Merge clang, llvm, lld, lldb, compiler-rt and libc++ 5.0.0 release.

MFC r309126 (by emaste):

  Correct lld llvm-tblgen dependency file name

MFC r309169:

  Get rid of separate Subversion mergeinfo properties for llvm-dwarfdump
  and llvm-lto.  The mergeinfo confuses Subversion enormously, and these
  directories will just use the mergeinfo for llvm itself.

MFC r312765:

  Pull in r276136 from upstream llvm trunk (by Wei Mi):

    Use ValueOffsetPair to enhance value reuse during SCEV expansion.

    In D12090, the ExprValueMap was added to reuse existing value during
    SCEV expansion. However, const folding and sext/zext distribution can
    make the reuse still difficult.

    A simplified case is: suppose we know S1 expands to V1 in
    ExprValueMap, and
      S1 = S2 + C_a
      S3 = S2 + C_b
    where C_a and C_b are different SCEVConstants. Then we'd like to
    expand S3 as V1 - C_a + C_b instead of expanding S2 literally. It is
    helpful when S2 is a complex SCEV expr and S2 has no entry in
    ExprValueMap, which is usually caused by the fact that S3 is
    generated from S1 after const folding.

    In order to do that, we represent ExprValueMap as a mapping from SCEV
    to ValueOffsetPair. We will save both S1->{V1, 0} and S2->{V1, C_a}
    into the ExprValueMap when we create SCEV for V1. When S3 is
    expanded, it will first expand S2 to V1 - C_a because of S2->{V1,
    C_a} in the map, then expand S3 to V1 - C_a + C_b.

    Differential Revision: https://reviews.llvm.org/D21313

  This should fix assertion failures when building OpenCV >= 3.1.

  PR:		215649

MFC r312831:

  Revert r312765 for now, since it causes assertions when building
  lang/spidermonkey24.

  Reported by:	antoine
  PR:		215649

MFC r316511 (by jhb):

  Add an implementation of __ffssi2() derived from __ffsdi2().

  Newer versions of GCC include an __ffssi2() symbol in libgcc and the
  compiler can emit calls to it in generated code.  This is true for at
  least GCC 6.2 when compiling world for mips and mips64.

  Reviewed by:	jmallett, dim
  Sponsored by:	DARPA / AFRL
  Differential Revision:	https://reviews.freebsd.org/D10086

MFC r318601 (by adrian):

  [libcompiler-rt] add bswapdi2/bswapsi2

  This is required for mips gcc 6.3 userland to build/run.

  Reviewed by:	emaste, dim
  Approved by:	emaste
  Differential Revision:	https://reviews.freebsd.org/D10838

MFC r318884 (by emaste):

  lldb: map TRAP_CAP to a trace trap

  In the absense of a more specific handler for TRAP_CAP (generated by
  ENOTCAPABLE or ECAPMODE while in capability mode) treat it as a trace
  trap.

  Example usage (testing the bug in PR219173):

  % proccontrol -m trapcap lldb usr.bin/hexdump/obj/hexdump -- -Cv -s 1 /bin/ls
  ...
  (lldb) run
  Process 12980 launching
  Process 12980 launched: '.../usr.bin/hexdump/obj/hexdump' (x86_64)
  Process 12980 stopped
  * thread #1, stop reason = trace
      frame #0: 0x0000004b80c65f1a libc.so.7`__sys_lseek + 10
  ...

  In the future we should have LLDB control the trapcap procctl itself
  (as it does with ASLR), as well as report a specific stop reason.
  This change eliminates an assertion failure from LLDB for now.

MFC r319796:

  Remove a few unneeded files from libllvm, libclang and liblldb.

MFC r319885 (by emaste):

  lld: ELF: Fix ICF crash on absolute symbol relocations.

  If two sections contained relocations to absolute symbols with the same
  value we would crash when trying to access their sections. Add a check that
  both symbols point to sections before accessing their sections, and treat
  absolute symbols as equal if their values are equal.

  Obtained from:	LLD commit r292578

MFC r319918:

  Revert r319796 for now, it can cause undefined references when linking
  in some circumstances.

  Reported by:	Shawn Webb <shawn.webb@hardenedbsd.org>

MFC r319957 (by emaste):

  lld: Add armelf emulation mode

  Obtained from:	LLD r305375

MFC r321369:

  Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
  5.0.0 (trunk r308421).  Upstream has branched for the 5.0.0 release,
  which should be in about a month.  Please report bugs and regressions,
  so we can get them into the release.

  Please note that from 3.5.0 onwards, clang, llvm and lldb require C++11
  support to build; see UPDATING for more information.

MFC r321420:

  Add a few more object files to liblldb, which should solve errors when
  linking the lldb executable in some cases.  In particular, when the
  -ffunction-sections -fdata-sections options are turned off, or
  ineffective.

  Reported by:	Shawn Webb, Mark Millard

MFC r321433:

  Cleanup stale Options.inc files from the previous libllvm build for
  clang 4.0.0.  Otherwise, these can get included before the two newly
  generated ones (which are different) for clang 5.0.0.

  Reported by:	Mark Millard

MFC r321439 (by bdrewery):

  Move llvm Options.inc hack from r321433 for NO_CLEAN to lib/clang/libllvm.

  The files are only ever generated to .OBJDIR, not to WORLDTMP (as a
  sysroot) and are only ever included from a compilation.  So using
  a beforebuild target here removes the file before the compilation
  tries to include it.

MFC r321664:

  Pull in r308891 from upstream llvm trunk (by Benjamin Kramer):

    [CodeGenPrepare] Cut off FindAllMemoryUses if there are too many uses.

    This avoids excessive compile time. The case I'm looking at is
    Function.cpp from an old version of LLVM that still had the giant
    memcmp string matcher in it. Before r308322 this compiled in about 2
    minutes, after it, clang takes infinite* time to compile it. With
    this patch we're at 5 min, which is still bad but this is a
    pathological case.

    The cut off at 20 uses was chosen by looking at other cut-offs in LLVM
    for user scanning. It's probably too high, but does the job and is
    very unlikely to regress anything.

    Fixes PR33900.

    * I'm impatient and aborted after 15 minutes, on the bug report it was
      killed after 2h.

  Pull in r308986 from upstream llvm trunk (by Simon Pilgrim):

    [X86][CGP] Reduce memcmp() expansion to 2 load pairs (PR33914)

    D35067/rL308322 attempted to support up to 4 load pairs for memcmp
    inlining which resulted in regressions for some optimized libc memcmp
    implementations (PR33914).

    Until we can match these more optimal cases, this patch reduces the
    memcmp expansion to a maximum of 2 load pairs (which matches what we
    do for -Os).

    This patch should be considered for the 5.0.0 release branch as well

    Differential Revision: https://reviews.llvm.org/D35830

  These fix a hang (or extremely long compile time) when building older
  LLVM ports.

  Reported by:    antoine
  PR:             219139

MFC r321719:

  Pull in r309503 from upstream clang trunk (by Richard Smith):

    PR33902: Invalidate line number cache when adding more text to
    existing buffer.

    This led to crashes as the line number cache would report a bogus
    line number for a line of code, and we'd try to find a nonexistent
    column within the line when printing diagnostics.

  This fixes an assertion when building the graphics/champlain port.

  Reported by:	antoine, kwm
  PR:		219139

MFC r321723:

  Upgrade our copies of clang, llvm, lld and lldb to r309439 from the
  upstream release_50 branch.  This is just after upstream's 5.0.0-rc1.

MFC r322320:

  Upgrade our copies of clang, llvm and libc++ to r310316 from the
  upstream release_50 branch.

MFC r322326 (by emaste):

  lldb: Make i386-*-freebsd expression work on JIT path

  * Enable i386 ABI creation for freebsd
  * Added an extra argument in ABISysV_i386::PrepareTrivialCall for mmap
    syscall
  * Unlike linux, the last argument of mmap is actually 64-bit(off_t).
    This requires us to push an additional word for the higher order bits.
  * Prior to this change, ktrace dump will show mmap failures due to
    invalid argument coming from the 6th mmap argument.

  Submitted by:	Karnajit Wangkhem
  Differential Revision:	https://reviews.llvm.org/D34776

MFC r322360 (by emaste):

  lldb: Report inferior signals as signals, not exceptions, on FreeBSD

  This is the FreeBSD equivalent of LLVM r238549.

  This serves 2 purposes:

  * LLDB should handle inferior process signals SIGSEGV/SIGILL/SIGBUS/
    SIGFPE the way it is suppose to be handled. Prior to this fix these
    signals will neither create a coredump, nor exit from the debugger
    or work for signal handling scenario.
  * eInvalidCrashReason need not report "unknown crash reason" if we have
    a valid si_signo

  llvm.org/pr23699

  Patch by Karnajit Wangkhem

  Differential Revision:  https://reviews.llvm.org/D35223

  Submitted by:	Karnajit Wangkhem
  Obtained from:	LLVM r310591

MFC r322474 (by emaste):

  lld: Add `-z muldefs` option.

  Obtained from:	LLVM r310757

MFC r322740:

  Upgrade our copies of clang, llvm, lld and libc++ to r311219 from the
  upstream release_50 branch.

MFC r322855:

  Upgrade our copies of clang, llvm, lldb and compiler-rt to r311606 from
  the upstream release_50 branch.

  As of this version, lib/msun's trig test should also work correctly
  again (see bug 220989 for more information).

  PR:		220989

MFC r323112:

  Upgrade our copies of clang, llvm, lldb and compiler-rt to r312293 from
  the upstream release_50 branch.  This corresponds to 5.0.0 rc4.

  As of this version, the cad/stepcode port should now compile in a more
  reasonable time on i386 (see bug 221836 for more information).

  PR:		221836

MFC r323245:

  Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
  5.0.0 release (upstream r312559).

  Release notes for llvm, clang and lld will be available here soon:
  <http://releases.llvm.org/5.0.0/docs/ReleaseNotes.html>
  <http://releases.llvm.org/5.0.0/tools/clang/docs/ReleaseNotes.html>
  <http://releases.llvm.org/5.0.0/tools/lld/docs/ReleaseNotes.html>

  Relnotes:	yes

(cherry picked from commit 12cd91cf4c6b96a24427c0de5374916f2808d263)

3 files changed, 583 insertions, 545 deletions

diff --git a/contrib/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/contrib/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index ebb2022..dcffde1 100644
--- a/contrib/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/contrib/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -28,10 +28,13 @@
 #include "llvm/IR/Operator.h"
 #include "llvm/IR/UseListOrder.h"
 #include "llvm/IR/ValueSymbolTable.h"
+#include "llvm/MC/StringTableBuilder.h"
+#include "llvm/Object/IRSymtab.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/Program.h"
 #include "llvm/Support/SHA1.h"
+#include "llvm/Support/TargetRegistry.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cctype>
 #include <map>
@@ -76,21 +79,24 @@ protected:
   /// The stream created and owned by the client.
   BitstreamWriter &Stream;
 
-  /// Saves the offset of the VSTOffset record that must eventually be
-  /// backpatched with the offset of the actual VST.
-  uint64_t VSTOffsetPlaceholder = 0;
+  StringTableBuilder &StrtabBuilder;
 
 public:
   /// Constructs a BitcodeWriterBase object that writes to the provided
   /// \p Stream.
-  BitcodeWriterBase(BitstreamWriter &Stream) : Stream(Stream) {}
+  BitcodeWriterBase(BitstreamWriter &Stream, StringTableBuilder &StrtabBuilder)
+      : Stream(Stream), StrtabBuilder(StrtabBuilder) {}
 
 protected:
-  bool hasVSTOffsetPlaceholder() { return VSTOffsetPlaceholder != 0; }
-  void writeValueSymbolTableForwardDecl();
   void writeBitcodeHeader();
+  void writeModuleVersion();
 };
 
+void BitcodeWriterBase::writeModuleVersion() {
+  // VERSION: [version#]
+  Stream.EmitRecord(bitc::MODULE_CODE_VERSION, ArrayRef<uint64_t>{2});
+}
+
 /// Class to manage the bitcode writing for a module.
 class ModuleBitcodeWriter : public BitcodeWriterBase {
   /// Pointer to the buffer allocated by caller for bitcode writing.
@@ -108,6 +114,16 @@ class ModuleBitcodeWriter : public BitcodeWriterBase {
   /// True if a module hash record should be written.
   bool GenerateHash;
 
+  SHA1 Hasher;
+
+  /// If non-null, when GenerateHash is true, the resulting hash is written
+  /// into ModHash. When GenerateHash is false, that specified value
+  /// is used as the hash instead of computing from the generated bitcode.
+  /// Can be used to produce the same module hash for a minimized bitcode
+  /// used just for the thin link as in the regular full bitcode that will
+  /// be used in the backend.
+  ModuleHash *ModHash;
+
   /// The start bit of the identification block.
   uint64_t BitcodeStartBit;
 
@@ -119,15 +135,22 @@ class ModuleBitcodeWriter : public BitcodeWriterBase {
   /// Tracks the last value id recorded in the GUIDToValueMap.
   unsigned GlobalValueId;
 
+  /// Saves the offset of the VSTOffset record that must eventually be
+  /// backpatched with the offset of the actual VST.
+  uint64_t VSTOffsetPlaceholder = 0;
+
 public:
   /// Constructs a ModuleBitcodeWriter object for the given Module,
   /// writing to the provided \p Buffer.
   ModuleBitcodeWriter(const Module *M, SmallVectorImpl<char> &Buffer,
+                      StringTableBuilder &StrtabBuilder,
                       BitstreamWriter &Stream, bool ShouldPreserveUseListOrder,
-                      const ModuleSummaryIndex *Index, bool GenerateHash)
-      : BitcodeWriterBase(Stream), Buffer(Buffer), M(*M),
+                      const ModuleSummaryIndex *Index, bool GenerateHash,
+                      ModuleHash *ModHash = nullptr)
+      : BitcodeWriterBase(Stream, StrtabBuilder), Buffer(Buffer), M(*M),
         VE(*M, ShouldPreserveUseListOrder), Index(Index),
-        GenerateHash(GenerateHash), BitcodeStartBit(Stream.GetCurrentBitNo()) {
+        GenerateHash(GenerateHash), ModHash(ModHash),
+        BitcodeStartBit(Stream.GetCurrentBitNo()) {
     // Assign ValueIds to any callee values in the index that came from
     // indirect call profiles and were recorded as a GUID not a Value*
     // (which would have been assigned an ID by the ValueEnumerator).
@@ -138,14 +161,14 @@ public:
       return;
     for (const auto &GUIDSummaryLists : *Index)
       // Examine all summaries for this GUID.
-      for (auto &Summary : GUIDSummaryLists.second)
+      for (auto &Summary : GUIDSummaryLists.second.SummaryList)
         if (auto FS = dyn_cast<FunctionSummary>(Summary.get()))
           // For each call in the function summary, see if the call
           // is to a GUID (which means it is for an indirect call,
           // otherwise we would have a Value for it). If so, synthesize
           // a value id.
           for (auto &CallEdge : FS->calls())
-            if (CallEdge.first.isGUID())
+            if (!CallEdge.first.getValue())
               assignValueId(CallEdge.first.getGUID());
   }
 
@@ -155,10 +178,13 @@ public:
 private:
   uint64_t bitcodeStartBit() { return BitcodeStartBit; }
 
+  size_t addToStrtab(StringRef Str);
+
   void writeAttributeGroupTable();
   void writeAttributeTable();
   void writeTypeTable();
   void writeComdats();
+  void writeValueSymbolTableForwardDecl();
   void writeModuleInfo();
   void writeValueAsMetadata(const ValueAsMetadata *MD,
                             SmallVectorImpl<uint64_t> &Record);
@@ -240,6 +266,7 @@ private:
                                     const GlobalObject &GO);
   void writeModuleMetadataKinds();
   void writeOperandBundleTags();
+  void writeSyncScopeNames();
   void writeConstants(unsigned FirstVal, unsigned LastVal, bool isGlobal);
   void writeModuleConstants();
   bool pushValueAndType(const Value *V, unsigned InstID,
@@ -251,9 +278,9 @@ private:
                        SmallVectorImpl<uint64_t> &Vals);
   void writeInstruction(const Instruction &I, unsigned InstID,
                         SmallVectorImpl<unsigned> &Vals);
-  void writeValueSymbolTable(
-      const ValueSymbolTable &VST, bool IsModuleLevel = false,
-      DenseMap<const Function *, uint64_t> *FunctionToBitcodeIndex = nullptr);
+  void writeFunctionLevelValueSymbolTable(const ValueSymbolTable &VST);
+  void writeGlobalValueSymbolTable(
+      DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex);
   void writeUseList(UseListOrder &&Order);
   void writeUseListBlock(const Function *F);
   void
@@ -285,11 +312,15 @@ private:
   }
   // Helper to get the valueId for the type of value recorded in VI.
   unsigned getValueId(ValueInfo VI) {
-    if (VI.isGUID())
+    if (!VI.getValue())
       return getValueId(VI.getGUID());
     return VE.getValueID(VI.getValue());
   }
   std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
+
+  unsigned getEncodedSyncScopeID(SyncScope::ID SSID) {
+    return unsigned(SSID);
+  }
 };
 
 /// Class to manage the bitcode writing for a combined index.
@@ -312,186 +343,75 @@ public:
   /// Constructs a IndexBitcodeWriter object for the given combined index,
   /// writing to the provided \p Buffer. When writing a subset of the index
   /// for a distributed backend, provide a \p ModuleToSummariesForIndex map.
-  IndexBitcodeWriter(BitstreamWriter &Stream, const ModuleSummaryIndex &Index,
+  IndexBitcodeWriter(BitstreamWriter &Stream, StringTableBuilder &StrtabBuilder,
+                     const ModuleSummaryIndex &Index,
                      const std::map<std::string, GVSummaryMapTy>
                          *ModuleToSummariesForIndex = nullptr)
-      : BitcodeWriterBase(Stream), Index(Index),
+      : BitcodeWriterBase(Stream, StrtabBuilder), Index(Index),
         ModuleToSummariesForIndex(ModuleToSummariesForIndex) {
     // Assign unique value ids to all summaries to be written, for use
     // in writing out the call graph edges. Save the mapping from GUID
     // to the new global value id to use when writing those edges, which
     // are currently saved in the index in terms of GUID.
-    for (const auto &I : *this)
+    forEachSummary([&](GVInfo I) {
       GUIDToValueIdMap[I.first] = ++GlobalValueId;
+    });
   }
 
   /// The below iterator returns the GUID and associated summary.
   typedef std::pair<GlobalValue::GUID, GlobalValueSummary *> GVInfo;
 
-  /// Iterator over the value GUID and summaries to be written to bitcode,
-  /// hides the details of whether they are being pulled from the entire
-  /// index or just those in a provided ModuleToSummariesForIndex map.
-  class iterator
-      : public llvm::iterator_facade_base<iterator, std::forward_iterator_tag,
-                                          GVInfo> {
-    /// Enables access to parent class.
-    const IndexBitcodeWriter &Writer;
-
-    // Iterators used when writing only those summaries in a provided
-    // ModuleToSummariesForIndex map:
-
-    /// Points to the last element in outer ModuleToSummariesForIndex map.
-    std::map<std::string, GVSummaryMapTy>::const_iterator ModuleSummariesBack;
-    /// Iterator on outer ModuleToSummariesForIndex map.
-    std::map<std::string, GVSummaryMapTy>::const_iterator ModuleSummariesIter;
-    /// Iterator on an inner global variable summary map.
-    GVSummaryMapTy::const_iterator ModuleGVSummariesIter;
-
-    // Iterators used when writing all summaries in the index:
-
-    /// Points to the last element in the Index outer GlobalValueMap.
-    const_gvsummary_iterator IndexSummariesBack;
-    /// Iterator on outer GlobalValueMap.
-    const_gvsummary_iterator IndexSummariesIter;
-    /// Iterator on an inner GlobalValueSummaryList.
-    GlobalValueSummaryList::const_iterator IndexGVSummariesIter;
-
-  public:
-    /// Construct iterator from parent \p Writer and indicate if we are
-    /// constructing the end iterator.
-    iterator(const IndexBitcodeWriter &Writer, bool IsAtEnd) : Writer(Writer) {
-      // Set up the appropriate set of iterators given whether we are writing
-      // the full index or just a subset.
-      // Can't setup the Back or inner iterators if the corresponding map
-      // is empty. This will be handled specially in operator== as well.
-      if (Writer.ModuleToSummariesForIndex &&
-          !Writer.ModuleToSummariesForIndex->empty()) {
-        for (ModuleSummariesBack = Writer.ModuleToSummariesForIndex->begin();
-             std::next(ModuleSummariesBack) !=
-             Writer.ModuleToSummariesForIndex->end();
-             ModuleSummariesBack++)
-          ;
-        ModuleSummariesIter = !IsAtEnd
-                                  ? Writer.ModuleToSummariesForIndex->begin()
-                                  : ModuleSummariesBack;
-        ModuleGVSummariesIter = !IsAtEnd ? ModuleSummariesIter->second.begin()
-                                         : ModuleSummariesBack->second.end();
-      } else if (!Writer.ModuleToSummariesForIndex &&
-                 Writer.Index.begin() != Writer.Index.end()) {
-        for (IndexSummariesBack = Writer.Index.begin();
-             std::next(IndexSummariesBack) != Writer.Index.end();
-             IndexSummariesBack++)
-          ;
-        IndexSummariesIter =
-            !IsAtEnd ? Writer.Index.begin() : IndexSummariesBack;
-        IndexGVSummariesIter = !IsAtEnd ? IndexSummariesIter->second.begin()
-                                        : IndexSummariesBack->second.end();
-      }
+  /// Calls the callback for each value GUID and summary to be written to
+  /// bitcode. This hides the details of whether they are being pulled from the
+  /// entire index or just those in a provided ModuleToSummariesForIndex map.
+  template<typename Functor>
+  void forEachSummary(Functor Callback) {
+    if (ModuleToSummariesForIndex) {
+      for (auto &M : *ModuleToSummariesForIndex)
+        for (auto &Summary : M.second)
+          Callback(Summary);
+    } else {
+      for (auto &Summaries : Index)
+        for (auto &Summary : Summaries.second.SummaryList)
+          Callback({Summaries.first, Summary.get()});
     }
+  }
 
-    /// Increment the appropriate set of iterators.
-    iterator &operator++() {
-      // First the inner iterator is incremented, then if it is at the end
-      // and there are more outer iterations to go, the inner is reset to
-      // the start of the next inner list.
-      if (Writer.ModuleToSummariesForIndex) {
-        ++ModuleGVSummariesIter;
-        if (ModuleGVSummariesIter == ModuleSummariesIter->second.end() &&
-            ModuleSummariesIter != ModuleSummariesBack) {
-          ++ModuleSummariesIter;
-          ModuleGVSummariesIter = ModuleSummariesIter->second.begin();
-        }
-      } else {
-        ++IndexGVSummariesIter;
-        if (IndexGVSummariesIter == IndexSummariesIter->second.end() &&
-            IndexSummariesIter != IndexSummariesBack) {
-          ++IndexSummariesIter;
-          IndexGVSummariesIter = IndexSummariesIter->second.begin();
+  /// Calls the callback for each entry in the modulePaths StringMap that
+  /// should be written to the module path string table. This hides the details
+  /// of whether they are being pulled from the entire index or just those in a
+  /// provided ModuleToSummariesForIndex map.
+  template <typename Functor> void forEachModule(Functor Callback) {
+    if (ModuleToSummariesForIndex) {
+      for (const auto &M : *ModuleToSummariesForIndex) {
+        const auto &MPI = Index.modulePaths().find(M.first);
+        if (MPI == Index.modulePaths().end()) {
+          // This should only happen if the bitcode file was empty, in which
+          // case we shouldn't be importing (the ModuleToSummariesForIndex
+          // would only include the module we are writing and index for).
+          assert(ModuleToSummariesForIndex->size() == 1);
+          continue;
         }
+        Callback(*MPI);
       }
-      return *this;
-    }
-
-    /// Access the <GUID,GlobalValueSummary*> pair corresponding to the current
-    /// outer and inner iterator positions.
-    GVInfo operator*() {
-      if (Writer.ModuleToSummariesForIndex)
-        return std::make_pair(ModuleGVSummariesIter->first,
-                              ModuleGVSummariesIter->second);
-      return std::make_pair(IndexSummariesIter->first,
-                            IndexGVSummariesIter->get());
-    }
-
-    /// Checks if the iterators are equal, with special handling for empty
-    /// indexes.
-    bool operator==(const iterator &RHS) const {
-      if (Writer.ModuleToSummariesForIndex) {
-        // First ensure that both are writing the same subset.
-        if (Writer.ModuleToSummariesForIndex !=
-            RHS.Writer.ModuleToSummariesForIndex)
-          return false;
-        // Already determined above that maps are the same, so if one is
-        // empty, they both are.
-        if (Writer.ModuleToSummariesForIndex->empty())
-          return true;
-        // Ensure the ModuleGVSummariesIter are iterating over the same
-        // container before checking them below.
-        if (ModuleSummariesIter != RHS.ModuleSummariesIter)
-          return false;
-        return ModuleGVSummariesIter == RHS.ModuleGVSummariesIter;
-      }
-      // First ensure RHS also writing the full index, and that both are
-      // writing the same full index.
-      if (RHS.Writer.ModuleToSummariesForIndex ||
-          &Writer.Index != &RHS.Writer.Index)
-        return false;
-      // Already determined above that maps are the same, so if one is
-      // empty, they both are.
-      if (Writer.Index.begin() == Writer.Index.end())
-        return true;
-      // Ensure the IndexGVSummariesIter are iterating over the same
-      // container before checking them below.
-      if (IndexSummariesIter != RHS.IndexSummariesIter)
-        return false;
-      return IndexGVSummariesIter == RHS.IndexGVSummariesIter;
+    } else {
+      for (const auto &MPSE : Index.modulePaths())
+        Callback(MPSE);
     }
-  };
-
-  /// Obtain the start iterator over the summaries to be written.
-  iterator begin() { return iterator(*this, /*IsAtEnd=*/false); }
-  /// Obtain the end iterator over the summaries to be written.
-  iterator end() { return iterator(*this, /*IsAtEnd=*/true); }
+  }
 
   /// Main entry point for writing a combined index to bitcode.
   void write();
 
 private:
-  void writeIndex();
   void writeModStrings();
-  void writeCombinedValueSymbolTable();
   void writeCombinedGlobalValueSummary();
 
-  /// Indicates whether the provided \p ModulePath should be written into
-  /// the module string table, e.g. if full index written or if it is in
-  /// the provided subset.
-  bool doIncludeModule(StringRef ModulePath) {
-    return !ModuleToSummariesForIndex ||
-           ModuleToSummariesForIndex->count(ModulePath);
-  }
-
-  bool hasValueId(GlobalValue::GUID ValGUID) {
-    const auto &VMI = GUIDToValueIdMap.find(ValGUID);
-    return VMI != GUIDToValueIdMap.end();
-  }
-  unsigned getValueId(GlobalValue::GUID ValGUID) {
-    const auto &VMI = GUIDToValueIdMap.find(ValGUID);
-    // If this GUID doesn't have an entry, assign one.
-    if (VMI == GUIDToValueIdMap.end()) {
-      GUIDToValueIdMap[ValGUID] = ++GlobalValueId;
-      return GlobalValueId;
-    } else {
-      return VMI->second;
-    }
+  Optional<unsigned> getValueId(GlobalValue::GUID ValGUID) {
+    auto VMI = GUIDToValueIdMap.find(ValGUID);
+    if (VMI == GUIDToValueIdMap.end())
+      return None;
+    return VMI->second;
   }
   std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
 };
@@ -570,14 +490,6 @@ static unsigned getEncodedOrdering(AtomicOrdering Ordering) {
   llvm_unreachable("Invalid ordering");
 }
 
-static unsigned getEncodedSynchScope(SynchronizationScope SynchScope) {
-  switch (SynchScope) {
-  case SingleThread: return bitc::SYNCHSCOPE_SINGLETHREAD;
-  case CrossThread: return bitc::SYNCHSCOPE_CROSSTHREAD;
-  }
-  llvm_unreachable("Invalid synch scope");
-}
-
 static void writeStringRecord(BitstreamWriter &Stream, unsigned Code,
                               StringRef Str, unsigned AbbrevToUse) {
   SmallVector<unsigned, 64> Vals;
@@ -671,6 +583,8 @@ static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
     return bitc::ATTR_KIND_RETURNS_TWICE;
   case Attribute::SExt:
     return bitc::ATTR_KIND_S_EXT;
+  case Attribute::Speculatable:
+    return bitc::ATTR_KIND_SPECULATABLE;
   case Attribute::StackAlignment:
     return bitc::ATTR_KIND_STACK_ALIGNMENT;
   case Attribute::StackProtect:
@@ -709,63 +623,62 @@ static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
 }
 
 void ModuleBitcodeWriter::writeAttributeGroupTable() {
-  const std::vector<AttributeSet> &AttrGrps = VE.getAttributeGroups();
+  const std::vector<ValueEnumerator::IndexAndAttrSet> &AttrGrps =
+      VE.getAttributeGroups();
   if (AttrGrps.empty()) return;
 
   Stream.EnterSubblock(bitc::PARAMATTR_GROUP_BLOCK_ID, 3);
 
   SmallVector<uint64_t, 64> Record;
-  for (unsigned i = 0, e = AttrGrps.size(); i != e; ++i) {
-    AttributeSet AS = AttrGrps[i];
-    for (unsigned i = 0, e = AS.getNumSlots(); i != e; ++i) {
-      AttributeSet A = AS.getSlotAttributes(i);
-
-      Record.push_back(VE.getAttributeGroupID(A));
-      Record.push_back(AS.getSlotIndex(i));
-
-      for (AttributeSet::iterator I = AS.begin(0), E = AS.end(0);
-           I != E; ++I) {
-        Attribute Attr = *I;
-        if (Attr.isEnumAttribute()) {
-          Record.push_back(0);
-          Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
-        } else if (Attr.isIntAttribute()) {
-          Record.push_back(1);
-          Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
-          Record.push_back(Attr.getValueAsInt());
-        } else {
-          StringRef Kind = Attr.getKindAsString();
-          StringRef Val = Attr.getValueAsString();
-
-          Record.push_back(Val.empty() ? 3 : 4);
-          Record.append(Kind.begin(), Kind.end());
+  for (ValueEnumerator::IndexAndAttrSet Pair : AttrGrps) {
+    unsigned AttrListIndex = Pair.first;
+    AttributeSet AS = Pair.second;
+    Record.push_back(VE.getAttributeGroupID(Pair));
+    Record.push_back(AttrListIndex);
+
+    for (Attribute Attr : AS) {
+      if (Attr.isEnumAttribute()) {
+        Record.push_back(0);
+        Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
+      } else if (Attr.isIntAttribute()) {
+        Record.push_back(1);
+        Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
+        Record.push_back(Attr.getValueAsInt());
+      } else {
+        StringRef Kind = Attr.getKindAsString();
+        StringRef Val = Attr.getValueAsString();
+
+        Record.push_back(Val.empty() ? 3 : 4);
+        Record.append(Kind.begin(), Kind.end());
+        Record.push_back(0);
+        if (!Val.empty()) {
+          Record.append(Val.begin(), Val.end());
           Record.push_back(0);
-          if (!Val.empty()) {
-            Record.append(Val.begin(), Val.end());
-            Record.push_back(0);
-          }
         }
       }
-
-      Stream.EmitRecord(bitc::PARAMATTR_GRP_CODE_ENTRY, Record);
-      Record.clear();
     }
+
+    Stream.EmitRecord(bitc::PARAMATTR_GRP_CODE_ENTRY, Record);
+    Record.clear();
   }
 
   Stream.ExitBlock();
 }
 
 void ModuleBitcodeWriter::writeAttributeTable() {
-  const std::vector<AttributeSet> &Attrs = VE.getAttributes();
+  const std::vector<AttributeList> &Attrs = VE.getAttributeLists();
   if (Attrs.empty()) return;
 
   Stream.EnterSubblock(bitc::PARAMATTR_BLOCK_ID, 3);
 
   SmallVector<uint64_t, 64> Record;
   for (unsigned i = 0, e = Attrs.size(); i != e; ++i) {
-    const AttributeSet &A = Attrs[i];
-    for (unsigned i = 0, e = A.getNumSlots(); i != e; ++i)
-      Record.push_back(VE.getAttributeGroupID(A.getSlotAttributes(i)));
+    AttributeList AL = Attrs[i];
+    for (unsigned i = AL.index_begin(), e = AL.index_end(); i != e; ++i) {
+      AttributeSet AS = AL.getAttributes(i);
+      if (AS.hasAttributes())
+        Record.push_back(VE.getAttributeGroupID({i, AS}));
+    }
 
     Stream.EmitRecord(bitc::PARAMATTR_CODE_ENTRY, Record);
     Record.clear();
@@ -972,7 +885,7 @@ static uint64_t getEncodedGVSummaryFlags(GlobalValueSummary::GVFlags Flags) {
   uint64_t RawFlags = 0;
 
   RawFlags |= Flags.NotEligibleToImport; // bool
-  RawFlags |= (Flags.LiveRoot << 1);
+  RawFlags |= (Flags.Live << 1);
   // Linkage don't need to be remapped at that time for the summary. Any future
   // change to the getEncodedLinkage() function will need to be taken into
   // account here as well.
@@ -1035,16 +948,19 @@ static unsigned getEncodedUnnamedAddr(const GlobalValue &GV) {
   llvm_unreachable("Invalid unnamed_addr");
 }
 
+size_t ModuleBitcodeWriter::addToStrtab(StringRef Str) {
+  if (GenerateHash)
+    Hasher.update(Str);
+  return StrtabBuilder.add(Str);
+}
+
 void ModuleBitcodeWriter::writeComdats() {
   SmallVector<unsigned, 64> Vals;
   for (const Comdat *C : VE.getComdats()) {
-    // COMDAT: [selection_kind, name]
+    // COMDAT: [strtab offset, strtab size, selection_kind]
+    Vals.push_back(addToStrtab(C->getName()));
+    Vals.push_back(C->getName().size());
     Vals.push_back(getEncodedComdatSelectionKind(*C));
-    size_t Size = C->getName().size();
-    assert(isUInt<32>(Size));
-    Vals.push_back(Size);
-    for (char Chr : C->getName())
-      Vals.push_back((unsigned char)Chr);
     Stream.EmitRecord(bitc::MODULE_CODE_COMDAT, Vals, /*AbbrevToUse=*/0);
     Vals.clear();
   }
@@ -1053,7 +969,7 @@ void ModuleBitcodeWriter::writeComdats() {
 /// Write a record that will eventually hold the word offset of the
 /// module-level VST. For now the offset is 0, which will be backpatched
 /// after the real VST is written. Saves the bit offset to backpatch.
-void BitcodeWriterBase::writeValueSymbolTableForwardDecl() {
+void ModuleBitcodeWriter::writeValueSymbolTableForwardDecl() {
   // Write a placeholder value in for the offset of the real VST,
   // which is written after the function blocks so that it can include
   // the offset of each function. The placeholder offset will be
@@ -1079,19 +995,18 @@ void BitcodeWriterBase::writeValueSymbolTableForwardDecl() {
 enum StringEncoding { SE_Char6, SE_Fixed7, SE_Fixed8 };
 
 /// Determine the encoding to use for the given string name and length.
-static StringEncoding getStringEncoding(const char *Str, unsigned StrLen) {
+static StringEncoding getStringEncoding(StringRef Str) {
   bool isChar6 = true;
-  for (const char *C = Str, *E = C + StrLen; C != E; ++C) {
+  for (char C : Str) {
     if (isChar6)
-      isChar6 = BitCodeAbbrevOp::isChar6(*C);
-    if ((unsigned char)*C & 128)
+      isChar6 = BitCodeAbbrevOp::isChar6(C);
+    if ((unsigned char)C & 128)
       // don't bother scanning the rest.
       return SE_Fixed8;
   }
   if (isChar6)
     return SE_Char6;
-  else
-    return SE_Fixed7;
+  return SE_Fixed7;
 }
 
 /// Emit top-level description of module, including target triple, inline asm,
@@ -1156,6 +1071,8 @@ void ModuleBitcodeWriter::writeModuleInfo() {
     // Add an abbrev for common globals with no visibility or thread localness.
     auto Abbv = std::make_shared<BitCodeAbbrev>();
     Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_GLOBALVAR));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));
     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
                               Log2_32_Ceil(MaxGlobalType+1)));
     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // AddrSpace << 2
@@ -1179,15 +1096,41 @@ void ModuleBitcodeWriter::writeModuleInfo() {
     SimpleGVarAbbrev = Stream.EmitAbbrev(std::move(Abbv));
   }
 
-  // Emit the global variable information.
   SmallVector<unsigned, 64> Vals;
+  // Emit the module's source file name.
+  {
+    StringEncoding Bits = getStringEncoding(M.getSourceFileName());
+    BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
+    if (Bits == SE_Char6)
+      AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
+    else if (Bits == SE_Fixed7)
+      AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
+
+    // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
+    auto Abbv = std::make_shared<BitCodeAbbrev>();
+    Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+    Abbv->Add(AbbrevOpToUse);
+    unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
+
+    for (const auto P : M.getSourceFileName())
+      Vals.push_back((unsigned char)P);
+
+    // Emit the finished record.
+    Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
+    Vals.clear();
+  }
+
+  // Emit the global variable information.
   for (const GlobalVariable &GV : M.globals()) {
     unsigned AbbrevToUse = 0;
 
-    // GLOBALVAR: [type, isconst, initid,
+    // GLOBALVAR: [strtab offset, strtab size, type, isconst, initid,
     //             linkage, alignment, section, visibility, threadlocal,
     //             unnamed_addr, externally_initialized, dllstorageclass,
-    //             comdat]
+    //             comdat, attributes]
+    Vals.push_back(addToStrtab(GV.getName()));
+    Vals.push_back(GV.getName().size());
     Vals.push_back(VE.getTypeID(GV.getValueType()));
     Vals.push_back(GV.getType()->getAddressSpace() << 2 | 2 | GV.isConstant());
     Vals.push_back(GV.isDeclaration() ? 0 :
@@ -1200,13 +1143,17 @@ void ModuleBitcodeWriter::writeModuleInfo() {
         GV.getUnnamedAddr() != GlobalValue::UnnamedAddr::None ||
         GV.isExternallyInitialized() ||
         GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass ||
-        GV.hasComdat()) {
+        GV.hasComdat() ||
+        GV.hasAttributes()) {
       Vals.push_back(getEncodedVisibility(GV));
       Vals.push_back(getEncodedThreadLocalMode(GV));
       Vals.push_back(getEncodedUnnamedAddr(GV));
       Vals.push_back(GV.isExternallyInitialized());
       Vals.push_back(getEncodedDLLStorageClass(GV));
       Vals.push_back(GV.hasComdat() ? VE.getComdatID(GV.getComdat()) : 0);
+
+      auto AL = GV.getAttributesAsList(AttributeList::FunctionIndex);
+      Vals.push_back(VE.getAttributeListID(AL));
     } else {
       AbbrevToUse = SimpleGVarAbbrev;
     }
@@ -1217,14 +1164,17 @@ void ModuleBitcodeWriter::writeModuleInfo() {
 
   // Emit the function proto information.
   for (const Function &F : M) {
-    // FUNCTION:  [type, callingconv, isproto, linkage, paramattrs, alignment,
-    //             section, visibility, gc, unnamed_addr, prologuedata,
-    //             dllstorageclass, comdat, prefixdata, personalityfn]
+    // FUNCTION:  [strtab offset, strtab size, type, callingconv, isproto,
+    //             linkage, paramattrs, alignment, section, visibility, gc,
+    //             unnamed_addr, prologuedata, dllstorageclass, comdat,
+    //             prefixdata, personalityfn]
+    Vals.push_back(addToStrtab(F.getName()));
+    Vals.push_back(F.getName().size());
     Vals.push_back(VE.getTypeID(F.getFunctionType()));
     Vals.push_back(F.getCallingConv());
     Vals.push_back(F.isDeclaration());
     Vals.push_back(getEncodedLinkage(F));
-    Vals.push_back(VE.getAttributeID(F.getAttributes()));
+    Vals.push_back(VE.getAttributeListID(F.getAttributes()));
     Vals.push_back(Log2_32(F.getAlignment())+1);
     Vals.push_back(F.hasSection() ? SectionMap[F.getSection()] : 0);
     Vals.push_back(getEncodedVisibility(F));
@@ -1246,8 +1196,10 @@ void ModuleBitcodeWriter::writeModuleInfo() {
 
   // Emit the alias information.
   for (const GlobalAlias &A : M.aliases()) {
-    // ALIAS: [alias type, aliasee val#, linkage, visibility, dllstorageclass,
-    //         threadlocal, unnamed_addr]
+    // ALIAS: [strtab offset, strtab size, alias type, aliasee val#, linkage,
+    //         visibility, dllstorageclass, threadlocal, unnamed_addr]
+    Vals.push_back(addToStrtab(A.getName()));
+    Vals.push_back(A.getName().size());
     Vals.push_back(VE.getTypeID(A.getValueType()));
     Vals.push_back(A.getType()->getAddressSpace());
     Vals.push_back(VE.getValueID(A.getAliasee()));
@@ -1263,7 +1215,10 @@ void ModuleBitcodeWriter::writeModuleInfo() {
 
   // Emit the ifunc information.
   for (const GlobalIFunc &I : M.ifuncs()) {
-    // IFUNC: [ifunc type, address space, resolver val#, linkage, visibility]
+    // IFUNC: [strtab offset, strtab size, ifunc type, address space, resolver
+    //         val#, linkage, visibility]
+    Vals.push_back(addToStrtab(I.getName()));
+    Vals.push_back(I.getName().size());
     Vals.push_back(VE.getTypeID(I.getValueType()));
     Vals.push_back(I.getType()->getAddressSpace());
     Vals.push_back(VE.getValueID(I.getResolver()));
@@ -1273,34 +1228,6 @@ void ModuleBitcodeWriter::writeModuleInfo() {
     Vals.clear();
   }
 
-  // Emit the module's source file name.
-  {
-    StringEncoding Bits = getStringEncoding(M.getSourceFileName().data(),
-                                            M.getSourceFileName().size());
-    BitCodeAbbrevOp AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8);
-    if (Bits == SE_Char6)
-      AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Char6);
-    else if (Bits == SE_Fixed7)
-      AbbrevOpToUse = BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7);
-
-    // MODULE_CODE_SOURCE_FILENAME: [namechar x N]
-    auto Abbv = std::make_shared<BitCodeAbbrev>();
-    Abbv->Add(BitCodeAbbrevOp(bitc::MODULE_CODE_SOURCE_FILENAME));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
-    Abbv->Add(AbbrevOpToUse);
-    unsigned FilenameAbbrev = Stream.EmitAbbrev(std::move(Abbv));
-
-    for (const auto P : M.getSourceFileName())
-      Vals.push_back((unsigned char)P);
-
-    // Emit the finished record.
-    Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
-    Vals.clear();
-  }
-
-  // If we have a VST, write the VSTOFFSET record placeholder.
-  if (M.getValueSymbolTable().empty())
-    return;
   writeValueSymbolTableForwardDecl();
 }
 
@@ -1326,6 +1253,8 @@ static uint64_t getOptimizationFlags(const Value *V) {
       Flags |= FastMathFlags::NoSignedZeros;
     if (FPMO->hasAllowReciprocal())
       Flags |= FastMathFlags::AllowReciprocal;
+    if (FPMO->hasAllowContract())
+      Flags |= FastMathFlags::AllowContract;
   }
 
   return Flags;
@@ -1473,6 +1402,13 @@ void ModuleBitcodeWriter::writeDIDerivedType(const DIDerivedType *N,
   Record.push_back(N->getFlags());
   Record.push_back(VE.getMetadataOrNullID(N->getExtraData()));
 
+  // DWARF address space is encoded as N->getDWARFAddressSpace() + 1. 0 means
+  // that there is no DWARF address space associated with DIDerivedType.
+  if (const auto &DWARFAddressSpace = N->getDWARFAddressSpace())
+    Record.push_back(*DWARFAddressSpace + 1);
+  else
+    Record.push_back(0);
+
   Stream.EmitRecord(bitc::METADATA_DERIVED_TYPE, Record, Abbrev);
   Record.clear();
 }
@@ -1549,6 +1485,7 @@ void ModuleBitcodeWriter::writeDICompileUnit(const DICompileUnit *N,
   Record.push_back(N->getDWOId());
   Record.push_back(VE.getMetadataOrNullID(N->getMacros().get()));
   Record.push_back(N->getSplitDebugInlining());
+  Record.push_back(N->getDebugInfoForProfiling());
 
   Stream.EmitRecord(bitc::METADATA_COMPILE_UNIT, Record, Abbrev);
   Record.clear();
@@ -1578,6 +1515,7 @@ void ModuleBitcodeWriter::writeDISubprogram(const DISubprogram *N,
   Record.push_back(VE.getMetadataOrNullID(N->getDeclaration()));
   Record.push_back(VE.getMetadataOrNullID(N->getVariables().get()));
   Record.push_back(N->getThisAdjustment());
+  Record.push_back(VE.getMetadataOrNullID(N->getThrownTypes().get()));
 
   Stream.EmitRecord(bitc::METADATA_SUBPROGRAM, Record, Abbrev);
   Record.clear();
@@ -1613,9 +1551,7 @@ void ModuleBitcodeWriter::writeDINamespace(const DINamespace *N,
                                            unsigned Abbrev) {
   Record.push_back(N->isDistinct() | N->getExportSymbols() << 1);
   Record.push_back(VE.getMetadataOrNullID(N->getScope()));
-  Record.push_back(VE.getMetadataOrNullID(N->getFile()));
   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
-  Record.push_back(N->getLine());
 
   Stream.EmitRecord(bitc::METADATA_NAMESPACE, Record, Abbrev);
   Record.clear();
@@ -1738,9 +1674,8 @@ void ModuleBitcodeWriter::writeDIExpression(const DIExpression *N,
                                             SmallVectorImpl<uint64_t> &Record,
                                             unsigned Abbrev) {
   Record.reserve(N->getElements().size() + 1);
-
-  const uint64_t HasOpFragmentFlag = 1 << 1;
-  Record.push_back((uint64_t)N->isDistinct() | HasOpFragmentFlag);
+  const uint64_t Version = 3 << 1;
+  Record.push_back((uint64_t)N->isDistinct() | Version);
   Record.append(N->elements_begin(), N->elements_end());
 
   Stream.EmitRecord(bitc::METADATA_EXPRESSION, Record, Abbrev);
@@ -1783,6 +1718,7 @@ void ModuleBitcodeWriter::writeDIImportedEntity(
   Record.push_back(VE.getMetadataOrNullID(N->getEntity()));
   Record.push_back(N->getLine());
   Record.push_back(VE.getMetadataOrNullID(N->getRawName()));
+  Record.push_back(VE.getMetadataOrNullID(N->getRawFile()));
 
   Stream.EmitRecord(bitc::METADATA_IMPORTED_ENTITY, Record, Abbrev);
   Record.clear();
@@ -2104,6 +2040,24 @@ void ModuleBitcodeWriter::writeOperandBundleTags() {
   Stream.ExitBlock();
 }
 
+void ModuleBitcodeWriter::writeSyncScopeNames() {
+  SmallVector<StringRef, 8> SSNs;
+  M.getContext().getSyncScopeNames(SSNs);
+  if (SSNs.empty())
+    return;
+
+  Stream.EnterSubblock(bitc::SYNC_SCOPE_NAMES_BLOCK_ID, 2);
+
+  SmallVector<uint64_t, 64> Record;
+  for (auto SSN : SSNs) {
+    Record.append(SSN.begin(), SSN.end());
+    Stream.EmitRecord(bitc::SYNC_SCOPE_NAME, Record, 0);
+    Record.clear();
+  }
+
+  Stream.ExitBlock();
+}
+
 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
   if ((int64_t)V >= 0)
     Vals.push_back(V << 1);
@@ -2559,7 +2513,7 @@ void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
       Vals.push_back(VE.getTypeID(SI.getCondition()->getType()));
       pushValue(SI.getCondition(), InstID, Vals);
       Vals.push_back(VE.getValueID(SI.getDefaultDest()));
-      for (SwitchInst::ConstCaseIt Case : SI.cases()) {
+      for (auto Case : SI.cases()) {
         Vals.push_back(VE.getValueID(Case.getCaseValue()));
         Vals.push_back(VE.getValueID(Case.getCaseSuccessor()));
       }
@@ -2584,7 +2538,7 @@ void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
 
     Code = bitc::FUNC_CODE_INST_INVOKE;
 
-    Vals.push_back(VE.getAttributeID(II->getAttributes()));
+    Vals.push_back(VE.getAttributeListID(II->getAttributes()));
     Vals.push_back(II->getCallingConv() | 1 << 13);
     Vals.push_back(VE.getValueID(II->getNormalDest()));
     Vals.push_back(VE.getValueID(II->getUnwindDest()));
@@ -2720,7 +2674,7 @@ void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
     Vals.push_back(cast<LoadInst>(I).isVolatile());
     if (cast<LoadInst>(I).isAtomic()) {
       Vals.push_back(getEncodedOrdering(cast<LoadInst>(I).getOrdering()));
-      Vals.push_back(getEncodedSynchScope(cast<LoadInst>(I).getSynchScope()));
+      Vals.push_back(getEncodedSyncScopeID(cast<LoadInst>(I).getSyncScopeID()));
     }
     break;
   case Instruction::Store:
@@ -2734,7 +2688,8 @@ void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
     Vals.push_back(cast<StoreInst>(I).isVolatile());
     if (cast<StoreInst>(I).isAtomic()) {
       Vals.push_back(getEncodedOrdering(cast<StoreInst>(I).getOrdering()));
-      Vals.push_back(getEncodedSynchScope(cast<StoreInst>(I).getSynchScope()));
+      Vals.push_back(
+          getEncodedSyncScopeID(cast<StoreInst>(I).getSyncScopeID()));
     }
     break;
   case Instruction::AtomicCmpXchg:
@@ -2746,7 +2701,7 @@ void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
     Vals.push_back(
         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getSuccessOrdering()));
     Vals.push_back(
-        getEncodedSynchScope(cast<AtomicCmpXchgInst>(I).getSynchScope()));
+        getEncodedSyncScopeID(cast<AtomicCmpXchgInst>(I).getSyncScopeID()));
     Vals.push_back(
         getEncodedOrdering(cast<AtomicCmpXchgInst>(I).getFailureOrdering()));
     Vals.push_back(cast<AtomicCmpXchgInst>(I).isWeak());
@@ -2760,12 +2715,12 @@ void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
     Vals.push_back(cast<AtomicRMWInst>(I).isVolatile());
     Vals.push_back(getEncodedOrdering(cast<AtomicRMWInst>(I).getOrdering()));
     Vals.push_back(
-        getEncodedSynchScope(cast<AtomicRMWInst>(I).getSynchScope()));
+        getEncodedSyncScopeID(cast<AtomicRMWInst>(I).getSyncScopeID()));
     break;
   case Instruction::Fence:
     Code = bitc::FUNC_CODE_INST_FENCE;
     Vals.push_back(getEncodedOrdering(cast<FenceInst>(I).getOrdering()));
-    Vals.push_back(getEncodedSynchScope(cast<FenceInst>(I).getSynchScope()));
+    Vals.push_back(getEncodedSyncScopeID(cast<FenceInst>(I).getSyncScopeID()));
     break;
   case Instruction::Call: {
     const CallInst &CI = cast<CallInst>(I);
@@ -2776,7 +2731,7 @@ void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
 
     Code = bitc::FUNC_CODE_INST_CALL;
 
-    Vals.push_back(VE.getAttributeID(CI.getAttributes()));
+    Vals.push_back(VE.getAttributeListID(CI.getAttributes()));
 
     unsigned Flags = getOptimizationFlags(&I);
     Vals.push_back(CI.getCallingConv() << bitc::CALL_CCONV |
@@ -2820,77 +2775,59 @@ void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
   Vals.clear();
 }
 
-/// Emit names for globals/functions etc. \p IsModuleLevel is true when
-/// we are writing the module-level VST, where we are including a function
-/// bitcode index and need to backpatch the VST forward declaration record.
-void ModuleBitcodeWriter::writeValueSymbolTable(
-    const ValueSymbolTable &VST, bool IsModuleLevel,
-    DenseMap<const Function *, uint64_t> *FunctionToBitcodeIndex) {
-  if (VST.empty()) {
-    // writeValueSymbolTableForwardDecl should have returned early as
-    // well. Ensure this handling remains in sync by asserting that
-    // the placeholder offset is not set.
-    assert(!IsModuleLevel || !hasVSTOffsetPlaceholder());
-    return;
-  }
+/// Write a GlobalValue VST to the module. The purpose of this data structure is
+/// to allow clients to efficiently find the function body.
+void ModuleBitcodeWriter::writeGlobalValueSymbolTable(
+  DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex) {
+  // Get the offset of the VST we are writing, and backpatch it into
+  // the VST forward declaration record.
+  uint64_t VSTOffset = Stream.GetCurrentBitNo();
+  // The BitcodeStartBit was the stream offset of the identification block.
+  VSTOffset -= bitcodeStartBit();
+  assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
+  // Note that we add 1 here because the offset is relative to one word
+  // before the start of the identification block, which was historically
+  // always the start of the regular bitcode header.
+  Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32 + 1);
+
+  Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
+
+  auto Abbv = std::make_shared<BitCodeAbbrev>();
+  Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
+  unsigned FnEntryAbbrev = Stream.EmitAbbrev(std::move(Abbv));
+
+  for (const Function &F : M) {
+    uint64_t Record[2];
 
-  if (IsModuleLevel && hasVSTOffsetPlaceholder()) {
-    // Get the offset of the VST we are writing, and backpatch it into
-    // the VST forward declaration record.
-    uint64_t VSTOffset = Stream.GetCurrentBitNo();
-    // The BitcodeStartBit was the stream offset of the identification block.
-    VSTOffset -= bitcodeStartBit();
-    assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
+    if (F.isDeclaration())
+      continue;
+
+    Record[0] = VE.getValueID(&F);
+
+    // Save the word offset of the function (from the start of the
+    // actual bitcode written to the stream).
+    uint64_t BitcodeIndex = FunctionToBitcodeIndex[&F] - bitcodeStartBit();
+    assert((BitcodeIndex & 31) == 0 && "function block not 32-bit aligned");
     // Note that we add 1 here because the offset is relative to one word
     // before the start of the identification block, which was historically
     // always the start of the regular bitcode header.
-    Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32 + 1);
-  }
-
-  Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
+    Record[1] = BitcodeIndex / 32 + 1;
 
-  // For the module-level VST, add abbrev Ids for the VST_CODE_FNENTRY
-  // records, which are not used in the per-function VSTs.
-  unsigned FnEntry8BitAbbrev;
-  unsigned FnEntry7BitAbbrev;
-  unsigned FnEntry6BitAbbrev;
-  unsigned GUIDEntryAbbrev;
-  if (IsModuleLevel && hasVSTOffsetPlaceholder()) {
-    // 8-bit fixed-width VST_CODE_FNENTRY function strings.
-    auto Abbv = std::make_shared<BitCodeAbbrev>();
-    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
-    FnEntry8BitAbbrev = Stream.EmitAbbrev(std::move(Abbv));
+    Stream.EmitRecord(bitc::VST_CODE_FNENTRY, Record, FnEntryAbbrev);
+  }
 
-    // 7-bit fixed width VST_CODE_FNENTRY function strings.
-    Abbv = std::make_shared<BitCodeAbbrev>();
-    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
-    FnEntry7BitAbbrev = Stream.EmitAbbrev(std::move(Abbv));
+  Stream.ExitBlock();
+}
 
-    // 6-bit char6 VST_CODE_FNENTRY function strings.
-    Abbv = std::make_shared<BitCodeAbbrev>();
-    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_FNENTRY));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // value id
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // funcoffset
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
-    FnEntry6BitAbbrev = Stream.EmitAbbrev(std::move(Abbv));
+/// Emit names for arguments, instructions and basic blocks in a function.
+void ModuleBitcodeWriter::writeFunctionLevelValueSymbolTable(
+    const ValueSymbolTable &VST) {
+  if (VST.empty())
+    return;
 
-    // FIXME: Change the name of this record as it is now used by
-    // the per-module index as well.
-    Abbv = std::make_shared<BitCodeAbbrev>();
-    Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_COMBINED_ENTRY));
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
-    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // refguid
-    GUIDEntryAbbrev = Stream.EmitAbbrev(std::move(Abbv));
-  }
+  Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
 
   // FIXME: Set up the abbrev, we know how many values there are!
   // FIXME: We know if the type names can use 7-bit ascii.
@@ -2898,51 +2835,18 @@ void ModuleBitcodeWriter::writeValueSymbolTable(
 
   for (const ValueName &Name : VST) {
     // Figure out the encoding to use for the name.
-    StringEncoding Bits =
-        getStringEncoding(Name.getKeyData(), Name.getKeyLength());
+    StringEncoding Bits = getStringEncoding(Name.getKey());
 
     unsigned AbbrevToUse = VST_ENTRY_8_ABBREV;
     NameVals.push_back(VE.getValueID(Name.getValue()));
 
-    Function *F = dyn_cast<Function>(Name.getValue());
-    if (!F) {
-      // If value is an alias, need to get the aliased base object to
-      // see if it is a function.
-      auto *GA = dyn_cast<GlobalAlias>(Name.getValue());
-      if (GA && GA->getBaseObject())
-        F = dyn_cast<Function>(GA->getBaseObject());
-    }
-
     // VST_CODE_ENTRY:   [valueid, namechar x N]
-    // VST_CODE_FNENTRY: [valueid, funcoffset, namechar x N]
     // VST_CODE_BBENTRY: [bbid, namechar x N]
     unsigned Code;
     if (isa<BasicBlock>(Name.getValue())) {
       Code = bitc::VST_CODE_BBENTRY;
       if (Bits == SE_Char6)
         AbbrevToUse = VST_BBENTRY_6_ABBREV;
-    } else if (F && !F->isDeclaration()) {
-      // Must be the module-level VST, where we pass in the Index and
-      // have a VSTOffsetPlaceholder. The function-level VST should not
-      // contain any Function symbols.
-      assert(FunctionToBitcodeIndex);
-      assert(hasVSTOffsetPlaceholder());
-
-      // Save the word offset of the function (from the start of the
-      // actual bitcode written to the stream).
-      uint64_t BitcodeIndex = (*FunctionToBitcodeIndex)[F] - bitcodeStartBit();
-      assert((BitcodeIndex & 31) == 0 && "function block not 32-bit aligned");
-      // Note that we add 1 here because the offset is relative to one word
-      // before the start of the identification block, which was historically
-      // always the start of the regular bitcode header.
-      NameVals.push_back(BitcodeIndex / 32 + 1);
-
-      Code = bitc::VST_CODE_FNENTRY;
-      AbbrevToUse = FnEntry8BitAbbrev;
-      if (Bits == SE_Char6)
-        AbbrevToUse = FnEntry6BitAbbrev;
-      else if (Bits == SE_Fixed7)
-        AbbrevToUse = FnEntry7BitAbbrev;
     } else {
       Code = bitc::VST_CODE_ENTRY;
       if (Bits == SE_Char6)
@@ -2958,47 +2862,7 @@ void ModuleBitcodeWriter::writeValueSymbolTable(
     Stream.EmitRecord(Code, NameVals, AbbrevToUse);
     NameVals.clear();
   }
-  // Emit any GUID valueIDs created for indirect call edges into the
-  // module-level VST.
-  if (IsModuleLevel && hasVSTOffsetPlaceholder())
-    for (const auto &GI : valueIds()) {
-      NameVals.push_back(GI.second);
-      NameVals.push_back(GI.first);
-      Stream.EmitRecord(bitc::VST_CODE_COMBINED_ENTRY, NameVals,
-                        GUIDEntryAbbrev);
-      NameVals.clear();
-    }
-  Stream.ExitBlock();
-}
-
-/// Emit function names and summary offsets for the combined index
-/// used by ThinLTO.
-void IndexBitcodeWriter::writeCombinedValueSymbolTable() {
-  assert(hasVSTOffsetPlaceholder() && "Expected non-zero VSTOffsetPlaceholder");
-  // Get the offset of the VST we are writing, and backpatch it into
-  // the VST forward declaration record.
-  uint64_t VSTOffset = Stream.GetCurrentBitNo();
-  assert((VSTOffset & 31) == 0 && "VST block not 32-bit aligned");
-  Stream.BackpatchWord(VSTOffsetPlaceholder, VSTOffset / 32);
 
-  Stream.EnterSubblock(bitc::VALUE_SYMTAB_BLOCK_ID, 4);
-
-  auto Abbv = std::make_shared<BitCodeAbbrev>();
-  Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_COMBINED_ENTRY));
-  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // valueid
-  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // refguid
-  unsigned EntryAbbrev = Stream.EmitAbbrev(std::move(Abbv));
-
-  SmallVector<uint64_t, 64> NameVals;
-  for (const auto &GVI : valueIds()) {
-    // VST_CODE_COMBINED_ENTRY: [valueid, refguid]
-    NameVals.push_back(GVI.second);
-    NameVals.push_back(GVI.first);
-
-    // Emit the finished record.
-    Stream.EmitRecord(bitc::VST_CODE_COMBINED_ENTRY, NameVals, EntryAbbrev);
-    NameVals.clear();
-  }
   Stream.ExitBlock();
 }
 
@@ -3102,7 +2966,7 @@ void ModuleBitcodeWriter::writeFunction(
 
   // Emit names for all the instructions etc.
   if (auto *Symtab = F.getValueSymbolTable())
-    writeValueSymbolTable(*Symtab);
+    writeFunctionLevelValueSymbolTable(*Symtab);
 
   if (NeedsMetadataAttachment)
     writeFunctionMetadataAttachment(F);
@@ -3329,42 +3193,77 @@ void IndexBitcodeWriter::writeModStrings() {
   unsigned AbbrevHash = Stream.EmitAbbrev(std::move(Abbv));
 
   SmallVector<unsigned, 64> Vals;
-  for (const auto &MPSE : Index.modulePaths()) {
-    if (!doIncludeModule(MPSE.getKey()))
-      continue;
-    StringEncoding Bits =
-        getStringEncoding(MPSE.getKey().data(), MPSE.getKey().size());
-    unsigned AbbrevToUse = Abbrev8Bit;
-    if (Bits == SE_Char6)
-      AbbrevToUse = Abbrev6Bit;
-    else if (Bits == SE_Fixed7)
-      AbbrevToUse = Abbrev7Bit;
+  forEachModule(
+      [&](const StringMapEntry<std::pair<uint64_t, ModuleHash>> &MPSE) {
+        StringRef Key = MPSE.getKey();
+        const auto &Value = MPSE.getValue();
+        StringEncoding Bits = getStringEncoding(Key);
+        unsigned AbbrevToUse = Abbrev8Bit;
+        if (Bits == SE_Char6)
+          AbbrevToUse = Abbrev6Bit;
+        else if (Bits == SE_Fixed7)
+          AbbrevToUse = Abbrev7Bit;
+
+        Vals.push_back(Value.first);
+        Vals.append(Key.begin(), Key.end());
+
+        // Emit the finished record.
+        Stream.EmitRecord(bitc::MST_CODE_ENTRY, Vals, AbbrevToUse);
+
+        // Emit an optional hash for the module now
+        const auto &Hash = Value.second;
+        if (llvm::any_of(Hash, [](uint32_t H) { return H; })) {
+          Vals.assign(Hash.begin(), Hash.end());
+          // Emit the hash record.
+          Stream.EmitRecord(bitc::MST_CODE_HASH, Vals, AbbrevHash);
+        }
 
-    Vals.push_back(MPSE.getValue().first);
+        Vals.clear();
+      });
+  Stream.ExitBlock();
+}
 
-    for (const auto P : MPSE.getKey())
-      Vals.push_back((unsigned char)P);
+/// Write the function type metadata related records that need to appear before
+/// a function summary entry (whether per-module or combined).
+static void writeFunctionTypeMetadataRecords(BitstreamWriter &Stream,
+                                             FunctionSummary *FS) {
+  if (!FS->type_tests().empty())
+    Stream.EmitRecord(bitc::FS_TYPE_TESTS, FS->type_tests());
 
-    // Emit the finished record.
-    Stream.EmitRecord(bitc::MST_CODE_ENTRY, Vals, AbbrevToUse);
+  SmallVector<uint64_t, 64> Record;
 
-    Vals.clear();
-    // Emit an optional hash for the module now
-    auto &Hash = MPSE.getValue().second;
-    bool AllZero = true; // Detect if the hash is empty, and do not generate it
-    for (auto Val : Hash) {
-      if (Val)
-        AllZero = false;
-      Vals.push_back(Val);
+  auto WriteVFuncIdVec = [&](uint64_t Ty,
+                             ArrayRef<FunctionSummary::VFuncId> VFs) {
+    if (VFs.empty())
+      return;
+    Record.clear();
+    for (auto &VF : VFs) {
+      Record.push_back(VF.GUID);
+      Record.push_back(VF.Offset);
     }
-    if (!AllZero) {
-      // Emit the hash record.
-      Stream.EmitRecord(bitc::MST_CODE_HASH, Vals, AbbrevHash);
+    Stream.EmitRecord(Ty, Record);
+  };
+
+  WriteVFuncIdVec(bitc::FS_TYPE_TEST_ASSUME_VCALLS,
+                  FS->type_test_assume_vcalls());
+  WriteVFuncIdVec(bitc::FS_TYPE_CHECKED_LOAD_VCALLS,
+                  FS->type_checked_load_vcalls());
+
+  auto WriteConstVCallVec = [&](uint64_t Ty,
+                                ArrayRef<FunctionSummary::ConstVCall> VCs) {
+    for (auto &VC : VCs) {
+      Record.clear();
+      Record.push_back(VC.VFunc.GUID);
+      Record.push_back(VC.VFunc.Offset);
+      Record.insert(Record.end(), VC.Args.begin(), VC.Args.end());
+      Stream.EmitRecord(Ty, Record);
     }
+  };
 
-    Vals.clear();
-  }
-  Stream.ExitBlock();
+  WriteConstVCallVec(bitc::FS_TYPE_TEST_ASSUME_CONST_VCALL,
+                     FS->type_test_assume_const_vcalls());
+  WriteConstVCallVec(bitc::FS_TYPE_CHECKED_LOAD_CONST_VCALL,
+                     FS->type_checked_load_const_vcalls());
 }
 
 // Helper to emit a single function summary record.
@@ -3375,8 +3274,7 @@ void ModuleBitcodeWriter::writePerModuleFunctionSummaryRecord(
   NameVals.push_back(ValueID);
 
   FunctionSummary *FS = cast<FunctionSummary>(Summary);
-  if (!FS->type_tests().empty())
-    Stream.EmitRecord(bitc::FS_TYPE_TESTS, FS->type_tests());
+  writeFunctionTypeMetadataRecords(Stream, FS);
 
   NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
   NameVals.push_back(FS->instCount());
@@ -3406,15 +3304,14 @@ void ModuleBitcodeWriter::writePerModuleFunctionSummaryRecord(
 void ModuleBitcodeWriter::writeModuleLevelReferences(
     const GlobalVariable &V, SmallVector<uint64_t, 64> &NameVals,
     unsigned FSModRefsAbbrev) {
-  auto Summaries =
-      Index->findGlobalValueSummaryList(GlobalValue::getGUID(V.getName()));
-  if (Summaries == Index->end()) {
+  auto VI = Index->getValueInfo(GlobalValue::getGUID(V.getName()));
+  if (!VI || VI.getSummaryList().empty()) {
     // Only declarations should not have a summary (a declaration might however
     // have a summary if the def was in module level asm).
     assert(V.isDeclaration());
     return;
   }
-  auto *Summary = Summaries->second.front().get();
+  auto *Summary = VI.getSummaryList()[0].get();
   NameVals.push_back(VE.getValueID(&V));
   GlobalVarSummary *VS = cast<GlobalVarSummary>(Summary);
   NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
@@ -3439,7 +3336,15 @@ static const uint64_t INDEX_VERSION = 3;
 /// Emit the per-module summary section alongside the rest of
 /// the module's bitcode.
 void ModuleBitcodeWriter::writePerModuleGlobalValueSummary() {
-  Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 4);
+  // By default we compile with ThinLTO if the module has a summary, but the
+  // client can request full LTO with a module flag.
+  bool IsThinLTO = true;
+  if (auto *MD =
+          mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("ThinLTO")))
+    IsThinLTO = MD->getZExtValue();
+  Stream.EnterSubblock(IsThinLTO ? bitc::GLOBALVAL_SUMMARY_BLOCK_ID
+                                 : bitc::FULL_LTO_GLOBALVAL_SUMMARY_BLOCK_ID,
+                       4);
 
   Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
 
@@ -3448,6 +3353,11 @@ void ModuleBitcodeWriter::writePerModuleGlobalValueSummary() {
     return;
   }
 
+  for (const auto &GVI : valueIds()) {
+    Stream.EmitRecord(bitc::FS_VALUE_GUID,
+                      ArrayRef<uint64_t>{GVI.second, GVI.first});
+  }
+
   // Abbrev for FS_PERMODULE.
   auto Abbv = std::make_shared<BitCodeAbbrev>();
   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE));
@@ -3498,15 +3408,14 @@ void ModuleBitcodeWriter::writePerModuleGlobalValueSummary() {
     if (!F.hasName())
       report_fatal_error("Unexpected anonymous function when writing summary");
 
-    auto Summaries =
-        Index->findGlobalValueSummaryList(GlobalValue::getGUID(F.getName()));
-    if (Summaries == Index->end()) {
+    ValueInfo VI = Index->getValueInfo(GlobalValue::getGUID(F.getName()));
+    if (!VI || VI.getSummaryList().empty()) {
       // Only declarations should not have a summary (a declaration might
       // however have a summary if the def was in module level asm).
       assert(F.isDeclaration());
       continue;
     }
-    auto *Summary = Summaries->second.front().get();
+    auto *Summary = VI.getSummaryList()[0].get();
     writePerModuleFunctionSummaryRecord(NameVals, Summary, VE.getValueID(&F),
                                         FSCallsAbbrev, FSCallsProfileAbbrev, F);
   }
@@ -3540,6 +3449,11 @@ void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
   Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
 
+  for (const auto &GVI : valueIds()) {
+    Stream.EmitRecord(bitc::FS_VALUE_GUID,
+                      ArrayRef<uint64_t>{GVI.second, GVI.first});
+  }
+
   // Abbrev for FS_COMBINED.
   auto Abbv = std::make_shared<BitCodeAbbrev>();
   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED));
@@ -3604,27 +3518,30 @@ void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
     NameVals.clear();
   };
 
-  for (const auto &I : *this) {
+  forEachSummary([&](GVInfo I) {
     GlobalValueSummary *S = I.second;
     assert(S);
 
-    assert(hasValueId(I.first));
-    unsigned ValueId = getValueId(I.first);
-    SummaryToValueIdMap[S] = ValueId;
+    auto ValueId = getValueId(I.first);
+    assert(ValueId);
+    SummaryToValueIdMap[S] = *ValueId;
 
     if (auto *AS = dyn_cast<AliasSummary>(S)) {
       // Will process aliases as a post-pass because the reader wants all
       // global to be loaded first.
       Aliases.push_back(AS);
-      continue;
+      return;
     }
 
     if (auto *VS = dyn_cast<GlobalVarSummary>(S)) {
-      NameVals.push_back(ValueId);
+      NameVals.push_back(*ValueId);
       NameVals.push_back(Index.getModuleId(VS->modulePath()));
       NameVals.push_back(getEncodedGVSummaryFlags(VS->flags()));
       for (auto &RI : VS->refs()) {
-        NameVals.push_back(getValueId(RI.getGUID()));
+        auto RefValueId = getValueId(RI.getGUID());
+        if (!RefValueId)
+          continue;
+        NameVals.push_back(*RefValueId);
       }
 
       // Emit the finished record.
@@ -3632,22 +3549,28 @@ void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
                         FSModRefsAbbrev);
       NameVals.clear();
       MaybeEmitOriginalName(*S);
-      continue;
+      return;
     }
 
     auto *FS = cast<FunctionSummary>(S);
-    if (!FS->type_tests().empty())
-      Stream.EmitRecord(bitc::FS_TYPE_TESTS, FS->type_tests());
+    writeFunctionTypeMetadataRecords(Stream, FS);
 
-    NameVals.push_back(ValueId);
+    NameVals.push_back(*ValueId);
     NameVals.push_back(Index.getModuleId(FS->modulePath()));
     NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
     NameVals.push_back(FS->instCount());
-    NameVals.push_back(FS->refs().size());
+    // Fill in below
+    NameVals.push_back(0);
 
+    unsigned Count = 0;
     for (auto &RI : FS->refs()) {
-      NameVals.push_back(getValueId(RI.getGUID()));
+      auto RefValueId = getValueId(RI.getGUID());
+      if (!RefValueId)
+        continue;
+      NameVals.push_back(*RefValueId);
+      Count++;
     }
+    NameVals[4] = Count;
 
     bool HasProfileData = false;
     for (auto &EI : FS->calls()) {
@@ -3659,9 +3582,20 @@ void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
     for (auto &EI : FS->calls()) {
       // If this GUID doesn't have a value id, it doesn't have a function
       // summary and we don't need to record any calls to it.
-      if (!hasValueId(EI.first.getGUID()))
-        continue;
-      NameVals.push_back(getValueId(EI.first.getGUID()));
+      GlobalValue::GUID GUID = EI.first.getGUID();
+      auto CallValueId = getValueId(GUID);
+      if (!CallValueId) {
+        // For SamplePGO, the indirect call targets for local functions will
+        // have its original name annotated in profile. We try to find the
+        // corresponding PGOFuncName as the GUID.
+        GUID = Index.getGUIDFromOriginalID(GUID);
+        if (GUID == 0)
+          continue;
+        CallValueId = getValueId(GUID);
+        if (!CallValueId)
+          continue;
+      }
+      NameVals.push_back(*CallValueId);
       if (HasProfileData)
         NameVals.push_back(static_cast<uint8_t>(EI.second.Hotness));
     }
@@ -3674,7 +3608,7 @@ void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
     Stream.EmitRecord(Code, NameVals, FSAbbrev);
     NameVals.clear();
     MaybeEmitOriginalName(*S);
-  }
+  });
 
   for (auto *AS : Aliases) {
     auto AliasValueId = SummaryToValueIdMap[AS];
@@ -3692,12 +3626,30 @@ void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
     MaybeEmitOriginalName(*AS);
   }
 
+  if (!Index.cfiFunctionDefs().empty()) {
+    for (auto &S : Index.cfiFunctionDefs()) {
+      NameVals.push_back(StrtabBuilder.add(S));
+      NameVals.push_back(S.size());
+    }
+    Stream.EmitRecord(bitc::FS_CFI_FUNCTION_DEFS, NameVals);
+    NameVals.clear();
+  }
+
+  if (!Index.cfiFunctionDecls().empty()) {
+    for (auto &S : Index.cfiFunctionDecls()) {
+      NameVals.push_back(StrtabBuilder.add(S));
+      NameVals.push_back(S.size());
+    }
+    Stream.EmitRecord(bitc::FS_CFI_FUNCTION_DECLS, NameVals);
+    NameVals.clear();
+  }
+
   Stream.ExitBlock();
 }
 
 /// Create the "IDENTIFICATION_BLOCK_ID" containing a single string with the
 /// current llvm version, and a record for the epoch number.
-void writeIdentificationBlock(BitstreamWriter &Stream) {
+static void writeIdentificationBlock(BitstreamWriter &Stream) {
   Stream.EnterSubblock(bitc::IDENTIFICATION_BLOCK_ID, 5);
 
   // Write the "user readable" string identifying the bitcode producer
@@ -3722,17 +3674,23 @@ void writeIdentificationBlock(BitstreamWriter &Stream) {
 void ModuleBitcodeWriter::writeModuleHash(size_t BlockStartPos) {
   // Emit the module's hash.
   // MODULE_CODE_HASH: [5*i32]
-  SHA1 Hasher;
-  Hasher.update(ArrayRef<uint8_t>((const uint8_t *)&(Buffer)[BlockStartPos],
-                                  Buffer.size() - BlockStartPos));
-  StringRef Hash = Hasher.result();
-  uint32_t Vals[5];
-  for (int Pos = 0; Pos < 20; Pos += 4) {
-    Vals[Pos / 4] = support::endian::read32be(Hash.data() + Pos);
-  }
+  if (GenerateHash) {
+    uint32_t Vals[5];
+    Hasher.update(ArrayRef<uint8_t>((const uint8_t *)&(Buffer)[BlockStartPos],
+                                    Buffer.size() - BlockStartPos));
+    StringRef Hash = Hasher.result();
+    for (int Pos = 0; Pos < 20; Pos += 4) {
+      Vals[Pos / 4] = support::endian::read32be(Hash.data() + Pos);
+    }
 
-  // Emit the finished record.
-  Stream.EmitRecord(bitc::MODULE_CODE_HASH, Vals);
+    // Emit the finished record.
+    Stream.EmitRecord(bitc::MODULE_CODE_HASH, Vals);
+
+    if (ModHash)
+      // Save the written hash value.
+      std::copy(std::begin(Vals), std::end(Vals), std::begin(*ModHash));
+  } else if (ModHash)
+    Stream.EmitRecord(bitc::MODULE_CODE_HASH, ArrayRef<uint32_t>(*ModHash));
 }
 
 void ModuleBitcodeWriter::write() {
@@ -3741,10 +3699,7 @@ void ModuleBitcodeWriter::write() {
   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
   size_t BlockStartPos = Buffer.size();
 
-  SmallVector<unsigned, 1> Vals;
-  unsigned CurVersion = 1;
-  Vals.push_back(CurVersion);
-  Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
+  writeModuleVersion();
 
   // Emit blockinfo, which defines the standard abbreviations etc.
   writeBlockInfo();
@@ -3778,6 +3733,7 @@ void ModuleBitcodeWriter::write() {
     writeUseListBlock(nullptr);
 
   writeOperandBundleTags();
+  writeSyncScopeNames();
 
   // Emit function bodies.
   DenseMap<const Function *, uint64_t> FunctionToBitcodeIndex;
@@ -3790,12 +3746,9 @@ void ModuleBitcodeWriter::write() {
   if (Index)
     writePerModuleGlobalValueSummary();
 
-  writeValueSymbolTable(M.getValueSymbolTable(),
-                        /* IsModuleLevel */ true, &FunctionToBitcodeIndex);
+  writeGlobalValueSymbolTable(FunctionToBitcodeIndex);
 
-  if (GenerateHash) {
-    writeModuleHash(BlockStartPos);
-  }
+  writeModuleHash(BlockStartPos);
 
   Stream.ExitBlock();
 }
@@ -3881,23 +3834,105 @@ BitcodeWriter::BitcodeWriter(SmallVectorImpl<char> &Buffer)
   writeBitcodeHeader(*Stream);
 }
 
-BitcodeWriter::~BitcodeWriter() = default;
+BitcodeWriter::~BitcodeWriter() { assert(WroteStrtab); }
+
+void BitcodeWriter::writeBlob(unsigned Block, unsigned Record, StringRef Blob) {
+  Stream->EnterSubblock(Block, 3);
+
+  auto Abbv = std::make_shared<BitCodeAbbrev>();
+  Abbv->Add(BitCodeAbbrevOp(Record));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
+  auto AbbrevNo = Stream->EmitAbbrev(std::move(Abbv));
+
+  Stream->EmitRecordWithBlob(AbbrevNo, ArrayRef<uint64_t>{Record}, Blob);
+
+  Stream->ExitBlock();
+}
+
+void BitcodeWriter::writeSymtab() {
+  assert(!WroteStrtab && !WroteSymtab);
+
+  // If any module has module-level inline asm, we will require a registered asm
+  // parser for the target so that we can create an accurate symbol table for
+  // the module.
+  for (Module *M : Mods) {
+    if (M->getModuleInlineAsm().empty())
+      continue;
+
+    std::string Err;
+    const Triple TT(M->getTargetTriple());
+    const Target *T = TargetRegistry::lookupTarget(TT.str(), Err);
+    if (!T || !T->hasMCAsmParser())
+      return;
+  }
+
+  WroteSymtab = true;
+  SmallVector<char, 0> Symtab;
+  // The irsymtab::build function may be unable to create a symbol table if the
+  // module is malformed (e.g. it contains an invalid alias). Writing a symbol
+  // table is not required for correctness, but we still want to be able to
+  // write malformed modules to bitcode files, so swallow the error.
+  if (Error E = irsymtab::build(Mods, Symtab, StrtabBuilder, Alloc)) {
+    consumeError(std::move(E));
+    return;
+  }
+
+  writeBlob(bitc::SYMTAB_BLOCK_ID, bitc::SYMTAB_BLOB,
+            {Symtab.data(), Symtab.size()});
+}
+
+void BitcodeWriter::writeStrtab() {
+  assert(!WroteStrtab);
+
+  std::vector<char> Strtab;
+  StrtabBuilder.finalizeInOrder();
+  Strtab.resize(StrtabBuilder.getSize());
+  StrtabBuilder.write((uint8_t *)Strtab.data());
+
+  writeBlob(bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB,
+            {Strtab.data(), Strtab.size()});
+
+  WroteStrtab = true;
+}
+
+void BitcodeWriter::copyStrtab(StringRef Strtab) {
+  writeBlob(bitc::STRTAB_BLOCK_ID, bitc::STRTAB_BLOB, Strtab);
+  WroteStrtab = true;
+}
 
 void BitcodeWriter::writeModule(const Module *M,
                                 bool ShouldPreserveUseListOrder,
                                 const ModuleSummaryIndex *Index,
-                                bool GenerateHash) {
-  ModuleBitcodeWriter ModuleWriter(
-      M, Buffer, *Stream, ShouldPreserveUseListOrder, Index, GenerateHash);
+                                bool GenerateHash, ModuleHash *ModHash) {
+  assert(!WroteStrtab);
+
+  // The Mods vector is used by irsymtab::build, which requires non-const
+  // Modules in case it needs to materialize metadata. But the bitcode writer
+  // requires that the module is materialized, so we can cast to non-const here,
+  // after checking that it is in fact materialized.
+  assert(M->isMaterialized());
+  Mods.push_back(const_cast<Module *>(M));
+
+  ModuleBitcodeWriter ModuleWriter(M, Buffer, StrtabBuilder, *Stream,
+                                   ShouldPreserveUseListOrder, Index,
+                                   GenerateHash, ModHash);
   ModuleWriter.write();
 }
 
+void BitcodeWriter::writeIndex(
+    const ModuleSummaryIndex *Index,
+    const std::map<std::string, GVSummaryMapTy> *ModuleToSummariesForIndex) {
+  IndexBitcodeWriter IndexWriter(*Stream, StrtabBuilder, *Index,
+                                 ModuleToSummariesForIndex);
+  IndexWriter.write();
+}
+
 /// WriteBitcodeToFile - Write the specified module to the specified output
 /// stream.
 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out,
                               bool ShouldPreserveUseListOrder,
                               const ModuleSummaryIndex *Index,
-                              bool GenerateHash) {
+                              bool GenerateHash, ModuleHash *ModHash) {
   SmallVector<char, 0> Buffer;
   Buffer.reserve(256*1024);
 
@@ -3908,7 +3943,10 @@ void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out,
     Buffer.insert(Buffer.begin(), BWH_HeaderSize, 0);
 
   BitcodeWriter Writer(Buffer);
-  Writer.writeModule(M, ShouldPreserveUseListOrder, Index, GenerateHash);
+  Writer.writeModule(M, ShouldPreserveUseListOrder, Index, GenerateHash,
+                     ModHash);
+  Writer.writeSymtab();
+  Writer.writeStrtab();
 
   if (TT.isOSDarwin() || TT.isOSBinFormatMachO())
     emitDarwinBCHeaderAndTrailer(Buffer, TT);
@@ -3920,13 +3958,7 @@ void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out,
 void IndexBitcodeWriter::write() {
   Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
 
-  SmallVector<unsigned, 1> Vals;
-  unsigned CurVersion = 1;
-  Vals.push_back(CurVersion);
-  Stream.EmitRecord(bitc::MODULE_CODE_VERSION, Vals);
-
-  // If we have a VST, write the VSTOFFSET record placeholder.
-  writeValueSymbolTableForwardDecl();
+  writeModuleVersion();
 
   // Write the module paths in the combined index.
   writeModStrings();
@@ -3934,10 +3966,6 @@ void IndexBitcodeWriter::write() {
   // Write the summary combined index records.
   writeCombinedGlobalValueSummary();
 
-  // Need a special VST writer for the combined index (we don't have a
-  // real VST and real values when this is invoked).
-  writeCombinedValueSymbolTable();
-
   Stream.ExitBlock();
 }
 
@@ -3951,11 +3979,9 @@ void llvm::WriteIndexToFile(
   SmallVector<char, 0> Buffer;
   Buffer.reserve(256 * 1024);
 
-  BitstreamWriter Stream(Buffer);
-  writeBitcodeHeader(Stream);
-
-  IndexBitcodeWriter IndexWriter(Stream, Index, ModuleToSummariesForIndex);
-  IndexWriter.write();
+  BitcodeWriter Writer(Buffer);
+  Writer.writeIndex(&Index, ModuleToSummariesForIndex);
+  Writer.writeStrtab();
 
   Out.write((char *)&Buffer.front(), Buffer.size());
 }
diff --git a/contrib/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp b/contrib/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp
index 5d5bfab..bb626ba 100644
--- a/contrib/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp
+++ b/contrib/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp
@@ -314,10 +314,13 @@ ValueEnumerator::ValueEnumerator(const Module &M,
   // Remember what is the cutoff between globalvalue's and other constants.
   unsigned FirstConstant = Values.size();
 
-  // Enumerate the global variable initializers.
-  for (const GlobalVariable &GV : M.globals())
+  // Enumerate the global variable initializers and attributes.
+  for (const GlobalVariable &GV : M.globals()) {
     if (GV.hasInitializer())
       EnumerateValue(GV.getInitializer());
+    if (GV.hasAttributes())
+      EnumerateAttributes(GV.getAttributesAsList(AttributeList::FunctionIndex));
+  }
 
   // Enumerate the aliasees.
   for (const GlobalAlias &GA : M.aliases())
@@ -432,12 +435,14 @@ unsigned ValueEnumerator::getValueID(const Value *V) const {
   return I->second-1;
 }
 
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
 LLVM_DUMP_METHOD void ValueEnumerator::dump() const {
   print(dbgs(), ValueMap, "Default");
   dbgs() << '\n';
   print(dbgs(), MetadataMap, "MetaData");
   dbgs() << '\n';
 }
+#endif
 
 void ValueEnumerator::print(raw_ostream &OS, const ValueMapType &Map,
                             const char *Name) const {
@@ -452,7 +457,8 @@ void ValueEnumerator::print(raw_ostream &OS, const ValueMapType &Map,
       OS << "Value: " << V->getName();
     else
       OS << "Value: [null]\n";
-    V->dump();
+    V->print(errs());
+    errs() << '\n';
 
     OS << " Uses(" << std::distance(V->use_begin(),V->use_end()) << "):";
     for (const Use &U : V->uses()) {
@@ -549,7 +555,7 @@ void ValueEnumerator::EnumerateFunctionLocalMetadata(
 void ValueEnumerator::dropFunctionFromMetadata(
     MetadataMapType::value_type &FirstMD) {
   SmallVector<const MDNode *, 64> Worklist;
-  auto push = [this, &Worklist](MetadataMapType::value_type &MD) {
+  auto push = [&Worklist](MetadataMapType::value_type &MD) {
     auto &Entry = MD.second;
 
     // Nothing to do if this metadata isn't tagged.
@@ -884,23 +890,26 @@ void ValueEnumerator::EnumerateOperandType(const Value *V) {
   }
 }
 
-void ValueEnumerator::EnumerateAttributes(AttributeSet PAL) {
+void ValueEnumerator::EnumerateAttributes(AttributeList PAL) {
   if (PAL.isEmpty()) return;  // null is always 0.
 
   // Do a lookup.
-  unsigned &Entry = AttributeMap[PAL];
+  unsigned &Entry = AttributeListMap[PAL];
   if (Entry == 0) {
     // Never saw this before, add it.
-    Attribute.push_back(PAL);
-    Entry = Attribute.size();
+    AttributeLists.push_back(PAL);
+    Entry = AttributeLists.size();
   }
 
   // Do lookups for all attribute groups.
-  for (unsigned i = 0, e = PAL.getNumSlots(); i != e; ++i) {
-    AttributeSet AS = PAL.getSlotAttributes(i);
-    unsigned &Entry = AttributeGroupMap[AS];
+  for (unsigned i = PAL.index_begin(), e = PAL.index_end(); i != e; ++i) {
+    AttributeSet AS = PAL.getAttributes(i);
+    if (!AS.hasAttributes())
+      continue;
+    IndexAndAttrSet Pair = {i, AS};
+    unsigned &Entry = AttributeGroupMap[Pair];
     if (Entry == 0) {
-      AttributeGroups.push_back(AS);
+      AttributeGroups.push_back(Pair);
       Entry = AttributeGroups.size();
     }
   }
diff --git a/contrib/llvm/lib/Bitcode/Writer/ValueEnumerator.h b/contrib/llvm/lib/Bitcode/Writer/ValueEnumerator.h
index a8d6cf9..e7ccc8d 100644
--- a/contrib/llvm/lib/Bitcode/Writer/ValueEnumerator.h
+++ b/contrib/llvm/lib/Bitcode/Writer/ValueEnumerator.h
@@ -36,7 +36,7 @@ class LocalAsMetadata;
 class MDNode;
 class MDOperand;
 class NamedMDNode;
-class AttributeSet;
+class AttributeList;
 class ValueSymbolTable;
 class MDSymbolTable;
 class raw_ostream;
@@ -48,6 +48,10 @@ public:
   // For each value, we remember its Value* and occurrence frequency.
   typedef std::vector<std::pair<const Value*, unsigned> > ValueList;
 
+  /// Attribute groups as encoded in bitcode are almost AttributeSets, but they
+  /// include the AttributeList index, so we have to track that in our map.
+  typedef std::pair<unsigned, AttributeSet> IndexAndAttrSet;
+
   UseListOrderStack UseListOrders;
 
 private:
@@ -102,13 +106,13 @@ private:
 
   bool ShouldPreserveUseListOrder;
 
-  typedef DenseMap<AttributeSet, unsigned> AttributeGroupMapType;
+  typedef DenseMap<IndexAndAttrSet, unsigned> AttributeGroupMapType;
   AttributeGroupMapType AttributeGroupMap;
-  std::vector<AttributeSet> AttributeGroups;
+  std::vector<IndexAndAttrSet> AttributeGroups;
 
-  typedef DenseMap<AttributeSet, unsigned> AttributeMapType;
-  AttributeMapType AttributeMap;
-  std::vector<AttributeSet> Attribute;
+  typedef DenseMap<AttributeList, unsigned> AttributeListMapType;
+  AttributeListMapType AttributeListMap;
+  std::vector<AttributeList> AttributeLists;
 
   /// GlobalBasicBlockIDs - This map memoizes the basic block ID's referenced by
   /// the "getGlobalBasicBlockID" method.
@@ -166,16 +170,17 @@ public:
   unsigned getInstructionID(const Instruction *I) const;
   void setInstructionID(const Instruction *I);
 
-  unsigned getAttributeID(AttributeSet PAL) const {
+  unsigned getAttributeListID(AttributeList PAL) const {
     if (PAL.isEmpty()) return 0;  // Null maps to zero.
-    AttributeMapType::const_iterator I = AttributeMap.find(PAL);
-    assert(I != AttributeMap.end() && "Attribute not in ValueEnumerator!");
+    AttributeListMapType::const_iterator I = AttributeListMap.find(PAL);
+    assert(I != AttributeListMap.end() && "Attribute not in ValueEnumerator!");
     return I->second;
   }
 
-  unsigned getAttributeGroupID(AttributeSet PAL) const {
-    if (PAL.isEmpty()) return 0;  // Null maps to zero.
-    AttributeGroupMapType::const_iterator I = AttributeGroupMap.find(PAL);
+  unsigned getAttributeGroupID(IndexAndAttrSet Group) const {
+    if (!Group.second.hasAttributes())
+      return 0; // Null maps to zero.
+    AttributeGroupMapType::const_iterator I = AttributeGroupMap.find(Group);
     assert(I != AttributeGroupMap.end() && "Attribute not in ValueEnumerator!");
     return I->second;
   }
@@ -206,10 +211,8 @@ public:
   const std::vector<const BasicBlock*> &getBasicBlocks() const {
     return BasicBlocks;
   }
-  const std::vector<AttributeSet> &getAttributes() const {
-    return Attribute;
-  }
-  const std::vector<AttributeSet> &getAttributeGroups() const {
+  const std::vector<AttributeList> &getAttributeLists() const { return AttributeLists; }
+  const std::vector<IndexAndAttrSet> &getAttributeGroups() const {
     return AttributeGroups;
   }
 
@@ -283,7 +286,7 @@ private:
   void EnumerateValue(const Value *V);
   void EnumerateType(Type *T);
   void EnumerateOperandType(const Value *V);
-  void EnumerateAttributes(AttributeSet PAL);
+  void EnumerateAttributes(AttributeList PAL);
 
   void EnumerateValueSymbolTable(const ValueSymbolTable &ST);
   void EnumerateNamedMetadata(const Module &M);