8.1.3. BFloat16 Fallback Behavior - 8.1.3. BFloat16 Fallback Behavior - 5.3 English - 57404

AOCL User Guide (57404)

Document ID
57404
Release Date
2026-05-13
Version
5.3 English

AOCL-DLP automatically handles BF16 operations on hardware that lacks native AVX512_BF16 support. BF16 API calls work unchanged across all hardware – the library performs runtime detection and transparent rerouting.

Hardware

ISA Available

What Happens

AMD Zen4+, Intel Cooper Lake+

AVX512_BF16

Native BF16 instructions – best performance

AMD Zen1-3

AVX2 only

BF16 inputs converted to f32, computed on AVX2 f32 kernels

Intel Skylake, Cascade Lake, Ice Lake

AVX512 (no BF16)

BF16 inputs converted to f32, computed on AVX512 f32 kernels

When fallback is active:

  • BF16 to F32 conversion on input

  • F32 computation

  • F32 to BF16 conversion on output (if output type is bf16)

  • Performance impact: conversion overhead plus 2x memory bandwidth for intermediates

No code changes are needed. The same aocl_gemm_bf16bf16f32of32() call works on all platforms.