[SPIR-V] tfetch UseRegisterLOD support

src/xenia/gpu/spirv_shader_translator.cc

@@ -111,6 +111,8 @@ void SpirvShaderTranslator::StartTranslation() {
                          "pc");
   a0_ = b.createVariable(spv::StorageClass::StorageClassFunction, int_type_,
                          "a0");
+  lod_ = b.createVariable(spv::StorageClass::StorageClassFunction, float_type_,
+                          "lod");
 
   // Uniform constants.
   Id float_consts_type =
@@ -1843,6 +1845,10 @@ void SpirvShaderTranslator::ProcessTextureFetchInstruction(
       spv::Builder::TextureParameters params = {0};
       params.coords = src;
       params.sampler = texture;
+      if (instr.attributes.use_register_lod) {
+        params.lod = b.createLoad(lod_);
+      }
+
       dest =
           b.createTextureCall(spv::NoPrecision, vec4_float_type_, false, false,
                               false, false, is_vertex_shader(), params);
@@ -1906,6 +1912,7 @@ void SpirvShaderTranslator::ProcessTextureFetchInstruction(
       // <lod register> = src1.x (MIP level)
       // ... immediately after
       // tfetch UseRegisterLOD=true
+      b.createStore(b.createCompositeExtract(src, float_type_, 0), lod_);
     } break;
 
     default:

src/xenia/gpu/spirv_shader_translator.h

@@ -149,6 +149,7 @@ class SpirvShaderTranslator : public ShaderTranslator {
   spv::Id loop_count_ = 0;   // Loop counter stack
   spv::Id ps_ = 0, pv_ = 0;  // IDs of previous results
   spv::Id pc_ = 0;           // Program counter
+  spv::Id lod_ = 0;          // LOD register
   spv::Id pos_ = 0;
   spv::Id push_consts_ = 0;
   spv::Id interpolators_ = 0;