3 ms·

Hi! Thanks for your interest in the library. Here is a godbolt example: https://godbolt.org/z/bEGd7Tnb3 https://godbolt.org/z/bEGd7Tnb3 Here is a bunch of sim

Hi! Thanks for your interest in the library. Here is a godbolt example: https://godbolt.org/z/bEGd7Tnb3 https://godbolt.org/z/bEGd7Tnb3 Here is a bunch of simple examples: https://github.com/jfalcou/eve/blob/fb093a0553d25bb8114f1396cced329ad99949f5/examples/start_here.cpp#L16 https://github.com/jfalcou/eve/blob/fb093a0553d25bb8114f1396... I personally think we have the following strenghs: * Algorithms. Writing SIMD loops is very hard. We give you a lot of ready to go loops. (find, search, remove, set_intersection to name a few). * zip and SOA support out of the box. * High quality codegen. I haven't seen other libraries care about unrolling/aligning data accesses - meanwhile these give you substantial improvements. * Supporting more than transform/reduce. We have really decent compress implemented for sse/avx/neon implemented for example. The following weaknesses: * We don't support runtime sized sve/rvv (only fixed size). We tried really hard, but unfortunately just the C++ language refuses to play ball there. Here is a discussion about that https://stackoverflow.com/questions/73210512/arm-sve-wrapping-runtime-sized-register https://stackoverflow.com/questions/73210512/arm-sve-wrappin... If this is something you need we recommend compiling a few dynamic libraries with the correct fixed lengths. Google Highway manage to pull it off but the trade off is a variadics interface that I personally find very difficult. * Runtime dispatch based on arch. We again recommend dlls for this. The problem here is ODR. I believe there is a solution based on preprocessor and namespaces I could use but it breaks as soon as modules become a thing. So - in the module world - we don't have an option. I'm happy for suggestions. * No MSVC support C++20 and MSVC is still not a thing enough. And each new version breaks something that was already working. Sad times. * Just tricky to get started. I don't know what to do about that. I'm happy to just write examples for people. If you wanna try a library - please create an issue/discussion or smth - I'm happy to take some time and try to solve your case. We talked about the library at CppCon: https://youtu.be/WZGNCPBMInI?si=buFteQB1e1vXRT5M https://youtu.be/WZGNCPBMInI?si=buFteQB1e1vXRT5M If you want to learn how SIMD algorithms work, here are a couple of talks I gave: https://youtu.be/PHZRTv3erlA?si=b87DBYMDskvzYcq1 https://youtu.be/PHZRTv3erlA?si=b87DBYMDskvzYcq1 https://youtu.be/vGcH40rkLdA?si=WL2e5gYQ7pSie9bd https://youtu.be/vGcH40rkLdA?si=WL2e5gYQ7pSie9bd Feel free to ask any questions.

janwas 2y ago
> Google Highway manage to pull it off but the trade off is a variadics interface that I personally find very difficult. I'm curious what you mean by 'variadics', and what exactly you find difficult? People new to Highway are often surprised by the d/tag argument to loads that say whether to load half/full vector, or no more than 4 elements, etc. The key is to understand these are just zero-sized structs used for type information, and are not the actual vector/data. After that, I observe introductory workshop participants are able to get started/productive quickly.
- dyaroshev 2y ago
  I struggle to read the highway documentation, it focuses on things that are unrelated to me. So sorry if I'm wrong. Let me write the std::ranges code and ask you to write them with highway. https://godbolt.org/z/3s1b8P3sj https://godbolt.org/z/3s1b8P3sj PS: this is how it looks in eve: https://godbolt.org/z/Kzxqqdrez https://godbolt.org/z/Kzxqqdrez
  - janwas 2y ago
    Thanks for sharing :) Any thoughts on what kind of things you are looking for and didn't find? I cannot recall anyone saying this kind of thing is a bottleneck for them. We don't use std::range, but searching for a negative value can look like: https://gcc.godbolt.org/z/8bbb16Eea https://gcc.godbolt.org/z/8bbb16Eea It looks like smaller codegen than EVE's https://godbolt.org/z/fEn9r175v https://godbolt.org/z/fEn9r175v?
    - dyaroshev 2y ago
      Thanks for this example. Can you write the second one two? With two ranges? That's where I believe the variadics will be. FYI: The codegen is smaller because the loop is not unrolled. That's a 2x slower on my measurements. + at least I don't see any aligning of memory accesses, that'd give you another third improment when the data is in L1. You really should fix that.
      - 2y ago

janwas 2y ago

> Google Highway manage to pull it off but the trade off is a variadics interface that I personally find very difficult. I'm curious what you mean by 'variadics', and what exactly you find difficult? People new to Highway are often surprised by the d/tag argument to loads that say whether to load half/full vector, or no more than 4 elements, etc. The key is to understand these are just zero-sized structs used for type information, and are not the actual vector/data. After that, I observe introductory workshop participants are able to get started/productive quickly.

dyaroshev 2y ago
I struggle to read the highway documentation, it focuses on things that are unrelated to me. So sorry if I'm wrong. Let me write the std::ranges code and ask you to write them with highway. https://godbolt.org/z/3s1b8P3sj https://godbolt.org/z/3s1b8P3sj PS: this is how it looks in eve: https://godbolt.org/z/Kzxqqdrez https://godbolt.org/z/Kzxqqdrez
- janwas 2y ago
  Thanks for sharing :) Any thoughts on what kind of things you are looking for and didn't find? I cannot recall anyone saying this kind of thing is a bottleneck for them. We don't use std::range, but searching for a negative value can look like: https://gcc.godbolt.org/z/8bbb16Eea https://gcc.godbolt.org/z/8bbb16Eea It looks like smaller codegen than EVE's https://godbolt.org/z/fEn9r175v https://godbolt.org/z/fEn9r175v?
  - dyaroshev 2y ago
    Thanks for this example. Can you write the second one two? With two ranges? That's where I believe the variadics will be. FYI: The codegen is smaller because the loop is not unrolled. That's a 2x slower on my measurements. + at least I don't see any aligning of memory accesses, that'd give you another third improment when the data is in L1. You really should fix that.
    - 2y ago