re PR debug/54796 (Non-addressable stack parameter debug quality regression)

	PR debug/54796
	* rtl.h: Document jump flag on VALUE.
	* cselib.h (cselib_set_value_sp_based,
	cselib_sp_based_value_p): New prototypes.
	* alias.c (find_base_term): For cselib_sp_based_value_p
	return static_reg_base_value[STACK_POINTER_REGNUM].
	* cselib.c (SP_BASED_VALUE_P): Define.
	(cselib_set_value_sp_based, cselib_sp_based_value_p): New functions.
	* var-tracking.c (add_stores): Call cselib_set_value_sp_based
	for not yet preserved VALUEs of sp on sp assignments if
	hard_frame_pointer_adjustment != -1.
	(vt_initialize): When setting hard_frame_pointer_adjustment,
	disassociate sp from its previous value and call
	cselib_set_value_sp_based on a new VALUE created for sp.

	* gcc.dg/guality/pr54796.c: New test.

From-SVN: r192494