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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Potential Unbounded recursion in MachineLICM::InitRegPressure"
href="https://bugs.llvm.org/show_bug.cgi?id=34447">34447</a>
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<th>Summary</th>
<td>Potential Unbounded recursion in MachineLICM::InitRegPressure
</td>
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<th>Product</th>
<td>new-bugs
</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>All
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>new bugs
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>joker.eph@gmail.com
</td>
</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
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<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=19096" name="attach_19096" title="Machine function that explodes the recursion stack">attachment 19096</a> <a href="attachment.cgi?id=19096&action=edit" title="Machine function that explodes the recursion stack">[details]</a></span>
Machine function that explodes the recursion stack
We enter the recursion here:
```
// If the preheader has only a single predecessor and it ends with a
// fallthrough or an unconditional branch, then scan its predecessor for live
// defs as well. This happens whenever the preheader is created by splitting
// the critical edge from the loop predecessor to the loop header.
if (BB->pred_size() == 1) {
MachineBasicBlock *TBB = nullptr, *FBB = nullptr;
SmallVector<MachineOperand, 4> Cond;
if (!TII->analyzeBranch(*BB, TBB, FBB, Cond, false) && Cond.empty())
InitRegPressure(*BB->pred_begin());
}
```
The attached function triggers a very deep recursion that crashes the program.
I'm not sure from the comment if it is intended that this can recurse more than
a single level. So it is possible that some preconditions are not enforced
before we reach this point.
If on the other hand the deep recursion is legit here, then we need to modify
the logic to make it iterative.</pre>
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