On Wed, 2016-03-09 at 19:04 -0800, Francisco Jerez wrote: > Matt Turner <matts...@gmail.com> writes: > > > On Wed, Mar 9, 2016 at 1:37 PM, Francisco Jerez <curroje...@riseup.net> > > wrote: > >> Iago Toral <ito...@igalia.com> writes: > >> > >>> On Tue, 2016-03-08 at 17:42 -0800, Francisco Jerez wrote: > >>>> brw_cfg.h already has include guards, remove the "#pragma once" which > >>>> is redundant and non-standard. > >>> > >>> FWIW, I think using both #pragma once and include guards is a way to > >>> keep portability while still getting the performance advantage of > >>> #pragma once where it is supported. > >>> > >> It's highly unlikely to make any significant difference on any > >> reasonably modern compiler. I cannot measure any change in compilation > >> time locally from my cleanup. > >> > >>> Also it seems that we do the same thing in many other files... > >>> > >> Really? I'm not aware of any other file where we use both. > > > > There are quite a few in glsl/ > > Heh, apparently you're right. Anyway it seems rather pointless to use > '#pragma once' in a bunch of scattered header files with the expectation > to gain some speed, the improvement from a single header file is so > minuscule (if it will make any difference at all on a modern compiler > and compilation workload, which I doubt) that we would have to use it > universally in order to have the chance to measure any improvement. > > Can we please just decide for one of the include guard styles and use it > consistently? Given that the majority of header files in the Mesa > codebase use old-school define guards, that it's the only standard > option, that it has well-defined semantics in presence of file copies > and hardlinks, and that the performance argument against it is rather > dubious (although I definitely find '#pragma once' prettier and more > concise), I'd vote for using preprocessor define guards universally. > > What do other people think?
I think we have to use define guards necessarily since #pragma once is not standard even it it has wide support. So the question is whether we want to use only define guards or define guards plus #pragma once. I am fine with doing only define guards as you propose. Iago _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
