[Mesa-stable] [PATCH 4/5] glsl: Optionally lower TCS gl_PatchVerticesIn to a uniform.

[Ian Romanick]

On 06/02/2016 02:09 PM, Kenneth Graunke wrote:
> i965 has no special hardware for this, so the best way to implement
> this is to pass it in via a uniform.
> 
> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
> Cc: mesa-stable at lists.freedesktop.org
> ---
>  src/compiler/glsl/builtin_variables.cpp | 13 ++++++++++++-
>  src/mesa/main/mtypes.h                  |  1 +
>  src/mesa/program/prog_statevars.c       |  4 ++++
>  src/mesa/program/prog_statevars.h       |  1 +
>  4 files changed, 18 insertions(+), 1 deletion(-)
> 
> diff --git a/src/compiler/glsl/builtin_variables.cpp b/src/compiler/glsl/builtin_variables.cpp
> index 05b3b0b..35a11bb 100644
> --- a/src/compiler/glsl/builtin_variables.cpp
> +++ b/src/compiler/glsl/builtin_variables.cpp
> @@ -37,6 +37,11 @@ static const struct gl_builtin_uniform_element gl_NumSamples_elements[] = {
>     {NULL, {STATE_NUM_SAMPLES, 0, 0}, SWIZZLE_XXXX}
>  };
>  
> +/* only for TCS */
> +static const struct gl_builtin_uniform_element gl_PatchVerticesIn_elements[] = {
> +   {NULL, {STATE_INTERNAL, STATE_TCS_PATCH_VERTICES_IN}, SWIZZLE_XXXX}
> +};
> +
>  static const struct gl_builtin_uniform_element gl_DepthRange_elements[] = {
>     {"near", {STATE_DEPTH_RANGE, 0, 0}, SWIZZLE_XXXX},
>     {"far", {STATE_DEPTH_RANGE, 0, 0}, SWIZZLE_YYYY},
> @@ -234,6 +239,7 @@ static const struct gl_builtin_uniform_element gl_NormalMatrix_elements[] = {
>  #define STATEVAR(name) {#name, name ## _elements, ARRAY_SIZE(name ## _elements)}
>  
>  static const struct gl_builtin_uniform_desc _mesa_builtin_uniform_desc[] = {
> +   STATEVAR(gl_PatchVerticesIn),
>     STATEVAR(gl_NumSamples),
>     STATEVAR(gl_DepthRange),
>     STATEVAR(gl_ClipPlane),
> @@ -1029,9 +1035,14 @@ void
>  builtin_variable_generator::generate_tcs_special_vars()
>  {
>     add_system_value(SYSTEM_VALUE_PRIMITIVE_ID, int_t, "gl_PrimitiveID");
> -   add_system_value(SYSTEM_VALUE_VERTICES_IN, int_t, "gl_PatchVerticesIn");
>     add_system_value(SYSTEM_VALUE_INVOCATION_ID, int_t, "gl_InvocationID");
>  
> +   if (state->ctx->Const.LowerTCSPatchVerticesIn) {
> +      add_uniform(int_t, "gl_PatchVerticesIn");
> +   } else {
> +      add_system_value(SYSTEM_VALUE_VERTICES_IN, int_t, "gl_PatchVerticesIn");
> +   }
> +

There are some built-in shader inputs that can be redeclared to add
qualifiers.  If gl_PatchVerticesIn is one of those (and I have no idea
whether or not it is), I think this will cause problems.

>     add_output(VARYING_SLOT_TESS_LEVEL_OUTER, array(float_t, 4),
>                "gl_TessLevelOuter")->data.patch = 1;
>     add_output(VARYING_SLOT_TESS_LEVEL_INNER, array(float_t, 2),
> diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
> index 8970274..f1d70fb 100644
> --- a/src/mesa/main/mtypes.h
> +++ b/src/mesa/main/mtypes.h
> @@ -3762,6 +3762,7 @@ struct gl_constants
>     GLuint MaxTessPatchComponents;
>     GLuint MaxTessControlTotalOutputComponents;
>     bool LowerTessLevel; /**< Lower gl_TessLevel* from float[n] to vecn? */
> +   bool LowerTCSPatchVerticesIn; /**< Lower gl_PatchVerticesIn to a uniform */
>     bool LowerTESPatchVerticesIn; /**< Lower gl_PatchVerticesIn to a uniform */
>     bool PrimitiveRestartForPatches;
>     bool LowerCsDerivedVariables;    /**< Lower gl_GlobalInvocationID and
> diff --git a/src/mesa/program/prog_statevars.c b/src/mesa/program/prog_statevars.c
> index 23e3015..8dddc0b 100644
> --- a/src/mesa/program/prog_statevars.c
> +++ b/src/mesa/program/prog_statevars.c
> @@ -598,6 +598,10 @@ _mesa_fetch_state(struct gl_context *ctx, const gl_state_index state[],
>           }
>           return;
>  
> +      case STATE_TCS_PATCH_VERTICES_IN:
> +         val[0].i = ctx->TessCtrlProgram.patch_vertices;
> +         return;
> +
>        case STATE_TES_PATCH_VERTICES_IN:
>           if (ctx->TessCtrlProgram._Current)
>              val[0].i = ctx->TessCtrlProgram._Current->VerticesOut;
> diff --git a/src/mesa/program/prog_statevars.h b/src/mesa/program/prog_statevars.h
> index 4b27527..e716d90 100644
> --- a/src/mesa/program/prog_statevars.h
> +++ b/src/mesa/program/prog_statevars.h
> @@ -128,6 +128,7 @@ typedef enum gl_state_index_ {
>     STATE_PT_BIAS,               /**< Pixel transfer RGBA bias */
>     STATE_FB_SIZE,               /**< (width-1, height-1, 0, 0) */
>     STATE_FB_WPOS_Y_TRANSFORM,   /**< (1, 0, -1, height) if a FBO is bound, (-1, height, 1, 0) otherwise */
> +   STATE_TCS_PATCH_VERTICES_IN, /**< gl_PatchVerticesIn for TCS (integer) */
>     STATE_TES_PATCH_VERTICES_IN, /**< gl_PatchVerticesIn for TES (integer) */
>     STATE_INTERNAL_DRIVER	/* first available state index for drivers (must be last) */
>  } gl_state_index;
>