more cleanup

2 files changed, 463 insertions, 406 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index f289121..71b0a88 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -5,11 +5,19 @@ set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_EXTENSIONS OFF)
 
+include(FetchContent)
+
 set(SLANG_SDK_ROOT "${CMAKE_CURRENT_SOURCE_DIR}/slang/build/slang-2025.18.2-windows-x86_64")
 if(NOT EXISTS "${SLANG_SDK_ROOT}")
     message(FATAL_ERROR "Expected Slang SDK directory at ${SLANG_SDK_ROOT}")
 endif()
 
+FetchContent_Declare(
+    abseil
+    URL https://github.com/abseil/abseil-cpp/archive/refs/tags/20240116.1.zip
+)
+FetchContent_MakeAvailable(abseil)
+
 add_executable(modular_slang main.cc)
 set_target_properties(modular_slang PROPERTIES
     RUNTIME_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/bin"
@@ -21,6 +29,8 @@ target_include_directories(modular_slang PRIVATE
 
 target_link_libraries(modular_slang PRIVATE
     "${SLANG_SDK_ROOT}/lib/slang.lib"
+    absl::status
+    absl::statusor
 )
 
 if(MSVC)
diff --git a/main.cc b/main.cc
index 32bd7f4..ba6ac3b 100644
--- a/main.cc
+++ b/main.cc
@@ -1,3 +1,4 @@
+#include <array>
 #include <filesystem>
 #include <cctype>
 #include <fstream>
@@ -10,6 +11,9 @@
 #include <unordered_set>
 #include <vector>
 
+#include "absl/status/status.h"
+#include "absl/status/statusor.h"
+
 #include <slang.h>
 #include <slang-com-ptr.h>
 
@@ -32,471 +36,514 @@ template <typename T>
 using ComPtr = ::Slang::ComPtr<T>;
 
 // Print any diagnostics carried by a Slang blob with optional context information.
-void printDiagnostics(const char* context, IBlob* diagnostics)
-{
-    if (!diagnostics)
-    {
-        return;
-    }
-
-    std::size_t size = diagnostics->getBufferSize();
-    if (size == 0)
-    {
-        return;
-    }
-
-    std::string_view text(static_cast<const char*>(diagnostics->getBufferPointer()), size);
-    if (!text.empty() && text.back() == '\0')
-    {
-        text.remove_suffix(1);
-    }
+void printDiagnostics(const char* context, IBlob* diagnostics) {
+  if (!diagnostics) {
+    return;
+  }
+
+  std::size_t size = diagnostics->getBufferSize();
+  if (size == 0) {
+    return;
+  }
+
+  std::string_view text(static_cast<const char*>(diagnostics->getBufferPointer()), size);
+  if (!text.empty() && text.back() == '\0') {
+    text.remove_suffix(1);
+  }
+
+  if (text.empty()) {
+    return;
+  }
+
+  if (context && *context) {
+    std::cerr << context << " diagnostics:" << std::endl;
+  }
+
+  std::cerr.write(text.data(), text.size());
+  if (text.back() != '\n') {
+    std::cerr << std::endl;
+  }
+}
 
-    if (text.empty())
-    {
-        return;
-    }
+// Helper to convert Slang API results into absl::Status values.
+absl::Status checkSlangResult(const char* context, SlangResult res, IBlob* diagnostics = nullptr) {
+  printDiagnostics(context, diagnostics);
 
-    if (context && *context)
-    {
-        std::cerr << context << " diagnostics:" << std::endl;
-    }
+  if (SLANG_FAILED(res)) {
+    std::ostringstream message;
+    message << (context && *context ? context : "Slang call")
+    << " failed with SlangResult " << res
+    << " (0x" << std::hex << res << std::dec << ')';
+    return absl::InternalError(message.str());
+  }
 
-    std::cerr.write(text.data(), text.size());
-    if (text.back() != '\n')
-    {
-        std::cerr << std::endl;
-    }
+  return absl::OkStatus();
 }
 
-// Helper to check Slang API results and surface diagnostic details when available.
-void checkResult(const char* context, SlangResult res, IBlob* diagnostics = nullptr)
-{
-    printDiagnostics(context, diagnostics);
-
-    if (SLANG_FAILED(res))
-    {
-        std::cerr << (context && *context ? context : "Slang call")
-                  << " failed with SlangResult " << res
-                  << " (0x" << std::hex << res << std::dec << ')' << std::endl;
-        exit(1);
-    }
-}
+absl::Status writeTextFile(const fs::path& path, std::string_view contents) {
+  std::ofstream file(path, std::ios::binary);
+  if (!file) {
+    std::ostringstream msg;
+    msg << "Failed to open " << path << " for writing.";
+    return absl::InternalError(msg.str());
+  }
 
-bool writeTextFile(const fs::path& path, std::string_view contents)
-{
-    std::ofstream file(path, std::ios::binary);
-    if (!file)
-    {
-        std::cerr << "Warning: Failed to open " << path << " for writing." << std::endl;
-        return false;
-    }
+  file.write(contents.data(), static_cast<std::streamsize>(contents.size()));
+  file.close();
 
-    file.write(contents.data(), static_cast<std::streamsize>(contents.size()));
-    file.close();
+  if (!file) {
+    std::ostringstream msg;
+    msg << "Failed to write " << path;
+    return absl::InternalError(msg.str());
+  }
 
-    if (!file)
-    {
-        std::cerr << "Warning: Failed to write " << path << std::endl;
-        return false;
-    }
-
-    return true;
+  return absl::OkStatus();
 }
 
-void addCompilerOption(std::vector<CompilerOptionEntry>& options, CompilerOptionName name)
-{
-    CompilerOptionEntry entry = {};
-    entry.name = name;
-    entry.value.intValue0 = 1;
-    options.push_back(entry);
+void addCompilerOption(std::vector<CompilerOptionEntry>& options, CompilerOptionName name) {
+  CompilerOptionEntry entry = {};
+  entry.name = name;
+  entry.value.intValue0 = 1;
+  options.push_back(entry);
 }
 
-struct FunctionInfo
-{
-    std::string name;
+struct FunctionInfo {
+  std::string name;
+};
+
+struct IncludeGuardInfo {
+  bool present = false;
+  std::string macro;
+  std::string ifndefLine;
+  std::string defineLine;
+  std::string endifLine;
 };
 
-struct IncludeGuardInfo
-{
-    bool present = false;
-    std::string macro;
-    std::string ifndefLine;
-    std::string defineLine;
-    std::string endifLine;
+struct ModuleRequest {
+  fs::path modulePath;
+  std::string moduleName;
+  std::string searchPath;
+  fs::path outputPath;
 };
 
-std::string trim(std::string_view text)
-{
-    std::size_t start = 0;
-    std::size_t end = text.size();
+std::string trim(std::string_view text) {
+  std::size_t start = 0;
+  std::size_t end = text.size();
 
-    while (start < end && std::isspace(static_cast<unsigned char>(text[start])))
-    {
-        ++start;
-    }
+  while (start < end && std::isspace(static_cast<unsigned char>(text[start]))) {
+    ++start;
+  }
 
-    while (end > start && std::isspace(static_cast<unsigned char>(text[end - 1])))
-    {
-        --end;
-    }
+  while (end > start && std::isspace(static_cast<unsigned char>(text[end - 1]))) {
+    --end;
+  }
 
-    return std::string(text.substr(start, end - start));
+  return std::string(text.substr(start, end - start));
 }
 
-bool isTopLevelFunction(DeclReflection* functionDecl)
-{
-    if (!functionDecl)
-    {
-        return false;
-    }
-
-    using Kind = DeclReflection::Kind;
-    for (DeclReflection* parent = functionDecl->getParent(); parent;
-         parent = parent->getParent())
-    {
-        switch (parent->getKind())
-        {
-        case Kind::Module:
-        case Kind::Namespace:
-            return true;
-        case Kind::Generic:
-            continue;
-        default:
-            return false;
-        }
+bool isTopLevelFunction(DeclReflection* functionDecl) {
+  if (!functionDecl) {
+    return false;
+  }
+
+  using Kind = DeclReflection::Kind;
+  for (DeclReflection* parent = functionDecl->getParent(); parent;
+      parent = parent->getParent()) {
+    switch (parent->getKind()) {
+    case Kind::Module:
+    case Kind::Namespace:
+      return true;
+    case Kind::Generic:
+      continue;
+    default:
+      return false;
     }
+  }
 
-    return false;
+  return false;
 }
 
 // Recursively gather function declarations defined in the supplied Slang module.
 void collectFunctionInfos(
     DeclReflection* decl,
     std::vector<FunctionInfo>& functions,
-    std::unordered_set<std::string>& seenNames)
-{
-    if (!decl)
-    {
-        return;
-    }
-
-    using Kind = DeclReflection::Kind;
-
-    switch (decl->getKind())
-    {
-    case Kind::Func:
-        if (auto* functionReflection = decl->asFunction())
-        {
-            if (const char* name = functionReflection->getName())
-            {
-                // Heuristic: functions that don't start with underscore are considered public
-                // (Slang convention: private/internal functions typically start with _)
-                bool isPublic = name[0] != '_';
-
-                if (*name && seenNames.insert(name).second && isTopLevelFunction(decl) && isPublic)
-                {
-                    std::cerr << "Discovered entry point: " << name << std::endl;
-                    functions.push_back({name});
-                }
-            }
-        }
-        break;
-    case Kind::Generic:
-        if (auto* genericDecl = decl->asGeneric())
-        {
-            collectFunctionInfos(
-                genericDecl->getInnerDecl(),
-                functions,
-                seenNames);
+    std::unordered_set<std::string>& seenNames) {
+  if (!decl) {
+    return;
+  }
+
+  using Kind = DeclReflection::Kind;
+
+  switch (decl->getKind()) {
+  case Kind::Func:
+    if (auto* functionReflection = decl->asFunction()) {
+      if (const char* name = functionReflection->getName()) {
+        // Heuristic: functions that don't start with underscore are considered public
+        // (Slang convention: private/internal functions typically start with _)
+        bool isPublic = name[0] != '_';
+
+        if (*name && seenNames.insert(name).second && isTopLevelFunction(decl) && isPublic) {
+          std::cerr << "Discovered entry point: " << name << std::endl;
+          functions.push_back({name});
         }
+      }
+    }
+    break;
+  case Kind::Generic:
+    if (auto* genericDecl = decl->asGeneric()) {
+      collectFunctionInfos(
+          genericDecl->getInnerDecl(),
+          functions,
+          seenNames);
+    }
+    break;
+  default:
+    break;
+  }
+
+  for (auto* child : decl->getChildren()) {
+    collectFunctionInfos(child, functions, seenNames);
+  }
+}
+
+IncludeGuardInfo detectIncludeGuard(const fs::path& sourcePath) {
+  IncludeGuardInfo info;
+
+  std::ifstream input(sourcePath);
+  if (!input) {
+    return info;
+  }
+
+  std::vector<std::string> lines;
+  std::string line;
+  while (std::getline(input, line)) {
+    lines.push_back(line);
+  }
+
+  std::size_t ifndefIndex = std::numeric_limits<std::size_t>::max();
+  for (std::size_t i = 0; i < lines.size(); ++i) {
+    std::string trimmed = trim(lines[i]);
+    if (trimmed.rfind("#ifndef", 0) == 0) {
+      std::istringstream stream(trimmed);
+      std::string directive;
+      std::string macro;
+      stream >> directive >> macro;
+      if (!macro.empty()) {
+        info.macro = macro;
+        info.ifndefLine = lines[i];
+        ifndefIndex = i;
+      }
+      break;
+    }
+  }
+
+  if (info.macro.empty()) {
+    return info;
+  }
+
+  for (std::size_t i = ifndefIndex + 1; i < lines.size(); ++i) {
+    std::string trimmed = trim(lines[i]);
+    if (trimmed.rfind("#define", 0) == 0) {
+      std::istringstream stream(trimmed);
+      std::string directive;
+      std::string macro;
+      stream >> directive >> macro;
+      if (macro == info.macro) {
+        info.defineLine = lines[i];
         break;
-    default:
-        break;
+      }
     }
+  }
 
-    for (auto* child : decl->getChildren())
-    {
-        collectFunctionInfos(child, functions, seenNames);
+  if (info.defineLine.empty()) {
+    info = IncludeGuardInfo{};
+    return info;
+  }
+
+  for (std::size_t i = lines.size(); i-- > 0;) {
+    std::string trimmed = trim(lines[i]);
+    if (trimmed.rfind("#endif", 0) == 0) {
+      info.endifLine = lines[i];
+      break;
     }
+  }
+
+  if (info.endifLine.empty()) {
+    info = IncludeGuardInfo{};
+    return info;
+  }
+
+  info.present = true;
+  return info;
 }
 
-IncludeGuardInfo detectIncludeGuard(const fs::path& sourcePath)
-{
-    IncludeGuardInfo info;
+absl::StatusOr<ModuleRequest> parseModuleRequest(int argc, char** argv) {
+  const char* programName = (argc > 0 && argv) ? argv[0] : "modular_slang";
+
+  if (argc < 2 || !argv) {
+    std::ostringstream usage;
+    usage << "Usage: " << programName << " <module.slang>";
+    return absl::InvalidArgumentError(usage.str());
+  }
+
+  ModuleRequest request;
+  request.modulePath = fs::absolute(argv[1]);
+
+  if (!fs::exists(request.modulePath)) {
+    std::ostringstream msg;
+    msg << "Module not found: " << request.modulePath;
+    return absl::NotFoundError(msg.str());
+  }
+
+  if (request.modulePath.extension() != ".slang") {
+    std::ostringstream msg;
+    msg << "Expected a .slang file: " << request.modulePath;
+    return absl::InvalidArgumentError(msg.str());
+  }
+
+  request.moduleName = request.modulePath.stem().string();
+  request.searchPath = request.modulePath.has_parent_path()
+  ? request.modulePath.parent_path().string()
+  : fs::current_path().string();
+  request.outputPath = request.modulePath;
+  request.outputPath.replace_extension(".hlsl");
+
+  return request;
+}
 
-    std::ifstream input(sourcePath);
-    if (!input)
-    {
-        return info;
-    }
+std::vector<CompilerOptionEntry> makeCommonOptions() {
+  std::vector<CompilerOptionEntry> options;
+  addCompilerOption(options, CompilerOptionName::DisableNonEssentialValidations);
+  addCompilerOption(options, CompilerOptionName::NoHLSLBinding);
+  addCompilerOption(options, CompilerOptionName::NoMangle);
+  addCompilerOption(options, CompilerOptionName::NoHLSLPackConstantBufferElements);
+  addCompilerOption(options, CompilerOptionName::NoEntryPointUniformParamTransform);
+  return options;
+}
 
-    std::vector<std::string> lines;
-    std::string line;
-    while (std::getline(input, line))
-    {
-        lines.push_back(line);
-    }
+void configureTargetDesc(
+    IGlobalSession* globalSession,
+    std::vector<CompilerOptionEntry>& targetOptions,
+    TargetDesc& outDesc) {
+  outDesc = {};
+  outDesc.format = SLANG_HLSL;
+  outDesc.profile = globalSession->findProfile("lib_6_6");
+  outDesc.flags = SLANG_TARGET_FLAG_GENERATE_WHOLE_PROGRAM;
+  outDesc.compilerOptionEntries = targetOptions.data();
+  outDesc.compilerOptionEntryCount = static_cast<uint32_t>(targetOptions.size());
+}
 
-    std::size_t ifndefIndex = std::numeric_limits<std::size_t>::max();
-    for (std::size_t i = 0; i < lines.size(); ++i)
-    {
-        std::string trimmed = trim(lines[i]);
-        if (trimmed.rfind("#ifndef", 0) == 0)
-        {
-            std::istringstream stream(trimmed);
-            std::string directive;
-            std::string macro;
-            stream >> directive >> macro;
-            if (!macro.empty())
-            {
-                info.macro = macro;
-                info.ifndefLine = lines[i];
-                ifndefIndex = i;
-            }
-            break;
-        }
-    }
+void configureSessionDesc(
+    const TargetDesc& targetDesc,
+    const ModuleRequest& request,
+    std::vector<CompilerOptionEntry>& sessionOptions,
+    std::array<const char*, 1>& searchPathStorage,
+    SessionDesc& outDesc) {
+  searchPathStorage[0] = request.searchPath.c_str();
+
+  outDesc = {};
+  outDesc.targets = &targetDesc;
+  outDesc.targetCount = 1;
+  outDesc.searchPaths = searchPathStorage.data();
+  outDesc.searchPathCount = static_cast<uint32_t>(searchPathStorage.size());
+  outDesc.compilerOptionEntries = sessionOptions.data();
+  outDesc.compilerOptionEntryCount = static_cast<uint32_t>(sessionOptions.size());
+}
 
-    if (info.macro.empty())
-    {
-        return info;
-    }
+absl::StatusOr<ComPtr<IModule>> loadSlangModule(ISession* session, const std::string& moduleName) {
+  ComPtr<IModule> module;
+  ComPtr<IBlob> diagnostics;
+  module = session->loadModule(moduleName.c_str(), diagnostics.writeRef());
 
-    for (std::size_t i = ifndefIndex + 1; i < lines.size(); ++i)
-    {
-        std::string trimmed = trim(lines[i]);
-        if (trimmed.rfind("#define", 0) == 0)
-        {
-            std::istringstream stream(trimmed);
-            std::string directive;
-            std::string macro;
-            stream >> directive >> macro;
-            if (macro == info.macro)
-            {
-                info.defineLine = lines[i];
-                break;
-            }
-        }
-    }
+  const std::string context = "loadModule: " + moduleName;
+  printDiagnostics(context.c_str(), diagnostics);
 
-    if (info.defineLine.empty())
-    {
-        info = IncludeGuardInfo{};
-        return info;
-    }
+  if (!module) {
+    std::ostringstream msg;
+    msg << "Failed to load module '" << moduleName << "'.";
+    return absl::InternalError(msg.str());
+  }
 
-    for (std::size_t i = lines.size(); i-- > 0;)
-    {
-        std::string trimmed = trim(lines[i]);
-        if (trimmed.rfind("#endif", 0) == 0)
-        {
-            info.endifLine = lines[i];
-            break;
-        }
-    }
+  return module;
+}
+
+absl::StatusOr<std::vector<FunctionInfo>> collectEntryPoints(
+    IModule* module,
+    const std::string& moduleName) {
+  std::vector<FunctionInfo> functions;
+  std::unordered_set<std::string> seenNames;
+
+  DeclReflection* moduleReflection = module ? module->getModuleReflection() : nullptr;
+  if (!moduleReflection) {
+    std::ostringstream msg;
+    msg << "Failed to retrieve reflection data for module '"
+    << moduleName << "'.";
+    return absl::InternalError(msg.str());
+  }
+
+  collectFunctionInfos(moduleReflection, functions, seenNames);
+
+  if (functions.empty()) {
+    std::ostringstream msg;
+    msg << "No functions found in module '" << moduleName << "'.";
+    return absl::NotFoundError(msg.str());
+  }
+
+  return functions;
+}
 
-    if (info.endifLine.empty())
-    {
-        info = IncludeGuardInfo{};
-        return info;
+absl::StatusOr<ComPtr<ICompileRequest>> createCompileRequest(
+    ISession* session,
+    const ModuleRequest& request,
+    const TargetDesc& targetDesc,
+    const std::vector<FunctionInfo>& functions) {
+  ComPtr<ICompileRequest> compileRequest;
+  ABSL_RETURN_IF_ERROR(checkSlangResult(
+      "ISession::createCompileRequest",
+      session->createCompileRequest(compileRequest.writeRef())));
+
+  compileRequest->setCodeGenTarget(SLANG_HLSL);
+  compileRequest->setTargetProfile(0, targetDesc.profile);
+  compileRequest->setTargetFlags(0, SLANG_TARGET_FLAG_GENERATE_WHOLE_PROGRAM);
+  compileRequest->setMatrixLayoutMode(SLANG_MATRIX_LAYOUT_ROW_MAJOR);
+  compileRequest->setLineDirectiveMode(SLANG_LINE_DIRECTIVE_MODE_NONE);
+
+  compileRequest->addSearchPath(request.searchPath.c_str());
+
+  const int translationUnitIndex = compileRequest->addTranslationUnit(
+      SLANG_SOURCE_LANGUAGE_SLANG,
+      request.moduleName.c_str());
+  compileRequest->addTranslationUnitSourceFile(
+      translationUnitIndex,
+      request.modulePath.string().c_str());
+
+  for (const FunctionInfo& func : functions) {
+    const int entryPointIndex = compileRequest->addEntryPoint(
+        translationUnitIndex,
+        func.name.c_str(),
+        SLANG_STAGE_DISPATCH);
+    if (entryPointIndex < 0) {
+      std::ostringstream msg;
+      msg << "Failed to register entry point '" << func.name << "'.";
+      return absl::InternalError(msg.str());
     }
+  }
 
-    info.present = true;
-    return info;
+  return compileRequest;
 }
 
-int main(int argc, char** argv)
-{
-    if (argc < 2) {
-        std::cerr << "Usage: " << (argc > 0 ? argv[0] : "modular_slang") << " <module.slang>" << std::endl;
-        return 1;
-    }
-    fs::path modulePath = fs::absolute(argv[1]);
-    if (!fs::exists(modulePath)) {
-        std::cerr << "Module not found: " << modulePath << std::endl;
-        return 1;
-    }
-    if (modulePath.extension() != ".slang") {
-        std::cerr << "Expected a .slang file: " << modulePath << std::endl;
-        return 1;
-    }
+absl::StatusOr<std::string> collectGeneratedHlsl(ICompileRequest* compileRequest, const std::string& moduleName) {
+  SlangResult compileResult = compileRequest->compile();
+  ComPtr<IBlob> diagnostics;
+  compileRequest->getDiagnosticOutputBlob(diagnostics.writeRef());
+  ABSL_RETURN_IF_ERROR(checkSlangResult("ICompileRequest::compile", compileResult, diagnostics.get()));
+
+  ComPtr<IBlob> targetCodeBlob;
+  ABSL_RETURN_IF_ERROR(checkSlangResult(
+      "ICompileRequest::getTargetCodeBlob",
+      compileRequest->getTargetCodeBlob(0, targetCodeBlob.writeRef())));
+
+  if (!targetCodeBlob || targetCodeBlob->getBufferSize() == 0) {
+    std::ostringstream msg;
+    msg << "No HLSL was generated for module '" << moduleName << "'.";
+    return absl::InternalError(msg.str());
+  }
+
+  return std::string(
+      static_cast<const char*>(targetCodeBlob->getBufferPointer()),
+      static_cast<std::size_t>(targetCodeBlob->getBufferSize()));
+}
 
-    std::string moduleName = modulePath.stem().string();
-    std::string searchPath = modulePath.has_parent_path()
-        ? modulePath.parent_path().string()
-        : fs::current_path().string();
-
-    fs::path outputPath = modulePath;
-    outputPath.replace_extension(".hlsl");
-
-    // Create session
-    ComPtr<IGlobalSession> globalSession;
-    checkResult("createGlobalSession", createGlobalSession(globalSession.writeRef()));
-
-    // Configure session and target
-    TargetDesc targetDesc = {};
-    targetDesc.format = SLANG_HLSL;
-    targetDesc.profile = globalSession->findProfile("lib_6_6");
-    targetDesc.flags = SLANG_TARGET_FLAG_GENERATE_WHOLE_PROGRAM;
-
-    std::vector<CompilerOptionEntry> options;
-    addCompilerOption(options, CompilerOptionName::DisableNonEssentialValidations);
-    addCompilerOption(options, CompilerOptionName::NoHLSLBinding);
-    addCompilerOption(options, CompilerOptionName::NoMangle);
-    addCompilerOption(options, CompilerOptionName::NoHLSLPackConstantBufferElements);
-    addCompilerOption(options, CompilerOptionName::NoEntryPointUniformParamTransform);
-
-    std::vector<CompilerOptionEntry> targetOptions(options);
-    targetDesc.compilerOptionEntries = targetOptions.data();
-    targetDesc.compilerOptionEntryCount = static_cast<uint32_t>(targetOptions.size());
-
-    SessionDesc sessionDesc = {};
-    sessionDesc.targets = &targetDesc;
-    sessionDesc.targetCount = 1;
-    const char* searchPaths[] = { searchPath.c_str() };
-    sessionDesc.searchPaths = searchPaths;
-    sessionDesc.searchPathCount = 1;
-
-    std::vector<CompilerOptionEntry> sessionOptions(options);
-    sessionDesc.compilerOptionEntries = sessionOptions.data();
-    sessionDesc.compilerOptionEntryCount = static_cast<uint32_t>(sessionOptions.size());
-
-    ComPtr<ISession> session;
-    checkResult("IGlobalSession::createSession",
-        globalSession->createSession(sessionDesc, session.writeRef()));
-
-    // Load the "module" aka the library
-    ComPtr<IModule> libraryModule;
-    {
-        ComPtr<IBlob> diagnosticsBlob;
-        libraryModule = session->loadModule(moduleName.c_str(), diagnosticsBlob.writeRef());
-        const std::string diagnosticsContext = "loadModule: " + moduleName;
-        printDiagnostics(diagnosticsContext.c_str(), diagnosticsBlob);
-        if (!libraryModule)
-        {
-            std::cerr << "Failed to load module '" << moduleName << "'." << std::endl;
-            return 1;
-        }
-    }
+std::string applyIncludeGuard(const std::string& hlslSource, const IncludeGuardInfo& includeGuard) {
+  if (!includeGuard.present) {
+    return hlslSource;
+  }
+
+  const std::string guardIfndefToken = "#ifndef " + includeGuard.macro;
+  const std::string guardDefineToken = "#define " + includeGuard.macro;
+  const bool alreadyGuarded =
+  hlslSource.find(guardIfndefToken) != std::string::npos &&
+  hlslSource.find(guardDefineToken) != std::string::npos;
+
+  if (alreadyGuarded) {
+    return hlslSource;
+  }
+
+  std::string body = hlslSource;
+  if (!body.empty() && body.back() != '\n') {
+    body += '\n';
+  }
+
+  std::ostringstream wrapped;
+  wrapped << includeGuard.ifndefLine << '\n';
+  wrapped << includeGuard.defineLine << '\n';
+  wrapped << '\n';
+  wrapped << body;
+  if (!body.empty() && body.back() != '\n') {
+    wrapped << '\n';
+  }
+  wrapped << includeGuard.endifLine;
+  if (!includeGuard.endifLine.empty() && includeGuard.endifLine.back() != '\n') {
+    wrapped << '\n';
+  }
+
+  return wrapped.str();
+}
 
-    // Discover top-level functions to treat as entry points
-    std::vector<FunctionInfo> functions;
-    std::unordered_set<std::string> seenNames;
-    DeclReflection* moduleReflection = libraryModule->getModuleReflection();
-    if (!moduleReflection) {
-        std::cerr << "Failed to retrieve reflection data for module '" << moduleName << "'."
-                  << std::endl;
-        return 1;
-    }
-    collectFunctionInfos(moduleReflection, functions, seenNames);
-    if (functions.empty()) {
-        std::cerr << "No functions found in module '" << moduleName << "'." << std::endl;
-        return 1;
-    }
+absl::Status run(int argc, char** argv) {
+  ABSL_ASSIGN_OR_RETURN(ModuleRequest request, parseModuleRequest(argc, argv));
 
-    // Compile
-    ComPtr<ICompileRequest> compileRequest;
-    checkResult(
-        "ISession::createCompileRequest",
-        session->createCompileRequest(compileRequest.writeRef()));
+  ComPtr<IGlobalSession> globalSession;
+  ABSL_RETURN_IF_ERROR(checkSlangResult(
+      "createGlobalSession",
+      createGlobalSession(globalSession.writeRef())));
 
-    compileRequest->setCodeGenTarget(SLANG_HLSL);
-    compileRequest->setTargetProfile(0, targetDesc.profile);
-    compileRequest->setTargetFlags(0, SLANG_TARGET_FLAG_GENERATE_WHOLE_PROGRAM);
-    compileRequest->setMatrixLayoutMode(SLANG_MATRIX_LAYOUT_ROW_MAJOR);
-    compileRequest->setLineDirectiveMode(SLANG_LINE_DIRECTIVE_MODE_NONE);
+  auto commonOptions = makeCommonOptions();
 
-    compileRequest->addSearchPath(searchPath.c_str());
+  std::vector<CompilerOptionEntry> targetOptions = commonOptions;
+  TargetDesc targetDesc;
+  configureTargetDesc(globalSession.get(), targetOptions, targetDesc);
 
-    const int translationUnitIndex = compileRequest->addTranslationUnit(
-        SLANG_SOURCE_LANGUAGE_SLANG,
-        moduleName.c_str());
-    compileRequest->addTranslationUnitSourceFile(
-        translationUnitIndex,
-        modulePath.string().c_str());
-
-    for (const FunctionInfo& func : functions)
-    {
-        const int entryPointIndex = compileRequest->addEntryPoint(
-            translationUnitIndex,
-            func.name.c_str(),
-            SLANG_STAGE_DISPATCH);
-        if (entryPointIndex < 0)
-        {
-            std::cerr << "Failed to register entry point '" << func.name << "'." << std::endl;
-            return 1;
-        }
-    }
+  std::vector<CompilerOptionEntry> sessionOptions = commonOptions;
+  SessionDesc sessionDesc;
+  std::array<const char*, 1> searchPaths{};
+  configureSessionDesc(targetDesc, request, sessionOptions, searchPaths, sessionDesc);
 
-    SlangResult compileResult = compileRequest->compile();
-    ComPtr<IBlob> compileDiagnostics;
-    compileRequest->getDiagnosticOutputBlob(compileDiagnostics.writeRef());
-    checkResult("ICompileRequest::compile", compileResult, compileDiagnostics);
+  ComPtr<ISession> session;
+  ABSL_RETURN_IF_ERROR(checkSlangResult(
+      "IGlobalSession::createSession",
+      globalSession->createSession(sessionDesc, session.writeRef())));
 
-    ComPtr<IBlob> targetCodeBlob;
-    checkResult(
-        "ICompileRequest::getTargetCodeBlob",
-        compileRequest->getTargetCodeBlob(0, targetCodeBlob.writeRef()));
+  ABSL_ASSIGN_OR_RETURN(ComPtr<IModule> libraryModule,
+      loadSlangModule(session.get(), request.moduleName));
 
-    if (!targetCodeBlob || targetCodeBlob->getBufferSize() == 0)
-    {
-        std::cerr << "No HLSL was generated for module '" << moduleName << "'." << std::endl;
-        return 1;
-    }
+  ABSL_ASSIGN_OR_RETURN(std::vector<FunctionInfo> functions,
+      collectEntryPoints(libraryModule.get(), request.moduleName));
 
-    std::string hlslSource(
-        static_cast<const char*>(targetCodeBlob->getBufferPointer()),
-        static_cast<std::size_t>(targetCodeBlob->getBufferSize()));
-
-    fs::path rawOutputPath = outputPath;
-    rawOutputPath.replace_extension(".raw.hlsl");
-    writeTextFile(rawOutputPath, hlslSource);
-
-    std::string finalHlsl = hlslSource;
-
-    IncludeGuardInfo includeGuard = detectIncludeGuard(modulePath);
-    if (includeGuard.present)
-    {
-        const std::string guardIfndefToken = "#ifndef " + includeGuard.macro;
-        const std::string guardDefineToken = "#define " + includeGuard.macro;
-        const bool alreadyGuarded =
-            finalHlsl.find(guardIfndefToken) != std::string::npos &&
-            finalHlsl.find(guardDefineToken) != std::string::npos;
-
-        if (!alreadyGuarded)
-        {
-            std::string body = finalHlsl;
-            if (!body.empty() && body.back() != '\n')
-            {
-                body += '\n';
-            }
-
-            std::ostringstream wrapped;
-            wrapped << includeGuard.ifndefLine << '\n';
-            wrapped << includeGuard.defineLine << '\n';
-            wrapped << '\n';
-            wrapped << body;
-            if (!body.empty() && body.back() != '\n')
-            {
-                wrapped << '\n';
-            }
-            wrapped << includeGuard.endifLine;
-            if (!includeGuard.endifLine.empty() && includeGuard.endifLine.back() != '\n')
-            {
-                wrapped << '\n';
-            }
-
-            finalHlsl = wrapped.str();
-        }
-    }
+  ABSL_ASSIGN_OR_RETURN(ComPtr<ICompileRequest> compileRequest,
+      createCompileRequest(session.get(), request, targetDesc, functions));
 
-    // 6. Write HLSL output to a sibling .hlsl file
-    if (!writeTextFile(outputPath, finalHlsl))
-    {
-        return 1;
-    }
+  ABSL_ASSIGN_OR_RETURN(std::string hlslSource,
+      collectGeneratedHlsl(compileRequest.get(), request.moduleName));
+
+  fs::path rawOutputPath = request.outputPath;
+  rawOutputPath.replace_extension(".raw.hlsl");
+  ABSL_RETURN_IF_ERROR(writeTextFile(rawOutputPath, hlslSource));
+
+  IncludeGuardInfo includeGuard = detectIncludeGuard(request.modulePath);
+  std::string finalHlsl = applyIncludeGuard(hlslSource, includeGuard);
+  ABSL_RETURN_IF_ERROR(writeTextFile(request.outputPath, finalHlsl));
+
+  std::cerr << "Generated HLSL written to " << request.outputPath << std::endl;
+  return absl::OkStatus();
+}
 
-    std::cerr << "Generated HLSL written to " << outputPath << std::endl;
+int main(int argc, char** argv) {
+  absl::Status status = run(argc, argv);
+  if (!status.ok()) {
+    std::cerr << status.message() << std::endl;
+    return 1;
+  }
 
-    return 0;
+  return 0;
 }