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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Possible miscompilation by clang-cl versions 7, 8, and 9 targeting 32-bit Windows"
href="https://bugs.llvm.org/show_bug.cgi?id=42567">42567</a>
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<th>Summary</th>
<td>Possible miscompilation by clang-cl versions 7, 8, and 9 targeting 32-bit Windows
</td>
</tr>
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<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Windows NT
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>-New Bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>bspencer@blackberry.com
</td>
</tr>
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<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
</td>
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<div>
<pre>Created <span class=""><a href="attachment.cgi?id=22221" name="attach_22221" title="Program demonstrating the bug">attachment 22221</a> <a href="attachment.cgi?id=22221&action=edit" title="Program demonstrating the bug">[details]</a></span>
Program demonstrating the bug
The attached program, when compiled with clang-cl versions 7, 8, and 9 (from
apt.llvm.org for Debian stretch) crashes when targeting 32-bit Windows. It
does not crash when targeting 64-bit Windows with clang-cl or when using MSVC
(15.9.12 and other versions).
The attached archive contains a (POSIX) Makefile that can build on Linux using
a selection of compilers. Building with MSVC (on Windows or on Linux) always
produces an executable that works. Building with clang-cl for 32-bit always
produces an executable that fails.
For example:
$ make
clang version 9.0.0-svn364966-1~exp1+0~20190702204433.1332~1.gbpb44072 (trunk)
LLD 9.0.0
INCLUDE="/home/bspencer/msvc2017-15.9.12/ucrt/Include/10.0.17134.0/ucrt;/home/bspencer/msvc2017-15.9.12/vc/Tools/MSVC/14.16.27023/include;/home/bspencer/msvc2017-15.9.12/ucrt/Include/10.0.17134.0/shared;/home/bspencer/msvc2017-15.9.12/ucrt/Include/10.0.17134.0/um"
clang-cl-9 -Wno-unused-private-field -EHsc -analyze- -O2 -MD -W4 -WX -m32
-Wno-unused-private-field -c -Foprog.obj prog.cc
INCLUDE="/home/bspencer/msvc2017-15.9.12/ucrt/Include/10.0.17134.0/ucrt;/home/bspencer/msvc2017-15.9.12/vc/Tools/MSVC/14.16.27023/include;/home/bspencer/msvc2017-15.9.12/ucrt/Include/10.0.17134.0/shared;/home/bspencer/msvc2017-15.9.12/ucrt/Include/10.0.17134.0/um"
clang-cl-9 -Wno-unused-private-field -EHsc -analyze- -O2 -MD -W4 -WX -m32
-Wno-unused-private-field -c -Folib.obj lib.cc
LIB="/home/bspencer/msvc2017-15.9.12/ucrt/Lib/10.0.17134.0/ucrt/x86;/home/bspencer/msvc2017-15.9.12/vc/Tools/MSVC/14.16.27023/lib/x86;/home/bspencer/msvc2017-15.9.12/ucrt/Lib/10.0.17134.0/um/x86"
lld-link-9 /OUT:prog.exe prog.obj lib.obj
It fails both under Wine and real Windows:
$ wine ./prog.exe
Try!
Catch!
wine: Unhandled page fault on execute access to 0x2f409fde at address
0x2f409fde (thread 0023), starting debugger...
C:> prog.exe
Try!
Catch!
(Windows crash dialog box)
The crash happens in an std::thread function accessing an exception thrown and
caught within that thread. Minimizing the test case further in any way that I
tried avoided the bug.</pre>
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