gallium: add fragment shader property for color writes to all buffers. (v2)

For GL fragColor semantics we need to tell the pipe drivers that the fragment
shader color result is to be replicated to all bound color buffers, this
adds the basic TGSI + documentation.

v2: fix missing comma pointed out by Tilman on mesa-dev.

Signed-off-by: Dave Airlie <airlied@redhat.com>

src/gallium/auxiliary/tgsi/tgsi_text.c

@@ -1264,7 +1264,8 @@ static const char *property_names[] =
    "GS_OUTPUT_PRIMITIVE",
    "GS_MAX_OUTPUT_VERTICES",
    "FS_COORD_ORIGIN",
-   "FS_COORD_PIXEL_CENTER"
+   "FS_COORD_PIXEL_CENTER",
+   "FS_COLOR0_WRITE_ALL_CBUFS"
 };
 
 static const char *primitive_names[] =
@@ -1398,6 +1399,8 @@ static boolean parse_property( struct translate_ctx *ctx )
          return FALSE;
       }
       break;
+   case TGSI_PROPERTY_FS_COLOR0_WRITES_ALL_CBUFS:
+      break;
    default:
       if (!parse_uint(&ctx->cur, &values[0] )) {
          report_error( ctx, "Expected unsigned integer as property!" );

src/gallium/auxiliary/tgsi/tgsi_ureg.c

@@ -148,6 +148,7 @@ struct ureg_program
    unsigned property_gs_max_vertices;
    unsigned char property_fs_coord_origin; /* = TGSI_FS_COORD_ORIGIN_* */
    unsigned char property_fs_coord_pixel_center; /* = TGSI_FS_COORD_PIXEL_CENTER_* */
+   unsigned char property_fs_color0_writes_all_cbufs; /* = TGSI_FS_COLOR0_WRITES_ALL_CBUFS * */
 
    unsigned nr_addrs;
    unsigned nr_preds;
@@ -284,7 +285,12 @@ ureg_property_fs_coord_pixel_center(struct ureg_program *ureg,
    ureg->property_fs_coord_pixel_center = fs_coord_pixel_center;
 }
 
-
+void
+ureg_property_fs_color0_writes_all_cbufs(struct ureg_program *ureg,
+                            unsigned fs_color0_writes_all_cbufs)
+{
+   ureg->property_fs_color0_writes_all_cbufs = fs_color0_writes_all_cbufs;
+}
 
 struct ureg_src
 ureg_DECL_fs_input_cyl_centroid(struct ureg_program *ureg,
@@ -1278,6 +1284,14 @@ static void emit_decls( struct ureg_program *ureg )
                     ureg->property_fs_coord_pixel_center);
    }
 
+   if (ureg->property_fs_color0_writes_all_cbufs) {
+      assert(ureg->processor == TGSI_PROCESSOR_FRAGMENT);
+
+      emit_property(ureg,
+                    TGSI_PROPERTY_FS_COLOR0_WRITES_ALL_CBUFS,
+                    ureg->property_fs_color0_writes_all_cbufs);
+   }
+
    if (ureg->processor == TGSI_PROCESSOR_VERTEX) {
       for (i = 0; i < UREG_MAX_INPUT; i++) {
          if (ureg->vs_inputs[i/32] & (1 << (i%32))) {

src/gallium/auxiliary/tgsi/tgsi_ureg.h

@@ -153,6 +153,10 @@ void
 ureg_property_fs_coord_pixel_center(struct ureg_program *ureg,
                             unsigned fs_coord_pixel_center);
 
+void
+ureg_property_fs_color0_writes_all_cbufs(struct ureg_program *ureg,
+                            unsigned fs_color0_writes_all_cbufs);
+
 /***********************************************************************
  * Build shader declarations:
  */

src/gallium/docs/source/tgsi.rst

@@ -1516,6 +1516,11 @@ GL_ARB_fragment_coord_conventions extension.
 DirectX 9 uses INTEGER.
 DirectX 10 uses HALF_INTEGER.
 
+FS_COLOR0_WRITES_ALL_CBUFS
+""""""""""""""""""""""""""
+Specifies that writes to the fragment shader color 0 are replicated to all
+bound cbufs. This facilitates OpenGL's fragColor output vs fragData[0] where
+fragData is directed to a single color buffer, but fragColor is broadcast.
 
 
 Texture Sampling and Texture Formats

src/gallium/include/pipe/p_shader_tokens.h

@@ -177,7 +177,8 @@ union tgsi_immediate_data
 #define TGSI_PROPERTY_GS_MAX_OUTPUT_VERTICES 2
 #define TGSI_PROPERTY_FS_COORD_ORIGIN        3
 #define TGSI_PROPERTY_FS_COORD_PIXEL_CENTER  4
-#define TGSI_PROPERTY_COUNT                  5
+#define TGSI_PROPERTY_FS_COLOR0_WRITES_ALL_CBUFS 5
+#define TGSI_PROPERTY_COUNT                  6
 
 struct tgsi_property {
    unsigned Type         : 4;  /**< TGSI_TOKEN_TYPE_PROPERTY */