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When emitting a sampler message, we allocate a temporary destination large enough to hold 4 values (or 5 for sparse). This is the maximum size needed to hold any result. However, we shrink the size written by the sampler message to skip writing any trailing components that NIR tells us are never read. So we may not write the entire temporary. The NIR texture instruction has a destination VGRF which is sized assuming that all components are present. We issue a LOAD_PAYLOAD instruction to copy our sampler result temporary to the NIR destination. When we reduce the response length of the sampler messages, then some of these temporary components have undefined values. The correct way to indicate that is by using a BAD_FILE source. Unfortunately, we were naively reading offsets of the temporary that were never written, but are still part of a larger VGRF. This complicates things. For example, sampling and only using RGB (not RGBA) was producing this: txl_logical(8) (written: 3) vgrf3+0.0:F, ... undef(8) (written: 4) vgrf4:UD load_payload(8) (written: 4) vgrf4:F, vgrf3+0.0:F, vgrf3+1.0:F, vgrf3+2.0:F, vgrf3+3.0:F The last source, vgrf3+3.0:F, is undefined, and should be BAD_FILE. Doing so allows VGRF splitting and other optimizations to work better. Reviewed-by: Ian Romanick <ian.d.romanick@intel.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/28971>
`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.