netdev - Re: cxgb3: Fix sparse warning and micro-optimize is_pure

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Date:	Fri, 28 Nov 2008 21:55:48 -0800 (PST)
From:	David Miller <davem@...emloft.net>
To:	rdreier@...co.com
Cc:	divy@...lsio.com, jeff@...zik.org, netdev@...r.kernel.org
Subject: Re: cxgb3: Fix sparse warning and micro-optimize is_pure_response()

From: Roland Dreier <rdreier@...co.com>
Date: Fri, 28 Nov 2008 21:47:03 -0800

> The function is_pure_response() does "ntohl(var) & const" and then
> essentially just tests whether the result is 0 or not; this can be done
> more efficiently by computing "var & htonl(const)" instead and doing the
> byte swap at compile time instead of run time.
> 
> This change slightly shrinks the compiled code; eg on x86-64 we save a
> couple of bswapl instructions:
> 
> add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-8 (-8)
> function                                     old     new   delta
> t3_sge_intr_msix_napi                        544     536      -8
> 
> and this also has the pleasant side effect of fixing a sparse warning:
> 
>     drivers/net/cxgb3/sge.c:2313:15: warning: restricted degrades to integer
> 
> Signed-off-by: Roland Dreier <rolandd@...co.com>

Applied, thanks Roland.
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