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llvm-project/llvm/lib/Linker/LinkModules.cpp

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//===- 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/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/System/Path.h"
#include "llvm/Transforms/Utils/ValueMapper.h"
#include "llvm/ADT/DenseMap.h"
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<OpaqueType>(DestTy)) {
// Type _is_ in module, just opaque...
const_cast<OpaqueType*>(OT)->refineAbstractTypeTo(SrcTy);
} else if (const OpaqueType *OT = dyn_cast<OpaqueType>(SrcTy)) {
const_cast<OpaqueType*>(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<const Type*, PATypeHolder> TheMapTy;
TheMapTy TheMap;
LinkerTypeMap(const LinkerTypeMap&); // DO NOT IMPLEMENT
void operator=(const LinkerTypeMap&); // DO NOT IMPLEMENT
public:
LinkerTypeMap() {}
~LinkerTypeMap() {
for (DenseMap<const Type*, PATypeHolder>::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;
}
/// 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 {
dbgs() << "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 (DstTy->isOpaqueTy() || SrcTy->isOpaqueTy())
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<FunctionType>(DstTy);
const FunctionType *SrcFT = cast<FunctionType>(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<StructType>(DstTy);
const StructType *SrcST = cast<StructType>(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<ArrayType>(DstTy);
const ArrayType *SAT = cast<ArrayType>(SrcTy);
if (DAT->getNumElements() != SAT->getNumElements()) return true;
return RecursiveResolveTypesI(DAT->getElementType(), SAT->getElementType(),
Pointers);
}
case Type::VectorTyID: {
const VectorType *DVT = cast<VectorType>(DstTy);
const VectorType *SVT = cast<VectorType>(SrcTy);
if (DVT->getNumElements() != SVT->getNumElements()) return true;
return RecursiveResolveTypesI(DVT->getElementType(), SVT->getElementType(),
Pointers);
}
case Type::PointerTyID: {
const PointerType *DstPT = cast<PointerType>(DstTy);
const PointerType *SrcPT = cast<PointerType>(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<std::string> 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<Type*>(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;
}
/// 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<GlobalValue>(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 &LT, 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;
}
// Insert all of the named mdnoes in Src into the Dest module.
static void LinkNamedMDNodes(Module *Dest, Module *Src,
ValueToValueMapTy &ValueMap) {
for (Module::const_named_metadata_iterator I = Src->named_metadata_begin(),
E = Src->named_metadata_end(); I != E; ++I) {
const NamedMDNode *SrcNMD = I;
NamedMDNode *DestNMD = Dest->getOrInsertNamedMetadata(SrcNMD->getName());
// Add Src elements into Dest node.
for (unsigned i = 0, e = SrcNMD->getNumOperands(); i != e; ++i)
DestNMD->addOperand(cast<MDNode>(MapValue(SrcNMD->getOperand(i),
ValueMap,
true)));
}
}
// 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,
ValueToValueMapTy &ValueMap,
std::multimap<std::string, GlobalVariable *> &AppendingVars,
std::string *Err) {
ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable();
// 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<GlobalValue>(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<GlobalAlias>(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(ConstantExpr::getBitCast(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<GlobalVariable>(DGV))
Var->eraseFromParent();
else
cast<Function>(DGV)->eraseFromParent();
// 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<GlobalVariable>(DGV))
if (DGVar->isDeclaration() && SGV->isConstant() && !DGVar->isConstant())
DGVar->setConstant(true);
// SGV is global, but DGV is alias.
if (isa<GlobalAlias>(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] = ConstantExpr::getBitCast(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 if (SL == GlobalValue::LinkerPrivateWeakLinkage &&
DL == GlobalValue::LinkerPrivateWeakLinkage)
return GlobalValue::LinkerPrivateWeakLinkage;
else if (SL == GlobalValue::LinkerPrivateWeakDefAutoLinkage &&
DL == GlobalValue::LinkerPrivateWeakDefAutoLinkage)
return GlobalValue::LinkerPrivateWeakDefAutoLinkage;
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,
ValueToValueMapTy &ValueMap,
std::string *Err) {
// 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.
ValueToValueMapTy::const_iterator VMI = ValueMap.find(SAliasee);
assert(VMI != ValueMap.end() && "Aliasee not linked");
GlobalValue* DAliasee = cast<GlobalValue>(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<GlobalAlias>(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<GlobalVariable>(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<GlobalVariable>(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(ConstantExpr::getBitCast(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<Function>(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<Function>(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(ConstantExpr::getBitCast(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...
Constant *Aliasee = DAliasee;
// Fixup aliases to bitcasts. Note that aliases to GEPs are still broken
// by this, but aliases to GEPs are broken to a lot of other things, so
// it's less important.
if (SGA->getType() != DAliasee->getType())
Aliasee = ConstantExpr::getBitCast(DAliasee, SGA->getType());
NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(),
SGA->getName(), Aliasee, 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 MapValue.
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,
ValueToValueMapTy &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<Constant>(MapValue(SGV->getInitializer(), ValueMap, true));
// Grab destination global variable or alias.
GlobalValue *DGV = cast<GlobalValue>(ValueMap[SGV]->stripPointerCasts());
// If dest if global variable, check that initializers match.
if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(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,
ValueToValueMapTy &ValueMap,
std::string *Err) {
ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable();
// 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<GlobalValue>(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<GlobalAlias>(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(ConstantExpr::getBitCast(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<GlobalVariable>(DGV))
Var->eraseFromParent();
else
cast<Function>(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 MapValue.
ValueMap[SF] = NewDF;
continue;
}
// Not "link from source", keep the one in the DestModule and remap the
// input onto it.
if (isa<GlobalAlias>(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] = ConstantExpr::getBitCast(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,
ValueToValueMapTy &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...
//
// This is the same as RemapInstruction, except that it avoids remapping
// instruction and basic block operands.
//
for (Function::iterator BB = Dest->begin(), BE = Dest->end(); BB != BE; ++BB)
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
// Remap operands.
for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end();
OI != OE; ++OI)
if (!isa<Instruction>(*OI) && !isa<BasicBlock>(*OI))
*OI = MapValue(*OI, ValueMap, true);
// Remap attached metadata.
SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
I->getAllMetadata(MDs);
for (SmallVectorImpl<std::pair<unsigned, MDNode *> >::iterator
MI = MDs.begin(), ME = MDs.end(); MI != ME; ++MI) {
Value *Old = MI->second;
if (!isa<Instruction>(Old) && !isa<BasicBlock>(Old)) {
Value *New = MapValue(Old, ValueMap, true);
if (New != Old)
I->setMetadata(MI->first, cast<MDNode>(New));
}
}
}
// 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,
ValueToValueMapTy &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<Function>(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<std::string, GlobalVariable *> &AppendingVars,
std::string *ErrorMsg) {
if (AppendingVars.empty()) return false; // Nothing to do.
// 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<Constant*> Inits;
while (AppendingVars.size() > 1) {
// Get the first two elements in the map...
std::multimap<std::string,
GlobalVariable*>::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<ArrayType>(G1->getType()->getElementType());
const ArrayType *T2 = cast<ArrayType>(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 = ArrayType::get(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<ConstantArray>(G1->getInitializer())) {
for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i)
Inits.push_back(I->getOperand(i));
} else {
assert(isa<ConstantAggregateZero>(G1->getInitializer()));
Constant *CV = Constant::getNullValue(T1->getElementType());
for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i)
Inits.push_back(CV);
}
if (ConstantArray *I = dyn_cast<ConstantArray>(G2->getInitializer())) {
for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i)
Inits.push_back(I->getOperand(i));
} else {
assert(isa<ConstantAggregateZero>(G2->getInitializer()));
Constant *CV = Constant::getNullValue(T2->getElementType());
for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i)
Inits.push_back(CV);
}
NG->setInitializer(ConstantArray::get(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(ConstantExpr::getBitCast(NG,
G1->getType()));
G2->replaceAllUsesWith(ConstantExpr::getBitCast(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)
// We can't sue resolveGlobalAlias here because we need to preserve
// bitcasts and GEPs.
if (const Constant *C = I->getAliasee()) {
while (dyn_cast<GlobalAlias>(C))
C = cast<GlobalAlias>(C)->getAliasee();
const GlobalValue *GV = dyn_cast<GlobalValue>(C);
if (C != I && !(GV && GV->isDeclaration()))
I->replaceAllUsesWith(const_cast<Constant*>(C));
}
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())
errs() << "WARNING: Linking two modules of different data layouts!\n";
if (!Src->getTargetTriple().empty() &&
Dest->getTargetTriple() != Src->getTargetTriple())
errs() << "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. 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;
// 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<std::string, GlobalVariable *> 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;
// Remap all of the named mdnoes in Src into the Dest module. We do this
// after linking GlobalValues so that MDNodes that reference GlobalValues
// are properly remapped.
LinkNamedMDNodes(Dest, Src, ValueMap);
// 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
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