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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Deficiency in 'if' compared to 'foreach' with cast in TableGen"
href="https://bugs.llvm.org/show_bug.cgi?id=50486">50486</a>
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<th>Summary</th>
<td>Deficiency in 'if' compared to 'foreach' with cast in TableGen
</td>
</tr>
<tr>
<th>Product</th>
<td>tools
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>TableGen
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>joseph.nash@amd.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
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<pre>Created <span class=""><a href="attachment.cgi?id=24894" name="attach_24894" title="reproducer and counterexamples">attachment 24894</a> <a href="attachment.cgi?id=24894&action=edit" title="reproducer and counterexamples">[details]</a></span>
reproducer and counterexamples
The Tablegen if statement introduced in <a href="https://reviews.llvm.org/D71474">https://reviews.llvm.org/D71474</a> seems
to have a deficiency compared to foreach, when using casts. The attached case
shows an example where this happens, and it is a reduced version of what
happens in the AMDGPU backend.
The error message is "attempting to loop over
'!if(!cast<with_field>("instance").val, [1], [])', expected a list" which is
the code the 'if ... then' is expanded to in llvm/lib/TableGen/TGParser.cpp.
However,I could not figure out a fix while looking at this file.
The equivalent formation the statement using foreach works.</pre>
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