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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [InstCombine] Taking an order of magnitude longer in 12.0.0 than in 10.0.0 for some examples."
href="https://bugs.llvm.org/show_bug.cgi?id=50155">50155</a>
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<th>Summary</th>
<td>[InstCombine] Taking an order of magnitude longer in 12.0.0 than in 10.0.0 for some examples.
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<th>Product</th>
<td>new-bugs
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<th>Version</th>
<td>unspecified
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<th>Hardware</th>
<td>PC
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<th>OS</th>
<td>Linux
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>new bugs
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>christine.andress@metrics.ca
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<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org
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<pre>Created <span class=""><a href="attachment.cgi?id=24809" name="attach_24809" title="gzipped ir module exhibiting much slower InstCombine optimization pass.">attachment 24809</a> <a href="attachment.cgi?id=24809&action=edit" title="gzipped ir module exhibiting much slower InstCombine optimization pass.">[details]</a></span>
gzipped ir module exhibiting much slower InstCombine optimization pass.
For some functions, the --instcombine optimization takes excessively longer
with llvm 12.0.0 than it does with llvm 10.0.0.
In the attached example, a run of "opt -o=out.o --instcombine test_instcomb.ir"
takes 53 seconds, where it used to take around 2 seconds when version 10.0.0
was used (albeit version 12.0.0 combines more instructions).
Is there a way to mitigate this speed performance degradation when using the
library interface (i.e. from C++ library API, not from the opt tool)?</pre>
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