[Mlir-commits] [mlir] [MLIR][Transform] Safely erase transform ops by collecting first (PR #172016)

[Miloš Poletanović]

https://github.com/milos1397 created https://github.com/llvm/llvm-project/pull/172016

Avoids runtime crashes caused by deleting operations inside a walk. Operations are gathered during the walk and then erased in the correct dependency order after the walk finishes.

Issue: [#130023](https://github.com/llvm/llvm-project/issues/130023)


>From 4c59916654c432fe80a44522d537ab17fc6f5e70 Mon Sep 17 00:00:00 2001
From: Milos Poletanovic <mpoletanovic at syrmia.com>
Date: Fri, 12 Dec 2025 13:45:16 +0100
Subject: [PATCH] [MLIR][Transform] Safely erase transform ops by collecting
 first

Avoids runtime crashes caused by deleting operations inside a walk.
Operations are gathered during the walk and then erased in the correct dependency
order after the walk finishes.
---
 .../transform-dialect-erase-schedule.mlir         | 15 +++++++++++++++
 .../Transform/TestTransformDialectInterpreter.cpp |  7 ++++++-
 2 files changed, 21 insertions(+), 1 deletion(-)
 create mode 100644 mlir/test/Dialect/Transform/transform-dialect-erase-schedule.mlir

diff --git a/mlir/test/Dialect/Transform/transform-dialect-erase-schedule.mlir b/mlir/test/Dialect/Transform/transform-dialect-erase-schedule.mlir
new file mode 100644
index 0000000000000..a258568d8679b
--- /dev/null
+++ b/mlir/test/Dialect/Transform/transform-dialect-erase-schedule.mlir
@@ -0,0 +1,15 @@
+// RUN: mlir-opt %s -test-transform-dialect-erase-schedule | FileCheck %s
+
+module attributes {transform.with_named_sequence} {
+    func.func @transform_example(%arg0: !transform.any_op) {
+        %transform_copy = transform.structured.match ops{["linalg.copy"]} in %arg0 : (!transform.any_op) -> !transform.any_op
+        transform.nvgpu.rewrite_copy_as_tma %transform_copy : (!transform.any_op) -> ()
+        transform.yield
+    }
+}
+
+// CHECK-LABEL: module attributes {transform.with_named_sequence} {
+// CHECK-NEXT: func.func @transform_example(%arg0: !transform.any_op) {
+// CHECK-NEXT: transform.yield
+// CHECK-NEXT: }
+// CHECK-NEXT: }
\ No newline at end of file
diff --git a/mlir/test/lib/Dialect/Transform/TestTransformDialectInterpreter.cpp b/mlir/test/lib/Dialect/Transform/TestTransformDialectInterpreter.cpp
index 1273414cd4dfc..bd2de68fb276d 100644
--- a/mlir/test/lib/Dialect/Transform/TestTransformDialectInterpreter.cpp
+++ b/mlir/test/lib/Dialect/Transform/TestTransformDialectInterpreter.cpp
@@ -36,13 +36,18 @@ struct TestTransformDialectEraseSchedulePass
   }
 
   void runOnOperation() override {
+    SmallVector<Operation *> opsToDelete;
     getOperation()->walk<WalkOrder::PreOrder>([&](Operation *nestedOp) {
       if (isa<transform::TransformOpInterface>(nestedOp)) {
-        nestedOp->erase();
+        opsToDelete.push_back(nestedOp);
         return WalkResult::skip();
       }
       return WalkResult::advance();
     });
+    for (Operation *op : llvm::reverse(opsToDelete)) {
+      // erase the operation
+      op->erase();
+    }
   }
 };
 } // namespace