1 //===- lib/Linker/LinkModules.cpp - Module Linker Implementation ----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the LLVM module linker.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Linker.h"
15 #include "llvm/Constants.h"
16 #include "llvm/DerivedTypes.h"
17 #include "llvm/Instructions.h"
18 #include "llvm/Module.h"
19 #include "llvm/ADT/SmallPtrSet.h"
20 #include "llvm/Support/raw_ostream.h"
21 #include "llvm/Support/Path.h"
22 #include "llvm/Transforms/Utils/Cloning.h"
23 #include "llvm/Transforms/Utils/ValueMapper.h"
26 //===----------------------------------------------------------------------===//
27 // TypeMap implementation.
28 //===----------------------------------------------------------------------===//
31 class TypeMapTy : public ValueMapTypeRemapper {
32 /// MappedTypes - This is a mapping from a source type to a destination type
34 DenseMap<Type*, Type*> MappedTypes;
36 /// SpeculativeTypes - When checking to see if two subgraphs are isomorphic,
37 /// we speculatively add types to MappedTypes, but keep track of them here in
38 /// case we need to roll back.
39 SmallVector<Type*, 16> SpeculativeTypes;
41 /// SrcDefinitionsToResolve - This is a list of non-opaque structs in the
42 /// source module that are mapped to an opaque struct in the destination
44 SmallVector<StructType*, 16> SrcDefinitionsToResolve;
46 /// DstResolvedOpaqueTypes - This is the set of opaque types in the
47 /// destination modules who are getting a body from the source module.
48 SmallPtrSet<StructType*, 16> DstResolvedOpaqueTypes;
51 /// addTypeMapping - Indicate that the specified type in the destination
52 /// module is conceptually equivalent to the specified type in the source
54 void addTypeMapping(Type *DstTy, Type *SrcTy);
56 /// linkDefinedTypeBodies - Produce a body for an opaque type in the dest
57 /// module from a type definition in the source module.
58 void linkDefinedTypeBodies();
60 /// get - Return the mapped type to use for the specified input type from the
62 Type *get(Type *SrcTy);
64 FunctionType *get(FunctionType *T) {return cast<FunctionType>(get((Type*)T));}
67 Type *getImpl(Type *T);
68 /// remapType - Implement the ValueMapTypeRemapper interface.
69 Type *remapType(Type *SrcTy) {
73 bool areTypesIsomorphic(Type *DstTy, Type *SrcTy);
77 void TypeMapTy::addTypeMapping(Type *DstTy, Type *SrcTy) {
78 Type *&Entry = MappedTypes[SrcTy];
86 // Check to see if these types are recursively isomorphic and establish a
87 // mapping between them if so.
88 if (!areTypesIsomorphic(DstTy, SrcTy)) {
89 // Oops, they aren't isomorphic. Just discard this request by rolling out
90 // any speculative mappings we've established.
91 for (unsigned i = 0, e = SpeculativeTypes.size(); i != e; ++i)
92 MappedTypes.erase(SpeculativeTypes[i]);
94 SpeculativeTypes.clear();
97 /// areTypesIsomorphic - Recursively walk this pair of types, returning true
98 /// if they are isomorphic, false if they are not.
99 bool TypeMapTy::areTypesIsomorphic(Type *DstTy, Type *SrcTy) {
100 // Two types with differing kinds are clearly not isomorphic.
101 if (DstTy->getTypeID() != SrcTy->getTypeID()) return false;
103 // If we have an entry in the MappedTypes table, then we have our answer.
104 Type *&Entry = MappedTypes[SrcTy];
106 return Entry == DstTy;
108 // Two identical types are clearly isomorphic. Remember this
109 // non-speculatively.
110 if (DstTy == SrcTy) {
115 // Okay, we have two types with identical kinds that we haven't seen before.
117 // If this is an opaque struct type, special case it.
118 if (StructType *SSTy = dyn_cast<StructType>(SrcTy)) {
119 // Mapping an opaque type to any struct, just keep the dest struct.
120 if (SSTy->isOpaque()) {
122 SpeculativeTypes.push_back(SrcTy);
126 // Mapping a non-opaque source type to an opaque dest. If this is the first
127 // type that we're mapping onto this destination type then we succeed. Keep
128 // the dest, but fill it in later. This doesn't need to be speculative. If
129 // this is the second (different) type that we're trying to map onto the
130 // same opaque type then we fail.
131 if (cast<StructType>(DstTy)->isOpaque()) {
132 // We can only map one source type onto the opaque destination type.
133 if (!DstResolvedOpaqueTypes.insert(cast<StructType>(DstTy)))
135 SrcDefinitionsToResolve.push_back(SSTy);
141 // If the number of subtypes disagree between the two types, then we fail.
142 if (SrcTy->getNumContainedTypes() != DstTy->getNumContainedTypes())
145 // Fail if any of the extra properties (e.g. array size) of the type disagree.
146 if (isa<IntegerType>(DstTy))
147 return false; // bitwidth disagrees.
148 if (PointerType *PT = dyn_cast<PointerType>(DstTy)) {
149 if (PT->getAddressSpace() != cast<PointerType>(SrcTy)->getAddressSpace())
151 } else if (FunctionType *FT = dyn_cast<FunctionType>(DstTy)) {
152 if (FT->isVarArg() != cast<FunctionType>(SrcTy)->isVarArg())
154 } else if (StructType *DSTy = dyn_cast<StructType>(DstTy)) {
155 StructType *SSTy = cast<StructType>(SrcTy);
156 if (DSTy->isLiteral() != SSTy->isLiteral() ||
157 DSTy->isPacked() != SSTy->isPacked())
159 } else if (ArrayType *DATy = dyn_cast<ArrayType>(DstTy)) {
160 if (DATy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements())
162 } else if (VectorType *DVTy = dyn_cast<VectorType>(DstTy)) {
163 if (DVTy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements())
167 // Otherwise, we speculate that these two types will line up and recursively
168 // check the subelements.
170 SpeculativeTypes.push_back(SrcTy);
172 for (unsigned i = 0, e = SrcTy->getNumContainedTypes(); i != e; ++i)
173 if (!areTypesIsomorphic(DstTy->getContainedType(i),
174 SrcTy->getContainedType(i)))
177 // If everything seems to have lined up, then everything is great.
181 /// linkDefinedTypeBodies - Produce a body for an opaque type in the dest
182 /// module from a type definition in the source module.
183 void TypeMapTy::linkDefinedTypeBodies() {
184 SmallVector<Type*, 16> Elements;
185 SmallString<16> TmpName;
187 // Note that processing entries in this loop (calling 'get') can add new
188 // entries to the SrcDefinitionsToResolve vector.
189 while (!SrcDefinitionsToResolve.empty()) {
190 StructType *SrcSTy = SrcDefinitionsToResolve.pop_back_val();
191 StructType *DstSTy = cast<StructType>(MappedTypes[SrcSTy]);
193 // TypeMap is a many-to-one mapping, if there were multiple types that
194 // provide a body for DstSTy then previous iterations of this loop may have
195 // already handled it. Just ignore this case.
196 if (!DstSTy->isOpaque()) continue;
197 assert(!SrcSTy->isOpaque() && "Not resolving a definition?");
199 // Map the body of the source type over to a new body for the dest type.
200 Elements.resize(SrcSTy->getNumElements());
201 for (unsigned i = 0, e = Elements.size(); i != e; ++i)
202 Elements[i] = getImpl(SrcSTy->getElementType(i));
204 DstSTy->setBody(Elements, SrcSTy->isPacked());
206 // If DstSTy has no name or has a longer name than STy, then viciously steal
208 if (!SrcSTy->hasName()) continue;
209 StringRef SrcName = SrcSTy->getName();
211 if (!DstSTy->hasName() || DstSTy->getName().size() > SrcName.size()) {
212 TmpName.insert(TmpName.end(), SrcName.begin(), SrcName.end());
214 DstSTy->setName(TmpName.str());
219 DstResolvedOpaqueTypes.clear();
223 /// get - Return the mapped type to use for the specified input type from the
225 Type *TypeMapTy::get(Type *Ty) {
226 Type *Result = getImpl(Ty);
228 // If this caused a reference to any struct type, resolve it before returning.
229 if (!SrcDefinitionsToResolve.empty())
230 linkDefinedTypeBodies();
234 /// getImpl - This is the recursive version of get().
235 Type *TypeMapTy::getImpl(Type *Ty) {
236 // If we already have an entry for this type, return it.
237 Type **Entry = &MappedTypes[Ty];
238 if (*Entry) return *Entry;
240 // If this is not a named struct type, then just map all of the elements and
241 // then rebuild the type from inside out.
242 if (!isa<StructType>(Ty) || cast<StructType>(Ty)->isLiteral()) {
243 // If there are no element types to map, then the type is itself. This is
244 // true for the anonymous {} struct, things like 'float', integers, etc.
245 if (Ty->getNumContainedTypes() == 0)
248 // Remap all of the elements, keeping track of whether any of them change.
249 bool AnyChange = false;
250 SmallVector<Type*, 4> ElementTypes;
251 ElementTypes.resize(Ty->getNumContainedTypes());
252 for (unsigned i = 0, e = Ty->getNumContainedTypes(); i != e; ++i) {
253 ElementTypes[i] = getImpl(Ty->getContainedType(i));
254 AnyChange |= ElementTypes[i] != Ty->getContainedType(i);
257 // If we found our type while recursively processing stuff, just use it.
258 Entry = &MappedTypes[Ty];
259 if (*Entry) return *Entry;
261 // If all of the element types mapped directly over, then the type is usable
266 // Otherwise, rebuild a modified type.
267 switch (Ty->getTypeID()) {
268 default: assert(0 && "unknown derived type to remap");
269 case Type::ArrayTyID:
270 return *Entry = ArrayType::get(ElementTypes[0],
271 cast<ArrayType>(Ty)->getNumElements());
272 case Type::VectorTyID:
273 return *Entry = VectorType::get(ElementTypes[0],
274 cast<VectorType>(Ty)->getNumElements());
275 case Type::PointerTyID:
276 return *Entry = PointerType::get(ElementTypes[0],
277 cast<PointerType>(Ty)->getAddressSpace());
278 case Type::FunctionTyID:
279 return *Entry = FunctionType::get(ElementTypes[0],
280 makeArrayRef(ElementTypes).slice(1),
281 cast<FunctionType>(Ty)->isVarArg());
282 case Type::StructTyID:
283 // Note that this is only reached for anonymous structs.
284 return *Entry = StructType::get(Ty->getContext(), ElementTypes,
285 cast<StructType>(Ty)->isPacked());
289 // Otherwise, this is an unmapped named struct. If the struct can be directly
290 // mapped over, just use it as-is. This happens in a case when the linked-in
291 // module has something like:
292 // %T = type {%T*, i32}
293 // @GV = global %T* null
294 // where T does not exist at all in the destination module.
296 // The other case we watch for is when the type is not in the destination
297 // module, but that it has to be rebuilt because it refers to something that
298 // is already mapped. For example, if the destination module has:
300 // and the source module has something like
301 // %A' = type { i32 }
302 // %B = type { %A'* }
303 // @GV = global %B* null
304 // then we want to create a new type: "%B = type { %A*}" and have it take the
305 // pristine "%B" name from the source module.
307 // To determine which case this is, we have to recursively walk the type graph
308 // speculating that we'll be able to reuse it unmodified. Only if this is
309 // safe would we map the entire thing over. Because this is an optimization,
310 // and is not required for the prettiness of the linked module, we just skip
311 // it and always rebuild a type here.
312 StructType *STy = cast<StructType>(Ty);
314 // If the type is opaque, we can just use it directly.
318 // Otherwise we create a new type and resolve its body later. This will be
319 // resolved by the top level of get().
320 SrcDefinitionsToResolve.push_back(STy);
321 StructType *DTy = StructType::create(STy->getContext());
322 DstResolvedOpaqueTypes.insert(DTy);
328 //===----------------------------------------------------------------------===//
329 // ModuleLinker implementation.
330 //===----------------------------------------------------------------------===//
333 /// ModuleLinker - This is an implementation class for the LinkModules
334 /// function, which is the entrypoint for this file.
340 /// ValueMap - Mapping of values from what they used to be in Src, to what
341 /// they are now in DstM. ValueToValueMapTy is a ValueMap, which involves
342 /// some overhead due to the use of Value handles which the Linker doesn't
343 /// actually need, but this allows us to reuse the ValueMapper code.
344 ValueToValueMapTy ValueMap;
346 struct AppendingVarInfo {
347 GlobalVariable *NewGV; // New aggregate global in dest module.
348 Constant *DstInit; // Old initializer from dest module.
349 Constant *SrcInit; // Old initializer from src module.
352 std::vector<AppendingVarInfo> AppendingVars;
354 unsigned Mode; // Mode to treat source module.
356 // Set of items not to link in from source.
357 SmallPtrSet<const Value*, 16> DoNotLinkFromSource;
359 // Vector of functions to lazily link in.
360 std::vector<Function*> LazilyLinkFunctions;
363 std::string ErrorMsg;
365 ModuleLinker(Module *dstM, Module *srcM, unsigned mode)
366 : DstM(dstM), SrcM(srcM), Mode(mode) { }
371 /// emitError - Helper method for setting a message and returning an error
373 bool emitError(const Twine &Message) {
374 ErrorMsg = Message.str();
378 /// getLinkageResult - This analyzes the two global values and determines
379 /// what the result will look like in the destination module.
380 bool getLinkageResult(GlobalValue *Dest, const GlobalValue *Src,
381 GlobalValue::LinkageTypes <, bool &LinkFromSrc);
383 /// getLinkedToGlobal - Given a global in the source module, return the
384 /// global in the destination module that is being linked to, if any.
385 GlobalValue *getLinkedToGlobal(GlobalValue *SrcGV) {
386 // If the source has no name it can't link. If it has local linkage,
387 // there is no name match-up going on.
388 if (!SrcGV->hasName() || SrcGV->hasLocalLinkage())
391 // Otherwise see if we have a match in the destination module's symtab.
392 GlobalValue *DGV = DstM->getNamedValue(SrcGV->getName());
393 if (DGV == 0) return 0;
395 // If we found a global with the same name in the dest module, but it has
396 // internal linkage, we are really not doing any linkage here.
397 if (DGV->hasLocalLinkage())
400 // Otherwise, we do in fact link to the destination global.
404 void computeTypeMapping();
406 bool linkAppendingVarProto(GlobalVariable *DstGV, GlobalVariable *SrcGV);
407 bool linkGlobalProto(GlobalVariable *SrcGV);
408 bool linkFunctionProto(Function *SrcF);
409 bool linkAliasProto(GlobalAlias *SrcA);
411 void linkAppendingVarInit(const AppendingVarInfo &AVI);
412 void linkGlobalInits();
413 void linkFunctionBody(Function *Dst, Function *Src);
414 void linkAliasBodies();
415 void linkNamedMDNodes();
421 /// forceRenaming - The LLVM SymbolTable class autorenames globals that conflict
422 /// in the symbol table. This is good for all clients except for us. Go
423 /// through the trouble to force this back.
424 static void forceRenaming(GlobalValue *GV, StringRef Name) {
425 // If the global doesn't force its name or if it already has the right name,
426 // there is nothing for us to do.
427 if (GV->hasLocalLinkage() || GV->getName() == Name)
430 Module *M = GV->getParent();
432 // If there is a conflict, rename the conflict.
433 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
434 GV->takeName(ConflictGV);
435 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
436 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
438 GV->setName(Name); // Force the name back
442 /// CopyGVAttributes - copy additional attributes (those not needed to construct
443 /// a GlobalValue) from the SrcGV to the DestGV.
444 static void CopyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) {
445 // Use the maximum alignment, rather than just copying the alignment of SrcGV.
446 unsigned Alignment = std::max(DestGV->getAlignment(), SrcGV->getAlignment());
447 DestGV->copyAttributesFrom(SrcGV);
448 DestGV->setAlignment(Alignment);
450 forceRenaming(DestGV, SrcGV->getName());
453 /// getLinkageResult - This analyzes the two global values and determines what
454 /// the result will look like in the destination module. In particular, it
455 /// computes the resultant linkage type, computes whether the global in the
456 /// source should be copied over to the destination (replacing the existing
457 /// one), and computes whether this linkage is an error or not. It also performs
458 /// visibility checks: we cannot link together two symbols with different
460 bool ModuleLinker::getLinkageResult(GlobalValue *Dest, const GlobalValue *Src,
461 GlobalValue::LinkageTypes <,
463 assert(Dest && "Must have two globals being queried");
464 assert(!Src->hasLocalLinkage() &&
465 "If Src has internal linkage, Dest shouldn't be set!");
467 bool SrcIsDeclaration = Src->isDeclaration() && !Src->isMaterializable();
468 bool DestIsDeclaration = Dest->isDeclaration();
470 if (SrcIsDeclaration) {
471 // If Src is external or if both Src & Dest are external.. Just link the
472 // external globals, we aren't adding anything.
473 if (Src->hasDLLImportLinkage()) {
474 // If one of GVs has DLLImport linkage, result should be dllimport'ed.
475 if (DestIsDeclaration) {
477 LT = Src->getLinkage();
479 } else if (Dest->hasExternalWeakLinkage()) {
480 // If the Dest is weak, use the source linkage.
482 LT = Src->getLinkage();
485 LT = Dest->getLinkage();
487 } else if (DestIsDeclaration && !Dest->hasDLLImportLinkage()) {
488 // If Dest is external but Src is not:
490 LT = Src->getLinkage();
491 } else if (Src->isWeakForLinker()) {
492 // At this point we know that Dest has LinkOnce, External*, Weak, Common,
494 if (Dest->hasExternalWeakLinkage() ||
495 Dest->hasAvailableExternallyLinkage() ||
496 (Dest->hasLinkOnceLinkage() &&
497 (Src->hasWeakLinkage() || Src->hasCommonLinkage()))) {
499 LT = Src->getLinkage();
502 LT = Dest->getLinkage();
504 } else if (Dest->isWeakForLinker()) {
505 // At this point we know that Src has External* or DLL* linkage.
506 if (Src->hasExternalWeakLinkage()) {
508 LT = Dest->getLinkage();
511 LT = GlobalValue::ExternalLinkage;
514 assert((Dest->hasExternalLinkage() || Dest->hasDLLImportLinkage() ||
515 Dest->hasDLLExportLinkage() || Dest->hasExternalWeakLinkage()) &&
516 (Src->hasExternalLinkage() || Src->hasDLLImportLinkage() ||
517 Src->hasDLLExportLinkage() || Src->hasExternalWeakLinkage()) &&
518 "Unexpected linkage type!");
519 return emitError("Linking globals named '" + Src->getName() +
520 "': symbol multiply defined!");
524 if (Src->getVisibility() != Dest->getVisibility() &&
525 !SrcIsDeclaration && !DestIsDeclaration &&
526 !Src->hasAvailableExternallyLinkage() &&
527 !Dest->hasAvailableExternallyLinkage())
528 return emitError("Linking globals named '" + Src->getName() +
529 "': symbols have different visibilities!");
533 /// computeTypeMapping - Loop over all of the linked values to compute type
534 /// mappings. For example, if we link "extern Foo *x" and "Foo *x = NULL", then
535 /// we have two struct types 'Foo' but one got renamed when the module was
536 /// loaded into the same LLVMContext.
537 void ModuleLinker::computeTypeMapping() {
538 // Incorporate globals.
539 for (Module::global_iterator I = SrcM->global_begin(),
540 E = SrcM->global_end(); I != E; ++I) {
541 GlobalValue *DGV = getLinkedToGlobal(I);
542 if (DGV == 0) continue;
544 if (!DGV->hasAppendingLinkage() || !I->hasAppendingLinkage()) {
545 TypeMap.addTypeMapping(DGV->getType(), I->getType());
549 // Unify the element type of appending arrays.
550 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
551 ArrayType *SAT = cast<ArrayType>(I->getType()->getElementType());
552 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
555 // Incorporate functions.
556 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I) {
557 if (GlobalValue *DGV = getLinkedToGlobal(I))
558 TypeMap.addTypeMapping(DGV->getType(), I->getType());
561 // Incorporate types by name, scanning all the types in the source module.
562 // At this point, the destination module may have a type "%foo = { i32 }" for
563 // example. When the source module got loaded into the same LLVMContext, if
564 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
565 // Though it isn't required for correctness, attempt to link these up to clean
567 std::vector<StructType*> SrcStructTypes;
568 SrcM->findUsedStructTypes(SrcStructTypes);
570 for (unsigned i = 0, e = SrcStructTypes.size(); i != e; ++i) {
571 StructType *ST = SrcStructTypes[i];
572 if (!ST->hasName()) continue;
574 // Check to see if there is a dot in the name followed by a digit.
575 size_t DotPos = ST->getName().rfind('.');
576 if (DotPos == 0 || DotPos == StringRef::npos ||
577 ST->getName().back() == '.' || !isdigit(ST->getName()[DotPos+1]))
580 // Check to see if the destination module has a struct with the prefix name.
581 if (StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos)))
582 TypeMap.addTypeMapping(DST, ST);
586 // Don't bother incorporating aliases, they aren't generally typed well.
588 // Now that we have discovered all of the type equivalences, get a body for
589 // any 'opaque' types in the dest module that are now resolved.
590 TypeMap.linkDefinedTypeBodies();
593 /// linkAppendingVarProto - If there were any appending global variables, link
594 /// them together now. Return true on error.
595 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
596 GlobalVariable *SrcGV) {
598 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
599 return emitError("Linking globals named '" + SrcGV->getName() +
600 "': can only link appending global with another appending global!");
602 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
604 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
605 Type *EltTy = DstTy->getElementType();
607 // Check to see that they two arrays agree on type.
608 if (EltTy != SrcTy->getElementType())
609 return emitError("Appending variables with different element types!");
610 if (DstGV->isConstant() != SrcGV->isConstant())
611 return emitError("Appending variables linked with different const'ness!");
613 if (DstGV->getAlignment() != SrcGV->getAlignment())
615 "Appending variables with different alignment need to be linked!");
617 if (DstGV->getVisibility() != SrcGV->getVisibility())
619 "Appending variables with different visibility need to be linked!");
621 if (DstGV->getSection() != SrcGV->getSection())
623 "Appending variables with different section name need to be linked!");
625 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements();
626 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
628 // Create the new global variable.
630 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(),
631 DstGV->getLinkage(), /*init*/0, /*name*/"", DstGV,
632 DstGV->isThreadLocal(),
633 DstGV->getType()->getAddressSpace());
635 // Propagate alignment, visibility and section info.
636 CopyGVAttributes(NG, DstGV);
638 AppendingVarInfo AVI;
640 AVI.DstInit = DstGV->getInitializer();
641 AVI.SrcInit = SrcGV->getInitializer();
642 AppendingVars.push_back(AVI);
644 // Replace any uses of the two global variables with uses of the new
646 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
648 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
649 DstGV->eraseFromParent();
651 // Track the source variable so we don't try to link it.
652 DoNotLinkFromSource.insert(SrcGV);
657 /// linkGlobalProto - Loop through the global variables in the src module and
658 /// merge them into the dest module.
659 bool ModuleLinker::linkGlobalProto(GlobalVariable *SGV) {
660 GlobalValue *DGV = getLinkedToGlobal(SGV);
663 // Concatenation of appending linkage variables is magic and handled later.
664 if (DGV->hasAppendingLinkage() || SGV->hasAppendingLinkage())
665 return linkAppendingVarProto(cast<GlobalVariable>(DGV), SGV);
667 // Determine whether linkage of these two globals follows the source
668 // module's definition or the destination module's definition.
669 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
670 bool LinkFromSrc = false;
671 if (getLinkageResult(DGV, SGV, NewLinkage, LinkFromSrc))
674 // If we're not linking from the source, then keep the definition that we
677 // Special case for const propagation.
678 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV))
679 if (DGVar->isDeclaration() && SGV->isConstant() && !DGVar->isConstant())
680 DGVar->setConstant(true);
682 // Set calculated linkage.
683 DGV->setLinkage(NewLinkage);
685 // Make sure to remember this mapping.
686 ValueMap[SGV] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGV->getType()));
688 // Track the source global so that we don't attempt to copy it over when
689 // processing global initializers.
690 DoNotLinkFromSource.insert(SGV);
696 // No linking to be performed or linking from the source: simply create an
697 // identical version of the symbol over in the dest module... the
698 // initializer will be filled in later by LinkGlobalInits.
699 GlobalVariable *NewDGV =
700 new GlobalVariable(*DstM, TypeMap.get(SGV->getType()->getElementType()),
701 SGV->isConstant(), SGV->getLinkage(), /*init*/0,
702 SGV->getName(), /*insertbefore*/0,
703 SGV->isThreadLocal(),
704 SGV->getType()->getAddressSpace());
705 // Propagate alignment, visibility and section info.
706 CopyGVAttributes(NewDGV, SGV);
709 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, DGV->getType()));
710 DGV->eraseFromParent();
713 // Make sure to remember this mapping.
714 ValueMap[SGV] = NewDGV;
718 /// linkFunctionProto - Link the function in the source module into the
719 /// destination module if needed, setting up mapping information.
720 bool ModuleLinker::linkFunctionProto(Function *SF) {
721 GlobalValue *DGV = getLinkedToGlobal(SF);
724 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
725 bool LinkFromSrc = false;
726 if (getLinkageResult(DGV, SF, NewLinkage, LinkFromSrc))
730 // Set calculated linkage
731 DGV->setLinkage(NewLinkage);
733 // Make sure to remember this mapping.
734 ValueMap[SF] = ConstantExpr::getBitCast(DGV, TypeMap.get(SF->getType()));
736 // Track the function from the source module so we don't attempt to remap
738 DoNotLinkFromSource.insert(SF);
744 // If there is no linkage to be performed or we are linking from the source,
746 Function *NewDF = Function::Create(TypeMap.get(SF->getFunctionType()),
747 SF->getLinkage(), SF->getName(), DstM);
748 CopyGVAttributes(NewDF, SF);
751 // Any uses of DF need to change to NewDF, with cast.
752 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, DGV->getType()));
753 DGV->eraseFromParent();
755 // Internal, LO_ODR, or LO linkage - stick in set to ignore and lazily link.
756 if (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() ||
757 SF->hasAvailableExternallyLinkage()) {
758 DoNotLinkFromSource.insert(SF);
759 LazilyLinkFunctions.push_back(SF);
763 ValueMap[SF] = NewDF;
767 /// LinkAliasProto - Set up prototypes for any aliases that come over from the
769 bool ModuleLinker::linkAliasProto(GlobalAlias *SGA) {
770 GlobalValue *DGV = getLinkedToGlobal(SGA);
773 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
774 bool LinkFromSrc = false;
775 if (getLinkageResult(DGV, SGA, NewLinkage, LinkFromSrc))
779 // Set calculated linkage.
780 DGV->setLinkage(NewLinkage);
782 // Make sure to remember this mapping.
783 ValueMap[SGA] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGA->getType()));
785 // Track the alias from the source module so we don't attempt to remap it.
786 DoNotLinkFromSource.insert(SGA);
792 // If there is no linkage to be performed or we're linking from the source,
794 GlobalAlias *NewDA = new GlobalAlias(TypeMap.get(SGA->getType()),
795 SGA->getLinkage(), SGA->getName(),
797 CopyGVAttributes(NewDA, SGA);
800 // Any uses of DGV need to change to NewDA, with cast.
801 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDA, DGV->getType()));
802 DGV->eraseFromParent();
805 ValueMap[SGA] = NewDA;
809 void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) {
810 // Merge the initializer.
811 SmallVector<Constant*, 16> Elements;
812 if (ConstantArray *I = dyn_cast<ConstantArray>(AVI.DstInit)) {
813 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
814 Elements.push_back(I->getOperand(i));
816 assert(isa<ConstantAggregateZero>(AVI.DstInit));
817 ArrayType *DstAT = cast<ArrayType>(AVI.DstInit->getType());
818 Type *EltTy = DstAT->getElementType();
819 Elements.append(DstAT->getNumElements(), Constant::getNullValue(EltTy));
822 Constant *SrcInit = MapValue(AVI.SrcInit, ValueMap, RF_None, &TypeMap);
823 if (const ConstantArray *I = dyn_cast<ConstantArray>(SrcInit)) {
824 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
825 Elements.push_back(I->getOperand(i));
827 assert(isa<ConstantAggregateZero>(SrcInit));
828 ArrayType *SrcAT = cast<ArrayType>(SrcInit->getType());
829 Type *EltTy = SrcAT->getElementType();
830 Elements.append(SrcAT->getNumElements(), Constant::getNullValue(EltTy));
832 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
833 AVI.NewGV->setInitializer(ConstantArray::get(NewType, Elements));
837 // linkGlobalInits - Update the initializers in the Dest module now that all
838 // globals that may be referenced are in Dest.
839 void ModuleLinker::linkGlobalInits() {
840 // Loop over all of the globals in the src module, mapping them over as we go
841 for (Module::const_global_iterator I = SrcM->global_begin(),
842 E = SrcM->global_end(); I != E; ++I) {
844 // Only process initialized GV's or ones not already in dest.
845 if (!I->hasInitializer() || DoNotLinkFromSource.count(I)) continue;
847 // Grab destination global variable.
848 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[I]);
849 // Figure out what the initializer looks like in the dest module.
850 DGV->setInitializer(MapValue(I->getInitializer(), ValueMap,
855 // linkFunctionBody - Copy the source function over into the dest function and
856 // fix up references to values. At this point we know that Dest is an external
857 // function, and that Src is not.
858 void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) {
859 assert(Src && Dst && Dst->isDeclaration() && !Src->isDeclaration());
861 // Go through and convert function arguments over, remembering the mapping.
862 Function::arg_iterator DI = Dst->arg_begin();
863 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
865 DI->setName(I->getName()); // Copy the name over.
867 // Add a mapping to our mapping.
871 if (Mode == Linker::DestroySource) {
872 // Splice the body of the source function into the dest function.
873 Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList());
875 // At this point, all of the instructions and values of the function are now
876 // copied over. The only problem is that they are still referencing values in
877 // the Source function as operands. Loop through all of the operands of the
878 // functions and patch them up to point to the local versions.
879 for (Function::iterator BB = Dst->begin(), BE = Dst->end(); BB != BE; ++BB)
880 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
881 RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries, &TypeMap);
884 // Clone the body of the function into the dest function.
885 SmallVector<ReturnInst*, 8> Returns; // Ignore returns.
886 CloneFunctionInto(Dst, Src, ValueMap, false, Returns);
889 // There is no need to map the arguments anymore.
890 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
897 void ModuleLinker::linkAliasBodies() {
898 for (Module::alias_iterator I = SrcM->alias_begin(), E = SrcM->alias_end();
900 if (DoNotLinkFromSource.count(I))
902 if (Constant *Aliasee = I->getAliasee()) {
903 GlobalAlias *DA = cast<GlobalAlias>(ValueMap[I]);
904 DA->setAliasee(MapValue(Aliasee, ValueMap, RF_None, &TypeMap));
909 /// linkNamedMDNodes - Insert all of the named mdnodes in Src into the Dest
911 void ModuleLinker::linkNamedMDNodes() {
912 for (Module::const_named_metadata_iterator I = SrcM->named_metadata_begin(),
913 E = SrcM->named_metadata_end(); I != E; ++I) {
914 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName());
915 // Add Src elements into Dest node.
916 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
917 DestNMD->addOperand(MapValue(I->getOperand(i), ValueMap,
922 bool ModuleLinker::run() {
923 assert(DstM && "Null Destination module");
924 assert(SrcM && "Null Source Module");
926 // Inherit the target data from the source module if the destination module
927 // doesn't have one already.
928 if (DstM->getDataLayout().empty() && !SrcM->getDataLayout().empty())
929 DstM->setDataLayout(SrcM->getDataLayout());
931 // Copy the target triple from the source to dest if the dest's is empty.
932 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
933 DstM->setTargetTriple(SrcM->getTargetTriple());
935 if (!SrcM->getDataLayout().empty() && !DstM->getDataLayout().empty() &&
936 SrcM->getDataLayout() != DstM->getDataLayout())
937 errs() << "WARNING: Linking two modules of different data layouts!\n";
938 if (!SrcM->getTargetTriple().empty() &&
939 DstM->getTargetTriple() != SrcM->getTargetTriple()) {
940 errs() << "WARNING: Linking two modules of different target triples: ";
941 if (!SrcM->getModuleIdentifier().empty())
942 errs() << SrcM->getModuleIdentifier() << ": ";
943 errs() << "'" << SrcM->getTargetTriple() << "' and '"
944 << DstM->getTargetTriple() << "'\n";
947 // Append the module inline asm string.
948 if (!SrcM->getModuleInlineAsm().empty()) {
949 if (DstM->getModuleInlineAsm().empty())
950 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
952 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
953 SrcM->getModuleInlineAsm());
956 // Update the destination module's dependent libraries list with the libraries
957 // from the source module. There's no opportunity for duplicates here as the
958 // Module ensures that duplicate insertions are discarded.
959 for (Module::lib_iterator SI = SrcM->lib_begin(), SE = SrcM->lib_end();
961 DstM->addLibrary(*SI);
963 // If the source library's module id is in the dependent library list of the
964 // destination library, remove it since that module is now linked in.
965 StringRef ModuleId = SrcM->getModuleIdentifier();
966 if (!ModuleId.empty())
967 DstM->removeLibrary(sys::path::stem(ModuleId));
969 // Loop over all of the linked values to compute type mappings.
970 computeTypeMapping();
972 // Insert all of the globals in src into the DstM module... without linking
973 // initializers (which could refer to functions not yet mapped over).
974 for (Module::global_iterator I = SrcM->global_begin(),
975 E = SrcM->global_end(); I != E; ++I)
976 if (linkGlobalProto(I))
979 // Link the functions together between the two modules, without doing function
980 // bodies... this just adds external function prototypes to the DstM
981 // function... We do this so that when we begin processing function bodies,
982 // all of the global values that may be referenced are available in our
984 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I)
985 if (linkFunctionProto(I))
988 // If there were any aliases, link them now.
989 for (Module::alias_iterator I = SrcM->alias_begin(),
990 E = SrcM->alias_end(); I != E; ++I)
991 if (linkAliasProto(I))
994 for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i)
995 linkAppendingVarInit(AppendingVars[i]);
997 // Update the initializers in the DstM module now that all globals that may
998 // be referenced are in DstM.
1001 // Link in the function bodies that are defined in the source module into
1003 for (Module::iterator SF = SrcM->begin(), E = SrcM->end(); SF != E; ++SF) {
1005 // Skip if not linking from source.
1006 if (DoNotLinkFromSource.count(SF)) continue;
1008 // Skip if no body (function is external) or materialize.
1009 if (SF->isDeclaration()) {
1010 if (!SF->isMaterializable())
1012 if (SF->Materialize(&ErrorMsg))
1016 linkFunctionBody(cast<Function>(ValueMap[SF]), SF);
1019 // Resolve all uses of aliases with aliasees.
1022 // Remap all of the named mdnoes in Src into the DstM module. We do this
1023 // after linking GlobalValues so that MDNodes that reference GlobalValues
1024 // are properly remapped.
1027 // Process vector of lazily linked in functions.
1028 bool LinkedInAnyFunctions;
1030 LinkedInAnyFunctions = false;
1032 for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(),
1033 E = LazilyLinkFunctions.end(); I != E; ++I) {
1038 Function *DF = cast<Function>(ValueMap[SF]);
1040 if (!DF->use_empty()) {
1042 // Materialize if necessary.
1043 if (SF->isDeclaration()) {
1044 if (!SF->isMaterializable())
1046 if (SF->Materialize(&ErrorMsg))
1050 // Link in function body.
1051 linkFunctionBody(DF, SF);
1053 // "Remove" from vector by setting the element to 0.
1056 // Set flag to indicate we may have more functions to lazily link in
1057 // since we linked in a function.
1058 LinkedInAnyFunctions = true;
1061 } while (LinkedInAnyFunctions);
1063 // Remove any prototypes of functions that were not actually linked in.
1064 for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(),
1065 E = LazilyLinkFunctions.end(); I != E; ++I) {
1070 Function *DF = cast<Function>(ValueMap[SF]);
1071 if (DF->use_empty())
1072 DF->eraseFromParent();
1075 // Now that all of the types from the source are used, resolve any structs
1076 // copied over to the dest that didn't exist there.
1077 TypeMap.linkDefinedTypeBodies();
1082 //===----------------------------------------------------------------------===//
1083 // LinkModules entrypoint.
1084 //===----------------------------------------------------------------------===//
1086 // LinkModules - This function links two modules together, with the resulting
1087 // left module modified to be the composite of the two input modules. If an
1088 // error occurs, true is returned and ErrorMsg (if not null) is set to indicate
1089 // the problem. Upon failure, the Dest module could be in a modified state, and
1090 // shouldn't be relied on to be consistent.
1091 bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Mode,
1092 std::string *ErrorMsg) {
1093 ModuleLinker TheLinker(Dest, Src, Mode);
1094 if (TheLinker.run()) {
1095 if (ErrorMsg) *ErrorMsg = TheLinker.ErrorMsg;