<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 - Should synthetic sections be InputSections or OutputSections?"
href="https://bugs.llvm.org/show_bug.cgi?id=49780">49780</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Should synthetic sections be InputSections or OutputSections?
</td>
</tr>
<tr>
<th>Product</th>
<td>lld
</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>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>MachO
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>smeenai@fb.com
</td>
</tr>
<tr>
<th>CC</th>
<td>gkm@fb.com, jezreel@gmail.com, llvm-bugs@lists.llvm.org, smeenai@fb.com, smithp352@googlemail.com, vyng@google.com
</td>
</tr></table>
<p>
<div>
<pre>We decided to make SyntheticSections be OutputSections back in
<a href="https://reviews.llvm.org/D77893#inline-716459">https://reviews.llvm.org/D77893#inline-716459</a>. We were debating why ELF makes
them InputSections; it appears the main motivation for that design was to allow
synthetic sections to be manipulated via linker scripts, which we don't need to
support with Mach-O.
Peter Smith gave a talk on LLD's performace
(<a href="https://archive.fosdem.org/2019/schedule/event/llvm_lld/">https://archive.fosdem.org/2019/schedule/event/llvm_lld/</a>), in which he
mentioned that LLD's synthetic sections being input sections (as opposed to
output sections) significantly sped up thunks (at the 25:10 mark). Our thunk
design will likely be closer to COFF's than ELF's, so I'd be curios if this has
an effect for us.
We discussed this further in <a href="https://reviews.llvm.org/D87199#2264781">https://reviews.llvm.org/D87199#2264781</a>, where we
decided to defer any potential refactoring until we were more feature-complete.
I don't think we're still at the point where we'd consider this refactoring
yet, but it's worth keeping in mind for the future.</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>