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Diffstat (limited to 'contrib/llvm/lib/Linker/LinkModules.cpp')
| -rw-r--r-- | contrib/llvm/lib/Linker/LinkModules.cpp | 1764 |
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diff --git a/contrib/llvm/lib/Linker/LinkModules.cpp b/contrib/llvm/lib/Linker/LinkModules.cpp new file mode 100644 index 0000000..767d465 --- /dev/null +++ b/contrib/llvm/lib/Linker/LinkModules.cpp @@ -0,0 +1,1764 @@ +//===- lib/Linker/LinkModules.cpp - Module Linker Implementation ----------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements the LLVM module linker. +// +//===----------------------------------------------------------------------===// + +#include "llvm/Linker/Linker.h" +#include "llvm-c/Linker.h" +#include "llvm/ADT/Hashing.h" +#include "llvm/ADT/Optional.h" +#include "llvm/ADT/SetVector.h" +#include "llvm/ADT/SmallString.h" +#include "llvm/ADT/Statistic.h" +#include "llvm/IR/Constants.h" +#include "llvm/IR/DebugInfo.h" +#include "llvm/IR/DiagnosticInfo.h" +#include "llvm/IR/DiagnosticPrinter.h" +#include "llvm/IR/LLVMContext.h" +#include "llvm/IR/Module.h" +#include "llvm/IR/TypeFinder.h" +#include "llvm/Support/CommandLine.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Transforms/Utils/Cloning.h" +#include <cctype> +#include <tuple> +using namespace llvm; + + +//===----------------------------------------------------------------------===// +// TypeMap implementation. +//===----------------------------------------------------------------------===// + +namespace { +class TypeMapTy : public ValueMapTypeRemapper { + /// This is a mapping from a source type to a destination type to use. + DenseMap<Type*, Type*> MappedTypes; + + /// When checking to see if two subgraphs are isomorphic, we speculatively + /// add types to MappedTypes, but keep track of them here in case we need to + /// roll back. + SmallVector<Type*, 16> SpeculativeTypes; + + SmallVector<StructType*, 16> SpeculativeDstOpaqueTypes; + + /// This is a list of non-opaque structs in the source module that are mapped + /// to an opaque struct in the destination module. + SmallVector<StructType*, 16> SrcDefinitionsToResolve; + + /// This is the set of opaque types in the destination modules who are + /// getting a body from the source module. + SmallPtrSet<StructType*, 16> DstResolvedOpaqueTypes; + +public: + TypeMapTy(Linker::IdentifiedStructTypeSet &DstStructTypesSet) + : DstStructTypesSet(DstStructTypesSet) {} + + Linker::IdentifiedStructTypeSet &DstStructTypesSet; + /// Indicate that the specified type in the destination module is conceptually + /// equivalent to the specified type in the source module. + void addTypeMapping(Type *DstTy, Type *SrcTy); + + /// Produce a body for an opaque type in the dest module from a type + /// definition in the source module. + void linkDefinedTypeBodies(); + + /// Return the mapped type to use for the specified input type from the + /// source module. + Type *get(Type *SrcTy); + Type *get(Type *SrcTy, SmallPtrSet<StructType *, 8> &Visited); + + void finishType(StructType *DTy, StructType *STy, ArrayRef<Type *> ETypes); + + FunctionType *get(FunctionType *T) { + return cast<FunctionType>(get((Type *)T)); + } + + /// Dump out the type map for debugging purposes. + void dump() const { + for (auto &Pair : MappedTypes) { + dbgs() << "TypeMap: "; + Pair.first->print(dbgs()); + dbgs() << " => "; + Pair.second->print(dbgs()); + dbgs() << '\n'; + } + } + +private: + Type *remapType(Type *SrcTy) override { return get(SrcTy); } + + bool areTypesIsomorphic(Type *DstTy, Type *SrcTy); +}; +} + +void TypeMapTy::addTypeMapping(Type *DstTy, Type *SrcTy) { + assert(SpeculativeTypes.empty()); + assert(SpeculativeDstOpaqueTypes.empty()); + + // Check to see if these types are recursively isomorphic and establish a + // mapping between them if so. + if (!areTypesIsomorphic(DstTy, SrcTy)) { + // Oops, they aren't isomorphic. Just discard this request by rolling out + // any speculative mappings we've established. + for (Type *Ty : SpeculativeTypes) + MappedTypes.erase(Ty); + + SrcDefinitionsToResolve.resize(SrcDefinitionsToResolve.size() - + SpeculativeDstOpaqueTypes.size()); + for (StructType *Ty : SpeculativeDstOpaqueTypes) + DstResolvedOpaqueTypes.erase(Ty); + } else { + for (Type *Ty : SpeculativeTypes) + if (auto *STy = dyn_cast<StructType>(Ty)) + if (STy->hasName()) + STy->setName(""); + } + SpeculativeTypes.clear(); + SpeculativeDstOpaqueTypes.clear(); +} + +/// Recursively walk this pair of types, returning true if they are isomorphic, +/// false if they are not. +bool TypeMapTy::areTypesIsomorphic(Type *DstTy, Type *SrcTy) { + // Two types with differing kinds are clearly not isomorphic. + if (DstTy->getTypeID() != SrcTy->getTypeID()) + return false; + + // If we have an entry in the MappedTypes table, then we have our answer. + Type *&Entry = MappedTypes[SrcTy]; + if (Entry) + return Entry == DstTy; + + // Two identical types are clearly isomorphic. Remember this + // non-speculatively. + if (DstTy == SrcTy) { + Entry = DstTy; + return true; + } + + // Okay, we have two types with identical kinds that we haven't seen before. + + // If this is an opaque struct type, special case it. + if (StructType *SSTy = dyn_cast<StructType>(SrcTy)) { + // Mapping an opaque type to any struct, just keep the dest struct. + if (SSTy->isOpaque()) { + Entry = DstTy; + SpeculativeTypes.push_back(SrcTy); + return true; + } + + // Mapping a non-opaque source type to an opaque dest. If this is the first + // type that we're mapping onto this destination type then we succeed. Keep + // the dest, but fill it in later. If this is the second (different) type + // that we're trying to map onto the same opaque type then we fail. + if (cast<StructType>(DstTy)->isOpaque()) { + // We can only map one source type onto the opaque destination type. + if (!DstResolvedOpaqueTypes.insert(cast<StructType>(DstTy)).second) + return false; + SrcDefinitionsToResolve.push_back(SSTy); + SpeculativeTypes.push_back(SrcTy); + SpeculativeDstOpaqueTypes.push_back(cast<StructType>(DstTy)); + Entry = DstTy; + return true; + } + } + + // If the number of subtypes disagree between the two types, then we fail. + if (SrcTy->getNumContainedTypes() != DstTy->getNumContainedTypes()) + return false; + + // Fail if any of the extra properties (e.g. array size) of the type disagree. + if (isa<IntegerType>(DstTy)) + return false; // bitwidth disagrees. + if (PointerType *PT = dyn_cast<PointerType>(DstTy)) { + if (PT->getAddressSpace() != cast<PointerType>(SrcTy)->getAddressSpace()) + return false; + + } else if (FunctionType *FT = dyn_cast<FunctionType>(DstTy)) { + if (FT->isVarArg() != cast<FunctionType>(SrcTy)->isVarArg()) + return false; + } else if (StructType *DSTy = dyn_cast<StructType>(DstTy)) { + StructType *SSTy = cast<StructType>(SrcTy); + if (DSTy->isLiteral() != SSTy->isLiteral() || + DSTy->isPacked() != SSTy->isPacked()) + return false; + } else if (ArrayType *DATy = dyn_cast<ArrayType>(DstTy)) { + if (DATy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements()) + return false; + } else if (VectorType *DVTy = dyn_cast<VectorType>(DstTy)) { + if (DVTy->getNumElements() != cast<VectorType>(SrcTy)->getNumElements()) + return false; + } + + // Otherwise, we speculate that these two types will line up and recursively + // check the subelements. + Entry = DstTy; + SpeculativeTypes.push_back(SrcTy); + + for (unsigned I = 0, E = SrcTy->getNumContainedTypes(); I != E; ++I) + if (!areTypesIsomorphic(DstTy->getContainedType(I), + SrcTy->getContainedType(I))) + return false; + + // If everything seems to have lined up, then everything is great. + return true; +} + +void TypeMapTy::linkDefinedTypeBodies() { + SmallVector<Type*, 16> Elements; + for (StructType *SrcSTy : SrcDefinitionsToResolve) { + StructType *DstSTy = cast<StructType>(MappedTypes[SrcSTy]); + assert(DstSTy->isOpaque()); + + // Map the body of the source type over to a new body for the dest type. + Elements.resize(SrcSTy->getNumElements()); + for (unsigned I = 0, E = Elements.size(); I != E; ++I) + Elements[I] = get(SrcSTy->getElementType(I)); + + DstSTy->setBody(Elements, SrcSTy->isPacked()); + } + SrcDefinitionsToResolve.clear(); + DstResolvedOpaqueTypes.clear(); +} + +void TypeMapTy::finishType(StructType *DTy, StructType *STy, + ArrayRef<Type *> ETypes) { + DTy->setBody(ETypes, STy->isPacked()); + + // Steal STy's name. + if (STy->hasName()) { + SmallString<16> TmpName = STy->getName(); + STy->setName(""); + DTy->setName(TmpName); + } + + DstStructTypesSet.addNonOpaque(DTy); +} + +Type *TypeMapTy::get(Type *Ty) { + SmallPtrSet<StructType *, 8> Visited; + return get(Ty, Visited); +} + +Type *TypeMapTy::get(Type *Ty, SmallPtrSet<StructType *, 8> &Visited) { + // If we already have an entry for this type, return it. + Type **Entry = &MappedTypes[Ty]; + if (*Entry) + return *Entry; + + // These are types that LLVM itself will unique. + bool IsUniqued = !isa<StructType>(Ty) || cast<StructType>(Ty)->isLiteral(); + +#ifndef NDEBUG + if (!IsUniqued) { + for (auto &Pair : MappedTypes) { + assert(!(Pair.first != Ty && Pair.second == Ty) && + "mapping to a source type"); + } + } +#endif + + if (!IsUniqued && !Visited.insert(cast<StructType>(Ty)).second) { + StructType *DTy = StructType::create(Ty->getContext()); + return *Entry = DTy; + } + + // If this is not a recursive type, then just map all of the elements and + // then rebuild the type from inside out. + SmallVector<Type *, 4> ElementTypes; + + // If there are no element types to map, then the type is itself. This is + // true for the anonymous {} struct, things like 'float', integers, etc. + if (Ty->getNumContainedTypes() == 0 && IsUniqued) + return *Entry = Ty; + + // Remap all of the elements, keeping track of whether any of them change. + bool AnyChange = false; + ElementTypes.resize(Ty->getNumContainedTypes()); + for (unsigned I = 0, E = Ty->getNumContainedTypes(); I != E; ++I) { + ElementTypes[I] = get(Ty->getContainedType(I), Visited); + AnyChange |= ElementTypes[I] != Ty->getContainedType(I); + } + + // If we found our type while recursively processing stuff, just use it. + Entry = &MappedTypes[Ty]; + if (*Entry) { + if (auto *DTy = dyn_cast<StructType>(*Entry)) { + if (DTy->isOpaque()) { + auto *STy = cast<StructType>(Ty); + finishType(DTy, STy, ElementTypes); + } + } + return *Entry; + } + + // If all of the element types mapped directly over and the type is not + // a nomed struct, then the type is usable as-is. + if (!AnyChange && IsUniqued) + return *Entry = Ty; + + // Otherwise, rebuild a modified type. + switch (Ty->getTypeID()) { + default: + llvm_unreachable("unknown derived type to remap"); + case Type::ArrayTyID: + return *Entry = ArrayType::get(ElementTypes[0], + cast<ArrayType>(Ty)->getNumElements()); + case Type::VectorTyID: + return *Entry = VectorType::get(ElementTypes[0], + cast<VectorType>(Ty)->getNumElements()); + case Type::PointerTyID: + return *Entry = PointerType::get(ElementTypes[0], + cast<PointerType>(Ty)->getAddressSpace()); + case Type::FunctionTyID: + return *Entry = FunctionType::get(ElementTypes[0], + makeArrayRef(ElementTypes).slice(1), + cast<FunctionType>(Ty)->isVarArg()); + case Type::StructTyID: { + auto *STy = cast<StructType>(Ty); + bool IsPacked = STy->isPacked(); + if (IsUniqued) + return *Entry = StructType::get(Ty->getContext(), ElementTypes, IsPacked); + + // If the type is opaque, we can just use it directly. + if (STy->isOpaque()) { + DstStructTypesSet.addOpaque(STy); + return *Entry = Ty; + } + + if (StructType *OldT = + DstStructTypesSet.findNonOpaque(ElementTypes, IsPacked)) { + STy->setName(""); + return *Entry = OldT; + } + + if (!AnyChange) { + DstStructTypesSet.addNonOpaque(STy); + return *Entry = Ty; + } + + StructType *DTy = StructType::create(Ty->getContext()); + finishType(DTy, STy, ElementTypes); + return *Entry = DTy; + } + } +} + +//===----------------------------------------------------------------------===// +// ModuleLinker implementation. +//===----------------------------------------------------------------------===// + +namespace { +class ModuleLinker; + +/// Creates prototypes for functions that are lazily linked on the fly. This +/// speeds up linking for modules with many/ lazily linked functions of which +/// few get used. +class ValueMaterializerTy : public ValueMaterializer { + TypeMapTy &TypeMap; + Module *DstM; + std::vector<GlobalValue *> &LazilyLinkGlobalValues; + +public: + ValueMaterializerTy(TypeMapTy &TypeMap, Module *DstM, + std::vector<GlobalValue *> &LazilyLinkGlobalValues) + : ValueMaterializer(), TypeMap(TypeMap), DstM(DstM), + LazilyLinkGlobalValues(LazilyLinkGlobalValues) {} + + Value *materializeValueFor(Value *V) override; +}; + +class LinkDiagnosticInfo : public DiagnosticInfo { + const Twine &Msg; + +public: + LinkDiagnosticInfo(DiagnosticSeverity Severity, const Twine &Msg); + void print(DiagnosticPrinter &DP) const override; +}; +LinkDiagnosticInfo::LinkDiagnosticInfo(DiagnosticSeverity Severity, + const Twine &Msg) + : DiagnosticInfo(DK_Linker, Severity), Msg(Msg) {} +void LinkDiagnosticInfo::print(DiagnosticPrinter &DP) const { DP << Msg; } + +/// This is an implementation class for the LinkModules function, which is the +/// entrypoint for this file. +class ModuleLinker { + Module *DstM, *SrcM; + + TypeMapTy TypeMap; + ValueMaterializerTy ValMaterializer; + + /// 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; + + struct AppendingVarInfo { + GlobalVariable *NewGV; // New aggregate global in dest module. + const Constant *DstInit; // Old initializer from dest module. + const Constant *SrcInit; // Old initializer from src module. + }; + + std::vector<AppendingVarInfo> AppendingVars; + + // Set of items not to link in from source. + SmallPtrSet<const Value *, 16> DoNotLinkFromSource; + + // Vector of GlobalValues to lazily link in. + std::vector<GlobalValue *> LazilyLinkGlobalValues; + + /// Functions that have replaced other functions. + SmallPtrSet<const Function *, 16> OverridingFunctions; + + DiagnosticHandlerFunction DiagnosticHandler; + +public: + ModuleLinker(Module *dstM, Linker::IdentifiedStructTypeSet &Set, Module *srcM, + DiagnosticHandlerFunction DiagnosticHandler) + : DstM(dstM), SrcM(srcM), TypeMap(Set), + ValMaterializer(TypeMap, DstM, LazilyLinkGlobalValues), + DiagnosticHandler(DiagnosticHandler) {} + + bool run(); + +private: + bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest, + const GlobalValue &Src); + + /// Helper method for setting a message and returning an error code. + bool emitError(const Twine &Message) { + DiagnosticHandler(LinkDiagnosticInfo(DS_Error, Message)); + return true; + } + + void emitWarning(const Twine &Message) { + DiagnosticHandler(LinkDiagnosticInfo(DS_Warning, Message)); + } + + bool getComdatLeader(Module *M, StringRef ComdatName, + const GlobalVariable *&GVar); + bool computeResultingSelectionKind(StringRef ComdatName, + Comdat::SelectionKind Src, + Comdat::SelectionKind Dst, + Comdat::SelectionKind &Result, + bool &LinkFromSrc); + std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>> + ComdatsChosen; + bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK, + bool &LinkFromSrc); + + /// Given a global in the source module, return the global in the + /// destination module that is being linked to, if any. + GlobalValue *getLinkedToGlobal(const GlobalValue *SrcGV) { + // If the source has no name it can't link. If it has local linkage, + // there is no name match-up going on. + if (!SrcGV->hasName() || SrcGV->hasLocalLinkage()) + return nullptr; + + // Otherwise see if we have a match in the destination module's symtab. + GlobalValue *DGV = DstM->getNamedValue(SrcGV->getName()); + if (!DGV) + return nullptr; + + // If we found a global with the same name in the dest module, but it has + // internal linkage, we are really not doing any linkage here. + if (DGV->hasLocalLinkage()) + return nullptr; + + // Otherwise, we do in fact link to the destination global. + return DGV; + } + + void computeTypeMapping(); + + void upgradeMismatchedGlobalArray(StringRef Name); + void upgradeMismatchedGlobals(); + + bool linkAppendingVarProto(GlobalVariable *DstGV, + const GlobalVariable *SrcGV); + + bool linkGlobalValueProto(GlobalValue *GV); + bool linkModuleFlagsMetadata(); + + void linkAppendingVarInit(const AppendingVarInfo &AVI); + + void linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src); + bool linkFunctionBody(Function &Dst, Function &Src); + void linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src); + bool linkGlobalValueBody(GlobalValue &Src); + + void linkNamedMDNodes(); + void stripReplacedSubprograms(); +}; +} + +/// 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, + // there is nothing for us to do. + if (GV->hasLocalLinkage() || GV->getName() == Name) + return; + + Module *M = GV->getParent(); + + // If there is a conflict, rename the conflict. + if (GlobalValue *ConflictGV = M->getNamedValue(Name)) { + GV->takeName(ConflictGV); + ConflictGV->setName(Name); // This will cause ConflictGV to get renamed + assert(ConflictGV->getName() != Name && "forceRenaming didn't work"); + } else { + GV->setName(Name); // Force the name back + } +} + +/// copy additional attributes (those not needed to construct a GlobalValue) +/// from the SrcGV to the DestGV. +static void copyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) { + DestGV->copyAttributesFrom(SrcGV); + forceRenaming(DestGV, SrcGV->getName()); +} + +static bool isLessConstraining(GlobalValue::VisibilityTypes a, + GlobalValue::VisibilityTypes b) { + if (a == GlobalValue::HiddenVisibility) + return false; + if (b == GlobalValue::HiddenVisibility) + return true; + if (a == GlobalValue::ProtectedVisibility) + return false; + if (b == GlobalValue::ProtectedVisibility) + return true; + return false; +} + +/// Loop through the global variables in the src module and merge them into the +/// dest module. +static GlobalVariable *copyGlobalVariableProto(TypeMapTy &TypeMap, Module &DstM, + const GlobalVariable *SGVar) { + // No linking to be performed or linking from the source: simply create an + // identical version of the symbol over in the dest module... the + // initializer will be filled in later by LinkGlobalInits. + GlobalVariable *NewDGV = new GlobalVariable( + DstM, TypeMap.get(SGVar->getType()->getElementType()), + SGVar->isConstant(), SGVar->getLinkage(), /*init*/ nullptr, + SGVar->getName(), /*insertbefore*/ nullptr, SGVar->getThreadLocalMode(), + SGVar->getType()->getAddressSpace()); + + return NewDGV; +} + +/// Link the function in the source module into the destination module if +/// needed, setting up mapping information. +static Function *copyFunctionProto(TypeMapTy &TypeMap, Module &DstM, + const Function *SF) { + // If there is no linkage to be performed or we are linking from the source, + // bring SF over. + return Function::Create(TypeMap.get(SF->getFunctionType()), SF->getLinkage(), + SF->getName(), &DstM); +} + +/// Set up prototypes for any aliases that come over from the source module. +static GlobalAlias *copyGlobalAliasProto(TypeMapTy &TypeMap, Module &DstM, + const GlobalAlias *SGA) { + // If there is no linkage to be performed or we're linking from the source, + // bring over SGA. + auto *PTy = cast<PointerType>(TypeMap.get(SGA->getType())); + return GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(), + SGA->getLinkage(), SGA->getName(), &DstM); +} + +static GlobalValue *copyGlobalValueProto(TypeMapTy &TypeMap, Module &DstM, + const GlobalValue *SGV) { + GlobalValue *NewGV; + if (auto *SGVar = dyn_cast<GlobalVariable>(SGV)) + NewGV = copyGlobalVariableProto(TypeMap, DstM, SGVar); + else if (auto *SF = dyn_cast<Function>(SGV)) + NewGV = copyFunctionProto(TypeMap, DstM, SF); + else + NewGV = copyGlobalAliasProto(TypeMap, DstM, cast<GlobalAlias>(SGV)); + copyGVAttributes(NewGV, SGV); + return NewGV; +} + +Value *ValueMaterializerTy::materializeValueFor(Value *V) { + auto *SGV = dyn_cast<GlobalValue>(V); + if (!SGV) + return nullptr; + + GlobalValue *DGV = copyGlobalValueProto(TypeMap, *DstM, SGV); + + if (Comdat *SC = SGV->getComdat()) { + if (auto *DGO = dyn_cast<GlobalObject>(DGV)) { + Comdat *DC = DstM->getOrInsertComdat(SC->getName()); + DGO->setComdat(DC); + } + } + + LazilyLinkGlobalValues.push_back(SGV); + return DGV; +} + +bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName, + const GlobalVariable *&GVar) { + const GlobalValue *GVal = M->getNamedValue(ComdatName); + if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) { + GVal = GA->getBaseObject(); + if (!GVal) + // We cannot resolve the size of the aliasee yet. + return emitError("Linking COMDATs named '" + ComdatName + + "': COMDAT key involves incomputable alias size."); + } + + GVar = dyn_cast_or_null<GlobalVariable>(GVal); + if (!GVar) + return emitError( + "Linking COMDATs named '" + ComdatName + + "': GlobalVariable required for data dependent selection!"); + + return false; +} + +bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName, + Comdat::SelectionKind Src, + Comdat::SelectionKind Dst, + Comdat::SelectionKind &Result, + bool &LinkFromSrc) { + // The ability to mix Comdat::SelectionKind::Any with + // Comdat::SelectionKind::Largest is a behavior that comes from COFF. + bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any || + Dst == Comdat::SelectionKind::Largest; + bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any || + Src == Comdat::SelectionKind::Largest; + if (DstAnyOrLargest && SrcAnyOrLargest) { + if (Dst == Comdat::SelectionKind::Largest || + Src == Comdat::SelectionKind::Largest) + Result = Comdat::SelectionKind::Largest; + else + Result = Comdat::SelectionKind::Any; + } else if (Src == Dst) { + Result = Dst; + } else { + return emitError("Linking COMDATs named '" + ComdatName + + "': invalid selection kinds!"); + } + + switch (Result) { + case Comdat::SelectionKind::Any: + // Go with Dst. + LinkFromSrc = false; + break; + case Comdat::SelectionKind::NoDuplicates: + return emitError("Linking COMDATs named '" + ComdatName + + "': noduplicates has been violated!"); + case Comdat::SelectionKind::ExactMatch: + case Comdat::SelectionKind::Largest: + case Comdat::SelectionKind::SameSize: { + const GlobalVariable *DstGV; + const GlobalVariable *SrcGV; + if (getComdatLeader(DstM, ComdatName, DstGV) || + getComdatLeader(SrcM, ComdatName, SrcGV)) + return true; + + const DataLayout *DstDL = DstM->getDataLayout(); + const DataLayout *SrcDL = SrcM->getDataLayout(); + if (!DstDL || !SrcDL) { + return emitError( + "Linking COMDATs named '" + ComdatName + + "': can't do size dependent selection without DataLayout!"); + } + uint64_t DstSize = + DstDL->getTypeAllocSize(DstGV->getType()->getPointerElementType()); + uint64_t SrcSize = + SrcDL->getTypeAllocSize(SrcGV->getType()->getPointerElementType()); + if (Result == Comdat::SelectionKind::ExactMatch) { + if (SrcGV->getInitializer() != DstGV->getInitializer()) + return emitError("Linking COMDATs named '" + ComdatName + + "': ExactMatch violated!"); + LinkFromSrc = false; + } else if (Result == Comdat::SelectionKind::Largest) { + LinkFromSrc = SrcSize > DstSize; + } else if (Result == Comdat::SelectionKind::SameSize) { + if (SrcSize != DstSize) + return emitError("Linking COMDATs named '" + ComdatName + + "': SameSize violated!"); + LinkFromSrc = false; + } else { + llvm_unreachable("unknown selection kind"); + } + break; + } + } + + return false; +} + +bool ModuleLinker::getComdatResult(const Comdat *SrcC, + Comdat::SelectionKind &Result, + bool &LinkFromSrc) { + Comdat::SelectionKind SSK = SrcC->getSelectionKind(); + StringRef ComdatName = SrcC->getName(); + Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable(); + Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName); + + if (DstCI == ComdatSymTab.end()) { + // Use the comdat if it is only available in one of the modules. + LinkFromSrc = true; + Result = SSK; + return false; + } + + const Comdat *DstC = &DstCI->second; + Comdat::SelectionKind DSK = DstC->getSelectionKind(); + return computeResultingSelectionKind(ComdatName, SSK, DSK, Result, + LinkFromSrc); +} + +bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc, + const GlobalValue &Dest, + const GlobalValue &Src) { + // We always have to add Src if it has appending linkage. + if (Src.hasAppendingLinkage()) { + LinkFromSrc = true; + return false; + } + + bool SrcIsDeclaration = Src.isDeclarationForLinker(); + bool DestIsDeclaration = Dest.isDeclarationForLinker(); + + if (SrcIsDeclaration) { + // If Src is external or if both Src & Dest are external.. Just link the + // external globals, we aren't adding anything. + if (Src.hasDLLImportStorageClass()) { + // If one of GVs is marked as DLLImport, result should be dllimport'ed. + LinkFromSrc = DestIsDeclaration; + return false; + } + // If the Dest is weak, use the source linkage. + LinkFromSrc = Dest.hasExternalWeakLinkage(); + return false; + } + + if (DestIsDeclaration) { + // If Dest is external but Src is not: + LinkFromSrc = true; + return false; + } + + if (Src.hasCommonLinkage()) { + if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage()) { + LinkFromSrc = true; + return false; + } + + if (!Dest.hasCommonLinkage()) { + LinkFromSrc = false; + return false; + } + + // FIXME: Make datalayout mandatory and just use getDataLayout(). + DataLayout DL(Dest.getParent()); + + uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType()); + uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType()); + LinkFromSrc = SrcSize > DestSize; + return false; + } + + if (Src.isWeakForLinker()) { + assert(!Dest.hasExternalWeakLinkage()); + assert(!Dest.hasAvailableExternallyLinkage()); + + if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage()) { + LinkFromSrc = true; + return false; + } + + LinkFromSrc = false; + return false; + } + + if (Dest.isWeakForLinker()) { + assert(Src.hasExternalLinkage()); + LinkFromSrc = true; + return false; + } + + assert(!Src.hasExternalWeakLinkage()); + assert(!Dest.hasExternalWeakLinkage()); + assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() && + "Unexpected linkage type!"); + return emitError("Linking globals named '" + Src.getName() + + "': symbol multiply defined!"); +} + +/// Loop over all of the linked values to compute type mappings. For example, +/// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct +/// types 'Foo' but one got renamed when the module was loaded into the same +/// LLVMContext. +void ModuleLinker::computeTypeMapping() { + for (GlobalValue &SGV : SrcM->globals()) { + GlobalValue *DGV = getLinkedToGlobal(&SGV); + if (!DGV) + continue; + + if (!DGV->hasAppendingLinkage() || !SGV.hasAppendingLinkage()) { + TypeMap.addTypeMapping(DGV->getType(), SGV.getType()); + continue; + } + + // Unify the element type of appending arrays. + ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType()); + ArrayType *SAT = cast<ArrayType>(SGV.getType()->getElementType()); + TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType()); + } + + for (GlobalValue &SGV : *SrcM) { + if (GlobalValue *DGV = getLinkedToGlobal(&SGV)) + TypeMap.addTypeMapping(DGV->getType(), SGV.getType()); + } + + for (GlobalValue &SGV : SrcM->aliases()) { + if (GlobalValue *DGV = getLinkedToGlobal(&SGV)) + TypeMap.addTypeMapping(DGV->getType(), SGV.getType()); + } + + // Incorporate types by name, scanning all the types in the source module. + // At this point, the destination module may have a type "%foo = { i32 }" for + // example. When the source module got loaded into the same LLVMContext, if + // it had the same type, it would have been renamed to "%foo.42 = { i32 }". + std::vector<StructType *> Types = SrcM->getIdentifiedStructTypes(); + for (StructType *ST : Types) { + if (!ST->hasName()) + continue; + + // Check to see if there is a dot in the name followed by a digit. + size_t DotPos = ST->getName().rfind('.'); + if (DotPos == 0 || DotPos == StringRef::npos || + ST->getName().back() == '.' || + !isdigit(static_cast<unsigned char>(ST->getName()[DotPos + 1]))) + continue; + + // Check to see if the destination module has a struct with the prefix name. + StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos)); + if (!DST) + continue; + + // Don't use it if this actually came from the source module. They're in + // the same LLVMContext after all. Also don't use it unless the type is + // actually used in the destination module. This can happen in situations + // like this: + // + // Module A Module B + // -------- -------- + // %Z = type { %A } %B = type { %C.1 } + // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* } + // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] } + // %C = type { i8* } %B.3 = type { %C.1 } + // + // When we link Module B with Module A, the '%B' in Module B is + // used. However, that would then use '%C.1'. But when we process '%C.1', + // we prefer to take the '%C' version. So we are then left with both + // '%C.1' and '%C' being used for the same types. This leads to some + // variables using one type and some using the other. + if (TypeMap.DstStructTypesSet.hasType(DST)) + TypeMap.addTypeMapping(DST, ST); + } + + // Now that we have discovered all of the type equivalences, get a body for + // any 'opaque' types in the dest module that are now resolved. + TypeMap.linkDefinedTypeBodies(); +} + +static void upgradeGlobalArray(GlobalVariable *GV) { + ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType()); + StructType *OldTy = cast<StructType>(ATy->getElementType()); + assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements"); + + // Get the upgraded 3 element type. + PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo(); + Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1), + VoidPtrTy}; + StructType *NewTy = StructType::get(GV->getContext(), Tys, false); + + // Build new constants with a null third field filled in. + Constant *OldInitC = GV->getInitializer(); + ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC); + if (!OldInit && !isa<ConstantAggregateZero>(OldInitC)) + // Invalid initializer; give up. + return; + std::vector<Constant *> Initializers; + if (OldInit && OldInit->getNumOperands()) { + Value *Null = Constant::getNullValue(VoidPtrTy); + for (Use &U : OldInit->operands()) { + ConstantStruct *Init = cast<ConstantStruct>(U.get()); + Initializers.push_back(ConstantStruct::get( + NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr)); + } + } + assert(Initializers.size() == ATy->getNumElements() && + "Failed to copy all array elements"); + + // Replace the old GV with a new one. + ATy = ArrayType::get(NewTy, Initializers.size()); + Constant *NewInit = ConstantArray::get(ATy, Initializers); + GlobalVariable *NewGV = new GlobalVariable( + *GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "", + GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(), + GV->isExternallyInitialized()); + NewGV->copyAttributesFrom(GV); + NewGV->takeName(GV); + assert(GV->use_empty() && "program cannot use initializer list"); + GV->eraseFromParent(); +} + +void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) { + // Look for the global arrays. + auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM->getNamedValue(Name)); + if (!DstGV) + return; + auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM->getNamedValue(Name)); + if (!SrcGV) + return; + + // Check if the types already match. + auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType()); + auto *SrcTy = + cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType())); + if (DstTy == SrcTy) + return; + + // Grab the element types. We can only upgrade an array of a two-field + // struct. Only bother if the other one has three-fields. + auto *DstEltTy = cast<StructType>(DstTy->getElementType()); + auto *SrcEltTy = cast<StructType>(SrcTy->getElementType()); + if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) { + upgradeGlobalArray(DstGV); + return; + } + if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2) + upgradeGlobalArray(SrcGV); + + // We can't upgrade any other differences. +} + +void ModuleLinker::upgradeMismatchedGlobals() { + upgradeMismatchedGlobalArray("llvm.global_ctors"); + upgradeMismatchedGlobalArray("llvm.global_dtors"); +} + +/// If there were any appending global variables, link them together now. +/// Return true on error. +bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV, + const GlobalVariable *SrcGV) { + + if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage()) + return emitError("Linking globals named '" + SrcGV->getName() + + "': can only link appending global with another appending global!"); + + ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType()); + ArrayType *SrcTy = + cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType())); + Type *EltTy = DstTy->getElementType(); + + // Check to see that they two arrays agree on type. + if (EltTy != SrcTy->getElementType()) + return emitError("Appending variables with different element types!"); + if (DstGV->isConstant() != SrcGV->isConstant()) + return emitError("Appending variables linked with different const'ness!"); + + if (DstGV->getAlignment() != SrcGV->getAlignment()) + return emitError( + "Appending variables with different alignment need to be linked!"); + + if (DstGV->getVisibility() != SrcGV->getVisibility()) + return emitError( + "Appending variables with different visibility need to be linked!"); + + if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr()) + return emitError( + "Appending variables with different unnamed_addr need to be linked!"); + + if (StringRef(DstGV->getSection()) != SrcGV->getSection()) + return emitError( + "Appending variables with different section name need to be linked!"); + + uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements(); + ArrayType *NewType = ArrayType::get(EltTy, NewSize); + + // Create the new global variable. + GlobalVariable *NG = + new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(), + DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV, + DstGV->getThreadLocalMode(), + DstGV->getType()->getAddressSpace()); + + // Propagate alignment, visibility and section info. + copyGVAttributes(NG, DstGV); + + AppendingVarInfo AVI; + AVI.NewGV = NG; + AVI.DstInit = DstGV->getInitializer(); + AVI.SrcInit = SrcGV->getInitializer(); + AppendingVars.push_back(AVI); + + // Replace any uses of the two global variables with uses of the new + // global. + ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType())); + + DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType())); + DstGV->eraseFromParent(); + + // Track the source variable so we don't try to link it. + DoNotLinkFromSource.insert(SrcGV); + + return false; +} + +bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) { + GlobalValue *DGV = getLinkedToGlobal(SGV); + + // Handle the ultra special appending linkage case first. + if (DGV && DGV->hasAppendingLinkage()) + return linkAppendingVarProto(cast<GlobalVariable>(DGV), + cast<GlobalVariable>(SGV)); + + bool LinkFromSrc = true; + Comdat *C = nullptr; + GlobalValue::VisibilityTypes Visibility = SGV->getVisibility(); + bool HasUnnamedAddr = SGV->hasUnnamedAddr(); + + if (const Comdat *SC = SGV->getComdat()) { + Comdat::SelectionKind SK; + std::tie(SK, LinkFromSrc) = ComdatsChosen[SC]; + C = DstM->getOrInsertComdat(SC->getName()); + C->setSelectionKind(SK); + } else if (DGV) { + if (shouldLinkFromSource(LinkFromSrc, *DGV, *SGV)) + return true; + } + + if (!LinkFromSrc) { + // Track the source global so that we don't attempt to copy it over when + // processing global initializers. + DoNotLinkFromSource.insert(SGV); + + if (DGV) + // Make sure to remember this mapping. + ValueMap[SGV] = + ConstantExpr::getBitCast(DGV, TypeMap.get(SGV->getType())); + } + + if (DGV) { + Visibility = isLessConstraining(Visibility, DGV->getVisibility()) + ? DGV->getVisibility() + : Visibility; + HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr(); + } + + if (!LinkFromSrc && !DGV) + return false; + + GlobalValue *NewGV; + if (!LinkFromSrc) { + NewGV = DGV; + } else { + // If the GV is to be lazily linked, don't create it just yet. + // The ValueMaterializerTy will deal with creating it if it's used. + if (!DGV && (SGV->hasLocalLinkage() || SGV->hasLinkOnceLinkage() || + SGV->hasAvailableExternallyLinkage())) { + DoNotLinkFromSource.insert(SGV); + return false; + } + + NewGV = copyGlobalValueProto(TypeMap, *DstM, SGV); + + if (DGV && isa<Function>(DGV)) + if (auto *NewF = dyn_cast<Function>(NewGV)) + OverridingFunctions.insert(NewF); + } + + NewGV->setUnnamedAddr(HasUnnamedAddr); + NewGV->setVisibility(Visibility); + + if (auto *NewGO = dyn_cast<GlobalObject>(NewGV)) { + if (C) + NewGO->setComdat(C); + + if (DGV && DGV->hasCommonLinkage() && SGV->hasCommonLinkage()) + NewGO->setAlignment(std::max(DGV->getAlignment(), SGV->getAlignment())); + } + + if (auto *NewGVar = dyn_cast<GlobalVariable>(NewGV)) { + auto *DGVar = dyn_cast_or_null<GlobalVariable>(DGV); + auto *SGVar = dyn_cast<GlobalVariable>(SGV); + if (DGVar && SGVar && DGVar->isDeclaration() && SGVar->isDeclaration() && + (!DGVar->isConstant() || !SGVar->isConstant())) + NewGVar->setConstant(false); + } + + // Make sure to remember this mapping. + if (NewGV != DGV) { + if (DGV) { + DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewGV, DGV->getType())); + DGV->eraseFromParent(); + } + ValueMap[SGV] = NewGV; + } + + return false; +} + +static void getArrayElements(const Constant *C, + SmallVectorImpl<Constant *> &Dest) { + unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements(); + + for (unsigned i = 0; i != NumElements; ++i) + Dest.push_back(C->getAggregateElement(i)); +} + +void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) { + // Merge the initializer. + SmallVector<Constant *, 16> DstElements; + getArrayElements(AVI.DstInit, DstElements); + + SmallVector<Constant *, 16> SrcElements; + getArrayElements(AVI.SrcInit, SrcElements); + + ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType()); + + StringRef Name = AVI.NewGV->getName(); + bool IsNewStructor = + (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") && + cast<StructType>(NewType->getElementType())->getNumElements() == 3; + + for (auto *V : SrcElements) { + if (IsNewStructor) { + Constant *Key = V->getAggregateElement(2); + if (DoNotLinkFromSource.count(Key)) + continue; + } + DstElements.push_back( + MapValue(V, ValueMap, RF_None, &TypeMap, &ValMaterializer)); + } + if (IsNewStructor) { + NewType = ArrayType::get(NewType->getElementType(), DstElements.size()); + AVI.NewGV->mutateType(PointerType::get(NewType, 0)); + } + + AVI.NewGV->setInitializer(ConstantArray::get(NewType, DstElements)); +} + +/// Update the initializers in the Dest module now that all globals that may be +/// referenced are in Dest. +void ModuleLinker::linkGlobalInit(GlobalVariable &Dst, GlobalVariable &Src) { + // Figure out what the initializer looks like in the dest module. + Dst.setInitializer(MapValue(Src.getInitializer(), ValueMap, RF_None, &TypeMap, + &ValMaterializer)); +} + +/// Copy the source function over into the dest function and fix up references +/// to values. At this point we know that Dest is an external function, and +/// that Src is not. +bool ModuleLinker::linkFunctionBody(Function &Dst, Function &Src) { + assert(Dst.isDeclaration() && !Src.isDeclaration()); + + // Materialize if needed. + if (std::error_code EC = Src.materialize()) + return emitError(EC.message()); + + // Link in the prefix data. + if (Src.hasPrefixData()) + Dst.setPrefixData(MapValue(Src.getPrefixData(), ValueMap, RF_None, &TypeMap, + &ValMaterializer)); + + // Link in the prologue data. + if (Src.hasPrologueData()) + Dst.setPrologueData(MapValue(Src.getPrologueData(), ValueMap, RF_None, + &TypeMap, &ValMaterializer)); + + // Go through and convert function arguments over, remembering the mapping. + Function::arg_iterator DI = Dst.arg_begin(); + for (Argument &Arg : Src.args()) { + DI->setName(Arg.getName()); // Copy the name over. + + // Add a mapping to our mapping. + ValueMap[&Arg] = DI; + ++DI; + } + + // Splice the body of the source function into the dest function. + Dst.getBasicBlockList().splice(Dst.end(), Src.getBasicBlockList()); + + // At this point, all of the instructions and values of the function are now + // copied over. The only problem is that they are still referencing values in + // the Source function as operands. Loop through all of the operands of the + // functions and patch them up to point to the local versions. + for (BasicBlock &BB : Dst) + for (Instruction &I : BB) + RemapInstruction(&I, ValueMap, RF_IgnoreMissingEntries, &TypeMap, + &ValMaterializer); + + // There is no need to map the arguments anymore. + for (Argument &Arg : Src.args()) + ValueMap.erase(&Arg); + + Src.Dematerialize(); + return false; +} + +void ModuleLinker::linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src) { + Constant *Aliasee = Src.getAliasee(); + Constant *Val = + MapValue(Aliasee, ValueMap, RF_None, &TypeMap, &ValMaterializer); + Dst.setAliasee(Val); +} + +bool ModuleLinker::linkGlobalValueBody(GlobalValue &Src) { + Value *Dst = ValueMap[&Src]; + assert(Dst); + if (auto *F = dyn_cast<Function>(&Src)) + return linkFunctionBody(cast<Function>(*Dst), *F); + if (auto *GVar = dyn_cast<GlobalVariable>(&Src)) { + linkGlobalInit(cast<GlobalVariable>(*Dst), *GVar); + return false; + } + linkAliasBody(cast<GlobalAlias>(*Dst), cast<GlobalAlias>(Src)); + return false; +} + +/// Insert all of the named MDNodes in Src into the Dest module. +void ModuleLinker::linkNamedMDNodes() { + const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata(); + for (Module::const_named_metadata_iterator I = SrcM->named_metadata_begin(), + E = SrcM->named_metadata_end(); I != E; ++I) { + // Don't link module flags here. Do them separately. + if (&*I == SrcModFlags) continue; + NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName()); + // Add Src elements into Dest node. + for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) + DestNMD->addOperand(MapMetadata(I->getOperand(i), ValueMap, RF_None, + &TypeMap, &ValMaterializer)); + } +} + +/// Drop DISubprograms that have been superseded. +/// +/// FIXME: this creates an asymmetric result: we strip losing subprograms from +/// DstM, but leave losing subprograms in SrcM. Instead we should also strip +/// losers from SrcM, but this requires extra plumbing in MapMetadata. +void ModuleLinker::stripReplacedSubprograms() { + // Avoid quadratic runtime by returning early when there's nothing to do. + if (OverridingFunctions.empty()) + return; + + // Move the functions now, so the set gets cleared even on early returns. + auto Functions = std::move(OverridingFunctions); + OverridingFunctions.clear(); + + // Drop subprograms whose functions have been overridden by the new compile + // unit. + NamedMDNode *CompileUnits = DstM->getNamedMetadata("llvm.dbg.cu"); + if (!CompileUnits) + return; + for (unsigned I = 0, E = CompileUnits->getNumOperands(); I != E; ++I) { + DICompileUnit CU(CompileUnits->getOperand(I)); + assert(CU && "Expected valid compile unit"); + + DITypedArray<DISubprogram> SPs(CU.getSubprograms()); + assert(SPs && "Expected valid subprogram array"); + + SmallVector<Metadata *, 16> NewSPs; + NewSPs.reserve(SPs.getNumElements()); + for (unsigned S = 0, SE = SPs.getNumElements(); S != SE; ++S) { + DISubprogram SP = SPs.getElement(S); + if (SP && SP.getFunction() && Functions.count(SP.getFunction())) + continue; + + NewSPs.push_back(SP); + } + + // Redirect operand to the overriding subprogram. + if (NewSPs.size() != SPs.getNumElements()) + CU.replaceSubprograms(DIArray(MDNode::get(DstM->getContext(), NewSPs))); + } +} + +/// Merge the linker flags in Src into the Dest module. +bool ModuleLinker::linkModuleFlagsMetadata() { + // If the source module has no module flags, we are done. + const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata(); + if (!SrcModFlags) return false; + + // If the destination module doesn't have module flags yet, then just copy + // over the source module's flags. + NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata(); + if (DstModFlags->getNumOperands() == 0) { + for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) + DstModFlags->addOperand(SrcModFlags->getOperand(I)); + + return false; + } + + // First build a map of the existing module flags and requirements. + DenseMap<MDString *, std::pair<MDNode *, unsigned>> Flags; + SmallSetVector<MDNode*, 16> Requirements; + for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) { + MDNode *Op = DstModFlags->getOperand(I); + ConstantInt *Behavior = mdconst::extract<ConstantInt>(Op->getOperand(0)); + MDString *ID = cast<MDString>(Op->getOperand(1)); + + if (Behavior->getZExtValue() == Module::Require) { + Requirements.insert(cast<MDNode>(Op->getOperand(2))); + } else { + Flags[ID] = std::make_pair(Op, I); + } + } + + // Merge in the flags from the source module, and also collect its set of + // requirements. + bool HasErr = false; + for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) { + MDNode *SrcOp = SrcModFlags->getOperand(I); + ConstantInt *SrcBehavior = + mdconst::extract<ConstantInt>(SrcOp->getOperand(0)); + MDString *ID = cast<MDString>(SrcOp->getOperand(1)); + MDNode *DstOp; + unsigned DstIndex; + std::tie(DstOp, DstIndex) = Flags.lookup(ID); + unsigned SrcBehaviorValue = SrcBehavior->getZExtValue(); + + // If this is a requirement, add it and continue. + if (SrcBehaviorValue == Module::Require) { + // If the destination module does not already have this requirement, add + // it. + if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) { + DstModFlags->addOperand(SrcOp); + } + continue; + } + + // If there is no existing flag with this ID, just add it. + if (!DstOp) { + Flags[ID] = std::make_pair(SrcOp, DstModFlags->getNumOperands()); + DstModFlags->addOperand(SrcOp); + continue; + } + + // Otherwise, perform a merge. + ConstantInt *DstBehavior = + mdconst::extract<ConstantInt>(DstOp->getOperand(0)); + unsigned DstBehaviorValue = DstBehavior->getZExtValue(); + + // If either flag has override behavior, handle it first. + if (DstBehaviorValue == Module::Override) { + // Diagnose inconsistent flags which both have override behavior. + if (SrcBehaviorValue == Module::Override && + SrcOp->getOperand(2) != DstOp->getOperand(2)) { + HasErr |= emitError("linking module flags '" + ID->getString() + + "': IDs have conflicting override values"); + } + continue; + } else if (SrcBehaviorValue == Module::Override) { + // Update the destination flag to that of the source. + DstModFlags->setOperand(DstIndex, SrcOp); + Flags[ID].first = SrcOp; + continue; + } + + // Diagnose inconsistent merge behavior types. + if (SrcBehaviorValue != DstBehaviorValue) { + HasErr |= emitError("linking module flags '" + ID->getString() + + "': IDs have conflicting behaviors"); + continue; + } + + auto replaceDstValue = [&](MDNode *New) { + Metadata *FlagOps[] = {DstOp->getOperand(0), ID, New}; + MDNode *Flag = MDNode::get(DstM->getContext(), FlagOps); + DstModFlags->setOperand(DstIndex, Flag); + Flags[ID].first = Flag; + }; + + // Perform the merge for standard behavior types. + switch (SrcBehaviorValue) { + case Module::Require: + case Module::Override: llvm_unreachable("not possible"); + case Module::Error: { + // Emit an error if the values differ. + if (SrcOp->getOperand(2) != DstOp->getOperand(2)) { + HasErr |= emitError("linking module flags '" + ID->getString() + + "': IDs have conflicting values"); + } + continue; + } + case Module::Warning: { + // Emit a warning if the values differ. + if (SrcOp->getOperand(2) != DstOp->getOperand(2)) { + emitWarning("linking module flags '" + ID->getString() + + "': IDs have conflicting values"); + } + continue; + } + case Module::Append: { + MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2)); + MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2)); + SmallVector<Metadata *, 8> MDs; + MDs.reserve(DstValue->getNumOperands() + SrcValue->getNumOperands()); + for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i) + MDs.push_back(DstValue->getOperand(i)); + for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i) + MDs.push_back(SrcValue->getOperand(i)); + + replaceDstValue(MDNode::get(DstM->getContext(), MDs)); + break; + } + case Module::AppendUnique: { + SmallSetVector<Metadata *, 16> Elts; + MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2)); + MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2)); + for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i) + Elts.insert(DstValue->getOperand(i)); + for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i) + Elts.insert(SrcValue->getOperand(i)); + + replaceDstValue(MDNode::get(DstM->getContext(), + makeArrayRef(Elts.begin(), Elts.end()))); + break; + } + } + } + + // Check all of the requirements. + for (unsigned I = 0, E = Requirements.size(); I != E; ++I) { + MDNode *Requirement = Requirements[I]; + MDString *Flag = cast<MDString>(Requirement->getOperand(0)); + Metadata *ReqValue = Requirement->getOperand(1); + + MDNode *Op = Flags[Flag].first; + if (!Op || Op->getOperand(2) != ReqValue) { + HasErr |= emitError("linking module flags '" + Flag->getString() + + "': does not have the required value"); + continue; + } + } + + return HasErr; +} + +bool ModuleLinker::run() { + assert(DstM && "Null destination module"); + assert(SrcM && "Null source module"); + + // Inherit the target data from the source module if the destination module + // doesn't have one already. + if (!DstM->getDataLayout() && SrcM->getDataLayout()) + DstM->setDataLayout(SrcM->getDataLayout()); + + // Copy the target triple from the source to dest if the dest's is empty. + if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty()) + DstM->setTargetTriple(SrcM->getTargetTriple()); + + if (SrcM->getDataLayout() && DstM->getDataLayout() && + *SrcM->getDataLayout() != *DstM->getDataLayout()) { + emitWarning("Linking two modules of different data layouts: '" + + SrcM->getModuleIdentifier() + "' is '" + + SrcM->getDataLayoutStr() + "' whereas '" + + DstM->getModuleIdentifier() + "' is '" + + DstM->getDataLayoutStr() + "'\n"); + } + if (!SrcM->getTargetTriple().empty() && + DstM->getTargetTriple() != SrcM->getTargetTriple()) { + emitWarning("Linking two modules of different target triples: " + + SrcM->getModuleIdentifier() + "' is '" + + SrcM->getTargetTriple() + "' whereas '" + + DstM->getModuleIdentifier() + "' is '" + + DstM->getTargetTriple() + "'\n"); + } + + // Append the module inline asm string. + if (!SrcM->getModuleInlineAsm().empty()) { + if (DstM->getModuleInlineAsm().empty()) + DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm()); + else + DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+ + SrcM->getModuleInlineAsm()); + } + + // Loop over all of the linked values to compute type mappings. + computeTypeMapping(); + + ComdatsChosen.clear(); + for (const auto &SMEC : SrcM->getComdatSymbolTable()) { + const Comdat &C = SMEC.getValue(); + if (ComdatsChosen.count(&C)) + continue; + Comdat::SelectionKind SK; + bool LinkFromSrc; + if (getComdatResult(&C, SK, LinkFromSrc)) + return true; + ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc); + } + + // Upgrade mismatched global arrays. + upgradeMismatchedGlobals(); + + // Insert all of the globals in src into the DstM module... without linking + // initializers (which could refer to functions not yet mapped over). + for (Module::global_iterator I = SrcM->global_begin(), + E = SrcM->global_end(); I != E; ++I) + if (linkGlobalValueProto(I)) + return true; + + // Link the functions together between the two modules, without doing function + // bodies... this just adds external function prototypes to the DstM + // function... We do this so that when we begin processing function bodies, + // all of the global values that may be referenced are available in our + // ValueMap. + for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I) + if (linkGlobalValueProto(I)) + return true; + + // If there were any aliases, link them now. + for (Module::alias_iterator I = SrcM->alias_begin(), + E = SrcM->alias_end(); I != E; ++I) + if (linkGlobalValueProto(I)) + return true; + + for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i) + linkAppendingVarInit(AppendingVars[i]); + + for (const auto &Entry : DstM->getComdatSymbolTable()) { + const Comdat &C = Entry.getValue(); + if (C.getSelectionKind() == Comdat::Any) + continue; + const GlobalValue *GV = SrcM->getNamedValue(C.getName()); + assert(GV); + MapValue(GV, ValueMap, RF_None, &TypeMap, &ValMaterializer); + } + + // Link in the function bodies that are defined in the source module into + // DstM. + for (Function &SF : *SrcM) { + // Skip if no body (function is external). + if (SF.isDeclaration()) + continue; + + // Skip if not linking from source. + if (DoNotLinkFromSource.count(&SF)) + continue; + + if (linkGlobalValueBody(SF)) + return true; + } + + // Resolve all uses of aliases with aliasees. + for (GlobalAlias &Src : SrcM->aliases()) { + if (DoNotLinkFromSource.count(&Src)) + continue; + linkGlobalValueBody(Src); + } + + // Strip replaced subprograms before linking together compile units. + stripReplacedSubprograms(); + + // Remap all of the named MDNodes in Src into the DstM module. We do this + // after linking GlobalValues so that MDNodes that reference GlobalValues + // are properly remapped. + linkNamedMDNodes(); + + // Merge the module flags into the DstM module. + if (linkModuleFlagsMetadata()) + return true; + + // Update the initializers in the DstM module now that all globals that may + // be referenced are in DstM. + for (GlobalVariable &Src : SrcM->globals()) { + // Only process initialized GV's or ones not already in dest. + if (!Src.hasInitializer() || DoNotLinkFromSource.count(&Src)) + continue; + linkGlobalValueBody(Src); + } + + // Process vector of lazily linked in functions. + while (!LazilyLinkGlobalValues.empty()) { + GlobalValue *SGV = LazilyLinkGlobalValues.back(); + LazilyLinkGlobalValues.pop_back(); + + assert(!SGV->isDeclaration() && "users should not pass down decls"); + if (linkGlobalValueBody(*SGV)) + return true; + } + + return false; +} + +Linker::StructTypeKeyInfo::KeyTy::KeyTy(ArrayRef<Type *> E, bool P) + : ETypes(E), IsPacked(P) {} + +Linker::StructTypeKeyInfo::KeyTy::KeyTy(const StructType *ST) + : ETypes(ST->elements()), IsPacked(ST->isPacked()) {} + +bool Linker::StructTypeKeyInfo::KeyTy::operator==(const KeyTy &That) const { + if (IsPacked != That.IsPacked) + return false; + if (ETypes != That.ETypes) + return false; + return true; +} + +bool Linker::StructTypeKeyInfo::KeyTy::operator!=(const KeyTy &That) const { + return !this->operator==(That); +} + +StructType *Linker::StructTypeKeyInfo::getEmptyKey() { + return DenseMapInfo<StructType *>::getEmptyKey(); +} + +StructType *Linker::StructTypeKeyInfo::getTombstoneKey() { + return DenseMapInfo<StructType *>::getTombstoneKey(); +} + +unsigned Linker::StructTypeKeyInfo::getHashValue(const KeyTy &Key) { + return hash_combine(hash_combine_range(Key.ETypes.begin(), Key.ETypes.end()), + Key.IsPacked); +} + +unsigned Linker::StructTypeKeyInfo::getHashValue(const StructType *ST) { + return getHashValue(KeyTy(ST)); +} + +bool Linker::StructTypeKeyInfo::isEqual(const KeyTy &LHS, + const StructType *RHS) { + if (RHS == getEmptyKey() || RHS == getTombstoneKey()) + return false; + return LHS == KeyTy(RHS); +} + +bool Linker::StructTypeKeyInfo::isEqual(const StructType *LHS, + const StructType *RHS) { + if (RHS == getEmptyKey()) + return LHS == getEmptyKey(); + + if (RHS == getTombstoneKey()) + return LHS == getTombstoneKey(); + + return KeyTy(LHS) == KeyTy(RHS); +} + +void Linker::IdentifiedStructTypeSet::addNonOpaque(StructType *Ty) { + assert(!Ty->isOpaque()); + NonOpaqueStructTypes.insert(Ty); +} + +void Linker::IdentifiedStructTypeSet::addOpaque(StructType *Ty) { + assert(Ty->isOpaque()); + OpaqueStructTypes.insert(Ty); +} + +StructType * +Linker::IdentifiedStructTypeSet::findNonOpaque(ArrayRef<Type *> ETypes, + bool IsPacked) { + Linker::StructTypeKeyInfo::KeyTy Key(ETypes, IsPacked); + auto I = NonOpaqueStructTypes.find_as(Key); + if (I == NonOpaqueStructTypes.end()) + return nullptr; + return *I; +} + +bool Linker::IdentifiedStructTypeSet::hasType(StructType *Ty) { + if (Ty->isOpaque()) + return OpaqueStructTypes.count(Ty); + auto I = NonOpaqueStructTypes.find(Ty); + if (I == NonOpaqueStructTypes.end()) + return false; + return *I == Ty; +} + +void Linker::init(Module *M, DiagnosticHandlerFunction DiagnosticHandler) { + this->Composite = M; + this->DiagnosticHandler = DiagnosticHandler; + + TypeFinder StructTypes; + StructTypes.run(*M, true); + for (StructType *Ty : StructTypes) { + if (Ty->isOpaque()) + IdentifiedStructTypes.addOpaque(Ty); + else + IdentifiedStructTypes.addNonOpaque(Ty); + } +} + +Linker::Linker(Module *M, DiagnosticHandlerFunction DiagnosticHandler) { + init(M, DiagnosticHandler); +} + +Linker::Linker(Module *M) { + init(M, [this](const DiagnosticInfo &DI) { + Composite->getContext().diagnose(DI); + }); +} + +Linker::~Linker() { +} + +void Linker::deleteModule() { + delete Composite; + Composite = nullptr; +} + +bool Linker::linkInModule(Module *Src) { + ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src, + DiagnosticHandler); + return TheLinker.run(); +} + +//===----------------------------------------------------------------------===// +// LinkModules entrypoint. +//===----------------------------------------------------------------------===// + +/// This function links two modules together, with the resulting Dest module +/// modified to be the composite of the two input modules. If an error occurs, +/// true is returned and ErrorMsg (if not null) is set to indicate the problem. +/// Upon failure, the Dest module could be in a modified state, and shouldn't be +/// relied on to be consistent. +bool Linker::LinkModules(Module *Dest, Module *Src, + DiagnosticHandlerFunction DiagnosticHandler) { + Linker L(Dest, DiagnosticHandler); + return L.linkInModule(Src); +} + +bool Linker::LinkModules(Module *Dest, Module *Src) { + Linker L(Dest); + return L.linkInModule(Src); +} + +//===----------------------------------------------------------------------===// +// C API. +//===----------------------------------------------------------------------===// + +LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src, + unsigned Unused, char **OutMessages) { + Module *D = unwrap(Dest); + std::string Message; + raw_string_ostream Stream(Message); + DiagnosticPrinterRawOStream DP(Stream); + + LLVMBool Result = Linker::LinkModules( + D, unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); }); + + if (OutMessages && Result) + *OutMessages = strdup(Message.c_str()); + return Result; +} |
