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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - zeroext i1 returning functions don't get TCO"
href="http://llvm.org/bugs/show_bug.cgi?id=16742">16742</a>
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<th>Summary</th>
<td>zeroext i1 returning functions don't get TCO
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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>Linux
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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
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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>richard-llvm@metafoo.co.uk
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</tr>
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu, nlewycky@google.com
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<th>Classification</th>
<td>Unclassified
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<p>
<div>
<pre>Running this through clang:
bool g(); bool f() { return g(); }
Generates this:
define zeroext i1 @_Z1fv() #0 {
entry:
%call = tail call zeroext i1 @_Z1gv()
ret i1 %call
}
declare zeroext i1 @_Z1gv() #1
... which produces suboptimal assembly:
_Z1fv: # @_Z1fv
pushq %rax
callq _Z1gv
popq %rdx
ret
If I strip out the 'zeroext' and run through llc, I instead get this:
_Z1fv: # @_Z1fv
jmp _Z1gv # TAILCALL</pre>
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