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

[Kenneth Graunke]

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");
+   }
+
    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;
-- 
2.8.3