https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79570
--- Comment #8 from Alexandre Oliva <aoliva at gcc dot gnu.org> --- > Alexandre, do you recall why debug insns at heads of basic blocks are special? I'm afraid I don't remember, but if I had to guess, I'd say it's because debug insns normally wouldn't be at the border of scheduling groups, but if they are at the top of a BB, then they might, and then they require closer attention to keep debug and non-debug compilations in sync.
