<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 - dereferenceable_or_null prevents tail call"
href="https://bugs.llvm.org/show_bug.cgi?id=43894">43894</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>dereferenceable_or_null prevents tail call
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>All
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>Common Code Generator Code
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>nok.raven@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>The dereferenceable_or_null attribute prevents tail call:
define i8* @foo() {
%1 = tail call i8* @qaz()
ret i8* %1
}
define i8* @bar() {
%1 = tail call dereferenceable_or_null(1) i8* @qaz()
ret i8* %1
}
declare i8* @qaz()
<a href="https://godbolt.org/z/ar_VZO">https://godbolt.org/z/ar_VZO</a>
Because of that there is a regression in Clang 10 (trunk 375507) which is
marking calls to malloc/calloc with dereferenceable_or_null attribute.
#include <stdlib.h>
void* foo(void) {
return calloc(1, 1);
}
void* bar(void) {
return malloc(1);
}
<a href="https://godbolt.org/z/Cg2jas">https://godbolt.org/z/Cg2jas</a></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>