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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [X86] Regcall calling convention mismanaged X87 fp stack if long double is an input argument but is never used"
href="https://bugs.llvm.org/show_bug.cgi?id=44445">44445</a>
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<th>Summary</th>
<td>[X86] Regcall calling convention mismanaged X87 fp stack if long double is an input argument but is never used
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<th>Product</th>
<td>libraries
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<th>Version</th>
<td>trunk
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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
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>Backend: X86
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>craig.topper@gmail.com
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<th>CC</th>
<td>craig.topper@gmail.com, llvm-bugs@lists.llvm.org, llvm-dev@redking.me.uk, spatel+llvm@rotateright.com
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<pre>The regcall calling convention allows long double to be passed into a function
in ST0. The called function is responsible for removing this data from the x87
stack when it is done with it.
This works if the argument is used in the function since it appears in the
function livein list so the FP stackifier will see it and remove it when its
done with it.
But if the argument is never used, then its not in the livein list so the FP
stackifier doesn't see it and doesn't remove it.</pre>
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