[llvm] [DeadStoreElimination] Optimize tautological assignments (PR #75744)

[via llvm-commits]

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@@ -1931,6 +1976,9 @@ struct DSEState {
     if (!Store)
       return false;
 
+    if (dominatingConditionImpliesValue(Def))
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hiraditya wrote:

I think we should pass the `Store` instruction here to avoid confusion in the callee. That will also remove a dyn_cast you have there.

https://github.com/llvm/llvm-project/pull/75744