Alyssa Rosenzweig
4b7e337b45
On Valhall, register reads may be marked as "last" [1]. Setting the last flag promises the hardware that the value of the register is no longer required. This may enable hardware optimizations. In particular, it may permit the hardware to avoid register file writes if a write to the marked register is still in the forwarding buffer. This may improve power efficiency. In principle, this is trivial: run liveness analysis and mark killed sources, like we would in an SSA-based register allocator. In practice, there are a few wrinkles to avoid hazards around staging registers and 64-bit register pairs, requiring some additional data flow analysis and fix ups. However, nothing here is particularly "hard", and all the ideas are already in use for the Bifrost scheduler and the Bifrost/Valhall scoreboard analyses. [1] In Mesa's compiler, this is called discard for historical reasons. Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17091>
`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.