[xserver patch] Optimize shadowUpdatePacked()

[Ian Romanick]

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Adrian Bunk wrote:
> From: Ilpo Ruotsalainen <ilpo.ruotsalainen at movial.com>
> 
> http://bugs.freedesktop.org/show_bug.cgi?id=26973
> 
> Signed-off-by: Adrian Bunk <adrian.bunk at movial.com>
> 
> ---
> 
> We already ship this patch in the ARM Linux Internet Platform, and it 
> looks like a good candidate for upstream inclusion.
> 
> The "#define PickBit" can be deleted, but that's unrelated.
> 
>  miext/shadow/shpacked.c |    3 +--
>  1 files changed, 1 insertions(+), 2 deletions(-)
> 
> diff --git a/miext/shadow/shpacked.c b/miext/shadow/shpacked.c
> index 6736162..f95adf9 100644
> --- a/miext/shadow/shpacked.c
> +++ b/miext/shadow/shpacked.c
> @@ -102,8 +102,7 @@ shadowUpdatePacked (ScreenPtr	    pScreen,
>  		width -= i;
>  		scr += i;
>  #define PickBit(a,i)	(((a) >> (i)) & 1)
> -		while (i--)
> -		    *win++ = *sha++;
> +		memcpy(win, sha, i * sizeof(FbBits));
>  	    }
>  	    shaLine += shaStride;
>  	    y++;

Are the values of "win" and "sha" used later in the code?  Are the
regions of memory accessed by "win" and "sha" known to not overlap in a
way that works with the current code but might break with memcpy?

Those are the only two possible issues that I could see from this change.
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