gallium: add pipe_vertex_state and draw_vertex_state for display lists

The main motivation is to improve the score of viewperf13/snx.

This new interface is designed to be optimal for display lists as implemented
by the vbo module. It has much lower CPU overhead in the frontend, threaded
context, and the driver.

Reviewed-By: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13050>

src/gallium/include/pipe/p_state.h

@@ -708,6 +708,39 @@ struct pipe_vertex_element
    unsigned instance_divisor;
 };
 
+/**
+ * Opaque refcounted constant state object encapsulating a vertex buffer,
+ * index buffer, and vertex elements. Used by display lists to bind those
+ * states and pass buffer references quickly.
+ *
+ * The state contains 1 index buffer, 0 or 1 vertex buffer, and 0 or more
+ * vertex elements.
+ *
+ * Constraints on the buffers to get the fastest codepath:
+ * - All buffer contents are considered immutable and read-only after
+ *   initialization. This implies the following things.
+ * - No place is required to track whether these buffers are busy.
+ * - All CPU mappings of these buffers can be forced to UNSYNCHRONIZED by
+ *   both drivers and common code unconditionally.
+ * - Buffer invalidation can be skipped by both drivers and common code
+ *   unconditionally.
+ */
+struct pipe_vertex_state {
+   struct pipe_reference reference;
+   struct pipe_screen *screen;
+
+   /* The following structure is used as a key for util_vertex_state_cache
+    * to deduplicate identical state objects and thus enable more
+    * opportunities for draw merging.
+    */
+   struct {
+      struct pipe_resource *indexbuf;
+      struct pipe_vertex_buffer vbuffer;
+      unsigned num_elements;
+      struct pipe_vertex_element elements[PIPE_MAX_ATTRIBS];
+      uint32_t full_velem_mask;
+   } input;
+};
 
 struct pipe_draw_indirect_info
 {
@@ -766,6 +799,25 @@ struct pipe_draw_start_count_bias {
    int index_bias; /**< a bias to be added to each index */
 };
 
+/**
+ * Draw vertex state description. It's translated to pipe_draw_info as follows:
+ * - mode comes from this structure
+ * - index_size is 4
+ * - instance_count is 1
+ * - index.resource comes from pipe_vertex_state
+ * - everything else is 0
+ */
+struct pipe_draw_vertex_state_info {
+#if defined(__GNUC__)
+   /* sizeof(mode) == 1 because it's a packed enum. */
+   enum pipe_prim_type mode;  /**< the mode of the primitive */
+#else
+   /* sizeof(mode) == 1 is required by draw merging in u_threaded_context. */
+   uint8_t mode;              /**< the mode of the primitive */
+#endif
+   bool take_vertex_state_ownership; /**< for skipping reference counting */
+};
+
 /**
  * Information to describe a draw_vbo call.
  */