[Mlir-commits] [mlir] [mlir][Func] Preserve attribute when converting CallOp/ReturnOp signature (PR #127772)

[Hongren Zheng]

================
@@ -126,8 +127,9 @@ class ReturnOpTypeConversion : public OpConversionPattern<ReturnOp> {
   LogicalResult
   matchAndRewrite(ReturnOp op, OneToNOpAdaptor adaptor,
                   ConversionPatternRewriter &rewriter) const final {
-    rewriter.replaceOpWithNewOp<ReturnOp>(op,
-                                          flattenValues(adaptor.getOperands()));
+    rewriter
+        .replaceOpWithNewOp<ReturnOp>(op, flattenValues(adaptor.getOperands()))
+        ->setAttrs(op->getAttrs());
----------------
ZenithalHourlyRate wrote:

Or more conversatively we can preserve some dialect attribute?

```cpp
newOp->setDialectAttrs(op->getDialectAttrs())
```

> transformations should discard them when they don't "understand" them (through interfaces or other mechanism).

I have not seen some mechanism for the transformation to query that. For dialect attribute the transformation could query the dialect `namedAttr.getName().getDialect()` but I have not found dialect interface / attribute interface that describe such information.  

https://github.com/llvm/llvm-project/pull/127772