linux-kernel - Re: [PATCH 18/20] ethernet: ucc_geth: add helper to replace repeated switch statements

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Message-ID: <17e064c3-41a7-fbc2-d9ee-35dd33345e16@prevas.dk>
Date:   Tue, 8 Dec 2020 21:55:46 +0100
From:   Rasmus Villemoes <rasmus.villemoes@...vas.dk>
To:     Christophe Leroy <christophe.leroy@...roup.eu>,
        Li Yang <leoyang.li@....com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     Vladimir Oltean <vladimir.oltean@....com>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, Zhao Qiang <qiang.zhao@....com>
Subject: Re: [PATCH 18/20] ethernet: ucc_geth: add helper to replace repeated
 switch statements

On 08/12/2020 16.21, Christophe Leroy wrote:
> 
> 
> Le 05/12/2020 à 20:17, Rasmus Villemoes a écrit :
>> The translation from the ucc_geth_num_of_threads enum value to the
>> actual count can be written somewhat more compactly with a small
>> lookup table, allowing us to replace the four switch statements.
>>
> I think you would allow GCC to provide a much better optimisation with
> something like:
> 

Your version compiles to 120 bytes of object code, mine around 49
(including the 5 byte lookup table). They're about the same in line count.

Rasmus