Definitions

repz

X86 instruction listings

The x86 instruction set has undergone numerous changes over time. Most of them were to add new functionality to the instruction set.

x86 integer instructions

This is the full 8086/8088 instruction set, but most, if not all of these instructions are available in 32-bit mode, they just operate on 32-bit registers (eax, ebx, etc) and values instead of their 16-bit (ax, bx, etc) counterparts. See also x86 assembly language for a quick tutorial for this chip.

Original 8086/8088 instructions

Instruction Meaning Notes
AAA ASCII adjust AL after addition used with unpacked binary coded decimal
AAD ASCII adjust AX before division buggy in the original instruction set, but "fixed" in the NEC V20, causing a number of incompatibilities
AAM ASCII adjust AX after multiplication
AAS ASCII adjust AL after subtraction
ADC Add with carry
ADD Add
AND Logical AND
CALL Call procedure
CBW Convert byte to word
CLC Clear carry flag
CLD Clear direction flag
CLI Clear interrupt flag
CMC Complement carry flag
CMP Compare operands
CMPSB Compare bytes in memory
CMPSW Compare words
CWD Convert word to doubleword
DAA Decimal adjust AL after addition (used with packed binary coded decimal)
DAS Decimal adjust AL after subtraction
DEC Decrement by 1
DIV Unsigned divide
ESC Used with floating-point unit
HLT Enter halt state
IDIV Signed divide
IMUL Signed multiply
IN Input from port
INC Increment by 1
INT Call to interrupt
INTO Call to interrupt if overflow
IRET Return from interrupt
Jxx Jump if condition (JA, JAE, JB, JBE, JC, JCXZ, JE, JG, JGE, JL, JLE, JNA, JNAE, JNB, JNBE, JNC, JNE, JNG, JNGE, JNL, JNLE, JNO, JNP, JNS, JNZ, JO, JP, JPE, JPO, JS, JZ)
JMP Jump
LAHF Load flags into AH register
LDS Load pointer using DS
LEA Load Effective Address
LES Load ES with pointer
LOCK Assert BUS LOCK# signal (for multiprocessing)
LODSB Load byte
LODSW Load word
LOOP/LOOPx Loop control (LOOPE, LOOPNE, LOOPNZ, LOOPZ)
MOV Move
MOVSB Move byte from string to string
MOVSW Move word from string to string
MUL Unsigned multiply
NEG Two's complement negation
NOP No operation opcode (0x90) equivalent to XCHG EAX, EAX
NOT Negate the operand, logical NOT
OR Logical OR
OUT Output to port
POP Pop data from stack (Does only work with register CS on 8086/8088.)
POPF Pop data into flags register
PUSH Push data onto stack
PUSHF Push flags onto stack
RCL Rotate left (with carry)
RCR Rotate right (with carry)
REPxx Repeat CMPS/MOVS/SCAS/STOS (REP, REPE, REPNE, REPNZ, REPZ)
RET Return from procedure
RETN Return from near procedure
RETF Return from far procedure
ROL Rotate left
ROR Rotate right
SAHF Store AH into flags
SAL Shift Arithmetically left (signed shift left)
SAR Shift Arithmetically right (signed shift right)
SBB Subtraction with borrow
SCASB Compare byte string
SCASW Compare word string
SHL Shift left (unsigned shift left)
SHR Shift right (unsigned shift right)
STC Set carry flag
STD Set direction flag
STI Set interrupt flag
STOSB Store byte in string
STOSW Store word in string
SUB Subtraction
TEST Logical compare (AND)
WAIT Wait until not busy Waits until BUSY# pin is inactive (used with floating-point unit)
XCHG Exchange data
XLAT Table look-up translation
XOR Exclusive OR

Added in specific processors

Added with 80186/80188

Instruction Meaning Notes
BOUND Check array index against bounds raises software interrupt 5 if test fails
ENTER Enter stack frame equivalent to
PUSH BP MOV BP, SP
INS Input from port to string equivalent to
IN (E)AX, DX
MOV ES:[(E)DI], (E)AX
LEAVE Leave stack frame equivalent to
MOV SP, BP POP BP
OUTS Output string to port equivalent to
MOV (E)AX, DS:[(E)SI]
OUT DX, (E)AX
POPA Pop all general purpose registers from stack equivalent to
POP DI, SI, BP, SP, BX, DX, CX, AX
PUSHA Push all general purpose registers onto stack equivalent to
PUSH DI, SI, BP, SP, BX, DX, CX, AX

Added with 80286

Instruction Meaning Notes
ARPL Adjust RPL field of selector
CLTS Clear task-switched flag in register CR0
LAR Load access rights byte
LGDT Load global descriptor table
LIDT Load interrupt descriptor table
LLDT Load local descriptor table
LMSW Load machine status word
LOADALL Load all CPU registers, including internal ones such as GDT Undocumented, (80)286 and 386 only
LSL Load segment limit
LTR Load task register
SGDT Store global descriptor table
SIDT Store interrupt descriptor table
SLDT Store local descriptor table
SMSW Store machine status word
STR Store task register
VERR Verify a segment for reading
VERW Verify a segment for writing

Added with 80386

Instruction Meaning Notes
BSF Bit scan forward
BSR Bit scan reverse
BT Bit test
BTC Bit test and complement
BTR Bit test and reset
BTS Bit test and set
CDQ Convert double-word to quad-word Sign-extends EAX into EDX, forming the quad-word EDX:EAX. Since (I)DIV uses EDX:EAX as its input, CDQ must be called after setting EAX if EDX is not manually initialized (as in 64/32 division) before (I)DIV.
CMPSD Compare string double-word Compares ES:[(E)DI] with DS:[SI]
CWDE Convert word to double-word Unlike CWD, CWDE sign-extends AX to EAX instead of AX to DX:AX
INSB, INSW, INSD Input from port to string with explicit size same as INS
IRETx Interrupt return; D suffix means 32-bit return, F suffix means do not generate epilogue code (i.e. LEAVE instruction) Use IRETD rather than IRET in 32-bit situations
JCXZ, JECXZ Jump if register (E)CX is zero
LFS, LGS Load far pointer
LSS Load stack segment
LODSW, LODSD Load string can be prefixed with REP
LOOPW, LOOPD Loop Loop; counter register is (E)CX is counter
LOOPEW, LOOPED Loop while equal
LOOPZW, LOOPZD Loop while zero
LOOPNEW, LOOPNED Loop while not equal
LOOPNZW, LOOPNZD Loop while not zero
MOVSW, MOVSD Move data from string to string
MOVSX Move with sign-extend
MOVZX Move with zero-extend
POPAD Pop all double-word (32-bit) registers from stack Does not pop register ESP off of stack
POPFD Pop data into EFLAGS register
PUSHAD Push all double-word (32-bit registers) onto stack
PUSHFD Push EFLAGS register onto stack
SCASD Scan string data dbouble-word
SETA, SETAE, SETB, SETBE, SETC, SETE, SETG, SETGE, SETL, SETLE, SETNA, SETNAE, SETNB, SETNBE, SETNC, SETNE, SETNG, SETNGE, SETNL, SETNLE, SETNO, SETNP, SETNS, SETNZ, SETO, SETP, SETPE, SETPO, SETS, SETZ Set byte to one on condition
SHLD Shift left double-word
SHRD Shift right double-word
STOSx Store string

Added with 80486

Instruction Meaning Notes
BSWAP Byte Swap Only works for 32 bit registers.
CMPXCHG CoMPare and eXCHanGe
CPUID CPU IDentification
INVD Invalidate Internal Caches
INVLPG Invalidate TLB Entry
WBINVD Write Back and Invalidate Cache
XADD Exchange and Add

Added with Pentium

Instruction Meaning Notes
CMPXCHG8B CoMPare and eXCHanGe 8 bytes
RDMSR ReaD from Model-Specific Register
RDTSC ReaD Time Stamp Counter
WRMSR WRite to Model-Specific Register

Added with Pentium MMX

RDPMC*

Added with Pentium Pro

Conditional MOV: CMOVA, CMOVAE, CMOVB, CMOVBE, CMOVC, CMOVE, CMOVG, CMOVGE, CMOVL, CMOVLE, CMOVNA, CMOVNAE, CMOVNB, CMOVNBE, CMOVNC, CMOVNE, CMOVNG, CMOVNGE, CMOVNL, CMOVNLE, CMOVNO, CMOVNP, CMOVNS, CMOVNZ, CMOVO, CMOVP, CMOVPE, CMOVPO, CMOVS, CMOVZ, SYSENTER (SYStem call ENTER), SYSEXIT (SYStem call EXIT), RDPMC*, UD2

Added with AMD K6-2

SYSCALL, SYSRET (functionally equivalent to SYSENTER and SYSEXIT)

Added with SSE

MASKMOVQ, MOVNTPS, MOVNTQ, PREFETCH0, PREFETCH1, PREFETCH2, PREFETCHNTA, SFENCE (for Cacheability and Memory Ordering)

Added with SSE2

CLFLUSH, LFENCE, MASKMOVDQU, MFENCE, MOVNTDQ, MOVNTI, MOVNTPD, PAUSE (for Cacheability)

Added with SSE3

LDDQU (for Video Encoding)

MONITOR, MWAIT (for thread synchronization; only on processors supporting Hyper-threading and some dual-core processors like Core 2, Phenom and others)

Added with Intel VT

VMPTRLD, VMPTRST, VMCLEAR, VMREAD, VMWRITE, VMCALL, VMLAUNCH, VMRESUME, VMXOFF, VMXON

Added with AMD-V

CLGI, SKINIT, STGI, VMLOAD, VMMCALL, VMRUN, VMSAVE (SVM instructions of AMD-V)

Added with x86-64

CMPXCHG16B (CoMPaRe and eXCHanGe 16 bytes), RDTSCP (ReaD Time Stamp Counter P?)

Added with SSE4a

LZCNT, POPCNT (POPulation CouNT) - advanced bit manipulation

x87 floating-point instructions

Original 8087 instructions

F2XM1, FABS, FADD, FADDP, FBLD, FBSTP, FCHS, FCLEX, FCOM, FCOMP, FCOMPP, FDECSTP, FDISI, FDIV, FDIVP, FDIVR, FDIVRP, FENI, FFREE, FIADD, FICOM, FICOMP, FIDIV, FIDIVR, FILD, FIMUL, FINCSTP, FINIT, FIST, FISTP, FISUB, FISUBR, FLD, FLD1, FLDCW, FLDENV, FLDENVW, FLDL2E, FLDL2T, FLDLG2, FLDLN2, FLDPI, FLDZ, FMUL, FMULP, FNCLEX, FNDISI, FNENI, FNINIT, FNOP, FNSAVE, FNSAVEW, FNSTCW, FNSTENV, FNSTENVW, FNSTSW, FPATAN, FPREM, FPTAN, FRNDINT, FRSTOR, FRSTORW, FSAVE, FSAVEW, FSCALE, FSQRT, FST, FSTCW, FSTENV, FSTENVW, FSTP, FSTSW, FSUB, FSUBP, FSUBR, FSUBRP, FTST, FWAIT, FXAM, FXCH, FXTRACT, FYL2X, FYL2XP1

Added in specific processors

Added with 80287

FSETPM

Added with 80387

FCOS, FLDENVD, FNSAVED, FNSTENVD, FPREM1, FRSTORD, FSAVED, FSIN, FSINCOS, FSTENVD, FUCOM, FUCOMP, FUCOMPP

Added with Pentium Pro

  • FCMOV variants: FCMOVB, FCMOVBE, FCMOVE, FCMOVNB, FCMOVNBE, FCMOVNE, FCMOVNU, FCMOVU
  • FCOMI variants: FCOMI, FCOMIP, FUCOMI, FUCOMIP

Added with SSE

  • FXRSTOR*, FXSAVE*
  • Also supported on later Pentium IIs, though they do not contain SSE support

Added with SSE3

FISTTP (x87 to integer conversion)

Undocumented instructions

FFREEP performs FFREE ST(i) and pop stack

SIMD instructions

MMX instructions

added with Pentium MMX EMMS, MOVD, MOVQ, PACKSSDW, PACKSSWB, PACKUSWB, PADDB, PADDD, PADDSB, PADDSW, PADDUSB, PADDUSW, PADDW, PAND, PANDN, PCMPEQB, PCMPEQD, PCMPEQW, PCMPGTB, PCMPGTD, PCMPGTW, PMADDWD, PMULHW, PMULLW, POR, PSLLD, PSLLQ, PSLLW, PSRAD, PSRAW, PSRLD, PSRLQ, PSRLW, PSUBB, PSUBD, PSUBSB, PSUBSW, PSUBUSB, PSUBUSW, PSUBW, PUNPCKHBW, PUNPCKHDQ, PUNPCKHWD, PUNPCKLBW, PUNPCKLDQ, PUNPCKLWD, PXOR

MMX+ instructions

added with Athlon

Same as the SSE SIMD Integer Instructions which operated on MMX registers.

EMMX instructions

added with 6x86MX from Cyrix, deprecated now

PAVEB, PADDSIW, PMAGW, PDISTIB, PSUBSIW, PMVZB, PMULHRW, PMVNZB, PMVLZB, PMVGEZB, PMULHRIW, PMACHRIW

3DNow! instructions

added with K6-2

FEMMS, PAVGUSB, PF2ID, PFACC, PFADD, PFCMPEQ, PFCMPGE, PFCMPGT, PFMAX, PFMIN, PFMUL, PFRCP, PFRCPIT1, PFRCPIT2, PFRSQIT1, PFRSQRT, PFSUB, PFSUBR, PI2FD, PMULHRW, PREFETCH, PREFETCHW

3DNow!+ instructions

added with Athlon

PF2IW, PFNACC, PFPNACC, PI2FW, PSWAPD

added with Geode GX

PFRSQRTV, PFRCPV

SSE instructions

added with Pentium III also see integer instruction added with Pentium III

SSE SIMD Floating-Point Instructions

ADDPS, ADDSS, CMPPS, CMPSS, COMISS, CVTPI2PS, CVTPS2PI, CVTSI2SS, CVTSS2SI, CVTTPS2PI, CVTTSS2SI, DIVPS, DIVSS, LDMXCSR, MAXPS, MAXSS, MINPS, MINSS, MOVAPS, MOVHLPS, MOVHPS, MOVLHPS, MOVLPS, MOVMSKPS, MOVNTPS, MOVSS, MOVUPS, MULPS, MULSS, RCPPS, RCPSS, RSQRTPS, RSQRTSS, SHUFPS, SQRTPS, SQRTSS, STMXCSR, SUBPS, SUBSS, UCOMISS, UNPCKHPS, UNPCKLPS

SSE SIMD Integer Instructions

ANDNPS, ANDPS, ORPS, PAVGB, PAVGW, PEXTRW, PINSRW, PMAXSW, PMAXUB, PMINSW, PMINUB, PMOVMSKB, PMULHUW, PSADBW, PSHUFW, XORPS

SSE2 instructions

added with Pentium 4 also see integer instructions added with Pentium 4

SSE2 SIMD Floating-Point Instructions

ADDPD, ADDSD, ANDNPD, ANDPD, CMPPD, CMPSD*, COMISD, CVTDQ2PD, CVTDQ2PS, CVTPD2DQ, CVTPD2PI, CVTPD2PS, CVTPI2PD, CVTPS2DQ, CVTPS2PD, CVTSD2SI, CVTSD2SS, CVTSI2SD, CVTSS2SD, CVTTPD2DQ, CVTTPD2PI, CVTPS2DQ, CVTTSD2SI, DIVPD, DIVSD, MAXPD, MAXSD, MINPD, MINSD, MOVAPD, MOVHPD, MOVLPD, MOVMSKPD, MOVSD*, MOVUPD, MULPD, MULSD, ORPD, SHUFPD, SQRTPD, SQRTSD, SUBPD, SUBSD, UCOMISD, UNPCKHPD, UNPCKLPD, XORPD

SSE2 SIMD Integer Instructions

MOVDQ2Q, MOVDQA, MOVDQU, MOVQ2DQ, PADDQ, PSUBQ, PMULUDQ, PSHUFHW, PSHUFLW, PSHUFD, PSLLDQ, PSRLDQ, PUNPCKHQDQ, PUNPCKLQDQ

SSE3 instructions

added with Pentium 4 supporting SSE3 also see integer and floating-point instructions added with Pentium 4 SSE3

SSE3 SIMD Floating-Point Instructions

  • ADDSUBPD, ADDSUBPS (for Complex Arithmetic)
  • HADDPD, HADDPS, HSUBPD, HSUBPS (for Graphics)
  • MOVDDUP, MOVSHDUP, MOVSLDUP (for Complex Arithmetic)

SSSE3 instructions

added with Xeon 5100 series and initial Core 2

  • PSIGNW, PSIGND, PSIGNB
  • PSHUFB
  • PMULHRSW, PMADDUBSW
  • PHSUBW, PHSUBSW, PHSUBD
  • PHADDW, PHADDSW, PHADDD
  • PALIGNR
  • PABSW, PABSD, PABSB

SSE4 instructions

SSE4.1

added with Core 2 x9000 series

  • MPSADBW
  • PHMINPOSUW
  • PMULLD, PMULDQ
  • DPPS, DPPD
  • BLENDPS, BLENDPD, BLENDVPS, BLENDVPD, PBLENDVB, PBLENDW
  • PMINSB, PMAXSB, PMINUW, PMAXUW, PMINUD, PMAXUD, PMINSD, PMAXSD
  • ROUNDPS, ROUNDSS, ROUNDPD, ROUNDSD
  • INSERTPS, PINSRB, PINSRD/PINSRQ, EXTRACTPS, PEXTRB, PEXTRW, PEXTRD/PEXTRQ
  • PMOVSXBW, PMOVZXBW, PMOVSXBD, PMOVZXBD, PMOVSXBQ, PMOVZXBQ, PMOVSXWD, PMOVZXWD, PMOVSXWQ, PMOVZXWQ, PMOVSXDQ, *PMOVZXDQ
  • PTEST
  • PCMPEQQ
  • PACKUSDW
  • MOVNTDQA

SSE4a

added with Phenom processors

  • EXTRQ/INSERTQ
  • MOVNTSD/MOVNTSS

SSE4.2

to be added with Nehalem processors

  • CRC32
  • PCMPESTRI
  • PCMPESTRM
  • PCMPISTRI
  • PCMPISTRM
  • PCMPGTQ

Undocumented instructions

The x86 CPUs contain undocumented instructions which are implemented on the chips but never listed in any official available document.

mnemonic opcode description undoc status
AAM imm8 D4 imm8 Divide AL by imm8, put the quotient in AH, and the remainder in AL Available beginning with 8086, documented since Pentium (earlier documentation lists no arguments)
AAD imm8 D5 imm8 Multiplication counterpart of AAM Available beginning with 8086, documented since Pentium (earlier documentation lists no arguments)
SALC D6 Set AL depending on the value of the Carry Flag Available beginning with 8086, but only documented since Pentium Pro.
ICEBP F1 Single byte single-step exception / Invoke ICE Available beginning with 80386, documented (as INT1) since Pentium Pro
LOADALL 0F 05 Loads All Registers from Memory Address 0x000800H Only available on 80286
LOADALLD 0F 07 Loads All Registers from Memory Address ES:EDI Only available on 80386
POP CS 0F Pop top of the stack into CS Segment register Only available on 8086. Beginning with 80286 this opcode is used as a prefix for 2-Byte-Instructions

References

External links

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