Mesa (master): i965: For color clears, only disable writes to components that exist.

[Kenneth Graunke]

Module: Mesa
Branch: master
Commit: 2919c3fdb40cf457f2e47f378a46f4cefa9e9f6d
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=2919c3fdb40cf457f2e47f378a46f4cefa9e9f6d

Author: Kenneth Graunke <kenneth at whitecape.org>
Date:   Fri Mar 21 03:47:16 2014 -0700

i965: For color clears, only disable writes to components that exist.

The SIMD16 replicated FB write message only works if we don't need the
color calculator to mask our framebuffer writes.  Previously, we bailed
on it if color_mask wasn't <true, true, true, true>.  However, this was
needlessly strict for formats with fewer than four components - only the
components that actually exist matter.

WebGL Aquarium attempts to clear a BGRX texture with the ColorMask set
to <true, true, true, false>.  This will work perfectly fine with the
replicated data message; we just bailed unnecessarily.

Improves performance of WebGL Aquarium on Iris Pro (at 1920x1080) by
abound 40%, and Bay Trail (at 1366x768) by over 70% (using Chrome 24).

Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
Reviewed-by: Anuj Phogat <anuj.phogat at gmail.com>
Reviewed-by: Paul Berry <stereotype441 at gmail.com>
Tested-by: Dylan Baker <baker.dylan.c at gmail.com>

---

 src/mesa/drivers/dri/i965/brw_blorp_clear.cpp |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/mesa/drivers/dri/i965/brw_blorp_clear.cpp b/src/mesa/drivers/dri/i965/brw_blorp_clear.cpp
index 76f8299..433f63e 100644
--- a/src/mesa/drivers/dri/i965/brw_blorp_clear.cpp
+++ b/src/mesa/drivers/dri/i965/brw_blorp_clear.cpp
@@ -231,7 +231,7 @@ brw_blorp_clear_params::brw_blorp_clear_params(struct brw_context *brw,
    /* Constant color writes ignore everyting in blend and color calculator
     * state.  This is not documented.
     */
-   for (int i = 0; i < 4; i++) {
+   for (int i = 0; i < _mesa_format_num_components(irb->mt->format); i++) {
       if (!color_mask[i]) {
          color_write_disable[i] = true;
          wm_prog_key.use_simd16_replicated_data = false;