From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Thu, 27 Jun 2013 08:03:25 +0000 (+0300)
Subject: comparison: stop caring so much about wrapping (it's rare)
X-Git-Tag: 1.59~34
X-Git-Url: https://repo.or.cz/w/smatch.git/commitdiff_plain/61792987c9e43a859a1cf191f7967b2efa9968e1

comparison: stop caring so much about wrapping (it's rare)

If we have code like:

	a = b + 1;

Then it's possible that "b + 1" might wrap, but it's more likely that it
won't so lets say that "a > b".

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---

diff --git a/smatch_comparison.c b/smatch_comparison.c
index 7e13c35d..6c136e51 100644
--- a/smatch_comparison.c
+++ b/smatch_comparison.c
@@ -564,29 +564,18 @@ static void match_assign_add(struct expression *expr)
 	r_left = strip_expr(right->left);
 	r_right = strip_expr(right->right);
 
-	if (!is_capped(expr->left)) {
-		get_absolute_max(r_left, &left_tmp);
-		get_absolute_max(r_right, &right_tmp);
-		if (sval_binop_overflows(left_tmp, '+', right_tmp))
-			return;
-	}
-
 	get_absolute_min(r_left, &left_tmp);
-	if (sval_is_negative(left_tmp))
-		return;
 	get_absolute_min(r_right, &right_tmp);
-	if (sval_is_negative(right_tmp))
-		return;
 
-	if (left_tmp.value == 0)
-		add_comparison(expr->left, SPECIAL_GTE, r_right);
-	else
+	if (left_tmp.value > 0)
 		add_comparison(expr->left, '>', r_right);
+	else if (left_tmp.value == 0)
+		add_comparison(expr->left, SPECIAL_GTE, r_right);
 
-	if (right_tmp.value == 0)
-		add_comparison(expr->left, SPECIAL_GTE, r_left);
-	else
+	if (right_tmp.value > 0)
 		add_comparison(expr->left, '>', r_left);
+	else if (right_tmp.value == 0)
+		add_comparison(expr->left, SPECIAL_GTE, r_left);
 }
 
 static void match_assign_sub(struct expression *expr)
diff --git a/validation/sm_compare8.c b/validation/sm_compare8.c
new file mode 100644
index 00000000..87b5d641
--- /dev/null
+++ b/validation/sm_compare8.c
@@ -0,0 +1,17 @@
+#include "check_debug.h"
+
+void *a, *b;
+static int options_write(void)
+{
+	a = b + 1;
+	__smatch_compare(a, b);
+}
+
+/*
+ * check-name: smatch compare #8
+ * check-command: smatch -I.. sm_compare8.c
+ *
+ * check-output-start
+sm_compare8.c:7 options_write() a > b
+ * check-output-end
+ */