1 //===- MipsDisassembler.cpp - Disassembler for Mips -------------*- 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 // This file is part of the Mips Disassembler.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "Mips.h"
15 #include "MipsRegisterInfo.h"
16 #include "MipsSubtarget.h"
17 #include "llvm/MC/MCContext.h"
18 #include "llvm/MC/MCDisassembler.h"
19 #include "llvm/MC/MCFixedLenDisassembler.h"
20 #include "llvm/MC/MCInst.h"
21 #include "llvm/MC/MCSubtargetInfo.h"
22 #include "llvm/Support/MathExtras.h"
23 #include "llvm/Support/TargetRegistry.h"
24 
25 using namespace llvm;
26 
27 #define DEBUG_TYPE "mips-disassembler"
28 
29 typedef MCDisassembler::DecodeStatus DecodeStatus;
30 
31 namespace {
32 
33 /// A disasembler class for Mips.
34 class MipsDisassemblerBase : public MCDisassembler {
35 public:
36   MipsDisassemblerBase(const MCSubtargetInfo &STI, MCContext &Ctx,
37                        bool IsBigEndian)
38       : MCDisassembler(STI, Ctx),
39         IsGP64Bit(STI.getFeatureBits() & Mips::FeatureGP64Bit),
40         IsBigEndian(IsBigEndian) {}
41 
42   virtual ~MipsDisassemblerBase() {}
43 
44   bool isGP64Bit() const { return IsGP64Bit; }
45 
46 private:
47   bool IsGP64Bit;
48 protected:
49   bool IsBigEndian;
50 };
51 
52 /// A disasembler class for Mips32.
53 class MipsDisassembler : public MipsDisassemblerBase {
54   bool IsMicroMips;
55 public:
56   MipsDisassembler(const MCSubtargetInfo &STI, MCContext &Ctx, bool bigEndian)
57       : MipsDisassemblerBase(STI, Ctx, bigEndian) {
58     IsMicroMips = STI.getFeatureBits() & Mips::FeatureMicroMips;
59   }
60 
61   bool hasMips3() const { return STI.getFeatureBits() & Mips::FeatureMips3; }
62   bool hasMips32() const { return STI.getFeatureBits() & Mips::FeatureMips32; }
63   bool hasMips32r6() const {
64     return STI.getFeatureBits() & Mips::FeatureMips32r6;
65   }
66 
67   bool isGP64() const { return STI.getFeatureBits() & Mips::FeatureGP64Bit; }
68 
69   bool hasCOP3() const {
70     // Only present in MIPS-I and MIPS-II
71     return !hasMips32() && !hasMips3();
72   }
73 
74   DecodeStatus getInstruction(MCInst &Instr, uint64_t &Size,
75                               ArrayRef<uint8_t> Bytes, uint64_t Address,
76                               raw_ostream &VStream,
77                               raw_ostream &CStream) const override;
78 };
79 
80 /// A disasembler class for Mips64.
81 class Mips64Disassembler : public MipsDisassemblerBase {
82 public:
83   Mips64Disassembler(const MCSubtargetInfo &STI, MCContext &Ctx,
84                      bool bigEndian) :
85     MipsDisassemblerBase(STI, Ctx, bigEndian) {}
86 
87   DecodeStatus getInstruction(MCInst &Instr, uint64_t &Size,
88                               ArrayRef<uint8_t> Bytes, uint64_t Address,
89                               raw_ostream &VStream,
90                               raw_ostream &CStream) const override;
91 };
92 
93 } // end anonymous namespace
94 
95 // Forward declare these because the autogenerated code will reference them.
96 // Definitions are further down.
97 static DecodeStatus DecodeGPR64RegisterClass(MCInst &Inst,
98                                              unsigned RegNo,
99                                              uint64_t Address,
100                                              const void *Decoder);
101 
102 static DecodeStatus DecodeCPU16RegsRegisterClass(MCInst &Inst,
103                                                  unsigned RegNo,
104                                                  uint64_t Address,
105                                                  const void *Decoder);
106 
107 static DecodeStatus DecodeGPRMM16RegisterClass(MCInst &Inst,
108                                                unsigned RegNo,
109                                                uint64_t Address,
110                                                const void *Decoder);
111 
112 static DecodeStatus DecodeGPRMM16ZeroRegisterClass(MCInst &Inst,
113                                                    unsigned RegNo,
114                                                    uint64_t Address,
115                                                    const void *Decoder);
116 
117 static DecodeStatus DecodeGPR32RegisterClass(MCInst &Inst,
118                                              unsigned RegNo,
119                                              uint64_t Address,
120                                              const void *Decoder);
121 
122 static DecodeStatus DecodePtrRegisterClass(MCInst &Inst,
123                                            unsigned Insn,
124                                            uint64_t Address,
125                                            const void *Decoder);
126 
127 static DecodeStatus DecodeDSPRRegisterClass(MCInst &Inst,
128                                             unsigned RegNo,
129                                             uint64_t Address,
130                                             const void *Decoder);
131 
132 static DecodeStatus DecodeFGR64RegisterClass(MCInst &Inst,
133                                              unsigned RegNo,
134                                              uint64_t Address,
135                                              const void *Decoder);
136 
137 static DecodeStatus DecodeFGR32RegisterClass(MCInst &Inst,
138                                              unsigned RegNo,
139                                              uint64_t Address,
140                                              const void *Decoder);
141 
142 static DecodeStatus DecodeCCRRegisterClass(MCInst &Inst,
143                                            unsigned RegNo,
144                                            uint64_t Address,
145                                            const void *Decoder);
146 
147 static DecodeStatus DecodeFCCRegisterClass(MCInst &Inst,
148                                            unsigned RegNo,
149                                            uint64_t Address,
150                                            const void *Decoder);
151 
152 static DecodeStatus DecodeFGRCCRegisterClass(MCInst &Inst, unsigned RegNo,
153                                              uint64_t Address,
154                                              const void *Decoder);
155 
156 static DecodeStatus DecodeHWRegsRegisterClass(MCInst &Inst,
157                                               unsigned Insn,
158                                               uint64_t Address,
159                                               const void *Decoder);
160 
161 static DecodeStatus DecodeAFGR64RegisterClass(MCInst &Inst,
162                                               unsigned RegNo,
163                                               uint64_t Address,
164                                               const void *Decoder);
165 
166 static DecodeStatus DecodeACC64DSPRegisterClass(MCInst &Inst,
167                                                 unsigned RegNo,
168                                                 uint64_t Address,
169                                                 const void *Decoder);
170 
171 static DecodeStatus DecodeHI32DSPRegisterClass(MCInst &Inst,
172                                                unsigned RegNo,
173                                                uint64_t Address,
174                                                const void *Decoder);
175 
176 static DecodeStatus DecodeLO32DSPRegisterClass(MCInst &Inst,
177                                                unsigned RegNo,
178                                                uint64_t Address,
179                                                const void *Decoder);
180 
181 static DecodeStatus DecodeMSA128BRegisterClass(MCInst &Inst,
182                                                unsigned RegNo,
183                                                uint64_t Address,
184                                                const void *Decoder);
185 
186 static DecodeStatus DecodeMSA128HRegisterClass(MCInst &Inst,
187                                                unsigned RegNo,
188                                                uint64_t Address,
189                                                const void *Decoder);
190 
191 static DecodeStatus DecodeMSA128WRegisterClass(MCInst &Inst,
192                                                unsigned RegNo,
193                                                uint64_t Address,
194                                                const void *Decoder);
195 
196 static DecodeStatus DecodeMSA128DRegisterClass(MCInst &Inst,
197                                                unsigned RegNo,
198                                                uint64_t Address,
199                                                const void *Decoder);
200 
201 static DecodeStatus DecodeMSACtrlRegisterClass(MCInst &Inst,
202                                                unsigned RegNo,
203                                                uint64_t Address,
204                                                const void *Decoder);
205 
206 static DecodeStatus DecodeCOP2RegisterClass(MCInst &Inst,
207                                             unsigned RegNo,
208                                             uint64_t Address,
209                                             const void *Decoder);
210 
211 static DecodeStatus DecodeBranchTarget(MCInst &Inst,
212                                        unsigned Offset,
213                                        uint64_t Address,
214                                        const void *Decoder);
215 
216 static DecodeStatus DecodeJumpTarget(MCInst &Inst,
217                                      unsigned Insn,
218                                      uint64_t Address,
219                                      const void *Decoder);
220 
221 static DecodeStatus DecodeBranchTarget21(MCInst &Inst,
222                                          unsigned Offset,
223                                          uint64_t Address,
224                                          const void *Decoder);
225 
226 static DecodeStatus DecodeBranchTarget26(MCInst &Inst,
227                                          unsigned Offset,
228                                          uint64_t Address,
229                                          const void *Decoder);
230 
231 // DecodeBranchTarget7MM - Decode microMIPS branch offset, which is
232 // shifted left by 1 bit.
233 static DecodeStatus DecodeBranchTarget7MM(MCInst &Inst,
234                                           unsigned Offset,
235                                           uint64_t Address,
236                                           const void *Decoder);
237 
238 // DecodeBranchTarget10MM - Decode microMIPS branch offset, which is
239 // shifted left by 1 bit.
240 static DecodeStatus DecodeBranchTarget10MM(MCInst &Inst,
241                                            unsigned Offset,
242                                            uint64_t Address,
243                                            const void *Decoder);
244 
245 // DecodeBranchTargetMM - Decode microMIPS branch offset, which is
246 // shifted left by 1 bit.
247 static DecodeStatus DecodeBranchTargetMM(MCInst &Inst,
248                                          unsigned Offset,
249                                          uint64_t Address,
250                                          const void *Decoder);
251 
252 // DecodeJumpTargetMM - Decode microMIPS jump target, which is
253 // shifted left by 1 bit.
254 static DecodeStatus DecodeJumpTargetMM(MCInst &Inst,
255                                        unsigned Insn,
256                                        uint64_t Address,
257                                        const void *Decoder);
258 
259 static DecodeStatus DecodeMem(MCInst &Inst,
260                               unsigned Insn,
261                               uint64_t Address,
262                               const void *Decoder);
263 
264 static DecodeStatus DecodeCacheOp(MCInst &Inst,
265                               unsigned Insn,
266                               uint64_t Address,
267                               const void *Decoder);
268 
269 static DecodeStatus DecodeCacheOpMM(MCInst &Inst,
270                                     unsigned Insn,
271                                     uint64_t Address,
272                                     const void *Decoder);
273 
274 static DecodeStatus DecodeSyncI(MCInst &Inst,
275                                 unsigned Insn,
276                                 uint64_t Address,
277                                 const void *Decoder);
278 
279 static DecodeStatus DecodeMSA128Mem(MCInst &Inst, unsigned Insn,
280                                     uint64_t Address, const void *Decoder);
281 
282 static DecodeStatus DecodeMemMMImm4(MCInst &Inst,
283                                     unsigned Insn,
284                                     uint64_t Address,
285                                     const void *Decoder);
286 
287 static DecodeStatus DecodeMemMMSPImm5Lsl2(MCInst &Inst,
288                                           unsigned Insn,
289                                           uint64_t Address,
290                                           const void *Decoder);
291 
292 static DecodeStatus DecodeMemMMImm12(MCInst &Inst,
293                                      unsigned Insn,
294                                      uint64_t Address,
295                                      const void *Decoder);
296 
297 static DecodeStatus DecodeMemMMImm16(MCInst &Inst,
298                                      unsigned Insn,
299                                      uint64_t Address,
300                                      const void *Decoder);
301 
302 static DecodeStatus DecodeFMem(MCInst &Inst, unsigned Insn,
303                                uint64_t Address,
304                                const void *Decoder);
305 
306 static DecodeStatus DecodeFMem2(MCInst &Inst, unsigned Insn,
307                                uint64_t Address,
308                                const void *Decoder);
309 
310 static DecodeStatus DecodeFMem3(MCInst &Inst, unsigned Insn,
311                                uint64_t Address,
312                                const void *Decoder);
313 
314 static DecodeStatus DecodeFMemCop2R6(MCInst &Inst, unsigned Insn,
315                                uint64_t Address,
316                                const void *Decoder);
317 
318 static DecodeStatus DecodeSpecial3LlSc(MCInst &Inst,
319                                        unsigned Insn,
320                                        uint64_t Address,
321                                        const void *Decoder);
322 
323 static DecodeStatus DecodeAddiur2Simm7(MCInst &Inst,
324                                        unsigned Value,
325                                        uint64_t Address,
326                                        const void *Decoder);
327 
328 static DecodeStatus DecodeUImm6Lsl2(MCInst &Inst,
329                                     unsigned Value,
330                                     uint64_t Address,
331                                     const void *Decoder);
332 
333 static DecodeStatus DecodeLiSimm7(MCInst &Inst,
334                                   unsigned Value,
335                                   uint64_t Address,
336                                   const void *Decoder);
337 
338 static DecodeStatus DecodeSimm4(MCInst &Inst,
339                                 unsigned Value,
340                                 uint64_t Address,
341                                 const void *Decoder);
342 
343 static DecodeStatus DecodeSimm16(MCInst &Inst,
344                                  unsigned Insn,
345                                  uint64_t Address,
346                                  const void *Decoder);
347 
348 // Decode the immediate field of an LSA instruction which
349 // is off by one.
350 static DecodeStatus DecodeLSAImm(MCInst &Inst,
351                                  unsigned Insn,
352                                  uint64_t Address,
353                                  const void *Decoder);
354 
355 static DecodeStatus DecodeInsSize(MCInst &Inst,
356                                   unsigned Insn,
357                                   uint64_t Address,
358                                   const void *Decoder);
359 
360 static DecodeStatus DecodeExtSize(MCInst &Inst,
361                                   unsigned Insn,
362                                   uint64_t Address,
363                                   const void *Decoder);
364 
365 static DecodeStatus DecodeSimm19Lsl2(MCInst &Inst, unsigned Insn,
366                                      uint64_t Address, const void *Decoder);
367 
368 static DecodeStatus DecodeSimm18Lsl3(MCInst &Inst, unsigned Insn,
369                                      uint64_t Address, const void *Decoder);
370 
371 static DecodeStatus DecodeSimm9SP(MCInst &Inst, unsigned Insn,
372                                   uint64_t Address, const void *Decoder);
373 
374 static DecodeStatus DecodeANDI16Imm(MCInst &Inst, unsigned Insn,
375                                     uint64_t Address, const void *Decoder);
376 
377 static DecodeStatus DecodeUImm5lsl2(MCInst &Inst, unsigned Insn,
378                                    uint64_t Address, const void *Decoder);
379 
380 static DecodeStatus DecodeSimm23Lsl2(MCInst &Inst, unsigned Insn,
381                                      uint64_t Address, const void *Decoder);
382 
383 /// INSVE_[BHWD] have an implicit operand that the generated decoder doesn't
384 /// handle.
385 template <typename InsnType>
386 static DecodeStatus DecodeINSVE_DF(MCInst &MI, InsnType insn, uint64_t Address,
387                                    const void *Decoder);
388 
389 template <typename InsnType>
390 static DecodeStatus
391 DecodeAddiGroupBranch(MCInst &MI, InsnType insn, uint64_t Address,
392                       const void *Decoder);
393 
394 template <typename InsnType>
395 static DecodeStatus
396 DecodeDaddiGroupBranch(MCInst &MI, InsnType insn, uint64_t Address,
397                        const void *Decoder);
398 
399 template <typename InsnType>
400 static DecodeStatus
401 DecodeBlezlGroupBranch(MCInst &MI, InsnType insn, uint64_t Address,
402                        const void *Decoder);
403 
404 template <typename InsnType>
405 static DecodeStatus
406 DecodeBgtzlGroupBranch(MCInst &MI, InsnType insn, uint64_t Address,
407                        const void *Decoder);
408 
409 template <typename InsnType>
410 static DecodeStatus
411 DecodeBgtzGroupBranch(MCInst &MI, InsnType insn, uint64_t Address,
412                       const void *Decoder);
413 
414 template <typename InsnType>
415 static DecodeStatus
416 DecodeBlezGroupBranch(MCInst &MI, InsnType insn, uint64_t Address,
417                        const void *Decoder);
418 
419 static DecodeStatus DecodeRegListOperand(MCInst &Inst, unsigned Insn,
420                                          uint64_t Address,
421                                          const void *Decoder);
422 
423 static DecodeStatus DecodeRegListOperand16(MCInst &Inst, unsigned Insn,
424                                            uint64_t Address,
425                                            const void *Decoder);
426 
427 namespace llvm {
428 extern Target TheMipselTarget, TheMipsTarget, TheMips64Target,
429               TheMips64elTarget;
430 }
431 
432 static MCDisassembler *createMipsDisassembler(
433                        const Target &T,
434                        const MCSubtargetInfo &STI,
435                        MCContext &Ctx) {
436   return new MipsDisassembler(STI, Ctx, true);
437 }
438 
439 static MCDisassembler *createMipselDisassembler(
440                        const Target &T,
441                        const MCSubtargetInfo &STI,
442                        MCContext &Ctx) {
443   return new MipsDisassembler(STI, Ctx, false);
444 }
445 
446 static MCDisassembler *createMips64Disassembler(
447                        const Target &T,
448                        const MCSubtargetInfo &STI,
449                        MCContext &Ctx) {
450   return new Mips64Disassembler(STI, Ctx, true);
451 }
452 
453 static MCDisassembler *createMips64elDisassembler(
454                        const Target &T,
455                        const MCSubtargetInfo &STI,
456                        MCContext &Ctx) {
457   return new Mips64Disassembler(STI, Ctx, false);
458 }
459 
460 extern "C" void LLVMInitializeMipsDisassembler() {
461   // Register the disassembler.
462   TargetRegistry::RegisterMCDisassembler(TheMipsTarget,
463                                          createMipsDisassembler);
464   TargetRegistry::RegisterMCDisassembler(TheMipselTarget,
465                                          createMipselDisassembler);
466   TargetRegistry::RegisterMCDisassembler(TheMips64Target,
467                                          createMips64Disassembler);
468   TargetRegistry::RegisterMCDisassembler(TheMips64elTarget,
469                                          createMips64elDisassembler);
470 }
471 
472 #include "MipsGenDisassemblerTables.inc"
473 
474 static unsigned getReg(const void *D, unsigned RC, unsigned RegNo) {
475   const MipsDisassemblerBase *Dis = static_cast<const MipsDisassemblerBase*>(D);
476   const MCRegisterInfo *RegInfo = Dis->getContext().getRegisterInfo();
477   return *(RegInfo->getRegClass(RC).begin() + RegNo);
478 }
479 
480 template <typename InsnType>
481 static DecodeStatus DecodeINSVE_DF(MCInst &MI, InsnType insn, uint64_t Address,
482                                    const void *Decoder) {
483   typedef DecodeStatus (*DecodeFN)(MCInst &, unsigned, uint64_t, const void *);
484   // The size of the n field depends on the element size
485   // The register class also depends on this.
486   InsnType tmp = fieldFromInstruction(insn, 17, 5);
487   unsigned NSize = 0;
488   DecodeFN RegDecoder = nullptr;
489   if ((tmp & 0x18) == 0x00) { // INSVE_B
490     NSize = 4;
491     RegDecoder = DecodeMSA128BRegisterClass;
492   } else if ((tmp & 0x1c) == 0x10) { // INSVE_H
493     NSize = 3;
494     RegDecoder = DecodeMSA128HRegisterClass;
495   } else if ((tmp & 0x1e) == 0x18) { // INSVE_W
496     NSize = 2;
497     RegDecoder = DecodeMSA128WRegisterClass;
498   } else if ((tmp & 0x1f) == 0x1c) { // INSVE_D
499     NSize = 1;
500     RegDecoder = DecodeMSA128DRegisterClass;
501   } else
502     llvm_unreachable("Invalid encoding");
503 
504   assert(NSize != 0 && RegDecoder != nullptr);
505 
506   // $wd
507   tmp = fieldFromInstruction(insn, 6, 5);
508   if (RegDecoder(MI, tmp, Address, Decoder) == MCDisassembler::Fail)
509     return MCDisassembler::Fail;
510   // $wd_in
511   if (RegDecoder(MI, tmp, Address, Decoder) == MCDisassembler::Fail)
512     return MCDisassembler::Fail;
513   // $n
514   tmp = fieldFromInstruction(insn, 16, NSize);
515   MI.addOperand(MCOperand::CreateImm(tmp));
516   // $ws
517   tmp = fieldFromInstruction(insn, 11, 5);
518   if (RegDecoder(MI, tmp, Address, Decoder) == MCDisassembler::Fail)
519     return MCDisassembler::Fail;
520   // $n2
521   MI.addOperand(MCOperand::CreateImm(0));
522 
523   return MCDisassembler::Success;
524 }
525 
526 template <typename InsnType>
527 static DecodeStatus DecodeAddiGroupBranch(MCInst &MI, InsnType insn,
528                                           uint64_t Address,
529                                           const void *Decoder) {
530   // If we are called then we can assume that MIPS32r6/MIPS64r6 is enabled
531   // (otherwise we would have matched the ADDI instruction from the earlier
532   // ISA's instead).
533   //
534   // We have:
535   //    0b001000 sssss ttttt iiiiiiiiiiiiiiii
536   //      BOVC if rs >= rt
537   //      BEQZALC if rs == 0 && rt != 0
538   //      BEQC if rs < rt && rs != 0
539 
540   InsnType Rs = fieldFromInstruction(insn, 21, 5);
541   InsnType Rt = fieldFromInstruction(insn, 16, 5);
542   InsnType Imm = SignExtend64(fieldFromInstruction(insn, 0, 16), 16) * 4;
543   bool HasRs = false;
544 
545   if (Rs >= Rt) {
546     MI.setOpcode(Mips::BOVC);
547     HasRs = true;
548   } else if (Rs != 0 && Rs < Rt) {
549     MI.setOpcode(Mips::BEQC);
550     HasRs = true;
551   } else
552     MI.setOpcode(Mips::BEQZALC);
553 
554   if (HasRs)
555     MI.addOperand(MCOperand::CreateReg(getReg(Decoder, Mips::GPR32RegClassID,
556                                        Rs)));
557 
558   MI.addOperand(MCOperand::CreateReg(getReg(Decoder, Mips::GPR32RegClassID,
559                                      Rt)));
560   MI.addOperand(MCOperand::CreateImm(Imm));
561 
562   return MCDisassembler::Success;
563 }
564 
565 template <typename InsnType>
566 static DecodeStatus DecodeDaddiGroupBranch(MCInst &MI, InsnType insn,
567                                            uint64_t Address,
568                                            const void *Decoder) {
569   // If we are called then we can assume that MIPS32r6/MIPS64r6 is enabled
570   // (otherwise we would have matched the ADDI instruction from the earlier
571   // ISA's instead).
572   //
573   // We have:
574   //    0b011000 sssss ttttt iiiiiiiiiiiiiiii
575   //      BNVC if rs >= rt
576   //      BNEZALC if rs == 0 && rt != 0
577   //      BNEC if rs < rt && rs != 0
578 
579   InsnType Rs = fieldFromInstruction(insn, 21, 5);
580   InsnType Rt = fieldFromInstruction(insn, 16, 5);
581   InsnType Imm = SignExtend64(fieldFromInstruction(insn, 0, 16), 16) * 4;
582   bool HasRs = false;
583 
584   if (Rs >= Rt) {
585     MI.setOpcode(Mips::BNVC);
586     HasRs = true;
587   } else if (Rs != 0 && Rs < Rt) {
588     MI.setOpcode(Mips::BNEC);
589     HasRs = true;
590   } else
591     MI.setOpcode(Mips::BNEZALC);
592 
593   if (HasRs)
594     MI.addOperand(MCOperand::CreateReg(getReg(Decoder, Mips::GPR32RegClassID,
595                                        Rs)));
596 
597   MI.addOperand(MCOperand::CreateReg(getReg(Decoder, Mips::GPR32RegClassID,
598                                      Rt)));
599   MI.addOperand(MCOperand::CreateImm(Imm));
600 
601   return MCDisassembler::Success;
602 }
603 
604 template <typename InsnType>
605 static DecodeStatus DecodeBlezlGroupBranch(MCInst &MI, InsnType insn,
606                                            uint64_t Address,
607                                            const void *Decoder) {
608   // If we are called then we can assume that MIPS32r6/MIPS64r6 is enabled
609   // (otherwise we would have matched the BLEZL instruction from the earlier
610   // ISA's instead).
611   //
612   // We have:
613   //    0b010110 sssss ttttt iiiiiiiiiiiiiiii
614   //      Invalid if rs == 0
615   //      BLEZC   if rs == 0  && rt != 0
616   //      BGEZC   if rs == rt && rt != 0
617   //      BGEC    if rs != rt && rs != 0  && rt != 0
618 
619   InsnType Rs = fieldFromInstruction(insn, 21, 5);
620   InsnType Rt = fieldFromInstruction(insn, 16, 5);
621   InsnType Imm = SignExtend64(fieldFromInstruction(insn, 0, 16), 16) * 4;
622   bool HasRs = false;
623 
624   if (Rt == 0)
625     return MCDisassembler::Fail;
626   else if (Rs == 0)
627     MI.setOpcode(Mips::BLEZC);
628   else if (Rs == Rt)
629     MI.setOpcode(Mips::BGEZC);
630   else {
631     HasRs = true;
632     MI.setOpcode(Mips::BGEC);
633   }
634 
635   if (HasRs)
636     MI.addOperand(MCOperand::CreateReg(getReg(Decoder, Mips::GPR32RegClassID,
637                                        Rs)));
638 
639   MI.addOperand(MCOperand::CreateReg(getReg(Decoder, Mips::GPR32RegClassID,
640                                      Rt)));
641 
642   MI.addOperand(MCOperand::CreateImm(Imm));
643 
644   return MCDisassembler::Success;
645 }
646 
647 template <typename InsnType>
648 static DecodeStatus DecodeBgtzlGroupBranch(MCInst &MI, InsnType insn,
649                                            uint64_t Address,
650                                            const void *Decoder) {
651   // If we are called then we can assume that MIPS32r6/MIPS64r6 is enabled
652   // (otherwise we would have matched the BGTZL instruction from the earlier
653   // ISA's instead).
654   //
655   // We have:
656   //    0b010111 sssss ttttt iiiiiiiiiiiiiiii
657   //      Invalid if rs == 0
658   //      BGTZC   if rs == 0  && rt != 0
659   //      BLTZC   if rs == rt && rt != 0
660   //      BLTC    if rs != rt && rs != 0  && rt != 0
661 
662   bool HasRs = false;
663 
664   InsnType Rs = fieldFromInstruction(insn, 21, 5);
665   InsnType Rt = fieldFromInstruction(insn, 16, 5);
666   InsnType Imm = SignExtend64(fieldFromInstruction(insn, 0, 16), 16) * 4;
667 
668   if (Rt == 0)
669     return MCDisassembler::Fail;
670   else if (Rs == 0)
671     MI.setOpcode(Mips::BGTZC);
672   else if (Rs == Rt)
673     MI.setOpcode(Mips::BLTZC);
674   else {
675     MI.setOpcode(Mips::BLTC);
676     HasRs = true;
677   }
678 
679   if (HasRs)
680     MI.addOperand(MCOperand::CreateReg(getReg(Decoder, Mips::GPR32RegClassID,
681                                               Rs)));
682 
683   MI.addOperand(MCOperand::CreateReg(getReg(Decoder, Mips::GPR32RegClassID,
684                                      Rt)));
685 
686   MI.addOperand(MCOperand::CreateImm(Imm));
687 
688   return MCDisassembler::Success;
689 }
690 
691 template <typename InsnType>
692 static DecodeStatus DecodeBgtzGroupBranch(MCInst &MI, InsnType insn,
693                                           uint64_t Address,
694                                           const void *Decoder) {
695   // If we are called then we can assume that MIPS32r6/MIPS64r6 is enabled
696   // (otherwise we would have matched the BGTZ instruction from the earlier
697   // ISA's instead).
698   //
699   // We have:
700   //    0b000111 sssss ttttt iiiiiiiiiiiiiiii
701   //      BGTZ    if rt == 0
702   //      BGTZALC if rs == 0 && rt != 0
703   //      BLTZALC if rs != 0 && rs == rt
704   //      BLTUC   if rs != 0 && rs != rt
705 
706   InsnType Rs = fieldFromInstruction(insn, 21, 5);
707   InsnType Rt = fieldFromInstruction(insn, 16, 5);
708   InsnType Imm = SignExtend64(fieldFromInstruction(insn, 0, 16), 16) * 4;
709   bool HasRs = false;
710   bool HasRt = false;
711 
712   if (Rt == 0) {
713     MI.setOpcode(Mips::BGTZ);
714     HasRs = true;
715   } else if (Rs == 0) {
716     MI.setOpcode(Mips::BGTZALC);
717     HasRt = true;
718   } else if (Rs == Rt) {
719     MI.setOpcode(Mips::BLTZALC);
720     HasRs = true;
721   } else {
722     MI.setOpcode(Mips::BLTUC);
723     HasRs = true;
724     HasRt = true;
725   }
726 
727   if (HasRs)
728     MI.addOperand(MCOperand::CreateReg(getReg(Decoder, Mips::GPR32RegClassID,
729                                        Rs)));
730 
731   if (HasRt)
732     MI.addOperand(MCOperand::CreateReg(getReg(Decoder, Mips::GPR32RegClassID,
733                                        Rt)));
734 
735   MI.addOperand(MCOperand::CreateImm(Imm));
736 
737   return MCDisassembler::Success;
738 }
739 
740 template <typename InsnType>
741 static DecodeStatus DecodeBlezGroupBranch(MCInst &MI, InsnType insn,
742                                            uint64_t Address,
743                                            const void *Decoder) {
744   // If we are called then we can assume that MIPS32r6/MIPS64r6 is enabled
745   // (otherwise we would have matched the BLEZL instruction from the earlier
746   // ISA's instead).
747   //
748   // We have:
749   //    0b000110 sssss ttttt iiiiiiiiiiiiiiii
750   //      Invalid   if rs == 0
751   //      BLEZALC   if rs == 0  && rt != 0
752   //      BGEZALC   if rs == rt && rt != 0
753   //      BGEUC     if rs != rt && rs != 0  && rt != 0
754 
755   InsnType Rs = fieldFromInstruction(insn, 21, 5);
756   InsnType Rt = fieldFromInstruction(insn, 16, 5);
757   InsnType Imm = SignExtend64(fieldFromInstruction(insn, 0, 16), 16) * 4;
758   bool HasRs = false;
759 
760   if (Rt == 0)
761     return MCDisassembler::Fail;
762   else if (Rs == 0)
763     MI.setOpcode(Mips::BLEZALC);
764   else if (Rs == Rt)
765     MI.setOpcode(Mips::BGEZALC);
766   else {
767     HasRs = true;
768     MI.setOpcode(Mips::BGEUC);
769   }
770 
771   if (HasRs)
772     MI.addOperand(MCOperand::CreateReg(getReg(Decoder, Mips::GPR32RegClassID,
773                                        Rs)));
774   MI.addOperand(MCOperand::CreateReg(getReg(Decoder, Mips::GPR32RegClassID,
775                                      Rt)));
776 
777   MI.addOperand(MCOperand::CreateImm(Imm));
778 
779   return MCDisassembler::Success;
780 }
781 
782 /// Read two bytes from the ArrayRef and return 16 bit halfword sorted
783 /// according to the given endianess.
784 static DecodeStatus readInstruction16(ArrayRef<uint8_t> Bytes, uint64_t Address,
785                                       uint64_t &Size, uint32_t &Insn,
786                                       bool IsBigEndian) {
787   // We want to read exactly 2 Bytes of data.
788   if (Bytes.size() < 2) {
789     Size = 0;
790     return MCDisassembler::Fail;
791   }
792 
793   if (IsBigEndian) {
794     Insn = (Bytes[0] << 8) | Bytes[1];
795   } else {
796     Insn = (Bytes[1] << 8) | Bytes[0];
797   }
798 
799   return MCDisassembler::Success;
800 }
801 
802 /// Read four bytes from the ArrayRef and return 32 bit word sorted
803 /// according to the given endianess
804 static DecodeStatus readInstruction32(ArrayRef<uint8_t> Bytes, uint64_t Address,
805                                       uint64_t &Size, uint32_t &Insn,
806                                       bool IsBigEndian, bool IsMicroMips) {
807   // We want to read exactly 4 Bytes of data.
808   if (Bytes.size() < 4) {
809     Size = 0;
810     return MCDisassembler::Fail;
811   }
812 
813   // High 16 bits of a 32-bit microMIPS instruction (where the opcode is)
814   // always precede the low 16 bits in the instruction stream (that is, they
815   // are placed at lower addresses in the instruction stream).
816   //
817   // microMIPS byte ordering:
818   //   Big-endian:    0 | 1 | 2 | 3
819   //   Little-endian: 1 | 0 | 3 | 2
820 
821   if (IsBigEndian) {
822     // Encoded as a big-endian 32-bit word in the stream.
823     Insn =
824         (Bytes[3] << 0) | (Bytes[2] << 8) | (Bytes[1] << 16) | (Bytes[0] << 24);
825   } else {
826     if (IsMicroMips) {
827       Insn = (Bytes[2] << 0) | (Bytes[3] << 8) | (Bytes[0] << 16) |
828              (Bytes[1] << 24);
829     } else {
830       Insn = (Bytes[0] << 0) | (Bytes[1] << 8) | (Bytes[2] << 16) |
831              (Bytes[3] << 24);
832     }
833   }
834 
835   return MCDisassembler::Success;
836 }
837 
838 DecodeStatus MipsDisassembler::getInstruction(MCInst &Instr, uint64_t &Size,
839                                               ArrayRef<uint8_t> Bytes,
840                                               uint64_t Address,
841                                               raw_ostream &VStream,
842                                               raw_ostream &CStream) const {
843   uint32_t Insn;
844   DecodeStatus Result;
845 
846   if (IsMicroMips) {
847     Result = readInstruction16(Bytes, Address, Size, Insn, IsBigEndian);
848 
849     DEBUG(dbgs() << "Trying MicroMips16 table (16-bit instructions):\n");
850     // Calling the auto-generated decoder function.
851     Result = decodeInstruction(DecoderTableMicroMips16, Instr, Insn, Address,
852                                this, STI);
853     if (Result != MCDisassembler::Fail) {
854       Size = 2;
855       return Result;
856     }
857 
858     Result = readInstruction32(Bytes, Address, Size, Insn, IsBigEndian, true);
859     if (Result == MCDisassembler::Fail)
860       return MCDisassembler::Fail;
861 
862     DEBUG(dbgs() << "Trying MicroMips32 table (32-bit instructions):\n");
863     // Calling the auto-generated decoder function.
864     Result = decodeInstruction(DecoderTableMicroMips32, Instr, Insn, Address,
865                                this, STI);
866     if (Result != MCDisassembler::Fail) {
867       Size = 4;
868       return Result;
869     }
870     return MCDisassembler::Fail;
871   }
872 
873   Result = readInstruction32(Bytes, Address, Size, Insn, IsBigEndian, false);
874   if (Result == MCDisassembler::Fail)
875     return MCDisassembler::Fail;
876 
877   if (hasCOP3()) {
878     DEBUG(dbgs() << "Trying COP3_ table (32-bit opcodes):\n");
879     Result =
880         decodeInstruction(DecoderTableCOP3_32, Instr, Insn, Address, this, STI);
881     if (Result != MCDisassembler::Fail) {
882       Size = 4;
883       return Result;
884     }
885   }
886 
887   if (hasMips32r6() && isGP64()) {
888     DEBUG(dbgs() << "Trying Mips32r6_64r6 (GPR64) table (32-bit opcodes):\n");
889     Result = decodeInstruction(DecoderTableMips32r6_64r6_GP6432, Instr, Insn,
890                                Address, this, STI);
891     if (Result != MCDisassembler::Fail) {
892       Size = 4;
893       return Result;
894     }
895   }
896 
897   if (hasMips32r6()) {
898     DEBUG(dbgs() << "Trying Mips32r6_64r6 table (32-bit opcodes):\n");
899     Result = decodeInstruction(DecoderTableMips32r6_64r632, Instr, Insn,
900                                Address, this, STI);
901     if (Result != MCDisassembler::Fail) {
902       Size = 4;
903       return Result;
904     }
905   }
906 
907   DEBUG(dbgs() << "Trying Mips table (32-bit opcodes):\n");
908   // Calling the auto-generated decoder function.
909   Result =
910       decodeInstruction(DecoderTableMips32, Instr, Insn, Address, this, STI);
911   if (Result != MCDisassembler::Fail) {
912     Size = 4;
913     return Result;
914   }
915 
916   return MCDisassembler::Fail;
917 }
918 
919 DecodeStatus Mips64Disassembler::getInstruction(MCInst &Instr, uint64_t &Size,
920                                                 ArrayRef<uint8_t> Bytes,
921                                                 uint64_t Address,
922                                                 raw_ostream &VStream,
923                                                 raw_ostream &CStream) const {
924   uint32_t Insn;
925 
926   DecodeStatus Result =
927       readInstruction32(Bytes, Address, Size, Insn, IsBigEndian, false);
928   if (Result == MCDisassembler::Fail)
929     return MCDisassembler::Fail;
930 
931   // Calling the auto-generated decoder function.
932   Result =
933       decodeInstruction(DecoderTableMips6432, Instr, Insn, Address, this, STI);
934   if (Result != MCDisassembler::Fail) {
935     Size = 4;
936     return Result;
937   }
938   // If we fail to decode in Mips64 decoder space we can try in Mips32
939   Result =
940       decodeInstruction(DecoderTableMips32, Instr, Insn, Address, this, STI);
941   if (Result != MCDisassembler::Fail) {
942     Size = 4;
943     return Result;
944   }
945 
946   return MCDisassembler::Fail;
947 }
948 
949 static DecodeStatus DecodeCPU16RegsRegisterClass(MCInst &Inst,
950                                                  unsigned RegNo,
951                                                  uint64_t Address,
952                                                  const void *Decoder) {
953 
954   return MCDisassembler::Fail;
955 
956 }
957 
958 static DecodeStatus DecodeGPR64RegisterClass(MCInst &Inst,
959                                              unsigned RegNo,
960                                              uint64_t Address,
961                                              const void *Decoder) {
962 
963   if (RegNo > 31)
964     return MCDisassembler::Fail;
965 
966   unsigned Reg = getReg(Decoder, Mips::GPR64RegClassID, RegNo);
967   Inst.addOperand(MCOperand::CreateReg(Reg));
968   return MCDisassembler::Success;
969 }
970 
971 static DecodeStatus DecodeGPRMM16RegisterClass(MCInst &Inst,
972                                                unsigned RegNo,
973                                                uint64_t Address,
974                                                const void *Decoder) {
975   if (RegNo > 7)
976     return MCDisassembler::Fail;
977   unsigned Reg = getReg(Decoder, Mips::GPRMM16RegClassID, RegNo);
978   Inst.addOperand(MCOperand::CreateReg(Reg));
979   return MCDisassembler::Success;
980 }
981 
982 static DecodeStatus DecodeGPRMM16ZeroRegisterClass(MCInst &Inst,
983                                                    unsigned RegNo,
984                                                    uint64_t Address,
985                                                    const void *Decoder) {
986   if (RegNo > 7)
987     return MCDisassembler::Fail;
988   unsigned Reg = getReg(Decoder, Mips::GPRMM16ZeroRegClassID, RegNo);
989   Inst.addOperand(MCOperand::CreateReg(Reg));
990   return MCDisassembler::Success;
991 }
992 
993 static DecodeStatus DecodeGPR32RegisterClass(MCInst &Inst,
994                                              unsigned RegNo,
995                                              uint64_t Address,
996                                              const void *Decoder) {
997   if (RegNo > 31)
998     return MCDisassembler::Fail;
999   unsigned Reg = getReg(Decoder, Mips::GPR32RegClassID, RegNo);
1000   Inst.addOperand(MCOperand::CreateReg(Reg));
1001   return MCDisassembler::Success;
1002 }
1003 
1004 static DecodeStatus DecodePtrRegisterClass(MCInst &Inst,
1005                                            unsigned RegNo,
1006                                            uint64_t Address,
1007                                            const void *Decoder) {
1008   if (static_cast<const MipsDisassembler *>(Decoder)->isGP64Bit())
1009     return DecodeGPR64RegisterClass(Inst, RegNo, Address, Decoder);
1010 
1011   return DecodeGPR32RegisterClass(Inst, RegNo, Address, Decoder);
1012 }
1013 
1014 static DecodeStatus DecodeDSPRRegisterClass(MCInst &Inst,
1015                                             unsigned RegNo,
1016                                             uint64_t Address,
1017                                             const void *Decoder) {
1018   return DecodeGPR32RegisterClass(Inst, RegNo, Address, Decoder);
1019 }
1020 
1021 static DecodeStatus DecodeFGR64RegisterClass(MCInst &Inst,
1022                                              unsigned RegNo,
1023                                              uint64_t Address,
1024                                              const void *Decoder) {
1025   if (RegNo > 31)
1026     return MCDisassembler::Fail;
1027 
1028   unsigned Reg = getReg(Decoder, Mips::FGR64RegClassID, RegNo);
1029   Inst.addOperand(MCOperand::CreateReg(Reg));
1030   return MCDisassembler::Success;
1031 }
1032 
1033 static DecodeStatus DecodeFGR32RegisterClass(MCInst &Inst,
1034                                              unsigned RegNo,
1035                                              uint64_t Address,
1036                                              const void *Decoder) {
1037   if (RegNo > 31)
1038     return MCDisassembler::Fail;
1039 
1040   unsigned Reg = getReg(Decoder, Mips::FGR32RegClassID, RegNo);
1041   Inst.addOperand(MCOperand::CreateReg(Reg));
1042   return MCDisassembler::Success;
1043 }
1044 
1045 static DecodeStatus DecodeCCRRegisterClass(MCInst &Inst,
1046                                            unsigned RegNo,
1047                                            uint64_t Address,
1048                                            const void *Decoder) {
1049   if (RegNo > 31)
1050     return MCDisassembler::Fail;
1051   unsigned Reg = getReg(Decoder, Mips::CCRRegClassID, RegNo);
1052   Inst.addOperand(MCOperand::CreateReg(Reg));
1053   return MCDisassembler::Success;
1054 }
1055 
1056 static DecodeStatus DecodeFCCRegisterClass(MCInst &Inst,
1057                                            unsigned RegNo,
1058                                            uint64_t Address,
1059                                            const void *Decoder) {
1060   if (RegNo > 7)
1061     return MCDisassembler::Fail;
1062   unsigned Reg = getReg(Decoder, Mips::FCCRegClassID, RegNo);
1063   Inst.addOperand(MCOperand::CreateReg(Reg));
1064   return MCDisassembler::Success;
1065 }
1066 
1067 static DecodeStatus DecodeFGRCCRegisterClass(MCInst &Inst, unsigned RegNo,
1068                                              uint64_t Address,
1069                                              const void *Decoder) {
1070   if (RegNo > 31)
1071     return MCDisassembler::Fail;
1072 
1073   unsigned Reg = getReg(Decoder, Mips::FGRCCRegClassID, RegNo);
1074   Inst.addOperand(MCOperand::CreateReg(Reg));
1075   return MCDisassembler::Success;
1076 }
1077 
1078 static DecodeStatus DecodeMem(MCInst &Inst,
1079                               unsigned Insn,
1080                               uint64_t Address,
1081                               const void *Decoder) {
1082   int Offset = SignExtend32<16>(Insn & 0xffff);
1083   unsigned Reg = fieldFromInstruction(Insn, 16, 5);
1084   unsigned Base = fieldFromInstruction(Insn, 21, 5);
1085 
1086   Reg = getReg(Decoder, Mips::GPR32RegClassID, Reg);
1087   Base = getReg(Decoder, Mips::GPR32RegClassID, Base);
1088 
1089   if(Inst.getOpcode() == Mips::SC ||
1090      Inst.getOpcode() == Mips::SCD){
1091     Inst.addOperand(MCOperand::CreateReg(Reg));
1092   }
1093 
1094   Inst.addOperand(MCOperand::CreateReg(Reg));
1095   Inst.addOperand(MCOperand::CreateReg(Base));
1096   Inst.addOperand(MCOperand::CreateImm(Offset));
1097 
1098   return MCDisassembler::Success;
1099 }
1100 
1101 static DecodeStatus DecodeCacheOp(MCInst &Inst,
1102                               unsigned Insn,
1103                               uint64_t Address,
1104                               const void *Decoder) {
1105   int Offset = SignExtend32<16>(Insn & 0xffff);
1106   unsigned Hint = fieldFromInstruction(Insn, 16, 5);
1107   unsigned Base = fieldFromInstruction(Insn, 21, 5);
1108 
1109   Base = getReg(Decoder, Mips::GPR32RegClassID, Base);
1110 
1111   Inst.addOperand(MCOperand::CreateReg(Base));
1112   Inst.addOperand(MCOperand::CreateImm(Offset));
1113   Inst.addOperand(MCOperand::CreateImm(Hint));
1114 
1115   return MCDisassembler::Success;
1116 }
1117 
1118 static DecodeStatus DecodeCacheOpMM(MCInst &Inst,
1119                                     unsigned Insn,
1120                                     uint64_t Address,
1121                                     const void *Decoder) {
1122   int Offset = SignExtend32<12>(Insn & 0xfff);
1123   unsigned Base = fieldFromInstruction(Insn, 16, 5);
1124   unsigned Hint = fieldFromInstruction(Insn, 21, 5);
1125 
1126   Base = getReg(Decoder, Mips::GPR32RegClassID, Base);
1127 
1128   Inst.addOperand(MCOperand::CreateReg(Base));
1129   Inst.addOperand(MCOperand::CreateImm(Offset));
1130   Inst.addOperand(MCOperand::CreateImm(Hint));
1131 
1132   return MCDisassembler::Success;
1133 }
1134 
1135 static DecodeStatus DecodeSyncI(MCInst &Inst,
1136                               unsigned Insn,
1137                               uint64_t Address,
1138                               const void *Decoder) {
1139   int Offset = SignExtend32<16>(Insn & 0xffff);
1140   unsigned Base = fieldFromInstruction(Insn, 21, 5);
1141 
1142   Base = getReg(Decoder, Mips::GPR32RegClassID, Base);
1143 
1144   Inst.addOperand(MCOperand::CreateReg(Base));
1145   Inst.addOperand(MCOperand::CreateImm(Offset));
1146 
1147   return MCDisassembler::Success;
1148 }
1149 
1150 static DecodeStatus DecodeMSA128Mem(MCInst &Inst, unsigned Insn,
1151                                     uint64_t Address, const void *Decoder) {
1152   int Offset = SignExtend32<10>(fieldFromInstruction(Insn, 16, 10));
1153   unsigned Reg = fieldFromInstruction(Insn, 6, 5);
1154   unsigned Base = fieldFromInstruction(Insn, 11, 5);
1155 
1156   Reg = getReg(Decoder, Mips::MSA128BRegClassID, Reg);
1157   Base = getReg(Decoder, Mips::GPR32RegClassID, Base);
1158 
1159   Inst.addOperand(MCOperand::CreateReg(Reg));
1160   Inst.addOperand(MCOperand::CreateReg(Base));
1161 
1162   // The immediate field of an LD/ST instruction is scaled which means it must
1163   // be multiplied (when decoding) by the size (in bytes) of the instructions'
1164   // data format.
1165   // .b - 1 byte
1166   // .h - 2 bytes
1167   // .w - 4 bytes
1168   // .d - 8 bytes
1169   switch(Inst.getOpcode())
1170   {
1171   default:
1172     assert (0 && "Unexpected instruction");
1173     return MCDisassembler::Fail;
1174     break;
1175   case Mips::LD_B:
1176   case Mips::ST_B:
1177     Inst.addOperand(MCOperand::CreateImm(Offset));
1178     break;
1179   case Mips::LD_H:
1180   case Mips::ST_H:
1181     Inst.addOperand(MCOperand::CreateImm(Offset * 2));
1182     break;
1183   case Mips::LD_W:
1184   case Mips::ST_W:
1185     Inst.addOperand(MCOperand::CreateImm(Offset * 4));
1186     break;
1187   case Mips::LD_D:
1188   case Mips::ST_D:
1189     Inst.addOperand(MCOperand::CreateImm(Offset * 8));
1190     break;
1191   }
1192 
1193   return MCDisassembler::Success;
1194 }
1195 
1196 static DecodeStatus DecodeMemMMImm4(MCInst &Inst,
1197                                     unsigned Insn,
1198                                     uint64_t Address,
1199                                     const void *Decoder) {
1200   unsigned Offset = Insn & 0xf;
1201   unsigned Reg = fieldFromInstruction(Insn, 7, 3);
1202   unsigned Base = fieldFromInstruction(Insn, 4, 3);
1203 
1204   switch (Inst.getOpcode()) {
1205     case Mips::LBU16_MM:
1206     case Mips::LHU16_MM:
1207     case Mips::LW16_MM:
1208       if (DecodeGPRMM16RegisterClass(Inst, Reg, Address, Decoder)
1209             == MCDisassembler::Fail)
1210         return MCDisassembler::Fail;
1211       break;
1212     case Mips::SB16_MM:
1213     case Mips::SH16_MM:
1214     case Mips::SW16_MM:
1215       if (DecodeGPRMM16ZeroRegisterClass(Inst, Reg, Address, Decoder)
1216             == MCDisassembler::Fail)
1217         return MCDisassembler::Fail;
1218       break;
1219   }
1220 
1221   if (DecodeGPRMM16RegisterClass(Inst, Base, Address, Decoder)
1222         == MCDisassembler::Fail)
1223     return MCDisassembler::Fail;
1224 
1225   switch (Inst.getOpcode()) {
1226     case Mips::LBU16_MM:
1227       if (Offset == 0xf)
1228         Inst.addOperand(MCOperand::CreateImm(-1));
1229       else
1230         Inst.addOperand(MCOperand::CreateImm(Offset));
1231       break;
1232     case Mips::SB16_MM:
1233       Inst.addOperand(MCOperand::CreateImm(Offset));
1234       break;
1235     case Mips::LHU16_MM:
1236     case Mips::SH16_MM:
1237       Inst.addOperand(MCOperand::CreateImm(Offset << 1));
1238       break;
1239     case Mips::LW16_MM:
1240     case Mips::SW16_MM:
1241       Inst.addOperand(MCOperand::CreateImm(Offset << 2));
1242       break;
1243   }
1244 
1245   return MCDisassembler::Success;
1246 }
1247 
1248 static DecodeStatus DecodeMemMMSPImm5Lsl2(MCInst &Inst,
1249                                           unsigned Insn,
1250                                           uint64_t Address,
1251                                           const void *Decoder) {
1252   unsigned Offset = Insn & 0x1F;
1253   unsigned Reg = fieldFromInstruction(Insn, 5, 5);
1254 
1255   Reg = getReg(Decoder, Mips::GPR32RegClassID, Reg);
1256 
1257   Inst.addOperand(MCOperand::CreateReg(Reg));
1258   Inst.addOperand(MCOperand::CreateReg(Mips::SP));
1259   Inst.addOperand(MCOperand::CreateImm(Offset << 2));
1260 
1261   return MCDisassembler::Success;
1262 }
1263 
1264 static DecodeStatus DecodeMemMMImm12(MCInst &Inst,
1265                                      unsigned Insn,
1266                                      uint64_t Address,
1267                                      const void *Decoder) {
1268   int Offset = SignExtend32<12>(Insn & 0x0fff);
1269   unsigned Reg = fieldFromInstruction(Insn, 21, 5);
1270   unsigned Base = fieldFromInstruction(Insn, 16, 5);
1271 
1272   Reg = getReg(Decoder, Mips::GPR32RegClassID, Reg);
1273   Base = getReg(Decoder, Mips::GPR32RegClassID, Base);
1274 
1275   switch (Inst.getOpcode()) {
1276   case Mips::SWM32_MM:
1277   case Mips::LWM32_MM:
1278     if (DecodeRegListOperand(Inst, Insn, Address, Decoder)
1279         == MCDisassembler::Fail)
1280       return MCDisassembler::Fail;
1281     Inst.addOperand(MCOperand::CreateReg(Base));
1282     Inst.addOperand(MCOperand::CreateImm(Offset));
1283     break;
1284   case Mips::SC_MM:
1285     Inst.addOperand(MCOperand::CreateReg(Reg));
1286     // fallthrough
1287   default:
1288     Inst.addOperand(MCOperand::CreateReg(Reg));
1289     if (Inst.getOpcode() == Mips::LWP_MM || Inst.getOpcode() == Mips::SWP_MM)
1290       Inst.addOperand(MCOperand::CreateReg(Reg+1));
1291 
1292     Inst.addOperand(MCOperand::CreateReg(Base));
1293     Inst.addOperand(MCOperand::CreateImm(Offset));
1294   }
1295 
1296   return MCDisassembler::Success;
1297 }
1298 
1299 static DecodeStatus DecodeMemMMImm16(MCInst &Inst,
1300                                      unsigned Insn,
1301                                      uint64_t Address,
1302                                      const void *Decoder) {
1303   int Offset = SignExtend32<16>(Insn & 0xffff);
1304   unsigned Reg = fieldFromInstruction(Insn, 21, 5);
1305   unsigned Base = fieldFromInstruction(Insn, 16, 5);
1306 
1307   Reg = getReg(Decoder, Mips::GPR32RegClassID, Reg);
1308   Base = getReg(Decoder, Mips::GPR32RegClassID, Base);
1309 
1310   Inst.addOperand(MCOperand::CreateReg(Reg));
1311   Inst.addOperand(MCOperand::CreateReg(Base));
1312   Inst.addOperand(MCOperand::CreateImm(Offset));
1313 
1314   return MCDisassembler::Success;
1315 }
1316 
1317 static DecodeStatus DecodeFMem(MCInst &Inst,
1318                                unsigned Insn,
1319                                uint64_t Address,
1320                                const void *Decoder) {
1321   int Offset = SignExtend32<16>(Insn & 0xffff);
1322   unsigned Reg = fieldFromInstruction(Insn, 16, 5);
1323   unsigned Base = fieldFromInstruction(Insn, 21, 5);
1324 
1325   Reg = getReg(Decoder, Mips::FGR64RegClassID, Reg);
1326   Base = getReg(Decoder, Mips::GPR32RegClassID, Base);
1327 
1328   Inst.addOperand(MCOperand::CreateReg(Reg));
1329   Inst.addOperand(MCOperand::CreateReg(Base));
1330   Inst.addOperand(MCOperand::CreateImm(Offset));
1331 
1332   return MCDisassembler::Success;
1333 }
1334 
1335 static DecodeStatus DecodeFMem2(MCInst &Inst,
1336                                unsigned Insn,
1337                                uint64_t Address,
1338                                const void *Decoder) {
1339   int Offset = SignExtend32<16>(Insn & 0xffff);
1340   unsigned Reg = fieldFromInstruction(Insn, 16, 5);
1341   unsigned Base = fieldFromInstruction(Insn, 21, 5);
1342 
1343   Reg = getReg(Decoder, Mips::COP2RegClassID, Reg);
1344   Base = getReg(Decoder, Mips::GPR32RegClassID, Base);
1345 
1346   Inst.addOperand(MCOperand::CreateReg(Reg));
1347   Inst.addOperand(MCOperand::CreateReg(Base));
1348   Inst.addOperand(MCOperand::CreateImm(Offset));
1349 
1350   return MCDisassembler::Success;
1351 }
1352 
1353 static DecodeStatus DecodeFMem3(MCInst &Inst,
1354                                unsigned Insn,
1355                                uint64_t Address,
1356                                const void *Decoder) {
1357   int Offset = SignExtend32<16>(Insn & 0xffff);
1358   unsigned Reg = fieldFromInstruction(Insn, 16, 5);
1359   unsigned Base = fieldFromInstruction(Insn, 21, 5);
1360 
1361   Reg = getReg(Decoder, Mips::COP3RegClassID, Reg);
1362   Base = getReg(Decoder, Mips::GPR32RegClassID, Base);
1363 
1364   Inst.addOperand(MCOperand::CreateReg(Reg));
1365   Inst.addOperand(MCOperand::CreateReg(Base));
1366   Inst.addOperand(MCOperand::CreateImm(Offset));
1367 
1368   return MCDisassembler::Success;
1369 }
1370 
1371 static DecodeStatus DecodeFMemCop2R6(MCInst &Inst,
1372                                     unsigned Insn,
1373                                     uint64_t Address,
1374                                     const void *Decoder) {
1375   int Offset = SignExtend32<11>(Insn & 0x07ff);
1376   unsigned Reg = fieldFromInstruction(Insn, 16, 5);
1377   unsigned Base = fieldFromInstruction(Insn, 11, 5);
1378 
1379   Reg = getReg(Decoder, Mips::COP2RegClassID, Reg);
1380   Base = getReg(Decoder, Mips::GPR32RegClassID, Base);
1381 
1382   Inst.addOperand(MCOperand::CreateReg(Reg));
1383   Inst.addOperand(MCOperand::CreateReg(Base));
1384   Inst.addOperand(MCOperand::CreateImm(Offset));
1385 
1386   return MCDisassembler::Success;
1387 }
1388 static DecodeStatus DecodeSpecial3LlSc(MCInst &Inst,
1389                                        unsigned Insn,
1390                                        uint64_t Address,
1391                                        const void *Decoder) {
1392   int64_t Offset = SignExtend64<9>((Insn >> 7) & 0x1ff);
1393   unsigned Rt = fieldFromInstruction(Insn, 16, 5);
1394   unsigned Base = fieldFromInstruction(Insn, 21, 5);
1395 
1396   Rt = getReg(Decoder, Mips::GPR32RegClassID, Rt);
1397   Base = getReg(Decoder, Mips::GPR32RegClassID, Base);
1398 
1399   if(Inst.getOpcode() == Mips::SC_R6 || Inst.getOpcode() == Mips::SCD_R6){
1400     Inst.addOperand(MCOperand::CreateReg(Rt));
1401   }
1402 
1403   Inst.addOperand(MCOperand::CreateReg(Rt));
1404   Inst.addOperand(MCOperand::CreateReg(Base));
1405   Inst.addOperand(MCOperand::CreateImm(Offset));
1406 
1407   return MCDisassembler::Success;
1408 }
1409 
1410 static DecodeStatus DecodeHWRegsRegisterClass(MCInst &Inst,
1411                                               unsigned RegNo,
1412                                               uint64_t Address,
1413                                               const void *Decoder) {
1414   // Currently only hardware register 29 is supported.
1415   if (RegNo != 29)
1416     return  MCDisassembler::Fail;
1417   Inst.addOperand(MCOperand::CreateReg(Mips::HWR29));
1418   return MCDisassembler::Success;
1419 }
1420 
1421 static DecodeStatus DecodeAFGR64RegisterClass(MCInst &Inst,
1422                                               unsigned RegNo,
1423                                               uint64_t Address,
1424                                               const void *Decoder) {
1425   if (RegNo > 30 || RegNo %2)
1426     return MCDisassembler::Fail;
1427 
1428   ;
1429   unsigned Reg = getReg(Decoder, Mips::AFGR64RegClassID, RegNo /2);
1430   Inst.addOperand(MCOperand::CreateReg(Reg));
1431   return MCDisassembler::Success;
1432 }
1433 
1434 static DecodeStatus DecodeACC64DSPRegisterClass(MCInst &Inst,
1435                                                 unsigned RegNo,
1436                                                 uint64_t Address,
1437                                                 const void *Decoder) {
1438   if (RegNo >= 4)
1439     return MCDisassembler::Fail;
1440 
1441   unsigned Reg = getReg(Decoder, Mips::ACC64DSPRegClassID, RegNo);
1442   Inst.addOperand(MCOperand::CreateReg(Reg));
1443   return MCDisassembler::Success;
1444 }
1445 
1446 static DecodeStatus DecodeHI32DSPRegisterClass(MCInst &Inst,
1447                                                unsigned RegNo,
1448                                                uint64_t Address,
1449                                                const void *Decoder) {
1450   if (RegNo >= 4)
1451     return MCDisassembler::Fail;
1452 
1453   unsigned Reg = getReg(Decoder, Mips::HI32DSPRegClassID, RegNo);
1454   Inst.addOperand(MCOperand::CreateReg(Reg));
1455   return MCDisassembler::Success;
1456 }
1457 
1458 static DecodeStatus DecodeLO32DSPRegisterClass(MCInst &Inst,
1459                                                unsigned RegNo,
1460                                                uint64_t Address,
1461                                                const void *Decoder) {
1462   if (RegNo >= 4)
1463     return MCDisassembler::Fail;
1464 
1465   unsigned Reg = getReg(Decoder, Mips::LO32DSPRegClassID, RegNo);
1466   Inst.addOperand(MCOperand::CreateReg(Reg));
1467   return MCDisassembler::Success;
1468 }
1469 
1470 static DecodeStatus DecodeMSA128BRegisterClass(MCInst &Inst,
1471                                                unsigned RegNo,
1472                                                uint64_t Address,
1473                                                const void *Decoder) {
1474   if (RegNo > 31)
1475     return MCDisassembler::Fail;
1476 
1477   unsigned Reg = getReg(Decoder, Mips::MSA128BRegClassID, RegNo);
1478   Inst.addOperand(MCOperand::CreateReg(Reg));
1479   return MCDisassembler::Success;
1480 }
1481 
1482 static DecodeStatus DecodeMSA128HRegisterClass(MCInst &Inst,
1483                                                unsigned RegNo,
1484                                                uint64_t Address,
1485                                                const void *Decoder) {
1486   if (RegNo > 31)
1487     return MCDisassembler::Fail;
1488 
1489   unsigned Reg = getReg(Decoder, Mips::MSA128HRegClassID, RegNo);
1490   Inst.addOperand(MCOperand::CreateReg(Reg));
1491   return MCDisassembler::Success;
1492 }
1493 
1494 static DecodeStatus DecodeMSA128WRegisterClass(MCInst &Inst,
1495                                                unsigned RegNo,
1496                                                uint64_t Address,
1497                                                const void *Decoder) {
1498   if (RegNo > 31)
1499     return MCDisassembler::Fail;
1500 
1501   unsigned Reg = getReg(Decoder, Mips::MSA128WRegClassID, RegNo);
1502   Inst.addOperand(MCOperand::CreateReg(Reg));
1503   return MCDisassembler::Success;
1504 }
1505 
1506 static DecodeStatus DecodeMSA128DRegisterClass(MCInst &Inst,
1507                                                unsigned RegNo,
1508                                                uint64_t Address,
1509                                                const void *Decoder) {
1510   if (RegNo > 31)
1511     return MCDisassembler::Fail;
1512 
1513   unsigned Reg = getReg(Decoder, Mips::MSA128DRegClassID, RegNo);
1514   Inst.addOperand(MCOperand::CreateReg(Reg));
1515   return MCDisassembler::Success;
1516 }
1517 
1518 static DecodeStatus DecodeMSACtrlRegisterClass(MCInst &Inst,
1519                                                unsigned RegNo,
1520                                                uint64_t Address,
1521                                                const void *Decoder) {
1522   if (RegNo > 7)
1523     return MCDisassembler::Fail;
1524 
1525   unsigned Reg = getReg(Decoder, Mips::MSACtrlRegClassID, RegNo);
1526   Inst.addOperand(MCOperand::CreateReg(Reg));
1527   return MCDisassembler::Success;
1528 }
1529 
1530 static DecodeStatus DecodeCOP2RegisterClass(MCInst &Inst,
1531                                             unsigned RegNo,
1532                                             uint64_t Address,
1533                                             const void *Decoder) {
1534   if (RegNo > 31)
1535     return MCDisassembler::Fail;
1536 
1537   unsigned Reg = getReg(Decoder, Mips::COP2RegClassID, RegNo);
1538   Inst.addOperand(MCOperand::CreateReg(Reg));
1539   return MCDisassembler::Success;
1540 }
1541 
1542 static DecodeStatus DecodeBranchTarget(MCInst &Inst,
1543                                        unsigned Offset,
1544                                        uint64_t Address,
1545                                        const void *Decoder) {
1546   int32_t BranchOffset = (SignExtend32<16>(Offset) * 4) + 4;
1547   Inst.addOperand(MCOperand::CreateImm(BranchOffset));
1548   return MCDisassembler::Success;
1549 }
1550 
1551 static DecodeStatus DecodeJumpTarget(MCInst &Inst,
1552                                      unsigned Insn,
1553                                      uint64_t Address,
1554                                      const void *Decoder) {
1555 
1556   unsigned JumpOffset = fieldFromInstruction(Insn, 0, 26) << 2;
1557   Inst.addOperand(MCOperand::CreateImm(JumpOffset));
1558   return MCDisassembler::Success;
1559 }
1560 
1561 static DecodeStatus DecodeBranchTarget21(MCInst &Inst,
1562                                          unsigned Offset,
1563                                          uint64_t Address,
1564                                          const void *Decoder) {
1565   int32_t BranchOffset = SignExtend32<21>(Offset) * 4;
1566 
1567   Inst.addOperand(MCOperand::CreateImm(BranchOffset));
1568   return MCDisassembler::Success;
1569 }
1570 
1571 static DecodeStatus DecodeBranchTarget26(MCInst &Inst,
1572                                          unsigned Offset,
1573                                          uint64_t Address,
1574                                          const void *Decoder) {
1575   int32_t BranchOffset = SignExtend32<26>(Offset) * 4;
1576 
1577   Inst.addOperand(MCOperand::CreateImm(BranchOffset));
1578   return MCDisassembler::Success;
1579 }
1580 
1581 static DecodeStatus DecodeBranchTarget7MM(MCInst &Inst,
1582                                           unsigned Offset,
1583                                           uint64_t Address,
1584                                           const void *Decoder) {
1585   int32_t BranchOffset = SignExtend32<7>(Offset) << 1;
1586   Inst.addOperand(MCOperand::CreateImm(BranchOffset));
1587   return MCDisassembler::Success;
1588 }
1589 
1590 static DecodeStatus DecodeBranchTarget10MM(MCInst &Inst,
1591                                            unsigned Offset,
1592                                            uint64_t Address,
1593                                            const void *Decoder) {
1594   int32_t BranchOffset = SignExtend32<10>(Offset) << 1;
1595   Inst.addOperand(MCOperand::CreateImm(BranchOffset));
1596   return MCDisassembler::Success;
1597 }
1598 
1599 static DecodeStatus DecodeBranchTargetMM(MCInst &Inst,
1600                                          unsigned Offset,
1601                                          uint64_t Address,
1602                                          const void *Decoder) {
1603   int32_t BranchOffset = SignExtend32<16>(Offset) * 2;
1604   Inst.addOperand(MCOperand::CreateImm(BranchOffset));
1605   return MCDisassembler::Success;
1606 }
1607 
1608 static DecodeStatus DecodeJumpTargetMM(MCInst &Inst,
1609                                        unsigned Insn,
1610                                        uint64_t Address,
1611                                        const void *Decoder) {
1612   unsigned JumpOffset = fieldFromInstruction(Insn, 0, 26) << 1;
1613   Inst.addOperand(MCOperand::CreateImm(JumpOffset));
1614   return MCDisassembler::Success;
1615 }
1616 
1617 static DecodeStatus DecodeAddiur2Simm7(MCInst &Inst,
1618                                        unsigned Value,
1619                                        uint64_t Address,
1620                                        const void *Decoder) {
1621   if (Value == 0)
1622     Inst.addOperand(MCOperand::CreateImm(1));
1623   else if (Value == 0x7)
1624     Inst.addOperand(MCOperand::CreateImm(-1));
1625   else
1626     Inst.addOperand(MCOperand::CreateImm(Value << 2));
1627   return MCDisassembler::Success;
1628 }
1629 
1630 static DecodeStatus DecodeUImm6Lsl2(MCInst &Inst,
1631                                     unsigned Value,
1632                                     uint64_t Address,
1633                                     const void *Decoder) {
1634   Inst.addOperand(MCOperand::CreateImm(Value << 2));
1635   return MCDisassembler::Success;
1636 }
1637 
1638 static DecodeStatus DecodeLiSimm7(MCInst &Inst,
1639                                   unsigned Value,
1640                                   uint64_t Address,
1641                                   const void *Decoder) {
1642   if (Value == 0x7F)
1643     Inst.addOperand(MCOperand::CreateImm(-1));
1644   else
1645     Inst.addOperand(MCOperand::CreateImm(Value));
1646   return MCDisassembler::Success;
1647 }
1648 
1649 static DecodeStatus DecodeSimm4(MCInst &Inst,
1650                                 unsigned Value,
1651                                 uint64_t Address,
1652                                 const void *Decoder) {
1653   Inst.addOperand(MCOperand::CreateImm(SignExtend32<4>(Value)));
1654   return MCDisassembler::Success;
1655 }
1656 
1657 static DecodeStatus DecodeSimm16(MCInst &Inst,
1658                                  unsigned Insn,
1659                                  uint64_t Address,
1660                                  const void *Decoder) {
1661   Inst.addOperand(MCOperand::CreateImm(SignExtend32<16>(Insn)));
1662   return MCDisassembler::Success;
1663 }
1664 
1665 static DecodeStatus DecodeLSAImm(MCInst &Inst,
1666                                  unsigned Insn,
1667                                  uint64_t Address,
1668                                  const void *Decoder) {
1669   // We add one to the immediate field as it was encoded as 'imm - 1'.
1670   Inst.addOperand(MCOperand::CreateImm(Insn + 1));
1671   return MCDisassembler::Success;
1672 }
1673 
1674 static DecodeStatus DecodeInsSize(MCInst &Inst,
1675                                   unsigned Insn,
1676                                   uint64_t Address,
1677                                   const void *Decoder) {
1678   // First we need to grab the pos(lsb) from MCInst.
1679   int Pos = Inst.getOperand(2).getImm();
1680   int Size = (int) Insn - Pos + 1;
1681   Inst.addOperand(MCOperand::CreateImm(SignExtend32<16>(Size)));
1682   return MCDisassembler::Success;
1683 }
1684 
1685 static DecodeStatus DecodeExtSize(MCInst &Inst,
1686                                   unsigned Insn,
1687                                   uint64_t Address,
1688                                   const void *Decoder) {
1689   int Size = (int) Insn  + 1;
1690   Inst.addOperand(MCOperand::CreateImm(SignExtend32<16>(Size)));
1691   return MCDisassembler::Success;
1692 }
1693 
1694 static DecodeStatus DecodeSimm19Lsl2(MCInst &Inst, unsigned Insn,
1695                                      uint64_t Address, const void *Decoder) {
1696   Inst.addOperand(MCOperand::CreateImm(SignExtend32<19>(Insn) * 4));
1697   return MCDisassembler::Success;
1698 }
1699 
1700 static DecodeStatus DecodeSimm18Lsl3(MCInst &Inst, unsigned Insn,
1701                                      uint64_t Address, const void *Decoder) {
1702   Inst.addOperand(MCOperand::CreateImm(SignExtend32<18>(Insn) * 8));
1703   return MCDisassembler::Success;
1704 }
1705 
1706 static DecodeStatus DecodeSimm9SP(MCInst &Inst, unsigned Insn,
1707                                   uint64_t Address, const void *Decoder) {
1708   int32_t DecodedValue;
1709   switch (Insn) {
1710   case 0: DecodedValue = 256; break;
1711   case 1: DecodedValue = 257; break;
1712   case 510: DecodedValue = -258; break;
1713   case 511: DecodedValue = -257; break;
1714   default: DecodedValue = SignExtend32<9>(Insn); break;
1715   }
1716   Inst.addOperand(MCOperand::CreateImm(DecodedValue * 4));
1717   return MCDisassembler::Success;
1718 }
1719 
1720 static DecodeStatus DecodeANDI16Imm(MCInst &Inst, unsigned Insn,
1721                                     uint64_t Address, const void *Decoder) {
1722   // Insn must be >= 0, since it is unsigned that condition is always true.
1723   assert(Insn < 16);
1724   int32_t DecodedValues[] = {128, 1, 2, 3, 4, 7, 8, 15, 16, 31, 32, 63, 64,
1725                              255, 32768, 65535};
1726   Inst.addOperand(MCOperand::CreateImm(DecodedValues[Insn]));
1727   return MCDisassembler::Success;
1728 }
1729 
1730 static DecodeStatus DecodeUImm5lsl2(MCInst &Inst, unsigned Insn,
1731                                     uint64_t Address, const void *Decoder) {
1732   Inst.addOperand(MCOperand::CreateImm(Insn << 2));
1733   return MCDisassembler::Success;
1734 }
1735 
1736 static DecodeStatus DecodeRegListOperand(MCInst &Inst,
1737                                          unsigned Insn,
1738                                          uint64_t Address,
1739                                          const void *Decoder) {
1740   unsigned Regs[] = {Mips::S0, Mips::S1, Mips::S2, Mips::S3, Mips::S4, Mips::S5,
1741                      Mips::S6, Mips::FP};
1742   unsigned RegNum;
1743 
1744   unsigned RegLst = fieldFromInstruction(Insn, 21, 5);
1745   // Empty register lists are not allowed.
1746   if (RegLst == 0)
1747     return MCDisassembler::Fail;
1748 
1749   RegNum = RegLst & 0xf;
1750   for (unsigned i = 0; i < RegNum; i++)
1751     Inst.addOperand(MCOperand::CreateReg(Regs[i]));
1752 
1753   if (RegLst & 0x10)
1754     Inst.addOperand(MCOperand::CreateReg(Mips::RA));
1755 
1756   return MCDisassembler::Success;
1757 }
1758 
1759 static DecodeStatus DecodeRegListOperand16(MCInst &Inst, unsigned Insn,
1760                                            uint64_t Address,
1761                                            const void *Decoder) {
1762   unsigned Regs[] = {Mips::S0, Mips::S1, Mips::S2, Mips::S3};
1763   unsigned RegNum;
1764 
1765   unsigned RegLst = fieldFromInstruction(Insn, 4, 2);
1766   // Empty register lists are not allowed.
1767   if (RegLst == 0)
1768     return MCDisassembler::Fail;
1769 
1770   RegNum = RegLst & 0x3;
1771   for (unsigned i = 0; i < RegNum - 1; i++)
1772     Inst.addOperand(MCOperand::CreateReg(Regs[i]));
1773 
1774   Inst.addOperand(MCOperand::CreateReg(Mips::RA));
1775 
1776   return MCDisassembler::Success;
1777 }
1778 
1779 static DecodeStatus DecodeSimm23Lsl2(MCInst &Inst, unsigned Insn,
1780                                      uint64_t Address, const void *Decoder) {
1781   Inst.addOperand(MCOperand::CreateImm(SignExtend32<23>(Insn) << 2));
1782   return MCDisassembler::Success;
1783 }
1784