/*
 * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
 * See the copyright notice in the ACK home directory, in the file "Copyright".
 */
/* $Header$ */
/*	Lint state stack	*/

/* These datastructures are used to implement a stack on which the
 * state of automatic variables (including register variables) is
 * kept.
 * In this way it is possible to account for the flow of
 * control of the program.
 */

#define	TEST_VAR	0		/* not a constant */
#define	TEST_TRUE	1		/* always true */
#define	TEST_FALSE	2		/* always false */

struct loop_state {			/* used in lint_end_state only */
	int lps_test;			/* is the test a constant? */
	struct state *lps_body;
	struct state *lps_loop;
};

struct switch_state {			/* used in lint_end_state only */
	struct state *sws_case;
	struct state *sws_break;
	int sws_default_met;
};

/*	This union describes the (possibly incomplete) state at the end of the
	mentioned construct.
*/
union lint_end_state {			/* used in lint_stack_entry only */
	struct state *ule_if;
	struct loop_state ule_loop;
	struct switch_state ule_switch;
};

struct lint_stack_entry {
	struct lint_stack_entry *next;
	struct lint_stack_entry *ls_previous;
	int ls_level;
	struct state *ls_current;	/* used by all classes */
	short ls_class;			/* IF, WHILE, DO, FOR, SWITCH, CASE */
	union lint_end_state ls_end;
};

/* ALLOCDEF "lint_stack_entry" 10 */

/* macros to access the union */
#define LS_IF	 	ls_end.ule_if
#define LS_TEST		ls_end.ule_loop.lps_test
#define LS_BODY		ls_end.ule_loop.lps_body
#define LS_LOOP		ls_end.ule_loop.lps_loop
#define LS_CASE		ls_end.ule_switch.sws_case
#define LS_BREAK	ls_end.ule_switch.sws_break
#define LS_DEFAULT_MET	ls_end.ule_switch.sws_default_met

/* describes a branch in the program, with its local idfs */
struct state {
	struct state *next;		/* only used by memory allocator */
	struct auto_def *st_auto_list;
	int st_notreached;		/* set if not reached */
	int st_warned;			/* set if warning issued */
};

/* ALLOCDEF "state" 15 */

/* describes the state of a local idf in a given branch of the program */
struct auto_def {
	struct auto_def *next;
	struct idf *ad_idf;
	struct def *ad_def;
	int ad_used;
	int ad_set;
	int ad_maybe_set;
};

/* ALLOCDEF "auto_def" 20 */

/* describes the state of an idf during expression evaluation */
struct expr_state {			/*actually concerns idfs only */
	struct expr_state *next;
	struct idf *es_idf;		/* the idf with its offset */
	arith es_offset;
	int es_used;			/* value has been used */
	int es_referred;		/* address has been taken */
	int es_set;			/* has been assigned to */
};

/* ALLOCDEF "expr_state" 20 */