Mesa (master): vc4: Colormask should apply after all other fragment ops ( like logic op).

[Eric Anholt]

Module: Mesa
Branch: master
Commit: 6313a2c8f074e6876df56881eebb4be8690d8c41
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=6313a2c8f074e6876df56881eebb4be8690d8c41

Author: Eric Anholt <eric at anholt.net>
Date:   Mon Jan 12 14:53:48 2015 +1300

vc4: Colormask should apply after all other fragment ops (like logic op).

Theoretically it should apply after dithering as well, but ditehring for
565 happens in fixed function in the TLB store.

---

 src/gallium/drivers/vc4/vc4_program.c |   27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/src/gallium/drivers/vc4/vc4_program.c b/src/gallium/drivers/vc4/vc4_program.c
index ff2bdf2..0fa43e2 100644
--- a/src/gallium/drivers/vc4/vc4_program.c
+++ b/src/gallium/drivers/vc4/vc4_program.c
@@ -1804,15 +1804,6 @@ emit_frag_end(struct vc4_compile *c)
                         blend_color[i] = qir_srgb_encode(c, blend_color[i]);
         }
 
-        /* If the bit isn't set in the color mask, then just return the
-         * original dst color, instead.
-         */
-        for (int i = 0; i < 4; i++) {
-                if (!(c->fs_key->blend.colormask & (1 << i))) {
-                        blend_color[i] = dst_color[i];
-                }
-        }
-
         /* Debug: Sometimes you're getting a black output and just want to see
          * if the FS is getting executed at all.  Spam magenta into the color
          * output.
@@ -1875,6 +1866,24 @@ emit_frag_end(struct vc4_compile *c)
                 packed_color = vc4_logicop(c, packed_color, packed_dst_color);
         }
 
+        /* If the bit isn't set in the color mask, then just return the
+         * original dst color, instead.
+         */
+        uint32_t colormask = 0xffffffff;
+        for (int i = 0; i < 4; i++) {
+                if (format_swiz[i] < 4 &&
+                    !(c->fs_key->blend.colormask & (1 << format_swiz[i]))) {
+                        colormask &= ~(0xff << (i * 8));
+                }
+        }
+        if (colormask != 0xffffffff) {
+                packed_color = qir_OR(c,
+                                      qir_AND(c, packed_color,
+                                              qir_uniform_ui(c, colormask)),
+                                      qir_AND(c, packed_dst_color,
+                                              qir_uniform_ui(c, ~colormask)));
+        }
+
         qir_emit(c, qir_inst(QOP_TLB_COLOR_WRITE, c->undef,
                              packed_color, c->undef));
 }