[Mlir-commits] [mlir] [mlir][Transforms] Dialect conversion: Fix bug in `UnresolvedMaterializationRewrite` rollback (PR #105949)

[llvmlistbot at llvm.org]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-mlir

Author: Matthias Springer (matthias-springer)

<details>
<summary>Changes</summary>

When an unresolved materialization (`unrealized_conversion_cast` op) is rolled back, the mapping should be rolled back as well, regardless of whether it is a source, target or argument materialization. Otherwise, we accumulate pointers to erased IR in the `mapping`. This is harmless in most cases, but can cause issues when a new operation is allocated at the same memory location and the pointer is "reused".

It is not possible to write a test case for this because I cannot trigger the pointer reuse programmatically.

---
Full diff: https://github.com/llvm/llvm-project/pull/105949.diff


1 Files Affected:

- (modified) mlir/lib/Transforms/Utils/DialectConversion.cpp (+2-4) 


``````````diff
diff --git a/mlir/lib/Transforms/Utils/DialectConversion.cpp b/mlir/lib/Transforms/Utils/DialectConversion.cpp
index 4058ed39621198..11e40b74b00424 100644
--- a/mlir/lib/Transforms/Utils/DialectConversion.cpp
+++ b/mlir/lib/Transforms/Utils/DialectConversion.cpp
@@ -1062,10 +1062,8 @@ void CreateOperationRewrite::rollback() {
 }
 
 void UnresolvedMaterializationRewrite::rollback() {
-  if (getMaterializationKind() == MaterializationKind::Target) {
-    for (Value input : op->getOperands())
-      rewriterImpl.mapping.erase(input);
-  }
+  for (Value input : op->getOperands())
+    rewriterImpl.mapping.erase(input);
   op->erase();
 }
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/105949