linux-kernel - Re: [PATCH] powerpc/32: Remove one insn in _

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Date:	Wed, 10 Aug 2016 12:18:15 +0200
From:	Christophe Leroy <christophe.leroy@....fr>
To:	Gabriel Paubert <paubert@...m.es>
Cc:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	Scott Wood <oss@...error.net>, linuxppc-dev@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] powerpc/32: Remove one insn in __bswapdi2



Le 10/08/2016 à 10:56, Gabriel Paubert a écrit :
> On Fri, Aug 05, 2016 at 01:28:02PM +0200, Christophe Leroy wrote:
>> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
>> ---
>>  arch/powerpc/kernel/misc_32.S | 3 +--
>>  1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/arch/powerpc/kernel/misc_32.S b/arch/powerpc/kernel/misc_32.S
>> index e025230..e18055c 100644
>> --- a/arch/powerpc/kernel/misc_32.S
>> +++ b/arch/powerpc/kernel/misc_32.S
>> @@ -578,9 +578,8 @@ _GLOBAL(__bswapdi2)
>>  	rlwimi  r9,r4,24,0,7
>>  	rlwimi  r10,r3,24,0,7
>>  	rlwimi  r9,r4,24,16,23
>> -	rlwimi  r10,r3,24,16,23
>> +	rlwimi  r4,r3,24,16,23
>>  	mr      r3,r9
>> -	mr      r4,r10
>>  	blr
>>
>
> Hmmm, are you sure that it works? rlwimi is a bit special since the
> first operand is both an input and an output of the instruction.
>
>

Oops, you are right ...