xref: /llvm-project/mlir/lib/Bindings/Python/IRAttributes.cpp (revision f05ff4f7570ca009f22f5e2fe8c6361f28faaa8a)

//===- IRAttributes.cpp - Exports builtin and standard attributes ---------===//
//
// 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
//
//===----------------------------------------------------------------------===//

#include "IRModule.h"

#include "PybindUtils.h"

#include "mlir-c/BuiltinAttributes.h"
#include "mlir-c/BuiltinTypes.h"

namespace py = pybind11;
using namespace mlir;
using namespace mlir::python;

using llvm::SmallVector;
using llvm::StringRef;
using llvm::Twine;

namespace {

static MlirStringRef toMlirStringRef(const std::string &s) {
  return mlirStringRefCreate(s.data(), s.size());
}

class PyAffineMapAttribute : public PyConcreteAttribute<PyAffineMapAttribute> {
public:
  static constexpr IsAFunctionTy isaFunction = mlirAttributeIsAAffineMap;
  static constexpr const char *pyClassName = "AffineMapAttr";
  using PyConcreteAttribute::PyConcreteAttribute;

  static void bindDerived(ClassTy &c) {
    c.def_static(
        "get",
        [](PyAffineMap &affineMap) {
          MlirAttribute attr = mlirAffineMapAttrGet(affineMap.get());
          return PyAffineMapAttribute(affineMap.getContext(), attr);
        },
        py::arg("affine_map"), "Gets an attribute wrapping an AffineMap.");
  }
};

class PyArrayAttribute : public PyConcreteAttribute<PyArrayAttribute> {
public:
  static constexpr IsAFunctionTy isaFunction = mlirAttributeIsAArray;
  static constexpr const char *pyClassName = "ArrayAttr";
  using PyConcreteAttribute::PyConcreteAttribute;

  class PyArrayAttributeIterator {
  public:
    PyArrayAttributeIterator(PyAttribute attr) : attr(attr) {}

    PyArrayAttributeIterator &dunderIter() { return *this; }

    PyAttribute dunderNext() {
      if (nextIndex >= mlirArrayAttrGetNumElements(attr.get())) {
        throw py::stop_iteration();
      }
      return PyAttribute(attr.getContext(),
                         mlirArrayAttrGetElement(attr.get(), nextIndex++));
    }

    static void bind(py::module &m) {
      py::class_<PyArrayAttributeIterator>(m, "ArrayAttributeIterator",
                                           py::module_local())
          .def("__iter__", &PyArrayAttributeIterator::dunderIter)
          .def("__next__", &PyArrayAttributeIterator::dunderNext);
    }

  private:
    PyAttribute attr;
    int nextIndex = 0;
  };

  static void bindDerived(ClassTy &c) {
    c.def_static(
        "get",
        [](py::list attributes, DefaultingPyMlirContext context) {
          SmallVector<MlirAttribute> mlirAttributes;
          mlirAttributes.reserve(py::len(attributes));
          for (auto attribute : attributes) {
            try {
              mlirAttributes.push_back(attribute.cast<PyAttribute>());
            } catch (py::cast_error &err) {
              std::string msg = std::string("Invalid attribute when attempting "
                                            "to create an ArrayAttribute (") +
                                err.what() + ")";
              throw py::cast_error(msg);
            } catch (py::reference_cast_error &err) {
              // This exception seems thrown when the value is "None".
              std::string msg =
                  std::string("Invalid attribute (None?) when attempting to "
                              "create an ArrayAttribute (") +
                  err.what() + ")";
              throw py::cast_error(msg);
            }
          }
          MlirAttribute attr = mlirArrayAttrGet(
              context->get(), mlirAttributes.size(), mlirAttributes.data());
          return PyArrayAttribute(context->getRef(), attr);
        },
        py::arg("attributes"), py::arg("context") = py::none(),
        "Gets a uniqued Array attribute");
    c.def("__getitem__",
          [](PyArrayAttribute &arr, intptr_t i) {
            if (i >= mlirArrayAttrGetNumElements(arr))
              throw py::index_error("ArrayAttribute index out of range");
            return PyAttribute(arr.getContext(),
                               mlirArrayAttrGetElement(arr, i));
          })
        .def("__len__",
             [](const PyArrayAttribute &arr) {
               return mlirArrayAttrGetNumElements(arr);
             })
        .def("__iter__", [](const PyArrayAttribute &arr) {
          return PyArrayAttributeIterator(arr);
        });
  }
};

/// Float Point Attribute subclass - FloatAttr.
class PyFloatAttribute : public PyConcreteAttribute<PyFloatAttribute> {
public:
  static constexpr IsAFunctionTy isaFunction = mlirAttributeIsAFloat;
  static constexpr const char *pyClassName = "FloatAttr";
  using PyConcreteAttribute::PyConcreteAttribute;

  static void bindDerived(ClassTy &c) {
    c.def_static(
        "get",
        [](PyType &type, double value, DefaultingPyLocation loc) {
          MlirAttribute attr = mlirFloatAttrDoubleGetChecked(loc, type, value);
          // TODO: Rework error reporting once diagnostic engine is exposed
          // in C API.
          if (mlirAttributeIsNull(attr)) {
            throw SetPyError(PyExc_ValueError,
                             Twine("invalid '") +
                                 py::repr(py::cast(type)).cast<std::string>() +
                                 "' and expected floating point type.");
          }
          return PyFloatAttribute(type.getContext(), attr);
        },
        py::arg("type"), py::arg("value"), py::arg("loc") = py::none(),
        "Gets an uniqued float point attribute associated to a type");
    c.def_static(
        "get_f32",
        [](double value, DefaultingPyMlirContext context) {
          MlirAttribute attr = mlirFloatAttrDoubleGet(
              context->get(), mlirF32TypeGet(context->get()), value);
          return PyFloatAttribute(context->getRef(), attr);
        },
        py::arg("value"), py::arg("context") = py::none(),
        "Gets an uniqued float point attribute associated to a f32 type");
    c.def_static(
        "get_f64",
        [](double value, DefaultingPyMlirContext context) {
          MlirAttribute attr = mlirFloatAttrDoubleGet(
              context->get(), mlirF64TypeGet(context->get()), value);
          return PyFloatAttribute(context->getRef(), attr);
        },
        py::arg("value"), py::arg("context") = py::none(),
        "Gets an uniqued float point attribute associated to a f64 type");
    c.def_property_readonly(
        "value",
        [](PyFloatAttribute &self) {
          return mlirFloatAttrGetValueDouble(self);
        },
        "Returns the value of the float point attribute");
  }
};

/// Integer Attribute subclass - IntegerAttr.
class PyIntegerAttribute : public PyConcreteAttribute<PyIntegerAttribute> {
public:
  static constexpr IsAFunctionTy isaFunction = mlirAttributeIsAInteger;
  static constexpr const char *pyClassName = "IntegerAttr";
  using PyConcreteAttribute::PyConcreteAttribute;

  static void bindDerived(ClassTy &c) {
    c.def_static(
        "get",
        [](PyType &type, int64_t value) {
          MlirAttribute attr = mlirIntegerAttrGet(type, value);
          return PyIntegerAttribute(type.getContext(), attr);
        },
        py::arg("type"), py::arg("value"),
        "Gets an uniqued integer attribute associated to a type");
    c.def_property_readonly(
        "value",
        [](PyIntegerAttribute &self) {
          return mlirIntegerAttrGetValueInt(self);
        },
        "Returns the value of the integer attribute");
  }
};

/// Bool Attribute subclass - BoolAttr.
class PyBoolAttribute : public PyConcreteAttribute<PyBoolAttribute> {
public:
  static constexpr IsAFunctionTy isaFunction = mlirAttributeIsABool;
  static constexpr const char *pyClassName = "BoolAttr";
  using PyConcreteAttribute::PyConcreteAttribute;

  static void bindDerived(ClassTy &c) {
    c.def_static(
        "get",
        [](bool value, DefaultingPyMlirContext context) {
          MlirAttribute attr = mlirBoolAttrGet(context->get(), value);
          return PyBoolAttribute(context->getRef(), attr);
        },
        py::arg("value"), py::arg("context") = py::none(),
        "Gets an uniqued bool attribute");
    c.def_property_readonly(
        "value",
        [](PyBoolAttribute &self) { return mlirBoolAttrGetValue(self); },
        "Returns the value of the bool attribute");
  }
};

class PyFlatSymbolRefAttribute
    : public PyConcreteAttribute<PyFlatSymbolRefAttribute> {
public:
  static constexpr IsAFunctionTy isaFunction = mlirAttributeIsAFlatSymbolRef;
  static constexpr const char *pyClassName = "FlatSymbolRefAttr";
  using PyConcreteAttribute::PyConcreteAttribute;

  static void bindDerived(ClassTy &c) {
    c.def_static(
        "get",
        [](std::string value, DefaultingPyMlirContext context) {
          MlirAttribute attr =
              mlirFlatSymbolRefAttrGet(context->get(), toMlirStringRef(value));
          return PyFlatSymbolRefAttribute(context->getRef(), attr);
        },
        py::arg("value"), py::arg("context") = py::none(),
        "Gets a uniqued FlatSymbolRef attribute");
    c.def_property_readonly(
        "value",
        [](PyFlatSymbolRefAttribute &self) {
          MlirStringRef stringRef = mlirFlatSymbolRefAttrGetValue(self);
          return py::str(stringRef.data, stringRef.length);
        },
        "Returns the value of the FlatSymbolRef attribute as a string");
  }
};

class PyStringAttribute : public PyConcreteAttribute<PyStringAttribute> {
public:
  static constexpr IsAFunctionTy isaFunction = mlirAttributeIsAString;
  static constexpr const char *pyClassName = "StringAttr";
  using PyConcreteAttribute::PyConcreteAttribute;

  static void bindDerived(ClassTy &c) {
    c.def_static(
        "get",
        [](std::string value, DefaultingPyMlirContext context) {
          MlirAttribute attr =
              mlirStringAttrGet(context->get(), toMlirStringRef(value));
          return PyStringAttribute(context->getRef(), attr);
        },
        py::arg("value"), py::arg("context") = py::none(),
        "Gets a uniqued string attribute");
    c.def_static(
        "get_typed",
        [](PyType &type, std::string value) {
          MlirAttribute attr =
              mlirStringAttrTypedGet(type, toMlirStringRef(value));
          return PyStringAttribute(type.getContext(), attr);
        },

        "Gets a uniqued string attribute associated to a type");
    c.def_property_readonly(
        "value",
        [](PyStringAttribute &self) {
          MlirStringRef stringRef = mlirStringAttrGetValue(self);
          return py::str(stringRef.data, stringRef.length);
        },
        "Returns the value of the string attribute");
  }
};

// TODO: Support construction of bool elements.
// TODO: Support construction of string elements.
class PyDenseElementsAttribute
    : public PyConcreteAttribute<PyDenseElementsAttribute> {
public:
  static constexpr IsAFunctionTy isaFunction = mlirAttributeIsADenseElements;
  static constexpr const char *pyClassName = "DenseElementsAttr";
  using PyConcreteAttribute::PyConcreteAttribute;

  static PyDenseElementsAttribute
  getFromBuffer(py::buffer array, bool signless,
                DefaultingPyMlirContext contextWrapper) {
    // Request a contiguous view. In exotic cases, this will cause a copy.
    int flags = PyBUF_C_CONTIGUOUS | PyBUF_FORMAT;
    Py_buffer *view = new Py_buffer();
    if (PyObject_GetBuffer(array.ptr(), view, flags) != 0) {
      delete view;
      throw py::error_already_set();
    }
    py::buffer_info arrayInfo(view);

    MlirContext context = contextWrapper->get();
    // Switch on the types that can be bulk loaded between the Python and
    // MLIR-C APIs.
    // See: https://docs.python.org/3/library/struct.html#format-characters
    if (arrayInfo.format == "f") {
      // f32
      assert(arrayInfo.itemsize == 4 && "mismatched array itemsize");
      return PyDenseElementsAttribute(
          contextWrapper->getRef(),
          bulkLoad(context, mlirDenseElementsAttrFloatGet,
                   mlirF32TypeGet(context), arrayInfo));
    } else if (arrayInfo.format == "d") {
      // f64
      assert(arrayInfo.itemsize == 8 && "mismatched array itemsize");
      return PyDenseElementsAttribute(
          contextWrapper->getRef(),
          bulkLoad(context, mlirDenseElementsAttrDoubleGet,
                   mlirF64TypeGet(context), arrayInfo));
    } else if (isSignedIntegerFormat(arrayInfo.format)) {
      if (arrayInfo.itemsize == 4) {
        // i32
        MlirType elementType = signless ? mlirIntegerTypeGet(context, 32)
                                        : mlirIntegerTypeSignedGet(context, 32);
        return PyDenseElementsAttribute(contextWrapper->getRef(),
                                        bulkLoad(context,
                                                 mlirDenseElementsAttrInt32Get,
                                                 elementType, arrayInfo));
      } else if (arrayInfo.itemsize == 8) {
        // i64
        MlirType elementType = signless ? mlirIntegerTypeGet(context, 64)
                                        : mlirIntegerTypeSignedGet(context, 64);
        return PyDenseElementsAttribute(contextWrapper->getRef(),
                                        bulkLoad(context,
                                                 mlirDenseElementsAttrInt64Get,
                                                 elementType, arrayInfo));
      }
    } else if (isUnsignedIntegerFormat(arrayInfo.format)) {
      if (arrayInfo.itemsize == 4) {
        // unsigned i32
        MlirType elementType = signless
                                   ? mlirIntegerTypeGet(context, 32)
                                   : mlirIntegerTypeUnsignedGet(context, 32);
        return PyDenseElementsAttribute(contextWrapper->getRef(),
                                        bulkLoad(context,
                                                 mlirDenseElementsAttrUInt32Get,
                                                 elementType, arrayInfo));
      } else if (arrayInfo.itemsize == 8) {
        // unsigned i64
        MlirType elementType = signless
                                   ? mlirIntegerTypeGet(context, 64)
                                   : mlirIntegerTypeUnsignedGet(context, 64);
        return PyDenseElementsAttribute(contextWrapper->getRef(),
                                        bulkLoad(context,
                                                 mlirDenseElementsAttrUInt64Get,
                                                 elementType, arrayInfo));
      }
    }

    // TODO: Fall back to string-based get.
    std::string message = "unimplemented array format conversion from format: ";
    message.append(arrayInfo.format);
    throw SetPyError(PyExc_ValueError, message);
  }

  static PyDenseElementsAttribute getSplat(PyType shapedType,
                                           PyAttribute &elementAttr) {
    auto contextWrapper =
        PyMlirContext::forContext(mlirTypeGetContext(shapedType));
    if (!mlirAttributeIsAInteger(elementAttr) &&
        !mlirAttributeIsAFloat(elementAttr)) {
      std::string message = "Illegal element type for DenseElementsAttr: ";
      message.append(py::repr(py::cast(elementAttr)));
      throw SetPyError(PyExc_ValueError, message);
    }
    if (!mlirTypeIsAShaped(shapedType) ||
        !mlirShapedTypeHasStaticShape(shapedType)) {
      std::string message =
          "Expected a static ShapedType for the shaped_type parameter: ";
      message.append(py::repr(py::cast(shapedType)));
      throw SetPyError(PyExc_ValueError, message);
    }
    MlirType shapedElementType = mlirShapedTypeGetElementType(shapedType);
    MlirType attrType = mlirAttributeGetType(elementAttr);
    if (!mlirTypeEqual(shapedElementType, attrType)) {
      std::string message =
          "Shaped element type and attribute type must be equal: shaped=";
      message.append(py::repr(py::cast(shapedType)));
      message.append(", element=");
      message.append(py::repr(py::cast(elementAttr)));
      throw SetPyError(PyExc_ValueError, message);
    }

    MlirAttribute elements =
        mlirDenseElementsAttrSplatGet(shapedType, elementAttr);
    return PyDenseElementsAttribute(contextWrapper->getRef(), elements);
  }

  intptr_t dunderLen() { return mlirElementsAttrGetNumElements(*this); }

  py::buffer_info accessBuffer() {
    MlirType shapedType = mlirAttributeGetType(*this);
    MlirType elementType = mlirShapedTypeGetElementType(shapedType);

    if (mlirTypeIsAF32(elementType)) {
      // f32
      return bufferInfo(shapedType, mlirDenseElementsAttrGetFloatValue);
    } else if (mlirTypeIsAF64(elementType)) {
      // f64
      return bufferInfo(shapedType, mlirDenseElementsAttrGetDoubleValue);
    } else if (mlirTypeIsAInteger(elementType) &&
               mlirIntegerTypeGetWidth(elementType) == 32) {
      if (mlirIntegerTypeIsSignless(elementType) ||
          mlirIntegerTypeIsSigned(elementType)) {
        // i32
        return bufferInfo(shapedType, mlirDenseElementsAttrGetInt32Value);
      } else if (mlirIntegerTypeIsUnsigned(elementType)) {
        // unsigned i32
        return bufferInfo(shapedType, mlirDenseElementsAttrGetUInt32Value);
      }
    } else if (mlirTypeIsAInteger(elementType) &&
               mlirIntegerTypeGetWidth(elementType) == 64) {
      if (mlirIntegerTypeIsSignless(elementType) ||
          mlirIntegerTypeIsSigned(elementType)) {
        // i64
        return bufferInfo(shapedType, mlirDenseElementsAttrGetInt64Value);
      } else if (mlirIntegerTypeIsUnsigned(elementType)) {
        // unsigned i64
        return bufferInfo(shapedType, mlirDenseElementsAttrGetUInt64Value);
      }
    }

    std::string message = "unimplemented array format.";
    throw SetPyError(PyExc_ValueError, message);
  }

  static void bindDerived(ClassTy &c) {
    c.def("__len__", &PyDenseElementsAttribute::dunderLen)
        .def_static("get", PyDenseElementsAttribute::getFromBuffer,
                    py::arg("array"), py::arg("signless") = true,
                    py::arg("context") = py::none(),
                    "Gets from a buffer or ndarray")
        .def_static("get_splat", PyDenseElementsAttribute::getSplat,
                    py::arg("shaped_type"), py::arg("element_attr"),
                    "Gets a DenseElementsAttr where all values are the same")
        .def_property_readonly("is_splat",
                               [](PyDenseElementsAttribute &self) -> bool {
                                 return mlirDenseElementsAttrIsSplat(self);
                               })
        .def_buffer(&PyDenseElementsAttribute::accessBuffer);
  }

private:
  template <typename ElementTy>
  static MlirAttribute
  bulkLoad(MlirContext context,
           MlirAttribute (*ctor)(MlirType, intptr_t, ElementTy *),
           MlirType mlirElementType, py::buffer_info &arrayInfo) {
    SmallVector<int64_t, 4> shape(arrayInfo.shape.begin(),
                                  arrayInfo.shape.begin() + arrayInfo.ndim);
    MlirAttribute encodingAttr = mlirAttributeGetNull();
    auto shapedType = mlirRankedTensorTypeGet(shape.size(), shape.data(),
                                              mlirElementType, encodingAttr);
    intptr_t numElements = arrayInfo.size;
    const ElementTy *contents = static_cast<const ElementTy *>(arrayInfo.ptr);
    return ctor(shapedType, numElements, contents);
  }

  static bool isUnsignedIntegerFormat(const std::string &format) {
    if (format.empty())
      return false;
    char code = format[0];
    return code == 'I' || code == 'B' || code == 'H' || code == 'L' ||
           code == 'Q';
  }

  static bool isSignedIntegerFormat(const std::string &format) {
    if (format.empty())
      return false;
    char code = format[0];
    return code == 'i' || code == 'b' || code == 'h' || code == 'l' ||
           code == 'q';
  }

  template <typename Type>
  py::buffer_info bufferInfo(MlirType shapedType,
                             Type (*value)(MlirAttribute, intptr_t)) {
    intptr_t rank = mlirShapedTypeGetRank(shapedType);
    // Prepare the data for the buffer_info.
    // Buffer is configured for read-only access below.
    Type *data = static_cast<Type *>(
        const_cast<void *>(mlirDenseElementsAttrGetRawData(*this)));
    // Prepare the shape for the buffer_info.
    SmallVector<intptr_t, 4> shape;
    for (intptr_t i = 0; i < rank; ++i)
      shape.push_back(mlirShapedTypeGetDimSize(shapedType, i));
    // Prepare the strides for the buffer_info.
    SmallVector<intptr_t, 4> strides;
    intptr_t strideFactor = 1;
    for (intptr_t i = 1; i < rank; ++i) {
      strideFactor = 1;
      for (intptr_t j = i; j < rank; ++j) {
        strideFactor *= mlirShapedTypeGetDimSize(shapedType, j);
      }
      strides.push_back(sizeof(Type) * strideFactor);
    }
    strides.push_back(sizeof(Type));
    return py::buffer_info(data, sizeof(Type),
                           py::format_descriptor<Type>::format(), rank, shape,
                           strides, /*readonly=*/true);
  }
}; // namespace

/// Refinement of the PyDenseElementsAttribute for attributes containing integer
/// (and boolean) values. Supports element access.
class PyDenseIntElementsAttribute
    : public PyConcreteAttribute<PyDenseIntElementsAttribute,
                                 PyDenseElementsAttribute> {
public:
  static constexpr IsAFunctionTy isaFunction = mlirAttributeIsADenseIntElements;
  static constexpr const char *pyClassName = "DenseIntElementsAttr";
  using PyConcreteAttribute::PyConcreteAttribute;

  /// Returns the element at the given linear position. Asserts if the index is
  /// out of range.
  py::int_ dunderGetItem(intptr_t pos) {
    if (pos < 0 || pos >= dunderLen()) {
      throw SetPyError(PyExc_IndexError,
                       "attempt to access out of bounds element");
    }

    MlirType type = mlirAttributeGetType(*this);
    type = mlirShapedTypeGetElementType(type);
    assert(mlirTypeIsAInteger(type) &&
           "expected integer element type in dense int elements attribute");
    // Dispatch element extraction to an appropriate C function based on the
    // elemental type of the attribute. py::int_ is implicitly constructible
    // from any C++ integral type and handles bitwidth correctly.
    // TODO: consider caching the type properties in the constructor to avoid
    // querying them on each element access.
    unsigned width = mlirIntegerTypeGetWidth(type);
    bool isUnsigned = mlirIntegerTypeIsUnsigned(type);
    if (isUnsigned) {
      if (width == 1) {
        return mlirDenseElementsAttrGetBoolValue(*this, pos);
      }
      if (width == 32) {
        return mlirDenseElementsAttrGetUInt32Value(*this, pos);
      }
      if (width == 64) {
        return mlirDenseElementsAttrGetUInt64Value(*this, pos);
      }
    } else {
      if (width == 1) {
        return mlirDenseElementsAttrGetBoolValue(*this, pos);
      }
      if (width == 32) {
        return mlirDenseElementsAttrGetInt32Value(*this, pos);
      }
      if (width == 64) {
        return mlirDenseElementsAttrGetInt64Value(*this, pos);
      }
    }
    throw SetPyError(PyExc_TypeError, "Unsupported integer type");
  }

  static void bindDerived(ClassTy &c) {
    c.def("__getitem__", &PyDenseIntElementsAttribute::dunderGetItem);
  }
};

class PyDictAttribute : public PyConcreteAttribute<PyDictAttribute> {
public:
  static constexpr IsAFunctionTy isaFunction = mlirAttributeIsADictionary;
  static constexpr const char *pyClassName = "DictAttr";
  using PyConcreteAttribute::PyConcreteAttribute;

  intptr_t dunderLen() { return mlirDictionaryAttrGetNumElements(*this); }

  static void bindDerived(ClassTy &c) {
    c.def("__len__", &PyDictAttribute::dunderLen);
    c.def_static(
        "get",
        [](py::dict attributes, DefaultingPyMlirContext context) {
          SmallVector<MlirNamedAttribute> mlirNamedAttributes;
          mlirNamedAttributes.reserve(attributes.size());
          for (auto &it : attributes) {
            auto &mlir_attr = it.second.cast<PyAttribute &>();
            auto name = it.first.cast<std::string>();
            mlirNamedAttributes.push_back(mlirNamedAttributeGet(
                mlirIdentifierGet(mlirAttributeGetContext(mlir_attr),
                                  toMlirStringRef(name)),
                mlir_attr));
          }
          MlirAttribute attr =
              mlirDictionaryAttrGet(context->get(), mlirNamedAttributes.size(),
                                    mlirNamedAttributes.data());
          return PyDictAttribute(context->getRef(), attr);
        },
        py::arg("value"), py::arg("context") = py::none(),
        "Gets an uniqued dict attribute");
    c.def("__getitem__", [](PyDictAttribute &self, const std::string &name) {
      MlirAttribute attr =
          mlirDictionaryAttrGetElementByName(self, toMlirStringRef(name));
      if (mlirAttributeIsNull(attr)) {
        throw SetPyError(PyExc_KeyError,
                         "attempt to access a non-existent attribute");
      }
      return PyAttribute(self.getContext(), attr);
    });
    c.def("__getitem__", [](PyDictAttribute &self, intptr_t index) {
      if (index < 0 || index >= self.dunderLen()) {
        throw SetPyError(PyExc_IndexError,
                         "attempt to access out of bounds attribute");
      }
      MlirNamedAttribute namedAttr = mlirDictionaryAttrGetElement(self, index);
      return PyNamedAttribute(
          namedAttr.attribute,
          std::string(mlirIdentifierStr(namedAttr.name).data));
    });
  }
};

/// Refinement of PyDenseElementsAttribute for attributes containing
/// floating-point values. Supports element access.
class PyDenseFPElementsAttribute
    : public PyConcreteAttribute<PyDenseFPElementsAttribute,
                                 PyDenseElementsAttribute> {
public:
  static constexpr IsAFunctionTy isaFunction = mlirAttributeIsADenseFPElements;
  static constexpr const char *pyClassName = "DenseFPElementsAttr";
  using PyConcreteAttribute::PyConcreteAttribute;

  py::float_ dunderGetItem(intptr_t pos) {
    if (pos < 0 || pos >= dunderLen()) {
      throw SetPyError(PyExc_IndexError,
                       "attempt to access out of bounds element");
    }

    MlirType type = mlirAttributeGetType(*this);
    type = mlirShapedTypeGetElementType(type);
    // Dispatch element extraction to an appropriate C function based on the
    // elemental type of the attribute. py::float_ is implicitly constructible
    // from float and double.
    // TODO: consider caching the type properties in the constructor to avoid
    // querying them on each element access.
    if (mlirTypeIsAF32(type)) {
      return mlirDenseElementsAttrGetFloatValue(*this, pos);
    }
    if (mlirTypeIsAF64(type)) {
      return mlirDenseElementsAttrGetDoubleValue(*this, pos);
    }
    throw SetPyError(PyExc_TypeError, "Unsupported floating-point type");
  }

  static void bindDerived(ClassTy &c) {
    c.def("__getitem__", &PyDenseFPElementsAttribute::dunderGetItem);
  }
};

class PyTypeAttribute : public PyConcreteAttribute<PyTypeAttribute> {
public:
  static constexpr IsAFunctionTy isaFunction = mlirAttributeIsAType;
  static constexpr const char *pyClassName = "TypeAttr";
  using PyConcreteAttribute::PyConcreteAttribute;

  static void bindDerived(ClassTy &c) {
    c.def_static(
        "get",
        [](PyType value, DefaultingPyMlirContext context) {
          MlirAttribute attr = mlirTypeAttrGet(value.get());
          return PyTypeAttribute(context->getRef(), attr);
        },
        py::arg("value"), py::arg("context") = py::none(),
        "Gets a uniqued Type attribute");
    c.def_property_readonly("value", [](PyTypeAttribute &self) {
      return PyType(self.getContext()->getRef(),
                    mlirTypeAttrGetValue(self.get()));
    });
  }
};

/// Unit Attribute subclass. Unit attributes don't have values.
class PyUnitAttribute : public PyConcreteAttribute<PyUnitAttribute> {
public:
  static constexpr IsAFunctionTy isaFunction = mlirAttributeIsAUnit;
  static constexpr const char *pyClassName = "UnitAttr";
  using PyConcreteAttribute::PyConcreteAttribute;

  static void bindDerived(ClassTy &c) {
    c.def_static(
        "get",
        [](DefaultingPyMlirContext context) {
          return PyUnitAttribute(context->getRef(),
                                 mlirUnitAttrGet(context->get()));
        },
        py::arg("context") = py::none(), "Create a Unit attribute.");
  }
};

} // namespace

void mlir::python::populateIRAttributes(py::module &m) {
  PyAffineMapAttribute::bind(m);
  PyArrayAttribute::bind(m);
  PyArrayAttribute::PyArrayAttributeIterator::bind(m);
  PyBoolAttribute::bind(m);
  PyDenseElementsAttribute::bind(m);
  PyDenseFPElementsAttribute::bind(m);
  PyDenseIntElementsAttribute::bind(m);
  PyDictAttribute::bind(m);
  PyFlatSymbolRefAttribute::bind(m);
  PyFloatAttribute::bind(m);
  PyIntegerAttribute::bind(m);
  PyStringAttribute::bind(m);
  PyTypeAttribute::bind(m);
  PyUnitAttribute::bind(m);
}