On Friday, 2017-11-17 12:34:12 -0800, Dylan Baker wrote: > Quoting Emil Velikov (2017-11-17 03:11:50) > > On 16 November 2017 at 22:21, Dylan Baker <dy...@pnwbakers.com> wrote: > > > Quoting Emil Velikov (2017-11-16 03:35:17) > > >> Hi Dylan, > > >> > > >> On 16 November 2017 at 01:10, Dylan Baker <dy...@pnwbakers.com> wrote: > > >> > This patch checks for an and then enables sse4.1 optimizations if the > > >> > host machine will be x86/x86_64. > > >> > > > >> Hell yeah, SSE is coming to town :-) > > >> > > >> Will this work if the user disables SSE4.1, say via CFLAGS=-mno-sse4.1 > > >> meson ...? > > >> My meson is still bit rough, so I could not quite grok ^^ by reading > > >> through the patch. > > >> > > >> Thanks > > >> Emil > > > > > > It'll explode horribly. Id didn't see any special handling of that in > > > autotools > > > build though either, did I miss something? > > > > > In autotools it's handled before the normal ld invocation. > > > > Namely: configure.ac does: > > - construct a program using sse4.1 intrinsicts > > Note: return _mm_...() is required otherwise the whole program will be > > optimised away > > - the -msse is passed first and then the user flags (-mno-sse and/or > > anything else) > > - the user -mno-sse takes precedence, hence the test program fails to build > > - set see_supported=false and don't build the SSE optimised static library > > > > HTH > > Emil > > That's an interesting question. So arguments passed via CFLAGS and friends > will > be passed to tests, but the arguments passed explicitly to those tests are > appended, so -msse4.1 will take precedence. I'm also pretty sure there isn't a > way to check the arguments passed via -Dc_args or CFLAGS (they're treated as > default arguments, like the c_std in the project() argument). I asked on > #mesonbuild, but I haven't gotten an answer yet (Fridays are pretty slow > everywhere).
I asked that already a little while ago, about if there was a way to get any -O passed in in any of the cflags inputs, and the answer was that no, you can't and you shouldn't have behaviour based on cflags set at any time, so I don't expect they will ever add this functionality. One thing they might do though, is parse all the cflags and print a warning if both `-foo` and `-nofoo` are present, so that might be something to suggest. > > I think currently the only way to control this would be to have a meson option > to turn off optimizations, and I really don't like that. > > Dylan _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
