<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 - [coroutines] musttail and -fstack-protector-all interactions don't mix well"
href="https://bugs.llvm.org/show_bug.cgi?id=43069">43069</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>[coroutines] musttail and -fstack-protector-all interactions don't mix well
</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>Linux
</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>Transformation Utilities
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>gornishanov@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>In this example, stack-protector-all will insert code before the return that
will prevent symmetric coroutine transfer.
Due to <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - Need to add product version numbers"
href="show_bug.cgi?id=1">bug#1</a> it will result in stack overflow when symmetric transfer is
required for correctness.
With <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - Need to add product version numbers"
href="show_bug.cgi?id=1">bug#1</a> fixed, the code will fail to compile, since musttail won't be
honored.
<a href="https://godbolt.org/z/7T_YnR">https://godbolt.org/z/7T_YnR</a>
// -O2 -stdlib=libc++ -std=c++2a -fstack-protector-all
// <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - Need to add product version numbers"
href="show_bug.cgi?id=1">Bug#1</a>, [coroutines] CoroSplit fails to add musttaill under -O2)
// <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - Customize Bugzilla to have some LLVM flavah"
href="show_bug.cgi?id=2">Bug#2</a>, fstack-protector-all interactions prevent tail call (this bug)
#include <experimental/coroutine>
using namespace std::experimental;
struct coro {
struct promise_type {
suspend_always initial_suspend() { return {}; }
suspend_always final_suspend() { return {}; }
void return_void() {}
void unhandled_exception(){}
coro get_return_object() { return{};}
};
};
coroutine_handle<> h;
struct sym {
bool await_ready() { return false; }
void await_resume() {}
auto await_suspend(coroutine_handle<>) { return h; }
};
coro f() { co_await sym{}; }</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>