Re: [PATCH] atheros/atlx: Simplify bit manipulations

[David Miller]

From: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Date: Fri, 23 Jan 2015 12:06:52 +0100

> The code 'if (foo & X) foo &= ~X;' is semantically equivalent to
> simply 'foo &= ~X;', but gcc generates about four instructions for the
> former, one for the latter. Similarly, if X consists of a single bit,
> 'if (!(foo & X)) X |= X;' can be replaced by 'foo |= X;'.
> 
> In the atl2 case, gcc does know how to merge the new adjacent
> operations, so altogether this gives a nice little code size
> reduction of about 80 bytes.
> 
> Signed-off-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>

I agree with the feedback given that these open-coded sequences should
be replaced with the appropriate PCI helpers instead of edited
further.
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