[IPO] Avoid repeated hash lookups (NFC) (#108796)

Author: kazutakahirata

llvm/lib/Transforms/IPO/OpenMPOpt.cpp

@@ -2364,8 +2364,8 @@ struct AAICVTrackerFunction : public AAICVTracker {
       /// TODO: Figure out a way to avoid adding entry in
       /// ICVReplacementValuesMap
       Instruction *Entry = &F->getEntryBlock().front();
-      if (HasChanged == ChangeStatus::CHANGED && !ValuesMap.count(Entry))
-        ValuesMap.insert(std::make_pair(Entry, nullptr));
+      if (HasChanged == ChangeStatus::CHANGED)
+        ValuesMap.try_emplace(Entry);
     }
 
     return HasChanged;