[clang] Pull some utility functions into CompilerInvocation NFC

[benlangmuir]

Summary

Move copying compiler arguments to a vector<string> and modifying
common module-related options into CompilerInvocation in preparation for
using some of them in more places and to avoid duplicating this code
accidentally in the future.

[jansvoboda11]

LGMT! Nice cleanup.

clang/include/clang/Frontend/CompilerInvocation.h

public:
   /// executable), for finding the builtin compiler path.
   static std::string GetResourcesPath(const char *Argv0, void *MainAddr);
 
   /// Retrieve a module hash string that is suitable for uniquely
   /// identifying the conditions under which the module was built.
   std::string getModuleHash() const;
 
   using StringAllocator = llvm::function_ref<const char *(const llvm::Twine &)>;
-  /// Generate a cc1-compatible command line arguments from this instance.
+  /// Generate cc1-compatible command line arguments from this instance.
   ///
   /// \param [out] Args - The generated arguments. Note that the caller is
   /// responsible for inserting the path to the clang executable and "-cc1" if
   /// desired.
   /// \param SA - A function that given a Twine can allocate storage for a given
   /// command line argument and return a pointer to the newly allocated string.
   /// The returned pointer is what gets appended to Args.
   void generateCC1CommandLine(llvm::SmallVectorImpl<const char *> &Args,
                               StringAllocator SA) const;
 
+  /// Generate cc1-compatible command line arguments from this instance,
+  /// wrapping the result as a std::vector<std::string>.
+  ///
+  /// This is a (less-efficient) wrapper over generateCC1CommandLine().
+  std::vector<std::string> getCC1CommandLine() const;
+
+  /// Reset all of the options that are not considered when building a
+  /// module.
+  void resetNonModularOptions();
+
+  /// Disable implicit modules and canonicalize options that are only used by
+  /// implicit modules.
+  void clearImplicitModuleBuildOptions();
+
 private:
   static bool CreateFromArgsImpl(CompilerInvocation &Res,
                                  ArrayRef<const char *> CommandLineArgs,
                                  DiagnosticsEngine &Diags, const char *Argv0);
 
   /// Generate command line options from DiagnosticOptions.
   static void GenerateDiagnosticArgs(const DiagnosticOptions &Opts,
                                      SmallVectorImpl<const char *> &Args,

clang/lib/Frontend/CompilerInstance.cpp

compileModuleImpl(CompilerInstance &ImportingInstance, SourceLocation ImportLoc,
   // Construct a compiler invocation for creating this module.
   auto Invocation =
       std::make_shared<CompilerInvocation>(ImportingInstance.getInvocation());
 
   PreprocessorOptions &PPOpts = Invocation->getPreprocessorOpts();
 
   // For any options that aren't intended to affect how a module is built,
   // reset them to their default values.
-  Invocation->getLangOpts()->resetNonModularOptions();
-  PPOpts.resetNonModularOptions();
+  Invocation->resetNonModularOptions();
 
   // Remove any macro definitions that are explicitly ignored by the module.
   // They aren't supposed to affect how the module is built anyway.
   HeaderSearchOptions &HSOpts = Invocation->getHeaderSearchOpts();
   llvm::erase_if(PPOpts.Macros,
                  [&HSOpts](const std::pair<std::string, bool> &def) {
                    StringRef MacroDef = def.first;
                    return HSOpts.ModulesIgnoreMacros.contains(

clang/lib/Frontend/CompilerInvocation.cpp

GenerateCodeGenArgs(CodeGenOpts, Args, SA, T, FrontendOpts.OutputFile,
                       &*LangOpts);
   GeneratePreprocessorArgs(*PreprocessorOpts, Args, SA, *LangOpts, FrontendOpts,
                            CodeGenOpts);
   GeneratePreprocessorOutputArgs(PreprocessorOutputOpts, Args, SA,
                                  FrontendOpts.ProgramAction);
   GenerateDependencyOutputArgs(DependencyOutputOpts, Args, SA);
 }
 
+std::vector<std::string> CompilerInvocation::getCC1CommandLine() const {
+  // Set up string allocator.
+  llvm::BumpPtrAllocator Alloc;
+  llvm::StringSaver Strings(Alloc);
+  auto SA = [&Strings](const Twine &Arg) { return Strings.save(Arg).data(); };
+
+  // Synthesize full command line from the CompilerInvocation, including "-cc1".
+  SmallVector<const char *, 32> Args{"-cc1"};
+  generateCC1CommandLine(Args, SA);
+
+  // Convert arguments to the return type.
+  return std::vector<std::string>{Args.begin(), Args.end()};
+}
+
+void CompilerInvocation::resetNonModularOptions() {
+  getLangOpts()->resetNonModularOptions();
+  getPreprocessorOpts().resetNonModularOptions();
+}
+
+void CompilerInvocation::clearImplicitModuleBuildOptions() {
+  getLangOpts()->ImplicitModules = false;
+  getHeaderSearchOpts().ImplicitModuleMaps = false;
+  getHeaderSearchOpts().ModuleCachePath.clear();
+  getHeaderSearchOpts().ModulesValidateOncePerBuildSession = false;
+  getHeaderSearchOpts().BuildSessionTimestamp = 0;
+  // The specific values we canonicalize to for pruning don't affect behaviour,
+  /// so use the default values so they may be dropped from the command-line.
+  getHeaderSearchOpts().ModuleCachePruneInterval = 7 * 24 * 60 * 60;
+  getHeaderSearchOpts().ModuleCachePruneAfter = 31 * 24 * 60 * 60;
+}
+
 IntrusiveRefCntPtr<llvm::vfs::FileSystem>
 clang::createVFSFromCompilerInvocation(const CompilerInvocation &CI,
                                        DiagnosticsEngine &Diags) {
   return createVFSFromCompilerInvocation(CI, Diags,
                                          llvm::vfs::getRealFileSystem());
 }
 
 IntrusiveRefCntPtr<llvm::vfs::FileSystem>

clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp

 
 CompilerInvocation
 ModuleDepCollector::makeInvocationForModuleBuildWithoutOutputs(
     const ModuleDeps &Deps,
     llvm::function_ref<void(CompilerInvocation &)> Optimize) const {
   // Make a deep copy of the original Clang invocation.
   CompilerInvocation CI(OriginalInvocation);
 
-  CI.getLangOpts()->resetNonModularOptions();
-  CI.getPreprocessorOpts().resetNonModularOptions();
+  CI.resetNonModularOptions();
+  CI.clearImplicitModuleBuildOptions();
 
   // Remove options incompatible with explicit module build or are likely to
   // differ between identical modules discovered from different translation
   // units.
   CI.getFrontendOpts().Inputs.clear();
   CI.getFrontendOpts().OutputFile.clear();
   CI.getCodeGenOpts().MainFileName.clear();
   CI.getCodeGenOpts().DwarfDebugFlags.clear();
   // Map output paths that affect behaviour to "-" so their existence is in the
   // context hash. The final path will be computed in addOutputPaths.
   if (!CI.getDiagnosticOpts().DiagnosticSerializationFile.empty())
     CI.getDiagnosticOpts().DiagnosticSerializationFile = "-";
   if (!CI.getDependencyOutputOpts().OutputFile.empty())
     CI.getDependencyOutputOpts().OutputFile = "-";
   CI.getDependencyOutputOpts().Targets.clear();
 
   CI.getFrontendOpts().ProgramAction = frontend::GenerateModule;
   CI.getLangOpts()->ModuleName = Deps.ID.ModuleName;
   CI.getFrontendOpts().IsSystemModule = Deps.IsSystem;
 
-  // Disable implicit modules and canonicalize options that are only used by
-  // implicit modules.
-  CI.getLangOpts()->ImplicitModules = false;
-  CI.getHeaderSearchOpts().ImplicitModuleMaps = false;
-  CI.getHeaderSearchOpts().ModuleCachePath.clear();
-  CI.getHeaderSearchOpts().ModulesValidateOncePerBuildSession = false;
-  CI.getHeaderSearchOpts().BuildSessionTimestamp = 0;
-  // The specific values we canonicalize to for pruning don't affect behaviour,
-  /// so use the default values so they will be dropped from the command-line.
-  CI.getHeaderSearchOpts().ModuleCachePruneInterval = 7 * 24 * 60 * 60;
-  CI.getHeaderSearchOpts().ModuleCachePruneAfter = 31 * 24 * 60 * 60;
-
   // Inputs
   InputKind ModuleMapInputKind(CI.getFrontendOpts().DashX.getLanguage(),
                                InputKind::Format::ModuleMap);
   CI.getFrontendOpts().Inputs.emplace_back(Deps.ClangModuleMapFile,
                                            ModuleMapInputKind);
   CI.getFrontendOpts().ModuleMapFiles = Deps.ModuleMapFileDeps;
 
   // Report the prebuilt modules this module uses.
ModuleDepCollector::makeInvocationForModuleBuildWithoutOutputs(
   // reporting dependencies to the clients. Let's make sure we're using
   // **strict** context hash in order to prevent accidental sharing of
   // incompatible modules (e.g. with differences in search paths).
   CI.getHeaderSearchOpts().ModulesStrictContextHash = true;
 
   return CI;
 }
 
-static std::vector<std::string>
-serializeCompilerInvocation(const CompilerInvocation &CI) {
-  // Set up string allocator.
-  llvm::BumpPtrAllocator Alloc;
-  llvm::StringSaver Strings(Alloc);
-  auto SA = [&Strings](const Twine &Arg) { return Strings.save(Arg).data(); };
-
-  // Synthesize full command line from the CompilerInvocation, including "-cc1".
-  SmallVector<const char *, 32> Args{"-cc1"};
-  CI.generateCC1CommandLine(Args, SA);
-
-  // Convert arguments to the return type.
-  return std::vector<std::string>{Args.begin(), Args.end()};
-}
-
 std::vector<std::string> ModuleDeps::getCanonicalCommandLine() const {
-  return serializeCompilerInvocation(BuildInvocation);
+  return BuildInvocation.getCC1CommandLine();
 }
 
 static std::string getModuleContextHash(const ModuleDeps &MD) {
   llvm::HashBuilder<llvm::TruncatedBLAKE3<16>,
                     llvm::support::endianness::native>
       HashBuilder;
   SmallString<32> Scratch;