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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - SHN_ABS symbols cause --gc-sections to crash"
href="https://bugs.llvm.org/show_bug.cgi?id=33239">33239</a>
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<th>Summary</th>
<td>SHN_ABS symbols cause --gc-sections to crash
</td>
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<th>Product</th>
<td>lld
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<th>Version</th>
<td>unspecified
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<th>Hardware</th>
<td>PC
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<th>OS</th>
<td>All
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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>ELF
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>smeenai@fb.com
</td>
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<th>CC</th>
<td>compnerd@compnerd.org, grimar@accesssoftek.com, llvm-bugs@lists.llvm.org, rafael.espindola@gmail.com, ruiu@google.com
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<p>
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<pre>% touch empty.bin
% ld.lld -m elf_x86_64 -b binary --relocatable -o empty.o empty.bin
% ld.lld -shared --gc-sections -o libempty.so empty.o
ld.lld: ../../../include/llvm/Support/Casting.h:104: static bool
llvm::isa_impl_cl<To, const From*>::doit(const From*) [with To =
lld::elf::InputSectionBase; From = lld::elf::SectionBase]: Assertion `Val &&
"isa<> used on a null pointer"' failed.
The assertion is triggered via the cast in [1]. The symbol for which it fails
is _binary_empty_bin_size, which is absolute and has a null Section.
I'm using the first ld.lld command because it was how I came across the issue;
I believe it would generalize to any SHN_ABS symbol, however. I'm not sure if
there are scenarios in which a non-absolute symbol would trigger the assertion.
[1]
<a href="https://reviews.llvm.org/diffusion/L/browse/lld/trunk/ELF/MarkLive.cpp;304274$223?color=1">https://reviews.llvm.org/diffusion/L/browse/lld/trunk/ELF/MarkLive.cpp;304274$223?color=1</a></pre>
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