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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - ARM: extraneous unwinder reference with -fprofile-arcs"
href="https://bugs.llvm.org/show_bug.cgi?id=43234">43234</a>
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<th>Summary</th>
<td>ARM: extraneous unwinder reference with -fprofile-arcs
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>8.0
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>-New Bugs
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>arnd@linaro.org
</td>
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<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
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<p>
<div>
<pre>I got a link error on a 32-bit ARM kernel build with CONFIG_GCOV_KERNEL and
CONFIG_UNWIND_FRAME_POINTER set:
kernel/trace/trace_clock.o:(.ARM.exidx+0x0): undefined reference to
`__aeabi_unwind_cpp_pr0'
kernel/trace/trace_clock.o:(.ARM.exidx+0x8): undefined reference to
`__aeabi_unwind_cpp_pr0'
kernel/trace/trace_clock.o:(.ARM.exidx+0x10): undefined reference to
`__aeabi_unwind_cpp_pr0'
I created a reduced test case at <a href="https://godbolt.org/z/gBQtAP">https://godbolt.org/z/gBQtAP</a>
Basically, clang inserts
__llvm_gcov_writeout/__llvm_gcov_flush/__llvm_gcov_init functions into any file
it compiles, even for an empty C file input. These functions contain
.fnstart/.fnend statements even when building with "-fno-omit-frame-pointer
-fno-unwind-tables", which then results in unresolved references to
__aeabi_unwind_cpp_pr0.</pre>
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