rtl.h (struct rtx_def): Update comments.

rtl.h (struct rtx_def): Update comments.

	* rtl.h (struct rtx_def): Update comments.
	(RTL_FLAG_CHECK[12345678]): New.  (rtl_check_failed_flag): Declare.
	(RTL_FLAG): New.  (CLEAR_RTX_FLAGS): New.  (flag access macros): Use
	RTL_FLAG_CHECK macros with list of expected RTL codes.
	* rtl.c (copy_rtx, shallow_copy_rtx): Use RTX_FLAG macro.
	(rtl_check_failed_flag): New.
	* reload1.c (reload): Use REG macro before changing rtx to MEM.
	(reload_cse_noop_set_p): Check rtx code before using access macro.
	* config/ia64/ia64.c (process_for_unwind_directive): Check rtx code
	before using access macro.

From-SVN: r53245