Mesa (master): vbo: Try to reuse the same VAO more often for successive dlists.

[Mathias Fröhlich]

Module: Mesa
Branch: master
Commit: 411aa8c322f6703b20d32c7c263fd7ea8639cf3f
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=411aa8c322f6703b20d32c7c263fd7ea8639cf3f

Author: Mathias Fröhlich <mathias.froehlich at web.de>
Date:   Wed Feb 28 08:31:44 2018 +0100

vbo: Try to reuse the same VAO more often for successive dlists.

The change tries to catch more opportunities to reuse the same set
of VAO's when building up display lists. Instead of checking the
offset with respect to the beginning of the vertex buffer object
the change tries to apply this same optimization with respect to the
previous display list node.

Reviewed-by: Brian Paul <brianp at vmware.com>
Signed-off-by: Mathias Fröhlich <Mathias.Froehlich at web.de>

---

 src/mesa/vbo/vbo_save_api.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/src/mesa/vbo/vbo_save_api.c b/src/mesa/vbo/vbo_save_api.c
index 47ee355e72..9dd9c7d7d2 100644
--- a/src/mesa/vbo/vbo_save_api.c
+++ b/src/mesa/vbo/vbo_save_api.c
@@ -542,11 +542,18 @@ compile_vertex_list(struct gl_context *ctx)
 
    /* Duplicate our template, increment refcounts to the storage structs:
     */
+   GLintptr old_offset = 0;
+   if (save->VAO[0]) {
+      old_offset = save->VAO[0]->BufferBinding[0].Offset
+         + save->VAO[0]->VertexAttrib[VERT_ATTRIB_POS].RelativeOffset;
+   }
    const GLsizei stride = save->vertex_size*sizeof(GLfloat);
    GLintptr buffer_offset =
        (save->buffer_map - save->vertex_store->buffer_map) * sizeof(GLfloat);
+   assert(old_offset <= buffer_offset);
+   const GLintptr offset_diff = buffer_offset - old_offset;
    GLuint start_offset = 0;
-   if (0 < buffer_offset && 0 < stride && buffer_offset % stride == 0) {
+   if (offset_diff > 0 && stride > 0 && offset_diff % stride == 0) {
       /* The vertex size is an exact multiple of the buffer offset.
        * This means that we can use zero-based vertex attribute pointers
        * and specify the start of the primitive with the _mesa_prim::start
@@ -558,8 +565,9 @@ compile_vertex_list(struct gl_context *ctx)
       /* We cannot immediately update the primitives as some methods below
        * still need the uncorrected start vertices
        */
-      start_offset = buffer_offset/stride;
-      buffer_offset = 0;
+      start_offset = offset_diff/stride;
+      assert(old_offset == buffer_offset - offset_diff);
+      buffer_offset = old_offset;
    }
    GLuint offsets[VBO_ATTRIB_MAX];
    for (unsigned i = 0, offset = 0; i < VBO_ATTRIB_MAX; ++i) {
@@ -666,6 +674,9 @@ compile_vertex_list(struct gl_context *ctx)
        */
       free_vertex_store(ctx, save->vertex_store);
       save->vertex_store = NULL;
+      /* When we have a new vbo, we will for sure need a new vao */
+      for (gl_vertex_processing_mode vpm = 0; vpm < VP_MODE_MAX; ++vpm)
+         _mesa_reference_vao(ctx, &save->VAO[vpm], NULL);
 
       /* Allocate and map new store:
        */