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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_CONFIRMED "
title="CONFIRMED - [WebAssembly] DW_TAG_call_site is not supported for indirect calls"
href="https://bugs.llvm.org/show_bug.cgi?id=50513">50513</a>
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<th>Summary</th>
<td>[WebAssembly] DW_TAG_call_site is not supported for indirect calls
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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>All
</td>
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<th>OS</th>
<td>All
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<th>Status</th>
<td>CONFIRMED
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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>Backend: WebAssembly
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>aheejin@gmail.com
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<th>CC</th>
<td>aardappel@gmail.com, dschuff@google.com, llvm-bugs@lists.llvm.org, ydelendik@mozilla.com
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<pre>DWARF Call site information (DW_TAG_call_site) is generated in DwarfDebug::
constructCallSiteEntryDIEs
(<a href="https://github.com/llvm/llvm-project/blob/0d5219feb9b26f299823b43c3c478e98cb3a0915/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp#L879-L1018">https://github.com/llvm/llvm-project/blob/0d5219feb9b26f299823b43c3c478e98cb3a0915/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp#L879-L1018</a>)
method, which supports two kinds of callee locations: global values for direct
calls and machine registers for indirect calls.
(<a href="https://github.com/llvm/llvm-project/blob/0d5219feb9b26f299823b43c3c478e98cb3a0915/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp#L938-L944">https://github.com/llvm/llvm-project/blob/0d5219feb9b26f299823b43c3c478e98cb3a0915/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp#L938-L944</a>)
It looks Chrome devtools do not use DW_TAG_call_site at the moment, so the lack
of support does not cause missing debug info there, but this bug is to make a
record that this is missing for the full DWARF support.
Direct calls are fine, but because wasm does not use machine registers, it
cannot record DW_TAG_call_site info for indirect calls. Wasm uses virtual
registers and they are stackified, and the info for stackified registers are
generated in WebAssemblyDebugFixup pass. I think we can add support for
DW_TAG_call_site in the DebugFixup pass too, if it becomes necessary.</pre>
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