[llvm] Make RAUW skip instances where operand is the replacement node (PR #212724)

[Soham Karandikar via llvm-commits]

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@@ -13307,6 +13301,18 @@ void SelectionDAG::ReplaceAllUsesOfValueWith(SDValue From, SDValue To){
   RAUWUpdateListener Listener(*this, UI, UE);
   while (UI != UE) {
     SDNode *User = UI->getUser();
+    
+    // Don't replace uses of the To node if is is self-referential.
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skadewdl3 wrote:

The DAG dump does show there's a self-referential token factor created. Afais, `makeEquivalentMemoryOrdering` calls UpdateNodeOperands` to fix that, but the assertion is hit before that happens in this case.

https://github.com/llvm/llvm-project/pull/212724