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The CMP instruction on Gen4 and Gen5 generates one bit (the LSB) of
valid data and 31 bits of junk. Results of comparisons that are used as
Boolean values need to have a fixup applied to generate the proper 0/~0
values.
Calling fs_visitor::nir_emit_alu with need_dest=false prevents the fixup
code from being generated. This results in a sequence like:
cmp.l.f0.0(16) g8<1>F g14<8,8,1>F 0x0F /* 0F */
...
cmp.l.f0.0(16) g4<1>F g6<8,8,1>F 0x0F /* 0F */
(+f0.1) or.z.f0.1(16) null<1>UD g4<8,8,1>UD g8<8,8,1>UD
instead of
cmp.l.f0.0(16) g8<1>F g14<8,8,1>F 0x0F /* 0F */
...
cmp.l.f0.0(16) g4<1>F g6<8,8,1>F 0x0F /* 0F */
or(16) g4<1>UD g4<8,8,1>UD g8<8,8,1>UD
(+f0.1) and.z.f0.1(16) null<1>UD g4<8,8,1>UD 1UD
I examined a couple of the shaders hurt by this change, and ALL of them
would have been affected by this bug. :(
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
Closes: https://gitlab.freedesktop.org/mesa/mesa/issues/1836
Fixes:
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|---|---|---|
| .appveyor | ||
| .gitlab-ci | ||
| bin | ||
| build-support | ||
| docs | ||
| doxygen | ||
| include | ||
| scons | ||
| src | ||
| subprojects | ||
| .dir-locals.el | ||
| .editorconfig | ||
| .gitignore | ||
| .gitlab-ci.yml | ||
| .mailmap | ||
| .travis.yml | ||
| Android.common.mk | ||
| Android.mk | ||
| appveyor.yml | ||
| CleanSpec.mk | ||
| common.py | ||
| meson.build | ||
| meson_options.txt | ||
| README.rst | ||
| REVIEWERS | ||
| SConstruct | ||
| 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.html <https://mesa3d.org/install.html>`_), but the recommended way is to use Meson (`docs/meson.html <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 `Freenode's #dri-devel <irc://chat.freenode.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.html <https://mesa3d.org/bugs.html>`_). Contributing ------------ Contributions are welcome, and step-by-step instructions can be found in our documentation (`docs/submittingpatches.html <https://mesa3d.org/submittingpatches.html>`_). Note that Mesa uses email mailing-lists for patches submission, review and discussions.