Merge triton-mlir branch - Complete rewrite of the backend from scratch (#1004)

This PR merges the `triton-mlir` branch, in which we have been quietly
rewriting the Triton backend from scratch to increase maintainability,
stability and ultimately performance. Changes to the runtime are
minimal, and this new version aims to remain backward-compatible with
the previous commit. The legacy backend is now officially deprecated,
but can still be accessed via the `legacy-backend` tag.

Co-authored-by: Keren Zhou <kerenzhou@openai.com>
Co-authored-by: Yan Chunwei <yanchunwei@outlook.com>
Co-authored-by: goostavz <109190422+goostavz@users.noreply.github.com>
Co-authored-by: Shintaro Iwasaki <siwasaki@fb.com>
Co-authored-by: Yan Da <dyanab@connect.ust.hk>
Co-authored-by: Jun Yang <yangjunpro@gmail.com>
Co-authored-by: Ian Bearman <ianb@microsoft.com>
Co-authored-by: Jason Ansel <jansel@jansel.net>
Co-authored-by: Qingyi Liu <qingyil@nvidia.com>
Co-authored-by: ben-zhang-609 <110140741+ben-zhang-609@users.noreply.github.com>
Co-authored-by: Chenggang Zhao <lyricz@yeah.net>
Co-authored-by: ben-zhang-609 <benzh609@gmail.com>
Co-authored-by: dongdongl <dongdongl@nvidia.com>

docs/getting-started/installation.rst

@@ -34,13 +34,11 @@ You can install the Python package from source by running the following commands
 .. code-block:: bash
 
       git clone https://github.com/openai/triton.git;
-      cd triton;
-      git submodule update --init --recursive;
-      cd python;
+      cd triton/python;
       pip install cmake; # build time dependency
       pip install -e .
 
-Note that, if llvm-11 is not present on your system and you are on linux, the setup.py script will download the official LLVM11 static libraries link against that. For windows users, LLVM must be installed and configured in PATH.
+Note that, if llvm-11 is not present on your system, the setup.py script will download the official LLVM11 static libraries link against that.
 
 You can then test your installation by running the unit tests: