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35f175301d
Marek recently changed hole_size to be signed, rather than unsigned.
A negative hole_size means that the two loads overlap - and thus are
prime candidates to be combined.
My original hole_size handling was:
if hole_size > 4 * (8 - low->num_components) then don't vectorize
For non-overlapping loads, this worked: NIR's largest vector is vec16,
and if low was already a vec16, combining it with anything would exceed
that, so it'd never be considered. That meant low would always be a
vec8 or less, so (8 - low->num_components) was a positive number.
Now that we see overlapping loads, we can see a vec16 low, vec4 high,
and also a negative hole size, giving us fun comparisons like:
-16 > 4 * (8 - 16) => -16 > -32 => true, don't vectorize
Which is absolutely the wrong thing to do, because the high load's data
is entirely included within the former load's data.
The idea here was to make sure the second load would be able to pack at
least one component into the first's V8 result. But even this isn't the
best, because...even if it's simply adjacent, doing one V16 load is more
efficient than requesting two back to back V8 loads.
So, we just simplify down to a static check: if there's an entire V8 of
hole, don't vectorize. This already won't happen because the core pass
has max_hole set to 28 bytes (7 32-bit components), but that could
change based on the needs of other drivers, so let's be defensive.
fossil-db results on Alchemist:
Instrs: 161533978 -> 161295137 (-0.15%); split: -0.20%, +0.05%
Subgroup size: 8092544 -> 8092568 (+0.00%)
Send messages: 7915233 -> 7844503 (-0.89%); split: -0.94%, +0.05%
Cycle count: 16577700697 -> 16702609256 (+0.75%); split: -0.59%, +1.35%
Spill count: 72338 -> 67226 (-7.07%); split: -7.36%, +0.29%
Fill count: 134058 -> 125980 (-6.03%); split: -6.83%, +0.80%
Scratch Memory Size: 4092928 -> 3786752 (-7.48%); split: -7.53%, +0.05%
Max live registers: 33031460 -> 32945994 (-0.26%); split: -0.27%, +0.01%
Max dispatch width: 5778384 -> 5778536 (+0.00%); split: +0.26%, -0.26%
Non SSA regs after NIR: 179809505 -> 152735471 (-15.06%); split: -15.08%, +0.03%
Fixes:
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| android | ||
| bin | ||
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| docs | ||
| include | ||
| src | ||
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| .clang-format | ||
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| .git-blame-ignore-revs | ||
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| .gitlab-ci.yml | ||
| .graphqlrc.yml | ||
| .mailmap | ||
| .mr-label-maker.yml | ||
| .shellcheckrc | ||
| CODEOWNERS | ||
| meson.build | ||
| meson_options.txt | ||
| README.rst | ||
| rustfmt.toml | ||
| 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://docs.mesa3d.org/install.html>`_), but the recommended way is to use Meson (`docs/meson.rst <https://docs.mesa3d.org/meson.html>`_): .. code-block:: sh $ meson setup build $ ninja -C build/ $ sudo ninja -C build/ 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://docs.mesa3d.org/bugs.html>`_). Contributing ------------ Contributions are welcome, and step-by-step instructions can be found in our documentation (`docs/submittingpatches.rst <https://docs.mesa3d.org/submittingpatches.html>`_). Note that Mesa uses gitlab for patches submission, review and discussions.