<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 - [clang-cl] Implement /d2FH4 to emit compact Win64 xdata"
href="https://bugs.llvm.org/show_bug.cgi?id=40996">40996</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>[clang-cl] Implement /d2FH4 to emit compact Win64 xdata
</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>Windows NT
</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>Backend: X86
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>rnk@google.com
</td>
</tr>
<tr>
<th>CC</th>
<td>craig.topper@gmail.com, llvm-bugs@lists.llvm.org, llvm-dev@redking.me.uk, spatel+llvm@rotateright.com
</td>
</tr></table>
<p>
<div>
<pre>Visual C++ folks appear to have optimized x64 EH data (.xdata), as described
here:
<a href="https://devblogs.microsoft.com/cppblog/making-cpp-exception-handling-smaller-x64/">https://devblogs.microsoft.com/cppblog/making-cpp-exception-handling-smaller-x64/</a>
The new flag is available in VS 2019 preview 3. The new __CxxFrameHandler4
personality function uses more compact tables for smaller binary size. We
should follow suit at some point.
For users that don't use exceptions, I am curious about how they reduced the
size of the unwind opcodes, which are used for normal stack unwinding. That is
something that *everybody* uses, and reducing its size therefore useful to
everyone.</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>