i915g: Make sure that new vbo gets updated

Malloc likes to reuse old address as soon as possible this would cause the
new vbo buffer to get the same address as the old. So make sure we set it to
NULL when we allocate a new one. This fixes ipers which will fill up a couple
of VBO buffers per frame.

Signed-off-by: Jakob Bornecrantz <wallbraker@gmail.com>

src/gallium/drivers/i915/TODO

@@ -18,10 +18,6 @@ Random list of problems with i915g:
   Texture sampling from Y-tiled buffers seems to work, though (save above
   problems).
 
-- Review buffer usage/cache domain handling in the winsys. Related: vbo cache
-  coherency is bunk: openarena tends to have a bunch of flatshaded triangles
-  popping up all over the screen.
-
 - Need to validate buffers before usage. Currently do_exec on the batchbuffer
   can fail with -ENOSPC.
 

src/gallium/drivers/i915/i915_prim_vbuf.c

@@ -172,6 +172,7 @@ i915_vbuf_render_reserve(struct i915_vbuf_render *i915_render, size_t size)
  *
  * Side effects:
  *    Updates hw_offset, sw_offset, index and allocates a new buffer.
+ *    Will set i915->vbo to null on buffer allocation.
  */
 static void
 i915_vbuf_render_new_buf(struct i915_vbuf_render *i915_render, size_t size)
@@ -179,8 +180,16 @@ i915_vbuf_render_new_buf(struct i915_vbuf_render *i915_render, size_t size)
    struct i915_context *i915 = i915_render->i915;
    struct i915_winsys *iws = i915->iws;
 
-   if (i915_render->vbo)
+   if (i915_render->vbo) {
       iws->buffer_destroy(iws, i915_render->vbo);
+      /*
+       * XXX If buffers where referenced then this should be done in
+       * update_vbo_state but since they arn't and malloc likes to reuse
+       * memory we need to set it to null
+       */
+      i915->vbo = NULL;
+      i915_render->vbo = NULL;
+   }
 
    i915->vbo_flushed = 0;