anv: ignore pColorBlendState if all color attachments of the subpass are unused

According to Vulkan spec:

  "pColorBlendState is a pointer to an instance of the
   VkPipelineColorBlendStateCreateInfo structure, and is ignored if the
   pipeline has rasterization disabled or if the subpass of the render pass the
   pipeline is created against does not use any color attachments."

Fixes tests from CL#2505:

   dEQP-VK.renderpass.*.simple.color_unused_omit_blend_state

v2:
- Check that blend is not NULL before usage.

Signed-off-by: Samuel Iglesias Gonsálvez <[email protected]>
Reviewed-by: Jason Ekstrand <[email protected]>

2 files changed, 13 insertions, 3 deletions

diff --git a/src/intel/vulkan/anv_pipeline.c b/src/intel/vulkan/anv_pipeline.c
index 87788de10a5..8f30136b100 100644
--- a/src/intel/vulkan/anv_pipeline.c
+++ b/src/intel/vulkan/anv_pipeline.c
@@ -1247,8 +1247,18 @@ anv_pipeline_validate_create_info(const VkGraphicsPipelineCreateInfo *info)
       if (subpass && subpass->depth_stencil_attachment.attachment != VK_ATTACHMENT_UNUSED)
          assert(info->pDepthStencilState);
 
-      if (subpass && subpass->color_count > 0)
-         assert(info->pColorBlendState);
+      if (subpass && subpass->color_count > 0) {
+         bool all_color_unused = true;
+         for (int i = 0; i < subpass->color_count; i++) {
+            if (subpass->color_attachments[i].attachment != VK_ATTACHMENT_UNUSED)
+               all_color_unused = false;
+         }
+         /* pColorBlendState is ignored if the pipeline has rasterization
+          * disabled or if the subpass of the render pass the pipeline is
+          * created against does not use any color attachments.
+          */
+         assert(info->pColorBlendState || all_color_unused);
+      }
    }
 
    for (uint32_t i = 0; i < info->stageCount; ++i) {
diff --git a/src/intel/vulkan/genX_pipeline.c b/src/intel/vulkan/genX_pipeline.c
index d3af9304ba3..6016d257584 100644
--- a/src/intel/vulkan/genX_pipeline.c
+++ b/src/intel/vulkan/genX_pipeline.c
@@ -1361,7 +1361,7 @@ has_color_buffer_write_enabled(const struct anv_pipeline *pipeline,
       if (binding->index == UINT32_MAX)
          continue;
 
-      if (blend->pAttachments[binding->index].colorWriteMask != 0)
+      if (blend && blend->pAttachments[binding->index].colorWriteMask != 0)
          return true;
    }