[Mlir-commits] [mlir] [MLIR] Add `InParallelOpInterface` for parallel combining operations (PR #157736)

[Mehdi Amini]

================
@@ -10,18 +10,47 @@
 
 using namespace mlir;
 
+/// Include the definitions of the interface.
+#include "mlir/Interfaces/ParallelCombiningOpInterface.cpp.inc"
+
 //===----------------------------------------------------------------------===//
-// ParallelCombiningOpInterface
+// InParallelOpInterface
 //===----------------------------------------------------------------------===//
 
+// TODO: Catch-22 with interface methods used to verify means methods can't
+// assume the impl is valid.
+LogicalResult mlir::detail::verifyInParallelOpInterface(Operation *op) {
+  auto inParallel = cast<InParallelOpInterface>(op);
+  auto parent = inParallel.getIteratingParent();
+  if (!parent) {
+    return op->emitError(
+        "in_parallel interface op must have an iterating parent");
+  }
+
+  // Simple verification without requiring ParallelIterationOpInterface
+  // Just check that updated destinations are block arguments
+  for (OpOperand &updatedValue : inParallel.getUpdatedDestinations()) {
+    auto bbArg = dyn_cast<BlockArgument>(updatedValue.get());
+    if (!bbArg) {
+      return op->emitError("updating a non block argument");
+    }
+  }
+  return success();
+}
----------------
joker-eph wrote:

This verifier is suspicious to me. 
1) The TODO makes it quite scary.
2) Using the interface to verify the interface does not seem right?
3) Where is this restriction on block operand coming from? Where is it documented and what are the implications? (it also needs a test)

https://github.com/llvm/llvm-project/pull/157736