Commit ca8f6bc629c causes a significant performance issue for my use of addr2line.  Specifically, the use of lookup_func_by_offset() exhibits quadratic complexity when processing a new compile unit.  One of our larger compile units has 80k entries in the funcinfo table, many of which I believe come from C++ inlined subroutines.  This takes almost 20 seconds to process, whereas before this commit, processing the compile unit was nearly instantaneous.  The regression is especially felt when using a tool such as google-pprof, which queries addresses across many compile units; what used to take 1 minute before that commit now takes 10.