1 files changed, 1347 insertions, 0 deletions
diff --git a/contrib/llvm/tools/clang/lib/Lex/HeaderSearch.cpp b/contrib/llvm/tools/clang/lib/Lex/HeaderSearch.cpp
new file mode 100644
index 0000000..c12d731
--- /dev/null
+++ b/contrib/llvm/tools/clang/lib/Lex/HeaderSearch.cpp
@@ -0,0 +1,1347 @@
+//===--- HeaderSearch.cpp - Resolve Header File Locations ---===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file implements the DirectoryLookup and HeaderSearch interfaces.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Lex/HeaderSearch.h"
+#include "clang/Basic/FileManager.h"
+#include "clang/Basic/IdentifierTable.h"
+#include "clang/Lex/HeaderMap.h"
+#include "clang/Lex/HeaderSearchOptions.h"
+#include "clang/Lex/LexDiagnostic.h"
+#include "clang/Lex/Lexer.h"
+#include "llvm/ADT/APInt.h"
+#include "llvm/ADT/Hashing.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/Support/Capacity.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/raw_ostream.h"
+#include <cstdio>
+#if defined(LLVM_ON_UNIX)
+#include <limits.h>
+#endif
+using namespace clang;
+
+const IdentifierInfo *
+HeaderFileInfo::getControllingMacro(ExternalIdentifierLookup *External) {
+  if (ControllingMacro)
+    return ControllingMacro;
+
+  if (!ControllingMacroID || !External)
+    return nullptr;
+
+  ControllingMacro = External->GetIdentifier(ControllingMacroID);
+  return ControllingMacro;
+}
+
+ExternalHeaderFileInfoSource::~ExternalHeaderFileInfoSource() {}
+
+HeaderSearch::HeaderSearch(IntrusiveRefCntPtr<HeaderSearchOptions> HSOpts,
+                           SourceManager &SourceMgr, DiagnosticsEngine &Diags,
+                           const LangOptions &LangOpts,
+                           const TargetInfo *Target)
+    : HSOpts(HSOpts), Diags(Diags), FileMgr(SourceMgr.getFileManager()),
+      FrameworkMap(64), ModMap(SourceMgr, Diags, LangOpts, Target, *this) {
+  AngledDirIdx = 0;
+  SystemDirIdx = 0;
+  NoCurDirSearch = false;
+
+  ExternalLookup = nullptr;
+  ExternalSource = nullptr;
+  NumIncluded = 0;
+  NumMultiIncludeFileOptzn = 0;
+  NumFrameworkLookups = NumSubFrameworkLookups = 0;
+
+  EnabledModules = LangOpts.Modules;
+}
+
+HeaderSearch::~HeaderSearch() {
+  // Delete headermaps.
+  for (unsigned i = 0, e = HeaderMaps.size(); i != e; ++i)
+    delete HeaderMaps[i].second;
+}
+
+void HeaderSearch::PrintStats() {
+  fprintf(stderr, "\n*** HeaderSearch Stats:\n");
+  fprintf(stderr, "%d files tracked.\n", (int)FileInfo.size());
+  unsigned NumOnceOnlyFiles = 0, MaxNumIncludes = 0, NumSingleIncludedFiles = 0;
+  for (unsigned i = 0, e = FileInfo.size(); i != e; ++i) {
+    NumOnceOnlyFiles += FileInfo[i].isImport;
+    if (MaxNumIncludes < FileInfo[i].NumIncludes)
+      MaxNumIncludes = FileInfo[i].NumIncludes;
+    NumSingleIncludedFiles += FileInfo[i].NumIncludes == 1;
+  }
+  fprintf(stderr, "  %d #import/#pragma once files.\n", NumOnceOnlyFiles);
+  fprintf(stderr, "  %d included exactly once.\n", NumSingleIncludedFiles);
+  fprintf(stderr, "  %d max times a file is included.\n", MaxNumIncludes);
+
+  fprintf(stderr, "  %d #include/#include_next/#import.\n", NumIncluded);
+  fprintf(stderr, "    %d #includes skipped due to"
+          " the multi-include optimization.\n", NumMultiIncludeFileOptzn);
+
+  fprintf(stderr, "%d framework lookups.\n", NumFrameworkLookups);
+  fprintf(stderr, "%d subframework lookups.\n", NumSubFrameworkLookups);
+}
+
+/// CreateHeaderMap - This method returns a HeaderMap for the specified
+/// FileEntry, uniquing them through the 'HeaderMaps' datastructure.
+const HeaderMap *HeaderSearch::CreateHeaderMap(const FileEntry *FE) {
+  // We expect the number of headermaps to be small, and almost always empty.
+  // If it ever grows, use of a linear search should be re-evaluated.
+  if (!HeaderMaps.empty()) {
+    for (unsigned i = 0, e = HeaderMaps.size(); i != e; ++i)
+      // Pointer equality comparison of FileEntries works because they are
+      // already uniqued by inode.
+      if (HeaderMaps[i].first == FE)
+        return HeaderMaps[i].second;
+  }
+
+  if (const HeaderMap *HM = HeaderMap::Create(FE, FileMgr)) {
+    HeaderMaps.push_back(std::make_pair(FE, HM));
+    return HM;
+  }
+
+  return nullptr;
+}
+
+std::string HeaderSearch::getModuleFileName(Module *Module) {
+  return getModuleFileName(Module->Name, Module->ModuleMap->getName());
+}
+
+std::string HeaderSearch::getModuleFileName(StringRef ModuleName,
+                                            StringRef ModuleMapPath) {
+  // If we don't have a module cache path, we can't do anything.
+  if (ModuleCachePath.empty()) 
+    return std::string();
+
+  SmallString<256> Result(ModuleCachePath);
+  llvm::sys::fs::make_absolute(Result);
+
+  if (HSOpts->DisableModuleHash) {
+    llvm::sys::path::append(Result, ModuleName + ".pcm");
+  } else {
+    // Construct the name <ModuleName>-<hash of ModuleMapPath>.pcm which should
+    // be globally unique to this particular module. To avoid false-negatives
+    // on case-insensitive filesystems, we use lower-case, which is safe because
+    // to cause a collision the modules must have the same name, which is an
+    // error if they are imported in the same translation.
+    SmallString<256> AbsModuleMapPath(ModuleMapPath);
+    llvm::sys::fs::make_absolute(AbsModuleMapPath);
+    llvm::APInt Code(64, llvm::hash_value(AbsModuleMapPath.str().lower()));
+    SmallString<128> HashStr;
+    Code.toStringUnsigned(HashStr, /*Radix*/36);
+    llvm::sys::path::append(Result, ModuleName + "-" + HashStr.str() + ".pcm");
+  }
+  return Result.str().str();
+}
+
+Module *HeaderSearch::lookupModule(StringRef ModuleName, bool AllowSearch) {
+  // Look in the module map to determine if there is a module by this name.
+  Module *Module = ModMap.findModule(ModuleName);
+  if (Module || !AllowSearch)
+    return Module;
+  
+  // Look through the various header search paths to load any available module
+  // maps, searching for a module map that describes this module.
+  for (unsigned Idx = 0, N = SearchDirs.size(); Idx != N; ++Idx) {
+    if (SearchDirs[Idx].isFramework()) {
+      // Search for or infer a module map for a framework.
+      SmallString<128> FrameworkDirName;
+      FrameworkDirName += SearchDirs[Idx].getFrameworkDir()->getName();
+      llvm::sys::path::append(FrameworkDirName, ModuleName + ".framework");
+      if (const DirectoryEntry *FrameworkDir 
+            = FileMgr.getDirectory(FrameworkDirName)) {
+        bool IsSystem
+          = SearchDirs[Idx].getDirCharacteristic() != SrcMgr::C_User;
+        Module = loadFrameworkModule(ModuleName, FrameworkDir, IsSystem);
+        if (Module)
+          break;
+      }
+    }
+    
+    // FIXME: Figure out how header maps and module maps will work together.
+    
+    // Only deal with normal search directories.
+    if (!SearchDirs[Idx].isNormalDir())
+      continue;
+
+    bool IsSystem = SearchDirs[Idx].isSystemHeaderDirectory();
+    // Search for a module map file in this directory.
+    if (loadModuleMapFile(SearchDirs[Idx].getDir(), IsSystem,
+                          /*IsFramework*/false) == LMM_NewlyLoaded) {
+      // We just loaded a module map file; check whether the module is
+      // available now.
+      Module = ModMap.findModule(ModuleName);
+      if (Module)
+        break;
+    }
+              
+    // Search for a module map in a subdirectory with the same name as the
+    // module.
+    SmallString<128> NestedModuleMapDirName;
+    NestedModuleMapDirName = SearchDirs[Idx].getDir()->getName();
+    llvm::sys::path::append(NestedModuleMapDirName, ModuleName);
+    if (loadModuleMapFile(NestedModuleMapDirName, IsSystem,
+                          /*IsFramework*/false) == LMM_NewlyLoaded){
+      // If we just loaded a module map file, look for the module again.
+      Module = ModMap.findModule(ModuleName);
+      if (Module)
+        break;
+    }
+
+    // If we've already performed the exhaustive search for module maps in this
+    // search directory, don't do it again.
+    if (SearchDirs[Idx].haveSearchedAllModuleMaps())
+      continue;
+
+    // Load all module maps in the immediate subdirectories of this search
+    // directory.
+    loadSubdirectoryModuleMaps(SearchDirs[Idx]);
+
+    // Look again for the module.
+    Module = ModMap.findModule(ModuleName);
+    if (Module)
+      break;
+  }
+
+  return Module;
+}
+
+//===----------------------------------------------------------------------===//
+// File lookup within a DirectoryLookup scope
+//===----------------------------------------------------------------------===//
+
+/// getName - Return the directory or filename corresponding to this lookup
+/// object.
+const char *DirectoryLookup::getName() const {
+  if (isNormalDir())
+    return getDir()->getName();
+  if (isFramework())
+    return getFrameworkDir()->getName();
+  assert(isHeaderMap() && "Unknown DirectoryLookup");
+  return getHeaderMap()->getFileName();
+}
+
+static const FileEntry *
+getFileAndSuggestModule(HeaderSearch &HS, StringRef FileName,
+                        const DirectoryEntry *Dir, bool IsSystemHeaderDir,
+                        ModuleMap::KnownHeader *SuggestedModule) {
+  // If we have a module map that might map this header, load it and
+  // check whether we'll have a suggestion for a module.
+  HS.hasModuleMap(FileName, Dir, IsSystemHeaderDir);
+  if (SuggestedModule) {
+    const FileEntry *File = HS.getFileMgr().getFile(FileName,
+                                                    /*OpenFile=*/false);
+    if (File) {
+      // If there is a module that corresponds to this header, suggest it.
+      *SuggestedModule = HS.findModuleForHeader(File);
+
+      // FIXME: This appears to be a no-op. We loaded the module map for this
+      // directory at the start of this function.
+      if (!SuggestedModule->getModule() &&
+          HS.hasModuleMap(FileName, Dir, IsSystemHeaderDir))
+        *SuggestedModule = HS.findModuleForHeader(File);
+    }
+
+    return File;
+  }
+
+  return HS.getFileMgr().getFile(FileName, /*openFile=*/true);
+}
+
+/// LookupFile - Lookup the specified file in this search path, returning it
+/// if it exists or returning null if not.
+const FileEntry *DirectoryLookup::LookupFile(
+    StringRef &Filename,
+    HeaderSearch &HS,
+    SmallVectorImpl<char> *SearchPath,
+    SmallVectorImpl<char> *RelativePath,
+    ModuleMap::KnownHeader *SuggestedModule,
+    bool &InUserSpecifiedSystemFramework,
+    bool &HasBeenMapped,
+    SmallVectorImpl<char> &MappedName) const {
+  InUserSpecifiedSystemFramework = false;
+  HasBeenMapped = false;
+
+  SmallString<1024> TmpDir;
+  if (isNormalDir()) {
+    // Concatenate the requested file onto the directory.
+    TmpDir = getDir()->getName();
+    llvm::sys::path::append(TmpDir, Filename);
+    if (SearchPath) {
+      StringRef SearchPathRef(getDir()->getName());
+      SearchPath->clear();
+      SearchPath->append(SearchPathRef.begin(), SearchPathRef.end());
+    }
+    if (RelativePath) {
+      RelativePath->clear();
+      RelativePath->append(Filename.begin(), Filename.end());
+    }
+
+    return getFileAndSuggestModule(HS, TmpDir.str(), getDir(),
+                                   isSystemHeaderDirectory(),
+                                   SuggestedModule);
+  }
+
+  if (isFramework())
+    return DoFrameworkLookup(Filename, HS, SearchPath, RelativePath,
+                             SuggestedModule, InUserSpecifiedSystemFramework);
+
+  assert(isHeaderMap() && "Unknown directory lookup");
+  const HeaderMap *HM = getHeaderMap();
+  SmallString<1024> Path;
+  StringRef Dest = HM->lookupFilename(Filename, Path);
+  if (Dest.empty())
+    return nullptr;
+
+  const FileEntry *Result;
+
+  // Check if the headermap maps the filename to a framework include
+  // ("Foo.h" -> "Foo/Foo.h"), in which case continue header lookup using the
+  // framework include.
+  if (llvm::sys::path::is_relative(Dest)) {
+    MappedName.clear();
+    MappedName.append(Dest.begin(), Dest.end());
+    Filename = StringRef(MappedName.begin(), MappedName.size());
+    HasBeenMapped = true;
+    Result = HM->LookupFile(Filename, HS.getFileMgr());
+
+  } else {
+    Result = HS.getFileMgr().getFile(Dest);
+  }
+
+  if (Result) {
+    if (SearchPath) {
+      StringRef SearchPathRef(getName());
+      SearchPath->clear();
+      SearchPath->append(SearchPathRef.begin(), SearchPathRef.end());
+    }
+    if (RelativePath) {
+      RelativePath->clear();
+      RelativePath->append(Filename.begin(), Filename.end());
+    }
+  }
+  return Result;
+}
+
+/// \brief Given a framework directory, find the top-most framework directory.
+///
+/// \param FileMgr The file manager to use for directory lookups.
+/// \param DirName The name of the framework directory.
+/// \param SubmodulePath Will be populated with the submodule path from the
+/// returned top-level module to the originally named framework.
+static const DirectoryEntry *
+getTopFrameworkDir(FileManager &FileMgr, StringRef DirName,
+                   SmallVectorImpl<std::string> &SubmodulePath) {
+  assert(llvm::sys::path::extension(DirName) == ".framework" &&
+         "Not a framework directory");
+
+  // Note: as an egregious but useful hack we use the real path here, because
+  // frameworks moving between top-level frameworks to embedded frameworks tend
+  // to be symlinked, and we base the logical structure of modules on the
+  // physical layout. In particular, we need to deal with crazy includes like
+  //
+  //   #include <Foo/Frameworks/Bar.framework/Headers/Wibble.h>
+  //
+  // where 'Bar' used to be embedded in 'Foo', is now a top-level framework
+  // which one should access with, e.g.,
+  //
+  //   #include <Bar/Wibble.h>
+  //
+  // Similar issues occur when a top-level framework has moved into an
+  // embedded framework.
+  const DirectoryEntry *TopFrameworkDir = FileMgr.getDirectory(DirName);
+  DirName = FileMgr.getCanonicalName(TopFrameworkDir);
+  do {
+    // Get the parent directory name.
+    DirName = llvm::sys::path::parent_path(DirName);
+    if (DirName.empty())
+      break;
+
+    // Determine whether this directory exists.
+    const DirectoryEntry *Dir = FileMgr.getDirectory(DirName);
+    if (!Dir)
+      break;
+
+    // If this is a framework directory, then we're a subframework of this
+    // framework.
+    if (llvm::sys::path::extension(DirName) == ".framework") {
+      SubmodulePath.push_back(llvm::sys::path::stem(DirName));
+      TopFrameworkDir = Dir;
+    }
+  } while (true);
+
+  return TopFrameworkDir;
+}
+
+/// DoFrameworkLookup - Do a lookup of the specified file in the current
+/// DirectoryLookup, which is a framework directory.
+const FileEntry *DirectoryLookup::DoFrameworkLookup(
+    StringRef Filename,
+    HeaderSearch &HS,
+    SmallVectorImpl<char> *SearchPath,
+    SmallVectorImpl<char> *RelativePath,
+    ModuleMap::KnownHeader *SuggestedModule,
+    bool &InUserSpecifiedSystemFramework) const
+{
+  FileManager &FileMgr = HS.getFileMgr();
+
+  // Framework names must have a '/' in the filename.
+  size_t SlashPos = Filename.find('/');
+  if (SlashPos == StringRef::npos) return nullptr;
+
+  // Find out if this is the home for the specified framework, by checking
+  // HeaderSearch.  Possible answers are yes/no and unknown.
+  HeaderSearch::FrameworkCacheEntry &CacheEntry =
+    HS.LookupFrameworkCache(Filename.substr(0, SlashPos));
+
+  // If it is known and in some other directory, fail.
+  if (CacheEntry.Directory && CacheEntry.Directory != getFrameworkDir())
+    return nullptr;
+
+  // Otherwise, construct the path to this framework dir.
+
+  // FrameworkName = "/System/Library/Frameworks/"
+  SmallString<1024> FrameworkName;
+  FrameworkName += getFrameworkDir()->getName();
+  if (FrameworkName.empty() || FrameworkName.back() != '/')
+    FrameworkName.push_back('/');
+
+  // FrameworkName = "/System/Library/Frameworks/Cocoa"
+  StringRef ModuleName(Filename.begin(), SlashPos);
+  FrameworkName += ModuleName;
+
+  // FrameworkName = "/System/Library/Frameworks/Cocoa.framework/"
+  FrameworkName += ".framework/";
+
+  // If the cache entry was unresolved, populate it now.
+  if (!CacheEntry.Directory) {
+    HS.IncrementFrameworkLookupCount();
+
+    // If the framework dir doesn't exist, we fail.
+    const DirectoryEntry *Dir = FileMgr.getDirectory(FrameworkName.str());
+    if (!Dir) return nullptr;
+
+    // Otherwise, if it does, remember that this is the right direntry for this
+    // framework.
+    CacheEntry.Directory = getFrameworkDir();
+
+    // If this is a user search directory, check if the framework has been
+    // user-specified as a system framework.
+    if (getDirCharacteristic() == SrcMgr::C_User) {
+      SmallString<1024> SystemFrameworkMarker(FrameworkName);
+      SystemFrameworkMarker += ".system_framework";
+      if (llvm::sys::fs::exists(SystemFrameworkMarker.str())) {
+        CacheEntry.IsUserSpecifiedSystemFramework = true;
+      }
+    }
+  }
+
+  // Set the 'user-specified system framework' flag.
+  InUserSpecifiedSystemFramework = CacheEntry.IsUserSpecifiedSystemFramework;
+
+  if (RelativePath) {
+    RelativePath->clear();
+    RelativePath->append(Filename.begin()+SlashPos+1, Filename.end());
+  }
+  
+  // Check "/System/Library/Frameworks/Cocoa.framework/Headers/file.h"
+  unsigned OrigSize = FrameworkName.size();
+
+  FrameworkName += "Headers/";
+
+  if (SearchPath) {
+    SearchPath->clear();
+    // Without trailing '/'.
+    SearchPath->append(FrameworkName.begin(), FrameworkName.end()-1);
+  }
+
+  FrameworkName.append(Filename.begin()+SlashPos+1, Filename.end());
+  const FileEntry *FE = FileMgr.getFile(FrameworkName.str(),
+                                        /*openFile=*/!SuggestedModule);
+  if (!FE) {
+    // Check "/System/Library/Frameworks/Cocoa.framework/PrivateHeaders/file.h"
+    const char *Private = "Private";
+    FrameworkName.insert(FrameworkName.begin()+OrigSize, Private,
+                         Private+strlen(Private));
+    if (SearchPath)
+      SearchPath->insert(SearchPath->begin()+OrigSize, Private,
+                         Private+strlen(Private));
+
+    FE = FileMgr.getFile(FrameworkName.str(), /*openFile=*/!SuggestedModule);
+  }
+
+  // If we found the header and are allowed to suggest a module, do so now.
+  if (FE && SuggestedModule) {
+    // Find the framework in which this header occurs.
+    StringRef FrameworkPath = FE->getDir()->getName();
+    bool FoundFramework = false;
+    do {
+      // Determine whether this directory exists.
+      const DirectoryEntry *Dir = FileMgr.getDirectory(FrameworkPath);
+      if (!Dir)
+        break;
+
+      // If this is a framework directory, then we're a subframework of this
+      // framework.
+      if (llvm::sys::path::extension(FrameworkPath) == ".framework") {
+        FoundFramework = true;
+        break;
+      }
+
+      // Get the parent directory name.
+      FrameworkPath = llvm::sys::path::parent_path(FrameworkPath);
+      if (FrameworkPath.empty())
+        break;
+    } while (true);
+
+    if (FoundFramework) {
+      // Find the top-level framework based on this framework.
+      SmallVector<std::string, 4> SubmodulePath;
+      const DirectoryEntry *TopFrameworkDir
+        = ::getTopFrameworkDir(FileMgr, FrameworkPath, SubmodulePath);
+
+      // Determine the name of the top-level framework.
+      StringRef ModuleName = llvm::sys::path::stem(TopFrameworkDir->getName());
+
+      // Load this framework module. If that succeeds, find the suggested module
+      // for this header, if any.
+      bool IsSystem = getDirCharacteristic() != SrcMgr::C_User;
+      if (HS.loadFrameworkModule(ModuleName, TopFrameworkDir, IsSystem)) {
+        *SuggestedModule = HS.findModuleForHeader(FE);
+      }
+    } else {
+      *SuggestedModule = HS.findModuleForHeader(FE);
+    }
+  }
+  return FE;
+}
+
+void HeaderSearch::setTarget(const TargetInfo &Target) {
+  ModMap.setTarget(Target);
+}
+
+
+//===----------------------------------------------------------------------===//
+// Header File Location.
+//===----------------------------------------------------------------------===//
+
+/// \brief Return true with a diagnostic if the file that MSVC would have found
+/// fails to match the one that Clang would have found with MSVC header search
+/// disabled.
+static bool checkMSVCHeaderSearch(DiagnosticsEngine &Diags,
+                                  const FileEntry *MSFE, const FileEntry *FE,
+                                  SourceLocation IncludeLoc) {
+  if (MSFE && FE != MSFE) {
+    Diags.Report(IncludeLoc, diag::ext_pp_include_search_ms) << MSFE->getName();
+    return true;
+  }
+  return false;
+}
+
+static const char *copyString(StringRef Str, llvm::BumpPtrAllocator &Alloc) {
+  assert(!Str.empty());
+  char *CopyStr = Alloc.Allocate<char>(Str.size()+1);
+  std::copy(Str.begin(), Str.end(), CopyStr);
+  CopyStr[Str.size()] = '\0';
+  return CopyStr;
+}
+
+/// LookupFile - Given a "foo" or \<foo> reference, look up the indicated file,
+/// return null on failure.  isAngled indicates whether the file reference is
+/// for system \#include's or not (i.e. using <> instead of ""). Includers, if
+/// non-empty, indicates where the \#including file(s) are, in case a relative
+/// search is needed. Microsoft mode will pass all \#including files.
+const FileEntry *HeaderSearch::LookupFile(
+    StringRef Filename, SourceLocation IncludeLoc, bool isAngled,
+    const DirectoryLookup *FromDir, const DirectoryLookup *&CurDir,
+    ArrayRef<const FileEntry *> Includers, SmallVectorImpl<char> *SearchPath,
+    SmallVectorImpl<char> *RelativePath,
+    ModuleMap::KnownHeader *SuggestedModule, bool SkipCache) {
+  if (!HSOpts->ModuleMapFiles.empty()) {
+    // Preload all explicitly specified module map files. This enables modules
+    // map files lying in a directory structure separate from the header files
+    // that they describe. These cannot be loaded lazily upon encountering a
+    // header file, as there is no other known mapping from a header file to its
+    // module map file.
+    for (llvm::SetVector<std::string>::iterator
+             I = HSOpts->ModuleMapFiles.begin(),
+             E = HSOpts->ModuleMapFiles.end();
+         I != E; ++I) {
+      const FileEntry *File = FileMgr.getFile(*I);
+      if (!File)
+        continue;
+      loadModuleMapFile(File, /*IsSystem=*/false);
+    }
+    HSOpts->ModuleMapFiles.clear();
+  }
+
+  if (SuggestedModule)
+    *SuggestedModule = ModuleMap::KnownHeader();
+    
+  // If 'Filename' is absolute, check to see if it exists and no searching.
+  if (llvm::sys::path::is_absolute(Filename)) {
+    CurDir = nullptr;
+
+    // If this was an #include_next "/absolute/file", fail.
+    if (FromDir) return nullptr;
+
+    if (SearchPath)
+      SearchPath->clear();
+    if (RelativePath) {
+      RelativePath->clear();
+      RelativePath->append(Filename.begin(), Filename.end());
+    }
+    // Otherwise, just return the file.
+    return FileMgr.getFile(Filename, /*openFile=*/true);
+  }
+
+  // This is the header that MSVC's header search would have found.
+  const FileEntry *MSFE = nullptr;
+  ModuleMap::KnownHeader MSSuggestedModule;
+
+  // Unless disabled, check to see if the file is in the #includer's
+  // directory.  This cannot be based on CurDir, because each includer could be
+  // a #include of a subdirectory (#include "foo/bar.h") and a subsequent
+  // include of "baz.h" should resolve to "whatever/foo/baz.h".
+  // This search is not done for <> headers.
+  if (!Includers.empty() && !isAngled && !NoCurDirSearch) {
+    SmallString<1024> TmpDir;
+    for (ArrayRef<const FileEntry *>::iterator I = Includers.begin(),
+                                               E = Includers.end();
+         I != E; ++I) {
+      const FileEntry *Includer = *I;
+      // Concatenate the requested file onto the directory.
+      // FIXME: Portability.  Filename concatenation should be in sys::Path.
+      TmpDir = Includer->getDir()->getName();
+      TmpDir.push_back('/');
+      TmpDir.append(Filename.begin(), Filename.end());
+
+      // FIXME: We don't cache the result of getFileInfo across the call to
+      // getFileAndSuggestModule, because it's a reference to an element of
+      // a container that could be reallocated across this call.
+      bool IncluderIsSystemHeader =
+          getFileInfo(Includer).DirInfo != SrcMgr::C_User;
+      if (const FileEntry *FE =
+              getFileAndSuggestModule(*this, TmpDir.str(), Includer->getDir(),
+                                      IncluderIsSystemHeader,
+                                      SuggestedModule)) {
+        // Leave CurDir unset.
+        // This file is a system header or C++ unfriendly if the old file is.
+        //
+        // Note that we only use one of FromHFI/ToHFI at once, due to potential
+        // reallocation of the underlying vector potentially making the first
+        // reference binding dangling.
+        HeaderFileInfo &FromHFI = getFileInfo(Includer);
+        unsigned DirInfo = FromHFI.DirInfo;
+        bool IndexHeaderMapHeader = FromHFI.IndexHeaderMapHeader;
+        StringRef Framework = FromHFI.Framework;
+
+        HeaderFileInfo &ToHFI = getFileInfo(FE);
+        ToHFI.DirInfo = DirInfo;
+        ToHFI.IndexHeaderMapHeader = IndexHeaderMapHeader;
+        ToHFI.Framework = Framework;
+
+        if (SearchPath) {
+          StringRef SearchPathRef(Includer->getDir()->getName());
+          SearchPath->clear();
+          SearchPath->append(SearchPathRef.begin(), SearchPathRef.end());
+        }
+        if (RelativePath) {
+          RelativePath->clear();
+          RelativePath->append(Filename.begin(), Filename.end());
+        }
+        if (I == Includers.begin())
+          return FE;
+
+        // Otherwise, we found the path via MSVC header search rules.  If
+        // -Wmsvc-include is enabled, we have to keep searching to see if we
+        // would've found this header in -I or -isystem directories.
+        if (Diags.isIgnored(diag::ext_pp_include_search_ms, IncludeLoc)) {
+          return FE;
+        } else {
+          MSFE = FE;
+          if (SuggestedModule) {
+            MSSuggestedModule = *SuggestedModule;
+            *SuggestedModule = ModuleMap::KnownHeader();
+          }
+          break;
+        }
+      }
+    }
+  }
+
+  CurDir = nullptr;
+
+  // If this is a system #include, ignore the user #include locs.
+  unsigned i = isAngled ? AngledDirIdx : 0;
+
+  // If this is a #include_next request, start searching after the directory the
+  // file was found in.
+  if (FromDir)
+    i = FromDir-&SearchDirs[0];
+
+  // Cache all of the lookups performed by this method.  Many headers are
+  // multiply included, and the "pragma once" optimization prevents them from
+  // being relex/pp'd, but they would still have to search through a
+  // (potentially huge) series of SearchDirs to find it.
+  LookupFileCacheInfo &CacheLookup =
+    LookupFileCache.GetOrCreateValue(Filename).getValue();
+
+  // If the entry has been previously looked up, the first value will be
+  // non-zero.  If the value is equal to i (the start point of our search), then
+  // this is a matching hit.
+  if (!SkipCache && CacheLookup.StartIdx == i+1) {
+    // Skip querying potentially lots of directories for this lookup.
+    i = CacheLookup.HitIdx;
+    if (CacheLookup.MappedName)
+      Filename = CacheLookup.MappedName;
+  } else {
+    // Otherwise, this is the first query, or the previous query didn't match
+    // our search start.  We will fill in our found location below, so prime the
+    // start point value.
+    CacheLookup.reset(/*StartIdx=*/i+1);
+  }
+
+  SmallString<64> MappedName;
+
+  // Check each directory in sequence to see if it contains this file.
+  for (; i != SearchDirs.size(); ++i) {
+    bool InUserSpecifiedSystemFramework = false;
+    bool HasBeenMapped = false;
+    const FileEntry *FE =
+      SearchDirs[i].LookupFile(Filename, *this, SearchPath, RelativePath,
+                               SuggestedModule, InUserSpecifiedSystemFramework,
+                               HasBeenMapped, MappedName);
+    if (HasBeenMapped) {
+      CacheLookup.MappedName =
+          copyString(Filename, LookupFileCache.getAllocator());
+    }
+    if (!FE) continue;
+
+    CurDir = &SearchDirs[i];
+
+    // This file is a system header or C++ unfriendly if the dir is.
+    HeaderFileInfo &HFI = getFileInfo(FE);
+    HFI.DirInfo = CurDir->getDirCharacteristic();
+
+    // If the directory characteristic is User but this framework was
+    // user-specified to be treated as a system framework, promote the
+    // characteristic.
+    if (HFI.DirInfo == SrcMgr::C_User && InUserSpecifiedSystemFramework)
+      HFI.DirInfo = SrcMgr::C_System;
+
+    // If the filename matches a known system header prefix, override
+    // whether the file is a system header.
+    for (unsigned j = SystemHeaderPrefixes.size(); j; --j) {
+      if (Filename.startswith(SystemHeaderPrefixes[j-1].first)) {
+        HFI.DirInfo = SystemHeaderPrefixes[j-1].second ? SrcMgr::C_System
+                                                       : SrcMgr::C_User;
+        break;
+      }
+    }
+
+    // If this file is found in a header map and uses the framework style of
+    // includes, then this header is part of a framework we're building.
+    if (CurDir->isIndexHeaderMap()) {
+      size_t SlashPos = Filename.find('/');
+      if (SlashPos != StringRef::npos) {
+        HFI.IndexHeaderMapHeader = 1;
+        HFI.Framework = getUniqueFrameworkName(StringRef(Filename.begin(), 
+                                                         SlashPos));
+      }
+    }
+
+    if (checkMSVCHeaderSearch(Diags, MSFE, FE, IncludeLoc)) {
+      if (SuggestedModule)
+        *SuggestedModule = MSSuggestedModule;
+      return MSFE;
+    }
+
+    // Remember this location for the next lookup we do.
+    CacheLookup.HitIdx = i;
+    return FE;
+  }
+
+  // If we are including a file with a quoted include "foo.h" from inside
+  // a header in a framework that is currently being built, and we couldn't
+  // resolve "foo.h" any other way, change the include to <Foo/foo.h>, where
+  // "Foo" is the name of the framework in which the including header was found.
+  if (!Includers.empty() && !isAngled &&
+      Filename.find('/') == StringRef::npos) {
+    HeaderFileInfo &IncludingHFI = getFileInfo(Includers.front());
+    if (IncludingHFI.IndexHeaderMapHeader) {
+      SmallString<128> ScratchFilename;
+      ScratchFilename += IncludingHFI.Framework;
+      ScratchFilename += '/';
+      ScratchFilename += Filename;
+
+      const FileEntry *FE = LookupFile(
+          ScratchFilename, IncludeLoc, /*isAngled=*/true, FromDir, CurDir,
+          Includers.front(), SearchPath, RelativePath, SuggestedModule);
+
+      if (checkMSVCHeaderSearch(Diags, MSFE, FE, IncludeLoc)) {
+        if (SuggestedModule)
+          *SuggestedModule = MSSuggestedModule;
+        return MSFE;
+      }
+
+      LookupFileCacheInfo &CacheLookup 
+        = LookupFileCache.GetOrCreateValue(Filename).getValue();
+      CacheLookup.HitIdx
+        = LookupFileCache.GetOrCreateValue(ScratchFilename).getValue().HitIdx;
+      // FIXME: SuggestedModule.
+      return FE;
+    }
+  }
+
+  if (checkMSVCHeaderSearch(Diags, MSFE, nullptr, IncludeLoc)) {
+    if (SuggestedModule)
+      *SuggestedModule = MSSuggestedModule;
+    return MSFE;
+  }
+
+  // Otherwise, didn't find it. Remember we didn't find this.
+  CacheLookup.HitIdx = SearchDirs.size();
+  return nullptr;
+}
+
+/// LookupSubframeworkHeader - Look up a subframework for the specified
+/// \#include file.  For example, if \#include'ing <HIToolbox/HIToolbox.h> from
+/// within ".../Carbon.framework/Headers/Carbon.h", check to see if HIToolbox
+/// is a subframework within Carbon.framework.  If so, return the FileEntry
+/// for the designated file, otherwise return null.
+const FileEntry *HeaderSearch::
+LookupSubframeworkHeader(StringRef Filename,
+                         const FileEntry *ContextFileEnt,
+                         SmallVectorImpl<char> *SearchPath,
+                         SmallVectorImpl<char> *RelativePath,
+                         ModuleMap::KnownHeader *SuggestedModule) {
+  assert(ContextFileEnt && "No context file?");
+
+  // Framework names must have a '/' in the filename.  Find it.
+  // FIXME: Should we permit '\' on Windows?
+  size_t SlashPos = Filename.find('/');
+  if (SlashPos == StringRef::npos) return nullptr;
+
+  // Look up the base framework name of the ContextFileEnt.
+  const char *ContextName = ContextFileEnt->getName();
+
+  // If the context info wasn't a framework, couldn't be a subframework.
+  const unsigned DotFrameworkLen = 10;
+  const char *FrameworkPos = strstr(ContextName, ".framework");
+  if (FrameworkPos == nullptr ||
+      (FrameworkPos[DotFrameworkLen] != '/' && 
+       FrameworkPos[DotFrameworkLen] != '\\'))
+    return nullptr;
+
+  SmallString<1024> FrameworkName(ContextName, FrameworkPos+DotFrameworkLen+1);
+
+  // Append Frameworks/HIToolbox.framework/
+  FrameworkName += "Frameworks/";
+  FrameworkName.append(Filename.begin(), Filename.begin()+SlashPos);
+  FrameworkName += ".framework/";
+
+  llvm::StringMapEntry<FrameworkCacheEntry> &CacheLookup =
+    FrameworkMap.GetOrCreateValue(Filename.substr(0, SlashPos));
+
+  // Some other location?
+  if (CacheLookup.getValue().Directory &&
+      CacheLookup.getKeyLength() == FrameworkName.size() &&
+      memcmp(CacheLookup.getKeyData(), &FrameworkName[0],
+             CacheLookup.getKeyLength()) != 0)
+    return nullptr;
+
+  // Cache subframework.
+  if (!CacheLookup.getValue().Directory) {
+    ++NumSubFrameworkLookups;
+
+    // If the framework dir doesn't exist, we fail.
+    const DirectoryEntry *Dir = FileMgr.getDirectory(FrameworkName.str());
+    if (!Dir) return nullptr;
+
+    // Otherwise, if it does, remember that this is the right direntry for this
+    // framework.
+    CacheLookup.getValue().Directory = Dir;
+  }
+
+  const FileEntry *FE = nullptr;
+
+  if (RelativePath) {
+    RelativePath->clear();
+    RelativePath->append(Filename.begin()+SlashPos+1, Filename.end());
+  }
+
+  // Check ".../Frameworks/HIToolbox.framework/Headers/HIToolbox.h"
+  SmallString<1024> HeadersFilename(FrameworkName);
+  HeadersFilename += "Headers/";
+  if (SearchPath) {
+    SearchPath->clear();
+    // Without trailing '/'.
+    SearchPath->append(HeadersFilename.begin(), HeadersFilename.end()-1);
+  }
+
+  HeadersFilename.append(Filename.begin()+SlashPos+1, Filename.end());
+  if (!(FE = FileMgr.getFile(HeadersFilename.str(), /*openFile=*/true))) {
+
+    // Check ".../Frameworks/HIToolbox.framework/PrivateHeaders/HIToolbox.h"
+    HeadersFilename = FrameworkName;
+    HeadersFilename += "PrivateHeaders/";
+    if (SearchPath) {
+      SearchPath->clear();
+      // Without trailing '/'.
+      SearchPath->append(HeadersFilename.begin(), HeadersFilename.end()-1);
+    }
+
+    HeadersFilename.append(Filename.begin()+SlashPos+1, Filename.end());
+    if (!(FE = FileMgr.getFile(HeadersFilename.str(), /*openFile=*/true)))
+      return nullptr;
+  }
+
+  // This file is a system header or C++ unfriendly if the old file is.
+  //
+  // Note that the temporary 'DirInfo' is required here, as either call to
+  // getFileInfo could resize the vector and we don't want to rely on order
+  // of evaluation.
+  unsigned DirInfo = getFileInfo(ContextFileEnt).DirInfo;
+  getFileInfo(FE).DirInfo = DirInfo;
+
+  // If we're supposed to suggest a module, look for one now.
+  if (SuggestedModule) {
+    // Find the top-level framework based on this framework.
+    FrameworkName.pop_back(); // remove the trailing '/'
+    SmallVector<std::string, 4> SubmodulePath;
+    const DirectoryEntry *TopFrameworkDir
+      = ::getTopFrameworkDir(FileMgr, FrameworkName, SubmodulePath);
+    
+    // Determine the name of the top-level framework.
+    StringRef ModuleName = llvm::sys::path::stem(TopFrameworkDir->getName());
+
+    // Load this framework module. If that succeeds, find the suggested module
+    // for this header, if any.
+    bool IsSystem = false;
+    if (loadFrameworkModule(ModuleName, TopFrameworkDir, IsSystem)) {
+      *SuggestedModule = findModuleForHeader(FE);
+    }
+  }
+
+  return FE;
+}
+
+/// \brief Helper static function to normalize a path for injection into
+/// a synthetic header.
+/*static*/ std::string
+HeaderSearch::NormalizeDashIncludePath(StringRef File, FileManager &FileMgr) {
+  // Implicit include paths should be resolved relative to the current
+  // working directory first, and then use the regular header search
+  // mechanism. The proper way to handle this is to have the
+  // predefines buffer located at the current working directory, but
+  // it has no file entry. For now, workaround this by using an
+  // absolute path if we find the file here, and otherwise letting
+  // header search handle it.
+  SmallString<128> Path(File);
+  llvm::sys::fs::make_absolute(Path);
+  bool exists;
+  if (llvm::sys::fs::exists(Path.str(), exists) || !exists)
+    Path = File;
+  else if (exists)
+    FileMgr.getFile(File);
+
+  return Lexer::Stringify(Path.str());
+}
+
+//===----------------------------------------------------------------------===//
+// File Info Management.
+//===----------------------------------------------------------------------===//
+
+/// \brief Merge the header file info provided by \p OtherHFI into the current
+/// header file info (\p HFI)
+static void mergeHeaderFileInfo(HeaderFileInfo &HFI, 
+                                const HeaderFileInfo &OtherHFI) {
+  HFI.isImport |= OtherHFI.isImport;
+  HFI.isPragmaOnce |= OtherHFI.isPragmaOnce;
+  HFI.isModuleHeader |= OtherHFI.isModuleHeader;
+  HFI.NumIncludes += OtherHFI.NumIncludes;
+  
+  if (!HFI.ControllingMacro && !HFI.ControllingMacroID) {
+    HFI.ControllingMacro = OtherHFI.ControllingMacro;
+    HFI.ControllingMacroID = OtherHFI.ControllingMacroID;
+  }
+  
+  if (OtherHFI.External) {
+    HFI.DirInfo = OtherHFI.DirInfo;
+    HFI.External = OtherHFI.External;
+    HFI.IndexHeaderMapHeader = OtherHFI.IndexHeaderMapHeader;
+  }
+
+  if (HFI.Framework.empty())
+    HFI.Framework = OtherHFI.Framework;
+  
+  HFI.Resolved = true;
+}
+                                
+/// getFileInfo - Return the HeaderFileInfo structure for the specified
+/// FileEntry.
+HeaderFileInfo &HeaderSearch::getFileInfo(const FileEntry *FE) {
+  if (FE->getUID() >= FileInfo.size())
+    FileInfo.resize(FE->getUID()+1);
+  
+  HeaderFileInfo &HFI = FileInfo[FE->getUID()];
+  if (ExternalSource && !HFI.Resolved)
+    mergeHeaderFileInfo(HFI, ExternalSource->GetHeaderFileInfo(FE));
+  HFI.IsValid = 1;
+  return HFI;
+}
+
+bool HeaderSearch::tryGetFileInfo(const FileEntry *FE, HeaderFileInfo &Result) const {
+  if (FE->getUID() >= FileInfo.size())
+    return false;
+  const HeaderFileInfo &HFI = FileInfo[FE->getUID()];
+  if (HFI.IsValid) {
+    Result = HFI;
+    return true;
+  }
+  return false;
+}
+
+bool HeaderSearch::isFileMultipleIncludeGuarded(const FileEntry *File) {
+  // Check if we've ever seen this file as a header.
+  if (File->getUID() >= FileInfo.size())
+    return false;
+
+  // Resolve header file info from the external source, if needed.
+  HeaderFileInfo &HFI = FileInfo[File->getUID()];
+  if (ExternalSource && !HFI.Resolved)
+    mergeHeaderFileInfo(HFI, ExternalSource->GetHeaderFileInfo(File));
+
+  return HFI.isPragmaOnce || HFI.isImport ||
+      HFI.ControllingMacro || HFI.ControllingMacroID;
+}
+
+void HeaderSearch::MarkFileModuleHeader(const FileEntry *FE,
+                                        ModuleMap::ModuleHeaderRole Role,
+                                        bool isCompilingModuleHeader) {
+  if (FE->getUID() >= FileInfo.size())
+    FileInfo.resize(FE->getUID()+1);
+
+  HeaderFileInfo &HFI = FileInfo[FE->getUID()];
+  HFI.isModuleHeader = true;
+  HFI.isCompilingModuleHeader = isCompilingModuleHeader;
+  HFI.setHeaderRole(Role);
+}
+
+bool HeaderSearch::ShouldEnterIncludeFile(const FileEntry *File, bool isImport){
+  ++NumIncluded; // Count # of attempted #includes.
+
+  // Get information about this file.
+  HeaderFileInfo &FileInfo = getFileInfo(File);
+
+  // If this is a #import directive, check that we have not already imported
+  // this header.
+  if (isImport) {
+    // If this has already been imported, don't import it again.
+    FileInfo.isImport = true;
+
+    // Has this already been #import'ed or #include'd?
+    if (FileInfo.NumIncludes) return false;
+  } else {
+    // Otherwise, if this is a #include of a file that was previously #import'd
+    // or if this is the second #include of a #pragma once file, ignore it.
+    if (FileInfo.isImport)
+      return false;
+  }
+
+  // Next, check to see if the file is wrapped with #ifndef guards.  If so, and
+  // if the macro that guards it is defined, we know the #include has no effect.
+  if (const IdentifierInfo *ControllingMacro
+      = FileInfo.getControllingMacro(ExternalLookup))
+    if (ControllingMacro->hasMacroDefinition()) {
+      ++NumMultiIncludeFileOptzn;
+      return false;
+    }
+
+  // Increment the number of times this file has been included.
+  ++FileInfo.NumIncludes;
+
+  return true;
+}
+
+size_t HeaderSearch::getTotalMemory() const {
+  return SearchDirs.capacity()
+    + llvm::capacity_in_bytes(FileInfo)
+    + llvm::capacity_in_bytes(HeaderMaps)
+    + LookupFileCache.getAllocator().getTotalMemory()
+    + FrameworkMap.getAllocator().getTotalMemory();
+}
+
+StringRef HeaderSearch::getUniqueFrameworkName(StringRef Framework) {
+  return FrameworkNames.GetOrCreateValue(Framework).getKey();
+}
+
+bool HeaderSearch::hasModuleMap(StringRef FileName, 
+                                const DirectoryEntry *Root,
+                                bool IsSystem) {
+  if (!enabledModules())
+    return false;
+
+  SmallVector<const DirectoryEntry *, 2> FixUpDirectories;
+  
+  StringRef DirName = FileName;
+  do {
+    // Get the parent directory name.
+    DirName = llvm::sys::path::parent_path(DirName);
+    if (DirName.empty())
+      return false;
+
+    // Determine whether this directory exists.
+    const DirectoryEntry *Dir = FileMgr.getDirectory(DirName);
+    if (!Dir)
+      return false;
+
+    // Try to load the module map file in this directory.
+    switch (loadModuleMapFile(Dir, IsSystem, /*IsFramework*/false)) {
+    case LMM_NewlyLoaded:
+    case LMM_AlreadyLoaded:
+      // Success. All of the directories we stepped through inherit this module
+      // map file.
+      for (unsigned I = 0, N = FixUpDirectories.size(); I != N; ++I)
+        DirectoryHasModuleMap[FixUpDirectories[I]] = true;
+      return true;
+
+    case LMM_NoDirectory:
+    case LMM_InvalidModuleMap:
+      break;
+    }
+
+    // If we hit the top of our search, we're done.
+    if (Dir == Root)
+      return false;
+        
+    // Keep track of all of the directories we checked, so we can mark them as
+    // having module maps if we eventually do find a module map.
+    FixUpDirectories.push_back(Dir);
+  } while (true);
+}
+
+ModuleMap::KnownHeader
+HeaderSearch::findModuleForHeader(const FileEntry *File) const {
+  if (ExternalSource) {
+    // Make sure the external source has handled header info about this file,
+    // which includes whether the file is part of a module.
+    (void)getFileInfo(File);
+  }
+  return ModMap.findModuleForHeader(File);
+}
+
+static const FileEntry *getPrivateModuleMap(StringRef ModuleMapPath,
+                                            const DirectoryEntry *Directory,
+                                            FileManager &FileMgr) {
+  StringRef Filename = llvm::sys::path::filename(ModuleMapPath);
+  SmallString<128>  PrivateFilename(Directory->getName());
+  if (Filename == "module.map")
+    llvm::sys::path::append(PrivateFilename, "module_private.map");
+  else if (Filename == "module.modulemap")
+    llvm::sys::path::append(PrivateFilename, "module.private.modulemap");
+  else
+    return nullptr;
+  return FileMgr.getFile(PrivateFilename);
+}
+
+bool HeaderSearch::loadModuleMapFile(const FileEntry *File, bool IsSystem) {
+  switch (loadModuleMapFileImpl(File, IsSystem)) {
+  case LMM_AlreadyLoaded:
+  case LMM_NewlyLoaded:
+    return false;
+  case LMM_NoDirectory:
+  case LMM_InvalidModuleMap:
+    return true;
+  }
+  llvm_unreachable("Unknown load module map result");
+}
+
+HeaderSearch::LoadModuleMapResult
+HeaderSearch::loadModuleMapFileImpl(const FileEntry *File, bool IsSystem) {
+  assert(File && "expected FileEntry");
+
+  const DirectoryEntry *Dir = File->getDir();
+  auto KnownDir = DirectoryHasModuleMap.find(Dir);
+  if (KnownDir != DirectoryHasModuleMap.end())
+    return KnownDir->second ? LMM_AlreadyLoaded : LMM_InvalidModuleMap;
+
+  if (ModMap.parseModuleMapFile(File, IsSystem)) {
+    DirectoryHasModuleMap[Dir] = false;
+    return LMM_InvalidModuleMap;
+  }
+
+  // Try to load a corresponding private module map.
+  if (const FileEntry *PMMFile =
+        getPrivateModuleMap(File->getName(), Dir, FileMgr)) {
+    if (ModMap.parseModuleMapFile(PMMFile, IsSystem)) {
+      DirectoryHasModuleMap[Dir] = false;
+      return LMM_InvalidModuleMap;
+    }
+  }
+
+  // This directory has a module map.
+  DirectoryHasModuleMap[Dir] = true;
+  return LMM_NewlyLoaded;
+}
+
+const FileEntry *
+HeaderSearch::lookupModuleMapFile(const DirectoryEntry *Dir, bool IsFramework) {
+  // For frameworks, the preferred spelling is Modules/module.modulemap, but
+  // module.map at the framework root is also accepted.
+  SmallString<128> ModuleMapFileName(Dir->getName());
+  if (IsFramework)
+    llvm::sys::path::append(ModuleMapFileName, "Modules");
+  llvm::sys::path::append(ModuleMapFileName, "module.modulemap");
+  if (const FileEntry *F = FileMgr.getFile(ModuleMapFileName))
+    return F;
+
+  // Continue to allow module.map
+  ModuleMapFileName = Dir->getName();
+  llvm::sys::path::append(ModuleMapFileName, "module.map");
+  return FileMgr.getFile(ModuleMapFileName);
+}
+
+Module *HeaderSearch::loadFrameworkModule(StringRef Name,
+                                          const DirectoryEntry *Dir,
+                                          bool IsSystem) {
+  if (Module *Module = ModMap.findModule(Name))
+    return Module;
+  
+  // Try to load a module map file.
+  switch (loadModuleMapFile(Dir, IsSystem, /*IsFramework*/true)) {
+  case LMM_InvalidModuleMap:
+    break;
+    
+  case LMM_AlreadyLoaded:
+  case LMM_NoDirectory:
+    return nullptr;
+
+  case LMM_NewlyLoaded:
+    return ModMap.findModule(Name);
+  }
+
+
+  // Try to infer a module map from the framework directory.
+  return ModMap.inferFrameworkModule(Name, Dir, IsSystem, /*Parent=*/nullptr);
+}
+
+
+HeaderSearch::LoadModuleMapResult 
+HeaderSearch::loadModuleMapFile(StringRef DirName, bool IsSystem,
+                                bool IsFramework) {
+  if (const DirectoryEntry *Dir = FileMgr.getDirectory(DirName))
+    return loadModuleMapFile(Dir, IsSystem, IsFramework);
+  
+  return LMM_NoDirectory;
+}
+
+HeaderSearch::LoadModuleMapResult 
+HeaderSearch::loadModuleMapFile(const DirectoryEntry *Dir, bool IsSystem,
+                                bool IsFramework) {
+  auto KnownDir = DirectoryHasModuleMap.find(Dir);
+  if (KnownDir != DirectoryHasModuleMap.end())
+    return KnownDir->second? LMM_AlreadyLoaded : LMM_InvalidModuleMap;
+
+  if (const FileEntry *ModuleMapFile = lookupModuleMapFile(Dir, IsFramework)) {
+    LoadModuleMapResult Result = loadModuleMapFileImpl(ModuleMapFile, IsSystem);
+    // Add Dir explicitly in case ModuleMapFile is in a subdirectory.
+    // E.g. Foo.framework/Modules/module.modulemap
+    //      ^Dir                  ^ModuleMapFile
+    if (Result == LMM_NewlyLoaded)
+      DirectoryHasModuleMap[Dir] = true;
+    return Result;
+  }
+  return LMM_InvalidModuleMap;
+}
+
+void HeaderSearch::collectAllModules(SmallVectorImpl<Module *> &Modules) {
+  Modules.clear();
+  
+  // Load module maps for each of the header search directories.
+  for (unsigned Idx = 0, N = SearchDirs.size(); Idx != N; ++Idx) {
+    bool IsSystem = SearchDirs[Idx].isSystemHeaderDirectory();
+    if (SearchDirs[Idx].isFramework()) {
+      std::error_code EC;
+      SmallString<128> DirNative;
+      llvm::sys::path::native(SearchDirs[Idx].getFrameworkDir()->getName(),
+                              DirNative);
+      
+      // Search each of the ".framework" directories to load them as modules.
+      for (llvm::sys::fs::directory_iterator Dir(DirNative.str(), EC), DirEnd;
+           Dir != DirEnd && !EC; Dir.increment(EC)) {
+        if (llvm::sys::path::extension(Dir->path()) != ".framework")
+          continue;
+        
+        const DirectoryEntry *FrameworkDir = FileMgr.getDirectory(Dir->path());
+        if (!FrameworkDir)
+          continue;
+        
+        // Load this framework module.
+        loadFrameworkModule(llvm::sys::path::stem(Dir->path()), FrameworkDir,
+                            IsSystem);
+      }
+      continue;
+    }
+    
+    // FIXME: Deal with header maps.
+    if (SearchDirs[Idx].isHeaderMap())
+      continue;
+    
+    // Try to load a module map file for the search directory.
+    loadModuleMapFile(SearchDirs[Idx].getDir(), IsSystem, /*IsFramework*/false);
+    
+    // Try to load module map files for immediate subdirectories of this search
+    // directory.
+    loadSubdirectoryModuleMaps(SearchDirs[Idx]);
+  }
+  
+  // Populate the list of modules.
+  for (ModuleMap::module_iterator M = ModMap.module_begin(), 
+                               MEnd = ModMap.module_end();
+       M != MEnd; ++M) {
+    Modules.push_back(M->getValue());
+  }
+}
+
+void HeaderSearch::loadTopLevelSystemModules() {
+  // Load module maps for each of the header search directories.
+  for (unsigned Idx = 0, N = SearchDirs.size(); Idx != N; ++Idx) {
+    // We only care about normal header directories.
+    if (!SearchDirs[Idx].isNormalDir()) {
+      continue;
+    }
+
+    // Try to load a module map file for the search directory.
+    loadModuleMapFile(SearchDirs[Idx].getDir(),
+                      SearchDirs[Idx].isSystemHeaderDirectory(),
+                      SearchDirs[Idx].isFramework());
+  }
+}
+
+void HeaderSearch::loadSubdirectoryModuleMaps(DirectoryLookup &SearchDir) {
+  if (SearchDir.haveSearchedAllModuleMaps())
+    return;
+
+  std::error_code EC;
+  SmallString<128> DirNative;
+  llvm::sys::path::native(SearchDir.getDir()->getName(), DirNative);
+  for (llvm::sys::fs::directory_iterator Dir(DirNative.str(), EC), DirEnd;
+       Dir != DirEnd && !EC; Dir.increment(EC)) {
+    loadModuleMapFile(Dir->path(), SearchDir.isSystemHeaderDirectory(),
+                      SearchDir.isFramework());
+  }
+
+  SearchDir.setSearchedAllModuleMaps(true);
+}