xref: /llvm-project/llvm/lib/Target/VE/Disassembler/VEDisassembler.cpp (revision b641c9f729fe4ebbc3e737fa69d3d9caf1cb3632)
1 //===- VEDisassembler.cpp - Disassembler for VE -----------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file is part of the VE Disassembler.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "MCTargetDesc/VEMCTargetDesc.h"
14 #include "TargetInfo/VETargetInfo.h"
15 #include "VE.h"
16 #include "llvm/MC/MCAsmInfo.h"
17 #include "llvm/MC/MCContext.h"
18 #include "llvm/MC/MCDisassembler/MCDisassembler.h"
19 #include "llvm/MC/MCFixedLenDisassembler.h"
20 #include "llvm/MC/MCInst.h"
21 #include "llvm/Support/TargetRegistry.h"
22 
23 using namespace llvm;
24 
25 #define DEBUG_TYPE "ve-disassembler"
26 
27 typedef MCDisassembler::DecodeStatus DecodeStatus;
28 
29 namespace {
30 
31 /// A disassembler class for VE.
32 class VEDisassembler : public MCDisassembler {
33 public:
34   VEDisassembler(const MCSubtargetInfo &STI, MCContext &Ctx)
35       : MCDisassembler(STI, Ctx) {}
36   virtual ~VEDisassembler() {}
37 
38   DecodeStatus getInstruction(MCInst &Instr, uint64_t &Size,
39                               ArrayRef<uint8_t> Bytes, uint64_t Address,
40                               raw_ostream &CStream) const override;
41 };
42 } // namespace
43 
44 static MCDisassembler *createVEDisassembler(const Target &T,
45                                             const MCSubtargetInfo &STI,
46                                             MCContext &Ctx) {
47   return new VEDisassembler(STI, Ctx);
48 }
49 
50 extern "C" void LLVMInitializeVEDisassembler() {
51   // Register the disassembler.
52   TargetRegistry::RegisterMCDisassembler(getTheVETarget(),
53                                          createVEDisassembler);
54 }
55 
56 static const unsigned I32RegDecoderTable[] = {
57     VE::SW0,  VE::SW1,  VE::SW2,  VE::SW3,  VE::SW4,  VE::SW5,  VE::SW6,
58     VE::SW7,  VE::SW8,  VE::SW9,  VE::SW10, VE::SW11, VE::SW12, VE::SW13,
59     VE::SW14, VE::SW15, VE::SW16, VE::SW17, VE::SW18, VE::SW19, VE::SW20,
60     VE::SW21, VE::SW22, VE::SW23, VE::SW24, VE::SW25, VE::SW26, VE::SW27,
61     VE::SW28, VE::SW29, VE::SW30, VE::SW31, VE::SW32, VE::SW33, VE::SW34,
62     VE::SW35, VE::SW36, VE::SW37, VE::SW38, VE::SW39, VE::SW40, VE::SW41,
63     VE::SW42, VE::SW43, VE::SW44, VE::SW45, VE::SW46, VE::SW47, VE::SW48,
64     VE::SW49, VE::SW50, VE::SW51, VE::SW52, VE::SW53, VE::SW54, VE::SW55,
65     VE::SW56, VE::SW57, VE::SW58, VE::SW59, VE::SW60, VE::SW61, VE::SW62,
66     VE::SW63};
67 
68 static const unsigned I64RegDecoderTable[] = {
69     VE::SX0,  VE::SX1,  VE::SX2,  VE::SX3,  VE::SX4,  VE::SX5,  VE::SX6,
70     VE::SX7,  VE::SX8,  VE::SX9,  VE::SX10, VE::SX11, VE::SX12, VE::SX13,
71     VE::SX14, VE::SX15, VE::SX16, VE::SX17, VE::SX18, VE::SX19, VE::SX20,
72     VE::SX21, VE::SX22, VE::SX23, VE::SX24, VE::SX25, VE::SX26, VE::SX27,
73     VE::SX28, VE::SX29, VE::SX30, VE::SX31, VE::SX32, VE::SX33, VE::SX34,
74     VE::SX35, VE::SX36, VE::SX37, VE::SX38, VE::SX39, VE::SX40, VE::SX41,
75     VE::SX42, VE::SX43, VE::SX44, VE::SX45, VE::SX46, VE::SX47, VE::SX48,
76     VE::SX49, VE::SX50, VE::SX51, VE::SX52, VE::SX53, VE::SX54, VE::SX55,
77     VE::SX56, VE::SX57, VE::SX58, VE::SX59, VE::SX60, VE::SX61, VE::SX62,
78     VE::SX63};
79 
80 static const unsigned F32RegDecoderTable[] = {
81     VE::SF0,  VE::SF1,  VE::SF2,  VE::SF3,  VE::SF4,  VE::SF5,  VE::SF6,
82     VE::SF7,  VE::SF8,  VE::SF9,  VE::SF10, VE::SF11, VE::SF12, VE::SF13,
83     VE::SF14, VE::SF15, VE::SF16, VE::SF17, VE::SF18, VE::SF19, VE::SF20,
84     VE::SF21, VE::SF22, VE::SF23, VE::SF24, VE::SF25, VE::SF26, VE::SF27,
85     VE::SF28, VE::SF29, VE::SF30, VE::SF31, VE::SF32, VE::SF33, VE::SF34,
86     VE::SF35, VE::SF36, VE::SF37, VE::SF38, VE::SF39, VE::SF40, VE::SF41,
87     VE::SF42, VE::SF43, VE::SF44, VE::SF45, VE::SF46, VE::SF47, VE::SF48,
88     VE::SF49, VE::SF50, VE::SF51, VE::SF52, VE::SF53, VE::SF54, VE::SF55,
89     VE::SF56, VE::SF57, VE::SF58, VE::SF59, VE::SF60, VE::SF61, VE::SF62,
90     VE::SF63};
91 
92 static const unsigned F128RegDecoderTable[] = {
93     VE::Q0,  VE::Q1,  VE::Q2,  VE::Q3,  VE::Q4,  VE::Q5,  VE::Q6,  VE::Q7,
94     VE::Q8,  VE::Q9,  VE::Q10, VE::Q11, VE::Q12, VE::Q13, VE::Q14, VE::Q15,
95     VE::Q16, VE::Q17, VE::Q18, VE::Q19, VE::Q20, VE::Q21, VE::Q22, VE::Q23,
96     VE::Q24, VE::Q25, VE::Q26, VE::Q27, VE::Q28, VE::Q29, VE::Q30, VE::Q31};
97 
98 static const unsigned MiscRegDecoderTable[] = {
99     VE::USRCC,      VE::PSW,        VE::SAR,        VE::NoRegister,
100     VE::NoRegister, VE::NoRegister, VE::NoRegister, VE::PMMR,
101     VE::PMCR0,      VE::PMCR1,      VE::PMCR2,      VE::PMCR3,
102     VE::NoRegister, VE::NoRegister, VE::NoRegister, VE::NoRegister,
103     VE::PMC0,       VE::PMC1,       VE::PMC2,       VE::PMC3,
104     VE::PMC4,       VE::PMC5,       VE::PMC6,       VE::PMC7,
105     VE::PMC8,       VE::PMC9,       VE::PMC10,      VE::PMC11,
106     VE::PMC12,      VE::PMC13,      VE::PMC14};
107 
108 static DecodeStatus DecodeI32RegisterClass(MCInst &Inst, unsigned RegNo,
109                                            uint64_t Address,
110                                            const void *Decoder) {
111   if (RegNo > 63)
112     return MCDisassembler::Fail;
113   unsigned Reg = I32RegDecoderTable[RegNo];
114   Inst.addOperand(MCOperand::createReg(Reg));
115   return MCDisassembler::Success;
116 }
117 
118 static DecodeStatus DecodeI64RegisterClass(MCInst &Inst, unsigned RegNo,
119                                            uint64_t Address,
120                                            const void *Decoder) {
121   if (RegNo > 63)
122     return MCDisassembler::Fail;
123   unsigned Reg = I64RegDecoderTable[RegNo];
124   Inst.addOperand(MCOperand::createReg(Reg));
125   return MCDisassembler::Success;
126 }
127 
128 static DecodeStatus DecodeF32RegisterClass(MCInst &Inst, unsigned RegNo,
129                                            uint64_t Address,
130                                            const void *Decoder) {
131   if (RegNo > 63)
132     return MCDisassembler::Fail;
133   unsigned Reg = F32RegDecoderTable[RegNo];
134   Inst.addOperand(MCOperand::createReg(Reg));
135   return MCDisassembler::Success;
136 }
137 
138 static DecodeStatus DecodeF128RegisterClass(MCInst &Inst, unsigned RegNo,
139                                             uint64_t Address,
140                                             const void *Decoder) {
141   if (RegNo % 2 || RegNo > 63)
142     return MCDisassembler::Fail;
143   unsigned Reg = F128RegDecoderTable[RegNo / 2];
144   Inst.addOperand(MCOperand::createReg(Reg));
145   return MCDisassembler::Success;
146 }
147 
148 static DecodeStatus DecodeMISCRegisterClass(MCInst &Inst, unsigned RegNo,
149                                             uint64_t Address,
150                                             const void *Decoder) {
151   if (RegNo > 30)
152     return MCDisassembler::Fail;
153   unsigned Reg = MiscRegDecoderTable[RegNo];
154   if (Reg == VE::NoRegister)
155     return MCDisassembler::Fail;
156   Inst.addOperand(MCOperand::createReg(Reg));
157   return MCDisassembler::Success;
158 }
159 
160 static DecodeStatus DecodeASX(MCInst &Inst, uint64_t insn, uint64_t Address,
161                               const void *Decoder);
162 static DecodeStatus DecodeLoadI32(MCInst &Inst, uint64_t insn, uint64_t Address,
163                                   const void *Decoder);
164 static DecodeStatus DecodeStoreI32(MCInst &Inst, uint64_t insn,
165                                    uint64_t Address, const void *Decoder);
166 static DecodeStatus DecodeLoadI64(MCInst &Inst, uint64_t insn, uint64_t Address,
167                                   const void *Decoder);
168 static DecodeStatus DecodeStoreI64(MCInst &Inst, uint64_t insn,
169                                    uint64_t Address, const void *Decoder);
170 static DecodeStatus DecodeLoadF32(MCInst &Inst, uint64_t insn, uint64_t Address,
171                                   const void *Decoder);
172 static DecodeStatus DecodeStoreF32(MCInst &Inst, uint64_t insn,
173                                    uint64_t Address, const void *Decoder);
174 static DecodeStatus DecodeTS1AMI64(MCInst &Inst, uint64_t insn,
175                                    uint64_t Address, const void *Decoder);
176 static DecodeStatus DecodeTS1AMI32(MCInst &Inst, uint64_t insn,
177                                    uint64_t Address, const void *Decoder);
178 static DecodeStatus DecodeCASI64(MCInst &Inst, uint64_t insn, uint64_t Address,
179                                  const void *Decoder);
180 static DecodeStatus DecodeCASI32(MCInst &Inst, uint64_t insn, uint64_t Address,
181                                  const void *Decoder);
182 static DecodeStatus DecodeCall(MCInst &Inst, uint64_t insn, uint64_t Address,
183                                const void *Decoder);
184 static DecodeStatus DecodeSIMM7(MCInst &Inst, uint64_t insn, uint64_t Address,
185                                 const void *Decoder);
186 static DecodeStatus DecodeCCOperand(MCInst &Inst, uint64_t insn,
187                                     uint64_t Address, const void *Decoder);
188 static DecodeStatus DecodeBranchCondition(MCInst &Inst, uint64_t insn,
189                                           uint64_t Address,
190                                           const void *Decoder);
191 static DecodeStatus DecodeBranchConditionAlways(MCInst &Inst, uint64_t insn,
192                                                 uint64_t Address,
193                                                 const void *Decoder);
194 
195 #include "VEGenDisassemblerTables.inc"
196 
197 /// Read four bytes from the ArrayRef and return 32 bit word.
198 static DecodeStatus readInstruction64(ArrayRef<uint8_t> Bytes, uint64_t Address,
199                                       uint64_t &Size, uint64_t &Insn,
200                                       bool IsLittleEndian) {
201   // We want to read exactly 8 Bytes of data.
202   if (Bytes.size() < 8) {
203     Size = 0;
204     return MCDisassembler::Fail;
205   }
206 
207   Insn = IsLittleEndian
208              ? ((uint64_t)Bytes[0] << 0) | ((uint64_t)Bytes[1] << 8) |
209                    ((uint64_t)Bytes[2] << 16) | ((uint64_t)Bytes[3] << 24) |
210                    ((uint64_t)Bytes[4] << 32) | ((uint64_t)Bytes[5] << 40) |
211                    ((uint64_t)Bytes[6] << 48) | ((uint64_t)Bytes[7] << 56)
212              : ((uint64_t)Bytes[7] << 0) | ((uint64_t)Bytes[6] << 8) |
213                    ((uint64_t)Bytes[5] << 16) | ((uint64_t)Bytes[4] << 24) |
214                    ((uint64_t)Bytes[3] << 32) | ((uint64_t)Bytes[2] << 40) |
215                    ((uint64_t)Bytes[1] << 48) | ((uint64_t)Bytes[0] << 56);
216 
217   return MCDisassembler::Success;
218 }
219 
220 DecodeStatus VEDisassembler::getInstruction(MCInst &Instr, uint64_t &Size,
221                                             ArrayRef<uint8_t> Bytes,
222                                             uint64_t Address,
223                                             raw_ostream &CStream) const {
224   uint64_t Insn;
225   bool isLittleEndian = getContext().getAsmInfo()->isLittleEndian();
226   DecodeStatus Result =
227       readInstruction64(Bytes, Address, Size, Insn, isLittleEndian);
228   if (Result == MCDisassembler::Fail)
229     return MCDisassembler::Fail;
230 
231   // Calling the auto-generated decoder function.
232 
233   Result = decodeInstruction(DecoderTableVE64, Instr, Insn, Address, this, STI);
234 
235   if (Result != MCDisassembler::Fail) {
236     Size = 8;
237     return Result;
238   }
239 
240   return MCDisassembler::Fail;
241 }
242 
243 typedef DecodeStatus (*DecodeFunc)(MCInst &MI, unsigned RegNo, uint64_t Address,
244                                    const void *Decoder);
245 
246 static DecodeStatus DecodeASX(MCInst &MI, uint64_t insn, uint64_t Address,
247                               const void *Decoder) {
248   unsigned sy = fieldFromInstruction(insn, 40, 7);
249   bool cy = fieldFromInstruction(insn, 47, 1);
250   unsigned sz = fieldFromInstruction(insn, 32, 7);
251   bool cz = fieldFromInstruction(insn, 39, 1);
252   uint64_t simm32 = SignExtend64<32>(fieldFromInstruction(insn, 0, 32));
253   DecodeStatus status;
254 
255   // Decode sz.
256   if (cz) {
257     status = DecodeI64RegisterClass(MI, sz, Address, Decoder);
258     if (status != MCDisassembler::Success)
259       return status;
260   } else {
261     MI.addOperand(MCOperand::createImm(0));
262   }
263 
264   // Decode sy.
265   if (cy) {
266     status = DecodeI64RegisterClass(MI, sy, Address, Decoder);
267     if (status != MCDisassembler::Success)
268       return status;
269   } else {
270     MI.addOperand(MCOperand::createImm(SignExtend32<7>(sy)));
271   }
272 
273   // Decode simm32.
274   MI.addOperand(MCOperand::createImm(simm32));
275 
276   return MCDisassembler::Success;
277 }
278 
279 static DecodeStatus DecodeAS(MCInst &MI, uint64_t insn, uint64_t Address,
280                              const void *Decoder) {
281   unsigned sz = fieldFromInstruction(insn, 32, 7);
282   bool cz = fieldFromInstruction(insn, 39, 1);
283   uint64_t simm32 = SignExtend64<32>(fieldFromInstruction(insn, 0, 32));
284   DecodeStatus status;
285 
286   // Decode sz.
287   if (cz) {
288     status = DecodeI64RegisterClass(MI, sz, Address, Decoder);
289     if (status != MCDisassembler::Success)
290       return status;
291   } else {
292     MI.addOperand(MCOperand::createImm(0));
293   }
294 
295   // Decode simm32.
296   MI.addOperand(MCOperand::createImm(simm32));
297 
298   return MCDisassembler::Success;
299 }
300 
301 static DecodeStatus DecodeMem(MCInst &MI, uint64_t insn, uint64_t Address,
302                               const void *Decoder, bool isLoad,
303                               DecodeFunc DecodeSX) {
304   unsigned sx = fieldFromInstruction(insn, 48, 7);
305 
306   DecodeStatus status;
307   if (isLoad) {
308     status = DecodeSX(MI, sx, Address, Decoder);
309     if (status != MCDisassembler::Success)
310       return status;
311   }
312 
313   status = DecodeASX(MI, insn, Address, Decoder);
314   if (status != MCDisassembler::Success)
315     return status;
316 
317   if (!isLoad) {
318     status = DecodeSX(MI, sx, Address, Decoder);
319     if (status != MCDisassembler::Success)
320       return status;
321   }
322   return MCDisassembler::Success;
323 }
324 
325 static DecodeStatus DecodeLoadI32(MCInst &Inst, uint64_t insn, uint64_t Address,
326                                   const void *Decoder) {
327   return DecodeMem(Inst, insn, Address, Decoder, true, DecodeI32RegisterClass);
328 }
329 
330 static DecodeStatus DecodeStoreI32(MCInst &Inst, uint64_t insn,
331                                    uint64_t Address, const void *Decoder) {
332   return DecodeMem(Inst, insn, Address, Decoder, false, DecodeI32RegisterClass);
333 }
334 
335 static DecodeStatus DecodeLoadI64(MCInst &Inst, uint64_t insn, uint64_t Address,
336                                   const void *Decoder) {
337   return DecodeMem(Inst, insn, Address, Decoder, true, DecodeI64RegisterClass);
338 }
339 
340 static DecodeStatus DecodeStoreI64(MCInst &Inst, uint64_t insn,
341                                    uint64_t Address, const void *Decoder) {
342   return DecodeMem(Inst, insn, Address, Decoder, false, DecodeI64RegisterClass);
343 }
344 
345 static DecodeStatus DecodeLoadF32(MCInst &Inst, uint64_t insn, uint64_t Address,
346                                   const void *Decoder) {
347   return DecodeMem(Inst, insn, Address, Decoder, true, DecodeF32RegisterClass);
348 }
349 
350 static DecodeStatus DecodeStoreF32(MCInst &Inst, uint64_t insn,
351                                    uint64_t Address, const void *Decoder) {
352   return DecodeMem(Inst, insn, Address, Decoder, false, DecodeF32RegisterClass);
353 }
354 
355 static DecodeStatus DecodeCAS(MCInst &MI, uint64_t insn, uint64_t Address,
356                               const void *Decoder, bool isImmOnly, bool isUImm,
357                               DecodeFunc DecodeSX) {
358   unsigned sx = fieldFromInstruction(insn, 48, 7);
359   bool cy = fieldFromInstruction(insn, 47, 1);
360   unsigned sy = fieldFromInstruction(insn, 40, 7);
361 
362   // Add $sx.
363   DecodeStatus status;
364   status = DecodeSX(MI, sx, Address, Decoder);
365   if (status != MCDisassembler::Success)
366     return status;
367 
368   // Add $disp($sz).
369   status = DecodeAS(MI, insn, Address, Decoder);
370   if (status != MCDisassembler::Success)
371     return status;
372 
373   // Add $sy.
374   if (cy && !isImmOnly) {
375     status = DecodeSX(MI, sy, Address, Decoder);
376     if (status != MCDisassembler::Success)
377       return status;
378   } else {
379     if (isUImm)
380       MI.addOperand(MCOperand::createImm(sy));
381     else
382       MI.addOperand(MCOperand::createImm(SignExtend32<7>(sy)));
383   }
384 
385   // Add $sd.
386   status = DecodeSX(MI, sx, Address, Decoder);
387   if (status != MCDisassembler::Success)
388     return status;
389 
390   return MCDisassembler::Success;
391 }
392 
393 static DecodeStatus DecodeTS1AMI64(MCInst &MI, uint64_t insn, uint64_t Address,
394                                    const void *Decoder) {
395   return DecodeCAS(MI, insn, Address, Decoder, false, true,
396                    DecodeI64RegisterClass);
397 }
398 
399 static DecodeStatus DecodeTS1AMI32(MCInst &MI, uint64_t insn, uint64_t Address,
400                                    const void *Decoder) {
401   return DecodeCAS(MI, insn, Address, Decoder, false, true,
402                    DecodeI32RegisterClass);
403 }
404 
405 static DecodeStatus DecodeCASI64(MCInst &MI, uint64_t insn, uint64_t Address,
406                                  const void *Decoder) {
407   return DecodeCAS(MI, insn, Address, Decoder, false, false,
408                    DecodeI64RegisterClass);
409 }
410 
411 static DecodeStatus DecodeCASI32(MCInst &MI, uint64_t insn, uint64_t Address,
412                                  const void *Decoder) {
413   return DecodeCAS(MI, insn, Address, Decoder, false, false,
414                    DecodeI32RegisterClass);
415 }
416 
417 static DecodeStatus DecodeCall(MCInst &Inst, uint64_t insn, uint64_t Address,
418                                const void *Decoder) {
419   return DecodeMem(Inst, insn, Address, Decoder, true, DecodeI64RegisterClass);
420 }
421 
422 static DecodeStatus DecodeSIMM7(MCInst &MI, uint64_t insn, uint64_t Address,
423                                 const void *Decoder) {
424   uint64_t tgt = SignExtend64<7>(insn);
425   MI.addOperand(MCOperand::createImm(tgt));
426   return MCDisassembler::Success;
427 }
428 
429 static bool isIntegerBCKind(MCInst &MI) {
430 
431 #define BCm_kind(NAME)                                                         \
432   case NAME##rri:                                                              \
433   case NAME##rzi:                                                              \
434   case NAME##iri:                                                              \
435   case NAME##izi:                                                              \
436   case NAME##rri_nt:                                                           \
437   case NAME##rzi_nt:                                                           \
438   case NAME##iri_nt:                                                           \
439   case NAME##izi_nt:                                                           \
440   case NAME##rri_t:                                                            \
441   case NAME##rzi_t:                                                            \
442   case NAME##iri_t:                                                            \
443   case NAME##izi_t:
444 
445 #define BCRm_kind(NAME)                                                        \
446   case NAME##rr:                                                               \
447   case NAME##ir:                                                               \
448   case NAME##rr_nt:                                                            \
449   case NAME##ir_nt:                                                            \
450   case NAME##rr_t:                                                             \
451   case NAME##ir_t:
452 
453   {
454     using namespace llvm::VE;
455     switch (MI.getOpcode()) {
456       BCm_kind(BCFL) BCm_kind(BCFW) BCRm_kind(BRCFL)
457           BCRm_kind(BRCFW) return true;
458     }
459   }
460 #undef BCm_kind
461 
462   return false;
463 }
464 
465 // Decode CC Operand field.
466 static DecodeStatus DecodeCCOperand(MCInst &MI, uint64_t cf, uint64_t Address,
467                                     const void *Decoder) {
468   MI.addOperand(MCOperand::createImm(VEValToCondCode(cf, isIntegerBCKind(MI))));
469   return MCDisassembler::Success;
470 }
471 
472 // Decode branch condition instruction and CCOperand field in it.
473 static DecodeStatus DecodeBranchCondition(MCInst &MI, uint64_t insn,
474                                           uint64_t Address,
475                                           const void *Decoder) {
476   unsigned cf = fieldFromInstruction(insn, 48, 4);
477   bool cy = fieldFromInstruction(insn, 47, 1);
478   unsigned sy = fieldFromInstruction(insn, 40, 7);
479 
480   // Decode cf.
481   MI.addOperand(MCOperand::createImm(VEValToCondCode(cf, isIntegerBCKind(MI))));
482 
483   // Decode sy.
484   DecodeStatus status;
485   if (cy) {
486     status = DecodeI64RegisterClass(MI, sy, Address, Decoder);
487     if (status != MCDisassembler::Success)
488       return status;
489   } else {
490     MI.addOperand(MCOperand::createImm(SignExtend32<7>(sy)));
491   }
492 
493   // Decode MEMri.
494   return DecodeAS(MI, insn, Address, Decoder);
495 }
496 
497 static DecodeStatus DecodeBranchConditionAlways(MCInst &MI, uint64_t insn,
498                                                 uint64_t Address,
499                                                 const void *Decoder) {
500   // Decode MEMri.
501   return DecodeAS(MI, insn, Address, Decoder);
502 }
503