vk_shader_decompiler: Implement force early fragment tests

Force early fragment tests when the 3D method is enabled.
The established pipeline cache takes care of recompiling if needed.

This is implemented only on Vulkan to avoid invalidating the shader
cache on OpenGL.

src/video_core/engines/maxwell_3d.h

@@ -755,7 +755,11 @@ public:
 
                 u32 data_upload;
 
-                INSERT_UNION_PADDING_WORDS(0x44);
+                INSERT_UNION_PADDING_WORDS(0x16);
+
+                u32 force_early_fragment_tests;
+
+                INSERT_UNION_PADDING_WORDS(0x2D);
 
                 struct {
                     union {
@@ -1572,6 +1576,7 @@ ASSERT_REG_POSITION(shadow_ram_control, 0x49);
 ASSERT_REG_POSITION(upload, 0x60);
 ASSERT_REG_POSITION(exec_upload, 0x6C);
 ASSERT_REG_POSITION(data_upload, 0x6D);
+ASSERT_REG_POSITION(force_early_fragment_tests, 0x84);
 ASSERT_REG_POSITION(sync_info, 0xB2);
 ASSERT_REG_POSITION(tess_mode, 0xC8);
 ASSERT_REG_POSITION(tess_level_outer, 0xC9);

src/video_core/renderer_vulkan/fixed_pipeline_state.cpp

@@ -46,7 +46,7 @@ void FixedPipelineState::Fill(const Maxwell& regs, bool has_extended_dynamic_sta
                                     regs.polygon_offset_fill_enable};
     const u32 topology_index = static_cast<u32>(regs.draw.topology.Value());
 
-    raw = 0;
+    raw1 = 0;
     primitive_restart_enable.Assign(regs.primitive_restart.enabled != 0 ? 1 : 0);
     depth_bias_enable.Assign(enabled_lut[POLYGON_OFFSET_ENABLE_LUT[topology_index]] != 0 ? 1 : 0);
     depth_clamp_disabled.Assign(regs.view_volume_clip_control.depth_clamp_disabled.Value());
@@ -61,12 +61,13 @@ void FixedPipelineState::Fill(const Maxwell& regs, bool has_extended_dynamic_sta
     rasterize_enable.Assign(regs.rasterize_enable != 0 ? 1 : 0);
     topology.Assign(regs.draw.topology);
 
-    alpha_raw = 0;
+    raw2 = 0;
     const auto test_func =
         regs.alpha_test_enabled == 1 ? regs.alpha_test_func : Maxwell::ComparisonOp::Always;
     alpha_test_func.Assign(PackComparisonOp(test_func));
-    alpha_test_ref = Common::BitCast<u32>(regs.alpha_test_ref);
+    early_z.Assign(regs.force_early_fragment_tests != 0 ? 1 : 0);
 
+    alpha_test_ref = Common::BitCast<u32>(regs.alpha_test_ref);
     point_size = Common::BitCast<u32>(regs.point_size);
 
     for (std::size_t index = 0; index < Maxwell::NumVertexArrays; ++index) {

src/video_core/renderer_vulkan/fixed_pipeline_state.h

@@ -171,7 +171,7 @@ struct FixedPipelineState {
     };
 
     union {
-        u32 raw;
+        u32 raw1;
         BitField<0, 1, u32> no_extended_dynamic_state;
         BitField<2, 1, u32> primitive_restart_enable;
         BitField<3, 1, u32> depth_bias_enable;
@@ -187,13 +187,13 @@ struct FixedPipelineState {
         BitField<23, 1, u32> rasterize_enable;
         BitField<24, 4, Maxwell::PrimitiveTopology> topology;
     };
-
-    u32 alpha_test_ref; ///< Alpha test reference value
     union {
-        u32 alpha_raw;
+        u32 raw2;
         BitField<0, 3, u32> alpha_test_func;
+        BitField<3, 1, u32> early_z;
     };
 
+    u32 alpha_test_ref;
     u32 point_size;
     std::array<u32, Maxwell::NumVertexArrays> binding_divisors;
     std::array<VertexAttribute, Maxwell::NumVertexAttributes> attributes;

src/video_core/renderer_vulkan/vk_pipeline_cache.cpp

@@ -344,6 +344,7 @@ VKPipelineCache::DecompileShaders(const FixedPipelineState& fixed_state) {
         specialization.attribute_types[i] = attribute.Type();
     }
     specialization.ndc_minus_one_to_one = fixed_state.ndc_minus_one_to_one;
+    specialization.early_fragment_tests = fixed_state.early_z;
 
     // Alpha test
     specialization.alpha_test_func =

src/video_core/renderer_vulkan/vk_shader_decompiler.cpp

@@ -315,7 +315,6 @@ public:
                                          "supported on this device");
             }
         }
-
         if (ir.UsesLayer() || ir.UsesViewportIndex()) {
             if (ir.UsesViewportIndex()) {
                 AddCapability(spv::Capability::MultiViewport);
@@ -325,11 +324,9 @@ public:
                 AddCapability(spv::Capability::ShaderViewportIndexLayerEXT);
             }
         }
-
         if (device.IsFormatlessImageLoadSupported()) {
             AddCapability(spv::Capability::StorageImageReadWithoutFormat);
         }
-
         if (device.IsFloat16Supported()) {
             AddCapability(spv::Capability::Float16);
         }
@@ -377,6 +374,9 @@ public:
             if (header.ps.omap.depth) {
                 AddExecutionMode(main, spv::ExecutionMode::DepthReplacing);
             }
+            if (specialization.early_fragment_tests) {
+                AddExecutionMode(main, spv::ExecutionMode::EarlyFragmentTests);
+            }
             break;
         case ShaderType::Compute:
             const auto workgroup_size = specialization.workgroup_size;

src/video_core/renderer_vulkan/vk_shader_decompiler.h

@@ -95,6 +95,7 @@ struct Specialization final {
     std::bitset<Maxwell::NumVertexAttributes> enabled_attributes;
     std::array<Maxwell::VertexAttribute::Type, Maxwell::NumVertexAttributes> attribute_types{};
     bool ndc_minus_one_to_one{};
+    bool early_fragment_tests{};
     float alpha_test_ref{};
     Maxwell::ComparisonOp alpha_test_func{};
 };