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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - GVN ignores inbounds of getelementptr"
href="https://llvm.org/bugs/show_bug.cgi?id=28562">28562</a>
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<th>Summary</th>
<td>GVN ignores inbounds of getelementptr
</td>
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<th>Product</th>
<td>libraries
</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>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Scalar Optimizations
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>kyoonss@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>david.majnemer@gmail.com, dberlin@dberlin.org, listmail@philipreames.com, llvm-bugs@lists.llvm.org, nunoplopes@sapo.pt, sanjoy@playingwithpointers.com
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
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<pre>GVN ignores the inbounds keyword of getelementptr instructions.
As a consequence, it may replace a GEP instruction without inbounds with
another GEP with inbounds.
Running 'opt -gvn' for the source code below produces the following result:
source:
define i32* @foo(i32* %a) {
%x1 = getelementptr inbounds i32, i32* %a, i32 10
%x2 = getelementptr i32, i32* %a, i32 10
ret i32* %x2
}
result:
define i32* @foo(i32* %a) {
%x1 = getelementptr inbounds i32, i32* %a, i32 10
ret i32* %x1
}
I think foo's behavior is changed, since the GEP with inbounds can be a poison
value.</pre>
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</p>
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