cfgloop: Make loops_list support an optional loop_p root

This patch follows Richi's suggestion to add one optional
argument class loop* root to loops_list's CTOR, it can
provide the ability to construct a visiting list starting
from the given class loop* ROOT rather than the default
tree_root of loops_for_fn (FN), for visiting a subset of
the loop tree.

It unifies all orders of walkings into walk_loop_tree, but
it still uses linear search for LI_ONLY_INNERMOST when
looking at the whole loop tree since it has a more stable
bound.

gcc/ChangeLog:

	* cfgloop.h (loops_list::loops_list): Add one optional argument
	root and adjust accordingly, update loop tree walking and factor
	out to ...
	* cfgloop.c (loops_list::walk_loop_tree): ... this.  New function.

0 files changed, 0 insertions, 0 deletions