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05703a49f9
This matches what NIR does. See nir_vector_extract.
This improves code generation for several reasons. First, it only
requires 3 comparisons instead of 4 (vec3(i > 0, i > 1, i > 2) vs
vec4(i == 0, i == 1, i == 2, i == 3)).
Secondly, it shortens the liverange of some values, possibly quite
dramatically. Consider a loop in the old version (after lowering
if-statements to selects):
loop {
...
x = csel(i == 0, a[0], x);
x = csel(i == 1, a[1], x);
x = csel(i == 2, a[2], x);
x = csel(i == 3, a[3], x);
...
}
x is live for the whole loop across iterations. In the new version, x
is only live while its value is needed:
loop {
...
t0 = csel(i > 0 , a[1], a[0]);
t1 = csel(i > 2 , a[3], a[2]);
x = csel(i > 1, t1, t0);
...
}
Outside a loop, this also means more values of the array may have their
liveness reduced sooner (by consuming two values at once).
All Intel platforms had similar results. (Tigerlake shown)
total instructions in shared programs: 21171336 -> 21163615 (-0.04%)
instructions in affected programs: 89680 -> 81959 (-8.61%)
helped: 40
HURT: 4
helped stats (abs) min: 1 max: 450 x̄: 193.68 x̃: 196
helped stats (rel) min: 0.41% max: 13.32% x̄: 6.01% x̃: 6.22%
HURT stats (abs) min: 1 max: 12 x̄: 6.50 x̃: 6
HURT stats (rel) min: 0.50% max: 0.66% x̄: 0.58% x̃: 0.58%
95% mean confidence interval for instructions value: -229.68 -121.28
95% mean confidence interval for instructions %-change: -6.93% -3.89%
Instructions are helped.
total cycles in shared programs: 832879641 -> 829513122 (-0.40%)
cycles in affected programs: 44738430 -> 41371911 (-7.52%)
helped: 35
HURT: 2
helped stats (abs) min: 2 max: 189948 x̄: 96186.49 x̃: 116154
helped stats (rel) min: 0.37% max: 11.08% x̄: 5.88% x̃: 6.47%
HURT stats (abs) min: 4 max: 4 x̄: 4.00 x̃: 4
HURT stats (rel) min: 0.69% max: 0.69% x̄: 0.69% x̃: 0.69%
95% mean confidence interval for cycles value: -112881.94 -69092.06
95% mean confidence interval for cycles %-change: -6.77% -4.27%
Cycles are helped.
total spills in shared programs: 8061 -> 7338 (-8.97%)
spills in affected programs: 873 -> 150 (-82.82%)
helped: 24
HURT: 0
total fills in shared programs: 7501 -> 6388 (-14.84%)
fills in affected programs: 1389 -> 276 (-80.13%)
helped: 24
HURT: 0
Radeon R430
total instructions in shared programs: 2449852 -> 2449136 (-0.03%)
instructions in affected programs: 6285 -> 5569 (-11.39%)
helped: 64
HURT: 0
helped stats (abs) min: 4 max: 12 x̄: 11.19 x̃: 12
helped stats (rel) min: 8.16% max: 21.62% x̄: 12.09% x̃: 10.91%
total consts in shared programs: 1032517 -> 1032482 (<.01%)
consts in affected programs: 966 -> 931 (-3.62%)
helped: 35
HURT: 0
helped stats (abs) min: 1 max: 1 x̄: 1.00 x̃: 1
helped stats (rel) min: 2.94% max: 10.00% x̄: 4.26% x̃: 3.57%
Reviewed-by: Matt Turner <mattst88@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14573>
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| src | ||
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| .dir-locals.el | ||
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| meson.build | ||
| meson_options.txt | ||
| 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.