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fmin(-A, -B) is -fmax(A, B), and fmax(-A, -B) is -fmin(A, B). Therefore the logic joining A and B should toggle between ior and iand for the negated versions. At the very least, a shader from Euro Truck Simulator 2 in shader-db is affected by this. The KIL instruction in the (ARB assembly) shader ends up with the wrong logic. This is _probably_ the source of https://gitlab.freedesktop.org/mesa/mesa/-/issues/1346. That said, the issue mentions that Mesa 18.0.5 works, but commit68420d8322("nir: Simplify min and max of b2f") was added in 17.3. Moreover, I was not able to reproduce the error in the ETS2 shader from shader-db from any Mesa commit near the time the original fd.o bugzilla was submitted (December 2018). 🤷 In fact, the current error in that shader starts with9167324a86("nir/algebraic: Mark some logic-joined comparison reductions as exact"). That's a bit of a red herring as9167324a86just sets off a chain of replacements that eventually leads to the incorrect min/max of b2f patterns fixed by this commit. The other affected shaders in the shader-db results are from Cargo Commander. These are also ARB assembly shaders. I think any ARB assembly shader that uses the pattern SLT r0, ...; ... KIL -r0; will suffer from issues related to this. This change fixes the piglit tests/spec/arb_fragment_program/kil-of-slt.shader_test test added in https://gitlab.freedesktop.org/mesa/piglit/-/merge_requests/454. shader-db results: All Gen6+ platforms had similar result. (Ice Lake shown) total instructions in shared programs: 20034604 -> 20034486 (<.01%) instructions in affected programs: 3885 -> 3767 (-3.04%) helped: 47 HURT: 2 helped stats (abs) min: 2 max: 4 x̄: 2.64 x̃: 2 helped stats (rel) min: 2.33% max: 8.33% x̄: 3.48% x̃: 3.39% HURT stats (abs) min: 3 max: 3 x̄: 3.00 x̃: 3 HURT stats (rel) min: 13.64% max: 16.67% x̄: 15.15% x̃: 15.15% 95% mean confidence interval for instructions value: -2.83 -1.99 95% mean confidence interval for instructions %-change: -3.84% -1.60% Instructions are helped. total cycles in shared programs: 979881379 -> 979879406 (<.01%) cycles in affected programs: 119873 -> 117900 (-1.65%) helped: 46 HURT: 3 helped stats (abs) min: 10 max: 756 x̄: 45.41 x̃: 26 helped stats (rel) min: 0.53% max: 19.72% x̄: 1.67% x̃: 1.26% HURT stats (abs) min: 28 max: 56 x̄: 38.67 x̃: 32 HURT stats (rel) min: 1.44% max: 3.54% x̄: 2.75% x̃: 3.27% 95% mean confidence interval for cycles value: -70.83 -9.70 95% mean confidence interval for cycles %-change: -2.23% -0.57% Cycles are helped. Iron Lake and GM45 had similar results. (Iron Lake shown) total instructions in shared programs: 8115098 -> 8115076 (<.01%) instructions in affected programs: 2592 -> 2570 (-0.85%) helped: 32 HURT: 2 helped stats (abs) min: 1 max: 1 x̄: 1.00 x̃: 1 helped stats (rel) min: 0.88% max: 2.70% x̄: 1.35% x̃: 1.31% HURT stats (abs) min: 5 max: 5 x̄: 5.00 x̃: 5 HURT stats (rel) min: 17.24% max: 18.52% x̄: 17.88% x̃: 17.88% 95% mean confidence interval for instructions value: -1.15 -0.15 95% mean confidence interval for instructions %-change: -1.83% 1.39% Inconclusive result (%-change mean confidence interval includes 0). total cycles in shared programs: 238189718 -> 238189802 (<.01%) cycles in affected programs: 75076 -> 75160 (0.11%) helped: 3 HURT: 31 helped stats (abs) min: 2 max: 130 x̄: 44.67 x̃: 2 helped stats (rel) min: 0.18% max: 5.70% x̄: 2.02% x̃: 0.19% HURT stats (abs) min: 2 max: 70 x̄: 7.03 x̃: 4 HURT stats (rel) min: 0.07% max: 6.41% x̄: 0.53% x̃: 0.15% 95% mean confidence interval for cycles value: -7.27 12.21 95% mean confidence interval for cycles %-change: -0.33% 0.94% Inconclusive result (value mean confidence interval includes 0). No fossil-db changes on any Intel platform. Fixes:68420d8322("nir: Simplify min and max of b2f") Closes: #1346 Reviewed-by: Matt Turner <mattst88@gmail.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9122>
`Mesa <https://mesa3d.org>`_ - The 3D Graphics Library ====================================================== Source ------ This repository lives at https://gitlab.freedesktop.org/mesa/mesa. Other repositories are likely forks, and code found there is not supported. Build & install --------------- You can find more information in our documentation (`docs/install.rst <https://mesa3d.org/install.html>`_), but the recommended way is to use Meson (`docs/meson.rst <https://mesa3d.org/meson.html>`_): .. code-block:: sh $ mkdir build $ cd build $ meson .. $ sudo ninja install Support ------- Many Mesa devs hang on IRC; if you're not sure which channel is appropriate, you should ask your question on `Freenode's #dri-devel <irc://chat.freenode.net#dri-devel>`_, someone will redirect you if necessary. Remember that not everyone is in the same timezone as you, so it might take a while before someone qualified sees your question. To figure out who you're talking to, or which nick to ping for your question, check out `Who's Who on IRC <https://dri.freedesktop.org/wiki/WhosWho/>`_. The next best option is to ask your question in an email to the mailing lists: `mesa-dev\@lists.freedesktop.org <https://lists.freedesktop.org/mailman/listinfo/mesa-dev>`_ Bug reports ----------- If you think something isn't working properly, please file a bug report (`docs/bugs.rst <https://mesa3d.org/bugs.html>`_). Contributing ------------ Contributions are welcome, and step-by-step instructions can be found in our documentation (`docs/submittingpatches.rst <https://mesa3d.org/submittingpatches.html>`_). Note that Mesa uses gitlab for patches submission, review and discussions.