1 //===-- X86Disassembler.cpp - Disassembler for x86 and x86_64 -------------===//
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 X86 Disassembler.
11 // It contains code to translate the data produced by the decoder into
12 //  MCInsts.
13 // Documentation for the disassembler can be found in X86Disassembler.h.
14 //
15 //===----------------------------------------------------------------------===//
16 
17 #include "X86Disassembler.h"
18 #include "X86DisassemblerDecoder.h"
19 #include "llvm/MC/MCContext.h"
20 #include "llvm/MC/MCDisassembler.h"
21 #include "llvm/MC/MCExpr.h"
22 #include "llvm/MC/MCInst.h"
23 #include "llvm/MC/MCInstrInfo.h"
24 #include "llvm/MC/MCSubtargetInfo.h"
25 #include "llvm/Support/Debug.h"
26 #include "llvm/Support/MemoryObject.h"
27 #include "llvm/Support/TargetRegistry.h"
28 #include "llvm/Support/raw_ostream.h"
29 
30 #define GET_REGINFO_ENUM
31 #include "X86GenRegisterInfo.inc"
32 #define GET_INSTRINFO_ENUM
33 #include "X86GenInstrInfo.inc"
34 
35 using namespace llvm;
36 using namespace llvm::X86Disassembler;
37 
38 void x86DisassemblerDebug(const char *file,
39                           unsigned line,
40                           const char *s) {
41   dbgs() << file << ":" << line << ": " << s;
42 }
43 
44 const char *x86DisassemblerGetInstrName(unsigned Opcode, const void *mii) {
45   const MCInstrInfo *MII = static_cast<const MCInstrInfo *>(mii);
46   return MII->getName(Opcode);
47 }
48 
49 #define debug(s) DEBUG(x86DisassemblerDebug(__FILE__, __LINE__, s));
50 
51 namespace llvm {
52 
53 // Fill-ins to make the compiler happy.  These constants are never actually
54 //   assigned; they are just filler to make an automatically-generated switch
55 //   statement work.
56 namespace X86 {
57   enum {
58     BX_SI = 500,
59     BX_DI = 501,
60     BP_SI = 502,
61     BP_DI = 503,
62     sib   = 504,
63     sib64 = 505
64   };
65 }
66 
67 extern Target TheX86_32Target, TheX86_64Target;
68 
69 }
70 
71 static bool translateInstruction(MCInst &target,
72                                 InternalInstruction &source,
73                                 const MCDisassembler *Dis);
74 
75 X86GenericDisassembler::X86GenericDisassembler(const MCSubtargetInfo &STI,
76                                                DisassemblerMode mode,
77                                                const MCInstrInfo *MII)
78   : MCDisassembler(STI), MII(MII), fMode(mode) {}
79 
80 X86GenericDisassembler::~X86GenericDisassembler() {
81   delete MII;
82 }
83 
84 /// regionReader - a callback function that wraps the readByte method from
85 ///   MemoryObject.
86 ///
87 /// @param arg      - The generic callback parameter.  In this case, this should
88 ///                   be a pointer to a MemoryObject.
89 /// @param byte     - A pointer to the byte to be read.
90 /// @param address  - The address to be read.
91 static int regionReader(const void* arg, uint8_t* byte, uint64_t address) {
92   const MemoryObject* region = static_cast<const MemoryObject*>(arg);
93   return region->readByte(address, byte);
94 }
95 
96 /// logger - a callback function that wraps the operator<< method from
97 ///   raw_ostream.
98 ///
99 /// @param arg      - The generic callback parameter.  This should be a pointe
100 ///                   to a raw_ostream.
101 /// @param log      - A string to be logged.  logger() adds a newline.
102 static void logger(void* arg, const char* log) {
103   if (!arg)
104     return;
105 
106   raw_ostream &vStream = *(static_cast<raw_ostream*>(arg));
107   vStream << log << "\n";
108 }
109 
110 //
111 // Public interface for the disassembler
112 //
113 
114 MCDisassembler::DecodeStatus
115 X86GenericDisassembler::getInstruction(MCInst &instr,
116                                        uint64_t &size,
117                                        const MemoryObject &region,
118                                        uint64_t address,
119                                        raw_ostream &vStream,
120                                        raw_ostream &cStream) const {
121   CommentStream = &cStream;
122 
123   InternalInstruction internalInstr;
124 
125   dlog_t loggerFn = logger;
126   if (&vStream == &nulls())
127     loggerFn = 0; // Disable logging completely if it's going to nulls().
128 
129   int ret = decodeInstruction(&internalInstr,
130                               regionReader,
131                               (const void*)&region,
132                               loggerFn,
133                               (void*)&vStream,
134                               (const void*)MII,
135                               address,
136                               fMode);
137 
138   if (ret) {
139     size = internalInstr.readerCursor - address;
140     return Fail;
141   }
142   else {
143     size = internalInstr.length;
144     return (!translateInstruction(instr, internalInstr, this)) ?
145             Success : Fail;
146   }
147 }
148 
149 //
150 // Private code that translates from struct InternalInstructions to MCInsts.
151 //
152 
153 /// translateRegister - Translates an internal register to the appropriate LLVM
154 ///   register, and appends it as an operand to an MCInst.
155 ///
156 /// @param mcInst     - The MCInst to append to.
157 /// @param reg        - The Reg to append.
158 static void translateRegister(MCInst &mcInst, Reg reg) {
159 #define ENTRY(x) X86::x,
160   uint8_t llvmRegnums[] = {
161     ALL_REGS
162     0
163   };
164 #undef ENTRY
165 
166   uint8_t llvmRegnum = llvmRegnums[reg];
167   mcInst.addOperand(MCOperand::CreateReg(llvmRegnum));
168 }
169 
170 /// tryAddingSymbolicOperand - trys to add a symbolic operand in place of the
171 /// immediate Value in the MCInst.
172 ///
173 /// @param Value      - The immediate Value, has had any PC adjustment made by
174 ///                     the caller.
175 /// @param isBranch   - If the instruction is a branch instruction
176 /// @param Address    - The starting address of the instruction
177 /// @param Offset     - The byte offset to this immediate in the instruction
178 /// @param Width      - The byte width of this immediate in the instruction
179 ///
180 /// If the getOpInfo() function was set when setupForSymbolicDisassembly() was
181 /// called then that function is called to get any symbolic information for the
182 /// immediate in the instruction using the Address, Offset and Width.  If that
183 /// returns non-zero then the symbolic information it returns is used to create
184 /// an MCExpr and that is added as an operand to the MCInst.  If getOpInfo()
185 /// returns zero and isBranch is true then a symbol look up for immediate Value
186 /// is done and if a symbol is found an MCExpr is created with that, else
187 /// an MCExpr with the immediate Value is created.  This function returns true
188 /// if it adds an operand to the MCInst and false otherwise.
189 static bool tryAddingSymbolicOperand(int64_t Value, bool isBranch,
190                                      uint64_t Address, uint64_t Offset,
191                                      uint64_t Width, MCInst &MI,
192                                      const MCDisassembler *Dis) {
193   return Dis->tryAddingSymbolicOperand(MI, Value, Address, isBranch,
194                                        Offset, Width);
195 }
196 
197 /// tryAddingPcLoadReferenceComment - trys to add a comment as to what is being
198 /// referenced by a load instruction with the base register that is the rip.
199 /// These can often be addresses in a literal pool.  The Address of the
200 /// instruction and its immediate Value are used to determine the address
201 /// being referenced in the literal pool entry.  The SymbolLookUp call back will
202 /// return a pointer to a literal 'C' string if the referenced address is an
203 /// address into a section with 'C' string literals.
204 static void tryAddingPcLoadReferenceComment(uint64_t Address, uint64_t Value,
205                                             const void *Decoder) {
206   const MCDisassembler *Dis = static_cast<const MCDisassembler*>(Decoder);
207   Dis->tryAddingPcLoadReferenceComment(Value, Address);
208 }
209 
210 /// translateImmediate  - Appends an immediate operand to an MCInst.
211 ///
212 /// @param mcInst       - The MCInst to append to.
213 /// @param immediate    - The immediate value to append.
214 /// @param operand      - The operand, as stored in the descriptor table.
215 /// @param insn         - The internal instruction.
216 static void translateImmediate(MCInst &mcInst, uint64_t immediate,
217                                const OperandSpecifier &operand,
218                                InternalInstruction &insn,
219                                const MCDisassembler *Dis) {
220   // Sign-extend the immediate if necessary.
221 
222   OperandType type = (OperandType)operand.type;
223 
224   bool isBranch = false;
225   uint64_t pcrel = 0;
226   if (type == TYPE_RELv) {
227     isBranch = true;
228     pcrel = insn.startLocation +
229             insn.immediateOffset + insn.immediateSize;
230     switch (insn.displacementSize) {
231     default:
232       break;
233     case 1:
234       if(immediate & 0x80)
235         immediate |= ~(0xffull);
236       break;
237     case 2:
238       if(immediate & 0x8000)
239         immediate |= ~(0xffffull);
240       break;
241     case 4:
242       if(immediate & 0x80000000)
243         immediate |= ~(0xffffffffull);
244       break;
245     case 8:
246       break;
247     }
248   }
249   // By default sign-extend all X86 immediates based on their encoding.
250   else if (type == TYPE_IMM8 || type == TYPE_IMM16 || type == TYPE_IMM32 ||
251            type == TYPE_IMM64) {
252     uint32_t Opcode = mcInst.getOpcode();
253     switch (operand.encoding) {
254     default:
255       break;
256     case ENCODING_IB:
257       // Special case those X86 instructions that use the imm8 as a set of
258       // bits, bit count, etc. and are not sign-extend.
259       if (Opcode != X86::BLENDPSrri && Opcode != X86::BLENDPDrri &&
260           Opcode != X86::PBLENDWrri && Opcode != X86::MPSADBWrri &&
261           Opcode != X86::DPPSrri && Opcode != X86::DPPDrri &&
262           Opcode != X86::INSERTPSrr && Opcode != X86::VBLENDPSYrri &&
263           Opcode != X86::VBLENDPSYrmi && Opcode != X86::VBLENDPDYrri &&
264           Opcode != X86::VBLENDPDYrmi && Opcode != X86::VPBLENDWrri &&
265           Opcode != X86::VMPSADBWrri && Opcode != X86::VDPPSYrri &&
266           Opcode != X86::VDPPSYrmi && Opcode != X86::VDPPDrri &&
267           Opcode != X86::VINSERTPSrr)
268         if(immediate & 0x80)
269           immediate |= ~(0xffull);
270       break;
271     case ENCODING_IW:
272       if(immediate & 0x8000)
273         immediate |= ~(0xffffull);
274       break;
275     case ENCODING_ID:
276       if(immediate & 0x80000000)
277         immediate |= ~(0xffffffffull);
278       break;
279     case ENCODING_IO:
280       break;
281     }
282   }
283 
284   switch (type) {
285   case TYPE_XMM32:
286   case TYPE_XMM64:
287   case TYPE_XMM128:
288     mcInst.addOperand(MCOperand::CreateReg(X86::XMM0 + (immediate >> 4)));
289     return;
290   case TYPE_XMM256:
291     mcInst.addOperand(MCOperand::CreateReg(X86::YMM0 + (immediate >> 4)));
292     return;
293   case TYPE_XMM512:
294     mcInst.addOperand(MCOperand::CreateReg(X86::ZMM0 + (immediate >> 4)));
295     return;
296   case TYPE_REL8:
297     isBranch = true;
298     pcrel = insn.startLocation + insn.immediateOffset + insn.immediateSize;
299     if(immediate & 0x80)
300       immediate |= ~(0xffull);
301     break;
302   case TYPE_REL32:
303   case TYPE_REL64:
304     isBranch = true;
305     pcrel = insn.startLocation + insn.immediateOffset + insn.immediateSize;
306     if(immediate & 0x80000000)
307       immediate |= ~(0xffffffffull);
308     break;
309   default:
310     // operand is 64 bits wide.  Do nothing.
311     break;
312   }
313 
314   if(!tryAddingSymbolicOperand(immediate + pcrel, isBranch, insn.startLocation,
315                                insn.immediateOffset, insn.immediateSize,
316                                mcInst, Dis))
317     mcInst.addOperand(MCOperand::CreateImm(immediate));
318 }
319 
320 /// translateRMRegister - Translates a register stored in the R/M field of the
321 ///   ModR/M byte to its LLVM equivalent and appends it to an MCInst.
322 /// @param mcInst       - The MCInst to append to.
323 /// @param insn         - The internal instruction to extract the R/M field
324 ///                       from.
325 /// @return             - 0 on success; -1 otherwise
326 static bool translateRMRegister(MCInst &mcInst,
327                                 InternalInstruction &insn) {
328   if (insn.eaBase == EA_BASE_sib || insn.eaBase == EA_BASE_sib64) {
329     debug("A R/M register operand may not have a SIB byte");
330     return true;
331   }
332 
333   switch (insn.eaBase) {
334   default:
335     debug("Unexpected EA base register");
336     return true;
337   case EA_BASE_NONE:
338     debug("EA_BASE_NONE for ModR/M base");
339     return true;
340 #define ENTRY(x) case EA_BASE_##x:
341   ALL_EA_BASES
342 #undef ENTRY
343     debug("A R/M register operand may not have a base; "
344           "the operand must be a register.");
345     return true;
346 #define ENTRY(x)                                                      \
347   case EA_REG_##x:                                                    \
348     mcInst.addOperand(MCOperand::CreateReg(X86::x)); break;
349   ALL_REGS
350 #undef ENTRY
351   }
352 
353   return false;
354 }
355 
356 /// translateRMMemory - Translates a memory operand stored in the Mod and R/M
357 ///   fields of an internal instruction (and possibly its SIB byte) to a memory
358 ///   operand in LLVM's format, and appends it to an MCInst.
359 ///
360 /// @param mcInst       - The MCInst to append to.
361 /// @param insn         - The instruction to extract Mod, R/M, and SIB fields
362 ///                       from.
363 /// @return             - 0 on success; nonzero otherwise
364 static bool translateRMMemory(MCInst &mcInst, InternalInstruction &insn,
365                               const MCDisassembler *Dis) {
366   // Addresses in an MCInst are represented as five operands:
367   //   1. basereg       (register)  The R/M base, or (if there is a SIB) the
368   //                                SIB base
369   //   2. scaleamount   (immediate) 1, or (if there is a SIB) the specified
370   //                                scale amount
371   //   3. indexreg      (register)  x86_registerNONE, or (if there is a SIB)
372   //                                the index (which is multiplied by the
373   //                                scale amount)
374   //   4. displacement  (immediate) 0, or the displacement if there is one
375   //   5. segmentreg    (register)  x86_registerNONE for now, but could be set
376   //                                if we have segment overrides
377 
378   MCOperand baseReg;
379   MCOperand scaleAmount;
380   MCOperand indexReg;
381   MCOperand displacement;
382   MCOperand segmentReg;
383   uint64_t pcrel = 0;
384 
385   if (insn.eaBase == EA_BASE_sib || insn.eaBase == EA_BASE_sib64) {
386     if (insn.sibBase != SIB_BASE_NONE) {
387       switch (insn.sibBase) {
388       default:
389         debug("Unexpected sibBase");
390         return true;
391 #define ENTRY(x)                                          \
392       case SIB_BASE_##x:                                  \
393         baseReg = MCOperand::CreateReg(X86::x); break;
394       ALL_SIB_BASES
395 #undef ENTRY
396       }
397     } else {
398       baseReg = MCOperand::CreateReg(0);
399     }
400 
401     // Check whether we are handling VSIB addressing mode for GATHER.
402     // If sibIndex was set to SIB_INDEX_NONE, index offset is 4 and
403     // we should use SIB_INDEX_XMM4|YMM4 for VSIB.
404     // I don't see a way to get the correct IndexReg in readSIB:
405     //   We can tell whether it is VSIB or SIB after instruction ID is decoded,
406     //   but instruction ID may not be decoded yet when calling readSIB.
407     uint32_t Opcode = mcInst.getOpcode();
408     bool IndexIs128 = (Opcode == X86::VGATHERDPDrm ||
409                        Opcode == X86::VGATHERDPDYrm ||
410                        Opcode == X86::VGATHERQPDrm ||
411                        Opcode == X86::VGATHERDPSrm ||
412                        Opcode == X86::VGATHERQPSrm ||
413                        Opcode == X86::VPGATHERDQrm ||
414                        Opcode == X86::VPGATHERDQYrm ||
415                        Opcode == X86::VPGATHERQQrm ||
416                        Opcode == X86::VPGATHERDDrm ||
417                        Opcode == X86::VPGATHERQDrm);
418     bool IndexIs256 = (Opcode == X86::VGATHERQPDYrm ||
419                        Opcode == X86::VGATHERDPSYrm ||
420                        Opcode == X86::VGATHERQPSYrm ||
421                        Opcode == X86::VPGATHERQQYrm ||
422                        Opcode == X86::VPGATHERDDYrm ||
423                        Opcode == X86::VPGATHERQDYrm);
424     if (IndexIs128 || IndexIs256) {
425       unsigned IndexOffset = insn.sibIndex -
426                          (insn.addressSize == 8 ? SIB_INDEX_RAX:SIB_INDEX_EAX);
427       SIBIndex IndexBase = IndexIs256 ? SIB_INDEX_YMM0 : SIB_INDEX_XMM0;
428       insn.sibIndex = (SIBIndex)(IndexBase +
429                            (insn.sibIndex == SIB_INDEX_NONE ? 4 : IndexOffset));
430     }
431 
432     if (insn.sibIndex != SIB_INDEX_NONE) {
433       switch (insn.sibIndex) {
434       default:
435         debug("Unexpected sibIndex");
436         return true;
437 #define ENTRY(x)                                          \
438       case SIB_INDEX_##x:                                 \
439         indexReg = MCOperand::CreateReg(X86::x); break;
440       EA_BASES_32BIT
441       EA_BASES_64BIT
442       REGS_XMM
443       REGS_YMM
444       REGS_ZMM
445 #undef ENTRY
446       }
447     } else {
448       indexReg = MCOperand::CreateReg(0);
449     }
450 
451     scaleAmount = MCOperand::CreateImm(insn.sibScale);
452   } else {
453     switch (insn.eaBase) {
454     case EA_BASE_NONE:
455       if (insn.eaDisplacement == EA_DISP_NONE) {
456         debug("EA_BASE_NONE and EA_DISP_NONE for ModR/M base");
457         return true;
458       }
459       if (insn.mode == MODE_64BIT){
460         pcrel = insn.startLocation +
461                 insn.displacementOffset + insn.displacementSize;
462         tryAddingPcLoadReferenceComment(insn.startLocation +
463                                         insn.displacementOffset,
464                                         insn.displacement + pcrel, Dis);
465         baseReg = MCOperand::CreateReg(X86::RIP); // Section 2.2.1.6
466       }
467       else
468         baseReg = MCOperand::CreateReg(0);
469 
470       indexReg = MCOperand::CreateReg(0);
471       break;
472     case EA_BASE_BX_SI:
473       baseReg = MCOperand::CreateReg(X86::BX);
474       indexReg = MCOperand::CreateReg(X86::SI);
475       break;
476     case EA_BASE_BX_DI:
477       baseReg = MCOperand::CreateReg(X86::BX);
478       indexReg = MCOperand::CreateReg(X86::DI);
479       break;
480     case EA_BASE_BP_SI:
481       baseReg = MCOperand::CreateReg(X86::BP);
482       indexReg = MCOperand::CreateReg(X86::SI);
483       break;
484     case EA_BASE_BP_DI:
485       baseReg = MCOperand::CreateReg(X86::BP);
486       indexReg = MCOperand::CreateReg(X86::DI);
487       break;
488     default:
489       indexReg = MCOperand::CreateReg(0);
490       switch (insn.eaBase) {
491       default:
492         debug("Unexpected eaBase");
493         return true;
494         // Here, we will use the fill-ins defined above.  However,
495         //   BX_SI, BX_DI, BP_SI, and BP_DI are all handled above and
496         //   sib and sib64 were handled in the top-level if, so they're only
497         //   placeholders to keep the compiler happy.
498 #define ENTRY(x)                                        \
499       case EA_BASE_##x:                                 \
500         baseReg = MCOperand::CreateReg(X86::x); break;
501       ALL_EA_BASES
502 #undef ENTRY
503 #define ENTRY(x) case EA_REG_##x:
504       ALL_REGS
505 #undef ENTRY
506         debug("A R/M memory operand may not be a register; "
507               "the base field must be a base.");
508         return true;
509       }
510     }
511 
512     scaleAmount = MCOperand::CreateImm(1);
513   }
514 
515   displacement = MCOperand::CreateImm(insn.displacement);
516 
517   static const uint8_t segmentRegnums[SEG_OVERRIDE_max] = {
518     0,        // SEG_OVERRIDE_NONE
519     X86::CS,
520     X86::SS,
521     X86::DS,
522     X86::ES,
523     X86::FS,
524     X86::GS
525   };
526 
527   segmentReg = MCOperand::CreateReg(segmentRegnums[insn.segmentOverride]);
528 
529   mcInst.addOperand(baseReg);
530   mcInst.addOperand(scaleAmount);
531   mcInst.addOperand(indexReg);
532   if(!tryAddingSymbolicOperand(insn.displacement + pcrel, false,
533                                insn.startLocation, insn.displacementOffset,
534                                insn.displacementSize, mcInst, Dis))
535     mcInst.addOperand(displacement);
536   mcInst.addOperand(segmentReg);
537   return false;
538 }
539 
540 /// translateRM - Translates an operand stored in the R/M (and possibly SIB)
541 ///   byte of an instruction to LLVM form, and appends it to an MCInst.
542 ///
543 /// @param mcInst       - The MCInst to append to.
544 /// @param operand      - The operand, as stored in the descriptor table.
545 /// @param insn         - The instruction to extract Mod, R/M, and SIB fields
546 ///                       from.
547 /// @return             - 0 on success; nonzero otherwise
548 static bool translateRM(MCInst &mcInst, const OperandSpecifier &operand,
549                         InternalInstruction &insn, const MCDisassembler *Dis) {
550   switch (operand.type) {
551   default:
552     debug("Unexpected type for a R/M operand");
553     return true;
554   case TYPE_R8:
555   case TYPE_R16:
556   case TYPE_R32:
557   case TYPE_R64:
558   case TYPE_Rv:
559   case TYPE_MM:
560   case TYPE_MM32:
561   case TYPE_MM64:
562   case TYPE_XMM:
563   case TYPE_XMM32:
564   case TYPE_XMM64:
565   case TYPE_XMM128:
566   case TYPE_XMM256:
567   case TYPE_XMM512:
568   case TYPE_DEBUGREG:
569   case TYPE_CONTROLREG:
570     return translateRMRegister(mcInst, insn);
571   case TYPE_M:
572   case TYPE_M8:
573   case TYPE_M16:
574   case TYPE_M32:
575   case TYPE_M64:
576   case TYPE_M128:
577   case TYPE_M256:
578   case TYPE_M512:
579   case TYPE_Mv:
580   case TYPE_M32FP:
581   case TYPE_M64FP:
582   case TYPE_M80FP:
583   case TYPE_M16INT:
584   case TYPE_M32INT:
585   case TYPE_M64INT:
586   case TYPE_M1616:
587   case TYPE_M1632:
588   case TYPE_M1664:
589   case TYPE_LEA:
590     return translateRMMemory(mcInst, insn, Dis);
591   }
592 }
593 
594 /// translateFPRegister - Translates a stack position on the FPU stack to its
595 ///   LLVM form, and appends it to an MCInst.
596 ///
597 /// @param mcInst       - The MCInst to append to.
598 /// @param stackPos     - The stack position to translate.
599 /// @return             - 0 on success; nonzero otherwise.
600 static bool translateFPRegister(MCInst &mcInst,
601                                uint8_t stackPos) {
602   if (stackPos >= 8) {
603     debug("Invalid FP stack position");
604     return true;
605   }
606 
607   mcInst.addOperand(MCOperand::CreateReg(X86::ST0 + stackPos));
608 
609   return false;
610 }
611 
612 /// translateOperand - Translates an operand stored in an internal instruction
613 ///   to LLVM's format and appends it to an MCInst.
614 ///
615 /// @param mcInst       - The MCInst to append to.
616 /// @param operand      - The operand, as stored in the descriptor table.
617 /// @param insn         - The internal instruction.
618 /// @return             - false on success; true otherwise.
619 static bool translateOperand(MCInst &mcInst, const OperandSpecifier &operand,
620                              InternalInstruction &insn,
621                              const MCDisassembler *Dis) {
622   switch (operand.encoding) {
623   default:
624     debug("Unhandled operand encoding during translation");
625     return true;
626   case ENCODING_REG:
627     translateRegister(mcInst, insn.reg);
628     return false;
629   case ENCODING_RM:
630     return translateRM(mcInst, operand, insn, Dis);
631   case ENCODING_CB:
632   case ENCODING_CW:
633   case ENCODING_CD:
634   case ENCODING_CP:
635   case ENCODING_CO:
636   case ENCODING_CT:
637     debug("Translation of code offsets isn't supported.");
638     return true;
639   case ENCODING_IB:
640   case ENCODING_IW:
641   case ENCODING_ID:
642   case ENCODING_IO:
643   case ENCODING_Iv:
644   case ENCODING_Ia:
645     translateImmediate(mcInst,
646                        insn.immediates[insn.numImmediatesTranslated++],
647                        operand,
648                        insn,
649                        Dis);
650     return false;
651   case ENCODING_RB:
652   case ENCODING_RW:
653   case ENCODING_RD:
654   case ENCODING_RO:
655     translateRegister(mcInst, insn.opcodeRegister);
656     return false;
657   case ENCODING_I:
658     return translateFPRegister(mcInst, insn.opcodeModifier);
659   case ENCODING_Rv:
660     translateRegister(mcInst, insn.opcodeRegister);
661     return false;
662   case ENCODING_VVVV:
663     translateRegister(mcInst, insn.vvvv);
664     return false;
665   case ENCODING_DUP:
666     return translateOperand(mcInst, insn.operands[operand.type - TYPE_DUP0],
667                             insn, Dis);
668   }
669 }
670 
671 /// translateInstruction - Translates an internal instruction and all its
672 ///   operands to an MCInst.
673 ///
674 /// @param mcInst       - The MCInst to populate with the instruction's data.
675 /// @param insn         - The internal instruction.
676 /// @return             - false on success; true otherwise.
677 static bool translateInstruction(MCInst &mcInst,
678                                 InternalInstruction &insn,
679                                 const MCDisassembler *Dis) {
680   if (!insn.spec) {
681     debug("Instruction has no specification");
682     return true;
683   }
684 
685   mcInst.setOpcode(insn.instructionID);
686   // If when reading the prefix bytes we determined the overlapping 0xf2 or 0xf3
687   // prefix bytes should be disassembled as xrelease and xacquire then set the
688   // opcode to those instead of the rep and repne opcodes.
689   if (insn.xAcquireRelease) {
690     if(mcInst.getOpcode() == X86::REP_PREFIX)
691       mcInst.setOpcode(X86::XRELEASE_PREFIX);
692     else if(mcInst.getOpcode() == X86::REPNE_PREFIX)
693       mcInst.setOpcode(X86::XACQUIRE_PREFIX);
694   }
695 
696   int index;
697 
698   insn.numImmediatesTranslated = 0;
699 
700   for (index = 0; index < X86_MAX_OPERANDS; ++index) {
701     if (insn.operands[index].encoding != ENCODING_NONE) {
702       if (translateOperand(mcInst, insn.operands[index], insn, Dis)) {
703         return true;
704       }
705     }
706   }
707 
708   return false;
709 }
710 
711 static MCDisassembler *createX86_32Disassembler(const Target &T,
712                                                 const MCSubtargetInfo &STI) {
713   return new X86Disassembler::X86GenericDisassembler(STI, MODE_32BIT,
714                                                      T.createMCInstrInfo());
715 }
716 
717 static MCDisassembler *createX86_64Disassembler(const Target &T,
718                                                 const MCSubtargetInfo &STI) {
719   return new X86Disassembler::X86GenericDisassembler(STI, MODE_64BIT,
720                                                      T.createMCInstrInfo());
721 }
722 
723 extern "C" void LLVMInitializeX86Disassembler() {
724   // Register the disassembler.
725   TargetRegistry::RegisterMCDisassembler(TheX86_32Target,
726                                          createX86_32Disassembler);
727   TargetRegistry::RegisterMCDisassembler(TheX86_64Target,
728                                          createX86_64Disassembler);
729 }
730