[Bug tree-optimization/84775] New: ICE on valid code at -O3: in check_loop_closed_ssa_def, at tree-ssa-loop-manip.c:709

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84775

            Bug ID: 84775
           Summary: ICE on valid code at -O3: in
                    check_loop_closed_ssa_def, at
                    tree-ssa-loop-manip.c:709
           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: ---

It appears to be a recent regression.

$ 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 20180309 (experimental) [trunk revision 258374] (GCC) 
$ 
$ gcctk -O2 -c small.c
$ gcc-7.2.0 -O3 -c small.c
$ 
$ gcctk -O3 -c small.c
during GIMPLE pass: ifcvt
small.c: In function ‘fn1’:
small.c:3:6: internal compiler error: in check_loop_closed_ssa_def, at
tree-ssa-loop-manip.c:709
 void fn1 ()
      ^~~
0xe3b38c check_loop_closed_ssa_def
        ../../gcc-source-trunk/gcc/tree-ssa-loop-manip.c:709
0xe3b4ed check_loop_closed_ssa_bb
        ../../gcc-source-trunk/gcc/tree-ssa-loop-manip.c:735
0xe3d686 verify_loop_closed_ssa(bool, loop*)
        ../../gcc-source-trunk/gcc/tree-ssa-loop-manip.c:760
0xbb888b execute_function_todo
        ../../gcc-source-trunk/gcc/passes.c:2012
0xbb91a9 execute_todo
        ../../gcc-source-trunk/gcc/passes.c:2048
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, f;

void fn1 ()
{
  while (e)
    for (f = 0; f < 4; f++)
      {
        int h[1];
        for (; c; c++)
          if (a)
            break;
        d = a - 4;
        if (d)
          b = h[0];
      }
}