<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 --- - Inefficient code gen for cmove"
href="https://llvm.org/bugs/show_bug.cgi?id=27577">27577</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Inefficient code gen for cmove
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</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>LLVM Codegen
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>hjl.tools@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>david.l.kreitzer@intel.com, llvm-bugs@lists.llvm.org, zia.ansari@intel.com
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>On x86-64, at -O2, for
---
extern int a, b;
int foo(int cond)
{
return cond == -1 ? a : b;
}
---
clang 3.7 and 3.9 generate
---
cmpl $-1, %edi
movl $a, %eax
movl $b, %ecx
cmoveq %rax, %rcx
movl (%rcx), %eax
retq
---
---
cmpl $-1, %edi
movl a(%rip), %eax
cmovne b(%rip), %eax
ret
---
is better.</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>