From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Thu, 27 Jun 2013 08:07:25 +0000 (+0300)
Subject: comparison: handle divide "a = b / 2"
X-Git-Tag: 1.59~33
X-Git-Url: https://repo.or.cz/w/smatch.git/commitdiff_plain/ee4cbd5ded1e2ebb4d987d5e76639672af9a0e64

comparison: handle divide "a = b / 2"

If you have code like:

	a = b / sizeof(int);

Then "a < b".

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

diff --git a/smatch_comparison.c b/smatch_comparison.c
index 6c136e51..5b3f2305 100644
--- a/smatch_comparison.c
+++ b/smatch_comparison.c
@@ -605,6 +605,21 @@ static void match_assign_sub(struct expression *expr)
 	}
 }
 
+static void match_assign_divide(struct expression *expr)
+{
+	struct expression *right;
+	struct expression *r_left, *r_right;
+	sval_t min;
+
+	right = strip_expr(expr->right);
+	r_left = strip_expr(right->left);
+	r_right = strip_expr(right->right);
+	if (!get_implied_min(r_right, &min) || min.value <= 1)
+		return;
+
+	add_comparison(expr->left, '<', r_left);
+}
+
 static void match_binop_assign(struct expression *expr)
 {
 	struct expression *right;
@@ -614,6 +629,8 @@ static void match_binop_assign(struct expression *expr)
 		match_assign_add(expr);
 	if (right->op == '-')
 		match_assign_sub(expr);
+	if (right->op == '/')
+		match_assign_divide(expr);
 }
 
 static void copy_comparisons(struct expression *left, struct expression *right)
diff --git a/validation/sm_compare9.c b/validation/sm_compare9.c
new file mode 100644
index 00000000..87f772c5
--- /dev/null
+++ b/validation/sm_compare9.c
@@ -0,0 +1,17 @@
+#include "check_debug.h"
+
+void *a, *b;
+static int options_write(void)
+{
+	a = b / 2;
+	__smatch_compare(a, b);
+}
+
+/*
+ * check-name: smatch compare #9
+ * check-command: smatch -I.. sm_compare9.c
+ *
+ * check-output-start
+sm_compare9.c:7 options_write() a < b
+ * check-output-end
+ */