<html>
<head>
<base href="https://llvm.org/bugs/" />
</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 --- - LiveRange not updated correctly in RegisterCoalescer"
href="https://llvm.org/bugs/show_bug.cgi?id=27331">27331</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>LiveRange not updated correctly in RegisterCoalescer
</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>Register Allocator
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>tstellar@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=16213" name="attach_16213" title="Failing test case">attachment 16213</a> <a href="attachment.cgi?id=16213&action=edit" title="Failing test case">[details]</a></span>
Failing test case
Compiling the attached test case results in a verifier error. Command ot
reproduce:
llc -mtriple=amdgcn--amdhsa -mcpu=fiji coalescer-bug.ll -verify-machineinstrs
-o -
qcolombet helped be debug this on IRC, and it appears the problem is that the
live range information is not updated correctly during this transformation:
**BEFORE**
%vreg23 = 0
%vreg24:sub0 = %vreg23
%vreg24:sub1 = 2146435072
USE %vreg24
%vreg80:sub0 = %vreg23
%vreg80:sub1 = 1076494336
USE %vreg80
**AFTER**
%vreg80:sub0 = 0
%vreg80:sub1 = 2146435072
USE %vreg80
%vreg80:sub1 = 1076494336
USE %vreg80</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>