diff --git a/mlir/lib/Dialect/SCF/SCF.cpp b/mlir/lib/Dialect/SCF/SCF.cpp
--- a/mlir/lib/Dialect/SCF/SCF.cpp
+++ b/mlir/lib/Dialect/SCF/SCF.cpp
@@ -2168,6 +2168,10 @@
 struct MergeNestedParallelLoops : public OpRewritePattern<ParallelOp> {
   using OpRewritePattern<ParallelOp>::OpRewritePattern;
 
+  void initialize() {
+    addDebugLabels("MergeNestedParallelLoops");
+  }
+
   LogicalResult matchAndRewrite(ParallelOp op,
                                 PatternRewriter &rewriter) const override {
     Block &outerBody = op.getLoopBody().front();