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<base href="https://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - After r249655, -save-temps causes -cc1as mode to crash"
href="https://llvm.org/bugs/show_bug.cgi?id=26999">26999</a>
</td>
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<tr>
<th>Summary</th>
<td>After r249655, -save-temps causes -cc1as mode to crash
</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>
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<th>OS</th>
<td>All
</td>
</tr>
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<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>llvm-bugs@lists.llvm.org
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>In r249655, there was an overhaul of the -g flag handling in the driver. This
seems to have caused a problem when you use -g in combination with -save-temps:
$ echo "int main(void) { return 0; }" > test.c
$ clang -g -save-temps -c test.c
Unknown version
UNREACHABLE executed at /share/dim/src/llvm/trunk/lib/MC/MCDwarf.cpp:1257!
clang-3.9: error: unable to execute command: Abort trap (core dumped)
clang-3.9: error: clang integrated assembler command failed due to signal (use
-v to see invocation)
clang version 3.9.0 (trunk 263389)
Target: i386-unknown-freebsd11.0
Thread model: posix
InstalledDir: /share/dim/llvm/263389-trunk-freebsd11-i386-ninja-rel-1/bin
Running the same command with -v shows that the cc1as stage is run as follows:
clag -cc1as -triple i386-unknown-freebsd11.0 -filetype obj -main-file-name
test.c -target-cpu i486 -mrelocation-model static -mrelax-all -o test.o test.s
Because no -g option is passed, cc1as_main.cpp sets the DwarfVersion to 0, and
this causes an assertion failure in MCDwarf.cpp's getCIEVersion() function:
1245 static unsigned getCIEVersion(bool IsEH, unsigned DwarfVersion) {
1246 if (IsEH)
1247 return 1;
1248 switch (DwarfVersion) {
1249 case 2:
1250 return 1;
1251 case 3:
1252 return 3;
1253 case 4:
1254 case 5:
1255 return 4;
1256 }
1257 llvm_unreachable("Unknown version");
1258 }
This function was called by FrameEmitterImpl::EmitCIE(), because the .s file
generated by the previous .c -> .s stage contains debugging directives.
Either the -cc1as stage should get a -dwarfversion flag passed by the previous
stage, or it should not set the DwarfVersion to 0 by default. (But if not
zero, then the DwarfVersion is really dependent on the platform and target...)</pre>
</div>
</p>
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