On Wed, Nov 18, 2015 at 2:03 PM, Emil Velikov <emil.l.veli...@gmail.com> wrote: > Hi Ilia, > > On 11 November 2015 at 00:28, Ilia Mirkin <imir...@alum.mit.edu> wrote: >> On Tue, Nov 10, 2015 at 7:24 PM, Connor Abbott <cwabbo...@gmail.com> wrote: >>> On Tue, Nov 10, 2015 at 7:02 PM, Ilia Mirkin <imir...@alum.mit.edu> wrote: >>>> On Tue, Nov 10, 2015 at 6:44 PM, Eric Anholt <e...@anholt.net> wrote: >>>>> Ilia Mirkin <imir...@alum.mit.edu> writes: >>>>> >>>>>> In nv50, and in the python script that Rob circulated, we do: >>>>>> >>>>>> bld.mkCmp(OP_SET, CC_GE, TYPE_U32, (s = bld.getSSA()), TYPE_U32, m, >>>>>> b); >>>>>> >>>>>> Do the same in the nir div lowering pass. This fixes the large-udiv-udiv >>>>>> piglit tests on freedreno. >>>>> >>>>> I assume you meant *-op-div-large-uint-uint.shader_test. >>>> >>>> Yes. >>>> >>>>> >>>>> vc4 doesn't have uge yet, but I've got a patch to add it and it does >>>>> fix one subtest. What this lowering pass is actually doing has never >>>>> really made sense to me, but it works, so: >>>>> >>>>> Acked-by: Eric Anholt <e...@anholt.net> >>>> >>>> It's a magical sequence of non-sensical operations which appear to >>>> produce the proper result with high probability... what's so confusing >>>> about that? :) >>>> >>>> More seriously, I think there are Newton-Raphson overtones in what >>>> it's doing, but I never fully traced it down. It kind of loses me >>>> after subtracting 2 from the integer representation of the float bits. >>>> _______________________________________________ >>>> mesa-dev mailing list >>>> mesa-dev@lists.freedesktop.org >>>> http://lists.freedesktop.org/mailman/listinfo/mesa-dev >>> >>> Where did you get it from? Is there a paper somewhere explaining it? I >>> sort of have a morbid curiosity, perhaps because I got sucked into >>> implementing division/sqrt/rsq for doubles. >> >> I made the old freedreno impl based on nv50's div lowering code. >> There's similarly weird code for r600, but I don't know if the r600 or >> nv50 code came first, or where they came from. FWIW the nvc0 div logic >> is quite different (implemented as a function call, which does rather >> different things... I think). I also don't know where that came from. >> > Just checking that this hasn't fallen through the cracks. Afaics the > only 'issue' with going forward is that no one has reviewed the patch > yet, is that right ?
Nope. Rob's going to push it out along with a bunch of freedreno stuff "soon". -ilia _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
