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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [LLVM 11 regression] Linker check, new in LLVM 11, rejects common GCC code"
href="https://bugs.llvm.org/show_bug.cgi?id=48201">48201</a>
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<th>Summary</th>
<td>[LLVM 11 regression] Linker check, new in LLVM 11, rejects common GCC code
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>11.0
</td>
</tr>
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<th>Hardware</th>
<td>All
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Keywords</th>
<td>compile-fail, regression
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Linker
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>burnus@net-b.de
</td>
</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>LLVM's linker added a reasonable check in <a href="https://reviews.llvm.org/D73999">https://reviews.llvm.org/D73999</a>
Such as (from the testsuite):
.section .foo,"aM",@progbits,1
.section .foo,"aM",@progbits,4
error: changed section entsize for .foo, expected: 1
However, it also now causes an error for:
.section .rodata.cst8,"aM",@progbits,8
.section .rodata.cst8
The problem is that GCC generates this by default (gcc/varasm.c):
/* If we have already declared this section, we can use an
abbreviated form to switch back to it -- unless this section is
part of a COMDAT groups, in which case GAS requires the full
declaration every time. */
if (!(HAVE_COMDAT_GROUP && (flags & SECTION_LINKONCE))
&& (flags & SECTION_DECLARED))
{
fprintf (asm_out_file, "\t.section\t%s\n", name);
return;
}
LLVM and GNU as ("gas") tried to align, cf. discussion
<a href="https://sourceware.org/legacy-ml/binutils/2020-02/msg00091.html">https://sourceware.org/legacy-ml/binutils/2020-02/msg00091.html</a>
and the GAS patch to turn a warning to an error:
<a href="https://sourceware.org/legacy-ml/binutils/2020-02/msg00129.html">https://sourceware.org/legacy-ml/binutils/2020-02/msg00129.html</a>
However, while llvm/lib/MC/MCParser/ELFAsmParser.cpp always issues an error:
+ if (Section->getType() != Type)
+ Error(loc, "changed section type for " + SectionName + ", expected: 0x" +
+ utohexstr(Section->getType()));
etc.
The GNU assembler only does so if flags have been specified,
gas/config/obj-elf.c:
if (attr != 0)
{
/* If section attributes are specified the second time we see a
particular section, then check that they are the same as we
saw the first time. */
if (((old_sec->flags ^ flags)
...</pre>
</div>
</p>
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