"If a worker wants to do his job well, he must first sharpen his tools." - Confucius, "The Analects of Confucius. Lu Linggong"
Front page > Programming > How to Load 8 Floats into an __m256 Variable Using AVX Intrinsics?

How to Load 8 Floats into an __m256 Variable Using AVX Intrinsics?

Published on 2024-11-17
Browse:670

How to Load 8 Floats into an __m256 Variable Using AVX Intrinsics?

Loading 8 Floats from Memory into __m256 Variable

Your goal is to replace the float buffer[8] with an intrinsic variable, __m256. Here are the instructions to achieve this:

AVX2 Instructions:

  1. Use VPMOVZXBD ymm0, [rsi] to zero-extend the bytes in memory into 32-bit integers.
  2. Convert the integers to floats with VCVTDQ2PS ymm0, ymm0.

AVX1 Instructions:

  1. Use VPMOVZXBD xmm0, [rsi] to load the first four bytes.
  2. Load the next four bytes with VPMOVZXBD xmm1, [rsi 4].
  3. Insert the second load into the high 128 bits of ymm0 with VINSERTF128 ymm0, ymm0, xmm1, 1.
  4. Convert to floats with VCVTDQ2PS ymm0, ymm0.

Optimization Tips:

  • For AVX2, consider using a 128-bit broadcast load and VPMOVZXBD for performance.
  • Avoid using VPMOVZXBD ymm, [mem] with intrinsics, as it may lead to missed optimizations.
  • For AVX1, use _mm_loadl_epi64 to fold the load into the VPMOVZXBD instruction for optimal code.
Latest tutorial More>

Disclaimer: All resources provided are partly from the Internet. If there is any infringement of your copyright or other rights and interests, please explain the detailed reasons and provide proof of copyright or rights and interests and then send it to the email: [email protected] We will handle it for you as soon as possible.

Copyright© 2022 湘ICP备2022001581号-3