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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Miscompile with opt -correlated-propagation"
href="https://bugs.llvm.org/show_bug.cgi?id=50399">50399</a>
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<th>Summary</th>
<td>Miscompile with opt -correlated-propagation
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
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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>
</tr>
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<th>Severity</th>
<td>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Scalar Optimizations
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>mikael.holmen@ericsson.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
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<pre>Created <span class=""><a href="attachment.cgi?id=24873" name="attach_24873" title="bbi-56214_2.ll reproducer">attachment 24873</a> <a href="attachment.cgi?id=24873&action=edit" title="bbi-56214_2.ll reproducer">[details]</a></span>
bbi-56214_2.ll reproducer
Reproduce with
opt -correlated-propagation -S -o - bbi-56214_2.ll
The store in %cond.end32 is changed from
store i64 %i10, i64* %arrayidx12, align 1 ; store 0
to
store i64 %sub18, i64* %arrayidx12, align 1
which I think is wrong.
In the last iteration of the loop the value 0 chould be written but now we
instead write %sub18 which actually is a poison value!
I've done some annotations in the input ll-file about the value of different
temporaries which I think shows that the change done by the pass is wrong.
I suspect that the fact that %sub18 is poison isn't handled correctly.
This starts happening with commit a917fb89dc28:
[LVI] Simplify and generalize handling of clamp patterns
Instead of handling a number of special cases for selects, handle
this generally when inferring ranges from conditions. We already
infer ranges from `x + C pred C2` to `x`, so doing the same for
`x pred C2` to `x + C` is straightforward.</pre>
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