1 //===- lib/Linker/LinkModules.cpp - Module Linker Implementation ----------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements the LLVM module linker.
11 //
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Linker.h"
15 #include "llvm-c/Linker.h"
16 #include "llvm/ADT/Optional.h"
17 #include "llvm/ADT/SetVector.h"
18 #include "llvm/ADT/SmallString.h"
19 #include "llvm/IR/Constants.h"
20 #include "llvm/IR/Module.h"
21 #include "llvm/IR/TypeFinder.h"
22 #include "llvm/Support/Debug.h"
23 #include "llvm/Support/raw_ostream.h"
24 #include "llvm/Transforms/Utils/Cloning.h"
25 using namespace llvm;
27 //===----------------------------------------------------------------------===//
28 // TypeMap implementation.
29 //===----------------------------------------------------------------------===//
31 namespace {
32 typedef SmallPtrSet<StructType*, 32> TypeSet;
34 class TypeMapTy : public ValueMapTypeRemapper {
35 /// MappedTypes - This is a mapping from a source type to a destination type
36 /// to use.
37 DenseMap<Type*, Type*> MappedTypes;
39 /// SpeculativeTypes - When checking to see if two subgraphs are isomorphic,
40 /// we speculatively add types to MappedTypes, but keep track of them here in
41 /// case we need to roll back.
42 SmallVector<Type*, 16> SpeculativeTypes;
44 /// SrcDefinitionsToResolve - This is a list of non-opaque structs in the
45 /// source module that are mapped to an opaque struct in the destination
46 /// module.
47 SmallVector<StructType*, 16> SrcDefinitionsToResolve;
49 /// DstResolvedOpaqueTypes - This is the set of opaque types in the
50 /// destination modules who are getting a body from the source module.
51 SmallPtrSet<StructType*, 16> DstResolvedOpaqueTypes;
53 public:
54 TypeMapTy(TypeSet &Set) : DstStructTypesSet(Set) {}
56 TypeSet &DstStructTypesSet;
57 /// addTypeMapping - Indicate that the specified type in the destination
58 /// module is conceptually equivalent to the specified type in the source
59 /// module.
60 void addTypeMapping(Type *DstTy, Type *SrcTy);
62 /// linkDefinedTypeBodies - Produce a body for an opaque type in the dest
63 /// module from a type definition in the source module.
64 void linkDefinedTypeBodies();
66 /// get - Return the mapped type to use for the specified input type from the
67 /// source module.
68 Type *get(Type *SrcTy);
70 FunctionType *get(FunctionType *T) {return cast<FunctionType>(get((Type*)T));}
72 /// dump - Dump out the type map for debugging purposes.
73 void dump() const {
74 for (DenseMap<Type*, Type*>::const_iterator
75 I = MappedTypes.begin(), E = MappedTypes.end(); I != E; ++I) {
76 dbgs() << "TypeMap: ";
77 I->first->dump();
78 dbgs() << " => ";
79 I->second->dump();
80 dbgs() << '\n';
81 }
82 }
84 private:
85 Type *getImpl(Type *T);
86 /// remapType - Implement the ValueMapTypeRemapper interface.
87 Type *remapType(Type *SrcTy) {
88 return get(SrcTy);
89 }
91 bool areTypesIsomorphic(Type *DstTy, Type *SrcTy);
92 };
93 }
95 void TypeMapTy::addTypeMapping(Type *DstTy, Type *SrcTy) {
96 Type *&Entry = MappedTypes[SrcTy];
97 if (Entry) return;
99 if (DstTy == SrcTy) {
100 Entry = DstTy;
101 return;
102 }
104 // Check to see if these types are recursively isomorphic and establish a
105 // mapping between them if so.
106 if (!areTypesIsomorphic(DstTy, SrcTy)) {
107 // Oops, they aren't isomorphic. Just discard this request by rolling out
108 // any speculative mappings we've established.
109 for (unsigned i = 0, e = SpeculativeTypes.size(); i != e; ++i)
110 MappedTypes.erase(SpeculativeTypes[i]);
111 }
112 SpeculativeTypes.clear();
113 }
115 /// areTypesIsomorphic - Recursively walk this pair of types, returning true
116 /// if they are isomorphic, false if they are not.
117 bool TypeMapTy::areTypesIsomorphic(Type *DstTy, Type *SrcTy) {
118 // Two types with differing kinds are clearly not isomorphic.
119 if (DstTy->getTypeID() != SrcTy->getTypeID()) return false;
121 // If we have an entry in the MappedTypes table, then we have our answer.
122 Type *&Entry = MappedTypes[SrcTy];
123 if (Entry)
124 return Entry == DstTy;
126 // Two identical types are clearly isomorphic. Remember this
127 // non-speculatively.
128 if (DstTy == SrcTy) {
129 Entry = DstTy;
130 return true;
131 }
133 // Okay, we have two types with identical kinds that we haven't seen before.
135 // If this is an opaque struct type, special case it.
136 if (StructType *SSTy = dyn_cast<StructType>(SrcTy)) {
137 // Mapping an opaque type to any struct, just keep the dest struct.
138 if (SSTy->isOpaque()) {
139 Entry = DstTy;
140 SpeculativeTypes.push_back(SrcTy);
141 return true;
142 }
144 // Mapping a non-opaque source type to an opaque dest. If this is the first
145 // type that we're mapping onto this destination type then we succeed. Keep
146 // the dest, but fill it in later. This doesn't need to be speculative. If
147 // this is the second (different) type that we're trying to map onto the
148 // same opaque type then we fail.
149 if (cast<StructType>(DstTy)->isOpaque()) {
150 // We can only map one source type onto the opaque destination type.
151 if (!DstResolvedOpaqueTypes.insert(cast<StructType>(DstTy)))
152 return false;
153 SrcDefinitionsToResolve.push_back(SSTy);
154 Entry = DstTy;
155 return true;
156 }
157 }
159 // If the number of subtypes disagree between the two types, then we fail.
160 if (SrcTy->getNumContainedTypes() != DstTy->getNumContainedTypes())
161 return false;
163 // Fail if any of the extra properties (e.g. array size) of the type disagree.
164 if (isa<IntegerType>(DstTy))
165 return false; // bitwidth disagrees.
166 if (PointerType *PT = dyn_cast<PointerType>(DstTy)) {
167 if (PT->getAddressSpace() != cast<PointerType>(SrcTy)->getAddressSpace())
168 return false;
170 } else if (FunctionType *FT = dyn_cast<FunctionType>(DstTy)) {
171 if (FT->isVarArg() != cast<FunctionType>(SrcTy)->isVarArg())
172 return false;
173 } else if (StructType *DSTy = dyn_cast<StructType>(DstTy)) {
174 StructType *SSTy = cast<StructType>(SrcTy);
175 if (DSTy->isLiteral() != SSTy->isLiteral() ||
176 DSTy->isPacked() != SSTy->isPacked())
177 return false;
178 } else if (ArrayType *DATy = dyn_cast<ArrayType>(DstTy)) {
179 if (DATy->getNumElements() != cast<ArrayType>(SrcTy)->getNumElements())
180 return false;
181 } else if (VectorType *DVTy = dyn_cast<VectorType>(DstTy)) {
182 if (DVTy->getNumElements() != cast<VectorType>(SrcTy)->getNumElements())
183 return false;
184 }
186 // Otherwise, we speculate that these two types will line up and recursively
187 // check the subelements.
188 Entry = DstTy;
189 SpeculativeTypes.push_back(SrcTy);
191 for (unsigned i = 0, e = SrcTy->getNumContainedTypes(); i != e; ++i)
192 if (!areTypesIsomorphic(DstTy->getContainedType(i),
193 SrcTy->getContainedType(i)))
194 return false;
196 // If everything seems to have lined up, then everything is great.
197 return true;
198 }
200 /// linkDefinedTypeBodies - Produce a body for an opaque type in the dest
201 /// module from a type definition in the source module.
202 void TypeMapTy::linkDefinedTypeBodies() {
203 SmallVector<Type*, 16> Elements;
204 SmallString<16> TmpName;
206 // Note that processing entries in this loop (calling 'get') can add new
207 // entries to the SrcDefinitionsToResolve vector.
208 while (!SrcDefinitionsToResolve.empty()) {
209 StructType *SrcSTy = SrcDefinitionsToResolve.pop_back_val();
210 StructType *DstSTy = cast<StructType>(MappedTypes[SrcSTy]);
212 // TypeMap is a many-to-one mapping, if there were multiple types that
213 // provide a body for DstSTy then previous iterations of this loop may have
214 // already handled it. Just ignore this case.
215 if (!DstSTy->isOpaque()) continue;
216 assert(!SrcSTy->isOpaque() && "Not resolving a definition?");
218 // Map the body of the source type over to a new body for the dest type.
219 Elements.resize(SrcSTy->getNumElements());
220 for (unsigned i = 0, e = Elements.size(); i != e; ++i)
221 Elements[i] = getImpl(SrcSTy->getElementType(i));
223 DstSTy->setBody(Elements, SrcSTy->isPacked());
225 // If DstSTy has no name or has a longer name than STy, then viciously steal
226 // STy's name.
227 if (!SrcSTy->hasName()) continue;
228 StringRef SrcName = SrcSTy->getName();
230 if (!DstSTy->hasName() || DstSTy->getName().size() > SrcName.size()) {
231 TmpName.insert(TmpName.end(), SrcName.begin(), SrcName.end());
232 SrcSTy->setName("");
233 DstSTy->setName(TmpName.str());
234 TmpName.clear();
235 }
236 }
238 DstResolvedOpaqueTypes.clear();
239 }
241 /// get - Return the mapped type to use for the specified input type from the
242 /// source module.
243 Type *TypeMapTy::get(Type *Ty) {
244 Type *Result = getImpl(Ty);
246 // If this caused a reference to any struct type, resolve it before returning.
247 if (!SrcDefinitionsToResolve.empty())
248 linkDefinedTypeBodies();
249 return Result;
250 }
252 /// getImpl - This is the recursive version of get().
253 Type *TypeMapTy::getImpl(Type *Ty) {
254 // If we already have an entry for this type, return it.
255 Type **Entry = &MappedTypes[Ty];
256 if (*Entry) return *Entry;
258 // If this is not a named struct type, then just map all of the elements and
259 // then rebuild the type from inside out.
260 if (!isa<StructType>(Ty) || cast<StructType>(Ty)->isLiteral()) {
261 // If there are no element types to map, then the type is itself. This is
262 // true for the anonymous {} struct, things like 'float', integers, etc.
263 if (Ty->getNumContainedTypes() == 0)
264 return *Entry = Ty;
266 // Remap all of the elements, keeping track of whether any of them change.
267 bool AnyChange = false;
268 SmallVector<Type*, 4> ElementTypes;
269 ElementTypes.resize(Ty->getNumContainedTypes());
270 for (unsigned i = 0, e = Ty->getNumContainedTypes(); i != e; ++i) {
271 ElementTypes[i] = getImpl(Ty->getContainedType(i));
272 AnyChange |= ElementTypes[i] != Ty->getContainedType(i);
273 }
275 // If we found our type while recursively processing stuff, just use it.
276 Entry = &MappedTypes[Ty];
277 if (*Entry) return *Entry;
279 // If all of the element types mapped directly over, then the type is usable
280 // as-is.
281 if (!AnyChange)
282 return *Entry = Ty;
284 // Otherwise, rebuild a modified type.
285 switch (Ty->getTypeID()) {
286 default: llvm_unreachable("unknown derived type to remap");
287 case Type::ArrayTyID:
288 return *Entry = ArrayType::get(ElementTypes[0],
289 cast<ArrayType>(Ty)->getNumElements());
290 case Type::VectorTyID:
291 return *Entry = VectorType::get(ElementTypes[0],
292 cast<VectorType>(Ty)->getNumElements());
293 case Type::PointerTyID:
294 return *Entry = PointerType::get(ElementTypes[0],
295 cast<PointerType>(Ty)->getAddressSpace());
296 case Type::FunctionTyID:
297 return *Entry = FunctionType::get(ElementTypes[0],
298 makeArrayRef(ElementTypes).slice(1),
299 cast<FunctionType>(Ty)->isVarArg());
300 case Type::StructTyID:
301 // Note that this is only reached for anonymous structs.
302 return *Entry = StructType::get(Ty->getContext(), ElementTypes,
303 cast<StructType>(Ty)->isPacked());
304 }
305 }
307 // Otherwise, this is an unmapped named struct. If the struct can be directly
308 // mapped over, just use it as-is. This happens in a case when the linked-in
309 // module has something like:
310 // %T = type {%T*, i32}
311 // @GV = global %T* null
312 // where T does not exist at all in the destination module.
313 //
314 // The other case we watch for is when the type is not in the destination
315 // module, but that it has to be rebuilt because it refers to something that
316 // is already mapped. For example, if the destination module has:
317 // %A = type { i32 }
318 // and the source module has something like
319 // %A' = type { i32 }
320 // %B = type { %A'* }
321 // @GV = global %B* null
322 // then we want to create a new type: "%B = type { %A*}" and have it take the
323 // pristine "%B" name from the source module.
324 //
325 // To determine which case this is, we have to recursively walk the type graph
326 // speculating that we'll be able to reuse it unmodified. Only if this is
327 // safe would we map the entire thing over. Because this is an optimization,
328 // and is not required for the prettiness of the linked module, we just skip
329 // it and always rebuild a type here.
330 StructType *STy = cast<StructType>(Ty);
332 // If the type is opaque, we can just use it directly.
333 if (STy->isOpaque()) {
334 // A named structure type from src module is used. Add it to the Set of
335 // identified structs in the destination module.
336 DstStructTypesSet.insert(STy);
337 return *Entry = STy;
338 }
340 // Otherwise we create a new type and resolve its body later. This will be
341 // resolved by the top level of get().
342 SrcDefinitionsToResolve.push_back(STy);
343 StructType *DTy = StructType::create(STy->getContext());
344 // A new identified structure type was created. Add it to the set of
345 // identified structs in the destination module.
346 DstStructTypesSet.insert(DTy);
347 DstResolvedOpaqueTypes.insert(DTy);
348 return *Entry = DTy;
349 }
351 //===----------------------------------------------------------------------===//
352 // ModuleLinker implementation.
353 //===----------------------------------------------------------------------===//
355 namespace {
356 class ModuleLinker;
358 /// ValueMaterializerTy - Creates prototypes for functions that are lazily
359 /// linked on the fly. This speeds up linking for modules with many
360 /// lazily linked functions of which few get used.
361 class ValueMaterializerTy : public ValueMaterializer {
362 TypeMapTy &TypeMap;
363 Module *DstM;
364 std::vector<Function*> &LazilyLinkFunctions;
365 public:
366 ValueMaterializerTy(TypeMapTy &TypeMap, Module *DstM,
367 std::vector<Function*> &LazilyLinkFunctions) :
368 ValueMaterializer(), TypeMap(TypeMap), DstM(DstM),
369 LazilyLinkFunctions(LazilyLinkFunctions) {
370 }
372 virtual Value *materializeValueFor(Value *V);
373 };
375 /// ModuleLinker - This is an implementation class for the LinkModules
376 /// function, which is the entrypoint for this file.
377 class ModuleLinker {
378 Module *DstM, *SrcM;
380 TypeMapTy TypeMap;
381 ValueMaterializerTy ValMaterializer;
383 /// ValueMap - Mapping of values from what they used to be in Src, to what
384 /// they are now in DstM. ValueToValueMapTy is a ValueMap, which involves
385 /// some overhead due to the use of Value handles which the Linker doesn't
386 /// actually need, but this allows us to reuse the ValueMapper code.
387 ValueToValueMapTy ValueMap;
389 struct AppendingVarInfo {
390 GlobalVariable *NewGV; // New aggregate global in dest module.
391 Constant *DstInit; // Old initializer from dest module.
392 Constant *SrcInit; // Old initializer from src module.
393 };
395 std::vector<AppendingVarInfo> AppendingVars;
397 unsigned Mode; // Mode to treat source module.
399 // Set of items not to link in from source.
400 SmallPtrSet<const Value*, 16> DoNotLinkFromSource;
402 // Vector of functions to lazily link in.
403 std::vector<Function*> LazilyLinkFunctions;
405 public:
406 std::string ErrorMsg;
408 ModuleLinker(Module *dstM, TypeSet &Set, Module *srcM, unsigned mode)
409 : DstM(dstM), SrcM(srcM), TypeMap(Set),
410 ValMaterializer(TypeMap, DstM, LazilyLinkFunctions),
411 Mode(mode) { }
413 bool run();
415 private:
416 /// emitError - Helper method for setting a message and returning an error
417 /// code.
418 bool emitError(const Twine &Message) {
419 ErrorMsg = Message.str();
420 return true;
421 }
423 /// getLinkageResult - This analyzes the two global values and determines
424 /// what the result will look like in the destination module.
425 bool getLinkageResult(GlobalValue *Dest, const GlobalValue *Src,
426 GlobalValue::LinkageTypes <,
427 GlobalValue::VisibilityTypes &Vis,
428 bool &LinkFromSrc);
430 /// getLinkedToGlobal - Given a global in the source module, return the
431 /// global in the destination module that is being linked to, if any.
432 GlobalValue *getLinkedToGlobal(GlobalValue *SrcGV) {
433 // If the source has no name it can't link. If it has local linkage,
434 // there is no name match-up going on.
435 if (!SrcGV->hasName() || SrcGV->hasLocalLinkage())
436 return 0;
438 // Otherwise see if we have a match in the destination module's symtab.
439 GlobalValue *DGV = DstM->getNamedValue(SrcGV->getName());
440 if (DGV == 0) return 0;
442 // If we found a global with the same name in the dest module, but it has
443 // internal linkage, we are really not doing any linkage here.
444 if (DGV->hasLocalLinkage())
445 return 0;
447 // Otherwise, we do in fact link to the destination global.
448 return DGV;
449 }
451 void computeTypeMapping();
453 bool linkAppendingVarProto(GlobalVariable *DstGV, GlobalVariable *SrcGV);
454 bool linkGlobalProto(GlobalVariable *SrcGV);
455 bool linkFunctionProto(Function *SrcF);
456 bool linkAliasProto(GlobalAlias *SrcA);
457 bool linkModuleFlagsMetadata();
459 void linkAppendingVarInit(const AppendingVarInfo &AVI);
460 void linkGlobalInits();
461 void linkFunctionBody(Function *Dst, Function *Src);
462 void linkAliasBodies();
463 void linkNamedMDNodes();
464 };
465 }
467 /// forceRenaming - The LLVM SymbolTable class autorenames globals that conflict
468 /// in the symbol table. This is good for all clients except for us. Go
469 /// through the trouble to force this back.
470 static void forceRenaming(GlobalValue *GV, StringRef Name) {
471 // If the global doesn't force its name or if it already has the right name,
472 // there is nothing for us to do.
473 if (GV->hasLocalLinkage() || GV->getName() == Name)
474 return;
476 Module *M = GV->getParent();
478 // If there is a conflict, rename the conflict.
479 if (GlobalValue *ConflictGV = M->getNamedValue(Name)) {
480 GV->takeName(ConflictGV);
481 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed
482 assert(ConflictGV->getName() != Name && "forceRenaming didn't work");
483 } else {
484 GV->setName(Name); // Force the name back
485 }
486 }
488 /// copyGVAttributes - copy additional attributes (those not needed to construct
489 /// a GlobalValue) from the SrcGV to the DestGV.
490 static void copyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) {
491 // Use the maximum alignment, rather than just copying the alignment of SrcGV.
492 unsigned Alignment = std::max(DestGV->getAlignment(), SrcGV->getAlignment());
493 DestGV->copyAttributesFrom(SrcGV);
494 DestGV->setAlignment(Alignment);
496 forceRenaming(DestGV, SrcGV->getName());
497 }
499 static bool isLessConstraining(GlobalValue::VisibilityTypes a,
500 GlobalValue::VisibilityTypes b) {
501 if (a == GlobalValue::HiddenVisibility)
502 return false;
503 if (b == GlobalValue::HiddenVisibility)
504 return true;
505 if (a == GlobalValue::ProtectedVisibility)
506 return false;
507 if (b == GlobalValue::ProtectedVisibility)
508 return true;
509 return false;
510 }
512 Value *ValueMaterializerTy::materializeValueFor(Value *V) {
513 Function *SF = dyn_cast<Function>(V);
514 if (!SF)
515 return NULL;
517 Function *DF = Function::Create(TypeMap.get(SF->getFunctionType()),
518 SF->getLinkage(), SF->getName(), DstM);
519 copyGVAttributes(DF, SF);
521 LazilyLinkFunctions.push_back(SF);
522 return DF;
523 }
526 /// getLinkageResult - This analyzes the two global values and determines what
527 /// the result will look like in the destination module. In particular, it
528 /// computes the resultant linkage type and visibility, computes whether the
529 /// global in the source should be copied over to the destination (replacing
530 /// the existing one), and computes whether this linkage is an error or not.
531 bool ModuleLinker::getLinkageResult(GlobalValue *Dest, const GlobalValue *Src,
532 GlobalValue::LinkageTypes <,
533 GlobalValue::VisibilityTypes &Vis,
534 bool &LinkFromSrc) {
535 assert(Dest && "Must have two globals being queried");
536 assert(!Src->hasLocalLinkage() &&
537 "If Src has internal linkage, Dest shouldn't be set!");
539 bool SrcIsDeclaration = Src->isDeclaration() && !Src->isMaterializable();
540 bool DestIsDeclaration = Dest->isDeclaration();
542 if (SrcIsDeclaration) {
543 // If Src is external or if both Src & Dest are external.. Just link the
544 // external globals, we aren't adding anything.
545 if (Src->hasDLLImportLinkage()) {
546 // If one of GVs has DLLImport linkage, result should be dllimport'ed.
547 if (DestIsDeclaration) {
548 LinkFromSrc = true;
549 LT = Src->getLinkage();
550 }
551 } else if (Dest->hasExternalWeakLinkage()) {
552 // If the Dest is weak, use the source linkage.
553 LinkFromSrc = true;
554 LT = Src->getLinkage();
555 } else {
556 LinkFromSrc = false;
557 LT = Dest->getLinkage();
558 }
559 } else if (DestIsDeclaration && !Dest->hasDLLImportLinkage()) {
560 // If Dest is external but Src is not:
561 LinkFromSrc = true;
562 LT = Src->getLinkage();
563 } else if (Src->isWeakForLinker()) {
564 // At this point we know that Dest has LinkOnce, External*, Weak, Common,
565 // or DLL* linkage.
566 if (Dest->hasExternalWeakLinkage() ||
567 Dest->hasAvailableExternallyLinkage() ||
568 (Dest->hasLinkOnceLinkage() &&
569 (Src->hasWeakLinkage() || Src->hasCommonLinkage()))) {
570 LinkFromSrc = true;
571 LT = Src->getLinkage();
572 } else {
573 LinkFromSrc = false;
574 LT = Dest->getLinkage();
575 }
576 } else if (Dest->isWeakForLinker()) {
577 // At this point we know that Src has External* or DLL* linkage.
578 if (Src->hasExternalWeakLinkage()) {
579 LinkFromSrc = false;
580 LT = Dest->getLinkage();
581 } else {
582 LinkFromSrc = true;
583 LT = GlobalValue::ExternalLinkage;
584 }
585 } else {
586 assert((Dest->hasExternalLinkage() || Dest->hasDLLImportLinkage() ||
587 Dest->hasDLLExportLinkage() || Dest->hasExternalWeakLinkage()) &&
588 (Src->hasExternalLinkage() || Src->hasDLLImportLinkage() ||
589 Src->hasDLLExportLinkage() || Src->hasExternalWeakLinkage()) &&
590 "Unexpected linkage type!");
591 return emitError("Linking globals named '" + Src->getName() +
592 "': symbol multiply defined!");
593 }
595 // Compute the visibility. We follow the rules in the System V Application
596 // Binary Interface.
597 Vis = isLessConstraining(Src->getVisibility(), Dest->getVisibility()) ?
598 Dest->getVisibility() : Src->getVisibility();
599 return false;
600 }
602 /// computeTypeMapping - Loop over all of the linked values to compute type
603 /// mappings. For example, if we link "extern Foo *x" and "Foo *x = NULL", then
604 /// we have two struct types 'Foo' but one got renamed when the module was
605 /// loaded into the same LLVMContext.
606 void ModuleLinker::computeTypeMapping() {
607 // Incorporate globals.
608 for (Module::global_iterator I = SrcM->global_begin(),
609 E = SrcM->global_end(); I != E; ++I) {
610 GlobalValue *DGV = getLinkedToGlobal(I);
611 if (DGV == 0) continue;
613 if (!DGV->hasAppendingLinkage() || !I->hasAppendingLinkage()) {
614 TypeMap.addTypeMapping(DGV->getType(), I->getType());
615 continue;
616 }
618 // Unify the element type of appending arrays.
619 ArrayType *DAT = cast<ArrayType>(DGV->getType()->getElementType());
620 ArrayType *SAT = cast<ArrayType>(I->getType()->getElementType());
621 TypeMap.addTypeMapping(DAT->getElementType(), SAT->getElementType());
622 }
624 // Incorporate functions.
625 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I) {
626 if (GlobalValue *DGV = getLinkedToGlobal(I))
627 TypeMap.addTypeMapping(DGV->getType(), I->getType());
628 }
630 // Incorporate types by name, scanning all the types in the source module.
631 // At this point, the destination module may have a type "%foo = { i32 }" for
632 // example. When the source module got loaded into the same LLVMContext, if
633 // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
634 TypeFinder SrcStructTypes;
635 SrcStructTypes.run(*SrcM, true);
636 SmallPtrSet<StructType*, 32> SrcStructTypesSet(SrcStructTypes.begin(),
637 SrcStructTypes.end());
639 for (unsigned i = 0, e = SrcStructTypes.size(); i != e; ++i) {
640 StructType *ST = SrcStructTypes[i];
641 if (!ST->hasName()) continue;
643 // Check to see if there is a dot in the name followed by a digit.
644 size_t DotPos = ST->getName().rfind('.');
645 if (DotPos == 0 || DotPos == StringRef::npos ||
646 ST->getName().back() == '.' ||
647 !isdigit(static_cast<unsigned char>(ST->getName()[DotPos+1])))
648 continue;
650 // Check to see if the destination module has a struct with the prefix name.
651 if (StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos)))
652 // Don't use it if this actually came from the source module. They're in
653 // the same LLVMContext after all. Also don't use it unless the type is
654 // actually used in the destination module. This can happen in situations
655 // like this:
656 //
657 // Module A Module B
658 // -------- --------
659 // %Z = type { %A } %B = type { %C.1 }
660 // %A = type { %B.1, [7 x i8] } %C.1 = type { i8* }
661 // %B.1 = type { %C } %A.2 = type { %B.3, [5 x i8] }
662 // %C = type { i8* } %B.3 = type { %C.1 }
663 //
664 // When we link Module B with Module A, the '%B' in Module B is
665 // used. However, that would then use '%C.1'. But when we process '%C.1',
666 // we prefer to take the '%C' version. So we are then left with both
667 // '%C.1' and '%C' being used for the same types. This leads to some
668 // variables using one type and some using the other.
669 if (!SrcStructTypesSet.count(DST) && TypeMap.DstStructTypesSet.count(DST))
670 TypeMap.addTypeMapping(DST, ST);
671 }
673 // Don't bother incorporating aliases, they aren't generally typed well.
675 // Now that we have discovered all of the type equivalences, get a body for
676 // any 'opaque' types in the dest module that are now resolved.
677 TypeMap.linkDefinedTypeBodies();
678 }
680 /// linkAppendingVarProto - If there were any appending global variables, link
681 /// them together now. Return true on error.
682 bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
683 GlobalVariable *SrcGV) {
685 if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
686 return emitError("Linking globals named '" + SrcGV->getName() +
687 "': can only link appending global with another appending global!");
689 ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());
690 ArrayType *SrcTy =
691 cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()));
692 Type *EltTy = DstTy->getElementType();
694 // Check to see that they two arrays agree on type.
695 if (EltTy != SrcTy->getElementType())
696 return emitError("Appending variables with different element types!");
697 if (DstGV->isConstant() != SrcGV->isConstant())
698 return emitError("Appending variables linked with different const'ness!");
700 if (DstGV->getAlignment() != SrcGV->getAlignment())
701 return emitError(
702 "Appending variables with different alignment need to be linked!");
704 if (DstGV->getVisibility() != SrcGV->getVisibility())
705 return emitError(
706 "Appending variables with different visibility need to be linked!");
708 if (DstGV->getSection() != SrcGV->getSection())
709 return emitError(
710 "Appending variables with different section name need to be linked!");
712 uint64_t NewSize = DstTy->getNumElements() + SrcTy->getNumElements();
713 ArrayType *NewType = ArrayType::get(EltTy, NewSize);
715 // Create the new global variable.
716 GlobalVariable *NG =
717 new GlobalVariable(*DstGV->getParent(), NewType, SrcGV->isConstant(),
718 DstGV->getLinkage(), /*init*/0, /*name*/"", DstGV,
719 DstGV->getThreadLocalMode(),
720 DstGV->getType()->getAddressSpace());
722 // Propagate alignment, visibility and section info.
723 copyGVAttributes(NG, DstGV);
725 AppendingVarInfo AVI;
726 AVI.NewGV = NG;
727 AVI.DstInit = DstGV->getInitializer();
728 AVI.SrcInit = SrcGV->getInitializer();
729 AppendingVars.push_back(AVI);
731 // Replace any uses of the two global variables with uses of the new
732 // global.
733 ValueMap[SrcGV] = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));
735 DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
736 DstGV->eraseFromParent();
738 // Track the source variable so we don't try to link it.
739 DoNotLinkFromSource.insert(SrcGV);
741 return false;
742 }
744 /// linkGlobalProto - Loop through the global variables in the src module and
745 /// merge them into the dest module.
746 bool ModuleLinker::linkGlobalProto(GlobalVariable *SGV) {
747 GlobalValue *DGV = getLinkedToGlobal(SGV);
748 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
749 bool HasUnnamedAddr = SGV->hasUnnamedAddr();
751 if (DGV) {
752 // Concatenation of appending linkage variables is magic and handled later.
753 if (DGV->hasAppendingLinkage() || SGV->hasAppendingLinkage())
754 return linkAppendingVarProto(cast<GlobalVariable>(DGV), SGV);
756 // Determine whether linkage of these two globals follows the source
757 // module's definition or the destination module's definition.
758 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
759 HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
760 GlobalValue::VisibilityTypes NV;
761 bool LinkFromSrc = false;
762 if (getLinkageResult(DGV, SGV, NewLinkage, NV, LinkFromSrc))
763 return true;
764 NewVisibility = NV;
766 // If we're not linking from the source, then keep the definition that we
767 // have.
768 if (!LinkFromSrc) {
769 // Special case for const propagation.
770 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV))
771 if (DGVar->isDeclaration() && SGV->isConstant() && !DGVar->isConstant())
772 DGVar->setConstant(true);
774 // Set calculated linkage, visibility and unnamed_addr.
775 DGV->setLinkage(NewLinkage);
776 DGV->setVisibility(*NewVisibility);
777 DGV->setUnnamedAddr(HasUnnamedAddr);
779 // Make sure to remember this mapping.
780 ValueMap[SGV] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGV->getType()));
782 // Track the source global so that we don't attempt to copy it over when
783 // processing global initializers.
784 DoNotLinkFromSource.insert(SGV);
786 return false;
787 }
788 }
790 // No linking to be performed or linking from the source: simply create an
791 // identical version of the symbol over in the dest module... the
792 // initializer will be filled in later by LinkGlobalInits.
793 GlobalVariable *NewDGV =
794 new GlobalVariable(*DstM, TypeMap.get(SGV->getType()->getElementType()),
795 SGV->isConstant(), SGV->getLinkage(), /*init*/0,
796 SGV->getName(), /*insertbefore*/0,
797 SGV->getThreadLocalMode(),
798 SGV->getType()->getAddressSpace());
799 // Propagate alignment, visibility and section info.
800 copyGVAttributes(NewDGV, SGV);
801 if (NewVisibility)
802 NewDGV->setVisibility(*NewVisibility);
803 NewDGV->setUnnamedAddr(HasUnnamedAddr);
805 if (DGV) {
806 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, DGV->getType()));
807 DGV->eraseFromParent();
808 }
810 // Make sure to remember this mapping.
811 ValueMap[SGV] = NewDGV;
812 return false;
813 }
815 /// linkFunctionProto - Link the function in the source module into the
816 /// destination module if needed, setting up mapping information.
817 bool ModuleLinker::linkFunctionProto(Function *SF) {
818 GlobalValue *DGV = getLinkedToGlobal(SF);
819 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
821 if (DGV) {
822 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
823 bool LinkFromSrc = false;
824 GlobalValue::VisibilityTypes NV;
825 if (getLinkageResult(DGV, SF, NewLinkage, NV, LinkFromSrc))
826 return true;
827 NewVisibility = NV;
829 if (!LinkFromSrc) {
830 // Set calculated linkage
831 DGV->setLinkage(NewLinkage);
832 DGV->setVisibility(*NewVisibility);
834 // Make sure to remember this mapping.
835 ValueMap[SF] = ConstantExpr::getBitCast(DGV, TypeMap.get(SF->getType()));
837 // Track the function from the source module so we don't attempt to remap
838 // it.
839 DoNotLinkFromSource.insert(SF);
841 return false;
842 }
843 }
845 // If the function is to be lazily linked, don't create it just yet.
846 // The ValueMaterializerTy will deal with creating it if it's used.
847 if (!DGV && (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() ||
848 SF->hasAvailableExternallyLinkage())) {
849 DoNotLinkFromSource.insert(SF);
850 return false;
851 }
853 // If there is no linkage to be performed or we are linking from the source,
854 // bring SF over.
855 Function *NewDF = Function::Create(TypeMap.get(SF->getFunctionType()),
856 SF->getLinkage(), SF->getName(), DstM);
857 copyGVAttributes(NewDF, SF);
858 if (NewVisibility)
859 NewDF->setVisibility(*NewVisibility);
861 if (DGV) {
862 // Any uses of DF need to change to NewDF, with cast.
863 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, DGV->getType()));
864 DGV->eraseFromParent();
865 }
867 ValueMap[SF] = NewDF;
868 return false;
869 }
871 /// LinkAliasProto - Set up prototypes for any aliases that come over from the
872 /// source module.
873 bool ModuleLinker::linkAliasProto(GlobalAlias *SGA) {
874 GlobalValue *DGV = getLinkedToGlobal(SGA);
875 llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
877 if (DGV) {
878 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
879 GlobalValue::VisibilityTypes NV;
880 bool LinkFromSrc = false;
881 if (getLinkageResult(DGV, SGA, NewLinkage, NV, LinkFromSrc))
882 return true;
883 NewVisibility = NV;
885 if (!LinkFromSrc) {
886 // Set calculated linkage.
887 DGV->setLinkage(NewLinkage);
888 DGV->setVisibility(*NewVisibility);
890 // Make sure to remember this mapping.
891 ValueMap[SGA] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGA->getType()));
893 // Track the alias from the source module so we don't attempt to remap it.
894 DoNotLinkFromSource.insert(SGA);
896 return false;
897 }
898 }
900 // If there is no linkage to be performed or we're linking from the source,
901 // bring over SGA.
902 GlobalAlias *NewDA = new GlobalAlias(TypeMap.get(SGA->getType()),
903 SGA->getLinkage(), SGA->getName(),
904 /*aliasee*/0, DstM);
905 copyGVAttributes(NewDA, SGA);
906 if (NewVisibility)
907 NewDA->setVisibility(*NewVisibility);
909 if (DGV) {
910 // Any uses of DGV need to change to NewDA, with cast.
911 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDA, DGV->getType()));
912 DGV->eraseFromParent();
913 }
915 ValueMap[SGA] = NewDA;
916 return false;
917 }
919 static void getArrayElements(Constant *C, SmallVectorImpl<Constant*> &Dest) {
920 unsigned NumElements = cast<ArrayType>(C->getType())->getNumElements();
922 for (unsigned i = 0; i != NumElements; ++i)
923 Dest.push_back(C->getAggregateElement(i));
924 }
926 void ModuleLinker::linkAppendingVarInit(const AppendingVarInfo &AVI) {
927 // Merge the initializer.
928 SmallVector<Constant*, 16> Elements;
929 getArrayElements(AVI.DstInit, Elements);
931 Constant *SrcInit = MapValue(AVI.SrcInit, ValueMap, RF_None, &TypeMap, &ValMaterializer);
932 getArrayElements(SrcInit, Elements);
934 ArrayType *NewType = cast<ArrayType>(AVI.NewGV->getType()->getElementType());
935 AVI.NewGV->setInitializer(ConstantArray::get(NewType, Elements));
936 }
938 /// linkGlobalInits - Update the initializers in the Dest module now that all
939 /// globals that may be referenced are in Dest.
940 void ModuleLinker::linkGlobalInits() {
941 // Loop over all of the globals in the src module, mapping them over as we go
942 for (Module::const_global_iterator I = SrcM->global_begin(),
943 E = SrcM->global_end(); I != E; ++I) {
945 // Only process initialized GV's or ones not already in dest.
946 if (!I->hasInitializer() || DoNotLinkFromSource.count(I)) continue;
948 // Grab destination global variable.
949 GlobalVariable *DGV = cast<GlobalVariable>(ValueMap[I]);
950 // Figure out what the initializer looks like in the dest module.
951 DGV->setInitializer(MapValue(I->getInitializer(), ValueMap,
952 RF_None, &TypeMap, &ValMaterializer));
953 }
954 }
956 /// linkFunctionBody - Copy the source function over into the dest function and
957 /// fix up references to values. At this point we know that Dest is an external
958 /// function, and that Src is not.
959 void ModuleLinker::linkFunctionBody(Function *Dst, Function *Src) {
960 assert(Src && Dst && Dst->isDeclaration() && !Src->isDeclaration());
962 // Go through and convert function arguments over, remembering the mapping.
963 Function::arg_iterator DI = Dst->arg_begin();
964 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
965 I != E; ++I, ++DI) {
966 DI->setName(I->getName()); // Copy the name over.
968 // Add a mapping to our mapping.
969 ValueMap[I] = DI;
970 }
972 if (Mode == Linker::DestroySource) {
973 // Splice the body of the source function into the dest function.
974 Dst->getBasicBlockList().splice(Dst->end(), Src->getBasicBlockList());
976 // At this point, all of the instructions and values of the function are now
977 // copied over. The only problem is that they are still referencing values in
978 // the Source function as operands. Loop through all of the operands of the
979 // functions and patch them up to point to the local versions.
980 for (Function::iterator BB = Dst->begin(), BE = Dst->end(); BB != BE; ++BB)
981 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
982 RemapInstruction(I, ValueMap, RF_IgnoreMissingEntries,
983 &TypeMap, &ValMaterializer);
985 } else {
986 // Clone the body of the function into the dest function.
987 SmallVector<ReturnInst*, 8> Returns; // Ignore returns.
988 CloneFunctionInto(Dst, Src, ValueMap, false, Returns, "", NULL,
989 &TypeMap, &ValMaterializer);
990 }
992 // There is no need to map the arguments anymore.
993 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end();
994 I != E; ++I)
995 ValueMap.erase(I);
997 }
999 /// linkAliasBodies - Insert all of the aliases in Src into the Dest module.
1000 void ModuleLinker::linkAliasBodies() {
1001 for (Module::alias_iterator I = SrcM->alias_begin(), E = SrcM->alias_end();
1002 I != E; ++I) {
1003 if (DoNotLinkFromSource.count(I))
1004 continue;
1005 if (Constant *Aliasee = I->getAliasee()) {
1006 GlobalAlias *DA = cast<GlobalAlias>(ValueMap[I]);
1007 DA->setAliasee(MapValue(Aliasee, ValueMap, RF_None,
1008 &TypeMap, &ValMaterializer));
1009 }
1010 }
1011 }
1013 /// linkNamedMDNodes - Insert all of the named MDNodes in Src into the Dest
1014 /// module.
1015 void ModuleLinker::linkNamedMDNodes() {
1016 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1017 for (Module::const_named_metadata_iterator I = SrcM->named_metadata_begin(),
1018 E = SrcM->named_metadata_end(); I != E; ++I) {
1019 // Don't link module flags here. Do them separately.
1020 if (&*I == SrcModFlags) continue;
1021 NamedMDNode *DestNMD = DstM->getOrInsertNamedMetadata(I->getName());
1022 // Add Src elements into Dest node.
1023 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1024 DestNMD->addOperand(MapValue(I->getOperand(i), ValueMap,
1025 RF_None, &TypeMap, &ValMaterializer));
1026 }
1027 }
1029 /// linkModuleFlagsMetadata - Merge the linker flags in Src into the Dest
1030 /// module.
1031 bool ModuleLinker::linkModuleFlagsMetadata() {
1032 // If the source module has no module flags, we are done.
1033 const NamedMDNode *SrcModFlags = SrcM->getModuleFlagsMetadata();
1034 if (!SrcModFlags) return false;
1036 // If the destination module doesn't have module flags yet, then just copy
1037 // over the source module's flags.
1038 NamedMDNode *DstModFlags = DstM->getOrInsertModuleFlagsMetadata();
1039 if (DstModFlags->getNumOperands() == 0) {
1040 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I)
1041 DstModFlags->addOperand(SrcModFlags->getOperand(I));
1043 return false;
1044 }
1046 // First build a map of the existing module flags and requirements.
1047 DenseMap<MDString*, MDNode*> Flags;
1048 SmallSetVector<MDNode*, 16> Requirements;
1049 for (unsigned I = 0, E = DstModFlags->getNumOperands(); I != E; ++I) {
1050 MDNode *Op = DstModFlags->getOperand(I);
1051 ConstantInt *Behavior = cast<ConstantInt>(Op->getOperand(0));
1052 MDString *ID = cast<MDString>(Op->getOperand(1));
1054 if (Behavior->getZExtValue() == Module::Require) {
1055 Requirements.insert(cast<MDNode>(Op->getOperand(2)));
1056 } else {
1057 Flags[ID] = Op;
1058 }
1059 }
1061 // Merge in the flags from the source module, and also collect its set of
1062 // requirements.
1063 bool HasErr = false;
1064 for (unsigned I = 0, E = SrcModFlags->getNumOperands(); I != E; ++I) {
1065 MDNode *SrcOp = SrcModFlags->getOperand(I);
1066 ConstantInt *SrcBehavior = cast<ConstantInt>(SrcOp->getOperand(0));
1067 MDString *ID = cast<MDString>(SrcOp->getOperand(1));
1068 MDNode *DstOp = Flags.lookup(ID);
1069 unsigned SrcBehaviorValue = SrcBehavior->getZExtValue();
1071 // If this is a requirement, add it and continue.
1072 if (SrcBehaviorValue == Module::Require) {
1073 // If the destination module does not already have this requirement, add
1074 // it.
1075 if (Requirements.insert(cast<MDNode>(SrcOp->getOperand(2)))) {
1076 DstModFlags->addOperand(SrcOp);
1077 }
1078 continue;
1079 }
1081 // If there is no existing flag with this ID, just add it.
1082 if (!DstOp) {
1083 Flags[ID] = SrcOp;
1084 DstModFlags->addOperand(SrcOp);
1085 continue;
1086 }
1088 // Otherwise, perform a merge.
1089 ConstantInt *DstBehavior = cast<ConstantInt>(DstOp->getOperand(0));
1090 unsigned DstBehaviorValue = DstBehavior->getZExtValue();
1092 // If either flag has override behavior, handle it first.
1093 if (DstBehaviorValue == Module::Override) {
1094 // Diagnose inconsistent flags which both have override behavior.
1095 if (SrcBehaviorValue == Module::Override &&
1096 SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1097 HasErr |= emitError("linking module flags '" + ID->getString() +
1098 "': IDs have conflicting override values");
1099 }
1100 continue;
1101 } else if (SrcBehaviorValue == Module::Override) {
1102 // Update the destination flag to that of the source.
1103 DstOp->replaceOperandWith(0, SrcBehavior);
1104 DstOp->replaceOperandWith(2, SrcOp->getOperand(2));
1105 continue;
1106 }
1108 // Diagnose inconsistent merge behavior types.
1109 if (SrcBehaviorValue != DstBehaviorValue) {
1110 HasErr |= emitError("linking module flags '" + ID->getString() +
1111 "': IDs have conflicting behaviors");
1112 continue;
1113 }
1115 // Perform the merge for standard behavior types.
1116 switch (SrcBehaviorValue) {
1117 case Module::Require:
1118 case Module::Override: assert(0 && "not possible"); break;
1119 case Module::Error: {
1120 // Emit an error if the values differ.
1121 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1122 HasErr |= emitError("linking module flags '" + ID->getString() +
1123 "': IDs have conflicting values");
1124 }
1125 continue;
1126 }
1127 case Module::Warning: {
1128 // Emit a warning if the values differ.
1129 if (SrcOp->getOperand(2) != DstOp->getOperand(2)) {
1130 errs() << "WARNING: linking module flags '" << ID->getString()
1131 << "': IDs have conflicting values";
1132 }
1133 continue;
1134 }
1135 case Module::Append: {
1136 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1137 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1138 unsigned NumOps = DstValue->getNumOperands() + SrcValue->getNumOperands();
1139 Value **VP, **Values = VP = new Value*[NumOps];
1140 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i, ++VP)
1141 *VP = DstValue->getOperand(i);
1142 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i, ++VP)
1143 *VP = SrcValue->getOperand(i);
1144 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1145 ArrayRef<Value*>(Values,
1146 NumOps)));
1147 delete[] Values;
1148 break;
1149 }
1150 case Module::AppendUnique: {
1151 SmallSetVector<Value*, 16> Elts;
1152 MDNode *DstValue = cast<MDNode>(DstOp->getOperand(2));
1153 MDNode *SrcValue = cast<MDNode>(SrcOp->getOperand(2));
1154 for (unsigned i = 0, e = DstValue->getNumOperands(); i != e; ++i)
1155 Elts.insert(DstValue->getOperand(i));
1156 for (unsigned i = 0, e = SrcValue->getNumOperands(); i != e; ++i)
1157 Elts.insert(SrcValue->getOperand(i));
1158 DstOp->replaceOperandWith(2, MDNode::get(DstM->getContext(),
1159 ArrayRef<Value*>(Elts.begin(),
1160 Elts.end())));
1161 break;
1162 }
1163 }
1164 }
1166 // Check all of the requirements.
1167 for (unsigned I = 0, E = Requirements.size(); I != E; ++I) {
1168 MDNode *Requirement = Requirements[I];
1169 MDString *Flag = cast<MDString>(Requirement->getOperand(0));
1170 Value *ReqValue = Requirement->getOperand(1);
1172 MDNode *Op = Flags[Flag];
1173 if (!Op || Op->getOperand(2) != ReqValue) {
1174 HasErr |= emitError("linking module flags '" + Flag->getString() +
1175 "': does not have the required value");
1176 continue;
1177 }
1178 }
1180 return HasErr;
1181 }
1183 bool ModuleLinker::run() {
1184 assert(DstM && "Null destination module");
1185 assert(SrcM && "Null source module");
1187 // Inherit the target data from the source module if the destination module
1188 // doesn't have one already.
1189 if (DstM->getDataLayout().empty() && !SrcM->getDataLayout().empty())
1190 DstM->setDataLayout(SrcM->getDataLayout());
1192 // Copy the target triple from the source to dest if the dest's is empty.
1193 if (DstM->getTargetTriple().empty() && !SrcM->getTargetTriple().empty())
1194 DstM->setTargetTriple(SrcM->getTargetTriple());
1196 if (!SrcM->getDataLayout().empty() && !DstM->getDataLayout().empty() &&
1197 SrcM->getDataLayout() != DstM->getDataLayout())
1198 errs() << "WARNING: Linking two modules of different data layouts!\n";
1199 if (!SrcM->getTargetTriple().empty() &&
1200 DstM->getTargetTriple() != SrcM->getTargetTriple()) {
1201 errs() << "WARNING: Linking two modules of different target triples: ";
1202 if (!SrcM->getModuleIdentifier().empty())
1203 errs() << SrcM->getModuleIdentifier() << ": ";
1204 errs() << "'" << SrcM->getTargetTriple() << "' and '"
1205 << DstM->getTargetTriple() << "'\n";
1206 }
1208 // Append the module inline asm string.
1209 if (!SrcM->getModuleInlineAsm().empty()) {
1210 if (DstM->getModuleInlineAsm().empty())
1211 DstM->setModuleInlineAsm(SrcM->getModuleInlineAsm());
1212 else
1213 DstM->setModuleInlineAsm(DstM->getModuleInlineAsm()+"\n"+
1214 SrcM->getModuleInlineAsm());
1215 }
1217 // Loop over all of the linked values to compute type mappings.
1218 computeTypeMapping();
1220 // Insert all of the globals in src into the DstM module... without linking
1221 // initializers (which could refer to functions not yet mapped over).
1222 for (Module::global_iterator I = SrcM->global_begin(),
1223 E = SrcM->global_end(); I != E; ++I)
1224 if (linkGlobalProto(I))
1225 return true;
1227 // Link the functions together between the two modules, without doing function
1228 // bodies... this just adds external function prototypes to the DstM
1229 // function... We do this so that when we begin processing function bodies,
1230 // all of the global values that may be referenced are available in our
1231 // ValueMap.
1232 for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I)
1233 if (linkFunctionProto(I))
1234 return true;
1236 // If there were any aliases, link them now.
1237 for (Module::alias_iterator I = SrcM->alias_begin(),
1238 E = SrcM->alias_end(); I != E; ++I)
1239 if (linkAliasProto(I))
1240 return true;
1242 for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i)
1243 linkAppendingVarInit(AppendingVars[i]);
1245 // Update the initializers in the DstM module now that all globals that may
1246 // be referenced are in DstM.
1247 linkGlobalInits();
1249 // Link in the function bodies that are defined in the source module into
1250 // DstM.
1251 for (Module::iterator SF = SrcM->begin(), E = SrcM->end(); SF != E; ++SF) {
1252 // Skip if not linking from source.
1253 if (DoNotLinkFromSource.count(SF)) continue;
1255 // Skip if no body (function is external) or materialize.
1256 if (SF->isDeclaration()) {
1257 if (!SF->isMaterializable())
1258 continue;
1259 if (SF->Materialize(&ErrorMsg))
1260 return true;
1261 }
1263 linkFunctionBody(cast<Function>(ValueMap[SF]), SF);
1264 SF->Dematerialize();
1265 }
1267 // Resolve all uses of aliases with aliasees.
1268 linkAliasBodies();
1270 // Remap all of the named MDNodes in Src into the DstM module. We do this
1271 // after linking GlobalValues so that MDNodes that reference GlobalValues
1272 // are properly remapped.
1273 linkNamedMDNodes();
1275 // Merge the module flags into the DstM module.
1276 if (linkModuleFlagsMetadata())
1277 return true;
1279 // Process vector of lazily linked in functions.
1280 bool LinkedInAnyFunctions;
1281 do {
1282 LinkedInAnyFunctions = false;
1284 for(std::vector<Function*>::iterator I = LazilyLinkFunctions.begin(),
1285 E = LazilyLinkFunctions.end(); I != E; ++I) {
1286 Function *SF = *I;
1287 if (!SF)
1288 continue;
1290 Function *DF = cast<Function>(ValueMap[SF]);
1292 // Materialize if necessary.
1293 if (SF->isDeclaration()) {
1294 if (!SF->isMaterializable())
1295 continue;
1296 if (SF->Materialize(&ErrorMsg))
1297 return true;
1298 }
1300 // Erase from vector *before* the function body is linked - linkFunctionBody could
1301 // invalidate I.
1302 LazilyLinkFunctions.erase(I);
1304 // Link in function body.
1305 linkFunctionBody(DF, SF);
1306 SF->Dematerialize();
1308 // Set flag to indicate we may have more functions to lazily link in
1309 // since we linked in a function.
1310 LinkedInAnyFunctions = true;
1311 break;
1312 }
1313 } while (LinkedInAnyFunctions);
1315 // Now that all of the types from the source are used, resolve any structs
1316 // copied over to the dest that didn't exist there.
1317 TypeMap.linkDefinedTypeBodies();
1319 return false;
1320 }
1322 Linker::Linker(Module *M) : Composite(M) {
1323 TypeFinder StructTypes;
1324 StructTypes.run(*M, true);
1325 IdentifiedStructTypes.insert(StructTypes.begin(), StructTypes.end());
1326 }
1328 Linker::~Linker() {
1329 }
1331 bool Linker::linkInModule(Module *Src, unsigned Mode, std::string *ErrorMsg) {
1332 ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src, Mode);
1333 if (TheLinker.run()) {
1334 if (ErrorMsg)
1335 *ErrorMsg = TheLinker.ErrorMsg;
1336 return true;
1337 }
1338 return false;
1339 }
1341 //===----------------------------------------------------------------------===//
1342 // LinkModules entrypoint.
1343 //===----------------------------------------------------------------------===//
1345 /// LinkModules - This function links two modules together, with the resulting
1346 /// Dest module modified to be the composite of the two input modules. If an
1347 /// error occurs, true is returned and ErrorMsg (if not null) is set to indicate
1348 /// the problem. Upon failure, the Dest module could be in a modified state,
1349 /// and shouldn't be relied on to be consistent.
1350 bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Mode,
1351 std::string *ErrorMsg) {
1352 Linker L(Dest);
1353 return L.linkInModule(Src, Mode, ErrorMsg);
1354 }
1356 //===----------------------------------------------------------------------===//
1357 // C API.
1358 //===----------------------------------------------------------------------===//
1360 LLVMBool LLVMLinkModules(LLVMModuleRef Dest, LLVMModuleRef Src,
1361 LLVMLinkerMode Mode, char **OutMessages) {
1362 std::string Messages;
1363 LLVMBool Result = Linker::LinkModules(unwrap(Dest), unwrap(Src),
1364 Mode, OutMessages? &Messages : 0);
1365 if (OutMessages)
1366 *OutMessages = strdup(Messages.c_str());
1367 return Result;
1368 }