[mlir][vector] Fix crash in ReorderCastOpsOnBroadcast with non-vector result

[Men-cotton]

Fixes a crash in ReorderCastOpsOnBroadcast by ensuring the cast result is a VectorType before applying the pattern.
A regression test has been added to mlir/test/Dialect/Vector/vector-sink.mlir.

Fixes: #126371

[llvmbot]

@llvm/pr-subscribers-mlir-vector

@llvm/pr-subscribers-mlir

Author: Men-cotton (Men-cotton)

Changes

Fixes a crash in ReorderCastOpsOnBroadcast by ensuring the cast result is a VectorType before applying the pattern.
A regression test has been added to mlir/test/Dialect/Vector/vector-sink.mlir.

Fixes: #126371

---

Full diff: https://github.com/llvm/llvm-project/pull/170985.diff

2 Files Affected:

• (modified) mlir/lib/Dialect/Vector/Transforms/VectorTransforms.cpp (+2)
• (modified) mlir/test/Dialect/Vector/vector-sink.mlir (+17)

diff --git a/mlir/lib/Dialect/Vector/Transforms/VectorTransforms.cpp b/mlir/lib/Dialect/Vector/Transforms/VectorTransforms.cpp
index 726da1e9a3d14..ad16b80a732b3 100644
--- a/mlir/lib/Dialect/Vector/Transforms/VectorTransforms.cpp
+++ b/mlir/lib/Dialect/Vector/Transforms/VectorTransforms.cpp
@@ -453,6 +453,8 @@ struct ReorderCastOpsOnBroadcast
                                 PatternRewriter &rewriter) const override {
     if (op->getNumOperands() != 1)
       return failure();
+    if (!isa<VectorType>(op->getResult(0).getType()))
+      return failure();
     auto bcastOp = op->getOperand(0).getDefiningOp<vector::BroadcastOp>();
     if (!bcastOp)
       return failure();
diff --git a/mlir/test/Dialect/Vector/vector-sink.mlir b/mlir/test/Dialect/Vector/vector-sink.mlir
index beaba52af1841..50ff63b44901a 100644
--- a/mlir/test/Dialect/Vector/vector-sink.mlir
+++ b/mlir/test/Dialect/Vector/vector-sink.mlir
@@ -850,3 +850,20 @@ func.func @negative_store_no_single_use(%arg0: memref<?xf32>, %arg1: index, %arg
   vector.store %0, %arg0[%arg1] : memref<?xf32>, vector<1xf32>
   return %0 : vector<1xf32>
 }
+
+// -----
+
+// CHECK-LABEL: func.func @broadcast_cast_non_vector_result
+// CHECK-SAME: (%[[ARG:.*]]: i64)
+// CHECK: %[[BCAST:.*]] = vector.broadcast %[[ARG]] : i64 to vector<26x7xi64>
+// CHECK: %[[CAST:.*]] = builtin.unrealized_conversion_cast %[[BCAST]] : vector<26x7xi64> to !llvm.array<26 x vector<7xi64>>
+// CHECK: return %[[CAST]] : !llvm.array<26 x vector<7xi64>>
+/// This test ensures that the `ReorderCastOpsOnBroadcast` pattern does not
+/// attempt to reorder a cast operation that produces a non-vector result type.
+/// Previously, this would crash because the pattern assumed the result was a
+/// vector type when creating the new inner broadcast.
+func.func @broadcast_cast_non_vector_result(%arg0: i64) -> !llvm.array<26 x vector<7xi64>> {
+  %0 = vector.broadcast %arg0 : i64 to vector<26x7xi64>
+  %1 = builtin.unrealized_conversion_cast %0 : vector<26x7xi64> to !llvm.array<26 x vector<7xi64>>
+  return %1 : !llvm.array<26 x vector<7xi64>>
+}