<html>
<head>
<base href="https://llvm.org/bugs/" />
</head>
<body><span class="vcard"><a class="email" href="mailto:john.brawn.123@gmail.com" title="John Brawn <john.brawn.123@gmail.com>"> <span class="fn">John Brawn</span></a>
</span> changed
<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - ARM THUMB: cpy instruction mustn't be emitted by default"
href="https://llvm.org/bugs/show_bug.cgi?id=1388">bug 1388</a>
<br>
<table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>What</th>
<th>Removed</th>
<th>Added</th>
</tr>
<tr>
<td style="text-align:right;">Status</td>
<td>NEW
</td>
<td>RESOLVED
</td>
</tr>
<tr>
<td style="text-align:right;">CC</td>
<td>
</td>
<td>john.brawn.123@gmail.com
</td>
</tr>
<tr>
<td style="text-align:right;">Resolution</td>
<td>---
</td>
<td>FIXED
</td>
</tr></table>
<p>
<div>
<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - ARM THUMB: cpy instruction mustn't be emitted by default"
href="https://llvm.org/bugs/show_bug.cgi?id=1388#c7">Comment # 7</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - ARM THUMB: cpy instruction mustn't be emitted by default"
href="https://llvm.org/bugs/show_bug.cgi?id=1388">bug 1388</a>
from <span class="vcard"><a class="email" href="mailto:john.brawn.123@gmail.com" title="John Brawn <john.brawn.123@gmail.com>"> <span class="fn">John Brawn</span></a>
</span></b>
<pre>This was fixed by r216138:
Author: Jonathan Roelofs <<a href="mailto:jonathan@codesourcery.com">jonathan@codesourcery.com</a>>
Date: Wed Aug 20 23:38:50 2014 +0000
Lower thumbv4t & thumbv5 lo->lo copies through a push-pop sequence
On pre-v6 hardware, 'MOV lo, lo' gives undefined results, so such copies
need to
be avoided. This patch trades simplicity for implementation time at the
expense
of performance... As they say: correctness first, then performance.
See <a href="http://lists.cs.uiuc.edu/pipermail/llvmdev/2014-August/075998.html">http://lists.cs.uiuc.edu/pipermail/llvmdev/2014-August/075998.html</a> for
a few
ideas on how to make this better.
AsmParser also doesn't permit MOV lo, lo (or CPY, as it used to be known), so
you can't use it in embedded asm, but MC does permit it, so using clang to
assemble a .s file with --target=thumbv4t-none-eabi gives no error but should.
That's less of a problem though.</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>