anv: Disable stencil writes when both write masks are zero

Vulkan doesn't have a stencilWriteEnable bit like it does for depth.
Instead, you have a stencil mask.  Since the stencil mask is handled as
dynamic state, we have to handle it later during command buffer
construction.  This, combined with a later commit, seems to help Dota2
on my Broadwell GT3e desktop by a couple percent because it allows the
hardware to move the depth and stencil writes to early in more cases.

Reviewed-by: Lionel Landwerlin <[email protected]>
Reviewed-by: Nanley Chery <[email protected]>

1 files changed, 8 insertions, 0 deletions

diff --git a/src/intel/vulkan/gen8_cmd_buffer.c b/src/intel/vulkan/gen8_cmd_buffer.c
index ab68872a260..8c8de622eb8 100644
--- a/src/intel/vulkan/gen8_cmd_buffer.c
+++ b/src/intel/vulkan/gen8_cmd_buffer.c
@@ -224,6 +224,10 @@ genX(cmd_buffer_flush_dynamic_state)(struct anv_cmd_buffer *cmd_buffer)
 
          .BackfaceStencilTestMask = d->stencil_compare_mask.back & 0xff,
          .BackfaceStencilWriteMask = d->stencil_write_mask.back & 0xff,
+
+         .StencilBufferWriteEnable =
+            (d->stencil_write_mask.front || d->stencil_write_mask.back) &&
+            pipeline->writes_stencil,
       };
       GENX(3DSTATE_WM_DEPTH_STENCIL_pack)(NULL, wm_depth_stencil_dw,
                                           &wm_depth_stencil);
@@ -271,6 +275,10 @@ genX(cmd_buffer_flush_dynamic_state)(struct anv_cmd_buffer *cmd_buffer)
 
          .StencilReferenceValue = d->stencil_reference.front & 0xff,
          .BackfaceStencilReferenceValue = d->stencil_reference.back & 0xff,
+
+         .StencilBufferWriteEnable =
+            (d->stencil_write_mask.front || d->stencil_write_mask.back) &&
+            pipeline->writes_stencil,
       };
       GEN9_3DSTATE_WM_DEPTH_STENCIL_pack(NULL, dwords, &wm_depth_stencil);