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Lionel Landwerlin ca1533cd03 nir/divergence: add a new mode to cover fused threads on Intel HW
The Intel Gfx12.x generation of GPU has an architecture feature called
EU fusion in which 2 subgroups run lock step. A typical case where
this happens is a compute shader with 1x1x1 local workgroup size and a
dispatch command of 2x1x1. In that case 2 threads will be run in lock
step for each of the workgroup.

This has been the sources of some troubles in the backend because one
subgroup can run with all lanes disabled, requiring care for SEND
messages using the NoMask flag (execution regardless of the lane mask).

We found out that other things are happening when 2 subgroups run
together :
  - the HW will use the surface/sampler handle from only one subgroup
  - the HW will use the sampler header from only one subgroup

So one of the fused subgroup can access the wrong surface/sampler if
the value is different between the 2 subgroups and that can happen
even with subgroup uniform values.

Fortunately we can flag SEND instructions to disable the fusion
behavior (most likely at a performance cost).

This change introduce a new divergence mode that tries to compute
things divergent between subgroups so that we can flag instructions
accordingly.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Francisco Jerez <currojerez@riseup.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/37394>
2025-10-10 11:19:39 +00:00
.ci-farms Revert "ci: disable Collabora's farm due to maintenance" 2025-10-06 13:00:52 +02:00
.ci-farms-disabled Revert "ci: disable Collabora's farm due to maintenance" 2025-10-06 13:00:52 +02:00
.github/workflows meson: remove unused osmesa option 2025-06-23 06:42:50 +00:00
.gitlab docs: update gitlab docs urls 2025-02-23 00:31:59 +01:00
.gitlab-ci ci/android: Make Vulkan driver replacement conditional 2025-10-08 09:25:24 +00:00
.marge/hooks ci: pipeline_message: reset empty errors 2025-01-07 05:08:10 +00:00
android android: fix building rules for i915, r300 2025-10-08 23:43:33 +02:00
bin ci,marge_queue: introduce testing 2025-10-09 12:12:42 +00:00
build-support meson: move tsan-blacklist.txt to build-support with the other build support files 2024-05-01 07:05:12 +00:00
docs calendar: fix 25.3 branch names 2025-10-09 10:12:05 -07:00
include vulkan: update spec to 1.4.328 2025-09-26 14:02:52 +00:00
licenses licenses: add missing licenses 2025-01-08 20:37:51 +00:00
src nir/divergence: add a new mode to cover fused threads on Intel HW 2025-10-10 11:19:39 +00:00
subprojects ci: Bump DirectX-Headers and Agility SDK dependencies to 1.618.1 2025-10-01 14:46:15 -04:00
.clang-format meson: enable the clang-format target 2023-05-29 11:57:08 +00:00
.clang-format-ignore ci: enforce formatting for RADV & ACO 2023-06-16 19:59:52 +00:00
.clang-format-include clang-format: Add src/imagination to .clang-format-include 2025-09-17 10:05:18 +00:00
.dir-locals.el
.editorconfig editorconfig: move OpenCL configuration to root 2025-08-30 22:49:08 -07:00
.git-blame-ignore-revs freedreno: Add register renaming to .git-blame-ignore-revs 2025-07-03 12:50:04 +00:00
.gitattributes gitlab: Highlight .cl as C 2023-11-02 11:37:46 +00:00
.gitignore intel/mda: Add code to produce mesa debug archives 2025-09-24 23:08:45 -07:00
.gitlab-ci.yml ci: Disable broken MR check in sanity job 2025-10-09 09:05:56 +00:00
.graphqlrc.yml
.mailmap mailmap: Update for Dylan Baker 2025-09-16 19:45:15 +00:00
.mr-label-maker.yml mr-label-maker.yml: remove remaining osmesa occurrences 2025-06-23 06:42:50 +00:00
.shellcheckrc ci: move shellcheck options to .shellcheckrc 2024-10-24 22:43:03 +00:00
CODEOWNERS intel: update code owners 2025-08-31 15:38:27 +00:00
meson.build meson: static link spirv-tools for darwin 2025-10-06 15:19:55 +00:00
meson.options pvr, pco: usc program (pre-)generation boilerplate 2025-09-16 18:26:09 +00:00
README.rst docs: Match README installation guide with meson.rst 2024-07-27 11:53:53 +00:00
rustfmt.toml mesa: Add rustfmt.toml 2024-11-18 22:29:14 +00:00
VERSION VERSION: bump to 25.3 2025-07-16 13:50:24 +00:00

`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://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.