gallium: add basic support for ARB_sample_shading

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>

src/gallium/auxiliary/tgsi/tgsi_strings.c

@@ -81,7 +81,10 @@ const char *tgsi_semantic_names[TGSI_SEMANTIC_COUNT] =
    "PCOORD",
    "VIEWPORT_INDEX",
    "LAYER",
-   "CULLDIST"
+   "CULLDIST",
+   "SAMPLEID",
+   "SAMPLEPOS",
+   "SAMPLEMASK"
 };
 
 const char *tgsi_texture_names[TGSI_TEXTURE_COUNT] =

src/gallium/docs/source/context.rst

@@ -67,6 +67,7 @@ objects. They all follow simple, one-method binding calls, e.g.
   which are used as comparison values in stencil test.
 * ``set_blend_color``
 * ``set_sample_mask``
+* ``set_min_samples`` sets the minimum number of samples that must be run.
 * ``set_clip_state``
 * ``set_polygon_stipple``
 * ``set_scissor_states`` sets the bounds for the scissor test, which culls

src/gallium/docs/source/screen.rst

@@ -197,6 +197,9 @@ The integer capabilities:
   in conjunction with a texture gather opcode.
 * ``PIPE_CAP_MAX_TEXTURE_GATHER_OFFSET``: The maximum offset that can be used
   in conjunction with a texture gather opcode.
+* ``PIPE_CAP_SAMPLE_SHADING``: Whether there is support for per-sample
+  shading. The context->set_min_samples function will be expected to be
+  implemented.
 
 
 .. _pipe_capf:

src/gallium/docs/source/tgsi.rst

@@ -2621,6 +2621,26 @@ distances and by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_ELEMENT_COUNT
 which specifies the maximum number of registers which can be
 annotated with those semantics.
 
+TGSI_SEMANTIC_SAMPLEID
+""""""""""""""""""""""
+
+For fragment shaders, this semantic label indicates that a system value
+contains the current sample id (i.e. gl_SampleID). Only the X value is used.
+
+TGSI_SEMANTIC_SAMPLEPOS
+"""""""""""""""""""""""
+
+For fragment shaders, this semantic label indicates that a system value
+contains the current sample's position (i.e. gl_SamplePosition). Only the X
+and Y values are used.
+
+TGSI_SEMANTIC_SAMPLEMASK
+""""""""""""""""""""""""
+
+For fragment shaders, this semantic label indicates that an output contains
+the sample mask used to disable further sample processing
+(i.e. gl_SampleMask). Only the X value is used, up to 32x MS.
+
 
 Declaration Interpolate
 ^^^^^^^^^^^^^^^^^^^^^^^

src/gallium/drivers/freedreno/freedreno_screen.c

@@ -208,6 +208,7 @@ fd_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
         case PIPE_CAP_BUFFER_MAP_PERSISTENT_COHERENT:
         case PIPE_CAP_FAKE_SW_MSAA:
 	case PIPE_CAP_TEXTURE_QUERY_LOD:
+        case PIPE_CAP_SAMPLE_SHADING:
 		return 0;
 
 	/* Stream output. */

src/gallium/drivers/i915/i915_screen.c

@@ -220,6 +220,7 @@ i915_get_param(struct pipe_screen *screen, enum pipe_cap cap)
    case PIPE_CAP_TEXTURE_GATHER_SM5:
    case PIPE_CAP_FAKE_SW_MSAA:
    case PIPE_CAP_TEXTURE_QUERY_LOD:
+   case PIPE_CAP_SAMPLE_SHADING:
       return 0;
 
    case PIPE_CAP_MAX_DUAL_SOURCE_RENDER_TARGETS:

src/gallium/drivers/ilo/ilo_screen.c

@@ -439,6 +439,7 @@ ilo_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_BUFFER_MAP_PERSISTENT_COHERENT:
    case PIPE_CAP_FAKE_SW_MSAA:
    case PIPE_CAP_TEXTURE_QUERY_LOD:
+   case PIPE_CAP_SAMPLE_SHADING:
       return 0;
 
    default:

src/gallium/drivers/llvmpipe/lp_screen.c

@@ -241,6 +241,7 @@ llvmpipe_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_TEXTURE_GATHER_SM5:
    case PIPE_CAP_BUFFER_MAP_PERSISTENT_COHERENT:
    case PIPE_CAP_TEXTURE_QUERY_LOD:
+   case PIPE_CAP_SAMPLE_SHADING:
       return 0;
    case PIPE_CAP_FAKE_SW_MSAA:
 	return 1;

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

@@ -135,6 +135,7 @@ nv30_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_BUFFER_MAP_PERSISTENT_COHERENT:
    case PIPE_CAP_FAKE_SW_MSAA:
    case PIPE_CAP_TEXTURE_QUERY_LOD:
+   case PIPE_CAP_SAMPLE_SHADING:
       return 0;
    case PIPE_CAP_VERTEX_BUFFER_OFFSET_4BYTE_ALIGNED_ONLY:
    case PIPE_CAP_VERTEX_BUFFER_STRIDE_4BYTE_ALIGNED_ONLY:

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

@@ -198,6 +198,7 @@ nv50_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_TEXTURE_GATHER_SM5:
    case PIPE_CAP_BUFFER_MAP_PERSISTENT_COHERENT:
    case PIPE_CAP_FAKE_SW_MSAA:
+   case PIPE_CAP_SAMPLE_SHADING:
       return 0;
    case PIPE_CAP_MAX_VIEWPORTS:
       return NV50_MAX_VIEWPORTS;

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

@@ -181,6 +181,7 @@ nvc0_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_TEXTURE_GATHER_SM5:
    case PIPE_CAP_BUFFER_MAP_PERSISTENT_COHERENT:
    case PIPE_CAP_FAKE_SW_MSAA:
+   case PIPE_CAP_SAMPLE_SHADING:
       return 0;
    case PIPE_CAP_MAX_VIEWPORTS:
       return 1;

src/gallium/drivers/r300/r300_screen.c

@@ -173,6 +173,7 @@ static int r300_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
         case PIPE_CAP_TEXTURE_GATHER_SM5:
         case PIPE_CAP_TEXTURE_QUERY_LOD:
         case PIPE_CAP_FAKE_SW_MSAA:
+        case PIPE_CAP_SAMPLE_SHADING:
             return 0;
 
         /* SWTCL-only features. */

src/gallium/drivers/r600/r600_pipe.c

@@ -314,6 +314,7 @@ static int r600_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
 	case PIPE_CAP_MAX_TEXTURE_GATHER_COMPONENTS:
 	case PIPE_CAP_TEXTURE_GATHER_SM5:
 	case PIPE_CAP_TEXTURE_QUERY_LOD:
+        case PIPE_CAP_SAMPLE_SHADING:
 		return 0;
 
 	/* Stream output. */

src/gallium/drivers/radeonsi/si_pipe.c

@@ -243,6 +243,7 @@ static int si_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
 	case PIPE_CAP_TGSI_TEXCOORD:
 	case PIPE_CAP_FAKE_SW_MSAA:
 	case PIPE_CAP_TEXTURE_QUERY_LOD:
+        case PIPE_CAP_SAMPLE_SHADING:
 		return 0;
 
 	case PIPE_CAP_TEXTURE_BORDER_COLOR_QUIRK:

src/gallium/drivers/softpipe/sp_screen.c

@@ -189,6 +189,7 @@ softpipe_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_TEXTURE_GATHER_SM5:
    case PIPE_CAP_BUFFER_MAP_PERSISTENT_COHERENT:
    case PIPE_CAP_TEXTURE_QUERY_LOD:
+   case PIPE_CAP_SAMPLE_SHADING:
       return 0;
    case PIPE_CAP_FAKE_SW_MSAA:
       return 1;

src/gallium/drivers/svga/svga_screen.c

@@ -273,6 +273,7 @@ svga_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_BUFFER_MAP_PERSISTENT_COHERENT:
    case PIPE_CAP_FAKE_SW_MSAA:
    case PIPE_CAP_TEXTURE_QUERY_LOD:
+   case PIPE_CAP_SAMPLE_SHADING:
       return 0;
    case PIPE_CAP_MIN_MAP_BUFFER_ALIGNMENT:
       return 64;

src/gallium/include/pipe/p_context.h

@@ -190,6 +190,9 @@ struct pipe_context {
    void (*set_sample_mask)( struct pipe_context *,
                             unsigned sample_mask );
 
+   void (*set_min_samples)( struct pipe_context *,
+                            unsigned min_samples );
+
    void (*set_clip_state)( struct pipe_context *,
                             const struct pipe_clip_state * );
 

src/gallium/include/pipe/p_defines.h

@@ -556,6 +556,7 @@ enum pipe_cap {
    PIPE_CAP_TEXTURE_QUERY_LOD = 94,
    PIPE_CAP_MIN_TEXTURE_GATHER_OFFSET = 95,
    PIPE_CAP_MAX_TEXTURE_GATHER_OFFSET = 96,
+   PIPE_CAP_SAMPLE_SHADING = 97,
 };
 
 #define PIPE_QUIRK_TEXTURE_BORDER_COLOR_SWIZZLE_NV50 (1 << 0)

src/gallium/include/pipe/p_shader_tokens.h

@@ -167,7 +167,10 @@ struct tgsi_declaration_interp
 #define TGSI_SEMANTIC_VIEWPORT_INDEX 21 /**< viewport index */
 #define TGSI_SEMANTIC_LAYER      22 /**< layer (rendertarget index) */
 #define TGSI_SEMANTIC_CULLDIST   23
-#define TGSI_SEMANTIC_COUNT      24 /**< number of semantic values */
+#define TGSI_SEMANTIC_SAMPLEID   24
+#define TGSI_SEMANTIC_SAMPLEPOS  25
+#define TGSI_SEMANTIC_SAMPLEMASK 26
+#define TGSI_SEMANTIC_COUNT      27 /**< number of semantic values */
 
 struct tgsi_declaration_semantic
 {