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Subject: Re: [PATCH] powerpc: sstep: Mark variable `rc` as unused in function
 'analyse_instr'
To:     Mathieu Malaterre <malat@debian.org>
Cc:     Michael Ellerman <mpe@ellerman.id.au>,
        Paul Mackerras <paulus@samba.org>,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
        LKML <linux-kernel@vger.kernel.org>
References: <20190312202008.29681-1-malat@debian.org>
 <57a0d93c-8784-d6af-a5fb-75e31455ae57@c-s.fr>
 <CA+7wUsyA698UtNLni7wi3=cKjbCd1V71YA0sxDtMD=MmQvQxTQ@mail.gmail.com>
From:   Christophe Leroy <christophe.leroy@c-s.fr>
Message-ID: <94d90740-c970-01b0-c430-bafc2e9eecd3@c-s.fr>
Date:   Tue, 12 Mar 2019 22:25:34 +0100
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Le 12/03/2019 à 22:12, Mathieu Malaterre a écrit :
> On Tue, Mar 12, 2019 at 9:56 PM Christophe Leroy
> <christophe.leroy@c-s.fr> wrote:
>>
>>
>>
>> Le 12/03/2019 à 21:20, Mathieu Malaterre a écrit :
>>> Add gcc attribute unused for `rc` variable.
>>>
>>> Fix warnings treated as errors with W=1:
>>>
>>>     arch/powerpc/lib/sstep.c:1172:31: error: variable 'rc' set but not used [-Werror=unused-but-set-variable]
>>>
>>> Signed-off-by: Mathieu Malaterre <malat@debian.org>
>>> ---
>>>    arch/powerpc/lib/sstep.c | 2 +-
>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
>>> index 3d33fb509ef4..32d092f62ae0 100644
>>> --- a/arch/powerpc/lib/sstep.c
>>> +++ b/arch/powerpc/lib/sstep.c
>>> @@ -1169,7 +1169,7 @@ static nokprobe_inline int trap_compare(long v1, long v2)
>>>    int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
>>>                  unsigned int instr)
>>>    {
>>> -     unsigned int opcode, ra, rb, rc, rd, spr, u;
>>> +     unsigned int opcode, ra, rb, rc __maybe_unused, rd, spr, u;
>>
>> I think it would be better to enclose 'rc' inside a #ifdef CONFIG_PPC64
> 
> Hum odd, I would have bet you would have suggested me to use
> IS_ENABLED with some crazy scheme (I was not able to mix it with the
> switch case nicely).

Well I guess yes, you could also get rid of the #ifdef __powerpc64__ and 
instead add the following just after the 'case 4:'

if (!IS_ENABLED(CONFIG_64))
	break;

That's less uggly than adding two #ifdef/#endif

Christophe

> 
> Anyway I'll try your suggestion and post a v2.
> 
>> Christophe
>>
>>>        unsigned long int imm;
>>>        unsigned long int val, val2;
>>>        unsigned int mb, me, sh;
>>>