[REFACTOR][IR] Use PrimType for compiler dtypes

Unify compiler-facing PrimExpr dtype state around PrimType as the source of expression type truth, while keeping runtime/storage dtype values as raw DLDataType at ABI and storage boundaries.

This squashes the PrimType refactor, review/CI follow-ups, raw dtype boundary repairs, and the benchmark-confirmed rewrite hot-path recovery into one PR commit.

Author: tqchen

include/tvm/ir/base_expr.h

@@ -0,0 +1,320 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+/*!
+ * \file tvm/ir/base_expr.h
+ * \brief Base expression and primitive type nodes.
+ */
+#ifndef TVM_IR_BASE_EXPR_H_
+#define TVM_IR_BASE_EXPR_H_
+
+#include <tvm/ffi/cast.h>
+#include <tvm/ffi/dtype.h>
+#include <tvm/ffi/reflection/registry.h>
+#include <tvm/ir/source_map.h>
+
+#include <cstddef>
+#include <cstdint>
+
+namespace tvm {
+
+/*!
+ * \brief Type is the base type of all types.
+ *
+ * TVM's type system contains following subclasses:
+ *
+ * - PrimType: type of primitive type values used in the low-level IR.
+ * - FuncType: type of a function.
+ * - TensorType: type of certain Tensor values in the expression.
+ *
+ * There are also advanced types to support generic(polymorphic types).
+ * \sa Type
+ */
+class TypeNode : public ffi::Object {
+ public:
+  /*!
+   * \brief Span that points to the original source code.
+   *        Reserved debug information.
+   */
+  mutable Span span;
+
+  static void RegisterReflection() {
+    namespace refl = tvm::ffi::reflection;
+    // span do not participate in structural equal and hash.
+    refl::ObjectDef<TypeNode>().def_ro("span", &TypeNode::span, refl::DefaultValue(Span()),
+                                       refl::AttachFieldFlag::SEqHashIgnore());
+  }
+
+  static constexpr TVMFFISEqHashKind _type_s_eq_hash_kind = kTVMFFISEqHashKindTreeNode;
+
+  static constexpr const uint32_t _type_child_slots = 14;
+  TVM_FFI_DECLARE_OBJECT_INFO("ir.Type", TypeNode, ffi::Object);
+};
+
+/*!
+ * \brief Managed reference to TypeNode.
+ * \sa TypeNode
+ */
+class Type : public ffi::ObjectRef {
+ public:
+  TVM_FFI_DEFINE_OBJECT_REF_METHODS_NULLABLE(Type, ffi::ObjectRef, TypeNode);
+};
+
+/*!
+ * \brief Primitive data types used in the low-level IR.
+ *
+ * PrimType represents POD-values and handles that are
+ * not automatically managed by the runtime.
+ *
+ * \sa PrimType
+ */
+class PrimTypeNode final : public TypeNode {
+ public:
+  /*!
+   * \brief The raw DLPack dtype represented by this primitive type.
+   */
+  DLDataType dtype;
+
+  static void RegisterReflection() {
+    namespace refl = tvm::ffi::reflection;
+    refl::ObjectDef<PrimTypeNode>().def_ro("dtype", &PrimTypeNode::dtype);
+  }
+  TVM_FFI_DECLARE_OBJECT_INFO_FINAL("ir.PrimType", PrimTypeNode, TypeNode);
+};
+
+/*
+ * \brief Managed reference to PrimTypeNode.
+ * \sa PrimTypeNode
+ */
+class PrimType final : public Type {
+ public:
+  /*!
+   * \brief Construct from a raw DLPack dtype.
+   * \param dtype The corresponding DLPack dtype.
+   */
+  TVM_DLL explicit PrimType(DLDataType dtype);
+
+  /*!
+   * \brief Construct from DLPack dtype fields.
+   * \param code The DLPack dtype code.
+   * \param bits The scalar bit width.
+   * \param lanes The fixed lane count.
+   */
+  TVM_DLL PrimType(DLDataTypeCode code, int bits, int lanes = 1);
+
+  /*! \brief Construct a signed integer type with fixed lanes. */
+  TVM_DLL static PrimType Int(int bits, int lanes = 1);
+  /*! \brief Construct an unsigned integer type with fixed lanes. */
+  TVM_DLL static PrimType UInt(int bits, int lanes = 1);
+  /*! \brief Construct a floating-point type with fixed lanes. */
+  TVM_DLL static PrimType Float(int bits, int lanes = 1);
+  /*! \brief Construct a bfloat type with fixed lanes. */
+  TVM_DLL static PrimType BFloat(int bits, int lanes = 1);
+  /*! \brief Construct a boolean type with fixed lanes. */
+  TVM_DLL static PrimType Bool(int lanes = 1);
+  /*! \brief Construct an opaque handle type. */
+  TVM_DLL static PrimType Handle(int bits = 64, int lanes = 1);
+  /*! \brief Construct the void sentinel type, encoded as handle(0, 0). */
+  TVM_DLL static PrimType Void();
+  /*!
+   * \brief Construct a scalable vector type.
+   * \param code The DLPack dtype code.
+   * \param bits The scalar bit width.
+   * \param lanes The positive vscale factor to encode in the DLPack lane field.
+   */
+  TVM_DLL static PrimType ScalableVector(DLDataTypeCode code, int bits, int lanes);
+
+  /*! \return The DLPack dtype code. */
+  TVM_FFI_INLINE DLDataTypeCode code() const {
+    return static_cast<DLDataTypeCode>(static_cast<int>(get()->dtype.code));
+  }
+
+  /*! \return The scalar bit width. */
+  TVM_FFI_INLINE int32_t bits() const { return get()->dtype.bits; }
+
+  /*!
+   * \return The fixed lane count.
+   * \note Throws on scalable vector types, where the encoded lane field stores a vscale factor.
+   */
+  TVM_FFI_INLINE int32_t lanes() const {
+    int16_t encoded_lanes = static_cast<int16_t>(get()->dtype.lanes);
+    if (TVM_FFI_PREDICT_FALSE(encoded_lanes < 0)) {
+      TVM_FFI_THROW(InternalError)
+          << "Can't fetch the lanes of a scalable vector at a compile time.";
+    }
+    return encoded_lanes;
+  }
+
+  /*!
+   * \brief Check the scalar element code and bit width.
+   * \note Lane count and scalable-vector encoding are intentionally ignored.
+   */
+  TVM_FFI_INLINE bool MatchesElementType(DLDataTypeCode code, int bits) const {
+    DLDataType dtype = get()->dtype;
+    return dtype.code == static_cast<uint8_t>(code) && dtype.bits == bits;
+  }
+
+  /*!
+   * \brief Check whether the dtype code matches any of the provided DLPack codes.
+   * \note Bit width and lanes are intentionally ignored.
+   */
+  template <typename... Codes>
+  TVM_FFI_INLINE bool MatchesCode(Codes... codes) const {
+    uint8_t dtype_code = get()->dtype.code;
+    return ((dtype_code == static_cast<uint8_t>(codes)) || ...);
+  }
+
+  /*! \brief Whether this type is a scalar, excluding fixed and scalable vectors. */
+  TVM_FFI_INLINE bool IsScalar() const {
+    int16_t encoded_lanes = static_cast<int16_t>(get()->dtype.lanes);
+    return encoded_lanes == 1;
+  }
+
+  /*! \brief Whether this type is the void sentinel `handle(0, 0)`. */
+  TVM_FFI_INLINE bool IsVoid() const {
+    DLDataType dtype = get()->dtype;
+    return dtype.code == static_cast<uint8_t>(DLDataTypeCode::kDLOpaqueHandle) && dtype.bits == 0 &&
+           static_cast<int16_t>(dtype.lanes) == 0;
+  }
+
+  /*! \brief Whether this type is an opaque handle, excluding the void sentinel. */
+  TVM_FFI_INLINE bool IsHandle() const {
+    return this->code() == DLDataTypeCode::kDLOpaqueHandle && !this->IsVoid();
+  }
+
+  /*! \brief Whether this type is a scalable vector. */
+  TVM_FFI_INLINE bool IsScalableVector() const {
+    return static_cast<int16_t>(get()->dtype.lanes) < -1;
+  }
+
+  /*! \brief Whether this type is a fixed-length vector. */
+  TVM_FFI_INLINE bool IsFixedLengthVector() const {
+    return static_cast<int16_t>(get()->dtype.lanes) > 1;
+  }
+
+  /*!
+   * \brief Return the number of bytes needed to store one value of this type.
+   *
+   * This uses the same packed sub-byte dtype sizing rule as runtime tensors.
+   * Scalable vector types have no compile-time storage size and are rejected.
+   */
+  TVM_DLL size_t StorageBytes() const;
+
+  /*! \brief Return the same type with a different dtype code, preserving bits and lanes. */
+  TVM_FFI_INLINE PrimType WithCode(DLDataTypeCode code) const {
+    DLDataType dtype = get()->dtype;
+    int16_t encoded_lanes = static_cast<int16_t>(dtype.lanes);
+    if (encoded_lanes < -1) {
+      return ScalableVector(code, dtype.bits, -encoded_lanes);
+    }
+    return PrimType(code, dtype.bits, encoded_lanes);
+  }
+
+  /*! \brief Return the same type with a different scalar bit width, preserving code and lanes. */
+  TVM_FFI_INLINE PrimType WithBits(int bits) const {
+    DLDataType dtype = get()->dtype;
+    int16_t encoded_lanes = static_cast<int16_t>(dtype.lanes);
+    if (encoded_lanes < -1) {
+      return ScalableVector(this->code(), bits, -encoded_lanes);
+    }
+    return PrimType(this->code(), bits, encoded_lanes);
+  }
+
+  /*! \brief Return the same scalar element type with a fixed lane count. */
+  TVM_FFI_INLINE PrimType WithLanes(int lanes) const {
+    return PrimType(this->code(), this->bits(), lanes);
+  }
+
+  /*! \return The vscale factor encoded in a scalable vector type. */
+  TVM_FFI_INLINE int32_t VScaleFactor() const {
+    int16_t encoded_lanes = static_cast<int16_t>(get()->dtype.lanes);
+    if (encoded_lanes >= -1) {
+      TVM_FFI_THROW(InternalError) << "A fixed length vector doesn't have a vscale factor.";
+    }
+    return -encoded_lanes;
+  }
+
+  TVM_FFI_DEFINE_OBJECT_REF_METHODS_NOTNULLABLE(PrimType, Type, PrimTypeNode);
+};
+
+inline bool operator==(const PrimType& lhs, const PrimType& rhs) {
+  return lhs->dtype == rhs->dtype;
+}
+
+inline bool operator!=(const PrimType& lhs, const PrimType& rhs) { return !(lhs == rhs); }
+
+/*!
+ * \brief Base type of all the expressions.
+ * \sa Expr
+ */
+class BaseExprNode : public ffi::Object {
+ public:
+  /*!
+   * \brief Span that points to the original source code.
+   *        Reserved debug information.
+   */
+  mutable Span span;
+
+  /*!
+   * \brief The deduced or annotated type of the expression.
+   *
+   * This field is intentionally nullable because type information may
+   * be populated by later analysis passes instead of expression
+   * constructors.
+   */
+  mutable Type ty;
+
+  static void RegisterReflection() {
+    namespace refl = tvm::ffi::reflection;
+    // span and ty do not participate in structural equal and hash.
+    refl::ObjectDef<BaseExprNode>()
+        .def_ro("span", &BaseExprNode::span, refl::DefaultValue(Span()),
+                refl::AttachFieldFlag::SEqHashIgnore())
+        .def_ro("ty", &BaseExprNode::ty, refl::DefaultValue(Type()),
+                refl::AttachFieldFlag::SEqHashIgnore());
+  }
+
+  static constexpr TVMFFISEqHashKind _type_s_eq_hash_kind = kTVMFFISEqHashKindTreeNode;
+
+  static constexpr const uint32_t _type_child_slots = 64;
+  TVM_FFI_DECLARE_OBJECT_INFO("ir.BaseExpr", BaseExprNode, ffi::Object);
+};
+
+/*!
+ * \brief Managed reference to BaseExprNode.
+ * \sa BaseExprNode
+ */
+class BaseExpr : public ffi::ObjectRef {
+ public:
+  TVM_FFI_DEFINE_OBJECT_REF_METHODS_NULLABLE(BaseExpr, ffi::ObjectRef, BaseExprNode);
+};
+
+namespace ffi {
+template <>
+inline constexpr bool use_default_type_traits_v<PrimType> = false;
+
+template <>
+struct TypeTraits<PrimType> : public ObjectRefWithFallbackTraitsBase<PrimType, DLDataType> {
+  TVM_FFI_INLINE static PrimType ConvertFallbackValue(DLDataType dtype) { return PrimType(dtype); }
+};
+}  // namespace ffi
+
+}  // namespace tvm
+
+#endif  // TVM_IR_BASE_EXPR_H_