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llvm / llvm-project / 08a8e1c6b62215bf0b410f297add76f4e3b068d7
commit08a8e1c6b62215bf0b410f297add76f4e3b068d7[log] [tgz]
authorFlorian Hahn <flo@fhahn.com>Mon Jul 14 22:01:03 2025 +0200
committerGitHub <noreply@github.com>Mon Jul 14 21:01:03 2025 +0100
treea8277528da9919fe4b137ae4bb5d9bf6010b8505
parent2edd4a25dd0bb4e5f49ce0d5ff8a95803ac88d27 [diff]
[InstCombine] Move extends across identity shuffles. (#146901)

Add a new fold to instcombine to move SExt/ZExt across identity
shuffles, applying the cast after the shuffle. This sinks extends and
can enable more general additional folding of both shuffles (and
related instructions) and extends. If backends prefer splitting up doing
casts first, the extends can be hoisted again in VectorCombine for
example.

A larger example is included in the load_i32_zext_to_v4i32. The wider
extend is easier to compute an accurate cost for and targets (like
AArch64) can lower a single wider extend more efficiently than multiple
separate extends.

This is a generalization of a VectorCombine version
(https://github.com/llvm/llvm-project/pull/141109) as suggested by
@preames.

PR: https://github.com/llvm/llvm-project/pull/146901
4 files changed
tree: a8277528da9919fe4b137ae4bb5d9bf6010b8505
  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. runtimes/
  25. third-party/
  26. utils/
  27. .clang-format
  28. .clang-format-ignore
  29. .clang-tidy
  30. .git-blame-ignore-revs
  31. .gitattributes
  32. .gitignore
  33. .mailmap
  34. CODE_OF_CONDUCT.md
  35. CONTRIBUTING.md
  36. LICENSE.TXT
  37. pyproject.toml
  38. README.md
  39. SECURITY.md
README.md

The LLVM Compiler Infrastructure

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