<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 --- - RegisterScavenger ignores kill flags on predicated instructions"
href="https://llvm.org/bugs/show_bug.cgi?id=23119">23119</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>RegisterScavenger ignores kill flags on predicated instructions
</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>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>Common Code Generator Code
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>tobias@codeaurora.org
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>The RegisterScavenger explicitly ignores <kill> flags on operands of predicated
instructions and therefore assumes that such registers remain live. When it
then scavenges such a register, it inserts a spill of this (killed) register.
This is invalid code and gets flagged up by the verifier.
RegisterScavenging.cpp includes a comment that explains why it ignores flags on
predicated instructions:
// FIXME: The scavenger is not predication aware. If the instruction is
// predicated, conservatively assume "kill" markers do not actually kill the
// register. Similarly ignores "dead" markers.
Is this still needed for any target?
Just removing the special handling of predicated instructions would seem an
easy way to fix this.</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>