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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Reverse the ownership between DICompileUnit and DISubprogram"
href="https://llvm.org/bugs/show_bug.cgi?id=27284">27284</a>
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<th>Summary</th>
<td>Reverse the ownership between DICompileUnit and DISubprogram
</td>
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<th>Product</th>
<td>libraries
</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>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>DebugInfo
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>aprantl@apple.com
</td>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<th>Classification</th>
<td>Unclassified
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<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=16187" name="attach_16187" title="a python script that updates LLVM IR testcases to the new format">attachment 16187</a> <a href="attachment.cgi?id=16187&action=edit" title="a python script that updates LLVM IR testcases to the new format">[details]</a></span>
a python script that updates LLVM IR testcases to the new format
Currently each Function points to a DISubprogram and DISubprogram has a scope
field. For member functions the scope is a DICompositeType. DIScopes never
point to the DICompileUnit to facilitate type uniquing.
Distinct DISubprograms (with isDefinition: true) are not part of the type
hierarchy and cannot be uniqued. I'm proposing to remove the subprograms list
from DICompileUnit and instead add a pointer to the owning compile unit to
distinct DISubprograms. This would make it easy for ThinLTO to strip unneeded
DISubprograms and their transitively referenced debug info.
Motivation
----------
Materializing DISubprograms is currently the most expensive operation when
doing a ThinLTO build of clang.
We want the DISubprogram to be stored in a separate Bitcode block (or the same
block as the function body) so we can avoid having to expensively deserialize
all DISubprograms together with the global metadata. If a function has been
inlined into another subprogram we need to store a reference the block
containing the inlined subprogram.
Implementation
--------------
Attached is a python script that updates LLVM IR testcases to the new format.</pre>
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