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<base href="https://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Incorrect sample profiles at O3"
href="https://llvm.org/bugs/show_bug.cgi?id=28991">28991</a>
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<tr>
<th>Summary</th>
<td>Incorrect sample profiles at O3
</td>
</tr>
<tr>
<th>Product</th>
<td>new-bugs
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
</tr>
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<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>new bugs
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>dcallahan@fb.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=16963" name="attach_16963" title="Tar file of script and input files">attachment 16963</a> <a href="attachment.cgi?id=16963&action=edit" title="Tar file of script and input files">[details]</a></span>
Tar file of script and input files
<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - Customize Bugzilla to have some LLVM flavah"
href="show_bug.cgi?id=2">bug2</a>.sh generates the reproduction where we compile a training program either
-00 or -03.
The -O0 training yield this sample
Function: _Z8clampSumPdidd: 105434939, 1, 14 sampled lines
Samples collected in the function's body {
0: 1
1: 1
2.1: 949899
2.2: 949797
3: 949833
4: 0
5: 949926
6: 949896
7: 0
8: 949929
9: 949904
11: 949889
12: 949809
14: 4
}
while the -O3 training yields this sample
Function: _Z8clampSumPdidd: 76108151, 2, 9 sampled lines
Samples collected in the function's body {
0: 2
2.1: 1435907
3: 1436091
6: 1436048
7: 1436032
9: 2
11: 1435984
12: 1435974
14: 2
}
Note the differences in values for relative statements 7 and 9.
The corresponding branch_weights are
!74 = !{!"branch_weights", i32 1, i32 949905}
and
!74 = !{!"branch_weights", i32 1436033, i32 3}
The -O3 sample inverts the relative weights relative to the (correct) -O0
sample.
The attached tar file has <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - Customize Bugzilla to have some LLVM flavah"
href="show_bug.cgi?id=2">bug2</a>.sh, bug.cc and main.cc and a snapshot of <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - Customize Bugzilla to have some LLVM flavah"
href="show_bug.cgi?id=2">bug2</a>.sh
output.</pre>
</div>
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