Fix handling mutually exclusive states.

[smatch.git] / smatch_slist.c

/*
 * sparse/smatch_slist.c
 *
 * Copyright (C) 2008,2009 Dan Carpenter.
 *
 *  Licensed under the Open Software License version 1.1
 *
 */

#include <stdlib.h>
#include <stdio.h>
#include "smatch.h"
#include "smatch_slist.h"

#undef CHECKORDER

ALLOCATOR(sm_state, "smatch state");
ALLOCATOR(named_slist, "named slist");

void __print_slist(struct state_list *slist)
{
        struct sm_state *state;

        printf("dumping slist at %d\n", get_lineno());
        FOR_EACH_PTR(slist, state) {
                printf("%d '%s'=%s\n", state->owner, state->name,
                        show_state(state->state));
        } END_FOR_EACH_PTR(state);
        printf("---\n");
}

void add_history(struct sm_state *state)
{
        struct state_history *tmp;

        if (!state)
                return;
        tmp = malloc(sizeof(*tmp));
        tmp->loc = get_lineno();
        add_ptr_list(&state->line_history, tmp);
}


/* NULL states go at the end to simplify merge_slist */
int cmp_tracker(const struct sm_state *a, const struct sm_state *b)
{
        int ret;

        if (!a && !b)
                return 0;
        if (!b)
                return -1;
        if (!a)
                return 1;

        if (a->owner > b->owner)
                return -1;
        if (a->owner < b->owner)
                return 1;

        ret = strcmp(a->name, b->name);
        if (ret)
                return ret;

        if (!b->sym && a->sym)
                return -1;
        if (!a->sym && b->sym)
                return 1;
        if (a->sym > b->sym)
                return -1;
        if (a->sym < b->sym)
                return 1;

        return 0;
}

static int cmp_sm_states(const struct sm_state *a, const struct sm_state *b)
{
        int ret;

        ret = cmp_tracker(a, b);
        if (ret)
                return ret;

        /* todo:  add hook for smatch_extra.c */
        if (a->state > b->state)
                return -1;
        if (a->state < b->state)
                return 1;
        return 0;
}

void add_sm_state_slist(struct state_list **slist, struct sm_state *new)
{
        struct sm_state *tmp;

        FOR_EACH_PTR(*slist, tmp) {
                if (cmp_sm_states(tmp, new) < 0)
                        continue;
                else if (cmp_sm_states(tmp, new) == 0) {
                        return;
                } else {
                        INSERT_CURRENT(new, tmp);
                        return;
                }
        } END_FOR_EACH_PTR(tmp);
        add_ptr_list(slist, new);
}

static void add_possible(struct sm_state *sm, struct sm_state *new)
{
        struct sm_state *tmp;


        if (!new) {
                struct smatch_state *s;

                s = merge_states(sm->name, sm->owner, sm->sym, sm->state, NULL);
                tmp = alloc_state(sm->name, sm->owner, sm->sym, s);
                add_sm_state_slist(&sm->possible, tmp);
                return;
        }
        FOR_EACH_PTR(new->possible, tmp) {
                add_sm_state_slist(&sm->possible, tmp);
        } END_FOR_EACH_PTR(tmp);
}

struct sm_state *alloc_state(const char *name, int owner, 
                             struct symbol *sym, struct smatch_state *state)
{
        struct sm_state *sm_state = __alloc_sm_state(0);

        sm_state->name = (char *)name;
        sm_state->owner = owner;
        sm_state->sym = sym;
        sm_state->state = state;
        sm_state->line_history = NULL;
        add_history(sm_state);
        sm_state->pools = NULL;
        sm_state->possible = NULL;
        add_ptr_list(&sm_state->possible, sm_state);
        return sm_state;
}

struct sm_state *clone_state(struct sm_state *s)
{
        struct sm_state *tmp;

        tmp = alloc_state(s->name, s->owner, s->sym, s->state);
        tmp->pools = clone_stack(s->pools);
        tmp->possible = s->possible;
        return tmp;
}

int slist_has_state(struct state_list *slist, struct smatch_state *state)
{
        struct sm_state *tmp;

        FOR_EACH_PTR(slist, tmp) {
                if (tmp->state == state)
                        return 1;
        } END_FOR_EACH_PTR(tmp);
        return 0;
}

#ifdef CHECKORDER
static void check_order(struct state_list *slist)
{
        struct sm_state *state;
        struct sm_state *last = NULL;
        int printed = 0;

        FOR_EACH_PTR(slist, state) {
                if (last && cmp_tracker(state, last) <= 0) {
                        printf("Error.  Unsorted slist %d vs %d, %p vs %p, "
                               "%s vs %s\n", last->owner, state->owner, 
                               last->sym, state->sym, last->name, state->name);
                        printed = 1;
                }
                last = state;
        } END_FOR_EACH_PTR(state);

        if (printed)
                printf("======\n");
}
#endif

struct state_list *clone_slist(struct state_list *from_slist)
{
        struct sm_state *state;
        struct sm_state *tmp;
        struct state_list *to_slist = NULL;

        FOR_EACH_PTR(from_slist, state) {
                tmp = clone_state(state);
                add_ptr_list(&to_slist, tmp);
        } END_FOR_EACH_PTR(state);
#ifdef CHECKORDER
        check_order(to_slist);
#endif
        return to_slist;
}

struct state_list_stack *clone_stack(struct state_list_stack *from_stack)
{
        struct state_list *slist;
        struct state_list_stack *to_stack = NULL;

        FOR_EACH_PTR(from_stack, slist) {
                push_slist(&to_stack, slist);
        } END_FOR_EACH_PTR(slist);
        return to_stack;
}

// FIXME...  shouldn't we free some of these state pointers?
struct smatch_state *merge_states(const char *name, int owner,
                                  struct symbol *sym,
                                  struct smatch_state *state1,
                                  struct smatch_state *state2)
{
        struct smatch_state *ret;

        if (state1 == state2)
                ret = state1;
        else if (__has_merge_function(owner))
                ret = __client_merge_function(owner, name, sym, state1, state2); 
        else if (!state1 || !state2)
                ret = &undefined;
        else 
                ret = &merged;
        return ret;
}

/*
 * add_pool() adds a slist to ->pools. If the slist has already been
 * added earlier then it doesn't get added a second time.
 */
static void add_pool(struct sm_state *to, struct state_list *new)
{
        struct state_list *tmp;

        FOR_EACH_PTR(to->pools, tmp) {
                if (tmp < new)
                        continue;
                else if (tmp == new) {
                        return;
                } else {
                        INSERT_CURRENT(new, tmp);
                        return;
                }
        } END_FOR_EACH_PTR(tmp);
        add_ptr_list(&to->pools, new);
}

static void copy_pools(struct sm_state *to, struct sm_state *sm)
{
        struct state_list *tmp;

        if (!sm)
                return;

        FOR_EACH_PTR(sm->pools, tmp) {
                add_pool(to, tmp);
        } END_FOR_EACH_PTR(tmp);
}

struct sm_state *merge_sm_states(struct sm_state *one, struct sm_state *two)
{
        struct smatch_state *s;
        struct sm_state *result;

        s = merge_states(one->name, one->owner, one->sym, one->state,
                        (two?two->state:NULL));
        result = alloc_state(one->name, one->owner, one->sym, s);
        add_possible(result, one);
        add_possible(result, two);
        copy_pools(result, one);
        copy_pools(result, two);

        if (debug_states) {
                struct sm_state *tmp;
                int i = 0;

                printf("%d merge name='%s' owner=%d: %s + %s => %s (", 
                        get_lineno(), one->name, one->owner,
                        show_state(one->state), show_state(two?two->state:NULL),
                        show_state(s));

                FOR_EACH_PTR(result->possible, tmp) {
                        if (i++) {
                                printf(", ");
                        }
                        printf("%s", show_state(tmp->state));
                } END_FOR_EACH_PTR(tmp);
                printf(")\n");
        }

        return result;
}

struct sm_state *get_sm_state_slist(struct state_list *slist, const char *name,
                                int owner, struct symbol *sym)
{
        struct sm_state *state;

        if (!name)
                return NULL;

        FOR_EACH_PTR(slist, state) {
                if (state->owner == owner && state->sym == sym 
                    && !strcmp(state->name, name))
                        return state;
        } END_FOR_EACH_PTR(state);
        return NULL;
}

struct smatch_state *get_state_slist(struct state_list *slist, 
                                const char *name, int owner,
                                struct symbol *sym)
{
        struct sm_state *state;

        state = get_sm_state_slist(slist, name, owner, sym);
        if (state)
                return state->state;
        return NULL;
}

void overwrite_sm_state(struct state_list **slist, struct sm_state *state)
{
        struct sm_state *tmp;
        struct sm_state *new = clone_state(state); //fixme. why?
 
        FOR_EACH_PTR(*slist, tmp) {
                if (cmp_tracker(tmp, new) < 0)
                        continue;
                else if (cmp_tracker(tmp, new) == 0) {
                        tmp->state = new->state;
                        tmp->pools = new->pools;
                        tmp->possible = new->possible;
                        __free_sm_state(new);
                        return;
                } else {
                        INSERT_CURRENT(new, tmp);
                        return;
                }
        } END_FOR_EACH_PTR(tmp);
        add_ptr_list(slist, new);
}

void overwrite_sm_state_stack(struct state_list_stack **stack,
                        struct sm_state *state)
{
        struct state_list *slist;

        slist = pop_slist(stack);
        overwrite_sm_state(&slist, state);
        push_slist(stack, slist);
}

void set_state_slist(struct state_list **slist, const char *name, int owner,
                     struct symbol *sym, struct smatch_state *state)
{
        struct sm_state *tmp;
        struct sm_state *new = alloc_state(name, owner, sym, state);

        FOR_EACH_PTR(*slist, tmp) {
                if (cmp_tracker(tmp, new) < 0)
                        continue;
                else if (cmp_tracker(tmp, new) == 0) {
                        tmp->state = state;
                        tmp->pools = NULL;
                        tmp->possible = NULL;
                        add_ptr_list(&tmp->possible, tmp);
                        __free_sm_state(new);
                        return;
                } else {
                        INSERT_CURRENT(new, tmp);
                        return;
                }
        } END_FOR_EACH_PTR(tmp);
        add_ptr_list(slist, new);
}

void delete_state_slist(struct state_list **slist, const char *name, int owner,
                        struct symbol *sym)
{
        struct sm_state *state;

        FOR_EACH_PTR(*slist, state) {
                if (state->owner == owner && state->sym == sym 
                    && !strcmp(state->name, name)){
                        delete_ptr_list_entry((struct ptr_list **)slist,
                                              state, 1);
                        __free_sm_state(state);
                        return;
                }
        } END_FOR_EACH_PTR(state);
}


void push_slist(struct state_list_stack **list_stack, struct state_list *slist)
{
        add_ptr_list(list_stack, slist);
}

struct state_list *pop_slist(struct state_list_stack **list_stack)
{
        struct state_list *slist;

        slist = last_ptr_list((struct ptr_list *)*list_stack);
        delete_ptr_list_last((struct ptr_list **)list_stack);
        return slist;
}

void del_slist(struct state_list **slist)
{
        __free_ptr_list((struct ptr_list **)slist);
}

void del_slist_stack(struct state_list_stack **slist_stack)
{
        struct state_list *slist;
        
        FOR_EACH_PTR(*slist_stack, slist) {
                __free_ptr_list((struct ptr_list **)&slist);
        } END_FOR_EACH_PTR(slist);
        __free_ptr_list((struct ptr_list **)slist_stack);       
}

/*
 * set_state_stack() sets the state for the top slist on the stack.
 */
void set_state_stack(struct state_list_stack **stack, const char *name,
                     int owner, struct symbol *sym, struct smatch_state *state)
{
        struct state_list *slist;

        slist = pop_slist(stack);
        set_state_slist(&slist, name, owner, sym, state);
        push_slist(stack, slist);
}

/*
 * get_state_stack() gets the state for the top slist on the stack.
 */
struct smatch_state *get_state_stack(struct state_list_stack *stack,
                                     const char *name, int owner,
                                     struct symbol *sym)
{
        struct state_list *slist;
        struct smatch_state *ret;

        slist = pop_slist(&stack);
        ret = get_state_slist(slist, name, owner, sym);
        push_slist(&stack, slist);
        return ret;
}

/*
 * We want to find which states have been modified inside a branch.
 * If you have 2 &merged states they could be different states really 
 * and maybe one or both were modified.  We say it is unchanged if
 * the ->state pointers are the same and they belong to the same pools.
 * If they have been modified on both sides of a branch to the same thing,
 * it's still OK to say they are the same, because that means they won't
 * belong to any pools.
 */
static int is_really_same(struct sm_state *one, struct sm_state *two)
{
        struct state_list *tmp1;
        struct state_list *tmp2;

        if (one->state != two->state)
                return 0;

        PREPARE_PTR_LIST(one->pools, tmp1);
        PREPARE_PTR_LIST(two->pools, tmp2);
        for (;;) {
                if (!tmp1 && !tmp2)
                        return 1;
                if (tmp1 < tmp2) {
                        return 0;
                } else if (tmp1 == tmp2) {
                        NEXT_PTR_LIST(tmp1);
                        NEXT_PTR_LIST(tmp2);
                } else {
                        return 0;
                }
        }
        FINISH_PTR_LIST(tmp2);
        FINISH_PTR_LIST(tmp1);
        return 1;
}

/*
 * merge_slist() is called whenever paths merge, such as after
 * an if statement.  It takes the two slists and creates one.
 */
void merge_slist(struct state_list **to, struct state_list *slist)
{
        struct sm_state *to_state, *state, *tmp;
        struct state_list *results = NULL;
        struct state_list *implied_to = NULL;
        struct state_list *implied_from = NULL;

#ifdef CHECKORDER
        check_order(*to);
        check_order(slist);
#endif

        /* merging a null and nonnull path gives you only the nonnull path */
        if (!slist) {
                return;
        }
        if (!*to) {
                *to = clone_slist(slist);
                return;
        }

        implied_to = clone_slist(*to);
        implied_from = clone_slist(slist);

        PREPARE_PTR_LIST(*to, to_state);
        PREPARE_PTR_LIST(slist, state);
        for (;;) {
                if (!to_state && !state)
                        break;
                if (cmp_tracker(to_state, state) < 0) {
                        tmp = merge_sm_states(to_state, NULL);
                        add_pool(tmp, implied_to);
                        add_ptr_list(&results, tmp);
                        NEXT_PTR_LIST(to_state);
                } else if (cmp_tracker(to_state, state) == 0) {
                        tmp = merge_sm_states(to_state, state);
                        if (!is_really_same(to_state, state)) {
                                add_pool(tmp, implied_to);
                                add_pool(tmp, implied_from);
                        }
                        add_ptr_list(&results, tmp);
                        NEXT_PTR_LIST(to_state);
                        NEXT_PTR_LIST(state);
                } else {
                        tmp = merge_sm_states(state, NULL);
                        add_pool(tmp, implied_from);
                        add_ptr_list(&results, tmp);
                        NEXT_PTR_LIST(state);
                }
        }
        FINISH_PTR_LIST(state);
        FINISH_PTR_LIST(to_state);

        del_slist(to);
        *to = results;

        push_slist(&implied_pools, implied_from);
        push_slist(&implied_pools, implied_to);
}

/*
 * is_currently_in_pool() is used because we remove states from pools.
 * When set_state() is called then we set ->pools to NULL, but on 
 * other paths the state is still a member of those pools.
 * Confusing huh?
 * if (foo) {
 *        bar = 1;
 *        a = malloc();
 * }
 * if (!a)
 *        return;
 * if (bar)
 *        a->b = x;
 */
static int is_currently_in_pool(struct sm_state *sm, struct state_list *pool,
                        struct state_list *cur_slist)
{
        struct sm_state *cur_state;
        struct state_list *tmp;
        
        cur_state = get_sm_state_slist(cur_slist, sm->name, sm->owner, sm->sym);
        if (!cur_state)
                return 0;
        
        /* if it's the current state return false because then it's the state
           itself, not the state in the pool.  */
        /* fixme:  The above confusing comment is a load of rubbish.  
           this doesn't belong here, it belongs somewhere else. */
        if (sm->state == cur_state->state)
                return 0;


        FOR_EACH_PTR(cur_state->pools, tmp) {
                if (tmp == pool)
                        return 1;
        } END_FOR_EACH_PTR(tmp);
        return 0;
}

struct state_list *clone_states_in_pool(struct state_list *pool,
                                struct state_list *cur_slist)
{
        struct sm_state *state;
        struct sm_state *tmp;
        struct state_list *to_slist = NULL;

        FOR_EACH_PTR(pool, state) {
                if (state->state == &merged)
                        continue;
                if (is_currently_in_pool(state, pool, cur_slist)) {
                        tmp = clone_state(state);
                        add_ptr_list(&to_slist, tmp);
                }
        } END_FOR_EACH_PTR(state);
        return to_slist;
}

/*
 * filter() is used to find what states are the same across
 * a series of slists.
 * It takes a **slist and a *filter.  
 * It removes everything from **slist that isn't in *filter.
 * The reason you would want to do this is if you want to 
 * know what other states are true if one state is true.  (smatch_implied).
 */
void filter(struct state_list **slist, struct state_list *filter,
        struct state_list *cur_slist)
{
        struct sm_state *s_one, *s_two;
        struct state_list *results = NULL;

#ifdef CHECKORDER
        check_order(*slist);
        check_order(filter);
#endif

        PREPARE_PTR_LIST(*slist, s_one);
        PREPARE_PTR_LIST(filter, s_two);
        for (;;) {
                if (!s_one || !s_two)
                        break;
                if (cmp_tracker(s_one, s_two) < 0) {
                        NEXT_PTR_LIST(s_one);
                } else if (cmp_tracker(s_one, s_two) == 0) {
                        /* todo.  pointer comparison works fine for most things
                           except smatch_extra.  we may need a hook here. */
                        if (s_one->state == s_two->state && 
                                is_currently_in_pool(s_two, filter, cur_slist)
                                && s_one->state != &merged) {
                                add_ptr_list(&results, s_one);
                        }
                        NEXT_PTR_LIST(s_one);
                        NEXT_PTR_LIST(s_two);
                } else {
                        NEXT_PTR_LIST(s_two);
                }
        }
        FINISH_PTR_LIST(s_two);
        FINISH_PTR_LIST(s_one);

        del_slist(slist);
        *slist = results;
}

/*
 * and_slist_stack() is basically the same as popping the top two slists,
 * overwriting the one with the other and pushing it back on the stack.
 * The difference is that it checks to see that a mutually exclusive
 * state isn't included in both stacks.  If smatch sees something like
 * "if (a && !a)" it prints a warning.
 */
void and_slist_stack(struct state_list_stack **slist_stack)
{
        struct sm_state *tmp;
        struct smatch_state *tmp_state;
        struct state_list *tmp_slist = pop_slist(slist_stack);

        FOR_EACH_PTR(tmp_slist, tmp) {
                tmp_state = get_state_stack(*slist_stack, tmp->name,
                                            tmp->owner, tmp->sym);
                if (tmp_state && tmp_state != tmp->state) {
                        smatch_msg("mutually exclusive 'and' conditions states "
                                "'%s': %s + %s",
                                tmp->name, show_state(tmp_state),
                                show_state(tmp->state));
                }
                set_state_stack(slist_stack, tmp->name, tmp->owner, tmp->sym,
                                tmp->state);
        } END_FOR_EACH_PTR(tmp);
        del_slist(&tmp_slist);
}

/* 
 * or_slist_stack() is for if we have:  if (foo || bar) { foo->baz;
 * It pops the two slists from the top of the stack and merges them
 * together in a way that preserves the things they have in common
 * but creates a merged state for most of the rest.
 * You could have code that had:  if (foo || foo) { foo->baz;
 * It's this function which ensures smatch does the right thing.
 */
void or_slist_stack(struct state_list_stack **slist_stack)
{
        struct state_list *one;
        struct state_list *two;
        struct state_list *res = NULL;
        struct sm_state *tmp;
        struct sm_state *sm;
        struct sm_state *new_sm;

        one = pop_slist(slist_stack);
        two = pop_slist(slist_stack);

        FOR_EACH_PTR(one, tmp) {
                sm = get_sm_state_slist(two, tmp->name, tmp->owner, tmp->sym);
                new_sm = merge_sm_states(tmp, sm);
                add_ptr_list(&res, new_sm);
        } END_FOR_EACH_PTR(tmp);

        FOR_EACH_PTR(two, tmp) {
                sm = get_sm_state_slist(one, tmp->name, tmp->owner, tmp->sym);
                new_sm = merge_sm_states(tmp, sm);
                add_ptr_list(&res, new_sm);
        } END_FOR_EACH_PTR(tmp);

        push_slist(slist_stack, res);

        del_slist(&one);
        del_slist(&two);
}

/*
 * get_slist_from_named_stack() is only used for gotos.
 */
struct state_list **get_slist_from_named_stack(struct named_stack *stack,
                                              const char *name)
{
        struct named_slist *tmp;

        FOR_EACH_PTR(stack, tmp) {
                if (!strcmp(tmp->name, name))
                        return &tmp->slist;
        } END_FOR_EACH_PTR(tmp);
        return NULL;
}

void overwrite_slist(struct state_list *from, struct state_list **to)
{
        struct sm_state *tmp;

        FOR_EACH_PTR(from, tmp) {
                overwrite_sm_state(to, tmp);
        } END_FOR_EACH_PTR(tmp);
}