X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=blobdiff_plain;f=lib%2FLinker%2FLinkModules.cpp;h=ee41d25ed706118849346b268a8f1c0beace21ca;hp=d1000dc9a9f3a25f1e5ae19a61d6d61e82b1f0d8;hb=73922aaadec0281f9d38fa6640413b0dce260091;hpb=529919ff310cbfce1ba55ea252ff738d5b56b93d diff --git a/lib/Linker/LinkModules.cpp b/lib/Linker/LinkModules.cpp index d1000dc9a9f..ee41d25ed70 100644 --- a/lib/Linker/LinkModules.cpp +++ b/lib/Linker/LinkModules.cpp @@ -365,16 +365,18 @@ 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 { +class ValueMaterializerTy final : public ValueMaterializer { TypeMapTy &TypeMap; Module *DstM; std::vector &LazilyLinkGlobalValues; + ModuleLinker *ModLinker; public: ValueMaterializerTy(TypeMapTy &TypeMap, Module *DstM, - std::vector &LazilyLinkGlobalValues) + std::vector &LazilyLinkGlobalValues, + ModuleLinker *ModLinker) : ValueMaterializer(), TypeMap(TypeMap), DstM(DstM), - LazilyLinkGlobalValues(LazilyLinkGlobalValues) {} + LazilyLinkGlobalValues(LazilyLinkGlobalValues), ModLinker(ModLinker) {} Value *materializeValueFor(Value *V) override; }; @@ -419,20 +421,69 @@ class ModuleLinker { // Vector of GlobalValues to lazily link in. std::vector LazilyLinkGlobalValues; - /// Functions that have replaced other functions. - SmallPtrSet OverridingFunctions; - DiagnosticHandlerFunction DiagnosticHandler; + /// For symbol clashes, prefer those from Src. + unsigned Flags; + + /// Function index passed into ModuleLinker for using in function + /// importing/exporting handling. + FunctionInfoIndex *ImportIndex; + + /// Function to import from source module, all other functions are + /// imported as declarations instead of definitions. + Function *ImportFunction; + + /// Set to true if the given FunctionInfoIndex contains any functions + /// from this source module, in which case we must conservatively assume + /// that any of its functions may be imported into another module + /// as part of a different backend compilation process. + bool HasExportedFunctions; + + /// Set to true when all global value body linking is complete (including + /// lazy linking). Used to prevent metadata linking from creating new + /// references. + bool DoneLinkingBodies; + public: ModuleLinker(Module *dstM, Linker::IdentifiedStructTypeSet &Set, Module *srcM, - DiagnosticHandlerFunction DiagnosticHandler) + DiagnosticHandlerFunction DiagnosticHandler, unsigned Flags, + FunctionInfoIndex *Index = nullptr, + Function *FuncToImport = nullptr) : DstM(dstM), SrcM(srcM), TypeMap(Set), - ValMaterializer(TypeMap, DstM, LazilyLinkGlobalValues), - DiagnosticHandler(DiagnosticHandler) {} + ValMaterializer(TypeMap, DstM, LazilyLinkGlobalValues, this), + DiagnosticHandler(DiagnosticHandler), Flags(Flags), ImportIndex(Index), + ImportFunction(FuncToImport), HasExportedFunctions(false), + DoneLinkingBodies(false) { + assert((ImportIndex || !ImportFunction) && + "Expect a FunctionInfoIndex when importing"); + // If we have a FunctionInfoIndex but no function to import, + // then this is the primary module being compiled in a ThinLTO + // backend compilation, and we need to see if it has functions that + // may be exported to another backend compilation. + if (ImportIndex && !ImportFunction) + HasExportedFunctions = ImportIndex->hasExportedFunctions(SrcM); + } bool run(); + bool shouldOverrideFromSrc() { return Flags & Linker::OverrideFromSrc; } + bool shouldLinkOnlyNeeded() { return Flags & Linker::LinkOnlyNeeded; } + bool shouldInternalizeLinkedSymbols() { + return Flags & Linker::InternalizeLinkedSymbols; + } + + /// Handles cloning of a global values from the source module into + /// the destination module, including setting the attributes and visibility. + GlobalValue *copyGlobalValueProto(TypeMapTy &TypeMap, const GlobalValue *SGV, + const GlobalValue *DGV = nullptr); + + /// Check if we should promote the given local value to global scope. + bool doPromoteLocalToGlobal(const GlobalValue *SGV); + + /// Check if all global value body linking is complete. + bool doneLinkingBodies() { return DoneLinkingBodies; } + private: bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest, const GlobalValue &Src); @@ -458,6 +509,8 @@ private: ComdatsChosen; bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK, bool &LinkFromSrc); + // Keep track of the global value members of each comdat in source. + DenseMap> ComdatMembers; /// Given a global in the source module, return the global in the /// destination module that is being linked to, if any. @@ -499,8 +552,43 @@ private: void linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src); bool linkGlobalValueBody(GlobalValue &Src); + /// Functions that take care of cloning a specific global value type + /// into the destination module. + GlobalVariable *copyGlobalVariableProto(TypeMapTy &TypeMap, + const GlobalVariable *SGVar); + Function *copyFunctionProto(TypeMapTy &TypeMap, const Function *SF); + GlobalValue *copyGlobalAliasProto(TypeMapTy &TypeMap, const GlobalAlias *SGA); + + /// Helper methods to check if we are importing from or potentially + /// exporting from the current source module. + bool isPerformingImport() { return ImportFunction != nullptr; } + bool isModuleExporting() { return HasExportedFunctions; } + + /// If we are importing from the source module, checks if we should + /// import SGV as a definition, otherwise import as a declaration. + bool doImportAsDefinition(const GlobalValue *SGV); + + /// Get the name for SGV that should be used in the linked destination + /// module. Specifically, this handles the case where we need to rename + /// a local that is being promoted to global scope. + std::string getName(const GlobalValue *SGV); + + /// Get the new linkage for SGV that should be used in the linked destination + /// module. Specifically, for ThinLTO importing or exporting it may need + /// to be adjusted. + GlobalValue::LinkageTypes getLinkage(const GlobalValue *SGV); + + /// Copies the necessary global value attributes and name from the source + /// to the newly cloned global value. + void copyGVAttributes(GlobalValue *NewGV, const GlobalValue *SrcGV); + + /// Updates the visibility for the new global cloned from the source + /// and, if applicable, linked with an existing destination global. + /// Handles visibility change required for promoted locals. + void setVisibility(GlobalValue *NewGV, const GlobalValue *SGV, + const GlobalValue *DGV = nullptr); + void linkNamedMDNodes(); - void stripReplacedSubprograms(); }; } @@ -510,6 +598,9 @@ private: 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. + // Note that any required local to global promotion should already be done, + // so promoted locals will not skip this handling as their linkage is no + // longer local. if (GV->hasLocalLinkage() || GV->getName() == Name) return; @@ -527,9 +618,21 @@ static void forceRenaming(GlobalValue *GV, StringRef Name) { /// 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()); +void ModuleLinker::copyGVAttributes(GlobalValue *NewGV, + const GlobalValue *SrcGV) { + auto *GA = dyn_cast(SrcGV); + // Check for the special case of converting an alias (definition) to a + // non-alias (declaration). This can happen when we are importing and + // encounter a weak_any alias (weak_any defs may not be imported, see + // comments in ModuleLinker::getLinkage) or an alias whose base object is + // being imported as a declaration. In that case copy the attributes from the + // base object. + if (GA && !dyn_cast(NewGV)) { + assert(isPerformingImport() && !doImportAsDefinition(GA)); + NewGV->copyAttributesFrom(GA->getBaseObject()); + } else + NewGV->copyAttributesFrom(SrcGV); + forceRenaming(NewGV, getName(SrcGV)); } static bool isLessConstraining(GlobalValue::VisibilityTypes a, @@ -545,17 +648,178 @@ static bool isLessConstraining(GlobalValue::VisibilityTypes a, return false; } +bool ModuleLinker::doImportAsDefinition(const GlobalValue *SGV) { + if (!isPerformingImport()) + return false; + auto *GA = dyn_cast(SGV); + if (GA) { + if (GA->hasWeakAnyLinkage()) + return false; + return doImportAsDefinition(GA->getBaseObject()); + } + // Always import GlobalVariable definitions, except for the special + // case of WeakAny which are imported as ExternalWeak declarations + // (see comments in ModuleLinker::getLinkage). The linkage changes + // described in ModuleLinker::getLinkage ensure the correct behavior (e.g. + // global variables with external linkage are transformed to + // available_externally definitions, which are ultimately turned into + // declarations after the EliminateAvailableExternally pass). + if (dyn_cast(SGV) && !SGV->isDeclaration() && + !SGV->hasWeakAnyLinkage()) + return true; + // Only import the function requested for importing. + auto *SF = dyn_cast(SGV); + if (SF && SF == ImportFunction) + return true; + // Otherwise no. + return false; +} + +bool ModuleLinker::doPromoteLocalToGlobal(const GlobalValue *SGV) { + assert(SGV->hasLocalLinkage()); + // Both the imported references and the original local variable must + // be promoted. + if (!isPerformingImport() && !isModuleExporting()) + return false; + + // Local const variables never need to be promoted unless they are address + // taken. The imported uses can simply use the clone created in this module. + // For now we are conservative in determining which variables are not + // address taken by checking the unnamed addr flag. To be more aggressive, + // the address taken information must be checked earlier during parsing + // of the module and recorded in the function index for use when importing + // from that module. + auto *GVar = dyn_cast(SGV); + if (GVar && GVar->isConstant() && GVar->hasUnnamedAddr()) + return false; + + // Eventually we only need to promote functions in the exporting module that + // are referenced by a potentially exported function (i.e. one that is in the + // function index). + return true; +} + +std::string ModuleLinker::getName(const GlobalValue *SGV) { + // For locals that must be promoted to global scope, ensure that + // the promoted name uniquely identifies the copy in the original module, + // using the ID assigned during combined index creation. When importing, + // we rename all locals (not just those that are promoted) in order to + // avoid naming conflicts between locals imported from different modules. + if (SGV->hasLocalLinkage() && + (doPromoteLocalToGlobal(SGV) || isPerformingImport())) + return FunctionInfoIndex::getGlobalNameForLocal( + SGV->getName(), + ImportIndex->getModuleId(SGV->getParent()->getModuleIdentifier())); + return SGV->getName(); +} + +GlobalValue::LinkageTypes ModuleLinker::getLinkage(const GlobalValue *SGV) { + // Any local variable that is referenced by an exported function needs + // to be promoted to global scope. Since we don't currently know which + // functions reference which local variables/functions, we must treat + // all as potentially exported if this module is exporting anything. + if (isModuleExporting()) { + if (SGV->hasLocalLinkage() && doPromoteLocalToGlobal(SGV)) + return GlobalValue::ExternalLinkage; + return SGV->getLinkage(); + } + + // Otherwise, if we aren't importing, no linkage change is needed. + if (!isPerformingImport()) + return SGV->getLinkage(); + + switch (SGV->getLinkage()) { + case GlobalValue::ExternalLinkage: + // External defnitions are converted to available_externally + // definitions upon import, so that they are available for inlining + // and/or optimization, but are turned into declarations later + // during the EliminateAvailableExternally pass. + if (doImportAsDefinition(SGV) && !dyn_cast(SGV)) + return GlobalValue::AvailableExternallyLinkage; + // An imported external declaration stays external. + return SGV->getLinkage(); + + case GlobalValue::AvailableExternallyLinkage: + // An imported available_externally definition converts + // to external if imported as a declaration. + if (!doImportAsDefinition(SGV)) + return GlobalValue::ExternalLinkage; + // An imported available_externally declaration stays that way. + return SGV->getLinkage(); + + case GlobalValue::LinkOnceAnyLinkage: + case GlobalValue::LinkOnceODRLinkage: + // These both stay the same when importing the definition. + // The ThinLTO pass will eventually force-import their definitions. + return SGV->getLinkage(); + + case GlobalValue::WeakAnyLinkage: + // Can't import weak_any definitions correctly, or we might change the + // program semantics, since the linker will pick the first weak_any + // definition and importing would change the order they are seen by the + // linker. The module linking caller needs to enforce this. + assert(!doImportAsDefinition(SGV)); + // If imported as a declaration, it becomes external_weak. + return GlobalValue::ExternalWeakLinkage; + + case GlobalValue::WeakODRLinkage: + // For weak_odr linkage, there is a guarantee that all copies will be + // equivalent, so the issue described above for weak_any does not exist, + // and the definition can be imported. It can be treated similarly + // to an imported externally visible global value. + if (doImportAsDefinition(SGV) && !dyn_cast(SGV)) + return GlobalValue::AvailableExternallyLinkage; + else + return GlobalValue::ExternalLinkage; + + case GlobalValue::AppendingLinkage: + // It would be incorrect to import an appending linkage variable, + // since it would cause global constructors/destructors to be + // executed multiple times. This should have already been handled + // by linkGlobalValueProto. + llvm_unreachable("Cannot import appending linkage variable"); + + case GlobalValue::InternalLinkage: + case GlobalValue::PrivateLinkage: + // If we are promoting the local to global scope, it is handled + // similarly to a normal externally visible global. + if (doPromoteLocalToGlobal(SGV)) { + if (doImportAsDefinition(SGV) && !dyn_cast(SGV)) + return GlobalValue::AvailableExternallyLinkage; + else + return GlobalValue::ExternalLinkage; + } + // A non-promoted imported local definition stays local. + // The ThinLTO pass will eventually force-import their definitions. + return SGV->getLinkage(); + + case GlobalValue::ExternalWeakLinkage: + // External weak doesn't apply to definitions, must be a declaration. + assert(!doImportAsDefinition(SGV)); + // Linkage stays external_weak. + return SGV->getLinkage(); + + case GlobalValue::CommonLinkage: + // Linkage stays common on definitions. + // The ThinLTO pass will eventually force-import their definitions. + return SGV->getLinkage(); + } + + llvm_unreachable("unknown linkage type"); +} + /// 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) { +GlobalVariable * +ModuleLinker::copyGlobalVariableProto(TypeMapTy &TypeMap, + 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(), + *DstM, TypeMap.get(SGVar->getType()->getElementType()), + SGVar->isConstant(), getLinkage(SGVar), /*init*/ nullptr, getName(SGVar), + /*insertbefore*/ nullptr, SGVar->getThreadLocalMode(), SGVar->getType()->getAddressSpace()); return NewDGV; @@ -563,34 +827,74 @@ static GlobalVariable *copyGlobalVariableProto(TypeMapTy &TypeMap, Module &DstM, /// 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) { +Function *ModuleLinker::copyFunctionProto(TypeMapTy &TypeMap, + 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); + return Function::Create(TypeMap.get(SF->getFunctionType()), getLinkage(SF), + getName(SF), DstM); } /// Set up prototypes for any aliases that come over from the source module. -static GlobalAlias *copyGlobalAliasProto(TypeMapTy &TypeMap, Module &DstM, - const GlobalAlias *SGA) { +GlobalValue *ModuleLinker::copyGlobalAliasProto(TypeMapTy &TypeMap, + const GlobalAlias *SGA) { + // If we are importing and encounter a weak_any alias, or an alias to + // an object being imported as a declaration, we must import the alias + // as a declaration as well, which involves converting it to a non-alias. + // See comments in ModuleLinker::getLinkage for why we cannot import + // weak_any defintions. + if (isPerformingImport() && !doImportAsDefinition(SGA)) { + // Need to convert to declaration. All aliases must be definitions. + const GlobalValue *GVal = SGA->getBaseObject(); + GlobalValue *NewGV; + if (auto *GVar = dyn_cast(GVal)) + NewGV = copyGlobalVariableProto(TypeMap, GVar); + else { + auto *F = dyn_cast(GVal); + assert(F); + NewGV = copyFunctionProto(TypeMap, F); + } + // Set the linkage to External or ExternalWeak (see comments in + // ModuleLinker::getLinkage for why WeakAny is converted to ExternalWeak). + if (SGA->hasWeakAnyLinkage()) + NewGV->setLinkage(GlobalValue::ExternalWeakLinkage); + else + NewGV->setLinkage(GlobalValue::ExternalLinkage); + return NewGV; + } // If there is no linkage to be performed or we're linking from the source, // bring over SGA. - auto *PTy = cast(TypeMap.get(SGA->getType())); - return GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(), - SGA->getLinkage(), SGA->getName(), &DstM); + auto *Ty = TypeMap.get(SGA->getValueType()); + return GlobalAlias::create(Ty, SGA->getType()->getPointerAddressSpace(), + getLinkage(SGA), getName(SGA), DstM); +} + +void ModuleLinker::setVisibility(GlobalValue *NewGV, const GlobalValue *SGV, + const GlobalValue *DGV) { + GlobalValue::VisibilityTypes Visibility = SGV->getVisibility(); + if (DGV) + Visibility = isLessConstraining(Visibility, DGV->getVisibility()) + ? DGV->getVisibility() + : Visibility; + // For promoted locals, mark them hidden so that they can later be + // stripped from the symbol table to reduce bloat. + if (SGV->hasLocalLinkage() && doPromoteLocalToGlobal(SGV)) + Visibility = GlobalValue::HiddenVisibility; + NewGV->setVisibility(Visibility); } -static GlobalValue *copyGlobalValueProto(TypeMapTy &TypeMap, Module &DstM, - const GlobalValue *SGV) { +GlobalValue *ModuleLinker::copyGlobalValueProto(TypeMapTy &TypeMap, + const GlobalValue *SGV, + const GlobalValue *DGV) { GlobalValue *NewGV; if (auto *SGVar = dyn_cast(SGV)) - NewGV = copyGlobalVariableProto(TypeMap, DstM, SGVar); + NewGV = copyGlobalVariableProto(TypeMap, SGVar); else if (auto *SF = dyn_cast(SGV)) - NewGV = copyFunctionProto(TypeMap, DstM, SF); + NewGV = copyFunctionProto(TypeMap, SF); else - NewGV = copyGlobalAliasProto(TypeMap, DstM, cast(SGV)); + NewGV = copyGlobalAliasProto(TypeMap, cast(SGV)); copyGVAttributes(NewGV, SGV); + setVisibility(NewGV, SGV, DGV); return NewGV; } @@ -599,7 +903,13 @@ Value *ValueMaterializerTy::materializeValueFor(Value *V) { if (!SGV) return nullptr; - GlobalValue *DGV = copyGlobalValueProto(TypeMap, *DstM, SGV); + // 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 (ModLinker->doneLinkingBodies()) + return nullptr; + + GlobalValue *DGV = ModLinker->copyGlobalValueProto(TypeMap, SGV); if (Comdat *SC = SGV->getComdat()) { if (auto *DGO = dyn_cast(DGV)) { @@ -725,8 +1035,17 @@ bool ModuleLinker::getComdatResult(const Comdat *SrcC, bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest, const GlobalValue &Src) { + // Should we unconditionally use the Src? + if (shouldOverrideFromSrc()) { + LinkFromSrc = true; + return false; + } + // We always have to add Src if it has appending linkage. if (Src.hasAppendingLinkage()) { + // Caller should have already determined that we can't link from source + // when importing (see comments in linkGlobalValueProto). + assert(!isPerformingImport()); LinkFromSrc = true; return false; } @@ -734,6 +1053,28 @@ bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc, bool SrcIsDeclaration = Src.isDeclarationForLinker(); bool DestIsDeclaration = Dest.isDeclarationForLinker(); + if (isPerformingImport()) { + if (isa(&Src)) { + // For functions, LinkFromSrc iff this is the function requested + // for importing. For variables, decide below normally. + LinkFromSrc = (&Src == ImportFunction); + return false; + } + + // Check if this is an alias with an already existing definition + // in Dest, which must have come from a prior importing pass from + // the same Src module. Unlike imported function and variable + // definitions, which are imported as available_externally and are + // not definitions for the linker, that is not a valid linkage for + // imported aliases which must be definitions. Simply use the existing + // Dest copy. + if (isa(&Src) && !DestIsDeclaration) { + assert(isa(&Dest)); + LinkFromSrc = false; + return false; + } + } + if (SrcIsDeclaration) { // If Src is external or if both Src & Dest are external.. Just link the // external globals, we aren't adding anything. @@ -1025,13 +1366,21 @@ bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) { GlobalValue *DGV = getLinkedToGlobal(SGV); // Handle the ultra special appending linkage case first. + assert(!DGV || SGV->hasAppendingLinkage() == DGV->hasAppendingLinkage()); + if (SGV->hasAppendingLinkage() && isPerformingImport()) { + // Don't want to append to global_ctors list, for example, when we + // are importing for ThinLTO, otherwise the global ctors and dtors + // get executed multiple times for local variables (the latter causing + // double frees). + DoNotLinkFromSource.insert(SGV); + return false; + } if (DGV && DGV->hasAppendingLinkage()) return linkAppendingVarProto(cast(DGV), cast(SGV)); bool LinkFromSrc = true; Comdat *C = nullptr; - GlobalValue::VisibilityTypes Visibility = SGV->getVisibility(); bool HasUnnamedAddr = SGV->hasUnnamedAddr(); if (const Comdat *SC = SGV->getComdat()) { @@ -1039,6 +1388,7 @@ bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) { std::tie(SK, LinkFromSrc) = ComdatsChosen[SC]; C = DstM->getOrInsertComdat(SC->getName()); C->setSelectionKind(SK); + ComdatMembers[SC].push_back(SGV); } else if (DGV) { if (shouldLinkFromSource(LinkFromSrc, *DGV, *SGV)) return true; @@ -1055,12 +1405,8 @@ bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) { ConstantExpr::getBitCast(DGV, TypeMap.get(SGV->getType())); } - if (DGV) { - Visibility = isLessConstraining(Visibility, DGV->getVisibility()) - ? DGV->getVisibility() - : Visibility; + if (DGV) HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr(); - } if (!LinkFromSrc && !DGV) return false; @@ -1068,24 +1414,32 @@ bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) { GlobalValue *NewGV; if (!LinkFromSrc) { NewGV = DGV; + // When linking from source we setVisibility from copyGlobalValueProto. + setVisibility(NewGV, SGV, 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())) { + if (!DGV && !shouldOverrideFromSrc() && SGV != ImportFunction && + (SGV->hasLocalLinkage() || SGV->hasLinkOnceLinkage() || + SGV->hasAvailableExternallyLinkage())) { DoNotLinkFromSource.insert(SGV); return false; } - NewGV = copyGlobalValueProto(TypeMap, *DstM, SGV); + // When we only want to link in unresolved dependencies, blacklist + // the symbol unless unless DestM has a matching declaration (DGV). + if (shouldLinkOnlyNeeded() && !(DGV && DGV->isDeclaration())) { + DoNotLinkFromSource.insert(SGV); + return false; + } + + NewGV = copyGlobalValueProto(TypeMap, SGV, DGV); - if (DGV && isa(DGV)) - if (auto *NewF = dyn_cast(NewGV)) - OverridingFunctions.insert(NewF); + if (isPerformingImport() && !doImportAsDefinition(SGV)) + DoNotLinkFromSource.insert(SGV); } NewGV->setUnnamedAddr(HasUnnamedAddr); - NewGV->setVisibility(Visibility); if (auto *NewGO = dyn_cast(NewGV)) { if (C) @@ -1145,7 +1499,7 @@ void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) { continue; } DstElements.push_back( - MapValue(V, ValueMap, RF_None, &TypeMap, &ValMaterializer)); + MapValue(V, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer)); } if (IsNewStructor) { NewType = ArrayType::get(NewType->getElementType(), DstElements.size()); @@ -1159,8 +1513,8 @@ void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) { /// 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)); + Dst.setInitializer(MapValue(Src.getInitializer(), ValueMap, + RF_MoveDistinctMDs, &TypeMap, &ValMaterializer)); } /// Copy the source function over into the dest function and fix up references @@ -1175,13 +1529,20 @@ bool ModuleLinker::linkFunctionBody(Function &Dst, Function &Src) { // Link in the prefix data. if (Src.hasPrefixData()) - Dst.setPrefixData(MapValue(Src.getPrefixData(), ValueMap, RF_None, &TypeMap, - &ValMaterializer)); + Dst.setPrefixData(MapValue(Src.getPrefixData(), ValueMap, + RF_MoveDistinctMDs, &TypeMap, &ValMaterializer)); // Link in the prologue data. if (Src.hasPrologueData()) - Dst.setPrologueData(MapValue(Src.getPrologueData(), ValueMap, RF_None, - &TypeMap, &ValMaterializer)); + Dst.setPrologueData(MapValue(Src.getPrologueData(), ValueMap, + RF_MoveDistinctMDs, &TypeMap, + &ValMaterializer)); + + // Link in the personality function. + if (Src.hasPersonalityFn()) + Dst.setPersonalityFn(MapValue(Src.getPersonalityFn(), ValueMap, + RF_MoveDistinctMDs, &TypeMap, + &ValMaterializer)); // Go through and convert function arguments over, remembering the mapping. Function::arg_iterator DI = Dst.arg_begin(); @@ -1189,10 +1550,17 @@ bool ModuleLinker::linkFunctionBody(Function &Dst, Function &Src) { DI->setName(Arg.getName()); // Copy the name over. // Add a mapping to our mapping. - ValueMap[&Arg] = DI; + ValueMap[&Arg] = &*DI; ++DI; } + // Copy over the metadata attachments. + SmallVector, 8> MDs; + Src.getAllMetadata(MDs); + for (const auto &I : MDs) + Dst.setMetadata(I.first, MapMetadata(I.second, ValueMap, RF_MoveDistinctMDs, + &TypeMap, &ValMaterializer)); + // Splice the body of the source function into the dest function. Dst.getBasicBlockList().splice(Dst.end(), Src.getBasicBlockList()); @@ -1202,27 +1570,44 @@ bool ModuleLinker::linkFunctionBody(Function &Dst, Function &Src) { // 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, + RemapInstruction(&I, ValueMap, + RF_IgnoreMissingEntries | RF_MoveDistinctMDs, &TypeMap, &ValMaterializer); // There is no need to map the arguments anymore. for (Argument &Arg : Src.args()) ValueMap.erase(&Arg); - Src.Dematerialize(); + Src.dematerialize(); return false; } void ModuleLinker::linkAliasBody(GlobalAlias &Dst, GlobalAlias &Src) { Constant *Aliasee = Src.getAliasee(); - Constant *Val = - MapValue(Aliasee, ValueMap, RF_None, &TypeMap, &ValMaterializer); + Constant *Val = MapValue(Aliasee, ValueMap, RF_MoveDistinctMDs, &TypeMap, + &ValMaterializer); Dst.setAliasee(Val); } bool ModuleLinker::linkGlobalValueBody(GlobalValue &Src) { Value *Dst = ValueMap[&Src]; assert(Dst); + if (const Comdat *SC = Src.getComdat()) { + // To ensure that we don't generate an incomplete comdat group, + // we must materialize and map in any other members that are not + // yet materialized in Dst, which also ensures their definitions + // are linked in. Otherwise, linkonce and other lazy linked GVs will + // not be materialized if they aren't referenced. + for (auto *SGV : ComdatMembers[SC]) { + if (ValueMap[SGV]) + continue; + Value *NewV = ValMaterializer.materializeValueFor(SGV); + ValueMap[SGV] = NewV; + } + } + if (shouldInternalizeLinkedSymbols()) + if (auto *DGV = dyn_cast(Dst)) + DGV->setLinkage(GlobalValue::InternalLinkage); if (auto *F = dyn_cast(&Src)) return linkFunctionBody(cast(*Dst), *F); if (auto *GVar = dyn_cast(&Src)) { @@ -1236,60 +1621,18 @@ bool ModuleLinker::linkGlobalValueBody(GlobalValue &Src) { /// 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) { + for (const NamedMDNode &NMD : SrcM->named_metadata()) { // Don't link module flags here. Do them separately. - if (&*I == SrcModFlags) continue; - NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName()); + if (&NMD == SrcModFlags) + continue; + NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(NMD.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, + for (const MDNode *op : NMD.operands()) + DestNMD->addOperand(MapMetadata(op, ValueMap, RF_MoveDistinctMDs, &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 SPs(CU.getSubprograms()); - assert(SPs && "Expected valid subprogram array"); - - SmallVector 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. @@ -1531,9 +1874,8 @@ bool ModuleLinker::run() { // 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)) + for (GlobalVariable &GV : SrcM->globals()) + if (linkGlobalValueProto(&GV)) return true; // Link the functions together between the two modules, without doing function @@ -1541,26 +1883,25 @@ bool ModuleLinker::run() { // 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)) + for (Function &F :*SrcM) + if (linkGlobalValueProto(&F)) 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)) + for (GlobalAlias &GA : SrcM->aliases()) + if (linkGlobalValueProto(&GA)) return true; - for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i) - linkAppendingVarInit(AppendingVars[i]); + for (const AppendingVarInfo &AppendingVar : AppendingVars) + linkAppendingVarInit(AppendingVar); 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); + if (GV) + MapValue(GV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer); } // Link in the function bodies that are defined in the source module into @@ -1585,18 +1926,6 @@ bool ModuleLinker::run() { 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()) { @@ -1610,12 +1939,32 @@ bool ModuleLinker::run() { while (!LazilyLinkGlobalValues.empty()) { GlobalValue *SGV = LazilyLinkGlobalValues.back(); LazilyLinkGlobalValues.pop_back(); + if (isPerformingImport() && !doImportAsDefinition(SGV)) + continue; + + // Skip declarations that ValueMaterializer may have created in + // case we link in only some of SrcM. + if (shouldLinkOnlyNeeded() && SGV->isDeclaration()) + continue; assert(!SGV->isDeclaration() && "users should not pass down decls"); if (linkGlobalValueBody(*SGV)) return true; } + // Note that we are done linking global value bodies. This prevents + // metadata linking from creating new references. + DoneLinkingBodies = true; + + // 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; + return false; } @@ -1733,17 +2082,15 @@ Linker::Linker(Module *M) { }); } -Linker::~Linker() { -} - void Linker::deleteModule() { delete Composite; Composite = nullptr; } -bool Linker::linkInModule(Module *Src) { +bool Linker::linkInModule(Module *Src, unsigned Flags, FunctionInfoIndex *Index, + Function *FuncToImport) { ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src, - DiagnosticHandler); + DiagnosticHandler, Flags, Index, FuncToImport); bool RetCode = TheLinker.run(); Composite->dropTriviallyDeadConstantArrays(); return RetCode; @@ -1763,14 +2110,15 @@ void Linker::setModule(Module *Dst) { /// 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) { + DiagnosticHandlerFunction DiagnosticHandler, + unsigned Flags) { Linker L(Dest, DiagnosticHandler); - return L.linkInModule(Src); + return L.linkInModule(Src, Flags); } -bool Linker::LinkModules(Module *Dest, Module *Src) { +bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Flags) { Linker L(Dest); - return L.linkInModule(Src); + return L.linkInModule(Src, Flags); } //===----------------------------------------------------------------------===// @@ -1787,7 +2135,9 @@ LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src, LLVMBool Result = Linker::LinkModules( D, unwrap(Src), [&](const DiagnosticInfo &DI) { DI.print(DP); }); - if (OutMessages && Result) + if (OutMessages && Result) { + Stream.flush(); *OutMessages = strdup(Message.c_str()); + } return Result; }