Mesa (master): ra: note a restriction in the interfence graph API

[Andreas Boll]

Module: Mesa
Branch: master
Commit: ec046bc08ef8ccf69e867635c7d1e2e032acce36
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=ec046bc08ef8ccf69e867635c7d1e2e032acce36

Author: Connor Abbott <cwabbott0 at gmail.com>
Date:   Fri Sep  5 20:59:31 2014 -0400

ra: note a restriction in the interfence graph API

As noted in the previous commit, this was introduced in
567e2769b81863b6dffdac3826a6b729ce6ea37c ("ra: make the p, q test more
efficient"), but I forgot to mention it.

Signed-off-by: Connor Abbott <cwabbott0 at gmail.com>
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>

---

 src/mesa/program/register_allocate.h |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/mesa/program/register_allocate.h b/src/mesa/program/register_allocate.h
index bfc9190..dc68744 100644
--- a/src/mesa/program/register_allocate.h
+++ b/src/mesa/program/register_allocate.h
@@ -56,7 +56,10 @@ void ra_set_finalize(struct ra_regs *regs, unsigned int **conflicts);
  * Each interference graph node is a virtual variable in the IL.  It
  * is up to the user to ra_set_node_class() for the virtual variable,
  * and compute live ranges and ra_node_interfere() between conflicting
- * live ranges.
+ * live ranges. Note that an interference *must not* be added between
+ * two nodes if their classes haven't been assigned yet. The user
+ * should set the class of each node before building the interference
+ * graph.
  */
 struct ra_graph *ra_alloc_interference_graph(struct ra_regs *regs,
 					     unsigned int count);