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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - builtin longjmp miscompiled when jmpbuf is rbp-relative address"
href="https://bugs.llvm.org/show_bug.cgi?id=48533">48533</a>
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<th>Summary</th>
<td>builtin longjmp miscompiled when jmpbuf is rbp-relative address
</td>
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<th>Product</th>
<td>new-bugs
</td>
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<th>Version</th>
<td>10.0
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>FreeBSD
</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
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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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<th>Reporter</th>
<td>jfc@mit.edu
</td>
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<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org
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<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=24293" name="attach_24293" title="bitcode that llc miscompiles">attachment 24293</a> <a href="attachment.cgi?id=24293&action=edit" title="bitcode that llc miscompiles">[details]</a></span>
bitcode that llc miscompiles
If the address argument to __builtin_longjmp is %rbp-relative the longjmp is
miscompiled. If I compile the attached .ll file with the 10.0 llc the function
ends
movq -48(%rbp), %rbp
movq -40(%rbp), %rax # This load needs the original rbp
movq -32(%rbp), %rsp # This load needs the original rbp
jmpq *%rax
Note that the first instruction overwrites %rbp but the next two instructions
depend on the old value. The branch goes to a random address with a random
%rsp.
The same bug is present in the version of llvm 11 included with FreeBSD-CURRENT
(13.0).</pre>
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