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 <brianp@vmware.com>

3 files changed, 13 insertions, 15 deletions

diff --git a/src/gallium/drivers/r300/r300_blit.c b/src/gallium/drivers/r300/r300_blit.c
index 96c96c3..651ea85 100644
--- a/src/gallium/drivers/r300/r300_blit.c
+++ b/src/gallium/drivers/r300/r300_blit.c
@@ -66,8 +66,7 @@ static void r300_blitter_begin(struct r300_context* r300, enum r300_blitter_op o
     util_blitter_save_vertex_shader(r300->blitter, r300->vs_state.state);
     util_blitter_save_viewport(r300->blitter, &r300->viewport);
     util_blitter_save_scissor(r300->blitter, r300->scissor_state.state);
-    util_blitter_save_vertex_buffers(r300->blitter, r300->nr_vertex_buffers,
-                                     r300->vertex_buffer);
+    util_blitter_save_vertex_buffer_slot(r300->blitter, r300->vertex_buffer);
     util_blitter_save_vertex_elements(r300->blitter, r300->velems);
 
     if (op & R300_SAVE_FRAMEBUFFER) {
diff --git a/src/gallium/drivers/r300/r300_render.c b/src/gallium/drivers/r300/r300_render.c
index 198ab73..46d7ea1 100644
--- a/src/gallium/drivers/r300/r300_render.c
+++ b/src/gallium/drivers/r300/r300_render.c
@@ -1191,8 +1191,6 @@ void r300_blitter_draw_rectangle(struct blitter_context *blitter,
     if (r300->skip_rendering)
         return;
 
-    r300->context.set_vertex_buffers(&r300->context, 0, NULL);
-
     if (type == UTIL_BLITTER_ATTRIB_TEXCOORD)
         r300->sprite_coord_enable = 1;
 
diff --git a/src/gallium/drivers/r300/r300_state.c b/src/gallium/drivers/r300/r300_state.c
index b43f330..85d05bd 100644
--- a/src/gallium/drivers/r300/r300_state.c
+++ b/src/gallium/drivers/r300/r300_state.c
@@ -25,6 +25,7 @@
 
 #include "util/u_framebuffer.h"
 #include "util/u_half.h"
+#include "util/u_helpers.h"
 #include "util/u_math.h"
 #include "util/u_mm.h"
 #include "util/u_memory.h"
@@ -1626,7 +1627,7 @@ static void r300_set_viewport_state(struct pipe_context* pipe,
 }
 
 static void r300_set_vertex_buffers_hwtcl(struct pipe_context* pipe,
-                                    unsigned count,
+                                    unsigned start_slot, unsigned count,
                                     const struct pipe_vertex_buffer* buffers)
 {
     struct r300_context* r300 = r300_context(pipe);
@@ -1637,31 +1638,31 @@ static void r300_set_vertex_buffers_hwtcl(struct pipe_context* pipe,
         count = 1;
     }
 
-    util_copy_vertex_buffers(r300->vertex_buffer,
-                             &r300->nr_vertex_buffers,
-                             buffers, count);
+    util_set_vertex_buffers_count(r300->vertex_buffer,
+                                  &r300->nr_vertex_buffers,
+                                  buffers, start_slot, count);
 
     r300->vertex_arrays_dirty = TRUE;
 }
 
 static void r300_set_vertex_buffers_swtcl(struct pipe_context* pipe,
-                                    unsigned count,
+                                    unsigned start_slot, unsigned count,
                                     const struct pipe_vertex_buffer* buffers)
 {
     struct r300_context* r300 = r300_context(pipe);
     unsigned i;
 
-    util_copy_vertex_buffers(r300->vertex_buffer,
-                             &r300->nr_vertex_buffers,
-                             buffers, count);
-    draw_set_vertex_buffers(r300->draw, count, buffers);
+    util_set_vertex_buffers_count(r300->vertex_buffer,
+                                  &r300->nr_vertex_buffers,
+                                  buffers, start_slot, count);
+    draw_set_vertex_buffers(r300->draw, start_slot, count, buffers);
 
     for (i = 0; i < count; i++) {
         if (buffers[i].user_buffer) {
-            draw_set_mapped_vertex_buffer(r300->draw, i,
+            draw_set_mapped_vertex_buffer(r300->draw, start_slot + i,
                                           buffers[i].user_buffer);
         } else if (buffers[i].buffer) {
-            draw_set_mapped_vertex_buffer(r300->draw, i,
+            draw_set_mapped_vertex_buffer(r300->draw, start_slot + i,
                 r300_resource(buffers[i].buffer)->malloced_buffer);
         }
     }