[Bug target/124454] [14/15/16 Regression] during RTL pass: sched2 ICE: in operator[], at vec.h:911 with custom flags since r14-4944

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124454

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Means delete_unreachable_blocks is missing somewhere.  Possibly the -fno-*
suppresses that and some parts leaving dangling blocks fail to cleanup
themselves.

Needs a look at which pass exposes the unreachable blocks.