Add saveRawVariants flag to matc (#7949)

filament/docs/SpirvDebugging.md

@@ -64,14 +64,15 @@ First determine the Filament material and variant that causes the problem.
 What we want is the "raw" GLSL version of the shader, before any optimizations / cross-compilation
 happens.
 
-The easiest way I've found to do this is by adding a `std::cout` statement inside `MaterialBuilder`,
-right after `sg.createFragmentProgram` or `sg.createVertexProgram` is called. For example,
+We can use the `--save-raw-variants` debug flag in matc to export each GLSL
+shader to a file. For example:
 
 ```
-if (v.variant.key == 8u) { std::cout << shader << std::endl; }
+matc --save-raw-variants --optimize-size --variant-filter fog,ssr,vsm,stereo \
+        -a all -p all -o mymaterial.filamat mymaterial.mat
 ```
 
-Then, I invoke `matc` and redirect stdout to a .frag or .vert file.
+Files will be named like `mymaterial_0x05.frag` or `mymaterial_0x05.vert`.
 
 Note that gltfio material "templates" first go through a build step. After building gltfio, the
 gltfio Filament materials are output to:

libs/filamat/include/filamat/MaterialBuilder.h

@@ -134,6 +134,7 @@ protected:
     TargetApi mTargetApi = (TargetApi) 0;
     Optimization mOptimization = Optimization::PERFORMANCE;
     bool mPrintShaders = false;
+    bool mSaveRawVariants = false;
     bool mGenerateDebugInfo = false;
     bool mIncludeEssl1 = true;
     utils::bitset32 mShaderModels;
@@ -586,6 +587,14 @@ public:
     //! If true, will output the generated GLSL shader code to stdout.
     MaterialBuilder& printShaders(bool printShaders) noexcept;
 
+    /**
+     * If true, this will write the raw generated GLSL for each variant to a text file in the
+     * current directory. The file will be named after the material name and the variant name. Its
+     * extension will be derived from the shader stage. For example, mymaterial_0x0e.frag,
+     * mymaterial_0x18.vert, etc.
+     */
+    MaterialBuilder& saveRawVariants(bool saveVariants) noexcept;
+
     //! If true, will include debugging information in generated SPIRV.
     MaterialBuilder& generateDebugInfo(bool generateDebugInfo) noexcept;
 

libs/filamat/src/MaterialBuilder.cpp

@@ -57,7 +57,7 @@
 #include <atomic>
 #include <utility>
 #include <vector>
-
+#include <fstream>
 
 namespace filamat {
 
@@ -547,6 +547,11 @@ MaterialBuilder& MaterialBuilder::printShaders(bool printShaders) noexcept {
     return *this;
 }
 
+MaterialBuilder& MaterialBuilder::saveRawVariants(bool saveRawVariants) noexcept {
+    mSaveRawVariants = saveRawVariants;
+    return *this;
+}
+
 MaterialBuilder& MaterialBuilder::generateDebugInfo(bool generateDebugInfo) noexcept {
     mGenerateDebugInfo = generateDebugInfo;
     return *this;
@@ -918,6 +923,30 @@ bool MaterialBuilder::generateShaders(JobSystem& jobSystem, const std::vector<Va
                             shaderModel, targetApi, targetLanguage, featureLevel, info);
                 }
 
+                // Write the variant to a file.
+                if (mSaveRawVariants) {
+                    int variantKey = v.variant.key;
+                    auto getExtension = [](backend::ShaderStage stage) {
+                        switch (stage) {
+                            case backend::ShaderStage::VERTEX:
+                                return "vert";
+                            case backend::ShaderStage::FRAGMENT:
+                                return "frag";
+                            case backend::ShaderStage::COMPUTE:
+                                return "comp";
+                        }
+                    };
+                    char filename[256];
+                    snprintf(filename, sizeof(filename), "%s_0x%02x.%s", mMaterialName.c_str_safe(),
+                            variantKey, getExtension(v.stage));
+                    printf("Writing variant 0x%02x to %s\n", variantKey, filename);
+                    std::ofstream file(filename);
+                    if (file.is_open()) {
+                        file << shader;
+                        file.close();
+                    }
+                }
+
                 std::string* pGlsl = nullptr;
                 if (targetApiNeedsGlsl) {
                     pGlsl = &shader;

tools/matc/src/matc/CommandlineConfig.cpp

@@ -103,6 +103,8 @@ static void usage(char* name) {
             "       Skip validation of number of sampler used\n\n"
             "   --print, -t\n"
             "       Print generated shaders for debugging\n\n"
+            "   --save-raw-variants, -R\n"
+            "       Write the raw generated GLSL for each variant to a text file in the current directory.\n\n"
     );
     const std::string from("MATC");
     for (size_t pos = usage.find(from); pos != std::string::npos; pos = usage.find(from, pos)) {
@@ -179,7 +181,7 @@ static void parseDefine(std::string defineString, Config::StringReplacementMap&
 }
 
 bool CommandlineConfig::parse() {
-    static constexpr const char* OPTSTR = "hLxo:f:dm:a:l:p:D:T:P:OSEr:vV:gtwF1";
+    static constexpr const char* OPTSTR = "hLxo:f:dm:a:l:p:D:T:P:OSEr:vV:gtwF1R";
     static const struct option OPTIONS[] = {
             { "help",                    no_argument, nullptr, 'h' },
             { "license",                 no_argument, nullptr, 'L' },
@@ -204,6 +206,7 @@ bool CommandlineConfig::parse() {
             { "version",                 no_argument, nullptr, 'v' },
             { "raw",                     no_argument, nullptr, 'w' },
             { "no-sampler-validation",   no_argument, nullptr, 'F' },
+            { "save-raw-variants",       no_argument, nullptr, 'R' },
             { nullptr, 0, nullptr, 0 }  // termination of the option list
     };
 
@@ -326,6 +329,8 @@ bool CommandlineConfig::parse() {
                 break;
             case 'F':
                 mNoSamplerValidation = true;
+            case 'R':
+                mSaveRawVariants = true;
                 break;
         }
     }

tools/matc/src/matc/Config.h

@@ -111,6 +111,10 @@ public:
         return mPrintShaders;
     }
 
+    bool saveRawVariants() const noexcept {
+        return mSaveRawVariants;
+    }
+
     bool rawShaderMode() const noexcept {
         return mRawShaderMode;
     }
@@ -149,6 +153,7 @@ protected:
     bool mPrintShaders = false;
     bool mRawShaderMode = false;
     bool mNoSamplerValidation = false;
+    bool mSaveRawVariants = false;
     Optimization mOptimizationLevel = Optimization::PERFORMANCE;
     Metadata mReflectionTarget = Metadata::NONE;
     Platform mPlatform = Platform::ALL;

tools/matc/src/matc/MaterialCompiler.cpp

@@ -408,6 +408,7 @@ bool MaterialCompiler::run(const Config& config) {
         .targetApi(config.getTargetApi())
         .optimization(config.getOptimizationLevel())
         .printShaders(config.printShaders())
+        .saveRawVariants(config.saveRawVariants())
         .generateDebugInfo(config.isDebug())
         .variantFilter(config.getVariantFilter() | builder.getVariantFilter());