[mlir][xegpu] Relax rank restriction of TensorDescType

mlir/include/mlir/Dialect/XeGPU/IR/XeGPUAttrs.td

@@ -43,8 +43,8 @@ def XeGPU_BlockTensorDescAttr: XeGPU_TensorDescAttr<"BlockTensorDesc", "block_td
 
   let parameters = (ins
     OptionalParameter<"MemorySpaceAttr">: $memory_space,
-    OptionalParameter<"IntegerAttr", "1">: $array_length,
-    OptionalParameter<"BoolAttr", "true">: $boundary_check
+    OptionalParameter<"IntegerAttr">: $array_length,
+    OptionalParameter<"BoolAttr">: $boundary_check
   );
 
   let builders = [
@@ -67,8 +67,11 @@ def XeGPU_ScatterTensorDescAttr: XeGPU_TensorDescAttr<"ScatterTensorDesc", "scat
         TensorDesc is located, `Global` device memory or `Shared` local memory.
         It is default to `Global`.
 
-    2.  `chunk_size`: indicates number of contiguous elements accessed for each
-        offset, default is 1. It is used with `scattered` attr only.
+    2. `chunk_size`: Specifies the number of contiguous elements accessed per offset.
+      The default value is 1. While XeGPU supports a range of chunk sizes, hardware
+      may only allow specific values (e.g., 1, 2, 3, 4, 8, 16, 32, 64, 128, 256).
+      Therefore, XeGPU will legalize the chunk size as needed prior to lowering to
+      hardware instructions.
   }];
 
   let parameters = (ins
@@ -91,7 +94,11 @@ def XeGPU_ScatterTensorDescAttr: XeGPU_TensorDescAttr<"ScatterTensorDesc", "scat
     )>
   ];
 
-  let genVerifyDecl = 1;
+  let extraClassDeclaration = [{
+    int64_t getChunkSizeAsInt() {
+      return getChunkSize().getInt();
+    }
+  }];
  }
 
 //===----------------------------------------------------------------------===//

mlir/include/mlir/Dialect/XeGPU/IR/XeGPUOps.td

@@ -757,6 +757,8 @@ def XeGPU_UpdateOffsetOp: XeGPU_Op<"update_offset",
   let assemblyFormat = [{
     $TensorDesc `,` $offsets attr-dict `:` qualified(type($TensorDesc)) `,` type($offsets)
   }];
+
+  let hasVerifier = 1;
 }
 
 def XeGPU_DpasOp : XeGPU_Op<"dpas", [Pure, AllElementTypesMatch<["lhs", "rhs"]>]> {

mlir/include/mlir/Dialect/XeGPU/IR/XeGPUTypes.td

@@ -17,12 +17,12 @@ def XeGPU_IntType: AnyTypeOf<[I1, I8, I16, I32, I64, SI1, SI8, SI16, SI32, SI64,
 def XeGPU_FloatType: AnyTypeOf<[F16, F32, F64, BF16, TF32]>;
 def XeGPU_ScalarType: AnyTypeOf<[XeGPU_IntType, XeGPU_FloatType]>;
 def XeGPU_BaseAddrType: AnyTypeOf<[Non0RankedMemRefOf<[XeGPU_ScalarType]>, UI64, UI32, I64, I32]>;
-def XeGPU_DpasOprType: VectorOfRankAndType<[1, 2, 3], [XeGPU_ScalarType]>;
-def XeGPU_DpasResType: VectorOfRankAndType<[1, 2], [XeGPU_ScalarType]>;
-def XeGPU_OffsetType: VectorOfRankAndType<[1], [Index]>;
-def XeGPU_MaskType: AnyTypeOf<[VectorOfRankAndType<[1], [I1]>, I1]>;
-def XeGPU_ValueType: AnyTypeOf<[VectorOfRankAndType<[1,2,3,4], [XeGPU_ScalarType]>, XeGPU_ScalarType]>;
-def XeGPU_Vector2DType: VectorOfRankAndType<[2], [XeGPU_ScalarType]>;
+def XeGPU_DpasOprType: FixedVectorOfRankAndType<[1, 2, 3], [XeGPU_ScalarType]>;
+def XeGPU_DpasResType: FixedVectorOfRankAndType<[1, 2], [XeGPU_ScalarType]>;
+def XeGPU_OffsetType: FixedVectorOfNonZeroRankOf<[Index]>;
+def XeGPU_MaskType: FixedVectorOfNonZeroRankOf<[I1]>;
+def XeGPU_ValueType: FixedVectorOfNonZeroRankOf<[XeGPU_ScalarType]>;
+def XeGPU_Vector2DType: FixedVectorOfRankAndType<[2], [XeGPU_ScalarType]>;
 
 // common base class for types in XeGPU dialect
 class XeGPUTypeDef<string name, string typeMnemonic, list<Trait> traits = [],
@@ -118,7 +118,6 @@ def XeGPU_TensorDesc: XeGPUTypeDef<"TensorDesc", "tensor_desc",
   ];
 
   let extraClassDeclaration = [{
-    using TensorType::clone;
     using mlir::ShapedType::Trait<TensorDescType>::getElementTypeBitWidth;
     using mlir::ShapedType::Trait<TensorDescType>::getRank;
     using mlir::ShapedType::Trait<TensorDescType>::getNumElements;
@@ -184,10 +183,8 @@ def XeGPU_TensorDesc: XeGPUTypeDef<"TensorDesc", "tensor_desc",
     int getChunkSize() {
       auto attr = getEncoding();
       auto scatter_attr = mlir::dyn_cast_if_present<ScatterTensorDescAttr>(attr);
-      assert((!attr || scatter_attr) && "invalid on non ScatterTensorDescAttr.");
-      if (scatter_attr)
-        return scatter_attr.getChunkSize().getInt();
-      return 1;
+      assert(scatter_attr && "invalid on non ScatterTensorDescAttr.");
+      return scatter_attr.getChunkSizeAsInt();
     }
 
     /// Helper to drop all layout information from the TensorDesc type.

mlir/lib/Dialect/XeGPU/IR/XeGPUDialect.cpp

@@ -125,18 +125,6 @@ ScatterTensorDescAttr::get(mlir::MLIRContext *context,
   return Base::get(context, scopeAttr, chunkSizeAttr);
 }
 
-LogicalResult ScatterTensorDescAttr::verify(
-    llvm::function_ref<mlir::InFlightDiagnostic()> emitError,
-    MemorySpaceAttr memory_space, IntegerAttr chunk_size) {
-  int64_t chunkSize = chunk_size.getInt();
-  SmallVector<int64_t> supportedChunkSizes = {1,  2,  3,  4,   8,
-                                              16, 32, 64, 128, 256};
-  if (!llvm::is_contained(supportedChunkSizes, chunkSize))
-    return emitError() << "invalid chunk size";
-
-  return success();
-}
-
 //===----------------------------------------------------------------------===//
 // XeGPU_LayoutAttr
 //===----------------------------------------------------------------------===//
@@ -310,15 +298,16 @@ LogicalResult TensorDescType::verify(
     llvm::ArrayRef<int64_t> shape, mlir::Type elementType,
     mlir::Attribute encoding, mlir::Attribute layout) {
   size_t rank = shape.size();
-  if (rank != 1 && rank != 2)
-    return emitError() << "expected 1D or 2D tensor";
+
+  if (rank == 0)
+    return emitError() << "expected non-zero rank tensor";
 
   auto blockAttr = mlir::dyn_cast_if_present<BlockTensorDescAttr>(encoding);
   if (blockAttr) {
     MemorySpaceAttr memorySpaceAttr = blockAttr.getMemorySpace();
-    if (rank == 2 && memorySpaceAttr &&
+    if (rank > 1 && memorySpaceAttr &&
         memorySpaceAttr.getValue() == MemorySpace::SLM)
-      return emitError() << "SLM is not supported for 2D block tensor";
+      return emitError() << "SLM is only supported for 1D block tensor";
   }
 
   // for gather and scatter ops, Low-precision types are packed in 32-bit units.
@@ -329,22 +318,18 @@ LogicalResult TensorDescType::verify(
           : 1;
   auto scatterAttr = mlir::dyn_cast_if_present<ScatterTensorDescAttr>(encoding);
   if (scatterAttr) {
-    // Expected tensor ranks for scattered data:
-    //   - 1D tensor for fully non-contiguous elements (chunk size == 1)
-    //   - 2D tensor for scattered blocks (chunk size > 1)
-    unsigned chunkSize = scatterAttr.getChunkSize().getInt();
+    int64_t chunkSize = scatterAttr.getChunkSizeAsInt();
     if (rank == 1 && chunkSize != 1)
       return emitError() << "expected non-contiguous elements for 1D tensor";
-    if (rank == 2 && chunkSize < 2)
-      return emitError() << "expected chunk blocks for 2D tensor";
+
     // If chunk size > 1, the second dimension of the tensor shape must be
-    // equal to chunk size and it must be a multiple of the packing factor.
+    // equal to chunk size and it must be a multiple of the
+    // chunkAlignmentFactor.
     if (chunkSize > 1) {
       if (shape.back() != chunkSize)
-        return emitError() << "expected tensor shape[1] to match chunk size";
+        return emitError() << "expected last dim of tensor to match chunk size";
       if (shape.back() % chunkAlignmentFactor != 0)
-        return emitError() << "expected tensor shape[1] to be a multiple of "
-                              "chunk alignment factor "
+        return emitError() << "expected last dim of tensor to be a multiple of "
                            << chunkAlignmentFactor;
     }
   }
@@ -357,17 +342,13 @@ LogicalResult TensorDescType::verify(
     auto laneData = layoutAttr.getLaneData();
     if (scatterAttr && laneData) {
       // Validate subgroup mapping rules for scattered tensors.
-      // A work-item's slice of the tensor with shape [sg_size] or
-      // [sg_size, chunk_size] will be [1] or [1, 32/element_ty_bit_width]
-      // respectively, the mapping should reflect that. This is because each
-      // work item access data in 32 bit granularity.
-
-      if (rank > 1 && laneData[0] != 1)
+      // if chunkSize > 1, the last dimension of the tensor should
+      // be distributed in the units divisible by chunkAlignmentFactor.
+      int64_t chunkSize = scatterAttr.getChunkSizeAsInt();
+      if (chunkSize > 1 && laneData[rank - 1] % chunkAlignmentFactor)
         return emitError()
-               << "cannot map over non-contiguous scattered row elements";
-      if (laneData[rank - 1] != chunkAlignmentFactor)
-        return emitError() << "work item data mapping must match the number of "
-                              "contiguous elements";
+               << "expected last dim of lane_data to be a multiple of: "
+               << chunkAlignmentFactor;
     }
 
     if (!XeGPUDialect::isEvenlyDistributable(shape, layoutAttr)) {

mlir/lib/Dialect/XeGPU/IR/XeGPUOps.cpp

@@ -87,9 +87,12 @@ isValidGatherScatterParams(Type maskTy, VectorType valueTy,
     return emitError()
            << "Value should have the same element type as TensorDesc.";
 
-  if (tdescShape[0] != maskShape[0])
+  llvm::SmallVector<int64_t> expectedMaskShape(tdescShape);
+  if (chunkSize > 1)
+    expectedMaskShape.pop_back();
+  if (expectedMaskShape != maskShape)
     return emitError()
-           << "dim-0 of the Mask and TensorDesc should be the same.";
+           << "Mask should match TensorDesc except the chunk size dim.";
 
   // a valid shape for SIMT case
   if (valueTy.getRank() == 1 && valueTy.getNumElements() == chunkSize) {
@@ -203,11 +206,9 @@ LogicalResult CreateNdDescOp::verify() {
         "is a memref) should match with each other.");
 
   // check result TensorDesc rank
-  invalidRank = (getType().getRank() > 2 || getType().getRank() > rank);
-
-  if (invalidRank)
+  if (getType().getRank() > rank)
     return emitOpError(
-        "Expecting the TensorDesc rank is up to 2 and not greater than the "
+        "Expecting the TensorDesc rank is not greater than the "
         "ranks of shape, strides, offsets or the memref source.");
 
   if (invalidElemTy)
@@ -247,9 +248,6 @@ LogicalResult LoadNdOp::verify() {
   auto tdescTy = getTensorDescType();
   auto valueTy = getType();
 
-  if (tdescTy.getRank() > 2)
-    return emitOpError("Expecting a 1D/2D TensorDesc.\n");
-
   if (tdescTy.isScattered())
     return emitOpError("Expects a non-scattered TensorDesc.\n");
 
@@ -316,15 +314,13 @@ LogicalResult LoadNdOp::verify() {
   }
 
   auto array_len = tdescTy.getArrayLength();
-  if (array_len > 1) {
+  if (array_len > 1)
     tdescShape.insert(tdescShape.begin(), array_len);
-  }
 
-  if (tdescShape != valueShape) {
+  if (tdescShape != valueShape)
     return emitOpError() << "Result shape " << makeString(valueShape)
                          << " is not consistent with tensor descriptor "
                          << tdescTy;
-  }
 
   return success();
 }
@@ -336,9 +332,6 @@ LogicalResult StoreNdOp::verify() {
   auto dstTy = getTensorDescType(); // Tile
   auto valTy = getValueType();      // Vector
 
-  if (dstTy.getRank() > 2)
-    return emitOpError("Expecting a 1D/2D TensorDesc.\n");
-
   if (dstTy.isScattered())
     return emitOpError("Expects a non-scattered TensorDesc.\n");
 
@@ -370,22 +363,21 @@ LogicalResult StoreNdOp::verify() {
       return emitOpError()
              << "TensorDesc doesn't need LayoutAttr for SIMT code";
 
-    if (tdescElems % valueElems) {
+    if (tdescElems % valueElems)
       return emitOpError()
              << "Value shape " << makeString(getShapeOf(valTy))
              << " is not a valid distribution for tensor descriptor " << dstTy;
-    }
+
     return success();
   }
 
   // SIMD code should have the same shape as the tensor descriptor.
   auto tdescShape = getShapeOf(dstTy);
   auto valueShape = getShapeOf(valTy);
-  if (tdescShape != valueShape) {
+  if (tdescShape != valueShape)
     return emitOpError() << "Value shape " << makeString(valueShape)
                          << " is not consistent with tensor descriptor "
                          << dstTy;
-  }
 
   return success();
 }
@@ -450,24 +442,7 @@ LogicalResult CreateDescOp::verify() {
 
   // check total size
   auto chunkSize = tdescTy.getChunkSize();
-  auto elemBits = tdescTy.getElementType().getIntOrFloatBitWidth();
-  auto bitsPerLane = elemBits * chunkSize;
-  if (chunkSize > 1 && bitsPerLane % 32) {
-    // For 8-bit and 16-bit data, the hardware only supports chunk size of 1.
-    // For 32-bit data, the hardware can support larger larger chunk size. So
-    // we can bitcast 8-bit/16-bit data to 32-bit data for better performance.
-    // But this requires the total size is 32 bit aligned to make the
-    // optimization work.
-    return emitOpError(
-        "access size (chunk_size * sizeof(elemTy)) should be 32-bit aligned.");
-  }
-
-  auto lscConstraints = 512 * 8; // each access is upto 512 bytes.
-  if (elemBits * tdescTy.getNumElements() > lscConstraints)
-    return emitOpError("total access size (simd_lanes * chunk_size * "
-                       "sizeof(elemTy)) is upto 512 bytes.");
-
-  SmallVector<int64_t> shape({(int64_t)getNumOffsets()});
+  SmallVector<int64_t> shape(getOffsetsType().getShape());
   if (chunkSize != 1)
     shape.push_back(chunkSize);
 
@@ -563,6 +538,23 @@ void UpdateOffsetOp::build(OpBuilder &builder, OperationState &state,
   build(builder, state, tensorDesc, ofrs);
 }
 
+LogicalResult UpdateOffsetOp::verify() {
+  auto tdescTy = getTensorDescType();
+  if (!tdescTy.isScattered())
+    return emitOpError("Expects a scattered TensorDesc.\n");
+
+  SmallVector<int64_t> expectedOffsetShape = getShapeOf(tdescTy);
+  SmallVector<int64_t> offsetShape = getShapeOf(getOffsetsType());
+  if (tdescTy.getChunkSize() > 1)
+    expectedOffsetShape.pop_back();
+
+  if (expectedOffsetShape != offsetShape)
+    return emitOpError(
+        "Offsets should match TensorDesc except the chunk size dim.");
+
+  return success();
+}
+
 //===----------------------------------------------------------------------===//
 // XeGPU_DpasOp
 //===----------------------------------------------------------------------===//

mlir/lib/Dialect/XeGPU/Transforms/XeGPUBlocking.cpp

@@ -303,9 +303,7 @@ void XeGPUBlockingPass::runOnOperation() {
       // If the encoding is a ScatterTensorDescAttr, we need to
       // potentially adjust the chunk size based on the inst_data.
       if (tdescTy.isScattered()) {
-        auto scatterAttr =
-            llvm::dyn_cast_if_present<xegpu::ScatterTensorDescAttr>(encoding);
-        int64_t chunkSize = scatterAttr.getChunkSize().getInt();
+        int64_t chunkSize = tdescTy.getChunkSize();
 
         if (chunkSize > 1) {
           int64_t blockedChunkSize = chunkSize;
@@ -315,7 +313,7 @@ void XeGPUBlockingPass::runOnOperation() {
 
           // To create a new attribute with a different chunk_size:
           auto newEncoding = xegpu::ScatterTensorDescAttr::get(
-              ctx, scatterAttr.getMemorySpace().getValue(), blockedChunkSize);
+              ctx, tdescTy.getMemorySpace(), blockedChunkSize);
 
           encoding = newEncoding;
         }

mlir/lib/Dialect/XeGPU/Transforms/XeGPUUnroll.cpp

@@ -625,9 +625,6 @@ struct UnrollUpdateOffsetOp : public UnrollPattern<xegpu::UpdateOffsetOp> {
     Location loc = op.getLoc();
     xegpu::TensorDescType tdescTy = op.getTensorDescType();
 
-    if (tdescTy.getRank() > 2)
-      return failure();
-
     if (!tdescTy.isScattered())
       return failure();