[mlir] First-party modeling of LLVM types

[ftynse]

Summary

The current modeling of LLVM IR types in MLIR is based on the LLVMType class
that wraps a raw llvm::Type * and delegates uniquing, printing and parsing to
LLVM itself. This model makes thread-safe type manipulation hard and is being
progressively replaced with a cleaner MLIR model that replicates the type
system. Introduce a set of classes reflecting the LLVM IR type system in MLIR
instead of wrapping the existing types. These are currently introduced as
separate classes without affecting the dialect flow, and are exercised through
a test dialect. Once feature parity is reached, the old implementation will be
gradually substituted with the new one.

Depends On D84171

[jdd]

mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp

2260

Why are you passing around the output stream instead of the DialogAsmPrinter? I would prefer the stack be in DialogAsmPrinter, be a stack of mlir::Type, and be automatically managed by DialogAsmPrinter so you're not relying on the closed nature of the LLVM type system. @rriddle seemed to be supportive of that idea or at least confirmed it would work. Do you consider this to be out-of-scope for this change?

[rriddle]

mlir/include/mlir/Dialect/LLVMIR/LLVMDialect.h

246 ↗

(On Diff #279857)

Please fix lint check.

mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp

1809

I would move these to an enum for KeyFlags/MutableFlags. Right now it is slightly confusing.

1895

Can we restructure this storage a bit? We could move the identified body Type[] to be a trailing object, and move that size here(as unsigned). We could then steal two bits from each of the sizes for the flags.

1927

You could pack this into the resultType with PointerIntPair, you just need to define PointerLikeTypeTraits for LLVMTypeNew(or drop it down to a Type and just case when accessing it).

[ftynse]

Ready for review

[ftynse]

mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp

1895

We could move the identified body Type[] to be a trailing object, and move that size here(as unsigned).

This would mean that we need to know the size of the storage, i.e. the number of elements in the body of an identified struct, when we construct the storage, but we don't. It may remain unknown until we mutate the storage, at which point we cannot reallocate it anymore.

I considered having TrailingObjects<Storage, char, Type> for the key, but it creates a wrong impression that both the name and the (literal) type list can be present at the same time, and increases code complexity.

1927

I've been looking for the place where alignment is indicated, but failed to find it... Can you point me to it?

2260

Well, because I only need a stream in these functions and because some functions are reused with other streams (error reporting in parsing also calls these before the type is fully constructed). LLVM types do and likely will keep relying on closedness, otherwise, e.g., !llvm.ptr<i32> is ambiguous in pointing to standard or LLVM type.

Though I am happy to use a DialectAsmPrinter/Parser with a stack instead of rolling my own, we are already looking at 1300 LoC without comments, and I'm not even done here. When somebody gets to implement those things, I can consider moving this code to use them.

[rriddle]

mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp

1895

SGTM.

[ftynse]

more cmake

[rriddle]

Looks really great Alex! Made a first pass through, nothing really big mostly nits.

mlir/include/mlir/Dialect/LLVMIR/LLVMTypes.h

57

nit: The other enums in MLIR use CamelCase for elements.

159

Can you separate these class definitions with comment blocks?

//===-...-===//
//
//===-...-===//

190

nit: Checks -> Returns

195

Why have the duplicate method?

198

nit: Maybe add signless integer type

214

nit: of this integer type?

256

typos: prodiving and lits

258

nit: without a body

289

nit: Such a struct

290

nit: with a mutable body

297

nit: Set the body

433

nit: Can you set this to the same value as PointerLikeTypeTraits<mlir::Type>::NumLowBitsAvailable?

mlir/include/mlir/IR/DialectImplementation.h

329

nit: Can you add a one line comment here?

mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp

1799

Why was this removed?

mlir/lib/Dialect/LLVMIR/IR/LLVMTypes.cpp

49

Could we use llvm/ADT/BitFields here instead?

105

Can you move these to a TypeDetail header in this directory?

115

nit: whether the

133

nit: I think you could state - mutable (Identified structs only) which would avoid the need to state it for each point? Feel free to ignore, given that the current description matches the style immutable part.

193

Can you use the enum names instead of numbers here?

203

if (isIdentified())
  return other.isIdentified() && identifier.equals(...);
return !other.isIdentified() && other.isPacked() == ...;

?

227

nit: Prefer getFoo style getters and setters. Same applies below.

259

typo: unintilized

289

nit: Prefer early return here.

353

BumpPtrAllocator::Allocate<T> (used by copyInto) ensures address alignment for a given T. Are you wanting the char * key to have the same alignment as the Type *?

Also, what would be within the pointer union?

462

Please remove the ::mlir:: in this file.

629

Could you also move the printing/parsing to a different file?

894

Please add a comment here.

941

nit: Can you just capture the diagnostic as a variable, and then attach the note?

auto diag = parser.emitError(subtypesLoc) << ...;
diag.attachNote() << ...;

969

nit: Just return directly.

[ftynse]

Address review

[ftynse]

Try to appease MSVC

[ftynse]

Even more MSVC

[ftynse]

mlir/include/mlir/Dialect/LLVMIR/LLVMTypes.h

195

LLVM has it as params but that contradicts the usual MLIR style. I am fine either way.

258

Intentionality matters here. A struct can be created without a body with the intention of setting the body later, or with the intention of keeping it opaque. I referred to the latter as intentionally opaque, do you have a better name?

mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp

1799

code motion accident

mlir/lib/Dialect/LLVMIR/IR/LLVMTypes.cpp

49

Sure, thanks for mentioning this!

193

The "packed" flag is present in two enums and while it currently has the same value in both, it can change leading to subtle problems with hashing here, e.g., if it has the same value as identified. I can add named variables here instead.

353

BumpPtrAllocator::Allocate<T> (used by copyInto) ensures address alignment for a given T. Are you wanting the char * key to have the same alignment as the Type *?

I want at least one bit for the pointer union itself. If I get three bits, I can use the remaining bits for flags instead of stealing them from the size. But that may consume extra space, so I'm also fine with writing the casts myself.

Also, what would be within the pointer union?

The same thing as in keyPtr with type erasure: first element of the key.

969

debug leftover, sorry

[ftynse]

Use LLVMTypeNew inside struct storage for consistency with other storages

[rriddle]

mlir/lib/Dialect/LLVMIR/IR/LLVMTypeSyntax.cpp

1 ↗

(On Diff #281543)

Should we name this TypeParser instead? This would match the naming that the Quant dialect used.

mlir/lib/Dialect/LLVMIR/IR/LLVMTypes.cpp

193

I can add named variables here instead.

Ah, thanks for explaining. Named variables works for me.

353

I want at least one bit for the pointer union itself. If I get three bits, I can use the
remaining bits for flags instead of stealing them from the size. But that may consume
extra space, so I'm also fine with writing the casts myself.

Ah, we could add an alignment parameter to StorageAllocator::copyInto. We'd just need to reimplement what BumpPtrAllocator<T>::Allocate does(effectively just uses the type-erased Allocate and casts back to a T*) and allow for a new desired alignment. We'd just need to assert that the desired alignment is still valid for T.

[ftynse]

mlir/lib/Dialect/LLVMIR/IR/LLVMTypeSyntax.cpp

1 ↗

(On Diff #281543)

I considered that, but the file contains both parsing and printing so it felt incorrect to emphasize the parser. I can rename if you think it makes more sense.

mlir/lib/Dialect/LLVMIR/IR/LLVMTypes.cpp

353

Ah, we could add an alignment parameter to StorageAllocator::copyInto. We'd just need to reimplement what BumpPtrAllocator<T>::Allocate does(effectively just uses the type-erased Allocate and casts back to a T*) and allow for a new desired alignment. We'd just need to assert that the desired alignment is still valid for T.

I'll keep it as a more detailed TODO, it is unclear to me if we want to potentially waste additional memory for alignment just to remove a couple of casts when we pack bits into sizes in the same object.

[ftynse]

Rebase

mlir/include/mlir/Dialect/LLVMIR/LLVMTypes.h

+//===- LLVMDialect.h - MLIR LLVM dialec types -------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the types for the LLVM dialect in MLIR. These MLIR types
+// correspond to the LLVM IR type system.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef MLIR_DIALECT_LLVMIR_LLVMTYPES_H_
+#define MLIR_DIALECT_LLVMIR_LLVMTYPES_H_
+
+#include "mlir/IR/Types.h"
+
+namespace llvm {
+class ElementCount;
+}
+
+namespace mlir {
+
+class DialectAsmParser;
+class DialectAsmPrinter;
+
+namespace LLVM {
+namespace detail {
+struct LLVMFunctionTypeStorage;
+struct LLVMIntegerTypeStorage;
+struct LLVMPointerTypeStorage;
+struct LLVMStructTypeStorage;
+struct LLVMTypeAndSizeStorage;
+} // namespace detail
+
+/// Base class for LLVM dialect types.
+///
+/// The LLVM dialect in MLIR fully reflects the LLVM IR type system, prodiving a
+/// sperate MLIR type for each LLVM IR type. All types are represted as separate
+/// subclasses and are compatible with the isa/cast infrastructure. For
+/// convenience, the base class provides most of the APIs available on
+/// llvm::Type in addition to MLIR-compatible APIs.
+///
+/// The LLVM dialect type system is closed: parametric types can only refer to
+/// other LLVM dialect types. This is consistent with LLVM IR and enables a more
+/// concise pretty-printing format.
+///
+/// Similarly to other MLIR types, LLVM dialect types are owned by the MLIR
+/// context, have an immutable identifier (for most types except identified
+/// structs, the entire type is the identifier) and are thread-safe.
+class LLVMTypeNew : public Type {
+public:
+  enum Kind {
+    // Keep non-parametric types contiguous in the enum.
+    VOID_TYPE = FIRST_LLVM_TYPE + 1,
+    HALF_TYPE,
+    BFLOAT_TYPE,
+    FLOAT_TYPE,
+    DOUBLE_TYPE,
+    FP128_TYPE,
+    X86_FP80_TYPE,
+    PPC_FP128_TYPE,
+    X86_MMX_TYPE,
+    LABEL_TYPE,
+    TOKEN_TYPE,
+    METADATA_TYPE,
+    // End of non-parametric types.
+    FUNCTION_TYPE,
+    INTEGER_TYPE,
+    POINTER_TYPE,
+    FIXED_VECTOR_TYPE,
+    SCALABLE_VECTOR_TYPE,
+    ARRAY_TYPE,
+    STRUCT_TYPE,
+    FIRST_NEW_LLVM_TYPE = VOID_TYPE,
+    LAST_NEW_LLVM_TYPE = STRUCT_TYPE,
+    FIRST_TRIVIAL_TYPE = VOID_TYPE,
+    LAST_TRIVIAL_TYPE = METADATA_TYPE
+  };
+
+  /// Inherit base constructors.
+  using Type::Type;
+
+  /// Support for PointerLikeTypeTraits.
+  using Type::getAsOpaquePointer;
+  static LLVMTypeNew getFromOpaquePointer(const void *ptr) {
+    return LLVMTypeNew(static_cast<ImplType *>(const_cast<void *>(ptr)));
+  }
+
+  /// Support for isa/cast.
+  static bool kindof(unsigned kind) {
+    return FIRST_NEW_LLVM_TYPE <= kind && kind <= LAST_NEW_LLVM_TYPE;
+  }
+};
+
+/// Simple, non-parametric LLVM dialect type.
+template <typename Derived, unsigned Kind>
+class LLVMTrivialType
+    : public Type::TypeBase<Derived, LLVMTypeNew, TypeStorage> {
+public:
+  using Type::TypeBase<Derived, LLVMTypeNew, TypeStorage>::TypeBase;
+  using Base = LLVMTrivialType<Derived, Kind>;
+
+  static bool kindof(unsigned kind) { return kind == Kind; }
+
+  /// Get or create an instance of the LLVM dialect type in the given context.
+  static Derived get(MLIRContext *context) {
+    return Type::TypeBase<Derived, LLVMTypeNew, TypeStorage>::get(context,
+                                                                  Kind);
+  }
+};
+
+// Batch-define trivial types.
+#define DEFINE_TRIVIAL_LLVM_TYPE(ClassName, Kind)                              \
+  class ClassName : public LLVMTrivialType<ClassName, Kind> {                  \
+  public:                                                                      \
+    using Base::Base;                                                          \
+  }
+
+DEFINE_TRIVIAL_LLVM_TYPE(LLVMVoidType, LLVMTypeNew::VOID_TYPE);
+DEFINE_TRIVIAL_LLVM_TYPE(LLVMHalfType, LLVMTypeNew::HALF_TYPE);
+DEFINE_TRIVIAL_LLVM_TYPE(LLVMBFloatType, LLVMTypeNew::BFLOAT_TYPE);
+DEFINE_TRIVIAL_LLVM_TYPE(LLVMFloatType, LLVMTypeNew::FLOAT_TYPE);
+DEFINE_TRIVIAL_LLVM_TYPE(LLVMDoubleType, LLVMTypeNew::DOUBLE_TYPE);
+DEFINE_TRIVIAL_LLVM_TYPE(LLVMFP128Type, LLVMTypeNew::FP128_TYPE);
+DEFINE_TRIVIAL_LLVM_TYPE(LLVMX86FP80Type, LLVMTypeNew::X86_FP80_TYPE);
+DEFINE_TRIVIAL_LLVM_TYPE(LLVMPPCFP128Type, LLVMTypeNew::PPC_FP128_TYPE);
+DEFINE_TRIVIAL_LLVM_TYPE(LLVMX86MMXType, LLVMTypeNew::X86_MMX_TYPE);
+DEFINE_TRIVIAL_LLVM_TYPE(LLVMTokenType, LLVMTypeNew::TOKEN_TYPE);
+DEFINE_TRIVIAL_LLVM_TYPE(LLVMLabelType, LLVMTypeNew::LABEL_TYPE);
+DEFINE_TRIVIAL_LLVM_TYPE(LLVMMetadataType, LLVMTypeNew::METADATA_TYPE);
+
+#undef DEFINE_TRIVIAL_LLVM_TYPE
+
+/// LLVM dialect array type. It is an aggregate type representing consecutive
+/// elements in memory, parameterized by the number of elements and the element
+/// type.
+class LLVMArrayType : public Type::TypeBase<LLVMArrayType, LLVMTypeNew,
+                                            detail::LLVMTypeAndSizeStorage> {
+public:
+  /// Inherit base constructors.
+  using Base::Base;
+
+  /// Support for isa/cast.
+  static bool kindof(unsigned kind) { return kind == LLVMTypeNew::ARRAY_TYPE; }
+
+  /// Gets or creates an instance of LLVM dialect array type containing
+  /// `numElements` of `elementType`, in the same context as `elementType`.
+  static LLVMArrayType get(LLVMTypeNew elementType, unsigned numElements);
+
+  /// Returns the element type of the array.
+  LLVMTypeNew getElementType();
+
+  /// Returns the number of elements in the array type.
+  unsigned getNumElements();
+};
+
+/// LLVM dialect function type. It consists of a single return type (unlike MLIR
+/// which can have multiple), a list of parameter types and can optionally be
+/// variadic.
+class LLVMFunctionType
+    : public Type::TypeBase<LLVMFunctionType, LLVMTypeNew,
+                            detail::LLVMFunctionTypeStorage> {
+public:
+  /// Inherit base constructors.
+  using Base::Base;
+
+  /// Support for isa/cast.
+  static bool kindof(unsigned kind) {
+    return kind == LLVMTypeNew::FUNCTION_TYPE;
+  }
+
+  /// Gets or creates an instance of LLVM dialect function in the same context
+  /// as the `result` type.
+  static LLVMFunctionType get(LLVMTypeNew result,
+                              ArrayRef<LLVMTypeNew> arguments,
+                              bool isVarArg = false);
+
+  /// Returns the result type of the function.
+  LLVMTypeNew getReturnType();
+
+  /// Returns the number of arguments to the function.
+  unsigned getNumParams();
+
+  /// Returns `i`-th argument of the function. Asserts on out-of-bounds.
+  LLVMTypeNew getParamType(unsigned i);
+
+  /// Checks whether the function is variadic.
+  bool isVarArg();
+
+  /// Returns a list of argument types of the function.
+  ArrayRef<LLVMTypeNew> getParams();
+  ArrayRef<LLVMTypeNew> params() { return getParams(); }
+};
+
+/// LLVM dialect integer type parameterized by bitwidth.
+class LLVMIntegerType : public Type::TypeBase<LLVMIntegerType, LLVMTypeNew,
+                                              detail::LLVMIntegerTypeStorage> {
+public:
+  /// Inherit base constructor.
+  using Base::Base;
+
+  /// Support for isa/cast.
+  static bool kindof(unsigned kind) {
+    return kind == LLVMTypeNew::INTEGER_TYPE;
+  }
+
+  /// Gets or creates an instance of the integer of the specified `bitwidth` in
+  /// the given context.
+  static LLVMIntegerType get(MLIRContext *ctx, unsigned bitwidth);
+
+  /// Returns the bitwidth of an integer type.
+  unsigned getBitWidth();
+};
+
+/// LLVM dialect pointer type. This type typically represents a reference to an
+/// object in memory. It is parameterized by the element type and the address
+/// space.
+class LLVMPointerType : public Type::TypeBase<LLVMPointerType, LLVMTypeNew,
+                                              detail::LLVMPointerTypeStorage> {
+public:
+  /// Inherit base constructors.
+  using Base::Base;
+
+  /// Support for isa/cast.
+  static bool kindof(unsigned kind) {
+    return kind == LLVMTypeNew::POINTER_TYPE;
+  }
+
+  /// Gets or creates an instance of LLVM dialect pointer type pointing to an
+  /// object of `pointee` type in the given address space. The pointer type is
+  /// created in the same context as `pointee`.
+  static LLVMPointerType get(LLVMTypeNew pointee, unsigned addressSpace = 0);
+
+  /// Returns the pointed-to type.
+  LLVMTypeNew getElementType();
+
+  /// Returns the address space of the pointer.
+  unsigned getAddressSpace();
+};
+
+/// LLVM dialect structure type representing a collection of different-typed
+/// elements manipulated together. Structured can optionally be packed, meaning
+/// that their elements immediately follow each other in memory without
+/// accounting for potential alignment.
+///
+/// Structure types can be identified (named) or literal. Literal structures
+/// are uniquely represented by the list of types they contain and packedness.
+/// Literal structure types are immutable after construction.
+///
+/// Identified structures are uniquely represented by their name, a string. They
+/// have a mutable component, consisting of the list of types they contain,
+/// the packedness and the opacity bits. Identified structs can be created
+/// without prodiving the lits of element types, making them suitable to
+/// represent recursive, i.e. self-referring, structures. Identified structs
+/// without body are considered opaque. For such structs, one can set the body.
+/// Identified structs can be created as intentionally-opaque, implying that the
+/// caller does not intend to ever set the body (e.g. forward-declarations of
+/// structs from another module) and wants to disallow further modification of
+/// the body. For intentionally-opaque structs or non-opaque structs with the
+/// body, one is not allowed to set another body (however, one can set exactly
+/// the same body).
+///
+/// Note that the packedness of the struct takes place in uniquing of literal
+/// structs, but does not in uniquing of identified structs.
+class LLVMStructType : public Type::TypeBase<LLVMStructType, LLVMTypeNew,
+                                             detail::LLVMStructTypeStorage> {
+public:
+  /// Inherit base construtors.
+  using Base::Base;
+
+  /// Support for isa/cast.
+  static bool kindof(unsigned kind) { return kind == LLVMTypeNew::STRUCT_TYPE; }
+
+  /// Gets or creates an identified struct with the given name in the provided
+  /// context. Note that unlike llvm::StructType::create, this function will
+  /// _NOT_ rename a struct in case a struct with the same name already exists
+  /// in the context. Instead, it will just return the existing struct,
+  /// similarly to the rest of MLIR type ::get methods.
+  static LLVMStructType getIdentified(MLIRContext *context, StringRef name);
+
+  /// Gets or creates a literal struct with the given body in the provided
+  /// context.
+  static LLVMStructType getLiteral(MLIRContext *context, ArrayRef<Type> types,
+                                   bool isPacked = false);
+
+  /// Gets or creates an intentionally-opaque identified struct. Such struct
+  /// cannot have its body set. To create an opaque struct with mutable body,
+  /// use `getIdentified`. Note that unlike llvm::StructType::create, this
+  /// function will _NOT_ rename a struct in case a struct with the same name
+  /// already exists in the context. Instead, it will just return the existing
+  /// struct, similarly to the rest of MLIR type ::get methods.
+  static LLVMStructType getOpaque(StringRef name, MLIRContext *context);
+
+  /// Set a body of an identified struct. Returns failure if the body could not
+  /// be set, e.g. if the struct already has a body or if it was marked as
+  /// intentionally opaque. This might happen in a multi-threaded context when a
+  /// different thread modified the struct after it was created. Most callers
+  /// are likely to assert this always succeeds, but it is possible to implement
+  /// a local renaming scheme based on the result of this call.
+  LogicalResult setBody(ArrayRef<Type> types, bool isPacked);
+
+  /// Checks if a struct is packed.
+  bool isPacked();
+
+  /// Checks if a struct is identified.
+  bool isIdentified();
+
+  /// Checks if a struct is opaque.
+  bool isOpaque();
+
+  /// Returns the identifier of an identified struct.
+  StringRef identifier();
+
+  /// Returns the list of element types contained in a non-opaque struct.
+  ArrayRef<Type> getBody();
+};
+
+/// LLVM dialect vector type, represents a sequence of elements that can be
+/// processed as one, typically in SIMD context. This is a base class for fixed
+/// and scalable vectors.
+class LLVMVectorType : public LLVMTypeNew {
+public:
+  /// Inherit base constructor.
+  using LLVMTypeNew::LLVMTypeNew;
+
+  /// Support for isa/cast.
+  static bool kindof(unsigned kind) {
+    return kind == LLVMTypeNew::FIXED_VECTOR_TYPE ||
+           kind == LLVMTypeNew::SCALABLE_VECTOR_TYPE;
+  }
+
+  /// Returns the element type of the vector.
+  LLVMTypeNew getElementType();
+
+  /// Returns the number of elements in the vector.
+  llvm::ElementCount getElementCount();
+};
+
+/// LLVM dialect fixed vector type, represents a sequence of elements of known
+/// length that can be processed as one.
+class LLVMFixedVectorType
+    : public Type::TypeBase<LLVMFixedVectorType, LLVMVectorType,
+                            detail::LLVMTypeAndSizeStorage> {
+public:
+  /// Inherit base constructor.
+  using Base::Base;
+
+  /// Support for isa/cast.
+  static bool kindof(unsigned kind) {
+    return kind == LLVMTypeNew::FIXED_VECTOR_TYPE;
+  }
+
+  /// Gets or creates a fixed vector type containing `numElements` of
+  /// `elementType` in the same context as `elementType`.
+  static LLVMFixedVectorType get(LLVMTypeNew elementType, unsigned numElements);
+
+  /// Returns the number of elements in the fixed vector.
+  unsigned getNumElements();
+};
+
+/// LLVM dialect scalable vector type, represents a sequence of elements of
+/// unknown length that is known to be divisible by some constant. These
+/// elements can be processed as one in SIMD context.
+class LLVMScalableVectorType
+    : public Type::TypeBase<LLVMScalableVectorType, LLVMVectorType,
+                            detail::LLVMTypeAndSizeStorage> {
+public:
+  /// Inherit base constructor.
+  using Base::Base;
+
+  /// Support for isa/cast.
+  static bool kindof(unsigned kind) {
+    return kind == LLVMTypeNew::SCALABLE_VECTOR_TYPE;
+  }
+
+  /// Gets or creates a scalable vector type containing a non-zero multiple of
+  /// `minNumElements` of `elementType` in the same context as `elementType`.
+  static LLVMScalableVectorType get(LLVMTypeNew elementType,
+                                    unsigned minNumElements);
+
+  /// Returns the scaling factor of the number of elements in the vector. The
+  /// vector contains at least the resulting number of elements, or any non-zero
+  /// multiple of this number.
+  unsigned getMinNumElements();
+};
+
+namespace detail {
+/// Parses an LLVM dialect type.
+LLVMTypeNew parseType(DialectAsmParser &parser);
+
+/// Prints an LLVM Dialect type.
+void printType(LLVMTypeNew type, DialectAsmPrinter &printer);
+} // namespace detail
+
+} // namespace LLVM
+} // namespace mlir
+
+namespace llvm {
+
+// LLVMTypeNew instances hash just like pointers.
+template <>
+struct DenseMapInfo<mlir::LLVM::LLVMTypeNew> {
+  static mlir::LLVM::LLVMTypeNew getEmptyKey() {
+    void *pointer = llvm::DenseMapInfo<void *>::getEmptyKey();
+    return mlir::LLVM::LLVMTypeNew(
+        static_cast<mlir::LLVM::LLVMTypeNew::ImplType *>(pointer));
+  }
+  static mlir::LLVM::LLVMTypeNew getTombstoneKey() {
+    void *pointer = llvm::DenseMapInfo<void *>::getTombstoneKey();
+    return mlir::LLVM::LLVMTypeNew(
+        static_cast<mlir::LLVM::LLVMTypeNew::ImplType *>(pointer));
+  }
+  static unsigned getHashValue(mlir::LLVM::LLVMTypeNew val) {
+    return mlir::hash_value(val);
+  }
+  static bool isEqual(mlir::LLVM::LLVMTypeNew lhs,
+                      mlir::LLVM::LLVMTypeNew rhs) {
+    return lhs == rhs;
+  }
+};
+
+template <>
+struct PointerLikeTypeTraits<mlir::LLVM::LLVMTypeNew> {
+  static inline void *getAsVoidPointer(mlir::LLVM::LLVMTypeNew I) {
+    return const_cast<void *>(I.getAsOpaquePointer());
+  }
+  static inline mlir::LLVM::LLVMTypeNew getFromVoidPointer(void *P) {
+    return mlir::LLVM::LLVMTypeNew::getFromOpaquePointer(P);
+  }
+  static constexpr int NumLowBitsAvailable = 3;
+};
+
+} // namespace llvm
+
+#endif // MLIR_DIALECT_LLVMIR_LLVMTYPES_H_

mlir/include/mlir/IR/DialectImplementation.h

public:
   virtual ParseResult parseOptionalComma() = 0;
 
   /// Parse a `=` token.
   virtual ParseResult parseEqual() = 0;
 
   /// Parse a `=` token if present.
   virtual ParseResult parseOptionalEqual() = 0;
 
+  /// Parse a quoted string token if present.
+  virtual ParseResult parseOptionalString(StringRef *string) = 0;
+
   /// Parse a given keyword.
   ParseResult parseKeyword(StringRef keyword, const Twine &msg = "") {
     auto loc = getCurrentLocation();
     if (parseOptionalKeyword(keyword))
       return emitError(loc, "expected '") << keyword << "'" << msg;
     return success();
   }
 
template <typename TypeType> ParseResult parseType(TypeType &result) {
 
     // Check for the right kind of attribute.
     result = type.dyn_cast<TypeType>();
     if (!result)
       return emitError(loc, "invalid kind of type specified");
     return success();
   }
 
+  virtual OptionalParseResult parseOptionalType(Type &result) = 0;
+
   /// Parse a 'x' separated dimension list. This populates the dimension list,
   /// using -1 for the `?` dimensions if `allowDynamic` is set and errors out on
   /// `?` otherwise.
   ///
   ///   dimension-list ::= (dimension `x`)*
   ///   dimension ::= `?` | integer
   ///
   /// When `allowDynamic` is not set, this is used to parse:

mlir/lib/Dialect/LLVMIR/CMakeLists.txt

 add_subdirectory(Transforms)
 
 add_mlir_dialect_library(MLIRLLVMIR
   IR/LLVMDialect.cpp
+  IR/LLVMTypes.cpp
 
   ADDITIONAL_HEADER_DIRS
   ${MLIR_MAIN_INCLUDE_DIR}/mlir/Dialect/LLVMIR
 
   DEPENDS
   MLIRLLVMOpsIncGen
   MLIRLLVMConversionsIncGen
   intrinsics_gen

mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp

 #include "mlir/Dialect/LLVMIR/LLVMDialect.h"
 #include "mlir/IR/Builders.h"
 #include "mlir/IR/DialectImplementation.h"
 #include "mlir/IR/FunctionImplementation.h"
 #include "mlir/IR/MLIRContext.h"
 #include "mlir/IR/Module.h"
 #include "mlir/IR/StandardTypes.h"
 
+#include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/AsmParser/Parser.h"
 #include "llvm/Bitcode/BitcodeReader.h"
 #include "llvm/Bitcode/BitcodeWriter.h"
 #include "llvm/IR/Attributes.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/Type.h"
 #include "llvm/Support/Mutex.h"

 }
 
 //===----------------------------------------------------------------------===//
 // LLVMDialect initialization, type parsing, and registration.
 //===----------------------------------------------------------------------===//
 
 namespace mlir {
 namespace LLVM {
+
 namespace detail {
 struct LLVMDialectImpl {
   LLVMDialectImpl() : module("LLVMDialectModule", llvmContext) {}
 
   llvm::LLVMContext llvmContext;
   llvm::Module module;
 
   /// A set of LLVMTypes that are cached on construction to avoid any lookups or
return op->emitError()
            << "llvm.noalias argument attribute of non boolean type";
   // Check that llvm.align is an integer attribute.
   if (argAttr.first == "llvm.align" && !argAttr.second.isa<IntegerAttr>())
     return op->emitError()
            << "llvm.align argument attribute of non integer type";
   return success();
 }
 
-//===----------------------------------------------------------------------===//
-// LLVMType.
-//===----------------------------------------------------------------------===//
-
 namespace mlir {
 namespace LLVM {
 namespace detail {
 struct LLVMTypeStorage : public ::mlir::TypeStorage {
   LLVMTypeStorage(llvm::Type *ty) : underlyingType(ty) {}
 
   // LLVM types are pointer-unique.
   using KeyTy = llvm::Type *;
   bool operator==(const KeyTy &key) const { return key == underlyingType; }
 
   static LLVMTypeStorage *construct(TypeStorageAllocator &allocator,
                                     llvm::Type *ty) {
     return new (allocator.allocate<LLVMTypeStorage>()) LLVMTypeStorage(ty);
   }
 
   llvm::Type *underlyingType;
 };

 }
 bool LLVMType::isPointerTy() { return getUnderlyingType()->isPointerTy(); }
 
 /// Struct type utilities.
 LLVMType LLVMType::getStructElementType(unsigned i) {
   return get(getContext(), getUnderlyingType()->getStructElementType(i));
 }
 unsigned LLVMType::getStructNumElements() {
   return getUnderlyingType()->getStructNumElements();
 }
 bool LLVMType::isStructTy() { return getUnderlyingType()->isStructTy(); }
 
 /// Utilities used to generate floating point types.
 LLVMType LLVMType::getDoubleTy(LLVMDialect *dialect) {
   return dialect->impl->doubleTy;
 }
 LLVMType LLVMType::getFloatTy(LLVMDialect *dialect) {

 /// Utilities used to generate integer types.
 LLVMType LLVMType::getIntNTy(LLVMDialect *dialect, unsigned numBits) {
   switch (numBits) {
   case 1:
     return dialect->impl->int1Ty;
   case 8:
     return dialect->impl->int8Ty;
   case 16:
     return dialect->impl->int16Ty;
   case 32:
     return dialect->impl->int32Ty;
   case 64:
     return dialect->impl->int64Ty;
   case 128:
     return dialect->impl->int128Ty;
   default:
     break;
mlir::LLVM::cloneModuleIntoNewContext(llvm::LLVMContext *context,
   SmallVector<char, 1> buffer;
   {
     llvm::raw_svector_ostream os(buffer);
     WriteBitcodeToFile(*module, os);
   }
   llvm::MemoryBufferRef bufferRef(StringRef(buffer.data(), buffer.size()),
                                   "cloned module buffer");
   return cantFail(parseBitcodeFile(bufferRef, *context));
 }

mlir/lib/Dialect/LLVMIR/IR/LLVMTypes.cpp

+//===- LLVMTypes.cpp - MLIR LLVM Dialect types ----------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the types for the LLVM dialect in MLIR. These MLIR types
+// correspond to the LLVM IR type system.
+//
+//===----------------------------------------------------------------------===//
+
+#include "mlir/Dialect/LLVMIR/LLVMTypes.h"
+#include "mlir/IR/Builders.h"
+#include "mlir/IR/DialectImplementation.h"
+#include "mlir/IR/TypeSupport.h"
+
+#include "llvm/ADT/SetVector.h"
+#include "llvm/Support/TypeSize.h"
+
+using namespace mlir;
+using namespace mlir::LLVM;
+
+//===----------------------------------------------------------------------===//
+// Storage structures.
+//===----------------------------------------------------------------------===//
+
+namespace {
+
+/// Type traits to verify that all types match.
+template <typename Expected, typename Ty, typename... Tys>
+struct are_same {
+  constexpr static bool value =
+      std::is_same<Expected, Ty>::value && are_same<Expected, Tys...>::value;
+};
+template <typename Expected, typename Ty>
+struct are_same<Expected, Ty> {
+  constexpr static bool value = std::is_same<Expected, Ty>::value;
+};
+
+/// A simple container that uses `ReservedBits` lowest bits of `UnderlyingTy`
+/// integer type to store flags of `FlagTy` type. Since this is intended for
+/// storing flags, setter/getter functions are expecting binary flags (e.g. 0x1,
+/// 0x4) or masks (e.g. 0x1 | 0x4) rather than bit positions (e.g. 1, 3 like
+/// BitVector does). This uses low bits for flags to avoid the need for getting
+/// the bit width of `UnderlyingType`. In memory, this stores exactly one
+/// `UnderlyingTy` object.
+template <unsigned ReservedBits, typename FlagTy = unsigned,
+          typename UnderlyingTy = unsigned>
+class IntAndFlags {
+public:
+  /// Sets the given flags.
+  template <typename Arg, typename... Args>
+  void setFlags(Arg arg, Args... args) {
+    static_assert(are_same<FlagTy, Arg, Args...>::value, "incorrect flag type");
+    UnderlyingTy mask = flags(arg, args...);
+    assert(mask == keepBits(mask) &&
+           "bit mask contains values beyond the bit range");
+    data |= mask;
+  }
+
+  /// Resets all flags.
+  void resetFlags() { data &= ~kBitMask; }
+
+  /// Tests if the given flag is set.
+  bool testFlag(FlagTy flag) const {
+    return data & static_cast<UnderlyingTy>(flag);
+  }
+
+  /// Gets the integer value.
+  UnderlyingTy value() const { return data >> ReservedBits; }
+
+  /// Sets the integer value.
+  void setValue(UnderlyingTy value) {
+    // If this ever triggers, consider restituting the bits currently
+    // taken for flags and store the flags separately.
+    assert((value << ReservedBits) >> ReservedBits == value &&
+           "Value does not fit into IntAndFlags");
+    data = value << ReservedBits | keepBits(data);
+  }
+
+private:
+  /// Bit mask storing the lowest bits.
+  constexpr static UnderlyingTy kBitMask = (1u << ReservedBits) - 1;
+
+  /// Computes the mask by ORing the flags.
+  template <typename... Args>
+  static UnderlyingTy flags(Args... args) {
+    UnderlyingTy mask = 0;
+    for (auto a : {args...})
+      mask |= static_cast<UnderlyingTy>(a);
+    return mask;
+  }
+
+  /// Keeps the bits storing the flags in the given value.
+  static UnderlyingTy keepBits(UnderlyingTy value) { return value & kBitMask; }
+
+  /// Storage for the integer and the flags.
+  UnderlyingTy data = 0;
+};
+} // end namespace
+
+namespace mlir {
+namespace LLVM {
+namespace detail {
+/// Type storage for LLVM structure types.
+///
+/// Structures are uniqued using:
+/// - a bit indicating whether a struct is literal or identified;
+/// - for identified structs, in addition to the bit:
+///   - a string identifier;
+/// - for literal structs, in addition to the bit:
+///   - a list of contained types;
+///   - a bit indicating whether a literal struct is packed.
+///
+/// Identified structures only have a mutable component consisting of:
+///   - a list of contained types;
+///   - a bit indicating whether an identified struct is packed;
+///   - a bit indicating whether an identified struct is intentionally opaque;
+///   - a bit indicating whether an identified struct has been initialized.
+/// Uninitialized structs are considered opaque by the user, and can be mutated.
+/// Initialized and still opaque structs cannot be mutated.
+///
+/// The struct storage consists of:
+///   - immutable part:
+///     - a pointer to the first element of the key (character for identified
+///       structs, type for literal structs);
+///     - the number of elements in the key packed together with bits indicating
+///       whether a type is literal or identified, and the packedness bit for
+///       literal structs only;
+///   - mutable part:
+///     - a pointer to the first contained type for identified structs only;
+///     - the number of contained types packed together with bits of the mutable
+///       component, for identified structs only.
+struct LLVMStructTypeStorage : public ::mlir::TypeStorage {
+private:
+  /// Flags used in the key component.
+  enum class KeyFlags { Identified = 0x1, Packed = 0x2 };
+  /// Flags used in the mutable component.
+  enum class MutableFlags { Opaque = 0x1, Packed = 0x2, Initialized = 0x4 };
+
+public:
+  /// Construction/uniquing key class for LLVM dialect structure storage. Note
+  /// that this is a transient helper data structure that is NOT stored.
+  /// Therefore, it intentionally avoids bit manipulation and type erasure in
+  /// pointers to make manipulation more straightforward. Not all elements of
+  /// the key participate in uniquing, but all elements participate in
+  /// construction.
+  class Key {
+  public:
+    /// Constructs a key for an identified struct.
+    Key(StringRef name, bool opaque)
+        : name(name), identified(true), packed(false), opaque(opaque) {}
+    /// Constructs a key for a literal struct.
+    Key(ArrayRef<Type> types, bool packed)
+        : types(types), identified(false), packed(packed), opaque(false) {}
+
+    /// Checks a specific property of the struct.
+    bool isIdentified() const { return identified; }
+    bool isPacked() const {
+      assert(!isIdentified() &&
+             "'packed' bit is not part of the key for identified stucts");
+      return packed;
+    }
+    bool isOpaque() const {
+      assert(isIdentified() &&
+             "'opaque' bit is meaningless on literal structs");
+      return opaque;
+    }
+
+    /// Returns the identifier of a key for identified structs.
+    StringRef identifier() const {
+      assert(isIdentified() &&
+             "non-identified struct key canont have an identifier");
+      return name;
+    }
+
+    /// Returns the list of type contained in the key of a literal struct.
+    ArrayRef<Type> typelist() const {
+      assert(!isIdentified() &&
+             "identified struct key cannot have a type list");
+      return types;
+    }
+
+    /// Returns the hash value of the key. This combines various flags into a
+    /// single value: the identified flag sets the first bit, and the packedness
+    /// flag sets the second bit. Opacity bit is only used for construction and
+    /// does not participate in uniquing.
+    llvm::hash_code hashValue() const {
+      unsigned flags = 0;
+      if (isIdentified()) {
+        flags |= 1;
+        return llvm::hash_combine(flags, identifier());
+      }
+      if (isPacked())
+        flags |= 2;
+      return llvm::hash_combine(flags, typelist());
+    }
+
+    /// Compares two keys.
+    bool operator==(const Key &other) const {
+      if (isIdentified() ^ other.isIdentified())
+        return false;
+      if (isIdentified())
+        return other.identifier().equals(identifier());
+      return other.isPacked() == isPacked() && other.typelist() == typelist();
+    }
+
+    /// Copies dynamically-sized components of the key into the given allocator.
+    Key copyIntoAllocator(TypeStorageAllocator &allocator) const {
+      if (isIdentified())
+        return Key(allocator.copyInto(name), opaque);
+      return Key(allocator.copyInto(types), packed);
+    }
+
+  private:
+    ArrayRef<Type> types;
+    StringRef name;
+    bool identified;
+    bool packed;
+    bool opaque;
+  };
+  using KeyTy = Key;
+
+  /// Returns the string identifier of an identified struct.
+  StringRef identifier() const {
+    assert(isIdentified() && "requested identifier on a non-identified struct");
+    return StringRef(static_cast<const char *>(keyPtr), keySize());
+  }
+
+  /// Returns the list of types (partially) identifying a literal struct.
+  ArrayRef<Type> typelist() const {
+    // If this triggers, use identifiedStructBody() instead.
+    assert(!isIdentified() && "requested typelist on an identified struct");
+    return ArrayRef<Type>(static_cast<const Type *>(keyPtr), keySize());
+  }
+
+  /// Returns the list of types contained in an identified struct.
+  ArrayRef<Type> identifiedStructBody() const {
+    // If this triggers, use typelist() instead.
+    assert(isIdentified() &&
+           "requested struct body on a non-identified struct");
+    return ArrayRef<Type>(identifiedBodyArray, identifiedBodySize());
+  }
+
+  /// Checks whether the struct is identified.
+  bool isIdentified() const {
+    return keySizeAndFlags.testFlag(KeyFlags::Identified);
+  }
+
+  /// Checks whether the struct is packed (both literal and identified structs).
+  bool isPacked() const {
+    return isIdentified()
+               ? (identifiedBodySizeAndFlags.testFlag(MutableFlags::Packed))
+               : (keySizeAndFlags.testFlag(KeyFlags::Packed));
+  }
+
+  /// Checks whether a struct is marked as intentionally opaque (an unintilized
+  /// struct is also considered opaque by the user, call isInitialized to check
+  /// that).
+  bool isOpaque() const {
+    return identifiedBodySizeAndFlags.testFlag(MutableFlags::Opaque);
+  }
+
+  /// Checks whether an identified struct has been explicitly initialized either
+  /// by setting its body or by marking it as intentionally opaque.
+  bool isInitialized() const {
+    return identifiedBodySizeAndFlags.testFlag(MutableFlags::Initialized);
+  }
+
+  /// Constructs the storage from the given key. This sets up the uniquing key
+  /// components and optionally the mutable component if they construction key
+  /// has the relevant information. In the latter case, the struct is considered
+  /// as initalized and can no longer be mutated.
+  LLVMStructTypeStorage(const KeyTy &key) {
+    if (key.isIdentified()) {
+      StringRef name = key.identifier();
+      keyPtr = static_cast<const void *>(name.data());
+      setKeySize(name.size());
+      keySizeAndFlags.setFlags(KeyFlags::Identified);
+
+      // If the struct is being constructed directly as opaque, mark it as
+      // initialized.
+      if (key.isOpaque())
+        identifiedBodySizeAndFlags.setFlags(MutableFlags::Initialized,
+                                            MutableFlags::Opaque);
+    } else {
+      ArrayRef<Type> types = key.typelist();
+      keyPtr = static_cast<const void *>(types.data());
+      setKeySize(types.size());
+      if (key.isPacked())
+        keySizeAndFlags.setFlags(KeyFlags::Packed);
+    }
+  }
+
+  /// Hook into the type unquing infrastructure.
+  bool operator==(const KeyTy &other) const { return getKey() == other; };
+  static llvm::hash_code hashKey(const KeyTy &key) { return key.hashValue(); }
+  static LLVMStructTypeStorage *construct(TypeStorageAllocator &allocator,
+                                          const KeyTy &key) {
+    return new (allocator.allocate<LLVMStructTypeStorage>())
+        LLVMStructTypeStorage(key.copyIntoAllocator(allocator));
+  }
+
+  /// Sets the body of an identified struct. If the struct is already
+  /// initialized, succeeds only if the body is equal to the current body. Fails
+  /// if the struct is marked as intentionally opaque. The struct will be marked
+  /// as initialized as a result of this operation and can no longer be changed.
+  LogicalResult mutate(TypeStorageAllocator &allocator, ArrayRef<Type> body,
+                       bool packed) {
+    if (!isIdentified())
+      return failure();
+    if (isInitialized())
+      return success(!isOpaque() && body == identifiedStructBody() &&
+                     packed == isPacked());
+
+    identifiedBodySizeAndFlags.setFlags(MutableFlags::Initialized);
+    if (packed)
+      identifiedBodySizeAndFlags.setFlags(MutableFlags::Packed);
+
+    ArrayRef<Type> typesInAllocator = allocator.copyInto(body);
+    identifiedBodyArray = typesInAllocator.data();
+    setIdentifiedBodySize(typesInAllocator.size());
+
+    return success();
+  }
+
+private:
+  /// Returns the number of elements in the key.
+  unsigned keySize() const { return keySizeAndFlags.value(); }
+
+  /// Sets the number of elements in the key.
+  void setKeySize(unsigned value) { keySizeAndFlags.setValue(value); }
+
+  /// Returns the number of types contained in an identified struct.
+  unsigned identifiedBodySize() const {
+    return identifiedBodySizeAndFlags.value();
+  }
+  /// Sets the number of types contained in an identified struct.
+  void setIdentifiedBodySize(unsigned value) {
+    identifiedBodySizeAndFlags.setValue(value);
+  }
+
+  /// Returns the key for the current storage.
+  Key getKey() const {
+    if (isIdentified())
+      return Key(identifier(), isOpaque());
+    return Key(typelist(), isPacked());
+  }
+
+  /// Pointer to the first element of the uniquing key.
+  // Note: cannot use PointerUnion because bump-ptr allocator does not guarantee
+  // address alignment.
+  const void *keyPtr = nullptr;
+
+  /// Pointer to the first type contained in an identified struct.
+  const Type *identifiedBodyArray = nullptr;
+
+  /// Size of the uniquing key combined with identified/literal and
+  /// packedness bits.
+  IntAndFlags<2, KeyFlags> keySizeAndFlags;
+
+  /// Number of the types contained in an identified struct combined with
+  /// mutable flags.
+  IntAndFlags<3, MutableFlags> identifiedBodySizeAndFlags;
+};
+
+/// Type storage for LLVM dialect function types. These are uniqued using the
+/// list of types they contain and the vararg bit.
+struct LLVMFunctionTypeStorage : public ::mlir::TypeStorage {
+  using KeyTy = std::tuple<LLVMTypeNew, ArrayRef<LLVMTypeNew>, bool>;
+
+  /// Construct a storage from the given components. The list is expected to be
+  /// allocated in the context.
+  LLVMFunctionTypeStorage(LLVMTypeNew result, ArrayRef<LLVMTypeNew> arguments,
+                          bool variadic)
+      : argumentTypes(arguments) {
+    returnTypeAndVariadic.setPointerAndInt(result, variadic);
+  }
+
+  /// Hook into the type uniquing infrastructure.
+  static LLVMFunctionTypeStorage *construct(TypeStorageAllocator &allocator,
+                                            const KeyTy &key) {
+    return new (allocator.allocate<LLVMFunctionTypeStorage>())
+        LLVMFunctionTypeStorage(std::get<0>(key),
+                                allocator.copyInto(std::get<1>(key)),
+                                std::get<2>(key));
+  }
+
+  static unsigned hashKey(const KeyTy &key) {
+    // LLVM doesn't like hashing bools in tuples.
+    return llvm::hash_combine(std::get<0>(key), std::get<1>(key),
+                              static_cast<int>(std::get<2>(key)));
+  }
+
+  bool operator==(const KeyTy &key) const {
+    return std::make_tuple(getReturnType(), getArgumentTypes(), isVariadic()) ==
+           key;
+  }
+
+  /// Returns the list of function argument types.
+  ArrayRef<LLVMTypeNew> getArgumentTypes() const { return argumentTypes; }
+
+  /// Checks whether the function type is variadic.
+  bool isVariadic() const { return returnTypeAndVariadic.getInt(); }
+
+  /// Returns the function result type.
+  LLVMTypeNew getReturnType() const {
+    return returnTypeAndVariadic.getPointer();
+  }
+
+private:
+  /// Function result type packed with the variadic bit.
+  llvm::PointerIntPair<LLVMTypeNew, 1, bool> returnTypeAndVariadic;
+  /// Argument types.
+  ArrayRef<LLVMTypeNew> argumentTypes;
+};
+
+/// Storage type for LLVM dialect integer types. These are uniqued by bitwidth.
+struct LLVMIntegerTypeStorage : public ::mlir::TypeStorage {
+  using KeyTy = unsigned;
+
+  LLVMIntegerTypeStorage(unsigned width) : bitwidth(width) {}
+
+  static LLVMIntegerTypeStorage *construct(TypeStorageAllocator &allocator,
+                                           const KeyTy &key) {
+    return new (allocator.allocate<LLVMIntegerTypeStorage>())
+        LLVMIntegerTypeStorage(key);
+  }
+
+  bool operator==(const KeyTy &key) const { return key == bitwidth; }
+
+  unsigned bitwidth;
+};
+
+/// Storage type for LLVM dialect pointer types. These are uniqued by a pair of
+/// element type and address space.
+struct LLVMPointerTypeStorage : public ::mlir::TypeStorage {
+  using KeyTy = std::tuple<LLVMTypeNew, unsigned>;
+
+  LLVMPointerTypeStorage(const KeyTy &key)
+      : pointeeType(std::get<0>(key)), addressSpace(std::get<1>(key)) {}
+
+  static LLVMPointerTypeStorage *construct(TypeStorageAllocator &allocator,
+                                           const KeyTy &key) {
+    return new (allocator.allocate<LLVMPointerTypeStorage>())
+        LLVMPointerTypeStorage(key);
+  }
+
+  bool operator==(const KeyTy &key) const {
+    return std::make_tuple(pointeeType, addressSpace) == key;
+  }
+
+  LLVMTypeNew pointeeType;
+  unsigned addressSpace;
+};
+
+/// Common storage used for LLVM dialect types that need an element type and a
+/// number: arrays, fixed and scalable vectors. The actual semantics of the
+/// type is defined by its kind.
+struct LLVMTypeAndSizeStorage : public ::mlir::TypeStorage {
+  using KeyTy = std::tuple<LLVMTypeNew, unsigned>;
+
+  LLVMTypeAndSizeStorage(const KeyTy &key)
+      : elementType(std::get<0>(key)), numElements(std::get<1>(key)) {}
+
+  static LLVMTypeAndSizeStorage *construct(TypeStorageAllocator &allocator,
+                                           const KeyTy &key) {
+    return new (allocator.allocate<LLVMTypeAndSizeStorage>())
+        LLVMTypeAndSizeStorage(key);
+  }
+
+  bool operator==(const KeyTy &key) const {
+    return std::make_tuple(elementType, numElements) == key;
+  }
+
+  LLVMTypeNew elementType;
+  unsigned numElements;
+};
+
+} // end namespace detail
+} // end namespace LLVM
+} // end namespace mlir
+
+//===----------------------------------------------------------------------===//
+// Type definitions.
+//===----------------------------------------------------------------------===//
+
+//===----------------------------------------------------------------------===//
+// Array type.
+
+LLVMArrayType LLVMArrayType::get(LLVMTypeNew elementType,
+                                 unsigned numElements) {
+  assert(elementType && "expected non-null subtype");
+  return Base::get(elementType.getContext(), LLVMTypeNew::ARRAY_TYPE,
+                   elementType, numElements);
+}
+
+LLVMTypeNew LLVMArrayType::getElementType() { return getImpl()->elementType; }
+
+unsigned LLVMArrayType::getNumElements() { return getImpl()->numElements; }
+
+//===----------------------------------------------------------------------===//
+// Function type.
+
+LLVMFunctionType LLVMFunctionType::get(LLVMTypeNew result,
+                                       ArrayRef<LLVMTypeNew> arguments,
+                                       bool isVarArg) {
+  assert(result && "expected non-null result");
+  return Base::get(result.getContext(), LLVMTypeNew::FUNCTION_TYPE, result,
+                   arguments, isVarArg);
+}
+
+LLVMTypeNew LLVMFunctionType::getReturnType() {
+  return getImpl()->getReturnType();
+}
+
+unsigned LLVMFunctionType::getNumParams() {
+  return getImpl()->getArgumentTypes().size();
+}
+
+LLVMTypeNew LLVMFunctionType::getParamType(unsigned i) {
+  return getImpl()->getArgumentTypes()[i];
+}
+
+bool LLVMFunctionType::isVarArg() { return getImpl()->isVariadic(); }
+
+ArrayRef<LLVMTypeNew> LLVMFunctionType::getParams() {
+  return getImpl()->getArgumentTypes();
+}
+
+//===----------------------------------------------------------------------===//
+// Integer type.
+
+LLVMIntegerType LLVMIntegerType::get(MLIRContext *ctx, unsigned bitwidth) {
+  return Base::get(ctx, LLVMTypeNew::INTEGER_TYPE, bitwidth);
+}
+
+unsigned LLVMIntegerType::getBitWidth() { return getImpl()->bitwidth; }
+
+//===----------------------------------------------------------------------===//
+// Pointer type.
+
+LLVMPointerType LLVMPointerType::get(LLVMTypeNew pointee,
+                                     unsigned addressSpace) {
+  assert(pointee && "expected non-null subtype");
+  return Base::get(pointee.getContext(), LLVMTypeNew::POINTER_TYPE, pointee,
+                   addressSpace);
+}
+
+LLVMTypeNew LLVMPointerType::getElementType() { return getImpl()->pointeeType; }
+
+unsigned LLVMPointerType::getAddressSpace() { return getImpl()->addressSpace; }
+
+//===----------------------------------------------------------------------===//
+// Struct type.
+
+LLVMStructType LLVMStructType::getIdentified(MLIRContext *context,
+                                             StringRef name) {
+  return Base::get(context, LLVMTypeNew::STRUCT_TYPE, name, /*opaque=*/false);
+}
+
+LLVMStructType LLVMStructType::getLiteral(MLIRContext *context,
+                                          ArrayRef<Type> types, bool isPacked) {
+  return Base::get(context, LLVMTypeNew::STRUCT_TYPE, types, isPacked);
+}
+
+LLVMStructType LLVMStructType::getOpaque(StringRef name, MLIRContext *context) {
+  return Base::get(context, LLVMTypeNew::STRUCT_TYPE, name, /*opaque=*/true);
+}
+
+LogicalResult LLVMStructType::setBody(ArrayRef<Type> types, bool isPacked) {
+  assert(isIdentified() && "can only set bodies of identified structs");
+  return Base::mutate(types, isPacked);
+}
+
+bool LLVMStructType::isPacked() { return getImpl()->isPacked(); }
+bool LLVMStructType::isIdentified() { return getImpl()->isIdentified(); }
+bool LLVMStructType::isOpaque() {
+  return getImpl()->isOpaque() || !getImpl()->isInitialized();
+}
+StringRef LLVMStructType::identifier() { return getImpl()->identifier(); }
+ArrayRef<Type> LLVMStructType::getBody() {
+  return isIdentified() ? getImpl()->identifiedStructBody()
+                        : getImpl()->typelist();
+}
+
+//===----------------------------------------------------------------------===//
+// Vector types.
+
+LLVMTypeNew LLVMVectorType::getElementType() {
+  // Both derived classes share the implementation type.
+  return static_cast<detail::LLVMTypeAndSizeStorage *>(impl)->elementType;
+}
+
+llvm::ElementCount LLVMVectorType::getElementCount() {
+  // Both derived classes share the implementation type.
+  return llvm::ElementCount(
+      static_cast<detail::LLVMTypeAndSizeStorage *>(impl)->numElements,
+      this->isa<LLVMScalableVectorType>());
+}
+
+LLVMFixedVectorType LLVMFixedVectorType::get(LLVMTypeNew elementType,
+                                             unsigned numElements) {
+  assert(elementType && "expected non-null subtype");
+  return Base::get(elementType.getContext(), LLVMTypeNew::FIXED_VECTOR_TYPE,
+                   elementType, numElements)
+      .cast<LLVMFixedVectorType>();
+}
+
+unsigned LLVMFixedVectorType::getNumElements() {
+  return getImpl()->numElements;
+}
+
+LLVMScalableVectorType LLVMScalableVectorType::get(LLVMTypeNew elementType,
+                                                   unsigned minNumElements) {
+  assert(elementType && "expected non-null subtype");
+  return Base::get(elementType.getContext(), LLVMTypeNew::SCALABLE_VECTOR_TYPE,
+                   elementType, minNumElements)
+      .cast<LLVMScalableVectorType>();
+}
+
+unsigned LLVMScalableVectorType::getMinNumElements() {
+  return getImpl()->numElements;
+}
+
+//===----------------------------------------------------------------------===//
+// Printing.
+//===----------------------------------------------------------------------===//
+
+static void printTypeImpl(llvm::raw_ostream &os, LLVMTypeNew type,
+                          llvm::SetVector<StringRef> &stack);
+
+/// Returns the keyword to use for the given type.
+static StringRef getTypeKeyword(LLVMTypeNew type) {
+  switch (type.getKind()) {
+  case LLVMTypeNew::VOID_TYPE:
+    return "void";
+  case LLVMTypeNew::HALF_TYPE:
+    return "half";
+  case LLVMTypeNew::BFLOAT_TYPE:
+    return "bfloat";
+  case LLVMTypeNew::FLOAT_TYPE:
+    return "float";
+  case LLVMTypeNew::DOUBLE_TYPE:
+    return "double";
+  case LLVMTypeNew::FP128_TYPE:
+    return "fp128";
+  case LLVMTypeNew::X86_FP80_TYPE:
+    return "x86_fp80";
+  case LLVMTypeNew::PPC_FP128_TYPE:
+    return "ppc_fp128";
+  case LLVMTypeNew::X86_MMX_TYPE:
+    return "x86_mmx";
+  case LLVMTypeNew::TOKEN_TYPE:
+    return "token";
+  case LLVMTypeNew::LABEL_TYPE:
+    return "label";
+  case LLVMTypeNew::METADATA_TYPE:
+    return "metadata";
+  case LLVMTypeNew::FUNCTION_TYPE:
+    return "func";
+  case LLVMTypeNew::INTEGER_TYPE:
+    return "i";
+  case LLVMTypeNew::POINTER_TYPE:
+    return "ptr";
+  case LLVMTypeNew::FIXED_VECTOR_TYPE:
+  case LLVMTypeNew::SCALABLE_VECTOR_TYPE:
+    return "vec";
+  case LLVMTypeNew::ARRAY_TYPE:
+    return "array";
+  case LLVMTypeNew::STRUCT_TYPE:
+    return "struct";
+  }
+  llvm_unreachable("unhandled type kind");
+}
+
+/// Prints the body of a structure type. Uses `stack` to avoid printing
+/// recursive structs indefinitely.
+static void printStructTypeBody(llvm::raw_ostream &os, LLVMStructType type,
+                                llvm::SetVector<StringRef> &stack) {
+  if (type.isIdentified() && type.isOpaque()) {
+    os << "opaque";
+    return;
+  }
+
+  if (type.isPacked())
+    os << "packed ";
+
+  // Put the current type on stack to avoid infinite recursion.
+  os << '(';
+  if (type.isIdentified())
+    stack.insert(type.identifier());
+  llvm::interleaveComma(type.getBody(), os, [&](Type subtype) {
+    printTypeImpl(os, subtype.cast<LLVMTypeNew>(), stack);
+  });
+  if (type.isIdentified())
+    stack.pop_back();
+  os << ')';
+}
+
+/// Prints a structure type. Uses `stack` to keep track of the identifiers of
+/// the structs being printed. Checks if the identifier of a struct is contained
+/// in `stack`, i.e. whether a self-reference to a recursive stack is being
+/// printed, and only prints the name to avoid infinite recursion.
+static void printStructType(llvm::raw_ostream &os, LLVMStructType type,
+                            llvm::SetVector<StringRef> &stack) {
+  os << "<";
+  if (type.isIdentified()) {
+    os << '"' << type.identifier() << '"';
+    // If we are printing a reference to one of the enclosing structs, just
+    // print the name and stop to avoid infinitely long output.
+    if (stack.count(type.identifier())) {
+      os << '>';
+      return;
+    }
+    os << ", ";
+  }
+
+  printStructTypeBody(os, type, stack);
+  os << '>';
+}
+
+/// Prints a type containing a fixed number of elements.
+template <typename TypeTy>
+static void printArrayOrVectorType(llvm::raw_ostream &os, TypeTy type,
+                                   llvm::SetVector<StringRef> &stack) {
+  os << '<' << type.getNumElements() << " x ";
+  printTypeImpl(os, type.getElementType(), stack);
+  os << '>';
+}
+
+/// Prints a function type.
+static void printFunctionType(llvm::raw_ostream &os, LLVMFunctionType funcType,
+                              llvm::SetVector<StringRef> &stack) {
+  os << '<';
+  printTypeImpl(os, funcType.getReturnType(), stack);
+  os << " (";
+  llvm::interleaveComma(funcType.getParams(), os,
+                        [&os, &stack](LLVMTypeNew subtype) {
+                          printTypeImpl(os, subtype, stack);
+                        });
+  if (funcType.isVarArg()) {
+    if (funcType.getNumParams() != 0)
+      os << ", ";
+    os << "...";
+  }
+  os << ")>";
+}
+
+/// Prints the given LLVM dialect type recursively. This leverages closedness of
+/// the LLVM dialect type system to avoid printing the dialect prefix
+/// repeatedly. For recursive structures, only prints the name of the structure
+/// when printing a self-reference. Note that this does not apply to sibling
+/// references. For example,
+///   struct<"a", (ptr<struct<"a">>)>
+///   struct<"c", (ptr<struct<"b", (ptr<struct<"c">>)>>,
+///                ptr<struct<"b", (ptr<struct<"c">>)>>)>
+/// note that "b" is printed twice.
+static void printTypeImpl(llvm::raw_ostream &os, LLVMTypeNew type,
+                          llvm::SetVector<StringRef> &stack) {
+  if (!type) {
+    os << "<<NULL-TYPE>>";
+    return;
+  }
+
+  unsigned kind = type.getKind();
+  os << getTypeKeyword(type);
+
+  // Trivial types only consist of their keyword.
+  if (LLVMTypeNew::FIRST_TRIVIAL_TYPE <= kind &&
+      kind <= LLVMTypeNew::LAST_TRIVIAL_TYPE)
+    return;
+
+  if (auto intType = type.dyn_cast<LLVMIntegerType>()) {
+    os << intType.getBitWidth();
+    return;
+  }
+
+  if (auto ptrType = type.dyn_cast<LLVMPointerType>()) {
+    os << '<';
+    printTypeImpl(os, ptrType.getElementType(), stack);
+    if (ptrType.getAddressSpace() != 0)
+      os << ", " << ptrType.getAddressSpace();
+    os << '>';
+    return;
+  }
+
+  if (auto arrayType = type.dyn_cast<LLVMArrayType>())
+    return printArrayOrVectorType(os, arrayType, stack);
+  if (auto vectorType = type.dyn_cast<LLVMFixedVectorType>())
+    return printArrayOrVectorType(os, vectorType, stack);
+
+  if (auto vectorType = type.dyn_cast<LLVMScalableVectorType>()) {
+    os << "<? x " << vectorType.getMinNumElements() << " x ";
+    printTypeImpl(os, vectorType.getElementType(), stack);
+    os << '>';
+    return;
+  }
+
+  if (auto structType = type.dyn_cast<LLVMStructType>())
+    return printStructType(os, structType, stack);
+
+  printFunctionType(os, type.cast<LLVMFunctionType>(), stack);
+}
+
+void mlir::LLVM::detail::printType(LLVMTypeNew type,
+                                   DialectAsmPrinter &printer) {
+  llvm::SetVector<StringRef> stack;
+  return printTypeImpl(printer.getStream(), type, stack);
+}
+
+//===----------------------------------------------------------------------===//
+// Parsing.
+//===----------------------------------------------------------------------===//
+
+static LLVMTypeNew parseTypeImpl(DialectAsmParser &parser,
+                                 llvm::SetVector<StringRef> &stack);
+
+/// Helper to be chained with other parsing functions.
+static ParseResult parseTypeImpl(DialectAsmParser &parser,
+                                 llvm::SetVector<StringRef> &stack,
+                                 LLVMTypeNew &result) {
+  result = parseTypeImpl(parser, stack);
+  return success(result != nullptr);
+}
+
+/// Parses an LLVM dialect function type.
+///   llvm-type :: = `func<` llvm-type `(` llvm-type-list `...`? `)>`
+static LLVMFunctionType parseFunctionType(DialectAsmParser &parser,
+                                          llvm::SetVector<StringRef> &stack) {
+  LLVMTypeNew returnType;
+  if (parser.parseLess() || parseTypeImpl(parser, stack, returnType) ||
+      parser.parseLParen())
+    return LLVMFunctionType();
+
+  // Function type without arguments.
+  if (succeeded(parser.parseOptionalRParen())) {
+    if (succeeded(parser.parseGreater()))
+      return LLVMFunctionType::get(returnType, {}, /*isVarArg=*/false);
+    return LLVMFunctionType();
+  }
+
+  // Parse arguments.
+  SmallVector<LLVMTypeNew, 8> argTypes;
+  do {
+    if (succeeded(parser.parseOptionalEllipsis())) {
+      if (parser.parseOptionalRParen() || parser.parseOptionalGreater())
+        return LLVMFunctionType();
+      return LLVMFunctionType::get(returnType, argTypes, /*isVarArg=*/true);
+    }
+
+    argTypes.push_back(parseTypeImpl(parser, stack));
+    if (!argTypes.back())
+      return LLVMFunctionType();
+  } while (succeeded(parser.parseOptionalComma()));
+
+  if (parser.parseOptionalRParen() || parser.parseOptionalGreater())
+    return LLVMFunctionType();
+  return LLVMFunctionType::get(returnType, argTypes, /*isVarArg=*/false);
+}
+
+/// Parses an LLVM dialect pointer type.
+///   llvm-type ::= `ptr<` llvm-type (`,` integer)? `>`
+static LLVMPointerType parsePointerType(DialectAsmParser &parser,
+                                        llvm::SetVector<StringRef> &stack) {
+  LLVMTypeNew elementType;
+  if (parser.parseLess() || parseTypeImpl(parser, stack, elementType))
+    return LLVMPointerType();
+
+  unsigned addressSpace = 0;
+  if (succeeded(parser.parseOptionalComma()) &&
+      failed(parser.parseInteger(addressSpace)))
+    return LLVMPointerType();
+  if (failed(parser.parseGreater()))
+    return LLVMPointerType();
+  return LLVMPointerType::get(elementType, addressSpace);
+}
+
+/// Parses an LLVM dialect vector type.
+///   llvm-type ::= `vec<` `? x`? integer `x` llvm-type `>`
+/// Supports both fixed and scalable vectors.
+static LLVMVectorType parseVectorType(DialectAsmParser &parser,
+                                      llvm::SetVector<StringRef> &stack) {
+  SmallVector<int64_t, 2> dims;
+  llvm::SMLoc dimPos;
+  LLVMTypeNew elementType;
+  if (parser.parseLess() || parser.getCurrentLocation(&dimPos) ||
+      parser.parseDimensionList(dims, /*allowDynamic=*/true) ||
+      parseTypeImpl(parser, stack, elementType) || parser.parseGreater())
+    return LLVMVectorType();
+
+  if (dims.empty() || dims.size() > 2 || (dims.size() == 2 ^ dims[0] == -1) ||
+      (dims.size() == 2 && dims[1] == -1)) {
+    parser.emitError(dimPos)
+        << "expected '? x <integer> x <type>' or '<integer> x <type>'";
+    return LLVMVectorType();
+  }
+
+  bool isScalable = dims.size() == 2;
+  return isScalable ? static_cast<LLVMVectorType>(
+                          LLVMScalableVectorType::get(elementType, dims[1]))
+                    : LLVMFixedVectorType::get(elementType, dims[0]);
+}
+
+/// Parses an LLVM dialect array type.
+///   llvm-type ::= `array<` integer `x` llvm-type `>`
+static LLVMArrayType parseArrayType(DialectAsmParser &parser,
+                                    llvm::SetVector<StringRef> &stack) {
+  SmallVector<int64_t, 1> dims;
+  llvm::SMLoc sizePos;
+  LLVMTypeNew elementType;
+  if (parser.parseLess() || parser.getCurrentLocation(&sizePos) ||
+      parser.parseDimensionList(dims, /*allowDynamic=*/false) ||
+      parseTypeImpl(parser, stack, elementType) || parser.parseGreater())
+    return LLVMArrayType();
+
+  if (dims.size() != 1) {
+    parser.emitError(sizePos) << "expected ? x <type>";
+    return LLVMArrayType();
+  }
+
+  return LLVMArrayType::get(elementType, dims[0]);
+}
+
+/// Attempts to set the body of an identified structure type. Reports a parsing
+/// error at `subtypesLoc` in case of failure, uses `stack` to make sure the
+/// types printed in the error message look like they did when parsed.
+static LLVMStructType trySetStructBody(LLVMStructType type,
+                                       ArrayRef<Type> subtypes, bool isPacked,
+                                       DialectAsmParser &parser,
+                                       llvm::SMLoc subtypesLoc,
+                                       llvm::SetVector<StringRef> &stack) {
+  if (succeeded(type.setBody(subtypes, isPacked)))
+    return type;
+
+  std::string currentBody;
+  llvm::raw_string_ostream currentBodyStream(currentBody);
+  printStructTypeBody(currentBodyStream, type, stack);
+  (parser.emitError(subtypesLoc)
+   << "identified type already used with a different body")
+          .attachNote()
+      << "existing body: " << currentBodyStream.str();
+  return LLVMStructType();
+}
+
+/// Parses an LLVM dialect structure type.
+///   llvm-type ::= `struct<` (string-literal `,`)? `packed`?
+///                 `(` llvm-type-list `)` `>`
+///               | `struct<` string-literal `>`
+///               | `struct<` string-literal `, opaque>`
+static LLVMStructType parseStructType(DialectAsmParser &parser,
+                                      llvm::SetVector<StringRef> &stack) {
+  MLIRContext *ctx = parser.getBuilder().getContext();
+
+  if (failed(parser.parseLess()))
+    return LLVMStructType();
+
+  // If we are parsing a self-reference to a recursive struct, i.e. the parsing
+  // stack already contains a struct with the same identifier, bail out after
+  // the name.
+  StringRef name;
+  bool isIdentified = succeeded(parser.parseOptionalString(&name));
+  if (isIdentified) {
+    if (stack.count(name)) {
+      if (failed(parser.parseGreater()))
+        return LLVMStructType();
+      auto t = LLVMStructType::getIdentified(ctx, name);
+      return t;
+    }
+    if (failed(parser.parseComma()))
+      return LLVMStructType();
+  }
+
+  // Handle intentionally opaque structs.
+  llvm::SMLoc kwLoc = parser.getCurrentLocation();
+  if (succeeded(parser.parseOptionalKeyword("opaque"))) {
+    if (!isIdentified)
+      return parser.emitError(kwLoc, "only identified structs can be opaque"),
+             LLVMStructType();
+    if (failed(parser.parseGreater()))
+      return LLVMStructType();
+    auto type = LLVMStructType::getOpaque(name, ctx);
+    if (!type.isOpaque()) {
+      parser.emitError(kwLoc, "redeclaring defined struct as opaque");
+      return LLVMStructType();
+    }
+    return type;
+  }
+
+  // Check for packedness.
+  bool isPacked = succeeded(parser.parseOptionalKeyword("packed"));
+  if (failed(parser.parseLParen()))
+    return LLVMStructType();
+
+  // Fast pass for structs with zero subtypes.
+  if (succeeded(parser.parseOptionalRParen())) {
+    if (failed(parser.parseGreater()))
+      return LLVMStructType();
+    if (!isIdentified)
+      return LLVMStructType::getLiteral(ctx, {}, isPacked);
+    auto type = LLVMStructType::getIdentified(ctx, name);
+    return trySetStructBody(type, {}, isPacked, parser, kwLoc, stack);
+  }
+
+  // Parse subtypes. For identified structs, put the identifier of the struct on
+  // the stack to support self-references in the recursive calls.
+  SmallVector<Type, 4> subtypes;
+  llvm::SMLoc subtypesLoc = parser.getCurrentLocation();
+  do {
+    if (isIdentified)
+      stack.insert(name);
+    Type type = parseTypeImpl(parser, stack);
+    if (!type)
+      return LLVMStructType();
+    subtypes.push_back(type);
+    if (isIdentified)
+      stack.pop_back();
+  } while (succeeded(parser.parseOptionalComma()));
+
+  if (parser.parseRParen() || parser.parseGreater())
+    return LLVMStructType();
+
+  // Construct the struct with body.
+  if (!isIdentified)
+    return LLVMStructType::getLiteral(ctx, subtypes, isPacked);
+  auto type = LLVMStructType::getIdentified(ctx, name);
+  return trySetStructBody(type, subtypes, isPacked, parser, subtypesLoc, stack);
+}
+
+/// Parses one of the LLVM dialect types.
+static LLVMTypeNew parseTypeImpl(DialectAsmParser &parser,
+                                 llvm::SetVector<StringRef> &stack) {
+  // Special case for integers (i[1-9][0-9]*) that are literals rather than
+  // keywords for the parser, so they are not caught by the main dispatch below.
+  // Try parsing it a built-in integer type instead.
+  Type maybeIntegerType;
+  MLIRContext *ctx = parser.getBuilder().getContext();
+  llvm::SMLoc keyLoc = parser.getCurrentLocation();
+  OptionalParseResult result = parser.parseOptionalType(maybeIntegerType);
+  if (result.hasValue()) {
+    if (failed(*result))
+      return LLVMTypeNew();
+
+    if (!maybeIntegerType.isSignlessInteger()) {
+      parser.emitError(keyLoc) << "unexpected type, expected i* or keyword";
+      return LLVMTypeNew();
+    }
+    return LLVMIntegerType::get(ctx, maybeIntegerType.getIntOrFloatBitWidth());
+  }
+
+  // Dispatch to concrete functions.
+  StringRef key;
+  if (failed(parser.parseKeyword(&key)))
+    return LLVMTypeNew();
+
+  return llvm::StringSwitch<function_ref<LLVMTypeNew()>>(key)
+      .Case("void", [&] { return LLVMVoidType::get(ctx); })
+      .Case("half", [&] { return LLVMHalfType::get(ctx); })
+      .Case("bfloat", [&] { return LLVMBFloatType::get(ctx); })
+      .Case("float", [&] { return LLVMFloatType::get(ctx); })
+      .Case("double", [&] { return LLVMDoubleType::get(ctx); })
+      .Case("fp128", [&] { return LLVMFP128Type::get(ctx); })
+      .Case("x86_fp80", [&] { return LLVMX86FP80Type::get(ctx); })
+      .Case("ppc_fp128", [&] { return LLVMPPCFP128Type::get(ctx); })
+      .Case("x86_mmx", [&] { return LLVMX86MMXType::get(ctx); })
+      .Case("token", [&] { return LLVMTokenType::get(ctx); })
+      .Case("label", [&] { return LLVMLabelType::get(ctx); })
+      .Case("metadata", [&] { return LLVMMetadataType::get(ctx); })
+      .Case("func", [&] { return parseFunctionType(parser, stack); })
+      .Case("ptr", [&] { return parsePointerType(parser, stack); })
+      .Case("vec", [&] { return parseVectorType(parser, stack); })
+      .Case("array", [&] { return parseArrayType(parser, stack); })
+      .Case("struct", [&] { return parseStructType(parser, stack); })
+      .Default([&] {
+        parser.emitError(keyLoc) << "unknown LLVM type: " << key;
+        return LLVMTypeNew();
+      })();
+}
+
+LLVMTypeNew mlir::LLVM::detail::parseType(DialectAsmParser &parser) {
+  llvm::SetVector<StringRef> stack;
+  return parseTypeImpl(parser, stack);
+}

mlir/lib/Parser/DialectSymbolParser.cpp

ParseResult parseOptionalQuestion() override {
     return success(parser.consumeIf(Token::question));
   }
 
   /// Parses a '*' if present.
   ParseResult parseOptionalStar() override {
     return success(parser.consumeIf(Token::star));
   }
 
+  /// Parses a quoted string token if present.
+  ParseResult parseOptionalString(StringRef *string) override {
+    if (!parser.getToken().is(Token::string))
+      return failure();
+
+    if (string)
+      *string = parser.getTokenSpelling().drop_front().drop_back();
+    parser.consumeToken();
+    return success();
+  }
+
   /// Returns if the current token corresponds to a keyword.
   bool isCurrentTokenAKeyword() const {
     return parser.getToken().is(Token::bare_identifier) ||
            parser.getToken().isKeyword();
   }
 
   /// Parse the given keyword if present.
   ParseResult parseOptionalKeyword(StringRef keyword) override {
ParseResult parseType(Type &result) override {
     return success(static_cast<bool>(result));
   }
 
   ParseResult parseDimensionList(SmallVectorImpl<int64_t> &dimensions,
                                  bool allowDynamic) override {
     return parser.parseDimensionListRanked(dimensions, allowDynamic);
   }
 
+  OptionalParseResult parseOptionalType(Type &result) override {
+    return parser.parseOptionalType(result);
+  }
+
 private:
   /// The full symbol specification.
   StringRef fullSpec;
 
   /// The source location of the dialect symbol.
   SMLoc nameLoc;
 
   /// The main parser.

mlir/test/Dialect/LLVMIR/types-invalid.mlir

+// RUN: mlir-opt --allow-unregistered-dialect -split-input-file -verify-diagnostics %s
+
+func @repeated_struct_name() {
+  "some.op"() : () -> !llvm2.struct<"a", (ptr<struct<"a">>)>
+  // expected-error @+2 {{identified type already used with a different body}}
+  // expected-note @+1 {{existing body: (ptr<struct<"a">>)}}
+  "some.op"() : () -> !llvm2.struct<"a", (i32)>
+}
+
+// -----
+
+func @repeated_struct_name_packed() {
+  "some.op"() : () -> !llvm2.struct<"a", packed (i32)>
+  // expected-error @+2 {{identified type already used with a different body}}
+  // expected-note @+1 {{existing body: packed (i32)}}
+  "some.op"() : () -> !llvm2.struct<"a", (i32)>
+}
+
+// -----
+
+func @repeated_struct_opaque() {
+  "some.op"() : () -> !llvm2.struct<"a", opaque>
+  // expected-error @+2 {{identified type already used with a different body}}
+  // expected-note @+1 {{existing body: opaque}}
+  "some.op"() : () -> !llvm2.struct<"a", ()>
+}
+
+// -----
+
+func @repeated_struct_opaque_non_empty() {
+  "some.op"() : () -> !llvm2.struct<"a", opaque>
+  // expected-error @+2 {{identified type already used with a different body}}
+  // expected-note @+1 {{existing body: opaque}}
+  "some.op"() : () -> !llvm2.struct<"a", (i32, i32)>
+}
+
+// -----
+
+func @repeated_struct_opaque_redefinition() {
+  "some.op"() : () -> !llvm2.struct<"a", ()>
+  // expected-error @+1 {{redeclaring defined struct as opaque}}
+  "some.op"() : () -> !llvm2.struct<"a", opaque>
+}
+
+// -----
+
+func @struct_literal_opaque() {
+  // expected-error @+1 {{only identified structs can be opaque}}
+  "some.op"() : () -> !llvm2.struct<opaque>
+}
+
+// -----
+
+func @unexpected_type() {
+  // expected-error @+1 {{unexpected type, expected i* or keyword}}
+  "some.op"() : () -> !llvm2.f32
+}
+
+// -----
+
+func @unexpected_type() {
+  // expected-error @+1 {{unknown LLVM type}}
+  "some.op"() : () -> !llvm2.ifoo
+}
+
+// -----
+
+func @explicitly_opaque_struct() {
+  "some.op"() : () -> !llvm2.struct<"a", opaque>
+  // expected-error @+2 {{identified type already used with a different body}}
+  // expected-note @+1 {{existing body: opaque}}
+  "some.op"() : () -> !llvm2.struct<"a", ()>
+}
+
+// -----
+
+func @dynamic_vector() {
+  // expected-error @+1 {{expected '? x <integer> x <type>' or '<integer> x <type>'}}
+  "some.op"() : () -> !llvm2.vec<? x float>
+}
+
+// -----
+
+func @dynamic_scalable_vector() {
+  // expected-error @+1 {{expected '? x <integer> x <type>' or '<integer> x <type>'}}
+  "some.op"() : () -> !llvm2.vec<? x ? x float>
+}
+
+// -----
+
+func @unscalable_vector() {
+  // expected-error @+1 {{expected '? x <integer> x <type>' or '<integer> x <type>'}}
+  "some.op"() : () -> !llvm2.vec<4 x 4 x i32>
+}
+

mlir/test/Dialect/LLVMIR/types.mlir

+// RUN: mlir-opt -allow-unregistered-dialect %s -split-input-file | mlir-opt -allow-unregistered-dialect | FileCheck %s
+
+// CHECK-LABEL: @primitive
+func @primitive() {
+  // CHECK: !llvm2.void
+  "some.op"() : () -> !llvm2.void
+  // CHECK: !llvm2.half
+  "some.op"() : () -> !llvm2.half
+  // CHECK: !llvm2.bfloat
+  "some.op"() : () -> !llvm2.bfloat
+  // CHECK: !llvm2.float
+  "some.op"() : () -> !llvm2.float
+  // CHECK: !llvm2.double
+  "some.op"() : () -> !llvm2.double
+  // CHECK: !llvm2.fp128
+  "some.op"() : () -> !llvm2.fp128
+  // CHECK: !llvm2.x86_fp80
+  "some.op"() : () -> !llvm2.x86_fp80
+  // CHECK: !llvm2.ppc_fp128
+  "some.op"() : () -> !llvm2.ppc_fp128
+  // CHECK: !llvm2.x86_mmx
+  "some.op"() : () -> !llvm2.x86_mmx
+  // CHECK: !llvm2.token
+  "some.op"() : () -> !llvm2.token
+  // CHECK: !llvm2.label
+  "some.op"() : () -> !llvm2.label
+  // CHECK: !llvm2.metadata
+  "some.op"() : () -> !llvm2.metadata
+  return
+}
+
+// CHECK-LABEL: @func
+func @func() {
+  // CHECK: !llvm2.func<void ()>
+  "some.op"() : () -> !llvm2.func<void ()>
+  // CHECK: !llvm2.func<void (i32)>
+  "some.op"() : () -> !llvm2.func<void (i32)>
+  // CHECK: !llvm2.func<i32 ()>
+  "some.op"() : () -> !llvm2.func<i32 ()>
+  // CHECK: !llvm2.func<i32 (half, bfloat, float, double)>
+  "some.op"() : () -> !llvm2.func<i32 (half, bfloat, float, double)>
+  // CHECK: !llvm2.func<i32 (i32, i32)>
+  "some.op"() : () -> !llvm2.func<i32 (i32, i32)>
+  // CHECK: !llvm2.func<void (...)>
+  "some.op"() : () -> !llvm2.func<void (...)>
+  // CHECK: !llvm2.func<void (i32, i32, ...)>
+  "some.op"() : () -> !llvm2.func<void (i32, i32, ...)>
+  return
+}
+
+// CHECK-LABEL: @integer
+func @integer() {
+  // CHECK: !llvm2.i1
+  "some.op"() : () -> !llvm2.i1
+  // CHECK: !llvm2.i8
+  "some.op"() : () -> !llvm2.i8
+  // CHECK: !llvm2.i16
+  "some.op"() : () -> !llvm2.i16
+  // CHECK: !llvm2.i32
+  "some.op"() : () -> !llvm2.i32
+  // CHECK: !llvm2.i64
+  "some.op"() : () -> !llvm2.i64
+  // CHECK: !llvm2.i57
+  "some.op"() : () -> !llvm2.i57
+  // CHECK: !llvm2.i129
+  "some.op"() : () -> !llvm2.i129
+  return
+}
+
+// CHECK-LABEL: @ptr
+func @ptr() {
+  // CHECK: !llvm2.ptr<i8>
+  "some.op"() : () -> !llvm2.ptr<i8>
+  // CHECK: !llvm2.ptr<float>
+  "some.op"() : () -> !llvm2.ptr<float>
+  // CHECK: !llvm2.ptr<ptr<i8>>
+  "some.op"() : () -> !llvm2.ptr<ptr<i8>>
+  // CHECK: !llvm2.ptr<ptr<ptr<ptr<ptr<i8>>>>>
+  "some.op"() : () -> !llvm2.ptr<ptr<ptr<ptr<ptr<i8>>>>>
+  // CHECK: !llvm2.ptr<i8>
+  "some.op"() : () -> !llvm2.ptr<i8, 0>
+  // CHECK: !llvm2.ptr<i8, 1>
+  "some.op"() : () -> !llvm2.ptr<i8, 1>
+  // CHECK: !llvm2.ptr<i8, 42>
+  "some.op"() : () -> !llvm2.ptr<i8, 42>
+  // CHECK: !llvm2.ptr<ptr<i8, 42>, 9>
+  "some.op"() : () -> !llvm2.ptr<ptr<i8, 42>, 9>
+  return
+}
+
+// CHECK-LABEL: @vec
+func @vec() {
+  // CHECK: !llvm2.vec<4 x i32>
+  "some.op"() : () -> !llvm2.vec<4 x i32>
+  // CHECK: !llvm2.vec<4 x float>
+  "some.op"() : () -> !llvm2.vec<4 x float>
+  // CHECK: !llvm2.vec<? x 4 x i32>
+  "some.op"() : () -> !llvm2.vec<? x 4 x i32>
+  // CHECK: !llvm2.vec<? x 8 x half>
+  "some.op"() : () -> !llvm2.vec<? x 8 x half>
+  // CHECK: !llvm2.vec<4 x ptr<i8>>
+  "some.op"() : () -> !llvm2.vec<4 x ptr<i8>>
+  return
+}
+
+// CHECK-LABEL: @array
+func @array() {
+  // CHECK: !llvm2.array<10 x i32>
+  "some.op"() : () -> !llvm2.array<10 x i32>
+  // CHECK: !llvm2.array<8 x float>
+  "some.op"() : () -> !llvm2.array<8 x float>
+  // CHECK: !llvm2.array<10 x ptr<i32, 4>>
+  "some.op"() : () -> !llvm2.array<10 x ptr<i32, 4>>
+  // CHECK: !llvm2.array<10 x array<4 x float>>
+  "some.op"() : () -> !llvm2.array<10 x array<4 x float>>
+  return
+}
+
+// CHECK-LABEL: @literal_struct
+func @literal_struct() {
+  // CHECK: !llvm2.struct<()>
+  "some.op"() : () -> !llvm2.struct<()>
+  // CHECK: !llvm2.struct<(i32)>
+  "some.op"() : () -> !llvm2.struct<(i32)>
+  // CHECK: !llvm2.struct<(float, i32)>
+  "some.op"() : () -> !llvm2.struct<(float, i32)>
+  // CHECK: !llvm2.struct<(struct<(i32)>)>
+  "some.op"() : () -> !llvm2.struct<(struct<(i32)>)>
+  // CHECK: !llvm2.struct<(i32, struct<(i32)>, float)>
+  "some.op"() : () -> !llvm2.struct<(i32, struct<(i32)>, float)>
+
+  // CHECK: !llvm2.struct<packed ()>
+  "some.op"() : () -> !llvm2.struct<packed ()>
+  // CHECK: !llvm2.struct<packed (i32)>
+  "some.op"() : () -> !llvm2.struct<packed (i32)>
+  // CHECK: !llvm2.struct<packed (float, i32)>
+  "some.op"() : () -> !llvm2.struct<packed (float, i32)>
+  // CHECK: !llvm2.struct<packed (float, i32)>
+  "some.op"() : () -> !llvm2.struct<packed (float, i32)>
+  // CHECK: !llvm2.struct<packed (struct<(i32)>)>
+  "some.op"() : () -> !llvm2.struct<packed (struct<(i32)>)>
+  // CHECK: !llvm2.struct<packed (i32, struct<(i32, i1)>, float)>
+  "some.op"() : () -> !llvm2.struct<packed (i32, struct<(i32, i1)>, float)>
+
+  // CHECK: !llvm2.struct<(struct<packed (i32)>)>
+  "some.op"() : () -> !llvm2.struct<(struct<packed (i32)>)>
+  // CHECK: !llvm2.struct<packed (struct<(i32)>)>
+  "some.op"() : () -> !llvm2.struct<packed (struct<(i32)>)>
+  return
+}
+
+// CHECK-LABEL: @identified_struct
+func @identified_struct() {
+  // CHECK: !llvm2.struct<"empty", ()>
+  "some.op"() : () -> !llvm2.struct<"empty", ()>
+  // CHECK: !llvm2.struct<"opaque", opaque>
+  "some.op"() : () -> !llvm2.struct<"opaque", opaque>
+  // CHECK: !llvm2.struct<"long", (i32, struct<(i32, i1)>, float, ptr<func<void ()>>)>
+  "some.op"() : () -> !llvm2.struct<"long", (i32, struct<(i32, i1)>, float, ptr<func<void ()>>)>
+  // CHECK: !llvm2.struct<"self-recursive", (ptr<struct<"self-recursive">>)>
+  "some.op"() : () -> !llvm2.struct<"self-recursive", (ptr<struct<"self-recursive">>)>
+  // CHECK: !llvm2.struct<"unpacked", (i32)>
+  "some.op"() : () -> !llvm2.struct<"unpacked", (i32)>
+  // CHECK: !llvm2.struct<"packed", packed (i32)>
+  "some.op"() : () -> !llvm2.struct<"packed", packed (i32)>
+  // CHECK: !llvm2.struct<"name with spaces and !^$@$#", packed (i32)>
+  "some.op"() : () -> !llvm2.struct<"name with spaces and !^$@$#", packed (i32)>
+
+  // CHECK: !llvm2.struct<"mutually-a", (ptr<struct<"mutually-b", (ptr<struct<"mutually-a">, 3>)>>)>
+  "some.op"() : () -> !llvm2.struct<"mutually-a", (ptr<struct<"mutually-b", (ptr<struct<"mutually-a">, 3>)>>)>
+  // CHECK: !llvm2.struct<"mutually-b", (ptr<struct<"mutually-a", (ptr<struct<"mutually-b">>)>, 3>)>
+  "some.op"() : () -> !llvm2.struct<"mutually-b", (ptr<struct<"mutually-a", (ptr<struct<"mutually-b">>)>, 3>)>
+  // CHECK: !llvm2.struct<"referring-another", (ptr<struct<"unpacked", (i32)>>)>
+  "some.op"() : () -> !llvm2.struct<"referring-another", (ptr<struct<"unpacked", (i32)>>)>
+
+  // CHECK: !llvm2.struct<"struct-of-arrays", (array<10 x i32>)>
+  "some.op"() : () -> !llvm2.struct<"struct-of-arrays", (array<10 x i32>)>
+  // CHECK: !llvm2.array<10 x struct<"array-of-structs", (i32)>>
+  "some.op"() : () -> !llvm2.array<10 x struct<"array-of-structs", (i32)>>
+  // CHECK: !llvm2.ptr<struct<"ptr-to-struct", (i8)>>
+  "some.op"() : () -> !llvm2.ptr<struct<"ptr-to-struct", (i8)>>
+  return
+}
+

mlir/test/lib/Dialect/CMakeLists.txt

 add_subdirectory(Affine)
+add_subdirectory(LLVMIR)
 add_subdirectory(SPIRV)
 add_subdirectory(Test)

mlir/test/lib/Dialect/LLVMIR/CMakeLists.txt

+
+add_mlir_library(MLIRLLVMTypeTestDialect
+  LLVMTypeTestDialect.cpp
+
+  EXCLUDE_FROM_LIBMLIR
+
+  LINK_COMPONENTS
+  Core
+
+  LINK_LIBS PUBLIC
+  MLIRDialect
+  MLIRIR
+  MLIRLLVMIR
+  )

mlir/test/lib/Dialect/LLVMIR/LLVMTypeTestDialect.cpp

+#ifndef DIALECT_LLVMIR_LLVMTYPETESTDIALECT_H_
+#define DIALECT_LLVMIR_LLVMTYPETESTDIALECT_H_
+
+#include "mlir/Dialect/LLVMIR/LLVMTypes.h"
+#include "mlir/IR/Dialect.h"
+
+namespace mlir {
+namespace LLVM {
+namespace {
+class LLVMDialectNewTypes : public Dialect {
+public:
+  LLVMDialectNewTypes(MLIRContext *ctx) : Dialect(getDialectNamespace(), ctx) {
+    // clang-format off
+    addTypes<LLVMVoidType,
+             LLVMHalfType,
+             LLVMBFloatType,
+             LLVMFloatType,
+             LLVMDoubleType,
+             LLVMFP128Type,
+             LLVMX86FP80Type,
+             LLVMPPCFP128Type,
+             LLVMX86MMXType,
+             LLVMTokenType,
+             LLVMLabelType,
+             LLVMMetadataType,
+             LLVMFunctionType,
+             LLVMIntegerType,
+             LLVMPointerType,
+             LLVMFixedVectorType,
+             LLVMScalableVectorType,
+             LLVMArrayType,
+             LLVMStructType>();
+    // clang-format on
+  }
+  static StringRef getDialectNamespace() { return "llvm2"; }
+
+  Type parseType(DialectAsmParser &parser) const override {
+    return detail::parseType(parser);
+  }
+  void printType(Type type, DialectAsmPrinter &printer) const override {
+    detail::printType(type.cast<LLVMTypeNew>(), printer);
+  }
+};
+} // namespace
+} // namespace LLVM
+
+void registerLLVMTypeTestDialect() {
+  mlir::registerDialect<LLVM::LLVMDialectNewTypes>();
+}
+} // namespace mlir
+
+#endif // DIALECT_LLVMIR_LLVMTYPETESTDIALECT_H_

mlir/tools/mlir-opt/CMakeLists.txt

 set(LLVM_OPTIONAL_SOURCES
   null.cpp
 )
 
 get_property(dialect_libs GLOBAL PROPERTY MLIR_DIALECT_LIBS)
 get_property(conversion_libs GLOBAL PROPERTY MLIR_CONVERSION_LIBS)
 set(LLVM_LINK_COMPONENTS
   Core
   Support
   AsmParser
   )
 
 if(MLIR_INCLUDE_TESTS)
   set(test_libs
     MLIRAffineTransformsTestPasses
+    MLIRLLVMTypeTestDialect
     MLIRSPIRVTestPasses
     MLIRTestDialect
     MLIRTestIR
     MLIRTestPass
     MLIRTestReducer
     MLIRTestTransforms
     )
 endif()

mlir/tools/mlir-opt/mlir-opt.cpp

 
 using namespace llvm;
 using namespace mlir;
 
 namespace mlir {
 // Defined in the test directory, no public header.
 void registerConvertToTargetEnvPass();
 void registerInliner();
+void registerLLVMTypeTestDialect();
 void registerMemRefBoundCheck();
 void registerPassManagerTestPass();
 void registerPatternsTestPass();
 void registerPrintOpAvailabilityPass();
 void registerSideEffectTestPasses();
 void registerSimpleParametricTilingPass();
 void registerSymbolTestPasses();
 void registerTestAffineDataCopyPass();
-void registerTestAllReduceLoweringPass();
 void registerTestAffineLoopUnswitchingPass();
+void registerTestAllReduceLoweringPass();
 void registerTestBufferPlacementPreparationPass();
-void registerTestLoopPermutationPass();
 void registerTestCallGraphPass();
 void registerTestConstantFold();
 void registerTestConvertGPUKernelToCubinPass();
 void registerTestConvertGPUKernelToHsacoPass();
 void registerTestDominancePass();
 void registerTestExpandTanhPass();
 void registerTestFunc();
 void registerTestGpuMemoryPromotionPass();
+void registerTestGpuParallelLoopMappingPass();
 void registerTestInterfaces();
 void registerTestLinalgHoisting();
 void registerTestLinalgTransforms();
 void registerTestLivenessPass();
 void registerTestLoopFusion();
 void registerTestLoopMappingPass();
+void registerTestLoopPermutationPass();
 void registerTestLoopUnrollingPass();
 void registerTestMatchers();
 void registerTestMemRefDependenceCheck();
 void registerTestMemRefStrideCalculation();
 void registerTestOpaqueLoc();
 void registerTestPreparationPassWithAllowedMemrefResults();
 void registerTestRecursiveTypesPass();
 void registerTestReducer();
-void registerTestGpuParallelLoopMappingPass();
 void registerTestSCFUtilsPass();
 void registerTestVectorConversions();
 void registerVectorizerTestPass();
 } // namespace mlir
 
 static cl::opt<std::string>
     inputFilename(cl::Positional, cl::desc("<input file>"), cl::init("-"));
 

 static cl::opt<bool> allowUnregisteredDialects(
     "allow-unregistered-dialect",
     cl::desc("Allow operation with no registered dialects"), cl::init(false));
 
 #ifdef MLIR_INCLUDE_TESTS
 void registerTestPasses() {
   registerConvertToTargetEnvPass();
   registerInliner();
+  registerLLVMTypeTestDialect();
   registerMemRefBoundCheck();
   registerPassManagerTestPass();
   registerPatternsTestPass();
   registerPrintOpAvailabilityPass();
   registerSideEffectTestPasses();
   registerSimpleParametricTilingPass();
   registerSymbolTestPasses();
   registerTestAffineDataCopyPass();