1 //===- HexagonDisassembler.cpp - Disassembler for Hexagon ISA -------------===//
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 "hexagon-disassembler"
11 
12 #include "MCTargetDesc/HexagonBaseInfo.h"
13 #include "MCTargetDesc/HexagonMCChecker.h"
14 #include "MCTargetDesc/HexagonMCInstrInfo.h"
15 #include "MCTargetDesc/HexagonMCTargetDesc.h"
16 #include "llvm/ADT/ArrayRef.h"
17 #include "llvm/ADT/STLExtras.h"
18 #include "llvm/MC/MCContext.h"
19 #include "llvm/MC/MCDisassembler/MCDisassembler.h"
20 #include "llvm/MC/MCExpr.h"
21 #include "llvm/MC/MCFixedLenDisassembler.h"
22 #include "llvm/MC/MCInst.h"
23 #include "llvm/MC/MCInstrInfo.h"
24 #include "llvm/MC/MCRegisterInfo.h"
25 #include "llvm/MC/MCSubtargetInfo.h"
26 #include "llvm/Support/Endian.h"
27 #include "llvm/Support/MathExtras.h"
28 #include "llvm/Support/TargetRegistry.h"
29 #include "llvm/Support/raw_ostream.h"
30 #include <cassert>
31 #include <cstddef>
32 #include <cstdint>
33 #include <memory>
34 
35 using namespace llvm;
36 using namespace Hexagon;
37 
38 using DecodeStatus = MCDisassembler::DecodeStatus;
39 
40 namespace {
41 
42 /// Hexagon disassembler for all Hexagon platforms.
43 class HexagonDisassembler : public MCDisassembler {
44 public:
45   std::unique_ptr<MCInstrInfo const> const MCII;
46   std::unique_ptr<MCInst *> CurrentBundle;
47   mutable MCInst const *CurrentExtender;
48 
49   HexagonDisassembler(const MCSubtargetInfo &STI, MCContext &Ctx,
50                       MCInstrInfo const *MCII)
51       : MCDisassembler(STI, Ctx), MCII(MCII), CurrentBundle(new MCInst *),
52         CurrentExtender(nullptr) {}
53 
54   DecodeStatus getSingleInstruction(MCInst &Instr, MCInst &MCB,
55                                     ArrayRef<uint8_t> Bytes, uint64_t Address,
56                                     raw_ostream &VStream, raw_ostream &CStream,
57                                     bool &Complete) const;
58   DecodeStatus getInstruction(MCInst &Instr, uint64_t &Size,
59                               ArrayRef<uint8_t> Bytes, uint64_t Address,
60                               raw_ostream &VStream,
61                               raw_ostream &CStream) const override;
62   void remapInstruction(MCInst &Instr) const;
63 };
64 
65 static uint64_t fullValue(HexagonDisassembler const &Disassembler, MCInst &MI,
66                           int64_t Value) {
67   MCInstrInfo MCII = *Disassembler.MCII;
68   if (!Disassembler.CurrentExtender ||
69       MI.size() != HexagonMCInstrInfo::getExtendableOp(MCII, MI))
70     return Value;
71   unsigned Alignment = HexagonMCInstrInfo::getExtentAlignment(MCII, MI);
72   uint32_t Lower6 = static_cast<uint32_t>(Value >> Alignment) & 0x3f;
73   int64_t Bits;
74   bool Success =
75       Disassembler.CurrentExtender->getOperand(0).getExpr()->evaluateAsAbsolute(
76           Bits);
77   assert(Success);
78   (void)Success;
79   uint64_t Upper26 = static_cast<uint64_t>(Bits);
80   uint64_t Operand = Upper26 | Lower6;
81   return Operand;
82 }
83 static HexagonDisassembler const &disassembler(void const *Decoder) {
84   return *static_cast<HexagonDisassembler const *>(Decoder);
85 }
86 template <size_t T>
87 static void signedDecoder(MCInst &MI, unsigned tmp, const void *Decoder) {
88   HexagonDisassembler const &Disassembler = disassembler(Decoder);
89   int64_t FullValue = fullValue(Disassembler, MI, SignExtend64<T>(tmp));
90   int64_t Extended = SignExtend64<32>(FullValue);
91   HexagonMCInstrInfo::addConstant(MI, Extended, Disassembler.getContext());
92 }
93 }
94 
95 // Forward declare these because the auto-generated code will reference them.
96 // Definitions are further down.
97 
98 static DecodeStatus DecodeIntRegsRegisterClass(MCInst &Inst, unsigned RegNo,
99                                                uint64_t Address,
100                                                const void *Decoder);
101 static DecodeStatus DecodeGeneralSubRegsRegisterClass(MCInst &Inst,
102                                                       unsigned RegNo,
103                                                       uint64_t Address,
104                                                       const void *Decoder);
105 static DecodeStatus DecodeIntRegsLow8RegisterClass(MCInst &Inst, unsigned RegNo,
106                                                    uint64_t Address,
107                                                    const void *Decoder);
108 static DecodeStatus DecodeHvxVRRegisterClass(MCInst &Inst, unsigned RegNo,
109                                              uint64_t Address,
110                                              const void *Decoder);
111 static DecodeStatus DecodeDoubleRegsRegisterClass(MCInst &Inst, unsigned RegNo,
112                                                   uint64_t Address,
113                                                   const void *Decoder);
114 static DecodeStatus
115 DecodeGeneralDoubleLow8RegsRegisterClass(MCInst &Inst, unsigned RegNo,
116                                          uint64_t Address, const void *Decoder);
117 static DecodeStatus DecodeHvxWRRegisterClass(MCInst &Inst, unsigned RegNo,
118                                              uint64_t Address,
119                                              const void *Decoder);
120 static DecodeStatus DecodePredRegsRegisterClass(MCInst &Inst, unsigned RegNo,
121                                                 uint64_t Address,
122                                                 const void *Decoder);
123 static DecodeStatus DecodeHvxQRRegisterClass(MCInst &Inst, unsigned RegNo,
124                                              uint64_t Address,
125                                              const void *Decoder);
126 static DecodeStatus DecodeCtrRegsRegisterClass(MCInst &Inst, unsigned RegNo,
127                                                uint64_t Address,
128                                                const void *Decoder);
129 static DecodeStatus DecodeGuestRegsRegisterClass(MCInst &Inst, unsigned RegNo,
130                                                  uint64_t Address,
131                                                  const void *Decoder);
132 static DecodeStatus DecodeModRegsRegisterClass(MCInst &Inst, unsigned RegNo,
133                                                uint64_t Address,
134                                                const void *Decoder);
135 static DecodeStatus DecodeCtrRegs64RegisterClass(MCInst &Inst, unsigned RegNo,
136                                                  uint64_t Address,
137                                                  const void *Decoder);
138 static DecodeStatus DecodeGuestRegs64RegisterClass(MCInst &Inst, unsigned RegNo,
139                                                    uint64_t Address,
140                                                    const void *Decoder);
141 
142 static DecodeStatus unsignedImmDecoder(MCInst &MI, unsigned tmp,
143                                        uint64_t Address, const void *Decoder);
144 static DecodeStatus s32_0ImmDecoder(MCInst &MI, unsigned tmp,
145                                     uint64_t /*Address*/, const void *Decoder);
146 static DecodeStatus brtargetDecoder(MCInst &MI, unsigned tmp, uint64_t Address,
147                                     const void *Decoder);
148 
149 static DecodeStatus s4_0ImmDecoder(MCInst &MI, unsigned tmp, uint64_t,
150                                    const void *Decoder) {
151   signedDecoder<4>(MI, tmp, Decoder);
152   return MCDisassembler::Success;
153 }
154 static DecodeStatus s29_3ImmDecoder(MCInst &MI, unsigned tmp, uint64_t,
155                                     const void *Decoder) {
156   signedDecoder<14>(MI, tmp, Decoder);
157   return MCDisassembler::Success;
158 }
159 static DecodeStatus s8_0ImmDecoder(MCInst &MI, unsigned tmp, uint64_t,
160                                    const void *Decoder) {
161   signedDecoder<8>(MI, tmp, Decoder);
162   return MCDisassembler::Success;
163 }
164 static DecodeStatus s4_3ImmDecoder(MCInst &MI, unsigned tmp, uint64_t,
165                                    const void *Decoder) {
166   signedDecoder<7>(MI, tmp, Decoder);
167   return MCDisassembler::Success;
168 }
169 static DecodeStatus s31_1ImmDecoder(MCInst &MI, unsigned tmp, uint64_t,
170                                     const void *Decoder) {
171   signedDecoder<12>(MI, tmp, Decoder);
172   return MCDisassembler::Success;
173 }
174 static DecodeStatus s3_0ImmDecoder(MCInst &MI, unsigned tmp, uint64_t,
175                                    const void *Decoder) {
176   signedDecoder<3>(MI, tmp, Decoder);
177   return MCDisassembler::Success;
178 }
179 static DecodeStatus s30_2ImmDecoder(MCInst &MI, unsigned tmp, uint64_t,
180                                     const void *Decoder) {
181   signedDecoder<13>(MI, tmp, Decoder);
182   return MCDisassembler::Success;
183 }
184 static DecodeStatus s6_0ImmDecoder(MCInst &MI, unsigned tmp, uint64_t,
185                                    const void *Decoder) {
186   signedDecoder<6>(MI, tmp, Decoder);
187   return MCDisassembler::Success;
188 }
189 static DecodeStatus s6_3ImmDecoder(MCInst &MI, unsigned tmp, uint64_t,
190                                    const void *Decoder) {
191   signedDecoder<9>(MI, tmp, Decoder);
192   return MCDisassembler::Success;
193 }
194 static DecodeStatus s4_1ImmDecoder(MCInst &MI, unsigned tmp, uint64_t,
195                                    const void *Decoder) {
196   signedDecoder<5>(MI, tmp, Decoder);
197   return MCDisassembler::Success;
198 }
199 static DecodeStatus s4_2ImmDecoder(MCInst &MI, unsigned tmp, uint64_t,
200                                    const void *Decoder) {
201   signedDecoder<6>(MI, tmp, Decoder);
202   return MCDisassembler::Success;
203 }
204 #include "HexagonGenDisassemblerTables.inc"
205 
206 static MCDisassembler *createHexagonDisassembler(const Target &T,
207                                                  const MCSubtargetInfo &STI,
208                                                  MCContext &Ctx) {
209   return new HexagonDisassembler(STI, Ctx, T.createMCInstrInfo());
210 }
211 
212 extern "C" void LLVMInitializeHexagonDisassembler() {
213   TargetRegistry::RegisterMCDisassembler(getTheHexagonTarget(),
214                                          createHexagonDisassembler);
215 }
216 
217 DecodeStatus HexagonDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
218                                                  ArrayRef<uint8_t> Bytes,
219                                                  uint64_t Address,
220                                                  raw_ostream &os,
221                                                  raw_ostream &cs) const {
222   DecodeStatus Result = DecodeStatus::Success;
223   bool Complete = false;
224   Size = 0;
225 
226   *CurrentBundle = &MI;
227   MI.setOpcode(Hexagon::BUNDLE);
228   MI.addOperand(MCOperand::createImm(0));
229   while (Result == Success && !Complete) {
230     if (Bytes.size() < HEXAGON_INSTR_SIZE)
231       return MCDisassembler::Fail;
232     MCInst *Inst = new (getContext()) MCInst;
233     Result = getSingleInstruction(*Inst, MI, Bytes, Address, os, cs, Complete);
234     MI.addOperand(MCOperand::createInst(Inst));
235     Size += HEXAGON_INSTR_SIZE;
236     Bytes = Bytes.slice(HEXAGON_INSTR_SIZE);
237   }
238   if (Result == MCDisassembler::Fail)
239     return Result;
240   if (Size > HEXAGON_MAX_PACKET_SIZE)
241     return MCDisassembler::Fail;
242   HexagonMCChecker Checker(getContext(), *MCII, STI, MI,
243                            *getContext().getRegisterInfo(), false);
244   if (!Checker.check())
245     return MCDisassembler::Fail;
246   remapInstruction(MI);
247   return MCDisassembler::Success;
248 }
249 
250 void HexagonDisassembler::remapInstruction(MCInst &Instr) const {
251   for (auto I: HexagonMCInstrInfo::bundleInstructions(Instr)) {
252     auto &MI = const_cast<MCInst &>(*I.getInst());
253     switch (MI.getOpcode()) {
254     case Hexagon::S2_allocframe:
255       if (MI.getOperand(0).getReg() == Hexagon::R29) {
256         MI.setOpcode(Hexagon::S6_allocframe_to_raw);
257         MI.erase(MI.begin () + 1);
258         MI.erase(MI.begin ());
259       }
260       break;
261     case Hexagon::L2_deallocframe:
262       if (MI.getOperand(0).getReg() == Hexagon::D15 &&
263           MI.getOperand(1).getReg() == Hexagon::R30) {
264         MI.setOpcode(L6_deallocframe_map_to_raw);
265         MI.erase(MI.begin () + 1);
266         MI.erase(MI.begin ());
267       }
268       break;
269     case Hexagon::L4_return:
270       if (MI.getOperand(0).getReg() == Hexagon::D15 &&
271           MI.getOperand(1).getReg() == Hexagon::R30) {
272         MI.setOpcode(L6_return_map_to_raw);
273         MI.erase(MI.begin () + 1);
274         MI.erase(MI.begin ());
275       }
276       break;
277     case Hexagon::L4_return_t:
278       if (MI.getOperand(0).getReg() == Hexagon::D15 &&
279           MI.getOperand(2).getReg() == Hexagon::R30) {
280         MI.setOpcode(L4_return_map_to_raw_t);
281         MI.erase(MI.begin () + 2);
282         MI.erase(MI.begin ());
283       }
284       break;
285     case Hexagon::L4_return_f:
286       if (MI.getOperand(0).getReg() == Hexagon::D15 &&
287           MI.getOperand(2).getReg() == Hexagon::R30) {
288         MI.setOpcode(L4_return_map_to_raw_f);
289         MI.erase(MI.begin () + 2);
290         MI.erase(MI.begin ());
291       }
292       break;
293     case Hexagon::L4_return_tnew_pt:
294       if (MI.getOperand(0).getReg() == Hexagon::D15 &&
295           MI.getOperand(2).getReg() == Hexagon::R30) {
296         MI.setOpcode(L4_return_map_to_raw_tnew_pt);
297         MI.erase(MI.begin () + 2);
298         MI.erase(MI.begin ());
299       }
300       break;
301     case Hexagon::L4_return_fnew_pt:
302       if (MI.getOperand(0).getReg() == Hexagon::D15 &&
303           MI.getOperand(2).getReg() == Hexagon::R30) {
304         MI.setOpcode(L4_return_map_to_raw_fnew_pt);
305         MI.erase(MI.begin () + 2);
306         MI.erase(MI.begin ());
307       }
308       break;
309     case Hexagon::L4_return_tnew_pnt:
310       if (MI.getOperand(0).getReg() == Hexagon::D15 &&
311           MI.getOperand(2).getReg() == Hexagon::R30) {
312         MI.setOpcode(L4_return_map_to_raw_tnew_pnt);
313         MI.erase(MI.begin () + 2);
314         MI.erase(MI.begin ());
315       }
316       break;
317     case Hexagon::L4_return_fnew_pnt:
318       if (MI.getOperand(0).getReg() == Hexagon::D15 &&
319           MI.getOperand(2).getReg() == Hexagon::R30) {
320         MI.setOpcode(L4_return_map_to_raw_fnew_pnt);
321         MI.erase(MI.begin () + 2);
322         MI.erase(MI.begin ());
323       }
324       break;
325     }
326   }
327 }
328 
329 static void adjustDuplex(MCInst &MI, MCContext &Context) {
330   switch (MI.getOpcode()) {
331   case Hexagon::SA1_setin1:
332     MI.insert(MI.begin() + 1,
333               MCOperand::createExpr(MCConstantExpr::create(-1, Context)));
334     break;
335   case Hexagon::SA1_dec:
336     MI.insert(MI.begin() + 2,
337               MCOperand::createExpr(MCConstantExpr::create(-1, Context)));
338     break;
339   default:
340     break;
341   }
342 }
343 
344 DecodeStatus HexagonDisassembler::getSingleInstruction(
345     MCInst &MI, MCInst &MCB, ArrayRef<uint8_t> Bytes, uint64_t Address,
346     raw_ostream &os, raw_ostream &cs, bool &Complete) const {
347   assert(Bytes.size() >= HEXAGON_INSTR_SIZE);
348 
349   uint32_t Instruction = support::endian::read32le(Bytes.data());
350 
351   auto BundleSize = HexagonMCInstrInfo::bundleSize(MCB);
352   if ((Instruction & HexagonII::INST_PARSE_MASK) ==
353       HexagonII::INST_PARSE_LOOP_END) {
354     if (BundleSize == 0)
355       HexagonMCInstrInfo::setInnerLoop(MCB);
356     else if (BundleSize == 1)
357       HexagonMCInstrInfo::setOuterLoop(MCB);
358     else
359       return DecodeStatus::Fail;
360   }
361 
362   CurrentExtender = HexagonMCInstrInfo::extenderForIndex(
363       MCB, HexagonMCInstrInfo::bundleSize(MCB));
364 
365   DecodeStatus Result = DecodeStatus::Fail;
366   if ((Instruction & HexagonII::INST_PARSE_MASK) ==
367       HexagonII::INST_PARSE_DUPLEX) {
368     unsigned duplexIClass;
369     uint8_t const *DecodeLow, *DecodeHigh;
370     duplexIClass = ((Instruction >> 28) & 0xe) | ((Instruction >> 13) & 0x1);
371     switch (duplexIClass) {
372     default:
373       return MCDisassembler::Fail;
374     case 0:
375       DecodeLow = DecoderTableSUBINSN_L132;
376       DecodeHigh = DecoderTableSUBINSN_L132;
377       break;
378     case 1:
379       DecodeLow = DecoderTableSUBINSN_L232;
380       DecodeHigh = DecoderTableSUBINSN_L132;
381       break;
382     case 2:
383       DecodeLow = DecoderTableSUBINSN_L232;
384       DecodeHigh = DecoderTableSUBINSN_L232;
385       break;
386     case 3:
387       DecodeLow = DecoderTableSUBINSN_A32;
388       DecodeHigh = DecoderTableSUBINSN_A32;
389       break;
390     case 4:
391       DecodeLow = DecoderTableSUBINSN_L132;
392       DecodeHigh = DecoderTableSUBINSN_A32;
393       break;
394     case 5:
395       DecodeLow = DecoderTableSUBINSN_L232;
396       DecodeHigh = DecoderTableSUBINSN_A32;
397       break;
398     case 6:
399       DecodeLow = DecoderTableSUBINSN_S132;
400       DecodeHigh = DecoderTableSUBINSN_A32;
401       break;
402     case 7:
403       DecodeLow = DecoderTableSUBINSN_S232;
404       DecodeHigh = DecoderTableSUBINSN_A32;
405       break;
406     case 8:
407       DecodeLow = DecoderTableSUBINSN_S132;
408       DecodeHigh = DecoderTableSUBINSN_L132;
409       break;
410     case 9:
411       DecodeLow = DecoderTableSUBINSN_S132;
412       DecodeHigh = DecoderTableSUBINSN_L232;
413       break;
414     case 10:
415       DecodeLow = DecoderTableSUBINSN_S132;
416       DecodeHigh = DecoderTableSUBINSN_S132;
417       break;
418     case 11:
419       DecodeLow = DecoderTableSUBINSN_S232;
420       DecodeHigh = DecoderTableSUBINSN_S132;
421       break;
422     case 12:
423       DecodeLow = DecoderTableSUBINSN_S232;
424       DecodeHigh = DecoderTableSUBINSN_L132;
425       break;
426     case 13:
427       DecodeLow = DecoderTableSUBINSN_S232;
428       DecodeHigh = DecoderTableSUBINSN_L232;
429       break;
430     case 14:
431       DecodeLow = DecoderTableSUBINSN_S232;
432       DecodeHigh = DecoderTableSUBINSN_S232;
433       break;
434     }
435     MI.setOpcode(Hexagon::DuplexIClass0 + duplexIClass);
436     MCInst *MILow = new (getContext()) MCInst;
437     MCInst *MIHigh = new (getContext()) MCInst;
438     auto TmpExtender = CurrentExtender;
439     CurrentExtender =
440         nullptr; // constant extenders in duplex must always be in slot 1
441     Result = decodeInstruction(DecodeLow, *MILow, Instruction & 0x1fff, Address,
442                                this, STI);
443     CurrentExtender = TmpExtender;
444     if (Result != DecodeStatus::Success)
445       return DecodeStatus::Fail;
446     adjustDuplex(*MILow, getContext());
447     Result = decodeInstruction(
448         DecodeHigh, *MIHigh, (Instruction >> 16) & 0x1fff, Address, this, STI);
449     if (Result != DecodeStatus::Success)
450       return DecodeStatus::Fail;
451     adjustDuplex(*MIHigh, getContext());
452     MCOperand OPLow = MCOperand::createInst(MILow);
453     MCOperand OPHigh = MCOperand::createInst(MIHigh);
454     MI.addOperand(OPLow);
455     MI.addOperand(OPHigh);
456     Complete = true;
457   } else {
458     if ((Instruction & HexagonII::INST_PARSE_MASK) ==
459         HexagonII::INST_PARSE_PACKET_END)
460       Complete = true;
461 
462     if (CurrentExtender != nullptr)
463       Result = decodeInstruction(DecoderTableMustExtend32, MI, Instruction,
464                                  Address, this, STI);
465 
466     if (Result != MCDisassembler::Success)
467       Result = decodeInstruction(DecoderTable32, MI, Instruction, Address, this,
468                                  STI);
469 
470     if (Result != MCDisassembler::Success &&
471         STI.getFeatureBits()[Hexagon::ExtensionHVX])
472       Result = decodeInstruction(DecoderTableEXT_mmvec32, MI, Instruction,
473                                  Address, this, STI);
474 
475   }
476 
477   switch (MI.getOpcode()) {
478   case Hexagon::J4_cmpeqn1_f_jumpnv_nt:
479   case Hexagon::J4_cmpeqn1_f_jumpnv_t:
480   case Hexagon::J4_cmpeqn1_fp0_jump_nt:
481   case Hexagon::J4_cmpeqn1_fp0_jump_t:
482   case Hexagon::J4_cmpeqn1_fp1_jump_nt:
483   case Hexagon::J4_cmpeqn1_fp1_jump_t:
484   case Hexagon::J4_cmpeqn1_t_jumpnv_nt:
485   case Hexagon::J4_cmpeqn1_t_jumpnv_t:
486   case Hexagon::J4_cmpeqn1_tp0_jump_nt:
487   case Hexagon::J4_cmpeqn1_tp0_jump_t:
488   case Hexagon::J4_cmpeqn1_tp1_jump_nt:
489   case Hexagon::J4_cmpeqn1_tp1_jump_t:
490   case Hexagon::J4_cmpgtn1_f_jumpnv_nt:
491   case Hexagon::J4_cmpgtn1_f_jumpnv_t:
492   case Hexagon::J4_cmpgtn1_fp0_jump_nt:
493   case Hexagon::J4_cmpgtn1_fp0_jump_t:
494   case Hexagon::J4_cmpgtn1_fp1_jump_nt:
495   case Hexagon::J4_cmpgtn1_fp1_jump_t:
496   case Hexagon::J4_cmpgtn1_t_jumpnv_nt:
497   case Hexagon::J4_cmpgtn1_t_jumpnv_t:
498   case Hexagon::J4_cmpgtn1_tp0_jump_nt:
499   case Hexagon::J4_cmpgtn1_tp0_jump_t:
500   case Hexagon::J4_cmpgtn1_tp1_jump_nt:
501   case Hexagon::J4_cmpgtn1_tp1_jump_t:
502     MI.insert(MI.begin() + 1,
503               MCOperand::createExpr(MCConstantExpr::create(-1, getContext())));
504     break;
505   default:
506     break;
507   }
508 
509   if (HexagonMCInstrInfo::isNewValue(*MCII, MI)) {
510     unsigned OpIndex = HexagonMCInstrInfo::getNewValueOp(*MCII, MI);
511     MCOperand &MCO = MI.getOperand(OpIndex);
512     assert(MCO.isReg() && "New value consumers must be registers");
513     unsigned Register =
514         getContext().getRegisterInfo()->getEncodingValue(MCO.getReg());
515     if ((Register & 0x6) == 0)
516       // HexagonPRM 10.11 Bit 1-2 == 0 is reserved
517       return MCDisassembler::Fail;
518     unsigned Lookback = (Register & 0x6) >> 1;
519     unsigned Offset = 1;
520     bool Vector = HexagonMCInstrInfo::isVector(*MCII, MI);
521     bool PrevVector = false;
522     auto Instructions = HexagonMCInstrInfo::bundleInstructions(**CurrentBundle);
523     auto i = Instructions.end() - 1;
524     for (auto n = Instructions.begin() - 1;; --i, ++Offset) {
525       if (i == n)
526         // Couldn't find producer
527         return MCDisassembler::Fail;
528       bool CurrentVector = HexagonMCInstrInfo::isVector(*MCII, *i->getInst());
529       if (Vector && !CurrentVector)
530         // Skip scalars when calculating distances for vectors
531         ++Lookback;
532       if (HexagonMCInstrInfo::isImmext(*i->getInst()) && (Vector == PrevVector))
533         ++Lookback;
534       PrevVector = CurrentVector;
535       if (Offset == Lookback)
536         break;
537     }
538     auto const &Inst = *i->getInst();
539     bool SubregBit = (Register & 0x1) != 0;
540     if (HexagonMCInstrInfo::hasNewValue2(*MCII, Inst)) {
541       // If subreg bit is set we're selecting the second produced newvalue
542       unsigned Producer = SubregBit ?
543           HexagonMCInstrInfo::getNewValueOperand(*MCII, Inst).getReg() :
544           HexagonMCInstrInfo::getNewValueOperand2(*MCII, Inst).getReg();
545       assert(Producer != Hexagon::NoRegister);
546       MCO.setReg(Producer);
547     } else if (HexagonMCInstrInfo::hasNewValue(*MCII, Inst)) {
548       unsigned Producer =
549           HexagonMCInstrInfo::getNewValueOperand(*MCII, Inst).getReg();
550       if (Producer >= Hexagon::W0 && Producer <= Hexagon::W15)
551         Producer = ((Producer - Hexagon::W0) << 1) + SubregBit + Hexagon::V0;
552       else if (SubregBit)
553         // Hexagon PRM 10.11 New-value operands
554         // Nt[0] is reserved and should always be encoded as zero.
555         return MCDisassembler::Fail;
556       assert(Producer != Hexagon::NoRegister);
557       MCO.setReg(Producer);
558     } else
559       return MCDisassembler::Fail;
560   }
561 
562   if (CurrentExtender != nullptr) {
563     MCInst const &Inst = HexagonMCInstrInfo::isDuplex(*MCII, MI)
564                              ? *MI.getOperand(1).getInst()
565                              : MI;
566     if (!HexagonMCInstrInfo::isExtendable(*MCII, Inst) &&
567         !HexagonMCInstrInfo::isExtended(*MCII, Inst))
568       return MCDisassembler::Fail;
569   }
570   return Result;
571 }
572 
573 static DecodeStatus DecodeRegisterClass(MCInst &Inst, unsigned RegNo,
574                                         ArrayRef<MCPhysReg> Table) {
575   if (RegNo < Table.size()) {
576     Inst.addOperand(MCOperand::createReg(Table[RegNo]));
577     return MCDisassembler::Success;
578   }
579 
580   return MCDisassembler::Fail;
581 }
582 
583 static DecodeStatus DecodeIntRegsLow8RegisterClass(MCInst &Inst, unsigned RegNo,
584                                                    uint64_t Address,
585                                                    const void *Decoder) {
586   return DecodeIntRegsRegisterClass(Inst, RegNo, Address, Decoder);
587 }
588 
589 static DecodeStatus DecodeIntRegsRegisterClass(MCInst &Inst, unsigned RegNo,
590                                                uint64_t Address,
591                                                const void *Decoder) {
592   static const MCPhysReg IntRegDecoderTable[] = {
593       Hexagon::R0,  Hexagon::R1,  Hexagon::R2,  Hexagon::R3,  Hexagon::R4,
594       Hexagon::R5,  Hexagon::R6,  Hexagon::R7,  Hexagon::R8,  Hexagon::R9,
595       Hexagon::R10, Hexagon::R11, Hexagon::R12, Hexagon::R13, Hexagon::R14,
596       Hexagon::R15, Hexagon::R16, Hexagon::R17, Hexagon::R18, Hexagon::R19,
597       Hexagon::R20, Hexagon::R21, Hexagon::R22, Hexagon::R23, Hexagon::R24,
598       Hexagon::R25, Hexagon::R26, Hexagon::R27, Hexagon::R28, Hexagon::R29,
599       Hexagon::R30, Hexagon::R31};
600 
601   return DecodeRegisterClass(Inst, RegNo, IntRegDecoderTable);
602 }
603 
604 static DecodeStatus DecodeGeneralSubRegsRegisterClass(MCInst &Inst,
605                                                       unsigned RegNo,
606                                                       uint64_t Address,
607                                                       const void *Decoder) {
608   static const MCPhysReg GeneralSubRegDecoderTable[] = {
609       Hexagon::R0,  Hexagon::R1,  Hexagon::R2,  Hexagon::R3,
610       Hexagon::R4,  Hexagon::R5,  Hexagon::R6,  Hexagon::R7,
611       Hexagon::R16, Hexagon::R17, Hexagon::R18, Hexagon::R19,
612       Hexagon::R20, Hexagon::R21, Hexagon::R22, Hexagon::R23,
613   };
614 
615   return DecodeRegisterClass(Inst, RegNo, GeneralSubRegDecoderTable);
616 }
617 
618 static DecodeStatus DecodeHvxVRRegisterClass(MCInst &Inst, unsigned RegNo,
619                                              uint64_t /*Address*/,
620                                              const void *Decoder) {
621   static const MCPhysReg HvxVRDecoderTable[] = {
622       Hexagon::V0,  Hexagon::V1,  Hexagon::V2,  Hexagon::V3,  Hexagon::V4,
623       Hexagon::V5,  Hexagon::V6,  Hexagon::V7,  Hexagon::V8,  Hexagon::V9,
624       Hexagon::V10, Hexagon::V11, Hexagon::V12, Hexagon::V13, Hexagon::V14,
625       Hexagon::V15, Hexagon::V16, Hexagon::V17, Hexagon::V18, Hexagon::V19,
626       Hexagon::V20, Hexagon::V21, Hexagon::V22, Hexagon::V23, Hexagon::V24,
627       Hexagon::V25, Hexagon::V26, Hexagon::V27, Hexagon::V28, Hexagon::V29,
628       Hexagon::V30, Hexagon::V31};
629 
630   return DecodeRegisterClass(Inst, RegNo, HvxVRDecoderTable);
631 }
632 
633 static DecodeStatus DecodeDoubleRegsRegisterClass(MCInst &Inst, unsigned RegNo,
634                                                   uint64_t /*Address*/,
635                                                   const void *Decoder) {
636   static const MCPhysReg DoubleRegDecoderTable[] = {
637       Hexagon::D0,  Hexagon::D1,  Hexagon::D2,  Hexagon::D3,
638       Hexagon::D4,  Hexagon::D5,  Hexagon::D6,  Hexagon::D7,
639       Hexagon::D8,  Hexagon::D9,  Hexagon::D10, Hexagon::D11,
640       Hexagon::D12, Hexagon::D13, Hexagon::D14, Hexagon::D15};
641 
642   return DecodeRegisterClass(Inst, RegNo >> 1, DoubleRegDecoderTable);
643 }
644 
645 static DecodeStatus DecodeGeneralDoubleLow8RegsRegisterClass(
646     MCInst &Inst, unsigned RegNo, uint64_t /*Address*/, const void *Decoder) {
647   static const MCPhysReg GeneralDoubleLow8RegDecoderTable[] = {
648       Hexagon::D0, Hexagon::D1, Hexagon::D2,  Hexagon::D3,
649       Hexagon::D8, Hexagon::D9, Hexagon::D10, Hexagon::D11};
650 
651   return DecodeRegisterClass(Inst, RegNo, GeneralDoubleLow8RegDecoderTable);
652 }
653 
654 static DecodeStatus DecodeHvxWRRegisterClass(MCInst &Inst, unsigned RegNo,
655                                              uint64_t /*Address*/,
656                                              const void *Decoder) {
657   static const MCPhysReg HvxWRDecoderTable[] = {
658       Hexagon::W0,  Hexagon::W1,  Hexagon::W2,  Hexagon::W3,
659       Hexagon::W4,  Hexagon::W5,  Hexagon::W6,  Hexagon::W7,
660       Hexagon::W8,  Hexagon::W9,  Hexagon::W10, Hexagon::W11,
661       Hexagon::W12, Hexagon::W13, Hexagon::W14, Hexagon::W15};
662 
663   return (DecodeRegisterClass(Inst, RegNo >> 1, HvxWRDecoderTable));
664 }
665 
666 static DecodeStatus DecodePredRegsRegisterClass(MCInst &Inst, unsigned RegNo,
667                                                 uint64_t /*Address*/,
668                                                 const void *Decoder) {
669   static const MCPhysReg PredRegDecoderTable[] = {Hexagon::P0, Hexagon::P1,
670                                                   Hexagon::P2, Hexagon::P3};
671 
672   return DecodeRegisterClass(Inst, RegNo, PredRegDecoderTable);
673 }
674 
675 static DecodeStatus DecodeHvxQRRegisterClass(MCInst &Inst, unsigned RegNo,
676                                              uint64_t /*Address*/,
677                                              const void *Decoder) {
678   static const MCPhysReg HvxQRDecoderTable[] = {Hexagon::Q0, Hexagon::Q1,
679                                                 Hexagon::Q2, Hexagon::Q3};
680 
681   return DecodeRegisterClass(Inst, RegNo, HvxQRDecoderTable);
682 }
683 
684 static DecodeStatus DecodeCtrRegsRegisterClass(MCInst &Inst, unsigned RegNo,
685                                                uint64_t /*Address*/,
686                                                const void *Decoder) {
687   using namespace Hexagon;
688 
689   static const MCPhysReg CtrlRegDecoderTable[] = {
690     /*  0 */  SA0,        LC0,        SA1,        LC1,
691     /*  4 */  P3_0,       C5,         M0,         M1,
692     /*  8 */  USR,        PC,         UGP,        GP,
693     /* 12 */  CS0,        CS1,        UPCYCLELO,  UPCYCLEHI,
694     /* 16 */  FRAMELIMIT, FRAMEKEY,   PKTCOUNTLO, PKTCOUNTHI,
695     /* 20 */  0,          0,          0,          0,
696     /* 24 */  0,          0,          0,          0,
697     /* 28 */  0,          0,          UTIMERLO,   UTIMERHI
698   };
699 
700   if (RegNo >= array_lengthof(CtrlRegDecoderTable))
701     return MCDisassembler::Fail;
702 
703   static_assert(NoRegister == 0, "Expecting NoRegister to be 0");
704   if (CtrlRegDecoderTable[RegNo] == NoRegister)
705     return MCDisassembler::Fail;
706 
707   unsigned Register = CtrlRegDecoderTable[RegNo];
708   Inst.addOperand(MCOperand::createReg(Register));
709   return MCDisassembler::Success;
710 }
711 
712 static DecodeStatus DecodeCtrRegs64RegisterClass(MCInst &Inst, unsigned RegNo,
713                                                  uint64_t /*Address*/,
714                                                  const void *Decoder) {
715   using namespace Hexagon;
716 
717   static const MCPhysReg CtrlReg64DecoderTable[] = {
718     /*  0 */  C1_0,       0,          C3_2,       0,
719     /*  4 */  C5_4,       0,          C7_6,       0,
720     /*  8 */  C9_8,       0,          C11_10,     0,
721     /* 12 */  CS,         0,          UPCYCLE,    0,
722     /* 16 */  C17_16,     0,          PKTCOUNT,   0,
723     /* 20 */  0,          0,          0,          0,
724     /* 24 */  0,          0,          0,          0,
725     /* 28 */  0,          0,          UTIMER,     0
726   };
727 
728   if (RegNo >= array_lengthof(CtrlReg64DecoderTable))
729     return MCDisassembler::Fail;
730 
731   static_assert(NoRegister == 0, "Expecting NoRegister to be 0");
732   if (CtrlReg64DecoderTable[RegNo] == NoRegister)
733     return MCDisassembler::Fail;
734 
735   unsigned Register = CtrlReg64DecoderTable[RegNo];
736   Inst.addOperand(MCOperand::createReg(Register));
737   return MCDisassembler::Success;
738 }
739 
740 static DecodeStatus DecodeModRegsRegisterClass(MCInst &Inst, unsigned RegNo,
741                                                uint64_t /*Address*/,
742                                                const void *Decoder) {
743   unsigned Register = 0;
744   switch (RegNo) {
745   case 0:
746     Register = Hexagon::M0;
747     break;
748   case 1:
749     Register = Hexagon::M1;
750     break;
751   default:
752     return MCDisassembler::Fail;
753   }
754   Inst.addOperand(MCOperand::createReg(Register));
755   return MCDisassembler::Success;
756 }
757 
758 static DecodeStatus unsignedImmDecoder(MCInst &MI, unsigned tmp,
759                                        uint64_t /*Address*/,
760                                        const void *Decoder) {
761   HexagonDisassembler const &Disassembler = disassembler(Decoder);
762   int64_t FullValue = fullValue(Disassembler, MI, tmp);
763   assert(FullValue >= 0 && "Negative in unsigned decoder");
764   HexagonMCInstrInfo::addConstant(MI, FullValue, Disassembler.getContext());
765   return MCDisassembler::Success;
766 }
767 
768 static DecodeStatus s32_0ImmDecoder(MCInst &MI, unsigned tmp,
769                                     uint64_t /*Address*/, const void *Decoder) {
770   HexagonDisassembler const &Disassembler = disassembler(Decoder);
771   unsigned Bits = HexagonMCInstrInfo::getExtentBits(*Disassembler.MCII, MI);
772   tmp = SignExtend64(tmp, Bits);
773   signedDecoder<32>(MI, tmp, Decoder);
774   return MCDisassembler::Success;
775 }
776 
777 // custom decoder for various jump/call immediates
778 static DecodeStatus brtargetDecoder(MCInst &MI, unsigned tmp, uint64_t Address,
779                                     const void *Decoder) {
780   HexagonDisassembler const &Disassembler = disassembler(Decoder);
781   unsigned Bits = HexagonMCInstrInfo::getExtentBits(*Disassembler.MCII, MI);
782   // r13_2 is not extendable, so if there are no extent bits, it's r13_2
783   if (Bits == 0)
784     Bits = 15;
785   uint64_t FullValue = fullValue(Disassembler, MI, SignExtend64(tmp, Bits));
786   uint32_t Extended = FullValue + Address;
787   if (!Disassembler.tryAddingSymbolicOperand(MI, Extended, Address, true, 0, 4))
788     HexagonMCInstrInfo::addConstant(MI, Extended, Disassembler.getContext());
789   return MCDisassembler::Success;
790 }
791 
792 static DecodeStatus DecodeGuestRegsRegisterClass(MCInst &Inst, unsigned RegNo,
793                                                  uint64_t /*Address*/,
794                                                  const void *Decoder) {
795   using namespace Hexagon;
796 
797   static const MCPhysReg GuestRegDecoderTable[] = {
798     /*  0 */ GELR,      GSR,        GOSP,       G3,
799     /*  4 */ G4,        G5,         G6,         G7,
800     /*  8 */ G8,        G9,         G10,        G11,
801     /* 12 */ G12,       G13,        G14,        G15,
802     /* 16 */ GPMUCNT4,  GPMUCNT5,   GPMUCNT6,   GPMUCNT7,
803     /* 20 */ G20,       G21,        G22,        G23,
804     /* 24 */ GPCYCLELO, GPCYCLEHI,  GPMUCNT0,   GPMUCNT1,
805     /* 28 */ GPMUCNT2,  GPMUCNT3,   G30,        G31
806   };
807 
808   if (RegNo >= array_lengthof(GuestRegDecoderTable))
809     return MCDisassembler::Fail;
810   if (GuestRegDecoderTable[RegNo] == Hexagon::NoRegister)
811     return MCDisassembler::Fail;
812 
813   unsigned Register = GuestRegDecoderTable[RegNo];
814   Inst.addOperand(MCOperand::createReg(Register));
815   return MCDisassembler::Success;
816 }
817 
818 static DecodeStatus DecodeGuestRegs64RegisterClass(MCInst &Inst, unsigned RegNo,
819                                                    uint64_t /*Address*/,
820                                                    const void *Decoder) {
821   using namespace Hexagon;
822 
823   static const MCPhysReg GuestReg64DecoderTable[] = {
824     /*  0 */ G1_0,      0,          G3_2,       0,
825     /*  4 */ G5_4,      0,          G7_6,       0,
826     /*  8 */ G9_8,      0,          G11_10,     0,
827     /* 12 */ G13_12,    0,          G15_14,     0,
828     /* 16 */ G17_16,    0,          G19_18,     0,
829     /* 20 */ G21_20,    0,          G23_22,     0,
830     /* 24 */ G25_24,    0,          G27_26,     0,
831     /* 28 */ G29_28,    0,          G31_30,     0
832   };
833 
834   if (RegNo >= array_lengthof(GuestReg64DecoderTable))
835     return MCDisassembler::Fail;
836   if (GuestReg64DecoderTable[RegNo] == Hexagon::NoRegister)
837     return MCDisassembler::Fail;
838 
839   unsigned Register = GuestReg64DecoderTable[RegNo];
840   Inst.addOperand(MCOperand::createReg(Register));
841   return MCDisassembler::Success;
842 }
843