[Bug target/79499] ICE in rtl_verify_bb_insns, at cfgrtl.c:2661

["gerhard dot steinmetz dot fortran at t-online dot de" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79499

--- Comment #1 from Gerhard Steinmetz <gerhard.steinmetz.fortran@t-online.de> ---
Original files from ./gcc/testsuite/gcc.dg/torture.
Oh, and gcc-5 (configured with --enable-checking=yes) also gives
that ICE for pr57478.c (but not for pr78542.c).

Whereas with release versions 5/6/7 (--enable-checking=release) :


$ cat z1.c     # slightly reduced/modified pr57478.c
typedef struct Node Node;
struct Node
{
  Node *Suc, *SubBestSuc;
};
void
foo (Node *N)
{
  do
    {
      N->SubBestSuc = N->Suc;
    }
  while (N = N->Suc);
}


$ gcc-7-20170212-rel -O2 -fsplit-stack -fno-omit-frame-pointer -c z1.c
z1.c: In function 'foo':
z1.c:14:1: internal compiler error: in maybe_add_or_update_dep_1, at
sched-deps.c:924
 }
 ^
0x10cab94 maybe_add_or_update_dep_1
        ../../gcc/sched-deps.c:924
0x10cacf9 haifa_note_dep
        ../../gcc/sched-deps.c:1866
0x10c2fc2 note_dep
        ../../gcc/sched-deps.c:1901
0x10c2fc2 add_dependence_1
        ../../gcc/sched-deps.c:4285
0x10c5163 add_dependence(rtx_insn*, rtx_insn*, reg_note)
        ../../gcc/sched-deps.c:1553
0xa35b9e add_branch_dependences
        ../../gcc/sched-rgn.c:2507
0xa35b9e compute_block_dependences
        ../../gcc/sched-rgn.c:2725
0xa35b9e sched_rgn_compute_dependencies(int)
        ../../gcc/sched-rgn.c:3347
0xa37a7b schedule_region
        ../../gcc/sched-rgn.c:3103
0xa37a7b schedule_insns()
        ../../gcc/sched-rgn.c:3506
0xa3807d schedule_insns()
        ../../gcc/sched-rgn.c:3491
0xa3807d rest_of_handle_sched2
        ../../gcc/sched-rgn.c:3730
0xa3807d execute
        ../../gcc/sched-rgn.c:3866



$ gcc-7-20170212-rel -Os -fsplit-stack -fno-omit-frame-pointer -c z1.c
z1.c: In function 'foo':
z1.c:14:1: internal compiler error: in schedule_block, at haifa-sched.c:6681
 }
 ^
0x105edd1 schedule_block(basic_block_def**, void*)
        ../../gcc/haifa-sched.c:6681
0xa37d3a schedule_region
        ../../gcc/sched-rgn.c:3169
0xa37d3a schedule_insns()
        ../../gcc/sched-rgn.c:3506
0xa3807d schedule_insns()
        ../../gcc/sched-rgn.c:3491
0xa3807d rest_of_handle_sched2
        ../../gcc/sched-rgn.c:3730
0xa3807d execute
        ../../gcc/sched-rgn.c:3866