[Bug tree-optimization/71595] ICE on valid code at -O2 and -O3 on x86_64-linux-gnu: in check_loop_closed_ssa_use, at tree-ssa-loop-manip.c:704

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71595

--- Comment #1 from Zhendong Su <su at cs dot ucdavis.edu> ---
Below is another test case that triggers the same ICE, but also at -O1 and -Os
(in addition to -O2 and -O3). 


$ 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/7.0.0/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 7.0.0 20160624 (experimental) [trunk revision 237753] (GCC) 
$ 
$ gcc-trunk -O0 -c small.c
$ gcc-6.1 -O1 -c small.c
$ 
$ gcc-trunk -O1 -c small.c
small.c: In function ‘fn1’:
small.c:5:1: internal compiler error: in check_loop_closed_ssa_use, at
tree-ssa-loop-manip.c:704
 fn1 ()
 ^~~
0xd30c3c check_loop_closed_ssa_use
        ../../gcc-source-trunk/gcc/tree-ssa-loop-manip.c:703
0xd339f6 check_loop_closed_ssa_stmt
        ../../gcc-source-trunk/gcc/tree-ssa-loop-manip.c:719
0xd339f6 verify_loop_closed_ssa(bool)
        ../../gcc-source-trunk/gcc/tree-ssa-loop-manip.c:753
0xd17a6e tree_unroll_loops_completely(bool, bool)
        ../../gcc-source-trunk/gcc/tree-ssa-loop-ivcanon.c:1431
0xd17afa execute
        ../../gcc-source-trunk/gcc/tree-ssa-loop-ivcanon.c:1537
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.
$ 


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


int a, d, e, f, g, h;
static int b[][6] = { {0}, {0}, {1, 1}, {1} };

void
fn1 ()
{
  for (; f; f++)
    if (g)
      {
        for (e = 0; e < 5; e++)
          if (b[e + 2][1])
            {
              h = b[2][e] ? 0 : a;
              d |= 4;
            }
          else
            return;
      }
}