[Mlir-commits] [mlir] [mlir][Transforms][NFC] Move `ReconcileUnrealizedCasts` implementation (PR #104671)

[Matthias Springer]

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@@ -1126,6 +1126,29 @@ struct ConversionConfig {
   RewriterBase::Listener *listener = nullptr;
 };
 
+//===----------------------------------------------------------------------===//
+// Reconcile Unrealized Casts
+//===----------------------------------------------------------------------===//
+
+/// Try to reconcile all given UnrealizedConversionCastOps and store the
+/// left-over ops in `remainingCastOps` (if provided).
+///
+/// This function processes cast ops in a worklist-driven fashion. For each
+/// cast op, if the chain of input casts eventually reaches a cast op where the
+/// input types match the output types of the matched op, replace the matched
+/// op with the inputs.
+///
+/// Example:
+/// %1 = unrealized_conversion_cast %0 : !A to !B
+/// %2 = unrealized_conversion_cast %1 : !B to !C
+/// %3 = unrealized_conversion_cast %2 : !C to !A
+///
+/// In the above example, %0 can be used instead of %3 and all cast ops are
+/// folded away.
+void reconcileUnrealizedCasts(
+    ArrayRef<UnrealizedConversionCastOp> castOps,
+    SmallVector<UnrealizedConversionCastOp> *remainingCastOps = nullptr);
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matthias-springer wrote:

What the difference between `SmallVector<...>` and `SmallVectorImpl<...>`?

https://github.com/llvm/llvm-project/pull/104671