Mesa (main): mesa/st: clear color buffers using color from a constant buffer

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Module: Mesa
Branch: main
Commit: c6bb8961a89f81749b73efd92419b7a793327cf3
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=c6bb8961a89f81749b73efd92419b7a793327cf3

Author: Indrajit Kumar Das <indrajit-kumar.das at amd.com>
Date:   Fri May 13 17:22:15 2022 +0530

mesa/st: clear color buffers using color from a constant buffer

v2: fixed GLCTS failures (mareko)

Reviewed-by: Marek Olšák <marek.olsak at amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/15318>

---

 src/mesa/state_tracker/st_cb_clear.c | 41 ++++++++++++++++--------------------
 1 file changed, 18 insertions(+), 23 deletions(-)

diff --git a/src/mesa/state_tracker/st_cb_clear.c b/src/mesa/state_tracker/st_cb_clear.c
index 75228555923..f24ddb9a288 100644
--- a/src/mesa/state_tracker/st_cb_clear.c
+++ b/src/mesa/state_tracker/st_cb_clear.c
@@ -103,56 +103,49 @@ st_destroy_clear(struct st_context *st)
 
 
 /**
- * Helper function to set the fragment shaders.
+ * Helper function to set the clear color fragment shader.
  */
-static inline void
-set_fragment_shader(struct st_context *st)
+static void
+set_clearcolor_fs(struct st_context *st, union pipe_color_union *color)
 {
    struct pipe_screen *pscreen = st->screen;
    bool use_nir = PIPE_SHADER_IR_NIR ==
       pscreen->get_shader_param(pscreen, PIPE_SHADER_VERTEX,
                                 PIPE_SHADER_CAP_PREFERRED_IR);
+   struct pipe_constant_buffer cb = {
+      .user_buffer = color->f,
+      .buffer_size = 4 * sizeof(float),
+   };
+   st->pipe->set_constant_buffer(st->pipe, PIPE_SHADER_FRAGMENT, 0,
+                                false, &cb);
 
    if (!st->clear.fs) {
       if (use_nir) {
-         unsigned inputs[] = { VARYING_SLOT_VAR0 };
-         unsigned outputs[] = { FRAG_RESULT_COLOR };
-         unsigned interpolation[] = { INTERP_MODE_FLAT };
-         st->clear.fs = st_nir_make_passthrough_shader(st, "clear FS",
-                                                       MESA_SHADER_FRAGMENT,
-                                                       1, inputs, outputs,
-                                                       interpolation, 0);
+         st->clear.fs = st_nir_make_clearcolor_shader(st);
       } else {
-         st->clear.fs =
-            util_make_fragment_passthrough_shader(st->pipe,
-                                                  TGSI_SEMANTIC_GENERIC,
-                                                  TGSI_INTERPOLATE_CONSTANT,
-                                                  TRUE);
+         st->clear.fs = util_make_fs_clear_all_cbufs(st->pipe);
       }
    }
 
    cso_set_fragment_shader_handle(st->cso_context, st->clear.fs);
 }
 
-
 static void *
 make_nir_clear_vertex_shader(struct st_context *st, bool layered)
 {
    const char *shader_name = layered ? "layered clear VS" : "clear VS";
    unsigned inputs[] = {
       VERT_ATTRIB_POS,
-      VERT_ATTRIB_GENERIC0,
       SYSTEM_VALUE_INSTANCE_ID,
    };
    unsigned outputs[] = {
       VARYING_SLOT_POS,
-      VARYING_SLOT_VAR0,
       VARYING_SLOT_LAYER
    };
 
    return st_nir_make_passthrough_shader(st, shader_name, MESA_SHADER_VERTEX,
-                                         layered ? 3 : 2, inputs, outputs,
-                                         NULL, (1 << 2));
+                                         layered ? 2 : 1, inputs, outputs,
+                                         NULL, (1 << 1));
 }
 
 
@@ -320,7 +313,7 @@ clear_with_quad(struct gl_context *ctx, unsigned clear_buffers)
       cso_set_depth_stencil_alpha(cso, &depth_stencil);
    }
 
-   st->util_velems.count = 2;
+   st->util_velems.count = 1;
    cso_set_vertex_elements(cso, &st->util_velems);
 
    cso_set_stream_outputs(cso, 0, NULL, NULL);
@@ -333,7 +326,8 @@ clear_with_quad(struct gl_context *ctx, unsigned clear_buffers)
    cso_set_viewport_dims(st->cso_context, fb_width, fb_height,
                          _mesa_fb_orientation(fb) == Y_0_TOP);
 
-   set_fragment_shader(st);
+   /* Set constant buffer */
+   set_clearcolor_fs(st, (union pipe_color_union*)&ctx->Color.ClearColor);
    cso_set_tessctrl_shader_handle(cso, NULL);
    cso_set_tesseval_shader_handle(cso, NULL);
 
@@ -361,7 +355,8 @@ clear_with_quad(struct gl_context *ctx, unsigned clear_buffers)
    /* Restore pipe state */
    cso_restore_state(cso, 0);
    ctx->Array.NewVertexElements = true;
-   st->dirty |= ST_NEW_VERTEX_ARRAYS;
+   st->dirty |= ST_NEW_VERTEX_ARRAYS |
+                ST_NEW_FS_CONSTANTS;
 }