glsl: Optionally lower TES gl_PatchVerticesIn to a uniform.

i965 has no special hardware for this, so we need to pass this value in
as a uniform (unless the TES is linked against a TCS, in which case the
linker can just replace this with a constant).

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>
Cc: mesa-stable@lists.freedesktop.org

src/compiler/glsl/linker.cpp

@@ -72,6 +72,7 @@
 #include "ir.h"
 #include "program.h"
 #include "program/hash_table.h"
+#include "program/prog_instruction.h"
 #include "linker.h"
 #include "link_varyings.h"
 #include "ir_optimization.h"
@@ -2485,7 +2486,7 @@ resize_tes_inputs(struct gl_context *ctx,
       ir->accept(&input_resize_visitor);
    }
 
-   if (tcs) {
+   if (tcs || ctx->Const.LowerTESPatchVerticesIn) {
       /* Convert the gl_PatchVerticesIn system value into a constant, since
        * the value is known at this point.
        */
@@ -2494,9 +2495,22 @@ resize_tes_inputs(struct gl_context *ctx,
          if (var && var->data.mode == ir_var_system_value &&
              var->data.location == SYSTEM_VALUE_VERTICES_IN) {
             void *mem_ctx = ralloc_parent(var);
-            var->data.mode = ir_var_auto;
             var->data.location = 0;
-            var->constant_value = new(mem_ctx) ir_constant(num_vertices);
+            var->data.explicit_location = false;
+            if (tcs) {
+               var->data.mode = ir_var_auto;
+               var->constant_value = new(mem_ctx) ir_constant(num_vertices);
+            } else {
+               var->data.mode = ir_var_uniform;
+               var->data.how_declared = ir_var_hidden;
+               var->allocate_state_slots(1);
+               ir_state_slot *slot0 = &var->get_state_slots()[0];
+               slot0->swizzle = SWIZZLE_XXXX;
+               slot0->tokens[0] = STATE_INTERNAL;
+               slot0->tokens[1] = STATE_TES_PATCH_VERTICES_IN;
+               for (int i = 2; i < STATE_LENGTH; i++)
+                  slot0->tokens[i] = 0;
+            }
          }
       }
    }

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 LowerTESPatchVerticesIn; /**< Lower gl_PatchVerticesIn to a uniform */
    bool PrimitiveRestartForPatches;
    bool LowerCsDerivedVariables;    /**< Lower gl_GlobalInvocationID and
                                      *   gl_LocalInvocationIndex based on

src/mesa/program/prog_statevars.c

@@ -598,6 +598,13 @@ _mesa_fetch_state(struct gl_context *ctx, const gl_state_index state[],
          }
          return;
 
+      case STATE_TES_PATCH_VERTICES_IN:
+         if (ctx->TessCtrlProgram._Current)
+            val[0].i = ctx->TessCtrlProgram._Current->VerticesOut;
+         else
+            val[0].i = ctx->TessCtrlProgram.patch_vertices;
+         return;
+
       /* XXX: make sure new tokens added here are also handled in the 
        * _mesa_program_state_flags() switch, below.
        */

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_TES_PATCH_VERTICES_IN, /**< gl_PatchVerticesIn for TES (integer) */
    STATE_INTERNAL_DRIVER	/* first available state index for drivers (must be last) */
 } gl_state_index;