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, 28 insertions, 29 deletions

diff --git a/src/gallium/drivers/r600/r600_blit.c b/src/gallium/drivers/r600/r600_blit.c
index a19248da3a2..085108d3709 100644
--- a/src/gallium/drivers/r600/r600_blit.c
+++ b/src/gallium/drivers/r600/r600_blit.c
@@ -55,9 +55,7 @@ static void r600_blitter_begin(struct pipe_context *ctx, enum r600_blitter_op op
 
 	r600_suspend_nontimer_queries(rctx);
 
-	util_blitter_save_vertex_buffers(rctx->blitter,
-					 util_last_bit(rctx->vertex_buffer_state.enabled_mask),
-					 rctx->vertex_buffer_state.vb);
+	util_blitter_save_vertex_buffer_slot(rctx->blitter, rctx->vertex_buffer_state.vb);
 	util_blitter_save_vertex_elements(rctx->blitter, rctx->vertex_fetch_shader.cso);
 	util_blitter_save_vertex_shader(rctx->blitter, rctx->vs_shader);
 	util_blitter_save_so_targets(rctx->blitter, rctx->num_so_targets,
diff --git a/src/gallium/drivers/r600/r600_state_common.c b/src/gallium/drivers/r600/r600_state_common.c
index a4d3e461ef1..3503c3964a6 100644
--- a/src/gallium/drivers/r600/r600_state_common.c
+++ b/src/gallium/drivers/r600/r600_state_common.c
@@ -495,41 +495,42 @@ void r600_vertex_buffers_dirty(struct r600_context *rctx)
 	}
 }
 
-static void r600_set_vertex_buffers(struct pipe_context *ctx, unsigned count,
-			     const struct pipe_vertex_buffer *input)
+static void r600_set_vertex_buffers(struct pipe_context *ctx,
+				    unsigned start_slot, unsigned count,
+				    const struct pipe_vertex_buffer *input)
 {
 	struct r600_context *rctx = (struct r600_context *)ctx;
 	struct r600_vertexbuf_state *state = &rctx->vertex_buffer_state;
-	struct pipe_vertex_buffer *vb = state->vb;
+	struct pipe_vertex_buffer *vb = state->vb + start_slot;
 	unsigned i;
-	/* This sets 1-bit for buffers with index >= count. */
-	uint32_t disable_mask = ~((1ull << count) - 1);
+	uint32_t disable_mask = 0;
 	/* These are the new buffers set by this function. */
 	uint32_t new_buffer_mask = 0;
 
-	/* Set buffers with index >= count to NULL. */
-	uint32_t remaining_buffers_mask =
-		rctx->vertex_buffer_state.enabled_mask & disable_mask;
-
-	while (remaining_buffers_mask) {
-		i = u_bit_scan(&remaining_buffers_mask);
-		pipe_resource_reference(&vb[i].buffer, NULL);
-	}
-
 	/* Set vertex buffers. */
-	for (i = 0; i < count; i++) {
-		if (memcmp(&input[i], &vb[i], sizeof(struct pipe_vertex_buffer))) {
-			if (input[i].buffer) {
-				vb[i].stride = input[i].stride;
-				vb[i].buffer_offset = input[i].buffer_offset;
-				pipe_resource_reference(&vb[i].buffer, input[i].buffer);
-				new_buffer_mask |= 1 << i;
-			} else {
-				pipe_resource_reference(&vb[i].buffer, NULL);
-				disable_mask |= 1 << i;
+	if (input) {
+		for (i = 0; i < count; i++) {
+			if (memcmp(&input[i], &vb[i], sizeof(struct pipe_vertex_buffer))) {
+				if (input[i].buffer) {
+					vb[i].stride = input[i].stride;
+					vb[i].buffer_offset = input[i].buffer_offset;
+					pipe_resource_reference(&vb[i].buffer, input[i].buffer);
+					new_buffer_mask |= 1 << i;
+				} else {
+					pipe_resource_reference(&vb[i].buffer, NULL);
+					disable_mask |= 1 << i;
+				}
 			}
 		}
-        }
+	} else {
+		for (i = 0; i < count; i++) {
+			pipe_resource_reference(&vb[i].buffer, NULL);
+		}
+		disable_mask = ((1ull << count) - 1);
+	}
+
+	disable_mask <<= start_slot;
+	new_buffer_mask <<= start_slot;
 
 	rctx->vertex_buffer_state.enabled_mask &= ~disable_mask;
 	rctx->vertex_buffer_state.dirty_mask &= rctx->vertex_buffer_state.enabled_mask;
@@ -1371,7 +1372,7 @@ void r600_draw_rectangle(struct blitter_context *blitter,
 	}
 
 	/* draw */
-	util_draw_vertex_buffer(&rctx->context, NULL, buf, offset,
+	util_draw_vertex_buffer(&rctx->context, NULL, buf, rctx->blitter->vb_slot, offset,
 				R600_PRIM_RECTANGLE_LIST, 3, 2);
 	pipe_resource_reference(&buf, NULL);
 }