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read-only mirror of https://gitlab.freedesktop.org/mesa/mesa
76b4255cd8
This fixes the behavior of register coalesce in cases where the source
of a copy is written elsewhere in the program by a force_writemask_all
instruction, which could cause the overwrite to be executed for an
inactive channel under non-uniform control flow, causing
can_coalesce_vars() to give incorrect results. This has been reported
in cases like:
> while (true) {
> x = imageSize(img);
> if (non_uniform_condition()) {
> y = x;
> break;
> }
> }
> use(y);
Currently the register coalesce pass would coalesce x and y in the
example above, which is invalid since in the example above imageSize()
is implemented as a force_writemask_all SEND message, whose result is
broadcast to all channels, so when a given channel executes 'y = x'
and breaks out of the loop, another divergent channel can execute a
subsequent iteration of the loop overwriting 'x' with a different
value, hence coalescing y and x into the same register changes the
behavior of the program.
Note that this is a regression introduced by commit
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| meson.build | ||
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| README.rst | ||
| VERSION | ||
`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.