* tree-ssa-dce.c (DCE_TODOs): New.

	(propagate_necessity): Return if something changed.
	(eliminate_unnecessary_stmts): Likewise.
	(perform_tree_ssa_dce): Return TODO flags when needed.
	(pass_dce, pass_dce_loop, pass_cd_dce): Remove TODO flags.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@120797 138bc75d-0d04-0410-961f-82ee72b054a4