[Mesa-dev] [PATCH] i965/fs: Drop our dead push constants before overflowing to pull constants.

[Eric Anholt]

The idea of the original order was that you'd dead code eliminate accesses
to push constants.  But I've never seen a case of that (nor has
shader-db), while we frequently see sparse accesses of large constant
arrays that would overflow into pull constants.

Cuts pull constant use on csgo, serious sam, planeshift, and the cave:

total instructions in shared programs: 1695103 -> 1688795 (-0.37%)
instructions in affected programs:     92024 -> 85716 (-6.85%)
GAINED:                                339
LOST:                                  0
---
 src/mesa/drivers/dri/i965/brw_fs.cpp | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index b724dca..4f881ea 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -3065,6 +3065,7 @@ fs_visitor::run()
       split_virtual_grfs();
 
       move_uniform_array_access_to_pull_constants();
+      remove_dead_constants();
       setup_pull_constants();
 
       bool progress;
@@ -3085,8 +3086,6 @@ fs_visitor::run()
 	 progress = compute_to_mrf() || progress;
       } while (progress);
 
-      remove_dead_constants();
-
       schedule_instructions(false);
 
       lower_uniform_pull_constant_loads();
-- 
1.8.4.rc3