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

[via llvm-commits]

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@@ -1901,6 +1901,51 @@ struct DSEState {
     return true;
   }
 
+  // Check if there is a dominating condition, that implies that the value
+  // being stored in a ptr is already present in the ptr.
+  bool dominatingConditionImpliesValue(MemoryDef *Def) {
+    auto *StoreI = dyn_cast<StoreInst>(Def->getMemoryInst());
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hiraditya wrote:

What happens when dyn_cast returns nullptr?

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