2017-11-05  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/82471
	* lang.opt (ffrontend-loop-interchange): New option.
	(Wfrontend-loop-interchange): New option.
	* options.c (gfc_post_options): Handle ffrontend-loop-interchange.
	* frontend-passes.c (gfc_run_passes): Run
	optimize_namespace if flag_frontend_optimize or
	flag_frontend_loop_interchange are set.
	(optimize_namespace): Run functions according to flags set;
	also call index_interchange.
	(ind_type): New function.
	(has_var): New function.
	(index_cost): New function.
	(loop_comp): New function.

2017-11-05  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/82471
	* gfortran.dg/loop_interchange_1.f90: New test.

From-SVN: r254430