diff --git a/mlir/lib/Transforms/DialectConversion.cpp b/mlir/lib/Transforms/DialectConversion.cpp
--- a/mlir/lib/Transforms/DialectConversion.cpp
+++ b/mlir/lib/Transforms/DialectConversion.cpp
@@ -1094,21 +1094,20 @@
 }
 
 bool ConversionPatternRewriterImpl::isOpIgnored(Operation *op) const {
-  // Check to see if this operation was replaced or its parent ignored.
-  return replacements.count(op) || ignoredOps.count(op->getParentOp());
+  // Check to see if this operation or a parent was replaced or ignored.
+  do {
+    if (replacements.count(op))
+      return true;
+    if (ignoredOps.count(op))
+      return true;
+  } while ((op = op->getParentOp()));
+  return false;
 }
 
 void ConversionPatternRewriterImpl::markNestedOpsIgnored(Operation *op) {
-  // Walk this operation and collect nested operations that define non-empty
-  // regions. We mark such operations as 'ignored' so that we know we don't have
-  // to convert them, or their nested ops.
-  if (op->getNumRegions() == 0)
-    return;
-  op->walk([&](Operation *op) {
-    if (llvm::any_of(op->getRegions(),
-                     [](Region &region) { return !region.empty(); }))
-      ignoredOps.insert(op);
-  });
+  // Mark operation as ignored and all children will be recursively considered
+  // ignored also.
+  ignoredOps.insert(op);
 }
 
 //===----------------------------------------------------------------------===//
@@ -1184,10 +1183,6 @@
   if (currentConversionPattern)
     converter = currentConversionPattern->getTypeConverter();
   replacements.insert(std::make_pair(op, OpReplacement(converter)));
-
-  // Mark this operation as recursively ignored so that we don't need to
-  // convert any nested operations.
-  markNestedOpsIgnored(op);
 }
 
 void ConversionPatternRewriterImpl::notifyBlockIsBeingErased(Block *block) {