<html>
<head>
<base href="http://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 --- - PPC: 64-bit signed integer division by power of 2 isn't optimized into sradi + addze"
href="http://llvm.org/bugs/show_bug.cgi?id=20732">20732</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>PPC: 64-bit signed integer division by power of 2 isn't optimized into sradi + addze
</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>Backend: PowerPC
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>spatel+llvm@rotateright.com
</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>Using llc built from r216267:
$ cat div.ll
define i64 @foo(i64 %n) {
%div = sdiv i64 %n, 8
ret i64 %div
}
$ ./llc -mtriple=powerpc64 div.ll -o -
...
li 4, 8
divd 3, 3, 4
blr
-------------------------------------------------------
I think this can be optimized to:
sradi 3, 3, 3
addze 3, 3
blr
The fix for this bug should model what AArch64TargetLowering::BuildSDIVPow2()
does. PPC should not use "setPow2SDivIsCheap()" to execute the current code in
PPCDAGToDAGISel::Select(). There's a "FIXME" in the code comments about 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>