* regrename.h (struct du_head): Add target_data_1 and target_data_2

	* regrename.h (struct du_head): Add target_data_1 and target_data_2
	fields.
	* regrename.c (create_new_chain): Clear entire struct after allocating.

	* config/i386/i386.opt (mmitigate-rop): New option.
	* doc/invoke.texi (mmitigate-rop): Document.
	* config/i386/i386.c: Include "regrename.h".
	(ix86_rop_should_change_byte_p, reg_encoded_number,
	ix86_get_modrm_for_rop, set_rop_modrm_reg_bits, ix86_mitigate_rop): New
	static functions.
	(ix86_reorg): Call ix86_mitigate_rop if -fmitigate-rop.
	* config/i386/i386.md (attr "modrm_class"): New.
	(cmp<mode>_ccno_1, mov<mode>_xor, movstrict<mode>_xor,
	x86_mov<mode>cc_0_m1. x86_mov<mode>cc_0_m1_se)
	(x86_mov<mode>cc_0_m1_neg): Override modrm_class attribute.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@230543 138bc75d-0d04-0410-961f-82ee72b054a4