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]>

1 files changed, 2 insertions, 2 deletions

diff --git a/src/gallium/drivers/galahad/glhd_context.c b/src/gallium/drivers/galahad/glhd_context.c
index 3400a4d213a..ecdfe068f79 100644
--- a/src/gallium/drivers/galahad/glhd_context.c
+++ b/src/gallium/drivers/galahad/glhd_context.c
@@ -621,7 +621,7 @@ galahad_context_set_fragment_sampler_views(struct pipe_context *_pipe,
 
 static void
 galahad_context_set_vertex_buffers(struct pipe_context *_pipe,
-                            unsigned num_buffers,
+                            unsigned start_slot, unsigned num_buffers,
                             const struct pipe_vertex_buffer *_buffers)
 {
    struct galahad_context *glhd_pipe = galahad_context(_pipe);
@@ -638,7 +638,7 @@ galahad_context_set_vertex_buffers(struct pipe_context *_pipe,
    }
 
    pipe->set_vertex_buffers(pipe,
-                            num_buffers,
+                            start_slot, num_buffers,
                             buffers);
 }