https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79165
--- Comment #21 from David Malcolm <dmalcolm at gcc dot gnu.org> --- (In reply to David Malcolm from comment #19) [...] > In particular, repeated accesses to the same source line are more expensive > that they could be: each time it tries to count forwards from the last > line_record entry, rather than reusing the line information it got last time > (in input.c:read_line_num). I'll try to fix it. aermod.f90 With the bad linemap: get_next_line is 16% of overhead Without the bad linemap: get_next_line is 0.4% of overhead tramp3d without the bad linemap, with -Wall shows get_next_line is only 0.35% of overhead Not sure how much of a win this would be, and it doesn't seem like gcc 7 material at this stage.