM::LDCL_OPTION:
920     case ARM::STC_OFFSET:
921     case ARM::STC_PRE:
922     case ARM::STC_POST:
923     case ARM::STC_OPTION:
924     case ARM::STCL_OFFSET:
925     case ARM::STCL_PRE:
926     case ARM::STCL_POST:
927     case ARM::STCL_OPTION:
928       if (!DecodePredicateOperand(Inst, pred, Address, Decoder)) return false;
929       break;
930     default:
931       break;
932   }
933 
934   return true;
935 }
936 
937 static bool DecodeAddrMode2IdxInstruction(llvm::MCInst &Inst, unsigned Insn,
938                                   uint64_t Address, const void *Decoder) {
939   unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
940   unsigned Rt = fieldFromInstruction32(Insn, 12, 4);
941   unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
942   unsigned imm = fieldFromInstruction32(Insn, 0, 12);
943   unsigned pred = fieldFromInstruction32(Insn, 28, 4);
944   unsigned reg = fieldFromInstruction32(Insn, 25, 1);
945   unsigned P = fieldFromInstruction32(Insn, 24, 1);
946   unsigned W = fieldFromInstruction32(Insn, 21, 1);
947 
948   // On stores, the writeback operand precedes Rt.
949   switch (Inst.getOpcode()) {
950     case ARM::STR_POST_IMM:
951     case ARM::STR_POST_REG:
952     case ARM::STRB_POST_IMM:
953     case ARM::STRB_POST_REG:
954     case ARM::STRT_POST_REG:
955     case ARM::STRT_POST_IMM:
956     case ARM::STRBT_POST_REG:
957     case ARM::STRBT_POST_IMM:
958       if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
959       break;
960     default:
961       break;
962   }
963 
964   if (!DecodeGPRRegisterClass(Inst, Rt, Address, Decoder)) return false;
965 
966   // On loads, the writeback operand comes after Rt.
967   switch (Inst.getOpcode()) {
968     case ARM::LDR_POST_IMM:
969     case ARM::LDR_POST_REG:
970     case ARM::LDRB_POST_IMM:
971     case ARM::LDRB_POST_REG:
972     case ARM::LDR_PRE:
973     case ARM::LDRBT_POST_REG:
974     case ARM::LDRBT_POST_IMM:
975     case ARM::LDRT_POST_REG:
976     case ARM::LDRT_POST_IMM:
977       if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder))
978         return false;
979       break;
980     default:
981       break;
982   }
983 
984   if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
985 
986   ARM_AM::AddrOpc Op = ARM_AM::add;
987   if (!fieldFromInstruction32(Insn, 23, 1))
988     Op = ARM_AM::sub;
989 
990   bool writeback = (P == 0) || (W == 1);
991   unsigned idx_mode = 0;
992   if (P && writeback)
993     idx_mode = ARMII::IndexModePre;
994   else if (!P && writeback)
995     idx_mode = ARMII::IndexModePost;
996 
997   if (writeback && (Rn == 15 || Rn == Rt)) return false; // UNPREDICTABLE
998 
999   if (reg) {
1000     if (!DecodeGPRnopcRegisterClass(Inst, Rm, Address, Decoder)) return false;
1001     ARM_AM::ShiftOpc Opc = ARM_AM::lsl;
1002     switch( fieldFromInstruction32(Insn, 5, 2)) {
1003       case 0:
1004         Opc = ARM_AM::lsl;
1005         break;
1006       case 1:
1007         Opc = ARM_AM::lsr;
1008         break;
1009       case 2:
1010         Opc = ARM_AM::asr;
1011         break;
1012       case 3:
1013         Opc = ARM_AM::ror;
1014         break;
1015       default:
1016         return false;
1017     }
1018     unsigned amt = fieldFromInstruction32(Insn, 7, 5);
1019     unsigned imm = ARM_AM::getAM2Opc(Op, amt, Opc, idx_mode);
1020 
1021     Inst.addOperand(MCOperand::CreateImm(imm));
1022   } else {
1023     Inst.addOperand(MCOperand::CreateReg(0));
1024     unsigned tmp = ARM_AM::getAM2Opc(Op, imm, ARM_AM::lsl, idx_mode);
1025     Inst.addOperand(MCOperand::CreateImm(tmp));
1026   }
1027 
1028   if (!DecodePredicateOperand(Inst, pred, Address, Decoder)) return false;
1029 
1030   return true;
1031 }
1032 
1033 static bool DecodeSORegMemOperand(llvm::MCInst &Inst, unsigned Val,
1034                                   uint64_t Address, const void *Decoder) {
1035   unsigned Rn = fieldFromInstruction32(Val, 13, 4);
1036   unsigned Rm = fieldFromInstruction32(Val,  0, 4);
1037   unsigned type = fieldFromInstruction32(Val, 5, 2);
1038   unsigned imm = fieldFromInstruction32(Val, 7, 5);
1039   unsigned U = fieldFromInstruction32(Val, 12, 1);
1040 
1041   ARM_AM::ShiftOpc ShOp = ARM_AM::lsl;
1042   switch (type) {
1043     case 0:
1044       ShOp = ARM_AM::lsl;
1045       break;
1046     case 1:
1047       ShOp = ARM_AM::lsr;
1048       break;
1049     case 2:
1050       ShOp = ARM_AM::asr;
1051       break;
1052     case 3:
1053       ShOp = ARM_AM::ror;
1054       break;
1055   }
1056 
1057   if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
1058   if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder)) return false;
1059   unsigned shift;
1060   if (U)
1061     shift = ARM_AM::getAM2Opc(ARM_AM::add, imm, ShOp);
1062   else
1063     shift = ARM_AM::getAM2Opc(ARM_AM::sub, imm, ShOp);
1064   Inst.addOperand(MCOperand::CreateImm(shift));
1065 
1066   return true;
1067 }
1068 
1069 static bool DecodeAddrMode3Instruction(llvm::MCInst &Inst, unsigned Insn,
1070                                   uint64_t Address, const void *Decoder) {
1071   unsigned Rt = fieldFromInstruction32(Insn, 12, 4);
1072   unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
1073   unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
1074   unsigned type = fieldFromInstruction32(Insn, 22, 1);
1075   unsigned imm = fieldFromInstruction32(Insn, 8, 4);
1076   unsigned U = ((~fieldFromInstruction32(Insn, 23, 1)) & 1) << 8;
1077   unsigned pred = fieldFromInstruction32(Insn, 28, 4);
1078   unsigned W = fieldFromInstruction32(Insn, 21, 1);
1079   unsigned P = fieldFromInstruction32(Insn, 24, 1);
1080 
1081   bool writeback = (W == 1) | (P == 0);
1082   if (writeback) { // Writeback
1083     if (P)
1084       U |= ARMII::IndexModePre << 9;
1085     else
1086       U |= ARMII::IndexModePost << 9;
1087 
1088     // On stores, the writeback operand precedes Rt.
1089     switch (Inst.getOpcode()) {
1090     case ARM::STRD:
1091     case ARM::STRD_PRE:
1092     case ARM::STRD_POST:
1093       if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder))
1094         return false;
1095       break;
1096     default:
1097       break;
1098     }
1099   }
1100 
1101   if (!DecodeGPRRegisterClass(Inst, Rt, Address, Decoder))
1102     return false;
1103   switch (Inst.getOpcode()) {
1104     case ARM::STRD:
1105     case ARM::STRD_PRE:
1106     case ARM::STRD_POST:
1107     case ARM::LDRD:
1108     case ARM::LDRD_PRE:
1109     case ARM::LDRD_POST:
1110       if (!DecodeGPRRegisterClass(Inst, Rt+1, Address, Decoder))
1111         return false;
1112       break;
1113     default:
1114       break;
1115   }
1116 
1117   if (writeback) {
1118     // On loads, the writeback operand comes after Rt.
1119     switch (Inst.getOpcode()) {
1120     case ARM::LDRD:
1121     case ARM::LDRD_PRE:
1122     case ARM::LDRD_POST:
1123     case ARM::LDRHTr:
1124     case ARM::LDRSBTr:
1125       if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder))
1126         return false;
1127       break;
1128     default:
1129       break;
1130     }
1131   }
1132 
1133   if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder))
1134     return false;
1135 
1136   if (type) {
1137     Inst.addOperand(MCOperand::CreateReg(0));
1138     Inst.addOperand(MCOperand::CreateImm(U | (imm << 4) | Rm));
1139   } else {
1140     if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder))
1141       return false;
1142     Inst.addOperand(MCOperand::CreateImm(U));
1143   }
1144 
1145   if (!DecodePredicateOperand(Inst, pred, Address, Decoder)) return false;
1146 
1147   return true;
1148 }
1149 
1150 static bool DecodeRFEInstruction(llvm::MCInst &Inst, unsigned Insn,
1151                                  uint64_t Address, const void *Decoder) {
1152   unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
1153   unsigned mode = fieldFromInstruction32(Insn, 23, 2);
1154 
1155   switch (mode) {
1156     case 0:
1157       mode = ARM_AM::da;
1158       break;
1159     case 1:
1160       mode = ARM_AM::ia;
1161       break;
1162     case 2:
1163       mode = ARM_AM::db;
1164       break;
1165     case 3:
1166       mode = ARM_AM::ib;
1167       break;
1168   }
1169 
1170   Inst.addOperand(MCOperand::CreateImm(mode));
1171   if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
1172 
1173   return true;
1174 }
1175 
1176 static bool DecodeMemMultipleWritebackInstruction(llvm::MCInst &Inst,
1177                                   unsigned Insn,
1178                                   uint64_t Address, const void *Decoder) {
1179   unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
1180   unsigned pred = fieldFromInstruction32(Insn, 28, 4);
1181   unsigned reglist = fieldFromInstruction32(Insn, 0, 16);
1182 
1183   if (pred == 0xF) {
1184     switch (Inst.getOpcode()) {
1185       case ARM::STMDA:
1186         Inst.setOpcode(ARM::RFEDA);
1187         break;
1188       case ARM::STMDA_UPD:
1189         Inst.setOpcode(ARM::RFEDA_UPD);
1190         break;
1191       case ARM::STMDB:
1192         Inst.setOpcode(ARM::RFEDB);
1193         break;
1194       case ARM::STMDB_UPD:
1195         Inst.setOpcode(ARM::RFEDB_UPD);
1196         break;
1197       case ARM::STMIA:
1198         Inst.setOpcode(ARM::RFEIA);
1199         break;
1200       case ARM::STMIA_UPD:
1201         Inst.setOpcode(ARM::RFEIA_UPD);
1202         break;
1203       case ARM::STMIB:
1204         Inst.setOpcode(ARM::RFEIB);
1205         break;
1206       case ARM::STMIB_UPD:
1207         Inst.setOpcode(ARM::RFEIB_UPD);
1208         break;
1209     }
1210     return DecodeRFEInstruction(Inst, Insn, Address, Decoder);
1211   }
1212 
1213   if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)   ||
1214       !DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)   || // Tied
1215       !DecodePredicateOperand(Inst, pred, Address, Decoder) ||
1216       !DecodeRegListOperand(Inst, reglist, Address, Decoder))
1217     return false;
1218 
1219   return true;
1220 }
1221 
1222 static bool DecodeCPSInstruction(llvm::MCInst &Inst, unsigned Insn,
1223                                  uint64_t Address, const void *Decoder) {
1224   unsigned imod = fieldFromInstruction32(Insn, 18, 2);
1225   unsigned M = fieldFromInstruction32(Insn, 17, 1);
1226   unsigned iflags = fieldFromInstruction32(Insn, 6, 3);
1227   unsigned mode = fieldFromInstruction32(Insn, 0, 5);
1228 
1229   // imod == '01' --> UNPREDICTABLE
1230   if (imod == 1) return false;
1231 
1232   if (M && mode && imod && iflags) {
1233     Inst.setOpcode(ARM::CPS3p);
1234     Inst.addOperand(MCOperand::CreateImm(imod));
1235     Inst.addOperand(MCOperand::CreateImm(iflags));
1236     Inst.addOperand(MCOperand::CreateImm(mode));
1237     return true;
1238   } else if (!mode && !M) {
1239     Inst.setOpcode(ARM::CPS2p);
1240     Inst.addOperand(MCOperand::CreateImm(imod));
1241     Inst.addOperand(MCOperand::CreateImm(iflags));
1242     return true;
1243   } else if (!imod && !iflags && M) {
1244     Inst.setOpcode(ARM::CPS1p);
1245     Inst.addOperand(MCOperand::CreateImm(mode));
1246     return true;
1247   }
1248 
1249   return false;
1250 }
1251 
1252 static bool DecodeSMLAInstruction(llvm::MCInst &Inst, unsigned Insn,
1253                                  uint64_t Address, const void *Decoder) {
1254   unsigned Rd = fieldFromInstruction32(Insn, 16, 4);
1255   unsigned Rn = fieldFromInstruction32(Insn, 0, 4);
1256   unsigned Rm = fieldFromInstruction32(Insn, 8, 4);
1257   unsigned Ra = fieldFromInstruction32(Insn, 12, 4);
1258   unsigned pred = fieldFromInstruction32(Insn, 28, 4);
1259 
1260   if (pred == 0xF)
1261     return DecodeCPSInstruction(Inst, Insn, Address, Decoder);
1262 
1263   if (!DecodeGPRnopcRegisterClass(Inst, Rd, Address, Decoder) ||
1264       !DecodeGPRnopcRegisterClass(Inst, Rn, Address, Decoder) ||
1265       !DecodeGPRnopcRegisterClass(Inst, Rm, Address, Decoder) ||
1266       !DecodeGPRnopcRegisterClass(Inst, Ra, Address, Decoder))
1267     return false;
1268 
1269   if (!DecodePredicateOperand(Inst, pred, Address, Decoder)) return false;
1270 
1271   return true;
1272 }
1273 
1274 static bool DecodeAddrModeImm12Operand(llvm::MCInst &Inst, unsigned Val,
1275                            uint64_t Address, const void *Decoder) {
1276   unsigned add = fieldFromInstruction32(Val, 12, 1);
1277   unsigned imm = fieldFromInstruction32(Val, 0, 12);
1278   unsigned Rn = fieldFromInstruction32(Val, 13, 4);
1279 
1280   if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder))
1281     return false;
1282 
1283   if (!add) imm *= -1;
1284   if (imm == 0 && !add) imm = INT32_MIN;
1285   Inst.addOperand(MCOperand::CreateImm(imm));
1286 
1287   return true;
1288 }
1289 
1290 static bool DecodeAddrMode5Operand(llvm::MCInst &Inst, unsigned Val,
1291                                    uint64_t Address, const void *Decoder) {
1292   unsigned Rn = fieldFromInstruction32(Val, 9, 4);
1293   unsigned U = fieldFromInstruction32(Val, 8, 1);
1294   unsigned imm = fieldFromInstruction32(Val, 0, 8);
1295 
1296   if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder))
1297     return false;
1298 
1299   if (U)
1300     Inst.addOperand(MCOperand::CreateImm(ARM_AM::getAM5Opc(ARM_AM::add, imm)));
1301   else
1302     Inst.addOperand(MCOperand::CreateImm(ARM_AM::getAM5Opc(ARM_AM::sub, imm)));
1303 
1304   return true;
1305 }
1306 
1307 static bool DecodeAddrMode7Operand(llvm::MCInst &Inst, unsigned Val,
1308                                    uint64_t Address, const void *Decoder) {
1309   return DecodeGPRRegisterClass(Inst, Val, Address, Decoder);
1310 }
1311 
1312 static bool DecodeBranchImmInstruction(llvm::MCInst &Inst, unsigned Insn,
1313                                    uint64_t Address, const void *Decoder) {
1314   unsigned pred = fieldFromInstruction32(Insn, 28, 4);
1315   unsigned imm = fieldFromInstruction32(Insn, 0, 24) << 2;
1316 
1317   if (pred == 0xF) {
1318     Inst.setOpcode(ARM::BLXi);
1319     imm |= fieldFromInstruction32(Insn, 24, 1) << 1;
1320     Inst.addOperand(MCOperand::CreateImm(SignExtend32<26>(imm)));
1321     return true;
1322   }
1323 
1324   Inst.addOperand(MCOperand::CreateImm(SignExtend32<26>(imm)));
1325   if (!DecodePredicateOperand(Inst, pred, Address, Decoder)) return false;
1326 
1327   return true;
1328 }
1329 
1330 
1331 static bool DecodeVCVTImmOperand(llvm::MCInst &Inst, unsigned Val,
1332                                  uint64_t Address, const void *Decoder) {
1333   Inst.addOperand(MCOperand::CreateImm(64 - Val));
1334   return true;
1335 }
1336 
1337 static bool DecodeAddrMode6Operand(llvm::MCInst &Inst, unsigned Val,
1338                                    uint64_t Address, const void *Decoder) {
1339   unsigned Rm = fieldFromInstruction32(Val, 0, 4);
1340   unsigned align = fieldFromInstruction32(Val, 4, 2);
1341 
1342   if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder))
1343     return false;
1344   if (!align)
1345     Inst.addOperand(MCOperand::CreateImm(0));
1346   else
1347     Inst.addOperand(MCOperand::CreateImm(4 << align));
1348 
1349   return true;
1350 }
1351 
1352 static bool DecodeVLDInstruction(llvm::MCInst &Inst, unsigned Insn,
1353                                    uint64_t Address, const void *Decoder) {
1354   unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
1355   Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
1356   unsigned wb = fieldFromInstruction32(Insn, 16, 4);
1357   unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
1358   Rn |= fieldFromInstruction32(Insn, 4, 2) << 4;
1359   unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
1360 
1361   // First output register
1362   if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
1363 
1364   // Second output register
1365   switch (Inst.getOpcode()) {
1366     case ARM::VLD1q8:
1367     case ARM::VLD1q16:
1368     case ARM::VLD1q32:
1369     case ARM::VLD1q64:
1370     case ARM::VLD1q8_UPD:
1371     case ARM::VLD1q16_UPD:
1372     case ARM::VLD1q32_UPD:
1373     case ARM::VLD1q64_UPD:
1374     case ARM::VLD1d8T:
1375     case ARM::VLD1d16T:
1376     case ARM::VLD1d32T:
1377     case ARM::VLD1d64T:
1378     case ARM::VLD1d8T_UPD:
1379     case ARM::VLD1d16T_UPD:
1380     case ARM::VLD1d32T_UPD:
1381     case ARM::VLD1d64T_UPD:
1382     case ARM::VLD1d8Q:
1383     case ARM::VLD1d16Q:
1384     case ARM::VLD1d32Q:
1385     case ARM::VLD1d64Q:
1386     case ARM::VLD1d8Q_UPD:
1387     case ARM::VLD1d16Q_UPD:
1388     case ARM::VLD1d32Q_UPD:
1389     case ARM::VLD1d64Q_UPD:
1390     case ARM::VLD2d8:
1391     case ARM::VLD2d16:
1392     case ARM::VLD2d32:
1393     case ARM::VLD2d8_UPD:
1394     case ARM::VLD2d16_UPD:
1395     case ARM::VLD2d32_UPD:
1396     case ARM::VLD2q8:
1397     case ARM::VLD2q16:
1398     case ARM::VLD2q32:
1399     case ARM::VLD2q8_UPD:
1400     case ARM::VLD2q16_UPD:
1401     case ARM::VLD2q32_UPD:
1402     case ARM::VLD3d8:
1403     case ARM::VLD3d16:
1404     case ARM::VLD3d32:
1405     case ARM::VLD3d8_UPD:
1406     case ARM::VLD3d16_UPD:
1407     case ARM::VLD3d32_UPD:
1408     case ARM::VLD4d8:
1409     case ARM::VLD4d16:
1410     case ARM::VLD4d32:
1411     case ARM::VLD4d8_UPD:
1412     case ARM::VLD4d16_UPD:
1413     case ARM::VLD4d32_UPD:
1414       if (!DecodeDPRRegisterClass(Inst, (Rd+1)%32, Address, Decoder)) return false;
1415       break;
1416     case ARM::VLD2b8:
1417     case ARM::VLD2b16:
1418     case ARM::VLD2b32:
1419     case ARM::VLD2b8_UPD:
1420     case ARM::VLD2b16_UPD:
1421     case ARM::VLD2b32_UPD:
1422     case ARM::VLD3q8:
1423     case ARM::VLD3q16:
1424     case ARM::VLD3q32:
1425     case ARM::VLD3q8_UPD:
1426     case ARM::VLD3q16_UPD:
1427     case ARM::VLD3q32_UPD:
1428     case ARM::VLD4q8:
1429     case ARM::VLD4q16:
1430     case ARM::VLD4q32:
1431     case ARM::VLD4q8_UPD:
1432     case ARM::VLD4q16_UPD:
1433     case ARM::VLD4q32_UPD:
1434       if (!DecodeDPRRegisterClass(Inst, (Rd+2)%32, Address, Decoder)) return false;
1435     default:
1436       break;
1437   }
1438 
1439   // Third output register
1440   switch(Inst.getOpcode()) {
1441     case ARM::VLD1d8T:
1442     case ARM::VLD1d16T:
1443     case ARM::VLD1d32T:
1444     case ARM::VLD1d64T:
1445     case ARM::VLD1d8T_UPD:
1446     case ARM::VLD1d16T_UPD:
1447     case ARM::VLD1d32T_UPD:
1448     case ARM::VLD1d64T_UPD:
1449     case ARM::VLD1d8Q:
1450     case ARM::VLD1d16Q:
1451     case ARM::VLD1d32Q:
1452     case ARM::VLD1d64Q:
1453     case ARM::VLD1d8Q_UPD:
1454     case ARM::VLD1d16Q_UPD:
1455     case ARM::VLD1d32Q_UPD:
1456     case ARM::VLD1d64Q_UPD:
1457     case ARM::VLD2q8:
1458     case ARM::VLD2q16:
1459     case ARM::VLD2q32:
1460     case ARM::VLD2q8_UPD:
1461     case ARM::VLD2q16_UPD:
1462     case ARM::VLD2q32_UPD:
1463     case ARM::VLD3d8:
1464     case ARM::VLD3d16:
1465     case ARM::VLD3d32:
1466     case ARM::VLD3d8_UPD:
1467     case ARM::VLD3d16_UPD:
1468     case ARM::VLD3d32_UPD:
1469     case ARM::VLD4d8:
1470     case ARM::VLD4d16:
1471     case ARM::VLD4d32:
1472     case ARM::VLD4d8_UPD:
1473     case ARM::VLD4d16_UPD:
1474     case ARM::VLD4d32_UPD:
1475       if (!DecodeDPRRegisterClass(Inst, (Rd+2)%32, Address, Decoder)) return false;
1476       break;
1477     case ARM::VLD3q8:
1478     case ARM::VLD3q16:
1479     case ARM::VLD3q32:
1480     case ARM::VLD3q8_UPD:
1481     case ARM::VLD3q16_UPD:
1482     case ARM::VLD3q32_UPD:
1483     case ARM::VLD4q8:
1484     case ARM::VLD4q16:
1485     case ARM::VLD4q32:
1486     case ARM::VLD4q8_UPD:
1487     case ARM::VLD4q16_UPD:
1488     case ARM::VLD4q32_UPD:
1489       if (!DecodeDPRRegisterClass(Inst, (Rd+4)%32, Address, Decoder)) return false;
1490       break;
1491     default:
1492       break;
1493   }
1494 
1495   // Fourth output register
1496   switch (Inst.getOpcode()) {
1497     case ARM::VLD1d8Q:
1498     case ARM::VLD1d16Q:
1499     case ARM::VLD1d32Q:
1500     case ARM::VLD1d64Q:
1501     case ARM::VLD1d8Q_UPD:
1502     case ARM::VLD1d16Q_UPD:
1503     case ARM::VLD1d32Q_UPD:
1504     case ARM::VLD1d64Q_UPD:
1505     case ARM::VLD2q8:
1506     case ARM::VLD2q16:
1507     case ARM::VLD2q32:
1508     case ARM::VLD2q8_UPD:
1509     case ARM::VLD2q16_UPD:
1510     case ARM::VLD2q32_UPD:
1511     case ARM::VLD4d8:
1512     case ARM::VLD4d16:
1513     case ARM::VLD4d32:
1514     case ARM::VLD4d8_UPD:
1515     case ARM::VLD4d16_UPD:
1516     case ARM::VLD4d32_UPD:
1517       if (!DecodeDPRRegisterClass(Inst, (Rd+3)%32, Address, Decoder)) return false;
1518       break;
1519     case ARM::VLD4q8:
1520     case ARM::VLD4q16:
1521     case ARM::VLD4q32:
1522     case ARM::VLD4q8_UPD:
1523     case ARM::VLD4q16_UPD:
1524     case ARM::VLD4q32_UPD:
1525       if (!DecodeDPRRegisterClass(Inst, (Rd+6)%32, Address, Decoder)) return false;
1526       break;
1527     default:
1528       break;
1529   }
1530 
1531   // Writeback operand
1532   switch (Inst.getOpcode()) {
1533     case ARM::VLD1d8_UPD:
1534     case ARM::VLD1d16_UPD:
1535     case ARM::VLD1d32_UPD:
1536     case ARM::VLD1d64_UPD:
1537     case ARM::VLD1q8_UPD:
1538     case ARM::VLD1q16_UPD:
1539     case ARM::VLD1q32_UPD:
1540     case ARM::VLD1q64_UPD:
1541     case ARM::VLD1d8T_UPD:
1542     case ARM::VLD1d16T_UPD:
1543     case ARM::VLD1d32T_UPD:
1544     case ARM::VLD1d64T_UPD:
1545     case ARM::VLD1d8Q_UPD:
1546     case ARM::VLD1d16Q_UPD:
1547     case ARM::VLD1d32Q_UPD:
1548     case ARM::VLD1d64Q_UPD:
1549     case ARM::VLD2d8_UPD:
1550     case ARM::VLD2d16_UPD:
1551     case ARM::VLD2d32_UPD:
1552     case ARM::VLD2q8_UPD:
1553     case ARM::VLD2q16_UPD:
1554     case ARM::VLD2q32_UPD:
1555     case ARM::VLD2b8_UPD:
1556     case ARM::VLD2b16_UPD:
1557     case ARM::VLD2b32_UPD:
1558     case ARM::VLD3d8_UPD:
1559     case ARM::VLD3d16_UPD:
1560     case ARM::VLD3d32_UPD:
1561     case ARM::VLD3q8_UPD:
1562     case ARM::VLD3q16_UPD:
1563     case ARM::VLD3q32_UPD:
1564     case ARM::VLD4d8_UPD:
1565     case ARM::VLD4d16_UPD:
1566     case ARM::VLD4d32_UPD:
1567     case ARM::VLD4q8_UPD:
1568     case ARM::VLD4q16_UPD:
1569     case ARM::VLD4q32_UPD:
1570       if (!DecodeGPRRegisterClass(Inst, wb, Address, Decoder)) return false;
1571       break;
1572     default:
1573       break;
1574   }
1575 
1576   // AddrMode6 Base (register+alignment)
1577   if (!DecodeAddrMode6Operand(Inst, Rn, Address, Decoder)) return false;
1578 
1579   // AddrMode6 Offset (register)
1580   if (Rm == 0xD)
1581     Inst.addOperand(MCOperand::CreateReg(0));
1582   else if (Rm != 0xF) {
1583     if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder))
1584       return false;
1585   }
1586 
1587   return true;
1588 }
1589 
1590 static bool DecodeVSTInstruction(llvm::MCInst &Inst, unsigned Insn,
1591                                  uint64_t Address, const void *Decoder) {
1592   unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
1593   Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
1594   unsigned wb = fieldFromInstruction32(Insn, 16, 4);
1595   unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
1596   Rn |= fieldFromInstruction32(Insn, 4, 2) << 4;
1597   unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
1598 
1599   // Writeback Operand
1600   switch (Inst.getOpcode()) {
1601     case ARM::VST1d8_UPD:
1602     case ARM::VST1d16_UPD:
1603     case ARM::VST1d32_UPD:
1604     case ARM::VST1d64_UPD:
1605     case ARM::VST1q8_UPD:
1606     case ARM::VST1q16_UPD:
1607     case ARM::VST1q32_UPD:
1608     case ARM::VST1q64_UPD:
1609     case ARM::VST1d8T_UPD:
1610     case ARM::VST1d16T_UPD:
1611     case ARM::VST1d32T_UPD:
1612     case ARM::VST1d64T_UPD:
1613     case ARM::VST1d8Q_UPD:
1614     case ARM::VST1d16Q_UPD:
1615     case ARM::VST1d32Q_UPD:
1616     case ARM::VST1d64Q_UPD:
1617     case ARM::VST2d8_UPD:
1618     case ARM::VST2d16_UPD:
1619     case ARM::VST2d32_UPD:
1620     case ARM::VST2q8_UPD:
1621     case ARM::VST2q16_UPD:
1622     case ARM::VST2q32_UPD:
1623     case ARM::VST2b8_UPD:
1624     case ARM::VST2b16_UPD:
1625     case ARM::VST2b32_UPD:
1626     case ARM::VST3d8_UPD:
1627     case ARM::VST3d16_UPD:
1628     case ARM::VST3d32_UPD:
1629     case ARM::VST3q8_UPD:
1630     case ARM::VST3q16_UPD:
1631     case ARM::VST3q32_UPD:
1632     case ARM::VST4d8_UPD:
1633     case ARM::VST4d16_UPD:
1634     case ARM::VST4d32_UPD:
1635     case ARM::VST4q8_UPD:
1636     case ARM::VST4q16_UPD:
1637     case ARM::VST4q32_UPD:
1638       if (!DecodeGPRRegisterClass(Inst, wb, Address, Decoder))
1639         return false;
1640       break;
1641     default:
1642       break;
1643   }
1644 
1645   // AddrMode6 Base (register+alignment)
1646   if (!DecodeAddrMode6Operand(Inst, Rn, Address, Decoder)) return false;
1647 
1648   // AddrMode6 Offset (register)
1649   if (Rm == 0xD)
1650     Inst.addOperand(MCOperand::CreateReg(0));
1651   else if (Rm != 0xF) {
1652     if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder)) return false;
1653   }
1654 
1655   // First input register
1656   if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
1657 
1658   // Second input register
1659   switch (Inst.getOpcode()) {
1660     case ARM::VST1q8:
1661     case ARM::VST1q16:
1662     case ARM::VST1q32:
1663     case ARM::VST1q64:
1664     case ARM::VST1q8_UPD:
1665     case ARM::VST1q16_UPD:
1666     case ARM::VST1q32_UPD:
1667     case ARM::VST1q64_UPD:
1668     case ARM::VST1d8T:
1669     case ARM::VST1d16T:
1670     case ARM::VST1d32T:
1671     case ARM::VST1d64T:
1672     case ARM::VST1d8T_UPD:
1673     case ARM::VST1d16T_UPD:
1674     case ARM::VST1d32T_UPD:
1675     case ARM::VST1d64T_UPD:
1676     case ARM::VST1d8Q:
1677     case ARM::VST1d16Q:
1678     case ARM::VST1d32Q:
1679     case ARM::VST1d64Q:
1680     case ARM::VST1d8Q_UPD:
1681     case ARM::VST1d16Q_UPD:
1682     case ARM::VST1d32Q_UPD:
1683     case ARM::VST1d64Q_UPD:
1684     case ARM::VST2d8:
1685     case ARM::VST2d16:
1686     case ARM::VST2d32:
1687     case ARM::VST2d8_UPD:
1688     case ARM::VST2d16_UPD:
1689     case ARM::VST2d32_UPD:
1690     case ARM::VST2q8:
1691     case ARM::VST2q16:
1692     case ARM::VST2q32:
1693     case ARM::VST2q8_UPD:
1694     case ARM::VST2q16_UPD:
1695     case ARM::VST2q32_UPD:
1696     case ARM::VST3d8:
1697     case ARM::VST3d16:
1698     case ARM::VST3d32:
1699     case ARM::VST3d8_UPD:
1700     case ARM::VST3d16_UPD:
1701     case ARM::VST3d32_UPD:
1702     case ARM::VST4d8:
1703     case ARM::VST4d16:
1704     case ARM::VST4d32:
1705     case ARM::VST4d8_UPD:
1706     case ARM::VST4d16_UPD:
1707     case ARM::VST4d32_UPD:
1708       if (!DecodeDPRRegisterClass(Inst, (Rd+1)%32, Address, Decoder)) return false;
1709       break;
1710     case ARM::VST2b8:
1711     case ARM::VST2b16:
1712     case ARM::VST2b32:
1713     case ARM::VST2b8_UPD:
1714     case ARM::VST2b16_UPD:
1715     case ARM::VST2b32_UPD:
1716     case ARM::VST3q8:
1717     case ARM::VST3q16:
1718     case ARM::VST3q32:
1719     case ARM::VST3q8_UPD:
1720     case ARM::VST3q16_UPD:
1721     case ARM::VST3q32_UPD:
1722     case ARM::VST4q8:
1723     case ARM::VST4q16:
1724     case ARM::VST4q32:
1725     case ARM::VST4q8_UPD:
1726     case ARM::VST4q16_UPD:
1727     case ARM::VST4q32_UPD:
1728       if (!DecodeDPRRegisterClass(Inst, (Rd+2)%32, Address, Decoder)) return false;
1729       break;
1730     default:
1731       break;
1732   }
1733 
1734   // Third input register
1735   switch (Inst.getOpcode()) {
1736     case ARM::VST1d8T:
1737     case ARM::VST1d16T:
1738     case ARM::VST1d32T:
1739     case ARM::VST1d64T:
1740     case ARM::VST1d8T_UPD:
1741     case ARM::VST1d16T_UPD:
1742     case ARM::VST1d32T_UPD:
1743     case ARM::VST1d64T_UPD:
1744     case ARM::VST1d8Q:
1745     case ARM::VST1d16Q:
1746     case ARM::VST1d32Q:
1747     case ARM::VST1d64Q:
1748     case ARM::VST1d8Q_UPD:
1749     case ARM::VST1d16Q_UPD:
1750     case ARM::VST1d32Q_UPD:
1751     case ARM::VST1d64Q_UPD:
1752     case ARM::VST2q8:
1753     case ARM::VST2q16:
1754     case ARM::VST2q32:
1755     case ARM::VST2q8_UPD:
1756     case ARM::VST2q16_UPD:
1757     case ARM::VST2q32_UPD:
1758     case ARM::VST3d8:
1759     case ARM::VST3d16:
1760     case ARM::VST3d32:
1761     case ARM::VST3d8_UPD:
1762     case ARM::VST3d16_UPD:
1763     case ARM::VST3d32_UPD:
1764     case ARM::VST4d8:
1765     case ARM::VST4d16:
1766     case ARM::VST4d32:
1767     case ARM::VST4d8_UPD:
1768     case ARM::VST4d16_UPD:
1769     case ARM::VST4d32_UPD:
1770       if (!DecodeDPRRegisterClass(Inst, (Rd+2)%32, Address, Decoder)) return false;
1771       break;
1772     case ARM::VST3q8:
1773     case ARM::VST3q16:
1774     case ARM::VST3q32:
1775     case ARM::VST3q8_UPD:
1776     case ARM::VST3q16_UPD:
1777     case ARM::VST3q32_UPD:
1778     case ARM::VST4q8:
1779     case ARM::VST4q16:
1780     case ARM::VST4q32:
1781     case ARM::VST4q8_UPD:
1782     case ARM::VST4q16_UPD:
1783     case ARM::VST4q32_UPD:
1784       if (!DecodeDPRRegisterClass(Inst, (Rd+4)%32, Address, Decoder)) return false;
1785       break;
1786     default:
1787       break;
1788   }
1789 
1790   // Fourth input register
1791   switch (Inst.getOpcode()) {
1792     case ARM::VST1d8Q:
1793     case ARM::VST1d16Q:
1794     case ARM::VST1d32Q:
1795     case ARM::VST1d64Q:
1796     case ARM::VST1d8Q_UPD:
1797     case ARM::VST1d16Q_UPD:
1798     case ARM::VST1d32Q_UPD:
1799     case ARM::VST1d64Q_UPD:
1800     case ARM::VST2q8:
1801     case ARM::VST2q16:
1802     case ARM::VST2q32:
1803     case ARM::VST2q8_UPD:
1804     case ARM::VST2q16_UPD:
1805     case ARM::VST2q32_UPD:
1806     case ARM::VST4d8:
1807     case ARM::VST4d16:
1808     case ARM::VST4d32:
1809     case ARM::VST4d8_UPD:
1810     case ARM::VST4d16_UPD:
1811     case ARM::VST4d32_UPD:
1812       if (!DecodeDPRRegisterClass(Inst, (Rd+3)%32, Address, Decoder)) return false;
1813       break;
1814     case ARM::VST4q8:
1815     case ARM::VST4q16:
1816     case ARM::VST4q32:
1817     case ARM::VST4q8_UPD:
1818     case ARM::VST4q16_UPD:
1819     case ARM::VST4q32_UPD:
1820       if (!DecodeDPRRegisterClass(Inst, (Rd+6)%32, Address, Decoder)) return false;
1821       break;
1822     default:
1823       break;
1824   }
1825 
1826   return true;
1827 }
1828 
1829 static bool DecodeVLD1DupInstruction(llvm::MCInst &Inst, unsigned Insn,
1830                                     uint64_t Address, const void *Decoder) {
1831   unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
1832   Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
1833   unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
1834   unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
1835   unsigned align = fieldFromInstruction32(Insn, 4, 1);
1836   unsigned size = fieldFromInstruction32(Insn, 6, 2);
1837   unsigned regs = fieldFromInstruction32(Insn, 5, 1) + 1;
1838 
1839   align *= (1 << size);
1840 
1841   if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
1842   if (regs == 2) {
1843     if (!DecodeDPRRegisterClass(Inst, (Rd+1)%32, Address, Decoder)) return false;
1844   }
1845   if (Rm == 0xD) {
1846     if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
1847   }
1848 
1849   if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
1850   Inst.addOperand(MCOperand::CreateImm(align));
1851 
1852   if (Rm == 0xD)
1853     Inst.addOperand(MCOperand::CreateReg(0));
1854   else if (Rm != 0xF) {
1855     if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder)) return false;
1856   }
1857 
1858   return true;
1859 }
1860 
1861 static bool DecodeVLD2DupInstruction(llvm::MCInst &Inst, unsigned Insn,
1862                                     uint64_t Address, const void *Decoder) {
1863   unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
1864   Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
1865   unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
1866   unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
1867   unsigned align = fieldFromInstruction32(Insn, 4, 1);
1868   unsigned size = 1 << fieldFromInstruction32(Insn, 6, 2);
1869   unsigned inc = fieldFromInstruction32(Insn, 5, 1) + 1;
1870   align *= 2*size;
1871 
1872   if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
1873   if (!DecodeDPRRegisterClass(Inst, (Rd+inc)%32, Address, Decoder)) return false;
1874   if (Rm == 0xD) {
1875     if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
1876   }
1877 
1878   if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
1879   Inst.addOperand(MCOperand::CreateImm(align));
1880 
1881   if (Rm == 0xD)
1882     Inst.addOperand(MCOperand::CreateReg(0));
1883   else if (Rm != 0xF) {
1884     if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder)) return false;
1885   }
1886 
1887   return true;
1888 }
1889 
1890 static bool DecodeVLD3DupInstruction(llvm::MCInst &Inst, unsigned Insn,
1891                                     uint64_t Address, const void *Decoder) {
1892   unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
1893   Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
1894   unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
1895   unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
1896   unsigned inc = fieldFromInstruction32(Insn, 5, 1) + 1;
1897 
1898   if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)          ||
1899       !DecodeDPRRegisterClass(Inst, (Rd+inc)%32, Address, Decoder) ||
1900       !DecodeDPRRegisterClass(Inst, (Rd+2*inc)%32, Address, Decoder))
1901     return false;
1902   if (Rm == 0xD) {
1903     if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
1904   }
1905 
1906   if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
1907   Inst.addOperand(MCOperand::CreateImm(0));
1908 
1909   if (Rm == 0xD)
1910     Inst.addOperand(MCOperand::CreateReg(0));
1911   else if (Rm != 0xF) {
1912     if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder)) return false;
1913   }
1914 
1915   return true;
1916 }
1917 
1918 static bool DecodeVLD4DupInstruction(llvm::MCInst &Inst, unsigned Insn,
1919                                     uint64_t Address, const void *Decoder) {
1920   unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
1921   Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
1922   unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
1923   unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
1924   unsigned size = fieldFromInstruction32(Insn, 6, 2);
1925   unsigned inc = fieldFromInstruction32(Insn, 5, 1) + 1;
1926   unsigned align = fieldFromInstruction32(Insn, 4, 1);
1927 
1928   if (size == 0x3) {
1929     size = 4;
1930     align = 16;
1931   } else {
1932     if (size == 2) {
1933       size = 1 << size;
1934       align *= 8;
1935     } else {
1936       size = 1 << size;
1937       align *= 4*size;
1938     }
1939   }
1940 
1941   if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)            ||
1942       !DecodeDPRRegisterClass(Inst, (Rd+inc)%32, Address, Decoder)   ||
1943       !DecodeDPRRegisterClass(Inst, (Rd+2*inc)%32, Address, Decoder) ||
1944       !DecodeDPRRegisterClass(Inst, (Rd+3*inc)%32, Address, Decoder))
1945     return false;
1946   if (Rm == 0xD) {
1947     if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
1948   }
1949 
1950   if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
1951   Inst.addOperand(MCOperand::CreateImm(align));
1952 
1953   if (Rm == 0xD)
1954     Inst.addOperand(MCOperand::CreateReg(0));
1955   else if (Rm != 0xF) {
1956     if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder)) return false;
1957   }
1958 
1959   return true;
1960 }
1961 
1962 static bool DecodeNEONModImmInstruction(llvm::MCInst &Inst, unsigned Insn,
1963                                         uint64_t Address, const void *Decoder) {
1964   unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
1965   Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
1966   unsigned imm = fieldFromInstruction32(Insn, 0, 4);
1967   imm |= fieldFromInstruction32(Insn, 16, 3) << 4;
1968   imm |= fieldFromInstruction32(Insn, 24, 1) << 7;
1969   imm |= fieldFromInstruction32(Insn, 8, 4) << 8;
1970   imm |= fieldFromInstruction32(Insn, 5, 1) << 12;
1971   unsigned Q = fieldFromInstruction32(Insn, 6, 1);
1972 
1973   if (Q) {
1974     if (!DecodeQPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
1975   } else {
1976     if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
1977   }
1978 
1979   Inst.addOperand(MCOperand::CreateImm(imm));
1980 
1981   switch (Inst.getOpcode()) {
1982     case ARM::VORRiv4i16:
1983     case ARM::VORRiv2i32:
1984     case ARM::VBICiv4i16:
1985     case ARM::VBICiv2i32:
1986       if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
1987       break;
1988     case ARM::VORRiv8i16:
1989     case ARM::VORRiv4i32:
1990     case ARM::VBICiv8i16:
1991     case ARM::VBICiv4i32:
1992       if (!DecodeQPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
1993       break;
1994     default:
1995       break;
1996   }
1997 
1998   return true;
1999 }
2000 
2001 static bool DecodeVSHLMaxInstruction(llvm::MCInst &Inst, unsigned Insn,
2002                                         uint64_t Address, const void *Decoder) {
2003   unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
2004   Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
2005   unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
2006   Rm |= fieldFromInstruction32(Insn, 5, 1) << 4;
2007   unsigned size = fieldFromInstruction32(Insn, 18, 2);
2008 
2009   if (!DecodeQPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
2010   if (!DecodeDPRRegisterClass(Inst, Rm, Address, Decoder)) return false;
2011   Inst.addOperand(MCOperand::CreateImm(8 << size));
2012 
2013   return true;
2014 }
2015 
2016 static bool DecodeShiftRight8Imm(llvm::MCInst &Inst, unsigned Val,
2017                                uint64_t Address, const void *Decoder) {
2018   Inst.addOperand(MCOperand::CreateImm(8 - Val));
2019   return true;
2020 }
2021 
2022 static bool DecodeShiftRight16Imm(llvm::MCInst &Inst, unsigned Val,
2023                                uint64_t Address, const void *Decoder) {
2024   Inst.addOperand(MCOperand::CreateImm(16 - Val));
2025   return true;
2026 }
2027 
2028 static bool DecodeShiftRight32Imm(llvm::MCInst &Inst, unsigned Val,
2029                                uint64_t Address, const void *Decoder) {
2030   Inst.addOperand(MCOperand::CreateImm(32 - Val));
2031   return true;
2032 }
2033 
2034 static bool DecodeShiftRight64Imm(llvm::MCInst &Inst, unsigned Val,
2035                                uint64_t Address, const void *Decoder) {
2036   Inst.addOperand(MCOperand::CreateImm(64 - Val));
2037   return true;
2038 }
2039 
2040 static bool DecodeTBLInstruction(llvm::MCInst &Inst, unsigned Insn,
2041                                uint64_t Address, const void *Decoder) {
2042   unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
2043   Rd |= fieldFromInstruction32(Insn, 22, 1) << 4;
2044   unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
2045   Rn |= fieldFromInstruction32(Insn, 7, 1) << 4;
2046   unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
2047   Rm |= fieldFromInstruction32(Insn, 5, 1) << 4;
2048   unsigned op = fieldFromInstruction32(Insn, 6, 1);
2049   unsigned length = fieldFromInstruction32(Insn, 8, 2) + 1;
2050 
2051   if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
2052   if (op) {
2053     if (!DecodeDPRRegisterClass(Inst, Rd, Address, Decoder)) return false; // Writeback
2054   }
2055 
2056   for (unsigned i = 0; i < length; ++i) {
2057     if (!DecodeDPRRegisterClass(Inst, (Rn+i)%32, Address, Decoder)) return false;
2058   }
2059 
2060   if (!DecodeDPRRegisterClass(Inst, Rm, Address, Decoder)) return false;
2061 
2062   return true;
2063 }
2064 
2065 static bool DecodeVFPfpImm(llvm::MCInst &Inst, unsigned Val,
2066                             uint64_t Address, const void *Decoder) {
2067   // The immediate needs to be a fully instantiated float.  However, the
2068   // auto-generated decoder is only able to fill in some of the bits
2069   // necessary.  For instance, the 'b' bit is replicated multiple times,
2070   // and is even present in inverted form in one bit.  We do a little
2071   // binary parsing here to fill in those missing bits, and then
2072   // reinterpret it all as a float.
2073   union {
2074     uint32_t integer;
2075     float fp;
2076   } fp_conv;
2077 
2078   fp_conv.integer = Val;
2079   uint32_t b = fieldFromInstruction32(Val, 25, 1);
2080   fp_conv.integer |= b << 26;
2081   fp_conv.integer |= b << 27;
2082   fp_conv.integer |= b << 28;
2083   fp_conv.integer |= b << 29;
2084   fp_conv.integer |= (~b & 0x1) << 30;
2085 
2086   Inst.addOperand(MCOperand::CreateFPImm(fp_conv.fp));
2087   return true;
2088 }
2089 
2090 static bool DecodeThumbAddSpecialReg(llvm::MCInst &Inst, uint16_t Insn,
2091                                      uint64_t Address, const void *Decoder) {
2092   unsigned dst = fieldFromInstruction16(Insn, 8, 3);
2093   unsigned imm = fieldFromInstruction16(Insn, 0, 8);
2094 
2095   if (!DecodetGPRRegisterClass(Inst, dst, Address, Decoder)) return false;
2096 
2097   if (Inst.getOpcode() == ARM::tADR)
2098     Inst.addOperand(MCOperand::CreateReg(ARM::PC));
2099   else if (Inst.getOpcode() == ARM::tADDrSPi)
2100     Inst.addOperand(MCOperand::CreateReg(ARM::SP));
2101   else
2102     return false;
2103 
2104   Inst.addOperand(MCOperand::CreateImm(imm));
2105   return true;
2106 }
2107 
2108 static bool DecodeThumbBROperand(llvm::MCInst &Inst, unsigned Val,
2109                                  uint64_t Address, const void *Decoder) {
2110   Inst.addOperand(MCOperand::CreateImm(SignExtend32<12>(Val << 1)));
2111   return true;
2112 }
2113 
2114 static bool DecodeT2BROperand(llvm::MCInst &Inst, unsigned Val,
2115                                  uint64_t Address, const void *Decoder) {
2116   Inst.addOperand(MCOperand::CreateImm(SignExtend32<21>(Val)));
2117   return true;
2118 }
2119 
2120 static bool DecodeThumbCmpBROperand(llvm::MCInst &Inst, unsigned Val,
2121                                  uint64_t Address, const void *Decoder) {
2122   Inst.addOperand(MCOperand::CreateImm(SignExtend32<7>(Val << 1)));
2123   return true;
2124 }
2125 
2126 static bool DecodeThumbAddrModeRR(llvm::MCInst &Inst, unsigned Val,
2127                                  uint64_t Address, const void *Decoder) {
2128   unsigned Rn = fieldFromInstruction32(Val, 0, 3);
2129   unsigned Rm = fieldFromInstruction32(Val, 3, 3);
2130 
2131   if (!DecodetGPRRegisterClass(Inst, Rn, Address, Decoder) ||
2132       !DecodetGPRRegisterClass(Inst, Rm, Address, Decoder))
2133     return false;
2134 
2135   return true;
2136 }
2137 
2138 static bool DecodeThumbAddrModeIS(llvm::MCInst &Inst, unsigned Val,
2139                                   uint64_t Address, const void *Decoder) {
2140   unsigned Rn = fieldFromInstruction32(Val, 0, 3);
2141   unsigned imm = fieldFromInstruction32(Val, 3, 5);
2142 
2143   if (!DecodetGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
2144   Inst.addOperand(MCOperand::CreateImm(imm));
2145 
2146   return true;
2147 }
2148 
2149 static bool DecodeThumbAddrModePC(llvm::MCInst &Inst, unsigned Val,
2150                                   uint64_t Address, const void *Decoder) {
2151   Inst.addOperand(MCOperand::CreateImm(Val << 2));
2152 
2153   return true;
2154 }
2155 
2156 static bool DecodeThumbAddrModeSP(llvm::MCInst &Inst, unsigned Val,
2157                                   uint64_t Address, const void *Decoder) {
2158   Inst.addOperand(MCOperand::CreateReg(ARM::SP));
2159   Inst.addOperand(MCOperand::CreateImm(Val << 2));
2160 
2161   return true;
2162 }
2163 
2164 static bool DecodeT2AddrModeSOReg(llvm::MCInst &Inst, unsigned Val,
2165                                   uint64_t Address, const void *Decoder) {
2166   unsigned Rn = fieldFromInstruction32(Val, 6, 4);
2167   unsigned Rm = fieldFromInstruction32(Val, 2, 4);
2168   unsigned imm = fieldFromInstruction32(Val, 0, 2);
2169 
2170   if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder) ||
2171       !DecoderGPRRegisterClass(Inst, Rm, Address, Decoder))
2172     return false;
2173   Inst.addOperand(MCOperand::CreateImm(imm));
2174 
2175   return true;
2176 }
2177 
2178 static bool DecodeT2LoadShift(llvm::MCInst &Inst, unsigned Insn,
2179                               uint64_t Address, const void *Decoder) {
2180   if (Inst.getOpcode() != ARM::t2PLDs) {
2181     unsigned Rt = fieldFromInstruction32(Insn, 12, 4);
2182     if (!DecodeGPRRegisterClass(Inst, Rt, Address, Decoder)) return false;
2183   }
2184 
2185   unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
2186   if (Rn == 0xF) {
2187     switch (Inst.getOpcode()) {
2188       case ARM::t2LDRBs:
2189         Inst.setOpcode(ARM::t2LDRBpci);
2190         break;
2191       case ARM::t2LDRHs:
2192         Inst.setOpcode(ARM::t2LDRHpci);
2193         break;
2194       case ARM::t2LDRSHs:
2195         Inst.setOpcode(ARM::t2LDRSHpci);
2196         break;
2197       case ARM::t2LDRSBs:
2198         Inst.setOpcode(ARM::t2LDRSBpci);
2199         break;
2200       case ARM::t2PLDs:
2201         Inst.setOpcode(ARM::t2PLDi12);
2202         Inst.addOperand(MCOperand::CreateReg(ARM::PC));
2203         break;
2204       default:
2205         return false;
2206     }
2207 
2208     int imm = fieldFromInstruction32(Insn, 0, 12);
2209     if (!fieldFromInstruction32(Insn, 23, 1)) imm *= -1;
2210     Inst.addOperand(MCOperand::CreateImm(imm));
2211 
2212     return true;
2213   }
2214 
2215   unsigned addrmode = fieldFromInstruction32(Insn, 4, 2);
2216   addrmode |= fieldFromInstruction32(Insn, 0, 4) << 2;
2217   addrmode |= fieldFromInstruction32(Insn, 16, 4) << 6;
2218   DecodeT2AddrModeSOReg(Inst, addrmode, Address, Decoder);
2219 
2220   return true;
2221 }
2222 
2223 static bool DecodeT2Imm8S4(llvm::MCInst &Inst, unsigned Val,
2224                            uint64_t Address, const void *Decoder) {
2225   int imm = Val & 0xFF;
2226   if (!(Val & 0x100)) imm *= -1;
2227   Inst.addOperand(MCOperand::CreateImm(imm << 2));
2228 
2229   return true;
2230 }
2231 
2232 static bool DecodeT2AddrModeImm8s4(llvm::MCInst &Inst, unsigned Val,
2233                                    uint64_t Address, const void *Decoder) {
2234   unsigned Rn = fieldFromInstruction32(Val, 9, 4);
2235   unsigned imm = fieldFromInstruction32(Val, 0, 9);
2236 
2237   if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder) ||
2238       !DecodeT2Imm8S4(Inst, imm, Address, Decoder))
2239     return false;
2240 
2241   return true;
2242 }
2243 
2244 static bool DecodeT2Imm8(llvm::MCInst &Inst, unsigned Val,
2245                          uint64_t Address, const void *Decoder) {
2246   int imm = Val & 0xFF;
2247   if (!(Val & 0x100)) imm *= -1;
2248   Inst.addOperand(MCOperand::CreateImm(imm));
2249 
2250   return true;
2251 }
2252 
2253 
2254 static bool DecodeT2AddrModeImm8(llvm::MCInst &Inst, unsigned Val,
2255                                  uint64_t Address, const void *Decoder) {
2256   unsigned Rn = fieldFromInstruction32(Val, 9, 4);
2257   unsigned imm = fieldFromInstruction32(Val, 0, 9);
2258 
2259   // Some instructions always use an additive offset.
2260   switch (Inst.getOpcode()) {
2261     case ARM::t2LDRT:
2262     case ARM::t2LDRBT:
2263     case ARM::t2LDRHT:
2264     case ARM::t2LDRSBT:
2265     case ARM::t2LDRSHT:
2266       imm |= 0x100;
2267       break;
2268     default:
2269       break;
2270   }
2271 
2272   if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder) ||
2273       !DecodeT2Imm8(Inst, imm, Address, Decoder))
2274     return false;
2275 
2276   return true;
2277 }
2278 
2279 
2280 static bool DecodeT2AddrModeImm12(llvm::MCInst &Inst, unsigned Val,
2281                                   uint64_t Address, const void *Decoder) {
2282   unsigned Rn = fieldFromInstruction32(Val, 13, 4);
2283   unsigned imm = fieldFromInstruction32(Val, 0, 12);
2284 
2285   if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
2286   Inst.addOperand(MCOperand::CreateImm(imm));
2287 
2288   return true;
2289 }
2290 
2291 
2292 static bool DecodeThumbAddSPImm(llvm::MCInst &Inst, uint16_t Insn,
2293                                 uint64_t Address, const void *Decoder) {
2294   unsigned imm = fieldFromInstruction16(Insn, 0, 7);
2295 
2296   Inst.addOperand(MCOperand::CreateReg(ARM::SP));
2297   Inst.addOperand(MCOperand::CreateReg(ARM::SP));
2298   Inst.addOperand(MCOperand::CreateImm(imm));
2299 
2300   return true;
2301 }
2302 
2303 static bool DecodeThumbAddSPReg(llvm::MCInst &Inst, uint16_t Insn,
2304                                 uint64_t Address, const void *Decoder) {
2305   if (Inst.getOpcode() == ARM::tADDrSP) {
2306     unsigned Rdm = fieldFromInstruction16(Insn, 0, 3);
2307     Rdm |= fieldFromInstruction16(Insn, 7, 1) << 3;
2308 
2309     if (!DecodeGPRRegisterClass(Inst, Rdm, Address, Decoder)) return false;
2310     Inst.addOperand(MCOperand::CreateReg(ARM::SP));
2311     if (!DecodeGPRRegisterClass(Inst, Rdm, Address, Decoder)) return false;
2312   } else if (Inst.getOpcode() == ARM::tADDspr) {
2313     unsigned Rm = fieldFromInstruction16(Insn, 3, 4);
2314 
2315     Inst.addOperand(MCOperand::CreateReg(ARM::SP));
2316     Inst.addOperand(MCOperand::CreateReg(ARM::SP));
2317     if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder)) return false;
2318   }
2319 
2320   return true;
2321 }
2322 
2323 static bool DecodeThumbCPS(llvm::MCInst &Inst, uint16_t Insn,
2324                            uint64_t Address, const void *Decoder) {
2325   unsigned imod = fieldFromInstruction16(Insn, 4, 1) | 0x2;
2326   unsigned flags = fieldFromInstruction16(Insn, 0, 3);
2327 
2328   Inst.addOperand(MCOperand::CreateImm(imod));
2329   Inst.addOperand(MCOperand::CreateImm(flags));
2330 
2331   return true;
2332 }
2333 
2334 static bool DecodePostIdxReg(llvm::MCInst &Inst, unsigned Insn,
2335                              uint64_t Address, const void *Decoder) {
2336   unsigned Rm = fieldFromInstruction32(Insn, 0, 4);
2337   unsigned add = fieldFromInstruction32(Insn, 4, 1);
2338 
2339   if (!DecodeGPRRegisterClass(Inst, Rm, Address, Decoder)) return false;
2340   Inst.addOperand(MCOperand::CreateImm(add));
2341 
2342   return true;
2343 }
2344 
2345 static bool DecodeThumbBLXOffset(llvm::MCInst &Inst, unsigned Val,
2346                                  uint64_t Address, const void *Decoder) {
2347   Inst.addOperand(MCOperand::CreateImm(SignExtend32<22>(Val << 1)));
2348   return true;
2349 }
2350 
2351 static bool DecodeCoprocessor(llvm::MCInst &Inst, unsigned Val,
2352                               uint64_t Address, const void *Decoder) {
2353   if (Val == 0xA || Val == 0xB)
2354     return false;
2355 
2356   Inst.addOperand(MCOperand::CreateImm(Val));
2357   return true;
2358 }
2359 
2360 static bool DecodeThumbSRImm(llvm::MCInst &Inst, unsigned Val,
2361                              uint64_t Address, const void *Decoder) {
2362   if (Val == 0)
2363     Inst.addOperand(MCOperand::CreateImm(32));
2364   else
2365     Inst.addOperand(MCOperand::CreateImm(Val));
2366   return true;
2367 }
2368 
2369 static bool DecodeThumb2BCCInstruction(llvm::MCInst &Inst, unsigned Insn,
2370                                        uint64_t Address, const void *Decoder) {
2371   unsigned pred = fieldFromInstruction32(Insn, 22, 4);
2372   if (pred == 0xE || pred == 0xF) {
2373     unsigned opc = fieldFromInstruction32(Insn, 4, 2);
2374     switch (opc) {
2375       default:
2376         return false;
2377       case 0:
2378         Inst.setOpcode(ARM::t2DSB);
2379         break;
2380       case 1:
2381         Inst.setOpcode(ARM::t2DMB);
2382         break;
2383       case 2:
2384         Inst.setOpcode(ARM::t2ISB);
2385         return true;
2386     }
2387 
2388     unsigned imm = fieldFromInstruction32(Insn, 0, 4);
2389     return DecodeMemBarrierOption(Inst, imm, Address, Decoder);
2390   }
2391 
2392   unsigned brtarget = fieldFromInstruction32(Insn, 0, 11) << 1;
2393   brtarget |= fieldFromInstruction32(Insn, 11, 1) << 19;
2394   brtarget |= fieldFromInstruction32(Insn, 13, 1) << 18;
2395   brtarget |= fieldFromInstruction32(Insn, 16, 6) << 12;
2396   brtarget |= fieldFromInstruction32(Insn, 26, 1) << 20;
2397 
2398   if (!DecodeT2BROperand(Inst, brtarget, Address, Decoder) ||
2399       !DecodePredicateOperand(Inst, pred, Address, Decoder))
2400     return false;
2401 
2402   return true;
2403 }
2404 
2405 // Decode a shifted immediate operand.  These basically consist
2406 // of an 8-bit value, and a 4-bit directive that specifies either
2407 // a splat operation or a rotation.
2408 static bool DecodeT2SOImm(llvm::MCInst &Inst, unsigned Val,
2409                           uint64_t Address, const void *Decoder) {
2410   unsigned ctrl = fieldFromInstruction32(Val, 10, 2);
2411   if (ctrl == 0) {
2412     unsigned byte = fieldFromInstruction32(Val, 8, 2);
2413     unsigned imm = fieldFromInstruction32(Val, 0, 8);
2414     switch (byte) {
2415       case 0:
2416         Inst.addOperand(MCOperand::CreateImm(imm));
2417         break;
2418       case 1:
2419         Inst.addOperand(MCOperand::CreateImm((imm << 16) | imm));
2420         break;
2421       case 2:
2422         Inst.addOperand(MCOperand::CreateImm((imm << 24) | (imm << 8)));
2423         break;
2424       case 3:
2425         Inst.addOperand(MCOperand::CreateImm((imm << 24) | (imm << 16) |
2426                                              (imm << 8)  |  imm));
2427         break;
2428     }
2429   } else {
2430     unsigned unrot = fieldFromInstruction32(Val, 0, 7) | 0x80;
2431     unsigned rot = fieldFromInstruction32(Val, 7, 5);
2432     unsigned imm = (unrot >> rot) | (unrot << ((32-rot)&31));
2433     Inst.addOperand(MCOperand::CreateImm(imm));
2434   }
2435 
2436   return true;
2437 }
2438 
2439 static bool DecodeThumbBCCTargetOperand(llvm::MCInst &Inst, unsigned Val,
2440                                         uint64_t Address, const void *Decoder){
2441   Inst.addOperand(MCOperand::CreateImm(Val << 1));
2442   return true;
2443 }
2444 
2445 static bool DecodeThumbBLTargetOperand(llvm::MCInst &Inst, unsigned Val,
2446                                        uint64_t Address, const void *Decoder){
2447   Inst.addOperand(MCOperand::CreateImm(SignExtend32<22>(Val << 1)));
2448   return true;
2449 }
2450 
2451 static bool DecodeAddrMode3Offset(llvm::MCInst &Inst, unsigned Val,
2452                                   uint64_t Address, const void *Decoder) {
2453   bool isImm = fieldFromInstruction32(Val, 9, 1);
2454   bool isAdd = fieldFromInstruction32(Val, 8, 1);
2455   unsigned imm = fieldFromInstruction32(Val, 0, 8);
2456 
2457   if (!isImm) {
2458     if (!DecodeGPRRegisterClass(Inst, imm, Address, Decoder)) return false;
2459     Inst.addOperand(MCOperand::CreateImm(!isAdd << 8));
2460   } else {
2461     Inst.addOperand(MCOperand::CreateReg(0));
2462     Inst.addOperand(MCOperand::CreateImm(imm | (!isAdd << 8)));
2463   }
2464 
2465   return true;
2466 }
2467 
2468 static bool DecodeMemBarrierOption(llvm::MCInst &Inst, unsigned Val,
2469                                    uint64_t Address, const void *Decoder) {
2470   switch (Val) {
2471   default:
2472     return false;
2473   case 0xF: // SY
2474   case 0xE: // ST
2475   case 0xB: // ISH
2476   case 0xA: // ISHST
2477   case 0x7: // NSH
2478   case 0x6: // NSHST
2479   case 0x3: // OSH
2480   case 0x2: // OSHST
2481     break;
2482   }
2483 
2484   Inst.addOperand(MCOperand::CreateImm(Val));
2485   return true;
2486 }
2487 
2488 static bool DecodeMSRMask(llvm::MCInst &Inst, unsigned Val,
2489                           uint64_t Address, const void *Decoder) {
2490   if (!Val) return false;
2491   Inst.addOperand(MCOperand::CreateImm(Val));
2492   return true;
2493 }
2494 
2495 static bool DecodeDoubleRegLoad(llvm::MCInst &Inst, unsigned Insn,
2496                                           uint64_t Address, const void *Decoder) {
2497   unsigned Rt = fieldFromInstruction32(Insn, 12, 4);
2498   unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
2499   unsigned pred = fieldFromInstruction32(Insn, 28, 4);
2500 
2501   if ((Rt & 1) || Rt == 0xE || Rn == 0xF) return false;
2502 
2503   if (!DecodeGPRRegisterClass(Inst, Rt, Address, Decoder)) return false;
2504   if (!DecodeGPRRegisterClass(Inst, Rt+1, Address, Decoder)) return false;
2505   if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
2506   if (!DecodePredicateOperand(Inst, pred, Address, Decoder)) return false;
2507 
2508   return true;
2509 }
2510 
2511 
2512 static bool DecodeDoubleRegStore(llvm::MCInst &Inst, unsigned Insn,
2513                                           uint64_t Address, const void *Decoder) {
2514   unsigned Rd = fieldFromInstruction32(Insn, 12, 4);
2515   unsigned Rt = fieldFromInstruction32(Insn, 0, 4);
2516   unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
2517   unsigned pred = fieldFromInstruction32(Insn, 28, 4);
2518 
2519   if (!DecoderGPRRegisterClass(Inst, Rd, Address, Decoder)) return false;
2520 
2521   if ((Rt & 1) || Rt == 0xE || Rn == 0xF) return false;
2522   if (Rd == Rn || Rd == Rt || Rd == Rt+1) return false;
2523 
2524   if (!DecodeGPRRegisterClass(Inst, Rt, Address, Decoder)) return false;
2525   if (!DecodeGPRRegisterClass(Inst, Rt+1, Address, Decoder)) return false;
2526   if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
2527   if (!DecodePredicateOperand(Inst, pred, Address, Decoder)) return false;
2528 
2529   return true;
2530 }
2531 
2532 static bool DecodeSTRPreImm(llvm::MCInst &Inst, unsigned Insn,
2533                             uint64_t Address, const void *Decoder) {
2534   unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
2535   unsigned Rt = fieldFromInstruction32(Insn, 12, 4);
2536   unsigned imm = fieldFromInstruction32(Insn, 0, 12);
2537   imm |= fieldFromInstruction32(Insn, 16, 4) << 13;
2538   imm |= fieldFromInstruction32(Insn, 23, 1) << 12;
2539   unsigned pred = fieldFromInstruction32(Insn, 28, 4);
2540 
2541   if (Rn == 0xF || Rn == Rt) return false; // UNPREDICTABLE
2542 
2543   if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
2544   if (!DecodeGPRRegisterClass(Inst, Rt, Address, Decoder)) return false;
2545   if (!DecodeAddrModeImm12Operand(Inst, imm, Address, Decoder)) return false;
2546   if (!DecodePredicateOperand(Inst, pred, Address, Decoder)) return false;
2547 
2548   return true;
2549 }
2550 
2551 static bool DecodeSTRPreReg(llvm::MCInst &Inst, unsigned Insn,
2552                             uint64_t Address, const void *Decoder) {
2553   unsigned Rn = fieldFromInstruction32(Insn, 16, 4);
2554   unsigned Rt = fieldFromInstruction32(Insn, 12, 4);
2555   unsigned imm = fieldFromInstruction32(Insn, 0, 12);
2556   imm |= fieldFromInstruction32(Insn, 16, 4) << 13;
2557   imm |= fieldFromInstruction32(Insn, 23, 1) << 12;
2558   unsigned pred = fieldFromInstruction32(Insn, 28, 4);
2559 
2560   if (Rn == 0xF || Rn == Rt) return false; // UNPREDICTABLE
2561 
2562   if (!DecodeGPRRegisterClass(Inst, Rn, Address, Decoder)) return false;
2563   if (!DecodeGPRRegisterClass(Inst, Rt, Address, Decoder)) return false;
2564   if (!DecodeSORegMemOperand(Inst, imm, Address, Decoder)) return false;
2565   if (!DecodePredicateOperand(Inst, pred, Address, Decoder)) return false;
2566 
2567   return true;
2568 }
2569