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UBO loads with a non-indirect buffer index should be safe to perform speculatively. With a direct offset, we may sometimes turn them into push constants, at which point it's just reading a register with no cost at all. Otherwise, we access them via messages that use surface state, and automatically perform bounds checking. So we shouldn't have any issues with reading out of bounds and page faulting, for example. This allows nir_opt_peephole_sel() to operate on load_ubo intrinsics, so we can turn simple if's with loads on both sides to bcsels. In some cases this can collapse a surprising amount of control flow, allowing other optimizations to work better. The i965 OpenGL driver used load_uniform intrinsics, which are allowed in NIR's peephole select pass. But iris uses the Gallium NIR pass that translates uniforms to loads from UBO 0, so we haven't been able to take advantage of NIR's peephole select pass there. The backend pass was still able to handle this to some extent, however. fossil-db results on Alchemist: Totals: Instrs: 150656329 -> 150645307 (-0.01%); split: -0.01%, +0.00% Cycles: 12635230179 -> 12633696811 (-0.01%); split: -0.02%, +0.00% Send messages: 7416330 -> 7416261 (-0.00%) Spill count: 52471 -> 52473 (+0.00%) Fill count: 100818 -> 100803 (-0.01%); split: -0.02%, +0.00% Scratch Memory Size: 3197952 -> 3198976 (+0.03%) Totals from 1848 (0.29% of 630003) affected shaders: Instrs: 1412300 -> 1401278 (-0.78%); split: -0.80%, +0.02% Cycles: 1809789567 -> 1808256199 (-0.08%); split: -0.11%, +0.03% Send messages: 59829 -> 59760 (-0.12%) Spill count: 3870 -> 3872 (+0.05%) Fill count: 9693 -> 9678 (-0.15%); split: -0.18%, +0.02% Scratch Memory Size: 174080 -> 175104 (+0.59%) Reviewed-by: Caio Oliveira <caio.oliveira@intel.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30498>
`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://docs.mesa3d.org/install.html>`_), but the recommended way is to use Meson (`docs/meson.rst <https://docs.mesa3d.org/meson.html>`_): .. code-block:: sh $ meson setup build $ ninja -C build/ $ sudo ninja -C build/ install Support ------- Many Mesa devs hang on IRC; if you're not sure which channel is appropriate, you should ask your question on `OFTC's #dri-devel <irc://irc.oftc.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://docs.mesa3d.org/bugs.html>`_). Contributing ------------ Contributions are welcome, and step-by-step instructions can be found in our documentation (`docs/submittingpatches.rst <https://docs.mesa3d.org/submittingpatches.html>`_). Note that Mesa uses gitlab for patches submission, review and discussions.