<html>
<head>
<base href="https://bugs.llvm.org/">
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Missing overflow check for ++x compared to x += 1"
href="https://bugs.llvm.org/show_bug.cgi?id=44054">44054</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Missing overflow check for ++x compared to x += 1
</td>
</tr>
<tr>
<th>Product</th>
<td>compiler-rt
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>ubsan
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>cullmann@absint.de
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>If you use this example:
int main()
{
signed char x = 127;
x += 1;
return 0;
}
with -fsanitize=integer you get a proper:
main.cpp:4:7: runtime error: implicit conversion from type 'int' of value 128
(32-bit, signed) to type 'signed char' changed the value to -128 (8-bit,
signed)
If you alter this to
int main()
{
signed char x = 127;
++x;
return 0;
}
no longer any check is done. In the IR already the call to the overflow stuff
is missing.
I am not sure if this is the right component to report, thought.
(Or if I miss some option to get this kind of overflow alarm)</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>