Mesa (master): i965/fs: Add a comment explaining what saturate propagation does.

[Matt Turner]

Module: Mesa
Branch: master
Commit: 2308b3bef25723b1ebff0b71f2f87dd44050cc2c
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=2308b3bef25723b1ebff0b71f2f87dd44050cc2c

Author: Matt Turner <mattst88 at gmail.com>
Date:   Tue Dec 16 11:30:12 2014 -0800

i965/fs: Add a comment explaining what saturate propagation does.

---

 .../drivers/dri/i965/brw_fs_saturate_propagation.cpp     |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/mesa/drivers/dri/i965/brw_fs_saturate_propagation.cpp b/src/mesa/drivers/dri/i965/brw_fs_saturate_propagation.cpp
index a4145ac..a9966a4 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_saturate_propagation.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_saturate_propagation.cpp
@@ -26,6 +26,20 @@
 #include "brw_cfg.h"
 
 /** @file brw_fs_saturate_propagation.cpp
+ *
+ * Implements a pass that propagates the SAT modifier from a MOV.SAT into the
+ * instruction that produced the source of the MOV.SAT, thereby allowing the
+ * MOV's src and dst to be coalesced and the MOV removed.
+ *
+ * For instance,
+ *
+ *    ADD     tmp, src0, src1
+ *    MOV.SAT dst, tmp
+ *
+ * would be transformed into
+ *
+ *    ADD.SAT tmp, src0, src1
+ *    MOV     dst, tmp
  */
 
 static bool