[Mlir-commits] [mlir] [mlir][xegpu] Improve XeGPU op verification logic for SIMT flavor and update tests. (PR #127920)

[Charitha Saumya]

================
@@ -307,6 +310,85 @@ LogicalResult TensorDescType::verify(
   return success();
 }
 
+// If tensor descriptor has a sg_map attribute it is used in SIMT mode.
+// In this mode, the distributed vector shape is determined as follows:
+// Definitions:
+//        wi_data_size = wi_data[0] × wi_data[1]
+//        subgroup_size = wi_layout[0] × wi_layout[1]
+//        distribution_unit_size = subgroup_size × wi_data_size
+// ---------------------------------------------------------------------
+// Case 1: Regular loads/stores.
+// ---------------------------------------------------------------------
+// Distributed vector shape must be:
+//        [chunk_size / wi_data_size, wi_data_size]
+// If the tensor descriptor shape is 1D, first dimension is ignored (set to 1).
+//        [wi_data_size]
+// ---------------------------------------------------------------------
+// Case 2: Block loads/stores
+// ---------------------------------------------------------------------
+// Additionalm definitions:
+//        tensor_size = tensor_desc[0] * .. * tensor_desc[r-1] * array_length
+//        n_distribution_units = tensor_size / distribution_unit_size
+// Given above definitions, the following conditions must be met:
+//        * tensor_desc[0] % (wi_layout[0] × wi_data[0]) == 0
+//        * tensor_desc[1] % (wi_layout[1] × wi_data[1]) == 0
+// Distributed vector shape must be:
+//        [n_distribution_units, wi_data_size]
+FailureOr<VectorType> TensorDescType::getDistributedVectorType() {
+  auto sgMap = llvm::dyn_cast_if_present<SGMapAttr>(getSgMap());
+  // If no sg_map is provided, tensor desc is not used in SIMT mode.
+  if (!sgMap)
+    return failure();
+
+  SmallVector<int64_t> wiData(sgMap.getWiData());
+  SmallVector<int64_t> wiLayout(sgMap.getWiLayout());
+  auto tdescShape = getShape();
+
+  auto wiDataSize = 1, sgSize = 1;
+  for (auto [wiDim, wiDataDim] : llvm::zip_equal(wiLayout, wiData)) {
+    wiDataSize *= wiDataDim;
+    sgSize *= wiDim;
+  }
+
+  // Case 1: regular loads/stores
+  auto scatterAttr =
+      llvm::dyn_cast_if_present<ScatterTensorDescAttr>(getEncoding());
+  if (scatterAttr) {
+    auto chunkSize = scatterAttr.getChunkSize().getInt();
+    // Check if the first dimension of the tensor descriptor shape is
+    // distributable.
+    if (tdescShape[0] % (wiLayout[0]) != 0)
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charithaintc wrote:

found that this already checked in verifier. converted to asserts. 

https://github.com/llvm/llvm-project/pull/127920