x86-64.net

Instruction

VPACKSSWB

Narrows signed words from two sources to bytes with signed saturation.

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

Forms

Every encoding of VPACKSSWB that Intel XED knows, one row per XED instruction form (iform). How to read the notation.
InstructionEncodingRequires
VPACKSSWB xmm, xmm, m128 VPACKSSWB_XMMdq_XMMdq_MEMdqVEX.128.66.0F.WIG 63 /rAVX
VPACKSSWB xmm, xmm, xmm VPACKSSWB_XMMdq_XMMdq_XMMdqVEX.128.66.0F.WIG 63 /rAVX
VPACKSSWB ymm, ymm, m256 VPACKSSWB_YMMqq_YMMqq_MEMqqVEX.256.66.0F.WIG 63 /rAVX2
VPACKSSWB ymm, ymm, ymm VPACKSSWB_YMMqq_YMMqq_YMMqqVEX.256.66.0F.WIG 63 /rAVX2
VPACKSSWB xmm {k}{z}, xmm, xmm VPACKSSWB_XMMi8_MASKmskw_XMMi16_XMMi16_AVX512EVEX.128.66.0F.WIG 63 /rAVX10.1 or AVX512BW + AVX512VL
VPACKSSWB xmm {k}{z}, xmm, m128 VPACKSSWB_XMMi8_MASKmskw_XMMi16_MEMi16_AVX512EVEX.128.66.0F.WIG 63 /rAVX10.1 or AVX512BW + AVX512VL
VPACKSSWB ymm {k}{z}, ymm, ymm VPACKSSWB_YMMi8_MASKmskw_YMMi16_YMMi16_AVX512EVEX.256.66.0F.WIG 63 /rAVX10.1 or AVX512BW + AVX512VL
VPACKSSWB ymm {k}{z}, ymm, m256 VPACKSSWB_YMMi8_MASKmskw_YMMi16_MEMi16_AVX512EVEX.256.66.0F.WIG 63 /rAVX10.1 or AVX512BW + AVX512VL
VPACKSSWB zmm {k}{z}, zmm, zmm VPACKSSWB_ZMMi8_MASKmskw_ZMMi16_ZMMi16_AVX512EVEX.512.66.0F.WIG 63 /rAVX10.1 or AVX512BW
VPACKSSWB zmm {k}{z}, zmm, m512 VPACKSSWB_ZMMi8_MASKmskw_ZMMi16_MEMi16_AVX512EVEX.512.66.0F.WIG 63 /rAVX10.1 or AVX512BW

Intrinsics

The C intrinsics of Clang 23.1.2 that compile to VPACKSSWB, 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_packs_epi16 __m128i _mm_packs_epi16(__m128i __a, __m128i __b)

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

_mm_mask_packs_epi16 __m128i _mm_mask_packs_epi16(__m128i __W, __mmask16 __M, __m128i __A, __m128i __B)

VPACKSSWB xmm {k}, xmm, xmm EVEX.128 -mavx512vl -mavx512bw

_mm_maskz_packs_epi16 __m128i _mm_maskz_packs_epi16(__mmask16 __M, __m128i __A, __m128i __B)

VPACKSSWB xmm {k}{z}, xmm, xmm EVEX.128 -mavx512vl -mavx512bw

_mm256_packs_epi16 __m256i _mm256_packs_epi16(__m256i __a, __m256i __b)

VPACKSSWB ymm, ymm, ymm VEX.256 -mavx2

_mm256_mask_packs_epi16 __m256i _mm256_mask_packs_epi16(__m256i __W, __mmask32 __M, __m256i __A, __m256i __B)

VPACKSSWB ymm {k}, ymm, ymm EVEX.256 -mavx512vl -mavx512bw

_mm256_maskz_packs_epi16 __m256i _mm256_maskz_packs_epi16(__mmask32 __M, __m256i __A, __m256i __B)

VPACKSSWB ymm {k}{z}, ymm, ymm EVEX.256 -mavx512vl -mavx512bw

_mm512_packs_epi16 __m512i _mm512_packs_epi16(__m512i __A, __m512i __B)

VPACKSSWB zmm, zmm, zmm EVEX.512 -mavx512bw

_mm512_mask_packs_epi16 __m512i _mm512_mask_packs_epi16(__m512i __W, __mmask64 __M, __m512i __A, __m512i __B)

VPACKSSWB zmm {k}, zmm, zmm EVEX.512 -mavx512bw

_mm512_maskz_packs_epi16 __m512i _mm512_maskz_packs_epi16(__mmask64 __M, __m512i __A, __m512i __B)

VPACKSSWB zmm {k}{z}, 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.