[Mlir-commits] [mlir] [MLIR][XeGPU] Add distribution pattern for xegpu.load & store for sg to wi pass (PR #181917)

[Charitha Saumya]

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@@ -522,6 +594,80 @@ struct LowerVectorMultiReductionPattern
   }
 };
 
+/// Distributes a subgroup-level StoreScatter (xegpu.store) op to
+/// workitem-level.
+struct SgToWiStoreScatter : public OpConversionPattern<xegpu::StoreScatterOp> {
+  using OpConversionPattern<xegpu::StoreScatterOp>::OpConversionPattern;
+
+  LogicalResult
+  matchAndRewrite(xegpu::StoreScatterOp op, OpAdaptor adaptor,
+                  ConversionPatternRewriter &rewriter) const override {
+    xegpu::DistributeLayoutAttr layout = op.getAnchorLayout();
+    if (!layout)
+      return failure();
+
+    VectorType valueTy = op.getValueType();
+    if (!valueTy)
+      return failure();
+
+    // Check that all leading dimensions are unit dimensions.
+    int chunkSize = op.getChunkSize().value_or(1);
+    int effectiveVecRank = (chunkSize == 1) ? 1 : 2;
+    for (int i = 0; i < valueTy.getRank() - effectiveVecRank; i++) {
+      if (valueTy.getShape()[i] != 1)
+        return rewriter.notifyMatchFailure(
+            op, "Only unit dimensions allowed for the leading "
+                "dimensions of the store vector!");
+    }
+
+    auto expectedWiValueTyOrFailure =
+        xegpu::getDistVecTypeBasedOnLaneLayout(layout, valueTy);
+    if (failed(expectedWiValueTyOrFailure))
+      return rewriter.notifyMatchFailure(
+          op,
+          "unable to compute expected workitem vector type from lane layout");
+
+    VectorType expectedWiValueTy = expectedWiValueTyOrFailure.value();
+    VectorType supportedWiValueTy =
+        VectorType::get({expectedWiValueTy.getNumElements()},
+                        expectedWiValueTy.getElementType());
+
+    Value adaptedValue = adaptor.getValue();
+    if (adaptedValue.getType() != supportedWiValueTy)
+      adaptedValue =
+          vector::ShapeCastOp::create(rewriter, op.getLoc(), supportedWiValueTy,
+                                      adaptedValue)
+              .getResult();
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charithaintc wrote:

use `castValueTo`

https://github.com/llvm/llvm-project/pull/181917