Linker: Add support for GlobalIFunc.

[pcc]

Summary

GlobalAlias and GlobalIFunc ought to be treated the same by the IR
linker, so we can generalize the code to be in terms of their common
base class GlobalIndirectSymbol.

[tejohnson]

LGTM with a few minor comments.

llvm/include/llvm/Transforms/Utils/ValueMapper.h

185

Elsewhere this was changed to "Constant &Target", make this one consistent.

llvm/lib/Linker/IRMover.cpp

590

This comment block might need to be generalized since it talks about aliases

llvm/test/LTO/Resolution/X86/ifunc2.ll

13

Nit: these 2 check lines correspond to the below @foo_resolver def, so it would make more sense to put them right before it, whereas the ones you check right before it are for the copy from the other module (which might make more sense shown after the below def).

llvm/include/llvm/IR/GlobalAlias.h

public:
 
   // Type, Parent and AddressSpace taken from the Aliasee.
   static GlobalAlias *create(LinkageTypes Linkage, const Twine &Name,
                              GlobalValue *Aliasee);
 
   // Linkage, Type, Parent and AddressSpace taken from the Aliasee.
   static GlobalAlias *create(const Twine &Name, GlobalValue *Aliasee);
 
-  void copyAttributesFrom(const GlobalValue *Src) {
-    GlobalValue::copyAttributesFrom(Src);
-  }
-
   /// removeFromParent - This method unlinks 'this' from the containing module,
   /// but does not delete it.
   ///
   void removeFromParent();
 
   /// eraseFromParent - This method unlinks 'this' from the containing module
   /// and deletes it.
   ///

llvm/include/llvm/IR/GlobalIFunc.h

public:
   GlobalIFunc &operator=(const GlobalIFunc &) = delete;
 
   /// If a parent module is specified, the ifunc is automatically inserted into
   /// the end of the specified module's ifunc list.
   static GlobalIFunc *create(Type *Ty, unsigned AddressSpace,
                              LinkageTypes Linkage, const Twine &Name,
                              Constant *Resolver, Module *Parent);
 
-  void copyAttributesFrom(const GlobalIFunc *Src) {
-    GlobalValue::copyAttributesFrom(Src);
-  }
-
   /// This method unlinks 'this' from the containing module, but does not
   /// delete it.
   void removeFromParent();
 
   /// This method unlinks 'this' from the containing module and deletes it.
   void eraseFromParent();
 
   /// These methods retrieve and set ifunc resolver function.

llvm/include/llvm/IR/GlobalIndirectSymbol.h

public:
   // allocate space for exactly one operand
   void *operator new(size_t s) {
     return User::operator new(s, 1);
   }
 
   /// Provide fast operand accessors
   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Constant);
 
+  void copyAttributesFrom(const GlobalValue *Src) {
+    GlobalValue::copyAttributesFrom(Src);
+  }
+
   /// These methods set and retrieve indirect symbol.
   void setIndirectSymbol(Constant *Symbol) {
     setOperand(0, Symbol);
   }
   const Constant *getIndirectSymbol() const {
     return getOperand(0);
   }
   Constant *getIndirectSymbol() {

llvm/include/llvm/Transforms/Utils/ValueMapper.h

 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/IR/ValueHandle.h"
 #include "llvm/IR/ValueMap.h"
 
 namespace llvm {
 
 class Constant;
 class Function;
-class GlobalAlias;
+class GlobalIndirectSymbol;
 class GlobalVariable;
 class Instruction;
 class MDNode;
 class Metadata;
 class Type;
 class Value;
 
 using ValueToValueMapTy = ValueMap<const Value *, WeakTrackingVH>;

 /// - \a remapFunction().
 ///
 /// The \a ValueMaterializer can be used as a callback, but cannot invoke any
 /// of these top-level functions recursively.  Instead, callbacks should use
 /// one of the following to schedule work lazily in the \a ValueMapper
 /// instance:
 /// - \a scheduleMapGlobalInitializer()
 /// - \a scheduleMapAppendingVariable()
-/// - \a scheduleMapGlobalAliasee()
+/// - \a scheduleMapGlobalIndirectSymbol()
 /// - \a scheduleRemapFunction()
 ///
 /// Sometimes a callback needs a different mapping context.  Such a context can
 /// be registered using \a registerAlternateMappingContext(), which takes an
 /// alternate \a ValueToValueMapTy and \a ValueMaterializer and returns a ID to
 /// pass into the schedule*() functions.
 ///
 /// TODO: lib/Linker really doesn't need the \a ValueHandle in the \a
public:
   void remapFunction(Function &F);
 
   void scheduleMapGlobalInitializer(GlobalVariable &GV, Constant &Init,
                                     unsigned MappingContextID = 0);
   void scheduleMapAppendingVariable(GlobalVariable &GV, Constant *InitPrefix,
                                     bool IsOldCtorDtor,
                                     ArrayRef<Constant *> NewMembers,
                                     unsigned MappingContextID = 0);
-  void scheduleMapGlobalAliasee(GlobalAlias &GA, Constant &Aliasee,
+  void scheduleMapGlobalIndirectSymbol(GlobalIndirectSymbol &GIS,
+                                       Constant &Aliasee,
                                        unsigned MappingContextID = 0);
   void scheduleRemapFunction(Function &F, unsigned MappingContextID = 0);
 };
 
 /// Look up or compute a value in the value map.
 ///
 /// Return a mapped value for a function-local value (Argument, Instruction,
 /// BasicBlock), or compute and memoize a value for a Constant.
 ///

llvm/lib/Linker/IRMover.cpp

class IRLinker {
   /// A metadata map that's shared between IRLinker instances.
   MDMapT &SharedMDs;
 
   /// Mapping of values from what they used to be in Src, to what they are now
   /// in DstM.  ValueToValueMapTy is a ValueMap, which involves some overhead
   /// due to the use of Value handles which the Linker doesn't actually need,
   /// but this allows us to reuse the ValueMapper code.
   ValueToValueMapTy ValueMap;
-  ValueToValueMapTy AliasValueMap;
+  ValueToValueMapTy IndirectSymbolValueMap;
 
   DenseSet<GlobalValue *> ValuesToLink;
   std::vector<GlobalValue *> Worklist;
 
   void maybeAdd(GlobalValue *GV) {
     if (ValuesToLink.insert(GV).second)
       Worklist.push_back(GV);
   }
class IRLinker {
   /// Most of the errors produced by this module are inconvertible StringErrors.
   /// This convenience function lets us return one of those more easily.
   Error stringErr(const Twine &T) {
     return make_error<StringError>(T, inconvertibleErrorCode());
   }
 
   /// Entry point for mapping values and alternate context for mapping aliases.
   ValueMapper Mapper;
-  unsigned AliasMCID;
+  unsigned IndirectSymbolMCID;
 
   /// Handles cloning of a global values from the source module into
   /// the destination module, including setting the attributes and visibility.
   GlobalValue *copyGlobalValueProto(const GlobalValue *SGV, bool ForDefinition);
 
   void emitWarning(const Twine &Message) {
     SrcM->getContext().diagnose(LinkDiagnosticInfo(DS_Warning, Message));
   }
Expected<Constant *> linkAppendingVarProto(GlobalVariable *DstGV,
                                              const GlobalVariable *SrcGV);
 
   /// Given the GlobaValue \p SGV in the source module, and the matching
   /// GlobalValue \p DGV (if any), return true if the linker will pull \p SGV
   /// into the destination module.
   ///
   /// Note this code may call the client-provided \p AddLazyFor.
   bool shouldLink(GlobalValue *DGV, GlobalValue &SGV);
-  Expected<Constant *> linkGlobalValueProto(GlobalValue *GV, bool ForAlias);
+  Expected<Constant *> linkGlobalValueProto(GlobalValue *GV, bool ForIndirectSymbol);
 
   Error linkModuleFlagsMetadata();
 
   void linkGlobalVariable(GlobalVariable &Dst, GlobalVariable &Src);
   Error linkFunctionBody(Function &Dst, Function &Src);
-  void linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src);
+  void linkIndirectSymbolBody(GlobalIndirectSymbol &Dst,
+                              GlobalIndirectSymbol &Src);
   Error linkGlobalValueBody(GlobalValue &Dst, GlobalValue &Src);
 
   /// Functions that take care of cloning a specific global value type
   /// into the destination module.
   GlobalVariable *copyGlobalVariableProto(const GlobalVariable *SGVar);
   Function *copyFunctionProto(const Function *SF);
-  GlobalValue *copyGlobalAliasProto(const GlobalAlias *SGA);
+  GlobalValue *copyGlobalIndirectSymbolProto(const GlobalIndirectSymbol *SGIS);
 
   /// When importing for ThinLTO, prevent importing of types listed on
   /// the DICompileUnit that we don't need a copy of in the importing
   /// module.
   void prepareCompileUnitsForImport();
   void linkNamedMDNodes();
 
 public:
   IRLinker(Module &DstM, MDMapT &SharedMDs,
            IRMover::IdentifiedStructTypeSet &Set, std::unique_ptr<Module> SrcM,
            ArrayRef<GlobalValue *> ValuesToLink,
            std::function<void(GlobalValue &, IRMover::ValueAdder)> AddLazyFor,
            bool IsPerformingImport)
       : DstM(DstM), SrcM(std::move(SrcM)), AddLazyFor(std::move(AddLazyFor)),
         TypeMap(Set), GValMaterializer(*this), LValMaterializer(*this),
         SharedMDs(SharedMDs), IsPerformingImport(IsPerformingImport),
         Mapper(ValueMap, RF_MoveDistinctMDs | RF_IgnoreMissingLocals, &TypeMap,
                &GValMaterializer),
-        AliasMCID(Mapper.registerAlternateMappingContext(AliasValueMap,
-                                                         &LValMaterializer)) {
+        IndirectSymbolMCID(Mapper.registerAlternateMappingContext(
+            IndirectSymbolValueMap, &LValMaterializer)) {
     ValueMap.getMDMap() = std::move(SharedMDs);
     for (GlobalValue *GV : ValuesToLink)
       maybeAdd(GV);
     if (IsPerformingImport)
       prepareCompileUnitsForImport();
   }
   ~IRLinker() { SharedMDs = std::move(*ValueMap.getMDMap()); }
 
   Error run();
-  Value *materialize(Value *V, bool ForAlias);
+  Value *materialize(Value *V, bool ForIndirectSymbol);
 };
 }
 
 /// The LLVM SymbolTable class autorenames globals that conflict in the symbol
 /// table. This is good for all clients except for us. Go through the trouble
 /// to force this back.
 static void forceRenaming(GlobalValue *GV, StringRef Name) {
   // If the global doesn't force its name or if it already has the right name,

 Value *GlobalValueMaterializer::materialize(Value *SGV) {
   return TheIRLinker.materialize(SGV, false);
 }
 
 Value *LocalValueMaterializer::materialize(Value *SGV) {
   return TheIRLinker.materialize(SGV, true);
 }
 
-Value *IRLinker::materialize(Value *V, bool ForAlias) {
+Value *IRLinker::materialize(Value *V, bool ForIndirectSymbol) {
   auto *SGV = dyn_cast<GlobalValue>(V);
   if (!SGV)
     return nullptr;
 
-  Expected<Constant *> NewProto = linkGlobalValueProto(SGV, ForAlias);
+  Expected<Constant *> NewProto = linkGlobalValueProto(SGV, ForIndirectSymbol);
   if (!NewProto) {
     setError(NewProto.takeError());
     return nullptr;
   }
   if (!*NewProto)
     return nullptr;
 
   GlobalValue *New = dyn_cast<GlobalValue>(*NewProto);
   if (!New)
     return *NewProto;
 
   // If we already created the body, just return.
   if (auto *F = dyn_cast<Function>(New)) {
     if (!F->isDeclaration())
       return New;
   } else if (auto *V = dyn_cast<GlobalVariable>(New)) {
     if (V->hasInitializer() || V->hasAppendingLinkage())
       return New;
   } else {
-    auto *A = cast<GlobalAlias>(New);
-    if (A->getAliasee())
+    auto *IS = cast<GlobalIndirectSymbol>(New);
+    if (IS->getIndirectSymbol())
       return New;
   }
 
   // When linking a global for an alias, it will always be linked. However we
   // need to check if it was not already scheduled to satisfy a reference from a
   // regular global value initializer. We know if it has been schedule if the
   // "New" GlobalValue that is mapped here for the alias is the same as the one
   // already mapped. If there is an entry in the ValueMap but the value is
   // different, it means that the value already had a definition in the
   // destination module (linkonce for instance), but we need a new definition
   // for the alias ("New" will be different.
-  if (ForAlias && ValueMap.lookup(SGV) == New)
+  if (ForIndirectSymbol && ValueMap.lookup(SGV) == New)
     return New;
 
-  if (ForAlias || shouldLink(New, *SGV))
+  if (ForIndirectSymbol || shouldLink(New, *SGV))
     setError(linkGlobalValueBody(*New, *SGV));
 
   return New;
 }
 
 /// Loop through the global variables in the src module and merge them into the
 /// dest module.
 GlobalVariable *IRLinker::copyGlobalVariableProto(const GlobalVariable *SGVar) {
Function *IRLinker::copyFunctionProto(const Function *SF) {
   // bring SF over.
   auto *F =
       Function::Create(TypeMap.get(SF->getFunctionType()),
                        GlobalValue::ExternalLinkage, SF->getName(), &DstM);
   F->copyAttributesFrom(SF);
   return F;
 }
 
-/// Set up prototypes for any aliases that come over from the source module.
-GlobalValue *IRLinker::copyGlobalAliasProto(const GlobalAlias *SGA) {
+/// Set up prototypes for any indirect symbols that come over from the source
+/// module.
+GlobalValue *
+IRLinker::copyGlobalIndirectSymbolProto(const GlobalIndirectSymbol *SGIS) {
   // If there is no linkage to be performed or we're linking from the source,
   // bring over SGA.
-  auto *Ty = TypeMap.get(SGA->getValueType());
-  auto *GA =
-      GlobalAlias::create(Ty, SGA->getType()->getPointerAddressSpace(),
-                          GlobalValue::ExternalLinkage, SGA->getName(), &DstM);
-  GA->copyAttributesFrom(SGA);
-  return GA;
+  auto *Ty = TypeMap.get(SGIS->getValueType());
+  GlobalIndirectSymbol *GIS;
+  if (isa<GlobalAlias>(SGIS))
+    GIS = GlobalAlias::create(Ty, SGIS->getType()->getPointerAddressSpace(),
+                              GlobalValue::ExternalLinkage, SGIS->getName(),
+                              &DstM);
+  else
+    GIS = GlobalIFunc::create(Ty, SGIS->getType()->getPointerAddressSpace(),
+                              GlobalValue::ExternalLinkage, SGIS->getName(),
+                              nullptr, &DstM);
+  GIS->copyAttributesFrom(SGIS);
+  return GIS;
 }
 
 GlobalValue *IRLinker::copyGlobalValueProto(const GlobalValue *SGV,
                                             bool ForDefinition) {
   GlobalValue *NewGV;
   if (auto *SGVar = dyn_cast<GlobalVariable>(SGV)) {
     NewGV = copyGlobalVariableProto(SGVar);
   } else if (auto *SF = dyn_cast<Function>(SGV)) {
     NewGV = copyFunctionProto(SF);
   } else {
     if (ForDefinition)
-      NewGV = copyGlobalAliasProto(cast<GlobalAlias>(SGV));
+      NewGV = copyGlobalIndirectSymbolProto(cast<GlobalIndirectSymbol>(SGV));
     else if (SGV->getValueType()->isFunctionTy())
       NewGV =
           Function::Create(cast<FunctionType>(TypeMap.get(SGV->getValueType())),
                            GlobalValue::ExternalLinkage, SGV->getName(), &DstM);
     else
       NewGV = new GlobalVariable(
           DstM, TypeMap.get(SGV->getValueType()),
           /*isConstant*/ false, GlobalValue::ExternalLinkage,
bool IRLinker::shouldLink(GlobalValue *DGV, GlobalValue &SGV) {
   AddLazyFor(SGV, [this, &LazilyAdded](GlobalValue &GV) {
     maybeAdd(&GV);
     LazilyAdded = true;
   });
   return LazilyAdded;
 }
 
 Expected<Constant *> IRLinker::linkGlobalValueProto(GlobalValue *SGV,
-                                                    bool ForAlias) {
+                                                    bool ForIndirectSymbol) {
   GlobalValue *DGV = getLinkedToGlobal(SGV);
 
   bool ShouldLink = shouldLink(DGV, *SGV);
 
   // just missing from map
   if (ShouldLink) {
     auto I = ValueMap.find(SGV);
     if (I != ValueMap.end())
       return cast<Constant>(I->second);
 
-    I = AliasValueMap.find(SGV);
-    if (I != AliasValueMap.end())
+    I = IndirectSymbolValueMap.find(SGV);
+    if (I != IndirectSymbolValueMap.end())
       return cast<Constant>(I->second);
   }
 
-  if (!ShouldLink && ForAlias)
+  if (!ShouldLink && ForIndirectSymbol)
     DGV = nullptr;
 
   // Handle the ultra special appending linkage case first.
   assert(!DGV || SGV->hasAppendingLinkage() == DGV->hasAppendingLinkage());
   if (SGV->hasAppendingLinkage())
     return linkAppendingVarProto(cast_or_null<GlobalVariable>(DGV),
                                  cast<GlobalVariable>(SGV));
 
   GlobalValue *NewGV;
   if (DGV && !ShouldLink) {
     NewGV = DGV;
   } else {
     // If we are done linking global value bodies (i.e. we are performing
     // metadata linking), don't link in the global value due to this
     // reference, simply map it to null.
     if (DoneLinkingBodies)
       return nullptr;
 
-    NewGV = copyGlobalValueProto(SGV, ShouldLink || ForAlias);
-    if (ShouldLink || !ForAlias)
+    NewGV = copyGlobalValueProto(SGV, ShouldLink || ForIndirectSymbol);
+    if (ShouldLink || !ForIndirectSymbol)
       forceRenaming(NewGV, SGV->getName());
   }
 
   // Overloaded intrinsics have overloaded types names as part of their
   // names. If we renamed overloaded types we should rename the intrinsic
   // as well.
   if (Function *F = dyn_cast<Function>(NewGV))
     if (auto Remangled = Intrinsic::remangleIntrinsicFunction(F))
       NewGV = Remangled.getValue();
 
-  if (ShouldLink || ForAlias) {
+  if (ShouldLink || ForIndirectSymbol) {
     if (const Comdat *SC = SGV->getComdat()) {
       if (auto *GO = dyn_cast<GlobalObject>(NewGV)) {
         Comdat *DC = DstM.getOrInsertComdat(SC->getName());
         DC->setSelectionKind(SC->getSelectionKind());
         GO->setComdat(DC);
       }
     }
   }
 
-  if (!ShouldLink && ForAlias)
+  if (!ShouldLink && ForIndirectSymbol)
     NewGV->setLinkage(GlobalValue::InternalLinkage);
 
   Constant *C = NewGV;
   // Only create a bitcast if necessary. In particular, with
   // DebugTypeODRUniquing we may reach metadata in the destination module
   // containing a GV from the source module, in which case SGV will be
   // the same as DGV and NewGV, and TypeMap.get() will assert since it
   // assumes it is being invoked on a type in the source module.
Error IRLinker::linkFunctionBody(Function &Dst, Function &Src) {
   Dst.stealArgumentListFrom(Src);
   Dst.getBasicBlockList().splice(Dst.end(), Src.getBasicBlockList());
 
   // Everything has been moved over.  Remap it.
   Mapper.scheduleRemapFunction(Dst);
   return Error::success();
 }
 
-void IRLinker::linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src) {
-  Mapper.scheduleMapGlobalAliasee(Dst, *Src.getAliasee(), AliasMCID);
+void IRLinker::linkIndirectSymbolBody(GlobalIndirectSymbol &Dst,
+                                      GlobalIndirectSymbol &Src) {
+  Mapper.scheduleMapGlobalIndirectSymbol(Dst, *Src.getIndirectSymbol(),
+                                         IndirectSymbolMCID);
 }
 
 Error IRLinker::linkGlobalValueBody(GlobalValue &Dst, GlobalValue &Src) {
   if (auto *F = dyn_cast<Function>(&Src))
     return linkFunctionBody(cast<Function>(Dst), *F);
   if (auto *GVar = dyn_cast<GlobalVariable>(&Src)) {
     linkGlobalVariable(cast<GlobalVariable>(Dst), *GVar);
     return Error::success();
   }
-  linkAliasBody(cast<GlobalAlias>(Dst), cast<GlobalAlias>(Src));
+  linkIndirectSymbolBody(cast<GlobalIndirectSymbol>(Dst), cast<GlobalIndirectSymbol>(Src));
   return Error::success();
 }
 
 void IRLinker::prepareCompileUnitsForImport() {
   NamedMDNode *SrcCompileUnits = SrcM->getNamedMetadata("llvm.dbg.cu");
   if (!SrcCompileUnits)
     return;
   // When importing for ThinLTO, prevent importing of types listed on
Error IRLinker::run() {
 
   std::reverse(Worklist.begin(), Worklist.end());
   while (!Worklist.empty()) {
     GlobalValue *GV = Worklist.back();
     Worklist.pop_back();
 
     // Already mapped.
     if (ValueMap.find(GV) != ValueMap.end() ||
-        AliasValueMap.find(GV) != AliasValueMap.end())
+        IndirectSymbolValueMap.find(GV) != IndirectSymbolValueMap.end())
       continue;
 
     assert(!GV->isDeclaration());
     Mapper.mapValue(*GV);
     if (FoundError)
       return std::move(*FoundError);
   }
 

llvm/lib/Transforms/Utils/ValueMapper.cpp

 #include "llvm/IR/Argument.h"
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/CallSite.h"
 #include "llvm/IR/Constant.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DebugInfoMetadata.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/Function.h"
-#include "llvm/IR/GlobalAlias.h"
 #include "llvm/IR/GlobalObject.h"
+#include "llvm/IR/GlobalIndirectSymbol.h"
 #include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/InlineAsm.h"
 #include "llvm/IR/Instruction.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/Metadata.h"
 #include "llvm/IR/Operator.h"
 #include "llvm/IR/Type.h"
 #include "llvm/IR/Value.h"
DelayedBasicBlock(const BlockAddress &Old)
       : OldBB(Old.getBasicBlock()),
         TempBB(BasicBlock::Create(Old.getContext())) {}
 };
 
 struct WorklistEntry {
   enum EntryKind {
     MapGlobalInit,
     MapAppendingVar,
-    MapGlobalAliasee,
+    MapGlobalIndirectSymbol,
     RemapFunction
   };
   struct GVInitTy {
     GlobalVariable *GV;
     Constant *Init;
   };
   struct AppendingGVTy {
     GlobalVariable *GV;
     Constant *InitPrefix;
   };
-  struct GlobalAliaseeTy {
-    GlobalAlias *GA;
-    Constant *Aliasee;
+  struct GlobalIndirectSymbolTy {
+    GlobalIndirectSymbol *GIS;
+    Constant *Target;
   };
 
   unsigned Kind : 2;
   unsigned MCID : 29;
   unsigned AppendingGVIsOldCtorDtor : 1;
   unsigned AppendingGVNumNewMembers;
   union {
     GVInitTy GVInit;
     AppendingGVTy AppendingGV;
-    GlobalAliaseeTy GlobalAliasee;
+    GlobalIndirectSymbolTy GlobalIndirectSymbol;
     Function *RemapF;
   } Data;
 };
 
 struct MappingContext {
   ValueToValueMapTy *VM;
   ValueMaterializer *Materializer = nullptr;
 
public:
   Metadata *mapMetadata(const Metadata *MD);
 
   void scheduleMapGlobalInitializer(GlobalVariable &GV, Constant &Init,
                                     unsigned MCID);
   void scheduleMapAppendingVariable(GlobalVariable &GV, Constant *InitPrefix,
                                     bool IsOldCtorDtor,
                                     ArrayRef<Constant *> NewMembers,
                                     unsigned MCID);
-  void scheduleMapGlobalAliasee(GlobalAlias &GA, Constant &Aliasee,
+  void scheduleMapGlobalIndirectSymbol(GlobalIndirectSymbol &GIS, Constant &Target,
                                        unsigned MCID);
   void scheduleRemapFunction(Function &F, unsigned MCID);
 
   void flush();
 
 private:
   void mapGlobalInitializer(GlobalVariable &GV, Constant &Init);
   void mapAppendingVariable(GlobalVariable &GV, Constant *InitPrefix,
                             bool IsOldCtorDtor,
                             ArrayRef<Constant *> NewMembers);
-  void mapGlobalAliasee(GlobalAlias &GA, Constant &Aliasee);
+  void mapGlobalIndirectSymbol(GlobalIndirectSymbol &GIS, Constant &Target);
   void remapFunction(Function &F, ValueToValueMapTy &VM);
 
   ValueToValueMapTy &getVM() { return *MCs[CurrentMCID].VM; }
   ValueMaterializer *getMaterializer() { return MCs[CurrentMCID].Materializer; }
 
   Value *mapBlockAddress(const BlockAddress &BA);
 
   /// Map metadata that doesn't require visiting operands.
case WorklistEntry::MapAppendingVar: {
       unsigned PrefixSize = AppendingInits.size() - E.AppendingGVNumNewMembers;
       mapAppendingVariable(*E.Data.AppendingGV.GV,
                            E.Data.AppendingGV.InitPrefix,
                            E.AppendingGVIsOldCtorDtor,
                            makeArrayRef(AppendingInits).slice(PrefixSize));
       AppendingInits.resize(PrefixSize);
       break;
     }
-    case WorklistEntry::MapGlobalAliasee:
-      E.Data.GlobalAliasee.GA->setAliasee(
-          mapConstant(E.Data.GlobalAliasee.Aliasee));
+    case WorklistEntry::MapGlobalIndirectSymbol:
+      E.Data.GlobalIndirectSymbol.GIS->setIndirectSymbol(
+          mapConstant(E.Data.GlobalIndirectSymbol.Target));
       break;
     case WorklistEntry::RemapFunction:
       remapFunction(*E.Data.RemapF);
       break;
     }
   }
   CurrentMCID = 0;
 
void Mapper::scheduleMapAppendingVariable(GlobalVariable &GV,
   WE.Data.AppendingGV.GV = &GV;
   WE.Data.AppendingGV.InitPrefix = InitPrefix;
   WE.AppendingGVIsOldCtorDtor = IsOldCtorDtor;
   WE.AppendingGVNumNewMembers = NewMembers.size();
   Worklist.push_back(WE);
   AppendingInits.append(NewMembers.begin(), NewMembers.end());
 }
 
-void Mapper::scheduleMapGlobalAliasee(GlobalAlias &GA, Constant &Aliasee,
-                                      unsigned MCID) {
-  assert(AlreadyScheduled.insert(&GA).second && "Should not reschedule");
+void Mapper::scheduleMapGlobalIndirectSymbol(GlobalIndirectSymbol &GIS,
+                                             Constant &Target, unsigned MCID) {
+  assert(AlreadyScheduled.insert(&GIS).second && "Should not reschedule");
   assert(MCID < MCs.size() && "Invalid mapping context");
 
   WorklistEntry WE;
-  WE.Kind = WorklistEntry::MapGlobalAliasee;
+  WE.Kind = WorklistEntry::MapGlobalIndirectSymbol;
   WE.MCID = MCID;
-  WE.Data.GlobalAliasee.GA = &GA;
-  WE.Data.GlobalAliasee.Aliasee = &Aliasee;
+  WE.Data.GlobalIndirectSymbol.GIS = &GIS;
+  WE.Data.GlobalIndirectSymbol.Target = &Target;
   Worklist.push_back(WE);
 }
 
 void Mapper::scheduleRemapFunction(Function &F, unsigned MCID) {
   assert(AlreadyScheduled.insert(&F).second && "Should not reschedule");
   assert(MCID < MCs.size() && "Invalid mapping context");
 
   WorklistEntry WE;
void ValueMapper::scheduleMapAppendingVariable(GlobalVariable &GV,
                                                Constant *InitPrefix,
                                                bool IsOldCtorDtor,
                                                ArrayRef<Constant *> NewMembers,
                                                unsigned MCID) {
   getAsMapper(pImpl)->scheduleMapAppendingVariable(
       GV, InitPrefix, IsOldCtorDtor, NewMembers, MCID);
 }
 
-void ValueMapper::scheduleMapGlobalAliasee(GlobalAlias &GA, Constant &Aliasee,
+void ValueMapper::scheduleMapGlobalIndirectSymbol(GlobalIndirectSymbol &GIS,
+                                                  Constant &Target,
                                                   unsigned MCID) {
-  getAsMapper(pImpl)->scheduleMapGlobalAliasee(GA, Aliasee, MCID);
+  getAsMapper(pImpl)->scheduleMapGlobalIndirectSymbol(GIS, Target, MCID);
 }
 
 void ValueMapper::scheduleRemapFunction(Function &F, unsigned MCID) {
   getAsMapper(pImpl)->scheduleRemapFunction(F, MCID);
 }

llvm/test/LTO/Resolution/X86/Inputs/ifunc2.ll

+target datalayout = "e-p:64:64"
+target triple = "x86_64-unknown-linux-gnu"
+
+define i32 @foo_resolver() {
+  ret i32 2
+}

llvm/test/LTO/Resolution/X86/ifunc2.ll

+; RUN: llvm-as -o %t1.o %s
+; RUN: llvm-as -o %t2.o %S/Inputs/ifunc2.ll
+; RUN: llvm-lto2 run %t1.o %t2.o -r %t1.o,foo,p -r %t1.o,foo_resolver, -r %t2.o,foo_resolver,p -save-temps -o %t3.o
+; RUN: llvm-dis -o - %t3.o.0.0.preopt.bc | FileCheck %s
+
+target datalayout = "e-p:64:64"
+target triple = "x86_64-unknown-linux-gnu"
+
+; CHECK: @foo = ifunc i32 (), i32 ()* @foo_resolver.2
+@foo = ifunc i32 (), i32 ()* @foo_resolver
+
+; CHECK: define internal i32 @foo_resolver.2() {
+; CHECK-NEXT: ret i32 1
+
+; CHECK: define i32 @foo_resolver() {
+; CHECK-NEXT: ret i32 2
+define weak i32 @foo_resolver() {
+  ret i32 1
+}