On Fri, Nov 17, 2017 at 12:34 PM, Dylan Baker <dy...@pnwbakers.com> 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 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.
The original bug report of "Mesa doesn't build with -mno-sse4.1" was in Gentoo's bugzilla; https://bugs.gentoo.org/503828 There's no compelling reason to support that configuration because since the -msseX flags are off by default... in order for the -mno-sseX flag to do anything the user must be enabling them somehow (likely via -march=...). Using -march=... only to disable particular instruction sets seems pretty idiotic. I can push back harder on such stupidity in the future if we can't handle this case, but it would be nice to solve so I never have to hear about it again. _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
