[Mlir-commits] [mlir] [mlir][vector] Add an eliminate-vector-masks pass (PR #226517)

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@llvm/pr-subscribers-mlir

Author: Dhairyashil R G (dhairyashilRG)

<details>
<summary>Changes</summary>

`eliminateVectorMasks` had no in-tree caller other than a test pass, so no pipeline could use it. This exposes it as an opt-in `-eliminate-vector-masks` pass and drops the test pass.

The pass rewrites `vector.create_mask` ops that can be proven all-true into `vector.constant_mask`; canonicalization then folds those away, so a masked transfer becomes an unmasked one. Mask sizes are bounded with `ValueBoundsOpInterface`, so a loop-derived size like `%dim - %iv` can be proven.

Scalable dimensions need a `vscale` range, given by `vscale-min`/`vscale-max`. Leaving them unset means fixed-size reasoning only; a half-specified or inverted range is rejected rather than silently ignored.

`eliminate-masks.mlir` keeps its checks and only switches its two RUN lines, which shows the pass behaves as the test pass did.

Follow-up to #<!-- -->221595, and the pass promised when #<!-- -->215340 was closed.

Context: https://discourse.llvm.org/t/rfc-should-vector-transfer-read-write-keep-in-bounds-measurements-on-the-masking-alternative/91649

Assisted-by: Claude


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Full diff: https://github.com/llvm/llvm-project/pull/226517.diff


5 Files Affected:

- (modified) mlir/include/mlir/Dialect/Vector/Transforms/Passes.td (+24) 
- (modified) mlir/lib/Dialect/Vector/Transforms/VectorMaskElimination.cpp (+33) 
- (added) mlir/test/Dialect/Vector/eliminate-masks-invalid-options.mlir (+11) 
- (modified) mlir/test/Dialect/Vector/eliminate-masks.mlir (+2-2) 
- (modified) mlir/test/lib/Dialect/Vector/TestVectorTransforms.cpp (-35) 


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</details>


https://github.com/llvm/llvm-project/pull/226517