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 50%, and Bay Trail (at 1366x768) by over 70% (using Chrome 24).

v2: Use _mesa_format_has_color_component() to properly handle ALPHA
    formats (and generally be less fragile).

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Tested-by: Dylan Baker <baker.dylan.c@gmail.com>

diff --git a/src/mesa/drivers/dri/i965/brw_blorp_clear.cpp b/src/mesa/drivers/dri/i965/brw_blorp_clear.cpp
index 3c6c57beda8e8c644e239ce6c56b9c54f171b8da..fd18b45202ffe7bb1bb7ffc139fee6a896150634 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_blorp_clear.cpp
+++ b/src/mesa/drivers/dri/i965/brw_blorp_clear.cpp
@@ -231,7 +231,8 @@ brw_blorp_clear_params::brw_blorp_clear_params(struct brw_context *brw,
     * state.  This is not documented.
     */
    for (int i = 0; i < 4; i++) {
-      if (!color_mask[i]) {
+      if (_mesa_format_has_color_component(irb->mt->format, i) &&
+          !color_mask[i]) {
          color_write_disable[i] = true;
          wm_prog_key.use_simd16_replicated_data = false;
       }