gallium: add per-sample interpolation control into rasterizer statOAe

Required by ARB_sample_shading for drivers that don't want a shader variant
in st/mesa.

Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>
Acked-by: Roland Scheidegger <sroland@vmware.com>

src/gallium/docs/source/screen.rst

@@ -268,6 +268,15 @@ The integer capabilities:
   bounds_max states of pipe_depth_stencil_alpha_state behave according
   to the GL_EXT_depth_bounds_test specification.
 * ``PIPE_CAP_TGSI_TXQS``: Whether the `TXQS` opcode is supported
+* ``PIPE_CAP_FORCE_PERSAMPLE_INTERP``: If the driver can force per-sample
+  interpolation for all fragment shader inputs if
+  pipe_rasterizer_state::force_persample_interp is set. This is only used
+  by GL3-level sample shading (ARB_sample_shading). GL4-level sample shading
+  (ARB_gpu_shader5) doesn't use this. While GL3 hardware has a state for it,
+  GL4 hardware will likely need to emulate it with a shader variant, or by
+  selecting the interpolation weights with a conditional assignment
+  in the shader.
+
 
 
 .. _pipe_capf:

src/gallium/drivers/freedreno/freedreno_screen.c

@@ -235,6 +235,7 @@ fd_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
 	case PIPE_CAP_MAX_SHADER_PATCH_VARYINGS:
 	case PIPE_CAP_DEPTH_BOUNDS_TEST:
 	case PIPE_CAP_TGSI_TXQS:
+	case PIPE_CAP_FORCE_PERSAMPLE_INTERP:
 		return 0;
 
 	case PIPE_CAP_MAX_VIEWPORTS:

src/gallium/drivers/i915/i915_screen.c

@@ -248,6 +248,7 @@ i915_get_param(struct pipe_screen *screen, enum pipe_cap cap)
    case PIPE_CAP_TEXTURE_HALF_FLOAT_LINEAR:
    case PIPE_CAP_DEPTH_BOUNDS_TEST:
    case PIPE_CAP_TGSI_TXQS:
+   case PIPE_CAP_FORCE_PERSAMPLE_INTERP:
       return 0;
 
    case PIPE_CAP_MAX_DUAL_SOURCE_RENDER_TARGETS:

src/gallium/drivers/ilo/ilo_screen.c

@@ -470,6 +470,7 @@ ilo_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_MAX_SHADER_PATCH_VARYINGS:
    case PIPE_CAP_DEPTH_BOUNDS_TEST:
    case PIPE_CAP_TGSI_TXQS:
+   case PIPE_CAP_FORCE_PERSAMPLE_INTERP:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:

src/gallium/drivers/llvmpipe/lp_screen.c

@@ -297,6 +297,7 @@ llvmpipe_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_MAX_SHADER_PATCH_VARYINGS:
    case PIPE_CAP_DEPTH_BOUNDS_TEST:
    case PIPE_CAP_TGSI_TXQS:
+   case PIPE_CAP_FORCE_PERSAMPLE_INTERP:
       return 0;
    }
    /* should only get here on unhandled cases */

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

@@ -170,6 +170,7 @@ nv30_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_TEXTURE_FLOAT_LINEAR:
    case PIPE_CAP_TEXTURE_HALF_FLOAT_LINEAR:
    case PIPE_CAP_TGSI_TXQS:
+   case PIPE_CAP_FORCE_PERSAMPLE_INTERP:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:

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

@@ -215,6 +215,7 @@ nv50_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_RESOURCE_FROM_USER_MEMORY:
    case PIPE_CAP_DEVICE_RESET_STATUS_QUERY:
    case PIPE_CAP_MAX_SHADER_PATCH_VARYINGS:
+   case PIPE_CAP_FORCE_PERSAMPLE_INTERP:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:

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

@@ -201,6 +201,7 @@ 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_FORCE_PERSAMPLE_INTERP:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:

src/gallium/drivers/r300/r300_screen.c

@@ -196,6 +196,7 @@ static int r300_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
         case PIPE_CAP_TEXTURE_HALF_FLOAT_LINEAR:
         case PIPE_CAP_DEPTH_BOUNDS_TEST:
         case PIPE_CAP_TGSI_TXQS:
+        case PIPE_CAP_FORCE_PERSAMPLE_INTERP:
             return 0;
 
         /* SWTCL-only features. */

src/gallium/drivers/r600/r600_pipe.c

@@ -342,6 +342,7 @@ static int r600_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
 	case PIPE_CAP_VERTEXID_NOBASE:
 	case PIPE_CAP_MAX_SHADER_PATCH_VARYINGS:
 	case PIPE_CAP_DEPTH_BOUNDS_TEST:
+	case PIPE_CAP_FORCE_PERSAMPLE_INTERP:
 		return 0;
 
 	/* Stream output. */

src/gallium/drivers/radeonsi/si_pipe.c

@@ -336,6 +336,7 @@ static int si_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
 	case PIPE_CAP_TEXTURE_GATHER_OFFSETS:
 	case PIPE_CAP_SAMPLER_VIEW_TARGET:
 	case PIPE_CAP_VERTEXID_NOBASE:
+	case PIPE_CAP_FORCE_PERSAMPLE_INTERP:
 		return 0;
 
 	case PIPE_CAP_MAX_SHADER_PATCH_VARYINGS:

src/gallium/drivers/softpipe/sp_screen.c

@@ -247,6 +247,7 @@ softpipe_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_MAX_SHADER_PATCH_VARYINGS:
    case PIPE_CAP_DEPTH_BOUNDS_TEST:
    case PIPE_CAP_TGSI_TXQS:
+   case PIPE_CAP_FORCE_PERSAMPLE_INTERP:
       return 0;
    }
    /* should only get here on unhandled cases */

src/gallium/drivers/svga/svga_screen.c

@@ -380,6 +380,7 @@ svga_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_TEXTURE_HALF_FLOAT_LINEAR:
    case PIPE_CAP_DEPTH_BOUNDS_TEST:
    case PIPE_CAP_TGSI_TXQS:
+   case PIPE_CAP_FORCE_PERSAMPLE_INTERP:
       return 0;
    }
 

src/gallium/drivers/vc4/vc4_screen.c

@@ -181,6 +181,7 @@ vc4_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
 	case PIPE_CAP_TEXTURE_HALF_FLOAT_LINEAR:
 	case PIPE_CAP_DEPTH_BOUNDS_TEST:
 	case PIPE_CAP_TGSI_TXQS:
+	case PIPE_CAP_FORCE_PERSAMPLE_INTERP:
                 return 0;
 
                 /* Stream output. */

src/gallium/include/pipe/p_defines.h

@@ -631,6 +631,7 @@ enum pipe_cap
    PIPE_CAP_TEXTURE_HALF_FLOAT_LINEAR,
    PIPE_CAP_DEPTH_BOUNDS_TEST,
    PIPE_CAP_TGSI_TXQS,
+   PIPE_CAP_FORCE_PERSAMPLE_INTERP,
 };
 
 #define PIPE_QUIRK_TEXTURE_BORDER_COLOR_SWIZZLE_NV50 (1 << 0)

src/gallium/include/pipe/p_state.h

@@ -103,6 +103,7 @@ struct pipe_rasterizer_state
    unsigned point_tri_clip:1; /** large points clipped as tris or points */
    unsigned point_size_per_vertex:1; /**< size computed in vertex shader */
    unsigned multisample:1;         /* XXX maybe more ms state in future */
+   unsigned force_persample_interp:1;
    unsigned line_smooth:1;
    unsigned line_stipple_enable:1;
    unsigned line_last_pixel:1;