/*
 * Copyright (C) 2012 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
 */

/*
 * This test is used to warn about mixups between bit shifters and bit flags.
 *
 */

#include "smatch.h"
#include "smatch_function_hashtable.h"

static int my_id;

static DEFINE_HASHTABLE_INSERT(insert_struct, char, int);
static DEFINE_HASHTABLE_SEARCH(search_struct, char, int);
static struct hashtable *shifters;

static const char *get_shifter(struct expression *expr)
{
        const char *name;
        sval_t expr_value;
        const int *shifter_value;

        expr = strip_expr(expr);
        if (expr->type != EXPR_VALUE)
                return NULL;
        if (!get_value(expr, &expr_value))
                return NULL;
        name = pos_ident(expr->pos);
        if (!name)
                return NULL;
        shifter_value = search_struct(shifters, (char *)name);
        if (!shifter_value)
                return NULL;
        if (sval_cmp_val(expr_value, *shifter_value) != 0)
                return NULL;
        return name;
}

static void match_assign(struct expression *expr)
{
        const char *name;

        if (expr->op != SPECIAL_OR_ASSIGN)
                return;
        if (positions_eq(expr->pos, expr->right->pos))
                return;
        name = get_shifter(expr->right);
        if (!name)
                return;

        sm_warning("'%s' is a shifter (not for '%s').",
                        name, show_special(expr->op));
}

static void match_binop(struct expression *expr)
{
        const char *name;

        if (positions_eq(expr->pos, expr->right->pos))
                return;
        if (expr->op != '&')
                return;
        name = get_shifter(expr->right);
        if (!name)
                return;

        sm_warning("bit shifter '%s' used for logical '%s'",
                        name, show_special(expr->op));
}

static void register_shifters(void)
{
        char filename[256];
        struct token *token;
        char *name;
        int *val;

        snprintf(filename, sizeof(filename), "%s.bit_shifters", option_project_str);
        token = get_tokens_file(filename);
        if (!token)
                return;
        if (token_type(token) != TOKEN_STREAMBEGIN)
                return;
        token = token->next;
        while (token_type(token) != TOKEN_STREAMEND) {
                if (token_type(token) != TOKEN_IDENT)
                        return;
                name = alloc_string(show_ident(token->ident));
                token = token->next;
                if (token_type(token) != TOKEN_NUMBER)
                        return;
                val = malloc(sizeof(int));
                *val = atoi(token->number);
                insert_struct(shifters, name, val);
                token = token->next;
        }
        clear_token_alloc();
}

static void match_binop_info(struct expression *expr)
{
        char *name;
        sval_t sval;

        if (positions_eq(expr->pos, expr->right->pos))
                return;
        if (expr->op != SPECIAL_LEFTSHIFT)
                return;
        if (expr->right->type != EXPR_VALUE)
                return;
        name = pos_ident(expr->right->pos);
        if (!name)
                return;
        if (!get_value(expr->right, &sval))
                return;
        sm_msg("info: bit shifter '%s' '%s'", name, sval_to_str(sval));
}

static void match_call(const char *fn, struct expression *expr, void *_arg_no)
{
        struct expression *arg_expr;
        int arg_no = PTR_INT(_arg_no);
        sval_t sval;
        char *name;

        arg_expr = get_argument_from_call_expr(expr->args, arg_no);
        if (positions_eq(expr->pos, arg_expr->pos))
                return;
        name = pos_ident(arg_expr->pos);
        if (!name)
                return;
        if (!get_value(arg_expr, &sval))
                return;
        sm_msg("info: bit shifter '%s' '%s'", name, sval_to_str(sval));
}

void check_bit_shift(int id)
{
        my_id = id;

        shifters = create_function_hashtable(5000);
        register_shifters();

        add_hook(&match_assign, ASSIGNMENT_HOOK);
        add_hook(&match_binop, BINOP_HOOK);

        if (option_info) {
                add_hook(&match_binop_info, BINOP_HOOK);
                if (option_project == PROJ_KERNEL) {
                        add_function_hook("set_bit", &match_call, INT_PTR(0));
                        add_function_hook("test_bit", &match_call, INT_PTR(0));
                }
        }
}