7 files changed, 696 insertions, 432 deletions
diff --git a/contrib/llvm/lib/LTO/Caching.cpp b/contrib/llvm/lib/LTO/Caching.cpp
index fd5bdb0..e32e46c 100644
--- a/contrib/llvm/lib/LTO/Caching.cpp
+++ b/contrib/llvm/lib/LTO/Caching.cpp
@@ -13,6 +13,7 @@
 
 #include "llvm/LTO/Caching.h"
 #include "llvm/ADT/StringExtras.h"
+#include "llvm/Support/Errc.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Path.h"
@@ -21,70 +22,71 @@
 using namespace llvm;
 using namespace llvm::lto;
 
-static void commitEntry(StringRef TempFilename, StringRef EntryPath) {
-  // Rename to final destination (hopefully race condition won't matter here)
-  auto EC = sys::fs::rename(TempFilename, EntryPath);
-  if (EC) {
-    // Renaming failed, probably not the same filesystem, copy and delete.
-    // FIXME: Avoid needing to do this by creating the temporary file in the
-    // cache directory.
-    {
-      auto ReloadedBufferOrErr = MemoryBuffer::getFile(TempFilename);
-      if (auto EC = ReloadedBufferOrErr.getError())
-        report_fatal_error(Twine("Failed to open temp file '") + TempFilename +
-                           "': " + EC.message() + "\n");
+Expected<NativeObjectCache> lto::localCache(StringRef CacheDirectoryPath,
+                                            AddBufferFn AddBuffer) {
+  if (std::error_code EC = sys::fs::create_directories(CacheDirectoryPath))
+    return errorCodeToError(EC);
 
-      raw_fd_ostream OS(EntryPath, EC, sys::fs::F_None);
-      if (EC)
-        report_fatal_error(Twine("Failed to open ") + EntryPath +
-                           " to save cached entry\n");
-      // I'm not sure what are the guarantee if two processes are doing this
-      // at the same time.
-      OS << (*ReloadedBufferOrErr)->getBuffer();
-    }
-    sys::fs::remove(TempFilename);
-  }
-}
-
-NativeObjectCache lto::localCache(std::string CacheDirectoryPath,
-                                  AddFileFn AddFile) {
   return [=](unsigned Task, StringRef Key) -> AddStreamFn {
-    // First, see if we have a cache hit.
+    // This choice of file name allows the cache to be pruned (see pruneCache()
+    // in include/llvm/Support/CachePruning.h).
     SmallString<64> EntryPath;
-    sys::path::append(EntryPath, CacheDirectoryPath, Key);
-    if (sys::fs::exists(EntryPath)) {
-      AddFile(Task, EntryPath);
+    sys::path::append(EntryPath, CacheDirectoryPath, "llvmcache-" + Key);
+    // First, see if we have a cache hit.
+    ErrorOr<std::unique_ptr<MemoryBuffer>> MBOrErr =
+        MemoryBuffer::getFile(EntryPath);
+    if (MBOrErr) {
+      AddBuffer(Task, std::move(*MBOrErr));
       return AddStreamFn();
     }
 
+    if (MBOrErr.getError() != errc::no_such_file_or_directory)
+      report_fatal_error(Twine("Failed to open cache file ") + EntryPath +
+                         ": " + MBOrErr.getError().message() + "\n");
+
     // This native object stream is responsible for commiting the resulting
-    // file to the cache and calling AddFile to add it to the link.
+    // file to the cache and calling AddBuffer to add it to the link.
     struct CacheStream : NativeObjectStream {
-      AddFileFn AddFile;
+      AddBufferFn AddBuffer;
       std::string TempFilename;
       std::string EntryPath;
       unsigned Task;
 
-      CacheStream(std::unique_ptr<raw_pwrite_stream> OS, AddFileFn AddFile,
+      CacheStream(std::unique_ptr<raw_pwrite_stream> OS, AddBufferFn AddBuffer,
                   std::string TempFilename, std::string EntryPath,
                   unsigned Task)
-          : NativeObjectStream(std::move(OS)), AddFile(AddFile),
-            TempFilename(TempFilename), EntryPath(EntryPath), Task(Task) {}
+          : NativeObjectStream(std::move(OS)), AddBuffer(std::move(AddBuffer)),
+            TempFilename(std::move(TempFilename)),
+            EntryPath(std::move(EntryPath)), Task(Task) {}
 
       ~CacheStream() {
+        // FIXME: This code could race with the cache pruner, but it is unlikely
+        // that the cache pruner will choose to remove a newly created file.
+
         // Make sure the file is closed before committing it.
         OS.reset();
-        commitEntry(TempFilename, EntryPath);
-        AddFile(Task, EntryPath);
+        // This is atomic on POSIX systems.
+        if (auto EC = sys::fs::rename(TempFilename, EntryPath))
+          report_fatal_error(Twine("Failed to rename temporary file ") +
+                             TempFilename + ": " + EC.message() + "\n");
+
+        ErrorOr<std::unique_ptr<MemoryBuffer>> MBOrErr =
+            MemoryBuffer::getFile(EntryPath);
+        if (!MBOrErr)
+          report_fatal_error(Twine("Failed to open cache file ") + EntryPath +
+                             ": " + MBOrErr.getError().message() + "\n");
+        AddBuffer(Task, std::move(*MBOrErr));
       }
     };
 
     return [=](size_t Task) -> std::unique_ptr<NativeObjectStream> {
       // Write to a temporary to avoid race condition
       int TempFD;
-      SmallString<64> TempFilename;
+      SmallString<64> TempFilenameModel, TempFilename;
+      sys::path::append(TempFilenameModel, CacheDirectoryPath, "Thin-%%%%%%.tmp.o");
       std::error_code EC =
-          sys::fs::createTemporaryFile("Thin", "tmp.o", TempFD, TempFilename);
+          sys::fs::createUniqueFile(TempFilenameModel, TempFD, TempFilename,
+                                    sys::fs::owner_read | sys::fs::owner_write);
       if (EC) {
         errs() << "Error: " << EC.message() << "\n";
         report_fatal_error("ThinLTO: Can't get a temporary file");
@@ -93,7 +95,7 @@ NativeObjectCache lto::localCache(std::string CacheDirectoryPath,
       // This CacheStream will move the temporary file into the cache when done.
       return llvm::make_unique<CacheStream>(
           llvm::make_unique<raw_fd_ostream>(TempFD, /* ShouldClose */ true),
-          AddFile, TempFilename.str(), EntryPath.str(), Task);
+          AddBuffer, TempFilename.str(), EntryPath.str(), Task);
     };
   };
 }
diff --git a/contrib/llvm/lib/LTO/LTO.cpp b/contrib/llvm/lib/LTO/LTO.cpp
index e3e2f9f..1997394 100644
--- a/contrib/llvm/lib/LTO/LTO.cpp
+++ b/contrib/llvm/lib/LTO/LTO.cpp
@@ -20,9 +20,12 @@
 #include "llvm/IR/AutoUpgrade.h"
 #include "llvm/IR/DiagnosticPrinter.h"
 #include "llvm/IR/LegacyPassManager.h"
+#include "llvm/IR/Mangler.h"
+#include "llvm/IR/Metadata.h"
 #include "llvm/LTO/LTOBackend.h"
 #include "llvm/Linker/IRMover.h"
-#include "llvm/Object/ModuleSummaryIndexObjectFile.h"
+#include "llvm/Object/IRObjectFile.h"
+#include "llvm/Support/Error.h"
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Path.h"
@@ -31,6 +34,7 @@
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Support/ThreadPool.h"
 #include "llvm/Support/Threading.h"
+#include "llvm/Support/VCSRevision.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetOptions.h"
@@ -46,6 +50,12 @@ using namespace object;
 
 #define DEBUG_TYPE "lto"
 
+// The values are (type identifier, summary) pairs.
+typedef DenseMap<
+    GlobalValue::GUID,
+    TinyPtrVector<const std::pair<const std::string, TypeIdSummary> *>>
+    TypeIdSummariesByGuidTy;
+
 // Returns a unique hash for the Module considering the current list of
 // export/import and other global analysis results.
 // The hash is produced in \p Key.
@@ -54,7 +64,8 @@ static void computeCacheKey(
     StringRef ModuleID, const FunctionImporter::ImportMapTy &ImportList,
     const FunctionImporter::ExportSetTy &ExportList,
     const std::map<GlobalValue::GUID, GlobalValue::LinkageTypes> &ResolvedODR,
-    const GVSummaryMapTy &DefinedGlobals) {
+    const GVSummaryMapTy &DefinedGlobals,
+    const TypeIdSummariesByGuidTy &TypeIdSummariesByGuid) {
   // Compute the unique hash for this entry.
   // This is based on the current compiler version, the module itself, the
   // export list, the hash for every single module in the import list, the
@@ -63,7 +74,7 @@ static void computeCacheKey(
 
   // Start with the compiler revision
   Hasher.update(LLVM_VERSION_STRING);
-#ifdef HAVE_LLVM_REVISION
+#ifdef LLVM_REVISION
   Hasher.update(LLVM_REVISION);
 #endif
 
@@ -80,6 +91,18 @@ static void computeCacheKey(
     Data[3] = I >> 24;
     Hasher.update(ArrayRef<uint8_t>{Data, 4});
   };
+  auto AddUint64 = [&](uint64_t I) {
+    uint8_t Data[8];
+    Data[0] = I;
+    Data[1] = I >> 8;
+    Data[2] = I >> 16;
+    Data[3] = I >> 24;
+    Data[4] = I >> 32;
+    Data[5] = I >> 40;
+    Data[6] = I >> 48;
+    Data[7] = I >> 56;
+    Hasher.update(ArrayRef<uint8_t>{Data, 8});
+  };
   AddString(Conf.CPU);
   // FIXME: Hash more of Options. For now all clients initialize Options from
   // command-line flags (which is unsupported in production), but may set
@@ -91,10 +114,15 @@ static void computeCacheKey(
   AddUnsigned((unsigned)Conf.Options.DebuggerTuning);
   for (auto &A : Conf.MAttrs)
     AddString(A);
-  AddUnsigned(Conf.RelocModel);
+  if (Conf.RelocModel)
+    AddUnsigned(*Conf.RelocModel);
+  else
+    AddUnsigned(-1);
   AddUnsigned(Conf.CodeModel);
   AddUnsigned(Conf.CGOptLevel);
+  AddUnsigned(Conf.CGFileType);
   AddUnsigned(Conf.OptLevel);
+  AddUnsigned(Conf.UseNewPM);
   AddString(Conf.OptPipeline);
   AddString(Conf.AAPipeline);
   AddString(Conf.OverrideTriple);
@@ -107,10 +135,16 @@ static void computeCacheKey(
     // The export list can impact the internalization, be conservative here
     Hasher.update(ArrayRef<uint8_t>((uint8_t *)&F, sizeof(F)));
 
-  // Include the hash for every module we import functions from
+  // Include the hash for every module we import functions from. The set of
+  // imported symbols for each module may affect code generation and is
+  // sensitive to link order, so include that as well.
   for (auto &Entry : ImportList) {
     auto ModHash = Index.getModuleHash(Entry.first());
     Hasher.update(ArrayRef<uint8_t>((uint8_t *)&ModHash[0], sizeof(ModHash)));
+
+    AddUint64(Entry.second.size());
+    for (auto &Fn : Entry.second)
+      AddUint64(Fn.first);
   }
 
   // Include the hash for the resolved ODR.
@@ -121,12 +155,68 @@ static void computeCacheKey(
                                     sizeof(GlobalValue::LinkageTypes)));
   }
 
+  std::set<GlobalValue::GUID> UsedTypeIds;
+
+  auto AddUsedTypeIds = [&](GlobalValueSummary *GS) {
+    auto *FS = dyn_cast_or_null<FunctionSummary>(GS);
+    if (!FS)
+      return;
+    for (auto &TT : FS->type_tests())
+      UsedTypeIds.insert(TT);
+    for (auto &TT : FS->type_test_assume_vcalls())
+      UsedTypeIds.insert(TT.GUID);
+    for (auto &TT : FS->type_checked_load_vcalls())
+      UsedTypeIds.insert(TT.GUID);
+    for (auto &TT : FS->type_test_assume_const_vcalls())
+      UsedTypeIds.insert(TT.VFunc.GUID);
+    for (auto &TT : FS->type_checked_load_const_vcalls())
+      UsedTypeIds.insert(TT.VFunc.GUID);
+  };
+
   // Include the hash for the linkage type to reflect internalization and weak
-  // resolution.
+  // resolution, and collect any used type identifier resolutions.
   for (auto &GS : DefinedGlobals) {
     GlobalValue::LinkageTypes Linkage = GS.second->linkage();
     Hasher.update(
         ArrayRef<uint8_t>((const uint8_t *)&Linkage, sizeof(Linkage)));
+    AddUsedTypeIds(GS.second);
+  }
+
+  // Imported functions may introduce new uses of type identifier resolutions,
+  // so we need to collect their used resolutions as well.
+  for (auto &ImpM : ImportList)
+    for (auto &ImpF : ImpM.second)
+      AddUsedTypeIds(Index.findSummaryInModule(ImpF.first, ImpM.first()));
+
+  auto AddTypeIdSummary = [&](StringRef TId, const TypeIdSummary &S) {
+    AddString(TId);
+
+    AddUnsigned(S.TTRes.TheKind);
+    AddUnsigned(S.TTRes.SizeM1BitWidth);
+
+    AddUint64(S.WPDRes.size());
+    for (auto &WPD : S.WPDRes) {
+      AddUnsigned(WPD.first);
+      AddUnsigned(WPD.second.TheKind);
+      AddString(WPD.second.SingleImplName);
+
+      AddUint64(WPD.second.ResByArg.size());
+      for (auto &ByArg : WPD.second.ResByArg) {
+        AddUint64(ByArg.first.size());
+        for (uint64_t Arg : ByArg.first)
+          AddUint64(Arg);
+        AddUnsigned(ByArg.second.TheKind);
+        AddUint64(ByArg.second.Info);
+      }
+    }
+  };
+
+  // Include the hash for all type identifiers used by this module.
+  for (GlobalValue::GUID TId : UsedTypeIds) {
+    auto SummariesI = TypeIdSummariesByGuid.find(TId);
+    if (SummariesI != TypeIdSummariesByGuid.end())
+      for (auto *Summary : SummariesI->second)
+        AddTypeIdSummary(Summary->first, Summary->second);
   }
 
   if (!Conf.SampleProfile.empty()) {
@@ -164,9 +254,7 @@ static void thinLTOResolveWeakForLinkerGUID(
     }
     // Alias and aliasee can't be turned into available_externally.
     else if (!isa<AliasSummary>(S.get()) &&
-             !GlobalInvolvedWithAlias.count(S.get()) &&
-             (GlobalValue::isLinkOnceODRLinkage(OriginalLinkage) ||
-              GlobalValue::isWeakODRLinkage(OriginalLinkage)))
+             !GlobalInvolvedWithAlias.count(S.get()))
       S->setLinkage(GlobalValue::AvailableExternallyLinkage);
     if (S->linkage() != OriginalLinkage)
       recordNewLinkage(S->modulePath(), GUID, S->linkage());
@@ -190,13 +278,14 @@ void llvm::thinLTOResolveWeakForLinkerInIndex(
   // when needed.
   DenseSet<GlobalValueSummary *> GlobalInvolvedWithAlias;
   for (auto &I : Index)
-    for (auto &S : I.second)
+    for (auto &S : I.second.SummaryList)
       if (auto AS = dyn_cast<AliasSummary>(S.get()))
         GlobalInvolvedWithAlias.insert(&AS->getAliasee());
 
   for (auto &I : Index)
-    thinLTOResolveWeakForLinkerGUID(I.second, I.first, GlobalInvolvedWithAlias,
-                                    isPrevailing, recordNewLinkage);
+    thinLTOResolveWeakForLinkerGUID(I.second.SummaryList, I.first,
+                                    GlobalInvolvedWithAlias, isPrevailing,
+                                    recordNewLinkage);
 }
 
 static void thinLTOInternalizeAndPromoteGUID(
@@ -217,92 +306,42 @@ void llvm::thinLTOInternalizeAndPromoteInIndex(
     ModuleSummaryIndex &Index,
     function_ref<bool(StringRef, GlobalValue::GUID)> isExported) {
   for (auto &I : Index)
-    thinLTOInternalizeAndPromoteGUID(I.second, I.first, isExported);
+    thinLTOInternalizeAndPromoteGUID(I.second.SummaryList, I.first, isExported);
 }
 
-struct InputFile::InputModule {
-  BitcodeModule BM;
-  std::unique_ptr<Module> Mod;
-
-  // The range of ModuleSymbolTable entries for this input module.
-  size_t SymBegin, SymEnd;
-};
-
 // Requires a destructor for std::vector<InputModule>.
 InputFile::~InputFile() = default;
 
 Expected<std::unique_ptr<InputFile>> InputFile::create(MemoryBufferRef Object) {
   std::unique_ptr<InputFile> File(new InputFile);
 
-  ErrorOr<MemoryBufferRef> BCOrErr =
-      IRObjectFile::findBitcodeInMemBuffer(Object);
-  if (!BCOrErr)
-    return errorCodeToError(BCOrErr.getError());
-
-  Expected<std::vector<BitcodeModule>> BMsOrErr =
-      getBitcodeModuleList(*BCOrErr);
-  if (!BMsOrErr)
-    return BMsOrErr.takeError();
-
-  if (BMsOrErr->empty())
-    return make_error<StringError>("Bitcode file does not contain any modules",
-                                   inconvertibleErrorCode());
-
-  // Create an InputModule for each module in the InputFile, and add it to the
-  // ModuleSymbolTable.
-  for (auto BM : *BMsOrErr) {
-    Expected<std::unique_ptr<Module>> MOrErr =
-        BM.getLazyModule(File->Ctx, /*ShouldLazyLoadMetadata*/ true,
-                         /*IsImporting*/ false);
-    if (!MOrErr)
-      return MOrErr.takeError();
-
-    size_t SymBegin = File->SymTab.symbols().size();
-    File->SymTab.addModule(MOrErr->get());
-    size_t SymEnd = File->SymTab.symbols().size();
-
-    for (const auto &C : (*MOrErr)->getComdatSymbolTable()) {
-      auto P = File->ComdatMap.insert(
-          std::make_pair(&C.second, File->Comdats.size()));
-      assert(P.second);
-      (void)P;
-      File->Comdats.push_back(C.first());
-    }
-
-    File->Mods.push_back({BM, std::move(*MOrErr), SymBegin, SymEnd});
+  Expected<IRSymtabFile> FOrErr = readIRSymtab(Object);
+  if (!FOrErr)
+    return FOrErr.takeError();
+
+  File->TargetTriple = FOrErr->TheReader.getTargetTriple();
+  File->SourceFileName = FOrErr->TheReader.getSourceFileName();
+  File->COFFLinkerOpts = FOrErr->TheReader.getCOFFLinkerOpts();
+  File->ComdatTable = FOrErr->TheReader.getComdatTable();
+
+  for (unsigned I = 0; I != FOrErr->Mods.size(); ++I) {
+    size_t Begin = File->Symbols.size();
+    for (const irsymtab::Reader::SymbolRef &Sym :
+         FOrErr->TheReader.module_symbols(I))
+      // Skip symbols that are irrelevant to LTO. Note that this condition needs
+      // to match the one in Skip() in LTO::addRegularLTO().
+      if (Sym.isGlobal() && !Sym.isFormatSpecific())
+        File->Symbols.push_back(Sym);
+    File->ModuleSymIndices.push_back({Begin, File->Symbols.size()});
   }
 
+  File->Mods = FOrErr->Mods;
+  File->Strtab = std::move(FOrErr->Strtab);
   return std::move(File);
 }
 
-Expected<int> InputFile::Symbol::getComdatIndex() const {
-  if (!isGV())
-    return -1;
-  const GlobalObject *GO = getGV()->getBaseObject();
-  if (!GO)
-    return make_error<StringError>("Unable to determine comdat of alias!",
-                                   inconvertibleErrorCode());
-  if (const Comdat *C = GO->getComdat()) {
-    auto I = File->ComdatMap.find(C);
-    assert(I != File->ComdatMap.end());
-    return I->second;
-  }
-  return -1;
-}
-
 StringRef InputFile::getName() const {
-  return Mods[0].BM.getModuleIdentifier();
-}
-
-StringRef InputFile::getSourceFileName() const {
-  return Mods[0].Mod->getSourceFileName();
-}
-
-iterator_range<InputFile::symbol_iterator>
-InputFile::module_symbols(InputModule &IM) {
-  return llvm::make_range(
-      symbol_iterator(SymTab.symbols().data() + IM.SymBegin, SymTab, this),
-      symbol_iterator(SymTab.symbols().data() + IM.SymEnd, SymTab, this));
+  return Mods[0].getModuleIdentifier();
 }
 
 LTO::RegularLTOState::RegularLTOState(unsigned ParallelCodeGenParallelismLevel,
@@ -325,33 +364,40 @@ LTO::LTO(Config Conf, ThinBackend Backend,
 // Requires a destructor for MapVector<BitcodeModule>.
 LTO::~LTO() = default;
 
-// Add the given symbol to the GlobalResolutions map, and resolve its partition.
-void LTO::addSymbolToGlobalRes(SmallPtrSet<GlobalValue *, 8> &Used,
-                               const InputFile::Symbol &Sym,
-                               SymbolResolution Res, unsigned Partition) {
-  GlobalValue *GV = Sym.isGV() ? Sym.getGV() : nullptr;
+// Add the symbols in the given module to the GlobalResolutions map, and resolve
+// their partitions.
+void LTO::addModuleToGlobalRes(ArrayRef<InputFile::Symbol> Syms,
+                               ArrayRef<SymbolResolution> Res,
+                               unsigned Partition, bool InSummary) {
+  auto *ResI = Res.begin();
+  auto *ResE = Res.end();
+  (void)ResE;
+  for (const InputFile::Symbol &Sym : Syms) {
+    assert(ResI != ResE);
+    SymbolResolution Res = *ResI++;
 
-  auto &GlobalRes = GlobalResolutions[Sym.getName()];
-  if (GV) {
-    GlobalRes.UnnamedAddr &= GV->hasGlobalUnnamedAddr();
+    auto &GlobalRes = GlobalResolutions[Sym.getName()];
+    GlobalRes.UnnamedAddr &= Sym.isUnnamedAddr();
     if (Res.Prevailing)
-      GlobalRes.IRName = GV->getName();
+      GlobalRes.IRName = Sym.getIRName();
+
+    // Set the partition to external if we know it is re-defined by the linker
+    // with -defsym or -wrap options, used elsewhere, e.g. it is visible to a
+    // regular object, is referenced from llvm.compiler_used, or was already
+    // recorded as being referenced from a different partition.
+    if (Res.LinkerRedefined || Res.VisibleToRegularObj || Sym.isUsed() ||
+        (GlobalRes.Partition != GlobalResolution::Unknown &&
+         GlobalRes.Partition != Partition)) {
+      GlobalRes.Partition = GlobalResolution::External;
+    } else
+      // First recorded reference, save the current partition.
+      GlobalRes.Partition = Partition;
+
+    // Flag as visible outside of summary if visible from a regular object or
+    // from a module that does not have a summary.
+    GlobalRes.VisibleOutsideSummary |=
+        (Res.VisibleToRegularObj || Sym.isUsed() || !InSummary);
   }
-  // Set the partition to external if we know it is used elsewhere, e.g.
-  // it is visible to a regular object, is referenced from llvm.compiler_used,
-  // or was already recorded as being referenced from a different partition.
-  if (Res.VisibleToRegularObj || (GV && Used.count(GV)) ||
-      (GlobalRes.Partition != GlobalResolution::Unknown &&
-       GlobalRes.Partition != Partition)) {
-    GlobalRes.Partition = GlobalResolution::External;
-  } else
-    // First recorded reference, save the current partition.
-    GlobalRes.Partition = Partition;
-
-  // Flag as visible outside of ThinLTO if visible from a regular object or
-  // if this is a reference in the regular LTO partition.
-  GlobalRes.VisibleOutsideThinLTO |=
-      (Res.VisibleToRegularObj || (Partition == GlobalResolution::RegularLTO));
 }
 
 static void writeToResolutionFile(raw_ostream &OS, InputFile *Input,
@@ -370,8 +416,11 @@ static void writeToResolutionFile(raw_ostream &OS, InputFile *Input,
       OS << 'l';
     if (Res.VisibleToRegularObj)
       OS << 'x';
+    if (Res.LinkerRedefined)
+      OS << 'r';
     OS << '\n';
   }
+  OS.flush();
   assert(ResI == Res.end());
 }
 
@@ -383,102 +432,174 @@ Error LTO::add(std::unique_ptr<InputFile> Input,
     writeToResolutionFile(*Conf.ResolutionFile, Input.get(), Res);
 
   const SymbolResolution *ResI = Res.begin();
-  for (InputFile::InputModule &IM : Input->Mods)
-    if (Error Err = addModule(*Input, IM, ResI, Res.end()))
+  for (unsigned I = 0; I != Input->Mods.size(); ++I)
+    if (Error Err = addModule(*Input, I, ResI, Res.end()))
       return Err;
 
   assert(ResI == Res.end());
   return Error::success();
 }
 
-Error LTO::addModule(InputFile &Input, InputFile::InputModule &IM,
+Error LTO::addModule(InputFile &Input, unsigned ModI,
                      const SymbolResolution *&ResI,
                      const SymbolResolution *ResE) {
-  // FIXME: move to backend
-  Module &M = *IM.Mod;
-
-  if (M.getDataLayoutStr().empty())
-    return make_error<StringError>("input module has no datalayout",
-                                    inconvertibleErrorCode());
-
-  if (!Conf.OverrideTriple.empty())
-    M.setTargetTriple(Conf.OverrideTriple);
-  else if (M.getTargetTriple().empty())
-    M.setTargetTriple(Conf.DefaultTriple);
-
-  Expected<bool> HasThinLTOSummary = IM.BM.hasSummary();
-  if (!HasThinLTOSummary)
-    return HasThinLTOSummary.takeError();
+  Expected<BitcodeLTOInfo> LTOInfo = Input.Mods[ModI].getLTOInfo();
+  if (!LTOInfo)
+    return LTOInfo.takeError();
+
+  BitcodeModule BM = Input.Mods[ModI];
+  auto ModSyms = Input.module_symbols(ModI);
+  addModuleToGlobalRes(ModSyms, {ResI, ResE},
+                       LTOInfo->IsThinLTO ? ThinLTO.ModuleMap.size() + 1 : 0,
+                       LTOInfo->HasSummary);
+
+  if (LTOInfo->IsThinLTO)
+    return addThinLTO(BM, ModSyms, ResI, ResE);
+
+  Expected<RegularLTOState::AddedModule> ModOrErr =
+      addRegularLTO(BM, ModSyms, ResI, ResE);
+  if (!ModOrErr)
+    return ModOrErr.takeError();
+
+  if (!LTOInfo->HasSummary)
+    return linkRegularLTO(std::move(*ModOrErr), /*LivenessFromIndex=*/false);
+
+  // Regular LTO module summaries are added to a dummy module that represents
+  // the combined regular LTO module.
+  if (Error Err = BM.readSummary(ThinLTO.CombinedIndex, "", -1ull))
+    return Err;
+  RegularLTO.ModsWithSummaries.push_back(std::move(*ModOrErr));
+  return Error::success();
+}
 
-  if (*HasThinLTOSummary)
-    return addThinLTO(IM.BM, M, Input.module_symbols(IM), ResI, ResE);
-  else
-    return addRegularLTO(IM.BM, ResI, ResE);
+// Checks whether the given global value is in a non-prevailing comdat
+// (comdat containing values the linker indicated were not prevailing,
+// which we then dropped to available_externally), and if so, removes
+// it from the comdat. This is called for all global values to ensure the
+// comdat is empty rather than leaving an incomplete comdat. It is needed for
+// regular LTO modules, in case we are in a mixed-LTO mode (both regular
+// and thin LTO modules) compilation. Since the regular LTO module will be
+// linked first in the final native link, we want to make sure the linker
+// doesn't select any of these incomplete comdats that would be left
+// in the regular LTO module without this cleanup.
+static void
+handleNonPrevailingComdat(GlobalValue &GV,
+                          std::set<const Comdat *> &NonPrevailingComdats) {
+  Comdat *C = GV.getComdat();
+  if (!C)
+    return;
+
+  if (!NonPrevailingComdats.count(C))
+    return;
+
+  // Additionally need to drop externally visible global values from the comdat
+  // to available_externally, so that there aren't multiply defined linker
+  // errors.
+  if (!GV.hasLocalLinkage())
+    GV.setLinkage(GlobalValue::AvailableExternallyLinkage);
+
+  if (auto GO = dyn_cast<GlobalObject>(&GV))
+    GO->setComdat(nullptr);
 }
 
 // Add a regular LTO object to the link.
-Error LTO::addRegularLTO(BitcodeModule BM, const SymbolResolution *&ResI,
-                         const SymbolResolution *ResE) {
-  if (!RegularLTO.CombinedModule) {
-    RegularLTO.CombinedModule =
-        llvm::make_unique<Module>("ld-temp.o", RegularLTO.Ctx);
-    RegularLTO.Mover = llvm::make_unique<IRMover>(*RegularLTO.CombinedModule);
-  }
+// The resulting module needs to be linked into the combined LTO module with
+// linkRegularLTO.
+Expected<LTO::RegularLTOState::AddedModule>
+LTO::addRegularLTO(BitcodeModule BM, ArrayRef<InputFile::Symbol> Syms,
+                   const SymbolResolution *&ResI,
+                   const SymbolResolution *ResE) {
+  RegularLTOState::AddedModule Mod;
   Expected<std::unique_ptr<Module>> MOrErr =
       BM.getLazyModule(RegularLTO.Ctx, /*ShouldLazyLoadMetadata*/ true,
                        /*IsImporting*/ false);
   if (!MOrErr)
     return MOrErr.takeError();
-
   Module &M = **MOrErr;
+  Mod.M = std::move(*MOrErr);
+
   if (Error Err = M.materializeMetadata())
-    return Err;
+    return std::move(Err);
   UpgradeDebugInfo(M);
 
   ModuleSymbolTable SymTab;
   SymTab.addModule(&M);
 
-  SmallPtrSet<GlobalValue *, 8> Used;
-  collectUsedGlobalVariables(M, Used, /*CompilerUsed*/ false);
-
-  std::vector<GlobalValue *> Keep;
-
   for (GlobalVariable &GV : M.globals())
     if (GV.hasAppendingLinkage())
-      Keep.push_back(&GV);
+      Mod.Keep.push_back(&GV);
+
+  DenseSet<GlobalObject *> AliasedGlobals;
+  for (auto &GA : M.aliases())
+    if (GlobalObject *GO = GA.getBaseObject())
+      AliasedGlobals.insert(GO);
+
+  // In this function we need IR GlobalValues matching the symbols in Syms
+  // (which is not backed by a module), so we need to enumerate them in the same
+  // order. The symbol enumeration order of a ModuleSymbolTable intentionally
+  // matches the order of an irsymtab, but when we read the irsymtab in
+  // InputFile::create we omit some symbols that are irrelevant to LTO. The
+  // Skip() function skips the same symbols from the module as InputFile does
+  // from the symbol table.
+  auto MsymI = SymTab.symbols().begin(), MsymE = SymTab.symbols().end();
+  auto Skip = [&]() {
+    while (MsymI != MsymE) {
+      auto Flags = SymTab.getSymbolFlags(*MsymI);
+      if ((Flags & object::BasicSymbolRef::SF_Global) &&
+          !(Flags & object::BasicSymbolRef::SF_FormatSpecific))
+        return;
+      ++MsymI;
+    }
+  };
+  Skip();
 
-  for (const InputFile::Symbol &Sym :
-       make_range(InputFile::symbol_iterator(SymTab.symbols().begin(), SymTab,
-                                             nullptr),
-                  InputFile::symbol_iterator(SymTab.symbols().end(), SymTab,
-                                             nullptr))) {
+  std::set<const Comdat *> NonPrevailingComdats;
+  for (const InputFile::Symbol &Sym : Syms) {
     assert(ResI != ResE);
     SymbolResolution Res = *ResI++;
-    addSymbolToGlobalRes(Used, Sym, Res, 0);
 
-    if (Sym.getFlags() & object::BasicSymbolRef::SF_Undefined)
-      continue;
-    if (Res.Prevailing && Sym.isGV()) {
-      GlobalValue *GV = Sym.getGV();
-      Keep.push_back(GV);
-      switch (GV->getLinkage()) {
-      default:
-        break;
-      case GlobalValue::LinkOnceAnyLinkage:
-        GV->setLinkage(GlobalValue::WeakAnyLinkage);
-        break;
-      case GlobalValue::LinkOnceODRLinkage:
-        GV->setLinkage(GlobalValue::WeakODRLinkage);
-        break;
+    assert(MsymI != MsymE);
+    ModuleSymbolTable::Symbol Msym = *MsymI++;
+    Skip();
+
+    if (GlobalValue *GV = Msym.dyn_cast<GlobalValue *>()) {
+      if (Res.Prevailing) {
+        if (Sym.isUndefined())
+          continue;
+        Mod.Keep.push_back(GV);
+        // For symbols re-defined with linker -wrap and -defsym options,
+        // set the linkage to weak to inhibit IPO. The linkage will be
+        // restored by the linker.
+        if (Res.LinkerRedefined)
+          GV->setLinkage(GlobalValue::WeakAnyLinkage);
+
+        GlobalValue::LinkageTypes OriginalLinkage = GV->getLinkage();
+        if (GlobalValue::isLinkOnceLinkage(OriginalLinkage))
+          GV->setLinkage(GlobalValue::getWeakLinkage(
+              GlobalValue::isLinkOnceODRLinkage(OriginalLinkage)));
+      } else if (isa<GlobalObject>(GV) &&
+                 (GV->hasLinkOnceODRLinkage() || GV->hasWeakODRLinkage() ||
+                  GV->hasAvailableExternallyLinkage()) &&
+                 !AliasedGlobals.count(cast<GlobalObject>(GV))) {
+        // Any of the above three types of linkage indicates that the
+        // chosen prevailing symbol will have the same semantics as this copy of
+        // the symbol, so we may be able to link it with available_externally
+        // linkage. We will decide later whether to do that when we link this
+        // module (in linkRegularLTO), based on whether it is undefined.
+        Mod.Keep.push_back(GV);
+        GV->setLinkage(GlobalValue::AvailableExternallyLinkage);
+        if (GV->hasComdat())
+          NonPrevailingComdats.insert(GV->getComdat());
+        cast<GlobalObject>(GV)->setComdat(nullptr);
       }
     }
     // Common resolution: collect the maximum size/alignment over all commons.
     // We also record if we see an instance of a common as prevailing, so that
     // if none is prevailing we can ignore it later.
-    if (Sym.getFlags() & object::BasicSymbolRef::SF_Common) {
+    if (Sym.isCommon()) {
       // FIXME: We should figure out what to do about commons defined by asm.
       // For now they aren't reported correctly by ModuleSymbolTable.
-      auto &CommonRes = RegularLTO.Commons[Sym.getGV()->getName()];
+      auto &CommonRes = RegularLTO.Commons[Sym.getIRName()];
       CommonRes.Size = std::max(CommonRes.Size, Sym.getCommonSize());
       CommonRes.Align = std::max(CommonRes.Align, Sym.getCommonAlignment());
       CommonRes.Prevailing |= Res.Prevailing;
@@ -486,37 +607,75 @@ Error LTO::addRegularLTO(BitcodeModule BM, const SymbolResolution *&ResI,
 
     // FIXME: use proposed local attribute for FinalDefinitionInLinkageUnit.
   }
+  if (!M.getComdatSymbolTable().empty())
+    for (GlobalValue &GV : M.global_values())
+      handleNonPrevailingComdat(GV, NonPrevailingComdats);
+  assert(MsymI == MsymE);
+  return std::move(Mod);
+}
+
+Error LTO::linkRegularLTO(RegularLTOState::AddedModule Mod,
+                          bool LivenessFromIndex) {
+  if (!RegularLTO.CombinedModule) {
+    RegularLTO.CombinedModule =
+        llvm::make_unique<Module>("ld-temp.o", RegularLTO.Ctx);
+    RegularLTO.Mover = llvm::make_unique<IRMover>(*RegularLTO.CombinedModule);
+  }
+
+  std::vector<GlobalValue *> Keep;
+  for (GlobalValue *GV : Mod.Keep) {
+    if (LivenessFromIndex && !ThinLTO.CombinedIndex.isGUIDLive(GV->getGUID()))
+      continue;
 
-  return RegularLTO.Mover->move(std::move(*MOrErr), Keep,
+    if (!GV->hasAvailableExternallyLinkage()) {
+      Keep.push_back(GV);
+      continue;
+    }
+
+    // Only link available_externally definitions if we don't already have a
+    // definition.
+    GlobalValue *CombinedGV =
+        RegularLTO.CombinedModule->getNamedValue(GV->getName());
+    if (CombinedGV && !CombinedGV->isDeclaration())
+      continue;
+
+    Keep.push_back(GV);
+  }
+
+  return RegularLTO.Mover->move(std::move(Mod.M), Keep,
                                 [](GlobalValue &, IRMover::ValueAdder) {},
-                                /* LinkModuleInlineAsm */ true,
                                 /* IsPerformingImport */ false);
 }
 
-// Add a ThinLTO object to the link.
-// FIXME: This function should not need to take as many parameters once we have
-// a bitcode symbol table.
-Error LTO::addThinLTO(BitcodeModule BM, Module &M,
-                      iterator_range<InputFile::symbol_iterator> Syms,
+// Add a ThinLTO module to the link.
+Error LTO::addThinLTO(BitcodeModule BM, ArrayRef<InputFile::Symbol> Syms,
                       const SymbolResolution *&ResI,
                       const SymbolResolution *ResE) {
-  SmallPtrSet<GlobalValue *, 8> Used;
-  collectUsedGlobalVariables(M, Used, /*CompilerUsed*/ false);
-
-  Expected<std::unique_ptr<ModuleSummaryIndex>> SummaryOrErr = BM.getSummary();
-  if (!SummaryOrErr)
-    return SummaryOrErr.takeError();
-  ThinLTO.CombinedIndex.mergeFrom(std::move(*SummaryOrErr),
-                                  ThinLTO.ModuleMap.size());
+  if (Error Err =
+          BM.readSummary(ThinLTO.CombinedIndex, BM.getModuleIdentifier(),
+                         ThinLTO.ModuleMap.size()))
+    return Err;
 
   for (const InputFile::Symbol &Sym : Syms) {
     assert(ResI != ResE);
     SymbolResolution Res = *ResI++;
-    addSymbolToGlobalRes(Used, Sym, Res, ThinLTO.ModuleMap.size() + 1);
 
-    if (Res.Prevailing && Sym.isGV())
-      ThinLTO.PrevailingModuleForGUID[Sym.getGV()->getGUID()] =
-          BM.getModuleIdentifier();
+    if (Res.Prevailing) {
+      if (!Sym.getIRName().empty()) {
+        auto GUID = GlobalValue::getGUID(GlobalValue::getGlobalIdentifier(
+            Sym.getIRName(), GlobalValue::ExternalLinkage, ""));
+        ThinLTO.PrevailingModuleForGUID[GUID] = BM.getModuleIdentifier();
+
+        // For linker redefined symbols (via --wrap or --defsym) we want to
+        // switch the linkage to `weak` to prevent IPOs from happening.
+        // Find the summary in the module for this very GV and record the new
+        // linkage so that we can switch it when we import the GV.
+        if (Res.LinkerRedefined)
+          if (auto S = ThinLTO.CombinedIndex.findSummaryInModule(
+                  GUID, BM.getModuleIdentifier()))
+            S->setLinkage(GlobalValue::WeakAnyLinkage);
+      }
+    }
   }
 
   if (!ThinLTO.ModuleMap.insert({BM.getModuleIdentifier(), BM}).second)
@@ -533,10 +692,24 @@ unsigned LTO::getMaxTasks() const {
 }
 
 Error LTO::run(AddStreamFn AddStream, NativeObjectCache Cache) {
+  // Compute "dead" symbols, we don't want to import/export these!
+  DenseSet<GlobalValue::GUID> GUIDPreservedSymbols;
+  for (auto &Res : GlobalResolutions) {
+    if (Res.second.VisibleOutsideSummary &&
+        // IRName will be defined if we have seen the prevailing copy of
+        // this value. If not, no need to preserve any ThinLTO copies.
+        !Res.second.IRName.empty())
+      GUIDPreservedSymbols.insert(GlobalValue::getGUID(
+          GlobalValue::dropLLVMManglingEscape(Res.second.IRName)));
+  }
+
+  computeDeadSymbols(ThinLTO.CombinedIndex, GUIDPreservedSymbols);
+
   // Save the status of having a regularLTO combined module, as
   // this is needed for generating the ThinLTO Task ID, and
   // the CombinedModule will be moved at the end of runRegularLTO.
-  bool HasRegularLTO = RegularLTO.CombinedModule != nullptr;
+  bool HasRegularLTO = RegularLTO.CombinedModule != nullptr ||
+                       !RegularLTO.ModsWithSummaries.empty();
   // Invoke regular LTO if there was a regular LTO module to start with.
   if (HasRegularLTO)
     if (auto E = runRegularLTO(AddStream))
@@ -545,6 +718,11 @@ Error LTO::run(AddStreamFn AddStream, NativeObjectCache Cache) {
 }
 
 Error LTO::runRegularLTO(AddStreamFn AddStream) {
+  for (auto &M : RegularLTO.ModsWithSummaries)
+    if (Error Err = linkRegularLTO(std::move(M),
+                                   /*LivenessFromIndex=*/true))
+      return Err;
+
   // Make sure commons have the right size/alignment: we kept the largest from
   // all the prevailing when adding the inputs, and we apply it here.
   const DataLayout &DL = RegularLTO.CombinedModule->getDataLayout();
@@ -602,7 +780,7 @@ Error LTO::runRegularLTO(AddStreamFn AddStream) {
       return Error::success();
   }
   return backend(Conf, AddStream, RegularLTO.ParallelCodeGenParallelismLevel,
-                 std::move(RegularLTO.CombinedModule));
+                 std::move(RegularLTO.CombinedModule), ThinLTO.CombinedIndex);
 }
 
 /// This class defines the interface to the ThinLTO backend.
@@ -633,6 +811,7 @@ class InProcessThinBackend : public ThinBackendProc {
   ThreadPool BackendThreadPool;
   AddStreamFn AddStream;
   NativeObjectCache Cache;
+  TypeIdSummariesByGuidTy TypeIdSummariesByGuid;
 
   Optional<Error> Err;
   std::mutex ErrMu;
@@ -645,7 +824,14 @@ public:
       AddStreamFn AddStream, NativeObjectCache Cache)
       : ThinBackendProc(Conf, CombinedIndex, ModuleToDefinedGVSummaries),
         BackendThreadPool(ThinLTOParallelismLevel),
-        AddStream(std::move(AddStream)), Cache(std::move(Cache)) {}
+        AddStream(std::move(AddStream)), Cache(std::move(Cache)) {
+    // Create a mapping from type identifier GUIDs to type identifier summaries.
+    // This allows backends to use the type identifier GUIDs stored in the
+    // function summaries to determine which type identifier summaries affect
+    // each function without needing to compute GUIDs in each backend.
+    for (auto &TId : CombinedIndex.typeIds())
+      TypeIdSummariesByGuid[GlobalValue::getGUID(TId.first)].push_back(&TId);
+  }
 
   Error runThinLTOBackendThread(
       AddStreamFn AddStream, NativeObjectCache Cache, unsigned Task,
@@ -654,7 +840,8 @@ public:
       const FunctionImporter::ExportSetTy &ExportList,
       const std::map<GlobalValue::GUID, GlobalValue::LinkageTypes> &ResolvedODR,
       const GVSummaryMapTy &DefinedGlobals,
-      MapVector<StringRef, BitcodeModule> &ModuleMap) {
+      MapVector<StringRef, BitcodeModule> &ModuleMap,
+      const TypeIdSummariesByGuidTy &TypeIdSummariesByGuid) {
     auto RunThinBackend = [&](AddStreamFn AddStream) {
       LTOLLVMContext BackendContext(Conf);
       Expected<std::unique_ptr<Module>> MOrErr = BM.parseModule(BackendContext);
@@ -677,7 +864,7 @@ public:
     SmallString<40> Key;
     // The module may be cached, this helps handling it.
     computeCacheKey(Key, Conf, CombinedIndex, ModuleID, ImportList, ExportList,
-                    ResolvedODR, DefinedGlobals);
+                    ResolvedODR, DefinedGlobals, TypeIdSummariesByGuid);
     if (AddStreamFn CacheAddStream = Cache(Task, Key))
       return RunThinBackend(CacheAddStream);
 
@@ -701,10 +888,11 @@ public:
             const std::map<GlobalValue::GUID, GlobalValue::LinkageTypes>
                 &ResolvedODR,
             const GVSummaryMapTy &DefinedGlobals,
-            MapVector<StringRef, BitcodeModule> &ModuleMap) {
+            MapVector<StringRef, BitcodeModule> &ModuleMap,
+            const TypeIdSummariesByGuidTy &TypeIdSummariesByGuid) {
           Error E = runThinLTOBackendThread(
-              AddStream, Cache, Task, BM, CombinedIndex, ImportList,
-              ExportList, ResolvedODR, DefinedGlobals, ModuleMap);
+              AddStream, Cache, Task, BM, CombinedIndex, ImportList, ExportList,
+              ResolvedODR, DefinedGlobals, ModuleMap, TypeIdSummariesByGuid);
           if (E) {
             std::unique_lock<std::mutex> L(ErrMu);
             if (Err)
@@ -713,9 +901,9 @@ public:
               Err = std::move(E);
           }
         },
-        BM, std::ref(CombinedIndex), std::ref(ImportList),
-        std::ref(ExportList), std::ref(ResolvedODR), std::ref(DefinedGlobals),
-        std::ref(ModuleMap));
+        BM, std::ref(CombinedIndex), std::ref(ImportList), std::ref(ExportList),
+        std::ref(ResolvedODR), std::ref(DefinedGlobals), std::ref(ModuleMap),
+        std::ref(TypeIdSummariesByGuid));
     return Error::success();
   }
 
@@ -842,7 +1030,7 @@ Error LTO::runThinLTO(AddStreamFn AddStream, NativeObjectCache Cache,
 
   // Collect for each module the list of function it defines (GUID ->
   // Summary).
-  StringMap<std::map<GlobalValue::GUID, GlobalValueSummary *>>
+  StringMap<GVSummaryMapTy>
       ModuleToDefinedGVSummaries(ThinLTO.ModuleMap.size());
   ThinLTO.CombinedIndex.collectDefinedGVSummariesPerModule(
       ModuleToDefinedGVSummaries);
@@ -857,19 +1045,6 @@ Error LTO::runThinLTO(AddStreamFn AddStream, NativeObjectCache Cache,
     if (!ModuleToDefinedGVSummaries.count(Mod.first))
       ModuleToDefinedGVSummaries.try_emplace(Mod.first);
 
-  // Compute "dead" symbols, we don't want to import/export these!
-  DenseSet<GlobalValue::GUID> GUIDPreservedSymbols;
-  for (auto &Res : GlobalResolutions) {
-    if (Res.second.VisibleOutsideThinLTO &&
-        // IRName will be defined if we have seen the prevailing copy of
-        // this value. If not, no need to preserve any ThinLTO copies.
-        !Res.second.IRName.empty())
-      GUIDPreservedSymbols.insert(GlobalValue::getGUID(Res.second.IRName));
-  }
-
-  auto DeadSymbols =
-      computeDeadSymbols(ThinLTO.CombinedIndex, GUIDPreservedSymbols);
-
   StringMap<FunctionImporter::ImportMapTy> ImportLists(
       ThinLTO.ModuleMap.size());
   StringMap<FunctionImporter::ExportSetTy> ExportLists(
@@ -878,7 +1053,7 @@ Error LTO::runThinLTO(AddStreamFn AddStream, NativeObjectCache Cache,
 
   if (Conf.OptLevel > 0) {
     ComputeCrossModuleImport(ThinLTO.CombinedIndex, ModuleToDefinedGVSummaries,
-                             ImportLists, ExportLists, &DeadSymbols);
+                             ImportLists, ExportLists);
 
     std::set<GlobalValue::GUID> ExportedGUIDs;
     for (auto &Res : GlobalResolutions) {
@@ -890,16 +1065,13 @@ Error LTO::runThinLTO(AddStreamFn AddStream, NativeObjectCache Cache,
       // partition (and we can't get the GUID).
       if (Res.second.IRName.empty())
         continue;
-      auto GUID = GlobalValue::getGUID(Res.second.IRName);
+      auto GUID = GlobalValue::getGUID(
+          GlobalValue::dropLLVMManglingEscape(Res.second.IRName));
       // Mark exported unless index-based analysis determined it to be dead.
-      if (!DeadSymbols.count(GUID))
-        ExportedGUIDs.insert(GlobalValue::getGUID(Res.second.IRName));
+      if (ThinLTO.CombinedIndex.isGUIDLive(GUID))
+        ExportedGUIDs.insert(GUID);
     }
 
-    auto isPrevailing = [&](GlobalValue::GUID GUID,
-                            const GlobalValueSummary *S) {
-      return ThinLTO.PrevailingModuleForGUID[GUID] == S->modulePath();
-    };
     auto isExported = [&](StringRef ModuleIdentifier, GlobalValue::GUID GUID) {
       const auto &ExportList = ExportLists.find(ModuleIdentifier);
       return (ExportList != ExportLists.end() &&
@@ -907,17 +1079,20 @@ Error LTO::runThinLTO(AddStreamFn AddStream, NativeObjectCache Cache,
              ExportedGUIDs.count(GUID);
     };
     thinLTOInternalizeAndPromoteInIndex(ThinLTO.CombinedIndex, isExported);
-
-    auto recordNewLinkage = [&](StringRef ModuleIdentifier,
-                                GlobalValue::GUID GUID,
-                                GlobalValue::LinkageTypes NewLinkage) {
-      ResolvedODR[ModuleIdentifier][GUID] = NewLinkage;
-    };
-
-    thinLTOResolveWeakForLinkerInIndex(ThinLTO.CombinedIndex, isPrevailing,
-                                       recordNewLinkage);
   }
 
+  auto isPrevailing = [&](GlobalValue::GUID GUID,
+                          const GlobalValueSummary *S) {
+    return ThinLTO.PrevailingModuleForGUID[GUID] == S->modulePath();
+  };
+  auto recordNewLinkage = [&](StringRef ModuleIdentifier,
+                              GlobalValue::GUID GUID,
+                              GlobalValue::LinkageTypes NewLinkage) {
+    ResolvedODR[ModuleIdentifier][GUID] = NewLinkage;
+  };
+  thinLTOResolveWeakForLinkerInIndex(ThinLTO.CombinedIndex, isPrevailing,
+                                     recordNewLinkage);
+
   std::unique_ptr<ThinBackendProc> BackendProc =
       ThinLTO.Backend(Conf, ThinLTO.CombinedIndex, ModuleToDefinedGVSummaries,
                       AddStream, Cache);
@@ -937,3 +1112,27 @@ Error LTO::runThinLTO(AddStreamFn AddStream, NativeObjectCache Cache,
 
   return BackendProc->wait();
 }
+
+Expected<std::unique_ptr<tool_output_file>>
+lto::setupOptimizationRemarks(LLVMContext &Context,
+                              StringRef LTORemarksFilename,
+                              bool LTOPassRemarksWithHotness, int Count) {
+  if (LTORemarksFilename.empty())
+    return nullptr;
+
+  std::string Filename = LTORemarksFilename;
+  if (Count != -1)
+    Filename += ".thin." + llvm::utostr(Count) + ".yaml";
+
+  std::error_code EC;
+  auto DiagnosticFile =
+      llvm::make_unique<tool_output_file>(Filename, EC, sys::fs::F_None);
+  if (EC)
+    return errorCodeToError(EC);
+  Context.setDiagnosticsOutputFile(
+      llvm::make_unique<yaml::Output>(DiagnosticFile->os()));
+  if (LTOPassRemarksWithHotness)
+    Context.setDiagnosticsHotnessRequested(true);
+  DiagnosticFile->keep();
+  return std::move(DiagnosticFile);
+}
diff --git a/contrib/llvm/lib/LTO/LTOBackend.cpp b/contrib/llvm/lib/LTO/LTOBackend.cpp
index 809db80..3f72e44 100644
--- a/contrib/llvm/lib/LTO/LTOBackend.cpp
+++ b/contrib/llvm/lib/LTO/LTOBackend.cpp
@@ -25,8 +25,8 @@
 #include "llvm/IR/PassManager.h"
 #include "llvm/IR/Verifier.h"
 #include "llvm/LTO/LTO.h"
-#include "llvm/LTO/legacy/UpdateCompilerUsed.h"
 #include "llvm/MC/SubtargetFeature.h"
+#include "llvm/Object/ModuleSymbolTable.h"
 #include "llvm/Passes/PassBuilder.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/FileSystem.h"
@@ -112,18 +112,79 @@ Error Config::addSaveTemps(std::string OutputFileName,
 namespace {
 
 std::unique_ptr<TargetMachine>
-createTargetMachine(Config &Conf, StringRef TheTriple,
-                    const Target *TheTarget) {
+createTargetMachine(Config &Conf, const Target *TheTarget, Module &M) {
+  StringRef TheTriple = M.getTargetTriple();
   SubtargetFeatures Features;
   Features.getDefaultSubtargetFeatures(Triple(TheTriple));
   for (const std::string &A : Conf.MAttrs)
     Features.AddFeature(A);
 
+  Reloc::Model RelocModel;
+  if (Conf.RelocModel)
+    RelocModel = *Conf.RelocModel;
+  else
+    RelocModel =
+        M.getPICLevel() == PICLevel::NotPIC ? Reloc::Static : Reloc::PIC_;
+
   return std::unique_ptr<TargetMachine>(TheTarget->createTargetMachine(
-      TheTriple, Conf.CPU, Features.getString(), Conf.Options, Conf.RelocModel,
+      TheTriple, Conf.CPU, Features.getString(), Conf.Options, RelocModel,
       Conf.CodeModel, Conf.CGOptLevel));
 }
 
+static void runNewPMPasses(Module &Mod, TargetMachine *TM, unsigned OptLevel,
+                           bool IsThinLTO) {
+  PassBuilder PB(TM);
+  AAManager AA;
+
+  // Parse a custom AA pipeline if asked to.
+  assert(PB.parseAAPipeline(AA, "default"));
+
+  LoopAnalysisManager LAM;
+  FunctionAnalysisManager FAM;
+  CGSCCAnalysisManager CGAM;
+  ModuleAnalysisManager MAM;
+
+  // Register the AA manager first so that our version is the one used.
+  FAM.registerPass([&] { return std::move(AA); });
+
+  // Register all the basic analyses with the managers.
+  PB.registerModuleAnalyses(MAM);
+  PB.registerCGSCCAnalyses(CGAM);
+  PB.registerFunctionAnalyses(FAM);
+  PB.registerLoopAnalyses(LAM);
+  PB.crossRegisterProxies(LAM, FAM, CGAM, MAM);
+
+  ModulePassManager MPM;
+  // FIXME (davide): verify the input.
+
+  PassBuilder::OptimizationLevel OL;
+
+  switch (OptLevel) {
+  default:
+    llvm_unreachable("Invalid optimization level");
+  case 0:
+    OL = PassBuilder::O0;
+    break;
+  case 1:
+    OL = PassBuilder::O1;
+    break;
+  case 2:
+    OL = PassBuilder::O2;
+    break;
+  case 3:
+    OL = PassBuilder::O3;
+    break;
+  }
+
+  if (IsThinLTO)
+    MPM = PB.buildThinLTODefaultPipeline(OL, false /* DebugLogging */);
+  else
+    MPM = PB.buildLTODefaultPipeline(OL, false /* DebugLogging */);
+  MPM.run(Mod, MAM);
+
+  // FIXME (davide): verify the output.
+}
+
 static void runNewPMCustomPasses(Module &Mod, TargetMachine *TM,
                                  std::string PipelineDesc,
                                  std::string AAPipelineDesc,
@@ -168,13 +229,16 @@ static void runNewPMCustomPasses(Module &Mod, TargetMachine *TM,
 }
 
 static void runOldPMPasses(Config &Conf, Module &Mod, TargetMachine *TM,
-                           bool IsThinLTO) {
+                           bool IsThinLTO, ModuleSummaryIndex *ExportSummary,
+                           const ModuleSummaryIndex *ImportSummary) {
   legacy::PassManager passes;
   passes.add(createTargetTransformInfoWrapperPass(TM->getTargetIRAnalysis()));
 
   PassManagerBuilder PMB;
   PMB.LibraryInfo = new TargetLibraryInfoImpl(Triple(TM->getTargetTriple()));
   PMB.Inliner = createFunctionInliningPass();
+  PMB.ExportSummary = ExportSummary;
+  PMB.ImportSummary = ImportSummary;
   // Unconditionally verify input since it is not verified before this
   // point and has unknown origin.
   PMB.VerifyInput = true;
@@ -191,12 +255,16 @@ static void runOldPMPasses(Config &Conf, Module &Mod, TargetMachine *TM,
 }
 
 bool opt(Config &Conf, TargetMachine *TM, unsigned Task, Module &Mod,
-         bool IsThinLTO) {
-  if (Conf.OptPipeline.empty())
-    runOldPMPasses(Conf, Mod, TM, IsThinLTO);
-  else
+         bool IsThinLTO, ModuleSummaryIndex *ExportSummary,
+         const ModuleSummaryIndex *ImportSummary) {
+  // FIXME: Plumb the combined index into the new pass manager.
+  if (!Conf.OptPipeline.empty())
     runNewPMCustomPasses(Mod, TM, Conf.OptPipeline, Conf.AAPipeline,
                          Conf.DisableVerify);
+  else if (Conf.UseNewPM)
+    runNewPMPasses(Mod, TM, Conf.OptLevel, IsThinLTO);
+  else
+    runOldPMPasses(Conf, Mod, TM, IsThinLTO, ExportSummary, ImportSummary);
   return !Conf.PostOptModuleHook || Conf.PostOptModuleHook(Task, Mod);
 }
 
@@ -207,8 +275,7 @@ void codegen(Config &Conf, TargetMachine *TM, AddStreamFn AddStream,
 
   auto Stream = AddStream(Task);
   legacy::PassManager CodeGenPasses;
-  if (TM->addPassesToEmitFile(CodeGenPasses, *Stream->OS,
-                              TargetMachine::CGFT_ObjectFile))
+  if (TM->addPassesToEmitFile(CodeGenPasses, *Stream->OS, Conf.CGFileType))
     report_fatal_error("Failed to setup codegen");
   CodeGenPasses.run(Mod);
 }
@@ -245,7 +312,7 @@ void splitCodeGen(Config &C, TargetMachine *TM, AddStreamFn AddStream,
               std::unique_ptr<Module> MPartInCtx = std::move(MOrErr.get());
 
               std::unique_ptr<TargetMachine> TM =
-                  createTargetMachine(C, MPartInCtx->getTargetTriple(), T);
+                  createTargetMachine(C, T, *MPartInCtx);
 
               codegen(C, TM.get(), AddStream, ThreadId, *MPartInCtx);
             },
@@ -276,34 +343,40 @@ Expected<const Target *> initAndLookupTarget(Config &C, Module &Mod) {
 
 }
 
-static void handleAsmUndefinedRefs(Module &Mod, TargetMachine &TM) {
-  // Collect the list of undefined symbols used in asm and update
-  // llvm.compiler.used to prevent optimization to drop these from the output.
-  StringSet<> AsmUndefinedRefs;
-  ModuleSymbolTable::CollectAsmSymbols(
-      Triple(Mod.getTargetTriple()), Mod.getModuleInlineAsm(),
-      [&AsmUndefinedRefs](StringRef Name, object::BasicSymbolRef::Flags Flags) {
-        if (Flags & object::BasicSymbolRef::SF_Undefined)
-          AsmUndefinedRefs.insert(Name);
-      });
-  updateCompilerUsed(Mod, TM, AsmUndefinedRefs);
+static void
+finalizeOptimizationRemarks(std::unique_ptr<tool_output_file> DiagOutputFile) {
+  // Make sure we flush the diagnostic remarks file in case the linker doesn't
+  // call the global destructors before exiting.
+  if (!DiagOutputFile)
+    return;
+  DiagOutputFile->keep();
+  DiagOutputFile->os().flush();
 }
 
 Error lto::backend(Config &C, AddStreamFn AddStream,
                    unsigned ParallelCodeGenParallelismLevel,
-                   std::unique_ptr<Module> Mod) {
+                   std::unique_ptr<Module> Mod,
+                   ModuleSummaryIndex &CombinedIndex) {
   Expected<const Target *> TOrErr = initAndLookupTarget(C, *Mod);
   if (!TOrErr)
     return TOrErr.takeError();
 
-  std::unique_ptr<TargetMachine> TM =
-      createTargetMachine(C, Mod->getTargetTriple(), *TOrErr);
+  std::unique_ptr<TargetMachine> TM = createTargetMachine(C, *TOrErr, *Mod);
 
-  handleAsmUndefinedRefs(*Mod, *TM);
+  // Setup optimization remarks.
+  auto DiagFileOrErr = lto::setupOptimizationRemarks(
+      Mod->getContext(), C.RemarksFilename, C.RemarksWithHotness);
+  if (!DiagFileOrErr)
+    return DiagFileOrErr.takeError();
+  auto DiagnosticOutputFile = std::move(*DiagFileOrErr);
 
-  if (!C.CodeGenOnly)
-    if (!opt(C, TM.get(), 0, *Mod, /*IsThinLTO=*/false))
+  if (!C.CodeGenOnly) {
+    if (!opt(C, TM.get(), 0, *Mod, /*IsThinLTO=*/false,
+             /*ExportSummary=*/&CombinedIndex, /*ImportSummary=*/nullptr)) {
+      finalizeOptimizationRemarks(std::move(DiagnosticOutputFile));
       return Error::success();
+    }
+  }
 
   if (ParallelCodeGenParallelismLevel == 1) {
     codegen(C, TM.get(), AddStream, 0, *Mod);
@@ -311,11 +384,12 @@ Error lto::backend(Config &C, AddStreamFn AddStream,
     splitCodeGen(C, TM.get(), AddStream, ParallelCodeGenParallelismLevel,
                  std::move(Mod));
   }
+  finalizeOptimizationRemarks(std::move(DiagnosticOutputFile));
   return Error::success();
 }
 
 Error lto::thinBackend(Config &Conf, unsigned Task, AddStreamFn AddStream,
-                       Module &Mod, ModuleSummaryIndex &CombinedIndex,
+                       Module &Mod, const ModuleSummaryIndex &CombinedIndex,
                        const FunctionImporter::ImportMapTy &ImportList,
                        const GVSummaryMapTy &DefinedGlobals,
                        MapVector<StringRef, BitcodeModule> &ModuleMap) {
@@ -323,10 +397,7 @@ Error lto::thinBackend(Config &Conf, unsigned Task, AddStreamFn AddStream,
   if (!TOrErr)
     return TOrErr.takeError();
 
-  std::unique_ptr<TargetMachine> TM =
-      createTargetMachine(Conf, Mod.getTargetTriple(), *TOrErr);
-
-  handleAsmUndefinedRefs(Mod, *TM);
+  std::unique_ptr<TargetMachine> TM = createTargetMachine(Conf, *TOrErr, Mod);
 
   if (Conf.CodeGenOnly) {
     codegen(Conf, TM.get(), AddStream, Task, Mod);
@@ -367,7 +438,8 @@ Error lto::thinBackend(Config &Conf, unsigned Task, AddStreamFn AddStream,
   if (Conf.PostImportModuleHook && !Conf.PostImportModuleHook(Task, Mod))
     return Error::success();
 
-  if (!opt(Conf, TM.get(), Task, Mod, /*IsThinLTO=*/true))
+  if (!opt(Conf, TM.get(), Task, Mod, /*IsThinLTO=*/true,
+           /*ExportSummary=*/nullptr, /*ImportSummary=*/&CombinedIndex))
     return Error::success();
 
   codegen(Conf, TM.get(), AddStream, Task, Mod);
diff --git a/contrib/llvm/lib/LTO/LTOCodeGenerator.cpp b/contrib/llvm/lib/LTO/LTOCodeGenerator.cpp
index 6af31e6..6a27556 100644
--- a/contrib/llvm/lib/LTO/LTOCodeGenerator.cpp
+++ b/contrib/llvm/lib/LTO/LTOCodeGenerator.cpp
@@ -35,6 +35,7 @@
 #include "llvm/IR/Module.h"
 #include "llvm/IR/Verifier.h"
 #include "llvm/InitializePasses.h"
+#include "llvm/LTO/LTO.h"
 #include "llvm/LTO/legacy/LTOModule.h"
 #include "llvm/LTO/legacy/UpdateCompilerUsed.h"
 #include "llvm/Linker/Linker.h"
@@ -140,6 +141,7 @@ void LTOCodeGenerator::initializeLTOPasses() {
   initializeMemCpyOptLegacyPassPass(R);
   initializeDCELegacyPassPass(R);
   initializeCFGSimplifyPassPass(R);
+  initializeLateCFGSimplifyPassPass(R);
 }
 
 void LTOCodeGenerator::setAsmUndefinedRefs(LTOModule *Mod) {
@@ -493,36 +495,14 @@ void LTOCodeGenerator::verifyMergedModuleOnce() {
     return;
   HasVerifiedInput = true;
 
-  if (LTOStripInvalidDebugInfo) {
-    bool BrokenDebugInfo = false;
-    if (verifyModule(*MergedModule, &dbgs(), &BrokenDebugInfo))
-      report_fatal_error("Broken module found, compilation aborted!");
-    if (BrokenDebugInfo) {
-      emitWarning("Invalid debug info found, debug info will be stripped");
-      StripDebugInfo(*MergedModule);
-    }
-  }
-  if (verifyModule(*MergedModule, &dbgs()))
+  bool BrokenDebugInfo = false;
+  if (verifyModule(*MergedModule, &dbgs(),
+                   LTOStripInvalidDebugInfo ? &BrokenDebugInfo : nullptr))
     report_fatal_error("Broken module found, compilation aborted!");
-}
-
-bool LTOCodeGenerator::setupOptimizationRemarks() {
-  if (LTORemarksFilename != "") {
-    std::error_code EC;
-    DiagnosticOutputFile = llvm::make_unique<tool_output_file>(
-        LTORemarksFilename, EC, sys::fs::F_None);
-    if (EC) {
-      emitError(EC.message());
-      return false;
-    }
-    Context.setDiagnosticsOutputFile(
-        llvm::make_unique<yaml::Output>(DiagnosticOutputFile->os()));
+  if (BrokenDebugInfo) {
+    emitWarning("Invalid debug info found, debug info will be stripped");
+    StripDebugInfo(*MergedModule);
   }
-
-  if (LTOPassRemarksWithHotness)
-    Context.setDiagnosticHotnessRequested(true);
-
-  return true;
 }
 
 void LTOCodeGenerator::finishOptimizationRemarks() {
@@ -540,8 +520,13 @@ bool LTOCodeGenerator::optimize(bool DisableVerify, bool DisableInline,
   if (!this->determineTarget())
     return false;
 
-  if (!setupOptimizationRemarks())
-    return false;
+  auto DiagFileOrErr = lto::setupOptimizationRemarks(
+      Context, LTORemarksFilename, LTOPassRemarksWithHotness);
+  if (!DiagFileOrErr) {
+    errs() << "Error: " << toString(DiagFileOrErr.takeError()) << "\n";
+    report_fatal_error("Can't get an output file for the remarks");
+  }
+  DiagnosticOutputFile = std::move(*DiagFileOrErr);
 
   // We always run the verifier once on the merged module, the `DisableVerify`
   // parameter only applies to subsequent verify.
@@ -567,6 +552,8 @@ bool LTOCodeGenerator::optimize(bool DisableVerify, bool DisableInline,
   if (!DisableInline)
     PMB.Inliner = createFunctionInliningPass();
   PMB.LibraryInfo = new TargetLibraryInfoImpl(TargetTriple);
+  if (Freestanding)
+    PMB.LibraryInfo->disableAllFunctions();
   PMB.OptLevel = OptLevel;
   PMB.VerifyInput = !DisableVerify;
   PMB.VerifyOutput = !DisableVerify;
@@ -610,6 +597,7 @@ bool LTOCodeGenerator::compileOptimized(ArrayRef<raw_pwrite_stream *> Out) {
   // If statistics were requested, print them out after codegen.
   if (llvm::AreStatisticsEnabled())
     llvm::PrintStatistics();
+  reportAndResetTimings();
 
   finishOptimizationRemarks();
 
diff --git a/contrib/llvm/lib/LTO/LTOModule.cpp b/contrib/llvm/lib/LTO/LTOModule.cpp
index 89aeb80..3cc8b7d 100644
--- a/contrib/llvm/lib/LTO/LTOModule.cpp
+++ b/contrib/llvm/lib/LTO/LTOModule.cpp
@@ -14,11 +14,12 @@
 
 #include "llvm/LTO/legacy/LTOModule.h"
 #include "llvm/ADT/Triple.h"
+#include "llvm/Analysis/ObjectUtils.h"
 #include "llvm/Bitcode/BitcodeReader.h"
-#include "llvm/CodeGen/Analysis.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DiagnosticPrinter.h"
 #include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Mangler.h"
 #include "llvm/IR/Metadata.h"
 #include "llvm/IR/Module.h"
 #include "llvm/MC/MCExpr.h"
@@ -76,14 +77,12 @@ bool LTOModule::isBitcodeFile(StringRef Path) {
 }
 
 bool LTOModule::isThinLTO() {
-  // Right now the detection is only based on the summary presence. We may want
-  // to add a dedicated flag at some point.
-  Expected<bool> Result = hasGlobalValueSummary(MBRef);
+  Expected<BitcodeLTOInfo> Result = getBitcodeLTOInfo(MBRef);
   if (!Result) {
     logAllUnhandledErrors(Result.takeError(), errs(), "");
     return false;
   }
-  return *Result;
+  return Result->IsThinLTO;
 }
 
 bool LTOModule::isBitcodeForTarget(MemoryBuffer *Buffer,
@@ -636,10 +635,10 @@ void LTOModule::parseMetadata() {
   raw_string_ostream OS(LinkerOpts);
 
   // Linker Options
-  if (Metadata *Val = getModule().getModuleFlag("Linker Options")) {
-    MDNode *LinkerOptions = cast<MDNode>(Val);
+  if (NamedMDNode *LinkerOptions =
+          getModule().getNamedMetadata("llvm.linker.options")) {
     for (unsigned i = 0, e = LinkerOptions->getNumOperands(); i != e; ++i) {
-      MDNode *MDOptions = cast<MDNode>(LinkerOptions->getOperand(i));
+      MDNode *MDOptions = LinkerOptions->getOperand(i);
       for (unsigned ii = 0, ie = MDOptions->getNumOperands(); ii != ie; ++ii) {
         MDString *MDOption = cast<MDString>(MDOptions->getOperand(ii));
         OS << " " << MDOption->getString();
@@ -647,11 +646,15 @@ void LTOModule::parseMetadata() {
     }
   }
 
-  // Globals
+  // Globals - we only need to do this for COFF.
+  const Triple TT(_target->getTargetTriple());
+  if (!TT.isOSBinFormatCOFF())
+    return;
+  Mangler M;
   for (const NameAndAttributes &Sym : _symbols) {
     if (!Sym.symbol)
       continue;
-    _target->getObjFileLowering()->emitLinkerFlagsForGlobal(OS, Sym.symbol);
+    emitLinkerFlagsForGlobalCOFF(OS, Sym.symbol, TT, M);
   }
 
   // Add other interesting metadata here.
diff --git a/contrib/llvm/lib/LTO/ThinLTOCodeGenerator.cpp b/contrib/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
index 40537e4..1efd481 100644
--- a/contrib/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
+++ b/contrib/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
@@ -14,10 +14,6 @@
 
 #include "llvm/LTO/legacy/ThinLTOCodeGenerator.h"
 
-#ifdef HAVE_LLVM_REVISION
-#include "LLVMLTORevision.h"
-#endif
-
 #include "llvm/ADT/Statistic.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Analysis/ModuleSummaryAnalysis.h"
@@ -28,16 +24,16 @@
 #include "llvm/Bitcode/BitcodeWriter.h"
 #include "llvm/Bitcode/BitcodeWriterPass.h"
 #include "llvm/ExecutionEngine/ObjectMemoryBuffer.h"
+#include "llvm/IR/DebugInfo.h"
 #include "llvm/IR/DiagnosticPrinter.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/LegacyPassManager.h"
 #include "llvm/IR/Mangler.h"
+#include "llvm/IR/Verifier.h"
 #include "llvm/IRReader/IRReader.h"
 #include "llvm/LTO/LTO.h"
-#include "llvm/Linker/Linker.h"
 #include "llvm/MC/SubtargetFeature.h"
 #include "llvm/Object/IRObjectFile.h"
-#include "llvm/Object/ModuleSummaryIndexObjectFile.h"
 #include "llvm/Support/CachePruning.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Error.h"
@@ -47,6 +43,7 @@
 #include "llvm/Support/ThreadPool.h"
 #include "llvm/Support/Threading.h"
 #include "llvm/Support/ToolOutputFile.h"
+#include "llvm/Support/VCSRevision.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Transforms/IPO.h"
 #include "llvm/Transforms/IPO/FunctionImport.h"
@@ -66,6 +63,7 @@ namespace llvm {
 extern cl::opt<bool> LTODiscardValueNames;
 extern cl::opt<std::string> LTORemarksFilename;
 extern cl::opt<bool> LTOPassRemarksWithHotness;
+extern cl::opt<bool> LTOStripInvalidDebugInfo;
 }
 
 namespace {
@@ -73,27 +71,6 @@ namespace {
 static cl::opt<int>
     ThreadCount("threads", cl::init(llvm::heavyweight_hardware_concurrency()));
 
-Expected<std::unique_ptr<tool_output_file>>
-setupOptimizationRemarks(LLVMContext &Ctx, int Count) {
-  if (LTOPassRemarksWithHotness)
-    Ctx.setDiagnosticHotnessRequested(true);
-
-  if (LTORemarksFilename.empty())
-    return nullptr;
-
-  std::string FileName =
-      LTORemarksFilename + ".thin." + llvm::utostr(Count) + ".yaml";
-  std::error_code EC;
-  auto DiagnosticOutputFile =
-      llvm::make_unique<tool_output_file>(FileName, EC, sys::fs::F_None);
-  if (EC)
-    return errorCodeToError(EC);
-  Ctx.setDiagnosticsOutputFile(
-      llvm::make_unique<yaml::Output>(DiagnosticOutputFile->os()));
-  DiagnosticOutputFile->keep();
-  return std::move(DiagnosticOutputFile);
-}
-
 // Simple helper to save temporary files for debug.
 static void saveTempBitcode(const Module &TheModule, StringRef TempDir,
                             unsigned count, StringRef Suffix) {
@@ -144,8 +121,9 @@ static void computePrevailingCopies(
   };
 
   for (auto &I : Index) {
-    if (HasMultipleCopies(I.second))
-      PrevailingCopy[I.first] = getFirstDefinitionForLinker(I.second);
+    if (HasMultipleCopies(I.second.SummaryList))
+      PrevailingCopy[I.first] =
+          getFirstDefinitionForLinker(I.second.SummaryList);
   }
 }
 
@@ -166,6 +144,30 @@ static void promoteModule(Module &TheModule, const ModuleSummaryIndex &Index) {
     report_fatal_error("renameModuleForThinLTO failed");
 }
 
+namespace {
+class ThinLTODiagnosticInfo : public DiagnosticInfo {
+  const Twine &Msg;
+public:
+  ThinLTODiagnosticInfo(const Twine &DiagMsg,
+                        DiagnosticSeverity Severity = DS_Error)
+      : DiagnosticInfo(DK_Linker, Severity), Msg(DiagMsg) {}
+  void print(DiagnosticPrinter &DP) const override { DP << Msg; }
+};
+}
+
+/// Verify the module and strip broken debug info.
+static void verifyLoadedModule(Module &TheModule) {
+  bool BrokenDebugInfo = false;
+  if (verifyModule(TheModule, &dbgs(),
+                   LTOStripInvalidDebugInfo ? &BrokenDebugInfo : nullptr))
+    report_fatal_error("Broken module found, compilation aborted!");
+  if (BrokenDebugInfo) {
+    TheModule.getContext().diagnose(ThinLTODiagnosticInfo(
+        "Invalid debug info found, debug info will be stripped", DS_Warning));
+    StripDebugInfo(TheModule);
+  }
+}
+
 static std::unique_ptr<Module>
 loadModuleFromBuffer(const MemoryBufferRef &Buffer, LLVMContext &Context,
                      bool Lazy, bool IsImporting) {
@@ -183,6 +185,8 @@ loadModuleFromBuffer(const MemoryBufferRef &Buffer, LLVMContext &Context,
     });
     report_fatal_error("Can't load module, abort.");
   }
+  if (!Lazy)
+    verifyLoadedModule(*ModuleOrErr.get());
   return std::move(ModuleOrErr.get());
 }
 
@@ -205,19 +209,24 @@ crossImportIntoModule(Module &TheModule, const ModuleSummaryIndex &Index,
     });
     report_fatal_error("importFunctions failed");
   }
+  // Verify again after cross-importing.
+  verifyLoadedModule(TheModule);
 }
 
 static void optimizeModule(Module &TheModule, TargetMachine &TM,
-                           unsigned OptLevel) {
+                           unsigned OptLevel, bool Freestanding) {
   // Populate the PassManager
   PassManagerBuilder PMB;
   PMB.LibraryInfo = new TargetLibraryInfoImpl(TM.getTargetTriple());
+  if (Freestanding)
+    PMB.LibraryInfo->disableAllFunctions();
   PMB.Inliner = createFunctionInliningPass();
   // FIXME: should get it from the bitcode?
   PMB.OptLevel = OptLevel;
   PMB.LoopVectorize = true;
   PMB.SLPVectorize = true;
-  PMB.VerifyInput = true;
+  // Already did this in verifyLoadedModule().
+  PMB.VerifyInput = false;
   PMB.VerifyOutput = false;
 
   legacy::PassManager PM;
@@ -285,7 +294,7 @@ public:
       const std::map<GlobalValue::GUID, GlobalValue::LinkageTypes> &ResolvedODR,
       const GVSummaryMapTy &DefinedFunctions,
       const DenseSet<GlobalValue::GUID> &PreservedSymbols, unsigned OptLevel,
-      const TargetMachineBuilder &TMBuilder) {
+      bool Freestanding, const TargetMachineBuilder &TMBuilder) {
     if (CachePath.empty())
       return;
 
@@ -323,7 +332,7 @@ public:
 
     // Start with the compiler revision
     Hasher.update(LLVM_VERSION_STRING);
-#ifdef HAVE_LLVM_REVISION
+#ifdef LLVM_REVISION
     Hasher.update(LLVM_REVISION);
 #endif
 
@@ -342,6 +351,7 @@ public:
       AddUnsigned(*TMBuilder.RelocModel);
     AddUnsigned(TMBuilder.CGOptLevel);
     AddUnsigned(OptLevel);
+    AddUnsigned(Freestanding);
 
     Hasher.update(ArrayRef<uint8_t>((uint8_t *)&ModHash[0], sizeof(ModHash)));
     for (auto F : ExportList)
@@ -369,7 +379,10 @@ public:
             ArrayRef<uint8_t>((const uint8_t *)&Entry, sizeof(GlobalValue::GUID)));
     }
 
-    sys::path::append(EntryPath, CachePath, toHex(Hasher.result()));
+    // This choice of file name allows the cache to be pruned (see pruneCache()
+    // in include/llvm/Support/CachePruning.h).
+    sys::path::append(EntryPath, CachePath,
+                      "llvmcache-" + toHex(Hasher.result()));
   }
 
   // Access the path to this entry in the cache.
@@ -422,7 +435,7 @@ ProcessThinLTOModule(Module &TheModule, ModuleSummaryIndex &Index,
                      const GVSummaryMapTy &DefinedGlobals,
                      const ThinLTOCodeGenerator::CachingOptions &CacheOptions,
                      bool DisableCodeGen, StringRef SaveTempsDir,
-                     unsigned OptLevel, unsigned count) {
+                     bool Freestanding, unsigned OptLevel, unsigned count) {
 
   // "Benchmark"-like optimization: single-source case
   bool SingleModule = (ModuleMap.size() == 1);
@@ -454,7 +467,7 @@ ProcessThinLTOModule(Module &TheModule, ModuleSummaryIndex &Index,
     saveTempBitcode(TheModule, SaveTempsDir, count, ".3.imported.bc");
   }
 
-  optimizeModule(TheModule, TM, OptLevel);
+  optimizeModule(TheModule, TM, OptLevel, Freestanding);
 
   saveTempBitcode(TheModule, SaveTempsDir, count, ".4.opt.bc");
 
@@ -464,7 +477,7 @@ ProcessThinLTOModule(Module &TheModule, ModuleSummaryIndex &Index,
     {
       raw_svector_ostream OS(OutputBuffer);
       ProfileSummaryInfo PSI(TheModule);
-      auto Index = buildModuleSummaryIndex(TheModule, nullptr, nullptr);
+      auto Index = buildModuleSummaryIndex(TheModule, nullptr, &PSI);
       WriteBitcodeToFile(&TheModule, OS, true, &Index);
     }
     return make_unique<ObjectMemoryBuffer>(std::move(OutputBuffer));
@@ -523,29 +536,25 @@ static void initTMBuilder(TargetMachineBuilder &TMBuilder,
 
 void ThinLTOCodeGenerator::addModule(StringRef Identifier, StringRef Data) {
   ThinLTOBuffer Buffer(Data, Identifier);
-  if (Modules.empty()) {
-    // First module added, so initialize the triple and some options
-    LLVMContext Context;
-    StringRef TripleStr;
-    ErrorOr<std::string> TripleOrErr = expectedToErrorOrAndEmitErrors(
-        Context, getBitcodeTargetTriple(Buffer.getMemBuffer()));
-    if (TripleOrErr)
-      TripleStr = *TripleOrErr;
-    Triple TheTriple(TripleStr);
+  LLVMContext Context;
+  StringRef TripleStr;
+  ErrorOr<std::string> TripleOrErr = expectedToErrorOrAndEmitErrors(
+      Context, getBitcodeTargetTriple(Buffer.getMemBuffer()));
+
+  if (TripleOrErr)
+    TripleStr = *TripleOrErr;
+
+  Triple TheTriple(TripleStr);
+
+  if (Modules.empty())
     initTMBuilder(TMBuilder, Triple(TheTriple));
+  else if (TMBuilder.TheTriple != TheTriple) {
+    if (!TMBuilder.TheTriple.isCompatibleWith(TheTriple))
+      report_fatal_error("ThinLTO modules with incompatible triples not "
+                         "supported");
+    initTMBuilder(TMBuilder, Triple(TMBuilder.TheTriple.merge(TheTriple)));
   }
-#ifndef NDEBUG
-  else {
-    LLVMContext Context;
-    StringRef TripleStr;
-    ErrorOr<std::string> TripleOrErr = expectedToErrorOrAndEmitErrors(
-        Context, getBitcodeTargetTriple(Buffer.getMemBuffer()));
-    if (TripleOrErr)
-      TripleStr = *TripleOrErr;
-    assert(TMBuilder.TheTriple.str() == TripleStr &&
-           "ThinLTO modules with different triple not supported");
-  }
-#endif
+
   Modules.push_back(Buffer);
 }
 
@@ -584,25 +593,18 @@ std::unique_ptr<TargetMachine> TargetMachineBuilder::create() const {
  * "thin-link".
  */
 std::unique_ptr<ModuleSummaryIndex> ThinLTOCodeGenerator::linkCombinedIndex() {
-  std::unique_ptr<ModuleSummaryIndex> CombinedIndex;
+  std::unique_ptr<ModuleSummaryIndex> CombinedIndex =
+      llvm::make_unique<ModuleSummaryIndex>();
   uint64_t NextModuleId = 0;
   for (auto &ModuleBuffer : Modules) {
-    Expected<std::unique_ptr<object::ModuleSummaryIndexObjectFile>> ObjOrErr =
-        object::ModuleSummaryIndexObjectFile::create(
-            ModuleBuffer.getMemBuffer());
-    if (!ObjOrErr) {
+    if (Error Err = readModuleSummaryIndex(ModuleBuffer.getMemBuffer(),
+                                           *CombinedIndex, NextModuleId++)) {
       // FIXME diagnose
       logAllUnhandledErrors(
-          ObjOrErr.takeError(), errs(),
-          "error: can't create ModuleSummaryIndexObjectFile for buffer: ");
+          std::move(Err), errs(),
+          "error: can't create module summary index for buffer: ");
       return nullptr;
     }
-    auto Index = (*ObjOrErr)->takeIndex();
-    if (CombinedIndex) {
-      CombinedIndex->mergeFrom(std::move(Index), ++NextModuleId);
-    } else {
-      CombinedIndex = std::move(Index);
-    }
   }
   return CombinedIndex;
 }
@@ -625,13 +627,13 @@ void ThinLTOCodeGenerator::promote(Module &TheModule,
       PreservedSymbols, Triple(TheModule.getTargetTriple()));
 
   // Compute "dead" symbols, we don't want to import/export these!
-  auto DeadSymbols = computeDeadSymbols(Index, GUIDPreservedSymbols);
+  computeDeadSymbols(Index, GUIDPreservedSymbols);
 
   // Generate import/export list
   StringMap<FunctionImporter::ImportMapTy> ImportLists(ModuleCount);
   StringMap<FunctionImporter::ExportSetTy> ExportLists(ModuleCount);
   ComputeCrossModuleImport(Index, ModuleToDefinedGVSummaries, ImportLists,
-                           ExportLists, &DeadSymbols);
+                           ExportLists);
 
   // Resolve LinkOnce/Weak symbols.
   StringMap<std::map<GlobalValue::GUID, GlobalValue::LinkageTypes>> ResolvedODR;
@@ -670,13 +672,13 @@ void ThinLTOCodeGenerator::crossModuleImport(Module &TheModule,
       PreservedSymbols, Triple(TheModule.getTargetTriple()));
 
   // Compute "dead" symbols, we don't want to import/export these!
-  auto DeadSymbols = computeDeadSymbols(Index, GUIDPreservedSymbols);
+  computeDeadSymbols(Index, GUIDPreservedSymbols);
 
   // Generate import/export list
   StringMap<FunctionImporter::ImportMapTy> ImportLists(ModuleCount);
   StringMap<FunctionImporter::ExportSetTy> ExportLists(ModuleCount);
   ComputeCrossModuleImport(Index, ModuleToDefinedGVSummaries, ImportLists,
-                           ExportLists, &DeadSymbols);
+                           ExportLists);
   auto &ImportList = ImportLists[TheModule.getModuleIdentifier()];
 
   crossImportIntoModule(TheModule, Index, ModuleMap, ImportList);
@@ -747,13 +749,13 @@ void ThinLTOCodeGenerator::internalize(Module &TheModule,
   Index.collectDefinedGVSummariesPerModule(ModuleToDefinedGVSummaries);
 
   // Compute "dead" symbols, we don't want to import/export these!
-  auto DeadSymbols = computeDeadSymbols(Index, GUIDPreservedSymbols);
+  computeDeadSymbols(Index, GUIDPreservedSymbols);
 
   // Generate import/export list
   StringMap<FunctionImporter::ImportMapTy> ImportLists(ModuleCount);
   StringMap<FunctionImporter::ExportSetTy> ExportLists(ModuleCount);
   ComputeCrossModuleImport(Index, ModuleToDefinedGVSummaries, ImportLists,
-                           ExportLists, &DeadSymbols);
+                           ExportLists);
   auto &ExportList = ExportLists[ModuleIdentifier];
 
   // Be friendly and don't nuke totally the module when the client didn't
@@ -780,7 +782,7 @@ void ThinLTOCodeGenerator::optimize(Module &TheModule) {
   initTMBuilder(TMBuilder, Triple(TheModule.getTargetTriple()));
 
   // Optimize now
-  optimizeModule(TheModule, *TMBuilder.create(), OptLevel);
+  optimizeModule(TheModule, *TMBuilder.create(), OptLevel, Freestanding);
 }
 
 /**
@@ -899,14 +901,14 @@ void ThinLTOCodeGenerator::run() {
       computeGUIDPreservedSymbols(PreservedSymbols, TMBuilder.TheTriple);
 
   // Compute "dead" symbols, we don't want to import/export these!
-  auto DeadSymbols = computeDeadSymbols(*Index, GUIDPreservedSymbols);
+  computeDeadSymbols(*Index, GUIDPreservedSymbols);
 
   // Collect the import/export lists for all modules from the call-graph in the
   // combined index.
   StringMap<FunctionImporter::ImportMapTy> ImportLists(ModuleCount);
   StringMap<FunctionImporter::ExportSetTy> ExportLists(ModuleCount);
   ComputeCrossModuleImport(*Index, ModuleToDefinedGVSummaries, ImportLists,
-                           ExportLists, &DeadSymbols);
+                           ExportLists);
 
   // We use a std::map here to be able to have a defined ordering when
   // producing a hash for the cache entry.
@@ -966,7 +968,7 @@ void ThinLTOCodeGenerator::run() {
                                     ImportLists[ModuleIdentifier], ExportList,
                                     ResolvedODR[ModuleIdentifier],
                                     DefinedFunctions, GUIDPreservedSymbols,
-                                    OptLevel, TMBuilder);
+                                    OptLevel, Freestanding, TMBuilder);
         auto CacheEntryPath = CacheEntry.getEntryPath();
 
         {
@@ -990,7 +992,8 @@ void ThinLTOCodeGenerator::run() {
         LLVMContext Context;
         Context.setDiscardValueNames(LTODiscardValueNames);
         Context.enableDebugTypeODRUniquing();
-        auto DiagFileOrErr = setupOptimizationRemarks(Context, count);
+        auto DiagFileOrErr = lto::setupOptimizationRemarks(
+            Context, LTORemarksFilename, LTOPassRemarksWithHotness, count);
         if (!DiagFileOrErr) {
           errs() << "Error: " << toString(DiagFileOrErr.takeError()) << "\n";
           report_fatal_error("ThinLTO: Can't get an output file for the "
@@ -1011,7 +1014,7 @@ void ThinLTOCodeGenerator::run() {
             *TheModule, *Index, ModuleMap, *TMBuilder.create(), ImportList,
             ExportList, GUIDPreservedSymbols,
             ModuleToDefinedGVSummaries[ModuleIdentifier], CacheOptions,
-            DisableCodeGen, SaveTempsDir, OptLevel, count);
+            DisableCodeGen, SaveTempsDir, Freestanding, OptLevel, count);
 
         // Commit to the cache (if enabled)
         CacheEntry.write(*OutputBuffer);
@@ -1043,13 +1046,10 @@ void ThinLTOCodeGenerator::run() {
     }
   }
 
-  CachePruning(CacheOptions.Path)
-      .setPruningInterval(std::chrono::seconds(CacheOptions.PruningInterval))
-      .setEntryExpiration(std::chrono::seconds(CacheOptions.Expiration))
-      .setMaxSize(CacheOptions.MaxPercentageOfAvailableSpace)
-      .prune();
+  pruneCache(CacheOptions.Path, CacheOptions.Policy);
 
   // If statistics were requested, print them out now.
   if (llvm::AreStatisticsEnabled())
     llvm::PrintStatistics();
+  reportAndResetTimings();
 }
diff --git a/contrib/llvm/lib/LTO/UpdateCompilerUsed.cpp b/contrib/llvm/lib/LTO/UpdateCompilerUsed.cpp
index b67d9ea..5165cc9 100644
--- a/contrib/llvm/lib/LTO/UpdateCompilerUsed.cpp
+++ b/contrib/llvm/lib/LTO/UpdateCompilerUsed.cpp
@@ -65,7 +65,7 @@ private:
     // target.
     for (unsigned I = 0, E = static_cast<unsigned>(LibFunc::NumLibFuncs);
          I != E; ++I) {
-      LibFunc::Func F = static_cast<LibFunc::Func>(I);
+      LibFunc F = static_cast<LibFunc>(I);
       if (TLI.has(F))
         Libcalls.insert(TLI.getName(F));
     }