[SparseTIR] Introduce SpIterVar (apache#6)

* [SparseTIR] Introduce SpIterVar

* Add conversion to PrimExpr

include/tvm/tir/sparse.h

@@ -355,6 +355,64 @@ class SparseBuffer : public ObjectRef {
   TVM_DEFINE_OBJECT_REF_METHODS(SparseBuffer, ObjectRef, SparseBufferNode);
 };
 
+enum class SpIterKind : int {
+  kDenseFixed = 0,
+  kDenseVariable = 1,
+  kSparseFixed = 2,
+  kSparseVariable = 3
+};
+
+/*!
+ * \brief Iterator variables in SparseTIR
+ */
+class SpIterVarNode : public Object {
+ public:
+  Var var;
+  PrimExpr max_extent;
+  SpIterKind kind;
+  Optional<Axis> axis;
+
+  void VisitAttrs(AttrVisitor* v) {
+    v->Visit("var", &var);
+    v->Visit("max_extent", &max_extent);
+    v->Visit("axis", &axis);
+    v->Visit("kind", &kind);
+  }
+
+  bool SEqualReduce(const SpIterVarNode* other, SEqualReducer equal) const {
+    return equal(var, other->var) && equal(max_extent, other->max_extent) &&
+           equal(axis, other->axis) && equal(kind, other->kind);
+  }
+
+  void SHashReduce(SHashReducer hash_reduce) const {
+    hash_reduce(var);
+    hash_reduce(max_extent);
+    hash_reduce(axis);
+    hash_reduce(kind);
+  }
+
+  static constexpr const char* _type_key = "tir.sparse.SpIterVar";
+  static constexpr const bool _type_has_method_sequal_reduce = true;
+  static constexpr const bool _type_has_method_shash_reduce = true;
+  TVM_DECLARE_FINAL_OBJECT_INFO(SpIterVarNode, Object);
+};
+
+class SpIterVar : public ObjectRef {
+ public:
+  TVM_DLL explicit SpIterVar(String name, PrimExpr max_extent, SpIterKind kind,
+                             Optional<Axis> axis = NullOpt);
+
+  /*!
+   * \return the corresponding var in the IterVar.
+   */
+  inline operator PrimExpr() const;
+
+  TVM_DEFINE_OBJECT_REF_METHODS(SpIterVar, ObjectRef, SpIterVarNode);
+};
+
+// inline implementations
+inline SpIterVar::operator PrimExpr() const { return (*this)->var; }
+
 }  // namespace tir
 }  // namespace tvm
 

python/tvm/tir/sparse.py

@@ -20,6 +20,7 @@
 import tvm._ffi
 from tvm.ir import PrimExpr
 from tvm.runtime import Object, const
+from tvm.tir import Var
 
 from . import _ffi_api
 from .buffer import Buffer
@@ -166,7 +167,7 @@ def __init__(self, axis_parent_map) -> None:
 
 
 @tvm._ffi.register_object("tir.sparse.SparseBuffer")
-class SparseBuffer:
+class SparseBuffer(Object):
     """SparseBuffer node
 
     Parameters
@@ -197,3 +198,39 @@ def __init__(self, tree, axes, data, name, dtype=None):
         self.__init_handle_by_constructor__(
             _ffi_api.SparseBuffer, tree, axes, data, name, dtype  # type: ignore
         )
+
+
+@tvm._ffi.register_object("tir.sparse.SpIterVar")
+class SpIterVar(Object):
+    """IterVar in SparseTIR
+
+    Parameters
+    ----------
+    var : Var
+        The var of the SpIterVar
+
+    max_extent : PrimExpr
+        The maximum extent of the SpIterVar
+
+    kind : int
+        The kind of the SpIterVar
+
+    axis : Optional[Axis]
+        The axis over which the SpIterVar iterates. Required to be defined
+        when `kind` is not `DenseFixed`
+    """
+    var: Var
+    max_extent: PrimExpr
+    kind: int
+    axis: Optional[Axis]
+
+    DenseFixed = 0
+    DenseVariable = 1
+    SparseFixed = 2
+    SparseVariable = 3
+
+    def __init__(self, var, max_extent, kind, axis=None):
+        self.__init_handle_by_constructor__(
+            _ffi_api.SpIterVar, var, max_extent, kind, axis  # type: ignore
+        )
+

src/tir/ir/sparse.cc

@@ -163,5 +163,28 @@ TVM_REGISTER_GLOBAL("tir.sparse.SparseBuffer")
       return SparseBuffer(tree, axes, data, name, dtype);
     });
 
+// SpIterVar
+SpIterVar::SpIterVar(String name, PrimExpr max_extent, SpIterKind kind, Optional<Axis> axis) {
+  ObjectPtr<SpIterVarNode> node = make_object<SpIterVarNode>();
+
+  if (kind != SpIterKind::kDenseFixed) {
+    CHECK(axis.defined()) << "ValueError: To create a SpIterVar that is not fixed-dense, one must "
+                             "specify the axis over which the SpIterVar iterates";
+  }
+
+  node->var = Var(std::move(name));
+  node->max_extent = std::move(max_extent);
+  node->kind = kind;
+  node->axis = std::move(axis);
+  data_ = std::move(node);
+}
+
+TVM_REGISTER_NODE_TYPE(SpIterVarNode);
+
+TVM_REGISTER_GLOBAL("tir.sparse.SpIterVar")
+    .set_body_typed([](String name, PrimExpr max_extent, SpIterKind kind, Optional<Axis> axis) {
+      return SpIterVar(name, max_extent, kind, axis);
+    });
+
 }  // namespace tir
 }  // namespace tvm