[mlir][sparse] codegen for trivial tensor cast

Reviewed By: bixia

Differential Revision: https://reviews.llvm.org/D133176

mlir/lib/Dialect/SparseTensor/Transforms/SparseTensorCodegen.cpp

@@ -33,16 +33,6 @@ namespace {
 // Helper methods.
 //===----------------------------------------------------------------------===//
 
-/// Reorders stored dimension to original dimension.
-static unsigned toOrig(const SparseTensorEncodingAttr &enc, unsigned i) {
-  auto order = enc.getDimOrdering();
-  if (order) {
-    assert(order.isPermutation());
-    return order.getDimPosition(i);
-  }
-  return i;
-}
-
 /// Reorders original dimension to stored dimension.
 static unsigned toStored(const SparseTensorEncodingAttr &enc, unsigned i) {
   auto order = enc.getDimOrdering();
@@ -67,7 +57,6 @@ static Optional<Type> convertSparseTensorType(Type type) {
   Type idxType = idxWidth ? IntegerType::get(context, idxWidth) : indexType;
   Type ptrType = ptrWidth ? IntegerType::get(context, ptrWidth) : indexType;
   Type eltType = rType.getElementType();
-  ArrayRef<int64_t> shape = rType.getShape();
   //
   // Sparse tensor storage for rank-dimensional tensor is organized as a
   // single compound type with the following fields:
@@ -85,27 +74,18 @@ static Optional<Type> convertSparseTensorType(Type type) {
   //   memref<? x eltType> values        ; values
   // };
   //
-  int64_t linear = 1;
-  bool allDense = true;
   unsigned rank = rType.getShape().size();
   SmallVector<Type, 8> fields;
   // The dimSizes array.
   fields.push_back(MemRefType::get({rank}, indexType));
   // Per-dimension storage.
   for (unsigned r = 0; r < rank; r++) {
-    // Get the original dimension (ro) for the current stored dimension (r).
-    unsigned ro = toOrig(enc, r);
     // Dimension level types apply in order to the reordered dimension.
     // As a result, the compound type can be constructed directly in the given
     // order. Clients of this type know what field is what from the sparse
     // tensor type.
     switch (enc.getDimLevelType()[r]) {
     case SparseTensorEncodingAttr::DimLevelType::Dense:
-      // Linearize the size of consecutive dense dimensions.
-      if (ShapedType::isDynamic(shape[ro]) || ShapedType::isDynamic(linear))
-        linear = ShapedType::kDynamicSize;
-      else
-        linear *= shape[ro];
       break;
     case SparseTensorEncodingAttr::DimLevelType::Compressed:
     case SparseTensorEncodingAttr::DimLevelType::CompressedNu:
@@ -113,23 +93,17 @@ static Optional<Type> convertSparseTensorType(Type type) {
     case SparseTensorEncodingAttr::DimLevelType::CompressedNuNo:
       fields.push_back(MemRefType::get({ShapedType::kDynamicSize}, ptrType));
       fields.push_back(MemRefType::get({ShapedType::kDynamicSize}, idxType));
-      allDense = false;
-      linear = 1;
       break;
     case SparseTensorEncodingAttr::DimLevelType::Singleton:
     case SparseTensorEncodingAttr::DimLevelType::SingletonNu:
     case SparseTensorEncodingAttr::DimLevelType::SingletonNo:
     case SparseTensorEncodingAttr::DimLevelType::SingletonNuNo:
       fields.push_back(MemRefType::get({ShapedType::kDynamicSize}, idxType));
-      allDense = false;
-      linear = 1;
       break;
     }
   }
   // The values array.
-  int64_t nnz =
-      (rType.hasStaticShape() && allDense) ? linear : ShapedType::kDynamicSize;
-  fields.push_back(MemRefType::get({nnz}, eltType));
+  fields.push_back(MemRefType::get({ShapedType::kDynamicSize}, eltType));
   // Sparse tensor storage (temporarily) lives in a tuple. This allows a
   // simple 1:1 type conversion during codegen. A subsequent pass uses
   // a 1:N type conversion to expand the tuple into its fields.
@@ -241,6 +215,23 @@ public:
   }
 };
 
+/// Sparse codegen rule for trivial tensor casts.
+class SparseCastConverter : public OpConversionPattern<tensor::CastOp> {
+public:
+  using OpConversionPattern::OpConversionPattern;
+  LogicalResult
+  matchAndRewrite(tensor::CastOp op, OpAdaptor adaptor,
+                  ConversionPatternRewriter &rewriter) const override {
+    // Only rewrite identically annotated source/dest.
+    auto encDst = getSparseTensorEncoding(op.getType());
+    auto encSrc = getSparseTensorEncoding(op.getSource().getType());
+    if (!encDst || encDst != encSrc)
+      return failure();
+    rewriter.replaceOp(op, adaptor.getOperands());
+    return success();
+  }
+};
+
 /// Sparse conversion rule for pointer accesses.
 class SparseToPointersConverter : public OpConversionPattern<ToPointersOp> {
 public:
@@ -314,7 +305,7 @@ mlir::SparseTensorTypeToBufferConverter::SparseTensorTypeToBufferConverter() {
 /// the sparsification of linear algebra operations.
 void mlir::populateSparseTensorCodegenPatterns(TypeConverter &typeConverter,
                                                RewritePatternSet &patterns) {
-  patterns.add<SparseReturnConverter, SparseDimOpConverter,
+  patterns.add<SparseReturnConverter, SparseDimOpConverter, SparseCastConverter,
                SparseToPointersConverter, SparseToIndicesConverter,
                SparseToValuesConverter>(typeConverter, patterns.getContext());
 }