* tree-pass.h (pass_phi_only_copy_prop): Delete.
	(pass_phi_only_cprop): Declare.
	* passes.c (init_optimization_passes): Replace pass_phi_only_copy_prop
	with phi_only_cprop
	* tree-ssa-dom.c (degenerate_phi_result): New function.
	(remove_stmt_or_phi, get_lhs_or_phi_result): Likewise.
	(get_rhs_or_phi_arg, propagate_rhs_into_lhs): Likewise.
	(eliminate_const_or_copy, eliminate_degenerate_phis_1): Likewise.
	(eliminate_degenerate_phis): Likewise.
	(pass_phi_only_cprop): New pass descriptor.
	* tree-ssa-copy.c (init_copy_prop): Lose PHIS_ONLY argument and
	support code.  Callers updated.
	(execute_copy_prop, do_copy_prop): Likewise and corresponding changes.
	(store_copy_prop): Likewise.
	(do_phi_only_copy_prop, pass_phi_only_copy_prop): Remove.

	* gcc.dg/tree-ssa/pr21829.c: New test.

From-SVN: r112242