[Mesa-dev] [PATCH 1/3] i965: Fix scratch overallocation if the original slot size was already a power of two.

[Francisco Jerez]

The bitwise arithmetic trick used in brw_get_scratch_size() to clamp
the scratch allocation to 1KB has the unintended side effect that it
will cause us to allocate 2x the required amount of scratch space if
the original per-thread scratch size happened to be already a power of
two.  Instead use the obvious MAX2 idiom to clamp the scratch
allocation to the expected range.
---
 src/mesa/drivers/dri/i965/brw_context.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/mesa/drivers/dri/i965/brw_context.h b/src/mesa/drivers/dri/i965/brw_context.h
index 4b22201..daa9ed2 100644
--- a/src/mesa/drivers/dri/i965/brw_context.h
+++ b/src/mesa/drivers/dri/i965/brw_context.h
@@ -1477,7 +1477,7 @@ void brwInitFragProgFuncs( struct dd_function_table *functions );
 static inline int
 brw_get_scratch_size(int size)
 {
-   return util_next_power_of_two(size | 1023);
+   return MAX2(1024, util_next_power_of_two(size));
 }
 void brw_get_scratch_bo(struct brw_context *brw,
 			drm_intel_bo **scratch_bo, int size);
-- 
2.7.3