Hi, In private backend for GCC 5.2.0, we do have target-specific scheduler (running in TARGET_SCHED_FINISH hook), that do some instruction packing/pairing on sched2 and relies on REG_DEAD notes, that should be correct.
But they aren't because inside haifa-sched.c, that is being run first in the sched2 pass, reemit_notes function processes only REG_SAVE_NOTE case, and, after this scheduler, some insns with REG_DEAD on register, say r1, might be moved before previous r1 usage (input dependency case) and things become totally wrong. Now I appllied some minimal patch locally to fix it (just added separate REG_DEAD case). But may be it is part of design and may be it is generally true, that we can't rely on correct REG_DEAD notes in platform-specific scheduler? --- With best regards, Konstantin
