gallium: add PIPE_COMPUTE_CAP_MAX_VARIABLE_THREADS_PER_BLOCK

v3: - use a new case statement in r600_pipe_common.c
    - fix compilation of softpipe...

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>

src/gallium/docs/source/screen.rst

@@ -498,6 +498,10 @@ pipe_screen::get_compute_param.
   threads. Also known as wavefront size, warp size or SIMD width.
 * ``PIPE_COMPUTE_CAP_ADDRESS_BITS``: The default compute device address space
   size specified as an unsigned integer value in bits.
+* ``PIPE_COMPUTE_CAP_MAX_VARIABLE_THREADS_PER_BLOCK``: Maximum variable number
+  of threads that a single block can contain. This is similar to
+  PIPE_COMPUTE_CAP_MAX_THREADS_PER_BLOCK, except that the variable size is not
+  known a compile-time but at dispatch-time.
 
 .. _pipe_bind:
 

src/gallium/drivers/ilo/ilo_screen.c

@@ -303,6 +303,8 @@ ilo_get_compute_param(struct pipe_screen *screen,
       ptr = &val.subgroup_size;
       size = sizeof(val.subgroup_size);
       break;
+   case PIPE_COMPUTE_CAP_MAX_VARIABLE_THREADS_PER_BLOCK:
+      /* fallthrough */
    default:
       ptr = NULL;
       size = 0;

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

@@ -418,6 +418,8 @@ nv50_screen_get_compute_param(struct pipe_screen *pscreen,
       RET((uint32_t []) { 512 }); /* FIXME: arbitrary limit */
    case PIPE_COMPUTE_CAP_ADDRESS_BITS:
       RET((uint32_t []) { 32 });
+   case PIPE_COMPUTE_CAP_MAX_VARIABLE_THREADS_PER_BLOCK:
+      RET((uint64_t []) { 0 });
    default:
       return 0;
    }

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

@@ -478,6 +478,8 @@ nvc0_screen_get_compute_param(struct pipe_screen *pscreen,
       RET((uint32_t []) { 512 }); /* FIXME: arbitrary limit */
    case PIPE_COMPUTE_CAP_ADDRESS_BITS:
       RET((uint32_t []) { 64 });
+   case PIPE_COMPUTE_CAP_MAX_VARIABLE_THREADS_PER_BLOCK:
+      RET((uint64_t []) { 0 });
    default:
       return 0;
    }

src/gallium/drivers/radeon/r600_pipe_common.c

@@ -1036,6 +1036,8 @@ static int r600_get_compute_param(struct pipe_screen *screen,
 			*subgroup_size = r600_wavefront_size(rscreen->family);
 		}
 		return sizeof(uint32_t);
+	case PIPE_COMPUTE_CAP_MAX_VARIABLE_THREADS_PER_BLOCK:
+		return 0;
 	}
 
         fprintf(stderr, "unknown PIPE_COMPUTE_CAP %d\n", param);

src/gallium/drivers/softpipe/sp_screen.c

@@ -522,6 +522,7 @@ softpipe_get_compute_param(struct pipe_screen *_screen,
    case PIPE_COMPUTE_CAP_IMAGES_SUPPORTED:
    case PIPE_COMPUTE_CAP_SUBGROUP_SIZE:
    case PIPE_COMPUTE_CAP_ADDRESS_BITS:
+   case PIPE_COMPUTE_CAP_MAX_VARIABLE_THREADS_PER_BLOCK:
       break;
    }
    return 0;

src/gallium/include/pipe/p_defines.h

@@ -847,7 +847,8 @@ enum pipe_compute_cap
    PIPE_COMPUTE_CAP_MAX_CLOCK_FREQUENCY,
    PIPE_COMPUTE_CAP_MAX_COMPUTE_UNITS,
    PIPE_COMPUTE_CAP_IMAGES_SUPPORTED,
-   PIPE_COMPUTE_CAP_SUBGROUP_SIZE
+   PIPE_COMPUTE_CAP_SUBGROUP_SIZE,
+   PIPE_COMPUTE_CAP_MAX_VARIABLE_THREADS_PER_BLOCK,
 };
 
 /**