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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [ASan] -fno-common generates a comdat with asan options"
href="https://bugs.llvm.org/show_bug.cgi?id=47925">47925</a>
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<th>Summary</th>
<td>[ASan] -fno-common generates a comdat with asan options
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>All
</td>
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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>normal
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>LLVM Codegen
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>Wolfgang_Pieb@playstation.sony.com
</td>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
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<p>
<div>
<pre>The following trivial source generates a comdat for 'bar' when using ASan:
/*==================*/
char bar;
/*==================*/
clang -emit-llvm -S -fsanitize=address -fdata-sections
-fsanitize-address-globals-dead-stripping -c bar.c
bar.ll:
<snip>
@bar = dso_local global { i8, [63 x i8] } zeroinitializer, comdat, align 32
<snip>
Without either -fsanitize-address-globals-dead-stripping or -fdata-sections no
comdat is generated.
The consequence is that we don't find some ODR violations at link time with
these options.
Note that commit
<a href="https://github.com/llvm/llvm-project/commit/3d9a0445cce368b55dc3a573bc91fe902bbb977f">https://github.com/llvm/llvm-project/commit/3d9a0445cce368b55dc3a573bc91fe902bbb977f</a>
changed the default to -fno-common. Before, you would have to give -fno-common
on the command line to trigger this behaviour.</pre>
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