> On Jun 10, 2016, at 3:49 PM, Ilia Mirkin <imir...@alum.mit.edu> wrote: > > On Fri, Jun 10, 2016 at 4:48 PM, Rowley, Timothy O > <timothy.o.row...@intel.com> wrote: >> >>> On Jun 10, 2016, at 3:37 PM, Rowley, Timothy O <timothy.o.row...@intel.com> >>> wrote: >>> >>>> >>>> On Jun 10, 2016, at 3:01 PM, Emil Velikov <emil.l.veli...@gmail.com> wrote: >>>> >>>> On 10 June 2016 at 20:43, Tim Rowley <timothy.o.row...@intel.com> wrote: >>>>> Previously used core-avx-i was for ivybridge; >>>>> corei7-avx allows sandybridge. >>>> Which GCC version was required by the previous and which by the >>>> current version ? >>> >>> Both options work back to gcc 4.8.x. I picked the wrong architecture flag >>> when setting up the build system initially. >>> >>>>> --- >>>>> src/gallium/drivers/swr/Makefile.am | 2 +- >>>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>>> >>>>> diff --git a/src/gallium/drivers/swr/Makefile.am >>>>> b/src/gallium/drivers/swr/Makefile.am >>>>> index d211f2e..8156cf2 100644 >>>>> --- a/src/gallium/drivers/swr/Makefile.am >>>>> +++ b/src/gallium/drivers/swr/Makefile.am >>>>> @@ -124,7 +124,7 @@ COMMON_LDFLAGS = \ >>>>> lib_LTLIBRARIES = libswrAVX.la libswrAVX2.la >>>>> >>>>> libswrAVX_la_CXXFLAGS = \ >>>>> - -march=core-avx-i \ >>>>> + -march=corei7-avx \ >>>> I'm likely missing something but neither one seems listed in the 5.4 >>>> [1] and 6.1 [2] manual. Should we be using one that's officially >>>> supported ? >>> >>> According to Chuck Atkins, while the older options aren’t documented >>> anymore, they still work on gcc 5.x and 6.x. >>> >>> Another possibility which Ilia also mentioned was to use feature flags >>> instead which have stayed consistent between gcc versions, i.e. “-mavx” and >>> “-mavx2 -mfma -mf16c” respectively for the avx and avx2 configurations. >>> Not too opposed to this except that we’ve had extensive testing with the >>> -march flags and changing the build configuration during the release >>> candidate stage seems a bit late. >> >> Another thought along these lines - since the swr code makes heavy use of >> intrinsics, we would like to have the code optimized as best as possible to >> the target architecture (or at least, the baseline architecture which >> introduces AVX and AVX2 respectively), which is best done with the -march >> flags. > > Actually it's best done with -mtune flags. -march, of course, also > sets mtune. (But you can override it later.)
Ah, true. Though the documented architecture flags for -mtune have changed along with -march between gcc 4.8 and gcc >=5, so we don’t really gain from using feature flags and -mtune versus -march. _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
