Hi,
This simple patch computes and preserves loop nest vector for whole distribution
life time.  The loop nest will be used multiple times in on-demand data dependence
computation.

Bootstrap and test on x86_64 and AArch64.  Is it OK?

Thanks,
bin
2017-06-07  Bin Cheng  <bin.cheng@arm.com>

	* tree-loop-distribution.c (loop_nest): New global var.
	(build_rdg): Use loop directly, rather than loop nest.
	(pg_add_dependence_edges): Remove loop nest parameter.  Use global
	variable directly.
	(distribute_loop): Compute global variable loop nest.  Update use.