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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 --- - BasicAliasAnalysis/getModRefInfo excessive compile time for this short example"
href="https://llvm.org/bugs/show_bug.cgi?id=24598">24598</a>
</td>
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<th>Summary</th>
<td>BasicAliasAnalysis/getModRefInfo excessive compile time for this short example
</td>
</tr>
<tr>
<th>Product</th>
<td>new-bugs
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>All
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
</tr>
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<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>yaron.keren@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>chandlerc@gmail.com, echristo@gmail.com, igor@azulsystems.com, llvm-bugs@lists.llvm.org, tzafrir11@gmail.com
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>sh-4.3$ cat < AliasSet.cpp
void foo(char *, char *);
void bar(int Size, bool flag) {
for (int i = 0; i < Size; ++i) {
char text[1];
char buff[1];
if (flag)
foo(text, buff);
}
}
sh-4.3$ ./runme.sh
++ clang++ -O2 -march=x86-64 -c AliasSet.cpp
real 0m0.072s
user 0m0.000s
sys 0m0.016s
++ clang++ -O3 -march=x86-64 -c AliasSet.cpp
real 0m1.135s
user 0m0.000s
sys 0m0.015s
++ clang++ -O2 -march=sandybridge -c AliasSet.cpp
real 0m0.068s
user 0m0.000s
sys 0m0.015s
++ clang++ -O3 -march=sandybridge -c AliasSet.cpp
real 0m17.028s
user 0m0.015s
sys 0m0.000s
As of current SVN, r246146. Profiling shows all time is spent around alias
analysis, slow at O3 and very slow at O3 for sandybridge architecture.
Reproduced on Linux and Windows.</pre>
</div>
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