[Mesa-dev] [PATCH 2/2] i965: Don't try to continue space before the start of a VBO.

[Eric Anholt]

This loop is trying to see if all the buffers to be uploaded happen to
be the same increment from the start of the 3DSTATE_VERTEX_BUFFERS
currently loaded in the hardware.  However, we might be at a smaller
offset than the previous set of VERTEX_BUFFERS, so we can't reuse
because that packet made the first entry be its starting offset (you
can't access outside the given bounds).

Fixes piglit ARB_vertex_buffer_object/elements-negative-offset.
---
 src/mesa/drivers/dri/i965/brw_draw_upload.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_draw_upload.c b/src/mesa/drivers/dri/i965/brw_draw_upload.c
index 13d3aa7..32a1d29 100644
--- a/src/mesa/drivers/dri/i965/brw_draw_upload.c
+++ b/src/mesa/drivers/dri/i965/brw_draw_upload.c
@@ -500,6 +500,8 @@ static void brw_prepare_vertices(struct brw_context *brw)
 	    break;
 
 	 d = brw->vb.buffers[i].offset - brw->vb.current_buffers[i].offset;
+	 if (d < 0)
+	    break;
 	 if (i == 0)
 	    delta = d / brw->vb.current_buffers[i].stride;
 	 if (delta * brw->vb.current_buffers[i].stride != d)
-- 
1.7.5.3