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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - LTO and Fortran COMMON blocks"
href="https://bugs.llvm.org/show_bug.cgi?id=41472">41472</a>
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<th>Summary</th>
<td>LTO and Fortran COMMON blocks
</td>
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<th>Product</th>
<td>tools
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Windows NT
</td>
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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>lto
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>eric.schweitz@pgroup.com
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
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<p>
<div>
<pre>This bug relates to <a href="https://reviews.llvm.org/D54327#1452828">https://reviews.llvm.org/D54327#1452828</a>
I'll just quote Paul's explanation here.
"Regarding your LTO-like experiments, that result is more or less what I
thought would happen. In a normal compilation, each CU gets its own description
of the types, and the fact that they are different in different CUs doesn't
matter. Within each CU's context, the common-block description is complete and
will be used correctly by the debugger.
"In LTO, however, the IR linker wants to de-duplicate debug information, to
avoid multiple copies of the same type in the final object file. I suspect that
de-duplication (which IIRC is founded on the C++ "one definition rule")
probably should not apply to Fortran, or at least not to common blocks."
Indeed, it is quite true that in Fortran a single COMMON block can be mapped to
different sets of variable names in different scopes.</pre>
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