<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 - std::condition_variable::wait_for unconditionally uses 'long double' arithmetic, using emulation code on ARM"
href="https://bugs.llvm.org/show_bug.cgi?id=42351">42351</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>std::condition_variable::wait_for unconditionally uses 'long double' arithmetic, using emulation code on ARM
</td>
</tr>
<tr>
<th>Product</th>
<td>libc++
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</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>All Bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>jacob.benoit.1@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, mclow.lists@gmail.com
</td>
</tr></table>
<p>
<div>
<pre>See
<a href="https://git.llvm.org/klaus/libcxx/blob/release_37/include/__mutex_base#L-379">https://git.llvm.org/klaus/libcxx/blob/release_37/include/__mutex_base#L-379</a>
Use of 'long double' here may seem innocuous from a x86 perspective, but on ARM
(both A32 and A64) it causes the compiler to emit emulation code. I can live
with the slowness in this context, but we discovered this while debugging a
binary size regression (+8k) from a change to a program that made it use
wait_until (which, in current libc++ implementation, calls wait_for).
Top symbols added:
size (bytes) type name
+0000000000002836 t __subtf3
@@ -127,0 +129 @@
+0000000000001760 t __multf3
@@ -934,0 +937,2 @@
+0000000000000316 t __lttf2
+0000000000000316 t __letf2</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>