gallium: add a pipe cap for performing automatic prim type conversion

drivers can now export a bitmask of the primitive types they support,
and all others will be automatically be rewritten

the default value is set to all primitive types supported to preserve
existing behavior

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Rob Clark <robdclark@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10973>

docs/gallium/screen.rst

@@ -616,6 +616,7 @@ The integer capabilities:
 * ``PIPE_CAP_SAMPLER_REDUCTION_MINMAX``: Driver supports EXT min/max sampler reduction.
 * ``PIPE_CAP_SAMPLER_REDUCTION_MINMAX_ARB``: Driver supports ARB min/max sampler reduction with format queries.
 * ``PIPE_CAP_EMULATE_NONFIXED_PRIMITIVE_RESTART``: Driver requests all draws using a non-fixed restart index to be rewritten to use a fixed restart index.
+* ``PIPE_CAP_SUPPORTED_PRIM_MODES``: A bitmask of the ``pipe_prim_type`` enum values that the driver can natively support.
 
 .. _pipe_capf:
 

src/gallium/auxiliary/util/u_screen.c

@@ -87,6 +87,9 @@ u_pipe_screen_get_param_defaults(struct pipe_screen *pscreen,
    case PIPE_CAP_RGB_OVERRIDE_DST_ALPHA_BLEND:
       return 0;
 
+   case PIPE_CAP_SUPPORTED_PRIM_MODES:
+      return BITFIELD_MASK(PIPE_PRIM_MAX);
+
    case PIPE_CAP_MIN_TEXEL_OFFSET:
       /* GL 3.x minimum value. */
       return -8;

src/gallium/auxiliary/util/u_vbuf.c

@@ -310,6 +310,9 @@ void u_vbuf_get_caps(struct pipe_screen *screen, struct u_vbuf_caps *caps,
       caps->rewrite_restart_index = screen->get_param(screen, PIPE_CAP_EMULATE_NONFIXED_PRIMITIVE_RESTART);
       caps->fallback_always |= caps->rewrite_restart_index;
    }
+   caps->supported_prim_modes = screen->get_param(screen, PIPE_CAP_SUPPORTED_PRIM_MODES);
+   if (caps->supported_prim_modes != BITFIELD_MASK(PIPE_PRIM_MAX))
+      caps->fallback_always = true;
 
    if (!screen->is_format_supported(screen, PIPE_FORMAT_R8_UINT, PIPE_BUFFER, 0, 0, PIPE_BIND_INDEX_BUFFER))
       caps->fallback_always = caps->rewrite_ubyte_ibs = true;
@@ -334,10 +337,11 @@ u_vbuf_create(struct pipe_context *pipe, struct u_vbuf_caps *caps)
 
    mgr->caps = *caps;
    mgr->pipe = pipe;
-   if (caps->rewrite_ubyte_ibs || caps->rewrite_restart_index) {
+   if (caps->rewrite_ubyte_ibs || caps->rewrite_restart_index ||
+       (caps->supported_prim_modes & BITFIELD_MASK(PIPE_PRIM_MAX)) != BITFIELD_MASK(PIPE_PRIM_MAX)) {
       struct primconvert_config cfg;
       cfg.fixed_prim_restart = caps->rewrite_restart_index;
-      cfg.primtypes_mask = 0xff;
+      cfg.primtypes_mask = caps->supported_prim_modes;
       cfg.restart_primtypes_mask = 0xff;
       mgr->pc = util_primconvert_create_config(pipe, &cfg);
    }
@@ -1387,7 +1391,8 @@ void u_vbuf_draw_vbo(struct u_vbuf *mgr, const struct pipe_draw_info *info,
        (info->index_size != 1 || !mgr->caps.rewrite_ubyte_ibs) &&
        (!info->primitive_restart ||
         info->restart_index == fixed_restart_index ||
-        !mgr->caps.rewrite_restart_index)) {
+        !mgr->caps.rewrite_restart_index) &&
+       mgr->caps.supported_prim_modes & BITFIELD_BIT(info->mode)) {
 
       /* Set vertex buffers if needed. */
       if (mgr->dirty_real_vb_mask & used_vb_mask) {
@@ -1668,7 +1673,8 @@ void u_vbuf_draw_vbo(struct u_vbuf *mgr, const struct pipe_draw_info *info,
 
    if ((new_info.index_size == 1 && mgr->caps.rewrite_ubyte_ibs) ||
        (new_info.primitive_restart &&
-        (new_info.restart_index != fixed_restart_index && mgr->caps.rewrite_restart_index))) {
+        new_info.restart_index != fixed_restart_index && mgr->caps.rewrite_restart_index) ||
+       !(mgr->caps.supported_prim_modes & BITFIELD_BIT(new_info.mode))) {
       util_primconvert_save_flatshade_first(mgr->pc, mgr->flatshade_first);
       util_primconvert_draw_vbo(mgr->pc, &new_info, drawid_offset, indirect, &new_draw, 1);
    } else

src/gallium/auxiliary/util/u_vbuf.h

@@ -57,6 +57,7 @@ struct u_vbuf_caps {
    /* Maximum number of vertex buffers */
    unsigned max_vertex_buffers:6;
 
+   uint16_t supported_prim_modes;
    bool fallback_always;
    bool fallback_only_for_user_vbuffers;
    bool rewrite_ubyte_ibs;

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

@@ -105,6 +105,8 @@ nv30_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    /* nv35 capabilities */
    case PIPE_CAP_DEPTH_BOUNDS_TEST:
       return eng3d->oclass == NV35_3D_CLASS || eng3d->oclass >= NV40_3D_CLASS;
+   case PIPE_CAP_SUPPORTED_PRIM_MODES:
+      return BITFIELD_MASK(PIPE_PRIM_MAX);
    /* nv4x capabilities */
    case PIPE_CAP_BLEND_EQUATION_SEPARATE:
    case PIPE_CAP_NPOT_TEXTURES:

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

@@ -188,6 +188,9 @@ nv50_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_MAX_TEXTURE_MB:
       return 0; /* TODO: use 1/2 of VRAM for this? */
 
+   case PIPE_CAP_SUPPORTED_PRIM_MODES:
+      return BITFIELD_MASK(PIPE_PRIM_MAX);
+
    /* supported caps */
    case PIPE_CAP_TEXTURE_MIRROR_CLAMP:
    case PIPE_CAP_TEXTURE_MIRROR_CLAMP_TO_EDGE:

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

@@ -208,6 +208,9 @@ nvc0_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
    case PIPE_CAP_MAX_TEXTURE_MB:
       return 0; /* TODO: use 1/2 of VRAM for this? */
 
+   case PIPE_CAP_SUPPORTED_PRIM_MODES:
+      return BITFIELD_MASK(PIPE_PRIM_MAX);
+
    /* supported caps */
    case PIPE_CAP_TEXTURE_MIRROR_CLAMP:
    case PIPE_CAP_TEXTURE_MIRROR_CLAMP_TO_EDGE:

src/gallium/include/pipe/p_defines.h

@@ -990,6 +990,7 @@ enum pipe_cap
    PIPE_CAP_SAMPLER_REDUCTION_MINMAX_ARB,
    PIPE_CAP_ALLOW_DYNAMIC_VAO_FASTPATH,
    PIPE_CAP_EMULATE_NONFIXED_PRIMITIVE_RESTART,
+   PIPE_CAP_SUPPORTED_PRIM_MODES,
 
    PIPE_CAP_LAST,
    /* XXX do not add caps after PIPE_CAP_LAST! */