diff --git a/mlir/docs/OpDefinitions.md b/mlir/docs/OpDefinitions.md
--- a/mlir/docs/OpDefinitions.md
+++ b/mlir/docs/OpDefinitions.md
@@ -229,6 +229,17 @@
 indicate that all variable length operands have the same number of dynamic
 values.
 
+#### VariadicOfVariadic operands
+
+To declare a variadic operand that has a variadic number of sub-ranges, wrap the
+`TypeConstraint` for the operand with `VariadicOfVariadic<...,
+"<segment-attribute-name>">`.
+
+The second field of the `VariadicOfVariadic` is the name of an `I32ElementsAttr`
+argument that contains the sizes of the variadic sub-ranges. This attribute will
+be used when determining the size of sub-ranges, or when updating the size of
+sub-ranges.
+
 #### Optional operands
 
 To declare an optional operand, wrap the `TypeConstraint` for the operand with
@@ -717,6 +728,8 @@
     -   Single: `OpAsmParser::OperandType &`
     -   Optional: `Optional<OpAsmParser::OperandType> &`
     -   Variadic: `SmallVectorImpl<OpAsmParser::OperandType> &`
+    -   VariadicOfVariadic:
+        `SmallVectorImpl<SmallVector<OpAsmParser::OperandType>> &`
 *   Ref Directives
     -   A reference directive is passed to the parser using the same mapping as
         the input operand. For example, a single region would be passed as a
@@ -731,6 +744,7 @@
     -   Single: `Type &`
     -   Optional: `Type &`
     -   Variadic: `SmallVectorImpl<Type> &`
+    -   VariadicOfVariadic: `SmallVectorImpl<SmallVector<Type>> &`
 *   `attr-dict` Directive: `NamedAttrList &`
 
 When a variable is optional, the value should only be specified if the variable
@@ -749,6 +763,7 @@
     -   Single: `Value`
     -   Optional: `Value`
     -   Variadic: `OperandRange`
+    -   VariadicOfVariadic: `OperandRangeRange`
 *   Ref Directives
     -   A reference directive is passed to the printer using the same mapping as
         the input operand. For example, a single region would be passed as a
@@ -763,6 +778,7 @@
     -   Single: `Type`
     -   Optional: `Type`
     -   Variadic: `TypeRange`
+    -   VariadicOfVariadic: `TypeRangeRange`
 *   `attr-dict` Directive: `DictionaryAttr`
 
 When a variable is optional, the provided value may be null.
@@ -923,7 +939,7 @@
 
 When this boolean field is set to `true`, it indicates that the op implements a
 `canonicalize` method for simple "matchAndRewrite" style canonicalization
-patterns.  If `hasCanonicalizer` is 0, then an implementation of
+patterns. If `hasCanonicalizer` is 0, then an implementation of
 `::getCanonicalizationPatterns()` is implemented to call this function.
 
 ### `hasFolder`
diff --git a/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td b/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td
--- a/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td
+++ b/mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td
@@ -701,23 +701,25 @@
 def LLVM_SwitchOp : LLVM_TerminatorOp<"switch",
     [AttrSizedOperandSegments, DeclareOpInterfaceMethods<BranchOpInterface>,
      NoSideEffect]> {
-  let arguments = (ins I32:$value,
-                   Variadic<AnyType>:$defaultOperands,
-                   Variadic<AnyType>:$caseOperands,
-                   OptionalAttr<ElementsAttr>:$case_values,
-                   OptionalAttr<ElementsAttr>:$case_operand_offsets,
-                   OptionalAttr<ElementsAttr>:$branch_weights);
+  let arguments = (ins
+    I32:$value,
+    Variadic<AnyType>:$defaultOperands,
+    VariadicOfVariadic<AnyType, "case_operand_segments">:$caseOperands,
+    OptionalAttr<ElementsAttr>:$case_values,
+    ElementsAttr:$case_operand_segments,
+    OptionalAttr<ElementsAttr>:$branch_weights
+  );
   let successors = (successor
-                    AnySuccessor:$defaultDestination,
-                    VariadicSuccessor<AnySuccessor>:$caseDestinations);
+    AnySuccessor:$defaultDestination,
+    VariadicSuccessor<AnySuccessor>:$caseDestinations
+  );
 
   let verifier = [{ return ::verify(*this); }];
   let assemblyFormat = [{
     $value `,`
     $defaultDestination (`(` $defaultOperands^ `:` type($defaultOperands) `)`)?
     `[` `\n` custom<SwitchOpCases>($case_values, $caseDestinations,
-                                   $caseOperands, type($caseOperands),
-                                   $case_operand_offsets) `]`
+                                   $caseOperands, type($caseOperands)) `]`
     attr-dict
   }];
 
@@ -734,11 +736,15 @@
 
   let extraClassDeclaration = [{
     /// Return the operands for the case destination block at the given index.
-    OperandRange getCaseOperands(unsigned index);
+    OperandRange getCaseOperands(unsigned index) {
+      return caseOperands()[index];
+    }
 
     /// Return a mutable range of operands for the case destination block at the
     /// given index.
-    MutableOperandRange getCaseOperandsMutable(unsigned index);
+    MutableOperandRange getCaseOperandsMutable(unsigned index) {
+      return caseOperandsMutable()[index];
+    }
   }];
 }
 
diff --git a/mlir/include/mlir/Dialect/StandardOps/IR/Ops.td b/mlir/include/mlir/Dialect/StandardOps/IR/Ops.td
--- a/mlir/include/mlir/Dialect/StandardOps/IR/Ops.td
+++ b/mlir/include/mlir/Dialect/StandardOps/IR/Ops.td
@@ -1812,14 +1812,17 @@
     ```
   }];
 
-  let arguments = (ins AnyInteger:$flag,
-                       Variadic<AnyType>:$defaultOperands,
-                       Variadic<AnyType>:$caseOperands,
-                       OptionalAttr<AnyIntElementsAttr>:$case_values,
-                       OptionalAttr<I32ElementsAttr>:$case_operand_offsets);
+  let arguments = (ins
+    AnyInteger:$flag,
+    Variadic<AnyType>:$defaultOperands,
+    VariadicOfVariadic<AnyType, "case_operand_segments">:$caseOperands,
+    OptionalAttr<AnyIntElementsAttr>:$case_values,
+    I32ElementsAttr:$case_operand_segments
+  );
   let successors = (successor
-                        AnySuccessor:$defaultDestination,
-                        VariadicSuccessor<AnySuccessor>:$caseDestinations);
+    AnySuccessor:$defaultDestination,
+    VariadicSuccessor<AnySuccessor>:$caseDestinations
+  );
   let builders = [
     OpBuilder<(ins "Value":$flag,
       "Block *":$defaultDestination,
@@ -1849,19 +1852,22 @@
                             $case_values,
                             $caseDestinations,
                             $caseOperands,
-                            type($caseOperands),
-                            $case_operand_offsets)
+                            type($caseOperands))
    `]`
     attr-dict
   }];
 
   let extraClassDeclaration = [{
     /// Return the operands for the case destination block at the given index.
-    OperandRange getCaseOperands(unsigned index);
+    OperandRange getCaseOperands(unsigned index) {
+      return caseOperands()[index];
+    }
 
     /// Return a mutable range of operands for the case destination block at the
     /// given index.
-    MutableOperandRange getCaseOperandsMutable(unsigned index);
+    MutableOperandRange getCaseOperandsMutable(unsigned index) {
+      return caseOperandsMutable()[index];
+    }
   }];
 
   let hasCanonicalizer = 1;
diff --git a/mlir/include/mlir/IR/OpBase.td b/mlir/include/mlir/IR/OpBase.td
--- a/mlir/include/mlir/IR/OpBase.td
+++ b/mlir/include/mlir/IR/OpBase.td
@@ -324,6 +324,16 @@
   Type baseType = type;
 }
 
+// A nested variadic type constraint. It expands to zero or more variadic ranges
+// of the base type. This class is used for supporting variadic operands and
+// results. `variadicSegmentAttrName` should correspond to the name of an
+// I32ElementsAttr argument that provides the sizes of the inner variadic
+// operand groups.
+class VariadicOfVariadic<Type type, string variadicSegmentAttrName>
+    : Variadic<type> {
+  string segmentAttrName = variadicSegmentAttrName;
+}
+
 // An optional type constraint. It expands to either zero or one of the base
 // type. This class is used for supporting optional operands/results.
 class Optional<Type type> : TypeConstraint<type.predicate, type.summary> {
diff --git a/mlir/include/mlir/IR/OpDefinition.h b/mlir/include/mlir/IR/OpDefinition.h
--- a/mlir/include/mlir/IR/OpDefinition.h
+++ b/mlir/include/mlir/IR/OpDefinition.h
@@ -267,6 +267,9 @@
 LogicalResult verifyOneSuccessor(Operation *op);
 LogicalResult verifyNSuccessors(Operation *op, unsigned numSuccessors);
 LogicalResult verifyAtLeastNSuccessors(Operation *op, unsigned numSuccessors);
+LogicalResult verifyValueSizeAttr(Operation *op, StringRef attrName,
+                                  StringRef valueGroupName,
+                                  size_t expectedCount);
 LogicalResult verifyOperandSizeAttr(Operation *op, StringRef sizeAttrName);
 LogicalResult verifyResultSizeAttr(Operation *op, StringRef sizeAttrName);
 LogicalResult verifyNoRegionArguments(Operation *op);
diff --git a/mlir/include/mlir/IR/OperationSupport.h b/mlir/include/mlir/IR/OperationSupport.h
--- a/mlir/include/mlir/IR/OperationSupport.h
+++ b/mlir/include/mlir/IR/OperationSupport.h
@@ -36,12 +36,14 @@
 class Dialect;
 class DictionaryAttr;
 class ElementsAttr;
+class MutableOperandRangeRange;
 class Operation;
 struct OperationState;
 class OpAsmParser;
 class OpAsmParserResult;
 class OpAsmPrinter;
 class OperandRange;
+class OperandRangeRange;
 class OpFoldResult;
 class ParseResult;
 class Pattern;
@@ -727,6 +729,10 @@
   /// must not be empty.
   unsigned getBeginOperandIndex() const;
 
+  /// Split this range into a set of contiguous subranges using the given
+  /// elements attribute, which contains the sizes of the sub ranges.
+  OperandRangeRange split(ElementsAttr segmentSizes) const;
+
 private:
   /// See `llvm::detail::indexed_accessor_range_base` for details.
   static OpOperand *offset_base(OpOperand *object, ptrdiff_t index) {
@@ -741,6 +747,42 @@
   friend RangeBaseT;
 };
 
+//===----------------------------------------------------------------------===//
+// OperandRangeRange
+
+/// This class represents a contiguous range of operand ranges, e.g. from a
+/// VariadicOfVariadic operand group.
+class OperandRangeRange final
+    : public llvm::indexed_accessor_range<
+          OperandRangeRange, std::pair<OpOperand *, Attribute>, OperandRange,
+          OperandRange, OperandRange> {
+  using OwnerT = std::pair<OpOperand *, Attribute>;
+  using RangeBaseT =
+      llvm::indexed_accessor_range<OperandRangeRange, OwnerT, OperandRange,
+                                   OperandRange, OperandRange>;
+
+public:
+  using RangeBaseT::RangeBaseT;
+
+  /// Returns the range of types of the values within this range.
+  TypeRangeRange getTypes() const { return TypeRangeRange(*this); }
+  auto getType() const { return getTypes(); }
+
+  /// Construct a range given a parent set of operands, and an I32 elements
+  /// attribute containing the sizes of the sub ranges.
+  OperandRangeRange(OperandRange operands, Attribute operandSegments);
+
+  /// Flatten all of the sub ranges into a single contiguous operand range.
+  OperandRange join() const;
+
+private:
+  /// See `llvm::indexed_accessor_range` for details.
+  static OperandRange dereference(const OwnerT &object, ptrdiff_t index);
+
+  /// Allow access to `dereference_iterator`.
+  friend RangeBaseT;
+};
+
 //===----------------------------------------------------------------------===//
 // MutableOperandRange
 
@@ -761,8 +803,9 @@
   MutableOperandRange(Operation *owner);
 
   /// Slice this range into a sub range, with the additional operand segment.
-  MutableOperandRange slice(unsigned subStart, unsigned subLen,
-                            Optional<OperandSegment> segment = llvm::None);
+  MutableOperandRange
+  slice(unsigned subStart, unsigned subLen,
+        Optional<OperandSegment> segment = llvm::None) const;
 
   /// Append the given values to the range.
   void append(ValueRange values);
@@ -782,12 +825,19 @@
   /// Returns the current size of the range.
   unsigned size() const { return length; }
 
+  /// Returns if the current range is empty.
+  bool empty() const { return size() == 0; }
+
   /// Allow implicit conversion to an OperandRange.
   operator OperandRange() const;
 
   /// Returns the owning operation.
   Operation *getOwner() const { return owner; }
 
+  /// Split this range into a set of contiguous subranges using the given
+  /// elements attribute, which contains the sizes of the sub ranges.
+  MutableOperandRangeRange split(NamedAttribute segmentSizes) const;
+
 private:
   /// Update the length of this range to the one provided.
   void updateLength(unsigned newLength);
@@ -801,7 +851,46 @@
 
   /// Optional set of operand segments that should be updated when mutating the
   /// length of this range.
-  SmallVector<std::pair<unsigned, NamedAttribute>, 1> operandSegments;
+  SmallVector<OperandSegment, 1> operandSegments;
+};
+
+//===----------------------------------------------------------------------===//
+// MutableOperandRangeRange
+
+/// This class represents a contiguous range of mutable operand ranges, e.g.
+/// from a VariadicOfVariadic operand group.
+class MutableOperandRangeRange final
+    : public llvm::indexed_accessor_range<
+          MutableOperandRangeRange,
+          std::pair<MutableOperandRange, NamedAttribute>, MutableOperandRange,
+          MutableOperandRange, MutableOperandRange> {
+  using OwnerT = std::pair<MutableOperandRange, NamedAttribute>;
+  using RangeBaseT =
+      llvm::indexed_accessor_range<MutableOperandRangeRange, OwnerT,
+                                   MutableOperandRange, MutableOperandRange,
+                                   MutableOperandRange>;
+
+public:
+  using RangeBaseT::RangeBaseT;
+
+  /// Construct a range given a parent set of operands, and an I32 tensor
+  /// elements attribute containing the sizes of the sub ranges.
+  MutableOperandRangeRange(const MutableOperandRange &operands,
+                           NamedAttribute operandSegmentAttr);
+
+  /// Flatten all of the sub ranges into a single contiguous mutable operand
+  /// range.
+  MutableOperandRange join() const;
+
+  /// Allow implicit conversion to an OperandRangeRange.
+  operator OperandRangeRange() const;
+
+private:
+  /// See `llvm::indexed_accessor_range` for details.
+  static MutableOperandRange dereference(const OwnerT &object, ptrdiff_t index);
+
+  /// Allow access to `dereference_iterator`.
+  friend RangeBaseT;
 };
 
 //===----------------------------------------------------------------------===//
diff --git a/mlir/include/mlir/IR/TypeRange.h b/mlir/include/mlir/IR/TypeRange.h
--- a/mlir/include/mlir/IR/TypeRange.h
+++ b/mlir/include/mlir/IR/TypeRange.h
@@ -16,6 +16,7 @@
 #include "mlir/IR/Types.h"
 #include "mlir/IR/Value.h"
 #include "llvm/ADT/PointerUnion.h"
+#include "llvm/ADT/Sequence.h"
 
 namespace mlir {
 class OperandRange;
@@ -88,6 +89,35 @@
   return os;
 }
 
+//===----------------------------------------------------------------------===//
+// TypeRangeRange
+
+using TypeRangeRangeIterator =
+    llvm::mapped_iterator<llvm::iota_range<unsigned>::iterator,
+                          std::function<TypeRange(unsigned)>>;
+
+/// This class provides an abstraction for a range of TypeRange. This is useful
+/// when accessing the types of a range of ranges, such as when using
+/// OperandRangeRange.
+class TypeRangeRange : public llvm::iterator_range<TypeRangeRangeIterator> {
+public:
+  template <typename RangeT>
+  TypeRangeRange(const RangeT &range)
+      : TypeRangeRange(llvm::seq<unsigned>(0, range.size()), range) {}
+
+private:
+  template <typename RangeT>
+  TypeRangeRange(llvm::iota_range<unsigned> sizeRange, const RangeT &range)
+      : llvm::iterator_range<TypeRangeRangeIterator>(
+            {sizeRange.begin(), getRangeFn(range)},
+            {sizeRange.end(), nullptr}) {}
+
+  template <typename RangeT>
+  static std::function<TypeRange(unsigned)> getRangeFn(const RangeT &range) {
+    return [=](unsigned index) -> TypeRange { return TypeRange(range[index]); };
+  }
+};
+
 //===----------------------------------------------------------------------===//
 // ValueTypeRange
 
diff --git a/mlir/include/mlir/TableGen/Argument.h b/mlir/include/mlir/TableGen/Argument.h
--- a/mlir/include/mlir/TableGen/Argument.h
+++ b/mlir/include/mlir/TableGen/Argument.h
@@ -48,6 +48,8 @@
   bool isOptional() const;
   // Returns true if this operand/result is variadic.
   bool isVariadic() const;
+  // Returns true if this operand/result is a variadic of a variadic constraint.
+  bool isVariadicOfVariadic() const;
   // Returns true if this is a variable length type constraint. This is either
   // variadic or optional.
   bool isVariableLength() const { return isOptional() || isVariadic(); }
diff --git a/mlir/include/mlir/TableGen/Type.h b/mlir/include/mlir/TableGen/Type.h
--- a/mlir/include/mlir/TableGen/Type.h
+++ b/mlir/include/mlir/TableGen/Type.h
@@ -40,6 +40,13 @@
   // Returns true if this is a variadic type constraint.
   bool isVariadic() const;
 
+  // Returns true if this is a nested variadic type constraint.
+  bool isVariadicOfVariadic() const;
+
+  // Return the segment size attribute used if this is a variadic of variadic
+  // constraint. Asserts isVariadicOfVariadic() is true.
+  StringRef getVariadicOfVariadicSegmentSizeAttr() const;
+
   // Returns true if this is a variable length type constraint. This is either
   // variadic or optional.
   bool isVariableLength() const { return isOptional() || isVariadic(); }
diff --git a/mlir/lib/Conversion/AsyncToLLVM/AsyncToLLVM.cpp b/mlir/lib/Conversion/AsyncToLLVM/AsyncToLLVM.cpp
--- a/mlir/lib/Conversion/AsyncToLLVM/AsyncToLLVM.cpp
+++ b/mlir/lib/Conversion/AsyncToLLVM/AsyncToLLVM.cpp
@@ -520,7 +520,7 @@
         /*defaultOperands=*/ValueRange(),
         /*caseValues=*/caseValues,
         /*caseDestinations=*/caseDest,
-        /*caseOperands=*/ArrayRef<ValueRange>(),
+        /*caseOperands=*/ArrayRef<ValueRange>({ValueRange(), ValueRange()}),
         /*branchWeights=*/ArrayRef<int32_t>());
 
     return success();
diff --git a/mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp b/mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp
--- a/mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp
+++ b/mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp
@@ -32,6 +32,7 @@
 #include "llvm/Support/SourceMgr.h"
 
 #include <iostream>
+#include <numeric>
 
 using namespace mlir;
 using namespace mlir::LLVM;
@@ -235,41 +236,27 @@
                      ArrayRef<int32_t> caseValues, BlockRange caseDestinations,
                      ArrayRef<ValueRange> caseOperands,
                      ArrayRef<int32_t> branchWeights) {
-  SmallVector<Value> flattenedCaseOperands;
-  SmallVector<int32_t> caseOperandOffsets;
-  int32_t offset = 0;
-  for (ValueRange operands : caseOperands) {
-    flattenedCaseOperands.append(operands.begin(), operands.end());
-    caseOperandOffsets.push_back(offset);
-    offset += operands.size();
-  }
   ElementsAttr caseValuesAttr;
   if (!caseValues.empty())
     caseValuesAttr = builder.getI32VectorAttr(caseValues);
-  ElementsAttr caseOperandOffsetsAttr;
-  if (!caseOperandOffsets.empty())
-    caseOperandOffsetsAttr = builder.getI32VectorAttr(caseOperandOffsets);
 
   ElementsAttr weightsAttr;
   if (!branchWeights.empty())
     weightsAttr = builder.getI32VectorAttr(llvm::to_vector<4>(branchWeights));
 
-  build(builder, result, value, defaultOperands, flattenedCaseOperands,
-        caseValuesAttr, caseOperandOffsetsAttr, weightsAttr, defaultDestination,
-        caseDestinations);
+  build(builder, result, value, defaultOperands, caseOperands, caseValuesAttr,
+        weightsAttr, defaultDestination, caseDestinations);
 }
 
 /// <cases> ::= integer `:` bb-id (`(` ssa-use-and-type-list `)`)?
 ///             ( `,` integer `:` bb-id (`(` ssa-use-and-type-list `)`)? )?
-static ParseResult
-parseSwitchOpCases(OpAsmParser &parser, ElementsAttr &caseValues,
-                   SmallVectorImpl<Block *> &caseDestinations,
-                   SmallVectorImpl<OpAsmParser::OperandType> &caseOperands,
-                   SmallVectorImpl<Type> &caseOperandTypes,
-                   ElementsAttr &caseOperandOffsets) {
+static ParseResult parseSwitchOpCases(
+    OpAsmParser &parser, ElementsAttr &caseValues,
+    SmallVectorImpl<Block *> &caseDestinations,
+    SmallVectorImpl<SmallVector<OpAsmParser::OperandType>> &caseOperands,
+    SmallVectorImpl<SmallVector<Type>> &caseOperandTypes) {
   SmallVector<int32_t> values;
-  SmallVector<int32_t> offsets;
-  int32_t value, offset = 0;
+  int32_t value = 0;
   do {
     OptionalParseResult integerParseResult = parser.parseOptionalInteger(value);
     if (values.empty() && !integerParseResult.hasValue())
@@ -281,32 +268,28 @@
 
     Block *destination;
     SmallVector<OpAsmParser::OperandType> operands;
+    SmallVector<Type> operandTypes;
     if (parser.parseColon() || parser.parseSuccessor(destination))
       return failure();
     if (!parser.parseOptionalLParen()) {
       if (parser.parseRegionArgumentList(operands) ||
-          parser.parseColonTypeList(caseOperandTypes) || parser.parseRParen())
+          parser.parseColonTypeList(operandTypes) || parser.parseRParen())
         return failure();
     }
     caseDestinations.push_back(destination);
-    caseOperands.append(operands.begin(), operands.end());
-    offsets.push_back(offset);
-    offset += operands.size();
+    caseOperands.emplace_back(operands);
+    caseOperandTypes.emplace_back(operandTypes);
   } while (!parser.parseOptionalComma());
 
-  Builder &builder = parser.getBuilder();
-  caseValues = builder.getI32VectorAttr(values);
-  caseOperandOffsets = builder.getI32VectorAttr(offsets);
-
+  caseValues = parser.getBuilder().getI32VectorAttr(values);
   return success();
 }
 
 static void printSwitchOpCases(OpAsmPrinter &p, SwitchOp op,
                                ElementsAttr caseValues,
                                SuccessorRange caseDestinations,
-                               OperandRange caseOperands,
-                               TypeRange caseOperandTypes,
-                               ElementsAttr caseOperandOffsets) {
+                               OperandRangeRange caseOperands,
+                               TypeRangeRange caseOperandTypes) {
   if (!caseValues)
     return;
 
@@ -317,7 +300,7 @@
         p << "  ";
         p << std::get<0>(i).getLimitedValue();
         p << ": ";
-        p.printSuccessorAndUseList(std::get<1>(i), op.getCaseOperands(index++));
+        p.printSuccessorAndUseList(std::get<1>(i), caseOperands[index++]);
       },
       [&] {
         p << ',';
@@ -341,28 +324,6 @@
   return success();
 }
 
-OperandRange SwitchOp::getCaseOperands(unsigned index) {
-  return getCaseOperandsMutable(index);
-}
-
-MutableOperandRange SwitchOp::getCaseOperandsMutable(unsigned index) {
-  MutableOperandRange caseOperands = caseOperandsMutable();
-  if (!case_operand_offsets()) {
-    assert(caseOperands.size() == 0 &&
-           "non-empty case operands must have offsets");
-    return caseOperands;
-  }
-
-  ElementsAttr offsets = case_operand_offsets().getValue();
-  assert(index < offsets.size() && "invalid case operand offset index");
-
-  int64_t begin = offsets.getValue(index).cast<IntegerAttr>().getInt();
-  int64_t end = index + 1 == offsets.size()
-                    ? caseOperands.size()
-                    : offsets.getValue(index + 1).cast<IntegerAttr>().getInt();
-  return caseOperandsMutable().slice(begin, end - begin);
-}
-
 Optional<MutableOperandRange>
 SwitchOp::getMutableSuccessorOperands(unsigned index) {
   assert(index < getNumSuccessors() && "invalid successor index");
diff --git a/mlir/lib/Dialect/StandardOps/IR/Ops.cpp b/mlir/lib/Dialect/StandardOps/IR/Ops.cpp
--- a/mlir/lib/Dialect/StandardOps/IR/Ops.cpp
+++ b/mlir/lib/Dialect/StandardOps/IR/Ops.cpp
@@ -28,6 +28,7 @@
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/raw_ostream.h"
+#include <numeric>
 
 #include "mlir/Dialect/StandardOps/IR/OpsDialect.cpp.inc"
 
@@ -2130,21 +2131,8 @@
                      DenseIntElementsAttr caseValues,
                      BlockRange caseDestinations,
                      ArrayRef<ValueRange> caseOperands) {
-  SmallVector<Value> flattenedCaseOperands;
-  SmallVector<int32_t> caseOperandOffsets;
-  int32_t offset = 0;
-  for (ValueRange operands : caseOperands) {
-    flattenedCaseOperands.append(operands.begin(), operands.end());
-    caseOperandOffsets.push_back(offset);
-    offset += operands.size();
-  }
-  DenseIntElementsAttr caseOperandOffsetsAttr;
-  if (!caseOperandOffsets.empty())
-    caseOperandOffsetsAttr = builder.getI32VectorAttr(caseOperandOffsets);
-
-  build(builder, result, value, defaultOperands, flattenedCaseOperands,
-        caseValues, caseOperandOffsetsAttr, defaultDestination,
-        caseDestinations);
+  build(builder, result, value, defaultOperands, caseOperands, caseValues,
+        defaultDestination, caseDestinations);
 }
 
 void SwitchOp::build(OpBuilder &builder, OperationState &result, Value value,
@@ -2163,16 +2151,14 @@
 
 /// <cases> ::= `default` `:` bb-id (`(` ssa-use-and-type-list `)`)?
 ///             ( `,` integer `:` bb-id (`(` ssa-use-and-type-list `)`)? )*
-static ParseResult
-parseSwitchOpCases(OpAsmParser &parser, Type &flagType,
-                   Block *&defaultDestination,
-                   SmallVectorImpl<OpAsmParser::OperandType> &defaultOperands,
-                   SmallVectorImpl<Type> &defaultOperandTypes,
-                   DenseIntElementsAttr &caseValues,
-                   SmallVectorImpl<Block *> &caseDestinations,
-                   SmallVectorImpl<OpAsmParser::OperandType> &caseOperands,
-                   SmallVectorImpl<Type> &caseOperandTypes,
-                   DenseIntElementsAttr &caseOperandOffsets) {
+static ParseResult parseSwitchOpCases(
+    OpAsmParser &parser, Type &flagType, Block *&defaultDestination,
+    SmallVectorImpl<OpAsmParser::OperandType> &defaultOperands,
+    SmallVectorImpl<Type> &defaultOperandTypes,
+    DenseIntElementsAttr &caseValues,
+    SmallVectorImpl<Block *> &caseDestinations,
+    SmallVectorImpl<SmallVector<OpAsmParser::OperandType>> &caseOperands,
+    SmallVectorImpl<SmallVector<Type>> &caseOperandTypes) {
   if (failed(parser.parseKeyword("default")) || failed(parser.parseColon()) ||
       failed(parser.parseSuccessor(defaultDestination)))
     return failure();
@@ -2184,9 +2170,7 @@
   }
 
   SmallVector<APInt> values;
-  SmallVector<int32_t> offsets;
   unsigned bitWidth = flagType.getIntOrFloatBitWidth();
-  int64_t offset = 0;
   while (succeeded(parser.parseOptionalComma())) {
     int64_t value = 0;
     if (failed(parser.parseInteger(value)))
@@ -2195,30 +2179,26 @@
 
     Block *destination;
     SmallVector<OpAsmParser::OperandType> operands;
+    SmallVector<Type> operandTypes;
     if (failed(parser.parseColon()) ||
         failed(parser.parseSuccessor(destination)))
       return failure();
     if (succeeded(parser.parseOptionalLParen())) {
       if (failed(parser.parseRegionArgumentList(operands)) ||
-          failed(parser.parseColonTypeList(caseOperandTypes)) ||
+          failed(parser.parseColonTypeList(operandTypes)) ||
           failed(parser.parseRParen()))
         return failure();
     }
     caseDestinations.push_back(destination);
-    caseOperands.append(operands.begin(), operands.end());
-    offsets.push_back(offset);
-    offset += operands.size();
+    caseOperands.emplace_back(operands);
+    caseOperandTypes.emplace_back(operandTypes);
   }
 
-  if (values.empty())
-    return success();
-
-  Builder &builder = parser.getBuilder();
-  ShapedType caseValueType =
-      VectorType::get(static_cast<int64_t>(values.size()), flagType);
-  caseValues = DenseIntElementsAttr::get(caseValueType, values);
-  caseOperandOffsets = builder.getI32VectorAttr(offsets);
-
+  if (!values.empty()) {
+    ShapedType caseValueType =
+        VectorType::get(static_cast<int64_t>(values.size()), flagType);
+    caseValues = DenseIntElementsAttr::get(caseValueType, values);
+  }
   return success();
 }
 
@@ -2226,8 +2206,7 @@
     OpAsmPrinter &p, SwitchOp op, Type flagType, Block *defaultDestination,
     OperandRange defaultOperands, TypeRange defaultOperandTypes,
     DenseIntElementsAttr caseValues, SuccessorRange caseDestinations,
-    OperandRange caseOperands, TypeRange caseOperandTypes,
-    ElementsAttr caseOperandOffsets) {
+    OperandRangeRange caseOperands, TypeRangeRange caseOperandTypes) {
   p << "  default: ";
   p.printSuccessorAndUseList(defaultDestination, defaultOperands);
 
@@ -2240,7 +2219,7 @@
     p << "  ";
     p << caseValues.getValue<APInt>(i).getLimitedValue();
     p << ": ";
-    p.printSuccessorAndUseList(caseDestinations[i], op.getCaseOperands(i));
+    p.printSuccessorAndUseList(caseDestinations[i], caseOperands[i]);
   }
   p.printNewline();
 }
@@ -2268,28 +2247,6 @@
   return success();
 }
 
-OperandRange SwitchOp::getCaseOperands(unsigned index) {
-  return getCaseOperandsMutable(index);
-}
-
-MutableOperandRange SwitchOp::getCaseOperandsMutable(unsigned index) {
-  MutableOperandRange caseOperands = caseOperandsMutable();
-  if (!case_operand_offsets()) {
-    assert(caseOperands.size() == 0 &&
-           "non-empty case operands must have offsets");
-    return caseOperands;
-  }
-
-  ElementsAttr offsets = case_operand_offsets().getValue();
-  assert(index < offsets.size() && "invalid case operand offset index");
-
-  int64_t begin = offsets.getValue(index).cast<IntegerAttr>().getInt();
-  int64_t end = index + 1 == offsets.size()
-                    ? caseOperands.size()
-                    : offsets.getValue(index + 1).cast<IntegerAttr>().getInt();
-  return caseOperandsMutable().slice(begin, end - begin);
-}
-
 Optional<MutableOperandRange>
 SwitchOp::getMutableSuccessorOperands(unsigned index) {
   assert(index < getNumSuccessors() && "invalid successor index");
diff --git a/mlir/lib/IR/Operation.cpp b/mlir/lib/IR/Operation.cpp
--- a/mlir/lib/IR/Operation.cpp
+++ b/mlir/lib/IR/Operation.cpp
@@ -996,16 +996,19 @@
   return success();
 }
 
-static LogicalResult verifyValueSizeAttr(Operation *op, StringRef attrName,
-                                         bool isOperand) {
+LogicalResult OpTrait::impl::verifyValueSizeAttr(Operation *op,
+                                                 StringRef attrName,
+                                                 StringRef valueGroupName,
+                                                 size_t expectedCount) {
   auto sizeAttr = op->getAttrOfType<DenseIntElementsAttr>(attrName);
   if (!sizeAttr)
-    return op->emitOpError("requires 1D vector attribute '") << attrName << "'";
+    return op->emitOpError("requires 1D i32 elements attribute '")
+           << attrName << "'";
 
-  auto sizeAttrType = sizeAttr.getType().dyn_cast<VectorType>();
-  if (!sizeAttrType || sizeAttrType.getRank() != 1 ||
+  auto sizeAttrType = sizeAttr.getType();
+  if (sizeAttrType.getRank() != 1 ||
       !sizeAttrType.getElementType().isInteger(32))
-    return op->emitOpError("requires 1D vector of i32 attribute '")
+    return op->emitOpError("requires 1D i32 elements attribute '")
            << attrName << "'";
 
   if (llvm::any_of(sizeAttr.getIntValues(), [](const APInt &element) {
@@ -1018,25 +1021,22 @@
       sizeAttr.begin(), sizeAttr.end(), 0,
       [](unsigned all, APInt one) { return all + one.getZExtValue(); });
 
-  if (isOperand && totalCount != op->getNumOperands())
-    return op->emitOpError("operand count (")
-           << op->getNumOperands() << ") does not match with the total size ("
-           << totalCount << ") specified in attribute '" << attrName << "'";
-  else if (!isOperand && totalCount != op->getNumResults())
-    return op->emitOpError("result count (")
-           << op->getNumResults() << ") does not match with the total size ("
-           << totalCount << ") specified in attribute '" << attrName << "'";
+  if (totalCount != expectedCount)
+    return op->emitOpError()
+           << valueGroupName << " count (" << expectedCount
+           << ") does not match with the total size (" << totalCount
+           << ") specified in attribute '" << attrName << "'";
   return success();
 }
 
 LogicalResult OpTrait::impl::verifyOperandSizeAttr(Operation *op,
                                                    StringRef attrName) {
-  return verifyValueSizeAttr(op, attrName, /*isOperand=*/true);
+  return verifyValueSizeAttr(op, attrName, "operand", op->getNumOperands());
 }
 
 LogicalResult OpTrait::impl::verifyResultSizeAttr(Operation *op,
                                                   StringRef attrName) {
-  return verifyValueSizeAttr(op, attrName, /*isOperand=*/false);
+  return verifyValueSizeAttr(op, attrName, "result", op->getNumResults());
 }
 
 LogicalResult OpTrait::impl::verifyNoRegionArguments(Operation *op) {
diff --git a/mlir/lib/IR/OperationSupport.cpp b/mlir/lib/IR/OperationSupport.cpp
--- a/mlir/lib/IR/OperationSupport.cpp
+++ b/mlir/lib/IR/OperationSupport.cpp
@@ -12,9 +12,11 @@
 //===----------------------------------------------------------------------===//
 
 #include "mlir/IR/OperationSupport.h"
+#include "mlir/IR/BuiltinAttributes.h"
 #include "mlir/IR/BuiltinTypes.h"
 #include "mlir/IR/OpDefinition.h"
 #include "llvm/ADT/BitVector.h"
+#include <numeric>
 
 using namespace mlir;
 
@@ -394,13 +396,38 @@
 OperandRange::OperandRange(Operation *op)
     : OperandRange(op->getOpOperands().data(), op->getNumOperands()) {}
 
-/// Return the operand index of the first element of this range. The range
-/// must not be empty.
 unsigned OperandRange::getBeginOperandIndex() const {
   assert(!empty() && "range must not be empty");
   return base->getOperandNumber();
 }
 
+OperandRangeRange OperandRange::split(ElementsAttr segmentSizes) const {
+  return OperandRangeRange(*this, segmentSizes);
+}
+
+//===----------------------------------------------------------------------===//
+// OperandRangeRange
+
+OperandRangeRange::OperandRangeRange(OperandRange operands,
+                                     Attribute operandSegments)
+    : OperandRangeRange(OwnerT(operands.getBase(), operandSegments), 0,
+                        operandSegments.cast<DenseElementsAttr>().size()) {}
+
+OperandRange OperandRangeRange::join() const {
+  const OwnerT &owner = getBase();
+  auto sizeData = owner.second.cast<DenseElementsAttr>().getValues<uint32_t>();
+  return OperandRange(owner.first,
+                      std::accumulate(sizeData.begin(), sizeData.end(), 0));
+}
+
+OperandRange OperandRangeRange::dereference(const OwnerT &object,
+                                            ptrdiff_t index) {
+  auto sizeData = object.second.cast<DenseElementsAttr>().getValues<uint32_t>();
+  uint32_t startIndex =
+      std::accumulate(sizeData.begin(), sizeData.begin() + index, 0);
+  return OperandRange(object.first + startIndex, *(sizeData.begin() + index));
+}
+
 //===----------------------------------------------------------------------===//
 // MutableOperandRange
 
@@ -419,7 +446,7 @@
 /// Slice this range into a sub range, with the additional operand segment.
 MutableOperandRange
 MutableOperandRange::slice(unsigned subStart, unsigned subLen,
-                           Optional<OperandSegment> segment) {
+                           Optional<OperandSegment> segment) const {
   assert((subStart + subLen) <= length && "invalid sub-range");
   MutableOperandRange subSlice(owner, start + subStart, subLen,
                                operandSegments);
@@ -475,6 +502,11 @@
   return owner->getOperands().slice(start, length);
 }
 
+MutableOperandRangeRange
+MutableOperandRange::split(NamedAttribute segmentSizes) const {
+  return MutableOperandRangeRange(*this, segmentSizes);
+}
+
 /// Update the length of this range to the one provided.
 void MutableOperandRange::updateLength(unsigned newLength) {
   int32_t diff = int32_t(newLength) - int32_t(length);
@@ -490,6 +522,35 @@
   }
 }
 
+//===----------------------------------------------------------------------===//
+// MutableOperandRangeRange
+
+MutableOperandRangeRange::MutableOperandRangeRange(
+    const MutableOperandRange &operands, NamedAttribute operandSegmentAttr)
+    : MutableOperandRangeRange(
+          OwnerT(operands, operandSegmentAttr), 0,
+          operandSegmentAttr.second.cast<DenseElementsAttr>().size()) {}
+
+MutableOperandRange MutableOperandRangeRange::join() const {
+  return getBase().first;
+}
+
+MutableOperandRangeRange::operator OperandRangeRange() const {
+  return OperandRangeRange(getBase().first,
+                           getBase().second.second.cast<DenseElementsAttr>());
+}
+
+MutableOperandRange MutableOperandRangeRange::dereference(const OwnerT &object,
+                                                          ptrdiff_t index) {
+  auto sizeData =
+      object.second.second.cast<DenseElementsAttr>().getValues<uint32_t>();
+  uint32_t startIndex =
+      std::accumulate(sizeData.begin(), sizeData.begin() + index, 0);
+  return object.first.slice(
+      startIndex, *(sizeData.begin() + index),
+      MutableOperandRange::OperandSegment(index, object.second));
+}
+
 //===----------------------------------------------------------------------===//
 // ValueRange
 
diff --git a/mlir/lib/TableGen/Argument.cpp b/mlir/lib/TableGen/Argument.cpp
--- a/mlir/lib/TableGen/Argument.cpp
+++ b/mlir/lib/TableGen/Argument.cpp
@@ -12,6 +12,10 @@
 using namespace mlir;
 using namespace mlir::tblgen;
 
+//===----------------------------------------------------------------------===//
+// NamedTypeConstraint
+//===----------------------------------------------------------------------===//
+
 bool NamedTypeConstraint::hasPredicate() const {
   return !constraint.getPredicate().isNull();
 }
@@ -19,3 +23,7 @@
 bool NamedTypeConstraint::isOptional() const { return constraint.isOptional(); }
 
 bool NamedTypeConstraint::isVariadic() const { return constraint.isVariadic(); }
+
+bool NamedTypeConstraint::isVariadicOfVariadic() const {
+  return constraint.isVariadicOfVariadic();
+}
diff --git a/mlir/lib/TableGen/Operator.cpp b/mlir/lib/TableGen/Operator.cpp
--- a/mlir/lib/TableGen/Operator.cpp
+++ b/mlir/lib/TableGen/Operator.cpp
@@ -458,6 +458,13 @@
     results.push_back({name, TypeConstraint(resultDef)});
     if (!name.empty())
       argumentsAndResultsIndex[name] = resultIndex(i);
+
+    // We currently only support VariadicOfVariadic operands.
+    if (results.back().constraint.isVariadicOfVariadic()) {
+      PrintFatalError(
+          def.getLoc(),
+          "'VariadicOfVariadic' results are currently not supported");
+    }
   }
 
   // Handle successors
@@ -577,8 +584,7 @@
 
 StringRef Operator::getAssemblyFormat() const {
   return TypeSwitch<llvm::Init *, StringRef>(def.getValueInit("assemblyFormat"))
-      .Case<llvm::StringInit>(
-          [&](auto *init) { return init->getValue(); });
+      .Case<llvm::StringInit>([&](auto *init) { return init->getValue(); });
 }
 
 void Operator::print(llvm::raw_ostream &os) const {
diff --git a/mlir/lib/TableGen/Type.cpp b/mlir/lib/TableGen/Type.cpp
--- a/mlir/lib/TableGen/Type.cpp
+++ b/mlir/lib/TableGen/Type.cpp
@@ -36,6 +36,15 @@
   return def->isSubClassOf("Variadic");
 }
 
+bool TypeConstraint::isVariadicOfVariadic() const {
+  return def->isSubClassOf("VariadicOfVariadic");
+}
+
+StringRef TypeConstraint::getVariadicOfVariadicSegmentSizeAttr() const {
+  assert(isVariadicOfVariadic());
+  return def->getValueAsString("segmentAttrName");
+}
+
 // Returns the builder call for this constraint if this is a buildable type,
 // returns None otherwise.
 Optional<StringRef> TypeConstraint::getBuilderCall() const {
diff --git a/mlir/test/IR/traits.mlir b/mlir/test/IR/traits.mlir
--- a/mlir/test/IR/traits.mlir
+++ b/mlir/test/IR/traits.mlir
@@ -375,28 +375,28 @@
 // -----
 
 func @failedMissingOperandSizeAttr(%arg: i32) {
-  // expected-error @+1 {{requires 1D vector attribute 'operand_segment_sizes'}}
+  // expected-error @+1 {{requires 1D i32 elements attribute 'operand_segment_sizes'}}
   "test.attr_sized_operands"(%arg, %arg, %arg, %arg) : (i32, i32, i32, i32) -> ()
 }
 
 // -----
 
 func @failedOperandSizeAttrWrongType(%arg: i32) {
-  // expected-error @+1 {{requires 1D vector of i32 attribute 'operand_segment_sizes'}}
-  "test.attr_sized_operands"(%arg, %arg, %arg, %arg) {operand_segment_sizes = dense<[1, 1, 1, 1]>: tensor<4xi32>} : (i32, i32, i32, i32) -> ()
+  // expected-error @+1 {{requires 1D i32 elements attribute 'operand_segment_sizes'}}
+  "test.attr_sized_operands"(%arg, %arg, %arg, %arg) {operand_segment_sizes = 10} : (i32, i32, i32, i32) -> ()
 }
 
 // -----
 
 func @failedOperandSizeAttrWrongRank(%arg: i32) {
-  // expected-error @+1 {{requires 1D vector of i32 attribute 'operand_segment_sizes'}}
+  // expected-error @+1 {{requires 1D i32 elements attribute 'operand_segment_sizes'}}
   "test.attr_sized_operands"(%arg, %arg, %arg, %arg) {operand_segment_sizes = dense<[[1, 1], [1, 1]]>: vector<2x2xi32>} : (i32, i32, i32, i32) -> ()
 }
 
 // -----
 
 func @failedOperandSizeAttrWrongElementType(%arg: i32) {
-  // expected-error @+1 {{requires 1D vector of i32 attribute 'operand_segment_sizes'}}
+  // expected-error @+1 {{requires 1D i32 elements attribute 'operand_segment_sizes'}}
   "test.attr_sized_operands"(%arg, %arg, %arg, %arg) {operand_segment_sizes = dense<[1, 1, 1, 1]>: vector<4xi64>} : (i32, i32, i32, i32) -> ()
 }
 
@@ -432,28 +432,28 @@
 // -----
 
 func @failedMissingResultSizeAttr() {
-  // expected-error @+1 {{requires 1D vector attribute 'result_segment_sizes'}}
+  // expected-error @+1 {{requires 1D i32 elements attribute 'result_segment_sizes'}}
   %0:4 = "test.attr_sized_results"() : () -> (i32, i32, i32, i32)
 }
 
 // -----
 
 func @failedResultSizeAttrWrongType() {
-  // expected-error @+1 {{requires 1D vector of i32 attribute 'result_segment_sizes'}}
-  %0:4 = "test.attr_sized_results"() {result_segment_sizes = dense<[1, 1, 1, 1]>: tensor<4xi32>} : () -> (i32, i32, i32, i32)
+  // expected-error @+1 {{requires 1D i32 elements attribute 'result_segment_sizes'}}
+  %0:4 = "test.attr_sized_results"() {result_segment_sizes = 10} : () -> (i32, i32, i32, i32)
 }
 
 // -----
 
 func @failedResultSizeAttrWrongRank() {
-  // expected-error @+1 {{requires 1D vector of i32 attribute 'result_segment_sizes'}}
+  // expected-error @+1 {{requires 1D i32 elements attribute 'result_segment_sizes'}}
   %0:4 = "test.attr_sized_results"() {result_segment_sizes = dense<[[1, 1], [1, 1]]>: vector<2x2xi32>} : () -> (i32, i32, i32, i32)
 }
 
 // -----
 
 func @failedResultSizeAttrWrongElementType() {
-  // expected-error @+1 {{requires 1D vector of i32 attribute 'result_segment_sizes'}}
+  // expected-error @+1 {{requires 1D i32 elements attribute 'result_segment_sizes'}}
   %0:4 = "test.attr_sized_results"() {result_segment_sizes = dense<[1, 1, 1, 1]>: vector<4xi64>} : () -> (i32, i32, i32, i32)
 }
 
diff --git a/mlir/test/lib/Dialect/Test/TestOps.td b/mlir/test/lib/Dialect/Test/TestOps.td
--- a/mlir/test/lib/Dialect/Test/TestOps.td
+++ b/mlir/test/lib/Dialect/Test/TestOps.td
@@ -1661,6 +1661,14 @@
   let arguments = (ins Variadic<I64>:$operand);
   let assemblyFormat = [{ $operand `:` type($operand) attr-dict}];
 }
+def FormatVariadicOfVariadicOperand
+   : TEST_Op<"format_variadic_of_variadic_operand"> {
+  let arguments = (ins
+    VariadicOfVariadic<I64, "operand_segments">:$operand,
+    I32ElementsAttr:$operand_segments
+  );
+  let assemblyFormat = [{ $operand `:` type($operand) attr-dict}];
+}
 
 def FormatMultipleVariadicOperands :
     TEST_Op<"format_multiple_variadic_operands", [AttrSizedOperandSegments]> {
diff --git a/mlir/test/mlir-tblgen/op-format.mlir b/mlir/test/mlir-tblgen/op-format.mlir
--- a/mlir/test/mlir-tblgen/op-format.mlir
+++ b/mlir/test/mlir-tblgen/op-format.mlir
@@ -151,6 +151,9 @@
 // CHECK: test.format_variadic_operand %[[I64]], %[[I64]], %[[I64]] : i64, i64, i64
 test.format_variadic_operand %i64, %i64, %i64 : i64, i64, i64
 
+// CHECK: test.format_variadic_of_variadic_operand (%[[I64]], %[[I64]]), (), (%[[I64]]) : (i64, i64), (), (i64)
+test.format_variadic_of_variadic_operand (%i64, %i64), (), (%i64) : (i64, i64), (), (i64)
+
 // CHECK: test.format_multiple_variadic_operands (%[[I64]], %[[I64]], %[[I64]]), (%[[I64]], %[[I32]] : i64, i32)
 test.format_multiple_variadic_operands (%i64, %i64, %i64), (%i64, %i32 : i64, i32)
 
diff --git a/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp b/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp
--- a/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp
+++ b/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp
@@ -24,6 +24,7 @@
 #include "llvm/ADT/MapVector.h"
 #include "llvm/ADT/Sequence.h"
 #include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/StringSet.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/TableGen/Error.h"
 #include "llvm/TableGen/Record.h"
@@ -89,6 +90,23 @@
   unsigned size = *(sizeAttrValues.begin() + index);
   return {start, size};
 )";
+// The logic to calculate the actual value range for a declared operand
+// of an op with variadic of variadic operands within the OpAdaptor.
+//
+// {0}: The name of the segment attribute.
+// {1}: The index of the main operand.
+const char *variadicOfVariadicAdaptorCalcCode = R"(
+  auto tblgenTmpOperands = getODSOperands({1});
+  auto sizeAttrValues = {0}().getValues<uint32_t>();
+  auto sizeAttrIt = sizeAttrValues.begin();
+
+  ::llvm::SmallVector<::mlir::ValueRange> tblgenTmpOperandGroups;
+  for (int i = 0, e = ::llvm::size(sizeAttrValues); i < e; ++i, ++sizeAttrIt) {{
+    tblgenTmpOperandGroups.push_back(tblgenTmpOperands.take_front(*sizeAttrIt));
+    tblgenTmpOperands = tblgenTmpOperands.drop_front(*sizeAttrIt);
+  }
+  return tblgenTmpOperandGroups;
+)";
 
 // The logic to build a range of either operand or result values.
 //
@@ -256,16 +274,20 @@
   // Builds the parameter list for build() method of this op. This method writes
   // to `paramList` the comma-separated parameter list and updates
   // `resultTypeNames` with the names for parameters for specifying result
-  // types. The given `typeParamKind` and `attrParamKind` controls how result
-  // types and attributes are placed in the parameter list.
+  // types. `inferredAttributes` is populated with any attributes that are
+  // elided from the build list. The given `typeParamKind` and `attrParamKind`
+  // controls how result types and attributes are placed in the parameter list.
   void buildParamList(llvm::SmallVectorImpl<OpMethodParameter> &paramList,
+                      llvm::StringSet<> &inferredAttributes,
                       SmallVectorImpl<std::string> &resultTypeNames,
                       TypeParamKind typeParamKind,
                       AttrParamKind attrParamKind = AttrParamKind::WrappedAttr);
 
   // Adds op arguments and regions into operation state for build() methods.
-  void genCodeForAddingArgAndRegionForBuilder(OpMethodBody &body,
-                                              bool isRawValueAttr = false);
+  void
+  genCodeForAddingArgAndRegionForBuilder(OpMethodBody &body,
+                                         llvm::StringSet<> &inferredAttributes,
+                                         bool isRawValueAttr = false);
 
   // Generates canonicalizer declaration for the operation.
   void genCanonicalizerDecls();
@@ -783,7 +805,7 @@
 // of ops, in particular for one-operand ops that may not have the
 // `getOperand(unsigned)` method.
 static void generateNamedOperandGetters(const Operator &op, Class &opClass,
-                                        StringRef sizeAttrInit,
+                                        bool isAdaptor, StringRef sizeAttrInit,
                                         StringRef rangeType,
                                         StringRef rangeBeginCall,
                                         StringRef rangeSizeCall,
@@ -838,6 +860,20 @@
       m->body()
           << "  auto operands = getODSOperands(" << i << ");\n"
           << "  return operands.empty() ? ::mlir::Value() : *operands.begin();";
+    } else if (operand.isVariadicOfVariadic()) {
+      StringRef segmentAttr =
+          operand.constraint.getVariadicOfVariadicSegmentSizeAttr();
+      if (isAdaptor) {
+        m = opClass.addMethodAndPrune("::llvm::SmallVector<::mlir::ValueRange>",
+                                      operand.name);
+        m->body() << llvm::formatv(variadicOfVariadicAdaptorCalcCode,
+                                   segmentAttr, i);
+        continue;
+      }
+
+      m = opClass.addMethodAndPrune("::mlir::OperandRangeRange", operand.name);
+      m->body() << "  return getODSOperands(" << i << ").split(" << segmentAttr
+                << "Attr());";
     } else if (operand.isVariadic()) {
       m = opClass.addMethodAndPrune(rangeType, operand.name);
       m->body() << "  return getODSOperands(" << i << ");";
@@ -860,6 +896,7 @@
 
   generateNamedOperandGetters(
       op, opClass,
+      /*isAdaptor=*/false,
       /*sizeAttrInit=*/attrSizeInitCode,
       /*rangeType=*/"::mlir::Operation::operand_range",
       /*rangeBeginCall=*/"getOperation()->operand_begin()",
@@ -874,17 +911,32 @@
     const auto &operand = op.getOperand(i);
     if (operand.name.empty())
       continue;
-    auto *m = opClass.addMethodAndPrune("::mlir::MutableOperandRange",
+    auto *m = opClass.addMethodAndPrune(operand.isVariadicOfVariadic()
+                                            ? "::mlir::MutableOperandRangeRange"
+                                            : "::mlir::MutableOperandRange",
                                         (operand.name + "Mutable").str());
     auto &body = m->body();
     body << "  auto range = getODSOperandIndexAndLength(" << i << ");\n"
-         << "  return ::mlir::MutableOperandRange(getOperation(), "
+         << "  auto mutableRange = ::mlir::MutableOperandRange(getOperation(), "
             "range.first, range.second";
     if (attrSizedOperands)
       body << ", ::mlir::MutableOperandRange::OperandSegment(" << i
            << "u, *getOperation()->getAttrDictionary().getNamed("
               "operand_segment_sizesAttrName()))";
     body << ");\n";
+
+    // If this operand is a nested variadic, we split the range into a
+    // MutableOperandRangeRange that provides a range over all of the
+    // sub-ranges.
+    if (operand.isVariadicOfVariadic()) {
+      body << "  return "
+              "mutableRange.split(*(*this)->getAttrDictionary().getNamed("
+           << operand.constraint.getVariadicOfVariadicSegmentSizeAttr()
+           << "AttrName()));\n";
+    } else {
+      // Otherwise, we use the full range directly.
+      body << "  return mutableRange;\n";
+    }
   }
 }
 
@@ -1038,7 +1090,9 @@
                   bool inferType) {
     llvm::SmallVector<OpMethodParameter, 4> paramList;
     llvm::SmallVector<std::string, 4> resultNames;
-    buildParamList(paramList, resultNames, paramKind, attrType);
+    llvm::StringSet<> inferredAttributes;
+    buildParamList(paramList, inferredAttributes, resultNames, paramKind,
+                   attrType);
 
     auto *m = opClass.addMethodAndPrune("void", "build", OpMethod::MP_Static,
                                         std::move(paramList));
@@ -1046,8 +1100,9 @@
     if (!m)
       return;
     auto &body = m->body();
-    genCodeForAddingArgAndRegionForBuilder(
-        body, /*isRawValueAttr=*/attrType == AttrParamKind::UnwrappedValue);
+    genCodeForAddingArgAndRegionForBuilder(body, inferredAttributes,
+                                           /*isRawValueAttr=*/attrType ==
+                                               AttrParamKind::UnwrappedValue);
 
     // Push all result types to the operation state
 
@@ -1215,7 +1270,9 @@
 void OpEmitter::genUseOperandAsResultTypeSeparateParamBuilder() {
   llvm::SmallVector<OpMethodParameter, 4> paramList;
   llvm::SmallVector<std::string, 4> resultNames;
-  buildParamList(paramList, resultNames, TypeParamKind::None);
+  llvm::StringSet<> inferredAttributes;
+  buildParamList(paramList, inferredAttributes, resultNames,
+                 TypeParamKind::None);
 
   auto *m = opClass.addMethodAndPrune("void", "build", OpMethod::MP_Static,
                                       std::move(paramList));
@@ -1223,7 +1280,7 @@
   if (!m)
     return;
   auto &body = m->body();
-  genCodeForAddingArgAndRegionForBuilder(body);
+  genCodeForAddingArgAndRegionForBuilder(body, inferredAttributes);
 
   auto numResults = op.getNumResults();
   if (numResults == 0)
@@ -1415,6 +1472,7 @@
 }
 
 void OpEmitter::buildParamList(SmallVectorImpl<OpMethodParameter> &paramList,
+                               llvm::StringSet<> &inferredAttributes,
                                SmallVectorImpl<std::string> &resultTypeNames,
                                TypeParamKind typeParamKind,
                                AttrParamKind attrParamKind) {
@@ -1453,10 +1511,6 @@
   }
 
   // Add parameters for all arguments (operands and attributes).
-
-  int numOperands = 0;
-  int numAttrs = 0;
-
   int defaultValuedAttrStartIndex = op.getNumArgs();
   if (attrParamKind == AttrParamKind::UnwrappedValue) {
     // Calculate the start index from which we can attach default values in the
@@ -1482,54 +1536,68 @@
     }
   }
 
-  for (int i = 0, e = op.getNumArgs(); i < e; ++i) {
-    auto argument = op.getArg(i);
-    if (argument.is<tblgen::NamedTypeConstraint *>()) {
-      const auto &operand = op.getOperand(numOperands);
-      StringRef type =
-          operand.isVariadic() ? "::mlir::ValueRange" : "::mlir::Value";
-      OpMethodParameter::Property properties = OpMethodParameter::PP_None;
-      if (operand.isOptional())
-        properties = OpMethodParameter::PP_Optional;
+  /// Collect any inferred attributes.
+  for (const NamedTypeConstraint &operand : op.getOperands()) {
+    if (operand.isVariadicOfVariadic()) {
+      inferredAttributes.insert(
+          operand.constraint.getVariadicOfVariadicSegmentSizeAttr());
+    }
+  }
 
-      paramList.emplace_back(type, getArgumentName(op, numOperands),
-                             properties);
-      ++numOperands;
-    } else {
-      const auto &namedAttr = op.getAttribute(numAttrs);
-      const auto &attr = namedAttr.attr;
+  for (int i = 0, e = op.getNumArgs(), numOperands = 0; i < e; ++i) {
+    Argument arg = op.getArg(i);
+    if (const auto *operand = arg.dyn_cast<NamedTypeConstraint *>()) {
+      StringRef type;
+      if (operand->isVariadicOfVariadic())
+        type = "::llvm::ArrayRef<::mlir::ValueRange>";
+      else if (operand->isVariadic())
+        type = "::mlir::ValueRange";
+      else
+        type = "::mlir::Value";
 
       OpMethodParameter::Property properties = OpMethodParameter::PP_None;
-      if (attr.isOptional())
+      if (operand->isOptional())
         properties = OpMethodParameter::PP_Optional;
+      paramList.emplace_back(type, getArgumentName(op, numOperands++),
+                             properties);
+      continue;
+    }
+    const NamedAttribute &namedAttr = *arg.get<NamedAttribute *>();
+    const Attribute &attr = namedAttr.attr;
 
-      StringRef type;
-      switch (attrParamKind) {
-      case AttrParamKind::WrappedAttr:
+    // inferred attributes don't need to be added to the param list.
+    if (inferredAttributes.contains(namedAttr.name))
+      continue;
+
+    OpMethodParameter::Property properties = OpMethodParameter::PP_None;
+    if (attr.isOptional())
+      properties = OpMethodParameter::PP_Optional;
+
+    StringRef type;
+    switch (attrParamKind) {
+    case AttrParamKind::WrappedAttr:
+      type = attr.getStorageType();
+      break;
+    case AttrParamKind::UnwrappedValue:
+      if (canUseUnwrappedRawValue(attr))
+        type = attr.getReturnType();
+      else
         type = attr.getStorageType();
-        break;
-      case AttrParamKind::UnwrappedValue:
-        if (canUseUnwrappedRawValue(attr))
-          type = attr.getReturnType();
-        else
-          type = attr.getStorageType();
-        break;
-      }
+      break;
+    }
 
-      std::string defaultValue;
-      // Attach default value if requested and possible.
-      if (attrParamKind == AttrParamKind::UnwrappedValue &&
-          i >= defaultValuedAttrStartIndex) {
-        bool isString = attr.getReturnType() == "::llvm::StringRef";
-        if (isString)
-          defaultValue.append("\"");
-        defaultValue += attr.getDefaultValue();
-        if (isString)
-          defaultValue.append("\"");
-      }
-      paramList.emplace_back(type, namedAttr.name, defaultValue, properties);
-      ++numAttrs;
+    // Attach default value if requested and possible.
+    std::string defaultValue;
+    if (attrParamKind == AttrParamKind::UnwrappedValue &&
+        i >= defaultValuedAttrStartIndex) {
+      bool isString = attr.getReturnType() == "::llvm::StringRef";
+      if (isString)
+        defaultValue.append("\"");
+      defaultValue += attr.getDefaultValue();
+      if (isString)
+        defaultValue.append("\"");
     }
+    paramList.emplace_back(type, namedAttr.name, defaultValue, properties);
   }
 
   /// Insert parameters for each successor.
@@ -1546,12 +1614,31 @@
                              llvm::formatv("{0}Count", region.name).str());
 }
 
-void OpEmitter::genCodeForAddingArgAndRegionForBuilder(OpMethodBody &body,
-                                                       bool isRawValueAttr) {
+void OpEmitter::genCodeForAddingArgAndRegionForBuilder(
+    OpMethodBody &body, llvm::StringSet<> &inferredAttributes,
+    bool isRawValueAttr) {
   // Push all operands to the result.
   for (int i = 0, e = op.getNumOperands(); i < e; ++i) {
     std::string argName = getArgumentName(op, i);
-    if (op.getOperand(i).isOptional())
+    NamedTypeConstraint &operand = op.getOperand(i);
+    if (operand.constraint.isVariadicOfVariadic()) {
+      body << "  for (::mlir::ValueRange range : " << argName << ")\n   "
+           << builderOpState << ".addOperands(range);\n";
+
+      // Add the segment attribute.
+      body << "  {\n"
+           << "    SmallVector<int32_t> rangeSegments;\n"
+           << "    for (::mlir::ValueRange range : " << argName << ")\n"
+           << "      rangeSegments.push_back(range.size());\n"
+           << "    " << builderOpState << ".addAttribute("
+           << operand.constraint.getVariadicOfVariadicSegmentSizeAttr()
+           << "AttrName(" << builderOpState << ".name), " << odsBuilder
+           << ".getI32TensorAttr(rangeSegments));"
+           << "  }\n";
+      continue;
+    }
+
+    if (operand.isOptional())
       body << "  if (" << argName << ")\n  ";
     body << "  " << builderOpState << ".addOperands(" << argName << ");\n";
   }
@@ -1563,12 +1650,24 @@
          << ".name), "
          << "odsBuilder.getI32VectorAttr({";
     interleaveComma(llvm::seq<int>(0, op.getNumOperands()), body, [&](int i) {
-      if (op.getOperand(i).isOptional())
-        body << "(" << getArgumentName(op, i) << " ? 1 : 0)";
-      else if (op.getOperand(i).isVariadic())
-        body << "static_cast<int32_t>(" << getArgumentName(op, i) << ".size())";
-      else
+      const NamedTypeConstraint &operand = op.getOperand(i);
+      if (!operand.isVariableLength()) {
         body << "1";
+        return;
+      }
+
+      std::string operandName = getArgumentName(op, i);
+      if (operand.isOptional()) {
+        body << "(" << operandName << " ? 1 : 0)";
+      } else if (operand.isVariadicOfVariadic()) {
+        body << llvm::formatv(
+            "static_cast<int32_t>(std::accumulate({0}.begin(), {0}.end(), 0, "
+            "[](int32_t curSum, ::mlir::ValueRange range) {{ return curSum + "
+            "range.size(); }))",
+            operandName);
+      } else {
+        body << "static_cast<int32_t>(" << getArgumentName(op, i) << ".size())";
+      }
     });
     body << "}));\n";
   }
@@ -1576,38 +1675,38 @@
   // Push all attributes to the result.
   for (const auto &namedAttr : op.getAttributes()) {
     auto &attr = namedAttr.attr;
-    if (!attr.isDerivedAttr()) {
-      bool emitNotNullCheck = attr.isOptional();
-      if (emitNotNullCheck)
-        body << formatv("  if ({0}) ", namedAttr.name) << "{\n";
-
-      if (isRawValueAttr && canUseUnwrappedRawValue(attr)) {
-        // If this is a raw value, then we need to wrap it in an Attribute
-        // instance.
-        FmtContext fctx;
-        fctx.withBuilder("odsBuilder");
-
-        std::string builderTemplate =
-            std::string(attr.getConstBuilderTemplate());
-
-        // For StringAttr, its constant builder call will wrap the input in
-        // quotes, which is correct for normal string literals, but incorrect
-        // here given we use function arguments. So we need to strip the
-        // wrapping quotes.
-        if (StringRef(builderTemplate).contains("\"$0\""))
-          builderTemplate = replaceAllSubstrs(builderTemplate, "\"$0\"", "$0");
-
-        std::string value =
-            std::string(tgfmt(builderTemplate, &fctx, namedAttr.name));
-        body << formatv("  {0}.addAttribute({1}AttrName({0}.name), {2});\n",
-                        builderOpState, namedAttr.name, value);
-      } else {
-        body << formatv("  {0}.addAttribute({1}AttrName({0}.name), {1});\n",
-                        builderOpState, namedAttr.name);
-      }
-      if (emitNotNullCheck)
-        body << "  }\n";
+    if (attr.isDerivedAttr() || inferredAttributes.contains(namedAttr.name))
+      continue;
+
+    bool emitNotNullCheck = attr.isOptional();
+    if (emitNotNullCheck)
+      body << formatv("  if ({0}) ", namedAttr.name) << "{\n";
+
+    if (isRawValueAttr && canUseUnwrappedRawValue(attr)) {
+      // If this is a raw value, then we need to wrap it in an Attribute
+      // instance.
+      FmtContext fctx;
+      fctx.withBuilder("odsBuilder");
+
+      std::string builderTemplate = std::string(attr.getConstBuilderTemplate());
+
+      // For StringAttr, its constant builder call will wrap the input in
+      // quotes, which is correct for normal string literals, but incorrect
+      // here given we use function arguments. So we need to strip the
+      // wrapping quotes.
+      if (StringRef(builderTemplate).contains("\"$0\""))
+        builderTemplate = replaceAllSubstrs(builderTemplate, "\"$0\"", "$0");
+
+      std::string value =
+          std::string(tgfmt(builderTemplate, &fctx, namedAttr.name));
+      body << formatv("  {0}.addAttribute({1}AttrName({0}.name), {2});\n",
+                      builderOpState, namedAttr.name, value);
+    } else {
+      body << formatv("  {0}.addAttribute({1}AttrName({0}.name), {1});\n",
+                      builderOpState, namedAttr.name);
     }
+    if (emitNotNullCheck)
+      body << "  }\n";
   }
 
   // Create the correct number of regions.
@@ -1960,9 +2059,12 @@
   body << "    unsigned index = 0; (void)index;\n";
 
   for (auto staticValue : llvm::enumerate(values)) {
-    bool hasPredicate = staticValue.value().hasPredicate();
-    bool isOptional = staticValue.value().isOptional();
-    if (!hasPredicate && !isOptional)
+    const NamedTypeConstraint &value = staticValue.value();
+
+    bool hasPredicate = value.hasPredicate();
+    bool isOptional = value.isOptional();
+    bool isVariadicOfVariadic = value.isVariadicOfVariadic();
+    if (!hasPredicate && !isOptional && !isVariadicOfVariadic)
       continue;
     body << formatv("    auto valueGroup{2} = getODS{0}{1}s({2});\n",
                     // Capitalize the first letter to match the function name
@@ -1977,14 +2079,21 @@
                       "<< index << \" requires 0 or 1 element, but found \" << "
                       "valueGroup{0}.size();\n",
                       staticValue.index(), valueKind);
+    } else if (isVariadicOfVariadic) {
+      body << formatv(
+          "    if (::mlir::failed(::mlir::OpTrait::impl::verifyValueSizeAttr("
+          "*this, \"{0}\", \"{1}\", valueGroup{2}.size())))\n"
+          "      return ::mlir::failure();\n",
+          value.constraint.getVariadicOfVariadicSegmentSizeAttr(), value.name,
+          staticValue.index());
     }
 
     // Otherwise, if there is no predicate there is nothing left to do.
     if (!hasPredicate)
       continue;
     // Emit a loop to check all the dynamic values in the pack.
-    StringRef constraintFn = staticVerifierEmitter.getTypeConstraintFn(
-        staticValue.value().constraint);
+    StringRef constraintFn =
+        staticVerifierEmitter.getTypeConstraintFn(value.constraint);
     body << "    for (::mlir::Value v : valueGroup" << staticValue.index()
          << ") {\n"
          << "      if (::mlir::failed(" << constraintFn
@@ -2257,7 +2366,8 @@
   }
   std::string sizeAttrInit =
       formatv(adapterSegmentSizeAttrInitCode, "operand_segment_sizes");
-  generateNamedOperandGetters(op, adaptor, sizeAttrInit,
+  generateNamedOperandGetters(op, adaptor,
+                              /*isAdaptor=*/true, sizeAttrInit,
                               /*rangeType=*/"::mlir::ValueRange",
                               /*rangeBeginCall=*/"odsOperands.begin()",
                               /*rangeSizeCall=*/"odsOperands.size()",
diff --git a/mlir/tools/mlir-tblgen/OpFormatGen.cpp b/mlir/tools/mlir-tblgen/OpFormatGen.cpp
--- a/mlir/tools/mlir-tblgen/OpFormatGen.cpp
+++ b/mlir/tools/mlir-tblgen/OpFormatGen.cpp
@@ -497,6 +497,7 @@
 
   /// The set of attributes explicitly used within the format.
   SmallVector<const NamedAttribute *, 8> usedAttributes;
+  llvm::StringSet<> inferredAttributes;
 };
 } // end anonymous namespace
 
@@ -616,10 +617,38 @@
   if (parser.parseOperand({0}RawOperands[0]))
     return ::mlir::failure();
 )";
+/// The code snippet used to generate a parser call for a VariadicOfVariadic
+/// operand.
+///
+/// {0}: The name of the operand.
+/// {1}: The name of segment size attribute.
+const char *const variadicOfVariadicOperandParserCode = R"(
+  {
+    {0}OperandsLoc = parser.getCurrentLocation();
+    int32_t curSize = 0;
+    do {
+      if (parser.parseOptionalLParen())
+        break;
+      if (parser.parseOperandList({0}Operands) || parser.parseRParen())
+        return ::mlir::failure();
+      {0}OperandGroupSizes.push_back({0}Operands.size() - curSize);
+      curSize = {0}Operands.size();
+    } while (succeeded(parser.parseOptionalComma()));
+  }
+)";
 
 /// The code snippet used to generate a parser call for a type list.
 ///
 /// {0}: The name for the type list.
+const char *const variadicOfVariadicTypeParserCode = R"(
+  do {
+    if (parser.parseOptionalLParen())
+      break;
+    if (parser.parseOptionalRParen() &&
+        (parser.parseTypeList({0}Types) || parser.parseRParen()))
+      return ::mlir::failure();
+  } while (succeeded(parser.parseOptionalComma()));
+)";
 const char *const variadicTypeParserCode = R"(
   if (parser.parseTypeList({0}Types))
     return ::mlir::failure();
@@ -758,6 +787,9 @@
 namespace {
 /// The type of length for a given parse argument.
 enum class ArgumentLengthKind {
+  /// The argument is a variadic of a variadic, and may contain 0->N range
+  /// elements.
+  VariadicOfVariadic,
   /// The argument is variadic, and may contain 0->N elements.
   Variadic,
   /// The argument is optional, and may contain 0 or 1 elements.
@@ -772,6 +804,8 @@
 getArgumentLengthKind(const NamedTypeConstraint *var) {
   if (var->isOptional())
     return ArgumentLengthKind::Optional;
+  if (var->isVariadicOfVariadic())
+    return ArgumentLengthKind::VariadicOfVariadic;
   if (var->isVariadic())
     return ArgumentLengthKind::Variadic;
   return ArgumentLengthKind::Single;
@@ -863,6 +897,10 @@
     if (operand->getVar()->isVariableLength()) {
       body << "  ::mlir::SmallVector<::mlir::OpAsmParser::OperandType, 4> "
            << name << "Operands;\n";
+      if (operand->getVar()->isVariadicOfVariadic()) {
+        body << "    llvm::SmallVector<int32_t> " << name
+             << "OperandGroupSizes;\n";
+      }
     } else {
       body << "  ::mlir::OpAsmParser::OperandType " << name
            << "RawOperands[1];\n"
@@ -924,7 +962,9 @@
   } else if (auto *operand = dyn_cast<OperandVariable>(&param)) {
     StringRef name = operand->getVar()->name;
     ArgumentLengthKind lengthKind = getArgumentLengthKind(operand->getVar());
-    if (lengthKind == ArgumentLengthKind::Variadic)
+    if (lengthKind == ArgumentLengthKind::VariadicOfVariadic)
+      body << llvm::formatv("{0}OperandGroups", name);
+    else if (lengthKind == ArgumentLengthKind::Variadic)
       body << llvm::formatv("{0}Operands", name);
     else if (lengthKind == ArgumentLengthKind::Optional)
       body << llvm::formatv("{0}Operand", name);
@@ -951,7 +991,9 @@
   } else if (auto *dir = dyn_cast<TypeDirective>(&param)) {
     ArgumentLengthKind lengthKind;
     StringRef listName = getTypeListName(dir->getOperand(), lengthKind);
-    if (lengthKind == ArgumentLengthKind::Variadic)
+    if (lengthKind == ArgumentLengthKind::VariadicOfVariadic)
+      body << llvm::formatv("{0}TypeGroups", listName);
+    else if (lengthKind == ArgumentLengthKind::Variadic)
       body << llvm::formatv("{0}Types", listName);
     else if (lengthKind == ArgumentLengthKind::Optional)
       body << llvm::formatv("{0}Type", listName);
@@ -972,19 +1014,32 @@
   // * Set the location of operand variables.
   for (Element &param : dir->getArguments()) {
     if (auto *operand = dyn_cast<OperandVariable>(&param)) {
-      body << "    " << operand->getVar()->name
+      auto *var = operand->getVar();
+      body << "    " << var->name
            << "OperandsLoc = parser.getCurrentLocation();\n";
-      if (operand->getVar()->isOptional()) {
+      if (var->isOptional()) {
         body << llvm::formatv(
             "    llvm::Optional<::mlir::OpAsmParser::OperandType> "
             "{0}Operand;\n",
-            operand->getVar()->name);
+            var->name);
+      } else if (var->isVariadicOfVariadic()) {
+        body << llvm::formatv("    "
+                              "llvm::SmallVector<llvm::SmallVector<::mlir::"
+                              "OpAsmParser::OperandType>> "
+                              "{0}OperandGroups;\n",
+                              var->name);
       }
     } else if (auto *dir = dyn_cast<TypeDirective>(&param)) {
       ArgumentLengthKind lengthKind;
       StringRef listName = getTypeListName(dir->getOperand(), lengthKind);
-      if (lengthKind == ArgumentLengthKind::Optional)
+      if (lengthKind == ArgumentLengthKind::Optional) {
         body << llvm::formatv("    ::mlir::Type {0}Type;\n", listName);
+      } else if (lengthKind == ArgumentLengthKind::VariadicOfVariadic) {
+        body << llvm::formatv(
+            "    llvm::SmallVector<llvm::SmallVector<::mlir::Type>> "
+            "{0}TypeGroups;\n",
+            listName);
+      }
     } else if (auto *dir = dyn_cast<RefDirective>(&param)) {
       Element *input = dir->getOperand();
       if (auto *operand = dyn_cast<OperandVariable>(input)) {
@@ -1028,11 +1083,18 @@
                             var->name);
     } else if (auto *operand = dyn_cast<OperandVariable>(&param)) {
       const NamedTypeConstraint *var = operand->getVar();
-      if (!var->isOptional())
-        continue;
-      body << llvm::formatv("    if ({0}Operand.hasValue())\n"
-                            "      {0}Operands.push_back(*{0}Operand);\n",
-                            var->name);
+      if (var->isOptional()) {
+        body << llvm::formatv("    if ({0}Operand.hasValue())\n"
+                              "      {0}Operands.push_back(*{0}Operand);\n",
+                              var->name);
+      } else if (var->isVariadicOfVariadic()) {
+        body << llvm::formatv(
+            "    for (const auto &subRange : {0}OperandGroups) {{\n"
+            "      {0}Operands.append(subRange.begin(), subRange.end());\n"
+            "      {0}OperandGroupSizes.push_back(subRange.size());\n"
+            "    }\n",
+            var->name, var->constraint.getVariadicOfVariadicSegmentSizeAttr());
+      }
     } else if (auto *dir = dyn_cast<TypeDirective>(&param)) {
       ArgumentLengthKind lengthKind;
       StringRef listName = getTypeListName(dir->getOperand(), lengthKind);
@@ -1040,6 +1102,11 @@
         body << llvm::formatv("    if ({0}Type)\n"
                               "      {0}Types.push_back({0}Type);\n",
                               listName);
+      } else if (lengthKind == ArgumentLengthKind::VariadicOfVariadic) {
+        body << llvm::formatv(
+            "    for (const auto &subRange : {0}TypeGroups)\n"
+            "      {0}Types.append(subRange.begin(), subRange.end());\n",
+            listName);
       }
     }
   }
@@ -1229,7 +1296,11 @@
   } else if (auto *operand = dyn_cast<OperandVariable>(element)) {
     ArgumentLengthKind lengthKind = getArgumentLengthKind(operand->getVar());
     StringRef name = operand->getVar()->name;
-    if (lengthKind == ArgumentLengthKind::Variadic)
+    if (lengthKind == ArgumentLengthKind::VariadicOfVariadic)
+      body << llvm::formatv(
+          variadicOfVariadicOperandParserCode, name,
+          operand->getVar()->constraint.getVariadicOfVariadicSegmentSizeAttr());
+    else if (lengthKind == ArgumentLengthKind::Variadic)
       body << llvm::formatv(variadicOperandParserCode, name);
     else if (lengthKind == ArgumentLengthKind::Optional)
       body << llvm::formatv(optionalOperandParserCode, name);
@@ -1281,7 +1352,9 @@
   } else if (auto *dir = dyn_cast<TypeDirective>(element)) {
     ArgumentLengthKind lengthKind;
     StringRef listName = getTypeListName(dir->getOperand(), lengthKind);
-    if (lengthKind == ArgumentLengthKind::Variadic)
+    if (lengthKind == ArgumentLengthKind::VariadicOfVariadic)
+      body << llvm::formatv(variadicOfVariadicTypeParserCode, listName);
+    else if (lengthKind == ArgumentLengthKind::Variadic)
       body << llvm::formatv(variadicTypeParserCode, listName);
     else if (lengthKind == ArgumentLengthKind::Optional)
       body << llvm::formatv(optionalTypeParserCode, listName);
@@ -1501,19 +1574,29 @@
 
 void OperationFormat::genParserVariadicSegmentResolution(Operator &op,
                                                          OpMethodBody &body) {
-  if (!allOperands &&
-      op.getTrait("::mlir::OpTrait::AttrSizedOperandSegments")) {
-    body << "  result.addAttribute(\"operand_segment_sizes\", "
-         << "parser.getBuilder().getI32VectorAttr({";
-    auto interleaveFn = [&](const NamedTypeConstraint &operand) {
-      // If the operand is variadic emit the parsed size.
-      if (operand.isVariableLength())
-        body << "static_cast<int32_t>(" << operand.name << "Operands.size())";
-      else
-        body << "1";
-    };
-    llvm::interleaveComma(op.getOperands(), body, interleaveFn);
-    body << "}));\n";
+  if (!allOperands) {
+    if (op.getTrait("::mlir::OpTrait::AttrSizedOperandSegments")) {
+      body << "  result.addAttribute(\"operand_segment_sizes\", "
+           << "parser.getBuilder().getI32VectorAttr({";
+      auto interleaveFn = [&](const NamedTypeConstraint &operand) {
+        // If the operand is variadic emit the parsed size.
+        if (operand.isVariableLength())
+          body << "static_cast<int32_t>(" << operand.name << "Operands.size())";
+        else
+          body << "1";
+      };
+      llvm::interleaveComma(op.getOperands(), body, interleaveFn);
+      body << "}));\n";
+    }
+    for (const NamedTypeConstraint &operand : op.getOperands()) {
+      if (!operand.isVariadicOfVariadic())
+        continue;
+      body << llvm::formatv(
+          "  result.addAttribute(\"{0}\", "
+          "parser.getBuilder().getI32TensorAttr({1}OperandGroupSizes));\n",
+          operand.constraint.getVariadicOfVariadicSegmentSizeAttr(),
+          operand.name);
+    }
   }
 
   if (!allResultTypes &&
@@ -1575,6 +1658,10 @@
   if (!fmt.allResultTypes &&
       op.getTrait("::mlir::OpTrait::AttrSizedResultSegments"))
     body << "\"result_segment_sizes\", ";
+  if (!fmt.inferredAttributes.empty()) {
+    for (const auto &attr : fmt.inferredAttributes)
+      body << "\"" << attr.getKey() << "\", ";
+  }
   llvm::interleaveComma(
       fmt.usedAttributes, body,
       [&](const NamedAttribute *attr) { body << "\"" << attr->name << "\""; });
@@ -1693,6 +1780,8 @@
     return body << "getOperation()->getResultTypes()";
   auto *operand = dyn_cast<OperandVariable>(arg);
   auto *var = operand ? operand->getVar() : cast<ResultVariable>(arg)->getVar();
+  if (var->isVariadicOfVariadic())
+    return body << llvm::formatv("{0}().join().getTypes()", var->name);
   if (var->isVariadic())
     return body << var->name << "().getTypes()";
   if (var->isOptional())
@@ -1896,7 +1985,12 @@
     else
       body << "  p.printAttribute(" << var->name << "Attr());\n";
   } else if (auto *operand = dyn_cast<OperandVariable>(element)) {
-    if (operand->getVar()->isOptional()) {
+    if (operand->getVar()->isVariadicOfVariadic()) {
+      body << "  ::llvm::interleaveComma(" << operand->getVar()->name
+           << "(), p, [&](const auto &operands) { p << \"(\" << operands << "
+              "\")\"; });\n";
+
+    } else if (operand->getVar()->isOptional()) {
       body << "  if (::mlir::Value value = " << operand->getVar()->name
            << "())\n"
            << "    p << value;\n";
@@ -1926,6 +2020,15 @@
   } else if (isa<SuccessorsDirective>(element)) {
     body << "  ::llvm::interleaveComma(getOperation()->getSuccessors(), p);\n";
   } else if (auto *dir = dyn_cast<TypeDirective>(element)) {
+    if (auto *operand = dyn_cast<OperandVariable>(dir->getOperand())) {
+      if (operand->getVar()->isVariadicOfVariadic()) {
+        body << llvm::formatv("  ::llvm::interleaveComma({0}().getTypes(), p, "
+                              "[&](::mlir::TypeRange types) {{ p << \"(\" << "
+                              "types << \")\"; });\n",
+                              operand->getVar()->name);
+        return;
+      }
+    }
     body << "  p << ";
     genTypeOperandPrinter(dir->getOperand(), body) << ";\n";
   } else if (auto *dir = dyn_cast<FunctionalTypeDirective>(element)) {
@@ -2449,6 +2552,16 @@
   while (!iteratorStack.empty())
     if (failed(verifyAttributes(loc, iteratorStack)))
       return ::mlir::failure();
+
+  // Check for VariadicOfVariadic variables. The segment attribute of those
+  // variables will be infered.
+  for (const NamedTypeConstraint *var : seenOperands) {
+    if (var->constraint.isVariadicOfVariadic()) {
+      fmt.inferredAttributes.insert(
+          var->constraint.getVariadicOfVariadicSegmentSizeAttr());
+    }
+  }
+
   return ::mlir::success();
 }
 /// Verify the attribute elements at the back of the given stack of iterators.