[Bug tree-optimization/39074] New: PTA constraint processing for *x = y is wrong

[rguenth at gcc dot gnu dot org]

if the solution of x includes ANYTHING we fail to add the solution of y to all
variables.  Testcase (fails on a-i branch):

int i;
void __attribute__((noinline))
foo(long b, long q)
{
  int *y;
  int **a = &y, **x;
  int ***p;
  if (b)
    p = (int ***)q;
  else
    p = &a;
  x = *p;
  *x = &i;
  *y = 0;
}
extern void abort (void);
int main()
{
  i = 1;
  foo (0, 0);
  if (i != 0)
    abort ();
  return 0;
}

I guess we should warn for dereferenced pointers whos points-to set is empty
with "warning: dereferencing uninitialized pointer".


-- 
           Summary: PTA constraint processing for *x = y is wrong
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Keywords: wrong-code, alias
          Severity: major
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rguenth at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39074