gallium: add caps for POSITION and FACE system values

v2: document the integer behavior

Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com
Reviewed-by: Brian Paul <brianp@vmware.com>

src/gallium/docs/source/screen.rst

@@ -292,6 +292,11 @@ The integer capabilities:
   supported in vertex shaders.
 * ``PIPE_CAP_TGSI_PACK_HALF_FLOAT``: Whether the ``UP2H`` and ``PK2H``
   TGSI opcodes are supported.
+* ``PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL``: If state trackers should use
+  a system value for the POSITION fragment shader input.
+* ``PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL``: If state trackers should use
+  a system value for the FACE fragment shader input.
+  Also, the FACE system value is integer, not float.
 
 
 .. _pipe_capf:

src/gallium/docs/source/tgsi.rst

@@ -2658,7 +2658,8 @@ space coordinate system.  After clipping, the X, Y and Z components of the
 vertex will be divided by the W value to get normalized device coordinates.
 
 For fragment shaders, TGSI_SEMANTIC_POSITION is used to indicate that
-fragment shader input contains the fragment's window position.  The X
+fragment shader input (or system value, depending on which one is
+supported by the driver) contains the fragment's window position.  The X
 component starts at zero and always increases from left to right.
 The Y component starts at zero and always increases but Y=0 may either
 indicate the top of the window or the bottom depending on the fragment
@@ -2770,11 +2771,17 @@ typically only used for legacy graphics APIs.
 TGSI_SEMANTIC_FACE
 """"""""""""""""""
 
-This label applies to fragment shader inputs only and indicates that
-the register contains front/back-face information of the form (F, 0,
-0, 1).  The first component will be positive when the fragment belongs
-to a front-facing polygon, and negative when the fragment belongs to a
-back-facing polygon.
+This label applies to fragment shader inputs (or system values,
+depending on which one is supported by the driver) and indicates that
+the register contains front/back-face information.
+
+If it is an input, it will be a floating-point vector in the form (F, 0, 0, 1),
+where F will be positive when the fragment belongs to a front-facing polygon,
+and negative when the fragment belongs to a back-facing polygon.
+
+If it is a system value, it will be an integer vector in the form (F, 0, 0, 1),
+where F is 0xffffffff when the fragment belongs to a front-facing polygon and
+0 when the fragment belongs to a back-facing polygon.
 
 
 TGSI_SEMANTIC_EDGEFLAG

src/gallium/drivers/freedreno/freedreno_screen.c

@@ -242,6 +242,8 @@ fd_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
 	case PIPE_CAP_CLEAR_TEXTURE:
 	case PIPE_CAP_DRAW_PARAMETERS:
 	case PIPE_CAP_TGSI_PACK_HALF_FLOAT:
+	case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
+	case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
 		return 0;
 
 	case PIPE_CAP_MAX_VIEWPORTS:

src/gallium/drivers/i915/i915_screen.c

@@ -256,6 +256,8 @@ i915_get_param(struct pipe_screen *screen, enum pipe_cap cap)
    case PIPE_CAP_CLEAR_TEXTURE:
    case PIPE_CAP_DRAW_PARAMETERS:
    case PIPE_CAP_TGSI_PACK_HALF_FLOAT:
+   case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
+   case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
       return 0;
 
    case PIPE_CAP_MAX_DUAL_SOURCE_RENDER_TARGETS:

src/gallium/drivers/ilo/ilo_screen.c

@@ -480,6 +480,8 @@ ilo_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_CLEAR_TEXTURE:
    case PIPE_CAP_DRAW_PARAMETERS:
    case PIPE_CAP_TGSI_PACK_HALF_FLOAT:
+   case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
+   case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:

src/gallium/drivers/llvmpipe/lp_screen.c

@@ -305,6 +305,8 @@ llvmpipe_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_TGSI_PACK_HALF_FLOAT:
    case PIPE_CAP_MULTI_DRAW_INDIRECT:
    case PIPE_CAP_MULTI_DRAW_INDIRECT_PARAMS:
+   case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
+   case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
       return 0;
    }
    /* should only get here on unhandled cases */

src/gallium/drivers/nouveau/nv30/nv30_screen.c

@@ -178,6 +178,8 @@ nv30_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_CLEAR_TEXTURE:
    case PIPE_CAP_DRAW_PARAMETERS:
    case PIPE_CAP_TGSI_PACK_HALF_FLOAT:
+   case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
+   case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:

src/gallium/drivers/nouveau/nv50/nv50_screen.c

@@ -221,6 +221,8 @@ nv50_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_MAX_SHADER_PATCH_VARYINGS:
    case PIPE_CAP_DRAW_PARAMETERS:
    case PIPE_CAP_TGSI_PACK_HALF_FLOAT:
+   case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
+   case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:

src/gallium/drivers/nouveau/nvc0/nvc0_screen.c

@@ -210,6 +210,8 @@ nvc0_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_VERTEXID_NOBASE:
    case PIPE_CAP_RESOURCE_FROM_USER_MEMORY:
    case PIPE_CAP_DEVICE_RESET_STATUS_QUERY:
+   case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
+   case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:

src/gallium/drivers/r300/r300_screen.c

@@ -204,6 +204,8 @@ static int r300_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
         case PIPE_CAP_CLEAR_TEXTURE:
         case PIPE_CAP_DRAW_PARAMETERS:
         case PIPE_CAP_TGSI_PACK_HALF_FLOAT:
+        case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
+        case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
             return 0;
 
         /* SWTCL-only features. */

src/gallium/drivers/r600/r600_pipe.c

@@ -352,6 +352,8 @@ static int r600_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
 	case PIPE_CAP_TGSI_PACK_HALF_FLOAT:
 	case PIPE_CAP_MULTI_DRAW_INDIRECT:
 	case PIPE_CAP_MULTI_DRAW_INDIRECT_PARAMS:
+	case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
+	case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
 		return 0;
 
 	case PIPE_CAP_MAX_SHADER_PATCH_VARYINGS:

src/gallium/drivers/radeonsi/si_pipe.c

@@ -344,6 +344,8 @@ static int si_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
 	case PIPE_CAP_TGSI_PACK_HALF_FLOAT:
 	case PIPE_CAP_MULTI_DRAW_INDIRECT:
 	case PIPE_CAP_MULTI_DRAW_INDIRECT_PARAMS:
+	case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
+	case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
 		return 0;
 
 	case PIPE_CAP_MAX_SHADER_PATCH_VARYINGS:

src/gallium/drivers/softpipe/sp_screen.c

@@ -255,6 +255,8 @@ softpipe_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_TGSI_PACK_HALF_FLOAT:
    case PIPE_CAP_MULTI_DRAW_INDIRECT:
    case PIPE_CAP_MULTI_DRAW_INDIRECT_PARAMS:
+   case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
+   case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
       return 0;
    }
    /* should only get here on unhandled cases */

src/gallium/drivers/svga/svga_screen.c

@@ -388,6 +388,8 @@ svga_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_COPY_BETWEEN_COMPRESSED_AND_PLAIN_FORMATS:
    case PIPE_CAP_CLEAR_TEXTURE:
    case PIPE_CAP_DRAW_PARAMETERS:
+   case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
+   case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
       return 0;
    }
 

src/gallium/drivers/vc4/vc4_screen.c

@@ -193,6 +193,8 @@ vc4_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
 	case PIPE_CAP_CLEAR_TEXTURE:
 	case PIPE_CAP_DRAW_PARAMETERS:
 	case PIPE_CAP_TGSI_PACK_HALF_FLOAT:
+	case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
+	case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
                 return 0;
 
                 /* Stream output. */

src/gallium/drivers/virgl/virgl_screen.c

@@ -223,6 +223,8 @@ virgl_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_CLEAR_TEXTURE:
    case PIPE_CAP_DRAW_PARAMETERS:
    case PIPE_CAP_TGSI_PACK_HALF_FLOAT:
+   case PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL:
+   case PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL:
       return 0;
    case PIPE_CAP_VENDOR_ID:
       return 0x1af4;

src/gallium/include/pipe/p_defines.h

@@ -639,6 +639,8 @@ enum pipe_cap
    PIPE_CAP_TGSI_PACK_HALF_FLOAT,
    PIPE_CAP_MULTI_DRAW_INDIRECT,
    PIPE_CAP_MULTI_DRAW_INDIRECT_PARAMS,
+   PIPE_CAP_TGSI_FS_POSITION_IS_SYSVAL,
+   PIPE_CAP_TGSI_FS_FACE_IS_INTEGER_SYSVAL,
 };
 
 #define PIPE_QUIRK_TEXTURE_BORDER_COLOR_SWIZZLE_NV50 (1 << 0)