[Bug tree-optimization/84746] New: ICE on valid code at -O2 and -O3: Segmentation fault

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84746

            Bug ID: 84746
           Summary: ICE on valid code at -O2 and -O3: Segmentation fault
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: su at cs dot ucdavis.edu
  Target Milestone: ---

$ gcctk -v
Using built-in specs.
COLLECT_GCC=gcctk
COLLECT_LTO_WRAPPER=/home/su/software/tmp/gcc/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/8.0.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-source-trunk/configure --enable-languages=c,c++,lto
--prefix=/home/su/software/tmp/gcc/gcc-trunk --disable-bootstrap
Thread model: posix
gcc version 8.0.1 20180307 (experimental) [trunk revision 258312] (GCC) 
$ 
$ gcctk -Os -c small.c
$ gcc-7.2.0 -O2 -c small.c
$ 
$ gcctk -O2 -c small.c
during GIMPLE pass: pre
small.c: In function ‘fn1’:
small.c:4:6: internal compiler error: Segmentation fault
 void fn1 ()
      ^~~
0xca7f6f crash_signal
        ../../gcc-source-trunk/gcc/toplev.c:325
0xedd700 update_dep_bb
        ../../gcc-source-trunk/gcc/tree-ssa-tail-merge.c:402
0xedfbf9 same_succ_hash
        ../../gcc-source-trunk/gcc/tree-ssa-tail-merge.c:506
0xedfbf9 find_same_succ_bb
        ../../gcc-source-trunk/gcc/tree-ssa-tail-merge.c:717
0xee00ff find_same_succ
        ../../gcc-source-trunk/gcc/tree-ssa-tail-merge.c:748
0xee00ff init_worklist
        ../../gcc-source-trunk/gcc/tree-ssa-tail-merge.c:767
0xee00ff tail_merge_optimize(unsigned int)
        ../../gcc-source-trunk/gcc/tree-ssa-tail-merge.c:1733
0xe7c6b6 execute
        ../../gcc-source-trunk/gcc/tree-ssa-pre.c:4196
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
$ 


--------------------------------------------------


int a, b, c, d, e;
char f, g;

void fn1 ()
{
  while (1)
    {
      if (d)
        goto L1;
      if (e)
        goto L3;
      int q = (c && a) % (f * (d || a)) && b;
      e = q;
      if (b)
        break;
    L1:
    L2:
      c = f;
    L3:
      f = g;
      while (a)
        goto L2;
    }
}