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/softpipe/sp_draw_arrays.c b/src/gallium/drivers/softpipe/sp_draw_arrays.c
index 59226fb9c15..ba9e7817ceb 100644
--- a/src/gallium/drivers/softpipe/sp_draw_arrays.c
+++ b/src/gallium/drivers/softpipe/sp_draw_arrays.c
@@ -76,8 +76,12 @@ softpipe_draw_vbo(struct pipe_context *pipe,
    /* Map vertex buffers */
    for (i = 0; i < sp->num_vertex_buffers; i++) {
       const void *buf = sp->vertex_buffer[i].user_buffer;
-      if (!buf)
+      if (!buf) {
+         if (!sp->vertex_buffer[i].buffer) {
+            continue;
+         }
          buf = softpipe_resource(sp->vertex_buffer[i].buffer)->data;
+      }
       draw_set_mapped_vertex_buffer(draw, i, buf);
    }
 
diff --git a/src/gallium/drivers/softpipe/sp_state_vertex.c b/src/gallium/drivers/softpipe/sp_state_vertex.c
index 95acecd3be4..2aee700fec2 100644
--- a/src/gallium/drivers/softpipe/sp_state_vertex.c
+++ b/src/gallium/drivers/softpipe/sp_state_vertex.c
@@ -33,6 +33,7 @@
 #include "sp_state.h"
 
 #include "util/u_memory.h"
+#include "util/u_helpers.h"
 #include "util/u_inlines.h"
 #include "util/u_transfer.h"
 #include "draw/draw_context.h"
@@ -79,20 +80,20 @@ softpipe_delete_vertex_elements_state(struct pipe_context *pipe, void *velems)
 
 static void
 softpipe_set_vertex_buffers(struct pipe_context *pipe,
-                            unsigned count,
+                            unsigned start_slot, unsigned count,
                             const struct pipe_vertex_buffer *buffers)
 {
    struct softpipe_context *softpipe = softpipe_context(pipe);
 
    assert(count <= PIPE_MAX_ATTRIBS);
 
-   util_copy_vertex_buffers(softpipe->vertex_buffer,
-                            &softpipe->num_vertex_buffers,
-                            buffers, count);
+   util_set_vertex_buffers_count(softpipe->vertex_buffer,
+                                 &softpipe->num_vertex_buffers,
+                                 buffers, start_slot, count);
 
    softpipe->dirty |= SP_NEW_VERTEX;
 
-   draw_set_vertex_buffers(softpipe->draw, count, buffers);
+   draw_set_vertex_buffers(softpipe->draw, start_slot, count, buffers);
 }
 
 
diff --git a/src/gallium/drivers/softpipe/sp_surface.c b/src/gallium/drivers/softpipe/sp_surface.c
index bb143f4cb3a..911c34df1b8 100644
--- a/src/gallium/drivers/softpipe/sp_surface.c
+++ b/src/gallium/drivers/softpipe/sp_surface.c
@@ -56,8 +56,7 @@ static void sp_blit(struct pipe_context *pipe,
 
    /* XXX turn off occlusion and streamout queries */
 
-   util_blitter_save_vertex_buffers(sp->blitter, sp->num_vertex_buffers,
-                                    sp->vertex_buffer);
+   util_blitter_save_vertex_buffer_slot(sp->blitter, sp->vertex_buffer);
    util_blitter_save_vertex_elements(sp->blitter, sp->velems);
    util_blitter_save_vertex_shader(sp->blitter, sp->vs);
    util_blitter_save_geometry_shader(sp->blitter, sp->gs);