[D3D12] ROV: Empty pixel shader for depth-only drawing

src/xenia/gpu/d3d12/pipeline_cache.cc

@@ -15,6 +15,7 @@
 #include <cinttypes>
 #include <cmath>
 #include <cstring>
+#include <utility>
 
 #include "xenia/base/assert.h"
 #include "xenia/base/logging.h"
@@ -42,6 +43,11 @@ PipelineCache::PipelineCache(D3D12CommandProcessor* command_processor,
       edram_rov_used_(edram_rov_used) {
   shader_translator_ = std::make_unique<DxbcShaderTranslator>(edram_rov_used_);
 
+  if (edram_rov_used_) {
+    depth_only_pixel_shader_ =
+        std::move(shader_translator_->CreateDepthOnlyPixelShader());
+  }
+
   // Set pipeline state description values we never change.
   // Zero out tessellation, stream output, blend state and formats for render
   // targets 4+, node mask, cached PSO, flags and other things.
@@ -325,8 +331,13 @@ PipelineCache::UpdateStatus PipelineCache::UpdateShaderStages(
     update_desc_.PS.pShaderBytecode = pixel_shader->translated_binary().data();
     update_desc_.PS.BytecodeLength = pixel_shader->translated_binary().size();
   } else {
-    update_desc_.PS.pShaderBytecode = nullptr;
-    update_desc_.PS.BytecodeLength = 0;
+    if (edram_rov_used_) {
+      update_desc_.PS.pShaderBytecode = depth_only_pixel_shader_.data();
+      update_desc_.PS.BytecodeLength = depth_only_pixel_shader_.size();
+    } else {
+      update_desc_.PS.pShaderBytecode = nullptr;
+      update_desc_.PS.BytecodeLength = 0;
+    }
   }
   switch (primitive_type) {
     case PrimitiveType::kPointList:

src/xenia/gpu/d3d12/pipeline_cache.h

@@ -11,6 +11,7 @@
 #define XENIA_GPU_D3D12_PIPELINE_CACHE_H_
 
 #include <unordered_map>
+#include <vector>
 
 #include "third_party/xxhash/xxhash.h"
 
@@ -93,6 +94,10 @@ class PipelineCache {
   // All loaded shaders mapped by their guest hash key.
   std::unordered_map<uint64_t, D3D12Shader*> shader_map_;
 
+  // Empty depth-only pixel shader for writing to depth buffer via ROV when no
+  // Xenos pixel shader provided.
+  std::vector<uint8_t> depth_only_pixel_shader_;
+
   // Hash state used to incrementally produce pipeline hashes during update.
   // By the time the full update pass has run the hash will represent the
   // current state in a way that can uniquely identify the produced