Add code comment/NFC

llvm-svn: 265966

llvm/lib/ProfileData/InstrProf.cpp

@@ -398,6 +398,10 @@ uint64_t InstrProfRecord::remapValue(uint64_t Value, uint32_t ValueKind,
         std::lower_bound(ValueMap->begin(), ValueMap->end(), Value,
                          [](const std::pair<uint64_t, uint64_t> &LHS,
                             uint64_t RHS) { return LHS.first < RHS; });
+   // Raw function pointer collected by value profiler may be from 
+   // external functions that are not instrumented. They won't have
+   // mapping data to be used by the deserializer. Force the value to
+   // be 0 in this case.
     if (Result != ValueMap->end() && Result->first == Value)
       Value = (uint64_t)Result->second;
     else