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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - functionattrs exhibits superlinear behaviour"
href="http://llvm.org/bugs/show_bug.cgi?id=16398">16398</a>
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<th>Summary</th>
<td>functionattrs exhibits superlinear behaviour
</td>
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<th>Product</th>
<td>libraries
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Interprocedural Optimizations
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>nlewycky@google.com
</td>
</tr>
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
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<th>Classification</th>
<td>Unclassified
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<p>
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<pre>This is broken out from <a class="bz_bug_link
bz_status_NEW "
title="NEW --- - stack usage per instantiation step is too high"
href="show_bug.cgi?id=13263">bug 13263</a>. On the attached .ll file, we see this:
===-------------------------------------------------------------------------===
... Pass execution timing report ...
===-------------------------------------------------------------------------===
Total Execution Time: 4.9600 seconds (4.9723 wall clock)
---User Time--- --System Time-- --User+System-- ---Wall Time--- ---
Name ---
3.8400 ( 78.0%) 0.0100 ( 25.0%) 3.8500 ( 77.6%) 3.8668 ( 77.8%)
Deduce function attributes
0.6800 ( 13.8%) 0.0000 ( 0.0%) 0.6800 ( 13.7%) 0.6421 ( 12.9%) SROA
0.1800 ( 3.7%) 0.0300 ( 75.0%) 0.2100 ( 4.2%) 0.1741 ( 3.5%)
Function Integration/Inlining
0.0000 ( 0.0%) 0.0000 ( 0.0%) 0.0000 ( 0.0%) 0.0570 ( 1.1%)
Module Verifier
[...]
The slowdown is happening inside AddNoCaptureAttrs, and the capture tracking
analysis happens to be trivial so that isn't the problem (and SCCNodes.size()
== 1 so that also isn't the problem). I'm placing my bet on inefficient
AttributeSet manipulation.</pre>
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