[Mesa-dev] [PATCH] Drop the "neutral" tnl module

Kristian Høgsberg krh at bitplanet.net
Wed Oct 13 13:25:42 PDT 2010


2010/10/13 Kristian Høgsberg <krh at bitplanet.net>:
> Just always check for FLUSH_UPDATE_CURRENT and call Driver.BeginVertices
> when necessary.  By using the unlikely() macros, this ends up as
> a 10% performance improvement (for isosurf, anyway) over the old,
> complicated function pointer swapping.
> ---

I should say that this also fixes the bug we discussed a few weeks back:

  http://lists.freedesktop.org/archives/mesa-dev/2010-September/002950.html

The root cause, it turns out, was that I forgot to set up the neutral
tnl module in case of a DRI driver that supports both GL and GLES (ie
has FEATURE_beginend set) but is used for a GLES2 context.  That would
have been a more minimal patch, but this gets rid of the pointer
swapping and is faster.

Kristian

>  src/mesa/main/context.c     |    5 ---
>  src/mesa/main/mtypes.h      |   29 ------------------
>  src/mesa/main/vtxfmt.c      |   67 +-----------------------------------------
>  src/mesa/vbo/vbo_exec_api.c |   14 ++++----
>  4 files changed, 9 insertions(+), 106 deletions(-)
>
> diff --git a/src/mesa/main/context.c b/src/mesa/main/context.c
> index 41f30ca..bb2dbf4 100644
> --- a/src/mesa/main/context.c
> +++ b/src/mesa/main/context.c
> @@ -949,11 +949,6 @@ _mesa_initialize_context_for_api(struct gl_context *ctx,
>
>    switch (ctx->API) {
>    case API_OPENGL:
> -      /* Neutral tnl module stuff */
> -      _mesa_init_exec_vtxfmt( ctx );
> -      ctx->TnlModule.Current = NULL;
> -      ctx->TnlModule.SwapCount = 0;
> -
>  #if FEATURE_dlist
>       ctx->Save = _mesa_create_save_table();
>       if (!ctx->Save) {
> diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
> index aace09d..6702032 100644
> --- a/src/mesa/main/mtypes.h
> +++ b/src/mesa/main/mtypes.h
> @@ -2942,32 +2942,6 @@ struct gl_matrix_stack
>  #include "dd.h"
>
>
> -#define NUM_VERTEX_FORMAT_ENTRIES (sizeof(GLvertexformat) / sizeof(void *))
> -
> -/**
> - * Core Mesa's support for tnl modules:
> - */
> -struct gl_tnl_module
> -{
> -   /**
> -    * Vertex format to be lazily swapped into current dispatch.
> -    */
> -   const GLvertexformat *Current;
> -
> -   /**
> -    * \name Record of functions swapped out.
> -    * On restore, only need to swap these functions back in.
> -    */
> -   /*@{*/
> -   struct {
> -       _glapi_proc * location;
> -       _glapi_proc function;
> -   } Swapped[NUM_VERTEX_FORMAT_ENTRIES];
> -   GLuint SwapCount;
> -   /*@}*/
> -};
> -
> -
>  /**
>  * Display list flags.
>  * Strictly this is a tnl-private concept, but it doesn't seem
> @@ -3231,9 +3205,6 @@ struct gl_context
>     */
>    GLboolean mvp_with_dp4;
>
> -   /** Core tnl module support */
> -   struct gl_tnl_module TnlModule;
> -
>    /**
>     * \name Hooks for module contexts.
>     *
> diff --git a/src/mesa/main/vtxfmt.c b/src/mesa/main/vtxfmt.c
> index 284e777..887c7d9 100644
> --- a/src/mesa/main/vtxfmt.c
> +++ b/src/mesa/main/vtxfmt.c
> @@ -34,51 +34,11 @@
>  #include "vtxfmt.h"
>  #include "eval.h"
>  #include "dlist.h"
> +#include "main/dispatch.h"
>
>
>  #if FEATURE_beginend
>
> -
> -/* The neutral vertex format.  This wraps all tnl module functions,
> - * verifying that the currently-installed module is valid and then
> - * installing the function pointers in a lazy fashion.  It records the
> - * function pointers that have been swapped out, which allows a fast
> - * restoration of the neutral module in almost all cases -- a typical
> - * app might only require 4-6 functions to be modified from the neutral
> - * baseline, and only restoring these is certainly preferable to doing
> - * the entire module's 60 or so function pointers.
> - */
> -
> -#define PRE_LOOPBACK( FUNC )                                           \
> -{                                                                      \
> -   GET_CURRENT_CONTEXT(ctx);                                           \
> -   struct gl_tnl_module * const tnl = &(ctx->TnlModule);               \
> -   const int tmp_offset = _gloffset_ ## FUNC ;                         \
> -                                                                       \
> -   ASSERT( tnl->Current );                                             \
> -   ASSERT( tnl->SwapCount < NUM_VERTEX_FORMAT_ENTRIES );               \
> -   ASSERT( tmp_offset >= 0 );                                          \
> -                                                                        \
> -   if (tnl->SwapCount == 0)                                             \
> -      ctx->Driver.BeginVertices( ctx );                                 \
> -                                                                        \
> -   /* Save the swapped function's dispatch entry so it can be */        \
> -   /* restored later. */                                                \
> -   tnl->Swapped[tnl->SwapCount].location = & (((_glapi_proc *)ctx->Exec)[tmp_offset]); \
> -   tnl->Swapped[tnl->SwapCount].function = (_glapi_proc)TAG(FUNC);     \
> -   tnl->SwapCount++;                                                   \
> -                                                                       \
> -   if ( 0 )                                                            \
> -      _mesa_debug(ctx, "   swapping gl" #FUNC"...\n" );                        \
> -                                                                       \
> -   /* Install the tnl function pointer.        */                              \
> -   SET_ ## FUNC(ctx->Exec, tnl->Current->FUNC);                                \
> -}
> -
> -#define TAG(x) neutral_##x
> -#include "vtxfmt_tmp.h"
> -
> -
>  /**
>  * Use the per-vertex functions found in <vfmt> to initialze the given
>  * API dispatch table.
> @@ -165,17 +125,9 @@ install_vtxfmt( struct _glapi_table *tab, const GLvertexformat *vfmt )
>  }
>
>
> -void _mesa_init_exec_vtxfmt( struct gl_context *ctx )
> -{
> -   install_vtxfmt( ctx->Exec, &neutral_vtxfmt );
> -   ctx->TnlModule.SwapCount = 0;
> -}
> -
> -
>  void _mesa_install_exec_vtxfmt( struct gl_context *ctx, const GLvertexformat *vfmt )
>  {
> -   ctx->TnlModule.Current = vfmt;
> -   _mesa_restore_exec_vtxfmt( ctx );
> +   install_vtxfmt( ctx->Exec, vfmt );
>  }
>
>
> @@ -185,19 +137,4 @@ void _mesa_install_save_vtxfmt( struct gl_context *ctx, const GLvertexformat *vf
>  }
>
>
> -void _mesa_restore_exec_vtxfmt( struct gl_context *ctx )
> -{
> -   struct gl_tnl_module *tnl = &(ctx->TnlModule);
> -   GLuint i;
> -
> -   /* Restore the neutral tnl module wrapper.
> -    */
> -   for ( i = 0 ; i < tnl->SwapCount ; i++ ) {
> -      *(tnl->Swapped[i].location) = tnl->Swapped[i].function;
> -   }
> -
> -   tnl->SwapCount = 0;
> -}
> -
> -
>  #endif /* FEATURE_beginend */
> diff --git a/src/mesa/vbo/vbo_exec_api.c b/src/mesa/vbo/vbo_exec_api.c
> index 5070b35..1b31eed 100644
> --- a/src/mesa/vbo/vbo_exec_api.c
> +++ b/src/mesa/vbo/vbo_exec_api.c
> @@ -358,10 +358,12 @@ static void vbo_exec_fixup_vertex( struct gl_context *ctx,
>  #define ATTR( A, N, V0, V1, V2, V3 )                           \
>  do {                                                           \
>    struct vbo_exec_context *exec = &vbo_context(ctx)->exec;    \
> -                                                               \
> -   if (exec->vtx.active_sz[A] != N)                            \
> -      vbo_exec_fixup_vertex(ctx, A, N);                        \
> -                                                               \
> +                                                                       \
> +   if (unlikely(exec->vtx.active_sz[A] != N))                          \
> +      vbo_exec_fixup_vertex(ctx, A, N);                                        \
> +   if (unlikely(!(exec->ctx->Driver.NeedFlush & FLUSH_UPDATE_CURRENT))) \
> +      ctx->Driver.BeginVertices( ctx );                                 \
> +                                                                       \
>    {                                                           \
>       GLfloat *dest = exec->vtx.attrptr[A];                    \
>       if (N>0) dest[0] = V0;                                   \
> @@ -911,10 +913,8 @@ void vbo_exec_FlushVertices( struct gl_context *ctx, GLuint flags )
>
>    /* Need to do this to ensure BeginVertices gets called again:
>     */
> -   if (exec->ctx->Driver.NeedFlush & FLUSH_UPDATE_CURRENT) {
> -      _mesa_restore_exec_vtxfmt( ctx );
> +   if (exec->ctx->Driver.NeedFlush & FLUSH_UPDATE_CURRENT)
>       exec->ctx->Driver.NeedFlush &= ~FLUSH_UPDATE_CURRENT;
> -   }
>
>    exec->ctx->Driver.NeedFlush &= ~flags;
>
> --
> 1.7.3.1
>
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