1 /* Declarations for Intel 80386 opcode table
2 Copyright (C) 2007-2020 Free Software Foundation, Inc.
4 This file is part of the GNU opcodes library.
6 This library is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3, or (at your option)
11 It is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
14 License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GAS; see the file COPYING. If not, write to the Free
18 Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
21 #include "opcode/i386.h"
30 /* Position of cpu flags bitfiled. */
34 /* i186 or better required */
36 /* i286 or better required */
38 /* i386 or better required */
40 /* i486 or better required */
42 /* i585 or better required */
44 /* i686 or better required */
46 /* CMOV Instruction support required */
48 /* FXSR Instruction support required */
50 /* CLFLUSH Instruction support required */
52 /* NOP Instruction support required */
54 /* SYSCALL Instructions support required */
56 /* Floating point support required */
58 /* i287 support required */
60 /* i387 support required */
62 /* i686 and floating point support required */
64 /* SSE3 and floating point support required */
66 /* MMX support required */
68 /* SSE support required */
70 /* SSE2 support required */
72 /* 3dnow! support required */
74 /* 3dnow! Extensions support required */
76 /* SSE3 support required */
78 /* VIA PadLock required */
80 /* AMD Secure Virtual Machine Ext-s required */
82 /* VMX Instructions required */
84 /* SMX Instructions required */
86 /* SSSE3 support required */
88 /* SSE4a support required */
90 /* LZCNT support required */
92 /* POPCNT support required */
94 /* SSE4.1 support required */
96 /* SSE4.2 support required */
98 /* AVX support required */
100 /* AVX2 support required */
102 /* Intel AVX-512 Foundation Instructions support required */
104 /* Intel AVX-512 Conflict Detection Instructions support required */
106 /* Intel AVX-512 Exponential and Reciprocal Instructions support
109 /* Intel AVX-512 Prefetch Instructions support required */
111 /* Intel AVX-512 VL Instructions support required. */
113 /* Intel AVX-512 DQ Instructions support required. */
115 /* Intel AVX-512 BW Instructions support required. */
117 /* Intel L1OM support required */
119 /* Intel K1OM support required */
121 /* Intel IAMCU support required */
123 /* Xsave/xrstor New Instructions support required */
125 /* Xsaveopt New Instructions support required */
127 /* AES support required */
129 /* PCLMUL support required */
131 /* FMA support required */
133 /* FMA4 support required */
135 /* XOP support required */
137 /* LWP support required */
139 /* BMI support required */
141 /* TBM support required */
143 /* MOVBE Instruction support required */
145 /* CMPXCHG16B instruction support required. */
147 /* EPT Instructions required */
149 /* RDTSCP Instruction support required */
151 /* FSGSBASE Instructions required */
153 /* RDRND Instructions required */
155 /* F16C Instructions required */
157 /* Intel BMI2 support required */
159 /* HLE support required */
161 /* RTM support required */
163 /* INVPCID Instructions required */
165 /* VMFUNC Instruction required */
167 /* Intel MPX Instructions required */
169 /* 64bit support available, used by -march= in assembler. */
171 /* RDRSEED instruction required. */
173 /* Multi-presisionn add-carry instructions are required. */
175 /* Supports prefetchw and prefetch instructions. */
177 /* SMAP instructions required. */
179 /* SHA instructions required. */
181 /* CLFLUSHOPT instruction required */
183 /* XSAVES/XRSTORS instruction required */
185 /* XSAVEC instruction required */
187 /* PREFETCHWT1 instruction required */
189 /* SE1 instruction required */
191 /* CLWB instruction required */
193 /* Intel AVX-512 IFMA Instructions support required. */
195 /* Intel AVX-512 VBMI Instructions support required. */
197 /* Intel AVX-512 4FMAPS Instructions support required. */
199 /* Intel AVX-512 4VNNIW Instructions support required. */
201 /* Intel AVX-512 VPOPCNTDQ Instructions support required. */
203 /* Intel AVX-512 VBMI2 Instructions support required. */
205 /* Intel AVX-512 VNNI Instructions support required. */
207 /* Intel AVX-512 BITALG Instructions support required. */
209 /* Intel AVX-512 BF16 Instructions support required. */
211 /* Intel AVX-512 VP2INTERSECT Instructions support required. */
212 CpuAVX512_VP2INTERSECT,
213 /* mwaitx instruction required */
215 /* Clzero instruction required */
217 /* OSPKE instruction required */
219 /* RDPID instruction required */
221 /* PTWRITE instruction required */
223 /* CET instructions support required */
226 /* GFNI instructions required */
228 /* VAES instructions required */
230 /* VPCLMULQDQ instructions required */
232 /* WBNOINVD instructions required */
234 /* PCONFIG instructions required */
236 /* WAITPKG instructions required */
238 /* CLDEMOTE instruction required */
240 /* MOVDIRI instruction support required */
242 /* MOVDIRR64B instruction required */
244 /* ENQCMD instruction required */
246 /* SERIALIZE instruction required */
248 /* RDPRU instruction required */
250 /* MCOMMIT instruction required */
252 /* SEV-ES instruction(s) required */
254 /* TSXLDTRK instruction required */
256 /* 64bit support required */
258 /* Not supported in the 64bit mode */
260 /* The last bitfield in i386_cpu_flags. */
264 #define CpuNumOfUints \
265 (CpuMax / sizeof (unsigned int) / CHAR_BIT + 1)
266 #define CpuNumOfBits \
267 (CpuNumOfUints * sizeof (unsigned int) * CHAR_BIT)
269 /* If you get a compiler error for zero width of the unused field,
271 #define CpuUnused (CpuMax + 1)
273 /* We can check if an instruction is available with array instead
275 typedef union i386_cpu_flags
279 unsigned int cpui186:1;
280 unsigned int cpui286:1;
281 unsigned int cpui386:1;
282 unsigned int cpui486:1;
283 unsigned int cpui586:1;
284 unsigned int cpui686:1;
285 unsigned int cpucmov:1;
286 unsigned int cpufxsr:1;
287 unsigned int cpuclflush:1;
288 unsigned int cpunop:1;
289 unsigned int cpusyscall:1;
290 unsigned int cpu8087:1;
291 unsigned int cpu287:1;
292 unsigned int cpu387:1;
293 unsigned int cpu687:1;
294 unsigned int cpufisttp:1;
295 unsigned int cpummx:1;
296 unsigned int cpusse:1;
297 unsigned int cpusse2:1;
298 unsigned int cpua3dnow:1;
299 unsigned int cpua3dnowa:1;
300 unsigned int cpusse3:1;
301 unsigned int cpupadlock:1;
302 unsigned int cpusvme:1;
303 unsigned int cpuvmx:1;
304 unsigned int cpusmx:1;
305 unsigned int cpussse3:1;
306 unsigned int cpusse4a:1;
307 unsigned int cpulzcnt:1;
308 unsigned int cpupopcnt:1;
309 unsigned int cpusse4_1:1;
310 unsigned int cpusse4_2:1;
311 unsigned int cpuavx:1;
312 unsigned int cpuavx2:1;
313 unsigned int cpuavx512f:1;
314 unsigned int cpuavx512cd:1;
315 unsigned int cpuavx512er:1;
316 unsigned int cpuavx512pf:1;
317 unsigned int cpuavx512vl:1;
318 unsigned int cpuavx512dq:1;
319 unsigned int cpuavx512bw:1;
320 unsigned int cpul1om:1;
321 unsigned int cpuk1om:1;
322 unsigned int cpuiamcu:1;
323 unsigned int cpuxsave:1;
324 unsigned int cpuxsaveopt:1;
325 unsigned int cpuaes:1;
326 unsigned int cpupclmul:1;
327 unsigned int cpufma:1;
328 unsigned int cpufma4:1;
329 unsigned int cpuxop:1;
330 unsigned int cpulwp:1;
331 unsigned int cpubmi:1;
332 unsigned int cputbm:1;
333 unsigned int cpumovbe:1;
334 unsigned int cpucx16:1;
335 unsigned int cpuept:1;
336 unsigned int cpurdtscp:1;
337 unsigned int cpufsgsbase:1;
338 unsigned int cpurdrnd:1;
339 unsigned int cpuf16c:1;
340 unsigned int cpubmi2:1;
341 unsigned int cpuhle:1;
342 unsigned int cpurtm:1;
343 unsigned int cpuinvpcid:1;
344 unsigned int cpuvmfunc:1;
345 unsigned int cpumpx:1;
346 unsigned int cpulm:1;
347 unsigned int cpurdseed:1;
348 unsigned int cpuadx:1;
349 unsigned int cpuprfchw:1;
350 unsigned int cpusmap:1;
351 unsigned int cpusha:1;
352 unsigned int cpuclflushopt:1;
353 unsigned int cpuxsaves:1;
354 unsigned int cpuxsavec:1;
355 unsigned int cpuprefetchwt1:1;
356 unsigned int cpuse1:1;
357 unsigned int cpuclwb:1;
358 unsigned int cpuavx512ifma:1;
359 unsigned int cpuavx512vbmi:1;
360 unsigned int cpuavx512_4fmaps:1;
361 unsigned int cpuavx512_4vnniw:1;
362 unsigned int cpuavx512_vpopcntdq:1;
363 unsigned int cpuavx512_vbmi2:1;
364 unsigned int cpuavx512_vnni:1;
365 unsigned int cpuavx512_bitalg:1;
366 unsigned int cpuavx512_bf16:1;
367 unsigned int cpuavx512_vp2intersect:1;
368 unsigned int cpumwaitx:1;
369 unsigned int cpuclzero:1;
370 unsigned int cpuospke:1;
371 unsigned int cpurdpid:1;
372 unsigned int cpuptwrite:1;
373 unsigned int cpuibt:1;
374 unsigned int cpushstk:1;
375 unsigned int cpugfni:1;
376 unsigned int cpuvaes:1;
377 unsigned int cpuvpclmulqdq:1;
378 unsigned int cpuwbnoinvd:1;
379 unsigned int cpupconfig:1;
380 unsigned int cpuwaitpkg:1;
381 unsigned int cpucldemote:1;
382 unsigned int cpumovdiri:1;
383 unsigned int cpumovdir64b:1;
384 unsigned int cpuenqcmd:1;
385 unsigned int cpuserialize:1;
386 unsigned int cpurdpru:1;
387 unsigned int cpumcommit:1;
388 unsigned int cpusev_es:1;
389 unsigned int cputsxldtrk:1;
390 unsigned int cpu64:1;
391 unsigned int cpuno64:1;
393 unsigned int unused:(CpuNumOfBits - CpuUnused);
396 unsigned int array[CpuNumOfUints];
399 /* Position of opcode_modifier bits. */
403 /* has direction bit. */
405 /* set if operands can be both bytes and words/dwords/qwords, encoded the
406 canonical way; the base_opcode field should hold the encoding for byte
409 /* load form instruction. Must be placed before store form. */
411 /* insn has a modrm byte. */
413 /* special case for jump insns; value has to be 1 */
419 /* special case for intersegment leaps/calls */
420 #define JUMP_INTERSEGMENT 4
421 /* absolute address for jump */
422 #define JUMP_ABSOLUTE 5
424 /* FP insn memory format bit, sized by 0x4 */
426 /* src/dest swap for floats. */
428 /* needs size prefix if in 32-bit mode */
430 /* needs size prefix if in 16-bit mode */
432 /* needs size prefix if in 64-bit mode */
435 /* check register size. */
437 /* instruction ignores operand size prefix and in Intel mode ignores
438 mnemonic size suffix check. */
440 /* default insn size depends on mode */
441 #define DEFAULTSIZE 2
443 /* any memory size */
445 /* b suffix on instruction illegal */
447 /* w suffix on instruction illegal */
449 /* l suffix on instruction illegal */
451 /* s suffix on instruction illegal */
453 /* q suffix on instruction illegal */
455 /* long double suffix on instruction illegal */
457 /* instruction needs FWAIT */
459 /* IsString provides for a quick test for string instructions, and
460 its actual value also indicates which of the operands (if any)
461 requires use of the %es segment. */
462 #define IS_STRING_ES_OP0 2
463 #define IS_STRING_ES_OP1 3
465 /* RegMem is for instructions with a modrm byte where the register
466 destination operand should be encoded in the mod and regmem fields.
467 Normally, it will be encoded in the reg field. We add a RegMem
468 flag to indicate that it should be encoded in the regmem field. */
470 /* quick test if branch instruction is MPX supported */
472 /* quick test if NOTRACK prefix is supported */
474 /* quick test for lockable instructions */
476 /* fake an extra reg operand for clr, imul and special register
477 processing for some instructions. */
479 /* An implicit xmm0 as the first operand */
481 /* The HLE prefix is OK:
482 1. With a LOCK prefix.
483 2. With or without a LOCK prefix.
484 3. With a RELEASE (0xf3) prefix.
486 #define HLEPrefixNone 0
487 #define HLEPrefixLock 1
488 #define HLEPrefixAny 2
489 #define HLEPrefixRelease 3
491 /* An instruction on which a "rep" prefix is acceptable. */
493 /* Convert to DWORD */
495 /* Convert to QWORD */
497 /* Address prefix changes register operand */
499 /* opcode is a prefix */
501 /* instruction has extension in 8 bit imm */
503 /* instruction don't need Rex64 prefix. */
505 /* deprecated fp insn, gets a warning */
507 /* insn has VEX prefix:
508 1: 128bit VEX prefix (or operand dependent).
509 2: 256bit VEX prefix.
510 3: Scalar VEX prefix.
516 /* How to encode VEX.vvvv:
517 0: VEX.vvvv must be 1111b.
518 1: VEX.NDS. Register-only source is encoded in VEX.vvvv where
519 the content of source registers will be preserved.
520 VEX.DDS. The second register operand is encoded in VEX.vvvv
521 where the content of first source register will be overwritten
523 VEX.NDD2. The second destination register operand is encoded in
524 VEX.vvvv for instructions with 2 destination register operands.
525 For assembler, there are no difference between VEX.NDS, VEX.DDS
527 2. VEX.NDD. Register destination is encoded in VEX.vvvv for
528 instructions with 1 destination register operand.
529 3. VEX.LWP. Register destination is encoded in VEX.vvvv and one
530 of the operands can access a memory location.
536 /* How the VEX.W bit is used:
537 0: Set by the REX.W bit.
538 1: VEX.W0. Should always be 0.
539 2: VEX.W1. Should always be 1.
540 3: VEX.WIG. The VEX.W bit is ignored.
546 /* VEX opcode prefix:
547 0: VEX 0x0F opcode prefix.
548 1: VEX 0x0F38 opcode prefix.
549 2: VEX 0x0F3A opcode prefix
550 3: XOP 0x08 opcode prefix.
551 4: XOP 0x09 opcode prefix
552 5: XOP 0x0A opcode prefix.
561 /* number of VEX source operands:
562 0: <= 2 source operands.
563 1: 2 XOP source operands.
564 2: 3 source operands.
566 #define XOP2SOURCES 1
567 #define VEX3SOURCES 2
569 /* Instruction with vector SIB byte:
570 1: 128bit vector register.
571 2: 256bit vector register.
572 3: 512bit vector register.
578 /* SSE to AVX support required */
580 /* No AVX equivalent */
583 /* insn has EVEX prefix:
584 1: 512bit EVEX prefix.
585 2: 128bit EVEX prefix.
586 3: 256bit EVEX prefix.
587 4: Length-ignored (LIG) EVEX prefix.
588 5: Length determined from actual operands.
597 /* AVX512 masking support:
598 1: Zeroing or merging masking depending on operands.
600 3: Both zeroing and merging masking.
602 #define DYNAMIC_MASKING 1
603 #define MERGING_MASKING 2
604 #define BOTH_MASKING 3
607 /* AVX512 broadcast support. The number of bytes to broadcast is
608 1 << (Broadcast - 1):
614 #define BYTE_BROADCAST 1
615 #define WORD_BROADCAST 2
616 #define DWORD_BROADCAST 3
617 #define QWORD_BROADCAST 4
620 /* Static rounding control is supported. */
623 /* Supress All Exceptions is supported. */
626 /* Compressed Disp8*N attribute. */
627 #define DISP8_SHIFT_VL 7
630 /* Default mask isn't allowed. */
633 /* The second operand must be a vector register, {x,y,z}mmN, where N is a multiple of 4.
634 It implicitly denotes the register group of {x,y,z}mmN - {x,y,z}mm(N + 3).
638 /* Support encoding optimization. */
647 /* ISA64: Don't change the order without other code adjustments.
648 0: Common to AMD64 and Intel64.
655 #define INTEL64ONLY 3
657 /* The last bitfield in i386_opcode_modifier. */
661 typedef struct i386_opcode_modifier
666 unsigned int modrm:1;
668 unsigned int floatmf:1;
669 unsigned int floatr:1;
671 unsigned int checkregsize:1;
672 unsigned int mnemonicsize:2;
673 unsigned int anysize:1;
674 unsigned int no_bsuf:1;
675 unsigned int no_wsuf:1;
676 unsigned int no_lsuf:1;
677 unsigned int no_ssuf:1;
678 unsigned int no_qsuf:1;
679 unsigned int no_ldsuf:1;
680 unsigned int fwait:1;
681 unsigned int isstring:2;
682 unsigned int regmem:1;
683 unsigned int bndprefixok:1;
684 unsigned int notrackprefixok:1;
685 unsigned int islockable:1;
686 unsigned int regkludge:1;
687 unsigned int implicit1stxmm0:1;
688 unsigned int hleprefixok:2;
689 unsigned int repprefixok:1;
690 unsigned int todword:1;
691 unsigned int toqword:1;
692 unsigned int addrprefixopreg:1;
693 unsigned int isprefix:1;
694 unsigned int immext:1;
695 unsigned int norex64:1;
698 unsigned int vexvvvv:2;
700 unsigned int vexopcode:3;
701 unsigned int vexsources:2;
702 unsigned int vecsib:2;
703 unsigned int sse2avx:1;
704 unsigned int noavx:1;
706 unsigned int masking:2;
707 unsigned int broadcast:3;
708 unsigned int staticrounding:1;
710 unsigned int disp8memshift:3;
711 unsigned int nodefmask:1;
712 unsigned int implicitquadgroup:1;
713 unsigned int optimize:1;
714 unsigned int attmnemonic:1;
715 unsigned int attsyntax:1;
716 unsigned int intelsyntax:1;
717 unsigned int isa64:2;
718 } i386_opcode_modifier;
720 /* Operand classes. */
722 #define CLASS_WIDTH 4
726 Reg, /* GPRs and FP regs, distinguished by operand size */
727 SReg, /* Segment register */
728 RegCR, /* Control register */
729 RegDR, /* Debug register */
730 RegTR, /* Test register */
731 RegMMX, /* MMX register */
732 RegSIMD, /* XMM/YMM/ZMM registers, distinguished by operand size */
733 RegMask, /* Vector Mask register */
734 RegBND, /* Bound register */
737 /* Special operand instances. */
739 #define INSTANCE_WIDTH 3
740 enum operand_instance
743 Accum, /* Accumulator %al/%ax/%eax/%rax/%st(0)/%xmm0 */
744 RegC, /* %cl / %cx / %ecx / %rcx, e.g. register to hold shift count */
745 RegD, /* %dl / %dx / %edx / %rdx, e.g. register to hold I/O port addr */
746 RegB, /* %bl / %bx / %ebx / %rbx */
749 /* Position of operand_type bits. */
753 /* Class and Instance */
754 ClassInstance = CLASS_WIDTH + INSTANCE_WIDTH - 1,
755 /* 1 bit immediate */
757 /* 8 bit immediate */
759 /* 8 bit immediate sign extended */
761 /* 16 bit immediate */
763 /* 32 bit immediate */
765 /* 32 bit immediate sign extended */
767 /* 64 bit immediate */
769 /* 8bit/16bit/32bit displacements are used in different ways,
770 depending on the instruction. For jumps, they specify the
771 size of the PC relative displacement, for instructions with
772 memory operand, they specify the size of the offset relative
773 to the base register, and for instructions with memory offset
774 such as `mov 1234,%al' they specify the size of the offset
775 relative to the segment base. */
776 /* 8 bit displacement */
778 /* 16 bit displacement */
780 /* 32 bit displacement */
782 /* 32 bit signed displacement */
784 /* 64 bit displacement */
786 /* Register which can be used for base or index in memory operand. */
790 /* WORD size. 2 byte */
792 /* DWORD size. 4 byte */
794 /* FWORD size. 6 byte */
796 /* QWORD size. 8 byte */
798 /* TBYTE size. 10 byte */
806 /* Unspecified memory size. */
809 /* The number of bits in i386_operand_type. */
813 #define OTNumOfUints \
814 ((OTNum - 1) / sizeof (unsigned int) / CHAR_BIT + 1)
815 #define OTNumOfBits \
816 (OTNumOfUints * sizeof (unsigned int) * CHAR_BIT)
818 /* If you get a compiler error for zero width of the unused field,
820 #define OTUnused OTNum
822 typedef union i386_operand_type
826 unsigned int class:CLASS_WIDTH;
827 unsigned int instance:INSTANCE_WIDTH;
830 unsigned int imm8s:1;
831 unsigned int imm16:1;
832 unsigned int imm32:1;
833 unsigned int imm32s:1;
834 unsigned int imm64:1;
835 unsigned int disp8:1;
836 unsigned int disp16:1;
837 unsigned int disp32:1;
838 unsigned int disp32s:1;
839 unsigned int disp64:1;
840 unsigned int baseindex:1;
843 unsigned int dword:1;
844 unsigned int fword:1;
845 unsigned int qword:1;
846 unsigned int tbyte:1;
847 unsigned int xmmword:1;
848 unsigned int ymmword:1;
849 unsigned int zmmword:1;
850 unsigned int unspecified:1;
852 unsigned int unused:(OTNumOfBits - OTUnused);
855 unsigned int array[OTNumOfUints];
858 typedef struct insn_template
860 /* instruction name sans width suffix ("mov" for movl insns) */
863 /* base_opcode is the fundamental opcode byte without optional
865 unsigned int base_opcode;
866 #define Opcode_D 0x2 /* Direction bit:
867 set if Reg --> Regmem;
868 unset if Regmem --> Reg. */
869 #define Opcode_FloatR 0x8 /* Bit to swap src/dest for float insns. */
870 #define Opcode_FloatD 0x400 /* Direction bit for float insns. */
871 #define Opcode_SIMD_FloatD 0x1 /* Direction bit for SIMD fp insns. */
872 #define Opcode_SIMD_IntD 0x10 /* Direction bit for SIMD int insns. */
874 /* extension_opcode is the 3 bit extension for group <n> insns.
875 This field is also used to store the 8-bit opcode suffix for the
876 AMD 3DNow! instructions.
877 If this template has no extension opcode (the usual case) use None
879 unsigned short extension_opcode;
880 #define None 0xffff /* If no extension_opcode is possible. */
883 unsigned char opcode_length;
885 /* how many operands */
886 unsigned char operands;
888 /* cpu feature flags */
889 i386_cpu_flags cpu_flags;
891 /* the bits in opcode_modifier are used to generate the final opcode from
892 the base_opcode. These bits also are used to detect alternate forms of
893 the same instruction */
894 i386_opcode_modifier opcode_modifier;
896 /* operand_types[i] describes the type of operand i. This is made
897 by OR'ing together all of the possible type masks. (e.g.
898 'operand_types[i] = Reg|Imm' specifies that operand i can be
899 either a register or an immediate operand. */
900 i386_operand_type operand_types[MAX_OPERANDS];
904 extern const insn_template i386_optab[];
906 /* these are for register name --> number & type hash lookup */
910 i386_operand_type reg_type;
911 unsigned char reg_flags;
912 #define RegRex 0x1 /* Extended register. */
913 #define RegRex64 0x2 /* Extended 8 bit register. */
914 #define RegVRex 0x4 /* Extended vector register. */
915 unsigned char reg_num;
916 #define RegIP ((unsigned char ) ~0)
917 /* EIZ and RIZ are fake index registers. */
918 #define RegIZ (RegIP - 1)
919 /* FLAT is a fake segment register (Intel mode). */
920 #define RegFlat ((unsigned char) ~0)
921 signed char dw2_regnum[2];
922 #define Dw2Inval (-1)
926 /* Entries in i386_regtab. */
929 #define REGNAM_EAX 41
931 extern const reg_entry i386_regtab[];
932 extern const unsigned int i386_regtab_size;
937 unsigned int seg_prefix;
941 extern const seg_entry cs;
942 extern const seg_entry ds;
943 extern const seg_entry ss;
944 extern const seg_entry es;
945 extern const seg_entry fs;
946 extern const seg_entry gs;