[Bug target/79570] [5/6/7 Regression] ICE in sel-sched-ir.c:4534 in pr69956.c

[aoliva at gcc dot gnu.org]

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.