[Spice-devel] [PATCH spice-server v3] glz-encode: Remove obsolete reference segment

[Uri Lublin]

On 8/12/19 12:39 PM, Frediano Ziglio wrote:
> The GLZ code is basically LZ code (in spice-common) sharing image
> segments between multiple images.
> The code for RLE check in LZ (common/lz_compress_tmpl.c) is dealing
> with both RLE and dictionary matches being:
> 
>      if (!distance) {
>          /* zero distance means a run */
>          PIXEL x = *ref;
>          while ((ip < ip_bound) && (ref < ref_limit)) { // TODO: maybe separate a run from
>                                                         //       the same seg or from different
>                                                         //       ones in order to spare
>                                                         //       ref < ref_limit
> 
> in GLZ that part was copied to RLE part removing the need for the
> second segment ("ref"). However the comment and setting ref variables
> were not removed. Remove the old code to avoid confusions.
> 
> This also remove a Covscan warning as ref_limit was set not not used
> (reported by Uri Lublin).
> The warning was:
> 
> CLANG warning: "Value stored to 'ref_limit' is never read"
> 
> Signed-off-by: Frediano Ziglio <fziglio at redhat.com>

Ack.

> ---
> Changes since v2:
> - better reference to spice-common code

Thanks,
     Uri

> 
> Changes since v1:
> - Covscan is not Coverity
> ---
>   server/glz-encode.tmpl.c | 10 +++-------
>   1 file changed, 3 insertions(+), 7 deletions(-)
> 
> diff --git a/server/glz-encode.tmpl.c b/server/glz-encode.tmpl.c
> index 48bab50bc..92deb0e12 100644
> --- a/server/glz-encode.tmpl.c
> +++ b/server/glz-encode.tmpl.c
> @@ -276,19 +276,15 @@ static void FNAME(compress_seg)(Encoder *encoder, uint32_t seg_idx, PIXEL *from,
>   
>           if (LZ_EXPECT_CONDITIONAL(ip > (PIXEL *)(seg->lines))) {
>               if (SAME_PIXEL(ip[-1], ip[0]) && SAME_PIXEL(ip[0], ip[1]) && SAME_PIXEL(ip[1], ip[2])) {
> -                PIXEL x;
> +                PIXEL x = ip[2];
> +
>                   pix_dist = 1;
>                   image_dist = 0;
>   
>                   ip += 3;
> -                ref = anchor + 2;
> -                ref_limit = (PIXEL *)(seg->lines_end);
>                   len = 3;
>   
> -                x = *ref;
> -
> -                while (ip < ip_bound) { // TODO: maybe separate a run from the same seg or from
> -                                       // different ones in order to spare ref < ref_limit
> +                while (ip < ip_bound) {
>                       if (!SAME_PIXEL(*ip, x)) {
>                           ip++;
>                           break;
>