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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.
//
//===----------------------------------------------------------------------===//
#include "llvm/Linker/Linker.h"
#include "llvm-c/Linker.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/TypeFinder.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include <cctype>
#include <tuple>
using namespace llvm;
//===----------------------------------------------------------------------===//
// TypeMap implementation.
//===----------------------------------------------------------------------===//
namespace {
typedef SmallPtrSet<StructType*, 32> TypeSet;
class TypeMapTy : public ValueMapTypeRemapper {
/// MappedTypes - This is a mapping from a source type to a destination type
/// to use.
DenseMap<Type*, Type*> MappedTypes;
/// SpeculativeTypes - When checking to see if two subgraphs are isomorphic,
/// we speculatively add types to MappedTypes, but keep track of them here in
/// case we need to roll back.
SmallVector<Type*, 16> SpeculativeTypes;
/// SrcDefinitionsToResolve - This is a list of non-opaque structs in the
/// source module that are mapped to an opaque struct in the destination
/// module.
SmallVector<StructType*, 16> SrcDefinitionsToResolve;
/// DstResolvedOpaqueTypes - This is the set of opaque types in the
/// destination modules who are getting a body from the source module.
SmallPtrSet<StructType*, 16> DstResolvedOpaqueTypes;
public:
TypeMapTy(TypeSet &Set) : DstStructTypesSet(Set) {}
TypeSet &DstStructTypesSet;
/// addTypeMapping - Indicate that the specified type in the destination
/// module is conceptually equivalent to the specified type in the source
/// module.
void addTypeMapping(Type *DstTy, Type *SrcTy);
/// linkDefinedTypeBodies - Produce a body for an opaque type in the dest
/// module from a type definition in the source module.
void linkDefinedTypeBodies();
/// get - Return the mapped type to use for the specified input type from the
/// source module.
Type *get(Type *SrcTy);
FunctionType *get(FunctionType *T) {return cast<FunctionType>(get((Type*)T));}
/// dump - Dump out the type map for debugging purposes.
void dump() const {
for (DenseMap<Type*, Type*>::const_iterator
I = MappedTypes.begin(), E = MappedTypes.end(); I != E; ++I) {
dbgs() << "TypeMap: ";
I->first->print(dbgs());
dbgs() << " => ";
I->second->print(dbgs());
dbgs() << '\n';
}
}
private:
Type *getImpl(Type *T);
/// remapType - Implement the ValueMapTypeRemapper interface.
Type *remapType(Type *SrcTy) override {
return get(SrcTy);
}
bool areTypesIsomorphic(Type *DstTy, Type *SrcTy);
};
}
void TypeMapTy::addTypeMapping(Type *DstTy, Type *SrcTy) {
Type *&Entry = MappedTypes[SrcTy];
if (Entry) return;
if (DstTy == SrcTy) {
Entry = DstTy;
return;
}
// Check to see if these types are recursively isomorphic and establish a
// mapping between them if so.
if (!areTypesIsomorphic(DstTy, SrcTy)) {
// Oops, they aren't isomorphic. Just discard this request by rolling out
// any speculative mappings we've established.
for (unsigned i = 0, e = SpeculativeTypes.size(); i != e; ++i)
MappedTypes.erase(SpeculativeTypes[i]);
}
SpeculativeTypes.clear();
}
/// areTypesIsomorphic - Recursively walk this pair of types, returning true
/// if they are isomorphic, false if they are not.
bool TypeMapTy::areTypesIsomorphic(Type *DstTy, Type *SrcTy) {
// Two types with differing kinds are clearly not isomorphic.
if (DstTy->getTypeID() != SrcTy->getTypeID()) return false;
// If we have an entry in the MappedTypes table, then we have our answer.
Type *&Entry = MappedTypes[SrcTy];
if (Entry)
return Entry == DstTy;
// Two identical types are clearly isomorphic. Remember this
// non-speculatively.
if (DstTy == SrcTy) {
Entry = DstTy;
return true;
}
// Okay, we have two types with identical kinds that we haven't seen before.
// If this is an opaque struct type, special case it.
if (StructType *SSTy = dyn_cast<StructType>(SrcTy)) {
// Mapping an opaque type to any struct, just keep the dest struct.
if (SSTy->isOpaque()) {
Entry = DstTy;
SpeculativeTypes.push_back(SrcTy);
return true;
}
// Mapping a non-opaque source type to an opaque dest. If this is the first
// type that we're mapping onto this destination type then we succeed. Keep
// the dest, but fill it in later. This doesn't need to be speculative. If
// this is the second (different) type that we're trying to map onto the
// same opaque type then we fail.
if (cast<StructType>(DstTy)->isOpaque()) {
// We can only map one source type onto the opaque destination type.
if (!DstResolvedOpaqueTypes.insert(cast<StructType>(DstTy)))
return false;
SrcDefinitionsToResolve.push_back(SSTy);
Entry = DstTy;
return true;
}
}
// If the number of subtypes disagree between the two types, then we fail.
if (SrcTy->getNumContainedTypes() != DstTy->getNumContainedTypes())
return false;
// Fail if any of the extra properties (e.g. array size) of the type disagree.
if (isa<IntegerType>(DstTy))
return false; // bitwidth disagrees.
if (PointerType *PT = dyn_cast<PointerType>(DstTy)) {
if (PT->getAddressSpace() != cast<PointerType>(SrcTy)->getAddressSpace())
return false;
} else if (FunctionType *FT = dyn_cast<FunctionType>(DstTy)) {
if (FT->isVarArg() != cast<FunctionType>(SrcTy)->isVarArg())
return false;
} else if (StructType *DSTy = dyn_cast<StructType>(DstTy)) {
StructType *SSTy = cast<StructType>(SrcTy);
if (DSTy->isLiteral() != SSTy->isLiteral() ||
DSTy->isPacked() != SSTy->isPacked())
return false;
} else if (ArrayType *DATy = dyn_cast<ArrayType>(DstTy)) {
if (DATy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements())
return false;
} else if (VectorType *DVTy = dyn_cast<VectorType>(DstTy)) {
if (DVTy->getNumElements() != cast<VectorType>(SrcTy)->getNumElements())
return false;
}
// Otherwise, we speculate that these two types will line up and recursively
// check the subelements.
Entry = DstTy;
SpeculativeTypes.push_back(SrcTy);
for (unsigned i = 0, e = SrcTy->getNumContainedTypes(); i != e; ++i)
if (!areTypesIsomorphic(DstTy->getContainedType(i),
SrcTy->getContainedType(i)))
return false;
// If everything seems to have lined up, then everything is great.
return true;
}
/// linkDefinedTypeBodies - Produce a body for an opaque type in the dest
/// module from a type definition in the source module.
void TypeMapTy::linkDefinedTypeBodies() {
SmallVector<Type*, 16> Elements;
SmallString<16> TmpName;
// Note that processing entries in this loop (calling 'get') can add new
// entries to the SrcDefinitionsToResolve vector.
while (!SrcDefinitionsToResolve.empty()) {
StructType *SrcSTy = SrcDefinitionsToResolve.pop_back_val();
StructType *DstSTy = cast<StructType>(MappedTypes[SrcSTy]);
// TypeMap is a many-to-one mapping, if there were multiple types that
// provide a body for DstSTy then previous iterations of this loop may have
// already handled it. Just ignore this case.
if (!DstSTy->isOpaque()) continue;
assert(!SrcSTy->isOpaque() && "Not resolving a definition?");
// Map the body of the source type over to a new body for the dest type.
Elements.resize(SrcSTy->getNumElements());
for (unsigned i = 0, e = Elements.size(); i != e; ++i)
Elements[i] = getImpl(SrcSTy->getElementType(i));
DstSTy->setBody(Elements, SrcSTy->isPacked());
// If DstSTy has no name or has a longer name than STy, then viciously steal
// STy's name.
if (!SrcSTy->hasName()) continue;
StringRef SrcName = SrcSTy->getName();
if (!DstSTy->hasName() || DstSTy->getName().size() > SrcName.size()) {
TmpName.insert(TmpName.end(), SrcName.begin(), SrcName.end());
SrcSTy->setName("");
DstSTy->setName(TmpName.str());
TmpName.clear();
}
}
DstResolvedOpaqueTypes.clear();
}
/// get - Return the mapped type to use for the specified input type from the
/// source module.
Type *TypeMapTy::get(Type *Ty) {
Type *Result = getImpl(Ty);
// If this caused a reference to any struct type, resolve it before returning.
if (!SrcDefinitionsToResolve.empty())
linkDefinedTypeBodies();
return Result;
}
/// getImpl - This is the recursive version of get().
Type *TypeMapTy::getImpl(Type *Ty) {
// If we already have an entry for this type, return it.
Type **Entry = &MappedTypes[Ty];
if (*Entry) return *Entry;
// If this is not a named struct type, then just map all of the elements and
// then rebuild the type from inside out.
if (!isa<StructType>(Ty) || cast<StructType>(Ty)->isLiteral()) {
// If there are no element types to map, then the type is itself. This is
// true for the anonymous {} struct, things like 'float', integers, etc.
if (Ty->getNumContainedTypes() == 0)
return *Entry = Ty;
// Remap all of the elements, keeping track of whether any of them change.
bool AnyChange = false;
SmallVector<Type*, 4> ElementTypes;
ElementTypes.resize(Ty->getNumContainedTypes());
for (unsigned i = 0, e = Ty->getNumContainedTypes(); i != e; ++i) {
ElementTypes[i] = getImpl(Ty->getContainedType(i));
AnyChange |= ElementTypes[i] != Ty->getContainedType(i);
}
// If we found our type while recursively processing stuff, just use it.
Entry = &MappedTypes[Ty];
if (*Entry) return *Entry;
// If all of the element types mapped directly over, then the type is usable
// as-is.
if (!AnyChange)
return *Entry = Ty;
// Otherwise, rebuild a modified type.
switch (Ty->getTypeID()) {
default: llvm_unreachable("unknown derived type to remap");
case Type::ArrayTyID:
return *Entry = ArrayType::get(ElementTypes[0],
cast<ArrayType>(Ty)->getNumElements());
case Type::VectorTyID:
return *Entry = VectorType::get(ElementTypes[0],
cast<VectorType>(Ty)->getNumElements());
case Type::PointerTyID:
return *Entry = PointerType::get(ElementTypes[0],
cast<PointerType>(Ty)->getAddressSpace());
case Type::FunctionTyID:
return *Entry = FunctionType::get(ElementTypes[0],
makeArrayRef(ElementTypes).slice(1),
cast<FunctionType>(Ty)->isVarArg());
case Type::StructTyID:
// Note that this is only reached for anonymous structs.
return *Entry = StructType::get(Ty->getContext(), ElementTypes,
cast<StructType>(Ty)->isPacked());
}
}
// Otherwise, this is an unmapped named struct. If the struct can be directly
// mapped over, just use it as-is. This happens in a case when the linked-in
// module has something like:
// %T = type {%T*, i32}
// @GV = global %T* null
// where T does not exist at all in the destination module.
//
// The other case we watch for is when the type is not in the destination
// module, but that it has to be rebuilt because it refers to something that
// is already mapped. For example, if the destination module has:
// %A = type { i32 }
// and the source module has something like
// %A' = type { i32 }
// %B = type { %A'* }
// @GV = global %B* null
// then we want to create a new type: "%B = type { %A*}" and have it take the
// pristine "%B" name from the source module.
//
// To determine which case this is, we have to recursively walk the type graph
// speculating that we'll be able to reuse it unmodified. Only if this is
// safe would we map the entire thing over. Because this is an optimization,
// and is not required for the prettiness of the linked module, we just skip
// it and always rebuild a type here.
StructType *STy = cast<StructType>(Ty);
// If the type is opaque, we can just use it directly.
if (STy->isOpaque()) {
// A named structure type from src module is used. Add it to the Set of
// identified structs in the destination module.
DstStructTypesSet.insert(STy);
return *Entry = STy;
}
// Otherwise we create a new type and resolve its body later. This will be
// resolved by the top level of get().
SrcDefinitionsToResolve.push_back(STy);
StructType *DTy = StructType::create(STy->getContext());
// A new identified structure type was created. Add it to the set of
// identified structs in the destination module.
DstStructTypesSet.insert(DTy);
DstResolvedOpaqueTypes.insert(DTy);
return *Entry = DTy;
}
//===----------------------------------------------------------------------===//
// ModuleLinker implementation.
//===----------------------------------------------------------------------===//
namespace {
class ModuleLinker;
/// ValueMaterializerTy - Creates prototypes for functions that are lazily
/// linked on the fly. This speeds up linking for modules with many
/// lazily linked functions of which few get used.
class ValueMaterializerTy : public ValueMaterializer {
TypeMapTy &TypeMap;
Module *DstM;
std::vector<Function*> &LazilyLinkFunctions;
public:
ValueMaterializerTy(TypeMapTy &TypeMap, Module *DstM,
std::vector<Function*> &LazilyLinkFunctions) :
ValueMaterializer(), TypeMap(TypeMap), DstM(DstM),
LazilyLinkFunctions(LazilyLinkFunctions) {
}
Value *materializeValueFor(Value *V) override;
};
/// ModuleLinker - This is an implementation class for the LinkModules
/// function, which is the entrypoint for this file.
class ModuleLinker {
Module *DstM, *SrcM;
TypeMapTy TypeMap;
ValueMaterializerTy ValMaterializer;
/// ValueMap - Mapping of values from what they used to be in Src, to what
/// they are now in DstM. ValueToValueMapTy is a ValueMap, which involves
/// some overhead due to the use of Value handles which the Linker doesn't
/// actually need, but this allows us to reuse the ValueMapper code.
ValueToValueMapTy ValueMap;
struct AppendingVarInfo {
GlobalVariable *NewGV; // New aggregate global in dest module.
Constant *DstInit; // Old initializer from dest module.
Constant *SrcInit; // Old initializer from src module.
};
std::vector<AppendingVarInfo> AppendingVars;
unsigned Mode; // Mode to treat source module.
// Set of items not to link in from source.
SmallPtrSet<const Value*, 16> DoNotLinkFromSource;
// Vector of functions to lazily link in.
std::vector<Function*> LazilyLinkFunctions;
bool SuppressWarnings;
public:
std::string ErrorMsg;
ModuleLinker(Module *dstM, TypeSet &Set, Module *srcM, unsigned mode,
bool SuppressWarnings=false)
: DstM(dstM), SrcM(srcM), TypeMap(Set),
ValMaterializer(TypeMap, DstM, LazilyLinkFunctions), Mode(mode),
SuppressWarnings(SuppressWarnings) {}
bool run();
private:
bool shouldLinkFromSource(const GlobalValue &Dest, const GlobalValue &Src);
/// emitError - Helper method for setting a message and returning an error
/// code.
bool emitError(const Twine &Message) {
ErrorMsg = Message.str();
return true;
}
bool getComdatLeader(Module *M, StringRef ComdatName,
const GlobalVariable *&GVar);
bool computeResultingSelectionKind(StringRef ComdatName,
Comdat::SelectionKind Src,
Comdat::SelectionKind Dst,
Comdat::SelectionKind &Result,
bool &LinkFromSrc);
std::map<const Comdat *, std::pair<Comdat::SelectionKind, bool>>
ComdatsChosen;
bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
bool &LinkFromSrc);
/// getLinkageResult - This analyzes the two global values and determines
/// what the result will look like in the destination module.
bool getLinkageResult(GlobalValue *Dest, const GlobalValue *Src,
GlobalValue::LinkageTypes &LT,
GlobalValue::VisibilityTypes &Vis,
bool &LinkFromSrc);
/// getLinkedToGlobal - Given a global in the source module, return the
/// global in the destination module that is being linked to, if any.
GlobalValue *getLinkedToGlobal(GlobalValue *SrcGV) {
// If the source has no name it can't link. If it has local linkage,
// there is no name match-up going on.
if (!SrcGV->hasName() || SrcGV->hasLocalLinkage())
return nullptr;
// Otherwise see if we have a match in the destination module's symtab.
GlobalValue *DGV = DstM->getNamedValue(SrcGV->getName());
if (!DGV) return nullptr;
// If we found a global with the same name in the dest module, but it has
// internal linkage, we are really not doing any linkage here.
if (DGV->hasLocalLinkage())
return nullptr;
// Otherwise, we do in fact link to the destination global.
return DGV;
}
void computeTypeMapping();
void upgradeMismatchedGlobalArray(StringRef Name);
void upgradeMismatchedGlobals();
bool linkAppendingVarProto(GlobalVariable *DstGV, GlobalVariable *SrcGV);
bool linkGlobalProto(GlobalVariable *SrcGV);
bool linkFunctionProto(Function *SrcF);
bool linkAliasProto(GlobalAlias *SrcA);
bool linkModuleFlagsMetadata();
void linkAppendingVarInit(const AppendingVarInfo &AVI);
void linkGlobalInits();
void linkFunctionBody(Function *Dst, Function *Src);
void linkAliasBodies();
void linkNamedMDNodes();
};
}
/// 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, StringRef Name) {
// If the global doesn't force its name or if it already has the right name,
// there is nothing for us to do.
if (GV->hasLocalLinkage() || GV->getName() == Name)
return;
Module *M = GV->getParent();
// If there is a conflict, rename the conflict.
if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
GV->takeName(ConflictGV);
ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
} else {
GV->setName(Name); // Force the name back
}
}
/// 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.
auto *DestGO = dyn_cast<GlobalObject>(DestGV);
unsigned Alignment;
if (DestGO)
Alignment = std::max(DestGO->getAlignment(), SrcGV->getAlignment());
DestGV->copyAttributesFrom(SrcGV);
if (DestGO)
DestGO->setAlignment(Alignment);
forceRenaming(DestGV, SrcGV->getName());
}
static bool isLessConstraining(GlobalValue::VisibilityTypes a,
GlobalValue::VisibilityTypes b) {
if (a == GlobalValue::HiddenVisibility)
return false;
if (b == GlobalValue::HiddenVisibility)
return true;
if (a == GlobalValue::ProtectedVisibility)
return false;
if (b == GlobalValue::ProtectedVisibility)
return true;
return false;
}
Value *ValueMaterializerTy::materializeValueFor(Value *V) {
Function *SF = dyn_cast<Function>(V);
if (!SF)
return nullptr;
Function *DF = Function::Create(TypeMap.get(SF->getFunctionType()),
SF->getLinkage(), SF->getName(), DstM);
copyGVAttributes(DF, SF);
if (Comdat *SC = SF->getComdat()) {
Comdat *DC = DstM->getOrInsertComdat(SC->getName());
DF->setComdat(DC);
}
LazilyLinkFunctions.push_back(SF);
return DF;
}
bool ModuleLinker::getComdatLeader(Module *M, StringRef ComdatName,
const GlobalVariable *&GVar) {
const GlobalValue *GVal = M->getNamedValue(ComdatName);
if (const auto *GA = dyn_cast_or_null<GlobalAlias>(GVal)) {
GVal = GA->getBaseObject();
if (!GVal)
// We cannot resolve the size of the aliasee yet.
return emitError("Linking COMDATs named '" + ComdatName +
"': COMDAT key involves incomputable alias size.");
}
GVar = dyn_cast_or_null<GlobalVariable>(GVal);
if (!GVar)
return emitError(
"Linking COMDATs named '" + ComdatName +
"': GlobalVariable required for data dependent selection!");
return false;
}
bool ModuleLinker::computeResultingSelectionKind(StringRef ComdatName,
Comdat::SelectionKind Src,
Comdat::SelectionKind Dst,
Comdat::SelectionKind &Result,
bool &LinkFromSrc) {
// The ability to mix Comdat::SelectionKind::Any with
// Comdat::SelectionKind::Largest is a behavior that comes from COFF.
bool DstAnyOrLargest = Dst == Comdat::SelectionKind::Any ||
Dst == Comdat::SelectionKind::Largest;
bool SrcAnyOrLargest = Src == Comdat::SelectionKind::Any ||
Src == Comdat::SelectionKind::Largest;
if (DstAnyOrLargest && SrcAnyOrLargest) {
if (Dst == Comdat::SelectionKind::Largest ||
Src == Comdat::SelectionKind::Largest)
Result = Comdat::SelectionKind::Largest;
else
Result = Comdat::SelectionKind::Any;
} else if (Src == Dst) {
Result = Dst;
} else {
return emitError("Linking COMDATs named '" + ComdatName +
"': invalid selection kinds!");
}
switch (Result) {
case Comdat::SelectionKind::Any:
// Go with Dst.
LinkFromSrc = false;
break;
case Comdat::SelectionKind::NoDuplicates:
return emitError("Linking COMDATs named '" + ComdatName +
"': noduplicates has been violated!");
case Comdat::SelectionKind::ExactMatch:
case Comdat::SelectionKind::Largest:
case Comdat::SelectionKind::SameSize: {
const GlobalVariable *DstGV;
const GlobalVariable *SrcGV;
if (getComdatLeader(DstM, ComdatName, DstGV) ||
getComdatLeader(SrcM, ComdatName, SrcGV))
return true;
const DataLayout *DstDL = DstM->getDataLayout();
const DataLayout *SrcDL = SrcM->getDataLayout();
if (!DstDL || !SrcDL) {
return emitError(
"Linking COMDATs named '" + ComdatName +
"': can't do size dependent selection without DataLayout!");
}
uint64_t DstSize =
DstDL->getTypeAllocSize(DstGV->getType()->getPointerElementType());
uint64_t SrcSize =
SrcDL->getTypeAllocSize(SrcGV->getType()->getPointerElementType());
if (Result == Comdat::SelectionKind::ExactMatch) {
if (SrcGV->getInitializer() != DstGV->getInitializer())
return emitError("Linking COMDATs named '" + ComdatName +
"': ExactMatch violated!");
LinkFromSrc = false;
} else if (Result == Comdat::SelectionKind::Largest) {
LinkFromSrc = SrcSize > DstSize;
} else if (Result == Comdat::SelectionKind::SameSize) {
if (SrcSize != DstSize)
return emitError("Linking COMDATs named '" + ComdatName +
"': SameSize violated!");
LinkFromSrc = false;
} else {
llvm_unreachable("unknown selection kind");
}
break;
}
}
return false;
}
bool ModuleLinker::getComdatResult(const Comdat *SrcC,
Comdat::SelectionKind &Result,
bool &LinkFromSrc) {
Comdat::SelectionKind SSK = SrcC->getSelectionKind();
StringRef ComdatName = SrcC->getName();
Module::ComdatSymTabType &ComdatSymTab = DstM->getComdatSymbolTable();
Module::ComdatSymTabType::iterator DstCI = ComdatSymTab.find(ComdatName);
if (DstCI == ComdatSymTab.end()) {
// Use the comdat if it is only available in one of the modules.
LinkFromSrc = true;
Result = SSK;
return false;
}
const Comdat *DstC = &DstCI->second;
Comdat::SelectionKind DSK = DstC->getSelectionKind();
return computeResultingSelectionKind(ComdatName, SSK, DSK, Result,
LinkFromSrc);
}
// FIXME: Duplicated from the gold plugin. This should be refactored somewhere.
static bool isDeclaration(const GlobalValue &V) {
if (V.hasAvailableExternallyLinkage())
return true;
if (V.isMaterializable())
return false;
return V.isDeclaration();
}
bool ModuleLinker::shouldLinkFromSource(const GlobalValue &Dest,
const GlobalValue &Src) {
bool SrcIsDeclaration = isDeclaration(Src);
bool DestIsDeclaration = isDeclaration(Dest);
// FIXME: Make datalayout mandatory and just use getDataLayout().
DataLayout DL(Dest.getParent());
if (SrcIsDeclaration) {
// If Src is external or if both Src & Dest are external.. Just link the
// external globals, we aren't adding anything.
if (Src.hasDLLImportStorageClass())
// If one of GVs is marked as DLLImport, result should be dllimport'ed.
return DestIsDeclaration;
// If the Dest is weak, use the source linkage.
return Dest.hasExternalWeakLinkage();
}
if (DestIsDeclaration)
// If Dest is external but Src is not:
return true;
if (Src.hasCommonLinkage()) {
if (Dest.hasLinkOnceLinkage() || Dest.hasWeakLinkage())
return true;
if (!Dest.hasCommonLinkage())
return false;
uint64_t DestSize = DL.getTypeAllocSize(Dest.getType()->getElementType());
uint64_t SrcSize = DL.getTypeAllocSize(Src.getType()->getElementType());
return SrcSize > DestSize;
}
if (Src.isWeakForLinker()) {
assert(!Dest.hasExternalWeakLinkage());
assert(!Dest.hasAvailableExternallyLinkage());
if (Dest.hasLinkOnceLinkage() && Src.hasWeakLinkage())
return true;
return false;
}
if (Dest.isWeakForLinker()) {
assert(Src.hasExternalLinkage());
return true;
}
assert(!Src.hasExternalWeakLinkage());
assert(!Dest.hasExternalWeakLinkage());
assert(Dest.hasExternalLinkage() && Src.hasExternalLinkage() &&
"Unexpected linkage type!");
return emitError("Linking globals named '" + Src.getName() +
"': symbol multiply defined!");
}
/// 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 and visibility, 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.
bool ModuleLinker::getLinkageResult(GlobalValue *Dest, const GlobalValue *Src,
GlobalValue::LinkageTypes &LT,
GlobalValue::VisibilityTypes &Vis,
bool &LinkFromSrc) {
assert(Dest && "Must have two globals being queried");
assert(!Src->hasLocalLinkage() &&
"If Src has internal linkage, Dest shouldn't be set!");
assert(ErrorMsg.empty());
LinkFromSrc = shouldLinkFromSource(*Dest, *Src);
if (!ErrorMsg.empty())
return true;
if (LinkFromSrc)
LT = Src->getLinkage();
else
LT = Dest->getLinkage();
// Compute the visibility. We follow the rules in the System V Application
// Binary Interface.
assert(!GlobalValue::isLocalLinkage(LT) &&
"Symbols with local linkage should not be merged");
Vis = isLessConstraining(Src->getVisibility(), Dest->getVisibility()) ?
Dest->getVisibility() : Src->getVisibility();
return false;
}
/// computeTypeMapping - Loop over all of the linked values to compute type
/// mappings. For example, if we link "extern Foo *x" and "Foo *x = NULL", then
/// we have two struct types 'Foo' but one got renamed when the module was
/// loaded into the same LLVMContext.
void ModuleLinker::computeTypeMapping() {
// Incorporate globals.
for (Module::global_iterator I = SrcM->global_begin(),
E = SrcM->global_end(); I != E; ++I) {
GlobalValue *DGV = getLinkedToGlobal(I);
if (!DGV) continue;
if (!DGV->hasAppendingLinkage() || !I->hasAppendingLinkage()) {
TypeMap.addTypeMapping(DGV->getType(), I->getType());
continue;
}
// Unify the element type of appending arrays.
ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
ArrayType *SAT = cast<ArrayType>(I->getType()->getElementType());
TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
}
// Incorporate functions.
for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I) {
if (GlobalValue *DGV = getLinkedToGlobal(I))
TypeMap.addTypeMapping(DGV->getType(), I->getType());
}
// Incorporate types by name, scanning all the types in the source module.
// At this point, the destination module may have a type "%foo = { i32 }" for
// example. When the source module got loaded into the same LLVMContext, if
// it had the same type, it would have been renamed to "%foo.42 = { i32 }".
TypeFinder SrcStructTypes;
SrcStructTypes.run(*SrcM, true);
SmallPtrSet<StructType*, 32> SrcStructTypesSet(SrcStructTypes.begin(),
SrcStructTypes.end());
for (unsigned i = 0, e = SrcStructTypes.size(); i != e; ++i) {
StructType *ST = SrcStructTypes[i];
if (!ST->hasName()) continue;
// Check to see if there is a dot in the name followed by a digit.
size_t DotPos = ST->getName().rfind('.');
if (DotPos == 0 || DotPos == StringRef::npos ||
ST->getName().back() == '.' ||
!isdigit(static_cast<unsigned char>(ST->getName()[DotPos+1])))
continue;
// Check to see if the destination module has a struct with the prefix name.
if (StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos)))
// Don't use it if this actually came from the source module. They're in
// the same LLVMContext after all. Also don't use it unless the type is
// actually used in the destination module. This can happen in situations
// like this:
//
// Module A Module B
// -------- --------
// %Z = type { %A } %B = type { %C.1 }
// %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
// %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
// %C = type { i8* } %B.3 = type { %C.1 }
//
// When we link Module B with Module A, the '%B' in Module B is
// used. However, that would then use '%C.1'. But when we process '%C.1',
// we prefer to take the '%C' version. So we are then left with both
// '%C.1' and '%C' being used for the same types. This leads to some
// variables using one type and some using the other.
if (!SrcStructTypesSet.count(DST) && TypeMap.DstStructTypesSet.count(DST))
TypeMap.addTypeMapping(DST, ST);
}
// Don't bother incorporating aliases, they aren't generally typed well.
// Now that we have discovered all of the type equivalences, get a body for
// any 'opaque' types in the dest module that are now resolved.
TypeMap.linkDefinedTypeBodies();
}
static void upgradeGlobalArray(GlobalVariable *GV) {
ArrayType *ATy = cast<ArrayType>(GV->getType()->getElementType());
StructType *OldTy = cast<StructType>(ATy->getElementType());
assert(OldTy->getNumElements() == 2 && "Expected to upgrade from 2 elements");
// Get the upgraded 3 element type.
PointerType *VoidPtrTy = Type::getInt8Ty(GV->getContext())->getPointerTo();
Type *Tys[3] = {OldTy->getElementType(0), OldTy->getElementType(1),
VoidPtrTy};
StructType *NewTy = StructType::get(GV->getContext(), Tys, false);
// Build new constants with a null third field filled in.
Constant *OldInitC = GV->getInitializer();
ConstantArray *OldInit = dyn_cast<ConstantArray>(OldInitC);
if (!OldInit && !isa<ConstantAggregateZero>(OldInitC))
// Invalid initializer; give up.
return;
std::vector<Constant *> Initializers;
if (OldInit && OldInit->getNumOperands()) {
Value *Null = Constant::getNullValue(VoidPtrTy);
for (Use &U : OldInit->operands()) {
ConstantStruct *Init = cast<ConstantStruct>(U.get());
Initializers.push_back(ConstantStruct::get(
NewTy, Init->getOperand(0), Init->getOperand(1), Null, nullptr));
}
}
assert(Initializers.size() == ATy->getNumElements() &&
"Failed to copy all array elements");
// Replace the old GV with a new one.
ATy = ArrayType::get(NewTy, Initializers.size());
Constant *NewInit = ConstantArray::get(ATy, Initializers);
GlobalVariable *NewGV = new GlobalVariable(
*GV->getParent(), ATy, GV->isConstant(), GV->getLinkage(), NewInit, "",
GV, GV->getThreadLocalMode(), GV->getType()->getAddressSpace(),
GV->isExternallyInitialized());
NewGV->copyAttributesFrom(GV);
NewGV->takeName(GV);
assert(GV->use_empty() && "program cannot use initializer list");
GV->eraseFromParent();
}
void ModuleLinker::upgradeMismatchedGlobalArray(StringRef Name) {
// Look for the global arrays.
auto *DstGV = dyn_cast_or_null<GlobalVariable>(DstM->getNamedValue(Name));
if (!DstGV)
return;
auto *SrcGV = dyn_cast_or_null<GlobalVariable>(SrcM->getNamedValue(Name));
if (!SrcGV)
return;
// Check if the types already match.
auto *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
auto *SrcTy =
cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
if (DstTy == SrcTy)
return;
// Grab the element types. We can only upgrade an array of a two-field
// struct. Only bother if the other one has three-fields.
auto *DstEltTy = cast<StructType>(DstTy->getElementType());
auto *SrcEltTy = cast<StructType>(SrcTy->getElementType());
if (DstEltTy->getNumElements() == 2 && SrcEltTy->getNumElements() == 3) {
upgradeGlobalArray(DstGV);
return;
}
if (DstEltTy->getNumElements() == 3 && SrcEltTy->getNumElements() == 2)
upgradeGlobalArray(SrcGV);
// We can't upgrade any other differences.
}
void ModuleLinker::upgradeMismatchedGlobals() {
upgradeMismatchedGlobalArray("llvm.global_ctors");
upgradeMismatchedGlobalArray("llvm.global_dtors");
}
/// linkAppendingVarProto - If there were any appending global variables, link
/// them together now. Return true on error.
bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
GlobalVariable *SrcGV) {
if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
return emitError("Linking globals named '" + SrcGV->getName() +
"': can only link appending global with another appending global!");
ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
ArrayType *SrcTy =
cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
Type *EltTy = DstTy->getElementType();
// Check to see that they two arrays agree on type.
if (EltTy != SrcTy->getElementType())
return emitError("Appending variables with different element types!");
if (DstGV->isConstant() != SrcGV->isConstant())
return emitError("Appending variables linked with different const'ness!");
if (DstGV->getAlignment() != SrcGV->getAlignment())
return emitError(
"Appending variables with different alignment need to be linked!");
if (DstGV->getVisibility() != SrcGV->getVisibility())
return emitError(
"Appending variables with different visibility need to be linked!");
if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr())
return emitError(
"Appending variables with different unnamed_addr need to be linked!");
if (StringRef(DstGV->getSection()) != SrcGV->getSection())
return emitError(
"Appending variables with different section name need to be linked!");
uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements();
ArrayType *NewType = ArrayType::get(EltTy, NewSize);
// Create the new global variable.
GlobalVariable *NG =
new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(),
DstGV->getLinkage(), /*init*/nullptr, /*name*/"", DstGV,
DstGV->getThreadLocalMode(),
DstGV->getType()->getAddressSpace());
// Propagate alignment, visibility and section info.
copyGVAttributes(NG, DstGV);
AppendingVarInfo AVI;
AVI.NewGV = NG;
AVI.DstInit = DstGV->getInitializer();
AVI.SrcInit = SrcGV->getInitializer();
AppendingVars.push_back(AVI);
// Replace any uses of the two global variables with uses of the new
// global.
ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
DstGV->eraseFromParent();
// Track the source variable so we don't try to link it.
DoNotLinkFromSource.insert(SrcGV);
return false;
}
/// linkGlobalProto - Loop through the global variables in the src module and
/// merge them into the dest module.
bool ModuleLinker::linkGlobalProto(GlobalVariable *SGV) {
GlobalValue *DGV = getLinkedToGlobal(SGV);
llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
bool HasUnnamedAddr = SGV->hasUnnamedAddr();
unsigned Alignment = SGV->getAlignment();
bool LinkFromSrc = false;
Comdat *DC = nullptr;
if (const Comdat *SC = SGV->getComdat()) {
Comdat::SelectionKind SK;
std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
DC = DstM->getOrInsertComdat(SC->getName());
DC->setSelectionKind(SK);
}
if (DGV) {
if (!DC) {
// Concatenation of appending linkage variables is magic and handled later.
if (DGV->hasAppendingLinkage() || SGV->hasAppendingLinkage())
return linkAppendingVarProto(cast<GlobalVariable>(DGV), SGV);
// Determine whether linkage of these two globals follows the source
// module's definition or the destination module's definition.
GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
GlobalValue::VisibilityTypes NV;
if (getLinkageResult(DGV, SGV, NewLinkage, NV, LinkFromSrc))
return true;
NewVisibility = NV;
HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
if (DGV->hasCommonLinkage() && SGV->hasCommonLinkage())
Alignment = std::max(Alignment, DGV->getAlignment());
else if (!LinkFromSrc)
Alignment = DGV->getAlignment();
// If we're not linking from the source, then keep the definition that we
// have.
if (!LinkFromSrc) {
// Special case for const propagation.
if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) {
DGVar->setAlignment(Alignment);
if (DGVar->isDeclaration() && SGV->isConstant() &&
!DGVar->isConstant())
DGVar->setConstant(true);
}
// Set calculated linkage, visibility and unnamed_addr.
DGV->setLinkage(NewLinkage);
DGV->setVisibility(*NewVisibility);
DGV->setUnnamedAddr(HasUnnamedAddr);
}
}
if (!LinkFromSrc) {
// Make sure to remember this mapping.
ValueMap[SGV] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGV->getType()));
// Track the source global so that we don't attempt to copy it over when
// processing global initializers.
DoNotLinkFromSource.insert(SGV);
return false;
}
}
// If the Comdat this variable was inside of wasn't selected, skip it.
if (DC && !DGV && !LinkFromSrc) {
DoNotLinkFromSource.insert(SGV);
return false;
}
// No linking to be performed or linking from the source: simply create an
// identical version of the symbol over in the dest module... the
// initializer will be filled in later by LinkGlobalInits.
GlobalVariable *NewDGV =
new GlobalVariable(*DstM, TypeMap.get(SGV->getType()->getElementType()),
SGV->isConstant(), SGV->getLinkage(), /*init*/nullptr,
SGV->getName(), /*insertbefore*/nullptr,
SGV->getThreadLocalMode(),
SGV->getType()->getAddressSpace());
// Propagate alignment, visibility and section info.
copyGVAttributes(NewDGV, SGV);
NewDGV->setAlignment(Alignment);
if (NewVisibility)
NewDGV->setVisibility(*NewVisibility);
NewDGV->setUnnamedAddr(HasUnnamedAddr);
if (DC)
NewDGV->setComdat(DC);
if (DGV) {
DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, DGV->getType()));
DGV->eraseFromParent();
}
// Make sure to remember this mapping.
ValueMap[SGV] = NewDGV;
return false;
}
/// linkFunctionProto - Link the function in the source module into the
/// destination module if needed, setting up mapping information.
bool ModuleLinker::linkFunctionProto(Function *SF) {
GlobalValue *DGV = getLinkedToGlobal(SF);
llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
bool HasUnnamedAddr = SF->hasUnnamedAddr();
bool LinkFromSrc = false;
Comdat *DC = nullptr;
if (const Comdat *SC = SF->getComdat()) {
Comdat::SelectionKind SK;
std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
DC = DstM->getOrInsertComdat(SC->getName());
DC->setSelectionKind(SK);
}
if (DGV) {
if (!DC) {
GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
GlobalValue::VisibilityTypes NV;
if (getLinkageResult(DGV, SF, NewLinkage, NV, LinkFromSrc))
return true;
NewVisibility = NV;
HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
if (!LinkFromSrc) {
// Set calculated linkage
DGV->setLinkage(NewLinkage);
DGV->setVisibility(*NewVisibility);
DGV->setUnnamedAddr(HasUnnamedAddr);
}
}
if (!LinkFromSrc) {
// Make sure to remember this mapping.
ValueMap[SF] = ConstantExpr::getBitCast(DGV, TypeMap.get(SF->getType()));
// Track the function from the source module so we don't attempt to remap
// it.
DoNotLinkFromSource.insert(SF);
return false;
}
}
// If the function is to be lazily linked, don't create it just yet.
// The ValueMaterializerTy will deal with creating it if it's used.
if (!DGV && (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() ||
SF->hasAvailableExternallyLinkage())) {
DoNotLinkFromSource.insert(SF);
return false;
}
// If the Comdat this function was inside of wasn't selected, skip it.
if (DC && !DGV && !LinkFromSrc) {
DoNotLinkFromSource.insert(SF);
return false;
}
// If there is no linkage to be performed or we are linking from the source,
// bring SF over.
Function *NewDF = Function::Create(TypeMap.get(SF->getFunctionType()),
SF->getLinkage(), SF->getName(), DstM);
copyGVAttributes(NewDF, SF);
if (NewVisibility)
NewDF->setVisibility(*NewVisibility);
NewDF->setUnnamedAddr(HasUnnamedAddr);
if (DC)
NewDF->setComdat(DC);
if (DGV) {
// Any uses of DF need to change to NewDF, with cast.
DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, DGV->getType()));
DGV->eraseFromParent();
}
ValueMap[SF] = NewDF;
return false;
}
/// LinkAliasProto - Set up prototypes for any aliases that come over from the
/// source module.
bool ModuleLinker::linkAliasProto(GlobalAlias *SGA) {
GlobalValue *DGV = getLinkedToGlobal(SGA);
llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
bool HasUnnamedAddr = SGA->hasUnnamedAddr();
bool LinkFromSrc = false;
Comdat *DC = nullptr;
if (const Comdat *SC = SGA->getComdat()) {
Comdat::SelectionKind SK;
std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
DC = DstM->getOrInsertComdat(SC->getName());
DC->setSelectionKind(SK);
}
if (DGV) {
if (!DC) {
GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
GlobalValue::VisibilityTypes NV;
if (getLinkageResult(DGV, SGA, NewLinkage, NV, LinkFromSrc))
return true;
NewVisibility = NV;
HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
if (!LinkFromSrc) {
// Set calculated linkage.
DGV->setLinkage(NewLinkage);
DGV->setVisibility(*NewVisibility);
DGV->setUnnamedAddr(HasUnnamedAddr);
}
}
if (!LinkFromSrc) {
// Make sure to remember this mapping.
ValueMap[SGA] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGA->getType()));
// Track the alias from the source module so we don't attempt to remap it.
DoNotLinkFromSource.insert(SGA);
return false;
}
}
// If the Comdat this alias was inside of wasn't selected, skip it.
if (DC && !DGV && !LinkFromSrc) {
DoNotLinkFromSource.insert(SGA);
return false;
}
// If there is no linkage to be performed or we're linking from the source,
// bring over SGA.
auto *PTy = cast<PointerType>(TypeMap.get(SGA->getType()));
auto *NewDA =
GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(),
SGA->getLinkage(), SGA->getName(), DstM);
copyGVAttributes(NewDA, SGA);
if (NewVisibility)
NewDA->setVisibility(*NewVisibility);
NewDA->setUnnamedAddr(HasUnnamedAddr);
if (DGV) {
// Any uses of DGV need to change to NewDA, with cast.
DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDA, DGV->getType()));
DGV->eraseFromParent();
}
ValueMap[SGA] = NewDA;
return false;
}
static void getArrayElements(Constant *C, SmallVectorImpl<Constant*> &Dest) {
unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
for (unsigned i = 0; i != NumElements; ++i)
Dest.push_back(C->getAggregateElement(i));
}
void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) {
// Merge the initializer.
SmallVector<Constant *, 16> DstElements;
getArrayElements(AVI.DstInit, DstElements);
SmallVector<Constant *, 16> SrcElements;
getArrayElements(AVI.SrcInit, SrcElements);
ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
StringRef Name = AVI.NewGV->getName();
bool IsNewStructor =
(Name == "llvm.global_ctors" || Name == "llvm.global_dtors") &&
cast<StructType>(NewType->getElementType())->getNumElements() == 3;
for (auto *V : SrcElements) {
if (IsNewStructor) {
Constant *Key = V->getAggregateElement(2);
if (DoNotLinkFromSource.count(Key))
continue;
}
DstElements.push_back(
MapValue(V, ValueMap, RF_None, &TypeMap, &ValMaterializer));
}
if (IsNewStructor) {
NewType = ArrayType::get(NewType->getElementType(), DstElements.size());
AVI.NewGV->mutateType(PointerType::get(NewType, 0));
}
AVI.NewGV->setInitializer(ConstantArray::get(NewType, DstElements));
}
/// linkGlobalInits - Update the initializers in the Dest module now that all
/// globals that may be referenced are in Dest.
void ModuleLinker::linkGlobalInits() {
// Loop over all of the globals in the src module, mapping them over as we go
for (Module::const_global_iterator I = SrcM->global_begin(),
E = SrcM->global_end(); I != E; ++I) {
// Only process initialized GV's or ones not already in dest.
if (!I->hasInitializer() || DoNotLinkFromSource.count(I)) continue;
// Grab destination global variable.
GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[I]);
// Figure out what the initializer looks like in the dest module.
DGV->setInitializer(MapValue(I->getInitializer(), ValueMap,
RF_None, &TypeMap, &ValMaterializer));
}
}
/// 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.
void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) {
assert(Src && Dst && Dst->isDeclaration() && !Src->isDeclaration());
// Go through and convert function arguments over, remembering the mapping.
Function::arg_iterator DI = Dst->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 over.
// Add a mapping to our mapping.
ValueMap[I] = DI;
}
if (Mode == Linker::DestroySource) {
// Splice the body of the source function into the dest function.
Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList());
// At this point, all of the instructions and values of the function are now
// copied over. The only problem is that they are still referencing values in
// the Source function as operands. Loop through all of the operands of the
// functions and patch them up to point to the local versions.
for (Function::iterator BB = Dst->begin(), BE = Dst->end(); BB != BE; ++BB)
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries,
&TypeMap, &ValMaterializer);
} else {
// Clone the body of the function into the dest function.
SmallVector<ReturnInst*, 8> Returns; // Ignore returns.
CloneFunctionInto(Dst, Src, ValueMap, false, Returns, "", nullptr,
&TypeMap, &ValMaterializer);
}
// 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);
}
/// linkAliasBodies - Insert all of the aliases in Src into the Dest module.
void ModuleLinker::linkAliasBodies() {
for (Module::alias_iterator I = SrcM->alias_begin(), E = SrcM->alias_end();
I != E; ++I) {
if (DoNotLinkFromSource.count(I))
continue;
if (Constant *Aliasee = I->getAliasee()) {
GlobalAlias *DA = cast<GlobalAlias>(ValueMap[I]);
Constant *Val =
MapValue(Aliasee, ValueMap, RF_None, &TypeMap, &ValMaterializer);
DA->setAliasee(Val);
}
}
}
/// linkNamedMDNodes - Insert all of the named MDNodes in Src into the Dest
/// module.
void ModuleLinker::linkNamedMDNodes() {
const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
for (Module::const_named_metadata_iterator I = SrcM->named_metadata_begin(),
E = SrcM->named_metadata_end(); I != E; ++I) {
// Don't link module flags here. Do them separately.
if (&*I == SrcModFlags) continue;
NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName());
// Add Src elements into Dest node.
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
DestNMD->addOperand(MapValue(I->getOperand(i), ValueMap,
RF_None, &TypeMap, &ValMaterializer));
}
}
/// linkModuleFlagsMetadata - Merge the linker flags in Src into the Dest
/// module.
bool ModuleLinker::linkModuleFlagsMetadata() {
// If the source module has no module flags, we are done.
const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
if (!SrcModFlags) return false;
// If the destination module doesn't have module flags yet, then just copy
// over the source module's flags.
NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
if (DstModFlags->getNumOperands() == 0) {
for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
DstModFlags->addOperand(SrcModFlags->getOperand(I));
return false;
}
// First build a map of the existing module flags and requirements.
DenseMap<MDString*, MDNode*> Flags;
SmallSetVector<MDNode*, 16> Requirements;
for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
MDNode *Op = DstModFlags->getOperand(I);
ConstantInt *Behavior = cast<ConstantInt>(Op->getOperand(0));
MDString *ID = cast<MDString>(Op->getOperand(1));
if (Behavior->getZExtValue() == Module::Require) {
Requirements.insert(cast<MDNode>(Op->getOperand(2)));
} else {
Flags[ID] = Op;
}
}
// Merge in the flags from the source module, and also collect its set of
// requirements.
bool HasErr = false;
for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
MDNode *SrcOp = SrcModFlags->getOperand(I);
ConstantInt *SrcBehavior = cast<ConstantInt>(SrcOp->getOperand(0));
MDString *ID = cast<MDString>(SrcOp->getOperand(1));
MDNode *DstOp = Flags.lookup(ID);
unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
// If this is a requirement, add it and continue.
if (SrcBehaviorValue == Module::Require) {
// If the destination module does not already have this requirement, add
// it.
if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
DstModFlags->addOperand(SrcOp);
}
continue;
}
// If there is no existing flag with this ID, just add it.
if (!DstOp) {
Flags[ID] = SrcOp;
DstModFlags->addOperand(SrcOp);
continue;
}
// Otherwise, perform a merge.
ConstantInt *DstBehavior = cast<ConstantInt>(DstOp->getOperand(0));
unsigned DstBehaviorValue = DstBehavior->getZExtValue();
// If either flag has override behavior, handle it first.
if (DstBehaviorValue == Module::Override) {
// Diagnose inconsistent flags which both have override behavior.
if (SrcBehaviorValue == Module::Override &&
SrcOp->getOperand(2) != DstOp->getOperand(2)) {
HasErr |= emitError("linking module flags '" + ID->getString() +
"': IDs have conflicting override values");
}
continue;
} else if (SrcBehaviorValue == Module::Override) {
// Update the destination flag to that of the source.
DstOp->replaceOperandWith(0, SrcBehavior);
DstOp->replaceOperandWith(2, SrcOp->getOperand(2));
continue;
}
// Diagnose inconsistent merge behavior types.
if (SrcBehaviorValue != DstBehaviorValue) {
HasErr |= emitError("linking module flags '" + ID->getString() +
"': IDs have conflicting behaviors");
continue;
}
// Perform the merge for standard behavior types.
switch (SrcBehaviorValue) {
case Module::Require:
case Module::Override: llvm_unreachable("not possible");
case Module::Error: {
// Emit an error if the values differ.
if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
HasErr |= emitError("linking module flags '" + ID->getString() +
"': IDs have conflicting values");
}
continue;
}
case Module::Warning: {
// Emit a warning if the values differ.
if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
if (!SuppressWarnings) {
errs() << "WARNING: linking module flags '" << ID->getString()
<< "': IDs have conflicting values";
}
}
continue;
}
case Module::Append: {
MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
unsigned NumOps = DstValue->getNumOperands() + SrcValue->getNumOperands();
Value **VP, **Values = VP = new Value*[NumOps];
for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i, ++VP)
*VP = DstValue->getOperand(i);
for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i, ++VP)
*VP = SrcValue->getOperand(i);
DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
ArrayRef<Value*>(Values,
NumOps)));
delete[] Values;
break;
}
case Module::AppendUnique: {
SmallSetVector<Value*, 16> Elts;
MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i)
Elts.insert(DstValue->getOperand(i));
for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i)
Elts.insert(SrcValue->getOperand(i));
DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
ArrayRef<Value*>(Elts.begin(),
Elts.end())));
break;
}
}
}
// Check all of the requirements.
for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
MDNode *Requirement = Requirements[I];
MDString *Flag = cast<MDString>(Requirement->getOperand(0));
Value *ReqValue = Requirement->getOperand(1);
MDNode *Op = Flags[Flag];
if (!Op || Op->getOperand(2) != ReqValue) {
HasErr |= emitError("linking module flags '" + Flag->getString() +
"': does not have the required value");
continue;
}
}
return HasErr;
}
bool ModuleLinker::run() {
assert(DstM && "Null destination module");
assert(SrcM && "Null source module");
// Inherit the target data from the source module if the destination module
// doesn't have one already.
if (!DstM->getDataLayout() && SrcM->getDataLayout())
DstM->setDataLayout(SrcM->getDataLayout());
// Copy the target triple from the source to dest if the dest's is empty.
if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
DstM->setTargetTriple(SrcM->getTargetTriple());
if (SrcM->getDataLayout() && DstM->getDataLayout() &&
*SrcM->getDataLayout() != *DstM->getDataLayout()) {
if (!SuppressWarnings) {
errs() << "WARNING: Linking two modules of different data layouts: '"
<< SrcM->getModuleIdentifier() << "' is '"
<< SrcM->getDataLayoutStr() << "' whereas '"
<< DstM->getModuleIdentifier() << "' is '"
<< DstM->getDataLayoutStr() << "'\n";
}
}
if (!SrcM->getTargetTriple().empty() &&
DstM->getTargetTriple() != SrcM->getTargetTriple()) {
if (!SuppressWarnings) {
errs() << "WARNING: Linking two modules of different target triples: "
<< SrcM->getModuleIdentifier() << "' is '"
<< SrcM->getTargetTriple() << "' whereas '"
<< DstM->getModuleIdentifier() << "' is '"
<< DstM->getTargetTriple() << "'\n";
}
}
// Append the module inline asm string.
if (!SrcM->getModuleInlineAsm().empty()) {
if (DstM->getModuleInlineAsm().empty())
DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
else
DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
SrcM->getModuleInlineAsm());
}
// Loop over all of the linked values to compute type mappings.
computeTypeMapping();
ComdatsChosen.clear();
for (const StringMapEntry<llvm::Comdat> &SMEC : SrcM->getComdatSymbolTable()) {
const Comdat &C = SMEC.getValue();
if (ComdatsChosen.count(&C))
continue;
Comdat::SelectionKind SK;
bool LinkFromSrc;
if (getComdatResult(&C, SK, LinkFromSrc))
return true;
ComdatsChosen[&C] = std::make_pair(SK, LinkFromSrc);
}
// Upgrade mismatched global arrays.
upgradeMismatchedGlobals();
// Insert all of the globals in src into the DstM module... without linking
// initializers (which could refer to functions not yet mapped over).
for (Module::global_iterator I = SrcM->global_begin(),
E = SrcM->global_end(); I != E; ++I)
if (linkGlobalProto(I))
return true;
// Link the functions together between the two modules, without doing function
// bodies... this just adds external function prototypes to the DstM
// function... We do this so that when we begin processing function bodies,
// all of the global values that may be referenced are available in our
// ValueMap.
for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I)
if (linkFunctionProto(I))
return true;
// If there were any aliases, link them now.
for (Module::alias_iterator I = SrcM->alias_begin(),
E = SrcM->alias_end(); I != E; ++I)
if (linkAliasProto(I))
return true;
for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i)
linkAppendingVarInit(AppendingVars[i]);
// Link in the function bodies that are defined in the source module into
// DstM.
for (Module::iterator SF = SrcM->begin(), E = SrcM->end(); SF != E; ++SF) {
// Skip if not linking from source.
if (DoNotLinkFromSource.count(SF)) continue;
Function *DF = cast<Function>(ValueMap[SF]);
if (SF->hasPrefixData()) {
// Link in the prefix data.
DF->setPrefixData(MapValue(
SF->getPrefixData(), ValueMap, RF_None, &TypeMap, &ValMaterializer));
}
// Skip if no body (function is external) or materialize.
if (SF->isDeclaration()) {
if (!SF->isMaterializable())
continue;
if (SF->Materialize(&ErrorMsg))
return true;
}
linkFunctionBody(DF, SF);
SF->Dematerialize();
}
// Resolve all uses of aliases with aliasees.
linkAliasBodies();
// Remap all of the named MDNodes in Src into the DstM module. We do this
// after linking GlobalValues so that MDNodes that reference GlobalValues
// are properly remapped.
linkNamedMDNodes();
// Merge the module flags into the DstM module.
if (linkModuleFlagsMetadata())
return true;
// Update the initializers in the DstM module now that all globals that may
// be referenced are in DstM.
linkGlobalInits();
// Process vector of lazily linked in functions.
bool LinkedInAnyFunctions;
do {
LinkedInAnyFunctions = false;
for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(),
E = LazilyLinkFunctions.end(); I != E; ++I) {
Function *SF = *I;
if (!SF)
continue;
Function *DF = cast<Function>(ValueMap[SF]);
if (SF->hasPrefixData()) {
// Link in the prefix data.
DF->setPrefixData(MapValue(SF->getPrefixData(),
ValueMap,
RF_None,
&TypeMap,
&ValMaterializer));
}
// Materialize if necessary.
if (SF->isDeclaration()) {
if (!SF->isMaterializable())
continue;
if (SF->Materialize(&ErrorMsg))
return true;
}
// Erase from vector *before* the function body is linked - linkFunctionBody could
// invalidate I.
LazilyLinkFunctions.erase(I);
// Link in function body.
linkFunctionBody(DF, SF);
SF->Dematerialize();
// Set flag to indicate we may have more functions to lazily link in
// since we linked in a function.
LinkedInAnyFunctions = true;
break;
}
} while (LinkedInAnyFunctions);
// Now that all of the types from the source are used, resolve any structs
// copied over to the dest that didn't exist there.
TypeMap.linkDefinedTypeBodies();
return false;
}
Linker::Linker(Module *M, bool SuppressWarnings)
: Composite(M), SuppressWarnings(SuppressWarnings) {
TypeFinder StructTypes;
StructTypes.run(*M, true);
IdentifiedStructTypes.insert(StructTypes.begin(), StructTypes.end());
}
Linker::~Linker() {
}
void Linker::deleteModule() {
delete Composite;
Composite = nullptr;
}
bool Linker::linkInModule(Module *Src, unsigned Mode, std::string *ErrorMsg) {
ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src, Mode,
SuppressWarnings);
if (TheLinker.run()) {
if (ErrorMsg)
*ErrorMsg = TheLinker.ErrorMsg;
return true;
}
return false;
}
//===----------------------------------------------------------------------===//
// LinkModules entrypoint.
//===----------------------------------------------------------------------===//
/// LinkModules - This function links two modules together, with the resulting
/// Dest module modified to be the composite of the two input modules. If an
/// error occurs, true is returned and ErrorMsg (if not null) is set to indicate
/// the problem. Upon failure, the Dest module could be in a modified state,
/// and shouldn't be relied on to be consistent.
bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Mode,
std::string *ErrorMsg) {
Linker L(Dest);
return L.linkInModule(Src, Mode, ErrorMsg);
}
//===----------------------------------------------------------------------===//
// C API.
//===----------------------------------------------------------------------===//
LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
LLVMLinkerMode Mode, char **OutMessages) {
std::string Messages;
LLVMBool Result = Linker::LinkModules(unwrap(Dest), unwrap(Src),
Mode, OutMessages? &Messages : nullptr);
if (OutMessages)
*OutMessages = strdup(Messages.c_str());
return Result;
}
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