On Wed, Dec 09, 2015 at 01:39:30PM +0200, Oded Gabbay wrote: > On Wed, Dec 9, 2015 at 1:09 PM, Emil Velikov <emil.l.veli...@gmail.com> wrote: > > On 9 December 2015 at 05:37, Jonathan Gray <j...@jsg.id.au> wrote: > >> Change the __m128i variables to be volatile so gcc 4.9 won't optimise > >> all of them out with -O1 or greater. The _mm_set1_epi32/pinsrd calls > >> still get optimised out but now there is at least one SSE4.1 instruction > >> generated via _mm_max_epu32/pmaxud. When all of the sse4.1 instructions > >> got optimised out the configure test would incorrectly pass when the > >> compiler supported the intrinsics and the assembler didn't support the > >> instructions. > >> > > Must admit that I was not expecting that one. Looks like pixman (the > > inspiration for this check) is missing volatile as well. Does that one > > build/run fine on OpenBSD ? > > > >> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91806 > >> Signed-off-by: Jonathan Gray <j...@jsg.id.au> > >> Cc: "11.0 11.1" <mesa-sta...@lists.freedesktop.org> > > Reviewed-by: Emil Velikov <emil.veli...@collabora.com> > > > > I'll pick this in a couple of days (barring any objections). > > > > Thanks > > Emil > > Adding pixman ML. > I must admit ignorance on this one. > I looked at configure.ac of pixman and I don't see any SSE4.1 > reference, and AFAIK, we don't use those instructions (only SSE2 and > SSSE3). > Is the above patch relevant for those as well ? because the tests in > configure.ac does *not* contain volatile. > > Oded
It looks like this is indeed a problem in pixman as well with at least gcc 4.2 and 4.9. Running the pixman sse2 test on amd64 I only see xmm register use and movdqa in the generated assembly with -O0. The pixman configure tests passes on OpenBSD but the toolchain recognises sse2 instructions just not sse 4.1. Introducing volatile to the pixman test stops the xmm/movdqa use from being optimised out. _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
