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Bas Nieuwenhuizen b7c3713706 radv: Use atomics to read query results.
The volatile pattern gives me flaky results for 32-bit builds on
ChromeOS Android. This is because on 32-bit the volatile 64-bit
loads gets split into 2 32-bit loads each.

So if we read the lower dword first and then the upper dword, it
can happen that the upper dword is already changed but the lower
dword isn't yet. In particular for occlusion queries this gives
false readings, as the upper dword commonly only constains the
ready bit.

With the GCC atomic intrinsics we get a call to __atomic_load_8
in libatomic.so which does the right thing.

An alternative fix would be to  explicitly split the 32-bit loads
in the right order and do a bunch of retries if things change, though
that gets messy quickly and for 32-bit builds only doesn't feel worth
it that much.

CC: mesa-stable
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6933>
(cherry picked from commit 7568c97df1)
2020-10-05 11:27:31 -07:00
.appveyor appveyor: Use Python3. 2020-08-06 09:46:48 +00:00
.gitlab/issue_templates gitlab: Ask about reproduction rate in the issue template 2020-05-20 10:20:00 +00:00
.gitlab-ci ci: Use ignore_scheduled_pipelines anchor in .radeonsi-rules 2020-09-24 09:32:14 -07:00
bin pick-ui: specify git commands in "resolve cherry pick" message 2020-08-11 09:35:47 -07:00
build-support configure: commit test files 2017-10-16 16:32:43 -07:00
docs docs: Add sh256 sums for 20.2.0 2020-09-28 16:29:08 -07:00
doxygen doxygen: Plumb through gallium/ to automated documentation 2016-05-30 17:53:45 +01:00
include ci: Include enough Android headers to let us compile test EGL 2020-08-05 18:08:07 +00:00
scons scons/windows: Support build with LLVM 10. 2020-04-14 08:40:56 +00:00
src radv: Use atomics to read query results. 2020-10-05 11:27:31 -07:00
subprojects meson: use github URL for wraps instead of completely unreliable wrapdb 2020-01-16 23:06:43 +00:00
.dir-locals.el dir-locals.el: Adds White Space support 2016-11-14 19:17:49 +02:00
.editorconfig docs: fixup indentation 2020-01-18 11:39:32 +01:00
.gitignore intel/tools: Add unit tests for assembler 2019-05-07 14:33:48 -07:00
.gitlab-ci.yml meson: bump required glvnd version 2020-08-11 09:35:50 -07:00
.mailmap .mailmap: add an alias for Andres Gomez 2020-04-30 14:33:20 +03:00
.pick_status.json radv: Use atomics to read query results. 2020-10-05 11:27:31 -07:00
.travis.yml travis: autodetect python version instead of hard-coding it 2019-12-21 20:23:08 +00:00
Android.common.mk tree-wide: fix deprecated GitLab URLs 2020-05-23 15:33:50 +00:00
Android.mk ac/llvm: handle static/shared llvm init separately 2020-08-18 07:32:07 -07:00
appveyor.yml appveyor: Use Python3. 2020-08-06 09:46:48 +00:00
CleanSpec.mk CleanSpec.mk: Remove HOST_OUT_release 2018-08-02 15:42:40 -06:00
common.py scons: Print a deprecation warning about using scons on not windows 2019-10-24 18:33:50 +00:00
meson.build meson: fix power8 option 2020-10-05 11:27:29 -07:00
meson_options.txt ci: Include enough Android headers to let us compile test EGL 2020-08-05 18:08:07 +00:00
README.rst README: update references to internal docs 2020-06-13 10:42:01 +00:00
REVIEWERS REVIEWERS: add VMware reviewers 2019-10-18 16:42:40 +00:00
SConstruct tree-wide: fix deprecated GitLab URLs 2020-05-23 15:33:50 +00:00
VERSION VERSION: bump for 20.2.0 release 2020-09-28 15:50:54 -07:00

`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.