[Mlir-commits] [mlir] [mlir][sparse] Lower affine before SCF to CF in sparsifier (PR #219860)

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<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-mlir-sparse

Author: Kohei Yamaguchi (sott0n)

<details>
<summary>Changes</summary>

Fix the lowering order in the sparsifier pipeline by running `convert-scf-to-cf` after `lower-affine`.

Previously, `convert-scf-to-cf` ran while Affine control-flow operations could still be present. For example, lowering an `scf.if` nested inside an `affine.for` introduces multiple blocks into the loop body, violating `affine.for`'s single-block region requirement and causing verification to fail.

Running `lower-affine` first converts Affine control flow to SCF. The subsequent `convert-scf-to-cf` pass can then lower both the existing SCF operations and those introduced by Affine lowering to CFG-based control flow.

`expand-strided-metadata` remains before `lower-affine`, since it can introduce Affine operations.

Fixes #<!-- -->217895.

---
Full diff: https://github.com/llvm/llvm-project/pull/219860.diff


1 Files Affected:

- (modified) mlir/lib/Dialect/SparseTensor/Pipelines/SparseTensorPipelines.cpp (+1-1) 


``````````diff
diff --git a/mlir/lib/Dialect/SparseTensor/Pipelines/SparseTensorPipelines.cpp b/mlir/lib/Dialect/SparseTensor/Pipelines/SparseTensorPipelines.cpp
index d85966ec88f98..9e33544efbcce 100644
--- a/mlir/lib/Dialect/SparseTensor/Pipelines/SparseTensorPipelines.cpp
+++ b/mlir/lib/Dialect/SparseTensor/Pipelines/SparseTensorPipelines.cpp
@@ -67,9 +67,9 @@ void mlir::sparse_tensor::buildSparsifier(OpPassManager &pm,
   pm.addNestedPass<func::FuncOp>(createConvertLinalgToLoopsPass());
   pm.addNestedPass<func::FuncOp>(createConvertVectorToSCFPass());
   pm.addNestedPass<func::FuncOp>(memref::createExpandReallocPass());
-  pm.addNestedPass<func::FuncOp>(createSCFToControlFlowPass());
   pm.addPass(memref::createExpandStridedMetadataPass());
   pm.addPass(createLowerAffinePass());
+  pm.addNestedPass<func::FuncOp>(createSCFToControlFlowPass());
   pm.addPass(
       createConvertVectorToLLVMPass(options.convertVectorToLLVMOptions()));
   pm.addNestedPass<func::FuncOp>(createConvertComplexToStandardPass());

``````````

</details>


https://github.com/llvm/llvm-project/pull/219860