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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Clang generates calls to __mulodi4() for ARM even when not using compiler-rt"
href="https://llvm.org/bugs/show_bug.cgi?id=28629">28629</a>
</td>
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<th>Summary</th>
<td>Clang generates calls to __mulodi4() for ARM even when not using compiler-rt
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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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>normal
</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>
<tr>
<th>Reporter</th>
<td>srhines@google.com
</td>
</tr>
<tr>
<th>CC</th>
<td>arnaud.degrandmaison@arm.com, llvm-bugs@lists.llvm.org, pirama@google.com, renato.golin@linaro.org, silviu.baranga@arm.com
</td>
</tr>
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<th>Blocks</th>
<td>21420
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>The instructions use NDK version r11c, but the latest version r12/r13beta also
reproduce this issue.
STEPS TO REPRODUCE:
1. make standalone toolchain using the following command
./build/tools/make-standalone-toolchain.sh \
--use-llvm \
--arch=arm64 \
--platform=android-24 \
--install_dir=$TOOLCHAIN_DIR
2. compile the Skia test executables using the instructions found at
<a href="https://skia.org/user/quick/android">https://skia.org/user/quick/android</a>
3. push the executable to the device and run.
EXPECTED RESULTS:
executable runs to completion
OBSERVED RESULTS:
crashes on launch with the following error message
dlopen failed: cannot locate symbol "__mulodi4" referenced by
“libskia_android.so"
ADDITIONAL INFORMATION:
In step 2, if we use the gcc binaries included with the toolchain then the
executable runs with no issues. We have a quick hack at
<a href="https://codereview.chromium.org/2011073002/">https://codereview.chromium.org/2011073002/</a> that attempts to work around the
issue but is not desireable.
<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED WORKSFORME - multiplying long long with fsanitize=integer fails with undefined reference to __mulodi4"
href="show_bug.cgi?id=17693">https://llvm.org/bugs/show_bug.cgi?id=17693</a> seems similar, but this is not for
sanitizer code, so we should be able to use a different rtlib than compiler-rt.
Is it expected for clang to lower sequences of __builtin_smull_overflow
(<a href="https://android.googlesource.com/platform/external/dng_sdk.git/+/master/source/dng_safe_arithmetic.h#112">https://android.googlesource.com/platform/external/dng_sdk.git/+/master/source/dng_safe_arithmetic.h#112</a>)
to __mulodi4 in all cases? It is known that libgcc won't provide this symbol,
so at the very least, clang should warn/error that the rtlib selected won't be
able to resolve this symbol at runtime.</pre>
</div>
</p>
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