2019-11-21  Richard Biener  <rguenther@suse.de>

	* cfgloop.h (loop_iterator::~loop_iterator): Remove.
	(loop_iterator::to_visit): Use an auto_vec with internal storage.
	(loop_iterator::loop_iterator): Adjust.
	* cfganal.c (compute_dominance_frontiers_1): Fold into...
	(compute_dominance_frontiers): ... this.  Hoist invariant
	get_immediate_dominator call.
	(compute_idf): Use a work-set instead of a work-list for more
	optimal iteration order and duplicate avoidance.
	* tree-into-ssa.c (mark_phi_for_rewrite): Avoid re-allocating
	the vector all the time, instead pre-allocate the vector only
	once.
	(delete_update_ssa): Simplify.
	* vec.h (va_heap::release): Disable -Wfree-nonheap-object around it.

From-SVN: r278550