2010-06-25  Christian Borntraeger  <borntraeger@de.ibm.com>
 
	* config/s390/s390.c (override_options): Adopt prefetching
        at -O3 to handle flag_prefetch_loop_arrays as a tristate.

Index: gcc/config/s390/s390.c
===================================================================
*** gcc/config/s390/s390.c.orig
--- gcc/config/s390/s390.c
*************** override_options (void)
*** 1675,1683 ****
      set_param_value ("simultaneous-prefetches", 6);
  
    /* This cannot reside in optimization_options since HAVE_prefetch
!      requires the arch flags to be evaluated already.  */
!   if (HAVE_prefetch && optimize >= 3)
!     flag_prefetch_loop_arrays = 1;
  }
  
  /* Map for smallest class containing reg regno.  */
--- 1675,1684 ----
      set_param_value ("simultaneous-prefetches", 6);
  
    /* This cannot reside in optimization_options since HAVE_prefetch
!      requires the arch flags to be evaluated already.  Since prefetching
!      is benefitial on s390, we enable it if available.  */
!   if (flag_prefetch_loop_arrays < 0 && HAVE_prefetch && optimize >= 3)
!       flag_prefetch_loop_arrays = 1;
  }
  
  /* Map for smallest class containing reg regno.  */