From a0d1ef7f619a330ea2807fb0eb6c5e55c438b470 Mon Sep 17 00:00:00 2001
From: Philip Rebohle <philip.rebohle@tu-dortmund.de>
Date: Wed, 6 Jul 2022 02:51:05 +0200
Subject: [PATCH] [dxvk] Handle null shader in DxvkShaderPipelineLibrary

---
 src/dxvk/dxvk_shader.cpp              | 26 +++++++++++++++++++++-----
 src/dxvk/meson.build                  |  2 ++
 src/dxvk/shaders/dxvk_dummy_frag.frag |  5 +++++
 3 files changed, 28 insertions(+), 5 deletions(-)
 create mode 100644 src/dxvk/shaders/dxvk_dummy_frag.frag

diff --git a/src/dxvk/dxvk_shader.cpp b/src/dxvk/dxvk_shader.cpp
index acd8f822..361cbd9e 100644
--- a/src/dxvk/dxvk_shader.cpp
+++ b/src/dxvk/dxvk_shader.cpp
@@ -1,6 +1,8 @@
 #include "dxvk_device.h"
 #include "dxvk_shader.h"
 
+#include <dxvk_dummy_frag.h>
+
 #include <algorithm>
 #include <unordered_map>
 #include <unordered_set>
@@ -444,14 +446,19 @@ namespace dxvk {
     const DxvkShaderPipelineLibraryCompileArgs& args) {
     std::lock_guard lock(m_mutex);
 
-    VkPipeline& pipeline = (m_shader->info().stage == VK_SHADER_STAGE_VERTEX_BIT && !args.depthClipEnable)
+    VkShaderStageFlagBits stage = VK_SHADER_STAGE_FRAGMENT_BIT;
+
+    if (m_shader)
+      stage = m_shader->info().stage;
+
+    VkPipeline& pipeline = (stage == VK_SHADER_STAGE_VERTEX_BIT && !args.depthClipEnable)
       ? m_pipelineNoDepthClip
       : m_pipeline;
 
     if (pipeline)
       return pipeline;
 
-    switch (m_shader->info().stage) {
+    switch (stage) {
       case VK_SHADER_STAGE_VERTEX_BIT:
         pipeline = compileVertexShaderPipeline(cache, args);
         break;
@@ -555,9 +562,18 @@ namespace dxvk {
   VkPipeline DxvkShaderPipelineLibrary::compileFragmentShaderPipeline(VkPipelineCache cache) {
     auto vk = m_device->vkd();
 
+    // Initialize code buffer. As a special case, it is possible that
+    // we have to deal with a null shader, but the pipeline library
+    // extension requires us to always specify a fragment shader.
     DxvkShaderStageInfo stageInfo(m_device);
-    stageInfo.addStage(VK_SHADER_STAGE_FRAGMENT_BIT,
-      m_shader->getCode(m_layout, DxvkShaderModuleCreateInfo()), nullptr);
+
+    if (m_shader) {
+      stageInfo.addStage(VK_SHADER_STAGE_FRAGMENT_BIT,
+        m_shader->getCode(m_layout, DxvkShaderModuleCreateInfo()), nullptr);
+    } else {
+      stageInfo.addStage(VK_SHADER_STAGE_FRAGMENT_BIT,
+        SpirvCodeBuffer(dxvk_dummy_frag), nullptr);
+    }
 
     // Set up dynamic state. We do not know any pipeline state
     // at this time, so make as much state dynamic as we can.
@@ -612,7 +628,7 @@ namespace dxvk {
     info.layout               = m_layout->getPipelineLayout();
     info.basePipelineIndex    = -1;
 
-    if (m_shader->flags().test(DxvkShaderFlag::HasSampleRateShading))
+    if (m_shader && m_shader->flags().test(DxvkShaderFlag::HasSampleRateShading))
       info.pMultisampleState  = &msInfo;
 
     VkPipeline pipeline = VK_NULL_HANDLE;
diff --git a/src/dxvk/meson.build b/src/dxvk/meson.build
index 0ed8caf6..e49c49b9 100644
--- a/src/dxvk/meson.build
+++ b/src/dxvk/meson.build
@@ -27,6 +27,8 @@ dxvk_shaders = files([
   'shaders/dxvk_copy_depth_stencil_2d.frag',
   'shaders/dxvk_copy_depth_stencil_ms.frag',
 
+  'shaders/dxvk_dummy_frag.frag',
+
   'shaders/dxvk_fullscreen_geom.geom',
   'shaders/dxvk_fullscreen_vert.vert',
   'shaders/dxvk_fullscreen_layer_vert.vert',
diff --git a/src/dxvk/shaders/dxvk_dummy_frag.frag b/src/dxvk/shaders/dxvk_dummy_frag.frag
new file mode 100644
index 00000000..0afc2bd1
--- /dev/null
+++ b/src/dxvk/shaders/dxvk_dummy_frag.frag
@@ -0,0 +1,5 @@
+#version 450
+
+void main() {
+
+}