This is clearly an O(n^2) situation somewhere in LLVM. Usually it is pretty easy to fix by adding a cache or two; or by changing a linear search to a hash map.

This is clearly an O(n^2) situation somewhere in LLVM. Usually it is pretty easy to fix by adding a cache or two; or by changing a linear search to a hash map. If OP could produce an LLVM reproduction sample then this would be a good help for LLVM team.