[Bug tree-optimization/65053] New: [5 Regression] PostgreSQL miscompilation

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65053

            Bug ID: 65053
           Summary: [5 Regression] PostgreSQL miscompilation
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org

Following testcase is miscompiled at -O2 starting with r220164:

int i;

__attribute__ ((noinline))
unsigned int foo (void)
{
  return 0;
}

int
main ()
{
  unsigned int u = -1;
  if (u == -1)
    {
      unsigned int n = foo ();
      if (n > 0)
    u = n - 1;
    }

  while (u != -1)
    {
      asm ("" : "+g" (u));
      u = -1;
      i = 1;
    }

  if (i)
    __builtin_abort ();
  return 0;
}