On Mittwoch, 22. Mai 2019 11:17:57 CEST Richard Biener wrote: > On Wed, May 22, 2019 at 10:36 AM Martin Reinecke > <mar...@mpa-garching.mpg.de> wrote: > > Hi Matthias! > > > > > I agree, we need more information from the compiler. Esp. whether the > > > user > > > specified `-mprefer-avx128` or `-mprefer-vector-width=none/128/256/512`. > > > OTOH `-msve-vector-bits=N` is reported as __ARM_FEATURE_SVE_BITS. So > > > that's > > > covered. > > > > Almost ... except that I'd need a platform-agnostic definition. The > > point is that the code does not care about the underlying hardware at > > all, only for the vector length supported by it. > > And then you run into AVX + SSE vs. AVX2 + SSE cases where the (optimal) > length depends on the component type... > > I wonder if we'd want to have a 'auto' length instead ;) > > I suppose exposing a __BIGGEST_VECTOR__ might be possible (not for SVE > though?).
AVX vs. AVX2 is a valid question. std::experimental::simd solves it by having the size depend on the element type. So I agree, `vector_size(auto)` seems like a possible solution. One could then take the sizeof if the number is important to know. -- ────────────────────────────────────────────────────────────────────────── Dr. Matthias Kretz https://kretzfamily.de GSI Helmholtzzentrum für Schwerionenforschung https://gsi.de SIMD easy and portable https://github.com/VcDevel/Vc ──────────────────────────────────────────────────────────────────────────
