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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - lld-link silently accepts AMD64_REL32 against absolute symbol"
href="https://bugs.llvm.org/show_bug.cgi?id=37599">37599</a>
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<th>Summary</th>
<td>lld-link silently accepts AMD64_REL32 against absolute symbol
</td>
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<th>Product</th>
<td>lld
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>COFF
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>smeenai@fb.com
</td>
</tr>
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<th>CC</th>
<td>compnerd@compnerd.org, llvm-bugs@lists.llvm.org, rnk@google.com, ruiu@google.com
</td>
</tr></table>
<p>
<div>
<pre>% cat reduced.s
.weak weak
.globl main
main:
leaq weak(%rip), %rax
retq
% llvm-mc -triple x86_64-windows-msvc -filetype=obj -o reduced.o reduced.s
% lld-link -entry:main reduced.o
Weak symbols are implemented for COFF on LLVM by using COFF weak externals and
creating an absolute symbol with the value 0 as the fallback symbol. Since we
don't define weak in this case, we'll end up falling back to the absolute
symbol. lld will then silently accept the AMD64_ADDR32 relocation against the
absolute symbol, which will produce the wrong result at runtime, whereas link
produces an error:
error LNK2016: absolute symbol 'foo' used as target of REL32 relocation in
section 1
(I used the weak external mechanism to demonstrate the issue because if I just
create an absolute symbol directly and try to create RIP-relative relocation
against that, clang won't actually emit the relocation in the object file.)</pre>
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</p>
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