[Bug debug/56950] compare-debug failure for gcc.dg/pr41345.c with fschedule-insns

["stevenb.gcc at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56950

--- Comment #8 from stevenb.gcc at gmail dot com <stevenb.gcc at gmail dot com> ---
> --- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
> That still doesn't look safe -fcompare-debug wise.
> I mean, if BB ends in a DEBUG_INSN (or more), it could be preceeded by note,
> label, or some other insns.  So shouldn't that be instead
>   rtx insn2 = DEBUG_INSN_P (insn) ? prev_nondebug_insn (insn2) : insn;

I suppose so, yes.

> (I'd hope there shouldn't be DEBUG_INSN only bb's, because then with -g0 insn
> ought to be NULL and NEXT_INSN (insn) should crash), and use this in the
> !NOTE_P and !LABEL_P tests?

This block is a DEBUG_INSN-only block, but insn is never NULL: BB_END
will be the basic block note.