Import LLVM 3.9.1 including clang and lld.

15 files changed, 734 insertions, 107 deletions

diff --git a/gnu/llvm/tools/clang/lib/Basic/Builtins.cpp b/gnu/llvm/tools/clang/lib/Basic/Builtins.cpp
index fb6a6451aa8..28695d649a8 100644
--- a/gnu/llvm/tools/clang/lib/Basic/Builtins.cpp
+++ b/gnu/llvm/tools/clang/lib/Basic/Builtins.cpp
@@ -69,7 +69,9 @@ bool Builtin::Context::builtinIsSupported(const Builtin::Info &BuiltinInfo,
   bool MSModeUnsupported =
       !LangOpts.MicrosoftExt && (BuiltinInfo.Langs & MS_LANG);
   bool ObjCUnsupported = !LangOpts.ObjC1 && BuiltinInfo.Langs == OBJC_LANG;
-  return !BuiltinsUnsupported && !MathBuiltinsUnsupported &&
+  bool OclCUnsupported = LangOpts.OpenCLVersion != 200 &&
+                         BuiltinInfo.Langs == OCLC20_LANG;
+  return !BuiltinsUnsupported && !MathBuiltinsUnsupported && !OclCUnsupported &&
          !GnuModeUnsupported && !MSModeUnsupported && !ObjCUnsupported;
 }
 
diff --git a/gnu/llvm/tools/clang/lib/Basic/CMakeLists.txt b/gnu/llvm/tools/clang/lib/Basic/CMakeLists.txt
index cfad8c3649e..ad460d49653 100644
--- a/gnu/llvm/tools/clang/lib/Basic/CMakeLists.txt
+++ b/gnu/llvm/tools/clang/lib/Basic/CMakeLists.txt
@@ -53,12 +53,20 @@ if(DEFINED llvm_vc AND DEFINED clang_vc)
 else()
   # Not producing a VC revision include.
   set(version_inc)
+
+  # Being able to force-set the SVN revision in cases where it isn't available
+  # is useful for performance tracking, and matches compatibility from autoconf.
+  if(SVN_REVISION)
+    set_source_files_properties(Version.cpp
+      PROPERTIES COMPILE_DEFINITIONS "SVN_REVISION=\"${SVN_REVISION}\"")
+  endif()
 endif()
 
 add_clang_library(clangBasic
   Attributes.cpp
   Builtins.cpp
   CharInfo.cpp
+  Cuda.cpp
   Diagnostic.cpp
   DiagnosticIDs.cpp
   DiagnosticOptions.cpp
diff --git a/gnu/llvm/tools/clang/lib/Basic/Cuda.cpp b/gnu/llvm/tools/clang/lib/Basic/Cuda.cpp
new file mode 100644
index 00000000000..3264078b98f
--- /dev/null
+++ b/gnu/llvm/tools/clang/lib/Basic/Cuda.cpp
@@ -0,0 +1,171 @@
+#include "clang/Basic/Cuda.h"
+
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/StringSwitch.h"
+#include "llvm/Support/ErrorHandling.h"
+
+namespace clang {
+
+const char *CudaVersionToString(CudaVersion V) {
+  switch (V) {
+  case CudaVersion::UNKNOWN:
+    return "unknown";
+  case CudaVersion::CUDA_70:
+    return "7.0";
+  case CudaVersion::CUDA_75:
+    return "7.5";
+  case CudaVersion::CUDA_80:
+    return "8.0";
+  }
+  llvm_unreachable("invalid enum");
+}
+
+const char *CudaArchToString(CudaArch A) {
+  switch (A) {
+  case CudaArch::UNKNOWN:
+    return "unknown";
+  case CudaArch::SM_20:
+    return "sm_20";
+  case CudaArch::SM_21:
+    return "sm_21";
+  case CudaArch::SM_30:
+    return "sm_30";
+  case CudaArch::SM_32:
+    return "sm_32";
+  case CudaArch::SM_35:
+    return "sm_35";
+  case CudaArch::SM_37:
+    return "sm_37";
+  case CudaArch::SM_50:
+    return "sm_50";
+  case CudaArch::SM_52:
+    return "sm_52";
+  case CudaArch::SM_53:
+    return "sm_53";
+  case CudaArch::SM_60:
+    return "sm_60";
+  case CudaArch::SM_61:
+    return "sm_61";
+  case CudaArch::SM_62:
+    return "sm_62";
+  }
+  llvm_unreachable("invalid enum");
+}
+
+CudaArch StringToCudaArch(llvm::StringRef S) {
+  return llvm::StringSwitch<CudaArch>(S)
+      .Case("sm_20", CudaArch::SM_20)
+      .Case("sm_21", CudaArch::SM_21)
+      .Case("sm_30", CudaArch::SM_30)
+      .Case("sm_32", CudaArch::SM_32)
+      .Case("sm_35", CudaArch::SM_35)
+      .Case("sm_37", CudaArch::SM_37)
+      .Case("sm_50", CudaArch::SM_50)
+      .Case("sm_52", CudaArch::SM_52)
+      .Case("sm_53", CudaArch::SM_53)
+      .Case("sm_60", CudaArch::SM_60)
+      .Case("sm_61", CudaArch::SM_61)
+      .Case("sm_62", CudaArch::SM_62)
+      .Default(CudaArch::UNKNOWN);
+}
+
+const char *CudaVirtualArchToString(CudaVirtualArch A) {
+  switch (A) {
+  case CudaVirtualArch::UNKNOWN:
+    return "unknown";
+  case CudaVirtualArch::COMPUTE_20:
+    return "compute_20";
+  case CudaVirtualArch::COMPUTE_30:
+    return "compute_30";
+  case CudaVirtualArch::COMPUTE_32:
+    return "compute_32";
+  case CudaVirtualArch::COMPUTE_35:
+    return "compute_35";
+  case CudaVirtualArch::COMPUTE_37:
+    return "compute_37";
+  case CudaVirtualArch::COMPUTE_50:
+    return "compute_50";
+  case CudaVirtualArch::COMPUTE_52:
+    return "compute_52";
+  case CudaVirtualArch::COMPUTE_53:
+    return "compute_53";
+  case CudaVirtualArch::COMPUTE_60:
+    return "compute_60";
+  case CudaVirtualArch::COMPUTE_61:
+    return "compute_61";
+  case CudaVirtualArch::COMPUTE_62:
+    return "compute_62";
+  }
+  llvm_unreachable("invalid enum");
+}
+
+CudaVirtualArch StringToCudaVirtualArch(llvm::StringRef S) {
+  return llvm::StringSwitch<CudaVirtualArch>(S)
+      .Case("compute_20", CudaVirtualArch::COMPUTE_20)
+      .Case("compute_30", CudaVirtualArch::COMPUTE_30)
+      .Case("compute_32", CudaVirtualArch::COMPUTE_32)
+      .Case("compute_35", CudaVirtualArch::COMPUTE_35)
+      .Case("compute_37", CudaVirtualArch::COMPUTE_37)
+      .Case("compute_50", CudaVirtualArch::COMPUTE_50)
+      .Case("compute_52", CudaVirtualArch::COMPUTE_52)
+      .Case("compute_53", CudaVirtualArch::COMPUTE_53)
+      .Case("compute_60", CudaVirtualArch::COMPUTE_60)
+      .Case("compute_61", CudaVirtualArch::COMPUTE_61)
+      .Case("compute_62", CudaVirtualArch::COMPUTE_62)
+      .Default(CudaVirtualArch::UNKNOWN);
+}
+
+CudaVirtualArch VirtualArchForCudaArch(CudaArch A) {
+  switch (A) {
+  case CudaArch::UNKNOWN:
+    return CudaVirtualArch::UNKNOWN;
+  case CudaArch::SM_20:
+  case CudaArch::SM_21:
+    return CudaVirtualArch::COMPUTE_20;
+  case CudaArch::SM_30:
+    return CudaVirtualArch::COMPUTE_30;
+  case CudaArch::SM_32:
+    return CudaVirtualArch::COMPUTE_32;
+  case CudaArch::SM_35:
+    return CudaVirtualArch::COMPUTE_35;
+  case CudaArch::SM_37:
+    return CudaVirtualArch::COMPUTE_37;
+  case CudaArch::SM_50:
+    return CudaVirtualArch::COMPUTE_50;
+  case CudaArch::SM_52:
+    return CudaVirtualArch::COMPUTE_52;
+  case CudaArch::SM_53:
+    return CudaVirtualArch::COMPUTE_53;
+  case CudaArch::SM_60:
+    return CudaVirtualArch::COMPUTE_60;
+  case CudaArch::SM_61:
+    return CudaVirtualArch::COMPUTE_61;
+  case CudaArch::SM_62:
+    return CudaVirtualArch::COMPUTE_62;
+  }
+  llvm_unreachable("invalid enum");
+}
+
+CudaVersion MinVersionForCudaArch(CudaArch A) {
+  switch (A) {
+  case CudaArch::UNKNOWN:
+    return CudaVersion::UNKNOWN;
+  case CudaArch::SM_20:
+  case CudaArch::SM_21:
+  case CudaArch::SM_30:
+  case CudaArch::SM_32:
+  case CudaArch::SM_35:
+  case CudaArch::SM_37:
+  case CudaArch::SM_50:
+  case CudaArch::SM_52:
+  case CudaArch::SM_53:
+    return CudaVersion::CUDA_70;
+  case CudaArch::SM_60:
+  case CudaArch::SM_61:
+  case CudaArch::SM_62:
+    return CudaVersion::CUDA_80;
+  }
+  llvm_unreachable("invalid enum");
+}
+
+} // namespace clang
diff --git a/gnu/llvm/tools/clang/lib/Basic/Diagnostic.cpp b/gnu/llvm/tools/clang/lib/Basic/Diagnostic.cpp
index 7cf7305827f..f10d156743b 100644
--- a/gnu/llvm/tools/clang/lib/Basic/Diagnostic.cpp
+++ b/gnu/llvm/tools/clang/lib/Basic/Diagnostic.cpp
@@ -68,6 +68,7 @@ DiagnosticsEngine::DiagnosticsEngine(
   WarningsAsErrors = false;
   EnableAllWarnings = false;
   ErrorsAsFatal = false;
+  FatalsAsError = false;
   SuppressSystemWarnings = false;
   SuppressAllDiagnostics = false;
   ElideType = true;
diff --git a/gnu/llvm/tools/clang/lib/Basic/DiagnosticIDs.cpp b/gnu/llvm/tools/clang/lib/Basic/DiagnosticIDs.cpp
index a34c7fecb53..3c370f67fa3 100644
--- a/gnu/llvm/tools/clang/lib/Basic/DiagnosticIDs.cpp
+++ b/gnu/llvm/tools/clang/lib/Basic/DiagnosticIDs.cpp
@@ -351,7 +351,7 @@ bool DiagnosticIDs::isDefaultMappingAsError(unsigned DiagID) {
   if (DiagID >= diag::DIAG_UPPER_LIMIT)
     return false;
 
-  return GetDefaultDiagMapping(DiagID).getSeverity() == diag::Severity::Error;
+  return GetDefaultDiagMapping(DiagID).getSeverity() >= diag::Severity::Error;
 }
 
 /// getDescription - Given a diagnostic ID, return a description of the
@@ -462,6 +462,12 @@ DiagnosticIDs::getDiagnosticSeverity(unsigned DiagID, SourceLocation Loc,
       Result = diag::Severity::Fatal;
   }
 
+  // If explicitly requested, map fatal errors to errors.
+  if (Result == diag::Severity::Fatal) {
+      if (Diag.FatalsAsError)
+        Result = diag::Severity::Error;
+  }
+
   // Custom diagnostics always are emitted in system headers.
   bool ShowInSystemHeader =
       !GetDiagInfo(DiagID) || GetDiagInfo(DiagID)->WarnShowInSystemHeader;
diff --git a/gnu/llvm/tools/clang/lib/Basic/FileManager.cpp b/gnu/llvm/tools/clang/lib/Basic/FileManager.cpp
index cb3f75c25a0..ce9b7e1bb48 100644
--- a/gnu/llvm/tools/clang/lib/Basic/FileManager.cpp
+++ b/gnu/llvm/tools/clang/lib/Basic/FileManager.cpp
@@ -19,7 +19,6 @@
 
 #include "clang/Basic/FileManager.h"
 #include "clang/Basic/FileSystemStatCache.h"
-#include "clang/Frontend/PCHContainerOperations.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Config/llvm-config.h"
 #include "llvm/ADT/STLExtras.h"
@@ -124,7 +123,7 @@ static const DirectoryEntry *getDirectoryFromFile(FileManager &FileMgr,
 void FileManager::addAncestorsAsVirtualDirs(StringRef Path) {
   StringRef DirName = llvm::sys::path::parent_path(Path);
   if (DirName.empty())
-    return;
+    DirName = ".";
 
   auto &NamedDirEnt =
       *SeenDirEntries.insert(std::make_pair(DirName, nullptr)).first;
@@ -313,6 +312,9 @@ const FileEntry *FileManager::getFile(StringRef Filename, bool openFile,
   UFE.InPCH = Data.InPCH;
   UFE.File = std::move(F);
   UFE.IsValid = true;
+  if (UFE.File)
+    if (auto RealPathName = UFE.File->getName())
+      UFE.RealPathName = *RealPathName;
   return &UFE;
 }
 
@@ -564,7 +566,3 @@ void FileManager::PrintStats() const {
 
   //llvm::errs() << PagesMapped << BytesOfPagesMapped << FSLookups;
 }
-
-// Virtual destructors for abstract base classes that need live in Basic.
-PCHContainerWriter::~PCHContainerWriter() {}
-PCHContainerReader::~PCHContainerReader() {}
diff --git a/gnu/llvm/tools/clang/lib/Basic/IdentifierTable.cpp b/gnu/llvm/tools/clang/lib/Basic/IdentifierTable.cpp
index 67de1cb6fda..d6ad0f5c915 100644
--- a/gnu/llvm/tools/clang/lib/Basic/IdentifierTable.cpp
+++ b/gnu/llvm/tools/clang/lib/Basic/IdentifierTable.cpp
@@ -42,6 +42,7 @@ IdentifierInfo::IdentifierInfo() {
   NeedsHandleIdentifier = false;
   IsFromAST = false;
   ChangedAfterLoad = false;
+  FEChangedAfterLoad = false;
   RevertedTokenID = false;
   OutOfDate = false;
   IsModulesImport = false;
diff --git a/gnu/llvm/tools/clang/lib/Basic/LangOptions.cpp b/gnu/llvm/tools/clang/lib/Basic/LangOptions.cpp
index 1b08b068604..8c0ecd46ad5 100644
--- a/gnu/llvm/tools/clang/lib/Basic/LangOptions.cpp
+++ b/gnu/llvm/tools/clang/lib/Basic/LangOptions.cpp
@@ -34,7 +34,6 @@ void LangOptions::resetNonModularOptions() {
   SanitizerBlacklistFiles.clear();
 
   CurrentModule.clear();
-  ImplementationOfModule.clear();
 }
 
 bool LangOptions::isNoBuiltinFunc(const char *Name) const {
diff --git a/gnu/llvm/tools/clang/lib/Basic/Module.cpp b/gnu/llvm/tools/clang/lib/Basic/Module.cpp
index 0b783263694..3d1a40db5ea 100644
--- a/gnu/llvm/tools/clang/lib/Basic/Module.cpp
+++ b/gnu/llvm/tools/clang/lib/Basic/Module.cpp
@@ -418,12 +418,8 @@ void Module::print(raw_ostream &OS, unsigned Indent) const {
     OS.indent(Indent + 2);
     OS << "export ";
     printModuleId(OS, UnresolvedExports[I].Id);
-    if (UnresolvedExports[I].Wildcard) {
-      if (UnresolvedExports[I].Id.empty())
-        OS << "*";
-      else
-        OS << ".*";
-    }
+    if (UnresolvedExports[I].Wildcard)
+      OS << (UnresolvedExports[I].Id.empty() ? "*" : ".*");
     OS << "\n";
   }
 
@@ -486,12 +482,13 @@ void Module::print(raw_ostream &OS, unsigned Indent) const {
   OS << "}\n";
 }
 
-void Module::dump() const {
+LLVM_DUMP_METHOD void Module::dump() const {
   print(llvm::errs());
 }
 
 void VisibleModuleSet::setVisible(Module *M, SourceLocation Loc,
                                   VisibleCallback Vis, ConflictCallback Cb) {
+  assert(Loc.isValid() && "setVisible expects a valid import location");
   if (isVisible(M))
     return;
 
diff --git a/gnu/llvm/tools/clang/lib/Basic/OpenMPKinds.cpp b/gnu/llvm/tools/clang/lib/Basic/OpenMPKinds.cpp
index 577132dc144..d1e4779e2c7 100644
--- a/gnu/llvm/tools/clang/lib/Basic/OpenMPKinds.cpp
+++ b/gnu/llvm/tools/clang/lib/Basic/OpenMPKinds.cpp
@@ -55,6 +55,7 @@ OpenMPClauseKind clang::getOpenMPClauseKind(StringRef Str) {
   return llvm::StringSwitch<OpenMPClauseKind>(Str)
 #define OPENMP_CLAUSE(Name, Class) .Case(#Name, OMPC_##Name)
 #include "clang/Basic/OpenMPKinds.def"
+      .Case("uniform", OMPC_uniform)
       .Default(OMPC_unknown);
 }
 
@@ -67,6 +68,8 @@ const char *clang::getOpenMPClauseName(OpenMPClauseKind Kind) {
   case OMPC_##Name:                                                            \
     return #Name;
 #include "clang/Basic/OpenMPKinds.def"
+  case OMPC_uniform:
+    return "uniform";
   case OMPC_threadprivate:
     return "threadprivate or thread local";
   }
@@ -109,6 +112,19 @@ unsigned clang::getOpenMPSimpleClauseType(OpenMPClauseKind Kind,
 #define OPENMP_MAP_KIND(Name) .Case(#Name, OMPC_MAP_##Name)
 #include "clang/Basic/OpenMPKinds.def"
         .Default(OMPC_MAP_unknown);
+  case OMPC_dist_schedule:
+    return llvm::StringSwitch<OpenMPDistScheduleClauseKind>(Str)
+#define OPENMP_DIST_SCHEDULE_KIND(Name) .Case(#Name, OMPC_DIST_SCHEDULE_##Name)
+#include "clang/Basic/OpenMPKinds.def"
+        .Default(OMPC_DIST_SCHEDULE_unknown);
+  case OMPC_defaultmap:
+    return llvm::StringSwitch<unsigned>(Str)
+#define OPENMP_DEFAULTMAP_KIND(Name)                                           \
+  .Case(#Name, static_cast<unsigned>(OMPC_DEFAULTMAP_##Name))
+#define OPENMP_DEFAULTMAP_MODIFIER(Name)                                       \
+  .Case(#Name, static_cast<unsigned>(OMPC_DEFAULTMAP_MODIFIER_##Name))
+#include "clang/Basic/OpenMPKinds.def"
+        .Default(OMPC_DEFAULTMAP_unknown);
   case OMPC_unknown:
   case OMPC_threadprivate:
   case OMPC_if:
@@ -145,6 +161,11 @@ unsigned clang::getOpenMPSimpleClauseType(OpenMPClauseKind Kind,
   case OMPC_nogroup:
   case OMPC_num_tasks:
   case OMPC_hint:
+  case OMPC_uniform:
+  case OMPC_to:
+  case OMPC_from:
+  case OMPC_use_device_ptr:
+  case OMPC_is_device_ptr:
     break;
   }
   llvm_unreachable("Invalid OpenMP simple clause kind");
@@ -219,6 +240,30 @@ const char *clang::getOpenMPSimpleClauseTypeName(OpenMPClauseKind Kind,
       break;
     }
     llvm_unreachable("Invalid OpenMP 'map' clause type");
+  case OMPC_dist_schedule:
+    switch (Type) {
+    case OMPC_DIST_SCHEDULE_unknown:
+      return "unknown";
+#define OPENMP_DIST_SCHEDULE_KIND(Name)                                      \
+  case OMPC_DIST_SCHEDULE_##Name:                                            \
+    return #Name;
+#include "clang/Basic/OpenMPKinds.def"
+    }
+    llvm_unreachable("Invalid OpenMP 'dist_schedule' clause type");
+  case OMPC_defaultmap:
+    switch (Type) {
+    case OMPC_DEFAULTMAP_unknown:
+    case OMPC_DEFAULTMAP_MODIFIER_last:
+      return "unknown";
+#define OPENMP_DEFAULTMAP_KIND(Name)                                         \
+    case OMPC_DEFAULTMAP_##Name:                                             \
+      return #Name;
+#define OPENMP_DEFAULTMAP_MODIFIER(Name)                                     \
+    case OMPC_DEFAULTMAP_MODIFIER_##Name:                                    \
+      return #Name;
+#include "clang/Basic/OpenMPKinds.def"
+    }
+    llvm_unreachable("Invalid OpenMP 'schedule' clause type");
   case OMPC_unknown:
   case OMPC_threadprivate:
   case OMPC_if:
@@ -255,6 +300,11 @@ const char *clang::getOpenMPSimpleClauseTypeName(OpenMPClauseKind Kind,
   case OMPC_nogroup:
   case OMPC_num_tasks:
   case OMPC_hint:
+  case OMPC_uniform:
+  case OMPC_to:
+  case OMPC_from:
+  case OMPC_use_device_ptr:
+  case OMPC_is_device_ptr:
     break;
   }
   llvm_unreachable("Invalid OpenMP simple clause kind");
@@ -398,6 +448,56 @@ bool clang::isAllowedClauseForDirective(OpenMPDirectiveKind DKind,
       break;
     }
     break;
+  case OMPD_target_enter_data:
+    switch (CKind) {
+#define OPENMP_TARGET_ENTER_DATA_CLAUSE(Name)                                  \
+  case OMPC_##Name:                                                            \
+    return true;
+#include "clang/Basic/OpenMPKinds.def"
+    default:
+      break;
+    }
+    break;
+  case OMPD_target_exit_data:
+    switch (CKind) {
+#define OPENMP_TARGET_EXIT_DATA_CLAUSE(Name)                                   \
+  case OMPC_##Name:                                                            \
+    return true;
+#include "clang/Basic/OpenMPKinds.def"
+    default:
+      break;
+    }
+    break;
+  case OMPD_target_parallel:
+    switch (CKind) {
+#define OPENMP_TARGET_PARALLEL_CLAUSE(Name)                                    \
+  case OMPC_##Name:                                                            \
+    return true;
+#include "clang/Basic/OpenMPKinds.def"
+    default:
+      break;
+    }
+    break;
+  case OMPD_target_parallel_for:
+    switch (CKind) {
+#define OPENMP_TARGET_PARALLEL_FOR_CLAUSE(Name)                                \
+  case OMPC_##Name:                                                            \
+    return true;
+#include "clang/Basic/OpenMPKinds.def"
+    default:
+      break;
+    }
+    break;
+  case OMPD_target_update:
+    switch (CKind) {
+#define OPENMP_TARGET_UPDATE_CLAUSE(Name)                                      \
+  case OMPC_##Name:                                                            \
+    return true;
+#include "clang/Basic/OpenMPKinds.def"
+    default:
+      break;
+    }
+    break;
   case OMPD_teams:
     switch (CKind) {
 #define OPENMP_TEAMS_CLAUSE(Name)                                              \
@@ -408,6 +508,8 @@ bool clang::isAllowedClauseForDirective(OpenMPDirectiveKind DKind,
       break;
     }
     break;
+  case OMPD_declare_simd:
+    break;
   case OMPD_cancel:
     switch (CKind) {
 #define OPENMP_CANCEL_CLAUSE(Name)                                             \
@@ -468,6 +570,48 @@ bool clang::isAllowedClauseForDirective(OpenMPDirectiveKind DKind,
       break;
     }
     break;
+  case OMPD_distribute_parallel_for:
+    switch (CKind) {
+#define OPENMP_DISTRIBUTE_PARALLEL_FOR_CLAUSE(Name)                            \
+  case OMPC_##Name:                                                            \
+    return true;
+#include "clang/Basic/OpenMPKinds.def"
+    default:
+      break;
+    }
+    break;
+  case OMPD_distribute_parallel_for_simd:
+    switch (CKind) {
+#define OPENMP_DISTRIBUTE_PARALLEL_FOR_SIMD_CLAUSE(Name)                       \
+  case OMPC_##Name:                                                            \
+    return true;
+#include "clang/Basic/OpenMPKinds.def"
+    default:
+      break;
+    }
+    break;
+  case OMPD_distribute_simd:
+    switch (CKind) {
+#define OPENMP_DISTRIBUTE_SIMD_CLAUSE(Name)                                    \
+  case OMPC_##Name:                                                            \
+    return true;
+#include "clang/Basic/OpenMPKinds.def"
+    default:
+      break;
+    }
+    break;
+  case OMPD_target_parallel_for_simd:
+    switch (CKind) {
+#define OPENMP_TARGET_PARALLEL_FOR_SIMD_CLAUSE(Name)                           \
+  case OMPC_##Name:                                                            \
+    return true;
+#include "clang/Basic/OpenMPKinds.def"
+    default:
+      break;
+    }
+    break;
+  case OMPD_declare_target:
+  case OMPD_end_declare_target:
   case OMPD_unknown:
   case OMPD_threadprivate:
   case OMPD_section:
@@ -477,6 +621,7 @@ bool clang::isAllowedClauseForDirective(OpenMPDirectiveKind DKind,
   case OMPD_taskwait:
   case OMPD_taskgroup:
   case OMPD_cancellation_point:
+  case OMPD_declare_reduction:
     break;
   }
   return false;
@@ -485,17 +630,25 @@ bool clang::isAllowedClauseForDirective(OpenMPDirectiveKind DKind,
 bool clang::isOpenMPLoopDirective(OpenMPDirectiveKind DKind) {
   return DKind == OMPD_simd || DKind == OMPD_for || DKind == OMPD_for_simd ||
          DKind == OMPD_parallel_for || DKind == OMPD_parallel_for_simd ||
-         DKind == OMPD_taskloop ||
-         DKind == OMPD_taskloop_simd ||
-         DKind == OMPD_distribute; // TODO add next directives.
+         DKind == OMPD_taskloop || DKind == OMPD_taskloop_simd ||
+         DKind == OMPD_distribute || DKind == OMPD_target_parallel_for ||
+         DKind == OMPD_distribute_parallel_for ||
+         DKind == OMPD_distribute_parallel_for_simd ||
+         DKind == OMPD_distribute_simd ||
+         DKind == OMPD_target_parallel_for_simd;
+  // TODO add next directives.
 }
 
 bool clang::isOpenMPWorksharingDirective(OpenMPDirectiveKind DKind) {
   return DKind == OMPD_for || DKind == OMPD_for_simd ||
          DKind == OMPD_sections || DKind == OMPD_section ||
          DKind == OMPD_single || DKind == OMPD_parallel_for ||
-         DKind == OMPD_parallel_for_simd ||
-         DKind == OMPD_parallel_sections; // TODO add next directives.
+         DKind == OMPD_parallel_for_simd || DKind == OMPD_parallel_sections ||
+         DKind == OMPD_target_parallel_for ||
+         DKind == OMPD_distribute_parallel_for ||
+         DKind == OMPD_distribute_parallel_for_simd ||
+         DKind == OMPD_target_parallel_for_simd;
+  // TODO add next directives.
 }
 
 bool clang::isOpenMPTaskLoopDirective(OpenMPDirectiveKind DKind) {
@@ -504,12 +657,24 @@ bool clang::isOpenMPTaskLoopDirective(OpenMPDirectiveKind DKind) {
 
 bool clang::isOpenMPParallelDirective(OpenMPDirectiveKind DKind) {
   return DKind == OMPD_parallel || DKind == OMPD_parallel_for ||
-         DKind == OMPD_parallel_for_simd ||
-         DKind == OMPD_parallel_sections; // TODO add next directives.
+         DKind == OMPD_parallel_for_simd || DKind == OMPD_parallel_sections ||
+         DKind == OMPD_target_parallel || DKind == OMPD_target_parallel_for ||
+         DKind == OMPD_distribute_parallel_for ||
+         DKind == OMPD_distribute_parallel_for_simd ||
+         DKind == OMPD_target_parallel_for_simd;
+  // TODO add next directives.
 }
 
-bool clang::isOpenMPTargetDirective(OpenMPDirectiveKind DKind) {
-  return DKind == OMPD_target; // TODO add next directives.
+bool clang::isOpenMPTargetExecutionDirective(OpenMPDirectiveKind DKind) {
+  // TODO add next directives.
+  return DKind == OMPD_target || DKind == OMPD_target_parallel ||
+         DKind == OMPD_target_parallel_for || 
+         DKind == OMPD_target_parallel_for_simd;
+}
+
+bool clang::isOpenMPTargetDataManagementDirective(OpenMPDirectiveKind DKind) {
+  return DKind == OMPD_target_data || DKind == OMPD_target_enter_data ||
+         DKind == OMPD_target_exit_data || DKind == OMPD_target_update;
 }
 
 bool clang::isOpenMPTeamsDirective(OpenMPDirectiveKind DKind) {
@@ -518,12 +683,17 @@ bool clang::isOpenMPTeamsDirective(OpenMPDirectiveKind DKind) {
 
 bool clang::isOpenMPSimdDirective(OpenMPDirectiveKind DKind) {
   return DKind == OMPD_simd || DKind == OMPD_for_simd ||
-         DKind == OMPD_parallel_for_simd ||
-         DKind == OMPD_taskloop_simd; // TODO add next directives.
+         DKind == OMPD_parallel_for_simd || DKind == OMPD_taskloop_simd ||
+         DKind == OMPD_distribute_parallel_for_simd ||
+         DKind == OMPD_distribute_simd;
+  // TODO add next directives.
 }
 
 bool clang::isOpenMPDistributeDirective(OpenMPDirectiveKind Kind) {
-  return Kind == OMPD_distribute; // TODO add next directives.
+  return Kind == OMPD_distribute || Kind == OMPD_distribute_parallel_for ||
+         Kind == OMPD_distribute_parallel_for_simd ||
+         Kind == OMPD_distribute_simd;
+  // TODO add next directives.
 }
 
 bool clang::isOpenMPPrivate(OpenMPClauseKind Kind) {
@@ -536,3 +706,12 @@ bool clang::isOpenMPThreadPrivate(OpenMPClauseKind Kind) {
   return Kind == OMPC_threadprivate || Kind == OMPC_copyin;
 }
 
+bool clang::isOpenMPTaskingDirective(OpenMPDirectiveKind Kind) {
+  return Kind == OMPD_task || isOpenMPTaskLoopDirective(Kind);
+}
+
+bool clang::isOpenMPLoopBoundSharingDirective(OpenMPDirectiveKind Kind) {
+  return Kind == OMPD_distribute_parallel_for ||
+         Kind == OMPD_distribute_parallel_for_simd ||
+         Kind == OMPD_distribute_simd;
+}
diff --git a/gnu/llvm/tools/clang/lib/Basic/OperatorPrecedence.cpp b/gnu/llvm/tools/clang/lib/Basic/OperatorPrecedence.cpp
index ade8d6d841d..384d23c38af 100644
--- a/gnu/llvm/tools/clang/lib/Basic/OperatorPrecedence.cpp
+++ b/gnu/llvm/tools/clang/lib/Basic/OperatorPrecedence.cpp
@@ -53,6 +53,7 @@ prec::Level getBinOpPrecedence(tok::TokenKind Kind, bool GreaterThanIsOperator,
   case tok::pipeequal:            return prec::Assignment;
   case tok::question:             return prec::Conditional;
   case tok::pipepipe:             return prec::LogicalOr;
+  case tok::caretcaret:
   case tok::ampamp:               return prec::LogicalAnd;
   case tok::pipe:                 return prec::InclusiveOr;
   case tok::caret:                return prec::ExclusiveOr;
diff --git a/gnu/llvm/tools/clang/lib/Basic/SourceManager.cpp b/gnu/llvm/tools/clang/lib/Basic/SourceManager.cpp
index 4c501616a3e..1e83b63cf82 100644
--- a/gnu/llvm/tools/clang/lib/Basic/SourceManager.cpp
+++ b/gnu/llvm/tools/clang/lib/Basic/SourceManager.cpp
@@ -1160,7 +1160,8 @@ unsigned SourceManager::getColumnNumber(FileID FID, unsigned FilePos,
 
 // isInvalid - Return the result of calling loc.isInvalid(), and
 // if Invalid is not null, set its value to same.
-static bool isInvalid(SourceLocation Loc, bool *Invalid) {
+template<typename LocType>
+static bool isInvalid(LocType Loc, bool *Invalid) {
   bool MyInvalid = Loc.isInvalid();
   if (Invalid)
     *Invalid = MyInvalid;
@@ -1183,8 +1184,9 @@ unsigned SourceManager::getExpansionColumnNumber(SourceLocation Loc,
 
 unsigned SourceManager::getPresumedColumnNumber(SourceLocation Loc,
                                                 bool *Invalid) const {
-  if (isInvalid(Loc, Invalid)) return 0;
-  return getPresumedLoc(Loc).getColumn();
+  PresumedLoc PLoc = getPresumedLoc(Loc);
+  if (isInvalid(PLoc, Invalid)) return 0;
+  return PLoc.getColumn();
 }
 
 #ifdef __SSE2__
@@ -1258,15 +1260,19 @@ FoundSpecialChar:
 
     if (Buf[0] == '\n' || Buf[0] == '\r') {
       // If this is \n\r or \r\n, skip both characters.
-      if ((Buf[1] == '\n' || Buf[1] == '\r') && Buf[0] != Buf[1])
-        ++Offs, ++Buf;
-      ++Offs, ++Buf;
+      if ((Buf[1] == '\n' || Buf[1] == '\r') && Buf[0] != Buf[1]) {
+        ++Offs;
+        ++Buf;
+      }
+      ++Offs;
+      ++Buf;
       LineOffsets.push_back(Offs);
     } else {
       // Otherwise, this is a null.  If end of file, exit.
       if (Buf == End) break;
       // Otherwise, skip the null.
-      ++Offs, ++Buf;
+      ++Offs;
+      ++Buf;
     }
   }
 
@@ -1388,8 +1394,9 @@ unsigned SourceManager::getExpansionLineNumber(SourceLocation Loc,
 }
 unsigned SourceManager::getPresumedLineNumber(SourceLocation Loc,
                                               bool *Invalid) const {
-  if (isInvalid(Loc, Invalid)) return 0;
-  return getPresumedLoc(Loc).getLine();
+  PresumedLoc PLoc = getPresumedLoc(Loc);
+  if (isInvalid(PLoc, Invalid)) return 0;
+  return PLoc.getLine();
 }
 
 /// getFileCharacteristic - return the file characteristic of the specified
@@ -2089,10 +2096,10 @@ bool SourceManager::isBeforeInTranslationUnit(SourceLocation LHS,
 
   // Clear the lookup cache, it depends on a common location.
   IsBeforeInTUCache.clear();
-  llvm::MemoryBuffer *LBuf = getBuffer(LOffs.first);
-  llvm::MemoryBuffer *RBuf = getBuffer(ROffs.first);
-  bool LIsBuiltins = strcmp("<built-in>", LBuf->getBufferIdentifier()) == 0;
-  bool RIsBuiltins = strcmp("<built-in>", RBuf->getBufferIdentifier()) == 0;
+  const char *LB = getBuffer(LOffs.first)->getBufferIdentifier();
+  const char *RB = getBuffer(ROffs.first)->getBufferIdentifier();
+  bool LIsBuiltins = strcmp("<built-in>", LB) == 0;
+  bool RIsBuiltins = strcmp("<built-in>", RB) == 0;
   // Sort built-in before non-built-in.
   if (LIsBuiltins || RIsBuiltins) {
     if (LIsBuiltins != RIsBuiltins)
@@ -2101,8 +2108,8 @@ bool SourceManager::isBeforeInTranslationUnit(SourceLocation LHS,
     // lower IDs come first.
     return LOffs.first < ROffs.first;
   }
-  bool LIsAsm = strcmp("<inline asm>", LBuf->getBufferIdentifier()) == 0;
-  bool RIsAsm = strcmp("<inline asm>", RBuf->getBufferIdentifier()) == 0;
+  bool LIsAsm = strcmp("<inline asm>", LB) == 0;
+  bool RIsAsm = strcmp("<inline asm>", RB) == 0;
   // Sort assembler after built-ins, but before the rest.
   if (LIsAsm || RIsAsm) {
     if (LIsAsm != RIsAsm)
@@ -2110,6 +2117,14 @@ bool SourceManager::isBeforeInTranslationUnit(SourceLocation LHS,
     assert(LOffs.first == ROffs.first);
     return false;
   }
+  bool LIsScratch = strcmp("<scratch space>", LB) == 0;
+  bool RIsScratch = strcmp("<scratch space>", RB) == 0;
+  // Sort scratch after inline asm, but before the rest.
+  if (LIsScratch || RIsScratch) {
+    if (LIsScratch != RIsScratch)
+      return LIsScratch;
+    return LOffs.second < ROffs.second;
+  }
   llvm_unreachable("Unsortable locations found");
 }
 
diff --git a/gnu/llvm/tools/clang/lib/Basic/TargetInfo.cpp b/gnu/llvm/tools/clang/lib/Basic/TargetInfo.cpp
index 1648a27d8b3..92f658a6a37 100644
--- a/gnu/llvm/tools/clang/lib/Basic/TargetInfo.cpp
+++ b/gnu/llvm/tools/clang/lib/Basic/TargetInfo.cpp
@@ -30,6 +30,7 @@ TargetInfo::TargetInfo(const llvm::Triple &T) : TargetOpts(), Triple(T) {
   BigEndian = true;
   TLSSupported = true;
   NoAsmVariants = false;
+  HasFloat128 = false;
   PointerWidth = PointerAlign = 32;
   BoolWidth = BoolAlign = 8;
   IntWidth = IntAlign = 32;
@@ -46,6 +47,7 @@ TargetInfo::TargetInfo(const llvm::Triple &T) : TargetOpts(), Triple(T) {
   DoubleAlign = 64;
   LongDoubleWidth = 64;
   LongDoubleAlign = 64;
+  Float128Align = 128;
   LargeArrayMinWidth = 0;
   LargeArrayAlign = 0;
   MaxAtomicPromoteWidth = MaxAtomicInlineWidth = 0;
@@ -66,13 +68,13 @@ TargetInfo::TargetInfo(const llvm::Triple &T) : TargetOpts(), Triple(T) {
   UseSignedCharForObjCBool = true;
   UseBitFieldTypeAlignment = true;
   UseZeroLengthBitfieldAlignment = false;
+  UseExplicitBitFieldAlignment = true;
   ZeroLengthBitfieldBoundary = 0;
   HalfFormat = &llvm::APFloat::IEEEhalf;
   FloatFormat = &llvm::APFloat::IEEEsingle;
   DoubleFormat = &llvm::APFloat::IEEEdouble;
   LongDoubleFormat = &llvm::APFloat::IEEEdouble;
-  DataLayoutString = nullptr;
-  UserLabelPrefix = "_";
+  Float128Format = &llvm::APFloat::IEEEquad;
   MCountName = "mcount";
   RegParmMax = 0;
   SSERegParmMax = 0;
@@ -224,6 +226,8 @@ TargetInfo::RealType TargetInfo::getRealTypeByWidth(unsigned BitWidth) const {
     if (&getLongDoubleFormat() == &llvm::APFloat::PPCDoubleDouble ||
         &getLongDoubleFormat() == &llvm::APFloat::IEEEquad)
       return LongDouble;
+    if (hasFloat128Type())
+      return Float128;
     break;
   }
 
@@ -276,6 +280,10 @@ void TargetInfo::adjust(const LangOptions &Opts) {
     UseBitFieldTypeAlignment = false;
   if (Opts.ShortWChar)
     WCharType = UnsignedShort;
+  if (Opts.AlignDouble) {
+    DoubleAlign = LongLongAlign = 64;
+    LongDoubleAlign = 64;
+  }
 
   if (Opts.OpenCL) {
     // OpenCL C requires specific widths for types, irrespective of
diff --git a/gnu/llvm/tools/clang/lib/Basic/Version.cpp b/gnu/llvm/tools/clang/lib/Basic/Version.cpp
index 58b40cca6fd..4fa52b4acce 100644
--- a/gnu/llvm/tools/clang/lib/Basic/Version.cpp
+++ b/gnu/llvm/tools/clang/lib/Basic/Version.cpp
@@ -36,7 +36,7 @@ std::string getClangRepositoryPath() {
 
   // If the SVN_REPOSITORY is empty, try to use the SVN keyword. This helps us
   // pick up a tag in an SVN export, for example.
-  StringRef SVNRepository("$URL: https://llvm.org/svn/llvm-project/cfe/tags/RELEASE_381/final/lib/Basic/Version.cpp $");
+  StringRef SVNRepository("$URL: https://llvm.org/svn/llvm-project/cfe/tags/RELEASE_391/final/lib/Basic/Version.cpp $");
   if (URL.empty()) {
     URL = SVNRepository.slice(SVNRepository.find(':'),
                               SVNRepository.find("/lib/Basic"));
diff --git a/gnu/llvm/tools/clang/lib/Basic/VirtualFileSystem.cpp b/gnu/llvm/tools/clang/lib/Basic/VirtualFileSystem.cpp
index 6977f400287..8ace2b3dc83 100644
--- a/gnu/llvm/tools/clang/lib/Basic/VirtualFileSystem.cpp
+++ b/gnu/llvm/tools/clang/lib/Basic/VirtualFileSystem.cpp
@@ -16,13 +16,16 @@
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/ADT/iterator_range.h"
+#include "llvm/Config/llvm-config.h"
+#include "llvm/Support/Debug.h"
 #include "llvm/Support/Errc.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Path.h"
+#include "llvm/Support/Process.h"
 #include "llvm/Support/YAMLParser.h"
-#include "llvm/Config/llvm-config.h"
 #include <atomic>
 #include <memory>
+#include <utility>
 
 // For chdir.
 #ifdef LLVM_ON_WIN32
@@ -99,6 +102,9 @@ FileSystem::getBufferForFile(const llvm::Twine &Name, int64_t FileSize,
 }
 
 std::error_code FileSystem::makeAbsolute(SmallVectorImpl<char> &Path) const {
+  if (llvm::sys::path::is_absolute(Path))
+    return std::error_code();
+
   auto WorkingDir = getCurrentWorkingDirectory();
   if (!WorkingDir)
     return WorkingDir.getError();
@@ -111,6 +117,20 @@ bool FileSystem::exists(const Twine &Path) {
   return Status && Status->exists();
 }
 
+#ifndef NDEBUG
+static bool isTraversalComponent(StringRef Component) {
+  return Component.equals("..") || Component.equals(".");
+}
+
+static bool pathHasTraversal(StringRef Path) {
+  using namespace llvm::sys;
+  for (StringRef Comp : llvm::make_range(path::begin(Path), path::end(Path)))
+    if (isTraversalComponent(Comp))
+      return true;
+  return false;
+}
+#endif
+
 //===-----------------------------------------------------------------------===/
 // RealFileSystem implementation
 //===-----------------------------------------------------------------------===/
@@ -120,16 +140,19 @@ namespace {
 class RealFile : public File {
   int FD;
   Status S;
+  std::string RealName;
   friend class RealFileSystem;
-  RealFile(int FD, StringRef NewName)
+  RealFile(int FD, StringRef NewName, StringRef NewRealPathName)
       : FD(FD), S(NewName, {}, {}, {}, {}, {},
-                  llvm::sys::fs::file_type::status_error, {}) {
+                  llvm::sys::fs::file_type::status_error, {}),
+        RealName(NewRealPathName.str()) {
     assert(FD >= 0 && "Invalid or inactive file descriptor");
   }
 
 public:
   ~RealFile() override;
   ErrorOr<Status> status() override;
+  ErrorOr<std::string> getName() override;
   ErrorOr<std::unique_ptr<MemoryBuffer>> getBuffer(const Twine &Name,
                                                    int64_t FileSize,
                                                    bool RequiresNullTerminator,
@@ -150,6 +173,10 @@ ErrorOr<Status> RealFile::status() {
   return S;
 }
 
+ErrorOr<std::string> RealFile::getName() {
+  return RealName.empty() ? S.getName().str() : RealName;
+}
+
 ErrorOr<std::unique_ptr<MemoryBuffer>>
 RealFile::getBuffer(const Twine &Name, int64_t FileSize,
                     bool RequiresNullTerminator, bool IsVolatile) {
@@ -158,21 +185,10 @@ RealFile::getBuffer(const Twine &Name, int64_t FileSize,
                                    IsVolatile);
 }
 
-// FIXME: This is terrible, we need this for ::close.
-#if !defined(_MSC_VER) && !defined(__MINGW32__)
-#include <unistd.h>
-#include <sys/uio.h>
-#else
-#include <io.h>
-#ifndef S_ISFIFO
-#define S_ISFIFO(x) (0)
-#endif
-#endif
 std::error_code RealFile::close() {
-  if (::close(FD))
-    return std::error_code(errno, std::generic_category());
+  std::error_code EC = sys::Process::SafelyCloseFileDescriptor(FD);
   FD = -1;
-  return std::error_code();
+  return EC;
 }
 
 namespace {
@@ -198,9 +214,10 @@ ErrorOr<Status> RealFileSystem::status(const Twine &Path) {
 ErrorOr<std::unique_ptr<File>>
 RealFileSystem::openFileForRead(const Twine &Name) {
   int FD;
-  if (std::error_code EC = sys::fs::openFileForRead(Name, FD))
+  SmallString<256> RealName;
+  if (std::error_code EC = sys::fs::openFileForRead(Name, FD, &RealName))
     return EC;
-  return std::unique_ptr<File>(new RealFile(FD, Name.str()));
+  return std::unique_ptr<File>(new RealFile(FD, Name.str(), RealName.str()));
 }
 
 llvm::ErrorOr<std::string> RealFileSystem::getCurrentWorkingDirectory() const {
@@ -271,7 +288,7 @@ directory_iterator RealFileSystem::dir_begin(const Twine &Dir,
 // OverlayFileSystem implementation
 //===-----------------------------------------------------------------------===/
 OverlayFileSystem::OverlayFileSystem(IntrusiveRefCntPtr<FileSystem> BaseFS) {
-  FSList.push_back(BaseFS);
+  FSList.push_back(std::move(BaseFS));
 }
 
 void OverlayFileSystem::pushOverlay(IntrusiveRefCntPtr<FileSystem> FS) {
@@ -711,7 +728,13 @@ public:
                             Status S)
       : Entry(EK_Directory, Name), Contents(std::move(Contents)),
         S(std::move(S)) {}
+  RedirectingDirectoryEntry(StringRef Name, Status S)
+      : Entry(EK_Directory, Name), S(std::move(S)) {}
   Status getStatus() { return S; }
+  void addContent(std::unique_ptr<Entry> Content) {
+    Contents.push_back(std::move(Content));
+  }
+  Entry *getLastContent() const { return Contents.back().get(); }
   typedef decltype(Contents)::iterator iterator;
   iterator contents_begin() { return Contents.begin(); }
   iterator contents_end() { return Contents.end(); }
@@ -739,6 +762,7 @@ public:
     return UseName == NK_NotSet ? GlobalUseExternalName
                                 : (UseName == NK_External);
   }
+  NameKind getUseName() const { return UseName; }
   static bool classof(const Entry *E) { return E->getKind() == EK_File; }
 };
 
@@ -776,6 +800,7 @@ public:
 /// All configuration options are optional.
 ///   'case-sensitive': <boolean, default=true>
 ///   'use-external-names': <boolean, default=true>
+///   'overlay-relative': <boolean, default=false>
 ///
 /// Virtual directories are represented as
 /// \verbatim
@@ -815,6 +840,10 @@ class RedirectingFileSystem : public vfs::FileSystem {
   std::vector<std::unique_ptr<Entry>> Roots;
   /// \brief The file system to use for external references.
   IntrusiveRefCntPtr<FileSystem> ExternalFS;
+  /// If IsRelativeOverlay is set, this represents the directory
+  /// path that should be prefixed to each 'external-contents' entry
+  /// when reading from YAML files.
+  std::string ExternalContentsPrefixDir;
 
   /// @name Configuration
   /// @{
@@ -822,18 +851,32 @@ class RedirectingFileSystem : public vfs::FileSystem {
   /// \brief Whether to perform case-sensitive comparisons.
   ///
   /// Currently, case-insensitive matching only works correctly with ASCII.
-  bool CaseSensitive;
+  bool CaseSensitive = true;
+
+  /// IsRelativeOverlay marks whether a IsExternalContentsPrefixDir path must
+  /// be prefixed in every 'external-contents' when reading from YAML files.
+  bool IsRelativeOverlay = false;
 
   /// \brief Whether to use to use the value of 'external-contents' for the
   /// names of files.  This global value is overridable on a per-file basis.
-  bool UseExternalNames;
+  bool UseExternalNames = true;
   /// @}
 
+  /// Virtual file paths and external files could be canonicalized without "..",
+  /// "." and "./" in their paths. FIXME: some unittests currently fail on
+  /// win32 when using remove_dots and remove_leading_dotslash on paths.
+  bool UseCanonicalizedPaths =
+#ifdef LLVM_ON_WIN32
+      false;
+#else
+      true;
+#endif
+
   friend class RedirectingFileSystemParser;
 
 private:
   RedirectingFileSystem(IntrusiveRefCntPtr<FileSystem> ExternalFS)
-      : ExternalFS(ExternalFS), CaseSensitive(true), UseExternalNames(true) {}
+      : ExternalFS(std::move(ExternalFS)) {}
 
   /// \brief Looks up \p Path in \c Roots.
   ErrorOr<Entry *> lookupPath(const Twine &Path);
@@ -851,8 +894,8 @@ public:
   /// returns a virtual file system representing its contents.
   static RedirectingFileSystem *
   create(std::unique_ptr<MemoryBuffer> Buffer,
-         SourceMgr::DiagHandlerTy DiagHandler, void *DiagContext,
-         IntrusiveRefCntPtr<FileSystem> ExternalFS);
+         SourceMgr::DiagHandlerTy DiagHandler, StringRef YAMLFilePath,
+         void *DiagContext, IntrusiveRefCntPtr<FileSystem> ExternalFS);
 
   ErrorOr<Status> status(const Twine &Path) override;
   ErrorOr<std::unique_ptr<File>> openFileForRead(const Twine &Path) override;
@@ -885,6 +928,38 @@ public:
     return directory_iterator(std::make_shared<VFSFromYamlDirIterImpl>(Dir,
         *this, D->contents_begin(), D->contents_end(), EC));
   }
+
+  void setExternalContentsPrefixDir(StringRef PrefixDir) {
+    ExternalContentsPrefixDir = PrefixDir.str();
+  }
+
+  StringRef getExternalContentsPrefixDir() const {
+    return ExternalContentsPrefixDir;
+  }
+
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+LLVM_DUMP_METHOD void dump() const {
+    for (const std::unique_ptr<Entry> &Root : Roots)
+      dumpEntry(Root.get());
+  }
+
+LLVM_DUMP_METHOD void dumpEntry(Entry *E, int NumSpaces = 0) const {
+    StringRef Name = E->getName();
+    for (int i = 0, e = NumSpaces; i < e; ++i)
+      dbgs() << " ";
+    dbgs() << "'" << Name.str().c_str() << "'" << "\n";
+
+    if (E->getKind() == EK_Directory) {
+      auto *DE = dyn_cast<RedirectingDirectoryEntry>(E);
+      assert(DE && "Should be a directory");
+
+      for (std::unique_ptr<Entry> &SubEntry :
+           llvm::make_range(DE->contents_begin(), DE->contents_end()))
+        dumpEntry(SubEntry.get(), NumSpaces+2);
+    }
+  }
+#endif
+
 };
 
 /// \brief A helper class to hold the common YAML parsing state.
@@ -964,7 +1039,71 @@ class RedirectingFileSystemParser {
     return true;
   }
 
-  std::unique_ptr<Entry> parseEntry(yaml::Node *N) {
+  Entry *lookupOrCreateEntry(RedirectingFileSystem *FS, StringRef Name,
+                             Entry *ParentEntry = nullptr) {
+    if (!ParentEntry) { // Look for a existent root
+      for (const std::unique_ptr<Entry> &Root : FS->Roots) {
+        if (Name.equals(Root->getName())) {
+          ParentEntry = Root.get();
+          return ParentEntry;
+        }
+      }
+    } else { // Advance to the next component
+      auto *DE = dyn_cast<RedirectingDirectoryEntry>(ParentEntry);
+      for (std::unique_ptr<Entry> &Content :
+           llvm::make_range(DE->contents_begin(), DE->contents_end())) {
+        auto *DirContent = dyn_cast<RedirectingDirectoryEntry>(Content.get());
+        if (DirContent && Name.equals(Content->getName()))
+          return DirContent;
+      }
+    }
+
+    // ... or create a new one
+    std::unique_ptr<Entry> E = llvm::make_unique<RedirectingDirectoryEntry>(
+        Name, Status("", getNextVirtualUniqueID(), sys::TimeValue::now(), 0, 0,
+                     0, file_type::directory_file, sys::fs::all_all));
+
+    if (!ParentEntry) { // Add a new root to the overlay
+      FS->Roots.push_back(std::move(E));
+      ParentEntry = FS->Roots.back().get();
+      return ParentEntry;
+    }
+
+    auto *DE = dyn_cast<RedirectingDirectoryEntry>(ParentEntry);
+    DE->addContent(std::move(E));
+    return DE->getLastContent();
+  }
+
+  void uniqueOverlayTree(RedirectingFileSystem *FS, Entry *SrcE,
+                         Entry *NewParentE = nullptr) {
+    StringRef Name = SrcE->getName();
+    switch (SrcE->getKind()) {
+    case EK_Directory: {
+      auto *DE = dyn_cast<RedirectingDirectoryEntry>(SrcE);
+      assert(DE && "Must be a directory");
+      // Empty directories could be present in the YAML as a way to
+      // describe a file for a current directory after some of its subdir
+      // is parsed. This only leads to redundant walks, ignore it.
+      if (!Name.empty())
+        NewParentE = lookupOrCreateEntry(FS, Name, NewParentE);
+      for (std::unique_ptr<Entry> &SubEntry :
+           llvm::make_range(DE->contents_begin(), DE->contents_end()))
+        uniqueOverlayTree(FS, SubEntry.get(), NewParentE);
+      break;
+    }
+    case EK_File: {
+      auto *FE = dyn_cast<RedirectingFileEntry>(SrcE);
+      assert(FE && "Must be a file");
+      assert(NewParentE && "Parent entry must exist");
+      auto *DE = dyn_cast<RedirectingDirectoryEntry>(NewParentE);
+      DE->addContent(llvm::make_unique<RedirectingFileEntry>(
+          Name, FE->getExternalContentsPath(), FE->getUseName()));
+      break;
+    }
+    }
+  }
+
+  std::unique_ptr<Entry> parseEntry(yaml::Node *N, RedirectingFileSystem *FS) {
     yaml::MappingNode *M = dyn_cast<yaml::MappingNode>(N);
     if (!M) {
       error(N, "expected mapping node for file or directory entry");
@@ -1004,7 +1143,17 @@ class RedirectingFileSystemParser {
       if (Key == "name") {
         if (!parseScalarString(I->getValue(), Value, Buffer))
           return nullptr;
-        Name = Value;
+
+        if (FS->UseCanonicalizedPaths) {
+          SmallString<256> Path(Value);
+          // Guarantee that old YAML files containing paths with ".." and "."
+          // are properly canonicalized before read into the VFS.
+          Path = sys::path::remove_leading_dotslash(Path);
+          sys::path::remove_dots(Path, /*remove_dot_dot=*/true);
+          Name = Path.str();
+        } else {
+          Name = Value;
+        }
       } else if (Key == "type") {
         if (!parseScalarString(I->getValue(), Value, Buffer))
           return nullptr;
@@ -1034,7 +1183,7 @@ class RedirectingFileSystemParser {
         for (yaml::SequenceNode::iterator I = Contents->begin(),
                                           E = Contents->end();
              I != E; ++I) {
-          if (std::unique_ptr<Entry> E = parseEntry(&*I))
+          if (std::unique_ptr<Entry> E = parseEntry(&*I, FS))
             EntryArrayContents.push_back(std::move(E));
           else
             return nullptr;
@@ -1048,7 +1197,24 @@ class RedirectingFileSystemParser {
         HasContents = true;
         if (!parseScalarString(I->getValue(), Value, Buffer))
           return nullptr;
-        ExternalContentsPath = Value;
+
+        SmallString<256> FullPath;
+        if (FS->IsRelativeOverlay) {
+          FullPath = FS->getExternalContentsPrefixDir();
+          assert(!FullPath.empty() &&
+                 "External contents prefix directory must exist");
+          llvm::sys::path::append(FullPath, Value);
+        } else {
+          FullPath = Value;
+        }
+
+        if (FS->UseCanonicalizedPaths) {
+          // Guarantee that old YAML files containing paths with ".." and "."
+          // are properly canonicalized before read into the VFS.
+          FullPath = sys::path::remove_leading_dotslash(FullPath);
+          sys::path::remove_dots(FullPath, /*remove_dot_dot=*/true);
+        }
+        ExternalContentsPath = FullPath.str();
       } else if (Key == "use-external-name") {
         bool Val;
         if (!parseScalarBool(I->getValue(), Val))
@@ -1134,10 +1300,12 @@ public:
       KeyStatusPair("version", true),
       KeyStatusPair("case-sensitive", false),
       KeyStatusPair("use-external-names", false),
+      KeyStatusPair("overlay-relative", false),
       KeyStatusPair("roots", true),
     };
 
     DenseMap<StringRef, KeyStatus> Keys(std::begin(Fields), std::end(Fields));
+    std::vector<std::unique_ptr<Entry>> RootEntries;
 
     // Parse configuration and 'roots'
     for (yaml::MappingNode::iterator I = Top->begin(), E = Top->end(); I != E;
@@ -1159,8 +1327,8 @@ public:
 
         for (yaml::SequenceNode::iterator I = Roots->begin(), E = Roots->end();
              I != E; ++I) {
-          if (std::unique_ptr<Entry> E = parseEntry(&*I))
-            FS->Roots.push_back(std::move(E));
+          if (std::unique_ptr<Entry> E = parseEntry(&*I, FS))
+            RootEntries.push_back(std::move(E));
           else
             return false;
         }
@@ -1185,6 +1353,9 @@ public:
       } else if (Key == "case-sensitive") {
         if (!parseScalarBool(I->getValue(), FS->CaseSensitive))
           return false;
+      } else if (Key == "overlay-relative") {
+        if (!parseScalarBool(I->getValue(), FS->IsRelativeOverlay))
+          return false;
       } else if (Key == "use-external-names") {
         if (!parseScalarBool(I->getValue(), FS->UseExternalNames))
           return false;
@@ -1198,6 +1369,13 @@ public:
 
     if (!checkMissingKeys(Top, Keys))
       return false;
+
+    // Now that we sucessefully parsed the YAML file, canonicalize the internal
+    // representation to a proper directory tree so that we can search faster
+    // inside the VFS.
+    for (std::unique_ptr<Entry> &E : RootEntries)
+      uniqueOverlayTree(FS, E.get());
+
     return true;
   }
 };
@@ -1205,9 +1383,11 @@ public:
 
 Entry::~Entry() = default;
 
-RedirectingFileSystem *RedirectingFileSystem::create(
-    std::unique_ptr<MemoryBuffer> Buffer, SourceMgr::DiagHandlerTy DiagHandler,
-    void *DiagContext, IntrusiveRefCntPtr<FileSystem> ExternalFS) {
+RedirectingFileSystem *
+RedirectingFileSystem::create(std::unique_ptr<MemoryBuffer> Buffer,
+                              SourceMgr::DiagHandlerTy DiagHandler,
+                              StringRef YAMLFilePath, void *DiagContext,
+                              IntrusiveRefCntPtr<FileSystem> ExternalFS) {
 
   SourceMgr SM;
   yaml::Stream Stream(Buffer->getMemBufferRef(), SM);
@@ -1223,7 +1403,24 @@ RedirectingFileSystem *RedirectingFileSystem::create(
   RedirectingFileSystemParser P(Stream);
 
   std::unique_ptr<RedirectingFileSystem> FS(
-      new RedirectingFileSystem(ExternalFS));
+      new RedirectingFileSystem(std::move(ExternalFS)));
+
+  if (!YAMLFilePath.empty()) {
+    // Use the YAML path from -ivfsoverlay to compute the dir to be prefixed
+    // to each 'external-contents' path.
+    //
+    // Example:
+    //    -ivfsoverlay dummy.cache/vfs/vfs.yaml
+    // yields:
+    //  FS->ExternalContentsPrefixDir => /<absolute_path_to>/dummy.cache/vfs
+    //
+    SmallString<256> OverlayAbsDir = sys::path::parent_path(YAMLFilePath);
+    std::error_code EC = llvm::sys::fs::make_absolute(OverlayAbsDir);
+    assert(!EC && "Overlay dir final path must be absolute");
+    (void)EC;
+    FS->setExternalContentsPrefixDir(OverlayAbsDir);
+  }
+
   if (!P.parse(Root, FS.get()))
     return nullptr;
 
@@ -1238,6 +1435,14 @@ ErrorOr<Entry *> RedirectingFileSystem::lookupPath(const Twine &Path_) {
   if (std::error_code EC = makeAbsolute(Path))
     return EC;
 
+  // Canonicalize path by removing ".", "..", "./", etc components. This is
+  // a VFS request, do bot bother about symlinks in the path components
+  // but canonicalize in order to perform the correct entry search.
+  if (UseCanonicalizedPaths) {
+    Path = sys::path::remove_leading_dotslash(Path);
+    sys::path::remove_dots(Path, /*remove_dot_dot=*/true);
+  }
+
   if (Path.empty())
     return make_error_code(llvm::errc::invalid_argument);
 
@@ -1254,20 +1459,32 @@ ErrorOr<Entry *> RedirectingFileSystem::lookupPath(const Twine &Path_) {
 ErrorOr<Entry *>
 RedirectingFileSystem::lookupPath(sys::path::const_iterator Start,
                                   sys::path::const_iterator End, Entry *From) {
+#ifndef LLVM_ON_WIN32
+  assert(!isTraversalComponent(*Start) &&
+         !isTraversalComponent(From->getName()) &&
+         "Paths should not contain traversal components");
+#else
+  // FIXME: this is here to support windows, remove it once canonicalized
+  // paths become globally default.
   if (Start->equals("."))
     ++Start;
+#endif
 
-  // FIXME: handle ..
-  if (CaseSensitive ? !Start->equals(From->getName())
-                    : !Start->equals_lower(From->getName()))
-    // failure to match
-    return make_error_code(llvm::errc::no_such_file_or_directory);
+  StringRef FromName = From->getName();
 
-  ++Start;
+  // Forward the search to the next component in case this is an empty one.
+  if (!FromName.empty()) {
+    if (CaseSensitive ? !Start->equals(FromName)
+                      : !Start->equals_lower(FromName))
+      // failure to match
+      return make_error_code(llvm::errc::no_such_file_or_directory);
 
-  if (Start == End) {
-    // Match!
-    return From;
+    ++Start;
+
+    if (Start == End) {
+      // Match!
+      return From;
+    }
   }
 
   auto *DE = dyn_cast<RedirectingDirectoryEntry>(From);
@@ -1322,7 +1539,7 @@ class FileWithFixedStatus : public File {
 
 public:
   FileWithFixedStatus(std::unique_ptr<File> InnerFile, Status S)
-      : InnerFile(std::move(InnerFile)), S(S) {}
+      : InnerFile(std::move(InnerFile)), S(std::move(S)) {}
 
   ErrorOr<Status> status() override { return S; }
   ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
@@ -1362,10 +1579,13 @@ RedirectingFileSystem::openFileForRead(const Twine &Path) {
 
 IntrusiveRefCntPtr<FileSystem>
 vfs::getVFSFromYAML(std::unique_ptr<MemoryBuffer> Buffer,
-                    SourceMgr::DiagHandlerTy DiagHandler, void *DiagContext,
+                    SourceMgr::DiagHandlerTy DiagHandler,
+                    StringRef YAMLFilePath,
+                    void *DiagContext,
                     IntrusiveRefCntPtr<FileSystem> ExternalFS) {
   return RedirectingFileSystem::create(std::move(Buffer), DiagHandler,
-                                       DiagContext, ExternalFS);
+                                       YAMLFilePath, DiagContext,
+                                       std::move(ExternalFS));
 }
 
 UniqueID vfs::getNextVirtualUniqueID() {
@@ -1376,16 +1596,6 @@ UniqueID vfs::getNextVirtualUniqueID() {
   return UniqueID(std::numeric_limits<uint64_t>::max(), ID);
 }
 
-#ifndef NDEBUG
-static bool pathHasTraversal(StringRef Path) {
-  using namespace llvm::sys;
-  for (StringRef Comp : llvm::make_range(path::begin(Path), path::end(Path)))
-    if (Comp == "." || Comp == "..")
-      return true;
-  return false;
-}
-#endif
-
 void YAMLVFSWriter::addFileMapping(StringRef VirtualPath, StringRef RealPath) {
   assert(sys::path::is_absolute(VirtualPath) && "virtual path not absolute");
   assert(sys::path::is_absolute(RealPath) && "real path not absolute");
@@ -1407,7 +1617,9 @@ class JSONWriter {
 
 public:
   JSONWriter(llvm::raw_ostream &OS) : OS(OS) {}
-  void write(ArrayRef<YAMLVFSEntry> Entries, Optional<bool> IsCaseSensitive);
+  void write(ArrayRef<YAMLVFSEntry> Entries, Optional<bool> UseExternalNames,
+             Optional<bool> IsCaseSensitive, Optional<bool> IsOverlayRelative,
+             StringRef OverlayDir);
 };
 }
 
@@ -1460,7 +1672,10 @@ void JSONWriter::writeEntry(StringRef VPath, StringRef RPath) {
 }
 
 void JSONWriter::write(ArrayRef<YAMLVFSEntry> Entries,
-                       Optional<bool> IsCaseSensitive) {
+                       Optional<bool> UseExternalNames,
+                       Optional<bool> IsCaseSensitive,
+                       Optional<bool> IsOverlayRelative,
+                       StringRef OverlayDir) {
   using namespace llvm::sys;
 
   OS << "{\n"
@@ -1468,12 +1683,30 @@ void JSONWriter::write(ArrayRef<YAMLVFSEntry> Entries,
   if (IsCaseSensitive.hasValue())
     OS << "  'case-sensitive': '"
        << (IsCaseSensitive.getValue() ? "true" : "false") << "',\n";
+  if (UseExternalNames.hasValue())
+    OS << "  'use-external-names': '"
+       << (UseExternalNames.getValue() ? "true" : "false") << "',\n";
+  bool UseOverlayRelative = false;
+  if (IsOverlayRelative.hasValue()) {
+    UseOverlayRelative = IsOverlayRelative.getValue();
+    OS << "  'overlay-relative': '"
+       << (UseOverlayRelative ? "true" : "false") << "',\n";
+  }
   OS << "  'roots': [\n";
 
   if (!Entries.empty()) {
     const YAMLVFSEntry &Entry = Entries.front();
     startDirectory(path::parent_path(Entry.VPath));
-    writeEntry(path::filename(Entry.VPath), Entry.RPath);
+
+    StringRef RPath = Entry.RPath;
+    if (UseOverlayRelative) {
+      unsigned OverlayDirLen = OverlayDir.size();
+      assert(RPath.substr(0, OverlayDirLen) == OverlayDir &&
+             "Overlay dir must be contained in RPath");
+      RPath = RPath.slice(OverlayDirLen, RPath.size());
+    }
+
+    writeEntry(path::filename(Entry.VPath), RPath);
 
     for (const auto &Entry : Entries.slice(1)) {
       StringRef Dir = path::parent_path(Entry.VPath);
@@ -1487,7 +1720,14 @@ void JSONWriter::write(ArrayRef<YAMLVFSEntry> Entries,
         OS << ",\n";
         startDirectory(Dir);
       }
-      writeEntry(path::filename(Entry.VPath), Entry.RPath);
+      StringRef RPath = Entry.RPath;
+      if (UseOverlayRelative) {
+        unsigned OverlayDirLen = OverlayDir.size();
+        assert(RPath.substr(0, OverlayDirLen) == OverlayDir &&
+               "Overlay dir must be contained in RPath");
+        RPath = RPath.slice(OverlayDirLen, RPath.size());
+      }
+      writeEntry(path::filename(Entry.VPath), RPath);
     }
 
     while (!DirStack.empty()) {
@@ -1507,7 +1747,8 @@ void YAMLVFSWriter::write(llvm::raw_ostream &OS) {
     return LHS.VPath < RHS.VPath;
   });
 
-  JSONWriter(OS).write(Mappings, IsCaseSensitive);
+  JSONWriter(OS).write(Mappings, UseExternalNames, IsCaseSensitive,
+                       IsOverlayRelative, OverlayDir);
 }
 
 VFSFromYamlDirIterImpl::VFSFromYamlDirIterImpl(