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llvm/lib/Linker/LinkModules.cpp
Anton Korobeynikov 5241957b1f Ultimately resolve aliases during linking, if possible 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@48259 91177308-0d34-0410-b5e6-96231b3b80d8
2008-03-11 22:51:09 +00:00

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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/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/System/Path.h"
#include <sstream>
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 std::string &Message) {
if (E) *E = Message;
return true;
}
// ToStr - Simple wrapper function to convert a type to a string.
static std::string ToStr(const Type *Ty, const Module *M) {
std::ostringstream OS;
WriteTypeSymbolic(OS, Ty, M);
return OS.str();
}
//
// 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.
// Name - The name of the type.
//
// 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,
TypeSymbolTable *DestST, const std::string &Name) {
if (DestTy == SrcTy) return false; // If already equal, noop
// Does the type already exist in the module?
if (DestTy && !isa<OpaqueType>(DestTy)) { // Yup, the type already exists...
if (const OpaqueType *OT = dyn_cast<OpaqueType>(SrcTy)) {
const_cast<OpaqueType*>(OT)->refineAbstractTypeTo(DestTy);
} else {
return true; // Cannot link types... neither is opaque and not-equal
}
} else { // Type not in dest module. Add it now.
if (DestTy) // Type _is_ in module, just opaque...
const_cast<OpaqueType*>(cast<OpaqueType>(DestTy))
->refineAbstractTypeTo(SrcTy);
else if (!Name.empty())
DestST->insert(Name, const_cast<Type*>(SrcTy));
}
return false;
}
static const FunctionType *getFT(const PATypeHolder &TH) {
return cast<FunctionType>(TH.get());
}
static const StructType *getST(const PATypeHolder &TH) {
return cast<StructType>(TH.get());
}
// 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 PATypeHolder &DestTy,
const PATypeHolder &SrcTy,
TypeSymbolTable *DestST,
const std::string &Name,
std::vector<std::pair<PATypeHolder, PATypeHolder> > &Pointers) {
const Type *SrcTyT = SrcTy.get();
const Type *DestTyT = DestTy.get();
if (DestTyT == SrcTyT) return false; // If already equal, noop
// If we found our opaque type, resolve it now!
if (isa<OpaqueType>(DestTyT) || isa<OpaqueType>(SrcTyT))
return ResolveTypes(DestTyT, SrcTyT, DestST, Name);
// Two types cannot be resolved together if they are of different primitive
// type. For example, we cannot resolve an int to a float.
if (DestTyT->getTypeID() != SrcTyT->getTypeID()) return true;
// Otherwise, resolve the used type used by this derived type...
switch (DestTyT->getTypeID()) {
case Type::IntegerTyID: {
if (cast<IntegerType>(DestTyT)->getBitWidth() !=
cast<IntegerType>(SrcTyT)->getBitWidth())
return true;
return false;
}
case Type::FunctionTyID: {
if (cast<FunctionType>(DestTyT)->isVarArg() !=
cast<FunctionType>(SrcTyT)->isVarArg() ||
cast<FunctionType>(DestTyT)->getNumContainedTypes() !=
cast<FunctionType>(SrcTyT)->getNumContainedTypes())
return true;
for (unsigned i = 0, e = getFT(DestTy)->getNumContainedTypes(); i != e; ++i)
if (RecursiveResolveTypesI(getFT(DestTy)->getContainedType(i),
getFT(SrcTy)->getContainedType(i), DestST, "",
Pointers))
return true;
return false;
}
case Type::StructTyID: {
if (getST(DestTy)->getNumContainedTypes() !=
getST(SrcTy)->getNumContainedTypes()) return 1;
for (unsigned i = 0, e = getST(DestTy)->getNumContainedTypes(); i != e; ++i)
if (RecursiveResolveTypesI(getST(DestTy)->getContainedType(i),
getST(SrcTy)->getContainedType(i), DestST, "",
Pointers))
return true;
return false;
}
case Type::ArrayTyID: {
const ArrayType *DAT = cast<ArrayType>(DestTy.get());
const ArrayType *SAT = cast<ArrayType>(SrcTy.get());
if (DAT->getNumElements() != SAT->getNumElements()) return true;
return RecursiveResolveTypesI(DAT->getElementType(), SAT->getElementType(),
DestST, "", Pointers);
}
case Type::PointerTyID: {
// 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...
for (unsigned i = 0, e = Pointers.size(); i != e; ++i)
if (Pointers[i].first == DestTy)
return Pointers[i].second != SrcTy;
// Otherwise, add the current pointers to the vector to stop recursion on
// this pair.
Pointers.push_back(std::make_pair(DestTyT, SrcTyT));
bool Result =
RecursiveResolveTypesI(cast<PointerType>(DestTy.get())->getElementType(),
cast<PointerType>(SrcTy.get())->getElementType(),
DestST, "", Pointers);
Pointers.pop_back();
return Result;
}
default: assert(0 && "Unexpected type!"); return true;
}
}
static bool RecursiveResolveTypes(const PATypeHolder &DestTy,
const PATypeHolder &SrcTy,
TypeSymbolTable *DestST,
const std::string &Name){
std::vector<std::pair<PATypeHolder, PATypeHolder> > PointerTypes;
return RecursiveResolveTypesI(DestTy, SrcTy, DestST, Name, 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 (ResolveTypes(Entry, RHS, DestST, Name)) {
// 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, DestST, Name)) {
// 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];
PATypeHolder T1(SrcST->lookup(Name));
PATypeHolder T2(DestST->lookup(Name));
if (!RecursiveResolveTypes(T2, T1, DestST, 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;
}
static void PrintMap(const std::map<const Value*, Value*> &M) {
for (std::map<const Value*, Value*>::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";
}
}
// RemapOperand - Use ValueMap to convert constants from one module to another.
static Value *RemapOperand(const Value *In,
std::map<const Value*, Value*> &ValueMap) {
std::map<const Value*,Value*>::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<Constant>(In)) {
if ((!isa<DerivedType>(CPV->getType()) && !isa<ConstantExpr>(CPV)) ||
isa<ConstantInt>(CPV) || isa<ConstantAggregateZero>(CPV))
return const_cast<Constant*>(CPV); // Simple constants stay identical.
if (const ConstantArray *CPA = dyn_cast<ConstantArray>(CPV)) {
std::vector<Constant*> Operands(CPA->getNumOperands());
for (unsigned i = 0, e = CPA->getNumOperands(); i != e; ++i)
Operands[i] =cast<Constant>(RemapOperand(CPA->getOperand(i), ValueMap));
Result = ConstantArray::get(cast<ArrayType>(CPA->getType()), Operands);
} else if (const ConstantStruct *CPS = dyn_cast<ConstantStruct>(CPV)) {
std::vector<Constant*> Operands(CPS->getNumOperands());
for (unsigned i = 0, e = CPS->getNumOperands(); i != e; ++i)
Operands[i] =cast<Constant>(RemapOperand(CPS->getOperand(i), ValueMap));
Result = ConstantStruct::get(cast<StructType>(CPS->getType()), Operands);
} else if (isa<ConstantPointerNull>(CPV) || isa<UndefValue>(CPV)) {
Result = const_cast<Constant*>(CPV);
} else if (const ConstantVector *CP = dyn_cast<ConstantVector>(CPV)) {
std::vector<Constant*> Operands(CP->getNumOperands());
for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i)
Operands[i] = cast<Constant>(RemapOperand(CP->getOperand(i), ValueMap));
Result = ConstantVector::get(Operands);
} else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CPV)) {
std::vector<Constant*> Ops;
for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i)
Ops.push_back(cast<Constant>(RemapOperand(CE->getOperand(i),ValueMap)));
Result = CE->getWithOperands(Ops);
} else if (isa<GlobalValue>(CPV)) {
assert(0 && "Unmapped global?");
} else {
assert(0 && "Unknown type of derived type constant value!");
}
} else if (isa<InlineAsm>(In)) {
Result = const_cast<Value*>(In);
}
// Cache the mapping in our local map structure
if (Result) {
ValueMap[In] = Result;
return Result;
}
cerr << "LinkModules ValueMap: \n";
PrintMap(ValueMap);
cerr << "Couldn't remap value: " << (void*)In << " " << *In << "\n";
assert(0 && "Couldn't remap value!");
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<GlobalValue>(ST.lookup(Name))) {
assert(ConflictGV->hasInternalLinkage() &&
"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) {
// Propagate alignment, visibility and section info.
DestGV->setAlignment(std::max(DestGV->getAlignment(), SrcGV->getAlignment()));
DestGV->setSection(SrcGV->getSection());
DestGV->setVisibility(SrcGV->getVisibility());
if (const Function *SrcF = dyn_cast<Function>(SrcGV)) {
Function *DestF = cast<Function>(DestGV);
DestF->setCallingConv(SrcF->getCallingConv());
DestF->setParamAttrs(SrcF->getParamAttrs());
if (SrcF->hasCollector())
DestF->setCollector(SrcF->getCollector());
} else if (const GlobalVariable *SrcVar = dyn_cast<GlobalVariable>(SrcGV)) {
GlobalVariable *DestVar = cast<GlobalVariable>(DestGV);
DestVar->setThreadLocal(SrcVar->isThreadLocal());
}
}
/// 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->hasInternalLinkage()) &&
"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->hasWeakLinkage() || Src->hasLinkOnceLinkage()) {
// At this point we know that Dest has LinkOnce, External*, Weak, or
// DLL* linkage.
if ((Dest->hasLinkOnceLinkage() && Src->hasWeakLinkage()) ||
Dest->hasExternalWeakLinkage()) {
LinkFromSrc = true;
LT = Src->getLinkage();
} else {
LinkFromSrc = false;
LT = Dest->getLinkage();
}
} else if (Dest->hasWeakLinkage() || Dest->hasLinkOnceLinkage()) {
// 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<const Value*, Value*> &ValueMap,
std::multimap<std::string, GlobalVariable *> &AppendingVars,
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;
GlobalValue *DGV = 0;
// Check to see if may have to link the global with the global
if (SGV->hasName() && !SGV->hasInternalLinkage()) {
DGV = Dest->getGlobalVariable(SGV->getName());
if (DGV && DGV->getType() != SGV->getType())
// If types don't agree due to opaque types, try to resolve them.
RecursiveResolveTypes(SGV->getType(), DGV->getType(),
&Dest->getTypeSymbolTable(), "");
}
// Check to see if may have to link the global with the alias
if (!DGV && SGV->hasName() && !SGV->hasInternalLinkage()) {
DGV = Dest->getNamedAlias(SGV->getName());
if (DGV && DGV->getType() != SGV->getType())
// If types don't agree due to opaque types, try to resolve them.
RecursiveResolveTypes(SGV->getType(), DGV->getType(),
&Dest->getTypeSymbolTable(), "");
}
if (DGV && DGV->hasInternalLinkage())
DGV = 0;
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) {
// 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(SGV->getType()->getElementType(),
SGV->isConstant(), SGV->getLinkage(), /*init*/0,
SGV->getName(), Dest);
// 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->getName() != SGV->getName() && !NewDGV->hasInternalLinkage())
ForceRenaming(NewDGV, SGV->getName());
// Make sure to remember this mapping...
ValueMap[SGV] = NewDGV;
if (SGV->hasAppendingLinkage())
// Keep track that this is an appending variable...
AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV));
} else 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(SGV->getType()->getElementType(),
SGV->isConstant(), SGV->getLinkage(), /*init*/0,
"", Dest);
// 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));
} else if (GlobalAlias *DGA = dyn_cast<GlobalAlias>(DGV)) {
// SGV is global, but DGV is alias. The only valid mapping is when SGV is
// external declaration, which is effectively a no-op. Also make sure
// linkage calculation was correct.
if (SGV->isDeclaration() && !LinkFromSrc) {
// Make sure to remember this mapping...
ValueMap[SGV] = DGA;
} else
return Error(Err, "Global-Alias Collision on '" + SGV->getName() +
"': symbol multiple defined");
} else if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) {
// Otherwise, perform the global-global mapping as instructed by
// GetLinkageResult.
if (LinkFromSrc) {
// Propagate alignment, section, and visibility info.
CopyGVAttributes(DGVar, SGV);
// 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.
if (SGV->getType() != DGVar->getType()) {
GlobalVariable *NewDGV =
new GlobalVariable(SGV->getType()->getElementType(),
DGVar->isConstant(), DGVar->getLinkage(),
/*init*/0, DGVar->getName(), Dest);
CopyGVAttributes(NewDGV, DGVar);
DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV,
DGVar->getType()));
// DGVar 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.
DGVar->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 it.
if (NewDGV->getName() != SGV->getName() &&
!NewDGV->hasInternalLinkage())
ForceRenaming(NewDGV, SGV->getName());
DGVar = NewDGV;
}
// Inherit const as appropriate
DGVar->setConstant(SGV->isConstant());
// Set initializer to zero, so we can link the stuff later
DGVar->setInitializer(0);
} else {
// Special case for const propagation
if (DGVar->isDeclaration() && SGV->isConstant() && !DGVar->isConstant())
DGVar->setConstant(true);
}
// Set calculated linkage
DGVar->setLinkage(NewLinkage);
// Make sure to remember this mapping...
ValueMap[SGV] = ConstantExpr::getBitCast(DGVar, SGV->getType());
}
}
return false;
}
static GlobalValue::LinkageTypes
CalculateAliasLinkage(const GlobalValue *SGV, const GlobalValue *DGV) {
if (SGV->hasExternalLinkage() || DGV->hasExternalLinkage())
return GlobalValue::ExternalLinkage;
else if (SGV->hasWeakLinkage() || DGV->hasWeakLinkage())
return GlobalValue::WeakLinkage;
else {
assert(SGV->hasInternalLinkage() && DGV->hasInternalLinkage() &&
"Unexpected linkage type");
return GlobalValue::InternalLinkage;
}
}
// 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<const Value*, Value*> &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
std::map<const Value*,Value*>::const_iterator VMI = ValueMap.find(SAliasee);
assert(VMI != ValueMap.end() && "Aliasee not linked");
GlobalValue* DAliasee = cast<GlobalValue>(VMI->second);
// Try to find something 'similar' to SGA in destination module.
if (GlobalAlias *DGA = Dest->getNamedAlias(SGA->getName())) {
// If types don't agree due to opaque types, try to resolve them.
if (RecursiveResolveTypes(SGA->getType(), DGA->getType(),
&Dest->getTypeSymbolTable(), ""))
return Error(Err, "Alias Collision on '" + SGA->getName()+
"': aliases have different types");
// Now 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 *DGV = Dest->getGlobalVariable(SGA->getName())) {
RecursiveResolveTypes(SGA->getType(), DGV->getType(),
&Dest->getTypeSymbolTable(), "");
// The only allowed way is to link alias with external declaration.
if (DGV->isDeclaration()) {
// 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() != DGV->getType())
DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA,
DGV->getType()));
else
DGV->replaceAllUsesWith(NewGA);
// DGV 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.
DGV->eraseFromParent();
// Proceed to 'common' steps
} else
return Error(Err, "Global-Alias Collision on '" + SGA->getName() +
"': symbol multiple defined");
} else if (Function *DF = Dest->getFunction(SGA->getName())) {
RecursiveResolveTypes(SGA->getType(), DF->getType(),
&Dest->getTypeSymbolTable(), "");
// The only allowed way is to link alias with external declaration.
if (DF->isDeclaration()) {
// 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 {
// Nothing similar found, just copy alias into destination 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, DGV must be an global value with internal linkage. Rename it.
if (NewGA->getName() != SGA->getName() &&
!NewGA->hasInternalLinkage())
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<const Value*, Value*> &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>(RemapOperand(SGV->getInitializer(), ValueMap));
GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[SGV]);
if (DGV->hasInitializer()) {
if (SGV->hasExternalLinkage()) {
if (DGV->getInitializer() != SInit)
return Error(Err, "Global Variable Collision on '" + SGV->getName() +
"': global variables have different initializers");
} else if (DGV->hasLinkOnceLinkage() || DGV->hasWeakLinkage()) {
// Nothing is required, mapped values will take the new global
// automatically.
} else if (SGV->hasLinkOnceLinkage() || SGV->hasWeakLinkage()) {
// Nothing is required, mapped values will take the new global
// automatically.
} else if (DGV->hasAppendingLinkage()) {
assert(0 && "Appending linkage unimplemented!");
} else {
assert(0 && "Unknown linkage!");
}
} else {
// Copy the initializer over now...
DGV->setInitializer(SInit);
}
}
}
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<const Value*, Value*> &ValueMap,
std::string *Err) {
// 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
Function *DF = 0;
if (SF->hasName() && !SF->hasInternalLinkage()) {
// Check to see if may have to link the function.
DF = Dest->getFunction(SF->getName());
if (DF && SF->getType() != DF->getType())
// If types don't agree because of opaque, try to resolve them
RecursiveResolveTypes(SF->getType(), DF->getType(),
&Dest->getTypeSymbolTable(), "");
}
// Check visibility
if (DF && !DF->hasInternalLinkage() &&
SF->getVisibility() != DF->getVisibility()) {
// If one is a prototype, ignore its visibility. Prototypes are always
// overridden by the definition.
if (!SF->isDeclaration() && !DF->isDeclaration())
return Error(Err, "Linking functions named '" + SF->getName() +
"': symbols have different visibilities!");
}
if (DF && DF->hasInternalLinkage())
DF = NULL;
if (DF && DF->getType() != SF->getType()) {
if (DF->isDeclaration() && !SF->isDeclaration()) {
// 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 = new Function(SF->getFunctionType(), SF->getLinkage(),
SF->getName(), Dest);
CopyGVAttributes(NewDF, SF);
// Any uses of DF need to change to NewDF, with cast
DF->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, DF->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.
DF->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->hasInternalLinkage())
ForceRenaming(NewDF, SF->getName());
// Remember this mapping so uses in the source module get remapped
// later by RemapOperand.
ValueMap[SF] = NewDF;
} else if (SF->isDeclaration()) {
// We have two functions of the same name but different type and the
// source is a declaration while the destination is not. Any use of
// the source must be mapped to the destination, with a cast.
ValueMap[SF] = ConstantExpr::getBitCast(DF, SF->getType());
} else {
// We have two functions of the same name but different types and they
// are both definitions. This is an error.
return Error(Err, "Function '" + DF->getName() + "' defined as both '" +
ToStr(SF->getFunctionType(), Src) + "' and '" +
ToStr(DF->getFunctionType(), Dest) + "'");
}
} else if (!DF || SF->hasInternalLinkage() || DF->hasInternalLinkage()) {
// Function does not already exist, simply insert an function signature
// identical to SF into the dest module.
Function *NewDF = new Function(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->getName() != SF->getName() && !NewDF->hasInternalLinkage())
ForceRenaming(NewDF, SF->getName());
// ... and remember this mapping...
ValueMap[SF] = NewDF;
} else if (SF->isDeclaration()) {
// If SF is a declaration or if both SF & DF are declarations, just link
// the declarations, we aren't adding anything.
if (SF->hasDLLImportLinkage()) {
if (DF->isDeclaration()) {
ValueMap.insert(std::make_pair(SF, DF));
DF->setLinkage(SF->getLinkage());
}
} else {
ValueMap[SF] = DF;
}
} else if (DF->isDeclaration() && !DF->hasDLLImportLinkage()) {
// If DF is external but SF is not...
// Link the external functions, update linkage qualifiers
ValueMap.insert(std::make_pair(SF, DF));
DF->setLinkage(SF->getLinkage());
// Visibility of prototype is overridden by vis of definition.
DF->setVisibility(SF->getVisibility());
} else if (SF->hasWeakLinkage() || SF->hasLinkOnceLinkage()) {
// At this point we know that DF has LinkOnce, Weak, or External* linkage.
ValueMap[SF] = DF;
// Linkonce+Weak = Weak
// *+External Weak = *
if ((DF->hasLinkOnceLinkage() && SF->hasWeakLinkage()) ||
DF->hasExternalWeakLinkage())
DF->setLinkage(SF->getLinkage());
} else if (DF->hasWeakLinkage() || DF->hasLinkOnceLinkage()) {
// At this point we know that SF has LinkOnce or External* linkage.
ValueMap[SF] = DF;
if (!SF->hasLinkOnceLinkage() && !SF->hasExternalWeakLinkage())
// Don't inherit linkonce & external weak linkage
DF->setLinkage(SF->getLinkage());
} else if (SF->getLinkage() != DF->getLinkage()) {
return Error(Err, "Functions named '" + SF->getName() +
"' have different linkage specifiers!");
} else if (SF->hasExternalLinkage()) {
// The function is defined identically in both modules!!
return Error(Err, "Function '" +
ToStr(SF->getFunctionType(), Src) + "':\"" +
SF->getName() + "\" - Function is already defined!");
} else {
assert(0 && "Unknown linkage configuration found!");
}
}
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<const Value*, Value*> &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<Instruction>(*OI) && !isa<BasicBlock>(*OI))
*OI = RemapOperand(*OI, ValueMap);
// 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<const Value*, Value*> &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 = cast<Function>(ValueMap[SF]); // Destination function
// DF not external SF external?
if (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(NewType, G1->isConstant(), G1->getLinkage(),
/*init*/0, First->first, M, G1->isThreadLocal());
// 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)
if (const GlobalValue *GV = I->resolveAliasedGlobal())
if (!GV->isDeclaration())
I->replaceAllUsesWith(const_cast<GlobalValue*>(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<const Value*, Value*> 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;
// 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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