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bd428162b6
The current align_mul calculation in the unknown-array-index
calculation is
align_mul = MIN3(parent_mul,
min_pow2_divisor(parent_offset),
min_pow2_divisor(stride))
which is certainly correct if parent_offset > 0. However, when
parent_offset = 0, min_pow2_divisor(parent_offset) isn't well-defined
and our calculation for it is 1 << -1 which isn't well-defined. That
said.... it's not actually needed.
The offset to the base of the array is
array_base = parent_mul * k + parent_offset
for some integer k. When we throw in an unknown array index i, we get
elem = parent_mul * k + parent_offset + stride * i.
If we set new_align = MIN2(parent_mul, min_pow2_divisor(stride)), then
both parent_mul and stride are divisible by new_align and
elem = (parent_mul / new_alig) * new_align * k +
(stride / new_align) * new_align * i + parent_offset
= new_align * ((parent_mul / new_alig) * k +
(stride / new_align) * i) + parent_offset
so elem = new_align * j + parent_offset where
j = (parent_mul / new_alig) * k + (stride / new_align) * i.
That's a very long-winded way of saying that we can delete one parameter
from the align_mul calculation and it's still fine. :-)
Fixes:
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| .appveyor | ||
| .gitlab/issue_templates | ||
| .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.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 `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.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.