--- /dev/null	Fri Dec 21 15:00:28 2018
+++ new/usr/src/tools/smatch/src/smatch_param_compare_limit.c	Fri Dec 21 15:00:28 2018
@@ -0,0 +1,373 @@
+/*
+ * Copyright (C) 2016 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
+ */
+
+/*
+ * The point here is to store the relationships between two variables.
+ * Ie:  y > x.
+ * To do that we create a state with the two variables in alphabetical order:
+ * ->name = "x vs y" and the state would be "<".  On the false path the state
+ * would be ">=".
+ *
+ * Part of the trick of it is that if x or y is modified then we need to reset
+ * the state.  We need to keep a list of all the states which depend on x and
+ * all the states which depend on y.  The link_id code handles this.
+ *
+ */
+
+#include "smatch.h"
+#include "smatch_extra.h"
+#include "smatch_slist.h"
+
+static int compare_id;
+static int link_id;
+
+static struct smatch_state *alloc_link_state(struct string_list *links)
+{
+	struct smatch_state *state;
+	static char buf[256];
+	char *tmp;
+	int i;
+
+	state = __alloc_smatch_state(0);
+
+	i = 0;
+	FOR_EACH_PTR(links, tmp) {
+		if (!i++) {
+			snprintf(buf, sizeof(buf), "%s", tmp);
+		} else {
+			append(buf, ", ", sizeof(buf));
+			append(buf, tmp, sizeof(buf));
+		}
+	} END_FOR_EACH_PTR(tmp);
+
+	state->name = alloc_sname(buf);
+	state->data = links;
+	return state;
+}
+
+static struct smatch_state *merge_links(struct smatch_state *s1, struct smatch_state *s2)
+{
+	struct smatch_state *ret;
+	struct string_list *links;
+
+	links = combine_string_lists(s1->data, s2->data);
+	ret = alloc_link_state(links);
+	return ret;
+}
+
+static void save_link_var_sym(const char *var, struct symbol *sym, const char *link)
+{
+	struct smatch_state *old_state, *new_state;
+	struct string_list *links;
+	char *new;
+
+	old_state = get_state(link_id, var, sym);
+	if (old_state)
+		links = clone_str_list(old_state->data);
+	else
+		links = NULL;
+
+	new = alloc_sname(link);
+	insert_string(&links, new);
+
+	new_state = alloc_link_state(links);
+	set_state(link_id, var, sym, new_state);
+}
+
+static void add_comparison_var_sym(const char *left_name,
+		struct var_sym_list *left_vsl,
+		int comparison,
+		const char *right_name, struct var_sym_list *right_vsl)
+{
+	struct smatch_state *state;
+	struct var_sym *vs;
+	char state_name[256];
+
+	if (strcmp(left_name, right_name) > 0) {
+		const char *tmp_name = left_name;
+		struct var_sym_list *tmp_vsl = left_vsl;
+
+		left_name = right_name;
+		left_vsl = right_vsl;
+		right_name = tmp_name;
+		right_vsl = tmp_vsl;
+		comparison = flip_comparison(comparison);
+	}
+	snprintf(state_name, sizeof(state_name), "%s vs %s", left_name, right_name);
+	state = alloc_compare_state(NULL, left_name, left_vsl, comparison, NULL, right_name, right_vsl);
+
+	set_state(compare_id, state_name, NULL, state);
+
+	FOR_EACH_PTR(left_vsl, vs) {
+		save_link_var_sym(vs->var, vs->sym, state_name);
+	} END_FOR_EACH_PTR(vs);
+	FOR_EACH_PTR(right_vsl, vs) {
+		save_link_var_sym(vs->var, vs->sym, state_name);
+	} END_FOR_EACH_PTR(vs);
+}
+
+/*
+ * This is quite a bit more limitted, less ambitious, simpler compared to
+ * smatch_camparison.c.
+ */
+void __compare_param_limit_hook(struct expression *left_expr, struct expression *right_expr,
+				const char *state_name,
+				struct smatch_state *true_state, struct smatch_state *false_state)
+{
+	char *left_name = NULL;
+	char *right_name = NULL;
+	char *tmp_name = NULL;
+	struct symbol *left_sym, *right_sym, *tmp_sym;
+
+	left_name = expr_to_var_sym(left_expr, &left_sym);
+	if (!left_name || !left_sym)
+		goto free;
+	right_name = expr_to_var_sym(right_expr, &right_sym);
+	if (!right_name || !right_sym)
+		goto free;
+
+	if (get_param_num_from_sym(left_sym) < 0 ||
+	    get_param_num_from_sym(right_sym) < 0)
+		return;
+
+	tmp_name = get_other_name_sym(left_name, left_sym, &tmp_sym);
+	if (tmp_name) {
+		free_string(left_name);
+		left_name = tmp_name;
+		left_sym = tmp_sym;
+	}
+
+	tmp_name = get_other_name_sym(right_name, right_sym, &tmp_sym);
+	if (tmp_name) {
+		free_string(right_name);
+		right_name = tmp_name;
+		right_sym = tmp_sym;
+	}
+
+	if (param_was_set_var_sym(left_name, left_sym))
+		return;
+	if (param_was_set_var_sym(right_name, right_sym))
+		return;
+
+	set_true_false_states(compare_id, state_name, NULL, true_state, false_state);
+	save_link_var_sym(left_name, left_sym, state_name);
+	save_link_var_sym(right_name, right_sym, state_name);
+free:
+	free_string(left_name);
+	free_string(right_name);
+}
+
+static void print_return_comparison(int return_id, char *return_ranges, struct expression *expr)
+{
+	struct sm_state *tmp;
+	struct string_list *links;
+	char *link;
+	struct sm_state *sm;
+	struct compare_data *data;
+	struct var_sym *left, *right;
+	int left_param, right_param;
+	static char left_buf[256];
+	static char right_buf[256];
+	static char info_buf[256];
+	const char *tmp_name;
+
+	FOR_EACH_MY_SM(link_id, __get_cur_stree(), tmp) {
+		links = tmp->state->data;
+		FOR_EACH_PTR(links, link) {
+			sm = get_sm_state(compare_id, link, NULL);
+			if (!sm)
+				continue;
+			data = sm->state->data;
+			if (!data || !data->comparison)
+				continue;
+			if (ptr_list_size((struct ptr_list *)data->left_vsl) != 1 ||
+			    ptr_list_size((struct ptr_list *)data->right_vsl) != 1)
+				continue;
+			left = first_ptr_list((struct ptr_list *)data->left_vsl);
+			right = first_ptr_list((struct ptr_list *)data->right_vsl);
+			if (left->sym == right->sym &&
+			    strcmp(left->var, right->var) == 0)
+				continue;
+			/*
+			 * Both parameters link to this comparison so only
+			 * record the first one.
+			 */
+			if (left->sym != tmp->sym ||
+			    strcmp(left->var, tmp->name) != 0)
+				continue;
+
+			left_param = get_param_num_from_sym(left->sym);
+			right_param = get_param_num_from_sym(right->sym);
+			if (left_param < 0 || right_param < 0) /* can't happen hopefully */
+				continue;
+
+			tmp_name = get_param_name_var_sym(left->var, left->sym);
+			if (!tmp_name)
+				continue;
+			snprintf(left_buf, sizeof(left_buf), "%s", tmp_name);
+
+			tmp_name = get_param_name_var_sym(right->var, right->sym);
+			if (!tmp_name || tmp_name[0] != '$')
+				continue;
+			snprintf(right_buf, sizeof(right_buf), "$%d%s", right_param, tmp_name + 1);
+
+			snprintf(info_buf, sizeof(info_buf), "%s %s", show_special(data->comparison), right_buf);
+			sql_insert_return_states(return_id, return_ranges,
+					COMPARE_LIMIT, left_param, left_buf, info_buf);
+		} END_FOR_EACH_PTR(link);
+
+	} END_FOR_EACH_SM(tmp);
+}
+
+static int parse_comparison(char **value, int *op)
+{
+
+	*op = **value;
+
+	switch (*op) {
+	case '<':
+		(*value)++;
+		if (**value == '=') {
+			(*value)++;
+			*op = SPECIAL_LTE;
+		}
+		break;
+	case '=':
+		(*value)++;
+		(*value)++;
+		*op = SPECIAL_EQUAL;
+		break;
+	case '!':
+		(*value)++;
+		(*value)++;
+		*op = SPECIAL_NOTEQUAL;
+		break;
+	case '>':
+		(*value)++;
+		if (**value == '=') {
+			(*value)++;
+			*op = SPECIAL_GTE;
+		}
+		break;
+	default:
+		return 0;
+	}
+
+	if (**value != ' ') {
+		sm_perror("parsing comparison.  %s", *value);
+		return 0;
+	}
+
+	(*value)++;
+	return 1;
+}
+
+static int split_op_param_key(char *value, int *op, int *param, char **key)
+{
+	static char buf[256];
+	char *p;
+
+	if (!parse_comparison(&value, op))
+		return 0;
+
+	snprintf(buf, sizeof(buf), value);
+
+	p = buf;
+	if (*p++ != '$')
+		return 0;
+
+	*param = atoi(p);
+	if (*param < 0 || *param > 99)
+		return 0;
+	p++;
+	if (*param > 9)
+		p++;
+	p--;
+	*p = '$';
+	*key = p;
+
+	return 1;
+}
+
+static void db_return_comparison(struct expression *expr, int left_param, char *key, char *value)
+{
+	struct expression *left_arg, *right_arg;
+	char *left_name = NULL;
+	struct symbol *left_sym;
+	char *right_name = NULL;
+	struct symbol *right_sym;
+	int op;
+	int right_param;
+	char *right_key;
+	struct var_sym_list *left_vsl = NULL, *right_vsl = NULL;
+
+	while (expr->type == EXPR_ASSIGNMENT)
+		expr = strip_expr(expr->right);
+	if (expr->type != EXPR_CALL)
+		return;
+
+	if (!split_op_param_key(value, &op, &right_param, &right_key))
+		return;
+
+	left_arg = get_argument_from_call_expr(expr->args, left_param);
+	if (!left_arg)
+		return;
+
+	right_arg = get_argument_from_call_expr(expr->args, right_param);
+	if (!right_arg)
+		return;
+
+	left_name = get_variable_from_key(left_arg, key, &left_sym);
+	if (!left_name || !left_sym)
+		goto free;
+	if (get_param_num_from_sym(left_sym) < 0)
+		goto free;
+
+	right_name = get_variable_from_key(right_arg, right_key, &right_sym);
+	if (!right_name || !right_sym)
+		goto free;
+	if (get_param_num_from_sym(right_sym) < 0)
+		goto free;
+
+	add_var_sym(&left_vsl, left_name, left_sym);
+	add_var_sym(&right_vsl, right_name, right_sym);
+
+	add_comparison_var_sym(left_name, left_vsl, op, right_name, right_vsl);
+
+free:
+	free_string(left_name);
+	free_string(right_name);
+}
+
+void register_param_compare_limit(int id)
+{
+	compare_id = id;
+
+	add_merge_hook(compare_id, &merge_compare_states);
+	add_split_return_callback(&print_return_comparison);
+
+	select_return_states_hook(COMPARE_LIMIT, &db_return_comparison);
+}
+
+void register_param_compare_limit_links(int id)
+{
+	link_id = id;
+
+	add_merge_hook(link_id, &merge_links);
+
+}
+
