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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - large codegen in clang for functions containing va_start"
href="https://bugs.llvm.org/show_bug.cgi?id=48195">48195</a>
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<th>Summary</th>
<td>large codegen in clang for functions containing va_start
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<th>Product</th>
<td>libraries
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<th>Version</th>
<td>11.0
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<th>Hardware</th>
<td>PC
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<th>OS</th>
<td>Windows NT
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<th>Status</th>
<td>NEW
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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>Common Code Generator Code
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>jeffr@radgametools.com
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<pre>Not sure what's happening here, but the code gen for va_start is really large
compared to GCC or MSVC on x64. It looks like it's spilling all the registers
(including the sse registers) for some reason.
Are GCC and MSVC assuming something that clang cannot? Are they doing some
optimization for intra-compliation unit?
Here's clang11:
<a href="https://godbolt.org/z/7PrKEf">https://godbolt.org/z/7PrKEf</a>
Flip to gcc and msvc and the code is what I would expect...</pre>
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