st/mesa: Add NIR versions of the drawpixels Z/stencil fragment shaders.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Tested-by: Rob Clark <robdclark@gmail.com>
Tested-by: Eric Anholt <eric@anholt.net>

src/mesa/state_tracker/st_cb_drawpixels.c

@@ -108,34 +108,97 @@
  */
 #define USE_DRAWPIXELS_CACHE 1
 
+static nir_ssa_def *
+sample_via_nir(nir_builder *b, nir_variable *texcoord,
+               const char *name, int sampler)
+{
+   const struct glsl_type *sampler2D =
+      glsl_sampler_type(GLSL_SAMPLER_DIM_2D, false, false, GLSL_TYPE_FLOAT);
+
+   nir_variable *var =
+      nir_variable_create(b->shader, nir_var_uniform, sampler2D, name);
+   var->data.binding = sampler;
+
+   nir_tex_instr *tex = nir_tex_instr_create(b->shader, 1);
+   tex->op = nir_texop_tex;
+   tex->sampler_dim = GLSL_SAMPLER_DIM_2D;
+   tex->coord_components = 2;
+   tex->sampler_index = sampler;
+   tex->texture_index = sampler;
+   tex->dest_type = nir_type_float;
+   tex->src[0].src_type = nir_tex_src_coord;
+   tex->src[0].src =
+      nir_src_for_ssa(nir_channels(b, nir_load_var(b, texcoord),
+                                   (1 << tex->coord_components) - 1));
+
+   nir_ssa_dest_init(&tex->instr, &tex->dest, 4, 32, NULL);
+   nir_builder_instr_insert(b, &tex->instr);
+   return nir_channel(b, &tex->dest.ssa, 0);
+}
+
+static void *
+make_drawpix_z_stencil_program_nir(struct st_context *st,
+                                   bool write_depth,
+                                   bool write_stencil)
+{
+   struct nir_builder b;
+   const nir_shader_compiler_options *options =
+      st->ctx->Const.ShaderCompilerOptions[MESA_SHADER_FRAGMENT].NirOptions;
+
+   nir_builder_init_simple_shader(&b, NULL, MESA_SHADER_FRAGMENT, options);
+
+   nir_variable *texcoord =
+      nir_variable_create(b.shader, nir_var_shader_in, glsl_vec_type(2),
+                          "texcoord");
+   texcoord->data.location = VARYING_SLOT_TEX0;
+
+   if (write_depth) {
+      nir_variable *out =
+         nir_variable_create(b.shader, nir_var_shader_out, glsl_float_type(),
+                             "gl_FragDepth");
+      out->data.location = FRAG_RESULT_DEPTH;
+      nir_ssa_def *depth = sample_via_nir(&b, texcoord, "depth", 0);
+      nir_store_var(&b, out, depth, 0x1);
+
+      /* Also copy color */
+      nir_variable *color_in =
+         nir_variable_create(b.shader, nir_var_shader_in, glsl_vec_type(4),
+                             "v_color");
+      color_in->data.location = VARYING_SLOT_COL0;
+
+      nir_variable *color_out =
+         nir_variable_create(b.shader, nir_var_shader_out, glsl_vec_type(4),
+                             "gl_FragColor");
+      color_out->data.location = FRAG_RESULT_COLOR;
+      nir_copy_var(&b, color_out, color_in);
+   }
+
+   if (write_stencil) {
+      nir_variable *out =
+         nir_variable_create(b.shader, nir_var_shader_out, glsl_uint_type(),
+                             "gl_FragStencilRefARB");
+      out->data.location = FRAG_RESULT_STENCIL;
+      nir_ssa_def *stencil = sample_via_nir(&b, texcoord, "stencil", 1);
+      nir_store_var(&b, out, stencil, 0x1);
+   }
+
+   char name[14];
+   snprintf(name, 14, "drawpixels %s%s",
+            write_depth ? "Z" : "", write_stencil ? "S" : "");
+
+   return st_nir_finish_builtin_shader(st, b.shader, name);
+}
 
 
-/**
- * Create fragment program that does a TEX() instruction to get a Z and/or
- * stencil value value, then writes to FRAG_RESULT_DEPTH/FRAG_RESULT_STENCIL.
- * Used for glDrawPixels(GL_DEPTH_COMPONENT / GL_STENCIL_INDEX).
- * Pass fragment color through as-is.
- *
- * \return CSO of the fragment shader.
- */
 static void *
-get_drawpix_z_stencil_program(struct st_context *st,
-                              GLboolean write_depth,
-                              GLboolean write_stencil)
+make_drawpix_z_stencil_program_tgsi(struct st_context *st,
+                                    bool write_depth,
+                                    bool write_stencil)
 {
    struct ureg_program *ureg;
    struct ureg_src depth_sampler, stencil_sampler;
    struct ureg_src texcoord, color;
    struct ureg_dst out_color, out_depth, out_stencil;
-   const GLuint shaderIndex = write_depth * 2 + write_stencil;
-   void *cso;
-
-   assert(shaderIndex < ARRAY_SIZE(st->drawpix.zs_shaders));
-
-   if (st->drawpix.zs_shaders[shaderIndex]) {
-      /* already have the proper shader */
-      return st->drawpix.zs_shaders[shaderIndex];
-   }
 
    ureg = ureg_create(PIPE_SHADER_FRAGMENT);
    if (ureg == NULL)
@@ -184,7 +247,42 @@ get_drawpix_z_stencil_program(struct st_context *st,
                TGSI_TEXTURE_2D, texcoord, stencil_sampler);
 
    ureg_END(ureg);
-   cso = ureg_create_shader_and_destroy(ureg, st->pipe);
+   return ureg_create_shader_and_destroy(ureg, st->pipe);
+}
+
+
+/**
+ * Create fragment program that does a TEX() instruction to get a Z and/or
+ * stencil value value, then writes to FRAG_RESULT_DEPTH/FRAG_RESULT_STENCIL.
+ * Used for glDrawPixels(GL_DEPTH_COMPONENT / GL_STENCIL_INDEX).
+ * Pass fragment color through as-is.
+ *
+ * \return CSO of the fragment shader.
+ */
+static void *
+get_drawpix_z_stencil_program(struct st_context *st,
+                              bool write_depth,
+                              bool write_stencil)
+{
+   struct pipe_screen *pscreen = st->pipe->screen;
+   const GLuint shaderIndex = write_depth * 2 + write_stencil;
+   void *cso;
+
+   assert(shaderIndex < ARRAY_SIZE(st->drawpix.zs_shaders));
+
+   if (st->drawpix.zs_shaders[shaderIndex]) {
+      /* already have the proper shader */
+      return st->drawpix.zs_shaders[shaderIndex];
+   }
+
+   enum pipe_shader_ir preferred_ir =
+      pscreen->get_shader_param(pscreen, PIPE_SHADER_FRAGMENT,
+                                PIPE_SHADER_CAP_PREFERRED_IR);
+
+   if (preferred_ir == PIPE_SHADER_IR_NIR)
+      cso = make_drawpix_z_stencil_program_nir(st, write_depth, write_stencil);
+   else
+      cso = make_drawpix_z_stencil_program_tgsi(st, write_depth, write_stencil);
 
    /* save the new shader */
    st->drawpix.zs_shaders[shaderIndex] = cso;