Re: gcc-4.6.0 generates no code for sub_preempt_count()

From: Mikael Pettersson
Date: Thu Apr 14 2011 - 03:49:23 EST


Richard Weinberger writes:
> Hi,
>
> I'm facing a very strange issue with gcc-4.6.0 and UML.
> Within __local_bh_enable() gcc generates no code for sub_preempt_count().
>
> See:
> http://userweb.kernel.org/~rw/uml-gcc460/__local_bh_enable-gcc460.txt
> vs.
> http://userweb.kernel.org/~rw/uml-gcc460/__local_bh_enable-gcc431.txt
>
> Interestingly it generates code for add_preempt_count().
> I can reproduce this on x86 and x86_64.
>
> The problem has to do with UML's current_thread_info() function.
> When I replace it with arch/x86's (unportable) variant gcc generates code.
>
> Any ideas whether this is a gcc or a kernel issue?

Please provide a standalone test case.
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