[mlir][ODS] Support specialized Attribute class for Enums

[vinograd47]

Summary

Add a feature to EnumAttr definition to generate
specialized Attribute class for the particular enumeration.

This class will inherit StringAttr or IntegerAttr and
will override classof and getValue methods.

With this class the enumeration predicate can be checked with simple
RTTI calls (isa, dyn_cast) and it will return the typed enumeration
directly instead of raw string/integer.

Based on the following discussion:
https://llvm.discourse.group/t/rfc-add-enum-attribute-decorator-class/2252

[vinograd47]

Fixed clang-tidy issues.

[rriddle]

mlir/include/mlir/IR/OpBase.td

1195

In what situations is this not desirable? This seems always desirable given that we could add utility methods for things like symbolization, getting the case value, etc.

1230

Why?

mlir/tools/mlir-tblgen/EnumsGen.cpp

324

You shouldn't need this check. classof should be guaranteed to never be called on a null value.

330

nit: Spell out auto here and above.

353

Drop trivial braces here.

[vinograd47]

mlir/include/mlir/IR/OpBase.td

1195

In what situations is this not desirable? This seems always desirable given that we could add utility methods for things like symbolization, getting the case value, etc.

I've disabled this feature for StrEnumAttr be default, because it might be less effective. The Enum getValue() method in specialized class will call symbolizeEnum each time (doing the string switch). So, in general StringRef getValue() and string comparison might be efficient than this approach. genSpecializedAttr allows to choose between type-safety and efficiency. In my local fork I did some optimization to overcome this - added separate mutable field to StringAttr to hold actual enumeration value (as uint64_t). If the enum attribute is creates with specialized attribute get/getChecked method, then this field is set. But this approach is fragile. For example, we might have 2 dialects, which has separate enums with the same string values, but different indexes (eg. "Foo::CaseA == 1" and Bar::Case1 == 5), but both of them will be represented as single "Case1" StringAttr.

[vinograd47]

Rebased and fixed review comments.

[vinograd47]

@rriddle I've fixed your remarks in EnumsGen.cpp.

[vinograd47]

Rebased

mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td

def LLVM_ICmpOp : LLVM_Op<"icmp", [NoSideEffect]> {
   let results = (outs LLVM_ScalarOrVectorOf<I1>:$res);
   let llvmBuilder = [{
     $res = builder.CreateICmp(getLLVMCmpPredicate($predicate), $lhs, $rhs);
   }];
   let builders = [
     OpBuilderDAG<(ins "ICmpPredicate":$predicate, "Value":$lhs, "Value":$rhs),
     [{
       build($_builder, $_state, IntegerType::get(lhs.getType().getContext(), 1),
-            $_builder.getI64IntegerAttr(static_cast<int64_t>(predicate)), lhs, rhs);
+            predicate, lhs, rhs);
     }]>];
   let parser = [{ return parseCmpOp<ICmpPredicate>(parser, result); }];
   let printer = [{ printICmpOp(p, *this); }];
 }
 
 // Predicate for float comparisons
 def FCmpPredicateFALSE  : I64EnumAttrCase<"_false", 0>;
 def FCmpPredicateOEQ    : I64EnumAttrCase<"oeq", 1>;
def LLVM_FCmpOp : LLVM_Op<"fcmp", [
   let arguments = (ins FCmpPredicate:$predicate,
                    LLVM_ScalarOrVectorOf<LLVM_AnyFloat>:$lhs,
                    LLVM_ScalarOrVectorOf<LLVM_AnyFloat>:$rhs,
                    DefaultValuedAttr<LLVM_FMFAttr, "{}">:$fastmathFlags);
   let results = (outs LLVM_ScalarOrVectorOf<I1>:$res);
   let llvmBuilder = [{
     $res = builder.CreateFCmp(getLLVMCmpPredicate($predicate), $lhs, $rhs);
   }];
-  let builders = [
-    OpBuilderDAG<(ins "FCmpPredicate":$predicate, "Value":$lhs, "Value":$rhs,
-                  CArg<"FastmathFlags", "{}">:$fmf),
-    [{
-      build($_builder, $_state, IntegerType::get(lhs.getType().getContext(), 1),
-            $_builder.getI64IntegerAttr(static_cast<int64_t>(predicate)), lhs, rhs,
-            ::mlir::LLVM::FMFAttr::get(fmf, $_builder.getContext()));
-    }]>];
   let parser = [{ return parseCmpOp<FCmpPredicate>(parser, result); }];
   let printer = [{ printFCmpOp(p, *this); }];
 }
 
 // Floating point binary operations.
 def LLVM_FAddOp : LLVM_FloatArithmeticOp<"fadd", "CreateFAdd">;
 def LLVM_FSubOp : LLVM_FloatArithmeticOp<"fsub", "CreateFSub">;
 def LLVM_FMulOp : LLVM_FloatArithmeticOp<"fmul", "CreateFMul">;

mlir/include/mlir/Dialect/SPIRV/IR/SPIRVEnums.h

 //===- SPIRVEnums.h - MLIR SPIR-V Enums -------------------------*- 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 declares the C/C++ enums from SPIR-V spec.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef MLIR_DIALECT_SPIRV_IR_SPIRVENUMS_H_
 #define MLIR_DIALECT_SPIRV_IR_SPIRVENUMS_H_
 
+#include "mlir/IR/BuiltinAttributes.h"
 #include "mlir/Support/LLVM.h"
 #include "llvm/ADT/DenseMapInfo.h"
 #include "llvm/ADT/StringRef.h"
 
 // Forward declare enum classes related to op availability. Their definitions
 // are in the TableGen'erated SPIRVEnums.h.inc and can be referenced by other
 // declarations in SPIRVEnums.h.inc.
 namespace mlir {

mlir/include/mlir/Dialect/SPIRV/IR/SPIRVMemoryOps.td

def SPV_LoadOp : SPV_Op<"Load", []> {
   );
 
   let results = (outs
     SPV_Type:$value
   );
 
   let builders = [
     OpBuilderDAG<(ins "Value":$basePtr,
-      CArg<"IntegerAttr", "{}">:$memory_access,
+      CArg<"MemoryAccessAttr", "{}">:$memory_access,
       CArg<"IntegerAttr", "{}">:$alignment)>
   ];
 }
 
 // -----
 
 def SPV_StoreOp : SPV_Op<"Store", []> {
   let summary = "Store through a pointer.";

mlir/include/mlir/Dialect/Vector/VectorOps.td

 
 def CombiningKind : BitEnumAttr<
     "CombiningKind",
     "Kind of combining function for contractions and reductions",
     [COMBINING_KIND_ADD, COMBINING_KIND_MUL, COMBINING_KIND_MIN,
      COMBINING_KIND_MAX, COMBINING_KIND_AND, COMBINING_KIND_OR,
      COMBINING_KIND_XOR]> {
   let cppNamespace = "::mlir::vector";
+  let genSpecializedAttr = 0;
 }
 
 def Vector_CombiningKindAttr : DialectAttr<
     Vector_Dialect,
     CPred<"$_self.isa<::mlir::vector::CombiningKindAttr>()">,
     "Kind of combining function for contractions and reductions"> {
   let storageType = "::mlir::vector::CombiningKindAttr";
   let returnType = "::mlir::vector::CombiningKind";

mlir/include/mlir/IR/OpBase.td

class BitEnumAttrCase<string sym, int val, string str = sym> :
     EnumAttrCaseInfo<sym, val, str>,
     SignlessIntegerAttrBase<I32, "case " # str> {
   let predicate = CPred<
     "$_self.cast<::mlir::IntegerAttr>().getValue().getZExtValue() & "
     # val # "u">;
 }
 
 // Additional information for an enum attribute.
-class EnumAttrInfo<string name, list<EnumAttrCaseInfo> cases> {
+class EnumAttrInfo<
+    string name, list<EnumAttrCaseInfo> cases, Attr baseClass> :
+      Attr<baseClass.predicate, baseClass.summary> {
   // The C++ enum class name
   string className = name;
 
   // List of all accepted cases
   list<EnumAttrCaseInfo> enumerants = cases;
 
   // The following fields are only used by the EnumsGen backend to generate
   // an enum class definition and conversion utility functions.
class EnumAttrInfo<
 
   // The name of the utility function that returns the max enum value used
   // within the enum class. It will have the following signature:
   //
   // ```c++
   // static constexpr unsigned <fn-name>();
   // ```
   string maxEnumValFnName = "getMaxEnumValFor" # name;
+
+  // Generate specialized Attribute class
+  bit genSpecializedAttr = 1;
+  // The underlying Attribute class, which holds the enum value
+  Attr baseAttrClass = baseClass;
+  // The name of specialized Enum Attribute class
+  string specializedAttrClassName = name # Attr;
+
+  // Override Attr class fields for specialized class
+  let predicate = !if(genSpecializedAttr,
+    CPred<"$_self.isa<" # cppNamespace # "::" # specializedAttrClassName # ">()">,
+    baseAttrClass.predicate);
+  let storageType = !if(genSpecializedAttr,
+    cppNamespace # "::" # specializedAttrClassName,
+    baseAttrClass.storageType);
+  let returnType = !if(genSpecializedAttr,
+    cppNamespace # "::" # className,
+    baseAttrClass.returnType);
+  let constBuilderCall = !if(genSpecializedAttr,
+    cppNamespace # "::" # specializedAttrClassName # "::get($_builder.getContext(), $0)",
+    baseAttrClass.constBuilderCall);
+  let valueType = baseAttrClass.valueType;
 }
 
 // An enum attribute backed by StringAttr.
 //
 // Op attributes of this kind are stored as StringAttr. Extra verification will
 // be generated on the string though: only the symbols of the allowed cases are
 // permitted as the string value.
-class StrEnumAttr<string name, string summary, list<StrEnumAttrCase> cases>
-  : EnumAttrInfo<name, cases>,
+class StrEnumAttr<string name, string summary, list<StrEnumAttrCase> cases> :
+  EnumAttrInfo<name, cases,
     StringBasedAttr<
       And<[StrAttr.predicate, Or<!foreach(case, cases, case.predicate)>]>,
       !if(!empty(summary), "allowed string cases: " #
           !interleave(!foreach(case, cases, "'" # case.symbol # "'"), ", "),
-          summary)>;
+          summary)>> {
+  // Disable specialized Attribute class for `StringAttr` backend by default.
+  let genSpecializedAttr = 0;
+}
 
 // An enum attribute backed by IntegerAttr.
 //
 // Op attributes of this kind are stored as IntegerAttr. Extra verification will
 // be generated on the integer though: only the values of the allowed cases are
 // permitted as the integer value.
-class IntEnumAttr<I intType, string name, string summary,
-                  list<IntEnumAttrCaseBase> cases> :
-    EnumAttrInfo<name, cases>,
-    SignlessIntegerAttrBase<intType,
-      !if(!empty(summary), "allowed " # intType.summary # " cases: " #
-          !interleave(!foreach(case, cases, case.value), ", "), summary)> {
+class IntEnumAttrBase<I intType, list<IntEnumAttrCaseBase> cases, string summary> :
+    SignlessIntegerAttrBase<intType, summary> {
   let predicate = And<[
-    SignlessIntegerAttrBase<intType, "">.predicate,
+    SignlessIntegerAttrBase<intType, summary>.predicate,
     Or<!foreach(case, cases, case.predicate)>]>;
 }
 
-class I32EnumAttr<string name, string summary,
-                  list<I32EnumAttrCase> cases> :
+class IntEnumAttr<I intType, string name, string summary,
+                  list<IntEnumAttrCaseBase> cases> :
+  EnumAttrInfo<name, cases,
+    IntEnumAttrBase<intType, cases,
+      !if(!empty(summary), "allowed " # intType.summary # " cases: " #
+          !interleave(!foreach(case, cases, case.value), ", "),
+          summary)>>;
+
+class I32EnumAttr<string name, string summary, list<I32EnumAttrCase> cases> :
     IntEnumAttr<I32, name, summary, cases> {
-  let returnType = cppNamespace # "::" # name;
   let underlyingType = "uint32_t";
-  let convertFromStorage = "static_cast<" # returnType # ">($_self.getInt())";
-  let constBuilderCall =
-          "$_builder.getI32IntegerAttr(static_cast<int32_t>($0))";
 }
-class I64EnumAttr<string name, string summary,
-                  list<I64EnumAttrCase> cases> :
+class I64EnumAttr<string name, string summary, list<I64EnumAttrCase> cases> :
     IntEnumAttr<I64, name, summary, cases> {
-  let returnType = cppNamespace # "::" # name;
   let underlyingType = "uint64_t";
-  let convertFromStorage = "static_cast<" # returnType # ">($_self.getInt())";
-  let constBuilderCall =
-          "$_builder.getI64IntegerAttr(static_cast<int64_t>($0))";
 }
 
 // A bit enum stored with 32-bit IntegerAttr.
 //
 // Op attributes of this kind are stored as IntegerAttr. Extra verification will
 // be generated on the integer to make sure only allowed bit are set. Besides,
 // helper methods are generated to parse a string separated with a specified
 // delimiter to a symbol and vice versa.
-class BitEnumAttr<string name, string summary,
-                  list<BitEnumAttrCase> cases> :
-    EnumAttrInfo<name, cases>, SignlessIntegerAttrBase<I32, summary> {
+class BitEnumAttrBase<list<BitEnumAttrCase> cases, string summary> :
+    SignlessIntegerAttrBase<I32, summary> {
   let predicate = And<[
     I32Attr.predicate,
     // Make sure we don't have unknown bit set.
     CPred<"!($_self.cast<::mlir::IntegerAttr>().getValue().getZExtValue() & (~("
           # !interleave(!foreach(case, cases, case.value # "u"), "|") #
           ")))">
   ]>;
+}
 
-  let returnType = cppNamespace # "::" # name;
+class BitEnumAttr<string name, string summary, list<BitEnumAttrCase> cases> :
+    EnumAttrInfo<name, cases, BitEnumAttrBase<cases, summary>> {
   let underlyingType = "uint32_t";
-  let convertFromStorage = "static_cast<" # returnType # ">($_self.getInt())";
-  let constBuilderCall =
-          "$_builder.getI32IntegerAttr(static_cast<int32_t>($0))";
 
   // We need to return a string because we may concatenate symbols for multiple
   // bits together.
   let symbolToStringFnRetType = "std::string";
 
   // The delimiter used to separate bit enum cases in strings.
   string separator = "|";
 }

mlir/include/mlir/TableGen/Attribute.h

public:
   StringRef getSymbolToStringFnRetType() const;
 
   // Returns the name of the utilit function that returns the max enum value
   // used within the enum class.
   StringRef getMaxEnumValFnName() const;
 
   // Returns all allowed cases for this enum attribute.
   std::vector<EnumAttrCase> getAllCases() const;
+
+  bool genSpecializedAttr() const;
+  llvm::Record *getBaseAttrClass() const;
+  StringRef getSpecializedAttrClassName() const;
 };
 
 class StructFieldAttr {
 public:
   explicit StructFieldAttr(const llvm::Record *record);
   explicit StructFieldAttr(const llvm::Record &record);
   explicit StructFieldAttr(const llvm::DefInit *init);
 

mlir/lib/Conversion/SCFToSPIRV/SCFToSPIRV.cpp

ForOpConversion::matchAndRewrite(scf::ForOp forOp, ArrayRef<Value> operands,
                                  ConversionPatternRewriter &rewriter) const {
   // scf::ForOp can be lowered to the structured control flow represented by
   // spirv::LoopOp by making the continue block of the spirv::LoopOp the loop
   // latch and the merge block the exit block. The resulting spirv::LoopOp has a
   // single back edge from the continue to header block, and a single exit from
   // header to merge.
   scf::ForOpAdaptor forOperands(operands);
   auto loc = forOp.getLoc();
-  auto loopControl = rewriter.getI32IntegerAttr(
-      static_cast<uint32_t>(spirv::LoopControl::None));
-  auto loopOp = rewriter.create<spirv::LoopOp>(loc, loopControl);
+  auto loopOp = rewriter.create<spirv::LoopOp>(loc, spirv::LoopControl::None);
   loopOp.addEntryAndMergeBlock();
 
   OpBuilder::InsertionGuard guard(rewriter);
   // Create the block for the header.
   auto *header = new Block();
   // Insert the header.
   loopOp.body().getBlocks().insert(std::next(loopOp.body().begin(), 1), header);
 
IfOpConversion::matchAndRewrite(scf::IfOp ifOp, ArrayRef<Value> operands,
                                 ConversionPatternRewriter &rewriter) const {
   // When lowering `scf::IfOp` we explicitly create a selection header block
   // before the control flow diverges and a merge block where control flow
   // subsequently converges.
   scf::IfOpAdaptor ifOperands(operands);
   auto loc = ifOp.getLoc();
 
   // Create `spv.selection` operation, selection header block and merge block.
-  auto selectionControl = rewriter.getI32IntegerAttr(
-      static_cast<uint32_t>(spirv::SelectionControl::None));
-  auto selectionOp = rewriter.create<spirv::SelectionOp>(loc, selectionControl);
+  auto selectionOp =
+      rewriter.create<spirv::SelectionOp>(loc, spirv::SelectionControl::None);
   auto *mergeBlock =
       rewriter.createBlock(&selectionOp.body(), selectionOp.body().end());
   rewriter.create<spirv::MergeOp>(loc);
 
   OpBuilder::InsertionGuard guard(rewriter);
   auto *selectionHeaderBlock =
       rewriter.createBlock(&selectionOp.body().front());
 

mlir/lib/Conversion/SPIRVToLLVM/SPIRVToLLVM.cpp

public:
   matchAndRewrite(SPIRVOp operation, ArrayRef<Value> operands,
                   ConversionPatternRewriter &rewriter) const override {
 
     auto dstType = this->typeConverter.convertType(operation.getType());
     if (!dstType)
       return failure();
 
     rewriter.template replaceOpWithNewOp<LLVM::FCmpOp>(
-        operation, dstType,
-        rewriter.getI64IntegerAttr(static_cast<int64_t>(predicate)),
-        operation.operand1(), operation.operand2(),
-        LLVM::FMFAttr::get({}, operation.getContext()));
+        operation, dstType, predicate, operation.operand1(),
+        operation.operand2());
     return success();
   }
 };
 
 /// Converts SPIR-V integer comparisons to llvm.icmp "predicate"
 template <typename SPIRVOp, LLVM::ICmpPredicate predicate>
 class IComparePattern : public SPIRVToLLVMConversion<SPIRVOp> {
 public:
   using SPIRVToLLVMConversion<SPIRVOp>::SPIRVToLLVMConversion;
 
   LogicalResult
   matchAndRewrite(SPIRVOp operation, ArrayRef<Value> operands,
                   ConversionPatternRewriter &rewriter) const override {
 
     auto dstType = this->typeConverter.convertType(operation.getType());
     if (!dstType)
       return failure();
 
     rewriter.template replaceOpWithNewOp<LLVM::ICmpOp>(
-        operation, dstType,
-        rewriter.getI64IntegerAttr(static_cast<int64_t>(predicate)),
-        operation.operand1(), operation.operand2());
+        operation, dstType, predicate, operation.operand1(),
+        operation.operand2());
     return success();
   }
 };
 
 class InverseSqrtPattern
     : public SPIRVToLLVMConversion<spirv::GLSLInverseSqrtOp> {
 public:
   using SPIRVToLLVMConversion<spirv::GLSLInverseSqrtOp>::SPIRVToLLVMConversion;

mlir/lib/Conversion/StandardToLLVM/StandardToLLVM.cpp

struct CmpIOpLowering : public ConvertOpToLLVMPattern<CmpIOp> {
 
   LogicalResult
   matchAndRewrite(CmpIOp cmpiOp, ArrayRef<Value> operands,
                   ConversionPatternRewriter &rewriter) const override {
     CmpIOpAdaptor transformed(operands);
 
     rewriter.replaceOpWithNewOp<LLVM::ICmpOp>(
         cmpiOp, typeConverter->convertType(cmpiOp.getResult().getType()),
-        rewriter.getI64IntegerAttr(static_cast<int64_t>(
-            convertCmpPredicate<LLVM::ICmpPredicate>(cmpiOp.getPredicate()))),
+        convertCmpPredicate<LLVM::ICmpPredicate>(cmpiOp.getPredicate()),
         transformed.lhs(), transformed.rhs());
 
     return success();
   }
 };
 
 struct CmpFOpLowering : public ConvertOpToLLVMPattern<CmpFOp> {
   using ConvertOpToLLVMPattern<CmpFOp>::ConvertOpToLLVMPattern;
 
   LogicalResult
   matchAndRewrite(CmpFOp cmpfOp, ArrayRef<Value> operands,
                   ConversionPatternRewriter &rewriter) const override {
     CmpFOpAdaptor transformed(operands);
 
-    auto fmf = LLVM::FMFAttr::get({}, cmpfOp.getContext());
     rewriter.replaceOpWithNewOp<LLVM::FCmpOp>(
         cmpfOp, typeConverter->convertType(cmpfOp.getResult().getType()),
-        rewriter.getI64IntegerAttr(static_cast<int64_t>(
-            convertCmpPredicate<LLVM::FCmpPredicate>(cmpfOp.getPredicate()))),
-        transformed.lhs(), transformed.rhs(), fmf);
+        convertCmpPredicate<LLVM::FCmpPredicate>(cmpfOp.getPredicate()),
+        transformed.lhs(), transformed.rhs());
 
     return success();
   }
 };
 
 struct SIToFPLowering
     : public OneToOneConvertToLLVMPattern<SIToFPOp, LLVM::SIToFPOp> {
   using Super::Super;

mlir/lib/Conversion/StandardToSPIRV/StandardToSPIRV.cpp

IntLoadOpPattern::matchAndRewrite(LoadOp loadOp, ArrayRef<Value> operands,
   // Assume that getElementPtr() works linearizely. If it's a scalar, the method
   // still returns a linearized accessing. If the accessing is not linearized,
   // there will be offset issues.
   assert(accessChainOp.indices().size() == 2);
   Value adjustedPtr = adjustAccessChainForBitwidth(typeConverter, accessChainOp,
                                                    srcBits, dstBits, rewriter);
   Value spvLoadOp = rewriter.create<spirv::LoadOp>(
       loc, dstType, adjustedPtr,
-      loadOp->getAttrOfType<IntegerAttr>(
+      loadOp->getAttrOfType<spirv::MemoryAccessAttr>(
           spirv::attributeName<spirv::MemoryAccess>()),
       loadOp->getAttrOfType<IntegerAttr>("alignment"));
 
   // Shift the bits to the rightmost.
   // ____XXXX________ -> ____________XXXX
   Value lastDim = accessChainOp->getOperand(accessChainOp.getNumOperands() - 1);
   Value offset = getOffsetForBitwidth(loc, lastDim, srcBits, dstBits, rewriter);
   Value result = rewriter.create<spirv::ShiftRightArithmeticOp>(

mlir/lib/Dialect/GPU/Transforms/ParallelLoopMapper.cpp

 StringRef getMappingAttrName() { return "mapping"; }
 
 ParallelLoopDimMapping getParallelLoopDimMappingAttr(Processor processor,
                                                      AffineMap map,
                                                      AffineMap bound) {
   MLIRContext *context = map.getContext();
   OpBuilder builder(context);
   return ParallelLoopDimMapping::get(
-      builder.getI64IntegerAttr(static_cast<int32_t>(processor)),
+      ProcessorAttr::get(builder.getContext(), processor),
       AffineMapAttr::get(map), AffineMapAttr::get(bound), context);
 }
 
 LogicalResult setMappingAttr(scf::ParallelOp ploopOp,
                              ArrayRef<ParallelLoopDimMapping> mapping) {
   // Verify that each processor is mapped to only once.
   llvm::DenseSet<gpu::Processor> specifiedMappings;
   for (auto dimAttr : mapping) {

mlir/lib/Dialect/SPIRV/IR/SPIRVEnums.cpp

 //===- SPIRVEnums.cpp - MLIR SPIR-V Enums ---------------------------------===//
 //
 // 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 C/C++ enums from SPIR-V spec.
 //
 //===----------------------------------------------------------------------===//
 
 #include "mlir/Dialect/SPIRV/IR/SPIRVEnums.h"
 
+#include "mlir/IR/BuiltinTypes.h"
+
 #include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSwitch.h"
 
 using namespace mlir;
 
 // Pull in all enum utility function definitions

mlir/lib/Dialect/SPIRV/IR/SPIRVOps.cpp

 // spv.EntryPoint
 //===----------------------------------------------------------------------===//
 
 void spirv::EntryPointOp::build(OpBuilder &builder, OperationState &state,
                                 spirv::ExecutionModel executionModel,
                                 spirv::FuncOp function,
                                 ArrayRef<Attribute> interfaceVars) {
   build(builder, state,
-        builder.getI32IntegerAttr(static_cast<int32_t>(executionModel)),
+        spirv::ExecutionModelAttr::get(builder.getContext(), executionModel),
         builder.getSymbolRefAttr(function),
         builder.getArrayAttr(interfaceVars));
 }
 
 static ParseResult parseEntryPointOp(OpAsmParser &parser,
                                      OperationState &state) {
   spirv::ExecutionModel execModel;
   SmallVector<OpAsmParser::OperandType, 0> identifiers;

 // spv.ExecutionMode
 //===----------------------------------------------------------------------===//
 
 void spirv::ExecutionModeOp::build(OpBuilder &builder, OperationState &state,
                                    spirv::FuncOp function,
                                    spirv::ExecutionMode executionMode,
                                    ArrayRef<int32_t> params) {
   build(builder, state, builder.getSymbolRefAttr(function),
-        builder.getI32IntegerAttr(static_cast<int32_t>(executionMode)),
+        spirv::ExecutionModeAttr::get(builder.getContext(), executionMode),
         builder.getI32ArrayAttr(params));
 }
 
 static ParseResult parseExecutionModeOp(OpAsmParser &parser,
                                         OperationState &state) {
   spirv::ExecutionMode execMode;
   Attribute fn;
   if (parser.parseAttribute(fn, kFnNameAttrName, state.attributes) ||
static LogicalResult verify(spirv::GroupNonUniformElectOp groupOp) {
   return success();
 }
 
 //===----------------------------------------------------------------------===//
 // spv.LoadOp
 //===----------------------------------------------------------------------===//
 
 void spirv::LoadOp::build(OpBuilder &builder, OperationState &state,
-                          Value basePtr, IntegerAttr memory_access,
+                          Value basePtr, MemoryAccessAttr memoryAccess,
                           IntegerAttr alignment) {
   auto ptrType = basePtr.getType().cast<spirv::PointerType>();
-  build(builder, state, ptrType.getPointeeType(), basePtr, memory_access,
+  build(builder, state, ptrType.getPointeeType(), basePtr, memoryAccess,
         alignment);
 }
 
 static ParseResult parseLoadOp(OpAsmParser &parser, OperationState &state) {
   // Parse the storage class specification
   spirv::StorageClass storageClass;
   OpAsmParser::OperandType ptrInfo;
   Type elementType;
void spirv::SelectionOp::addMergeBlock() {
 
   // Add a spv.mlir.merge op into the merge block.
   builder.create<spirv::MergeOp>(getLoc());
 }
 
 spirv::SelectionOp spirv::SelectionOp::createIfThen(
     Location loc, Value condition,
     function_ref<void(OpBuilder &builder)> thenBody, OpBuilder &builder) {
-  auto selectionControl = builder.getI32IntegerAttr(
-      static_cast<uint32_t>(spirv::SelectionControl::None));
-  auto selectionOp = builder.create<spirv::SelectionOp>(loc, selectionControl);
+  auto selectionOp =
+      builder.create<spirv::SelectionOp>(loc, spirv::SelectionControl::None);
 
   selectionOp.addMergeBlock();
   Block *mergeBlock = selectionOp.getMergeBlock();
   Block *thenBlock = nullptr;
 
   // Build the "then" block.
   {
     OpBuilder::InsertionGuard guard(builder);

mlir/lib/TableGen/Attribute.cpp

std::vector<EnumAttrCase> EnumAttr::getAllCases() const {
 
   for (const llvm::Init *init : *inits) {
     cases.push_back(EnumAttrCase(cast<llvm::DefInit>(init)));
   }
 
   return cases;
 }
 
+bool EnumAttr::genSpecializedAttr() const {
+  return def->getValueAsBit("genSpecializedAttr");
+}
+
+llvm::Record *EnumAttr::getBaseAttrClass() const {
+  return def->getValueAsDef("baseAttrClass");
+}
+
+StringRef EnumAttr::getSpecializedAttrClassName() const {
+  return def->getValueAsString("specializedAttrClassName");
+}
+
 StructFieldAttr::StructFieldAttr(const llvm::Record *record) : def(record) {
   assert(def->isSubClassOf("StructFieldAttr") &&
          "must be subclass of TableGen 'StructFieldAttr' class");
 }
 
 StructFieldAttr::StructFieldAttr(const llvm::Record &record)
     : StructFieldAttr(&record) {}
 

mlir/lib/Target/SPIRV/Deserialization/DeserializeOps.cpp

 template <>
 LogicalResult
 Deserializer::processOp<spirv::EntryPointOp>(ArrayRef<uint32_t> words) {
   unsigned wordIndex = 0;
   if (wordIndex >= words.size()) {
     return emitError(unknownLoc,
                      "missing Execution Model specification in OpEntryPoint");
   }
-  auto execModel = opBuilder.getI32IntegerAttr(words[wordIndex++]);
+  auto execModel = spirv::ExecutionModelAttr::get(
+      context, static_cast<spirv::ExecutionModel>(words[wordIndex++]));
   if (wordIndex >= words.size()) {
     return emitError(unknownLoc, "missing <id> in OpEntryPoint");
   }
   // Get the function <id>
   auto fnID = words[wordIndex++];
   // Get the function name
   auto fnName = decodeStringLiteral(words, wordIndex);
   // Verify that the function <id> matches the fnName
Deserializer::processOp<spirv::ExecutionModeOp>(ArrayRef<uint32_t> words) {
   auto fn = getFunction(fnID);
   if (!fn) {
     return emitError(unknownLoc, "no function matching <id> ") << fnID;
   }
   // Get the Execution mode
   if (wordIndex >= words.size()) {
     return emitError(unknownLoc, "missing Execution Mode in OpExecutionMode");
   }
-  auto execMode = opBuilder.getI32IntegerAttr(words[wordIndex++]);
+  auto execMode = spirv::ExecutionModeAttr::get(
+      context, static_cast<spirv::ExecutionMode>(words[wordIndex++]));
 
   // Get the values
   SmallVector<Attribute, 4> attrListElems;
   while (wordIndex < words.size()) {
     attrListElems.push_back(opBuilder.getI32IntegerAttr(words[wordIndex++]));
   }
   auto values = opBuilder.getArrayAttr(attrListElems);
   opBuilder.create<spirv::ExecutionModeOp>(
for (auto operand : operands) {
     if (!argAttr) {
       return emitError(unknownLoc,
                        "expected 32-bit integer constant from <id> ")
              << operand << " for OpControlBarrier";
     }
     argAttrs.push_back(argAttr);
   }
 
-  opBuilder.create<spirv::ControlBarrierOp>(unknownLoc, argAttrs[0],
-                                            argAttrs[1], argAttrs[2]);
+  opBuilder.create<spirv::ControlBarrierOp>(
+      unknownLoc, argAttrs[0].cast<spirv::ScopeAttr>(),
+      argAttrs[1].cast<spirv::ScopeAttr>(),
+      argAttrs[2].cast<spirv::MemorySemanticsAttr>());
+
   return success();
 }
 
 template <>
 LogicalResult
 Deserializer::processOp<spirv::FunctionCallOp>(ArrayRef<uint32_t> operands) {
   if (operands.size() < 3) {
     return emitError(unknownLoc,
for (auto operand : operands) {
     if (!argAttr) {
       return emitError(unknownLoc,
                        "expected 32-bit integer constant from <id> ")
              << operand << " for OpMemoryBarrier";
     }
     argAttrs.push_back(argAttr);
   }
 
-  opBuilder.create<spirv::MemoryBarrierOp>(unknownLoc, argAttrs[0],
-                                           argAttrs[1]);
+  opBuilder.create<spirv::MemoryBarrierOp>(
+      unknownLoc, argAttrs[0].cast<spirv::ScopeAttr>(),
+      argAttrs[1].cast<spirv::MemorySemanticsAttr>());
   return success();
 }
 
 template <>
 LogicalResult
 Deserializer::processOp<spirv::CopyMemoryOp>(ArrayRef<uint32_t> words) {
   SmallVector<Type, 1> resultTypes;
   size_t wordIndex = 0;

mlir/lib/Target/SPIRV/Deserialization/Deserializer.cpp

 } // namespace
 
 spirv::SelectionOp
 ControlFlowStructurizer::createSelectionOp(uint32_t selectionControl) {
   // Create a builder and set the insertion point to the beginning of the
   // merge block so that the newly created SelectionOp will be inserted there.
   OpBuilder builder(&mergeBlock->front());
 
-  auto control = builder.getI32IntegerAttr(selectionControl);
+  auto control = static_cast<spirv::SelectionControl>(selectionControl);
   auto selectionOp = builder.create<spirv::SelectionOp>(location, control);
   selectionOp.addMergeBlock();
 
   return selectionOp;
 }
 
 spirv::LoopOp ControlFlowStructurizer::createLoopOp(uint32_t loopControl) {
   // Create a builder and set the insertion point to the beginning of the
   // merge block so that the newly created LoopOp will be inserted there.
   OpBuilder builder(&mergeBlock->front());
 
-  auto control = builder.getI32IntegerAttr(loopControl);
+  auto control = static_cast<spirv::LoopControl>(loopControl);
   auto loopOp = builder.create<spirv::LoopOp>(location, control);
   loopOp.addEntryAndMergeBlock();
 
   return loopOp;
 }
 
 void ControlFlowStructurizer::collectBlocksInConstruct() {
   assert(constructBlocks.empty() && "expected empty constructBlocks");

mlir/test/lib/Dialect/Test/TestOps.td

 }
 
 def OneResultOp3 : TEST_Op<"one_result3"> {
   let arguments = (ins F32);
   let results = (outs I32:$result1);
 }
 
 // Test using multi-result op as a whole
-def : Pat<(ThreeResultOp MultiResultOpKind1),
-          (AnotherThreeResultOp MultiResultOpKind1)>;
+def : Pat<(ThreeResultOp MultiResultOpKind1:$kind),
+          (AnotherThreeResultOp $kind)>;
 
 // Test using multi-result op as a whole for partial replacement
-def : Pattern<(ThreeResultOp MultiResultOpKind2),
-              [(TwoResultOp MultiResultOpKind2),
-               (OneResultOp1 MultiResultOpKind2)]>;
-def : Pattern<(ThreeResultOp MultiResultOpKind3),
-              [(OneResultOp2 MultiResultOpKind3),
-               (AnotherTwoResultOp MultiResultOpKind3)]>;
+def : Pattern<(ThreeResultOp MultiResultOpKind2:$kind),
+              [(TwoResultOp $kind),
+               (OneResultOp1 $kind)]>;
+def : Pattern<(ThreeResultOp MultiResultOpKind3:$kind),
+              [(OneResultOp2 $kind),
+               (AnotherTwoResultOp $kind)]>;
 
 // Test using results separately in a multi-result op
-def : Pattern<(ThreeResultOp MultiResultOpKind4),
-              [(TwoResultOp:$res1__0 MultiResultOpKind4),
-               (OneResultOp1 MultiResultOpKind4),
-               (TwoResultOp:$res2__1 MultiResultOpKind4)]>;
+def : Pattern<(ThreeResultOp MultiResultOpKind4:$kind),
+              [(TwoResultOp:$res1__0 $kind),
+               (OneResultOp1 $kind),
+               (TwoResultOp:$res2__1 $kind)]>;
 
 // Test referencing a single value in the value pack
 // This rule only matches TwoResultOp if its second result has no use.
-def : Pattern<(TwoResultOp:$res MultiResultOpKind5),
-              [(OneResultOp2 MultiResultOpKind5),
-               (OneResultOp1 MultiResultOpKind5)],
+def : Pattern<(TwoResultOp:$res MultiResultOpKind5:$kind),
+              [(OneResultOp2 $kind),
+               (OneResultOp1 $kind)],
               [(HasNoUseOf:$res__1)]>;
 
 // Test using auxiliary ops for replacing multi-result op
 def : Pattern<
-    (ThreeResultOp MultiResultOpKind6), [
+    (ThreeResultOp MultiResultOpKind6:$kind), [
         // Auxiliary op generated to help building the final result but not
         // directly used to replace the source op's results.
-        (TwoResultOp:$interm MultiResultOpKind6),
+        (TwoResultOp:$interm $kind),
 
         (OneResultOp3 $interm__1),
-        (AnotherTwoResultOp MultiResultOpKind6)
+        (AnotherTwoResultOp $kind)
     ]>;
 
 //===----------------------------------------------------------------------===//
 // Test Patterns (Variadic Ops)
 
 def OneVResOneVOperandOp1 : TEST_Op<"one_variadic_out_one_variadic_in1"> {
   let arguments = (ins Variadic<I32>);
   let results = (outs Variadic<I32>);

mlir/tools/mlir-tblgen/EnumsGen.cpp

 //===- EnumsGen.cpp - MLIR enum utility generator -------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 //
 // EnumsGen generates common utility functions for enums.
 //
 //===----------------------------------------------------------------------===//
 
 #include "mlir/TableGen/Attribute.h"
+#include "mlir/TableGen/Format.h"
 #include "mlir/TableGen/GenInfo.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/TableGen/Error.h"
 #include "llvm/TableGen/Record.h"
 #include "llvm/TableGen/TableGenBackend.h"
 
 using llvm::formatv;
 using llvm::isDigit;
+using llvm::PrintFatalError;
 using llvm::raw_ostream;
 using llvm::Record;
 using llvm::RecordKeeper;
 using llvm::StringRef;
+using mlir::tblgen::Attribute;
 using mlir::tblgen::EnumAttr;
 using mlir::tblgen::EnumAttrCase;
+using mlir::tblgen::FmtContext;
+using mlir::tblgen::tgfmt;
 
 static std::string makeIdentifier(StringRef str) {
   if (!str.empty() && isDigit(static_cast<unsigned char>(str.front()))) {
     std::string newStr = std::string("_") + str.str();
     return newStr;
   }
   return str.str();
 }
for (const auto &enumerant : enumerants) {
     os << formatv("  case {0}: return {1}::{2};\n", value, enumName,
                   makeIdentifier(symbol));
   }
   os << "  default: return ::llvm::None;\n"
      << "  }\n"
      << "}\n\n";
 }
 
+static void emitSpecializedAttrDef(const Record &enumDef, raw_ostream &os) {
+  EnumAttr enumAttr(enumDef);
+  StringRef enumName = enumAttr.getEnumClassName();
+  StringRef symToStrFnName = enumAttr.getSymbolToStringFnName();
+  StringRef strToSymFnName = enumAttr.getStringToSymbolFnName();
+  StringRef attrClassName = enumAttr.getSpecializedAttrClassName();
+  auto *baseAttrDef = enumAttr.getBaseAttrClass();
+  Attribute baseAttr(baseAttrDef);
+
+  // Emit classof method
+
+  os << formatv("bool {0}::classof(::mlir::Attribute attr) {{\n",
+                attrClassName);
+  os << "  if (!attr) return false;\n";
+
+  auto baseAttrPred = baseAttr.getPredicate();
+  if (baseAttrPred.isNull())
+    PrintFatalError("ERROR: baseAttrClass for EnumAttr has no Predicate\n");
+
+  auto condition = baseAttrPred.getCondition();
+  FmtContext verifyCtx;
+  verifyCtx.withSelf("attr");
+  os << tgfmt("  return $0;\n", /*ctx=*/nullptr, tgfmt(condition, &verifyCtx));
+
+  os << "}\n";
+
+  // Emit get method
+
+  os << formatv("{0} {0}::get(::mlir::MLIRContext *context, {1} val) {{\n",
+                attrClassName, enumName);
+
+  if (enumAttr.isSubClassOf("StrEnumAttr")) {
+    os << formatv("  ::mlir::StringAttr baseAttr = "
+                  "::mlir::StringAttr::get(context, {0}(val));\n",
+                  symToStrFnName);
+  } else {
+    StringRef underlyingType = enumAttr.getUnderlyingType();
+
+    // Assuming that it is IntegerAttr constraint
+    int64_t bitwidth = 64;
+    if (baseAttrDef->getValue("valueType")) {
+      auto *valueTypeDef = baseAttrDef->getValueAsDef("valueType");
+      if (valueTypeDef->getValue("bitwidth")) {
+        bitwidth = valueTypeDef->getValueAsInt("bitwidth");
+      }
+    }
+
+    os << formatv("  ::mlir::IntegerType intType = "
+                  "::mlir::IntegerType::get(context, {0});\n",
+                  bitwidth);
+    os << formatv("  ::mlir::IntegerAttr baseAttr = "
+                  "::mlir::IntegerAttr::get(intType, static_cast<{0}>(val));\n",
+                  underlyingType);
+  }
+  os << formatv("  return baseAttr.cast<{0}>();\n", attrClassName);
+
+  os << "}\n";
+
+  // Emit getValue method
+
+  os << formatv("{0} {1}::getValue() const {{\n", enumName, attrClassName);
+
+  if (enumAttr.isSubClassOf("StrEnumAttr")) {
+    os << formatv("  const auto res = {0}(::mlir::StringAttr::getValue());\n",
+                  strToSymFnName);
+    os << "  return res.getValue();\n";
+  } else {
+    os << formatv("  return static_cast<{0}>(::mlir::IntegerAttr::getInt());\n",
+                  enumName);
+  }
+
+  os << "}\n";
+}
+
 static void emitUnderlyingToSymFnForBitEnum(const Record &enumDef,
                                             raw_ostream &os) {
   EnumAttr enumAttr(enumDef);
   StringRef enumName = enumAttr.getEnumClassName();
   std::string underlyingType = std::string(enumAttr.getUnderlyingType());
   StringRef underlyingToSymFnName = enumAttr.getUnderlyingToSymbolFnName();
   auto enumerants = enumAttr.getAllCases();
   auto allBitsUnsetCase = getAllBitsUnsetCase(enumerants);

 
 template <>
 inline ::llvm::Optional<{0}> symbolizeEnum<{0}>(::llvm::StringRef str) {
   return {1}(str);
 }
 )";
   os << formatv(symbolizeEnumStr, enumName, strToSymFnName);
 
+  const char *const attrClassDecl = R"(
+class {1} : public ::mlir::{2} {
+public:
+  using ValueType = {0};
+  using ::mlir::{2}::{2};
+  static bool classof(::mlir::Attribute attr);
+  static {1} get(::mlir::MLIRContext *context, {0} val);
+  {0} getValue() const;
+};
+)";
+  if (enumAttr.genSpecializedAttr()) {
+    StringRef attrClassName = enumAttr.getSpecializedAttrClassName();
+    StringRef baseAttrClassName =
+        enumAttr.isSubClassOf("StrEnumAttr") ? "StringAttr" : "IntegerAttr";
+    os << formatv(attrClassDecl, enumName, attrClassName, baseAttrClassName);
+  }
+
   for (auto ns : llvm::reverse(namespaces))
     os << "} // namespace " << ns << "\n";
 
   // Emit DenseMapInfo for this enum class
   emitDenseMapInfo(enumName, underlyingType, cppNamespace, os);
 }
 
 static bool emitEnumDecls(const RecordKeeper &recordKeeper, raw_ostream &os) {
if (enumAttr.isBitEnum()) {
     emitStrToSymFnForBitEnum(enumDef, os);
     emitUnderlyingToSymFnForBitEnum(enumDef, os);
   } else {
     emitSymToStrFnForIntEnum(enumDef, os);
     emitStrToSymFnForIntEnum(enumDef, os);
     emitUnderlyingToSymFnForIntEnum(enumDef, os);
   }
 
+  if (enumAttr.genSpecializedAttr())
+    emitSpecializedAttrDef(enumDef, os);
+
   for (auto ns : llvm::reverse(namespaces))
     os << "} // namespace " << ns << "\n";
   os << "\n";
 }
 
 static bool emitEnumDefs(const RecordKeeper &recordKeeper, raw_ostream &os) {
   llvm::emitSourceFileHeader("Enum Utility Definitions", os);
 

mlir/unittests/TableGen/EnumsGenTest.cpp

 //===- EnumsGenTest.cpp - TableGen EnumsGen Tests -------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
+#include "mlir/IR/BuiltinAttributes.h"
+#include "mlir/IR/BuiltinTypes.h"
+#include "mlir/IR/MLIRContext.h"
 #include "mlir/Support/LLVM.h"
+
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringSwitch.h"
+
 #include "gmock/gmock.h"
+
 #include <type_traits>
 
 /// Pull in generated enum utility declarations and definitions.
 #include "EnumsGenTest.h.inc"
+
 #include "EnumsGenTest.cpp.inc"
 
 /// Test namespaces and enum class/utility names.
 using Outer::Inner::ConvertToEnum;
 using Outer::Inner::ConvertToString;
 using Outer::Inner::StrEnum;
+using Outer::Inner::StrEnumAttr;
 
 TEST(EnumsGenTest, GeneratedStrEnumDefinition) {
   EXPECT_EQ(0u, static_cast<uint64_t>(StrEnum::CaseA));
   EXPECT_EQ(10u, static_cast<uint64_t>(StrEnum::CaseB));
 }
 
 TEST(EnumsGenTest, GeneratedI32EnumDefinition) {
   EXPECT_EQ(5u, static_cast<uint64_t>(I32Enum::Case5));
TEST(EnumsGenTest, GeneratedCustomStringToSymbolFn) {
 
   auto two = symbolizePrettyIntEnum("case_two");
   EXPECT_TRUE(two);
   EXPECT_EQ(*two, PrettyIntEnum::Case2);
 
   auto none = symbolizePrettyIntEnum("Case1");
   EXPECT_FALSE(none);
 }
+
+TEST(EnumsGenTest, GeneratedIntAttributeClass) {
+  mlir::MLIRContext ctx;
+  I32Enum rawVal = I32Enum::Case5;
+
+  I32EnumAttr enumAttr = I32EnumAttr::get(&ctx, rawVal);
+  EXPECT_NE(enumAttr, nullptr);
+  EXPECT_EQ(enumAttr.getValue(), rawVal);
+
+  mlir::Type intType = mlir::IntegerType::get(&ctx, 32);
+  mlir::Attribute intAttr = mlir::IntegerAttr::get(intType, 5);
+  EXPECT_TRUE(intAttr.isa<I32EnumAttr>());
+  EXPECT_EQ(intAttr, enumAttr);
+}
+
+TEST(EnumsGenTest, GeneratedStringAttributeClass) {
+  mlir::MLIRContext ctx;
+  StrEnum rawVal = StrEnum::CaseA;
+
+  StrEnumAttr enumAttr = StrEnumAttr::get(&ctx, rawVal);
+  EXPECT_NE(enumAttr, nullptr);
+  EXPECT_EQ(enumAttr.getValue(), rawVal);
+
+  mlir::Attribute strAttr = mlir::StringAttr::get(&ctx, "CaseA");
+  EXPECT_TRUE(strAttr.isa<StrEnumAttr>());
+  EXPECT_EQ(strAttr, enumAttr);
+}
+
+TEST(EnumsGenTest, GeneratedBitAttributeClass) {
+  mlir::MLIRContext ctx;
+
+  mlir::Type intType = mlir::IntegerType::get(&ctx, 32);
+  mlir::Attribute intAttr = mlir::IntegerAttr::get(
+      intType,
+      static_cast<uint32_t>(BitEnumWithNone::Bit1 | BitEnumWithNone::Bit3));
+  EXPECT_TRUE(intAttr.isa<BitEnumWithNoneAttr>());
+  EXPECT_TRUE(intAttr.isa<BitEnumWithoutNoneAttr>());
+}

mlir/unittests/TableGen/enums.td

 
 def CaseA: StrEnumAttrCase<"CaseA">;
 def CaseB: StrEnumAttrCase<"CaseB", 10>;
 
 def StrEnum: StrEnumAttr<"StrEnum", "A test enum", [CaseA, CaseB]> {
   let cppNamespace = "Outer::Inner";
   let stringToSymbolFnName = "ConvertToEnum";
   let symbolToStringFnName = "ConvertToString";
+  let genSpecializedAttr = 1;
 }
 
 def Case5: I32EnumAttrCase<"Case5", 5>;
 def Case10: I32EnumAttrCase<"Case10", 10>;
 
 def I32Enum: I32EnumAttr<"I32Enum", "A test enum", [Case5, Case10]>;
 
 def Bit0 : BitEnumAttrCase<"None", 0x0000>;