xref: /freebsd/contrib/llvm-project/llvm/lib/Target/X86/Disassembler/X86DisassemblerDecoder.h (revision 47ce20aef1e636e601ef26a4bc7e05c64a000640)
1 //===-- X86DisassemblerDecoderInternal.h - Disassembler decoder -*- 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 X86 Disassembler.
10 // It contains the public interface of the instruction decoder.
11 // Documentation for the disassembler can be found in X86Disassembler.h.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_LIB_TARGET_X86_DISASSEMBLER_X86DISASSEMBLERDECODER_H
16 #define LLVM_LIB_TARGET_X86_DISASSEMBLER_X86DISASSEMBLERDECODER_H
17 
18 #include "llvm/ADT/ArrayRef.h"
19 #include "llvm/Support/X86DisassemblerDecoderCommon.h"
20 
21 namespace llvm {
22 namespace X86Disassembler {
23 
24 // Accessor functions for various fields of an Intel instruction
25 #define modFromModRM(modRM)  (((modRM) & 0xc0) >> 6)
26 #define regFromModRM(modRM)  (((modRM) & 0x38) >> 3)
27 #define rmFromModRM(modRM)   ((modRM) & 0x7)
28 #define scaleFromSIB(sib)    (((sib) & 0xc0) >> 6)
29 #define indexFromSIB(sib)    (((sib) & 0x38) >> 3)
30 #define baseFromSIB(sib)     ((sib) & 0x7)
31 #define wFromREX(rex)        (((rex) & 0x8) >> 3)
32 #define rFromREX(rex)        (((rex) & 0x4) >> 2)
33 #define xFromREX(rex)        (((rex) & 0x2) >> 1)
34 #define bFromREX(rex)        ((rex) & 0x1)
35 
36 #define rFromEVEX2of4(evex)     (((~(evex)) & 0x80) >> 7)
37 #define xFromEVEX2of4(evex)     (((~(evex)) & 0x40) >> 6)
38 #define bFromEVEX2of4(evex)     (((~(evex)) & 0x20) >> 5)
39 #define r2FromEVEX2of4(evex)    (((~(evex)) & 0x10) >> 4)
40 #define mmFromEVEX2of4(evex)    ((evex) & 0x3)
41 #define wFromEVEX3of4(evex)     (((evex) & 0x80) >> 7)
42 #define vvvvFromEVEX3of4(evex)  (((~(evex)) & 0x78) >> 3)
43 #define ppFromEVEX3of4(evex)    ((evex) & 0x3)
44 #define zFromEVEX4of4(evex)     (((evex) & 0x80) >> 7)
45 #define l2FromEVEX4of4(evex)    (((evex) & 0x40) >> 6)
46 #define lFromEVEX4of4(evex)     (((evex) & 0x20) >> 5)
47 #define bFromEVEX4of4(evex)     (((evex) & 0x10) >> 4)
48 #define v2FromEVEX4of4(evex)    (((~evex) & 0x8) >> 3)
49 #define aaaFromEVEX4of4(evex)   ((evex) & 0x7)
50 
51 #define rFromVEX2of3(vex)       (((~(vex)) & 0x80) >> 7)
52 #define xFromVEX2of3(vex)       (((~(vex)) & 0x40) >> 6)
53 #define bFromVEX2of3(vex)       (((~(vex)) & 0x20) >> 5)
54 #define mmmmmFromVEX2of3(vex)   ((vex) & 0x1f)
55 #define wFromVEX3of3(vex)       (((vex) & 0x80) >> 7)
56 #define vvvvFromVEX3of3(vex)    (((~(vex)) & 0x78) >> 3)
57 #define lFromVEX3of3(vex)       (((vex) & 0x4) >> 2)
58 #define ppFromVEX3of3(vex)      ((vex) & 0x3)
59 
60 #define rFromVEX2of2(vex)       (((~(vex)) & 0x80) >> 7)
61 #define vvvvFromVEX2of2(vex)    (((~(vex)) & 0x78) >> 3)
62 #define lFromVEX2of2(vex)       (((vex) & 0x4) >> 2)
63 #define ppFromVEX2of2(vex)      ((vex) & 0x3)
64 
65 #define rFromXOP2of3(xop)       (((~(xop)) & 0x80) >> 7)
66 #define xFromXOP2of3(xop)       (((~(xop)) & 0x40) >> 6)
67 #define bFromXOP2of3(xop)       (((~(xop)) & 0x20) >> 5)
68 #define mmmmmFromXOP2of3(xop)   ((xop) & 0x1f)
69 #define wFromXOP3of3(xop)       (((xop) & 0x80) >> 7)
70 #define vvvvFromXOP3of3(vex)    (((~(vex)) & 0x78) >> 3)
71 #define lFromXOP3of3(xop)       (((xop) & 0x4) >> 2)
72 #define ppFromXOP3of3(xop)      ((xop) & 0x3)
73 
74 // These enums represent Intel registers for use by the decoder.
75 #define REGS_8BIT     \
76   ENTRY(AL)           \
77   ENTRY(CL)           \
78   ENTRY(DL)           \
79   ENTRY(BL)           \
80   ENTRY(AH)           \
81   ENTRY(CH)           \
82   ENTRY(DH)           \
83   ENTRY(BH)           \
84   ENTRY(R8B)          \
85   ENTRY(R9B)          \
86   ENTRY(R10B)         \
87   ENTRY(R11B)         \
88   ENTRY(R12B)         \
89   ENTRY(R13B)         \
90   ENTRY(R14B)         \
91   ENTRY(R15B)         \
92   ENTRY(SPL)          \
93   ENTRY(BPL)          \
94   ENTRY(SIL)          \
95   ENTRY(DIL)
96 
97 #define EA_BASES_16BIT  \
98   ENTRY(BX_SI)          \
99   ENTRY(BX_DI)          \
100   ENTRY(BP_SI)          \
101   ENTRY(BP_DI)          \
102   ENTRY(SI)             \
103   ENTRY(DI)             \
104   ENTRY(BP)             \
105   ENTRY(BX)             \
106   ENTRY(R8W)            \
107   ENTRY(R9W)            \
108   ENTRY(R10W)           \
109   ENTRY(R11W)           \
110   ENTRY(R12W)           \
111   ENTRY(R13W)           \
112   ENTRY(R14W)           \
113   ENTRY(R15W)
114 
115 #define REGS_16BIT    \
116   ENTRY(AX)           \
117   ENTRY(CX)           \
118   ENTRY(DX)           \
119   ENTRY(BX)           \
120   ENTRY(SP)           \
121   ENTRY(BP)           \
122   ENTRY(SI)           \
123   ENTRY(DI)           \
124   ENTRY(R8W)          \
125   ENTRY(R9W)          \
126   ENTRY(R10W)         \
127   ENTRY(R11W)         \
128   ENTRY(R12W)         \
129   ENTRY(R13W)         \
130   ENTRY(R14W)         \
131   ENTRY(R15W)
132 
133 #define EA_BASES_32BIT  \
134   ENTRY(EAX)            \
135   ENTRY(ECX)            \
136   ENTRY(EDX)            \
137   ENTRY(EBX)            \
138   ENTRY(sib)            \
139   ENTRY(EBP)            \
140   ENTRY(ESI)            \
141   ENTRY(EDI)            \
142   ENTRY(R8D)            \
143   ENTRY(R9D)            \
144   ENTRY(R10D)           \
145   ENTRY(R11D)           \
146   ENTRY(R12D)           \
147   ENTRY(R13D)           \
148   ENTRY(R14D)           \
149   ENTRY(R15D)
150 
151 #define REGS_32BIT  \
152   ENTRY(EAX)        \
153   ENTRY(ECX)        \
154   ENTRY(EDX)        \
155   ENTRY(EBX)        \
156   ENTRY(ESP)        \
157   ENTRY(EBP)        \
158   ENTRY(ESI)        \
159   ENTRY(EDI)        \
160   ENTRY(R8D)        \
161   ENTRY(R9D)        \
162   ENTRY(R10D)       \
163   ENTRY(R11D)       \
164   ENTRY(R12D)       \
165   ENTRY(R13D)       \
166   ENTRY(R14D)       \
167   ENTRY(R15D)
168 
169 #define EA_BASES_64BIT  \
170   ENTRY(RAX)            \
171   ENTRY(RCX)            \
172   ENTRY(RDX)            \
173   ENTRY(RBX)            \
174   ENTRY(sib64)          \
175   ENTRY(RBP)            \
176   ENTRY(RSI)            \
177   ENTRY(RDI)            \
178   ENTRY(R8)             \
179   ENTRY(R9)             \
180   ENTRY(R10)            \
181   ENTRY(R11)            \
182   ENTRY(R12)            \
183   ENTRY(R13)            \
184   ENTRY(R14)            \
185   ENTRY(R15)
186 
187 #define REGS_64BIT  \
188   ENTRY(RAX)        \
189   ENTRY(RCX)        \
190   ENTRY(RDX)        \
191   ENTRY(RBX)        \
192   ENTRY(RSP)        \
193   ENTRY(RBP)        \
194   ENTRY(RSI)        \
195   ENTRY(RDI)        \
196   ENTRY(R8)         \
197   ENTRY(R9)         \
198   ENTRY(R10)        \
199   ENTRY(R11)        \
200   ENTRY(R12)        \
201   ENTRY(R13)        \
202   ENTRY(R14)        \
203   ENTRY(R15)
204 
205 #define REGS_MMX  \
206   ENTRY(MM0)      \
207   ENTRY(MM1)      \
208   ENTRY(MM2)      \
209   ENTRY(MM3)      \
210   ENTRY(MM4)      \
211   ENTRY(MM5)      \
212   ENTRY(MM6)      \
213   ENTRY(MM7)
214 
215 #define REGS_XMM  \
216   ENTRY(XMM0)     \
217   ENTRY(XMM1)     \
218   ENTRY(XMM2)     \
219   ENTRY(XMM3)     \
220   ENTRY(XMM4)     \
221   ENTRY(XMM5)     \
222   ENTRY(XMM6)     \
223   ENTRY(XMM7)     \
224   ENTRY(XMM8)     \
225   ENTRY(XMM9)     \
226   ENTRY(XMM10)    \
227   ENTRY(XMM11)    \
228   ENTRY(XMM12)    \
229   ENTRY(XMM13)    \
230   ENTRY(XMM14)    \
231   ENTRY(XMM15)    \
232   ENTRY(XMM16)    \
233   ENTRY(XMM17)    \
234   ENTRY(XMM18)    \
235   ENTRY(XMM19)    \
236   ENTRY(XMM20)    \
237   ENTRY(XMM21)    \
238   ENTRY(XMM22)    \
239   ENTRY(XMM23)    \
240   ENTRY(XMM24)    \
241   ENTRY(XMM25)    \
242   ENTRY(XMM26)    \
243   ENTRY(XMM27)    \
244   ENTRY(XMM28)    \
245   ENTRY(XMM29)    \
246   ENTRY(XMM30)    \
247   ENTRY(XMM31)
248 
249 #define REGS_YMM  \
250   ENTRY(YMM0)     \
251   ENTRY(YMM1)     \
252   ENTRY(YMM2)     \
253   ENTRY(YMM3)     \
254   ENTRY(YMM4)     \
255   ENTRY(YMM5)     \
256   ENTRY(YMM6)     \
257   ENTRY(YMM7)     \
258   ENTRY(YMM8)     \
259   ENTRY(YMM9)     \
260   ENTRY(YMM10)    \
261   ENTRY(YMM11)    \
262   ENTRY(YMM12)    \
263   ENTRY(YMM13)    \
264   ENTRY(YMM14)    \
265   ENTRY(YMM15)    \
266   ENTRY(YMM16)    \
267   ENTRY(YMM17)    \
268   ENTRY(YMM18)    \
269   ENTRY(YMM19)    \
270   ENTRY(YMM20)    \
271   ENTRY(YMM21)    \
272   ENTRY(YMM22)    \
273   ENTRY(YMM23)    \
274   ENTRY(YMM24)    \
275   ENTRY(YMM25)    \
276   ENTRY(YMM26)    \
277   ENTRY(YMM27)    \
278   ENTRY(YMM28)    \
279   ENTRY(YMM29)    \
280   ENTRY(YMM30)    \
281   ENTRY(YMM31)
282 
283 #define REGS_ZMM  \
284   ENTRY(ZMM0)     \
285   ENTRY(ZMM1)     \
286   ENTRY(ZMM2)     \
287   ENTRY(ZMM3)     \
288   ENTRY(ZMM4)     \
289   ENTRY(ZMM5)     \
290   ENTRY(ZMM6)     \
291   ENTRY(ZMM7)     \
292   ENTRY(ZMM8)     \
293   ENTRY(ZMM9)     \
294   ENTRY(ZMM10)    \
295   ENTRY(ZMM11)    \
296   ENTRY(ZMM12)    \
297   ENTRY(ZMM13)    \
298   ENTRY(ZMM14)    \
299   ENTRY(ZMM15)    \
300   ENTRY(ZMM16)    \
301   ENTRY(ZMM17)    \
302   ENTRY(ZMM18)    \
303   ENTRY(ZMM19)    \
304   ENTRY(ZMM20)    \
305   ENTRY(ZMM21)    \
306   ENTRY(ZMM22)    \
307   ENTRY(ZMM23)    \
308   ENTRY(ZMM24)    \
309   ENTRY(ZMM25)    \
310   ENTRY(ZMM26)    \
311   ENTRY(ZMM27)    \
312   ENTRY(ZMM28)    \
313   ENTRY(ZMM29)    \
314   ENTRY(ZMM30)    \
315   ENTRY(ZMM31)
316 
317 #define REGS_MASKS \
318   ENTRY(K0)        \
319   ENTRY(K1)        \
320   ENTRY(K2)        \
321   ENTRY(K3)        \
322   ENTRY(K4)        \
323   ENTRY(K5)        \
324   ENTRY(K6)        \
325   ENTRY(K7)
326 
327 #define REGS_MASK_PAIRS \
328   ENTRY(K0_K1)     \
329   ENTRY(K2_K3)     \
330   ENTRY(K4_K5)     \
331   ENTRY(K6_K7)
332 
333 #define REGS_SEGMENT \
334   ENTRY(ES)          \
335   ENTRY(CS)          \
336   ENTRY(SS)          \
337   ENTRY(DS)          \
338   ENTRY(FS)          \
339   ENTRY(GS)
340 
341 #define REGS_DEBUG  \
342   ENTRY(DR0)        \
343   ENTRY(DR1)        \
344   ENTRY(DR2)        \
345   ENTRY(DR3)        \
346   ENTRY(DR4)        \
347   ENTRY(DR5)        \
348   ENTRY(DR6)        \
349   ENTRY(DR7)        \
350   ENTRY(DR8)        \
351   ENTRY(DR9)        \
352   ENTRY(DR10)       \
353   ENTRY(DR11)       \
354   ENTRY(DR12)       \
355   ENTRY(DR13)       \
356   ENTRY(DR14)       \
357   ENTRY(DR15)
358 
359 #define REGS_CONTROL  \
360   ENTRY(CR0)          \
361   ENTRY(CR1)          \
362   ENTRY(CR2)          \
363   ENTRY(CR3)          \
364   ENTRY(CR4)          \
365   ENTRY(CR5)          \
366   ENTRY(CR6)          \
367   ENTRY(CR7)          \
368   ENTRY(CR8)          \
369   ENTRY(CR9)          \
370   ENTRY(CR10)         \
371   ENTRY(CR11)         \
372   ENTRY(CR12)         \
373   ENTRY(CR13)         \
374   ENTRY(CR14)         \
375   ENTRY(CR15)
376 
377 #define REGS_BOUND    \
378   ENTRY(BND0)         \
379   ENTRY(BND1)         \
380   ENTRY(BND2)         \
381   ENTRY(BND3)
382 
383 #define ALL_EA_BASES  \
384   EA_BASES_16BIT      \
385   EA_BASES_32BIT      \
386   EA_BASES_64BIT
387 
388 #define ALL_SIB_BASES \
389   REGS_32BIT          \
390   REGS_64BIT
391 
392 #define ALL_REGS      \
393   REGS_8BIT           \
394   REGS_16BIT          \
395   REGS_32BIT          \
396   REGS_64BIT          \
397   REGS_MMX            \
398   REGS_XMM            \
399   REGS_YMM            \
400   REGS_ZMM            \
401   REGS_MASKS          \
402   REGS_MASK_PAIRS     \
403   REGS_SEGMENT        \
404   REGS_DEBUG          \
405   REGS_CONTROL        \
406   REGS_BOUND          \
407   ENTRY(RIP)
408 
409 /// All possible values of the base field for effective-address
410 /// computations, a.k.a. the Mod and R/M fields of the ModR/M byte.
411 /// We distinguish between bases (EA_BASE_*) and registers that just happen
412 /// to be referred to when Mod == 0b11 (EA_REG_*).
413 enum EABase {
414   EA_BASE_NONE,
415 #define ENTRY(x) EA_BASE_##x,
416   ALL_EA_BASES
417 #undef ENTRY
418 #define ENTRY(x) EA_REG_##x,
419   ALL_REGS
420 #undef ENTRY
421   EA_max
422 };
423 
424 /// All possible values of the SIB index field.
425 /// borrows entries from ALL_EA_BASES with the special case that
426 /// sib is synonymous with NONE.
427 /// Vector SIB: index can be XMM or YMM.
428 enum SIBIndex {
429   SIB_INDEX_NONE,
430 #define ENTRY(x) SIB_INDEX_##x,
431   ALL_EA_BASES
432   REGS_XMM
433   REGS_YMM
434   REGS_ZMM
435 #undef ENTRY
436   SIB_INDEX_max
437 };
438 
439 /// All possible values of the SIB base field.
440 enum SIBBase {
441   SIB_BASE_NONE,
442 #define ENTRY(x) SIB_BASE_##x,
443   ALL_SIB_BASES
444 #undef ENTRY
445   SIB_BASE_max
446 };
447 
448 /// Possible displacement types for effective-address computations.
449 typedef enum {
450   EA_DISP_NONE,
451   EA_DISP_8,
452   EA_DISP_16,
453   EA_DISP_32
454 } EADisplacement;
455 
456 /// All possible values of the reg field in the ModR/M byte.
457 enum Reg {
458 #define ENTRY(x) MODRM_REG_##x,
459   ALL_REGS
460 #undef ENTRY
461   MODRM_REG_max
462 };
463 
464 /// All possible segment overrides.
465 enum SegmentOverride {
466   SEG_OVERRIDE_NONE,
467   SEG_OVERRIDE_CS,
468   SEG_OVERRIDE_SS,
469   SEG_OVERRIDE_DS,
470   SEG_OVERRIDE_ES,
471   SEG_OVERRIDE_FS,
472   SEG_OVERRIDE_GS,
473   SEG_OVERRIDE_max
474 };
475 
476 /// Possible values for the VEX.m-mmmm field
477 enum VEXLeadingOpcodeByte {
478   VEX_LOB_0F = 0x1,
479   VEX_LOB_0F38 = 0x2,
480   VEX_LOB_0F3A = 0x3
481 };
482 
483 enum XOPMapSelect {
484   XOP_MAP_SELECT_8 = 0x8,
485   XOP_MAP_SELECT_9 = 0x9,
486   XOP_MAP_SELECT_A = 0xA
487 };
488 
489 /// Possible values for the VEX.pp/EVEX.pp field
490 enum VEXPrefixCode {
491   VEX_PREFIX_NONE = 0x0,
492   VEX_PREFIX_66 = 0x1,
493   VEX_PREFIX_F3 = 0x2,
494   VEX_PREFIX_F2 = 0x3
495 };
496 
497 enum VectorExtensionType {
498   TYPE_NO_VEX_XOP   = 0x0,
499   TYPE_VEX_2B       = 0x1,
500   TYPE_VEX_3B       = 0x2,
501   TYPE_EVEX         = 0x3,
502   TYPE_XOP          = 0x4
503 };
504 
505 /// Type for the byte reader that the consumer must provide to
506 /// the decoder. Reads a single byte from the instruction's address space.
507 /// \param arg     A baton that the consumer can associate with any internal
508 ///                state that it needs.
509 /// \param byte    A pointer to a single byte in memory that should be set to
510 ///                contain the value at address.
511 /// \param address The address in the instruction's address space that should
512 ///                be read from.
513 /// \return        -1 if the byte cannot be read for any reason; 0 otherwise.
514 typedef int (*byteReader_t)(const void *arg, uint8_t *byte, uint64_t address);
515 
516 /// Type for the logging function that the consumer can provide to
517 /// get debugging output from the decoder.
518 /// \param arg A baton that the consumer can associate with any internal
519 ///            state that it needs.
520 /// \param log A string that contains the message.  Will be reused after
521 ///            the logger returns.
522 typedef void (*dlog_t)(void *arg, const char *log);
523 
524 /// The specification for how to extract and interpret a full instruction and
525 /// its operands.
526 struct InstructionSpecifier {
527   uint16_t operands;
528 };
529 
530 /// The x86 internal instruction, which is produced by the decoder.
531 struct InternalInstruction {
532   // Reader interface (C)
533   byteReader_t reader;
534   // Opaque value passed to the reader
535   const void* readerArg;
536   // The address of the next byte to read via the reader
537   uint64_t readerCursor;
538 
539   // Logger interface (C)
540   dlog_t dlog;
541   // Opaque value passed to the logger
542   void* dlogArg;
543 
544   // General instruction information
545 
546   // The mode to disassemble for (64-bit, protected, real)
547   DisassemblerMode mode;
548   // The start of the instruction, usable with the reader
549   uint64_t startLocation;
550   // The length of the instruction, in bytes
551   size_t length;
552 
553   // Prefix state
554 
555   // The possible mandatory prefix
556   uint8_t mandatoryPrefix;
557   // The value of the vector extension prefix(EVEX/VEX/XOP), if present
558   uint8_t vectorExtensionPrefix[4];
559   // The type of the vector extension prefix
560   VectorExtensionType vectorExtensionType;
561   // The value of the REX prefix, if present
562   uint8_t rexPrefix;
563   // The segment override type
564   SegmentOverride segmentOverride;
565   // 1 if the prefix byte, 0xf2 or 0xf3 is xacquire or xrelease
566   bool xAcquireRelease;
567 
568   // Address-size override
569   bool hasAdSize;
570   // Operand-size override
571   bool hasOpSize;
572   // Lock prefix
573   bool hasLockPrefix;
574   // The repeat prefix if any
575   uint8_t repeatPrefix;
576 
577   // Sizes of various critical pieces of data, in bytes
578   uint8_t registerSize;
579   uint8_t addressSize;
580   uint8_t displacementSize;
581   uint8_t immediateSize;
582 
583   // Offsets from the start of the instruction to the pieces of data, which is
584   // needed to find relocation entries for adding symbolic operands.
585   uint8_t displacementOffset;
586   uint8_t immediateOffset;
587 
588   // opcode state
589 
590   // The last byte of the opcode, not counting any ModR/M extension
591   uint8_t opcode;
592 
593   // decode state
594 
595   // The type of opcode, used for indexing into the array of decode tables
596   OpcodeType opcodeType;
597   // The instruction ID, extracted from the decode table
598   uint16_t instructionID;
599   // The specifier for the instruction, from the instruction info table
600   const InstructionSpecifier *spec;
601 
602   // state for additional bytes, consumed during operand decode.  Pattern:
603   // consumed___ indicates that the byte was already consumed and does not
604   // need to be consumed again.
605 
606   // The VEX.vvvv field, which contains a third register operand for some AVX
607   // instructions.
608   Reg                           vvvv;
609 
610   // The writemask for AVX-512 instructions which is contained in EVEX.aaa
611   Reg                           writemask;
612 
613   // The ModR/M byte, which contains most register operands and some portion of
614   // all memory operands.
615   bool                          consumedModRM;
616   uint8_t                       modRM;
617 
618   // The SIB byte, used for more complex 32- or 64-bit memory operands
619   bool                          consumedSIB;
620   uint8_t                       sib;
621 
622   // The displacement, used for memory operands
623   bool                          consumedDisplacement;
624   int32_t                       displacement;
625 
626   // Immediates.  There can be two in some cases
627   uint8_t                       numImmediatesConsumed;
628   uint8_t                       numImmediatesTranslated;
629   uint64_t                      immediates[2];
630 
631   // A register or immediate operand encoded into the opcode
632   Reg                           opcodeRegister;
633 
634   // Portions of the ModR/M byte
635 
636   // These fields determine the allowable values for the ModR/M fields, which
637   // depend on operand and address widths.
638   EABase                        eaRegBase;
639   Reg                           regBase;
640 
641   // The Mod and R/M fields can encode a base for an effective address, or a
642   // register.  These are separated into two fields here.
643   EABase                        eaBase;
644   EADisplacement                eaDisplacement;
645   // The reg field always encodes a register
646   Reg                           reg;
647 
648   // SIB state
649   SIBIndex                      sibIndexBase;
650   SIBIndex                      sibIndex;
651   uint8_t                       sibScale;
652   SIBBase                       sibBase;
653 
654   // Embedded rounding control.
655   uint8_t                       RC;
656 
657   ArrayRef<OperandSpecifier> operands;
658 };
659 
660 /// Decode one instruction and store the decoding results in
661 /// a buffer provided by the consumer.
662 /// \param insn      The buffer to store the instruction in.  Allocated by the
663 ///                  consumer.
664 /// \param reader    The byteReader_t for the bytes to be read.
665 /// \param readerArg An argument to pass to the reader for storing context
666 ///                  specific to the consumer.  May be NULL.
667 /// \param logger    The dlog_t to be used in printing status messages from the
668 ///                  disassembler.  May be NULL.
669 /// \param loggerArg An argument to pass to the logger for storing context
670 ///                  specific to the logger.  May be NULL.
671 /// \param startLoc  The address (in the reader's address space) of the first
672 ///                  byte in the instruction.
673 /// \param mode      The mode (16-bit, 32-bit, 64-bit) to decode in.
674 /// \return          Nonzero if there was an error during decode, 0 otherwise.
675 int decodeInstruction(InternalInstruction *insn,
676                       byteReader_t reader,
677                       const void *readerArg,
678                       dlog_t logger,
679                       void *loggerArg,
680                       const void *miiArg,
681                       uint64_t startLoc,
682                       DisassemblerMode mode);
683 
684 /// Print a message to debugs()
685 /// \param file The name of the file printing the debug message.
686 /// \param line The line number that printed the debug message.
687 /// \param s    The message to print.
688 void Debug(const char *file, unsigned line, const char *s);
689 
690 StringRef GetInstrName(unsigned Opcode, const void *mii);
691 
692 } // namespace X86Disassembler
693 } // namespace llvm
694 
695 #endif
696