mesa: set pipe_draw_info::index::resource directly and remove gl_bo

The motivation is to remove branching from prepare_indexed_draw
and remove the unsafe hack in vbo_save_playback_vertex_list.

There is some duplication that is not identical in all 3 cases.

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20287>

src/gallium/include/pipe/p_state.h

@@ -55,8 +55,6 @@
 extern "C" {
 #endif
 
-struct gl_buffer_object;
-
 /**
  * Implementation limits
  */
@@ -879,7 +877,6 @@ struct pipe_draw_info
     */
    union {
       struct pipe_resource *resource;  /**< real buffer */
-      struct gl_buffer_object *gl_bo; /**< for the GL frontend, not passed to drivers */
       const void *user;  /**< pointer to a user buffer */
    } index;
 

src/mesa/main/dd.h

@@ -154,7 +154,6 @@ struct dd_function_table {
     * - info->min_index (if index_bounds_valid is false)
     * - info->max_index (if index_bounds_valid is false)
     * - info->drawid (if increment_draw_id is true)
-    * - info->index.gl_bo (if index_size && !has_user_indices)
     */
    void (*DrawGallium)(struct gl_context *ctx,
                        struct pipe_draw_info *info,

src/mesa/main/draw.c

@@ -45,6 +45,7 @@
 
 #include "state_tracker/st_context.h"
 #include "state_tracker/st_draw.h"
+#include "util/u_threaded_context.h"
 
 typedef struct {
    GLuint count;
@@ -1636,14 +1637,23 @@ _mesa_validated_drawrangeelements(struct gl_context *ctx, GLenum mode,
       draw.start = 0;
    } else {
       uintptr_t start = (uintptr_t) indices;
-      if (unlikely(index_bo->Size < start)) {
+      if (unlikely(index_bo->Size < start || !index_bo->buffer)) {
          _mesa_warning(ctx, "Invalid indices offset 0x%" PRIxPTR
-                            " (indices buffer size is %ld bytes)."
+                            " (indices buffer size is %ld bytes)"
-                            " Draw skipped.", start, index_bo->Size);
+                            " or unallocated buffer (%u). Draw skipped.",
+                            start, index_bo->Size, !!index_bo->buffer);
          return;
       }
-      info.index.gl_bo = index_bo;
+
       draw.start = start >> index_size_shift;
+
+      if (ctx->st->pipe->draw_vbo == tc_draw_vbo) {
+         /* Fast path for u_threaded_context to eliminate atomics. */
+         info.index.resource = _mesa_get_bufferobj_reference(ctx, index_bo);
+         info.take_index_buffer_ownership = true;
+      } else {
+         info.index.resource = index_bo->buffer;
+      }
    }
    draw.index_bias = basevertex;
 
@@ -2004,10 +2014,21 @@ _mesa_validated_multidrawelements(struct gl_context *ctx, GLenum mode,
    info.view_mask = 0;
    info.restart_index = ctx->Array._RestartIndex[index_size_shift];
 
-   if (info.has_user_indices)
+   if (info.has_user_indices) {
       info.index.user = (void*)min_index_ptr;
-   else
+   } else {
-      info.index.gl_bo = index_bo;
+      if (ctx->st->pipe->draw_vbo == tc_draw_vbo) {
+         /* Fast path for u_threaded_context to eliminate atomics. */
+         info.index.resource = _mesa_get_bufferobj_reference(ctx, index_bo);
+         info.take_index_buffer_ownership = true;
+      } else {
+         info.index.resource = index_bo->buffer;
+      }
+
+      /* No index buffer storage allocated - nothing to do. */
+      if (!info.index.resource)
+         return;
+   }
 
    if (!fallback &&
        (!info.has_user_indices ||
@@ -2429,11 +2450,24 @@ _mesa_MultiDrawElementsIndirect(GLenum mode, GLenum type,
       /* Packed section end. */
       info.restart_index = ctx->Array._RestartIndex[index_size_shift];
 
+      struct gl_buffer_object *index_bo = ctx->Array.VAO->IndexBufferObj;
+
+      if (ctx->st->pipe->draw_vbo == tc_draw_vbo) {
+         /* Fast path for u_threaded_context to eliminate atomics. */
+         info.index.resource = _mesa_get_bufferobj_reference(ctx, index_bo);
+         info.take_index_buffer_ownership = true;
+      } else {
+         info.index.resource = index_bo->buffer;
+      }
+
+      /* No index buffer storage allocated - nothing to do. */
+      if (!info.index.resource)
+         return;
+
       const uint8_t *ptr = (const uint8_t *) indirect;
       for (unsigned i = 0; i < primcount; i++) {
          DrawElementsIndirectCommand *cmd = (DrawElementsIndirectCommand*)ptr;
 
-         info.index.gl_bo = ctx->Array.VAO->IndexBufferObj;
          info.start_instance = cmd->baseInstance;
          info.instance_count = cmd->primCount;
 

src/mesa/state_tracker/st_draw.c

@@ -127,26 +127,6 @@ prepare_indexed_draw(/* pass both st and ctx to reduce dereferences */
 
          info->index_bounds_valid = true;
       }
-
-      if (!info->has_user_indices) {
-         if (st->pipe->draw_vbo == tc_draw_vbo) {
-            /* Fast path for u_threaded_context. This eliminates the atomic
-             * increment for the index buffer refcount when adding it into
-             * the threaded batch buffer.
-             */
-            info->index.resource =
-               _mesa_get_bufferobj_reference(ctx, info->index.gl_bo);
-            info->take_index_buffer_ownership = true;
-         } else {
-            info->index.resource = info->index.gl_bo->buffer;
-         }
-
-         /* Return if the bound element array buffer doesn't have any backing
-          * storage. (nothing to do)
-          */
-         if (unlikely(!info->index.resource))
-            return false;
-      }
    }
    return true;
 }

src/mesa/state_tracker/st_draw_feedback.c

@@ -173,9 +173,6 @@ st_feedback_draw_vbo(struct gl_context *ctx,
       if (info->has_user_indices) {
          mapped_indices = info->index.user;
       } else {
-         info->index.resource = info->index.gl_bo->buffer;
-         if (!info->index.resource)
-            return; /* glBufferData wasn't called on the buffer */
          mapped_indices = pipe_buffer_map(pipe, info->index.resource,
                                           PIPE_MAP_READ, &ib_transfer);
       }

src/mesa/vbo/vbo_minmax_index.c

@@ -364,6 +364,9 @@ vbo_get_minmax_indices_gallium(struct gl_context *ctx,
    info->min_index = ~0;
    info->max_index = 0;
 
+   struct gl_buffer_object *buf =
+      info->has_user_indices ? NULL : ctx->Array.VAO->IndexBufferObj;
+
    for (unsigned i = 0; i < num_draws; i++) {
       struct pipe_draw_start_count_bias draw = draws[i];
 
@@ -378,8 +381,7 @@ vbo_get_minmax_indices_gallium(struct gl_context *ctx,
          continue;
 
       unsigned tmp_min, tmp_max;
-      vbo_get_minmax_index(ctx, info->has_user_indices ?
+      vbo_get_minmax_index(ctx, buf,
-                              NULL : info->index.gl_bo,
                            info->index.user,
                            (GLintptr)draw.start * info->index_size,
                            draw.count, info->index_size,

src/mesa/vbo/vbo_save_api.c

@@ -881,7 +881,7 @@ compile_vertex_list(struct gl_context *ctx)
    /* The other info fields will be updated in vbo_save_playback_vertex_list */
    node->cold->info.index_size = 4;
    node->cold->info.instance_count = 1;
-   node->cold->info.index.gl_bo = node->cold->ib.obj;
+   node->cold->info.index.resource = node->cold->ib.obj->buffer;
    if (merged_prim_count == 1) {
       node->cold->info.mode = merged_prims[0].mode;
       node->start_count.start = merged_prims[0].start;

src/mesa/vbo/vbo_save_draw.c

@@ -343,7 +343,7 @@ vbo_save_playback_vertex_list(struct gl_context *ctx, void *data, bool copy_to_c
    assert(ctx->NewState == 0);
 
    struct pipe_draw_info *info = (struct pipe_draw_info *) &node->cold->info;
-   void *gl_bo = info->index.gl_bo;
+
    if (node->modes) {
       ctx->Driver.DrawGalliumMultiMode(ctx, info,
                                        node->start_counts,
@@ -355,7 +355,6 @@ vbo_save_playback_vertex_list(struct gl_context *ctx, void *data, bool copy_to_c
       ctx->Driver.DrawGallium(ctx, info, 0, node->start_counts,
                               node->num_draws);
    }
-   info->index.gl_bo = gl_bo;
 
    _mesa_restore_draw_vao(ctx, old_vao, old_vp_input_filter);