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700867bb69
llvm/lib/Linker/LinkModules.cpp
John Criswell 700867bb69 Checking in Chris's suggestions: 
Added assert() to ensure symbol table is well formed.
Added code to remember the value that was found; resolving types can change
the symbol table and invalidate the value of the iterator.
Added comments to the ResolveTypes() function (mainly for my own benefit).
Please feel free to correct the comments if they are not accurate.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@9693 91177308-0d34-0410-b5e6-96231b3b80d8
2003-11-04 15:22:26 +00:00

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//===- Linker.cpp - Module Linker Implementation --------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and 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/Transforms/Utils/Linker.h"
#include "llvm/Module.h"
#include "llvm/SymbolTable.h"
#include "llvm/DerivedTypes.h"
#include "llvm/iOther.h"
#include "llvm/Constants.h"
// 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;
}
//
// 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,
SymbolTable *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,
SymbolTable *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->getPrimitiveID() != SrcTyT->getPrimitiveID()) return true;
// Otherwise, resolve the used type used by this derived type...
switch (DestTyT->getPrimitiveID()) {
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,
SymbolTable *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) {
SymbolTable *DestST = &Dest->getSymbolTable();
const SymbolTable *SrcST = &Src->getSymbolTable();
// Look for a type plane for Type's...
SymbolTable::const_iterator PI = SrcST->find(Type::TypeTy);
if (PI == SrcST->end()) 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;
const SymbolTable::VarMap &VM = PI->second;
for (SymbolTable::type_const_iterator I = VM.begin(), E = VM.end();
I != E; ++I) {
const std::string &Name = I->first;
Type *RHS = cast<Type>(I->second);
// Check to see if this type name is already in the dest module...
Type *Entry = cast_or_null<Type>(DestST->lookup(Type::TypeTy, 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 = cast<Type>(VM.find(Name)->second);
Type *T2 = cast<Type>(DestST->lookup(Type::TypeTy, 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(cast<Type>(VM.find(Name)->second));
PATypeHolder T2(cast<Type>(DestST->lookup(Type::TypeTy, 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.
// Report the warning and delete one of the names.
if (DelayedTypesToResolve.size() == OldSize) {
const std::string &Name = DelayedTypesToResolve.back();
const Type *T1 = cast<Type>(VM.find(Name)->second);
const Type *T2 = cast<Type>(DestST->lookup(Type::TypeTy, Name));
std::cerr << "WARNING: Type conflict between types named '" << Name
<< "'.\n Src='" << *T1 << "'.\n Dest='" << *T2 << "'\n";
// 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) {
std::cerr << " Fr: " << (void*)I->first << " ";
I->first->dump();
std::cerr << " To: " << (void*)I->second << " ";
I->second->dump();
std::cerr << "\n";
}
}
// RemapOperand - Use LocalMap and GlobalMap to convert references from one
// module to another. This is somewhat sophisticated in that it can
// automatically handle constant references correctly as well...
//
static Value *RemapOperand(const Value *In,
std::map<const Value*, Value*> &LocalMap,
std::map<const Value*, Value*> *GlobalMap) {
std::map<const Value*,Value*>::const_iterator I = LocalMap.find(In);
if (I != LocalMap.end()) return I->second;
if (GlobalMap) {
I = GlobalMap->find(In);
if (I != GlobalMap->end()) return I->second;
}
// Check to see if it's a constant that we are interesting in transforming...
if (const Constant *CPV = dyn_cast<Constant>(In)) {
if (!isa<DerivedType>(CPV->getType()) && !isa<ConstantExpr>(CPV))
return const_cast<Constant*>(CPV); // Simple constants stay identical...
Constant *Result = 0;
if (const ConstantArray *CPA = dyn_cast<ConstantArray>(CPV)) {
const std::vector<Use> &Ops = CPA->getValues();
std::vector<Constant*> Operands(Ops.size());
for (unsigned i = 0, e = Ops.size(); i != e; ++i)
Operands[i] =
cast<Constant>(RemapOperand(Ops[i], LocalMap, GlobalMap));
Result = ConstantArray::get(cast<ArrayType>(CPA->getType()), Operands);
} else if (const ConstantStruct *CPS = dyn_cast<ConstantStruct>(CPV)) {
const std::vector<Use> &Ops = CPS->getValues();
std::vector<Constant*> Operands(Ops.size());
for (unsigned i = 0; i < Ops.size(); ++i)
Operands[i] =
cast<Constant>(RemapOperand(Ops[i], LocalMap, GlobalMap));
Result = ConstantStruct::get(cast<StructType>(CPS->getType()), Operands);
} else if (isa<ConstantPointerNull>(CPV)) {
Result = const_cast<Constant*>(CPV);
} else if (const ConstantPointerRef *CPR =
dyn_cast<ConstantPointerRef>(CPV)) {
Value *V = RemapOperand(CPR->getValue(), LocalMap, GlobalMap);
Result = ConstantPointerRef::get(cast<GlobalValue>(V));
} else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CPV)) {
if (CE->getOpcode() == Instruction::GetElementPtr) {
Value *Ptr = RemapOperand(CE->getOperand(0), LocalMap, GlobalMap);
std::vector<Constant*> Indices;
Indices.reserve(CE->getNumOperands()-1);
for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
Indices.push_back(cast<Constant>(RemapOperand(CE->getOperand(i),
LocalMap, GlobalMap)));
Result = ConstantExpr::getGetElementPtr(cast<Constant>(Ptr), Indices);
} else if (CE->getNumOperands() == 1) {
// Cast instruction
assert(CE->getOpcode() == Instruction::Cast);
Value *V = RemapOperand(CE->getOperand(0), LocalMap, GlobalMap);
Result = ConstantExpr::getCast(cast<Constant>(V), CE->getType());
} else if (CE->getNumOperands() == 2) {
// Binary operator...
Value *V1 = RemapOperand(CE->getOperand(0), LocalMap, GlobalMap);
Value *V2 = RemapOperand(CE->getOperand(1), LocalMap, GlobalMap);
Result = ConstantExpr::get(CE->getOpcode(), cast<Constant>(V1),
cast<Constant>(V2));
} else {
assert(0 && "Unknown constant expr type!");
}
} else {
assert(0 && "Unknown type of derived type constant value!");
}
// Cache the mapping in our local map structure...
if (GlobalMap)
GlobalMap->insert(std::make_pair(In, Result));
else
LocalMap.insert(std::make_pair(In, Result));
return Result;
}
std::cerr << "XXX LocalMap: \n";
PrintMap(LocalMap);
if (GlobalMap) {
std::cerr << "XXX GlobalMap: \n";
PrintMap(*GlobalMap);
}
std::cerr << "Couldn't remap value: " << (void*)In << " " << *In << "\n";
assert(0 && "Couldn't remap value!");
return 0;
}
/// FindGlobalNamed - Look in the specified symbol table for a global with the
/// specified name and type. If an exactly matching global does not exist, see
/// if there is a global which is "type compatible" with the specified
/// name/type. This allows us to resolve things like '%x = global int*' with
/// '%x = global opaque*'.
///
static GlobalValue *FindGlobalNamed(const std::string &Name, const Type *Ty,
SymbolTable *ST) {
// See if an exact match exists in the symbol table...
if (Value *V = ST->lookup(Ty, Name)) return cast<GlobalValue>(V);
// It doesn't exist exactly, scan through all of the type planes in the symbol
// table, checking each of them for a type-compatible version.
//
for (SymbolTable::iterator I = ST->begin(), E = ST->end(); I != E; ++I)
if (I->first != Type::TypeTy) {
SymbolTable::VarMap &VM = I->second;
// Does this type plane contain an entry with the specified name?
SymbolTable::type_iterator TI = VM.find(Name);
if (TI != VM.end()) {
//
// Ensure that this type if placed correctly into the symbol table.
//
assert(TI->second->getType() == I->first && "Type conflict!");
//
// Save a reference to the new type. Resolving the type can modify the
// symbol table, invalidating the TI variable.
//
Value *ValPtr = TI->second;
//
// Determine whether we can fold the two types together, resolving them.
// If so, we can use this value.
//
if (!RecursiveResolveTypes(Ty, I->first, ST, ""))
return cast<GlobalValue>(ValPtr);
}
}
return 0; // Otherwise, nothing could be found.
}
// 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) {
// We will need a module level symbol table if the src module has a module
// level symbol table...
SymbolTable *ST = (SymbolTable*)&Dest->getSymbolTable();
// Loop over all of the globals in the src module, mapping them over as we go
//
for (Module::const_giterator I = Src->gbegin(), E = Src->gend(); I != E; ++I){
const GlobalVariable *SGV = I;
GlobalVariable *DGV = 0;
if (SGV->hasName()) {
// A same named thing is a global variable, because the only two things
// that may be in a module level symbol table are Global Vars and
// Functions, and they both have distinct, nonoverlapping, possible types.
//
DGV = cast_or_null<GlobalVariable>(FindGlobalNamed(SGV->getName(),
SGV->getType(), ST));
}
assert(SGV->hasInitializer() || SGV->hasExternalLinkage() &&
"Global must either be external or have an initializer!");
bool SGExtern = SGV->isExternal();
bool DGExtern = DGV ? DGV->isExternal() : false;
if (!DGV || DGV->hasInternalLinkage() || SGV->hasInternalLinkage()) {
// 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);
// 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()){
assert(DGV && DGV->getName() == SGV->getName() &&
DGV->hasInternalLinkage());
DGV->setName("");
NewDGV->setName(SGV->getName()); // Force the name back
DGV->setName(SGV->getName()); // This will cause a renaming
assert(NewDGV->getName() == SGV->getName() &&
DGV->getName() != SGV->getName());
}
// Make sure to remember this mapping...
ValueMap.insert(std::make_pair(SGV, NewDGV));
if (SGV->hasAppendingLinkage())
// Keep track that this is an appending variable...
AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV));
} else if (SGV->isExternal()) {
// If SGV is external or if both SGV & DGV are external.. Just link the
// external globals, we aren't adding anything.
ValueMap.insert(std::make_pair(SGV, DGV));
} else if (DGV->isExternal()) { // If DGV is external but SGV is not...
ValueMap.insert(std::make_pair(SGV, DGV));
DGV->setLinkage(SGV->getLinkage()); // Inherit linkage!
} else if (SGV->hasWeakLinkage() || SGV->hasLinkOnceLinkage()) {
// At this point we know that DGV has LinkOnce, Appending, Weak, or
// External linkage. If DGV is Appending, this is an error.
if (DGV->hasAppendingLinkage())
return Error(Err, "Linking globals named '" + SGV->getName() +
" ' with 'weak' and 'appending' linkage is not allowed!");
if (SGV->isConstant() != DGV->isConstant())
return Error(Err, "Global Variable Collision on '" +
SGV->getType()->getDescription() + " %" + SGV->getName() +
"' - Global variables differ in const'ness");
// Otherwise, just perform the link.
ValueMap.insert(std::make_pair(SGV, DGV));
// Linkonce+Weak = Weak
if (DGV->hasLinkOnceLinkage() && SGV->hasWeakLinkage())
DGV->setLinkage(SGV->getLinkage());
} else if (DGV->hasWeakLinkage() || DGV->hasLinkOnceLinkage()) {
// At this point we know that SGV has LinkOnce, Appending, or External
// linkage. If SGV is Appending, this is an error.
if (SGV->hasAppendingLinkage())
return Error(Err, "Linking globals named '" + SGV->getName() +
" ' with 'weak' and 'appending' linkage is not allowed!");
if (SGV->isConstant() != DGV->isConstant())
return Error(Err, "Global Variable Collision on '" +
SGV->getType()->getDescription() + " %" + SGV->getName() +
"' - Global variables differ in const'ness");
if (!SGV->hasLinkOnceLinkage())
DGV->setLinkage(SGV->getLinkage()); // Inherit linkage!
ValueMap.insert(std::make_pair(SGV, DGV));
} else if (SGV->getLinkage() != DGV->getLinkage()) {
return Error(Err, "Global variables named '" + SGV->getName() +
"' have different linkage specifiers!");
} else if (SGV->hasExternalLinkage()) {
// Allow linking two exactly identical external global variables...
if (SGV->isConstant() != DGV->isConstant())
return Error(Err, "Global Variable Collision on '" +
SGV->getType()->getDescription() + " %" + SGV->getName() +
"' - Global variables differ in const'ness");
if (SGV->getInitializer() != DGV->getInitializer())
return Error(Err, "Global Variable Collision on '" +
SGV->getType()->getDescription() + " %" + SGV->getName() +
"' - External linkage globals have different initializers");
ValueMap.insert(std::make_pair(SGV, DGV));
} else if (SGV->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);
// Make sure to remember this mapping...
ValueMap.insert(std::make_pair(SGV, NewDGV));
// Keep track that this is an appending variable...
AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV));
} else {
assert(0 && "Unknown linkage!");
}
}
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_giterator I = Src->gbegin(), E = Src->gend(); 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, 0));
GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[SGV]);
if (DGV->hasInitializer()) {
assert(SGV->getLinkage() == DGV->getLinkage());
if (SGV->hasExternalLinkage()) {
if (DGV->getInitializer() != SInit)
return Error(Err, "Global Variable Collision on '" +
SGV->getType()->getDescription() +"':%"+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 (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) {
SymbolTable *ST = (SymbolTable*)&Dest->getSymbolTable();
// Loop over all of the functions in the src module, mapping them over as we
// go
//
for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) {
const Function *SF = I; // SrcFunction
Function *DF = 0;
if (SF->hasName())
// The same named thing is a Function, because the only two things
// that may be in a module level symbol table are Global Vars and
// Functions, and they both have distinct, nonoverlapping, possible types.
//
DF = cast_or_null<Function>(FindGlobalNamed(SF->getName(), SF->getType(),
ST));
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);
// 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()) {
assert(DF && DF->getName() == SF->getName() &&DF->hasInternalLinkage());
DF->setName("");
NewDF->setName(SF->getName()); // Force the name back
DF->setName(SF->getName()); // This will cause a renaming
assert(NewDF->getName() == SF->getName() &&
DF->getName() != SF->getName());
}
// ... and remember this mapping...
ValueMap.insert(std::make_pair(SF, NewDF));
} else if (SF->isExternal()) {
// If SF is external or if both SF & DF are external.. Just link the
// external functions, we aren't adding anything.
ValueMap.insert(std::make_pair(SF, DF));
} else if (DF->isExternal()) { // 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());
} else if (SF->hasWeakLinkage() || SF->hasLinkOnceLinkage()) {
// At this point we know that DF has LinkOnce, Weak, or External linkage.
ValueMap.insert(std::make_pair(SF, DF));
// Linkonce+Weak = Weak
if (DF->hasLinkOnceLinkage() && SF->hasWeakLinkage())
DF->setLinkage(SF->getLinkage());
} else if (DF->hasWeakLinkage() || DF->hasLinkOnceLinkage()) {
// At this point we know that SF has LinkOnce or External linkage.
ValueMap.insert(std::make_pair(SF, DF));
if (!SF->hasLinkOnceLinkage()) // Don't inherit linkonce 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 in both modules!!
return Error(Err, "Function '" +
SF->getFunctionType()->getDescription() + "':\"" +
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, const Function *Src,
std::map<const Value*, Value*> &GlobalMap,
std::string *Err) {
assert(Src && Dest && Dest->isExternal() && !Src->isExternal());
std::map<const Value*, Value*> LocalMap; // Map for function local values
// Go through and convert function arguments over...
Function::aiterator DI = Dest->abegin();
for (Function::const_aiterator I = Src->abegin(), E = Src->aend();
I != E; ++I, ++DI) {
DI->setName(I->getName()); // Copy the name information over...
// Add a mapping to our local map
LocalMap.insert(std::make_pair(I, DI));
}
// Loop over all of the basic blocks, copying the instructions over...
//
for (Function::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) {
// Create new basic block and add to mapping and the Dest function...
BasicBlock *DBB = new BasicBlock(I->getName(), Dest);
LocalMap.insert(std::make_pair(I, DBB));
// Loop over all of the instructions in the src basic block, copying them
// over. Note that this is broken in a strict sense because the cloned
// instructions will still be referencing values in the Src module, not
// the remapped values. In our case, however, we will not get caught and
// so we can delay patching the values up until later...
//
for (BasicBlock::const_iterator II = I->begin(), IE = I->end();
II != IE; ++II) {
Instruction *DI = II->clone();
DI->setName(II->getName());
DBB->getInstList().push_back(DI);
LocalMap.insert(std::make_pair(II, DI));
}
}
// 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)
*OI = RemapOperand(*OI, LocalMap, &GlobalMap);
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, 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 as we
// go
//
for (Module::const_iterator SF = Src->begin(), E = Src->end(); SF != E; ++SF){
if (!SF->isExternal()) { // No body if function is external
Function *DF = cast<Function>(ValueMap[SF]); // Destination function
// DF not external SF external?
if (DF->isExternal()) {
// 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!");
unsigned NewSize = T1->getNumElements() + T2->getNumElements();
ArrayType *NewType = ArrayType::get(T1->getElementType(), NewSize);
// Create the new global variable...
GlobalVariable *NG =
new GlobalVariable(NewType, G1->isConstant(), G1->getLinkage(),
/*init*/0, First->first, M);
// Merge the initializer...
Inits.reserve(NewSize);
ConstantArray *I = cast<ConstantArray>(G1->getInitializer());
for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i)
Inits.push_back(cast<Constant>(I->getValues()[i]));
I = cast<ConstantArray>(G2->getInitializer());
for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i)
Inits.push_back(cast<Constant>(I->getValues()[i]));
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!
ConstantPointerRef *NGCP = ConstantPointerRef::get(NG);
G1->replaceAllUsesWith(ConstantExpr::getCast(NGCP, G1->getType()));
G2->replaceAllUsesWith(ConstantExpr::getCast(NGCP, 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;
}
// 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 LinkModules(Module *Dest, const Module *Src, std::string *ErrorMsg) {
if (Dest->getEndianness() == Module::AnyEndianness)
Dest->setEndianness(Src->getEndianness());
if (Dest->getPointerSize() == Module::AnyPointerSize)
Dest->setPointerSize(Src->getPointerSize());
if (Src->getEndianness() != Module::AnyEndianness &&
Dest->getEndianness() != Src->getEndianness())
std::cerr << "WARNING: Linking two modules of different endianness!\n";
if (Src->getPointerSize() != Module::AnyPointerSize &&
Dest->getPointerSize() != Src->getPointerSize())
std::cerr << "WARNING: Linking two modules of different pointer size!\n";
// 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;
// Add all of the appending globals already in the Dest module to
// AppendingVars.
for (Module::giterator I = Dest->gbegin(), E = Dest->gend(); I != E; ++I)
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;
// 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;
return false;
}
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