tree-optimization/103690 - not up-to-date SSA and PRE DCE

tree-optimization/103690 - not up-to-date SSA and PRE DCE

This avoids running simple_dce_from_worklist on partially not up-to-date
SSA form (in unreachable code regions) by scheduling CFG cleanup
manually as is done anyway when tail-merging runs.

2022-01-04  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/103690
	* tree-pass.h (tail_merge_optimize): Adjust.
	* tree-ssa-tail-merge.c (tail_merge_optimize): Pass in whether
	to re-split critical edges, move CFG cleanup ...
	* tree-ssa-pre.c (pass_pre::execute): ... here, before
	simple_dce_from_worklist and delay freeing inserted_exprs from
	...
	(fini_pre): .. here.