On Fri, Feb 5, 2016 at 10:57 AM, Marek Olšák <mar...@gmail.com> wrote: > On Fri, Feb 5, 2016 at 1:55 AM, Matt Turner <matts...@gmail.com> wrote: >> On Thu, Feb 4, 2016 at 10:50 AM, Marek Olšák <mar...@gmail.com> wrote: >>> From: Marek Olšák <marek.ol...@amd.com> >>> >>> This is a subset of the generated tests which are known to fail >>> on everything except CPU emulation (AFAIK). >>> --- >> >> This is really awful. Committing a generated test, but with unknown >> bits chopped out is gross. >> >> If it were me, I'd want to understand why my hardware behaved >> differently -- not just hack up *different* tests and claim victory. >> >> FWIW, the generated tests pass on all Intel hardware exposing >> ARB_shading_language_packing. Gen7+ has native half-float support, and >> Gen6 uses the lowering code in lower_packing_builtins.cpp to turn the >> built-ins into a pile of instructions. >> >> If you can identify how AMD hardware behaves differently and can prove >> that the generator needs to be relaxed or something, that's cool. But >> as is, I hate this patch. >> >> I can't find anything in the AMD docs (I looked at GCN3) about >> half-precision support, so I can't check my theory that AMD hardware >> rounds towards zero instead of to-nearest/even like Intel. > > Since the tests only fail with very small numbers, I think the problem > is that denorms are disabled by radeonsi. I can try to confirm that. > > The hardware rounds to nearest even. The hw precision is: > - unpack functions - 0 ULP > - pack functions = 0.5 ULP > - input and output denorms are flushed to 0
Hey Matt, I have just confirmed that I was right. After I enable denormals in hw, the original tests pass. This means that this patch tests the packing functions but skips denormals. Not so awful now, is it? :) Sadly, I can't enable denormals on all chips, because they are slow. So if I add "-no-denormals" suffix into the test names, I can push this, right? Marek _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
