gallium: add start_slot parameter to set_vertex_buffers

This allows updating only a subrange of buffer bindings.

set_vertex_buffers(pipe, start_slot, count, NULL) unbinds buffers in that
range. Binding NULL resources unbinds buffers too (both buffer and user_buffer
must be NULL).

The meta ops are adapted to only save, change, and restore the single slot
they use. The cso_context can save and restore only one vertex buffer slot.
The clients can query which one it is using cso_get_aux_vertex_buffer_slot.
It's currently set to 0. (the Draw module breaks if it's set to non-zero)

It should decrease the CPU overhead when using a lot of meta ops, but
the drivers must be able to treat each vertex buffer slot as a separate
state (only r600g does so at the moment).

I can imagine this also being useful for optimizing some OpenGL use cases.

Reviewed-by: Brian Paul <[email protected]>

3 files changed, 12 insertions, 8 deletions

diff --git a/src/gallium/drivers/llvmpipe/lp_draw_arrays.c b/src/gallium/drivers/llvmpipe/lp_draw_arrays.c
index f37b3ca1cea..3497edf9d1c 100644
--- a/src/gallium/drivers/llvmpipe/lp_draw_arrays.c
+++ b/src/gallium/drivers/llvmpipe/lp_draw_arrays.c
@@ -68,8 +68,12 @@ llvmpipe_draw_vbo(struct pipe_context *pipe, const struct pipe_draw_info *info)
     */
    for (i = 0; i < lp->num_vertex_buffers; i++) {
       const void *buf = lp->vertex_buffer[i].user_buffer;
-      if (!buf)
+      if (!buf) {
+         if (!lp->vertex_buffer[i].buffer) {
+            continue;
+         }
          buf = llvmpipe_resource_data(lp->vertex_buffer[i].buffer);
+      }
       draw_set_mapped_vertex_buffer(draw, i, buf);
    }
 
diff --git a/src/gallium/drivers/llvmpipe/lp_state_vertex.c b/src/gallium/drivers/llvmpipe/lp_state_vertex.c
index 4a74cd7c9d4..7594d028b71 100644
--- a/src/gallium/drivers/llvmpipe/lp_state_vertex.c
+++ b/src/gallium/drivers/llvmpipe/lp_state_vertex.c
@@ -33,6 +33,7 @@
 #include "lp_state.h"
 
 #include "draw/draw_context.h"
+#include "util/u_helpers.h"
 #include "util/u_inlines.h"
 #include "util/u_transfer.h"
 
@@ -75,20 +76,20 @@ llvmpipe_delete_vertex_elements_state(struct pipe_context *pipe, void *velems)
 
 static void
 llvmpipe_set_vertex_buffers(struct pipe_context *pipe,
-                            unsigned count,
+                            unsigned start_slot, unsigned count,
                             const struct pipe_vertex_buffer *buffers)
 {
    struct llvmpipe_context *llvmpipe = llvmpipe_context(pipe);
 
    assert(count <= PIPE_MAX_ATTRIBS);
 
-   util_copy_vertex_buffers(llvmpipe->vertex_buffer,
-                            &llvmpipe->num_vertex_buffers,
-                            buffers, count);
+   util_set_vertex_buffers_count(llvmpipe->vertex_buffer,
+                                 &llvmpipe->num_vertex_buffers,
+                                 buffers, start_slot, count);
 
    llvmpipe->dirty |= LP_NEW_VERTEX;
 
-   draw_set_vertex_buffers(llvmpipe->draw, count, buffers);
+   draw_set_vertex_buffers(llvmpipe->draw, start_slot, count, buffers);
 }
 
 
diff --git a/src/gallium/drivers/llvmpipe/lp_surface.c b/src/gallium/drivers/llvmpipe/lp_surface.c
index a4789b4f5c3..e42f4c838e9 100644
--- a/src/gallium/drivers/llvmpipe/lp_surface.c
+++ b/src/gallium/drivers/llvmpipe/lp_surface.c
@@ -204,8 +204,7 @@ static void lp_blit(struct pipe_context *pipe,
 
    /* XXX turn off occlusion and streamout queries */
 
-   util_blitter_save_vertex_buffers(lp->blitter, lp->num_vertex_buffers,
-                                    lp->vertex_buffer);
+   util_blitter_save_vertex_buffer_slot(lp->blitter, lp->vertex_buffer);
    util_blitter_save_vertex_elements(lp->blitter, (void*)lp->velems);
    util_blitter_save_vertex_shader(lp->blitter, (void*)lp->vs);
    util_blitter_save_geometry_shader(lp->blitter, (void*)lp->gs);