[Mlir-commits] [mlir] [mlir][SparseTensor] Fix invalid IR in `ForallRewriter` pattern (PR #74547)

[llvmlistbot at llvm.org]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-mlir-sparse

Author: Matthias Springer (matthias-springer)

<details>
<summary>Changes</summary>

The `ForallRewriter` pattern used to generate invalid IR:
```
mlir/test/Dialect/SparseTensor/GPU/gpu_combi.mlir:0:0: error: 'scf.for' op expects region #<!-- -->0 to have 0 or 1 blocks
mlir/test/Dialect/SparseTensor/GPU/gpu_combi.mlir:0:0: note: see current operation:
"scf.for"(%8, %2, %9) ({
^bb0(%arg5: index):
  // ...
  "scf.yield"() : () -> ()
^bb1(%10: index):  // no predecessors
  "scf.yield"() : () -> ()
}) : (index, index, index) -> ()
```

This commit fixes tests such as `mlir/test/Dialect/SparseTensor/GPU/gpu_combi.mlir` when verifying the IR after each pattern application (#<!-- -->74270).

---
Full diff: https://github.com/llvm/llvm-project/pull/74547.diff


1 Files Affected:

- (modified) mlir/lib/Dialect/SparseTensor/Transforms/SparseGPUCodegen.cpp (+4) 


``````````diff
diff --git a/mlir/lib/Dialect/SparseTensor/Transforms/SparseGPUCodegen.cpp b/mlir/lib/Dialect/SparseTensor/Transforms/SparseGPUCodegen.cpp
index 927fc71f84a85..5155cab772d44 100644
--- a/mlir/lib/Dialect/SparseTensor/Transforms/SparseGPUCodegen.cpp
+++ b/mlir/lib/Dialect/SparseTensor/Transforms/SparseGPUCodegen.cpp
@@ -309,6 +309,10 @@ static void genGPUCode(PatternRewriter &rewriter, gpu::GPUFuncOp gpuFunc,
   //   }
   Value upper = irMap.lookup(forallOp.getUpperBound()[0]);
   scf::ForOp forOp = rewriter.create<scf::ForOp>(loc, row, upper, inc);
+  // The scf.for builder creates an empty block. scf.for does not allow multiple
+  // blocks in its region, so delete the block before `cloneRegionBefore` adds
+  // an additional block.
+  rewriter.eraseBlock(forOp.getBody());
   rewriter.cloneRegionBefore(forallOp.getRegion(), forOp.getRegion(),
                              forOp.getRegion().begin(), irMap);
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/74547