<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 --- - processor feature detection confused in VM"
href="http://llvm.org/bugs/show_bug.cgi?id=19720">19720</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>processor feature detection confused in VM
</td>
</tr>
<tr>
<th>Product</th>
<td>compiler-rt
</td>
</tr>
<tr>
<th>Version</th>
<td>3.2
</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>compiler-rt
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>vtjnash@gmail.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>I am running an Ubuntu VM on Ubuntu 12.04 on a mobile core2duo. The default
install detected my CPU model as most closely matching n270 (atom), but did not
enable the MOVBE instruction (since I don't have it). However, LLVM appears to
ignore the lack of MOVBE in my cpuid, and assumes that I have it because of the
atom processor declaration.
this snippet from lib/Target/X86/X86.td (from master) I believe to be at fault:
```
// Atom.
def : ProcessorModel<"atom", AtomModel,
[ProcIntelAtom, FeatureSSSE3, FeatureCMPXCHG16B,
FeatureMOVBE, FeatureSlowBTMem, FeatureLeaForSP,
```
/proc/cpuinfo file, as seen by the client:
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 28
model name : Intel(R) Atom(TM) CPU N270 @ 1.60GHz
stepping : 2
microcode : 0x1
cpu MHz : 1995.163
cache size : 4096 KB
fdiv_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 5
wp : yes
flags : fpu vme de tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat
pse36 clflush mmx fxsr sse sse2 ss nx constant_tsc pni vmx ssse3 cx16
hypervisor lahf_lm
bogomips : 3990.32
clflush size : 64
cache_alignment : 64
address sizes : 36 bits physical, 0 bits virtual
power management:
(and duplicated for processor 1)</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>