[llvm] [WPD]Regard unreachable function as a possible devirtualizable target (PR #115668)

[Mingming Liu via llvm-commits]

================
@@ -167,6 +167,18 @@ static cl::list<std::string>
                       cl::desc("Prevent function(s) from being devirtualized"),
                       cl::Hidden, cl::CommaSeparated);
 
+/// A function is unreachable if its entry block ends with 'unreachable' IR
----------------
minglotus-6 wrote:

Updated the surrounding comment with the motivating case and a TODO for Clang's codegen, and updated PR description as suggested. 

https://github.com/llvm/llvm-project/pull/115668