[Mlir-commits] [mlir] [MLIR][XeGPU] Extend propagation and sg_to_lane distribution pass support broadcast with low rank and scalar source input (PR #170409)

[Charitha Saumya]

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@@ -1424,6 +1424,133 @@ struct VectorMultiReductionDistribution : public gpu::WarpDistributionPattern {
   }
 };
 
+/// This pattern distributes the `vector.broadcast` operation across lanes in a
+/// warp. The pattern supports three use cases:
+///
+/// 1) Broadcast a low-rank vector to high-rank vector: The low-rank input
+/// vector
+///    must have a slice layout of the result. If the distributed source and
+///    target vector types are identical, this lowers to a no-op; otherwise, it
+///    remains a broadcast but operates on distributed vectors.
+///
+/// 2) Broadcast a same-rank vector with identical layouts for source and
+/// target:
+///    The source vector must have unit dimensions, and lane_layout must be unit
+///    size for those unit dims. This always lowers to a no-op.
+///
+/// 3) Broadcast a scalar with no layout: This always lowers to a broadcast from
+///    scalar to distributed result type.
+///
+/// Example 1 (lowering to a broadcast with distributed types):
+/// ```
+/// %r = gpu.warp_execute_on_lane_0(%laneid)[32] -> (vector<8x1xf32>) {
+///   %0 = "some_def"() {layout_result_0 =
+///   #xegpu.slice<#xegpu.layout<lane_layout = [1, 32], lane_data = [1, 1]>,
+///   dims = [0]> } : () -> (vector<32xf32>) %2 = vector.broadcast %1
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charithaintc wrote:

formatting is broken. %2 should be in new line. 

https://github.com/llvm/llvm-project/pull/170409