x86
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AVX-512 BFloat16 Instructions (AVX512_BF16) is an x86 extension, part of AVX-512, designed to accelerate neural network-based algorithms by performing dot-product on bfloat16.

Overview

The AVX512 BF16 x86 extension extends AVX-512 Foundation by introducing three new instructions for converting and operating on bfloat16.

• VCVTNE2PS2BF16 - Convert two SIMD registers with packed single-precision floating point values to bfloat16 packed in a single register.
• VCVTNEPS2BF16 - Convert one SIMD register with packed single-precision floating-point values to bfloat16 packed in a single register.
• VDPBF16PS - Performs a SIMD dot-product on bfloat16 pairs and accumulates the results into a packaged single-precision register.

Motivation

See bfloat16 § Motivation.

Detection

CPUID		Instruction Set
Input	Output
EAX=07H, ECX=1	EAX[bit 05]	AVX512VNNI

Microarchitecture support

Instructions	Introduction
AVX512_BF16	Cooper Lake (server) Sapphire Rapids

Intrinsic functions

# vcvtne2ps2bf16
__m128bh _mm_cvtne2ps_pbh (__m128 a, __m128 b)
__m128bh _mm_mask_cvtne2ps_pbh (__m128bh src, __mmask8 k, __m128 a, __m128 b)
__m128bh _mm_maskz_cvtne2ps_pbh (__mmask8 k, __m128 a, __m128 b)
__m256bh _mm256_cvtne2ps_pbh (__m256 a, __m256 b)
__m256bh _mm256_mask_cvtne2ps_pbh (__m256bh src, __mmask16 k, __m256 a, __m256 b)
__m256bh _mm256_maskz_cvtne2ps_pbh (__mmask16 k, __m256 a, __m256 b)
__m512bh _mm512_cvtne2ps_pbh (__m512 a, __m512 b)
__m512bh _mm512_mask_cvtne2ps_pbh (__m512bh src, __mmask32 k, __m512 a, __m512 b)
__m512bh _mm512_maskz_cvtne2ps_pbh (__mmask32 k, __m512 a, __m512 b)
# vcvtneps2bf16
__m128bh _mm_cvtneps_pbh (__m128 a)
__m128bh _mm_mask_cvtneps_pbh (__m128bh src, __mmask8 k, __m128 a)
__m128bh _mm_maskz_cvtneps_pbh (__mmask8 k, __m128 a)
__m128bh _mm256_cvtneps_pbh (__m256 a)
__m128bh _mm256_mask_cvtneps_pbh (__m128bh src, __mmask8 k, __m256 a)
__m128bh _mm256_maskz_cvtneps_pbh (__mmask8 k, __m256 a)
__m256bh _mm512_cvtneps_pbh (__m512 a)
__m256bh _mm512_mask_cvtneps_pbh (__m256bh src, __mmask16 k, __m512 a)
__m256bh _mm512_maskz_cvtneps_pbh (__mmask16 k, __m512 a)
# vdpbf16ps
__m128 _mm_dpbf16_ps (__m128 src, __m128bh a, __m128bh b)
__m128 _mm_mask_dpbf16_ps (__m128 src, __mmask8 k, __m128bh a, __m128bh b)
__m128 _mm_maskz_dpbf16_ps (__mmask8 k, __m128 src, __m128bh a, __m128bh b)
__m256 _mm256_dpbf16_ps (__m256 src, __m256bh a, __m256bh b)
__m256 _mm256_mask_dpbf16_ps (__m256 src, __mmask8 k, __m256bh a, __m256bh b)
__m256 _mm256_maskz_dpbf16_ps (__mmask8 k, __m256 src, __m256bh a, __m256bh b)
__m512 _mm512_dpbf16_ps (__m512 src, __m512bh a, __m512bh b)
__m512 _mm512_mask_dpbf16_ps (__m512 src, __mmask16 k, __m512bh a, __m512bh b)
__m512 _mm512_maskz_dpbf16_ps (__mmask16 k, __m512 src, __m512bh a, __m512bh b)

Bibliography

• Intel Architecture Instruction Set Extensions and Future Features Programming Reference, Revision 36. (Ref #319433-039)