Mesa (master): i965: Only enable depth IZ signals if there's an actual depthbuffer.

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Module: Mesa
Branch: master
Commit: 11b9f63a7403225c75de07a658a71063bde99ac9
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=11b9f63a7403225c75de07a658a71063bde99ac9

Author: Kenneth Graunke <kenneth at whitecape.org>
Date:   Thu Aug  2 11:31:27 2018 -0700

i965: Only enable depth IZ signals if there's an actual depthbuffer.

According to the G45 PRM Volume 2 Page 265 we're supposed to only set
these signals when there is an actual depth buffer.  Note that we
already do this for the stencil buffer by virtue of brw->stencil_enabled
invoking _mesa_is_stencil_enabled(ctx) which checks whether the current
drawbuffer's visual has stencil bits (which is updated based on what
buffers are bound).  We just need to do it for depth as well.

Not observed to fix anything.

Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>

---

 src/mesa/drivers/dri/i965/brw_wm.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_wm.c b/src/mesa/drivers/dri/i965/brw_wm.c
index 70fe384444..db632ed15e 100644
--- a/src/mesa/drivers/dri/i965/brw_wm.c
+++ b/src/mesa/drivers/dri/i965/brw_wm.c
@@ -35,6 +35,7 @@
 #include "program/program.h"
 #include "intel_mipmap_tree.h"
 #include "intel_image.h"
+#include "intel_fbo.h"
 #include "compiler/brw_nir.h"
 #include "brw_program.h"
 
@@ -456,6 +457,9 @@ brw_wm_populate_key(struct brw_context *brw, struct brw_wm_prog_key *key)
    /* Build the index for table lookup
     */
    if (devinfo->gen < 6) {
+      struct intel_renderbuffer *depth_irb =
+         intel_get_renderbuffer(ctx->DrawBuffer, BUFFER_DEPTH);
+
       /* _NEW_COLOR */
       if (prog->info.fs.uses_discard || ctx->Color.AlphaEnabled) {
          lookup |= BRW_WM_IZ_PS_KILL_ALPHATEST_BIT;
@@ -466,11 +470,12 @@ brw_wm_populate_key(struct brw_context *brw, struct brw_wm_prog_key *key)
       }
 
       /* _NEW_DEPTH */
-      if (ctx->Depth.Test)
+      if (depth_irb && ctx->Depth.Test) {
          lookup |= BRW_WM_IZ_DEPTH_TEST_ENABLE_BIT;
 
-      if (brw_depth_writes_enabled(brw))
-         lookup |= BRW_WM_IZ_DEPTH_WRITE_ENABLE_BIT;
+         if (brw_depth_writes_enabled(brw))
+            lookup |= BRW_WM_IZ_DEPTH_WRITE_ENABLE_BIT;
+      }
 
       /* _NEW_STENCIL | _NEW_BUFFERS */
       if (brw->stencil_enabled) {