Google Git
Sign in
llvm / llvm-project / 52b345d036677e6377ea5e2022a1b6bd403ed91e
commit52b345d036677e6377ea5e2022a1b6bd403ed91e[log] [tgz]
authorAlex Bradbury <asb@igalia.com>Thu May 08 12:33:14 2025 +0100
committerGitHub <noreply@github.com>Thu May 08 12:33:14 2025 +0100
tree9a946397974d40249a3d5e7e5cb52911dccba607
parent245def9def7b025644a8cf991ba24c53a50822c6 [diff]
[RISCV][TII] Add and use new hook to simplify/canonicalize instructions after MachineCopyPropagation (#137973)

PR #136875 was posted as a draft PR that handled a subset of these
cases, using the CompressPat mechanism. The consensus from that
discussion (and a conclusion I agree with) is that it would be
beneficial doing this optimisation earlier on, and in a way that isn't
limited just to cases that can be handled by instruction compression.

The most common source for instructions that can be
optimized/canonicalized in this way is through tail duplication in
MachineBlockPlacement followed by machine copy propagation. For RISC-V,
choosing a more canonical instruction allows it to be compressed when it
couldn't be before. There is the potential that it would make other
MI-level optimisations easier.

This modifies ~910 instructions across an llvm-test-suite build
including SPEC2017, targeting rva22u64. Looking at the diff, it seems
there's room for eliminating instructions or further propagating after
this.

Coverage of instructions is based on observations from a script written
to find redundant or improperly canonicalized instructions (though I aim
to support all instructions in a 'group' at once, e.g. MUL* even if I
only saw some variants of MUL in practice).
5 files changed
tree: 9a946397974d40249a3d5e7e5cb52911dccba607
  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. libunwind/
  16. lld/
  17. lldb/
  18. llvm/
  19. llvm-libgcc/
  20. mlir/
  21. offload/
  22. openmp/
  23. polly/
  24. pstl/
  25. runtimes/
  26. third-party/
  27. utils/
  28. .clang-format
  29. .clang-format-ignore
  30. .clang-tidy
  31. .git-blame-ignore-revs
  32. .gitattributes
  33. .gitignore
  34. .mailmap
  35. CODE_OF_CONDUCT.md
  36. CONTRIBUTING.md
  37. LICENSE.TXT
  38. pyproject.toml
  39. README.md
  40. 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.