Add RegionRange for when need to abstract over different region iteration

Follows ValueRange in representing a generic abstraction over the different
ways to represent a range of Regions. This wrapper is not as ValueRange and only
considers the current cases of interest: MutableArrayRef<Region> and
ArrayRef<std::unique_ptr<Region>> as occurs during op construction vs op region
querying.

Note: ArrayRef<std::unique_ptr<Region>> allows for unset regions, so this range
returns a pointer to a Region instead of a Region.
PiperOrigin-RevId: 284563229

2 files changed, 19 insertions, 2 deletions

diff --git a/mlir/lib/IR/Operation.cpp b/mlir/lib/IR/Operation.cpp
index 26f20d324f0..ae635d108b2 100644
--- a/mlir/lib/IR/Operation.cpp
+++ b/mlir/lib/IR/Operation.cpp
@@ -136,8 +136,7 @@ Operation *Operation::create(Location location, OperationName name,
                              ArrayRef<Type> resultTypes,
                              ArrayRef<Value *> operands,
                              NamedAttributeList attributes,
-                             ArrayRef<Block *> successors,
-                             ArrayRef<std::unique_ptr<Region>> regions,
+                             ArrayRef<Block *> successors, RegionRange regions,
                              bool resizableOperandList) {
   unsigned numRegions = regions.size();
   Operation *op = create(location, name, resultTypes, operands, attributes,
diff --git a/mlir/lib/IR/Region.cpp b/mlir/lib/IR/Region.cpp
index a91d36b1e48..a5a19cbcbf2 100644
--- a/mlir/lib/IR/Region.cpp
+++ b/mlir/lib/IR/Region.cpp
@@ -213,3 +213,21 @@ void llvm::ilist_traits<::mlir::Block>::transferNodesFromList(
   for (; first != last; ++first)
     first->parentValidOpOrderPair.setPointer(curParent);
 }
+
+//===----------------------------------------------------------------------===//
+// RegionRange
+//===----------------------------------------------------------------------===//
+RegionRange::RegionRange(MutableArrayRef<Region> regions)
+    : owner(regions.data()), count(regions.size()) {}
+RegionRange::RegionRange(ArrayRef<std::unique_ptr<Region>> regions)
+    : owner(regions.data()), count(regions.size()) {}
+RegionRange::Iterator::Iterator(OwnerT owner, unsigned curIndex)
+    : indexed_accessor_iterator<Iterator, OwnerT, Region *, Region *, Region *>(
+          owner, curIndex) {}
+
+Region *RegionRange::Iterator::operator*() const {
+  if (const std::unique_ptr<Region> *operand =
+          object.dyn_cast<const std::unique_ptr<Region> *>())
+    return operand[index].get();
+  return &object.get<Region *>()[index];
+}