[Mesa-dev] [PATCH] anv: ignore pColorBlendState if all color attachments of the subpass are unused

[Samuel Iglesias Gonsálvez]

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

Signed-off-by: Samuel Iglesias Gonsálvez <siglesias at igalia.com>
---
 src/intel/vulkan/anv_pipeline.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 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) {
-- 
2.17.0