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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Flag unbalanced .cfi_adjust_cfa_offset directives at .cfi_endproc as error"
href="https://llvm.org/bugs/show_bug.cgi?id=26098">26098</a>
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<th>Summary</th>
<td>Flag unbalanced .cfi_adjust_cfa_offset directives at .cfi_endproc as error
</td>
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<th>Product</th>
<td>tools
</td>
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<th>Version</th>
<td>3.5
</td>
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<th>Hardware</th>
<td>Macintosh
</td>
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<th>OS</th>
<td>MacOS X
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>gccas
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>bart.jacobs@cs.kuleuven.be
</td>
</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
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<div>
<pre>Created <span class=""><a href="attachment.cgi?id=15597" name="attach_15597" title="Small repro">attachment 15597</a> <a href="attachment.cgi?id=15597&action=edit" title="Small repro">[details]</a></span>
Small repro
First: I'm not sure whether I am using gccas or llvm-as. The command I use is
'clang -arch x86_64 -c -v myobj.s'.
This is about .cfi_xxx directives for emitting DWARF CFI (call frame
information) that enables debuggers to generate stack backtraces and
programming language runtimes (specifically C++ and Objective-C) to walk and
unwind the stack.
The assembler currently accepts input where the net CFA offset adjustment at a
.cfi_endproc is nonzero. See small example attached. Its current behavior in
that case is that the adjustment is applied to the next assembly routine
(.cfi_startproc directive) as well. You can see by running 'dwarfdump
--eh-frame myobj.o'. I believe this input is usually/always erroneous and
furthermore the behavior is undesirable.
I would suggest to at least offer an option to have this flagged as an error.
Also, that behavior should probably be the default.
(Context: the OCaml native code compiler currently generates such unbalanced
directives. See <a href="http://caml.inria.fr/mantis/view.php?id=7120">http://caml.inria.fr/mantis/view.php?id=7120</a> and
<a href="http://caml.inria.fr/mantis/view.php?id=7118">http://caml.inria.fr/mantis/view.php?id=7118</a> and
<a href="https://github.com/ocaml/ocaml/pull/408">https://github.com/ocaml/ocaml/pull/408</a> . In this case, it is definitely an
error. It caused my application to crash randomly. Especially during demos ;-)
)</pre>
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