[all-commits] [llvm/llvm-project] 878d35: [mlir][vector] Avoid setting padding by default to...

[Fabian Mora via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 878d3594ed74cd1153bc5cba2cb7a449702cdf34
      https://github.com/llvm/llvm-project/commit/878d3594ed74cd1153bc5cba2cb7a449702cdf34
  Author: Fabian Mora <fmora.dev at gmail.com>
  Date:   2025-06-30 (Mon, 30 Jun 2025)

  Changed paths:
    M mlir/include/mlir/Dialect/Arith/IR/Arith.h
    M mlir/include/mlir/Dialect/Vector/IR/Vector.td
    M mlir/include/mlir/Dialect/Vector/IR/VectorOps.td
    M mlir/lib/Dialect/Affine/Transforms/SuperVectorize.cpp
    M mlir/lib/Dialect/Arith/IR/ArithOps.cpp
    M mlir/lib/Dialect/ArmSVE/Transforms/LegalizeVectorStorage.cpp
    M mlir/lib/Dialect/Linalg/Transforms/Vectorization.cpp
    M mlir/lib/Dialect/Vector/IR/VectorOps.cpp
    M mlir/lib/Dialect/Vector/Transforms/VectorDistribute.cpp
    M mlir/lib/Dialect/Vector/Transforms/VectorTransferOpTransforms.cpp
    M mlir/test/Dialect/Affine/SuperVectorize/vectorize_1d.mlir
    M mlir/test/Dialect/Affine/SuperVectorize/vectorize_affine_apply.mlir
    M mlir/test/Dialect/ArmSVE/legalize-transfer-read.mlir
    M mlir/test/Dialect/Vector/vector-transfer-flatten.mlir
    M mlir/test/Dialect/Vector/vector-warp-distribute.mlir

  Log Message:
  -----------
  [mlir][vector] Avoid setting padding by default to `0` in `vector.transfer_read` prefer `ub.poison` (#146088)

Context:
`vector.transfer_read` always requires a padding value. Most of its
builders take no `padding` value and assume the safe value of `0`.
However, this should be a conscious choice by the API user, as it makes
it easy to introduce bugs.
For example, I found several occasions while making this patch that the
padding value was not getting propagated (`vector.transfer_read` was
transformed into another `vector.transfer_read`). These bugs, were
always caused because of constructors that don't require specifying
padding.

Additionally, using `ub.poison` as a possible default value is better,
as it indicates the user "doesn't care" about the actual padding value,
forcing users to specify the actual padding semantics they want.

With that in mind, this patch changes the builders in
`vector.transfer_read` to always having a `std::optional<Value> padding`
argument. This argument is never optional, but for convenience users can
pass `std::nullopt`, padding the transfer read with `ub.poison`.

---------

Signed-off-by: Fabian Mora <fabian.mora-cordero at amd.com>



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