[llvm] [LICM] Improve LICM when calls only change Inaccessible memory (PR #169379)

[Paul Walker via llvm-commits]

================
@@ -311,6 +311,14 @@ instructionClobbersQuery(const MemoryDef *MD, const MemoryLocation &UseLoc,
   }
 
   if (auto *CB = dyn_cast_or_null<CallBase>(UseInst)) {
+    if (auto *CU = dyn_cast_or_null<CallBase>(DefInst)) {
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paulwalker-arm wrote:

```suggestion
    if (auto *CU = dyn_cast<CallBase>(DefInst)) {
```
because `DefInst` cannot be null?

https://github.com/llvm/llvm-project/pull/169379