[Mlir-commits] [mlir] [MLIR][XeGPU] Add pattern for arith.constant for wg to sg distribution (PR #151977)

[Nishant Patel]

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@@ -649,6 +649,48 @@ struct UnrealizedConversionCastOpPattern
   }
 };
 
+// This pattern distributes arith.constant op into subgroup-level constants
+struct WgToSgArithConstantOp : public OpConversionPattern<arith::ConstantOp> {
+  using OpConversionPattern<arith::ConstantOp>::OpConversionPattern;
+
+  LogicalResult
+  matchAndRewrite(arith::ConstantOp op, OneToNOpAdaptor adaptor,
+                  ConversionPatternRewriter &rewriter) const override {
+    auto vecAttr = dyn_cast<DenseElementsAttr>(op.getValue());
+    auto vecType = dyn_cast<VectorType>(op.getType());
+    if (!vecAttr || !vecAttr.isSplat() || !vecType)
+      return failure();
+
+    xegpu::LayoutAttr layout = xegpu::getLayoutAttr(op.getResult());
+    if (!layout || !layout.getSgLayout())
+      return failure();
+
+    ArrayRef<int64_t> wgShape = vecType.getShape();
+    SmallVector<int64_t> sgShape;
+    int count;
+    std::tie(sgShape, count) = getSgShapeAndCount(wgShape, layout);
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nbpatel wrote:

I dont think I understand the question. The pattern only works on vecType

https://github.com/llvm/llvm-project/pull/151977