[Bug tree-optimization/81627] New: ICE on valid code at -O3: in check_loop_closed_ssa_use, at tree-ssa-loop-manip.c:707

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81627

            Bug ID: 81627
           Summary: ICE on valid code at -O3: in
                    check_loop_closed_ssa_use, at
                    tree-ssa-loop-manip.c:707
           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: ---

$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/8.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-source-trunk/configure --enable-languages=c,c++,lto
--prefix=/usr/local/gcc-trunk --disable-bootstrap
Thread model: posix
gcc version 8.0.0 20170731 (experimental) [trunk revision 250725] (GCC)
$
$ gcc-trunk -O2 small.c; ./a.out
$
$ gcc-trunk -O3 small.c
during GIMPLE pass: pcom
small.c: In function ‘fn1’:
small.c:3:6: internal compiler error: in check_loop_closed_ssa_use, at
tree-ssa-loop-manip.c:707
 void fn1 ()
      ^~~
0xdd5aed check_loop_closed_ssa_use
        ../../gcc-source-trunk/gcc/tree-ssa-loop-manip.c:706
0xdd8b5e verify_loop_closed_ssa(bool)
        ../../gcc-source-trunk/gcc/tree-ssa-loop-manip.c:751
0xb6b1a9 execute_function_todo
        ../../gcc-source-trunk/gcc/passes.c:2008
0xb6bac9 execute_todo
        ../../gcc-source-trunk/gcc/passes.c:2044
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[6], e, f;

void fn1 ()
{ 
  for (b = 1; b < 5; b++)
    { 
      for (c = 0; c < 5; c++)
        d[b] = e;
      if (a)
        f++;
      d[b + 1] = 1;
    }
}

int main ()
{ 
  fn1 ();
  return 0;
}