Hi,

I ran into a problem with fortran loops in oacc kernels regions not 
being parallelized, after introducting transform_to_exit_first_loop_alt.

For gfortran.dg/goacc/kernels-loop.f95, we get:
...
#pragma omp target oacc_parallel num_gangs(1)
...
instead of the desired num_gangs (32).

transform_to_exit_first_loop_alt fails because nit is _135, where nit is 
defined by:
...
*_105 = 0;
D__lsm.27_50 = *_105;
_32 = (unsigned int) D__lsm.27_50;
_135 = 1023 - _32;
...

pass_fre would manage to propagate the '*105 = 0' assignment. But in the 
current pass order, pass_fre is run before pass_lim, where this pattern 
is introduced:
...
               NEXT_PASS (pass_ch_oacc_kernels);
               NEXT_PASS (pass_fre);
               NEXT_PASS (pass_tree_loop_init);
               NEXT_PASS (pass_lim);
               NEXT_PASS (pass_copy_prop);
               NEXT_PASS (pass_scev_cprop);
               NEXT_PASS (pass_parallelize_loops_oacc_kernels);
               NEXT_PASS (pass_expand_omp_ssa);
               NEXT_PASS (pass_tree_loop_done);
...

The patch moves pass_fre to the location of pass_copy_prop, and replaces 
it.  Furthermore, it adds scans to the fortran test-cases to make sure 
they get properly parallelized.

Bootstrapped and reg-tested on x86_64.

Committed to gomp-4_0-branch.

Thanks,
- Tom