[Mesa-dev] [PATCH] i965/miptree_map_blit: Don't do the initial copy if INVALIDATE_RANGE is set

[Kenneth Graunke]

On Tuesday, January 13, 2015 10:39:22 AM Jason Ekstrand wrote:
> Before we were always coping from the buffer being mapped into the
> temporary buffer.  However, if INVALIDATE_RANGE is set, then we know that
> the data is going to be junk after we unmap so there's no point in doing
> the blit.  This is important because doing the blit will cause a stall 3
> lines later when we map the buffer.
> 
> Signed-off-by: Jason Ekstrand <jason.ekstrand at intel.com>
> ---
>  src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 23 +++++++++++++++--------
>  1 file changed, 15 insertions(+), 8 deletions(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> index f815fbe..d44df18 100644
> --- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> +++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> @@ -1807,14 +1807,21 @@ intel_miptree_map_blit(struct brw_context *brw,
>     }
>     map->stride = map->mt->pitch;
>  
> -   if (!intel_miptree_blit(brw,
> -                           mt, level, slice,
> -                           map->x, map->y, false,
> -                           map->mt, 0, 0,
> -                           0, 0, false,
> -                           map->w, map->h, GL_COPY)) {
> -      fprintf(stderr, "Failed to blit\n");
> -      goto fail;
> +   /* One of either READ_BIT or WRITE_BIT or both is set.  READ_BIT implies no
> +    * INVALIDATE_RANGE_BIT.  WRITE_BIT needs the original values read in unless
> +    * invalidate is set, since we'll be writing the whole rectangle from our
> +    * temporary buffer back out.
> +    */
> +   if (!(map->mode & GL_MAP_INVALIDATE_RANGE_BIT)) {
> +      if (!intel_miptree_blit(brw,
> +                              mt, level, slice,
> +                              map->x, map->y, false,
> +                              map->mt, 0, 0,
> +                              0, 0, false,
> +                              map->w, map->h, GL_COPY)) {
> +         fprintf(stderr, "Failed to blit\n");
> +         goto fail;
> +      }
>     }
>  
>     map->ptr = intel_miptree_map_raw(brw, map->mt);

Just for the hell of it, how about

if (!(map->mode & (GL_MAP_INVALIDATE_RANGE_BIT | GL_MAP_INVALIDATE_BUFFER_BIT)))

I don't think we pass INVALIDATE_BUFFER_BIT today, but we could someday,
and the same logic applies.

Either way,
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
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