[MLIR][python bindings] TypeCasters for Attributes

[makslevental]

Summary

This diff adds casting for Attributes similar to that of Types.

[makslevental]

add DenseArray and DenseIntOrFPElements support

[makslevental]

remove .operator std::string()

[makslevental]

remove cruft

[makslevental]

add BoolAttr

[makslevental]

restore static_typeid on IntegerAttr

[makslevental]

increase use-case coverage and add support for mlir_attribute_subclass

[makslevental]

update tests

[makslevental]

clean up and repr for mlir_attribute_subclass

[makslevental]

a few more tests

[rkayaith]

Awesome, just some minor comments.

There may be some comments to update as well, like https://github.com/llvm/llvm-project/blob/9ad3ca4e9a310c1507578b1c8165cd61a9a45037/mlir/include/mlir-c/Bindings/Python/Interop.h#L112

mlir/lib/Bindings/Python/IRAttributes.cpp

415

maybe a comment here explaining why getTypeIdFunction isn't used?

mlir/lib/Bindings/Python/IRCore.cpp

3195–3198

can this ever happen? below it's just an assert

mlir/test/python/ir/builtin_types.py

404–408 ↗

(On Diff #528682)

returning None here might be a better API? I don't have any strong opinion, but it'd be more consistent with PyRankedTensorType.encoding as well

[makslevental]

update comments

mlir/lib/Bindings/Python/IRCore.cpp

3195–3198

if you get to the caster then you definitely have a typeid (otherwise there wouldn't have been a match for a/some key in the typecaster densemap) but here you might be able to call typeid on some strange attribute.

[makslevental]

mlir/include/mlir/Bindings/Python/PybindAdaptors.h

418–419

just wanted to point out how descriptive this comment string is 😂

[rkayaith]

mlir/lib/Bindings/Python/IRCore.cpp

3195–3198

here you might be able to call typeid on some strange attribute.

Only case I can think of is if you called mlirAttributeGetTypeID on a null attribute, but in that case it looks like the call would crash instead of returning a null TypeID

[makslevental]

change exception to assert

[makslevental]

mlir/lib/Bindings/Python/IRCore.cpp

3195–3198

i double checked and right you are - it segfaults. so i did as you imply and changed to an assert.

mlir/include/mlir-c/BuiltinAttributes.h

 
 /// Creates an affine map attribute wrapping the given map. The attribute
 /// belongs to the same context as the affine map.
 MLIR_CAPI_EXPORTED MlirAttribute mlirAffineMapAttrGet(MlirAffineMap map);
 
 /// Returns the affine map wrapped in the given affine map attribute.
 MLIR_CAPI_EXPORTED MlirAffineMap mlirAffineMapAttrGetValue(MlirAttribute attr);
 
+/// Returns the typeID of an AffineMap attribute.
+MLIR_CAPI_EXPORTED MlirTypeID mlirAffineMapAttrGetTypeID(void);
+
 //===----------------------------------------------------------------------===//
 // Array attribute.
 //===----------------------------------------------------------------------===//
 
 /// Checks whether the given attribute is an array attribute.
 MLIR_CAPI_EXPORTED bool mlirAttributeIsAArray(MlirAttribute attr);
 
 /// Creates an array element containing the given list of elements in the given
 /// context.
 MLIR_CAPI_EXPORTED MlirAttribute mlirArrayAttrGet(
     MlirContext ctx, intptr_t numElements, MlirAttribute const *elements);
 
 /// Returns the number of elements stored in the given array attribute.
 MLIR_CAPI_EXPORTED intptr_t mlirArrayAttrGetNumElements(MlirAttribute attr);
 
 /// Returns pos-th element stored in the given array attribute.
 MLIR_CAPI_EXPORTED MlirAttribute mlirArrayAttrGetElement(MlirAttribute attr,
                                                          intptr_t pos);
 
+/// Returns the typeID of an Array attribute.
+MLIR_CAPI_EXPORTED MlirTypeID mlirArrayAttrGetTypeID(void);
+
 //===----------------------------------------------------------------------===//
 // Dictionary attribute.
 //===----------------------------------------------------------------------===//
 
 /// Checks whether the given attribute is a dictionary attribute.
 MLIR_CAPI_EXPORTED bool mlirAttributeIsADictionary(MlirAttribute attr);
 
 /// Creates a dictionary attribute containing the given list of elements in the

 MLIR_CAPI_EXPORTED MlirNamedAttribute
 mlirDictionaryAttrGetElement(MlirAttribute attr, intptr_t pos);
 
 /// Returns the dictionary attribute element with the given name or NULL if the
 /// given name does not exist in the dictionary.
 MLIR_CAPI_EXPORTED MlirAttribute
 mlirDictionaryAttrGetElementByName(MlirAttribute attr, MlirStringRef name);
 
+/// Returns the typeID of a Dictionary attribute.
+MLIR_CAPI_EXPORTED MlirTypeID mlirDictionaryAttrGetTypeID(void);
+
 //===----------------------------------------------------------------------===//
 // Floating point attribute.
 //===----------------------------------------------------------------------===//
 
 // TODO: add support for APFloat and APInt to LLVM IR C API, then expose the
 // relevant functions here.
 
 /// Checks whether the given attribute is a floating point attribute.

 MLIR_CAPI_EXPORTED MlirAttribute mlirFloatAttrDoubleGetChecked(MlirLocation loc,
                                                                MlirType type,
                                                                double value);
 
 /// Returns the value stored in the given floating point attribute, interpreting
 /// the value as double.
 MLIR_CAPI_EXPORTED double mlirFloatAttrGetValueDouble(MlirAttribute attr);
 
+/// Returns the typeID of a Float attribute.
+MLIR_CAPI_EXPORTED MlirTypeID mlirFloatAttrGetTypeID(void);
+
 //===----------------------------------------------------------------------===//
 // Integer attribute.
 //===----------------------------------------------------------------------===//
 
 // TODO: add support for APFloat and APInt to LLVM IR C API, then expose the
 // relevant functions here.
 
 /// Checks whether the given attribute is an integer attribute.

 /// Returns the value stored in the given integer attribute, assuming the value
 /// is of signed type and fits into a signed 64-bit integer.
 MLIR_CAPI_EXPORTED int64_t mlirIntegerAttrGetValueSInt(MlirAttribute attr);
 
 /// Returns the value stored in the given integer attribute, assuming the value
 /// is of unsigned type and fits into an unsigned 64-bit integer.
 MLIR_CAPI_EXPORTED uint64_t mlirIntegerAttrGetValueUInt(MlirAttribute attr);
 
+/// Returns the typeID of an Integer attribute.
+MLIR_CAPI_EXPORTED MlirTypeID mlirIntegerAttrGetTypeID(void);
+
 //===----------------------------------------------------------------------===//
 // Bool attribute.
 //===----------------------------------------------------------------------===//
 
 /// Checks whether the given attribute is a bool attribute.
 MLIR_CAPI_EXPORTED bool mlirAttributeIsABool(MlirAttribute attr);
 
 /// Creates a bool attribute in the given context with the given value.
 MLIR_CAPI_EXPORTED MlirAttribute mlirBoolAttrGet(MlirContext ctx, int value);
 
 /// Returns the value stored in the given bool attribute.
 MLIR_CAPI_EXPORTED bool mlirBoolAttrGetValue(MlirAttribute attr);
 
 //===----------------------------------------------------------------------===//
 // Integer set attribute.
 //===----------------------------------------------------------------------===//
 
 /// Checks whether the given attribute is an integer set attribute.
 MLIR_CAPI_EXPORTED bool mlirAttributeIsAIntegerSet(MlirAttribute attr);
 
+/// Returns the typeID of an IntegerSet attribute.
+MLIR_CAPI_EXPORTED MlirTypeID mlirIntegerSetAttrGetTypeID(void);
+
 //===----------------------------------------------------------------------===//
 // Opaque attribute.
 //===----------------------------------------------------------------------===//
 
 /// Checks whether the given attribute is an opaque attribute.
 MLIR_CAPI_EXPORTED bool mlirAttributeIsAOpaque(MlirAttribute attr);
 
 /// Creates an opaque attribute in the given context associated with the dialect
 /// identified by its namespace. The attribute contains opaque byte data of the
 /// specified length (data need not be null-terminated).
 MLIR_CAPI_EXPORTED MlirAttribute
 mlirOpaqueAttrGet(MlirContext ctx, MlirStringRef dialectNamespace,
                   intptr_t dataLength, const char *data, MlirType type);
 
 /// Returns the namespace of the dialect with which the given opaque attribute
 /// is associated. The namespace string is owned by the context.
 MLIR_CAPI_EXPORTED MlirStringRef
 mlirOpaqueAttrGetDialectNamespace(MlirAttribute attr);
 
 /// Returns the raw data as a string reference. The data remains live as long as
 /// the context in which the attribute lives.
 MLIR_CAPI_EXPORTED MlirStringRef mlirOpaqueAttrGetData(MlirAttribute attr);
 
+/// Returns the typeID of an Opaque attribute.
+MLIR_CAPI_EXPORTED MlirTypeID mlirOpaqueAttrGetTypeID(void);
+
 //===----------------------------------------------------------------------===//
 // String attribute.
 //===----------------------------------------------------------------------===//
 
 /// Checks whether the given attribute is a string attribute.
 MLIR_CAPI_EXPORTED bool mlirAttributeIsAString(MlirAttribute attr);
 
 /// Creates a string attribute in the given context containing the given string.
 
 MLIR_CAPI_EXPORTED MlirAttribute mlirStringAttrGet(MlirContext ctx,
                                                    MlirStringRef str);
 
 /// Creates a string attribute in the given context containing the given string.
 /// Additionally, the attribute has the given type.
 MLIR_CAPI_EXPORTED MlirAttribute mlirStringAttrTypedGet(MlirType type,
                                                         MlirStringRef str);
 
 /// Returns the attribute values as a string reference. The data remains live as
 /// long as the context in which the attribute lives.
 MLIR_CAPI_EXPORTED MlirStringRef mlirStringAttrGetValue(MlirAttribute attr);
 
+/// Returns the typeID of a String attribute.
+MLIR_CAPI_EXPORTED MlirTypeID mlirStringAttrGetTypeID(void);
+
 //===----------------------------------------------------------------------===//
 // SymbolRef attribute.
 //===----------------------------------------------------------------------===//
 
 /// Checks whether the given attribute is a symbol reference attribute.
 MLIR_CAPI_EXPORTED bool mlirAttributeIsASymbolRef(MlirAttribute attr);
 
 /// Creates a symbol reference attribute in the given context referencing a

 /// attribute.
 MLIR_CAPI_EXPORTED intptr_t
 mlirSymbolRefAttrGetNumNestedReferences(MlirAttribute attr);
 
 /// Returns pos-th reference nested in the given symbol reference attribute.
 MLIR_CAPI_EXPORTED MlirAttribute
 mlirSymbolRefAttrGetNestedReference(MlirAttribute attr, intptr_t pos);
 
+/// Returns the typeID of an SymbolRef attribute.
+MLIR_CAPI_EXPORTED MlirTypeID mlirSymbolRefAttrGetTypeID(void);
+
 //===----------------------------------------------------------------------===//
 // Flat SymbolRef attribute.
 //===----------------------------------------------------------------------===//
 
 /// Checks whether the given attribute is a flat symbol reference attribute.
 MLIR_CAPI_EXPORTED bool mlirAttributeIsAFlatSymbolRef(MlirAttribute attr);
 
 /// Creates a flat symbol reference attribute in the given context referencing a
 /// symbol identified by the given string.
 MLIR_CAPI_EXPORTED MlirAttribute mlirFlatSymbolRefAttrGet(MlirContext ctx,
                                                           MlirStringRef symbol);
 
 /// Returns the referenced symbol as a string reference. The data remains live
 /// as long as the context in which the attribute lives.
 MLIR_CAPI_EXPORTED MlirStringRef
 mlirFlatSymbolRefAttrGetValue(MlirAttribute attr);
 
+/// Returns the typeID of an FlatSymbolRef attribute.
+MLIR_CAPI_EXPORTED MlirTypeID mlirFlatSymbolRefAttrGetTypeID(void);
+
 //===----------------------------------------------------------------------===//
 // Type attribute.
 //===----------------------------------------------------------------------===//
 
 /// Checks whether the given attribute is a type attribute.
 MLIR_CAPI_EXPORTED bool mlirAttributeIsAType(MlirAttribute attr);
 
 /// Creates a type attribute wrapping the given type in the same context as the
 /// type.
 MLIR_CAPI_EXPORTED MlirAttribute mlirTypeAttrGet(MlirType type);
 
 /// Returns the type stored in the given type attribute.
 MLIR_CAPI_EXPORTED MlirType mlirTypeAttrGetValue(MlirAttribute attr);
 
+/// Returns the typeID of a Type attribute.
+MLIR_CAPI_EXPORTED MlirTypeID mlirTypeAttrGetTypeID(void);
+
 //===----------------------------------------------------------------------===//
 // Unit attribute.
 //===----------------------------------------------------------------------===//
 
 /// Checks whether the given attribute is a unit attribute.
 MLIR_CAPI_EXPORTED bool mlirAttributeIsAUnit(MlirAttribute attr);
 
 /// Creates a unit attribute in the given context.
 MLIR_CAPI_EXPORTED MlirAttribute mlirUnitAttrGet(MlirContext ctx);
 
+/// Returns the typeID of a Unit attribute.
+MLIR_CAPI_EXPORTED MlirTypeID mlirUnitAttrGetTypeID(void);
+
 //===----------------------------------------------------------------------===//
 // Elements attributes.
 //===----------------------------------------------------------------------===//
 
 /// Checks whether the given attribute is an elements attribute.
 MLIR_CAPI_EXPORTED bool mlirAttributeIsAElements(MlirAttribute attr);
 
 /// Returns the element at the given rank-dimensional index.

 /// to iterate over the attribute, obtain its type, which must be a statically
 /// shaped type and use its sizes to build a multi-dimensional index.
 MLIR_CAPI_EXPORTED int64_t mlirElementsAttrGetNumElements(MlirAttribute attr);
 
 //===----------------------------------------------------------------------===//
 // Dense array attribute.
 //===----------------------------------------------------------------------===//
 
+MLIR_CAPI_EXPORTED MlirTypeID mlirDenseArrayAttrGetTypeID(void);
+
 /// Checks whether the given attribute is a dense array attribute.
 MLIR_CAPI_EXPORTED bool mlirAttributeIsADenseBoolArray(MlirAttribute attr);
 MLIR_CAPI_EXPORTED bool mlirAttributeIsADenseI8Array(MlirAttribute attr);
 MLIR_CAPI_EXPORTED bool mlirAttributeIsADenseI16Array(MlirAttribute attr);
 MLIR_CAPI_EXPORTED bool mlirAttributeIsADenseI32Array(MlirAttribute attr);
 MLIR_CAPI_EXPORTED bool mlirAttributeIsADenseI64Array(MlirAttribute attr);
 MLIR_CAPI_EXPORTED bool mlirAttributeIsADenseF32Array(MlirAttribute attr);
 MLIR_CAPI_EXPORTED bool mlirAttributeIsADenseF64Array(MlirAttribute attr);

 // TODO: add support for APFloat and APInt to LLVM IR C API, then expose the
 // relevant functions here.
 
 /// Checks whether the given attribute is a dense elements attribute.
 MLIR_CAPI_EXPORTED bool mlirAttributeIsADenseElements(MlirAttribute attr);
 MLIR_CAPI_EXPORTED bool mlirAttributeIsADenseIntElements(MlirAttribute attr);
 MLIR_CAPI_EXPORTED bool mlirAttributeIsADenseFPElements(MlirAttribute attr);
 
+/// Returns the typeID of an DenseIntOrFPElements attribute.
+MLIR_CAPI_EXPORTED MlirTypeID mlirDenseIntOrFPElementsAttrGetTypeID(void);
+
 /// Creates a dense elements attribute with the given Shaped type and elements
 /// in the same context as the type.
 MLIR_CAPI_EXPORTED MlirAttribute mlirDenseElementsAttrGet(
     MlirType shapedType, intptr_t numElements, MlirAttribute const *elements);
 
 /// Creates a dense elements attribute with the given Shaped type and elements
 /// populated from a packed, row-major opaque buffer of contents.
 ///

 MLIR_CAPI_EXPORTED MlirAttribute
 mlirSparseElementsAttrGetIndices(MlirAttribute attr);
 
 /// Returns the dense elements attribute containing the non-null elements in the
 /// given sparse elements attribute.
 MLIR_CAPI_EXPORTED MlirAttribute
 mlirSparseElementsAttrGetValues(MlirAttribute attr);
 
+/// Returns the typeID of a SparseElements attribute.
+MLIR_CAPI_EXPORTED MlirTypeID mlirSparseElementsAttrGetTypeID(void);
+
 //===----------------------------------------------------------------------===//
 // Strided layout attribute.
 //===----------------------------------------------------------------------===//
 
 // Checks wheather the given attribute is a strided layout attribute.
 MLIR_CAPI_EXPORTED bool mlirAttributeIsAStridedLayout(MlirAttribute attr);
 
 // Creates a strided layout attribute from given strides and offset.
 MLIR_CAPI_EXPORTED MlirAttribute
 mlirStridedLayoutAttrGet(MlirContext ctx, int64_t offset, intptr_t numStrides,
                          const int64_t *strides);
 
 // Returns the offset in the given strided layout layout attribute.
 MLIR_CAPI_EXPORTED int64_t mlirStridedLayoutAttrGetOffset(MlirAttribute attr);
 
 // Returns the number of strides in the given strided layout attribute.
 MLIR_CAPI_EXPORTED intptr_t
 mlirStridedLayoutAttrGetNumStrides(MlirAttribute attr);
 
 // Returns the pos-th stride stored in the given strided layout attribute.
 MLIR_CAPI_EXPORTED int64_t mlirStridedLayoutAttrGetStride(MlirAttribute attr,
                                                           intptr_t pos);
 
+/// Returns the typeID of a StridedLayout attribute.
+MLIR_CAPI_EXPORTED MlirTypeID mlirStridedLayoutAttrGetTypeID(void);
+
 #ifdef __cplusplus
 }
 #endif
 
 #endif // MLIR_C_BUILTINATTRIBUTES_H

mlir/include/mlir-c/IR.h

 MLIR_CAPI_EXPORTED MlirContext mlirAttributeGetContext(MlirAttribute attribute);
 
 /// Gets the type of this attribute.
 MLIR_CAPI_EXPORTED MlirType mlirAttributeGetType(MlirAttribute attribute);
 
 /// Gets the type id of the attribute.
 MLIR_CAPI_EXPORTED MlirTypeID mlirAttributeGetTypeID(MlirAttribute attribute);
 
+/// Gets the dialect of the attribute.
+MLIR_CAPI_EXPORTED MlirDialect mlirAttributeGetDialect(MlirAttribute attribute);
+
 /// Checks whether an attribute is null.
 static inline bool mlirAttributeIsNull(MlirAttribute attr) { return !attr.ptr; }
 
 /// Checks if two attributes are equal.
 MLIR_CAPI_EXPORTED bool mlirAttributeEqual(MlirAttribute a1, MlirAttribute a2);
 
 /// Prints an attribute by sending chunks of the string representation and
 /// forwarding `userData to `callback`. Note that the callback may be called

mlir/include/mlir/Bindings/Python/PybindAdaptors.h

bool load(handle src, bool) {
     return !mlirAttributeIsNull(value);
   }
   static handle cast(MlirAttribute v, return_value_policy, handle) {
     py::object capsule =
         py::reinterpret_steal<py::object>(mlirPythonAttributeToCapsule(v));
     return py::module::import(MAKE_MLIR_PYTHON_QUALNAME("ir"))
         .attr("Attribute")
         .attr(MLIR_PYTHON_CAPI_FACTORY_ATTR)(capsule)
+        .attr(MLIR_PYTHON_MAYBE_DOWNCAST_ATTR)()
         .release();
   }
 };
 
 /// Casts object -> MlirContext.
 template <>
 struct type_caster<MlirContext> {
   PYBIND11_TYPE_CASTER(MlirContext, _("MlirContext"));
py::cpp_function newCf(
           }
           py::object self = superCls.attr("__new__")(cls, otherAttribute);
           return self;
         },
         py::name("__new__"), py::arg("cls"), py::arg("cast_from_attr"));
     thisClass.attr("__new__") = newCf;
 
     // 'isinstance' method.
     def_staticmethod(
         "isinstance",
         [isaFunction](MlirAttribute other) { return isaFunction(other); },
         py::arg("other_attribute"));
   }
 };
 
 /// Creates a custom subclass of mlir.ir.Type, implementing a casting
 /// constructor and type checking methods.
 class mlir_type_subclass : public pure_subclass {

mlir/lib/Bindings/Python/IRAttributes.cpp

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 constexpr GetTypeIDFunctionTy getTypeIdFunction =
+      mlirAffineMapAttrGetTypeID;
 
   static void bindDerived(ClassTy &c) {
     c.def_static(
         "get",
         [](PyAffineMap &affineMap) {
           MlirAttribute attr = mlirAffineMapAttrGet(affineMap.get());
           return PyAffineMapAttribute(affineMap.getContext(), attr);
         },
struct PyDenseF64ArrayAttribute
   using PyDenseArrayAttribute::PyDenseArrayAttribute;
 };
 
 class PyArrayAttribute : public PyConcreteAttribute<PyArrayAttribute> {
 public:
   static constexpr IsAFunctionTy isaFunction = mlirAttributeIsAArray;
   static constexpr const char *pyClassName = "ArrayAttr";
   using PyConcreteAttribute::PyConcreteAttribute;
+  static constexpr GetTypeIDFunctionTy getTypeIdFunction =
+      mlirArrayAttrGetTypeID;
 
   class PyArrayAttributeIterator {
   public:
     PyArrayAttributeIterator(PyAttribute attr) : attr(std::move(attr)) {}
 
     PyArrayAttributeIterator &dunderIter() { return *this; }
 
     PyAttribute dunderNext() {

 };
 
 /// 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 constexpr GetTypeIDFunctionTy getTypeIdFunction =
+      mlirFloatAttrGetTypeID;
 
   static void bindDerived(ClassTy &c) {
     c.def_static(
         "get",
         [](PyType &type, double value, DefaultingPyLocation loc) {
           PyMlirContext::ErrorCapture errors(loc->getContext());
           MlirAttribute attr = mlirFloatAttrDoubleGetChecked(loc, type, value);
           if (mlirAttributeIsNull(attr))
c.def_property_readonly(
           MlirType type = mlirAttributeGetType(self);
           if (mlirTypeIsAIndex(type) || mlirIntegerTypeIsSignless(type))
             return mlirIntegerAttrGetValueInt(self);
           if (mlirIntegerTypeIsSigned(type))
             return mlirIntegerAttrGetValueSInt(self);
           return mlirIntegerAttrGetValueUInt(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;

 };
 
 class PyFlatSymbolRefAttribute
     : public PyConcreteAttribute<PyFlatSymbolRefAttribute> {
 public:
   static constexpr IsAFunctionTy isaFunction = mlirAttributeIsAFlatSymbolRef;
   static constexpr const char *pyClassName = "FlatSymbolRefAttr";
   using PyConcreteAttribute::PyConcreteAttribute;
+  static constexpr GetTypeIDFunctionTy getTypeIdFunction =
+      mlirFlatSymbolRefAttrGetTypeID;
 
   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);
public:
   }
 };
 
 class PyOpaqueAttribute : public PyConcreteAttribute<PyOpaqueAttribute> {
 public:
   static constexpr IsAFunctionTy isaFunction = mlirAttributeIsAOpaque;
   static constexpr const char *pyClassName = "OpaqueAttr";
   using PyConcreteAttribute::PyConcreteAttribute;
+  static constexpr GetTypeIDFunctionTy getTypeIdFunction =
+      mlirOpaqueAttrGetTypeID;
 
   static void bindDerived(ClassTy &c) {
     c.def_static(
         "get",
         [](std::string dialectNamespace, py::buffer buffer, PyType &type,
            DefaultingPyMlirContext context) {
           const py::buffer_info bufferInfo = buffer.request();
           intptr_t bufferSize = bufferInfo.size;
public:
   }
 };
 
 class PyStringAttribute : public PyConcreteAttribute<PyStringAttribute> {
 public:
   static constexpr IsAFunctionTy isaFunction = mlirAttributeIsAString;
   static constexpr const char *pyClassName = "StringAttr";
   using PyConcreteAttribute::PyConcreteAttribute;
+  static constexpr GetTypeIDFunctionTy getTypeIdFunction =
+      mlirStringAttrGetTypeID;
 
   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);
public:
   }
 };
 
 class PyDictAttribute : public PyConcreteAttribute<PyDictAttribute> {
 public:
   static constexpr IsAFunctionTy isaFunction = mlirAttributeIsADictionary;
   static constexpr const char *pyClassName = "DictAttr";
   using PyConcreteAttribute::PyConcreteAttribute;
+  static constexpr GetTypeIDFunctionTy getTypeIdFunction =
+      mlirDictionaryAttrGetTypeID;
 
   intptr_t dunderLen() { return mlirDictionaryAttrGetNumElements(*this); }
 
   bool dunderContains(const std::string &name) {
     return !mlirAttributeIsNull(
         mlirDictionaryAttrGetElementByName(*this, toMlirStringRef(name)));
   }
 
public:
   }
 };
 
 class PyTypeAttribute : public PyConcreteAttribute<PyTypeAttribute> {
 public:
   static constexpr IsAFunctionTy isaFunction = mlirAttributeIsAType;
   static constexpr const char *pyClassName = "TypeAttr";
   using PyConcreteAttribute::PyConcreteAttribute;
+  static constexpr GetTypeIDFunctionTy getTypeIdFunction =
+      mlirTypeAttrGetTypeID;
 
   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 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 constexpr GetTypeIDFunctionTy getTypeIdFunction =
+      mlirUnitAttrGetTypeID;
 
   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.");
   }
 };
 
 /// Strided layout attribute subclass.
 class PyStridedLayoutAttribute
     : public PyConcreteAttribute<PyStridedLayoutAttribute> {
 public:
   static constexpr IsAFunctionTy isaFunction = mlirAttributeIsAStridedLayout;
   static constexpr const char *pyClassName = "StridedLayoutAttr";
   using PyConcreteAttribute::PyConcreteAttribute;
+  static constexpr GetTypeIDFunctionTy getTypeIdFunction =
+      mlirStridedLayoutAttrGetTypeID;
 
   static void bindDerived(ClassTy &c) {
     c.def_static(
         "get",
         [](int64_t offset, const std::vector<int64_t> strides,
            DefaultingPyMlirContext ctx) {
           MlirAttribute attr = mlirStridedLayoutAttrGet(
               ctx->get(), offset, strides.size(), strides.data());
c.def_property_readonly(
             strides[i] = mlirStridedLayoutAttrGetStride(self, i);
           }
           return strides;
         },
         "Returns the value of the float point attribute");
   }
 };
 
+py::object denseArrayAttributeCaster(PyAttribute &pyAttribute) {
+  if (PyDenseBoolArrayAttribute::isaFunction(pyAttribute))
+    return py::cast(PyDenseBoolArrayAttribute(pyAttribute));
+  if (PyDenseI8ArrayAttribute::isaFunction(pyAttribute))
+    return py::cast(PyDenseI8ArrayAttribute(pyAttribute));
+  if (PyDenseI16ArrayAttribute::isaFunction(pyAttribute))
+    return py::cast(PyDenseI16ArrayAttribute(pyAttribute));
+  if (PyDenseI32ArrayAttribute::isaFunction(pyAttribute))
+    return py::cast(PyDenseI32ArrayAttribute(pyAttribute));
+  if (PyDenseI64ArrayAttribute::isaFunction(pyAttribute))
+    return py::cast(PyDenseI64ArrayAttribute(pyAttribute));
+  if (PyDenseF32ArrayAttribute::isaFunction(pyAttribute))
+    return py::cast(PyDenseF32ArrayAttribute(pyAttribute));
+  if (PyDenseF64ArrayAttribute::isaFunction(pyAttribute))
+    return py::cast(PyDenseF64ArrayAttribute(pyAttribute));
+  std::string msg =
+      std::string("Can't cast unknown element type DenseArrayAttr (") +
+      std::string(py::repr(py::cast(pyAttribute))) + ")";
+  throw py::cast_error(msg);
+}
+
+py::object denseIntOrFPElementsAttributeCaster(PyAttribute &pyAttribute) {
+  if (PyDenseFPElementsAttribute::isaFunction(pyAttribute))
+    return py::cast(PyDenseFPElementsAttribute(pyAttribute));
+  if (PyDenseIntElementsAttribute::isaFunction(pyAttribute))
+    return py::cast(PyDenseIntElementsAttribute(pyAttribute));
+  std::string msg =
+      std::string(
+          "Can't cast unknown element type DenseIntOrFPElementsAttr (") +
+      std::string(py::repr(py::cast(pyAttribute))) + ")";
+  throw py::cast_error(msg);
+}
+
+py::object integerOrBoolAttributeCaster(PyAttribute &pyAttribute) {
+  if (PyBoolAttribute::isaFunction(pyAttribute))
+    return py::cast(PyBoolAttribute(pyAttribute));
+  if (PyIntegerAttribute::isaFunction(pyAttribute))
+    return py::cast(PyIntegerAttribute(pyAttribute));
+  std::string msg =
+      std::string("Can't cast unknown element type DenseArrayAttr (") +
+      std::string(py::repr(py::cast(pyAttribute))) + ")";
+  throw py::cast_error(msg);
+}
+
 } // namespace
 
 void mlir::python::populateIRAttributes(py::module &m) {
   PyAffineMapAttribute::bind(m);
 
   PyDenseBoolArrayAttribute::bind(m);
   PyDenseBoolArrayAttribute::PyDenseArrayIterator::bind(m);
   PyDenseI8ArrayAttribute::bind(m);
   PyDenseI8ArrayAttribute::PyDenseArrayIterator::bind(m);
   PyDenseI16ArrayAttribute::bind(m);
   PyDenseI16ArrayAttribute::PyDenseArrayIterator::bind(m);
   PyDenseI32ArrayAttribute::bind(m);
   PyDenseI32ArrayAttribute::PyDenseArrayIterator::bind(m);
   PyDenseI64ArrayAttribute::bind(m);
   PyDenseI64ArrayAttribute::PyDenseArrayIterator::bind(m);
   PyDenseF32ArrayAttribute::bind(m);
   PyDenseF32ArrayAttribute::PyDenseArrayIterator::bind(m);
   PyDenseF64ArrayAttribute::bind(m);
   PyDenseF64ArrayAttribute::PyDenseArrayIterator::bind(m);
+  PyGlobals::get().registerTypeCaster(
+      mlirDenseArrayAttrGetTypeID(),
+      pybind11::cpp_function(denseArrayAttributeCaster));
 
   PyArrayAttribute::bind(m);
   PyArrayAttribute::PyArrayAttributeIterator::bind(m);
   PyBoolAttribute::bind(m);
   PyDenseElementsAttribute::bind(m);
   PyDenseFPElementsAttribute::bind(m);
   PyDenseIntElementsAttribute::bind(m);
+  PyGlobals::get().registerTypeCaster(
+      mlirDenseIntOrFPElementsAttrGetTypeID(),
+      pybind11::cpp_function(denseIntOrFPElementsAttributeCaster));
+
   PyDictAttribute::bind(m);
   PyFlatSymbolRefAttribute::bind(m);
   PyOpaqueAttribute::bind(m);
   PyFloatAttribute::bind(m);
   PyIntegerAttribute::bind(m);
   PyStringAttribute::bind(m);
   PyTypeAttribute::bind(m);
+  PyGlobals::get().registerTypeCaster(
+      mlirIntegerAttrGetTypeID(),
+      pybind11::cpp_function(integerOrBoolAttributeCaster));
   PyUnitAttribute::bind(m);
 
   PyStridedLayoutAttribute::bind(m);
 }

mlir/lib/Bindings/Python/IRCore.cpp

py::class_<PyLocation>(m, "Location", py::module_local())
           py::arg("attribute"), py::arg("context") = py::none(),
           "Gets a Location from a LocationAttr")
       .def_property_readonly(
           "context",
           [](PyLocation &self) { return self.getContext().getObject(); },
           "Context that owns the Location")
       .def_property_readonly(
           "attr",
-          [](PyLocation &self) {
-            return PyAttribute(self.getContext(),
-                               mlirLocationGetAttribute(self));
-          },
+          [](PyLocation &self) { return mlirLocationGetAttribute(self); },
           "Get the underlying LocationAttr")
       .def(
           "emit_error",
           [](PyLocation &self, std::string message) {
             mlirEmitError(self, message.c_str());
           },
           py::arg("message"), "Emits an error at this location")
       .def("__repr__", [](PyLocation &self) {
py::class_<PyAttribute>(m, "Attribute", py::module_local())
       .def_static(
           "parse",
           [](std::string attrSpec, DefaultingPyMlirContext context) {
             PyMlirContext::ErrorCapture errors(context->getRef());
             MlirAttribute type = mlirAttributeParseGet(
                 context->get(), toMlirStringRef(attrSpec));
             if (mlirAttributeIsNull(type))
               throw MLIRError("Unable to parse attribute", errors.take());
-            return PyAttribute(context->getRef(), type);
+            return type;
           },
           py::arg("asm"), py::arg("context") = py::none(),
           "Parses an attribute from an assembly form. Raises an MLIRError on "
           "failure.")
       .def_property_readonly(
           "context",
           [](PyAttribute &self) { return self.getContext().getObject(); },
           "Context that owns the Attribute")
py::class_<PyAttribute>(m, "Attribute", py::module_local())
           "__str__",
           [](PyAttribute &self) {
             PyPrintAccumulator printAccum;
             mlirAttributePrint(self, printAccum.getCallback(),
                                printAccum.getUserData());
             return printAccum.join();
           },
           "Returns the assembly form of the Attribute.")
-      .def("__repr__", [](PyAttribute &self) {
+      .def("__repr__",
+           [](PyAttribute &self) {
              // Generally, assembly formats are not printed for __repr__ because
              // this can cause exceptionally long debug output and exceptions.
-        // However, attribute values are generally considered useful and are
-        // printed. This may need to be re-evaluated if debug dumps end up
-        // being excessive.
+             // However, attribute values are generally considered useful and
+             // are printed. This may need to be re-evaluated if debug dumps end
+             // up being excessive.
              PyPrintAccumulator printAccum;
              printAccum.parts.append("Attribute(");
              mlirAttributePrint(self, printAccum.getCallback(),
                                 printAccum.getUserData());
              printAccum.parts.append(")");
              return printAccum.join();
+           })
+      .def_property_readonly(
+          "typeid",
+          [](PyAttribute &self) -> MlirTypeID {
+            MlirTypeID mlirTypeID = mlirAttributeGetTypeID(self);
+            if (!mlirTypeIDIsNull(mlirTypeID))
+              return mlirTypeID;
+            auto origRepr =
+                pybind11::repr(pybind11::cast(self)).cast<std::string>();
+            throw py::value_error(
+                (origRepr + llvm::Twine(" has no typeid.")).str());
+          })
+      .def(MLIR_PYTHON_MAYBE_DOWNCAST_ATTR, [](PyAttribute &self) {
+        MlirTypeID mlirTypeID = mlirAttributeGetTypeID(self);
+        assert(!mlirTypeIDIsNull(mlirTypeID) &&
+               "mlirTypeID was expected to be non-null.");
+        std::optional<pybind11::function> typeCaster =
+            PyGlobals::get().lookupTypeCaster(mlirTypeID,
+                                              mlirAttributeGetDialect(self));
+        if (!typeCaster)
+          return py::cast(self);
+        return typeCaster.value()(self);
       });
 
   //----------------------------------------------------------------------------
   // Mapping of PyNamedAttribute
   //----------------------------------------------------------------------------
   py::class_<PyNamedAttribute>(m, "NamedAttribute", py::module_local())
       .def("__repr__",
            [](PyNamedAttribute &self) {
py::class_<PyNamedAttribute>(m, "NamedAttribute", py::module_local())
           "name",
           [](PyNamedAttribute &self) {
             return py::str(mlirIdentifierStr(self.namedAttr.name).data,
                            mlirIdentifierStr(self.namedAttr.name).length);
           },
           "The name of the NamedAttribute binding")
       .def_property_readonly(
           "attr",
-          [](PyNamedAttribute &self) {
-            // TODO: When named attribute is removed/refactored, also remove
-            // this constructor (it does an inefficient table lookup).
-            auto contextRef = PyMlirContext::forContext(
-                mlirAttributeGetContext(self.namedAttr.attribute));
-            return PyAttribute(std::move(contextRef), self.namedAttr.attribute);
-          },
+          [](PyNamedAttribute &self) { return self.namedAttr.attribute; },
           py::keep_alive<0, 1>(),
           "The underlying generic attribute of the NamedAttribute binding");
 
   //----------------------------------------------------------------------------
   // Mapping of PyType.
   //----------------------------------------------------------------------------
   py::class_<PyType>(m, "Type", py::module_local())
       // Delegate to the PyType copy constructor, which will also lifetime

mlir/lib/Bindings/Python/IRModule.h

 template <typename DerivedTy, typename BaseTy = PyAttribute>
 class PyConcreteAttribute : public BaseTy {
 public:
   // Derived classes must define statics for:
   //   IsAFunctionTy isaFunction
   //   const char *pyClassName
   using ClassTy = pybind11::class_<DerivedTy, BaseTy>;
   using IsAFunctionTy = bool (*)(MlirAttribute);
+  using GetTypeIDFunctionTy = MlirTypeID (*)();
+  static constexpr GetTypeIDFunctionTy getTypeIdFunction = nullptr;
 
   PyConcreteAttribute() = default;
   PyConcreteAttribute(PyMlirContextRef contextRef, MlirAttribute attr)
       : BaseTy(std::move(contextRef), attr) {}
   PyConcreteAttribute(PyAttribute &orig)
       : PyConcreteAttribute(orig.getContext(), castFrom(orig)) {}
 
   static MlirAttribute castFrom(PyAttribute &orig) {
static void bind(pybind11::module &m) {
     cls.def_static(
         "isinstance",
         [](PyAttribute &otherAttr) -> bool {
           return DerivedTy::isaFunction(otherAttr);
         },
         pybind11::arg("other"));
     cls.def_property_readonly(
         "type", [](PyAttribute &attr) { return mlirAttributeGetType(attr); });
+    cls.def_property_readonly_static(
+        "static_typeid", [](py::object & /*class*/) -> MlirTypeID {
+          if (DerivedTy::getTypeIdFunction)
+            return DerivedTy::getTypeIdFunction();
+          throw py::attribute_error(
+              (DerivedTy::pyClassName + llvm::Twine(" has no typeid.")).str());
+        });
+    cls.def_property_readonly("typeid", [](PyAttribute &self) {
+      return py::cast(self).attr("typeid").cast<MlirTypeID>();
+    });
+    cls.def("__repr__", [](DerivedTy &self) {
+      PyPrintAccumulator printAccum;
+      printAccum.parts.append(DerivedTy::pyClassName);
+      printAccum.parts.append("(");
+      mlirAttributePrint(self, printAccum.getCallback(),
+                         printAccum.getUserData());
+      printAccum.parts.append(")");
+      return printAccum.join();
+    });
+
+    if (DerivedTy::getTypeIdFunction) {
+      PyGlobals::get().registerTypeCaster(
+          DerivedTy::getTypeIdFunction(),
+          pybind11::cpp_function([](PyAttribute pyAttribute) -> DerivedTy {
+            return pyAttribute;
+          }));
+    }
+
     DerivedTy::bindDerived(cls);
   }
 
   /// Implemented by derived classes to add methods to the Python subclass.
   static void bindDerived(ClassTy &m) {}
 };
 
 /// Wrapper around the generic MlirValue.

mlir/lib/CAPI/IR/BuiltinAttributes.cpp

 MlirAttribute mlirAffineMapAttrGet(MlirAffineMap map) {
   return wrap(AffineMapAttr::get(unwrap(map)));
 }
 
 MlirAffineMap mlirAffineMapAttrGetValue(MlirAttribute attr) {
   return wrap(llvm::cast<AffineMapAttr>(unwrap(attr)).getValue());
 }
 
+MlirTypeID mlirAffineMapAttrGetTypeID(void) {
+  return wrap(AffineMapAttr::getTypeID());
+}
+
 //===----------------------------------------------------------------------===//
 // Array attribute.
 //===----------------------------------------------------------------------===//
 
 bool mlirAttributeIsAArray(MlirAttribute attr) {
   return llvm::isa<ArrayAttr>(unwrap(attr));
 }
 
 MlirAttribute mlirArrayAttrGet(MlirContext ctx, intptr_t numElements,
                                MlirAttribute const *elements) {
   SmallVector<Attribute, 8> attrs;
   return wrap(
       ArrayAttr::get(unwrap(ctx), unwrapList(static_cast<size_t>(numElements),
                                              elements, attrs)));
 }
 
 intptr_t mlirArrayAttrGetNumElements(MlirAttribute attr) {
   return static_cast<intptr_t>(llvm::cast<ArrayAttr>(unwrap(attr)).size());
 }
 
 MlirAttribute mlirArrayAttrGetElement(MlirAttribute attr, intptr_t pos) {
   return wrap(llvm::cast<ArrayAttr>(unwrap(attr)).getValue()[pos]);
 }
 
+MlirTypeID mlirArrayAttrGetTypeID(void) { return wrap(ArrayAttr::getTypeID()); }
+
 //===----------------------------------------------------------------------===//
 // Dictionary attribute.
 //===----------------------------------------------------------------------===//
 
 bool mlirAttributeIsADictionary(MlirAttribute attr) {
   return llvm::isa<DictionaryAttr>(unwrap(attr));
 }
 
MlirNamedAttribute mlirDictionaryAttrGetElement(MlirAttribute attr,
   return {wrap(attribute.getName()), wrap(attribute.getValue())};
 }
 
 MlirAttribute mlirDictionaryAttrGetElementByName(MlirAttribute attr,
                                                  MlirStringRef name) {
   return wrap(llvm::cast<DictionaryAttr>(unwrap(attr)).get(unwrap(name)));
 }
 
+MlirTypeID mlirDictionaryAttrGetTypeID(void) {
+  return wrap(DictionaryAttr::getTypeID());
+}
+
 //===----------------------------------------------------------------------===//
 // Floating point attribute.
 //===----------------------------------------------------------------------===//
 
 bool mlirAttributeIsAFloat(MlirAttribute attr) {
   return llvm::isa<FloatAttr>(unwrap(attr));
 }
 
 MlirAttribute mlirFloatAttrDoubleGet(MlirContext ctx, MlirType type,
                                      double value) {
   return wrap(FloatAttr::get(unwrap(type), value));
 }
 
 MlirAttribute mlirFloatAttrDoubleGetChecked(MlirLocation loc, MlirType type,
                                             double value) {
   return wrap(FloatAttr::getChecked(unwrap(loc), unwrap(type), value));
 }
 
 double mlirFloatAttrGetValueDouble(MlirAttribute attr) {
   return llvm::cast<FloatAttr>(unwrap(attr)).getValueAsDouble();
 }
 
+MlirTypeID mlirFloatAttrGetTypeID(void) { return wrap(FloatAttr::getTypeID()); }
+
 //===----------------------------------------------------------------------===//
 // Integer attribute.
 //===----------------------------------------------------------------------===//
 
 bool mlirAttributeIsAInteger(MlirAttribute attr) {
   return llvm::isa<IntegerAttr>(unwrap(attr));
 }
 
 MlirAttribute mlirIntegerAttrGet(MlirType type, int64_t value) {
   return wrap(IntegerAttr::get(unwrap(type), value));
 }
 
 int64_t mlirIntegerAttrGetValueInt(MlirAttribute attr) {
   return llvm::cast<IntegerAttr>(unwrap(attr)).getInt();
 }
 
 int64_t mlirIntegerAttrGetValueSInt(MlirAttribute attr) {
   return llvm::cast<IntegerAttr>(unwrap(attr)).getSInt();
 }
 
 uint64_t mlirIntegerAttrGetValueUInt(MlirAttribute attr) {
   return llvm::cast<IntegerAttr>(unwrap(attr)).getUInt();
 }
 
+MlirTypeID mlirIntegerAttrGetTypeID(void) {
+  return wrap(IntegerAttr::getTypeID());
+}
+
 //===----------------------------------------------------------------------===//
 // Bool attribute.
 //===----------------------------------------------------------------------===//
 
 bool mlirAttributeIsABool(MlirAttribute attr) {
   return llvm::isa<BoolAttr>(unwrap(attr));
 }
 
 MlirAttribute mlirBoolAttrGet(MlirContext ctx, int value) {
   return wrap(BoolAttr::get(unwrap(ctx), value));
 }
 
 bool mlirBoolAttrGetValue(MlirAttribute attr) {
   return llvm::cast<BoolAttr>(unwrap(attr)).getValue();
 }
 
 //===----------------------------------------------------------------------===//
 // Integer set attribute.
 //===----------------------------------------------------------------------===//
 
 bool mlirAttributeIsAIntegerSet(MlirAttribute attr) {
   return llvm::isa<IntegerSetAttr>(unwrap(attr));
 }
 
+MlirTypeID mlirIntegerSetAttrGetTypeID(void) {
+  return wrap(IntegerSetAttr::getTypeID());
+}
+
 //===----------------------------------------------------------------------===//
 // Opaque attribute.
 //===----------------------------------------------------------------------===//
 
 bool mlirAttributeIsAOpaque(MlirAttribute attr) {
   return llvm::isa<OpaqueAttr>(unwrap(attr));
 }
 
MlirStringRef mlirOpaqueAttrGetDialectNamespace(MlirAttribute attr) {
   return wrap(
       llvm::cast<OpaqueAttr>(unwrap(attr)).getDialectNamespace().strref());
 }
 
 MlirStringRef mlirOpaqueAttrGetData(MlirAttribute attr) {
   return wrap(llvm::cast<OpaqueAttr>(unwrap(attr)).getAttrData());
 }
 
+MlirTypeID mlirOpaqueAttrGetTypeID(void) {
+  return wrap(OpaqueAttr::getTypeID());
+}
+
 //===----------------------------------------------------------------------===//
 // String attribute.
 //===----------------------------------------------------------------------===//
 
 bool mlirAttributeIsAString(MlirAttribute attr) {
   return llvm::isa<StringAttr>(unwrap(attr));
 }
 
 MlirAttribute mlirStringAttrGet(MlirContext ctx, MlirStringRef str) {
   return wrap((Attribute)StringAttr::get(unwrap(ctx), unwrap(str)));
 }
 
 MlirAttribute mlirStringAttrTypedGet(MlirType type, MlirStringRef str) {
   return wrap((Attribute)StringAttr::get(unwrap(str), unwrap(type)));
 }
 
 MlirStringRef mlirStringAttrGetValue(MlirAttribute attr) {
   return wrap(llvm::cast<StringAttr>(unwrap(attr)).getValue());
 }
 
+MlirTypeID mlirStringAttrGetTypeID(void) {
+  return wrap(StringAttr::getTypeID());
+}
+
 //===----------------------------------------------------------------------===//
 // SymbolRef attribute.
 //===----------------------------------------------------------------------===//
 
 bool mlirAttributeIsASymbolRef(MlirAttribute attr) {
   return llvm::isa<SymbolRefAttr>(unwrap(attr));
 }
 

 }
 
 MlirAttribute mlirSymbolRefAttrGetNestedReference(MlirAttribute attr,
                                                   intptr_t pos) {
   return wrap(
       llvm::cast<SymbolRefAttr>(unwrap(attr)).getNestedReferences()[pos]);
 }
 
+MlirTypeID mlirSymbolRefAttrGetTypeID(void) {
+  return wrap(SymbolRefAttr::getTypeID());
+}
+
 //===----------------------------------------------------------------------===//
 // Flat SymbolRef attribute.
 //===----------------------------------------------------------------------===//
 
 bool mlirAttributeIsAFlatSymbolRef(MlirAttribute attr) {
   return llvm::isa<FlatSymbolRefAttr>(unwrap(attr));
 }
 
 MlirAttribute mlirFlatSymbolRefAttrGet(MlirContext ctx, MlirStringRef symbol) {
   return wrap(FlatSymbolRefAttr::get(unwrap(ctx), unwrap(symbol)));
 }
 
 MlirStringRef mlirFlatSymbolRefAttrGetValue(MlirAttribute attr) {
   return wrap(llvm::cast<FlatSymbolRefAttr>(unwrap(attr)).getValue());
 }
 
+MlirTypeID mlirFlatSymbolRefAttrGetTypeID(void) {
+  return wrap(FlatSymbolRefAttr::getTypeID());
+}
+
 //===----------------------------------------------------------------------===//
 // Type attribute.
 //===----------------------------------------------------------------------===//
 
 bool mlirAttributeIsAType(MlirAttribute attr) {
   return llvm::isa<TypeAttr>(unwrap(attr));
 }
 
 MlirAttribute mlirTypeAttrGet(MlirType type) {
   return wrap(TypeAttr::get(unwrap(type)));
 }
 
 MlirType mlirTypeAttrGetValue(MlirAttribute attr) {
   return wrap(llvm::cast<TypeAttr>(unwrap(attr)).getValue());
 }
 
+MlirTypeID mlirTypeAttrGetTypeID(void) { return wrap(TypeAttr::getTypeID()); }
+
 //===----------------------------------------------------------------------===//
 // Unit attribute.
 //===----------------------------------------------------------------------===//
 
 bool mlirAttributeIsAUnit(MlirAttribute attr) {
   return llvm::isa<UnitAttr>(unwrap(attr));
 }
 
 MlirAttribute mlirUnitAttrGet(MlirContext ctx) {
   return wrap(UnitAttr::get(unwrap(ctx)));
 }
 
+MlirTypeID mlirUnitAttrGetTypeID(void) { return wrap(UnitAttr::getTypeID()); }
+
 //===----------------------------------------------------------------------===//
 // Elements attributes.
 //===----------------------------------------------------------------------===//
 
 bool mlirAttributeIsAElements(MlirAttribute attr) {
   return llvm::isa<ElementsAttr>(unwrap(attr));
 }
 

 int64_t mlirElementsAttrGetNumElements(MlirAttribute attr) {
   return llvm::cast<ElementsAttr>(unwrap(attr)).getNumElements();
 }
 
 //===----------------------------------------------------------------------===//
 // Dense array attribute.
 //===----------------------------------------------------------------------===//
 
+MlirTypeID mlirDenseArrayAttrGetTypeID() {
+  return wrap(DenseArrayAttr::getTypeID());
+}
+
 //===----------------------------------------------------------------------===//
 // IsA support.
+//===----------------------------------------------------------------------===//
 
 bool mlirAttributeIsADenseBoolArray(MlirAttribute attr) {
   return llvm::isa<DenseBoolArrayAttr>(unwrap(attr));
 }
 bool mlirAttributeIsADenseI8Array(MlirAttribute attr) {
   return llvm::isa<DenseI8ArrayAttr>(unwrap(attr));
 }
 bool mlirAttributeIsADenseI16Array(MlirAttribute attr) {
bool mlirAttributeIsADenseF32Array(MlirAttribute attr) {
   return llvm::isa<DenseF32ArrayAttr>(unwrap(attr));
 }
 bool mlirAttributeIsADenseF64Array(MlirAttribute attr) {
   return llvm::isa<DenseF64ArrayAttr>(unwrap(attr));
 }
 
 //===----------------------------------------------------------------------===//
 // Constructors.
+//===----------------------------------------------------------------------===//
 
 MlirAttribute mlirDenseBoolArrayGet(MlirContext ctx, intptr_t size,
                                     int const *values) {
   SmallVector<bool, 4> elements(values, values + size);
   return wrap(DenseBoolArrayAttr::get(unwrap(ctx), elements));
 }
 MlirAttribute mlirDenseI8ArrayGet(MlirContext ctx, intptr_t size,
                                   int8_t const *values) {

 MlirAttribute mlirDenseF64ArrayGet(MlirContext ctx, intptr_t size,
                                    double const *values) {
   return wrap(
       DenseF64ArrayAttr::get(unwrap(ctx), ArrayRef<double>(values, size)));
 }
 
 //===----------------------------------------------------------------------===//
 // Accessors.
+//===----------------------------------------------------------------------===//
 
 intptr_t mlirDenseArrayGetNumElements(MlirAttribute attr) {
   return llvm::cast<DenseArrayAttr>(unwrap(attr)).size();
 }
 
 //===----------------------------------------------------------------------===//
 // Indexed accessors.
+//===----------------------------------------------------------------------===//
 
 bool mlirDenseBoolArrayGetElement(MlirAttribute attr, intptr_t pos) {
   return llvm::cast<DenseBoolArrayAttr>(unwrap(attr))[pos];
 }
 int8_t mlirDenseI8ArrayGetElement(MlirAttribute attr, intptr_t pos) {
   return llvm::cast<DenseI8ArrayAttr>(unwrap(attr))[pos];
 }
 int16_t mlirDenseI16ArrayGetElement(MlirAttribute attr, intptr_t pos) {

 }
 
 //===----------------------------------------------------------------------===//
 // Dense elements attribute.
 //===----------------------------------------------------------------------===//
 
 //===----------------------------------------------------------------------===//
 // IsA support.
+//===----------------------------------------------------------------------===//
 
 bool mlirAttributeIsADenseElements(MlirAttribute attr) {
   return llvm::isa<DenseElementsAttr>(unwrap(attr));
 }
+
 bool mlirAttributeIsADenseIntElements(MlirAttribute attr) {
   return llvm::isa<DenseIntElementsAttr>(unwrap(attr));
 }
+
 bool mlirAttributeIsADenseFPElements(MlirAttribute attr) {
   return llvm::isa<DenseFPElementsAttr>(unwrap(attr));
 }
 
+MlirTypeID mlirDenseIntOrFPElementsAttrGetTypeID(void) {
+  return wrap(DenseIntOrFPElementsAttr::getTypeID());
+}
+
 //===----------------------------------------------------------------------===//
 // Constructors.
+//===----------------------------------------------------------------------===//
 
 MlirAttribute mlirDenseElementsAttrGet(MlirType shapedType,
                                        intptr_t numElements,
                                        MlirAttribute const *elements) {
   SmallVector<Attribute, 8> attributes;
   return wrap(
       DenseElementsAttr::get(llvm::cast<ShapedType>(unwrap(shapedType)),
                              unwrapList(numElements, elements, attributes)));

 MlirAttribute mlirDenseElementsAttrReshapeGet(MlirAttribute attr,
                                               MlirType shapedType) {
   return wrap(llvm::cast<DenseElementsAttr>(unwrap(attr))
                   .reshape(llvm::cast<ShapedType>(unwrap(shapedType))));
 }
 
 //===----------------------------------------------------------------------===//
 // Splat accessors.
+//===----------------------------------------------------------------------===//
 
 bool mlirDenseElementsAttrIsSplat(MlirAttribute attr) {
   return llvm::cast<DenseElementsAttr>(unwrap(attr)).isSplat();
 }
 
 MlirAttribute mlirDenseElementsAttrGetSplatValue(MlirAttribute attr) {
   return wrap(
       llvm::cast<DenseElementsAttr>(unwrap(attr)).getSplatValue<Attribute>());

 }
 MlirStringRef mlirDenseElementsAttrGetStringSplatValue(MlirAttribute attr) {
   return wrap(
       llvm::cast<DenseElementsAttr>(unwrap(attr)).getSplatValue<StringRef>());
 }
 
 //===----------------------------------------------------------------------===//
 // Indexed accessors.
+//===----------------------------------------------------------------------===//
 
 bool mlirDenseElementsAttrGetBoolValue(MlirAttribute attr, intptr_t pos) {
   return llvm::cast<DenseElementsAttr>(unwrap(attr)).getValues<bool>()[pos];
 }
 int8_t mlirDenseElementsAttrGetInt8Value(MlirAttribute attr, intptr_t pos) {
   return llvm::cast<DenseElementsAttr>(unwrap(attr)).getValues<int8_t>()[pos];
 }
 uint8_t mlirDenseElementsAttrGetUInt8Value(MlirAttribute attr, intptr_t pos) {

 MlirStringRef mlirDenseElementsAttrGetStringValue(MlirAttribute attr,
                                                   intptr_t pos) {
   return wrap(
       llvm::cast<DenseElementsAttr>(unwrap(attr)).getValues<StringRef>()[pos]);
 }
 
 //===----------------------------------------------------------------------===//
 // Raw data accessors.
+//===----------------------------------------------------------------------===//
 
 const void *mlirDenseElementsAttrGetRawData(MlirAttribute attr) {
   return static_cast<const void *>(
       llvm::cast<DenseElementsAttr>(unwrap(attr)).getRawData().data());
 }
 
 //===----------------------------------------------------------------------===//
 // Resource blob attributes.

 MlirAttribute mlirSparseElementsAttrGetIndices(MlirAttribute attr) {
   return wrap(llvm::cast<SparseElementsAttr>(unwrap(attr)).getIndices());
 }
 
 MlirAttribute mlirSparseElementsAttrGetValues(MlirAttribute attr) {
   return wrap(llvm::cast<SparseElementsAttr>(unwrap(attr)).getValues());
 }
 
+MlirTypeID mlirSparseElementsAttrGetTypeID(void) {
+  return wrap(SparseElementsAttr::getTypeID());
+}
+
 //===----------------------------------------------------------------------===//
 // Strided layout attribute.
 //===----------------------------------------------------------------------===//
 
 bool mlirAttributeIsAStridedLayout(MlirAttribute attr) {
   return llvm::isa<StridedLayoutAttr>(unwrap(attr));
 }
 

 intptr_t mlirStridedLayoutAttrGetNumStrides(MlirAttribute attr) {
   return static_cast<intptr_t>(
       llvm::cast<StridedLayoutAttr>(unwrap(attr)).getStrides().size());
 }
 
 int64_t mlirStridedLayoutAttrGetStride(MlirAttribute attr, intptr_t pos) {
   return llvm::cast<StridedLayoutAttr>(unwrap(attr)).getStrides()[pos];
 }
+
+MlirTypeID mlirStridedLayoutAttrGetTypeID(void) {
+  return wrap(StridedLayoutAttr::getTypeID());
+}

mlir/lib/CAPI/IR/IR.cpp

if (auto typedAttr = llvm::dyn_cast<TypedAttr>(attr))
     return wrap(typedAttr.getType());
   return wrap(NoneType::get(attr.getContext()));
 }
 
 MlirTypeID mlirAttributeGetTypeID(MlirAttribute attr) {
   return wrap(unwrap(attr).getTypeID());
 }
 
+MlirDialect mlirAttributeGetDialect(MlirAttribute attr) {
+  return wrap(&unwrap(attr).getDialect());
+}
+
 bool mlirAttributeEqual(MlirAttribute a1, MlirAttribute a2) {
   return unwrap(a1) == unwrap(a2);
 }
 
 void mlirAttributePrint(MlirAttribute attr, MlirStringCallback callback,
                         void *userData) {
   detail::CallbackOstream stream(callback, userData);
   unwrap(attr).print(stream);

mlir/test/python/ir/attributes.py

 def testParsePrint():
     with Context() as ctx:
         t = Attribute.parse('"hello"')
     assert t.context is ctx
     ctx = None
     gc.collect()
     # CHECK: "hello"
     print(str(t))
-    # CHECK: Attribute("hello")
+    # CHECK: StringAttr("hello")
     print(repr(t))
 
 
 # CHECK-LABEL: TEST: testParseError
 @run
 def testParseError():
     with Context():
         try:

 
 # CHECK-LABEL: TEST: testStandardAttrCasts
 @run
 def testStandardAttrCasts():
     with Context():
         a1 = Attribute.parse('"attr1"')
         astr = StringAttr(a1)
         aself = StringAttr(astr)
-        # CHECK: Attribute("attr1")
+        # CHECK: StringAttr("attr1")
         print(repr(astr))
         try:
             tillegal = StringAttr(Attribute.parse("1.0"))
         except ValueError as e:
             # CHECK: ValueError: Cannot cast attribute to StringAttr (from Attribute(1.000000e+00 : f64))
             print("ValueError:", e)
         else:
             print("Exception not produced")
with Context():
         print()
 
         # CHECK: i1
         print(ShapedType(a.type).element_type)
 
 
 @run
 def testDenseArrayGetItem():
-    def print_item(AttrClass, attr_asm):
-        attr = AttrClass(Attribute.parse(attr_asm))
+    def print_item(attr_asm):
+        attr = Attribute.parse(attr_asm)
         print(f"{len(attr)}: {attr[0]}, {attr[1]}")
 
     with Context():
         # CHECK: 2: 0, 1
-        print_item(DenseBoolArrayAttr, "array<i1: false, true>")
+        print_item("array<i1: false, true>")
         # CHECK: 2: 2, 3
-        print_item(DenseI8ArrayAttr, "array<i8: 2, 3>")
+        print_item("array<i8: 2, 3>")
         # CHECK: 2: 4, 5
-        print_item(DenseI16ArrayAttr, "array<i16: 4, 5>")
+        print_item("array<i16: 4, 5>")
         # CHECK: 2: 6, 7
-        print_item(DenseI32ArrayAttr, "array<i32: 6, 7>")
+        print_item("array<i32: 6, 7>")
         # CHECK: 2: 8, 9
-        print_item(DenseI64ArrayAttr, "array<i64: 8, 9>")
+        print_item("array<i64: 8, 9>")
         # CHECK: 2: 1.{{0+}}, 2.{{0+}}
-        print_item(DenseF32ArrayAttr, "array<f32: 1.0, 2.0>")
+        print_item("array<f32: 1.0, 2.0>")
         # CHECK: 2: 3.{{0+}}, 4.{{0+}}
-        print_item(DenseF64ArrayAttr, "array<f64: 3.0, 4.0>")
+        print_item("array<f64: 3.0, 4.0>")
 
 
 # CHECK-LABEL: TEST: testDenseIntAttrGetItem
 @run
 def testDenseIntAttrGetItem():
     def print_item(attr_asm):
-        attr = DenseIntElementsAttr(Attribute.parse(attr_asm))
+        attr = Attribute.parse(attr_asm)
         dtype = ShapedType(attr.type).element_type
         try:
             item = attr[0]
             print(f"{dtype}:", item)
         except TypeError as e:
             print(f"{dtype}:", e)
 
     with Context():
with Context(), Location.unknown():
         # CHECK: attr: vector<4xf32>
         print("attr:", raw)
         type_attr = TypeAttr(raw)
 
         # CHECK: VectorType(vector<4xf32>)
         print(repr(type_attr.value))
         # CHECK: F32Type(f32)
         print(repr(type_attr.value.element_type))
+
+
+# CHECK-LABEL: TEST: testConcreteAttributesRoundTrip
+@run
+def testConcreteAttributesRoundTrip():
+    with Context(), Location.unknown():
+
+        # CHECK: FloatAttr(4.200000e+01 : f32)
+        print(repr(Attribute.parse("42.0 : f32")))