[Bug tree-optimization/63406] New: -Warray-bounds false positive with -O3

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63406

            Bug ID: 63406
           Summary: -Warray-bounds false positive with -O3
           Product: gcc
           Version: 4.9.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org

int total_objs = 0;
#ifndef N
#define N 2
#endif
void *objs[N];

void
del_obj (void *obj)
{
  int i = 0;
  while (i < total_objs && objs[i] != obj)
    ++i;
  if (i >= total_objs)
    return;
  while (++i < total_objs)
    objs[i - 1] = objs[i];
  --total_objs;
}

Both loops seem to be unrolled N times (although the second loop clearly could
be
only executed N-1 times, because otherwise it triggers undefined behavior in
the loop), and after unrolling the misdesigned -Warray-bounds warning complains
on the last iteration of the unrolled loop.