Re: [PATCH] introduce lower_32_bits() macro

[H. Peter Anvin]

Roland Dreier wrote:
>  > There's some readability benefit.  Sometimes it is hard to understand
>  > why some random open-coded cast was used.  But I seem to recall that
>  > there was another reason why we decided we needed this.  I forget, and
>  > so apparently did the changelog author ;)
>
> The guy who added the macro explained it in a comment ;)
>
>  * A basic shift-right of a 64- or 32-bit quantity.  Use this to suppress
>  * the "right shift count >= width of type" warning when that quantity is
>  * 32-bits.

That was for upper_32_bits() -- and can also be done with an internal 
(u64) cast; it would be interesting to find out if that would generate 
better code.

	-hpa
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