[Bug tree-optimization/80791] New: [8 regression] test case gcc.dg/sms-1.c fail2 starting with r247885

[seurer at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80791

            Bug ID: 80791
           Summary: [8 regression] test case gcc.dg/sms-1.c fail2 starting
                    with r247885
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: seurer at gcc dot gnu.org
  Target Milestone: ---

With this revision SMS fails when compiling this test case.

With revision r247884 and earlier we get:

SMS SC already optimized.
SMS schedule branch at cycle ii-1
crr_insn->node=0 (insn id 16), crr_insn->cycle=-1, min_cycle=-1
crr_insn->node=5 (insn id 26), crr_insn->cycle=2, min_cycle=-1
crr_insn->node=3 (insn id 22), crr_insn->cycle=2, min_cycle=-1
crr_insn->node=6 (insn id 43), crr_insn->cycle=2, min_cycle=-1 (branch)
crr_insn->node=1 (insn id 18), crr_insn->cycle=0, min_cycle=-1
crr_insn->node=2 (insn id 21), crr_insn->cycle=0, min_cycle=-1
crr_insn->node=4 (insn id 25), crr_insn->cycle=1, min_cycle=-1
changing bb of uid 64
  unscanned insn
verify found no changes in insn with uid = 43.
Edge 6->6 redirected to 7
 /home/seurer/gcc/gcc-test3/gcc/testsuite/gcc.dg/sms-1.c:24 SMS succeeded 3 2
(with ii, sc)


Starting with revision r247885 we get:

SMS SC already optimized.
SMS schedule branch at cycle ii-1
crr_insn->node=1 (insn id 11), crr_insn->cycle=-1, min_cycle=-2
crr_insn->node=2 (insn id 14), crr_insn->cycle=-1, min_cycle=-2
crr_insn->node=4 (insn id 17), crr_insn->cycle=2, min_cycle=-2
crr_insn->node=7 (insn id 36), crr_insn->cycle=2, min_cycle=-2 (branch)
crr_insn->node=5 (insn id 18), crr_insn->cycle=0, min_cycle=-2
crr_insn->node=3 (insn id 16), crr_insn->cycle=0, min_cycle=-2
crr_insn->node=0 (insn id 9), crr_insn->cycle=-2, min_cycle=-2
crr_insn->node=6 (insn id 19), crr_insn->cycle=1, min_cycle=-2
Scheduling register move INSN 57; ii = 3, min cycle = -2

...more...

Scheduled w/o split in 0
SMS SC already optimized.
SMS schedule branch at cycle ii-1
SMS failed... 
SMS sched-failed (stage-count=1, loop-count=0, trip-count=0)


There is another SMS test with a similar failure but that one has been failing
for a while now:  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69992