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llvm / llvm-project / ed7ad0a1a0584f90a211ca5a87bc46968e169e5d
commited7ad0a1a0584f90a211ca5a87bc46968e169e5d[log] [tgz]
authorSimon Pilgrim <llvm-dev@redking.me.uk>Tue Aug 13 12:48:04 2024 +0100
committerSimon Pilgrim <llvm-dev@redking.me.uk>Tue Aug 13 12:48:27 2024 +0100
tree904dbf3ab7cedf9c1daa570a39ad0f3112dc25f2
parentdc8c217db6329f03a116ef63dafa6de02913d311 [diff]
[X86] Promote cttz_i32(x) -> cttz_i64((i64)x | (1 << 32)) (#102900) (REAPPLIED)

On 64bit targets we can promote i32 CTTZ nodes to i64 CTTZ_ZERO_UNDEF by setting the 32nd bit.

#57811 also queried about whether we should use BTS instead of MOVABS+OR to avoid a i64 immediate - I'm willing to tweak the DAGToDAG isel peephole for these cases if reviewers think it worthwhile. But most recent CPUs can actually handle MOVABS faster than BTS/C/R.......

Reapplied with missing costmodel changes - the cost tables can probably be improved in a follow up patch.

Fixes #57811
9 files changed
tree: 904dbf3ab7cedf9c1daa570a39ad0f3112dc25f2
  1. .ci/
  2. .github/
  3. bolt/
  4. clang/
  5. clang-tools-extra/
  6. cmake/
  7. compiler-rt/
  8. cross-project-tests/
  9. flang/
  10. libc/
  11. libclc/
  12. libcxx/
  13. libcxxabi/
  14. libunwind/
  15. lld/
  16. lldb/
  17. llvm/
  18. llvm-libgcc/
  19. mlir/
  20. offload/
  21. openmp/
  22. polly/
  23. pstl/
  24. runtimes/
  25. third-party/
  26. utils/
  27. .clang-format
  28. .clang-tidy
  29. .git-blame-ignore-revs
  30. .gitattributes
  31. .gitignore
  32. .mailmap
  33. CODE_OF_CONDUCT.md
  34. CONTRIBUTING.md
  35. LICENSE.TXT
  36. pyproject.toml
  37. README.md
  38. SECURITY.md
README.md

The LLVM Compiler Infrastructure

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