[mlir][spirv] Support querying type extension/capability requirements

[antiagainst]

Summary

Previously we only consider the version/capability/extension requirements
on ops themselves. Some types in SPIR-V also require special extensions
or capabilities to be used. For example, non-32-bit integers/floats
will require different capabilities and/or extensions depending on
where they are used because it may mean special hardware abilities.

This commit adds query methods to SPIR-V type class hierarchy to support
querying extensions and capabilities. We don't go through ODS for
auto-generating such information given that we don't have them in
SPIR-V machine readable grammar and there are just a few types.

Depends On D75874

[mravishankar]

This is really great. I see there is a lot of complexity involved in deciding the extensions and capability, and storage class, etc. Wondering if most of the logic could be put in a single place for all types. So instead of querying the type to get the extension/capability info, have a single method that has all the logic...

[mravishankar]

Just making sure that this is still being worked on, and there are updates coming (the earlier comment doesnt seem to addressed, so wondering if I missed something)

[antiagainst]

In D75875#1915667, @mravishankar wrote:

This is really great. I see there is a lot of complexity involved in deciding the extensions and capability, and storage class, etc. Wondering if most of the logic could be put in a single place for all types. So instead of querying the type to get the extension/capability info, have a single method that has all the logic...

You can have availability information on many things in SPIR-V, including types, ops, and enum cases, and these information are available from SPIR-V's human-readable grammar. So it's quite suitable for auto-generation. The way it works right now is we generate utility functions for each enum to return its requirements on version/extension/capabilities and also auto-generate the methods for ops to synthesize the availability info (note that for an op, the opcode itself has availability constraints, but it should also consider the enum attributes it has. Types are a bit different because we don't have the information readily available in the grammar. We can probably include that in the grammar too but it seems fine for now to manually write the C++ code given there are just a few types.

Hope the above clarifies things. I plan to write it down in the doc afterwards. Putting in a single place means we will have a gigantic method and it involves recursively calling into itself and goes through switch table all the time, which I don't think is a good practice.

[antiagainst]

In D75875#1917741, @mravishankar wrote:

Just making sure that this is still being worked on, and there are updates coming (the earlier comment doesnt seem to addressed, so wondering if I missed something)

Yep; still working on this chain of CLs. For now this one should be good for the batch; you can hold for reviews on next CL, which will need more changes to make sense. Sorry for the delay in addressing the comments. :)

[mravishankar]

Just a few nits. Nice to see everything threaded through!

mlir/include/mlir/Dialect/SPIRV/SPIRVTypes.h

276

THis is a nice addition!

mlir/lib/Dialect/SPIRV/SPIRVTypes.cpp

583

So input/output cant be 8 bit?

mlir/lib/Dialect/SPIRV/Transforms/UpdateVCEPass.cpp

75

This and the above method are the same. Could just template this to reduce bloat

[rriddle]

mlir/include/mlir/Dialect/SPIRV/SPIRVTypes.h

291

typo: cconstructors

mlir/lib/Dialect/SPIRV/Transforms/UpdateVCEPass.cpp

58

nit: Return the error directly.

60

nit: I don't think the join is actually necessary.

92

Same here.

[antiagainst]

mlir/lib/Dialect/SPIRV/SPIRVTypes.cpp

583

No. SPV_KHR_8bit_storage does not support 8-bit on Input/Output. Input/Output is not useful for compute pipeline where you can have only one compute shader. It's more for graphics pipeline where you've many shader stages and they pass data from one to another with Input/Output.

mlir/lib/Dialect/SPIRV/Transforms/UpdateVCEPass.cpp

60

Hmm, I'm seeing compilation errors if missing it.

75

I've tried too. But we don't have a templated version of stringifyEnum<EnumClass> like what we have for symbolizeEnum<EnumClass>. I guess it's not really worth it for just two enum classes.

mlir/include/mlir/Dialect/SPIRV/SPIRVBase.td

 // dialect-specific types so we use "Any" here.
 def SPV_AnyPtr : Type<SPV_IsPtrType, "any SPIR-V pointer type">;
 def SPV_AnyArray : Type<SPV_IsArrayType, "any SPIR-V array type">;
 def SPV_AnyRTArray : Type<SPV_IsRTArrayType, "any SPIR-V runtime array type">;
 def SPV_AnyStruct : Type<SPV_IsStructType, "any SPIR-V struct type">;
 
 def SPV_Numerical : AnyTypeOf<[SPV_Integer, SPV_Float]>;
 def SPV_Scalar : AnyTypeOf<[SPV_Numerical, SPV_Bool]>;
-def SPV_Aggregate : AnyTypeOf<[SPV_AnyArray, SPV_AnyStruct]>;
+def SPV_Aggregate : AnyTypeOf<[SPV_AnyArray, SPV_AnyRTArray, SPV_AnyStruct]>;
 def SPV_Composite :
     AnyTypeOf<[SPV_Vector, SPV_AnyArray, SPV_AnyRTArray, SPV_AnyStruct]>;
 def SPV_Type : AnyTypeOf<[
     SPV_Void, SPV_Bool, SPV_Integer, SPV_Float, SPV_Vector,
     SPV_AnyPtr, SPV_AnyArray, SPV_AnyRTArray, SPV_AnyStruct
   ]>;
 
 def SPV_SignlessOrUnsignedInt : SignlessOrUnsignedIntOfWidths<[8, 16, 32, 64]>;

mlir/include/mlir/Dialect/SPIRV/SPIRVTypes.h

enum Kind {
   Image,
   Pointer,
   RuntimeArray,
   Struct,
   LAST_SPIRV_TYPE = Struct,
 };
 }
 
-// SPIR-V composite type: VectorType, SPIR-V ArrayType, or SPIR-V StructType.
-class CompositeType : public Type {
+// Base SPIR-V type for providing availability queries.
+class SPIRVType : public Type {
 public:
   using Type::Type;
 
   static bool classof(Type type);
 
+  /// The extension requirements for each type are following the
+  /// ((Extension::A OR Extension::B) AND (Extension::C OR Extension::D))
+  /// convention.
+  using ExtensionArrayRefVector = SmallVectorImpl<ArrayRef<spirv::Extension>>;
+
+  /// Appends to `extensions` the extensions needed for this type to appear in
+  /// the given `storage` class. This method does not guarantee the uniqueness
+  /// of extensions; the same extension may be appended multiple times.
+  void getExtensions(ExtensionArrayRefVector &extensions,
+                     Optional<spirv::StorageClass> storage = llvm::None);
+
+  /// The capability requirements for each type are following the
+  /// ((Capability::A OR Extension::B) AND (Capability::C OR Capability::D))
+  /// convention.
+  using CapabilityArrayRefVector = SmallVectorImpl<ArrayRef<spirv::Capability>>;
+
+  /// Appends to `capabilities` the capabilities needed for this type to appear
+  /// in the given `storage` class. This method does not guarantee the
+  /// uniqueness of capabilities; the same capability may be appended multiple
+  /// times.
+  void getCapabilities(CapabilityArrayRefVector &capabilities,
+                       Optional<spirv::StorageClass> storage = llvm::None);
+};
+
+// SPIR-V scalar type: bool type, integer type, floating point type.
+class ScalarType : public SPIRVType {
+public:
+  using SPIRVType::SPIRVType;
+
+  static bool classof(Type type);
+
+  void getExtensions(SPIRVType::ExtensionArrayRefVector &extensions,
+                     Optional<spirv::StorageClass> storage = llvm::None);
+  void getCapabilities(SPIRVType::CapabilityArrayRefVector &capabilities,
+                       Optional<spirv::StorageClass> storage = llvm::None);
+};
+
+// SPIR-V composite type: VectorType, SPIR-V ArrayType, or SPIR-V StructType.
+class CompositeType : public SPIRVType {
+public:
+  using SPIRVType::SPIRVType;
+
+  static bool classof(Type type);
+
   unsigned getNumElements() const;
 
   Type getElementType(unsigned) const;
+
+  void getExtensions(SPIRVType::ExtensionArrayRefVector &extensions,
+                     Optional<spirv::StorageClass> storage = llvm::None);
+  void getCapabilities(SPIRVType::CapabilityArrayRefVector &capabilities,
+                       Optional<spirv::StorageClass> storage = llvm::None);
 };
 
 // SPIR-V array type
 class ArrayType : public Type::TypeBase<ArrayType, CompositeType,
                                         detail::ArrayTypeStorage> {
 public:
   using Base::Base;
   // Zero layout specifies that is no layout
   using LayoutInfo = uint64_t;
 
   static bool kindof(unsigned kind) { return kind == TypeKind::Array; }
 
   static ArrayType get(Type elementType, unsigned elementCount);
 
   static ArrayType get(Type elementType, unsigned elementCount,
                        LayoutInfo layoutInfo);
 
   unsigned getNumElements() const;
 
   Type getElementType() const;
 
   bool hasLayout() const;
 
   uint64_t getArrayStride() const;
+
+  void getExtensions(SPIRVType::ExtensionArrayRefVector &extensions,
+                     Optional<spirv::StorageClass> storage = llvm::None);
+  void getCapabilities(SPIRVType::CapabilityArrayRefVector &capabilities,
+                       Optional<spirv::StorageClass> storage = llvm::None);
 };
 
 // SPIR-V image type
 class ImageType
-    : public Type::TypeBase<ImageType, Type, detail::ImageTypeStorage> {
+    : public Type::TypeBase<ImageType, SPIRVType, detail::ImageTypeStorage> {
 public:
   using Base::Base;
 
   static bool kindof(unsigned kind) { return kind == TypeKind::Image; }
 
   static ImageType
   get(Type elementType, Dim dim,
       ImageDepthInfo depth = ImageDepthInfo::DepthUnknown,
public:
   Type getElementType() const;
   Dim getDim() const;
   ImageDepthInfo getDepthInfo() const;
   ImageArrayedInfo getArrayedInfo() const;
   ImageSamplingInfo getSamplingInfo() const;
   ImageSamplerUseInfo getSamplerUseInfo() const;
   ImageFormat getImageFormat() const;
   // TODO(ravishankarm): Add support for Access qualifier
+
+  void getExtensions(SPIRVType::ExtensionArrayRefVector &extensions,
+                     Optional<spirv::StorageClass> storage = llvm::None);
+  void getCapabilities(SPIRVType::CapabilityArrayRefVector &capabilities,
+                       Optional<spirv::StorageClass> storage = llvm::None);
 };
 
 // SPIR-V pointer type
-class PointerType
-    : public Type::TypeBase<PointerType, Type, detail::PointerTypeStorage> {
+class PointerType : public Type::TypeBase<PointerType, SPIRVType,
+                                          detail::PointerTypeStorage> {
 public:
   using Base::Base;
 
   static bool kindof(unsigned kind) { return kind == TypeKind::Pointer; }
 
   static PointerType get(Type pointeeType, StorageClass storageClass);
 
   Type getPointeeType() const;
 
   StorageClass getStorageClass() const;
+
+  void getExtensions(SPIRVType::ExtensionArrayRefVector &extensions,
+                     Optional<spirv::StorageClass> storage = llvm::None);
+  void getCapabilities(SPIRVType::CapabilityArrayRefVector &capabilities,
+                       Optional<spirv::StorageClass> storage = llvm::None);
 };
 
 // SPIR-V run-time array type
 class RuntimeArrayType
-    : public Type::TypeBase<RuntimeArrayType, Type,
+    : public Type::TypeBase<RuntimeArrayType, SPIRVType,
                             detail::RuntimeArrayTypeStorage> {
 public:
   using Base::Base;
 
   static bool kindof(unsigned kind) { return kind == TypeKind::RuntimeArray; }
 
   static RuntimeArrayType get(Type elementType);
 
   Type getElementType() const;
+
+  void getExtensions(SPIRVType::ExtensionArrayRefVector &extensions,
+                     Optional<spirv::StorageClass> storage = llvm::None);
+  void getCapabilities(SPIRVType::CapabilityArrayRefVector &capabilities,
+                       Optional<spirv::StorageClass> storage = llvm::None);
 };
 
 // SPIR-V struct type
 class StructType : public Type::TypeBase<StructType, CompositeType,
                                          detail::StructTypeStorage> {
 public:
   using Base::Base;
 
public:
 
   /// Construct a struct with no members.
   static StructType getEmpty(MLIRContext *context);
 
   unsigned getNumElements() const;
 
   Type getElementType(unsigned) const;
 
+  /// Range class for element types.
+  class ElementTypeRange
+      : public ::mlir::detail::indexed_accessor_range_base<
+            ElementTypeRange, const Type *, Type, Type, Type> {
+  private:
+    using RangeBaseT::RangeBaseT;
+
+    /// See `mlir::detail::indexed_accessor_range_base` for details.
+    static const Type *offset_base(const Type *object, ptrdiff_t index) {
+      return object + index;
+    }
+    /// See `mlir::detail::indexed_accessor_range_base` for details.
+    static Type dereference_iterator(const Type *object, ptrdiff_t index) {
+      return object[index];
+    }
+
+    /// Allow StructType class access to cconstructors.
+    friend class ElementTypeRange;
+
+    /// Allow base class access to `offset_base` and `dereference_iterator`.
+    friend RangeBaseT;
+  };
+
+  ElementTypeRange getElementTypes() const;
+
   bool hasLayout() const;
 
   uint64_t getOffset(unsigned) const;
 
   // Returns in `allMemberDecorations` the spirv::Decorations (apart from
   // Offset) associated with all members of the StructType.
   void getMemberDecorations(SmallVectorImpl<StructType::MemberDecorationInfo>
                                 &allMemberDecorations) const;
 
   // Returns in `memberDecorations` all the spirv::Decorations (apart from
   // Offset) associated with the `i`-th member of the StructType.
   void getMemberDecorations(
       unsigned i, SmallVectorImpl<spirv::Decoration> &memberDecorations) const;
+
+  void getExtensions(SPIRVType::ExtensionArrayRefVector &extensions,
+                     Optional<spirv::StorageClass> storage = llvm::None);
+  void getCapabilities(SPIRVType::CapabilityArrayRefVector &capabilities,
+                       Optional<spirv::StorageClass> storage = llvm::None);
 };
 
 } // end namespace spirv
 } // end namespace mlir
 
 #endif // MLIR_DIALECT_SPIRV_SPIRVTYPES_H_

mlir/lib/Dialect/SPIRV/SPIRVTypes.cpp

Extension::SPV_KHR_8bit_storage, Extension::SPV_EXT_descriptor_indexing,     \
       Extension::SPV_EXT_physical_storage_buffer,                              \
       Extension::SPV_KHR_physical_storage_buffer,                              \
       Extension::SPV_KHR_vulkan_memory_model
 
   switch (version) {
   default:
     return {};
   case Version::V_1_3: {
+    // The following manual ArrayRef constructor call is to satisfy GCC 5.
     static const Extension exts[] = {V_1_3_IMPLIED_EXTS};
     return ArrayRef<Extension>(exts, llvm::array_lengthof(exts));
   }
   case Version::V_1_4: {
     static const Extension exts[] = {V_1_3_IMPLIED_EXTS, V_1_4_IMPLIED_EXTS};
     return ArrayRef<Extension>(exts, llvm::array_lengthof(exts));
   }
   case Version::V_1_5: {

 
 Type ArrayType::getElementType() const { return getImpl()->elementType; }
 
 // ArrayStride must be greater than zero
 bool ArrayType::hasLayout() const { return getImpl()->layoutInfo; }
 
 uint64_t ArrayType::getArrayStride() const { return getImpl()->layoutInfo; }
 
+void ArrayType::getExtensions(SPIRVType::ExtensionArrayRefVector &extensions,
+                              Optional<StorageClass> storage) {
+  getElementType().cast<SPIRVType>().getExtensions(extensions, storage);
+}
+
+void ArrayType::getCapabilities(
+    SPIRVType::CapabilityArrayRefVector &capabilities,
+    Optional<StorageClass> storage) {
+  getElementType().cast<SPIRVType>().getCapabilities(capabilities, storage);
+}
+
 //===----------------------------------------------------------------------===//
 // CompositeType
 //===----------------------------------------------------------------------===//
 
 bool CompositeType::classof(Type type) {
   switch (type.getKind()) {
   case TypeKind::Array:
   case TypeKind::RuntimeArray:
case spirv::TypeKind::Struct:
     return cast<StructType>().getNumElements();
   case StandardTypes::Vector:
     return cast<VectorType>().getNumElements();
   default:
     llvm_unreachable("invalid composite type");
   }
 }
 
+void CompositeType::getExtensions(
+    SPIRVType::ExtensionArrayRefVector &extensions,
+    Optional<StorageClass> storage) {
+  switch (getKind()) {
+  case spirv::TypeKind::Array:
+    cast<ArrayType>().getExtensions(extensions, storage);
+    break;
+  case spirv::TypeKind::RuntimeArray:
+    cast<ArrayType>().getExtensions(extensions, storage);
+    break;
+  case spirv::TypeKind::Struct:
+    cast<StructType>().getExtensions(extensions, storage);
+    break;
+  case StandardTypes::Vector:
+    cast<VectorType>().getElementType().cast<ScalarType>().getExtensions(
+        extensions, storage);
+    break;
+  default:
+    llvm_unreachable("invalid composite type");
+  }
+}
+
+void CompositeType::getCapabilities(
+    SPIRVType::CapabilityArrayRefVector &capabilities,
+    Optional<StorageClass> storage) {
+  switch (getKind()) {
+  case spirv::TypeKind::Array:
+    cast<ArrayType>().getCapabilities(capabilities, storage);
+    break;
+  case spirv::TypeKind::RuntimeArray:
+    cast<ArrayType>().getCapabilities(capabilities, storage);
+    break;
+  case spirv::TypeKind::Struct:
+    cast<StructType>().getCapabilities(capabilities, storage);
+    break;
+  case StandardTypes::Vector:
+    cast<VectorType>().getElementType().cast<ScalarType>().getCapabilities(
+        capabilities, storage);
+    break;
+  default:
+    llvm_unreachable("invalid composite type");
+  }
+}
+
 //===----------------------------------------------------------------------===//
 // ImageType
 //===----------------------------------------------------------------------===//
 
 template <typename T> static constexpr unsigned getNumBits() { return 0; }
 template <> constexpr unsigned getNumBits<Dim>() {
   static_assert((1 << 3) > getMaxEnumValForDim(),
                 "Not enough bits to encode Dim value");

 ImageSamplerUseInfo ImageType::getSamplerUseInfo() const {
   return getImpl()->getSamplerUseInfo();
 }
 
 ImageFormat ImageType::getImageFormat() const {
   return getImpl()->getImageFormat();
 }
 
+void ImageType::getExtensions(SPIRVType::ExtensionArrayRefVector &,
+                              Optional<StorageClass>) {
+  // Image types do not require extra extensions thus far.
+}
+
+void ImageType::getCapabilities(
+    SPIRVType::CapabilityArrayRefVector &capabilities, Optional<StorageClass>) {
+  if (auto dimCaps = spirv::getCapabilities(getDim()))
+    capabilities.push_back(*dimCaps);
+
+  if (auto fmtCaps = spirv::getCapabilities(getImageFormat()))
+    capabilities.push_back(*fmtCaps);
+}
+
 //===----------------------------------------------------------------------===//
 // PointerType
 //===----------------------------------------------------------------------===//
 
 struct spirv::detail::PointerTypeStorage : public TypeStorage {
   // (Type, StorageClass) as the key: Type stored in this struct, and
   // StorageClass stored as TypeStorage's subclass data.
   using KeyTy = std::pair<Type, StorageClass>;

 }
 
 Type PointerType::getPointeeType() const { return getImpl()->pointeeType; }
 
 StorageClass PointerType::getStorageClass() const {
   return getImpl()->getStorageClass();
 }
 
+void PointerType::getExtensions(SPIRVType::ExtensionArrayRefVector &extensions,
+                                Optional<StorageClass> storage) {
+  if (storage)
+    assert(*storage == getStorageClass() && "inconsistent storage class!");
+
+  // Use this pointer type's storage class because this pointer indicates we are
+  // using the pointee type in that specific storage class.
+  getPointeeType().cast<SPIRVType>().getExtensions(extensions,
+                                                   getStorageClass());
+
+  if (auto scExts = spirv::getExtensions(getStorageClass()))
+    extensions.push_back(*scExts);
+}
+
+void PointerType::getCapabilities(
+    SPIRVType::CapabilityArrayRefVector &capabilities,
+    Optional<StorageClass> storage) {
+  if (storage)
+    assert(*storage == getStorageClass() && "inconsistent storage class!");
+
+  // Use this pointer type's storage class because this pointer indicates we are
+  // using the pointee type in that specific storage class.
+  getPointeeType().cast<SPIRVType>().getCapabilities(capabilities,
+                                                     getStorageClass());
+
+  if (auto scCaps = spirv::getCapabilities(getStorageClass()))
+    capabilities.push_back(*scCaps);
+}
+
 //===----------------------------------------------------------------------===//
 // RuntimeArrayType
 //===----------------------------------------------------------------------===//
 
 struct spirv::detail::RuntimeArrayTypeStorage : public TypeStorage {
   using KeyTy = Type;
 
   static RuntimeArrayTypeStorage *construct(TypeStorageAllocator &allocator,

 
 RuntimeArrayType RuntimeArrayType::get(Type elementType) {
   return Base::get(elementType.getContext(), TypeKind::RuntimeArray,
                    elementType);
 }
 
 Type RuntimeArrayType::getElementType() const { return getImpl()->elementType; }
 
+void RuntimeArrayType::getExtensions(
+    SPIRVType::ExtensionArrayRefVector &extensions,
+    Optional<StorageClass> storage) {
+  getElementType().cast<SPIRVType>().getExtensions(extensions, storage);
+}
+
+void RuntimeArrayType::getCapabilities(
+    SPIRVType::CapabilityArrayRefVector &capabilities,
+    Optional<StorageClass> storage) {
+  {
+    static const Capability caps[] = {Capability::Shader};
+    ArrayRef<Capability> ref(caps, llvm::array_lengthof(caps));
+    capabilities.push_back(ref);
+  }
+  getElementType().cast<SPIRVType>().getCapabilities(capabilities, storage);
+}
+
+//===----------------------------------------------------------------------===//
+// ScalarType
+//===----------------------------------------------------------------------===//
+
+bool ScalarType::classof(Type type) { return type.isIntOrFloat(); }
+
+void ScalarType::getExtensions(SPIRVType::ExtensionArrayRefVector &extensions,
+                               Optional<StorageClass> storage) {
+  // 8- or 16-bit integer/floating-point numbers will require extra extensions
+  // to appear in interface storage classes. See SPV_KHR_16bit_storage and
+  // SPV_KHR_8bit_storage for more details.
+  if (!storage)
+    return;
+
+  switch (*storage) {
+  case StorageClass::PushConstant:
+  case StorageClass::StorageBuffer:
+  case StorageClass::Uniform:
+    if (getIntOrFloatBitWidth() == 8) {
+      static const Extension exts[] = {Extension::SPV_KHR_8bit_storage};
+      ArrayRef<Extension> ref(exts, llvm::array_lengthof(exts));
+      extensions.push_back(ref);
+    }
+    LLVM_FALLTHROUGH;
+  case StorageClass::Input:
+  case StorageClass::Output:
+    if (getIntOrFloatBitWidth() == 16) {
+      static const Extension exts[] = {Extension::SPV_KHR_16bit_storage};
+      ArrayRef<Extension> ref(exts, llvm::array_lengthof(exts));
+      extensions.push_back(ref);
+    }
+    break;
+  default:
+    break;
+  }
+}
+
+void ScalarType::getCapabilities(
+    SPIRVType::CapabilityArrayRefVector &capabilities,
+    Optional<StorageClass> storage) {
+  unsigned bitwidth = getIntOrFloatBitWidth();
+
+  // 8- or 16-bit integer/floating-point numbers will require extra capabilities
+  // to appear in interface storage classes. See SPV_KHR_16bit_storage and
+  // SPV_KHR_8bit_storage for more details.
+
+#define STORAGE_CASE(storage, cap8, cap16)                                     \
+  case StorageClass::storage: {                                                \
+    if (bitwidth == 8) {                                                       \
+      static const Capability caps[] = {Capability::cap8};                     \
+      ArrayRef<Capability> ref(caps, llvm::array_lengthof(caps));              \
+      capabilities.push_back(ref);                                             \
+    } else if (bitwidth == 16) {                                               \
+      static const Capability caps[] = {Capability::cap16};                    \
+      ArrayRef<Capability> ref(caps, llvm::array_lengthof(caps));              \
+      capabilities.push_back(ref);                                             \
+    }                                                                          \
+  } break
+
+  if (storage) {
+    switch (*storage) {
+      STORAGE_CASE(PushConstant, StoragePushConstant8, StoragePushConstant16);
+      STORAGE_CASE(StorageBuffer, StorageBuffer8BitAccess,
+                   StorageBuffer16BitAccess);
+      STORAGE_CASE(Uniform, UniformAndStorageBuffer8BitAccess,
+                   StorageUniform16);
+    case StorageClass::Input:
+    case StorageClass::Output:
+      if (bitwidth == 16) {
+        static const Capability caps[] = {Capability::StorageInputOutput16};
+        ArrayRef<Capability> ref(caps, llvm::array_lengthof(caps));
+        capabilities.push_back(ref);
+      }
+      break;
+    default:
+      break;
+    }
+    return;
+  }
+#undef STORAGE_CASE
+
+  // For other non-interface storage classes, require a different set of
+  // capabilities for special bitwidths.
+
+#define WIDTH_CASE(type, width)                                                \
+  case width: {                                                                \
+    static const Capability caps[] = {Capability::type##width};                \
+    ArrayRef<Capability> ref(caps, llvm::array_lengthof(caps));                \
+    capabilities.push_back(ref);                                               \
+  } break
+
+  if (auto intType = dyn_cast<IntegerType>()) {
+    switch (bitwidth) {
+    case 32:
+    case 1:
+      break;
+      WIDTH_CASE(Int, 8);
+      WIDTH_CASE(Int, 16);
+      WIDTH_CASE(Int, 64);
+    default:
+      llvm_unreachable("invalid bitwidth to getCapabilities");
+    }
+  } else {
+    assert(isa<FloatType>());
+    switch (bitwidth) {
+    case 32:
+      break;
+      WIDTH_CASE(Float, 16);
+      WIDTH_CASE(Float, 64);
+    default:
+      llvm_unreachable("invalid bitwidth to getCapabilities");
+    }
+  }
+
+#undef WIDTH_CASE
+}
+
+//===----------------------------------------------------------------------===//
+// SPIRVType
+//===----------------------------------------------------------------------===//
+
+bool SPIRVType::classof(Type type) {
+  return type.isa<ScalarType>() || type.isa<VectorType>() ||
+         (type.getKind() >= Type::FIRST_SPIRV_TYPE &&
+          type.getKind() <= TypeKind::LAST_SPIRV_TYPE);
+}
+
+void SPIRVType::getExtensions(SPIRVType::ExtensionArrayRefVector &extensions,
+                              Optional<StorageClass> storage) {
+  if (auto scalarType = dyn_cast<ScalarType>()) {
+    scalarType.getExtensions(extensions, storage);
+  } else if (auto compositeType = dyn_cast<CompositeType>()) {
+    compositeType.getExtensions(extensions, storage);
+  } else if (auto ptrType = dyn_cast<PointerType>()) {
+    ptrType.getExtensions(extensions, storage);
+  } else if (auto imageType = dyn_cast<ImageType>()) {
+    imageType.getExtensions(extensions, storage);
+  } else {
+    llvm_unreachable("invalid SPIR-V Type to getExtensions");
+  }
+}
+
+void SPIRVType::getCapabilities(
+    SPIRVType::CapabilityArrayRefVector &capabilities,
+    Optional<StorageClass> storage) {
+  if (auto scalarType = dyn_cast<ScalarType>()) {
+    scalarType.getCapabilities(capabilities, storage);
+  } else if (auto compositeType = dyn_cast<CompositeType>()) {
+    compositeType.getCapabilities(capabilities, storage);
+  } else if (auto ptrType = dyn_cast<PointerType>()) {
+    ptrType.getCapabilities(capabilities, storage);
+  } else if (auto imageType = dyn_cast<ImageType>()) {
+    imageType.getCapabilities(capabilities, storage);
+  } else {
+    llvm_unreachable("invalid SPIR-V Type to getCapabilities");
+  }
+}
+
 //===----------------------------------------------------------------------===//
 // StructType
 //===----------------------------------------------------------------------===//
 
 struct spirv::detail::StructTypeStorage : public TypeStorage {
   StructTypeStorage(
       unsigned numMembers, Type const *memberTypes,
       StructType::LayoutInfo const *layoutInfo, unsigned numMemberDecorations,
return Base::get(context, TypeKind::Struct, ArrayRef<Type>(),
                    ArrayRef<StructType::MemberDecorationInfo>());
 }
 
 unsigned StructType::getNumElements() const {
   return getImpl()->getSubclassData();
 }
 
 Type StructType::getElementType(unsigned index) const {
-  assert(
-      getNumElements() > index &&
-      "element index is more than number of members of the SPIR-V StructType");
+  assert(getNumElements() > index && "member index out of range");
   return getImpl()->memberTypes[index];
 }
 
+StructType::ElementTypeRange StructType::getElementTypes() const {
+  return ElementTypeRange(getImpl()->memberTypes, getNumElements());
+}
+
 bool StructType::hasLayout() const { return getImpl()->layoutInfo; }
 
 uint64_t StructType::getOffset(unsigned index) const {
-  assert(
-      getNumElements() > index &&
-      "element index is more than number of members of the SPIR-V StructType");
+  assert(getNumElements() > index && "member index out of range");
   return getImpl()->layoutInfo[index];
 }
 
 void StructType::getMemberDecorations(
     SmallVectorImpl<StructType::MemberDecorationInfo> &memberDecorations)
     const {
   memberDecorations.clear();
   auto implMemberDecorations = getImpl()->getMemberDecorationsInfo();
if (memberDecoration.first == index) {
       decorations.push_back(memberDecoration.second);
     }
     if (memberDecoration.first > index) {
       // Early exit since the decorations are stored sorted.
       return;
     }
   }
 }
+
+void StructType::getExtensions(SPIRVType::ExtensionArrayRefVector &extensions,
+                               Optional<StorageClass> storage) {
+  for (Type elementType : getElementTypes())
+    elementType.cast<SPIRVType>().getExtensions(extensions, storage);
+}
+
+void StructType::getCapabilities(
+    SPIRVType::CapabilityArrayRefVector &capabilities,
+    Optional<StorageClass> storage) {
+  for (Type elementType : getElementTypes())
+    elementType.cast<SPIRVType>().getCapabilities(capabilities, storage);
+}

mlir/lib/Dialect/SPIRV/Transforms/UpdateVCEPass.cpp

 /// spirv::ModuleOp.
 class UpdateVCEPass final
     : public OperationPass<UpdateVCEPass, spirv::ModuleOp> {
 private:
   void runOnOperation() override;
 };
 } // namespace
 
+/// Checks that `candidates` extension requirements are possible to be satisfied
+/// with the given `allowedExtensions` and updates `deducedExtensions` if so.
+/// Emits errors attaching to the given `op` on failures.
+///
+///  `candidates` is a vector of vector for extension requirements following
+/// ((Extension::A OR Extension::B) AND (Extension::C OR Extension::D))
+/// convention.
+static LogicalResult checkAndUpdateExtensionRequirements(
+    Operation *op, const llvm::SmallSet<spirv::Extension, 4> &allowedExtensions,
+    const spirv::SPIRVType::ExtensionArrayRefVector &candidates,
+    llvm::SetVector<spirv::Extension> &deducedExtensions) {
+  for (const auto &ors : candidates) {
+    auto chosen = llvm::find_if(ors, [&](spirv::Extension ext) {
+      return allowedExtensions.count(ext);
+    });
+
+    if (chosen != ors.end()) {
+      deducedExtensions.insert(*chosen);
+    } else {
+      SmallVector<StringRef, 4> extStrings;
+      for (spirv::Extension ext : ors)
+        extStrings.push_back(spirv::stringifyExtension(ext));
+
+      emitError(op->getLoc(), "'")
+          << op->getName() << "' requires at least one extension in ["
+          << llvm::join(extStrings, ", ")
+          << "] but none allowed in target environment";
+      return failure();
+    }
+  }
+  return success();
+}
+
+/// Checks that `candidates`capability requirements are possible to be satisfied
+/// with the given `allowedCapabilities` and updates `deducedCapabilities` if
+/// so. Emits errors attaching to the given `op` on failures.
+///
+///  `candidates` is a vector of vector for capability requirements following
+/// ((Capability::A OR Capability::B) AND (Capability::C OR Capability::D))
+/// convention.
+static LogicalResult checkAndUpdateCapabilityRequirements(
+    Operation *op,
+    const llvm::SmallSet<spirv::Capability, 8> &allowedCapabilities,
+    const spirv::SPIRVType::CapabilityArrayRefVector &candidates,
+    llvm::SetVector<spirv::Capability> &deducedCapabilities) {
+  for (const auto &ors : candidates) {
+    auto chosen = llvm::find_if(ors, [&](spirv::Capability cap) {
+      return allowedCapabilities.count(cap);
+    });
+
+    if (chosen != ors.end()) {
+      deducedCapabilities.insert(*chosen);
+    } else {
+      SmallVector<StringRef, 4> capStrings;
+      for (spirv::Capability cap : ors)
+        capStrings.push_back(spirv::stringifyCapability(cap));
+
+      emitError(op->getLoc(), "'")
+          << op->getName() << "' requires at least one capability in ["
+          << llvm::join(capStrings, ", ")
+          << "] but none allowed in target environment";
+      return failure();
+    }
+  }
+  return success();
+}
+
 void UpdateVCEPass::runOnOperation() {
   spirv::ModuleOp module = getOperation();
 
   spirv::TargetEnvAttr targetEnv = spirv::lookupTargetEnv(module);
   if (!targetEnv) {
     module.emitError("missing 'spv.target_env' attribute");
     return signalPassFailure();
   }
void UpdateVCEPass::runOnOperation() {
 
   spirv::Version deducedVersion = spirv::Version::V_1_0;
   llvm::SetVector<spirv::Extension> deducedExtensions;
   llvm::SetVector<spirv::Capability> deducedCapabilities;
 
   // Walk each SPIR-V op to deduce the minimal version/extension/capability
   // requirements.
   WalkResult walkResult = module.walk([&](Operation *op) {
+    // Op min version requirements
     if (auto minVersion = dyn_cast<spirv::QueryMinVersionInterface>(op)) {
       deducedVersion = std::max(deducedVersion, minVersion.getMinVersion());
       if (deducedVersion > allowedVersion) {
         emitError(op->getLoc(), "'")
             << op->getName() << "' requires min version "
             << spirv::stringifyVersion(deducedVersion)
             << " but target environment allows up to "
             << spirv::stringifyVersion(allowedVersion);
         return WalkResult::interrupt();
       }
     }
 
-    // Deduce this op's extension requirement. For each op, the query interfacce
-    // returns a vector of vector for its extension requirements following
-    // ((Extension::A OR Extension::B) AND (Extension::C OR Extension::D))
-    // convention. Ops not implementing QueryExtensionInterface do not require
-    // extensions to be available.
-    if (auto extensions = dyn_cast<spirv::QueryExtensionInterface>(op)) {
-      for (const auto &ors : extensions.getExtensions()) {
-        bool satisfied = false; // True when at least one extension can be used
-        for (spirv::Extension ext : ors) {
-          if (allowedExtensions.count(ext)) {
-            deducedExtensions.insert(ext);
-            satisfied = true;
-            break;
-          }
-        }
-
-        if (!satisfied) {
-          SmallVector<StringRef, 4> extStrings;
-          for (spirv::Extension ext : ors)
-            extStrings.push_back(spirv::stringifyExtension(ext));
-
-          emitError(op->getLoc(), "'")
-              << op->getName() << "' requires at least one extension in ["
-              << llvm::join(extStrings, ", ")
-              << "] but none allowed in target environment";
-          return WalkResult::interrupt();
-        }
-      }
-    }
+    // Op extension requirements
+    if (auto extensions = dyn_cast<spirv::QueryExtensionInterface>(op))
+      if (failed(checkAndUpdateExtensionRequirements(
+              op, allowedExtensions, extensions.getExtensions(),
+              deducedExtensions)))
 
-    // Deduce this op's capability requirement. For each op, the queryinterface
-    // returns a vector of vector for its capability requirements following
-    // ((Capability::A OR Extension::B) AND (Capability::C OR Capability::D))
-    // convention. Ops not implementing QueryExtensionInterface do not require
-    // extensions to be available.
-    if (auto capabilities = dyn_cast<spirv::QueryCapabilityInterface>(op)) {
-      for (const auto &ors : capabilities.getCapabilities()) {
-        bool satisfied = false; // True when at least one capability can be used
-        for (spirv::Capability cap : ors) {
-          if (allowedCapabilities.count(cap)) {
-            deducedCapabilities.insert(cap);
-            satisfied = true;
-            break;
-          }
-        }
+    // Op capability requirements
+    if (auto capabilities = dyn_cast<spirv::QueryCapabilityInterface>(op))
+      if (failed(checkAndUpdateCapabilityRequirements(
+              op, allowedCapabilities, capabilities.getCapabilities(),
+              deducedCapabilities)))
+        return WalkResult::interrupt();
 
-        if (!satisfied) {
-          SmallVector<StringRef, 4> capStrings;
-          for (spirv::Capability cap : ors)
-            capStrings.push_back(spirv::stringifyCapability(cap));
+    SmallVector<Type, 4> valueTypes;
+    valueTypes.append(op->operand_type_begin(), op->operand_type_end());
+    valueTypes.append(op->result_type_begin(), op->result_type_end());
+
+    // Special treatment for global variables, whose type requirements are
+    // conveyed by type attributes.
+    if (auto globalVar = dyn_cast<spirv::GlobalVariableOp>(op))
+      valueTypes.push_back(globalVar.type());
+
+    // Requirements from values' types
+    SmallVector<ArrayRef<spirv::Extension>, 4> typeExtensions;
+    SmallVector<ArrayRef<spirv::Capability>, 8> typeCapabilities;
+    for (Type valueType : valueTypes) {
+      typeExtensions.clear();
+      valueType.cast<spirv::SPIRVType>().getExtensions(typeExtensions);
+      if (failed(checkAndUpdateExtensionRequirements(
+              op, allowedExtensions, typeExtensions, deducedExtensions)))
+        return WalkResult::interrupt();
 
-          emitError(op->getLoc(), "'")
-              << op->getName() << "' requires at least one capability in ["
-              << llvm::join(capStrings, ", ")
-              << "] but none allowed in target environment";
-          return WalkResult::interrupt();
-        }
-      }
-    }
+      typeCapabilities.clear();
+      valueType.cast<spirv::SPIRVType>().getCapabilities(typeCapabilities);
+      if (failed(checkAndUpdateCapabilityRequirements(
+              op, allowedCapabilities, typeCapabilities, deducedCapabilities)))
 
     return WalkResult::advance();
   });
 
   if (walkResult.wasInterrupted())
     return signalPassFailure();
 
   // TODO(antiagainst): verify that the deduced version is consistent with

mlir/test/Dialect/SPIRV/Transforms/vce-deduction.mlir

spv.target_env = #spv.target_env<
      max_compute_workgroup_size = dense<[128, 128, 64]> : vector<3xi32>}>
 } {
   spv.func @group_non_uniform_iadd(%val : i32) -> i32 "None" {
     %0 = spv.GroupNonUniformIAdd "Subgroup" "Reduce" %val : i32
     spv.ReturnValue %0: i32
   }
 }
 
+// Test type required capabilities
+
+// Using 8-bit integers in non-interface storage class requires Int8.
+// CHECK: requires #spv.vce<v1.0, [Int8, Shader], []>
+spv.module Logical GLSL450 attributes {
+  spv.target_env = #spv.target_env<
+    #spv.vce<v1.3, [Shader, Int8], []>,
+    {max_compute_workgroup_invocations = 128 : i32,
+     max_compute_workgroup_size = dense<[128, 128, 64]> : vector<3xi32>}>
+} {
+  spv.func @iadd_function(%val : i8) -> i8 "None" {
+    %0 = spv.IAdd %val, %val : i8
+    spv.ReturnValue %0: i8
+  }
+}
+
+// Using 16-bit floats in non-interface storage class requires Float16.
+// CHECK: requires #spv.vce<v1.0, [Float16, Shader], []>
+spv.module Logical GLSL450 attributes {
+  spv.target_env = #spv.target_env<
+    #spv.vce<v1.3, [Shader, Float16], []>,
+    {max_compute_workgroup_invocations = 128 : i32,
+     max_compute_workgroup_size = dense<[128, 128, 64]> : vector<3xi32>}>
+} {
+  spv.func @fadd_function(%val : f16) -> f16 "None" {
+    %0 = spv.FAdd %val, %val : f16
+    spv.ReturnValue %0: f16
+  }
+}
+
 //===----------------------------------------------------------------------===//
 // Extension
 //===----------------------------------------------------------------------===//
 
 // Test deducing minimal extensions.
 // spv.SubgroupBallotKHR requires the SPV_KHR_shader_ballot extension.
 
 // CHECK: requires #spv.vce<v1.0, [SubgroupBallotKHR, Shader], [SPV_KHR_shader_ballot]>
spv.target_env = #spv.target_env<
     {max_compute_workgroup_invocations = 128 : i32,
      max_compute_workgroup_size = dense<[128, 128, 64]> : vector<3xi32>}>
 } {
   spv.func @iadd(%val : i32) -> i32 "None" {
     %0 = spv.IAdd %val, %val: i32
     spv.ReturnValue %0: i32
   }
 }
+
+// Test type required extensions
+
+// Using 8-bit integers in interface storage class requires additional
+// extensions and capabilities.
+// CHECK: requires #spv.vce<v1.0, [StorageBuffer16BitAccess, Shader, Int16], [SPV_KHR_16bit_storage, SPV_KHR_storage_buffer_storage_class]>
+spv.module Logical GLSL450 attributes {
+  spv.target_env = #spv.target_env<
+    #spv.vce<v1.3, [Shader, StorageBuffer16BitAccess, Int16], []>,
+    {max_compute_workgroup_invocations = 128 : i32,
+     max_compute_workgroup_size = dense<[128, 128, 64]> : vector<3xi32>}>
+} {
+  spv.func @iadd_storage_buffer(%ptr : !spv.ptr<i16, StorageBuffer>) -> i16 "None" {
+    %0 = spv.Load "StorageBuffer" %ptr : i16
+    %1 = spv.IAdd %0, %0 : i16
+    spv.ReturnValue %1: i16
+  }
+}
+
+// Complicated nested types
+// * Buffer requires ImageBuffer or SampledBuffer.
+// * Rg32f requires StorageImageExtendedFormats.
+// CHECK: requires #spv.vce<v1.0, [UniformAndStorageBuffer8BitAccess, StorageUniform16, Shader, ImageBuffer, StorageImageExtendedFormats], [SPV_KHR_8bit_storage, SPV_KHR_16bit_storage]>
+spv.module Logical GLSL450 attributes {
+  spv.target_env = #spv.target_env<
+    #spv.vce<v1.5, [Shader, UniformAndStorageBuffer8BitAccess, StorageBuffer16BitAccess, StorageUniform16, Int16, ImageBuffer, StorageImageExtendedFormats], []>,
+    {max_compute_workgroup_invocations = 128 : i32,
+     max_compute_workgroup_size = dense<[128, 128, 64]> : vector<3xi32>}>
+} {
+  spv.globalVariable @data : !spv.ptr<!spv.struct<i8 [0], f16 [2], i64 [4]>, Uniform>
+  spv.globalVariable @img  : !spv.ptr<!spv.image<f32, Buffer, NoDepth, NonArrayed, SingleSampled, SamplerUnknown, Rg32f>, UniformConstant>
+}