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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Exceptions broken with -m32 -g"
href="https://llvm.org/bugs/show_bug.cgi?id=31545">31545</a>
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<th>Summary</th>
<td>Exceptions broken with -m32 -g
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>unspecified
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>release blocker
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>-New Bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>labath@google.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>$ cat /tmp/a.cc
int foo(void) { return 0; }
int main() {
try {
throw 10;
} catch (...) {
}
return 0;
}
$ .../clang++ -g -m32 /tmp/a.cc -o a.out && ./a.out
terminate called after throwing an instance of 'int'
Aborted
=> The app crashes due to uncaught exception even though it should be caught
Things to note:
- the problem goes away if I remove "-g" from the command line
- the problem goes away if I remove "-m32" from the command line
- the problem goes away if I remove the "foo" declaration from a.cc
If I look at the intermediate .S file, I see that the thing in common for all
these three scenarios is that the ".cfi_sections .debug_frame" directive
dissapears.
My guess to what is going on is:
- we look at the first function, see that it cannot throw an exception, but we
still want to generate unwind info for the debugger, so we decide to use the
.debug_frame section.
- the second function *does* use need the unwind info, but now it's too late to
change the section, so it still ends up in .debug_frame.
- now the exception unwinder cannot find the unwind info at runtime
This bug was introduced recently, but I don't have an exact commit for it. I am
hoping that the problem will be sufficiently obvious to someone who is familiar
with the code in question.</pre>
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