vrend: use uniform for alpha func value

Some applications change glAlphaFunc nearly every frame.

Sam 3 apitrace replay went from ~4 fps to ~19 fps on a chromebook.

Signed-off-by: John Bates <jbates@chromium.com>
Reviewed-by: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: Chia-I Wu <olvaffe@gmail.com>

src/vrend_renderer.c

@@ -347,6 +347,8 @@ struct vrend_linked_shader_program {
 
    GLint fs_stipple_loc;
 
+   GLint fs_alpha_ref_val_loc;
+
    GLuint clip_locs[8];
 
    uint32_t images_used_mask[PIPE_SHADER_TYPES];
@@ -1602,6 +1604,10 @@ static struct vrend_linked_shader_program *add_shader_program(struct vrend_conte
       sprog->fs_stipple_loc = glGetUniformLocation(prog_id, "pstipple_sampler");
    else
       sprog->fs_stipple_loc = -1;
+   if (vrend_shader_needs_alpha_func(&fs->key))
+      sprog->fs_alpha_ref_val_loc = glGetUniformLocation(prog_id, "alpha_ref_val");
+   else
+      sprog->fs_alpha_ref_val_loc = -1;
    sprog->vs_ws_adjust_loc = glGetUniformLocation(prog_id, "winsys_adjust_y");
 
    vrend_use_program(ctx, prog_id);
@@ -3138,7 +3144,6 @@ static inline void vrend_fill_shader_key(struct vrend_context *ctx,
       if (add_alpha_test) {
          key->add_alpha_test = ctx->sub->dsa_state.alpha.enabled;
          key->alpha_test = ctx->sub->dsa_state.alpha.func;
-         key->alpha_ref_val = ctx->sub->dsa_state.alpha.ref_value;
       }
 
       key->pstipple_tex = ctx->sub->rs_state.poly_stipple_enable;
@@ -4228,6 +4233,10 @@ static void vrend_draw_bind_objects(struct vrend_context *ctx, bool new_program)
       glBindTexture(GL_TEXTURE_2D, ctx->pstipple_tex_id);
       glUniform1i(ctx->sub->prog->fs_stipple_loc, next_sampler_id);
    }
+
+   if (vrend_state.use_core_profile && ctx->sub->prog->fs_alpha_ref_val_loc != -1) {
+      glUniform1i(ctx->sub->prog->fs_alpha_ref_val_loc, ctx->sub->dsa_state.alpha.ref_value);
+   }
 }
 
 static

src/vrend_shader.c

@@ -1724,7 +1724,7 @@ static void emit_alpha_test(struct dump_ctx *ctx)
    case PIPE_FUNC_GREATER:
    case PIPE_FUNC_NOTEQUAL:
    case PIPE_FUNC_GEQUAL:
-      snprintf(comp_buf, 128, "%s %s %f", "fsout_c0.w", atests[ctx->key->alpha_test], ctx->key->alpha_ref_val);
+      snprintf(comp_buf, 128, "%s %s alpha_ref_val", "fsout_c0.w", atests[ctx->key->alpha_test]);
       break;
    default:
       vrend_printf( "invalid alpha-test: %x\n", ctx->key->alpha_test);
@@ -6137,6 +6137,10 @@ static void emit_ios_fs(struct dump_ctx *ctx)
       }
    }
 
+   if (vrend_shader_needs_alpha_func(ctx->key)) {
+      emit_hdr(ctx, "uniform float alpha_ref_val;\n");
+   }
+
    if (ctx->key->color_two_side) {
       if (ctx->color_in_mask & 1)
          emit_hdr(ctx, "vec4 realcolor0;\n");
@@ -7060,3 +7064,19 @@ fail:
    free(ctx.temp_ranges);
    return false;
 }
+
+bool vrend_shader_needs_alpha_func(const struct vrend_shader_key *key) {
+   if (!key->add_alpha_test)
+      return false;
+   switch (key->alpha_test) {
+   default:
+      return false;
+   case PIPE_FUNC_LESS:
+   case PIPE_FUNC_EQUAL:
+   case PIPE_FUNC_LEQUAL:
+   case PIPE_FUNC_GREATER:
+   case PIPE_FUNC_NOTEQUAL:
+   case PIPE_FUNC_GEQUAL:
+      return true;
+   }
+}

src/vrend_shader.h

@@ -117,7 +117,6 @@ struct vrend_shader_key {
 
    uint8_t prev_stage_num_clip_out;
    uint8_t prev_stage_num_cull_out;
-   float alpha_ref_val;
    uint32_t cbufs_are_a8_bitmask;
    uint8_t num_indirect_generic_outputs;
    uint8_t num_indirect_patch_outputs;
@@ -176,4 +175,7 @@ bool vrend_shader_create_passthrough_tcs(struct vrend_context *ctx,
                                          struct vrend_shader_info *sinfo,
                                          struct vrend_strarray *shader,
                                          int vertices_per_patch);
+
+bool vrend_shader_needs_alpha_func(const struct vrend_shader_key *key);
+
 #endif