[Mlir-commits] [mlir] [mlir][memref] Fix crash in DimOp::fold for subview with ambiguous dropped dims (PR #183995)

[Mehdi Amini]

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@@ -1084,8 +1084,12 @@ OpFoldResult DimOp::fold(FoldAdaptor adaptor) {
       }
       resultIndex++;
     }
-    assert(subview.isDynamicSize(sourceIndex) &&
-           "expected dynamic subview size");
+    // If the source dimension is not dynamic, getDroppedDims() may have
+    // computed an incorrect mapping (e.g., when strides are all dynamic and
+    // there are multiple unit-size candidate dimensions), so conservatively
+    // bail out.
+    if (!subview.isDynamicSize(sourceIndex))
+      return {};
     return subview.getDynamicSize(sourceIndex);
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joker-eph wrote:

That works, but Claude found a simplification that avoids even calling `getDroppedDims()` in the first place!

https://github.com/llvm/llvm-project/pull/183995