[Bug tree-optimization/71335] New: wrong code at -O2 and -O3 in 32-bit and 64-bit modes on x86_64-linux-gnu

["chengniansun at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71335

            Bug ID: 71335
           Summary: wrong code at -O2 and -O3 in 32-bit and 64-bit modes
                    on x86_64-linux-gnu
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: chengniansun at gmail dot com
  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/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 20160529 (experimental) [trunk revision 236861] (GCC)
$: gcc-trunk small.c -O3 -m64 ; timeout -s 9 2 ./a.out
Killed
$: gcc-trunk small.c -O2 -m64 ; timeout -s 9 2 ./a.out
Killed
$: gcc-trunk small.c -Os -m64 ; timeout -s 9 2 ./a.out
$: cat small.c
int a;
int main() {
  int b = 0;
  while (a < 0 || b) {
    b = 0;
    for (; b < 9; b++)
      ;
  }
  return 0;
}
$: