[Dependency Scanning][Serialization] Do not serialize auxiliary files

The field is only used to store information to be used in finalize stage, in caching builds. When loading scan results from the cache, the entries are finalized already and have the file info encoded in CASIDs already.

Resolves rdar://150307865

Author: artemcm

include/swift/AST/ModuleDependencies.h

@@ -787,11 +787,6 @@ class ModuleDependencyInfo {
     return storage->auxiliaryFiles;
   }
 
-  void
-  setAuxiliaryFiles(const ArrayRef<std::string> auxiliaryFiles) {
-    storage->auxiliaryFiles.assign(auxiliaryFiles.begin(), auxiliaryFiles.end());
-  }
-
   bool isStaticLibrary() const {
     if (auto *detail = getAsSwiftInterfaceModule())
       return detail->isStatic;

include/swift/DependencyScan/SerializedModuleDependencyCacheFormat.h

@@ -80,7 +80,6 @@ using LinkLibrariesArrayIDField = IdentifierIDField;
 using MacroDependenciesArrayIDField = IdentifierIDField;
 using FlagIDArrayIDField = IdentifierIDField;
 using DependencyIDArrayIDField = IdentifierIDField;
-using AuxiliaryFilesArrayIDField = IdentifierIDField;
 using SourceLocationIDArrayIDField = IdentifierIDField;
 
 /// The ID of the top-level block containing the dependency graph
@@ -204,8 +203,7 @@ using ModuleInfoLayout =
                    DependencyIDArrayIDField,       // importedClangModules
                    DependencyIDArrayIDField,       // crossImportOverlayModules
                    DependencyIDArrayIDField,       // swiftOverlayDependencies
-                   ModuleCacheKeyIDField,          // moduleCacheKey
-                   AuxiliaryFilesArrayIDField      // auxiliaryFiles
+                   ModuleCacheKeyIDField           // moduleCacheKey
                    >;
 
 using SwiftInterfaceModuleDetailsLayout =

lib/DependencyScan/ModuleDependencyCacheSerialization.cpp

@@ -229,17 +229,12 @@ bool ModuleDependenciesCacheDeserializer::readGraph(
   std::vector<ScannerImportStatementInfo> importStatements;
   std::vector<ScannerImportStatementInfo> optionalImportStatements;
 
-  std::vector<std::string> auxiliaryFiles;
-
   auto addCommonDependencyInfo =
-      [&importedClangDependenciesIDs, &auxiliaryFiles,
-       &macroDependencies](ModuleDependencyInfo &moduleDep) {
+      [&importedClangDependenciesIDs, &macroDependencies]
+      (ModuleDependencyInfo &moduleDep) {
         // Add qualified dependencies of this module
         moduleDep.setImportedClangDependencies(importedClangDependenciesIDs);
 
-        // Add any auxiliary files
-        moduleDep.setAuxiliaryFiles(auxiliaryFiles);
-
         // Add macro dependencies
         for (const auto &md : macroDependencies)
           moduleDep.addMacroDependency(md.first, md.second.LibraryPath,
@@ -441,8 +436,7 @@ bool ModuleDependenciesCacheDeserializer::readGraph(
           importedSwiftDependenciesIDsArrayID,
           importedClangDependenciesIDsArrayID,
           crossImportOverlayDependenciesIDsArrayID,
-          swiftOverlayDependenciesIDsArrayID, moduleCacheKeyID,
-          AuxiliaryFilesArrayID;
+          swiftOverlayDependenciesIDsArrayID, moduleCacheKeyID;
 
       ModuleInfoLayout::readRecord(Scratch, moduleNameID, moduleImportsArrayID,
                                    optionalImportsArrayID, linkLibraryArrayID,
@@ -451,7 +445,7 @@ bool ModuleDependenciesCacheDeserializer::readGraph(
                                    importedClangDependenciesIDsArrayID,
                                    crossImportOverlayDependenciesIDsArrayID,
                                    swiftOverlayDependenciesIDsArrayID,
-                                   moduleCacheKeyID, AuxiliaryFilesArrayID);
+                                   moduleCacheKeyID);
       auto moduleName = getIdentifier(moduleNameID);
       if (!moduleName)
         llvm::report_fatal_error("Bad module name");
@@ -468,11 +462,6 @@ bool ModuleDependenciesCacheDeserializer::readGraph(
       if (optionalOptionalImportStatementInfos)
         optionalImportStatements = *optionalOptionalImportStatementInfos;
 
-      auto optionalAuxiliaryFiles = getStringArray(AuxiliaryFilesArrayID);
-      if (optionalAuxiliaryFiles)
-        for (const auto &af : *optionalAuxiliaryFiles)
-          auxiliaryFiles.push_back(af);
-
       auto optionalImportedSwiftDependenciesIDs =
           getModuleDependencyIDArray(importedSwiftDependenciesIDsArrayID);
       if (!optionalImportedSwiftDependenciesIDs)
@@ -1042,7 +1031,6 @@ enum ModuleIdentifierArrayKind : uint8_t {
   ImportedClangDependenciesIDs,
   CrossImportOverlayDependenciesIDs,
   SwiftOverlayDependenciesIDs,
-  AuxiliaryFileIDs,
   CompiledModuleCandidates,
   BuildCommandLine,
   SourceFiles,
@@ -1490,9 +1478,7 @@ void ModuleDependenciesCacheSerializer::writeModuleInfo(
           ModuleIdentifierArrayKind::CrossImportOverlayDependenciesIDs),
       getIdentifierArrayID(
           moduleID, ModuleIdentifierArrayKind::SwiftOverlayDependenciesIDs),
-      getIdentifier(dependencyInfo.getModuleCacheKey()),
-      getIdentifierArrayID(moduleID,
-                           ModuleIdentifierArrayKind::AuxiliaryFileIDs));
+      getIdentifier(dependencyInfo.getModuleCacheKey()));
 
   switch (dependencyInfo.getKind()) {
   case swift::ModuleDependencyKind::SwiftInterface: {
@@ -1779,9 +1765,6 @@ void ModuleDependenciesCacheSerializer::collectStringsAndArrays(
           moduleID, ModuleIdentifierArrayKind::SwiftOverlayDependenciesIDs,
           dependencyInfo->getSwiftOverlayDependencies());
 
-      addStringArray(moduleID, ModuleIdentifierArrayKind::AuxiliaryFileIDs,
-                     dependencyInfo->getAuxiliaryFiles());
-
       std::vector<std::string> clangHeaderDependencyNames;
       for (const auto &headerDepID :
            dependencyInfo->getHeaderClangDependencies())