<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 - LLD .map files: Request more info for "<internal>:(.rodata)""
href="https://bugs.llvm.org/show_bug.cgi?id=35248">35248</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>LLD .map files: Request more info for "<internal>:(.rodata)"
</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>Linux
</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>ELF
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>huangs@google.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=19387" name="attach_19387" title="Sample .map outputs and script + sources to generate them.">attachment 19387</a> <a href="attachment.cgi?id=19387&action=edit" title="Sample .map outputs and script + sources to generate them.">[details]</a></span>
Sample .map outputs and script + sources to generate them.
LLD's generated .map file provides no semantic information on merged data in
.rodata section. In particular, merged strings are not distinguished from
other data; everything is labelled as "<internal>:(.rodata)".
The missing information is useful for tools that parse .map file to annotate
executable bytes to source. An example is Chrome's Supersize too (that I'm
working on):
<a href="https://github.com/webrtc-uwp/chromium-tools/blob/master/binary_size/README.md">https://github.com/webrtc-uwp/chromium-tools/blob/master/binary_size/README.md</a>
Comparison with other linkers:
LD .map files annotates .rodata section names from the original .o files,
.rodata.cst4 0x0000000000400ad0 0x4
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crt1.o
0x0000000000400ad0 _IO_stdin_used
*fill* 0x0000000000400ad4 0x4
.rodata.cst8 0x0000000000400ad8 0x8 a.o
.rodata.str1.1
0x0000000000400ae0 0x3e a.o
0x44 (size before relaxing)
GOLD .map files provides less info, but identifies the type ("** merge
constants" vs. "** mege strings"), e.g.:
.rodata 0x0000000000400af0 0x60
** merge constants
0x0000000000400af0 0x4
** merge constants
0x0000000000400af8 0x8
** merge strings
0x0000000000400b00 0x44
Meanwhile, LLD .map files only has "<internal>:(.rodata)", e.g.:
00000000002002e8 0000000000000060 8 .rodata
00000000002002e8 0000000000000004 4 <internal>:(.rodata)
00000000002002f0 0000000000000008 8 <internal>:(.rodata)
00000000002002f8 0000000000000044 1 <internal>:(.rodata)
0000000000200340 0000000000000008 8 b.o:(.rodata)
0000000000200340 0000000000000008 0 b
The attached .zip file contains examples to generate the above ('genall'
generates the .map files, and need to be tweaked to get proper paths).</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>