linux-kernel - Re: InfiniBand-ocrdma: Delete unnecessary variable initialisations in 11 functions

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Date:	Fri, 15 Jan 2016 16:26:36 +0100
From:	SF Markus Elfring <elfring@...rs.sourceforge.net>
To:	linux-rdma@...r.kernel.org, Leon Romanovsky <leon@...n.nu>
Cc:	Devesh Sharma <devesh.sharma@...gotech.com>,
	Doug Ledford <dledford@...hat.com>,
	Hal Rosenstock <hal.rosenstock@...il.com>,
	Mitesh Ahuja <mitesh.ahuja@...gotech.com>,
	Sean Hefty <sean.hefty@...el.com>,
	Selvin Xavier <selvin.xavier@...gotech.com>,
	LKML <linux-kernel@...r.kernel.org>,
	kernel-janitors@...r.kernel.org,
	Julia Lawall <julia.lawall@...6.fr>
Subject: Re: InfiniBand-ocrdma: Delete unnecessary variable initialisations in
 11 functions

>> Would you like to clarify any measurable effects around the implementation
>> detail when various variables will only be initialised immediately
>> before they will be read again?
> 
> Compiler will drop this variable initialization by itself because
> there are no reads between this variable initialization and write.

Which compiler variants would you to take into account for such an use case?


> I recommend you to take a look on the assembly code and ensure it
> by yourself.

Will any configuration parameters and command arguments become relevant
to improve also a corresponding software comparison?


> The proposed change won't affect performance at all.

Will unneeded variable assignments be really optimised away by default?


By the way:
Will a small source code reduction matter also a bit here?

Regards,
Markus