[MLIR][LLVM] Add bytecode support for several attributes (#162577)

For a total of 20 attributes, 18 debug information related + 2 regular
ones (loop and alias_scope).

Quick background on how this work: if a given attribute isn't supported,
by default its textual form is dumped into the bytecode. In order to get
proper encoding, an attribute needs a tablegen description of it and its
element. There's an additional rule here: if an attribute is only used
by another attribute, it's user need also to have an encoding in order
for it to be encoded. (e.g. `DICompileUnitAttr` only gets encoded while
in `DISubprogramAttr` if the later also has an encoded form), otherwise
text is used. For this reason, this PR does a bunch at the same time,
otherwise there isn't really much to test (easy to break it down if
needed though).

The PR is tested against some of our internal apps, successfully
round-tripping around 14Gb of llvm dialect text. Some interesting
findings include a 800K mlir textual file that used to become 1.2G in
bytecode format - now down to 100K due to proper encoding of debug info
attributes.

In the future we should find a way to merge this together in the
attribute definitions (perhaps autogenerate the entries from LLVM
attribute descriptions), seems like we can benefit from the boilerplate.
It's not clear yet how to solve some of the tablegen issues; some fields
require manual translation of flag values using `LocalVar`, others
require custom getters, etc. Ideas on that front are welcome.

A next natural step here is to add type support, LLVM structs can also
lead to non-neglible disk footprint.
9 files changed
tree: 9789d85af1868957c603b5e0be105e0250507b41
  1. .ci/
  2. .github/
  3. bolt/
  4. clang/
  5. clang-tools-extra/
  6. cmake/
  7. compiler-rt/
  8. cross-project-tests/
  9. flang/
  10. flang-rt/
  11. libc/
  12. libclc/
  13. libcxx/
  14. libcxxabi/
  15. libsycl/
  16. libunwind/
  17. lld/
  18. lldb/
  19. llvm/
  20. llvm-libgcc/
  21. mlir/
  22. offload/
  23. openmp/
  24. orc-rt/
  25. polly/
  26. runtimes/
  27. third-party/
  28. utils/
  29. .clang-format
  30. .clang-format-ignore
  31. .clang-tidy
  32. .git-blame-ignore-revs
  33. .gitattributes
  34. .gitignore
  35. .mailmap
  36. CODE_OF_CONDUCT.md
  37. CONTRIBUTING.md
  38. LICENSE.TXT
  39. pyproject.toml
  40. README.md
  41. SECURITY.md
README.md

The LLVM Compiler Infrastructure

OpenSSF Scorecard OpenSSF Best Practices libc++

Welcome to the LLVM project!

This repository contains the source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and run-time environments.

The LLVM project has multiple components. The core of the project is itself called “LLVM”. This contains all of the tools, libraries, and header files needed to process intermediate representations and convert them into object files. Tools include an assembler, disassembler, bitcode analyzer, and bitcode optimizer.

C-like languages use the Clang frontend. This component compiles C, C++, Objective-C, and Objective-C++ code into LLVM bitcode -- and from there into object files, using LLVM.

Other components include: the libc++ C++ standard library, the LLD linker, and more.

Getting the Source Code and Building LLVM

Consult the Getting Started with LLVM page for information on building and running LLVM.

For information on how to contribute to the LLVM project, please take a look at the Contributing to LLVM guide.

Getting in touch

Join the LLVM Discourse forums, Discord chat, LLVM Office Hours or Regular sync-ups.

The LLVM project has adopted a code of conduct for participants to all modes of communication within the project.