Tie chains for move instructions.

Tie chains for move instructions.

gcc/
	* regrename.c (create_new_chain): Initialize renamed and tied_chain.
	(build_def_use): Initialize terminated_this_insn.
	(find_best_rename_reg): Pick and check register from the tied chain.
	(regrename_do_replace): Mark head as renamed.
	(struct du_head *terminated_this_insn). New static variable.
	(scan_rtx_reg): Tie chains in move insns.  Set terminated_this_insn.
	* regrename.h (struct du_head): Add tied_chain, renamed members.

From-SVN: r230087