<html>
<head>
<base href="https://bugs.llvm.org/">
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Using a private global as a global_ctor key fails when emitting a COFF object"
href="https://bugs.llvm.org/show_bug.cgi?id=38607">38607</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Using a private global as a global_ctor key fails when emitting a COFF object
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Windows NT
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>Common Code Generator Code
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>rnk@google.com
</td>
</tr>
<tr>
<th>CC</th>
<td>david.majnemer@gmail.com, llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>Consider this LLVM IR:
@x = private global i32 0
@llvm.global_ctors = appending global [1 x { i32, void ()*, i8* }]
[{ i32, void ()*, i8* }
{ i32 65535,
void ()* @register_x,
i8* bitcast (i32* @x to i8*) }]
define internal void @register_x() {
ret void
}
We can generate asm for it, but we cannot assemble it to an object. We emit:
$ llc t.ll -o t.o -filetype=obj
LLVM ERROR: Missing associated COMDAT section for section .CRT$XCU
Mechanically, what happens is we try to look up a private label (.Lx) in the
COFF symbol table that we're making, we use GetOrCreate on it, but we don't
have a section for it, so we issue this diagnostic.
However, the input LLVM IR makes some sense. We should run the initializer if
and only if @x is included in the final link, and it's not comdat, so it will
be included, and we can just ignore it and always put @register_x in the main
.CRT$XCU section.
The question is, should we accept the assembly that we generate today?
.section .rdata,"dr"
.p2align 2 # @x
.Lx:
.long 0 # 0x0
.section .CRT$XCU,"dr",associative,.Lx
.p2align 3
.quad register_x
Does that assembly make sense, i.e. make this .CRT$XCU section associative with
the non-comdat .rdata section?</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>