From: "Philippe Mathieu-Daudé" <philmd@redhat.com>
To: Thomas Huth <thuth@redhat.com>,
Chen Qun <kuhn.chenqun@huawei.com>,
qemu-devel@nongnu.org, qemu-trivial@nongnu.org,
Richard Henderson <richard.henderson@linaro.org>,
Tony Nguyen <tony.nguyen@bt.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>,
zhang.zhanghailiang@huawei.com, ganqixin@huawei.com,
Euler Robot <euler.robot@huawei.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Richard Henderson <rth@twiddle.net>
Subject: Re: [PATCH 1/9] target/i386: silence the compiler warnings in gen_shiftd_rm_T1
Date: Wed, 28 Oct 2020 14:20:56 +0100 [thread overview]
Message-ID: <b868a495-4c11-bf59-3ba5-9fa4bc6fe8a1@redhat.com> (raw)
In-Reply-To: <30ca9af0-dfc2-e236-5575-068cec679508@redhat.com>
+Tony
On 10/28/20 1:57 PM, Thomas Huth wrote:
> On 28/10/2020 05.18, Chen Qun wrote:
>> The current "#ifdef TARGET_X86_64" statement affects
>> the compiler's determination of fall through.
>>
>> When using -Wimplicit-fallthrough in our CFLAGS, the compiler showed warning:
>> target/i386/translate.c: In function ‘gen_shiftd_rm_T1’:
>> target/i386/translate.c:1773:12: warning: this statement may fall through [-Wimplicit-fallthrough=]
>> if (is_right) {
>> ^
>> target/i386/translate.c:1782:5: note: here
>> case MO_32:
>> ^~~~
>>
>> Reported-by: Euler Robot <euler.robot@huawei.com>
>> Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
>> ---
>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>> Cc: Richard Henderson <richard.henderson@linaro.org>
>> Cc: Eduardo Habkost <ehabkost@redhat.com>
>> ---
>> target/i386/translate.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/target/i386/translate.c b/target/i386/translate.c
>> index caea6f5fb1..4c353427d7 100644
>> --- a/target/i386/translate.c
>> +++ b/target/i386/translate.c
>> @@ -1777,9 +1777,9 @@ static void gen_shiftd_rm_T1(DisasContext *s, MemOp ot, int op1,
>> } else {
>> tcg_gen_deposit_tl(s->T1, s->T0, s->T1, 16, 16);
>> }
>> - /* FALLTHRU */
>> -#ifdef TARGET_X86_64
>> + /* fall through */
>> case MO_32:
>> +#ifdef TARGET_X86_64
>> /* Concatenate the two 32-bit values and use a 64-bit shift. */
>> tcg_gen_subi_tl(s->tmp0, count, 1);
>> if (is_right) {
>
> The whole code here looks a little bit fishy to me ... in case TARGET_X86_64
> is defined, the MO_16 code falls through to MO_32 ... but in case it is not
> defined, it falls through to the default case that comes after the #ifdef
> block? Is this really the right thing here? If so, I think there should be
> some additional comments explaining this behavior.
>
> Richard, maybe you could help to judge what is right here...?
I think the previous discussion is this thread:
https://www.mail-archive.com/qemu-devel@nongnu.org/msg632245.html
next prev parent reply other threads:[~2020-10-28 13:22 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 [this message]
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
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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