[all-commits] [llvm/llvm-project] df1838: [Polly] Skip vectorize.enable for FP loops with di...

[Karthika Devi C via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: df1838f5d961f9587ca4f90d992bef81cc6155db
      https://github.com/llvm/llvm-project/commit/df1838f5d961f9587ca4f90d992bef81cc6155db
  Author: Karthika Devi C <kartc at qti.qualcomm.com>
  Date:   2026-07-15 (Wed, 15 Jul 2026)

  Changed paths:
    M polly/include/polly/CodeGen/LoopGenerators.h
    M polly/lib/CodeGen/IslAst.cpp
    M polly/lib/CodeGen/IslNodeBuilder.cpp
    M polly/lib/CodeGen/LoopGenerators.cpp
    M polly/test/CodeGen/Metadata/basic_vec_annotate.ll
    A polly/test/CodeGen/Metadata/skip_vec_annotate_fp_dist1.ll

  Log Message:
  -----------
  [Polly] Skip vectorize.enable for FP loops with dist=1 dependences (#205756)

When -polly-annotate-metadata-vectorize is active, Polly marks its
generated loops with llvm.loop.vectorize.enable=true. This is harmful
for loops with a loop-carried dependence of distance 1 that involve
floating-point operations: the Loop Vectorizer reorders FP operations
(e.g. scalar reduction like q = factor*q), producing results that differ
from the sequential scalar reference and causing correctness failures.

Two changes are made:

1. IslAst.cpp: add PollyVectorizeMetadata to the PerformParallelTest
gate so that dependence-distance computation is performed whenever
-polly-annotate-metadata-vectorize is passed, not only when
-polly-parallel or a vectorizer is active.

2. IslNodeBuilder.cpp / LoopGenerators.cpp: when a loop has a dist=1
dependence involving FP operations, omit the vectorize.enable annotation
entirely. This lets the Loop Vectorizer apply its own cost model and
legality checks decide.



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