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]>

2 files changed, 7 insertions, 7 deletions

diff --git a/src/gallium/drivers/i915/i915_state.c b/src/gallium/drivers/i915/i915_state.c
index d96ac7ab938..7fa648fc4d9 100644
--- a/src/gallium/drivers/i915/i915_state.c
+++ b/src/gallium/drivers/i915/i915_state.c
@@ -30,6 +30,7 @@
 
 
 #include "draw/draw_context.h"
+#include "util/u_helpers.h"
 #include "util/u_inlines.h"
 #include "util/u_math.h"
 #include "util/u_memory.h"
@@ -926,19 +927,18 @@ static void i915_delete_rasterizer_state(struct pipe_context *pipe,
 }
 
 static void i915_set_vertex_buffers(struct pipe_context *pipe,
-                                    unsigned count,
+                                    unsigned start_slot, unsigned count,
                                     const struct pipe_vertex_buffer *buffers)
 {
    struct i915_context *i915 = i915_context(pipe);
    struct draw_context *draw = i915->draw;
 
-   util_copy_vertex_buffers(i915->vertex_buffers,
-                            &i915->nr_vertex_buffers,
-                            buffers, count);
+   util_set_vertex_buffers_count(i915->vertex_buffers,
+                                 &i915->nr_vertex_buffers,
+                                 buffers, start_slot, count);
 
    /* pass-through to draw module */
-   draw_set_vertex_buffers(draw, count, buffers);
-
+   draw_set_vertex_buffers(draw, start_slot, count, buffers);
 }
 
 static void *
diff --git a/src/gallium/drivers/i915/i915_surface.c b/src/gallium/drivers/i915/i915_surface.c
index 331d6e230d0..08a6f343922 100644
--- a/src/gallium/drivers/i915/i915_surface.c
+++ b/src/gallium/drivers/i915/i915_surface.c
@@ -55,7 +55,7 @@ i915_util_blitter_save_states(struct i915_context *i915)
    util_blitter_save_viewport(i915->blitter, &i915->viewport);
    util_blitter_save_scissor(i915->blitter, &i915->scissor);
    util_blitter_save_vertex_elements(i915->blitter, i915->velems);
-   util_blitter_save_vertex_buffers(i915->blitter, i915->nr_vertex_buffers,
+   util_blitter_save_vertex_buffer_slot(i915->blitter,
                                     i915->vertex_buffers);
 
    util_blitter_save_framebuffer(i915->blitter, &i915->framebuffer);