[Bug tree-optimization/20165] New: Pointer does not really escape with write

["pinskia at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>]

Take the following fortran code (were we know that write does not make the pointer escape):
      program main
      dimension x(10)
      write(3)n,(x(n),n=1,10)
      end

in the last tree dump we get:
  _gfortran_transfer_integer (&n, 4);
  n = 1;

<L0>:;
  _gfortran_transfer_real (&x[n + -1], 4);
  n.3 = n;
  n = n.3 + 1;
  if (n.3 == 10) goto <L4>; else goto <L0>;

See how n is marked as not a gimple variable which causes us to store it on the stack.  Even though we 
know that _gfortran_transfer_real will not cause the pointer to escape.  There should be a new attribute 
to mark functions as causing pointers not to escape at all.

-- 
           Summary: Pointer does not really escape with write
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: enhancement
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pinskia at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20165