Mesa (master): anv: ignore pColorBlendState if all color attachments of the subpass are unused

[Samuel Iglesias Gonsálvez]

Module: Mesa
Branch: master
Commit: 2cf64fdb4623cb145e51f615cf0baf85de23234d
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=2cf64fdb4623cb145e51f615cf0baf85de23234d

Author: Samuel Iglesias Gonsálvez <siglesias at igalia.com>
Date:   Mon May  7 08:42:56 2018 +0200

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

---

 src/intel/vulkan/anv_pipeline.c  | 14 ++++++++++++--
 src/intel/vulkan/genX_pipeline.c |  2 +-
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/src/intel/vulkan/anv_pipeline.c b/src/intel/vulkan/anv_pipeline.c
index 87788de10a..8f30136b10 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 d3af9304ba..6016d25758 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;
    }