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<base href="http://llvm.org/bugs/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Incorrect CIE version 3 in object files for platforms defaulting to DWARF2"
href="http://llvm.org/bugs/show_bug.cgi?id=22046">22046</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Incorrect CIE version 3 in object files for platforms defaulting to DWARF2
</td>
</tr>
<tr>
<th>Product</th>
<td>new-bugs
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>All
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>new bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>dimitry@andric.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>As discussed on the llvm-commits list [1], for platforms which default to
emitting DWARF2, such as *BSD, Darwin and Solaris, clang can output an
incorrect CIE version field in object files, depending on whether -g is used or
not.
This behavior was introduced by r211272. A simple demonstration (as already
shown on the mailing list):
$ cat build-config-test.c
int f (void) { return 0; }
$ ~/obj/llvm-r211272/bin/clang -c build-config-test.c -o
test-r211272-without-g.o
$ ~/obj/llvm-r211272/bin/clang -c -g build-config-test.c -o
test-r211272-with-g.o
$ strip test-r211272-without-g.o
$ strip test-r211272-with-g.o
$ dwarfdump -v -F test-r211272-without-g.o
.eh_frame
fde:
< 0><0x00000020:0x0000002b><><fde offset 0x00000018 length: 0x0000001c><eh
aug data len 0x0>
0x00000020: <off cfa=08(r7) > <off r16=-8(cfa) >
0x00000021: <off cfa=16(r7) > <off r6=-16(cfa) > <off r16=-8(cfa) >
0x00000024: <off cfa=16(r6) > <off r6=-16(cfa) > <off r16=-8(cfa) >
cie:
< 0> version 3
cie section offset 0 0x00000000
augmentation zR
code_alignment_factor 1
data_alignment_factor -8
return_address_register 16
eh aug data len 0x1 bytes 0x1b
bytes of initial instructions 7
cie length 20
initial instructions
0 DW_CFA_def_cfa r7 8
3 DW_CFA_offset r16 -8 (1 * -8)
5 DW_CFA_nop
6 DW_CFA_nop
$ dwarfdump -v -F test-r211272-with-g.o
.eh_frame
fde:
< 0><0x00000020:0x0000002b><><fde offset 0x00000018 length: 0x0000001c><eh
aug data len 0x0>
0x00000020: <off cfa=08(r7) > <off r16=-8(cfa) >
0x00000021: <off cfa=16(r7) > <off r6=-16(cfa) > <off r16=-8(cfa) >
0x00000024: <off cfa=16(r6) > <off r6=-16(cfa) > <off r16=-8(cfa) >
cie:
< 0> version 1
cie section offset 0 0x00000000
augmentation zR
code_alignment_factor 1
data_alignment_factor -8
return_address_register 16
eh aug data len 0x1 bytes 0x1b
bytes of initial instructions 7
cie length 20
initial instructions
0 DW_CFA_def_cfa r7 8
3 DW_CFA_offset r16 -8 (1 * -8)
5 DW_CFA_nop
6 DW_CFA_nop
E.g., without the -g option, the CIE version is incorrectly set to 3, while
with the -g option, the CIE version is correctly set to 1.
This still reproduces on trunk r224901, as of 2014-12-28.
[1]
<a href="http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20141222/250134.html">http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20141222/250134.html</a></pre>
</div>
</p>
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