[Mesa-dev] [PATCH] st/mesa: cleanup and fix primitive restart for indirect draws

[Nicolai Hähnle]

From: Nicolai Hähnle <nicolai.haehnle at amd.com>

There are three intended functional changes here:

1. OpenGL 4.5 clarifies that primitive restart should only apply with index
   buffers, so make that change explicit in the indirect draw path.

2. Make PrimitiveRestartFixedIndex work with indirect draws.

3. The change where primitive_restart is only set when the restart index can
   actually have an effect (based on the size of indices) is also applied for
   indirect draws.

Cc: 13.0 <mesa-stable at lists.freedesktop.org>
---
 src/mesa/state_tracker/st_draw.c | 45 +++++++++++++++++++++++++---------------
 1 file changed, 28 insertions(+), 17 deletions(-)

diff --git a/src/mesa/state_tracker/st_draw.c b/src/mesa/state_tracker/st_draw.c
index 5dcaff0..e9f25b6 100644
--- a/src/mesa/state_tracker/st_draw.c
+++ b/src/mesa/state_tracker/st_draw.c
@@ -120,20 +120,44 @@ setup_index_buffer(struct st_context *st,
       /* indices are in user space memory */
       ibuffer->user_buffer = ib->ptr;
    }
 
    cso_set_index_buffer(st->cso_context, ibuffer);
    return TRUE;
 }
 
 
 /**
+ * Set the restart index.
+ */
+static void
+setup_primitive_restart(struct gl_context *ctx,
+                        const struct _mesa_index_buffer *ib,
+                        struct pipe_draw_info *info)
+{
+   if (ctx->Array._PrimitiveRestart) {
+      info->restart_index = _mesa_primitive_restart_index(ctx, ib->type);
+
+      /* Enable primitive restart only when the restart index can have an
+       * effect. This is required for correctness in radeonsi VI support.
+       * Other hardware may also benefit from taking a faster, non-restart path
+       * when possible.
+       */
+      if ((ib->type == GL_UNSIGNED_INT) ||
+          (ib->type == GL_UNSIGNED_SHORT && info->restart_index <= 0xffff) ||
+          (ib->type == GL_UNSIGNED_BYTE && info->restart_index <= 0xff))
+         info->primitive_restart = true;
+   }
+}
+
+
+/**
  * Translate OpenGL primtive type (GL_POINTS, GL_TRIANGLE_STRIP, etc) to
  * the corresponding Gallium type.
  */
 static unsigned
 translate_prim(const struct gl_context *ctx, unsigned prim)
 {
    /* GL prims should match Gallium prims, spot-check a few */
    STATIC_ASSERT(GL_POINTS == PIPE_PRIM_POINTS);
    STATIC_ASSERT(GL_QUADS == PIPE_PRIM_QUADS);
    STATIC_ASSERT(GL_TRIANGLE_STRIP_ADJACENCY == PIPE_PRIM_TRIANGLE_STRIP_ADJACENCY);
@@ -198,33 +222,21 @@ st_draw_vbo(struct gl_context *ctx,
 
       info.indexed = TRUE;
       if (min_index != ~0U && max_index != ~0U) {
          info.min_index = min_index;
          info.max_index = max_index;
       }
 
       /* The VBO module handles restart for the non-indexed GLDrawArrays
        * so we only set these fields for indexed drawing:
        */
-      if (ctx->Array._PrimitiveRestart) {
-         info.restart_index = _mesa_primitive_restart_index(ctx, ib->type);
-
-         /* Enable primitive restart only when the restart index can have an
-          * effect. This is required for correctness in radeonsi VI support,
-          * though other hardware may also benefit from taking a faster,
-          * non-restart path when possible.
-          */
-         if ((ibuffer.index_size >= 4) ||
-             (ibuffer.index_size >= 2 && info.restart_index <= 0xffff) ||
-             (info.restart_index <= 0xff))
-            info.primitive_restart = true;
-      }
+      setup_primitive_restart(ctx, ib, &info);
    }
    else {
       /* Transform feedback drawing is always non-indexed. */
       /* Set info.count_from_stream_output. */
       if (tfb_vertcount) {
          if (!st_transform_feedback_draw_init(tfb_vertcount, stream, &info))
             return;
       }
    }
 
@@ -303,31 +315,30 @@ st_indirect_draw_vbo(struct gl_context *ctx,
 
    if (ib) {
       if (!setup_index_buffer(st, ib, &ibuffer)) {
          _mesa_error(ctx, GL_OUT_OF_MEMORY, "gl%sDrawElementsIndirect%s",
                      (draw_count > 1) ? "Multi" : "",
                      indirect_params ? "CountARB" : "");
          return;
       }
 
       info.indexed = TRUE;
+
+      /* Primitive restart is not handled by the VBO module in this case. */
+      setup_primitive_restart(ctx, ib, &info);
    }
 
    info.mode = translate_prim(ctx, mode);
    info.vertices_per_patch = ctx->TessCtrlProgram.patch_vertices;
    info.indirect = st_buffer_object(indirect_data)->buffer;
    info.indirect_offset = indirect_offset;
 
-   /* Primitive restart is not handled by the VBO module in this case. */
-   info.primitive_restart = ctx->Array._PrimitiveRestart;
-   info.restart_index = ctx->Array.RestartIndex;
-
    if (ST_DEBUG & DEBUG_DRAW) {
       debug_printf("st/draw indirect: mode %s drawcount %d indexed %d\n",
                    u_prim_name(info.mode),
                    draw_count,
                    info.indexed);
    }
 
    if (!st->has_multi_draw_indirect) {
       int i;
 
-- 
2.7.4