Date: Mon, 17 Aug 2015 17:09:04 -0500 From: JimF <jfoug@....net> To: john-dev@...ts.openwall.com Subject: Re: FMT_OMP_BAD On Mon, 17 Aug 2015 16:43:00 -0500, magnum <john.magnum@...hmail.com> wrote: > On 2015-08-17 23:30, JimF wrote: >> If we put the >> >> #if !FAST_FORMATS_OMP >> #undef _OPENMP >> #endif >> >> at the very top of the C files, even before any includes, then the >> entire compile of this module will be done under the assumption that >> there is no OMP. > > What if the fmt_main struct is slightly different for an OpenMP build? > Or db_main? Or some global parameter in params.h? > >> I find this safer than having this #undef happening after all the >> header includes. > > It's only safe if we can guarantee that no core struct or type or > whatever look different with OpenMP. I'm not 100% sure about that and > even if I were, I'd not be 100% sure no-one introduces such a caveat > tomorrow. > >> It also removes the requirement for the #ifdef _OPENMP wrapper down >> in the format structure. FMT_OMP and FMT_OMP_BAD will always be >> set with a 0 for the build, since there will be no _OPENMP set when >> the format.h is included. > > Yes, but with the risk I described. Then the 'simple' fix, to make a OMP_FAST_FORMATS_DISABLE.h file or something like that then include that header very late, but before any declarations that take OMP. Probably before the 'omp.h' file or memdbg.h and put those 2 last. // OMP_FAST_FORMATS_DISABLE.h #if !FAST_FORMATS_OMP #undef _OPENMP #undef FMT_OMP #define FMT_OMP 0 #undef FMT_OMP_BAD #define FMT_OMP_BAD 0 #endif Then later if we have 'other' things that we need to properly adjust, we can properly do it 1 time within this file.
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