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. Dylan
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