On Donnerstag, 6. Februar 2020 21:17:02 CET Lars Knoll wrote: > > On 6 Feb 2020, at 19:29, Allan Sandfeld Jensen <[email protected]> wrote: > > making the default SSE4.1 enabled but still offer users (linux distros > > really), the option to force it down to only SSE2. > > > We should at least default to SSE2 as the minimum requirement. We’ll anyway > need some pure C/C++ code as fallback, so if someone really needs to run it > on a CPU from 1999, he can compile things with SSE turned off.
Isn't that the current status?. The question is if we should now do the same for SSE4 we have been doing for SSE2 the last several years. Or do you mean we perhaps now can remove the option to non-SSE2? > > > > You could do the same with NEON, but I think we already use that > > unconditionally if detected at configure time. > > > We do use NEON conditionally in some cases (e.g. qimagescale.cpp), but for > most embedded devices it simply makes most sense to do the choice at Qt > configuration time. Hmm, all the NEON-runtime check got disabled long ago when we had issues with instructions leaking from one compile unit to another through headers. That issue later got solved when it also threatened x86 by leaking AVX instructions, and while I never reinstated the removed runtime checks for NEON in painting code, I do appear to have written new runtime switches where I added new NEON code (at least in qimagescale.cpp) Didn't even remember I did that, or why. That probably makes it limited to only a few places in image handling, and it probably shouldn't be there either. Cheers 'Allan _______________________________________________ Development mailing list [email protected] https://lists.qt-project.org/listinfo/development
