Allow shader patching

documents/patching-shader.md

@@ -0,0 +1,14 @@
+### Install Vulkan SDK and \*ensure `spirv-cross` and `glslc` are in PATH\*.
+
+1. Enable `dumpShaders` in config.toml
+
+2. Run `spirv-cross -V fs_0x000000.spv --output fs_0x000000.glsl` to decompile the SPIR-V IR to GLSL.
+
+3. Edit the GLSL file as you wish
+
+4. To compile back to SPIR-V, run (change the _**-fshader-stage**_ to correct stage):
+   `glslc --target-env=vulkan1.3 --target-spv=spv1.6 -fshader-stage=frag fs_0x000000.glsl -o fs_0x000000.spv`
+
+5. Put the updated .spv file to `shader/patch` folder with the same name as the original shader
+
+6. Enable `patchShaders` in config.toml

src/common/config.cpp

@@ -21,6 +21,7 @@ static bool isLibc = true;
 static bool isShowSplash = false;
 static bool isNullGpu = false;
 static bool shouldDumpShaders = false;
+static bool shouldPatchShaders = true;
 static bool shouldDumpPM4 = false;
 static u32 vblankDivider = 1;
 static bool vkValidation = false;
@@ -94,6 +95,10 @@ bool dumpShaders() {
     return shouldDumpShaders;
 }
 
+bool patchShaders() {
+    return shouldPatchShaders;
+}
+
 bool dumpPM4() {
     return shouldDumpPM4;
 }
@@ -245,6 +250,7 @@ void load(const std::filesystem::path& path) {
         screenHeight = toml::find_or<int>(gpu, "screenHeight", screenHeight);
         isNullGpu = toml::find_or<bool>(gpu, "nullGpu", false);
         shouldDumpShaders = toml::find_or<bool>(gpu, "dumpShaders", false);
+        shouldPatchShaders = toml::find_or<bool>(gpu, "patchShaders", true);
         shouldDumpPM4 = toml::find_or<bool>(gpu, "dumpPM4", false);
         vblankDivider = toml::find_or<int>(gpu, "vblankDivider", 1);
     }
@@ -325,6 +331,7 @@ void save(const std::filesystem::path& path) {
     data["GPU"]["screenHeight"] = screenHeight;
     data["GPU"]["nullGpu"] = isNullGpu;
     data["GPU"]["dumpShaders"] = shouldDumpShaders;
+    data["GPU"]["patchShaders"] = shouldPatchShaders;
     data["GPU"]["dumpPM4"] = shouldDumpPM4;
     data["GPU"]["vblankDivider"] = vblankDivider;
     data["Vulkan"]["gpuId"] = gpuId;

src/common/config.h

@@ -25,6 +25,7 @@ bool isLleLibc();
 bool showSplash();
 bool nullGpu();
 bool dumpShaders();
+bool patchShaders();
 bool dumpPM4();
 bool isRdocEnabled();
 u32 vblankDiv();

src/video_core/renderer_vulkan/vk_pipeline_cache.cpp

@@ -274,7 +274,15 @@ std::unique_ptr<GraphicsPipeline> PipelineCache::CreateGraphicsPipeline() {
 
             // Compile IR to SPIR-V
             auto spv_code = Shader::Backend::SPIRV::EmitSPIRV(profile, programs[i], binding);
-            if (Config::dumpShaders()) {
+            bool patched = false;
+            if (Config::patchShaders()) {
+                auto patch = GetShaderPatch(hash, stage, "spv");
+                if (patch) {
+                    spv_code = *patch;
+                    patched = true;
+                }
+            }
+            if (Config::dumpShaders() && !patched) {
                 DumpShader(spv_code, hash, stage, "spv");
             }
             stages[i] = CompileSPV(spv_code, instance.GetDevice());
@@ -315,8 +323,16 @@ std::unique_ptr<ComputePipeline> PipelineCache::CreateComputePipeline() {
 
         // Compile IR to SPIR-V
         u32 binding{};
-        const auto spv_code = Shader::Backend::SPIRV::EmitSPIRV(profile, program, binding);
+        auto spv_code = Shader::Backend::SPIRV::EmitSPIRV(profile, program, binding);
-        if (Config::dumpShaders()) {
+        bool patched = false;
+        if (Config::patchShaders()) {
+            auto patch = GetShaderPatch(compute_key, Shader::Stage::Compute, "spv");
+            if (patch) {
+                spv_code = *patch;
+                patched = true;
+            }
+        }
+        if (Config::dumpShaders() && !patched) {
             DumpShader(spv_code, compute_key, Shader::Stage::Compute, "spv");
         }
         const auto module = CompileSPV(spv_code, instance.GetDevice());
@@ -343,4 +359,22 @@ void PipelineCache::DumpShader(std::span<const u32> code, u64 hash, Shader::Stag
     file.WriteSpan(code);
 }
 
+std::optional<std::vector<u32>> PipelineCache::GetShaderPatch(u64 hash, Shader::Stage stage,
+                                                              std::string_view ext) {
+    using namespace Common::FS;
+    const auto patch_dir = GetUserPath(PathType::ShaderDir) / "patch";
+    if (!std::filesystem::exists(patch_dir)) {
+        std::filesystem::create_directories(patch_dir);
+    }
+    const auto filename = fmt::format("{}_{:#018x}.{}", stage, hash, ext);
+    const auto filepath = patch_dir / filename;
+    if (!std::filesystem::exists(filepath)) {
+        return {};
+    }
+    const auto file = IOFile{patch_dir / filename, FileAccessMode::Read};
+    std::vector<u32> code(file.GetSize() / sizeof(u32));
+    file.Read(code);
+    return code;
+}
+
 } // namespace Vulkan

src/video_core/renderer_vulkan/vk_pipeline_cache.h

@@ -33,6 +33,8 @@ public:
 private:
     void RefreshGraphicsKey();
     void DumpShader(std::span<const u32> code, u64 hash, Shader::Stage stage, std::string_view ext);
+    std::optional<std::vector<u32>> GetShaderPatch(u64 hash, Shader::Stage stage,
+                                                   std::string_view ext);
 
     std::unique_ptr<GraphicsPipeline> CreateGraphicsPipeline();
     std::unique_ptr<ComputePipeline> CreateComputePipeline();