Adding collectives HAL operations and compiler support. (#11342)

This adds end-to-end support from a new `stream.async.collective` op and
communication channel type down through the HAL and all the way to
runtime.

Conceptually collective operations are commands that can be recorded
into command buffers and the various HAL backends can decide how to
implement them. The commands are transfer-like but may be implemented
with dispatch logic.

We could offer a local emulated channel that let us simulate multiple
devices by performing copies but this first version just returns
unimplemented on all backends. A skeleton of the runtime support is
provided for NCCL support in the CUDA backend. In the future we can add
local/ backend support for various collective libraries if we want or
expose a factory mechanism on device creation to allow hosting
applications control over the communication channels and routing. A
utility has been added to allow command buffer implementations to
accumulate batches of collective operations for efficient submission to
the underlying library APIs.

There are several areas future changes will focus on but what's here
should be enough for some basic hello-world programs, major things
missing:

* send/recv are not available at the `stream.async.*` level
* collectives cannot currently be performed in-place (#11249 is tracking
the support required)
* supported collective element types and reduction operators are
basically just NCCL
* emulation for unsupported element types and reduction operators is
missing - we should insert casts and such at higher levels

The next steps for wiring this up are to implement NCCL shared library
loading, implement the `TODO(#9580)`s in the code for calling into NCCL,
and some representation of collectives at the flow level that lower into
the stream ops.

Progress on #9580.
tree: 5896d1a5cc340d0b212c7e893500003703578ff6
  1. .github/
  2. benchmarks/
  3. build_tools/
  4. compiler/
  5. docs/
  6. experimental/
  7. integrations/
  8. llvm-external-projects/
  9. runtime/
  10. samples/
  11. tests/
  12. third_party/
  13. tools/
  14. .bazelignore
  15. .bazelrc
  16. .bazelversion
  17. .clang-format
  18. .dockerignore
  19. .gitignore
  20. .gitmodules
  21. .pylintrc
  22. .style.yapf
  23. .yamllint.yml
  24. AUTHORS
  25. BUILD.bazel
  26. CITATION.cff
  27. CMakeLists.txt
  28. configure_bazel.py
  29. CONTRIBUTING.md
  30. LICENSE
  31. README.md
  32. WORKSPACE
README.md

IREE: Intermediate Representation Execution Environment

IREE (Intermediate Representation Execution Environment, pronounced as “eerie”) is an MLIR-based end-to-end compiler and runtime that lowers Machine Learning (ML) models to a unified IR that scales up to meet the needs of the datacenter and down to satisfy the constraints and special considerations of mobile and edge deployments.

See our website for project details, user guides, and instructions on building from source.

CI Status

Project Status

IREE is still in its early phase. We have settled down on the overarching infrastructure and are actively improving various software components as well as project logistics. It is still quite far from ready for everyday use and is made available without any support at the moment. With that said, we welcome any kind of feedback on any communication channels!

Communication Channels

Related Project Channels

  • MLIR topic within LLVM Discourse: IREE is enabled by and heavily relies on MLIR. IREE sometimes is referred to in certain MLIR discussions. Useful if you are also interested in MLIR evolution.

Architecture Overview

IREE Architecture IREE Architecture

See our website for more information.

Presentations and Talks

  • 2021-06-09: IREE Runtime Design Tech Talk (recording and slides)
  • 2020-08-20: IREE CodeGen: MLIR Open Design Meeting Presentation (recording and slides)
  • 2020-03-18: Interactive HAL IR Walkthrough (recording)
  • 2020-01-31: End-to-end MLIR Workflow in IREE: MLIR Open Design Meeting Presentation (recording and slides)

License

IREE is licensed under the terms of the Apache 2.0 License with LLVM Exceptions. See LICENSE for more information.