x86-64.net

Instruction

VPCMPEQB

Compares packed bytes for equality; the VEX form writes all-ones or zero elements, the EVEX form a mask register.

Extensions
Forms
10 (4 VEX, 6 EVEX)
Data
Intel XED v2026.08.23

Forms

Every encoding of VPCMPEQB that Intel XED knows, one row per XED instruction form (iform). How to read the notation.
InstructionEncodingRequires
VPCMPEQB xmm, xmm, m128 VPCMPEQB_XMMdq_XMMdq_MEMdqVEX.128.66.0F.WIG 74 /rAVX
VPCMPEQB xmm, xmm, xmm VPCMPEQB_XMMdq_XMMdq_XMMdqVEX.128.66.0F.WIG 74 /rAVX
VPCMPEQB ymm, ymm, m256 VPCMPEQB_YMMqq_YMMqq_MEMqqVEX.256.66.0F.WIG 74 /rAVX2
VPCMPEQB ymm, ymm, ymm VPCMPEQB_YMMqq_YMMqq_YMMqqVEX.256.66.0F.WIG 74 /rAVX2
VPCMPEQB k {k}, xmm, xmm VPCMPEQB_MASKmskw_MASKmskw_XMMu8_XMMu8_AVX512EVEX.128.66.0F.WIG 74 /rAVX10.1 or AVX512BW + AVX512VL
VPCMPEQB k {k}, xmm, m128 VPCMPEQB_MASKmskw_MASKmskw_XMMu8_MEMu8_AVX512EVEX.128.66.0F.WIG 74 /rAVX10.1 or AVX512BW + AVX512VL
VPCMPEQB k {k}, ymm, ymm VPCMPEQB_MASKmskw_MASKmskw_YMMu8_YMMu8_AVX512EVEX.256.66.0F.WIG 74 /rAVX10.1 or AVX512BW + AVX512VL
VPCMPEQB k {k}, ymm, m256 VPCMPEQB_MASKmskw_MASKmskw_YMMu8_MEMu8_AVX512EVEX.256.66.0F.WIG 74 /rAVX10.1 or AVX512BW + AVX512VL
VPCMPEQB k {k}, zmm, zmm VPCMPEQB_MASKmskw_MASKmskw_ZMMu8_ZMMu8_AVX512EVEX.512.66.0F.WIG 74 /rAVX10.1 or AVX512BW
VPCMPEQB k {k}, zmm, m512 VPCMPEQB_MASKmskw_MASKmskw_ZMMu8_MEMu8_AVX512EVEX.512.66.0F.WIG 74 /rAVX10.1 or AVX512BW

Intrinsics

The C intrinsics of Clang 23.1.2 that compile to VPCMPEQB, each with the form it compiles to and the Clang options it needs. The forms come from compiling every intrinsic and decoding the result with Intel XED; all intrinsics A–Z explains the method.

IntrinsicCompiles to
_mm_cmpeq_epi8 __m128i _mm_cmpeq_epi8(__m128i __a, __m128i __b)

VPCMPEQB xmm, xmm, xmm VEX.128 -mavxwith AVX enabled

_mm_cmpeq_epi8_mask __mmask16 _mm_cmpeq_epi8_mask(__m128i A, __m128i B)

VPCMPEQB k, xmm, xmm EVEX.128 -mavx512vl -mavx512bw

_mm_mask_cmpeq_epi8_mask __mmask16 _mm_mask_cmpeq_epi8_mask(__mmask16 k, __m128i A, __m128i B)

VPCMPEQB k, xmm, xmm EVEX.128 -mavx512vl -mavx512bw

_mm_cmpeq_epu8_mask __mmask16 _mm_cmpeq_epu8_mask(__m128i A, __m128i B)

VPCMPEQB k, xmm, xmm EVEX.128 -mavx512vl -mavx512bw

_mm_mask_cmpeq_epu8_mask __mmask16 _mm_mask_cmpeq_epu8_mask(__mmask16 k, __m128i A, __m128i B)

VPCMPEQB k, xmm, xmm EVEX.128 -mavx512vl -mavx512bw

_mm256_cmpeq_epi8 __m256i _mm256_cmpeq_epi8(__m256i __a, __m256i __b)

VPCMPEQB ymm, ymm, ymm VEX.256 -mavx2

_mm256_cmpeq_epi8_mask __mmask32 _mm256_cmpeq_epi8_mask(__m256i A, __m256i B)

VPCMPEQB k, ymm, ymm EVEX.256 -mavx512vl -mavx512bw

_mm256_mask_cmpeq_epi8_mask __mmask32 _mm256_mask_cmpeq_epi8_mask(__mmask32 k, __m256i A, __m256i B)

VPCMPEQB k, ymm, ymm EVEX.256 -mavx512vl -mavx512bw

_mm256_cmpeq_epu8_mask __mmask32 _mm256_cmpeq_epu8_mask(__m256i A, __m256i B)

VPCMPEQB k, ymm, ymm EVEX.256 -mavx512vl -mavx512bw

_mm256_mask_cmpeq_epu8_mask __mmask32 _mm256_mask_cmpeq_epu8_mask(__mmask32 k, __m256i A, __m256i B)

VPCMPEQB k, ymm, ymm EVEX.256 -mavx512vl -mavx512bw

_mm512_cmpeq_epi8_mask __mmask64 _mm512_cmpeq_epi8_mask(__m512i A, __m512i B)

VPCMPEQB k, zmm, zmm EVEX.512 -mavx512bw

_mm512_mask_cmpeq_epi8_mask __mmask64 _mm512_mask_cmpeq_epi8_mask(__mmask64 k, __m512i A, __m512i B)

VPCMPEQB k, zmm, zmm EVEX.512 -mavx512bw

_mm512_cmpeq_epu8_mask __mmask64 _mm512_cmpeq_epu8_mask(__m512i A, __m512i B)

VPCMPEQB k, zmm, zmm EVEX.512 -mavx512bw

_mm512_mask_cmpeq_epu8_mask __mmask64 _mm512_mask_cmpeq_epu8_mask(__mmask64 k, __m512i A, __m512i B)

VPCMPEQB k, zmm, zmm EVEX.512 -mavx512bw

CPUID and processors

Each form belongs to an XED ISA set. A form can be used when the processor reports every CPUID bit of one of its ISA set's alternatives.

CPUID requirements and processors of the XED ISA sets above. Alternatives are separated by “or”; processors follow XED’s chip model, which covers AMD processors up to Zen 2.
ISA setCPUIDProcessors in XED
AVX

AVX
CPUID.01H:ECX[28] AVX

Sandy Bridge, Ivy Bridge, Haswell, Broadwell, Skylake, Comet Lake, Cannon Lake, Ice Lake (client), Tiger Lake, Alder Lake, Arrow Lake, Panther Lake, Nova Lake, Skylake-SP, Cascade Lake, Cooper Lake, Ice Lake (server), Sapphire Rapids, Emerald Rapids, Granite Rapids, Diamond Rapids, Sierra Forest, Clearwater Forest, Knights Landing, Knights Mill, Bulldozer, Piledriver, Zen, Zen+, Zen 2
AVX2

AVX2
CPUID.(EAX=07H,ECX=0):EBX[5] AVX2

Haswell, Broadwell, Skylake, Comet Lake, Cannon Lake, Ice Lake (client), Tiger Lake, Alder Lake, Arrow Lake, Panther Lake, Nova Lake, Skylake-SP, Cascade Lake, Cooper Lake, Ice Lake (server), Sapphire Rapids, Emerald Rapids, Granite Rapids, Diamond Rapids, Sierra Forest, Clearwater Forest, Knights Landing, Knights Mill, Zen, Zen+, Zen 2
AVX512BW_128

AVX10.1
CPUID.(EAX=07H,ECX=1):EDX[19] AVX10
CPUID.(EAX=24H,ECX=0):EBX[7:0] ≥ 1 AVX10 version

or

AVX512BW + AVX512VL
CPUID.(EAX=07H,ECX=0):EBX[30] AVX512BW
CPUID.(EAX=07H,ECX=0):EBX[31] AVX512VL

Cannon Lake, Ice Lake (client), Tiger Lake, Nova Lake, Skylake-SP, Cascade Lake, Cooper Lake, Ice Lake (server), Sapphire Rapids, Emerald Rapids, Granite Rapids, Diamond Rapids
AVX512BW_256

AVX10.1
CPUID.(EAX=07H,ECX=1):EDX[19] AVX10
CPUID.(EAX=24H,ECX=0):EBX[7:0] ≥ 1 AVX10 version

or

AVX512BW + AVX512VL
CPUID.(EAX=07H,ECX=0):EBX[30] AVX512BW
CPUID.(EAX=07H,ECX=0):EBX[31] AVX512VL

Cannon Lake, Ice Lake (client), Tiger Lake, Nova Lake, Skylake-SP, Cascade Lake, Cooper Lake, Ice Lake (server), Sapphire Rapids, Emerald Rapids, Granite Rapids, Diamond Rapids
AVX512BW_512

AVX10.1
CPUID.(EAX=07H,ECX=1):EDX[19] AVX10
CPUID.(EAX=24H,ECX=0):EBX[7:0] ≥ 1 AVX10 version

or

AVX512BW
CPUID.(EAX=07H,ECX=0):EBX[30] AVX512BW

Cannon Lake, Ice Lake (client), Tiger Lake, Nova Lake, Skylake-SP, Cascade Lake, Cooper Lake, Ice Lake (server), Sapphire Rapids, Emerald Rapids, Granite Rapids, Diamond Rapids

More AVX10.1 instructions

All 686 AVX10.1 instructions

Sources

  1. Intel XED v2026.08.23 (commit 0bcb6237345c): forms, encodings, ISA sets, CPUID bits and chip model.
  2. Clang's x86 intrinsic headers, LLVM 23.1.2 (commit 85ac56026243): the intrinsics, their signatures and doc comments, and the Clang of that release, which compiled each of them.
  3. Intel Advanced Vector Extensions 10.2 Architecture Specification, revision 6.0 (361050-006, January 2026)

The tables are derived from Intel XED, Copyright Intel Corporation, licensed under the Apache License 2.0; x86-64.net converted and reformatted them. The intrinsics and their signatures come from Clang, part of the LLVM Project, licensed under the Apache License 2.0 with LLVM Exceptions. The text is our own.