On Fri, Feb 1, 2013 at 1:34 PM, Eric Anholt <e...@anholt.net> wrote:
> minecraft apparently has its piles of display lists each contain 6
> instances of glBegin(GL_QUADS)/verts/glEnd(), which appear in the
> compiled list as 6 prims of 4 verts each in one draw call. We can
> reduce driver overhead even more by making that one prim of 24 verts.
>
> Improves minecraft performance by 1.6% +/- .25% (n=446)
> ---
> src/mesa/vbo/vbo_save_api.c | 43
> +++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 43 insertions(+)
>
> diff --git a/src/mesa/vbo/vbo_save_api.c b/src/mesa/vbo/vbo_save_api.c
> index 789e864..7490717 100644
> --- a/src/mesa/vbo/vbo_save_api.c
> +++ b/src/mesa/vbo/vbo_save_api.c
> @@ -301,6 +301,47 @@ _save_reset_counters(struct gl_context *ctx)
> save->dangling_attr_ref = 0;
> }
>
> +/**
> + * For a list of prims, try merging prims that can just be extensions of the
> + * previous prim.
> + */
> +static void
> +vbo_merge_prims(struct gl_context *ctx,
> + struct _mesa_prim *prim_list,
> + GLuint *prim_count)
> +{
> + GLuint i;
> + struct _mesa_prim *prev_prim = prim_list;
> +
> + for (i = 1; i < *prim_count; i++) {
> + struct _mesa_prim *this_prim = prim_list + i;
> +
> + if (this_prim->mode == prev_prim->mode &&
> + this_prim->mode == GL_QUADS &&
> + this_prim->count % 4 == 0 &&
> + prev_prim->count % 4 == 0 &&
It seems like you might be able cover GL_POINTS, GL_LINES and
GL_TRIANGLES fairly easily too.
Reviewed-by: Jordan Justen <jordan.l.jus...@intel.com>
> + this_prim->start == prev_prim->start + prev_prim->count &&
> + this_prim->basevertex == prev_prim->basevertex &&
> + this_prim->num_instances == prev_prim->num_instances &&
> + this_prim->base_instance == prev_prim->base_instance) {
> + /* We've found a prim that just extend the previous one. Tack it
> + * onto the previous one, and let this primitive struct get dropped.
> + */
> + prev_prim->count += this_prim->count;
> + prev_prim->end = this_prim->end;
> + continue;
> + }
> +
> + /* If any previous primitives have been dropped, then we need to copy
> + * this later one into the next available slot.
> + */
> + prev_prim++;
> + if (prev_prim != this_prim)
> + *prev_prim = *this_prim;
> + }
> +
> + *prim_count = prev_prim - prim_list + 1;
> +}
>
> /**
> * Insert the active immediate struct onto the display list currently
> @@ -380,6 +421,8 @@ _save_compile_vertex_list(struct gl_context *ctx)
> */
> save->copied.nr = _save_copy_vertices(ctx, node, save->buffer);
>
> + vbo_merge_prims(ctx, node->prim, &node->prim_count);
> +
> /* Deal with GL_COMPILE_AND_EXECUTE:
> */
> if (ctx->ExecuteFlag) {
> --
> 1.7.10.4
>
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