//===- 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. // // Specifically, this: // * Merges global variables between the two modules // * Uninit + Uninit = Init, Init + Uninit = Init, Init + Init = Error if != // * Merges functions between two modules // //===----------------------------------------------------------------------===// #include "llvm/Linker.h" #include "llvm/Constants.h" #include "llvm/DerivedTypes.h" #include "llvm/LLVMContext.h" #include "llvm/Module.h" #include "llvm/TypeSymbolTable.h" #include "llvm/ValueSymbolTable.h" #include "llvm/Instructions.h" #include "llvm/Assembly/Writer.h" #include "llvm/Support/Streams.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/System/Path.h" #include "llvm/ADT/DenseMap.h" #include using namespace llvm; // Error - Simple wrapper function to conditionally assign to E and return true. // This just makes error return conditions a little bit simpler... static inline bool Error(std::string *E, const Twine &Message) { if (E) *E = Message.str(); return true; } // Function: ResolveTypes() // // Description: // Attempt to link the two specified types together. // // Inputs: // DestTy - The type to which we wish to resolve. // SrcTy - The original type which we want to resolve. // // Outputs: // DestST - The symbol table in which the new type should be placed. // // Return value: // true - There is an error and the types cannot yet be linked. // false - No errors. // static bool ResolveTypes(const Type *DestTy, const Type *SrcTy) { if (DestTy == SrcTy) return false; // If already equal, noop assert(DestTy && SrcTy && "Can't handle null types"); if (const OpaqueType *OT = dyn_cast(DestTy)) { // Type _is_ in module, just opaque... const_cast(OT)->refineAbstractTypeTo(SrcTy); } else if (const OpaqueType *OT = dyn_cast(SrcTy)) { const_cast(OT)->refineAbstractTypeTo(DestTy); } else { return true; // Cannot link types... not-equal and neither is opaque. } return false; } /// LinkerTypeMap - This implements a map of types that is stable /// even if types are resolved/refined to other types. This is not a general /// purpose map, it is specific to the linker's use. namespace { class LinkerTypeMap : public AbstractTypeUser { typedef DenseMap TheMapTy; TheMapTy TheMap; LinkerTypeMap(const LinkerTypeMap&); // DO NOT IMPLEMENT void operator=(const LinkerTypeMap&); // DO NOT IMPLEMENT public: LinkerTypeMap() {} ~LinkerTypeMap() { for (DenseMap::iterator I = TheMap.begin(), E = TheMap.end(); I != E; ++I) I->first->removeAbstractTypeUser(this); } /// lookup - Return the value for the specified type or null if it doesn't /// exist. const Type *lookup(const Type *Ty) const { TheMapTy::const_iterator I = TheMap.find(Ty); if (I != TheMap.end()) return I->second; return 0; } /// erase - Remove the specified type, returning true if it was in the set. bool erase(const Type *Ty) { if (!TheMap.erase(Ty)) return false; if (Ty->isAbstract()) Ty->removeAbstractTypeUser(this); return true; } /// insert - This returns true if the pointer was new to the set, false if it /// was already in the set. bool insert(const Type *Src, const Type *Dst) { if (!TheMap.insert(std::make_pair(Src, PATypeHolder(Dst))).second) return false; // Already in map. if (Src->isAbstract()) Src->addAbstractTypeUser(this); return true; } protected: /// refineAbstractType - The callback method invoked when an abstract type is /// resolved to another type. An object must override this method to update /// its internal state to reference NewType instead of OldType. /// virtual void refineAbstractType(const DerivedType *OldTy, const Type *NewTy) { TheMapTy::iterator I = TheMap.find(OldTy); const Type *DstTy = I->second; TheMap.erase(I); if (OldTy->isAbstract()) OldTy->removeAbstractTypeUser(this); // Don't reinsert into the map if the key is concrete now. if (NewTy->isAbstract()) insert(NewTy, DstTy); } /// The other case which AbstractTypeUsers must be aware of is when a type /// makes the transition from being abstract (where it has clients on it's /// AbstractTypeUsers list) to concrete (where it does not). This method /// notifies ATU's when this occurs for a type. virtual void typeBecameConcrete(const DerivedType *AbsTy) { TheMap.erase(AbsTy); AbsTy->removeAbstractTypeUser(this); } // for debugging... virtual void dump() const { cerr << "AbstractTypeSet!\n"; } }; } // RecursiveResolveTypes - This is just like ResolveTypes, except that it // recurses down into derived types, merging the used types if the parent types // are compatible. static bool RecursiveResolveTypesI(const Type *DstTy, const Type *SrcTy, LinkerTypeMap &Pointers) { if (DstTy == SrcTy) return false; // If already equal, noop // If we found our opaque type, resolve it now! if (isa(DstTy) || isa(SrcTy)) return ResolveTypes(DstTy, SrcTy); // Two types cannot be resolved together if they are of different primitive // type. For example, we cannot resolve an int to a float. if (DstTy->getTypeID() != SrcTy->getTypeID()) return true; // If neither type is abstract, then they really are just different types. if (!DstTy->isAbstract() && !SrcTy->isAbstract()) return true; // Otherwise, resolve the used type used by this derived type... switch (DstTy->getTypeID()) { default: return true; case Type::FunctionTyID: { const FunctionType *DstFT = cast(DstTy); const FunctionType *SrcFT = cast(SrcTy); if (DstFT->isVarArg() != SrcFT->isVarArg() || DstFT->getNumContainedTypes() != SrcFT->getNumContainedTypes()) return true; // Use TypeHolder's so recursive resolution won't break us. PATypeHolder ST(SrcFT), DT(DstFT); for (unsigned i = 0, e = DstFT->getNumContainedTypes(); i != e; ++i) { const Type *SE = ST->getContainedType(i), *DE = DT->getContainedType(i); if (SE != DE && RecursiveResolveTypesI(DE, SE, Pointers)) return true; } return false; } case Type::StructTyID: { const StructType *DstST = cast(DstTy); const StructType *SrcST = cast(SrcTy); if (DstST->getNumContainedTypes() != SrcST->getNumContainedTypes()) return true; PATypeHolder ST(SrcST), DT(DstST); for (unsigned i = 0, e = DstST->getNumContainedTypes(); i != e; ++i) { const Type *SE = ST->getContainedType(i), *DE = DT->getContainedType(i); if (SE != DE && RecursiveResolveTypesI(DE, SE, Pointers)) return true; } return false; } case Type::ArrayTyID: { const ArrayType *DAT = cast(DstTy); const ArrayType *SAT = cast(SrcTy); if (DAT->getNumElements() != SAT->getNumElements()) return true; return RecursiveResolveTypesI(DAT->getElementType(), SAT->getElementType(), Pointers); } case Type::VectorTyID: { const VectorType *DVT = cast(DstTy); const VectorType *SVT = cast(SrcTy); if (DVT->getNumElements() != SVT->getNumElements()) return true; return RecursiveResolveTypesI(DVT->getElementType(), SVT->getElementType(), Pointers); } case Type::PointerTyID: { const PointerType *DstPT = cast(DstTy); const PointerType *SrcPT = cast(SrcTy); if (DstPT->getAddressSpace() != SrcPT->getAddressSpace()) return true; // If this is a pointer type, check to see if we have already seen it. If // so, we are in a recursive branch. Cut off the search now. We cannot use // an associative container for this search, because the type pointers (keys // in the container) change whenever types get resolved. if (SrcPT->isAbstract()) if (const Type *ExistingDestTy = Pointers.lookup(SrcPT)) return ExistingDestTy != DstPT; if (DstPT->isAbstract()) if (const Type *ExistingSrcTy = Pointers.lookup(DstPT)) return ExistingSrcTy != SrcPT; // Otherwise, add the current pointers to the vector to stop recursion on // this pair. if (DstPT->isAbstract()) Pointers.insert(DstPT, SrcPT); if (SrcPT->isAbstract()) Pointers.insert(SrcPT, DstPT); return RecursiveResolveTypesI(DstPT->getElementType(), SrcPT->getElementType(), Pointers); } } } static bool RecursiveResolveTypes(const Type *DestTy, const Type *SrcTy) { LinkerTypeMap PointerTypes; return RecursiveResolveTypesI(DestTy, SrcTy, PointerTypes); } // LinkTypes - Go through the symbol table of the Src module and see if any // types are named in the src module that are not named in the Dst module. // Make sure there are no type name conflicts. static bool LinkTypes(Module *Dest, const Module *Src, std::string *Err) { TypeSymbolTable *DestST = &Dest->getTypeSymbolTable(); const TypeSymbolTable *SrcST = &Src->getTypeSymbolTable(); // Look for a type plane for Type's... TypeSymbolTable::const_iterator TI = SrcST->begin(); TypeSymbolTable::const_iterator TE = SrcST->end(); if (TI == TE) return false; // No named types, do nothing. // Some types cannot be resolved immediately because they depend on other // types being resolved to each other first. This contains a list of types we // are waiting to recheck. std::vector DelayedTypesToResolve; for ( ; TI != TE; ++TI ) { const std::string &Name = TI->first; const Type *RHS = TI->second; // Check to see if this type name is already in the dest module. Type *Entry = DestST->lookup(Name); // If the name is just in the source module, bring it over to the dest. if (Entry == 0) { if (!Name.empty()) DestST->insert(Name, const_cast(RHS)); } else if (ResolveTypes(Entry, RHS)) { // They look different, save the types 'till later to resolve. DelayedTypesToResolve.push_back(Name); } } // Iteratively resolve types while we can... while (!DelayedTypesToResolve.empty()) { // Loop over all of the types, attempting to resolve them if possible... unsigned OldSize = DelayedTypesToResolve.size(); // Try direct resolution by name... for (unsigned i = 0; i != DelayedTypesToResolve.size(); ++i) { const std::string &Name = DelayedTypesToResolve[i]; Type *T1 = SrcST->lookup(Name); Type *T2 = DestST->lookup(Name); if (!ResolveTypes(T2, T1)) { // We are making progress! DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i); --i; } } // Did we not eliminate any types? if (DelayedTypesToResolve.size() == OldSize) { // Attempt to resolve subelements of types. This allows us to merge these // two types: { int* } and { opaque* } for (unsigned i = 0, e = DelayedTypesToResolve.size(); i != e; ++i) { const std::string &Name = DelayedTypesToResolve[i]; if (!RecursiveResolveTypes(SrcST->lookup(Name), DestST->lookup(Name))) { // We are making progress! DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i); // Go back to the main loop, perhaps we can resolve directly by name // now... break; } } // If we STILL cannot resolve the types, then there is something wrong. if (DelayedTypesToResolve.size() == OldSize) { // Remove the symbol name from the destination. DelayedTypesToResolve.pop_back(); } } } return false; } #ifndef NDEBUG static void PrintMap(const std::map &M) { for (std::map::const_iterator I = M.begin(), E =M.end(); I != E; ++I) { cerr << " Fr: " << (void*)I->first << " "; I->first->dump(); cerr << " To: " << (void*)I->second << " "; I->second->dump(); cerr << "\n"; } } #endif // RemapOperand - Use ValueMap to convert constants from one module to another. static Value *RemapOperand(const Value *In, std::map &ValueMap, LLVMContext &Context) { std::map::const_iterator I = ValueMap.find(In); if (I != ValueMap.end()) return I->second; // Check to see if it's a constant that we are interested in transforming. Value *Result = 0; if (const Constant *CPV = dyn_cast(In)) { if ((!isa(CPV->getType()) && !isa(CPV)) || isa(CPV) || isa(CPV)) return const_cast(CPV); // Simple constants stay identical. if (const ConstantArray *CPA = dyn_cast(CPV)) { std::vector Operands(CPA->getNumOperands()); for (unsigned i = 0, e = CPA->getNumOperands(); i != e; ++i) Operands[i] =cast(RemapOperand(CPA->getOperand(i), ValueMap, Context)); Result = Context.getConstantArray(cast(CPA->getType()), Operands); } else if (const ConstantStruct *CPS = dyn_cast(CPV)) { std::vector Operands(CPS->getNumOperands()); for (unsigned i = 0, e = CPS->getNumOperands(); i != e; ++i) Operands[i] =cast(RemapOperand(CPS->getOperand(i), ValueMap, Context)); Result = Context.getConstantStruct(cast(CPS->getType()), Operands); } else if (isa(CPV) || isa(CPV)) { Result = const_cast(CPV); } else if (const ConstantVector *CP = dyn_cast(CPV)) { std::vector Operands(CP->getNumOperands()); for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i) Operands[i] = cast(RemapOperand(CP->getOperand(i), ValueMap, Context)); Result = Context.getConstantVector(Operands); } else if (const ConstantExpr *CE = dyn_cast(CPV)) { std::vector Ops; for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i) Ops.push_back(cast(RemapOperand(CE->getOperand(i),ValueMap, Context))); Result = CE->getWithOperands(Ops); } else { assert(!isa(CPV) && "Unmapped global?"); llvm_unreachable("Unknown type of derived type constant value!"); } } else if (isa(In)) { Result = const_cast(In); } // Cache the mapping in our local map structure if (Result) { ValueMap[In] = Result; return Result; } #ifndef NDEBUG cerr << "LinkModules ValueMap: \n"; PrintMap(ValueMap); cerr << "Couldn't remap value: " << (void*)In << " " << *In << "\n"; llvm_unreachable("Couldn't remap value!"); #endif return 0; } /// ForceRenaming - 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, const std::string &Name) { assert(GV->getName() != Name && "Can't force rename to self"); ValueSymbolTable &ST = GV->getParent()->getValueSymbolTable(); // If there is a conflict, rename the conflict. if (GlobalValue *ConflictGV = cast_or_null(ST.lookup(Name))) { assert(ConflictGV->hasLocalLinkage() && "Not conflicting with a static global, should link instead!"); 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 } } /// CopyGVAttributes - copy additional attributes (those not needed to construct /// a GlobalValue) from the SrcGV to the DestGV. static void CopyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) { // Use the maximum alignment, rather than just copying the alignment of SrcGV. unsigned Alignment = std::max(DestGV->getAlignment(), SrcGV->getAlignment()); DestGV->copyAttributesFrom(SrcGV); DestGV->setAlignment(Alignment); } /// GetLinkageResult - This analyzes the two global values and determines what /// the result will look like in the destination module. In particular, it /// computes the resultant linkage type, computes whether the global in the /// source should be copied over to the destination (replacing the existing /// one), and computes whether this linkage is an error or not. It also performs /// visibility checks: we cannot link together two symbols with different /// visibilities. static bool GetLinkageResult(GlobalValue *Dest, const GlobalValue *Src, GlobalValue::LinkageTypes <, bool &LinkFromSrc, std::string *Err) { assert((!Dest || !Src->hasLocalLinkage()) && "If Src has internal linkage, Dest shouldn't be set!"); if (!Dest) { // Linking something to nothing. LinkFromSrc = true; LT = Src->getLinkage(); } else if (Src->isDeclaration()) { // If Src is external or if both Src & Dest are external.. Just link the // external globals, we aren't adding anything. if (Src->hasDLLImportLinkage()) { // If one of GVs has DLLImport linkage, result should be dllimport'ed. if (Dest->isDeclaration()) { LinkFromSrc = true; LT = Src->getLinkage(); } } else if (Dest->hasExternalWeakLinkage()) { // If the Dest is weak, use the source linkage. LinkFromSrc = true; LT = Src->getLinkage(); } else { LinkFromSrc = false; LT = Dest->getLinkage(); } } else if (Dest->isDeclaration() && !Dest->hasDLLImportLinkage()) { // If Dest is external but Src is not: LinkFromSrc = true; LT = Src->getLinkage(); } else if (Src->hasAppendingLinkage() || Dest->hasAppendingLinkage()) { if (Src->getLinkage() != Dest->getLinkage()) return Error(Err, "Linking globals named '" + Src->getName() + "': can only link appending global with another appending global!"); LinkFromSrc = true; // Special cased. LT = Src->getLinkage(); } else if (Src->isWeakForLinker()) { // At this point we know that Dest has LinkOnce, External*, Weak, Common, // or DLL* linkage. if (Dest->hasExternalWeakLinkage() || Dest->hasAvailableExternallyLinkage() || (Dest->hasLinkOnceLinkage() && (Src->hasWeakLinkage() || Src->hasCommonLinkage()))) { LinkFromSrc = true; LT = Src->getLinkage(); } else { LinkFromSrc = false; LT = Dest->getLinkage(); } } else if (Dest->isWeakForLinker()) { // At this point we know that Src has External* or DLL* linkage. if (Src->hasExternalWeakLinkage()) { LinkFromSrc = false; LT = Dest->getLinkage(); } else { LinkFromSrc = true; LT = GlobalValue::ExternalLinkage; } } else { assert((Dest->hasExternalLinkage() || Dest->hasDLLImportLinkage() || Dest->hasDLLExportLinkage() || Dest->hasExternalWeakLinkage()) && (Src->hasExternalLinkage() || Src->hasDLLImportLinkage() || Src->hasDLLExportLinkage() || Src->hasExternalWeakLinkage()) && "Unexpected linkage type!"); return Error(Err, "Linking globals named '" + Src->getName() + "': symbol multiply defined!"); } // Check visibility if (Dest && Src->getVisibility() != Dest->getVisibility()) if (!Src->isDeclaration() && !Dest->isDeclaration()) return Error(Err, "Linking globals named '" + Src->getName() + "': symbols have different visibilities!"); return false; } // LinkGlobals - Loop through the global variables in the src module and merge // them into the dest module. static bool LinkGlobals(Module *Dest, const Module *Src, std::map &ValueMap, std::multimap &AppendingVars, std::string *Err) { ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable(); LLVMContext &Context = Dest->getContext(); // Loop over all of the globals in the src module, mapping them over as we go for (Module::const_global_iterator I = Src->global_begin(), E = Src->global_end(); I != E; ++I) { const GlobalVariable *SGV = I; GlobalValue *DGV = 0; // Check to see if may have to link the global with the global, alias or // function. if (SGV->hasName() && !SGV->hasLocalLinkage()) DGV = cast_or_null(DestSymTab.lookup(SGV->getName())); // 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 && DGV->hasLocalLinkage()) DGV = 0; // If types don't agree due to opaque types, try to resolve them. if (DGV && DGV->getType() != SGV->getType()) RecursiveResolveTypes(SGV->getType(), DGV->getType()); assert((SGV->hasInitializer() || SGV->hasExternalWeakLinkage() || SGV->hasExternalLinkage() || SGV->hasDLLImportLinkage()) && "Global must either be external or have an initializer!"); GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; bool LinkFromSrc = false; if (GetLinkageResult(DGV, SGV, NewLinkage, LinkFromSrc, Err)) return true; if (DGV == 0) { // No linking to be performed, 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(*Dest, SGV->getType()->getElementType(), SGV->isConstant(), SGV->getLinkage(), /*init*/0, SGV->getName(), 0, false, SGV->getType()->getAddressSpace()); // Propagate alignment, visibility and section info. CopyGVAttributes(NewDGV, SGV); // If the LLVM runtime renamed the global, but it is an externally visible // symbol, DGV must be an existing global with internal linkage. Rename // it. if (!NewDGV->hasLocalLinkage() && NewDGV->getName() != SGV->getName()) ForceRenaming(NewDGV, SGV->getName()); // Make sure to remember this mapping. ValueMap[SGV] = NewDGV; // Keep track that this is an appending variable. if (SGV->hasAppendingLinkage()) AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV)); continue; } // If the visibilities of the symbols disagree and the destination is a // prototype, take the visibility of its input. if (DGV->isDeclaration()) DGV->setVisibility(SGV->getVisibility()); if (DGV->hasAppendingLinkage()) { // No linking is performed yet. Just insert a new copy of the global, and // keep track of the fact that it is an appending variable in the // AppendingVars map. The name is cleared out so that no linkage is // performed. GlobalVariable *NewDGV = new GlobalVariable(*Dest, SGV->getType()->getElementType(), SGV->isConstant(), SGV->getLinkage(), /*init*/0, "", 0, false, SGV->getType()->getAddressSpace()); // Set alignment allowing CopyGVAttributes merge it with alignment of SGV. NewDGV->setAlignment(DGV->getAlignment()); // Propagate alignment, section and visibility info. CopyGVAttributes(NewDGV, SGV); // Make sure to remember this mapping... ValueMap[SGV] = NewDGV; // Keep track that this is an appending variable... AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV)); continue; } if (LinkFromSrc) { if (isa(DGV)) return Error(Err, "Global-Alias Collision on '" + SGV->getName() + "': symbol multiple defined"); // If the types don't match, and if we are to link from the source, nuke // DGV and create a new one of the appropriate type. Note that the thing // we are replacing may be a function (if a prototype, weak, etc) or a // global variable. GlobalVariable *NewDGV = new GlobalVariable(*Dest, SGV->getType()->getElementType(), SGV->isConstant(), NewLinkage, /*init*/0, DGV->getName(), 0, false, SGV->getType()->getAddressSpace()); // Propagate alignment, section, and visibility info. CopyGVAttributes(NewDGV, SGV); DGV->replaceAllUsesWith(Context.getConstantExprBitCast(NewDGV, DGV->getType())); // DGV will conflict with NewDGV because they both had the same // name. We must erase this now so ForceRenaming doesn't assert // because DGV might not have internal linkage. if (GlobalVariable *Var = dyn_cast(DGV)) Var->eraseFromParent(); else cast(DGV)->eraseFromParent(); DGV = NewDGV; // If the symbol table renamed the global, but it is an externally visible // symbol, DGV must be an existing global with internal linkage. Rename. if (NewDGV->getName() != SGV->getName() && !NewDGV->hasLocalLinkage()) ForceRenaming(NewDGV, SGV->getName()); // Inherit const as appropriate. NewDGV->setConstant(SGV->isConstant()); // Make sure to remember this mapping. ValueMap[SGV] = NewDGV; continue; } // Not "link from source", keep the one in the DestModule and remap the // input onto it. // Special case for const propagation. if (GlobalVariable *DGVar = dyn_cast(DGV)) if (DGVar->isDeclaration() && SGV->isConstant() && !DGVar->isConstant()) DGVar->setConstant(true); // SGV is global, but DGV is alias. if (isa(DGV)) { // The only valid mappings are: // - SGV is external declaration, which is effectively a no-op. // - SGV is weak, when we just need to throw SGV out. if (!SGV->isDeclaration() && !SGV->isWeakForLinker()) return Error(Err, "Global-Alias Collision on '" + SGV->getName() + "': symbol multiple defined"); } // Set calculated linkage DGV->setLinkage(NewLinkage); // Make sure to remember this mapping... ValueMap[SGV] = Context.getConstantExprBitCast(DGV, SGV->getType()); } return false; } static GlobalValue::LinkageTypes CalculateAliasLinkage(const GlobalValue *SGV, const GlobalValue *DGV) { GlobalValue::LinkageTypes SL = SGV->getLinkage(); GlobalValue::LinkageTypes DL = DGV->getLinkage(); if (SL == GlobalValue::ExternalLinkage || DL == GlobalValue::ExternalLinkage) return GlobalValue::ExternalLinkage; else if (SL == GlobalValue::WeakAnyLinkage || DL == GlobalValue::WeakAnyLinkage) return GlobalValue::WeakAnyLinkage; else if (SL == GlobalValue::WeakODRLinkage || DL == GlobalValue::WeakODRLinkage) return GlobalValue::WeakODRLinkage; else if (SL == GlobalValue::InternalLinkage && DL == GlobalValue::InternalLinkage) return GlobalValue::InternalLinkage; else if (SL == GlobalValue::LinkerPrivateLinkage && DL == GlobalValue::LinkerPrivateLinkage) return GlobalValue::LinkerPrivateLinkage; else { assert (SL == GlobalValue::PrivateLinkage && DL == GlobalValue::PrivateLinkage && "Unexpected linkage type"); return GlobalValue::PrivateLinkage; } } // LinkAlias - Loop through the alias in the src module and link them into the // dest module. We're assuming, that all functions/global variables were already // linked in. static bool LinkAlias(Module *Dest, const Module *Src, std::map &ValueMap, std::string *Err) { LLVMContext &Context = Dest->getContext(); // Loop over all alias in the src module for (Module::const_alias_iterator I = Src->alias_begin(), E = Src->alias_end(); I != E; ++I) { const GlobalAlias *SGA = I; const GlobalValue *SAliasee = SGA->getAliasedGlobal(); GlobalAlias *NewGA = NULL; // Globals were already linked, thus we can just query ValueMap for variant // of SAliasee in Dest. std::map::const_iterator VMI = ValueMap.find(SAliasee); assert(VMI != ValueMap.end() && "Aliasee not linked"); GlobalValue* DAliasee = cast(VMI->second); GlobalValue* DGV = NULL; // Try to find something 'similar' to SGA in destination module. if (!DGV && !SGA->hasLocalLinkage()) { DGV = Dest->getNamedAlias(SGA->getName()); // If types don't agree due to opaque types, try to resolve them. if (DGV && DGV->getType() != SGA->getType()) RecursiveResolveTypes(SGA->getType(), DGV->getType()); } if (!DGV && !SGA->hasLocalLinkage()) { DGV = Dest->getGlobalVariable(SGA->getName()); // If types don't agree due to opaque types, try to resolve them. if (DGV && DGV->getType() != SGA->getType()) RecursiveResolveTypes(SGA->getType(), DGV->getType()); } if (!DGV && !SGA->hasLocalLinkage()) { DGV = Dest->getFunction(SGA->getName()); // If types don't agree due to opaque types, try to resolve them. if (DGV && DGV->getType() != SGA->getType()) RecursiveResolveTypes(SGA->getType(), DGV->getType()); } // No linking to be performed on internal stuff. if (DGV && DGV->hasLocalLinkage()) DGV = NULL; if (GlobalAlias *DGA = dyn_cast_or_null(DGV)) { // Types are known to be the same, check whether aliasees equal. As // globals are already linked we just need query ValueMap to find the // mapping. if (DAliasee == DGA->getAliasedGlobal()) { // This is just two copies of the same alias. Propagate linkage, if // necessary. DGA->setLinkage(CalculateAliasLinkage(SGA, DGA)); NewGA = DGA; // Proceed to 'common' steps } else return Error(Err, "Alias Collision on '" + SGA->getName()+ "': aliases have different aliasees"); } else if (GlobalVariable *DGVar = dyn_cast_or_null(DGV)) { // The only allowed way is to link alias with external declaration or weak // symbol.. if (DGVar->isDeclaration() || DGVar->isWeakForLinker()) { // But only if aliasee is global too... if (!isa(DAliasee)) return Error(Err, "Global-Alias Collision on '" + SGA->getName() + "': aliasee is not global variable"); NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), SGA->getName(), DAliasee, Dest); CopyGVAttributes(NewGA, SGA); // Any uses of DGV need to change to NewGA, with cast, if needed. if (SGA->getType() != DGVar->getType()) DGVar->replaceAllUsesWith(Context.getConstantExprBitCast(NewGA, DGVar->getType())); else DGVar->replaceAllUsesWith(NewGA); // DGVar will conflict with NewGA because they both had the same // name. We must erase this now so ForceRenaming doesn't assert // because DGV might not have internal linkage. DGVar->eraseFromParent(); // Proceed to 'common' steps } else return Error(Err, "Global-Alias Collision on '" + SGA->getName() + "': symbol multiple defined"); } else if (Function *DF = dyn_cast_or_null(DGV)) { // The only allowed way is to link alias with external declaration or weak // symbol... if (DF->isDeclaration() || DF->isWeakForLinker()) { // But only if aliasee is function too... if (!isa(DAliasee)) return Error(Err, "Function-Alias Collision on '" + SGA->getName() + "': aliasee is not function"); NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), SGA->getName(), DAliasee, Dest); CopyGVAttributes(NewGA, SGA); // Any uses of DF need to change to NewGA, with cast, if needed. if (SGA->getType() != DF->getType()) DF->replaceAllUsesWith(Context.getConstantExprBitCast(NewGA, DF->getType())); else DF->replaceAllUsesWith(NewGA); // DF will conflict with NewGA because they both had the same // name. We must erase this now so ForceRenaming doesn't assert // because DF might not have internal linkage. DF->eraseFromParent(); // Proceed to 'common' steps } else return Error(Err, "Function-Alias Collision on '" + SGA->getName() + "': symbol multiple defined"); } else { // No linking to be performed, simply create an identical version of the // alias over in the dest module... NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), SGA->getName(), DAliasee, Dest); CopyGVAttributes(NewGA, SGA); // Proceed to 'common' steps } assert(NewGA && "No alias was created in destination module!"); // If the symbol table renamed the alias, but it is an externally visible // symbol, DGA must be an global value with internal linkage. Rename it. if (NewGA->getName() != SGA->getName() && !NewGA->hasLocalLinkage()) ForceRenaming(NewGA, SGA->getName()); // Remember this mapping so uses in the source module get remapped // later by RemapOperand. ValueMap[SGA] = NewGA; } return false; } // LinkGlobalInits - Update the initializers in the Dest module now that all // globals that may be referenced are in Dest. static bool LinkGlobalInits(Module *Dest, const Module *Src, std::map &ValueMap, std::string *Err) { // Loop over all of the globals in the src module, mapping them over as we go for (Module::const_global_iterator I = Src->global_begin(), E = Src->global_end(); I != E; ++I) { const GlobalVariable *SGV = I; if (SGV->hasInitializer()) { // Only process initialized GV's // Figure out what the initializer looks like in the dest module... Constant *SInit = cast(RemapOperand(SGV->getInitializer(), ValueMap, Dest->getContext())); // Grab destination global variable or alias. GlobalValue *DGV = cast(ValueMap[SGV]->stripPointerCasts()); // If dest if global variable, check that initializers match. if (GlobalVariable *DGVar = dyn_cast(DGV)) { if (DGVar->hasInitializer()) { if (SGV->hasExternalLinkage()) { if (DGVar->getInitializer() != SInit) return Error(Err, "Global Variable Collision on '" + SGV->getName() + "': global variables have different initializers"); } else if (DGVar->isWeakForLinker()) { // Nothing is required, mapped values will take the new global // automatically. } else if (SGV->isWeakForLinker()) { // Nothing is required, mapped values will take the new global // automatically. } else if (DGVar->hasAppendingLinkage()) { llvm_unreachable("Appending linkage unimplemented!"); } else { llvm_unreachable("Unknown linkage!"); } } else { // Copy the initializer over now... DGVar->setInitializer(SInit); } } else { // Destination is alias, the only valid situation is when source is // weak. Also, note, that we already checked linkage in LinkGlobals(), // thus we assert here. // FIXME: Should we weaken this assumption, 'dereference' alias and // check for initializer of aliasee? assert(SGV->isWeakForLinker()); } } } return false; } // LinkFunctionProtos - Link the functions together between the two modules, // without doing function bodies... this just adds external function prototypes // to the Dest function... // static bool LinkFunctionProtos(Module *Dest, const Module *Src, std::map &ValueMap, std::string *Err) { ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable(); LLVMContext &Context = Dest->getContext(); // Loop over all of the functions in the src module, mapping them over for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) { const Function *SF = I; // SrcFunction GlobalValue *DGV = 0; // Check to see if may have to link the function with the global, alias or // function. if (SF->hasName() && !SF->hasLocalLinkage()) DGV = cast_or_null(DestSymTab.lookup(SF->getName())); // 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 && DGV->hasLocalLinkage()) DGV = 0; // If types don't agree due to opaque types, try to resolve them. if (DGV && DGV->getType() != SF->getType()) RecursiveResolveTypes(SF->getType(), DGV->getType()); GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; bool LinkFromSrc = false; if (GetLinkageResult(DGV, SF, NewLinkage, LinkFromSrc, Err)) return true; // If there is no linkage to be performed, just bring over SF without // modifying it. if (DGV == 0) { // Function does not already exist, simply insert an function signature // identical to SF into the dest module. Function *NewDF = Function::Create(SF->getFunctionType(), SF->getLinkage(), SF->getName(), Dest); CopyGVAttributes(NewDF, SF); // If the LLVM runtime renamed the function, but it is an externally // visible symbol, DF must be an existing function with internal linkage. // Rename it. if (!NewDF->hasLocalLinkage() && NewDF->getName() != SF->getName()) ForceRenaming(NewDF, SF->getName()); // ... and remember this mapping... ValueMap[SF] = NewDF; continue; } // If the visibilities of the symbols disagree and the destination is a // prototype, take the visibility of its input. if (DGV->isDeclaration()) DGV->setVisibility(SF->getVisibility()); if (LinkFromSrc) { if (isa(DGV)) return Error(Err, "Function-Alias Collision on '" + SF->getName() + "': symbol multiple defined"); // We have a definition of the same name but different type in the // source module. Copy the prototype to the destination and replace // uses of the destination's prototype with the new prototype. Function *NewDF = Function::Create(SF->getFunctionType(), NewLinkage, SF->getName(), Dest); CopyGVAttributes(NewDF, SF); // Any uses of DF need to change to NewDF, with cast DGV->replaceAllUsesWith(Context.getConstantExprBitCast(NewDF, DGV->getType())); // DF will conflict with NewDF because they both had the same. We must // erase this now so ForceRenaming doesn't assert because DF might // not have internal linkage. if (GlobalVariable *Var = dyn_cast(DGV)) Var->eraseFromParent(); else cast(DGV)->eraseFromParent(); // If the symbol table renamed the function, but it is an externally // visible symbol, DF must be an existing function with internal // linkage. Rename it. if (NewDF->getName() != SF->getName() && !NewDF->hasLocalLinkage()) ForceRenaming(NewDF, SF->getName()); // Remember this mapping so uses in the source module get remapped // later by RemapOperand. ValueMap[SF] = NewDF; continue; } // Not "link from source", keep the one in the DestModule and remap the // input onto it. if (isa(DGV)) { // The only valid mappings are: // - SF is external declaration, which is effectively a no-op. // - SF is weak, when we just need to throw SF out. if (!SF->isDeclaration() && !SF->isWeakForLinker()) return Error(Err, "Function-Alias Collision on '" + SF->getName() + "': symbol multiple defined"); } // Set calculated linkage DGV->setLinkage(NewLinkage); // Make sure to remember this mapping. ValueMap[SF] = Context.getConstantExprBitCast(DGV, SF->getType()); } return false; } // LinkFunctionBody - 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. static bool LinkFunctionBody(Function *Dest, Function *Src, std::map &ValueMap, std::string *Err) { assert(Src && Dest && Dest->isDeclaration() && !Src->isDeclaration()); // Go through and convert function arguments over, remembering the mapping. Function::arg_iterator DI = Dest->arg_begin(); for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); I != E; ++I, ++DI) { DI->setName(I->getName()); // Copy the name information over... // Add a mapping to our local map ValueMap[I] = DI; } // Splice the body of the source function into the dest function. Dest->getBasicBlockList().splice(Dest->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 (Function::iterator BB = Dest->begin(), BE = Dest->end(); BB != BE; ++BB) for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end(); OI != OE; ++OI) if (!isa(*OI) && !isa(*OI)) *OI = RemapOperand(*OI, ValueMap, Dest->getContext()); // There is no need to map the arguments anymore. for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); I != E; ++I) ValueMap.erase(I); return false; } // LinkFunctionBodies - Link in the function bodies that are defined in the // source module into the DestModule. This consists basically of copying the // function over and fixing up references to values. static bool LinkFunctionBodies(Module *Dest, Module *Src, std::map &ValueMap, std::string *Err) { // Loop over all of the functions in the src module, mapping them over as we // go for (Module::iterator SF = Src->begin(), E = Src->end(); SF != E; ++SF) { if (!SF->isDeclaration()) { // No body if function is external Function *DF = dyn_cast(ValueMap[SF]); // Destination function // DF not external SF external? if (DF && DF->isDeclaration()) // Only provide the function body if there isn't one already. if (LinkFunctionBody(DF, SF, ValueMap, Err)) return true; } } return false; } // LinkAppendingVars - If there were any appending global variables, link them // together now. Return true on error. static bool LinkAppendingVars(Module *M, std::multimap &AppendingVars, std::string *ErrorMsg) { if (AppendingVars.empty()) return false; // Nothing to do. LLVMContext &Context = M->getContext(); // Loop over the multimap of appending vars, processing any variables with the // same name, forming a new appending global variable with both of the // initializers merged together, then rewrite references to the old variables // and delete them. std::vector Inits; while (AppendingVars.size() > 1) { // Get the first two elements in the map... std::multimap::iterator Second = AppendingVars.begin(), First=Second++; // If the first two elements are for different names, there is no pair... // Otherwise there is a pair, so link them together... if (First->first == Second->first) { GlobalVariable *G1 = First->second, *G2 = Second->second; const ArrayType *T1 = cast(G1->getType()->getElementType()); const ArrayType *T2 = cast(G2->getType()->getElementType()); // Check to see that they two arrays agree on type... if (T1->getElementType() != T2->getElementType()) return Error(ErrorMsg, "Appending variables with different element types need to be linked!"); if (G1->isConstant() != G2->isConstant()) return Error(ErrorMsg, "Appending variables linked with different const'ness!"); if (G1->getAlignment() != G2->getAlignment()) return Error(ErrorMsg, "Appending variables with different alignment need to be linked!"); if (G1->getVisibility() != G2->getVisibility()) return Error(ErrorMsg, "Appending variables with different visibility need to be linked!"); if (G1->getSection() != G2->getSection()) return Error(ErrorMsg, "Appending variables with different section name need to be linked!"); unsigned NewSize = T1->getNumElements() + T2->getNumElements(); ArrayType *NewType = Context.getArrayType(T1->getElementType(), NewSize); G1->setName(""); // Clear G1's name in case of a conflict! // Create the new global variable... GlobalVariable *NG = new GlobalVariable(*M, NewType, G1->isConstant(), G1->getLinkage(), /*init*/0, First->first, 0, G1->isThreadLocal(), G1->getType()->getAddressSpace()); // Propagate alignment, visibility and section info. CopyGVAttributes(NG, G1); // Merge the initializer... Inits.reserve(NewSize); if (ConstantArray *I = dyn_cast(G1->getInitializer())) { for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i) Inits.push_back(I->getOperand(i)); } else { assert(isa(G1->getInitializer())); Constant *CV = Context.getNullValue(T1->getElementType()); for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i) Inits.push_back(CV); } if (ConstantArray *I = dyn_cast(G2->getInitializer())) { for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i) Inits.push_back(I->getOperand(i)); } else { assert(isa(G2->getInitializer())); Constant *CV = Context.getNullValue(T2->getElementType()); for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i) Inits.push_back(CV); } NG->setInitializer(Context.getConstantArray(NewType, Inits)); Inits.clear(); // Replace any uses of the two global variables with uses of the new // global... // FIXME: This should rewrite simple/straight-forward uses such as // getelementptr instructions to not use the Cast! G1->replaceAllUsesWith(Context.getConstantExprBitCast(NG, G1->getType())); G2->replaceAllUsesWith(Context.getConstantExprBitCast(NG, G2->getType())); // Remove the two globals from the module now... M->getGlobalList().erase(G1); M->getGlobalList().erase(G2); // Put the new global into the AppendingVars map so that we can handle // linking of more than two vars... Second->second = NG; } AppendingVars.erase(First); } return false; } static bool ResolveAliases(Module *Dest) { for (Module::alias_iterator I = Dest->alias_begin(), E = Dest->alias_end(); I != E; ++I) if (const GlobalValue *GV = I->resolveAliasedGlobal()) if (GV != I && !GV->isDeclaration()) I->replaceAllUsesWith(const_cast(GV)); return false; } // LinkModules - This function links two modules together, with the resulting // left 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, std::string *ErrorMsg) { assert(Dest != 0 && "Invalid Destination module"); assert(Src != 0 && "Invalid Source Module"); if (Dest->getDataLayout().empty()) { if (!Src->getDataLayout().empty()) { Dest->setDataLayout(Src->getDataLayout()); } else { std::string DataLayout; if (Dest->getEndianness() == Module::AnyEndianness) { if (Src->getEndianness() == Module::BigEndian) DataLayout.append("E"); else if (Src->getEndianness() == Module::LittleEndian) DataLayout.append("e"); } if (Dest->getPointerSize() == Module::AnyPointerSize) { if (Src->getPointerSize() == Module::Pointer64) DataLayout.append(DataLayout.length() == 0 ? "p:64:64" : "-p:64:64"); else if (Src->getPointerSize() == Module::Pointer32) DataLayout.append(DataLayout.length() == 0 ? "p:32:32" : "-p:32:32"); } Dest->setDataLayout(DataLayout); } } // Copy the target triple from the source to dest if the dest's is empty. if (Dest->getTargetTriple().empty() && !Src->getTargetTriple().empty()) Dest->setTargetTriple(Src->getTargetTriple()); if (!Src->getDataLayout().empty() && !Dest->getDataLayout().empty() && Src->getDataLayout() != Dest->getDataLayout()) cerr << "WARNING: Linking two modules of different data layouts!\n"; if (!Src->getTargetTriple().empty() && Dest->getTargetTriple() != Src->getTargetTriple()) cerr << "WARNING: Linking two modules of different target triples!\n"; // Append the module inline asm string. if (!Src->getModuleInlineAsm().empty()) { if (Dest->getModuleInlineAsm().empty()) Dest->setModuleInlineAsm(Src->getModuleInlineAsm()); else Dest->setModuleInlineAsm(Dest->getModuleInlineAsm()+"\n"+ Src->getModuleInlineAsm()); } // Update the destination module's dependent libraries list with the libraries // from the source module. There's no opportunity for duplicates here as the // Module ensures that duplicate insertions are discarded. for (Module::lib_iterator SI = Src->lib_begin(), SE = Src->lib_end(); SI != SE; ++SI) Dest->addLibrary(*SI); // LinkTypes - Go through the symbol table of the Src module and see if any // types are named in the src module that are not named in the Dst module. // Make sure there are no type name conflicts. if (LinkTypes(Dest, Src, ErrorMsg)) return true; // ValueMap - Mapping of values from what they used to be in Src, to what they // are now in Dest. std::map ValueMap; // AppendingVars - Keep track of global variables in the destination module // with appending linkage. After the module is linked together, they are // appended and the module is rewritten. std::multimap AppendingVars; for (Module::global_iterator I = Dest->global_begin(), E = Dest->global_end(); I != E; ++I) { // Add all of the appending globals already in the Dest module to // AppendingVars. if (I->hasAppendingLinkage()) AppendingVars.insert(std::make_pair(I->getName(), I)); } // Insert all of the globals in src into the Dest module... without linking // initializers (which could refer to functions not yet mapped over). if (LinkGlobals(Dest, Src, ValueMap, AppendingVars, ErrorMsg)) return true; // Link the functions together between the two modules, without doing function // bodies... this just adds external function prototypes to the Dest // 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. if (LinkFunctionProtos(Dest, Src, ValueMap, ErrorMsg)) return true; // If there were any alias, link them now. We really need to do this now, // because all of the aliases that may be referenced need to be available in // ValueMap if (LinkAlias(Dest, Src, ValueMap, ErrorMsg)) return true; // Update the initializers in the Dest module now that all globals that may // be referenced are in Dest. if (LinkGlobalInits(Dest, Src, ValueMap, ErrorMsg)) return true; // Link in the function bodies that are defined in the source module into the // DestModule. This consists basically of copying the function over and // fixing up references to values. if (LinkFunctionBodies(Dest, Src, ValueMap, ErrorMsg)) return true; // If there were any appending global variables, link them together now. if (LinkAppendingVars(Dest, AppendingVars, ErrorMsg)) return true; // Resolve all uses of aliases with aliasees if (ResolveAliases(Dest)) return true; // If the source library's module id is in the dependent library list of the // destination library, remove it since that module is now linked in. sys::Path modId; modId.set(Src->getModuleIdentifier()); if (!modId.isEmpty()) Dest->removeLibrary(modId.getBasename()); return false; } // vim: sw=2