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Demoting means that we don't execute any writes to memory but otherwise the invocation continues to execute. Particularly, subgroup operations and derivatives must work. Our implementation of discard does exactly this by using setmsf to prevent writes for the affected invocations, the only difference for us is that with discard/terminate we want to be more careful with emitting quad loads for tmu operations, since the invocations are not supposed to be running any more and load offsets may not be valid, but with demote the invocations are not terminated and thus we should emit memory reads for them to ensure quad operations and derivatives from invocations that have not been demoted still work. Since we use the sample mask to implement demotes we can't tell whether a particular helper invocation was originally such (gl_HelperInvocation in GLSL) or was later demoted (OpIsHelperInvocationEXT added with SPV_EXT_demote_to_helper_invocation), so we use nir_lower_is_helper_invocation to take care of this. Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26949>
`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 `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://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.