[llvm] Introducing a new ISD::POISON SDNode to represent the poison value in the IR. (PR #125883)

[Amy Kwan via llvm-commits]

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@@ -16266,7 +16266,8 @@ SDValue DAGCombiner::visitFREEZE(SDNode *N) {
   // Finally, recreate the node, it's operands were updated to use
   // frozen operands, so we just need to use it's "original" operands.
   SmallVector<SDValue> Ops(N0->ops());
-  // Special-handle ISD::UNDEF, each single one of them can be it's own thing.
+  // Special-handle ISD::UNDEF, ISD::POISON, each single one of them can be it's
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amy-kwan wrote:

```suggestion
  // Special-handle ISD::UNDEF and ISD::POISON, each single one of them can be it's
```

https://github.com/llvm/llvm-project/pull/125883