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Re: [Qemu-devel] [PATCH] atomic.h: Work around gcc spurious "unused valu
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [PATCH] atomic.h: Work around gcc spurious "unused value" warning |
Date: |
Thu, 10 May 2018 07:37:44 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 |
On 05/10/2018 07:36 AM, Peter Maydell wrote:
> Some versions of gcc produce a spurious warning if the result of
> __atomic_compare_echange_n() is not used and the type involved
> is a signed 8 bit value:
> error: value computed is not used [-Werror=unused-value]
> This has been seen on at least
> gcc (Ubuntu 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
>
> Work around this by using an explicit cast to void to indicate
> that we don't care about the return value.
>
> We don't currently use our atomic_cmpxchg() macro on any signed
> 8 bit types, but the upcoming support for the Arm v8.1-Atomics
> will require it.
>
> Signed-off-by: Peter Maydell <address@hidden>
> ---
> Sending out my workaround as an actual patch. If this is OK I'll
> put in via target-arm.next as it's a dependency for the v8.1-atomics
> series.
>
> include/qemu/atomic.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
Reviewed-by: Richard Henderson <address@hidden>
r~