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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [IA] clang hangs with `-no-integrated-as -Wa,-`"
href="https://bugs.llvm.org/show_bug.cgi?id=39410">39410</a>
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<th>Summary</th>
<td>[IA] clang hangs with `-no-integrated-as -Wa,-`
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<th>Product</th>
<td>clang
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<th>Version</th>
<td>trunk
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<th>Hardware</th>
<td>PC
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<th>OS</th>
<td>Linux
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<th>Status</th>
<td>NEW
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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>libclang
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>ndesaulniers@google.com
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<th>CC</th>
<td>echristo@gmail.com, klimek@google.com, llozano@chromium.org, llvm-bugs@lists.llvm.org, natechancellor@gmail.com, srhines@google.com
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<p>
<div>
<pre>From <a href="https://lkml.org/lkml/2018/10/23/136">https://lkml.org/lkml/2018/10/23/136</a>.
The linux kernel as of 4.20 for x86_64 uses the flag `-Wa,-` with `-pipe`.
This causes the use of `no-integrated-as` to hang the build. I *think* `-pipe`
is a red herring.
ie.
$ clang hello_world.c -no-integrated-as -Wa,-
can reproduce the issue. strace'ing with and without -Wa,-, I see:
with -Wa,-:
...
access("/usr/bin/as", F_OK) = 0
...
wait4(167173,
w/o: -Wa,-:
access("/usr/bin/as", F_OK) = 0
...
wait4(167996, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0, NULL) = 167996
...
--- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=167996,
si_uid=366559, si_status=0, si_utime=0, si_stime=1} ---
so however clang is invoking the non-integrated-as, it's not receiving SIGCHLD
in order to exit the `wait4`.
Looking at
$ strace gcc hello_world.c -Wa,-</pre>
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