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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - LSR asserts trying to insert instructions at a catchswitch"
href="https://llvm.org/bugs/show_bug.cgi?id=26373">26373</a>
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<th>Summary</th>
<td>LSR asserts trying to insert instructions at a catchswitch
</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>Windows NT
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
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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>andrew.kaylor@intel.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=15753" name="attach_15753" title="small reproducer">attachment 15753</a> <a href="attachment.cgi?id=15753&action=edit" title="small reproducer">[details]</a></span>
small reproducer
I've come across a case where an assertion fires in the loop strength reduction
pass because the instruction selected for an insertion point is a catchswitch
statement. In the failing test case, LSR is trying to replace a PHI node
(which happens to be in a catchswitch statement) and two of the incoming blocks
for this PHI node are catchswitch blocks. LSR does not currently attempt to
handle this case.
LSRInstance::RewriteForPHI() selects PN->getIncomingBlock(i)->getTerminator()
-- a catchswitch statement in the failing case -- as the insertion point and
calls LSRInstance::Expand() which in turn calls
LSRInstance::AdjustInsertPositionForExpand(), which is where the assertion
occurs.
assert(!isa<PHINode>(LowestIP) && !LowestIP->isEHPad()
&& !isa<DbgInfoIntrinsic>(LowestIP) &&
"Insertion point must be a normal instruction");
[at LoopStrengthReduce.cpp, line 4419 in r255921 of that file]
I used bugpoint to reduce the failing case and have attached the resulting IR
file. You should be able to reproduce the problem by running:
opt -loop-reduce lsr-catchswitch-insert.ll</pre>
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