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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - 'Undefined behavior: Call with "tail" keyword references alloca' after memcpyopt"
href="https://bugs.llvm.org/show_bug.cgi?id=35241">35241</a>
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<th>Summary</th>
<td>'Undefined behavior: Call with "tail" keyword references alloca' after memcpyopt
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<th>Product</th>
<td>new-bugs
</td>
</tr>
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<th>Version</th>
<td>unspecified
</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>enhancement
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>new bugs
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>mikael.holmen@ericsson.com
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</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<div>
<pre>Created <span class=""><a href="attachment.cgi?id=19382" name="attach_19382" title="reproducer">attachment 19382</a> <a href="attachment.cgi?id=19382&action=edit" title="reproducer">[details]</a></span>
reproducer
opt -memcpyopt -lint -S -o tr14894.opt.ll tr14894.ll
makes lint complain with
Undefined behavior: Call with "tail" keyword references alloca
tail call void @f1(%s* byval align 1 %c)
memcpyopt has turned
%tmp1 = bitcast %s* %c to i8*
%tmp2 = bitcast i8* bitcast (%s* @b to i8*) to i8*
call void @llvm.memcpy.p0i8.p0i8.i32(i8* %tmp2, i8* %tmp1, i32 3, i32 1, i1
false)
tail call void @f1(%s* byval align 1 @b)
into
%tmp1 = bitcast %s* %c to i8*
%tmp2 = bitcast i8* getelementptr inbounds (%s, %s* @b, i32 0, i32 0) to i8*
call void @llvm.memcpy.p0i8.p0i8.i32(i8* %tmp2, i8* %tmp1, i32 3, i32 1, i1
false)
tail call void @f1(%s* byval align 1 %c)
Should memcpyopt avoid th transformation for tail calls perhaps?
(Or is the lint warning in fact wrong for byval arguments?)</pre>
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