gallium: introduce PIPE_CAP_CLIP_HALFZ.

In preparation of ARB_clip_control. Let the driver decide if
it supports pipe_rasterizer_state::clip_halfz being set to true.

v3:
Initially enable on ilo.

Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
Signed-off-by: Mathias Froehlich <Mathias.Froehlich@web.de

src/gallium/docs/source/screen.rst

@@ -230,6 +230,9 @@ The integer capabilities:
   different than the underlying resource's, as permitted by
   ARB_texture_view. For example a 2d array texture may be reinterpreted as a
   cube (array) texture and vice-versa.
+* ``PIPE_CAP_CLIP_HALFZ``: Whether the driver supports the
+  pipe_rasterizer_state::clip_halfz being set to true. This is required
+  for enabling ARB_clip_control.
 
 
 .. _pipe_capf:

src/gallium/drivers/freedreno/freedreno_screen.c

@@ -226,6 +226,7 @@ fd_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
 	case PIPE_CAP_TGSI_FS_FINE_DERIVATIVE:
 	case PIPE_CAP_CONDITIONAL_RENDER_INVERTED:
 	case PIPE_CAP_SAMPLER_VIEW_TARGET:
+	case PIPE_CAP_CLIP_HALFZ:
 		return 0;
 
 	case PIPE_CAP_MAX_VIEWPORTS:

src/gallium/drivers/i915/i915_screen.c

@@ -225,6 +225,7 @@ i915_get_param(struct pipe_screen *screen, enum pipe_cap cap)
    case PIPE_CAP_TEXTURE_GATHER_OFFSETS:
    case PIPE_CAP_TGSI_VS_WINDOW_SPACE_POSITION:
    case PIPE_CAP_CONDITIONAL_RENDER_INVERTED:
+   case PIPE_CAP_CLIP_HALFZ:
       return 0;
 
    case PIPE_CAP_MAX_DUAL_SOURCE_RENDER_TARGETS:

src/gallium/drivers/ilo/ilo_screen.c

@@ -469,6 +469,8 @@ ilo_get_param(struct pipe_screen *screen, enum pipe_cap param)
    }
    case PIPE_CAP_UMA:
       return true;
+   case PIPE_CAP_CLIP_HALFZ:
+      return true;
 
    default:
       return 0;

src/gallium/drivers/llvmpipe/lp_screen.c

@@ -277,6 +277,8 @@ llvmpipe_get_param(struct pipe_screen *screen, enum pipe_cap param)
    }
    case PIPE_CAP_UMA:
       return 0;
+   case PIPE_CAP_CLIP_HALFZ:
+      return 1;
    }
    /* should only get here on unhandled cases */
    debug_printf("Unexpected PIPE_CAP %d query\n", param);

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

@@ -156,6 +156,7 @@ nv30_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_TGSI_FS_FINE_DERIVATIVE:
    case PIPE_CAP_CONDITIONAL_RENDER_INVERTED:
    case PIPE_CAP_SAMPLER_VIEW_TARGET:
+   case PIPE_CAP_CLIP_HALFZ:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:

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

@@ -204,6 +204,7 @@ nv50_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_COMPUTE:
    case PIPE_CAP_DRAW_INDIRECT:
    case PIPE_CAP_CONDITIONAL_RENDER_INVERTED:
+   case PIPE_CAP_CLIP_HALFZ:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:

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

@@ -188,6 +188,7 @@ nvc0_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_TGSI_VS_LAYER_VIEWPORT:
    case PIPE_CAP_FAKE_SW_MSAA:
    case PIPE_CAP_TGSI_VS_WINDOW_SPACE_POSITION:
+   case PIPE_CAP_CLIP_HALFZ:
       return 0;
 
    case PIPE_CAP_VENDOR_ID:

src/gallium/drivers/r300/r300_screen.c

@@ -107,6 +107,7 @@ static int r300_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
         case PIPE_CAP_USER_CONSTANT_BUFFERS:
         case PIPE_CAP_PREFER_BLIT_BASED_TEXTURE_TRANSFER:
         case PIPE_CAP_BUFFER_MAP_PERSISTENT_COHERENT:
+        case PIPE_CAP_CLIP_HALFZ:
             return 1;
 
         case PIPE_CAP_MIN_MAP_BUFFER_ALIGNMENT:

src/gallium/drivers/r600/r600_pipe.c

@@ -266,6 +266,7 @@ static int r600_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
 	case PIPE_CAP_TGSI_VS_WINDOW_SPACE_POSITION:
 	case PIPE_CAP_TGSI_VS_LAYER_VIEWPORT:
 	case PIPE_CAP_SAMPLE_SHADING:
+	case PIPE_CAP_CLIP_HALFZ:
 		return 1;
 
 	case PIPE_CAP_COMPUTE:

src/gallium/drivers/radeonsi/si_pipe.c

@@ -210,6 +210,7 @@ static int si_get_param(struct pipe_screen* pscreen, enum pipe_cap param)
 	case PIPE_CAP_CUBE_MAP_ARRAY:
 	case PIPE_CAP_SAMPLE_SHADING:
 	case PIPE_CAP_DRAW_INDIRECT:
+	case PIPE_CAP_CLIP_HALFZ:
 		return 1;
 
 	case PIPE_CAP_TEXTURE_MULTISAMPLE:

src/gallium/drivers/softpipe/sp_screen.c

@@ -227,6 +227,8 @@ softpipe_get_param(struct pipe_screen *screen, enum pipe_cap param)
       return 0;
    case PIPE_CAP_CONDITIONAL_RENDER_INVERTED:
       return 1;
+   case PIPE_CAP_CLIP_HALFZ:
+      return 1;
    }
    /* should only get here on unhandled cases */
    debug_printf("Unexpected PIPE_CAP %d query\n", param);

src/gallium/drivers/svga/svga_screen.c

@@ -281,6 +281,7 @@ svga_get_param(struct pipe_screen *screen, enum pipe_cap param)
    case PIPE_CAP_TGSI_FS_FINE_DERIVATIVE:
    case PIPE_CAP_CONDITIONAL_RENDER_INVERTED:
    case PIPE_CAP_SAMPLER_VIEW_TARGET:
+   case PIPE_CAP_CLIP_HALFZ:
       return 0;
    case PIPE_CAP_MIN_MAP_BUFFER_ALIGNMENT:
       return 64;

src/gallium/drivers/vc4/vc4_screen.c

@@ -164,6 +164,7 @@ vc4_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
         case PIPE_CAP_TGSI_FS_FINE_DERIVATIVE:
         case PIPE_CAP_CONDITIONAL_RENDER_INVERTED:
         case PIPE_CAP_SAMPLER_VIEW_TARGET:
+        case PIPE_CAP_CLIP_HALFZ:
                 return 0;
 
                 /* Stream output. */

src/gallium/include/pipe/p_defines.h

@@ -571,6 +571,7 @@ enum pipe_cap {
    PIPE_CAP_CONDITIONAL_RENDER_INVERTED = 108,
    PIPE_CAP_MAX_VERTEX_ATTRIB_STRIDE = 109,
    PIPE_CAP_SAMPLER_VIEW_TARGET = 110,
+   PIPE_CAP_CLIP_HALFZ = 111,
 };
 
 #define PIPE_QUIRK_TEXTURE_BORDER_COLOR_SWIZZLE_NV50 (1 << 0)