aboutsummaryrefslogtreecommitdiffstats
path: root/lib/Target/X86/X86InstrFormats.td
blob: 5e8c8258c2c249f1a04b57044e03dd08d82f7b12 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
//===- X86InstrFormats.td - X86 Instruction Formats --------*- tablegen -*-===//
// 
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// 
//===----------------------------------------------------------------------===//

//===----------------------------------------------------------------------===//
// X86 Instruction Format Definitions.
//

// Format specifies the encoding used by the instruction.  This is part of the
// ad-hoc solution used to emit machine instruction encodings by our machine
// code emitter.
class Format<bits<6> val> {
  bits<6> Value = val;
}

def Pseudo     : Format<0>; def RawFrm     : Format<1>;
def AddRegFrm  : Format<2>; def MRMDestReg : Format<3>;
def MRMDestMem : Format<4>; def MRMSrcReg  : Format<5>;
def MRMSrcMem  : Format<6>;
def MRM0r  : Format<16>; def MRM1r  : Format<17>; def MRM2r  : Format<18>;
def MRM3r  : Format<19>; def MRM4r  : Format<20>; def MRM5r  : Format<21>;
def MRM6r  : Format<22>; def MRM7r  : Format<23>;
def MRM0m  : Format<24>; def MRM1m  : Format<25>; def MRM2m  : Format<26>;
def MRM3m  : Format<27>; def MRM4m  : Format<28>; def MRM5m  : Format<29>;
def MRM6m  : Format<30>; def MRM7m  : Format<31>;
def MRMInitReg : Format<32>;
def MRM_C1 : Format<33>;
def MRM_C2 : Format<34>;
def MRM_C3 : Format<35>;
def MRM_C4 : Format<36>;
def MRM_C8 : Format<37>;
def MRM_C9 : Format<38>;
def MRM_E8 : Format<39>;
def MRM_F0 : Format<40>;
def MRM_F8 : Format<41>;
def MRM_F9 : Format<42>;

// ImmType - This specifies the immediate type used by an instruction. This is
// part of the ad-hoc solution used to emit machine instruction encodings by our
// machine code emitter.
class ImmType<bits<3> val> {
  bits<3> Value = val;
}
def NoImm      : ImmType<0>;
def Imm8       : ImmType<1>;
def Imm8PCRel  : ImmType<2>;
def Imm16      : ImmType<3>;
def Imm32      : ImmType<4>;
def Imm32PCRel : ImmType<5>;
def Imm64      : ImmType<6>;

// FPFormat - This specifies what form this FP instruction has.  This is used by
// the Floating-Point stackifier pass.
class FPFormat<bits<3> val> {
  bits<3> Value = val;
}
def NotFP      : FPFormat<0>;
def ZeroArgFP  : FPFormat<1>;
def OneArgFP   : FPFormat<2>;
def OneArgFPRW : FPFormat<3>;
def TwoArgFP   : FPFormat<4>;
def CompareFP  : FPFormat<5>;
def CondMovFP  : FPFormat<6>;
def SpecialFP  : FPFormat<7>;

// Class specifying the SSE execution domain, used by the SSEDomainFix pass.
// Keep in sync with tables in X86InstrInfo.cpp.
class Domain<bits<2> val> {
  bits<2> Value = val;
}
def GenericDomain   : Domain<0>;
def SSEPackedSingle : Domain<1>;
def SSEPackedDouble : Domain<2>;
def SSEPackedInt    : Domain<3>;

// Prefix byte classes which are used to indicate to the ad-hoc machine code
// emitter that various prefix bytes are required.
class OpSize { bit hasOpSizePrefix = 1; }
class AdSize { bit hasAdSizePrefix = 1; }
class REX_W  { bit hasREX_WPrefix = 1; }
class LOCK   { bit hasLockPrefix = 1; }
class SegFS  { bits<2> SegOvrBits = 1; }
class SegGS  { bits<2> SegOvrBits = 2; }
class TB     { bits<4> Prefix = 1; }
class REP    { bits<4> Prefix = 2; }
class D8     { bits<4> Prefix = 3; }
class D9     { bits<4> Prefix = 4; }
class DA     { bits<4> Prefix = 5; }
class DB     { bits<4> Prefix = 6; }
class DC     { bits<4> Prefix = 7; }
class DD     { bits<4> Prefix = 8; }
class DE     { bits<4> Prefix = 9; }
class DF     { bits<4> Prefix = 10; }
class XD     { bits<4> Prefix = 11; }
class XS     { bits<4> Prefix = 12; }
class T8     { bits<4> Prefix = 13; }
class TA     { bits<4> Prefix = 14; }
class TF     { bits<4> Prefix = 15; }
class VEX    { bit hasVEXPrefix = 1; }
class VEX_4V : VEX { bit hasVEX_4VPrefix = 1; }

class X86Inst<bits<8> opcod, Format f, ImmType i, dag outs, dag ins,
              string AsmStr, Domain d = GenericDomain>
  : Instruction {
  let Namespace = "X86";

  bits<8> Opcode = opcod;
  Format Form = f;
  bits<6> FormBits = Form.Value;
  ImmType ImmT = i;

  dag OutOperandList = outs;
  dag InOperandList = ins;
  string AsmString = AsmStr;

  //
  // Attributes specific to X86 instructions...
  //
  bit hasOpSizePrefix = 0;  // Does this inst have a 0x66 prefix?
  bit hasAdSizePrefix = 0;  // Does this inst have a 0x67 prefix?

  bits<4> Prefix = 0;       // Which prefix byte does this inst have?
  bit hasREX_WPrefix  = 0;  // Does this inst requires the REX.W prefix?
  FPFormat FPForm = NotFP;  // What flavor of FP instruction is this?
  bit hasLockPrefix = 0;    // Does this inst have a 0xF0 prefix?
  bits<2> SegOvrBits = 0;   // Segment override prefix.
  Domain ExeDomain = d;
  bit hasVEXPrefix  = 0;    // Does this inst requires a VEX prefix?
  bit hasVEX_4VPrefix  = 0; // Does this inst requires the VEX.VVVV field?

  // TSFlags layout should be kept in sync with X86InstrInfo.h.
  let TSFlags{5-0}   = FormBits;
  let TSFlags{6}     = hasOpSizePrefix;
  let TSFlags{7}     = hasAdSizePrefix;
  let TSFlags{11-8}  = Prefix;
  let TSFlags{12}    = hasREX_WPrefix;
  let TSFlags{15-13} = ImmT.Value;
  let TSFlags{18-16} = FPForm.Value;
  let TSFlags{19}    = hasLockPrefix;
  let TSFlags{21-20} = SegOvrBits;
  let TSFlags{23-22} = ExeDomain.Value;
  let TSFlags{31-24} = Opcode;
  let TSFlags{32}    = hasVEXPrefix;
  let TSFlags{33}    = hasVEX_4VPrefix;
}

class I<bits<8> o, Format f, dag outs, dag ins, string asm,
        list<dag> pattern, Domain d = GenericDomain>
  : X86Inst<o, f, NoImm, outs, ins, asm, d> {
  let Pattern = pattern;
  let CodeSize = 3;
}
class Ii8 <bits<8> o, Format f, dag outs, dag ins, string asm, 
           list<dag> pattern, Domain d = GenericDomain>
  : X86Inst<o, f, Imm8, outs, ins, asm, d> {
  let Pattern = pattern;
  let CodeSize = 3;
}
class Ii8PCRel<bits<8> o, Format f, dag outs, dag ins, string asm, 
               list<dag> pattern>
  : X86Inst<o, f, Imm8PCRel, outs, ins, asm> {
  let Pattern = pattern;
  let CodeSize = 3;
}
class Ii16<bits<8> o, Format f, dag outs, dag ins, string asm, 
           list<dag> pattern>
  : X86Inst<o, f, Imm16, outs, ins, asm> {
  let Pattern = pattern;
  let CodeSize = 3;
}
class Ii32<bits<8> o, Format f, dag outs, dag ins, string asm, 
           list<dag> pattern>
  : X86Inst<o, f, Imm32, outs, ins, asm> {
  let Pattern = pattern;
  let CodeSize = 3;
}

class Ii32PCRel<bits<8> o, Format f, dag outs, dag ins, string asm, 
           list<dag> pattern>
  : X86Inst<o, f, Imm32PCRel, outs, ins, asm> {
  let Pattern = pattern;
  let CodeSize = 3;
}

// FPStack Instruction Templates:
// FPI - Floating Point Instruction template.
class FPI<bits<8> o, Format F, dag outs, dag ins, string asm>
  : I<o, F, outs, ins, asm, []> {}

// FpI_ - Floating Point Psuedo Instruction template. Not Predicated.
class FpI_<dag outs, dag ins, FPFormat fp, list<dag> pattern>
  : X86Inst<0, Pseudo, NoImm, outs, ins, ""> {
  let FPForm = fp;
  let Pattern = pattern;
}

// Templates for instructions that use a 16- or 32-bit segmented address as
//  their only operand: lcall (FAR CALL) and ljmp (FAR JMP)
//
//   Iseg16 - 16-bit segment selector, 16-bit offset
//   Iseg32 - 16-bit segment selector, 32-bit offset

class Iseg16 <bits<8> o, Format f, dag outs, dag ins, string asm, 
              list<dag> pattern> : X86Inst<o, f, NoImm, outs, ins, asm> {
  let Pattern = pattern;
  let CodeSize = 3;
}

class Iseg32 <bits<8> o, Format f, dag outs, dag ins, string asm, 
              list<dag> pattern> : X86Inst<o, f, NoImm, outs, ins, asm> {
  let Pattern = pattern;
  let CodeSize = 3;
}

// SI - SSE 1 & 2 scalar instructions
class SI<bits<8> o, Format F, dag outs, dag ins, string asm, list<dag> pattern>
      : I<o, F, outs, ins, asm, pattern> {
  let Predicates = !if(hasVEXPrefix /* VEX_4V */,
            !if(!eq(Prefix, 11 /* XD */), [HasAVX, HasSSE2], [HasAVX, HasSSE1]),
            !if(!eq(Prefix, 12 /* XS */), [HasSSE1], [HasSSE2]));

  // AVX instructions have a 'v' prefix in the mnemonic
  let AsmString = !if(hasVEXPrefix, !strconcat("v", asm), asm);
}

// PI - SSE 1 & 2 packed instructions
class PI<bits<8> o, Format F, dag outs, dag ins, string asm, list<dag> pattern,
         Domain d>
      : I<o, F, outs, ins, asm, pattern, d> {
  let Predicates = !if(hasVEXPrefix /* VEX_4V */,
        !if(hasOpSizePrefix /* OpSize */, [HasAVX, HasSSE2], [HasAVX, HasSSE1]),
        !if(hasOpSizePrefix /* OpSize */, [HasSSE2], [HasSSE1]));

  // AVX instructions have a 'v' prefix in the mnemonic
  let AsmString = !if(hasVEXPrefix, !strconcat("v", asm), asm);
}

// PIi8 - SSE 1 & 2 packed instructions with immediate
class PIi8<bits<8> o, Format F, dag outs, dag ins, string asm,
           list<dag> pattern, Domain d>
      : Ii8<o, F, outs, ins, asm, pattern, d> {
  let Predicates = !if(hasVEX_4VPrefix /* VEX_4V */,
        !if(hasOpSizePrefix /* OpSize */, [HasAVX, HasSSE2], [HasAVX, HasSSE1]),
        !if(hasOpSizePrefix /* OpSize */, [HasSSE2], [HasSSE1]));

  // AVX instructions have a 'v' prefix in the mnemonic
  let AsmString = !if(hasVEX_4VPrefix, !strconcat("v", asm), asm);
}

// SSE1 Instruction Templates:
// 
//   SSI   - SSE1 instructions with XS prefix.
//   PSI   - SSE1 instructions with TB prefix.
//   PSIi8 - SSE1 instructions with ImmT == Imm8 and TB prefix.
//   VSSI  - SSE1 instructions with XS prefix in AVX form.
//   VPSI  - SSE1 instructions with TB prefix in AVX form.

class SSI<bits<8> o, Format F, dag outs, dag ins, string asm, list<dag> pattern>
      : I<o, F, outs, ins, asm, pattern>, XS, Requires<[HasSSE1]>;
class SSIi8<bits<8> o, Format F, dag outs, dag ins, string asm,
            list<dag> pattern>
      : Ii8<o, F, outs, ins, asm, pattern>, XS, Requires<[HasSSE1]>;
class PSI<bits<8> o, Format F, dag outs, dag ins, string asm, list<dag> pattern>
      : I<o, F, outs, ins, asm, pattern, SSEPackedSingle>, TB,
        Requires<[HasSSE1]>;
class PSIi8<bits<8> o, Format F, dag outs, dag ins, string asm,
            list<dag> pattern>
      : Ii8<o, F, outs, ins, asm, pattern, SSEPackedSingle>, TB,
        Requires<[HasSSE1]>;
class VSSI<bits<8> o, Format F, dag outs, dag ins, string asm,
           list<dag> pattern>
      : I<o, F, outs, ins, !strconcat("v", asm), pattern>, XS, VEX_4V,
        Requires<[HasAVX, HasSSE1]>;
class VPSI<bits<8> o, Format F, dag outs, dag ins, string asm,
           list<dag> pattern>
      : I<o, F, outs, ins, !strconcat("v", asm), pattern, SSEPackedSingle>,
        VEX_4V, Requires<[HasAVX, HasSSE1]>;

// SSE2 Instruction Templates:
// 
//   SDI    - SSE2 instructions with XD prefix.
//   SDIi8  - SSE2 instructions with ImmT == Imm8 and XD prefix.
//   SSDIi8 - SSE2 instructions with ImmT == Imm8 and XS prefix.
//   PDI    - SSE2 instructions with TB and OpSize prefixes.
//   PDIi8  - SSE2 instructions with ImmT == Imm8 and TB and OpSize prefixes.
//   VSDI   - SSE2 instructions with XD prefix in AVX form.
//   VPDI   - SSE2 instructions with TB and OpSize prefixes in AVX form.

class SDI<bits<8> o, Format F, dag outs, dag ins, string asm, list<dag> pattern>
      : I<o, F, outs, ins, asm, pattern>, XD, Requires<[HasSSE2]>;
class SDIi8<bits<8> o, Format F, dag outs, dag ins, string asm,
            list<dag> pattern>
      : Ii8<o, F, outs, ins, asm, pattern>, XD, Requires<[HasSSE2]>;
class SSDIi8<bits<8> o, Format F, dag outs, dag ins, string asm,
             list<dag> pattern>
      : Ii8<o, F, outs, ins, asm, pattern>, XS, Requires<[HasSSE2]>;
class PDI<bits<8> o, Format F, dag outs, dag ins, string asm, list<dag> pattern>
      : I<o, F, outs, ins, asm, pattern, SSEPackedDouble>, TB, OpSize,
        Requires<[HasSSE2]>;
class PDIi8<bits<8> o, Format F, dag outs, dag ins, string asm,
            list<dag> pattern>
      : Ii8<o, F, outs, ins, asm, pattern, SSEPackedDouble>, TB, OpSize,
        Requires<[HasSSE2]>;
class VSDI<bits<8> o, Format F, dag outs, dag ins, string asm,
           list<dag> pattern>
      : I<o, F, outs, ins, !strconcat("v", asm), pattern>, XD, VEX_4V,
        Requires<[HasAVX, HasSSE2]>;
class VPDI<bits<8> o, Format F, dag outs, dag ins, string asm,
           list<dag> pattern>
      : I<o, F, outs, ins, !strconcat("v", asm), pattern, SSEPackedDouble>,
        VEX_4V, OpSize, Requires<[HasAVX, HasSSE2]>;

// SSE3 Instruction Templates:
// 
//   S3I   - SSE3 instructions with TB and OpSize prefixes.
//   S3SI  - SSE3 instructions with XS prefix.
//   S3DI  - SSE3 instructions with XD prefix.

class S3SI<bits<8> o, Format F, dag outs, dag ins, string asm, 
           list<dag> pattern>
      : I<o, F, outs, ins, asm, pattern, SSEPackedSingle>, XS,
        Requires<[HasSSE3]>;
class S3DI<bits<8> o, Format F, dag outs, dag ins, string asm, 
           list<dag> pattern>
      : I<o, F, outs, ins, asm, pattern, SSEPackedDouble>, XD,
        Requires<[HasSSE3]>;
class S3I<bits<8> o, Format F, dag outs, dag ins, string asm, list<dag> pattern>
      : I<o, F, outs, ins, asm, pattern, SSEPackedDouble>, TB, OpSize,
        Requires<[HasSSE3]>;


// SSSE3 Instruction Templates:
// 
//   SS38I - SSSE3 instructions with T8 prefix.
//   SS3AI - SSSE3 instructions with TA prefix.
//
// Note: SSSE3 instructions have 64-bit and 128-bit versions. The 64-bit version
// uses the MMX registers. We put those instructions here because they better
// fit into the SSSE3 instruction category rather than the MMX category.

class SS38I<bits<8> o, Format F, dag outs, dag ins, string asm,
            list<dag> pattern>
      : Ii8<o, F, outs, ins, asm, pattern, SSEPackedInt>, T8,
        Requires<[HasSSSE3]>;
class SS3AI<bits<8> o, Format F, dag outs, dag ins, string asm,
            list<dag> pattern>
      : Ii8<o, F, outs, ins, asm, pattern, SSEPackedInt>, TA,
        Requires<[HasSSSE3]>;

// SSE4.1 Instruction Templates:
// 
//   SS48I - SSE 4.1 instructions with T8 prefix.
//   SS41AIi8 - SSE 4.1 instructions with TA prefix and ImmT == Imm8.
//
class SS48I<bits<8> o, Format F, dag outs, dag ins, string asm,
            list<dag> pattern>
      : I<o, F, outs, ins, asm, pattern, SSEPackedInt>, T8,
        Requires<[HasSSE41]>;
class SS4AIi8<bits<8> o, Format F, dag outs, dag ins, string asm,
            list<dag> pattern>
      : Ii8<o, F, outs, ins, asm, pattern, SSEPackedInt>, TA,
        Requires<[HasSSE41]>;

// SSE4.2 Instruction Templates:
// 
//   SS428I - SSE 4.2 instructions with T8 prefix.
class SS428I<bits<8> o, Format F, dag outs, dag ins, string asm,
             list<dag> pattern>
      : I<o, F, outs, ins, asm, pattern, SSEPackedInt>, T8,
        Requires<[HasSSE42]>;

//   SS42FI - SSE 4.2 instructions with TF prefix.
class SS42FI<bits<8> o, Format F, dag outs, dag ins, string asm,
              list<dag> pattern>
      : I<o, F, outs, ins, asm, pattern>, TF, Requires<[HasSSE42]>;
      
//   SS42AI = SSE 4.2 instructions with TA prefix
class SS42AI<bits<8> o, Format F, dag outs, dag ins, string asm,
             list<dag> pattern>
      : Ii8<o, F, outs, ins, asm, pattern, SSEPackedInt>, TA,
        Requires<[HasSSE42]>;

// AES Instruction Templates:
//
// AES8I
// These use the same encoding as the SSE4.2 T8 and TA encodings.
class AES8I<bits<8> o, Format F, dag outs, dag ins, string asm,
            list<dag>pattern>
      : I<o, F, outs, ins, asm, pattern, SSEPackedInt>, T8,
        Requires<[HasAES]>;

class AESAI<bits<8> o, Format F, dag outs, dag ins, string asm,
            list<dag> pattern>
      : Ii8<o, F, outs, ins, asm, pattern, SSEPackedInt>, TA,
        Requires<[HasAES]>;

// X86-64 Instruction templates...
//

class RI<bits<8> o, Format F, dag outs, dag ins, string asm, list<dag> pattern>
      : I<o, F, outs, ins, asm, pattern>, REX_W;
class RIi8 <bits<8> o, Format F, dag outs, dag ins, string asm,
            list<dag> pattern>
      : Ii8<o, F, outs, ins, asm, pattern>, REX_W;
class RIi32 <bits<8> o, Format F, dag outs, dag ins, string asm,
             list<dag> pattern>
      : Ii32<o, F, outs, ins, asm, pattern>, REX_W;

class RIi64<bits<8> o, Format f, dag outs, dag ins, string asm,
            list<dag> pattern>
  : X86Inst<o, f, Imm64, outs, ins, asm>, REX_W {
  let Pattern = pattern;
  let CodeSize = 3;
}

class RSSI<bits<8> o, Format F, dag outs, dag ins, string asm,
           list<dag> pattern>
      : SSI<o, F, outs, ins, asm, pattern>, REX_W;
class RSDI<bits<8> o, Format F, dag outs, dag ins, string asm,
           list<dag> pattern>
      : SDI<o, F, outs, ins, asm, pattern>, REX_W;
class RPDI<bits<8> o, Format F, dag outs, dag ins, string asm,
           list<dag> pattern>
      : PDI<o, F, outs, ins, asm, pattern>, REX_W;

// MMX Instruction templates
//

// MMXI   - MMX instructions with TB prefix.
// MMXI64 - MMX instructions with TB prefix valid only in 64 bit mode.
// MMX2I  - MMX / SSE2 instructions with TB and OpSize prefixes.
// MMXIi8 - MMX instructions with ImmT == Imm8 and TB prefix.
// MMXIi8 - MMX instructions with ImmT == Imm8 and TB prefix.
// MMXID  - MMX instructions with XD prefix.
// MMXIS  - MMX instructions with XS prefix.
class MMXI<bits<8> o, Format F, dag outs, dag ins, string asm, 
           list<dag> pattern>
      : I<o, F, outs, ins, asm, pattern>, TB, Requires<[HasMMX]>;
class MMXI64<bits<8> o, Format F, dag outs, dag ins, string asm, 
             list<dag> pattern>
      : I<o, F, outs, ins, asm, pattern>, TB, Requires<[HasMMX,In64BitMode]>;
class MMXRI<bits<8> o, Format F, dag outs, dag ins, string asm, 
            list<dag> pattern>
      : I<o, F, outs, ins, asm, pattern>, TB, REX_W, Requires<[HasMMX]>;
class MMX2I<bits<8> o, Format F, dag outs, dag ins, string asm, 
            list<dag> pattern>
      : I<o, F, outs, ins, asm, pattern>, TB, OpSize, Requires<[HasMMX]>;
class MMXIi8<bits<8> o, Format F, dag outs, dag ins, string asm, 
             list<dag> pattern>
      : Ii8<o, F, outs, ins, asm, pattern>, TB, Requires<[HasMMX]>;
class MMXID<bits<8> o, Format F, dag outs, dag ins, string asm, 
            list<dag> pattern>
      : Ii8<o, F, outs, ins, asm, pattern>, XD, Requires<[HasMMX]>;
class MMXIS<bits<8> o, Format F, dag outs, dag ins, string asm, 
            list<dag> pattern>
      : Ii8<o, F, outs, ins, asm, pattern>, XS, Requires<[HasMMX]>;