/*
 * Copyright (C) 2014 Oracle.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
 */

#include "smatch.h"
#include "smatch_extra.h"

static int my_id;

STATE(readl);
STATE(readl_ff);
STATE(readl_00);

DECLARE_PTR_LIST(state_stack, struct smatch_state);
struct state_stack *state_at_start;

static int readl_has_been_called;
static int returned;

static int is_readl_call(struct expression *expr)
{
        struct symbol *sym;

        expr = strip_expr(expr);
        if (expr->type != EXPR_CALL)
                return 0;
        if (expr->fn->type != EXPR_SYMBOL)
                return 0;
        sym = expr->fn->symbol;
        if (!sym || !sym->ident)
                return 0;
        if (strcmp(sym->ident->name, "readl") != 0)
                return 0;
        return 1;
}

static int is_readl(struct expression *expr)
{
        if (is_readl_call(expr))
                return 1;
        if (get_state_expr(my_id, expr) == &readl)
                return 1;
        return 0;
}

static void match_assign(struct expression *expr)
{
        if (is_readl(expr->right))
                set_state_expr(my_id, expr->left, &readl);
        else if (get_state_expr(my_id, expr->left))
                set_state_expr(my_id, expr->left, &undefined);
}

static int condition_depends_on_readl(struct expression *expr)
{
        if (expr->type == EXPR_BINOP) {
                if (condition_depends_on_readl(expr->left))
                        return 1;
                if (condition_depends_on_readl(expr->right))
                        return 1;
                return 0;
        }
        if (is_readl(expr))
                return 1;
        return 0;
}

static void check_condition(struct expression *expr)
{
        if (expr->op != '&')
                return;
        if (!condition_depends_on_readl(expr))
                return;
        readl_has_been_called = 1;
        set_true_false_states(my_id, "depends on", NULL, &readl_ff, &readl_00);
}

static void match_return(struct expression *expr)
{

        if (__inline_fn)
                return;
        returned = 1;
#if 0
        struct smatch_state *tmp;

        if (!readl_has_been_called)
                return;

        FOR_EACH_PTR(state_at_start, tmp) {
                REPLACE_CURRENT_PTR(tmp, NULL);
        }
#endif
}

static void push_state_at_start(struct smatch_state *state)
{
        add_ptr_list(&state_at_start, state);
}

static struct smatch_state *pop_state_at_start(void)
{
        struct smatch_state *state;

        state = last_ptr_list((struct ptr_list *)state_at_start);
        delete_ptr_list_last((struct ptr_list **)&state_at_start);
        return state;
}

static void before_loop(struct statement *stmt)
{
        struct smatch_state *state;

        if (!stmt || stmt->type != STMT_ITERATOR)
                return;
        if (ptr_list_empty((struct ptr_list *)state_at_start))
                returned = 0;
        state = get_state(my_id, "depends on", NULL);
        push_state_at_start(state);
}

static void after_loop(struct statement *stmt)
{
        struct smatch_state *old_state;

        if (!stmt || stmt->type != STMT_ITERATOR)
                return;
        old_state = pop_state_at_start();
        if (old_state == &readl_00)
                return;
        if (returned)
                return;
        if (get_state(my_id, "depends on", NULL) != &readl_00)
                return;
        sm_warning("this loop depends on readl() succeeding");
}

void check_readl_infinite_loops(int id)
{
        if (option_project != PROJ_KERNEL)
                return;

        my_id = id;

        add_hook(match_assign, ASSIGNMENT_HOOK);
        add_hook(check_condition, CONDITION_HOOK);

        add_hook(&match_return, RETURN_HOOK);

        add_hook(before_loop, STMT_HOOK);
        add_hook(after_loop, STMT_HOOK_AFTER);
}