vendor/llvm/llvm-trunk-r321017

1 files changed, 367 insertions, 94 deletions

diff --git a/lib/Bitcode/Writer/BitcodeWriter.cpp b/lib/Bitcode/Writer/BitcodeWriter.cpp
index dcffde1742cd7..fd13dbc1f1e2b 100644
--- a/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -1,4 +1,4 @@
-//===--- Bitcode/Writer/BitcodeWriter.cpp - Bitcode Writer ----------------===//
+//===- Bitcode/Writer/BitcodeWriter.cpp - Bitcode Writer ------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -13,39 +13,81 @@
 
 #include "llvm/Bitcode/BitcodeWriter.h"
 #include "ValueEnumerator.h"
-#include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/APFloat.h"
+#include "llvm/ADT/APInt.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/None.h"
+#include "llvm/ADT/Optional.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/Triple.h"
+#include "llvm/Bitcode/BitCodes.h"
 #include "llvm/Bitcode/BitstreamWriter.h"
 #include "llvm/Bitcode/LLVMBitCodes.h"
+#include "llvm/IR/Attributes.h"
+#include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/CallSite.h"
+#include "llvm/IR/Comdat.h"
+#include "llvm/IR/Constant.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DebugInfoMetadata.h"
+#include "llvm/IR/DebugLoc.h"
 #include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/GlobalAlias.h"
+#include "llvm/IR/GlobalIFunc.h"
+#include "llvm/IR/GlobalObject.h"
+#include "llvm/IR/GlobalValue.h"
+#include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/InlineAsm.h"
+#include "llvm/IR/InstrTypes.h"
+#include "llvm/IR/Instruction.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Metadata.h"
 #include "llvm/IR/Module.h"
+#include "llvm/IR/ModuleSummaryIndex.h"
 #include "llvm/IR/Operator.h"
+#include "llvm/IR/Type.h"
 #include "llvm/IR/UseListOrder.h"
+#include "llvm/IR/Value.h"
 #include "llvm/IR/ValueSymbolTable.h"
 #include "llvm/MC/StringTableBuilder.h"
 #include "llvm/Object/IRSymtab.h"
+#include "llvm/Support/AtomicOrdering.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Endian.h"
+#include "llvm/Support/Error.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 <algorithm>
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <iterator>
 #include <map>
-using namespace llvm;
+#include <memory>
+#include <string>
+#include <utility>
+#include <vector>
 
-namespace {
+using namespace llvm;
 
-cl::opt<unsigned>
+static cl::opt<unsigned>
     IndexThreshold("bitcode-mdindex-threshold", cl::Hidden, cl::init(25),
                    cl::desc("Number of metadatas above which we emit an index "
                             "to enable lazy-loading"));
+
+namespace {
+
 /// These are manifest constants used by the bitcode writer. They do not need to
 /// be kept in sync with the reader, but need to be consistent within this file.
 enum {
@@ -97,11 +139,10 @@ void BitcodeWriterBase::writeModuleVersion() {
   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.
-  const SmallVectorImpl<char> &Buffer;
-
+/// Base class to manage the module bitcode writing, currently subclassed for
+/// ModuleBitcodeWriter and ThinLinkBitcodeWriter.
+class ModuleBitcodeWriterBase : public BitcodeWriterBase {
+protected:
   /// The Module to write to bitcode.
   const Module &M;
 
@@ -111,22 +152,6 @@ class ModuleBitcodeWriter : public BitcodeWriterBase {
   /// Optional per-module index to write for ThinLTO.
   const ModuleSummaryIndex *Index;
 
-  /// 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;
-
   /// Map that holds the correspondence between GUIDs in the summary index,
   /// that came from indirect call profiles, and a value id generated by this
   /// class to use in the VST and summary block records.
@@ -140,17 +165,14 @@ class ModuleBitcodeWriter : public BitcodeWriterBase {
   uint64_t VSTOffsetPlaceholder = 0;
 
 public:
-  /// Constructs a ModuleBitcodeWriter object for the given Module,
+  /// Constructs a ModuleBitcodeWriterBase 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,
-                      ModuleHash *ModHash = nullptr)
-      : BitcodeWriterBase(Stream, StrtabBuilder), Buffer(Buffer), M(*M),
-        VE(*M, ShouldPreserveUseListOrder), Index(Index),
-        GenerateHash(GenerateHash), ModHash(ModHash),
-        BitcodeStartBit(Stream.GetCurrentBitNo()) {
+  ModuleBitcodeWriterBase(const Module *M, StringTableBuilder &StrtabBuilder,
+                          BitstreamWriter &Stream,
+                          bool ShouldPreserveUseListOrder,
+                          const ModuleSummaryIndex *Index)
+      : BitcodeWriterBase(Stream, StrtabBuilder), M(*M),
+        VE(*M, ShouldPreserveUseListOrder), Index(Index) {
     // 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).
@@ -172,6 +194,73 @@ public:
               assignValueId(CallEdge.first.getGUID());
   }
 
+protected:
+  void writePerModuleGlobalValueSummary();
+
+private:
+  void writePerModuleFunctionSummaryRecord(SmallVector<uint64_t, 64> &NameVals,
+                                           GlobalValueSummary *Summary,
+                                           unsigned ValueID,
+                                           unsigned FSCallsAbbrev,
+                                           unsigned FSCallsProfileAbbrev,
+                                           const Function &F);
+  void writeModuleLevelReferences(const GlobalVariable &V,
+                                  SmallVector<uint64_t, 64> &NameVals,
+                                  unsigned FSModRefsAbbrev);
+
+  void assignValueId(GlobalValue::GUID ValGUID) {
+    GUIDToValueIdMap[ValGUID] = ++GlobalValueId;
+  }
+
+  unsigned getValueId(GlobalValue::GUID ValGUID) {
+    const auto &VMI = GUIDToValueIdMap.find(ValGUID);
+    // Expect that any GUID value had a value Id assigned by an
+    // earlier call to assignValueId.
+    assert(VMI != GUIDToValueIdMap.end() &&
+           "GUID does not have assigned value Id");
+    return VMI->second;
+  }
+
+  // Helper to get the valueId for the type of value recorded in VI.
+  unsigned getValueId(ValueInfo VI) {
+    if (!VI.getValue())
+      return getValueId(VI.getGUID());
+    return VE.getValueID(VI.getValue());
+  }
+
+  std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
+};
+
+/// Class to manage the bitcode writing for a module.
+class ModuleBitcodeWriter : public ModuleBitcodeWriterBase {
+  /// Pointer to the buffer allocated by caller for bitcode writing.
+  const SmallVectorImpl<char> &Buffer;
+
+  /// True if a module hash record should be written.
+  bool GenerateHash;
+
+  /// If non-null, when GenerateHash is true, the resulting hash is written
+  /// into ModHash.
+  ModuleHash *ModHash;
+
+  SHA1 Hasher;
+
+  /// The start bit of the identification block.
+  uint64_t BitcodeStartBit;
+
+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,
+                      ModuleHash *ModHash = nullptr)
+      : ModuleBitcodeWriterBase(M, StrtabBuilder, Stream,
+                                ShouldPreserveUseListOrder, Index),
+        Buffer(Buffer), GenerateHash(GenerateHash), ModHash(ModHash),
+        BitcodeStartBit(Stream.GetCurrentBitNo()) {}
+
   /// Emit the current module to the bitstream.
   void write();
 
@@ -287,37 +376,8 @@ private:
   writeFunction(const Function &F,
                 DenseMap<const Function *, uint64_t> &FunctionToBitcodeIndex);
   void writeBlockInfo();
-  void writePerModuleFunctionSummaryRecord(SmallVector<uint64_t, 64> &NameVals,
-                                           GlobalValueSummary *Summary,
-                                           unsigned ValueID,
-                                           unsigned FSCallsAbbrev,
-                                           unsigned FSCallsProfileAbbrev,
-                                           const Function &F);
-  void writeModuleLevelReferences(const GlobalVariable &V,
-                                  SmallVector<uint64_t, 64> &NameVals,
-                                  unsigned FSModRefsAbbrev);
-  void writePerModuleGlobalValueSummary();
   void writeModuleHash(size_t BlockStartPos);
 
-  void assignValueId(GlobalValue::GUID ValGUID) {
-    GUIDToValueIdMap[ValGUID] = ++GlobalValueId;
-  }
-  unsigned getValueId(GlobalValue::GUID ValGUID) {
-    const auto &VMI = GUIDToValueIdMap.find(ValGUID);
-    // Expect that any GUID value had a value Id assigned by an
-    // earlier call to assignValueId.
-    assert(VMI != GUIDToValueIdMap.end() &&
-           "GUID does not have assigned value Id");
-    return VMI->second;
-  }
-  // Helper to get the valueId for the type of value recorded in VI.
-  unsigned getValueId(ValueInfo VI) {
-    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);
   }
@@ -353,13 +413,13 @@ public:
     // 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.
-    forEachSummary([&](GVInfo I) {
+    forEachSummary([&](GVInfo I, bool) {
       GUIDToValueIdMap[I.first] = ++GlobalValueId;
     });
   }
 
   /// The below iterator returns the GUID and associated summary.
-  typedef std::pair<GlobalValue::GUID, GlobalValueSummary *> GVInfo;
+  using GVInfo = std::pair<GlobalValue::GUID, GlobalValueSummary *>;
 
   /// 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
@@ -368,12 +428,18 @@ public:
   void forEachSummary(Functor Callback) {
     if (ModuleToSummariesForIndex) {
       for (auto &M : *ModuleToSummariesForIndex)
-        for (auto &Summary : M.second)
-          Callback(Summary);
+        for (auto &Summary : M.second) {
+          Callback(Summary, false);
+          // Ensure aliasee is handled, e.g. for assigning a valueId,
+          // even if we are not importing the aliasee directly (the
+          // imported alias will contain a copy of aliasee).
+          if (auto *AS = dyn_cast<AliasSummary>(Summary.getSecond()))
+            Callback({AS->getAliaseeGUID(), &AS->getAliasee()}, true);
+        }
     } else {
       for (auto &Summaries : Index)
         for (auto &Summary : Summaries.second.SummaryList)
-          Callback({Summaries.first, Summary.get()});
+          Callback({Summaries.first, Summary.get()}, false);
     }
   }
 
@@ -413,8 +479,10 @@ private:
       return None;
     return VMI->second;
   }
+
   std::map<GlobalValue::GUID, unsigned> &valueIds() { return GUIDToValueIdMap; }
 };
+
 } // end anonymous namespace
 
 static unsigned getEncodedCastOpcode(unsigned Opcode) {
@@ -595,10 +663,14 @@ static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
     return bitc::ATTR_KIND_STACK_PROTECT_STRONG;
   case Attribute::SafeStack:
     return bitc::ATTR_KIND_SAFESTACK;
+  case Attribute::StrictFP:
+    return bitc::ATTR_KIND_STRICT_FP;
   case Attribute::StructRet:
     return bitc::ATTR_KIND_STRUCT_RET;
   case Attribute::SanitizeAddress:
     return bitc::ATTR_KIND_SANITIZE_ADDRESS;
+  case Attribute::SanitizeHWAddress:
+    return bitc::ATTR_KIND_SANITIZE_HWADDRESS;
   case Attribute::SanitizeThread:
     return bitc::ATTR_KIND_SANITIZE_THREAD;
   case Attribute::SanitizeMemory:
@@ -709,7 +781,6 @@ void ModuleBitcodeWriter::writeTypeTable() {
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // isvararg
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
-
   unsigned FunctionAbbrev = Stream.EmitAbbrev(std::move(Abbv));
 
   // Abbrev for TYPE_CODE_STRUCT_ANON.
@@ -718,7 +789,6 @@ void ModuleBitcodeWriter::writeTypeTable() {
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
-
   unsigned StructAnonAbbrev = Stream.EmitAbbrev(std::move(Abbv));
 
   // Abbrev for TYPE_CODE_STRUCT_NAME.
@@ -734,7 +804,6 @@ void ModuleBitcodeWriter::writeTypeTable() {
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
-
   unsigned StructNamedAbbrev = Stream.EmitAbbrev(std::move(Abbv));
 
   // Abbrev for TYPE_CODE_ARRAY.
@@ -742,7 +811,6 @@ void ModuleBitcodeWriter::writeTypeTable() {
   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // size
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, NumBits));
-
   unsigned ArrayAbbrev = Stream.EmitAbbrev(std::move(Abbv));
 
   // Emit an entry count so the reader can reserve space.
@@ -880,12 +948,23 @@ static unsigned getEncodedLinkage(const GlobalValue &GV) {
   return getEncodedLinkage(GV.getLinkage());
 }
 
+static uint64_t getEncodedFFlags(FunctionSummary::FFlags Flags) {
+  uint64_t RawFlags = 0;
+  RawFlags |= Flags.ReadNone;
+  RawFlags |= (Flags.ReadOnly << 1);
+  RawFlags |= (Flags.NoRecurse << 2);
+  RawFlags |= (Flags.ReturnDoesNotAlias << 3);
+  return RawFlags;
+}
+
 // Decode the flags for GlobalValue in the summary
 static uint64_t getEncodedGVSummaryFlags(GlobalValueSummary::GVFlags Flags) {
   uint64_t RawFlags = 0;
 
   RawFlags |= Flags.NotEligibleToImport; // bool
   RawFlags |= (Flags.Live << 1);
+  RawFlags |= (Flags.DSOLocal << 2);
+
   // 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.
@@ -1128,7 +1207,7 @@ void ModuleBitcodeWriter::writeModuleInfo() {
     // GLOBALVAR: [strtab offset, strtab size, type, isconst, initid,
     //             linkage, alignment, section, visibility, threadlocal,
     //             unnamed_addr, externally_initialized, dllstorageclass,
-    //             comdat, attributes]
+    //             comdat, attributes, DSO_Local]
     Vals.push_back(addToStrtab(GV.getName()));
     Vals.push_back(GV.getName().size());
     Vals.push_back(VE.getTypeID(GV.getValueType()));
@@ -1144,7 +1223,8 @@ void ModuleBitcodeWriter::writeModuleInfo() {
         GV.isExternallyInitialized() ||
         GV.getDLLStorageClass() != GlobalValue::DefaultStorageClass ||
         GV.hasComdat() ||
-        GV.hasAttributes()) {
+        GV.hasAttributes() ||
+        GV.isDSOLocal()) {
       Vals.push_back(getEncodedVisibility(GV));
       Vals.push_back(getEncodedThreadLocalMode(GV));
       Vals.push_back(getEncodedUnnamedAddr(GV));
@@ -1154,6 +1234,8 @@ void ModuleBitcodeWriter::writeModuleInfo() {
 
       auto AL = GV.getAttributesAsList(AttributeList::FunctionIndex);
       Vals.push_back(VE.getAttributeListID(AL));
+
+      Vals.push_back(GV.isDSOLocal());
     } else {
       AbbrevToUse = SimpleGVarAbbrev;
     }
@@ -1167,7 +1249,7 @@ void ModuleBitcodeWriter::writeModuleInfo() {
     // FUNCTION:  [strtab offset, strtab size, type, callingconv, isproto,
     //             linkage, paramattrs, alignment, section, visibility, gc,
     //             unnamed_addr, prologuedata, dllstorageclass, comdat,
-    //             prefixdata, personalityfn]
+    //             prefixdata, personalityfn, DSO_Local]
     Vals.push_back(addToStrtab(F.getName()));
     Vals.push_back(F.getName().size());
     Vals.push_back(VE.getTypeID(F.getFunctionType()));
@@ -1189,6 +1271,7 @@ void ModuleBitcodeWriter::writeModuleInfo() {
     Vals.push_back(
         F.hasPersonalityFn() ? (VE.getValueID(F.getPersonalityFn()) + 1) : 0);
 
+    Vals.push_back(F.isDSOLocal());
     unsigned AbbrevToUse = 0;
     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);
     Vals.clear();
@@ -1197,7 +1280,8 @@ void ModuleBitcodeWriter::writeModuleInfo() {
   // Emit the alias information.
   for (const GlobalAlias &A : M.aliases()) {
     // ALIAS: [strtab offset, strtab size, alias type, aliasee val#, linkage,
-    //         visibility, dllstorageclass, threadlocal, unnamed_addr]
+    //         visibility, dllstorageclass, threadlocal, unnamed_addr,
+    //         DSO_Local]
     Vals.push_back(addToStrtab(A.getName()));
     Vals.push_back(A.getName().size());
     Vals.push_back(VE.getTypeID(A.getValueType()));
@@ -1208,6 +1292,8 @@ void ModuleBitcodeWriter::writeModuleInfo() {
     Vals.push_back(getEncodedDLLStorageClass(A));
     Vals.push_back(getEncodedThreadLocalMode(A));
     Vals.push_back(getEncodedUnnamedAddr(A));
+    Vals.push_back(A.isDSOLocal());
+
     unsigned AbbrevToUse = 0;
     Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals, AbbrevToUse);
     Vals.clear();
@@ -1243,8 +1329,8 @@ static uint64_t getOptimizationFlags(const Value *V) {
     if (PEO->isExact())
       Flags |= 1 << bitc::PEO_EXACT;
   } else if (const auto *FPMO = dyn_cast<FPMathOperator>(V)) {
-    if (FPMO->hasUnsafeAlgebra())
-      Flags |= FastMathFlags::UnsafeAlgebra;
+    if (FPMO->hasAllowReassoc())
+      Flags |= FastMathFlags::AllowReassoc;
     if (FPMO->hasNoNaNs())
       Flags |= FastMathFlags::NoNaNs;
     if (FPMO->hasNoInfs())
@@ -1255,6 +1341,8 @@ static uint64_t getOptimizationFlags(const Value *V) {
       Flags |= FastMathFlags::AllowReciprocal;
     if (FPMO->hasAllowContract())
       Flags |= FastMathFlags::AllowContract;
+    if (FPMO->hasApproxFunc())
+      Flags |= FastMathFlags::ApproxFunc;
   }
 
   return Flags;
@@ -1486,6 +1574,7 @@ void ModuleBitcodeWriter::writeDICompileUnit(const DICompileUnit *N,
   Record.push_back(VE.getMetadataOrNullID(N->getMacros().get()));
   Record.push_back(N->getSplitDebugInlining());
   Record.push_back(N->getDebugInfoForProfiling());
+  Record.push_back(N->getGnuPubnames());
 
   Stream.EmitRecord(bitc::METADATA_COMPILE_UNIT, Record, Abbrev);
   Record.clear();
@@ -1688,7 +1777,7 @@ void ModuleBitcodeWriter::writeDIGlobalVariableExpression(
   Record.push_back(N->isDistinct());
   Record.push_back(VE.getMetadataOrNullID(N->getVariable()));
   Record.push_back(VE.getMetadataOrNullID(N->getExpression()));
-  
+
   Stream.EmitRecord(bitc::METADATA_GLOBAL_VAR_EXPR, Record, Abbrev);
   Record.clear();
 }
@@ -2180,7 +2269,7 @@ void ModuleBitcodeWriter::writeConstants(unsigned FirstVal, unsigned LastVal,
         Record.push_back(p[0]);
         Record.push_back(p[1]);
       } else {
-        assert (0 && "Unknown FP type!");
+        assert(0 && "Unknown FP type!");
       }
     } else if (isa<ConstantDataSequential>(C) &&
                cast<ConstantDataSequential>(C)->isString()) {
@@ -3025,8 +3114,6 @@ void ModuleBitcodeWriter::writeBlockInfo() {
       llvm_unreachable("Unexpected abbrev ordering!");
   }
 
-
-
   { // SETTYPE abbrev for CONSTANTS_BLOCK.
     auto Abbv = std::make_shared<BitCodeAbbrev>();
     Abbv->Add(BitCodeAbbrevOp(bitc::CST_CODE_SETTYPE));
@@ -3267,7 +3354,7 @@ static void writeFunctionTypeMetadataRecords(BitstreamWriter &Stream,
 }
 
 // Helper to emit a single function summary record.
-void ModuleBitcodeWriter::writePerModuleFunctionSummaryRecord(
+void ModuleBitcodeWriterBase::writePerModuleFunctionSummaryRecord(
     SmallVector<uint64_t, 64> &NameVals, GlobalValueSummary *Summary,
     unsigned ValueID, unsigned FSCallsAbbrev, unsigned FSCallsProfileAbbrev,
     const Function &F) {
@@ -3278,6 +3365,7 @@ void ModuleBitcodeWriter::writePerModuleFunctionSummaryRecord(
 
   NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
   NameVals.push_back(FS->instCount());
+  NameVals.push_back(getEncodedFFlags(FS->fflags()));
   NameVals.push_back(FS->refs().size());
 
   for (auto &RI : FS->refs())
@@ -3301,7 +3389,7 @@ void ModuleBitcodeWriter::writePerModuleFunctionSummaryRecord(
 
 // Collect the global value references in the given variable's initializer,
 // and emit them in a summary record.
-void ModuleBitcodeWriter::writeModuleLevelReferences(
+void ModuleBitcodeWriterBase::writeModuleLevelReferences(
     const GlobalVariable &V, SmallVector<uint64_t, 64> &NameVals,
     unsigned FSModRefsAbbrev) {
   auto VI = Index->getValueInfo(GlobalValue::getGUID(V.getName()));
@@ -3331,11 +3419,11 @@ void ModuleBitcodeWriter::writeModuleLevelReferences(
 // Current version for the summary.
 // This is bumped whenever we introduce changes in the way some record are
 // interpreted, like flags for instance.
-static const uint64_t INDEX_VERSION = 3;
+static const uint64_t INDEX_VERSION = 4;
 
 /// Emit the per-module summary section alongside the rest of
 /// the module's bitcode.
-void ModuleBitcodeWriter::writePerModuleGlobalValueSummary() {
+void ModuleBitcodeWriterBase::writePerModuleGlobalValueSummary() {
   // 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;
@@ -3364,6 +3452,7 @@ void ModuleBitcodeWriter::writePerModuleGlobalValueSummary() {
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
   // numrefs x valueid, n x (valueid)
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
@@ -3376,6 +3465,7 @@ void ModuleBitcodeWriter::writePerModuleGlobalValueSummary() {
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
   // numrefs x valueid, n x (valueid, hotness)
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
@@ -3461,6 +3551,7 @@ void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
   // numrefs x valueid, n x (valueid)
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
@@ -3474,6 +3565,7 @@ void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // flags
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // instcount
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // fflags
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4));   // numrefs
   // numrefs x valueid, n x (valueid, hotness)
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
@@ -3518,7 +3610,7 @@ void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
     NameVals.clear();
   };
 
-  forEachSummary([&](GVInfo I) {
+  forEachSummary([&](GVInfo I, bool IsAliasee) {
     GlobalValueSummary *S = I.second;
     assert(S);
 
@@ -3526,6 +3618,12 @@ void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
     assert(ValueId);
     SummaryToValueIdMap[S] = *ValueId;
 
+    // If this is invoked for an aliasee, we want to record the above
+    // mapping, but then not emit a summary entry (if the aliasee is
+    // to be imported, we will invoke this separately with IsAliasee=false).
+    if (IsAliasee)
+      return;
+
     if (auto *AS = dyn_cast<AliasSummary>(S)) {
       // Will process aliases as a post-pass because the reader wants all
       // global to be loaded first.
@@ -3559,6 +3657,7 @@ void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
     NameVals.push_back(Index.getModuleId(FS->modulePath()));
     NameVals.push_back(getEncodedGVSummaryFlags(FS->flags()));
     NameVals.push_back(FS->instCount());
+    NameVals.push_back(getEncodedFFlags(FS->fflags()));
     // Fill in below
     NameVals.push_back(0);
 
@@ -3570,7 +3669,7 @@ void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
       NameVals.push_back(*RefValueId);
       Count++;
     }
-    NameVals[4] = Count;
+    NameVals[5] = Count;
 
     bool HasProfileData = false;
     for (auto &EI : FS->calls()) {
@@ -3594,6 +3693,20 @@ void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
         CallValueId = getValueId(GUID);
         if (!CallValueId)
           continue;
+        // The mapping from OriginalId to GUID may return a GUID
+        // that corresponds to a static variable. Filter it out here.
+        // This can happen when 
+        // 1) There is a call to a library function which does not have
+        // a CallValidId;
+        // 2) There is a static variable with the  OriginalGUID identical
+        // to the GUID of the library function in 1);
+        // When this happens, the logic for SamplePGO kicks in and
+        // the static variable in 2) will be found, which needs to be
+        // filtered out.
+        auto *GVSum = Index.getGlobalValueSummary(GUID, false);
+        if (GVSum &&
+            GVSum->getSummaryKind() == GlobalValueSummary::GlobalVarKind)
+          continue;
       }
       NameVals.push_back(*CallValueId);
       if (HasProfileData)
@@ -3689,8 +3802,7 @@ void ModuleBitcodeWriter::writeModuleHash(size_t BlockStartPos) {
     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() {
@@ -3985,3 +4097,164 @@ void llvm::WriteIndexToFile(
 
   Out.write((char *)&Buffer.front(), Buffer.size());
 }
+
+namespace {
+
+/// Class to manage the bitcode writing for a thin link bitcode file.
+class ThinLinkBitcodeWriter : public ModuleBitcodeWriterBase {
+  /// ModHash is for use in ThinLTO incremental build, generated while writing
+  /// the module bitcode file.
+  const ModuleHash *ModHash;
+
+public:
+  ThinLinkBitcodeWriter(const Module *M, StringTableBuilder &StrtabBuilder,
+                        BitstreamWriter &Stream,
+                        const ModuleSummaryIndex &Index,
+                        const ModuleHash &ModHash)
+      : ModuleBitcodeWriterBase(M, StrtabBuilder, Stream,
+                                /*ShouldPreserveUseListOrder=*/false, &Index),
+        ModHash(&ModHash) {}
+
+  void write();
+
+private:
+  void writeSimplifiedModuleInfo();
+};
+
+} // end anonymous namespace
+
+// This function writes a simpilified module info for thin link bitcode file.
+// It only contains the source file name along with the name(the offset and
+// size in strtab) and linkage for global values. For the global value info
+// entry, in order to keep linkage at offset 5, there are three zeros used
+// as padding.
+void ThinLinkBitcodeWriter::writeSimplifiedModuleInfo() {
+  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);
+
+    Stream.EmitRecord(bitc::MODULE_CODE_SOURCE_FILENAME, Vals, FilenameAbbrev);
+    Vals.clear();
+  }
+
+  // Emit the global variable information.
+  for (const GlobalVariable &GV : M.globals()) {
+    // GLOBALVAR: [strtab offset, strtab size, 0, 0, 0, linkage]
+    Vals.push_back(StrtabBuilder.add(GV.getName()));
+    Vals.push_back(GV.getName().size());
+    Vals.push_back(0);
+    Vals.push_back(0);
+    Vals.push_back(0);
+    Vals.push_back(getEncodedLinkage(GV));
+
+    Stream.EmitRecord(bitc::MODULE_CODE_GLOBALVAR, Vals);
+    Vals.clear();
+  }
+
+  // Emit the function proto information.
+  for (const Function &F : M) {
+    // FUNCTION:  [strtab offset, strtab size, 0, 0, 0, linkage]
+    Vals.push_back(StrtabBuilder.add(F.getName()));
+    Vals.push_back(F.getName().size());
+    Vals.push_back(0);
+    Vals.push_back(0);
+    Vals.push_back(0);
+    Vals.push_back(getEncodedLinkage(F));
+
+    Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals);
+    Vals.clear();
+  }
+
+  // Emit the alias information.
+  for (const GlobalAlias &A : M.aliases()) {
+    // ALIAS: [strtab offset, strtab size, 0, 0, 0, linkage]
+    Vals.push_back(StrtabBuilder.add(A.getName()));
+    Vals.push_back(A.getName().size());
+    Vals.push_back(0);
+    Vals.push_back(0);
+    Vals.push_back(0);
+    Vals.push_back(getEncodedLinkage(A));
+
+    Stream.EmitRecord(bitc::MODULE_CODE_ALIAS, Vals);
+    Vals.clear();
+  }
+
+  // Emit the ifunc information.
+  for (const GlobalIFunc &I : M.ifuncs()) {
+    // IFUNC: [strtab offset, strtab size, 0, 0, 0, linkage]
+    Vals.push_back(StrtabBuilder.add(I.getName()));
+    Vals.push_back(I.getName().size());
+    Vals.push_back(0);
+    Vals.push_back(0);
+    Vals.push_back(0);
+    Vals.push_back(getEncodedLinkage(I));
+
+    Stream.EmitRecord(bitc::MODULE_CODE_IFUNC, Vals);
+    Vals.clear();
+  }
+}
+
+void ThinLinkBitcodeWriter::write() {
+  Stream.EnterSubblock(bitc::MODULE_BLOCK_ID, 3);
+
+  writeModuleVersion();
+
+  writeSimplifiedModuleInfo();
+
+  writePerModuleGlobalValueSummary();
+
+  // Write module hash.
+  Stream.EmitRecord(bitc::MODULE_CODE_HASH, ArrayRef<uint32_t>(*ModHash));
+
+  Stream.ExitBlock();
+}
+
+void BitcodeWriter::writeThinLinkBitcode(const Module *M,
+                                         const ModuleSummaryIndex &Index,
+                                         const 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));
+
+  ThinLinkBitcodeWriter ThinLinkWriter(M, StrtabBuilder, *Stream, Index,
+                                       ModHash);
+  ThinLinkWriter.write();
+}
+
+// Write the specified thin link bitcode file to the given raw output stream,
+// where it will be written in a new bitcode block. This is used when
+// writing the per-module index file for ThinLTO.
+void llvm::WriteThinLinkBitcodeToFile(const Module *M, raw_ostream &Out,
+                                      const ModuleSummaryIndex &Index,
+                                      const ModuleHash &ModHash) {
+  SmallVector<char, 0> Buffer;
+  Buffer.reserve(256 * 1024);
+
+  BitcodeWriter Writer(Buffer);
+  Writer.writeThinLinkBitcode(M, Index, ModHash);
+  Writer.writeSymtab();
+  Writer.writeStrtab();
+
+  Out.write((char *)&Buffer.front(), Buffer.size());
+}