BuiltinAttributes.h

Go to the documentation of this file.

//===- BuiltinAttributes.h - MLIR Builtin Attribute Classes -----*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef MLIR_IR_BUILTINATTRIBUTES_H
#define MLIR_IR_BUILTINATTRIBUTES_H

#include "mlir/IR/BuiltinAttributeInterfaces.h"
#include "mlir/IR/SubElementInterfaces.h"
#include "llvm/ADT/APFloat.h"
#include "llvm/ADT/Sequence.h"
#include <complex>

namespace mlir {
class AffineMap;
class BoolAttr;
class DenseIntElementsAttr;
class FlatSymbolRefAttr;
class FunctionType;
class IntegerSet;
class IntegerType;
class Location;
class Operation;
class ShapedType;

//===----------------------------------------------------------------------===//
// Elements Attributes
//===----------------------------------------------------------------------===//

namespace detail {
/// Pair of raw pointer and a boolean flag of whether the pointer holds a splat,
using DenseIterPtrAndSplat = std::pair<const char *, bool>;

/// Impl iterator for indexed DenseElementsAttr iterators that records a data
/// pointer and data index that is adjusted for the case of a splat attribute.
template <typename ConcreteT, typename T, typename PointerT = T *,
          typename ReferenceT = T &>
class DenseElementIndexedIteratorImpl
    : public llvm::indexed_accessor_iterator<ConcreteT, DenseIterPtrAndSplat, T,
                                             PointerT, ReferenceT> {
protected:
  DenseElementIndexedIteratorImpl(const char *data, bool isSplat,
                                  size_t dataIndex)
      : llvm::indexed_accessor_iterator<ConcreteT, DenseIterPtrAndSplat, T,
                                        PointerT, ReferenceT>({data, isSplat},
                                                              dataIndex) {}

  /// Return the current index for this iterator, adjusted for the case of a
  /// splat.
  ptrdiff_t getDataIndex() const {
    bool isSplat = this->base.second;
    return isSplat ? 0 : this->index;
  }

  /// Return the data base pointer.
  const char *getData() const { return this->base.first; }
};

/// Type trait detector that checks if a given type T is a complex type.
template <typename T> struct is_complex_t : public std::false_type {};
template <typename T>
struct is_complex_t<std::complex<T>> : public std::true_type {};
} // namespace detail

/// An attribute that represents a reference to a dense vector or tensor object.
///
class DenseElementsAttr : public Attribute {
public:
  using Attribute::Attribute;

  /// Allow implicit conversion to ElementsAttr.
  operator ElementsAttr() const {
    return *this ? cast<ElementsAttr>() : nullptr;
  }

  /// Type trait used to check if the given type T is a potentially valid C++
  /// floating point type that can be used to access the underlying element
  /// types of a DenseElementsAttr.
  // TODO: Use std::disjunction when C++17 is supported.
  template <typename T> struct is_valid_cpp_fp_type {
    /// The type is a valid floating point type if it is a builtin floating
    /// point type, or is a potentially user defined floating point type. The
    /// latter allows for supporting users that have custom types defined for
    /// bfloat16/half/etc.
    static constexpr bool value = llvm::is_one_of<T, float, double>::value ||
                                  (std::numeric_limits<T>::is_specialized &&
                                   !std::numeric_limits<T>::is_integer);
  };

  /// Method for support type inquiry through isa, cast and dyn_cast.
  static bool classof(Attribute attr);

  /// Constructs a dense elements attribute from an array of element values.
  /// Each element attribute value is expected to be an element of 'type'.
  /// 'type' must be a vector or tensor with static shape. If the element of
  /// `type` is non-integer/index/float it is assumed to be a string type.
  static DenseElementsAttr get(ShapedType type, ArrayRef<Attribute> values);

  /// Constructs a dense integer elements attribute from an array of integer
  /// or floating-point values. Each value is expected to be the same bitwidth
  /// of the element type of 'type'. 'type' must be a vector or tensor with
  /// static shape.
  template <typename T, typename = typename std::enable_if<
                            std::numeric_limits<T>::is_integer ||
                            is_valid_cpp_fp_type<T>::value>::type>
  static DenseElementsAttr get(const ShapedType &type, ArrayRef<T> values) {
    const char *data = reinterpret_cast<const char *>(values.data());
    return getRawIntOrFloat(
        type, ArrayRef<char>(data, values.size() * sizeof(T)), sizeof(T),
        std::numeric_limits<T>::is_integer, std::numeric_limits<T>::is_signed);
  }

  /// Constructs a dense integer elements attribute from a single element.
  template <typename T, typename = typename std::enable_if<
                            std::numeric_limits<T>::is_integer ||
                            is_valid_cpp_fp_type<T>::value ||
                            detail::is_complex_t<T>::value>::type>
  static DenseElementsAttr get(const ShapedType &type, T value) {
    return get(type, llvm::makeArrayRef(value));
  }

  /// Constructs a dense complex elements attribute from an array of complex
  /// values. Each value is expected to be the same bitwidth of the element type
  /// of 'type'. 'type' must be a vector or tensor with static shape.
  template <typename T, typename ElementT = typename T::value_type,
            typename = typename std::enable_if<
                detail::is_complex_t<T>::value &&
                (std::numeric_limits<ElementT>::is_integer ||
                 is_valid_cpp_fp_type<ElementT>::value)>::type>
  static DenseElementsAttr get(const ShapedType &type, ArrayRef<T> values) {
    const char *data = reinterpret_cast<const char *>(values.data());
    return getRawComplex(type, ArrayRef<char>(data, values.size() * sizeof(T)),
                         sizeof(T), std::numeric_limits<ElementT>::is_integer,
                         std::numeric_limits<ElementT>::is_signed);
  }

  /// Overload of the above 'get' method that is specialized for boolean values.
  static DenseElementsAttr get(ShapedType type, ArrayRef<bool> values);

  /// Overload of the above 'get' method that is specialized for StringRef
  /// values.
  static DenseElementsAttr get(ShapedType type, ArrayRef<StringRef> values);

  /// Constructs a dense integer elements attribute from an array of APInt
  /// values. Each APInt value is expected to have the same bitwidth as the
  /// element type of 'type'. 'type' must be a vector or tensor with static
  /// shape.
  static DenseElementsAttr get(ShapedType type, ArrayRef<APInt> values);

  /// Constructs a dense complex elements attribute from an array of APInt
  /// values. Each APInt value is expected to have the same bitwidth as the
  /// element type of 'type'. 'type' must be a vector or tensor with static
  /// shape.
  static DenseElementsAttr get(ShapedType type,
                               ArrayRef<std::complex<APInt>> values);

  /// Constructs a dense float elements attribute from an array of APFloat
  /// values. Each APFloat value is expected to have the same bitwidth as the
  /// element type of 'type'. 'type' must be a vector or tensor with static
  /// shape.
  static DenseElementsAttr get(ShapedType type, ArrayRef<APFloat> values);

  /// Constructs a dense complex elements attribute from an array of APFloat
  /// values. Each APFloat value is expected to have the same bitwidth as the
  /// element type of 'type'. 'type' must be a vector or tensor with static
  /// shape.
  static DenseElementsAttr get(ShapedType type,
                               ArrayRef<std::complex<APFloat>> values);

  /// Construct a dense elements attribute for an initializer_list of values.
  /// Each value is expected to be the same bitwidth of the element type of
  /// 'type'. 'type' must be a vector or tensor with static shape.
  template <typename T>
  static DenseElementsAttr get(const ShapedType &type,
                               const std::initializer_list<T> &list) {
    return get(type, ArrayRef<T>(list));
  }

  /// Construct a dense elements attribute from a raw buffer representing the
  /// data for this attribute. Users are encouraged to use one of the
  /// constructors above, which provide more safeties. However, this
  /// constructor is useful for tools which may want to interop and can
  /// follow the precise definition.
  ///
  /// The format of the raw buffer is a densely packed array of values that
  /// can be bitcast to the storage format of the element type specified.
  /// Types that are not byte aligned will be:
  ///   - For bitwidth > 1: Rounded up to the next byte.
  ///   - For bitwidth = 1: Packed into 8bit bytes with bits corresponding to
  ///     the linear order of the shape type from MSB to LSB, padded to on the
  ///     right.
  ///
  /// If `isSplatBuffer` is true, then the raw buffer should contain a
  /// single element (or for the case of 1-bit, a single byte of 0 or 255),
  /// which will be used to construct a splat.
  static DenseElementsAttr getFromRawBuffer(ShapedType type,
                                            ArrayRef<char> rawBuffer,
                                            bool isSplatBuffer);

  /// Returns true if the given buffer is a valid raw buffer for the given type.
  /// `detectedSplat` is set if the buffer is valid and represents a splat
  /// buffer. The definition may be expanded over time, but currently, a
  /// splat buffer is detected if:
  ///   - For >1bit: The buffer consists of a single element.
  ///   - For 1bit: The buffer consists of a single byte with value 0 or 255.
  ///
  /// User code should be prepared for additional, conformant patterns to be
  /// identified as splats in the future.
  static bool isValidRawBuffer(ShapedType type, ArrayRef<char> rawBuffer,
                               bool &detectedSplat);

  //===--------------------------------------------------------------------===//
  // Iterators
  //===--------------------------------------------------------------------===//

  /// The iterator range over the given iterator type T.
  template <typename IteratorT>
  using iterator_range_impl = detail::ElementsAttrRange<IteratorT>;

  /// The iterator for the given element type T.
  template <typename T, typename AttrT = DenseElementsAttr>
  using iterator = decltype(std::declval<AttrT>().template value_begin<T>());
  /// The iterator range over the given element T.
  template <typename T, typename AttrT = DenseElementsAttr>
  using iterator_range =
      decltype(std::declval<AttrT>().template getValues<T>());

  /// A utility iterator that allows walking over the internal Attribute values
  /// of a DenseElementsAttr.
  class AttributeElementIterator
      : public llvm::indexed_accessor_iterator<AttributeElementIterator,
                                               const void *, Attribute,
                                               Attribute, Attribute> {
  public:
    /// Accesses the Attribute value at this iterator position.
    Attribute operator*() const;

  private:
    friend DenseElementsAttr;

    /// Constructs a new iterator.
    AttributeElementIterator(DenseElementsAttr attr, size_t index);
  };

  /// Iterator for walking raw element values of the specified type 'T', which
  /// may be any c++ data type matching the stored representation: int32_t,
  /// float, etc.
  template <typename T>
  class ElementIterator
      : public detail::DenseElementIndexedIteratorImpl<ElementIterator<T>,
                                                       const T> {
  public:
    /// Accesses the raw value at this iterator position.
    const T &operator*() const {
      return reinterpret_cast<const T *>(this->getData())[this->getDataIndex()];
    }

  private:
    friend DenseElementsAttr;

    /// Constructs a new iterator.
    ElementIterator(const char *data, bool isSplat, size_t dataIndex)
        : detail::DenseElementIndexedIteratorImpl<ElementIterator<T>, const T>(
              data, isSplat, dataIndex) {}
  };

  /// A utility iterator that allows walking over the internal bool values.
  class BoolElementIterator
      : public detail::DenseElementIndexedIteratorImpl<BoolElementIterator,
                                                       bool, bool, bool> {
  public:
    /// Accesses the bool value at this iterator position.
    bool operator*() const;

  private:
    friend DenseElementsAttr;

    /// Constructs a new iterator.
    BoolElementIterator(DenseElementsAttr attr, size_t dataIndex);
  };

  /// A utility iterator that allows walking over the internal raw APInt values.
  class IntElementIterator
      : public detail::DenseElementIndexedIteratorImpl<IntElementIterator,
                                                       APInt, APInt, APInt> {
  public:
    /// Accesses the raw APInt value at this iterator position.
    APInt operator*() const;

  private:
    friend DenseElementsAttr;

    /// Constructs a new iterator.
    IntElementIterator(DenseElementsAttr attr, size_t dataIndex);

    /// The bitwidth of the element type.
    size_t bitWidth;
  };

  /// A utility iterator that allows walking over the internal raw complex APInt
  /// values.
  class ComplexIntElementIterator
      : public detail::DenseElementIndexedIteratorImpl<
            ComplexIntElementIterator, std::complex<APInt>, std::complex<APInt>,
            std::complex<APInt>> {
  public:
    /// Accesses the raw std::complex<APInt> value at this iterator position.
    std::complex<APInt> operator*() const;

  private:
    friend DenseElementsAttr;

    /// Constructs a new iterator.
    ComplexIntElementIterator(DenseElementsAttr attr, size_t dataIndex);

    /// The bitwidth of the element type.
    size_t bitWidth;
  };

  /// Iterator for walking over APFloat values.
  class FloatElementIterator final
      : public llvm::mapped_iterator_base<FloatElementIterator,
                                          IntElementIterator, APFloat> {
  public:
    /// Map the element to the iterator result type.
    APFloat mapElement(const APInt &value) const {
      return APFloat(*smt, value);
    }

  private:
    friend DenseElementsAttr;

    /// Initializes the float element iterator to the specified iterator.
    FloatElementIterator(const llvm::fltSemantics &smt, IntElementIterator it)
        : BaseT(it), smt(&smt) {}

    /// The float semantics to use when constructing the APFloat.
    const llvm::fltSemantics *smt;
  };

  /// Iterator for walking over complex APFloat values.
  class ComplexFloatElementIterator final
      : public llvm::mapped_iterator_base<ComplexFloatElementIterator,
                                          ComplexIntElementIterator,
                                          std::complex<APFloat>> {
  public:
    /// Map the element to the iterator result type.
    std::complex<APFloat> mapElement(const std::complex<APInt> &value) const {
      return {APFloat(*smt, value.real()), APFloat(*smt, value.imag())};
    }

  private:
    friend DenseElementsAttr;

    /// Initializes the float element iterator to the specified iterator.
    ComplexFloatElementIterator(const llvm::fltSemantics &smt,
                                ComplexIntElementIterator it)
        : BaseT(it), smt(&smt) {}

    /// The float semantics to use when constructing the APFloat.
    const llvm::fltSemantics *smt;
  };

  //===--------------------------------------------------------------------===//
  // Value Querying
  //===--------------------------------------------------------------------===//

  /// Returns true if this attribute corresponds to a splat, i.e. if all element
  /// values are the same.
  bool isSplat() const;

  /// Return the splat value for this attribute. This asserts that the attribute
  /// corresponds to a splat.
  template <typename T>
  typename std::enable_if<!std::is_base_of<Attribute, T>::value ||
                              std::is_same<Attribute, T>::value,
                          T>::type
  getSplatValue() const {
    assert(isSplat() && "expected the attribute to be a splat");
    return *value_begin<T>();
  }
  /// Return the splat value for derived attribute element types.
  template <typename T>
  typename std::enable_if<std::is_base_of<Attribute, T>::value &&
                              !std::is_same<Attribute, T>::value,
                          T>::type
  getSplatValue() const {
    return getSplatValue<Attribute>().template cast<T>();
  }

  /// Return the held element values as a range of integer or floating-point
  /// values.
  template <typename T>
  using IntFloatValueTemplateCheckT =
      typename std::enable_if<(!std::is_same<T, bool>::value &&
                               std::numeric_limits<T>::is_integer) ||
                              is_valid_cpp_fp_type<T>::value>::type;
  template <typename T, typename = IntFloatValueTemplateCheckT<T>>
  iterator_range_impl<ElementIterator<T>> getValues() const {
    assert(isValidIntOrFloat(sizeof(T), std::numeric_limits<T>::is_integer,
                             std::numeric_limits<T>::is_signed));
    const char *rawData = getRawData().data();
    bool splat = isSplat();
    return {Attribute::getType(), ElementIterator<T>(rawData, splat, 0),
            ElementIterator<T>(rawData, splat, getNumElements())};
  }
  template <typename T, typename = IntFloatValueTemplateCheckT<T>>
  ElementIterator<T> value_begin() const {
    assert(isValidIntOrFloat(sizeof(T), std::numeric_limits<T>::is_integer,
                             std::numeric_limits<T>::is_signed));
    return ElementIterator<T>(getRawData().data(), isSplat(), 0);
  }
  template <typename T, typename = IntFloatValueTemplateCheckT<T>>
  ElementIterator<T> value_end() const {
    assert(isValidIntOrFloat(sizeof(T), std::numeric_limits<T>::is_integer,
                             std::numeric_limits<T>::is_signed));
    return ElementIterator<T>(getRawData().data(), isSplat(), getNumElements());
  }

  /// Return the held element values as a range of std::complex.
  template <typename T, typename ElementT>
  using ComplexValueTemplateCheckT =
      typename std::enable_if<detail::is_complex_t<T>::value &&
                              (std::numeric_limits<ElementT>::is_integer ||
                               is_valid_cpp_fp_type<ElementT>::value)>::type;
  template <typename T, typename ElementT = typename T::value_type,
            typename = ComplexValueTemplateCheckT<T, ElementT>>
  iterator_range_impl<ElementIterator<T>> getValues() const {
    assert(isValidComplex(sizeof(T), std::numeric_limits<ElementT>::is_integer,
                          std::numeric_limits<ElementT>::is_signed));
    const char *rawData = getRawData().data();
    bool splat = isSplat();
    return {Attribute::getType(), ElementIterator<T>(rawData, splat, 0),
            ElementIterator<T>(rawData, splat, getNumElements())};
  }
  template <typename T, typename ElementT = typename T::value_type,
            typename = ComplexValueTemplateCheckT<T, ElementT>>
  ElementIterator<T> value_begin() const {
    assert(isValidComplex(sizeof(T), std::numeric_limits<ElementT>::is_integer,
                          std::numeric_limits<ElementT>::is_signed));
    return ElementIterator<T>(getRawData().data(), isSplat(), 0);
  }
  template <typename T, typename ElementT = typename T::value_type,
            typename = ComplexValueTemplateCheckT<T, ElementT>>
  ElementIterator<T> value_end() const {
    assert(isValidComplex(sizeof(T), std::numeric_limits<ElementT>::is_integer,
                          std::numeric_limits<ElementT>::is_signed));
    return ElementIterator<T>(getRawData().data(), isSplat(), getNumElements());
  }

  /// Return the held element values as a range of StringRef.
  template <typename T>
  using StringRefValueTemplateCheckT =
      typename std::enable_if<std::is_same<T, StringRef>::value>::type;
  template <typename T, typename = StringRefValueTemplateCheckT<T>>
  iterator_range_impl<ElementIterator<StringRef>> getValues() const {
    auto stringRefs = getRawStringData();
    const char *ptr = reinterpret_cast<const char *>(stringRefs.data());
    bool splat = isSplat();
    return {Attribute::getType(), ElementIterator<StringRef>(ptr, splat, 0),
            ElementIterator<StringRef>(ptr, splat, getNumElements())};
  }
  template <typename T, typename = StringRefValueTemplateCheckT<T>>
  ElementIterator<StringRef> value_begin() const {
    const char *ptr = reinterpret_cast<const char *>(getRawStringData().data());
    return ElementIterator<StringRef>(ptr, isSplat(), 0);
  }
  template <typename T, typename = StringRefValueTemplateCheckT<T>>
  ElementIterator<StringRef> value_end() const {
    const char *ptr = reinterpret_cast<const char *>(getRawStringData().data());
    return ElementIterator<StringRef>(ptr, isSplat(), getNumElements());
  }

  /// Return the held element values as a range of Attributes.
  template <typename T>
  using AttributeValueTemplateCheckT =
      typename std::enable_if<std::is_same<T, Attribute>::value>::type;
  template <typename T, typename = AttributeValueTemplateCheckT<T>>
  iterator_range_impl<AttributeElementIterator> getValues() const {
    return {Attribute::getType(), value_begin<Attribute>(),
            value_end<Attribute>()};
  }
  template <typename T, typename = AttributeValueTemplateCheckT<T>>
  AttributeElementIterator value_begin() const {
    return AttributeElementIterator(*this, 0);
  }
  template <typename T, typename = AttributeValueTemplateCheckT<T>>
  AttributeElementIterator value_end() const {
    return AttributeElementIterator(*this, getNumElements());
  }

  /// Return the held element values a range of T, where T is a derived
  /// attribute type.
  template <typename T>
  using DerivedAttrValueTemplateCheckT =
      typename std::enable_if<std::is_base_of<Attribute, T>::value &&
                              !std::is_same<Attribute, T>::value>::type;
  template <typename T>
  struct DerivedAttributeElementIterator
      : public llvm::mapped_iterator_base<DerivedAttributeElementIterator<T>,
                                          AttributeElementIterator, T> {
    using llvm::mapped_iterator_base<DerivedAttributeElementIterator<T>,
                                     AttributeElementIterator,
                                     T>::mapped_iterator_base;

    /// Map the element to the iterator result type.
    T mapElement(Attribute attr) const { return attr.cast<T>(); }
  };
  template <typename T, typename = DerivedAttrValueTemplateCheckT<T>>
  iterator_range_impl<DerivedAttributeElementIterator<T>> getValues() const {
    using DerivedIterT = DerivedAttributeElementIterator<T>;
    return {Attribute::getType(), DerivedIterT(value_begin<Attribute>()),
            DerivedIterT(value_end<Attribute>())};
  }
  template <typename T, typename = DerivedAttrValueTemplateCheckT<T>>
  DerivedAttributeElementIterator<T> value_begin() const {
    return {value_begin<Attribute>()};
  }
  template <typename T, typename = DerivedAttrValueTemplateCheckT<T>>
  DerivedAttributeElementIterator<T> value_end() const {
    return {value_end<Attribute>()};
  }

  /// Return the held element values as a range of bool. The element type of
  /// this attribute must be of integer type of bitwidth 1.
  template <typename T>
  using BoolValueTemplateCheckT =
      typename std::enable_if<std::is_same<T, bool>::value>::type;
  template <typename T, typename = BoolValueTemplateCheckT<T>>
  iterator_range_impl<BoolElementIterator> getValues() const {
    assert(isValidBool() && "bool is not the value of this elements attribute");
    return {Attribute::getType(), BoolElementIterator(*this, 0),
            BoolElementIterator(*this, getNumElements())};
  }
  template <typename T, typename = BoolValueTemplateCheckT<T>>
  BoolElementIterator value_begin() const {
    assert(isValidBool() && "bool is not the value of this elements attribute");
    return BoolElementIterator(*this, 0);
  }
  template <typename T, typename = BoolValueTemplateCheckT<T>>
  BoolElementIterator value_end() const {
    assert(isValidBool() && "bool is not the value of this elements attribute");
    return BoolElementIterator(*this, getNumElements());
  }

  /// Return the held element values as a range of APInts. The element type of
  /// this attribute must be of integer type.
  template <typename T>
  using APIntValueTemplateCheckT =
      typename std::enable_if<std::is_same<T, APInt>::value>::type;
  template <typename T, typename = APIntValueTemplateCheckT<T>>
  iterator_range_impl<IntElementIterator> getValues() const {
    assert(getElementType().isIntOrIndex() && "expected integral type");
    return {Attribute::getType(), raw_int_begin(), raw_int_end()};
  }
  template <typename T, typename = APIntValueTemplateCheckT<T>>
  IntElementIterator value_begin() const {
    assert(getElementType().isIntOrIndex() && "expected integral type");
    return raw_int_begin();
  }
  template <typename T, typename = APIntValueTemplateCheckT<T>>
  IntElementIterator value_end() const {
    assert(getElementType().isIntOrIndex() && "expected integral type");
    return raw_int_end();
  }

  /// Return the held element values as a range of complex APInts. The element
  /// type of this attribute must be a complex of integer type.
  template <typename T>
  using ComplexAPIntValueTemplateCheckT = typename std::enable_if<
      std::is_same<T, std::complex<APInt>>::value>::type;
  template <typename T, typename = ComplexAPIntValueTemplateCheckT<T>>
  iterator_range_impl<ComplexIntElementIterator> getValues() const {
    return getComplexIntValues();
  }
  template <typename T, typename = ComplexAPIntValueTemplateCheckT<T>>
  ComplexIntElementIterator value_begin() const {
    return complex_value_begin();
  }
  template <typename T, typename = ComplexAPIntValueTemplateCheckT<T>>
  ComplexIntElementIterator value_end() const {
    return complex_value_end();
  }

  /// Return the held element values as a range of APFloat. The element type of
  /// this attribute must be of float type.
  template <typename T>
  using APFloatValueTemplateCheckT =
      typename std::enable_if<std::is_same<T, APFloat>::value>::type;
  template <typename T, typename = APFloatValueTemplateCheckT<T>>
  iterator_range_impl<FloatElementIterator> getValues() const {
    return getFloatValues();
  }
  template <typename T, typename = APFloatValueTemplateCheckT<T>>
  FloatElementIterator value_begin() const {
    return float_value_begin();
  }
  template <typename T, typename = APFloatValueTemplateCheckT<T>>
  FloatElementIterator value_end() const {
    return float_value_end();
  }

  /// Return the held element values as a range of complex APFloat. The element
  /// type of this attribute must be a complex of float type.
  template <typename T>
  using ComplexAPFloatValueTemplateCheckT = typename std::enable_if<
      std::is_same<T, std::complex<APFloat>>::value>::type;
  template <typename T, typename = ComplexAPFloatValueTemplateCheckT<T>>
  iterator_range_impl<ComplexFloatElementIterator> getValues() const {
    return getComplexFloatValues();
  }
  template <typename T, typename = ComplexAPFloatValueTemplateCheckT<T>>
  ComplexFloatElementIterator value_begin() const {
    return complex_float_value_begin();
  }
  template <typename T, typename = ComplexAPFloatValueTemplateCheckT<T>>
  ComplexFloatElementIterator value_end() const {
    return complex_float_value_end();
  }

  /// Return the raw storage data held by this attribute. Users should generally
  /// not use this directly, as the internal storage format is not always in the
  /// form the user might expect.
  ArrayRef<char> getRawData() const;

  /// Return the raw StringRef data held by this attribute.
  ArrayRef<StringRef> getRawStringData() const;

  /// Return the type of this ElementsAttr, guaranteed to be a vector or tensor
  /// with static shape.
  ShapedType getType() const;

  /// Return the element type of this DenseElementsAttr.
  Type getElementType() const;

  /// Returns the number of elements held by this attribute.
  int64_t getNumElements() const;

  /// Returns the number of elements held by this attribute.
  int64_t size() const { return getNumElements(); }

  /// Returns if the number of elements held by this attribute is 0.
  bool empty() const { return size() == 0; }

  //===--------------------------------------------------------------------===//
  // Mutation Utilities
  //===--------------------------------------------------------------------===//

  /// Return a new DenseElementsAttr that has the same data as the current
  /// attribute, but has been reshaped to 'newType'. The new type must have the
  /// same total number of elements as well as element type.
  DenseElementsAttr reshape(ShapedType newType);

  /// Return a new DenseElementsAttr that has the same data as the current
  /// attribute, but has bitcast elements to 'newElType'. The new type must have
  /// the same bitwidth as the current element type.
  DenseElementsAttr bitcast(Type newElType);

  /// Generates a new DenseElementsAttr by mapping each int value to a new
  /// underlying APInt. The new values can represent either an integer or float.
  /// This underlying type must be an DenseIntElementsAttr.
  DenseElementsAttr mapValues(Type newElementType,
                              function_ref<APInt(const APInt &)> mapping) const;

  /// Generates a new DenseElementsAttr by mapping each float value to a new
  /// underlying APInt. the new values can represent either an integer or float.
  /// This underlying type must be an DenseFPElementsAttr.
  DenseElementsAttr
  mapValues(Type newElementType,
            function_ref<APInt(const APFloat &)> mapping) const;

protected:
  /// Iterators to various elements that require out-of-line definition. These
  /// are hidden from the user to encourage consistent use of the
  /// getValues/value_begin/value_end API.
  IntElementIterator raw_int_begin() const {
    return IntElementIterator(*this, 0);
  }
  IntElementIterator raw_int_end() const {
    return IntElementIterator(*this, getNumElements());
  }
  iterator_range_impl<ComplexIntElementIterator> getComplexIntValues() const;
  ComplexIntElementIterator complex_value_begin() const;
  ComplexIntElementIterator complex_value_end() const;
  iterator_range_impl<FloatElementIterator> getFloatValues() const;
  FloatElementIterator float_value_begin() const;
  FloatElementIterator float_value_end() const;
  iterator_range_impl<ComplexFloatElementIterator>
  getComplexFloatValues() const;
  ComplexFloatElementIterator complex_float_value_begin() const;
  ComplexFloatElementIterator complex_float_value_end() const;

  /// Overload of the raw 'get' method that asserts that the given type is of
  /// complex type. This method is used to verify type invariants that the
  /// templatized 'get' method cannot.
  static DenseElementsAttr getRawComplex(ShapedType type, ArrayRef<char> data,
                                         int64_t dataEltSize, bool isInt,
                                         bool isSigned);

  /// Overload of the raw 'get' method that asserts that the given type is of
  /// integer or floating-point type. This method is used to verify type
  /// invariants that the templatized 'get' method cannot.
  static DenseElementsAttr getRawIntOrFloat(ShapedType type,
                                            ArrayRef<char> data,
                                            int64_t dataEltSize, bool isInt,
                                            bool isSigned);

  /// Check the information for a C++ data type, check if this type is valid for
  /// the current attribute. This method is used to verify specific type
  /// invariants that the templatized 'getValues' method cannot.
  bool isValidBool() const { return getElementType().isInteger(1); }
  bool isValidIntOrFloat(int64_t dataEltSize, bool isInt, bool isSigned) const;
  bool isValidComplex(int64_t dataEltSize, bool isInt, bool isSigned) const;
};

/// An attribute that represents a reference to a splat vector or tensor
/// constant, meaning all of the elements have the same value.
class SplatElementsAttr : public DenseElementsAttr {
public:
  using DenseElementsAttr::DenseElementsAttr;

  /// Method for support type inquiry through isa, cast and dyn_cast.
  static bool classof(Attribute attr) {
    auto denseAttr = attr.dyn_cast<DenseElementsAttr>();
    return denseAttr && denseAttr.isSplat();
  }
};
} // namespace mlir

//===----------------------------------------------------------------------===//
// Tablegen Attribute Declarations
//===----------------------------------------------------------------------===//

#define GET_ATTRDEF_CLASSES
#include "mlir/IR/BuiltinAttributes.h.inc"

//===----------------------------------------------------------------------===//
// C++ Attribute Declarations
//===----------------------------------------------------------------------===//

namespace mlir {
//===----------------------------------------------------------------------===//
// BoolAttr
//===----------------------------------------------------------------------===//

/// Special case of IntegerAttr to represent boolean integers, i.e., signless i1
/// integers.
class BoolAttr : public Attribute {
public:
  using Attribute::Attribute;
  using ValueType = bool;

  static BoolAttr get(MLIRContext *context, bool value);

  /// Enable conversion to IntegerAttr. This uses conversion vs. inheritance to
  /// avoid bringing in all of IntegerAttrs methods.
  operator IntegerAttr() const { return IntegerAttr(impl); }

  /// Return the boolean value of this attribute.
  bool getValue() const;

  /// Methods for support type inquiry through isa, cast, and dyn_cast.
  static bool classof(Attribute attr);
};

//===----------------------------------------------------------------------===//
// FlatSymbolRefAttr
//===----------------------------------------------------------------------===//

/// A symbol reference with a reference path containing a single element. This
/// is used to refer to an operation within the current symbol table.
class FlatSymbolRefAttr : public SymbolRefAttr {
public:
  using SymbolRefAttr::SymbolRefAttr;
  using ValueType = StringRef;

  /// Construct a symbol reference for the given value name.
  static FlatSymbolRefAttr get(StringAttr value) {
    return SymbolRefAttr::get(value);
  }
  static FlatSymbolRefAttr get(MLIRContext *ctx, StringRef value) {
    return SymbolRefAttr::get(ctx, value);
  }

  /// Convenience getter for building a SymbolRefAttr based on an operation
  /// that implements the SymbolTrait.
  static FlatSymbolRefAttr get(Operation *symbol) {
    return SymbolRefAttr::get(symbol);
  }

  /// Returns the name of the held symbol reference as a StringAttr.
  StringAttr getAttr() const { return getRootReference(); }

  /// Returns the name of the held symbol reference.
  StringRef getValue() const { return getAttr().getValue(); }

  /// Methods for support type inquiry through isa, cast, and dyn_cast.
  static bool classof(Attribute attr) {
    SymbolRefAttr refAttr = attr.dyn_cast<SymbolRefAttr>();
    return refAttr && refAttr.getNestedReferences().empty();
  }

private:
  using SymbolRefAttr::get;
  using SymbolRefAttr::getNestedReferences;
};

//===----------------------------------------------------------------------===//
// DenseFPElementsAttr
//===----------------------------------------------------------------------===//

/// An attribute that represents a reference to a dense float vector or tensor
/// object. Each element is stored as a double.
class DenseFPElementsAttr : public DenseIntOrFPElementsAttr {
public:
  using iterator = DenseElementsAttr::FloatElementIterator;

  using DenseIntOrFPElementsAttr::DenseIntOrFPElementsAttr;

  /// Get an instance of a DenseFPElementsAttr with the given arguments. This
  /// simply wraps the DenseElementsAttr::get calls.
  template <typename Arg>
  static DenseFPElementsAttr get(const ShapedType &type, Arg &&arg) {
    return DenseElementsAttr::get(type, llvm::makeArrayRef(arg))
        .template cast<DenseFPElementsAttr>();
  }
  template <typename T>
  static DenseFPElementsAttr get(const ShapedType &type,
                                 const std::initializer_list<T> &list) {
    return DenseElementsAttr::get(type, list)
        .template cast<DenseFPElementsAttr>();
  }

  /// Generates a new DenseElementsAttr by mapping each value attribute, and
  /// constructing the DenseElementsAttr given the new element type.
  DenseElementsAttr
  mapValues(Type newElementType,
            function_ref<APInt(const APFloat &)> mapping) const;

  /// Iterator access to the float element values.
  iterator begin() const { return float_value_begin(); }
  iterator end() const { return float_value_end(); }

  /// Method for supporting type inquiry through isa, cast and dyn_cast.
  static bool classof(Attribute attr);
};

//===----------------------------------------------------------------------===//
// DenseIntElementsAttr
//===----------------------------------------------------------------------===//

/// An attribute that represents a reference to a dense integer vector or tensor
/// object.
class DenseIntElementsAttr : public DenseIntOrFPElementsAttr {
public:
  /// DenseIntElementsAttr iterates on APInt, so we can use the raw element
  /// iterator directly.
  using iterator = DenseElementsAttr::IntElementIterator;

  using DenseIntOrFPElementsAttr::DenseIntOrFPElementsAttr;

  /// Get an instance of a DenseIntElementsAttr with the given arguments. This
  /// simply wraps the DenseElementsAttr::get calls.
  template <typename Arg>
  static DenseIntElementsAttr get(const ShapedType &type, Arg &&arg) {
    return DenseElementsAttr::get(type, llvm::makeArrayRef(arg))
        .template cast<DenseIntElementsAttr>();
  }
  template <typename T>
  static DenseIntElementsAttr get(const ShapedType &type,
                                  const std::initializer_list<T> &list) {
    return DenseElementsAttr::get(type, list)
        .template cast<DenseIntElementsAttr>();
  }

  /// Generates a new DenseElementsAttr by mapping each value attribute, and
  /// constructing the DenseElementsAttr given the new element type.
  DenseElementsAttr mapValues(Type newElementType,
                              function_ref<APInt(const APInt &)> mapping) const;

  /// Iterator access to the integer element values.
  iterator begin() const { return raw_int_begin(); }
  iterator end() const { return raw_int_end(); }

  /// Method for supporting type inquiry through isa, cast and dyn_cast.
  static bool classof(Attribute attr);
};

//===----------------------------------------------------------------------===//
// SparseElementsAttr
//===----------------------------------------------------------------------===//

template <typename T>
auto SparseElementsAttr::value_begin() const -> iterator<T> {
  auto zeroValue = getZeroValue<T>();
  auto valueIt = getValues().value_begin<T>();
  const std::vector<ptrdiff_t> flatSparseIndices(getFlattenedSparseIndices());
  std::function<T(ptrdiff_t)> mapFn =
      [flatSparseIndices{flatSparseIndices}, valueIt{std::move(valueIt)},
       zeroValue{std::move(zeroValue)}](ptrdiff_t index) {
        // Try to map the current index to one of the sparse indices.
        for (unsigned i = 0, e = flatSparseIndices.size(); i != e; ++i)
          if (flatSparseIndices[i] == index)
            return *std::next(valueIt, i);
        // Otherwise, return the zero value.
        return zeroValue;
      };
  return iterator<T>(llvm::seq<ptrdiff_t>(0, getNumElements()).begin(), mapFn);
}

//===----------------------------------------------------------------------===//
// StringAttr
//===----------------------------------------------------------------------===//

/// Define comparisons for StringAttr against nullptr and itself to avoid the
/// StringRef overloads from being chosen when not desirable.
inline bool operator==(StringAttr lhs, std::nullptr_t) { return !lhs; }
inline bool operator!=(StringAttr lhs, std::nullptr_t) {
  return static_cast<bool>(lhs);
}
inline bool operator==(StringAttr lhs, StringAttr rhs) {
  return (Attribute)lhs == (Attribute)rhs;
}
inline bool operator!=(StringAttr lhs, StringAttr rhs) { return !(lhs == rhs); }

/// Allow direct comparison with StringRef.
inline bool operator==(StringAttr lhs, StringRef rhs) {
  return lhs.getValue() == rhs;
}
inline bool operator!=(StringAttr lhs, StringRef rhs) { return !(lhs == rhs); }
inline bool operator==(StringRef lhs, StringAttr rhs) {
  return rhs.getValue() == lhs;
}
inline bool operator!=(StringRef lhs, StringAttr rhs) { return !(lhs == rhs); }

inline Type StringAttr::getType() const { return Attribute::getType(); }

} // namespace mlir

//===----------------------------------------------------------------------===//
// Attribute Utilities
//===----------------------------------------------------------------------===//

namespace llvm {

template <>
struct DenseMapInfo<mlir::StringAttr> : public DenseMapInfo<mlir::Attribute> {
  static mlir::StringAttr getEmptyKey() {
    const void *pointer = llvm::DenseMapInfo<const void *>::getEmptyKey();
    return mlir::StringAttr::getFromOpaquePointer(pointer);
  }
  static mlir::StringAttr getTombstoneKey() {
    const void *pointer = llvm::DenseMapInfo<const void *>::getTombstoneKey();
    return mlir::StringAttr::getFromOpaquePointer(pointer);
  }
};
template <>
struct PointerLikeTypeTraits<mlir::StringAttr>
    : public PointerLikeTypeTraits<mlir::Attribute> {
  static inline mlir::StringAttr getFromVoidPointer(void *p) {
    return mlir::StringAttr::getFromOpaquePointer(p);
  }
};

template <>
struct PointerLikeTypeTraits<mlir::SymbolRefAttr>
    : public PointerLikeTypeTraits<mlir::Attribute> {
  static inline mlir::SymbolRefAttr getFromVoidPointer(void *ptr) {
    return mlir::SymbolRefAttr::getFromOpaquePointer(ptr);
  }
};

} // namespace llvm

#endif // MLIR_IR_BUILTINATTRIBUTES_H