[all-commits] [llvm/llvm-project] 70311b: [unroll-and-jam] Document dependency patterns in d...

[Sebastian Pop via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 70311b453c73c8bc92362bb4035449f3a87210fc
      https://github.com/llvm/llvm-project/commit/70311b453c73c8bc92362bb4035449f3a87210fc
  Author: Sebastian Pop <spop at nvidia.com>
  Date:   2025-11-20 (Thu, 20 Nov 2025)

  Changed paths:
    M llvm/test/Transforms/LoopUnrollAndJam/dependencies.ll

  Log Message:
  -----------
  [unroll-and-jam] Document dependency patterns in dependencies.ll (NFC) (#156577)

Add detailed comments explaining each function's memory access patterns
and why they should/shouldn't be unroll-and-jammed:

- fore_aft_*: Dependencies between fore block and aft block
- fore_sub_*: Dependencies between fore block and sub block
- sub_aft_*: Dependencies between sub block and aft block
- sub_sub_*: Dependencies within sub block

- *_less: Backward dependency (i-1) - safe for fore/aft, fore/sub,
sub/aft; unsafe for sub/sub due to jamming conflicts
- *_eq: Same iteration dependency (i+0) - safe due to preserved
execution order
- *_more: Forward dependency (i+1) - unsafe due to write-after-write
races between unrolled iterations, except sub/sub case creates conflicts



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