[Lima] [PATCH 4/9] gallium: add a cap to force compute minmax indices

[Qiang Yu]

From: Erico Nunes <nunes.erico at gmail.com>

pipe_draw_info has min_index and max_index fields that can be useful in
indexed drawing, however gallium may decide to not compute them in some
cases to avoid impacting performance if the driver won't need them.
However, some drivers may need to always compute these values to build a
valid command stream for indexed draw.
Instead of reimplementing this functionality or having to explicitly
compute those in driver specific code, this new cap can be used to
ensure that gallium will not skip the computation.
Drivers that set this cap will be able to rely on those values to build
the command stream.

For more details on this patch:
https://lists.freedesktop.org/archives/mesa-dev/2018-March/189251.html

Signed-off-by: Erico Nunes <nunes.erico at gmail.com>
---
 src/gallium/auxiliary/util/u_screen.c | 3 +++
 src/gallium/include/pipe/p_defines.h  | 1 +
 src/mesa/state_tracker/st_draw.c      | 5 ++++-
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/gallium/auxiliary/util/u_screen.c b/src/gallium/auxiliary/util/u_screen.c
index 50964f3b3ef..e8fbdf56e2f 100644
--- a/src/gallium/auxiliary/util/u_screen.c
+++ b/src/gallium/auxiliary/util/u_screen.c
@@ -341,6 +341,9 @@ u_pipe_screen_get_param_defaults(struct pipe_screen *pscreen,
    case PIPE_CAP_MAX_VARYINGS:
       return 8;
 
+   case PIPE_CAP_FORCE_COMPUTE_MINMAX_INDICES:
+      return 0;
+
    default:
       unreachable("bad PIPE_CAP_*");
    }
diff --git a/src/gallium/include/pipe/p_defines.h b/src/gallium/include/pipe/p_defines.h
index e2b0104ce43..495ba88e521 100644
--- a/src/gallium/include/pipe/p_defines.h
+++ b/src/gallium/include/pipe/p_defines.h
@@ -858,6 +858,7 @@ enum pipe_cap
    PIPE_CAP_DEST_SURFACE_SRGB_CONTROL,
    PIPE_CAP_NIR_COMPACT_ARRAYS,
    PIPE_CAP_MAX_VARYINGS,
+   PIPE_CAP_FORCE_COMPUTE_MINMAX_INDICES,
 };
 
 /**
diff --git a/src/mesa/state_tracker/st_draw.c b/src/mesa/state_tracker/st_draw.c
index 7485fc82b18..501c09817c0 100644
--- a/src/mesa/state_tracker/st_draw.c
+++ b/src/mesa/state_tracker/st_draw.c
@@ -195,9 +195,12 @@ st_draw_vbo(struct gl_context *ctx,
 
    if (ib) {
       struct gl_buffer_object *bufobj = ib->obj;
+      struct pipe_screen *screen = st->pipe->screen;
+      bool needs_minmax_index = st->draw_needs_minmax_index ||
+         screen->get_param(screen, PIPE_CAP_FORCE_COMPUTE_MINMAX_INDICES);
 
       /* Get index bounds for user buffers. */
-      if (!index_bounds_valid && st->draw_needs_minmax_index) {
+      if (!index_bounds_valid && needs_minmax_index) {
          vbo_get_minmax_indices(ctx, prims, ib, &min_index, &max_index,
                                 nr_prims);
       }
-- 
2.17.1