[Mesa-dev] [PATCH 27/41] i965: Prevent recursive calls to FLUSH_VERTICES

[Eric Anholt]

On Thu, 17 Nov 2011 19:58:54 -0800, Chad Versace <chad.versace at linux.intel.com> wrote:
> To do so, we must resolve all buffers on entering a glBegin/glEnd block.
> For the detailed explanation, see the Doxygen comments in this patch.
> 
> Signed-off-by: Chad Versace <chad.versace at linux.intel.com>
> ---
>  src/mesa/drivers/dri/i965/brw_context.c |   73 +++++++++++++++++++++++++++++++
>  1 files changed, 73 insertions(+), 0 deletions(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
> index 9b506a6..4d51e62 100644
> --- a/src/mesa/drivers/dri/i965/brw_context.c
> +++ b/src/mesa/drivers/dri/i965/brw_context.c
> @@ -33,11 +33,23 @@
>  #include "main/imports.h"
>  #include "main/macros.h"
>  #include "main/simple_list.h"
> +
> +#include "vbo/vbo_context.h"
> +
>  #include "brw_context.h"
>  #include "brw_defines.h"
>  #include "brw_draw.h"
>  #include "brw_state.h"
> +
> +#include "gen6_hiz.h"
> +
> +#include "intel_fbo.h"
> +#include "intel_mipmap_tree.h"
> +#include "intel_regions.h"
>  #include "intel_span.h"
> +#include "intel_tex.h"
> +#include "intel_tex_obj.h"
> +
>  #include "tnl/t_pipeline.h"
>  #include "glsl/ralloc.h"
>  
> @@ -45,12 +57,73 @@
>   * Mesa's Driver Functions
>   ***************************************/
>  
> +/**
> + * \brief Prepare for entry into glBegin/glEnd block.
> + *
> + * Resolve all buffers before entering a glBegin/glEnd block. This is
> + * necessary to prevent recursive calls to FLUSH_VERTICES.
> + *
> + * Details
> + * -------
> + * When vertices are queued during a glBegin/glEnd block, those vertices must
> + * be drawn before any rendering state changes. To enusure this, Mesa calls

"ensure"

> + * FLUSH_VERTICES as a prehook to such state changes. Therefore,
> + * FLUSH_VERTICES itself cannot change rendering state without falling into a
> + * recursive trap.
> + *
> + * This precludes meta-ops, namely buffer resolves, from occuring while any
> + * vertices are queued. To prevent that situation, we resolve all buffers on
> + * entering a glBegin/glEnd
> + *
> + * \see brwCleanupExecEnd()
> + */
> +static void brwPrepareExecBegin(struct gl_context *ctx)
> +{
> +   struct brw_context *brw = brw_context(ctx);
> +   struct intel_context *intel = &brw->intel;
> +   struct intel_renderbuffer *draw_irb;
> +   struct intel_renderbuffer *read_irb;
> +   struct intel_texture_object *tex_obj;
> +
> +   if (!intel->has_hiz) {
> +      /* The context uses no feature that requires buffer resolves. */
> +      return;
> +   }
> +
> +   /* Resolve each enabled texture. */
> +   for (int i = 0; i < ctx->Const.MaxTextureImageUnits; i++) {
> +      if (!ctx->Texture.Unit[i]._ReallyEnabled)
> +	 continue;
> +      tex_obj = intel_texture_object(ctx->Texture.Unit[i]._Current);
> +      if (!tex_obj || !tex_obj->mt)
> +	 continue;
> +      intel_miptree_all_slices_resolve_hiz(intel, tex_obj->mt);
> +      intel_miptree_all_slices_resolve_depth(intel, tex_obj->mt);
> +   }
> +
> +   /* Resolve each attached depth buffer. */
> +   draw_irb = intel_get_renderbuffer(ctx->DrawBuffer, BUFFER_DEPTH);
> +   read_irb = intel_get_renderbuffer(ctx->ReadBuffer, BUFFER_DEPTH);
> +
> +   if (draw_irb) {
> +      intel_renderbuffer_resolve_hiz(intel, draw_irb);
> +      intel_renderbuffer_resolve_depth(intel, draw_irb);
> +   }
> +
> +   if (read_irb != draw_irb && read_irb) {
> +      intel_renderbuffer_resolve_hiz(intel, read_irb);
> +      intel_renderbuffer_resolve_depth(intel, read_irb);
> +   }

I find it odd that this is doing a larger set of resolves than the
brw_predraw_resolve_buffers in the next patch.  Actually, it seems like
this ought to be just brw_predraw_resolve_buffers, since you're trying
to just get that function's work done before getting any begin/end
vertices queued up, right?

All previous uncommented-by-me patches are r-b.
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