[Mlir-commits] [mlir] [MLIR][XeGPU] Remove the transpose attribte from Gather/Scatter ops and Cleanup the documents (PR #145389)

[Chao Chen]

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@@ -213,6 +213,37 @@ static LayoutInfo getDefaultSIMTLayoutInfo(VectorType vectorTy) {
                     LaneData({1, packingFactor}));
 }
 
+/// Helper to get the default layout for a vector type.
+static LayoutInfo getDefaultSIMTLayoutInfo(xegpu::TensorDescType tdescTy) {
+  // Expecting a 1D or 2D vector.
+  assert((tdescTy.getRank() == 1 || tdescTy.getRank() == 2) &&
+         "Expected 1D or 2D TensorDesc.");
+  // Expecting int or float element type.
+  assert(tdescTy.getElementType().isIntOrFloat() &&
+         "Expected int or float element type.");
+  // If the rank is 1, then return default layout for 1D vector.
+  if (tdescTy.getRank() == 1)
+    return getDefaultSIMTLayoutInfo(1);
+  // Packing factor is determined by the element type bitwidth.
+  unsigned bitwidth = tdescTy.getElementType().getIntOrFloatBitWidth();
+
+  if (tdescTy.isScattered()) {
+    int packingFactor =
+        bitwidth < xegpu::targetinfo::packedSizeInBitsForGatherScatter
+            ? xegpu::targetinfo::packedSizeInBitsForGatherScatter / bitwidth
+            : 1;
+    return LayoutInfo(LaneLayout({xegpu::targetinfo::subgroupSize, 1}),
+                      LaneData({1, packingFactor}));
+  }
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chencha3 wrote:

The semantic of scattered tensor_desc explicitly defines the layout it can handle. When its user requests a different layout, it will create a conflict. I think this how the conflict is detected, and then handled. please correct me if I am wrong.

https://github.com/llvm/llvm-project/pull/145389