}
    }
    if (!newType) {
      return failure();
    }
    rewriter.replaceOpWithNewOp<UnrealizedConversionCastOp>(op, newType,
                                                            op->getOperands());
    return success();
  }
};

class HandleCall : public OpInterfaceRewritePattern<CallOpInterface> {
  // Optional-agnostic pattern that propagates types across the program.

  if (num_cores_per_replica != 1) return success();

  llvm::SetVector<Value> bcasts;
  cluster->walk([&](Operation* op) {
    if (op == cluster) return WalkResult::advance();
    for (auto operand : op->getOperands()) {
      Operation* scope = operand.getParentBlock()->getParentOp();
      if (scope->isProperAncestor(replicate)) {
        bcasts.insert(operand);
      }
    }
    return WalkResult::advance();
  });