From: Richard Henderson <richard.henderson@linaro.org>
To: Thomas Huth <thuth@redhat.com>,
Chen Qun <kuhn.chenqun@huawei.com>,
qemu-devel@nongnu.org, qemu-trivial@nongnu.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Riku Voipio <riku.voipio@iki.fi>,
zhang.zhanghailiang@huawei.com, ganqixin@huawei.com,
Euler Robot <euler.robot@huawei.com>
Subject: Re: [PATCH 3/9] accel/tcg/user-exec: silence the compiler warnings
Date: Wed, 28 Oct 2020 08:37:57 -0700 [thread overview]
Message-ID: <d84d1e42-5814-05fb-4bfa-878cdca0754b@linaro.org> (raw)
In-Reply-To: <e2a3548e-d36c-3338-f298-150cce3c3d47@redhat.com>
On 10/28/20 6:52 AM, Thomas Huth wrote:
> On 28/10/2020 05.18, Chen Qun wrote:
>> When using -Wimplicit-fallthrough in our CFLAGS, the compiler showed warning:
>> ../accel/tcg/user-exec.c: In function ‘handle_cpu_signal’:
>> ../accel/tcg/user-exec.c:169:13: warning: this statement may fall through [-Wimplicit-fallthrough=]
>> 169 | cpu_exit_tb_from_sighandler(cpu, old_set);
>> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> ../accel/tcg/user-exec.c:172:9: note: here
>> 172 | default:
>>
>> This exception branch fall through the 'default' branch and run the 'g_assert_not_reached' statement.
>> So we could use "fall through" instead of "NORETURN" here.
>>
>> Reported-by: Euler Robot <euler.robot@huawei.com>
>> Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
>> ---
>> Cc: Riku Voipio <riku.voipio@iki.fi>
>> Cc: Richard Henderson <richard.henderson@linaro.org>
>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>> ---
>> accel/tcg/user-exec.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c
>> index 4ebe25461a..330468e990 100644
>> --- a/accel/tcg/user-exec.c
>> +++ b/accel/tcg/user-exec.c
>> @@ -167,7 +167,7 @@ static inline int handle_cpu_signal(uintptr_t pc, siginfo_t *info,
>> */
>> clear_helper_retaddr();
>> cpu_exit_tb_from_sighandler(cpu, old_set);
>> - /* NORETURN */
>> + /* fall through */
>
> There should not be a fall through here since the previous function should
> never return. Does the warning go away if you mark the
> cpu_exit_tb_from_sighandler() function with QEMU_NORETURN ? If so, I think
> that would be the better fix.
The compiler should have figured that out itself, due to cpu_loop_exit_noexc
being marked QEMU_NORETURN. However,
if adding a second QEMU_NORETURN works, I'm fine with that.
As a very last resort, we can change the comment to
/* no return, but fall through to assert not reached */
which correctly documents both the function preceding and also contains the
regexp that the compiler is using for the warning.
r~
next prev parent reply other threads:[~2020-10-28 15:43 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-28 4:18 [PATCH 0/9] silence the compiler warnings Chen Qun
2020-10-28 4:18 ` [PATCH 1/9] target/i386: silence the compiler warnings in gen_shiftd_rm_T1 Chen Qun
2020-10-28 12:57 ` Thomas Huth
2020-10-28 13:20 ` Philippe Mathieu-Daudé
2020-10-28 15:31 ` Richard Henderson
2020-10-28 16:51 ` Thomas Huth
2020-10-29 2:40 ` Chenqun (kuhn)
2020-10-28 15:31 ` Richard Henderson
2020-10-28 4:18 ` [PATCH 2/9] hw/intc/arm_gicv3_kvm: silence the compiler warnings Chen Qun
2020-10-28 20:20 ` Peter Maydell
2020-10-28 4:18 ` [PATCH 3/9] accel/tcg/user-exec: " Chen Qun
2020-10-28 13:52 ` Thomas Huth
2020-10-28 15:37 ` Richard Henderson [this message]
2020-10-29 6:13 ` Chenqun (kuhn)
2020-10-28 4:18 ` [PATCH 4/9] linux-user/mips/cpu_loop: " Chen Qun
2020-10-28 13:22 ` Thomas Huth
2020-10-28 4:18 ` [PATCH 5/9] target/sparc/translate: " Chen Qun
2020-10-28 6:39 ` Artyom Tarasenko
2020-10-28 9:50 ` Philippe Mathieu-Daudé
2020-10-28 4:18 ` [PATCH 6/9] target/sparc/win_helper: " Chen Qun
2020-10-28 6:42 ` Artyom Tarasenko
2020-10-28 9:51 ` Philippe Mathieu-Daudé
2020-10-29 2:45 ` Chenqun (kuhn)
2020-10-28 4:18 ` [PATCH 7/9] ppc: " Chen Qun
2020-10-28 4:29 ` David Gibson
2020-10-28 14:42 ` Thomas Huth
2020-10-28 23:38 ` David Gibson
2020-10-29 7:06 ` Chenqun (kuhn)
2020-10-28 4:18 ` [PATCH 8/9] target/ppc: " Chen Qun
2020-10-28 4:30 ` David Gibson
2020-10-28 9:56 ` Philippe Mathieu-Daudé
2020-10-28 15:06 ` Thomas Huth
2020-10-28 23:39 ` David Gibson
2020-10-29 7:16 ` Chenqun (kuhn)
2020-10-28 4:18 ` [PATCH 9/9] hw/timer/renesas_tmr: " Chen Qun
2020-10-28 9:59 ` Philippe Mathieu-Daudé
2020-10-28 15:04 ` Thomas Huth
2020-10-28 20:14 ` Peter Maydell
2020-10-29 8:26 ` Chenqun (kuhn)
2020-10-29 8:12 ` Chenqun (kuhn)
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