[Mesa-dev] [PATCH 1/2] state_tracker: Initialize the draw context only when needed.

[Brian Paul]

Reviewed-by: Brian Paul <brianp at vmware.com>

On 08/03/2016 11:27 AM, Eric Anholt wrote:
> It's only used for rarely-used deprecated GL features
> (feedback/rasterpos), so we can skip the memory allocation and
> initialization for it most of the time.
>
> Saves about 659k (out of 1605k) of maximum memory size according to massif
> on simulated vc4 glsl-algebraic-add-add-1
> ---
>   src/mesa/state_tracker/st_cb_feedback.c   |  5 ++++-
>   src/mesa/state_tracker/st_cb_rasterpos.c  |  5 ++++-
>   src/mesa/state_tracker/st_draw.c          | 31 +++++++++++++++++++++++--------
>   src/mesa/state_tracker/st_draw.h          |  2 ++
>   src/mesa/state_tracker/st_draw_feedback.c |  5 +++--
>   5 files changed, 36 insertions(+), 12 deletions(-)
>
> diff --git a/src/mesa/state_tracker/st_cb_feedback.c b/src/mesa/state_tracker/st_cb_feedback.c
> index 735e268be870..a18f4f76bcf2 100644
> --- a/src/mesa/state_tracker/st_cb_feedback.c
> +++ b/src/mesa/state_tracker/st_cb_feedback.c
> @@ -274,7 +274,10 @@ static void
>   st_RenderMode(struct gl_context *ctx, GLenum newMode )
>   {
>      struct st_context *st = st_context(ctx);
> -   struct draw_context *draw = st->draw;
> +   struct draw_context *draw = st_get_draw_context(st);
> +
> +   if (!st->draw)
> +      return;
>
>      if (newMode == GL_RENDER) {
>         /* restore normal VBO draw function */
> diff --git a/src/mesa/state_tracker/st_cb_rasterpos.c b/src/mesa/state_tracker/st_cb_rasterpos.c
> index 29c148471801..5dda0e2c8b7b 100644
> --- a/src/mesa/state_tracker/st_cb_rasterpos.c
> +++ b/src/mesa/state_tracker/st_cb_rasterpos.c
> @@ -219,10 +219,13 @@ static void
>   st_RasterPos(struct gl_context *ctx, const GLfloat v[4])
>   {
>      struct st_context *st = st_context(ctx);
> -   struct draw_context *draw = st->draw;
> +   struct draw_context *draw = st_get_draw_context(st);
>      struct rastpos_stage *rs;
>      const struct gl_client_array **saved_arrays = ctx->Array._DrawArrays;
>
> +   if (!st->draw)
> +      return;
> +
>      if (ctx->VertexProgram._Current == NULL ||
>          ctx->VertexProgram._Current == ctx->VertexProgram._TnlProgram) {
>         /* No vertex shader/program is enabled, used the simple/fast fixed-
> diff --git a/src/mesa/state_tracker/st_draw.c b/src/mesa/state_tracker/st_draw.c
> index b248dafc9a20..f4af23da97f3 100644
> --- a/src/mesa/state_tracker/st_draw.c
> +++ b/src/mesa/state_tracker/st_draw.c
> @@ -346,8 +346,29 @@ st_init_draw(struct st_context *st)
>
>      vbo_set_draw_func(ctx, st_draw_vbo);
>      vbo_set_indirect_draw_func(ctx, st_indirect_draw_vbo);
> +}
> +
> +
> +void
> +st_destroy_draw(struct st_context *st)
> +{
> +   draw_destroy(st->draw);
> +}
>
> -   st->draw = draw_create(st->pipe); /* for selection/feedback */
> +/**
> + * Getter for the draw_context, so that initialization of it can happen only
> + * when needed (the TGSI exec machines take up quite a bit of memory).
> + */
> +struct draw_context *
> +st_get_draw_context(struct st_context *st)
> +{
> +   if (!st->draw) {
> +      st->draw = draw_create(st->pipe);
> +      if (!st->draw) {
> +         _mesa_error(st->ctx, GL_OUT_OF_MEMORY, "feedback fallback allocation");
> +         return NULL;
> +      }
> +   }
>
>      /* Disable draw options that might convert points/lines to tris, etc.
>       * as that would foul-up feedback/selection mode.
> @@ -356,16 +377,10 @@ st_init_draw(struct st_context *st)
>      draw_wide_point_threshold(st->draw, 1000.0f);
>      draw_enable_line_stipple(st->draw, FALSE);
>      draw_enable_point_sprites(st->draw, FALSE);
> -}
> -
>
> -void
> -st_destroy_draw(struct st_context *st)
> -{
> -   draw_destroy(st->draw);
> +   return st->draw;
>   }
>
> -
>   /**
>    * Draw a quad with given position, texcoords and color.
>    */
> diff --git a/src/mesa/state_tracker/st_draw.h b/src/mesa/state_tracker/st_draw.h
> index d85c3b7facdd..fc863819c7e0 100644
> --- a/src/mesa/state_tracker/st_draw.h
> +++ b/src/mesa/state_tracker/st_draw.h
> @@ -47,6 +47,8 @@ void st_init_draw( struct st_context *st );
>
>   void st_destroy_draw( struct st_context *st );
>
> +struct draw_context *st_get_draw_context(struct st_context *st);
> +
>   extern void
>   st_draw_vbo(struct gl_context *ctx,
>               const struct _mesa_prim *prims,
> diff --git a/src/mesa/state_tracker/st_draw_feedback.c b/src/mesa/state_tracker/st_draw_feedback.c
> index e76694d4b2b0..6cc7dd77701d 100644
> --- a/src/mesa/state_tracker/st_draw_feedback.c
> +++ b/src/mesa/state_tracker/st_draw_feedback.c
> @@ -123,7 +123,7 @@ st_feedback_draw_vbo(struct gl_context *ctx,
>   {
>      struct st_context *st = st_context(ctx);
>      struct pipe_context *pipe = st->pipe;
> -   struct draw_context *draw = st->draw;
> +   struct draw_context *draw = st_get_draw_context(st);
>      const struct st_vertex_program *vp;
>      const struct pipe_shader_state *vs;
>      struct pipe_vertex_buffer vbuffers[PIPE_MAX_SHADER_INPUTS];
> @@ -136,7 +136,8 @@ st_feedback_draw_vbo(struct gl_context *ctx,
>      const GLubyte *low_addr = NULL;
>      const void *mapped_indices = NULL;
>
> -   assert(draw);
> +   if (!draw)
> +      return;
>
>      st_flush_bitmap_cache(st);
>      st_invalidate_readpix_cache(st);
>