[Mesa-dev] [PATCH] anv: Take write mask into account in has_color_buffer_write_enabled

[Alex Smith]

If we have a color attachment, but its writes are masked, this would
have still returned true. This is inconsistent with how HasWriteableRT
in 3DSTATE_PS_BLEND is set, which does take the mask into account.

This could lead to PixelShaderHasUAV not being set in 3DSTATE_PS_EXTRA
if the fragment shader does use UAVs, meaning the fragment shader may
not be invoked because HasWriteableRT is false. Specifically, this was
seen to occur when the shader also enables early fragment tests: the
fragment shader was not invoked despite passing depth/stencil.

Fix by taking the color write mask into account in this function. This
is consistent with how things are done on i965.

Signed-off-by: Alex Smith <asmith at feralinteractive.com>
Cc: mesa-stable at lists.freedesktop.org
---
 src/intel/vulkan/genX_pipeline.c | 27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/src/intel/vulkan/genX_pipeline.c b/src/intel/vulkan/genX_pipeline.c
index 0ae9ead587..cfc3bea426 100644
--- a/src/intel/vulkan/genX_pipeline.c
+++ b/src/intel/vulkan/genX_pipeline.c
@@ -1330,7 +1330,8 @@ emit_3dstate_gs(struct anv_pipeline *pipeline)
 }
 
 static bool
-has_color_buffer_write_enabled(const struct anv_pipeline *pipeline)
+has_color_buffer_write_enabled(const struct anv_pipeline *pipeline,
+                               const VkPipelineColorBlendStateCreateInfo *blend)
 {
    const struct anv_shader_bin *shader_bin =
       pipeline->shaders[MESA_SHADER_FRAGMENT];
@@ -1339,10 +1340,15 @@ has_color_buffer_write_enabled(const struct anv_pipeline *pipeline)
 
    const struct anv_pipeline_bind_map *bind_map = &shader_bin->bind_map;
    for (int i = 0; i < bind_map->surface_count; i++) {
-      if (bind_map->surface_to_descriptor[i].set !=
-          ANV_DESCRIPTOR_SET_COLOR_ATTACHMENTS)
+      struct anv_pipeline_binding *binding = &bind_map->surface_to_descriptor[i];
+
+      if (binding->set != ANV_DESCRIPTOR_SET_COLOR_ATTACHMENTS)
          continue;
-      if (bind_map->surface_to_descriptor[i].index != UINT32_MAX)
+
+      const VkPipelineColorBlendAttachmentState *a =
+         &blend->pAttachments[binding->index];
+
+      if (binding->index != UINT32_MAX && a->colorWriteMask != 0)
          return true;
    }
 
@@ -1351,6 +1357,7 @@ has_color_buffer_write_enabled(const struct anv_pipeline *pipeline)
 
 static void
 emit_3dstate_wm(struct anv_pipeline *pipeline, struct anv_subpass *subpass,
+                const VkPipelineColorBlendStateCreateInfo *blend,
                 const VkPipelineMultisampleStateCreateInfo *multisample)
 {
    const struct brw_wm_prog_data *wm_prog_data = get_wm_prog_data(pipeline);
@@ -1395,7 +1402,7 @@ emit_3dstate_wm(struct anv_pipeline *pipeline, struct anv_subpass *subpass,
          if (wm.PixelShaderComputedDepthMode != PSCDEPTH_OFF ||
              wm_prog_data->has_side_effects ||
              wm.PixelShaderKillsPixel ||
-             has_color_buffer_write_enabled(pipeline))
+             has_color_buffer_write_enabled(pipeline, blend))
             wm.ThreadDispatchEnable = true;
 
          if (samples > 1) {
@@ -1520,7 +1527,8 @@ emit_3dstate_ps(struct anv_pipeline *pipeline,
 #if GEN_GEN >= 8
 static void
 emit_3dstate_ps_extra(struct anv_pipeline *pipeline,
-                      struct anv_subpass *subpass)
+                      struct anv_subpass *subpass,
+                      const VkPipelineColorBlendStateCreateInfo *blend)
 {
    const struct brw_wm_prog_data *wm_prog_data = get_wm_prog_data(pipeline);
 
@@ -1575,7 +1583,7 @@ emit_3dstate_ps_extra(struct anv_pipeline *pipeline,
        * attachments, we need to force-enable here.
        */
       if ((wm_prog_data->has_side_effects || wm_prog_data->uses_kill) &&
-          !has_color_buffer_write_enabled(pipeline))
+          !has_color_buffer_write_enabled(pipeline, blend))
          ps.PixelShaderHasUAV = true;
 
 #if GEN_GEN >= 9
@@ -1705,10 +1713,11 @@ genX(graphics_pipeline_create)(
    emit_3dstate_hs_te_ds(pipeline, pCreateInfo->pTessellationState);
    emit_3dstate_gs(pipeline);
    emit_3dstate_sbe(pipeline);
-   emit_3dstate_wm(pipeline, subpass, pCreateInfo->pMultisampleState);
+   emit_3dstate_wm(pipeline, subpass, pCreateInfo->pColorBlendState,
+                   pCreateInfo->pMultisampleState);
    emit_3dstate_ps(pipeline, pCreateInfo->pColorBlendState);
 #if GEN_GEN >= 8
-   emit_3dstate_ps_extra(pipeline, subpass);
+   emit_3dstate_ps_extra(pipeline, subpass, pCreateInfo->pColorBlendState);
    emit_3dstate_vf_topology(pipeline);
 #endif
    emit_3dstate_vf_statistics(pipeline);
-- 
2.13.6