llvm/lib/IR/Globals.cpp

   1 //===-- Globals.cpp - Implement the GlobalValue & GlobalVariable class ----===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file implements the GlobalValue & GlobalVariable classes for the IR
  10 // library.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "LLVMContextImpl.h"
  15 #include "llvm/IR/ConstantRange.h"
  16 #include "llvm/IR/Constants.h"
  17 #include "llvm/IR/DerivedTypes.h"
  18 #include "llvm/IR/GlobalAlias.h"
  19 #include "llvm/IR/GlobalValue.h"
  20 #include "llvm/IR/GlobalVariable.h"
  21 #include "llvm/IR/Module.h"
  22 #include "llvm/Support/Error.h"
  23 #include "llvm/Support/ErrorHandling.h"
  24 #include "llvm/Support/MD5.h"
  25 #include "llvm/TargetParser/Triple.h"
  26 using namespace llvm;
  27
  28 //===----------------------------------------------------------------------===//
  29 //                            GlobalValue Class
  30 //===----------------------------------------------------------------------===//
  31
  32 // GlobalValue should be a Constant, plus a type, a module, some flags, and an
  33 // intrinsic ID. Add an assert to prevent people from accidentally growing
  34 // GlobalValue while adding flags.
  35 static_assert(sizeof(GlobalValue) ==
  36                   sizeof(Constant) + 2 * sizeof(void *) + 2 * sizeof(unsigned),
  37               "unexpected GlobalValue size growth");
  38
  39 // GlobalObject adds a comdat.
  40 static_assert(sizeof(GlobalObject) == sizeof(GlobalValue) + sizeof(void *),
  41               "unexpected GlobalObject size growth");
  42
  43 bool GlobalValue::isMaterializable() const {
  44   if (const Function *F = dyn_cast<Function>(this))
  45     return F->isMaterializable();
  46   return false;
  47 }
  48 Error GlobalValue::materialize() { return getParent()->materialize(this); }
  49
  50 /// Override destroyConstantImpl to make sure it doesn't get called on
  51 /// GlobalValue's because they shouldn't be treated like other constants.
  52 void GlobalValue::destroyConstantImpl() {
  53   llvm_unreachable("You can't GV->destroyConstantImpl()!");
  54 }
  55
  56 Value *GlobalValue::handleOperandChangeImpl(Value *From, Value *To) {
  57   llvm_unreachable("Unsupported class for handleOperandChange()!");
  58 }
  59
  60 /// copyAttributesFrom - copy all additional attributes (those not needed to
  61 /// create a GlobalValue) from the GlobalValue Src to this one.
  62 void GlobalValue::copyAttributesFrom(const GlobalValue *Src) {
  63   setVisibility(Src->getVisibility());
  64   setUnnamedAddr(Src->getUnnamedAddr());
  65   setThreadLocalMode(Src->getThreadLocalMode());
  66   setDLLStorageClass(Src->getDLLStorageClass());
  67   setDSOLocal(Src->isDSOLocal());
  68   setPartition(Src->getPartition());
  69   if (Src->hasSanitizerMetadata())
  70     setSanitizerMetadata(Src->getSanitizerMetadata());
  71   else
  72     removeSanitizerMetadata();
  73 }
  74
  75 GlobalValue::GUID GlobalValue::getGUID(StringRef GlobalName) {
  76   return MD5Hash(GlobalName);
  77 }
  78
  79 void GlobalValue::removeFromParent() {
  80   switch (getValueID()) {
  81 #define HANDLE_GLOBAL_VALUE(NAME)                                              \
  82   case Value::NAME##Val:                                                       \
  83     return static_cast<NAME *>(this)->removeFromParent();
  84 #include "llvm/IR/Value.def"
  85   default:
  86     break;
  87   }
  88   llvm_unreachable("not a global");
  89 }
  90
  91 void GlobalValue::eraseFromParent() {
  92   switch (getValueID()) {
  93 #define HANDLE_GLOBAL_VALUE(NAME)                                              \
  94   case Value::NAME##Val:                                                       \
  95     return static_cast<NAME *>(this)->eraseFromParent();
  96 #include "llvm/IR/Value.def"
  97   default:
  98     break;
  99   }
 100   llvm_unreachable("not a global");
 101 }
 102
 103 GlobalObject::~GlobalObject() { setComdat(nullptr); }
 104
 105 bool GlobalValue::isInterposable() const {
 106   if (isInterposableLinkage(getLinkage()))
 107     return true;
 108   return getParent() && getParent()->getSemanticInterposition() &&
 109          !isDSOLocal();
 110 }
 111
 112 bool GlobalValue::canBenefitFromLocalAlias() const {
 113   if (isTagged()) {
 114     // Cannot create local aliases to MTE tagged globals. The address of a
 115     // tagged global includes a tag that is assigned by the loader in the
 116     // GOT.
 117     return false;
 118   }
 119   // See AsmPrinter::getSymbolPreferLocal(). For a deduplicate comdat kind,
 120   // references to a discarded local symbol from outside the group are not
 121   // allowed, so avoid the local alias.
 122   auto isDeduplicateComdat = [](const Comdat *C) {
 123     return C && C->getSelectionKind() != Comdat::NoDeduplicate;
 124   };
 125   return hasDefaultVisibility() &&
 126          GlobalObject::isExternalLinkage(getLinkage()) && !isDeclaration() &&
 127          !isa<GlobalIFunc>(this) && !isDeduplicateComdat(getComdat());
 128 }
 129
 130 const DataLayout &GlobalValue::getDataLayout() const {
 131   return getParent()->getDataLayout();
 132 }
 133
 134 void GlobalObject::setAlignment(MaybeAlign Align) {
 135   assert((!Align || *Align <= MaximumAlignment) &&
 136          "Alignment is greater than MaximumAlignment!");
 137   unsigned AlignmentData = encode(Align);
 138   unsigned OldData = getGlobalValueSubClassData();
 139   setGlobalValueSubClassData((OldData & ~AlignmentMask) | AlignmentData);
 140   assert(getAlign() == Align && "Alignment representation error!");
 141 }
 142
 143 void GlobalObject::setAlignment(Align Align) {
 144   assert(Align <= MaximumAlignment &&
 145          "Alignment is greater than MaximumAlignment!");
 146   unsigned AlignmentData = encode(Align);
 147   unsigned OldData = getGlobalValueSubClassData();
 148   setGlobalValueSubClassData((OldData & ~AlignmentMask) | AlignmentData);
 149   assert(getAlign() && *getAlign() == Align &&
 150          "Alignment representation error!");
 151 }
 152
 153 void GlobalObject::copyAttributesFrom(const GlobalObject *Src) {
 154   GlobalValue::copyAttributesFrom(Src);
 155   setAlignment(Src->getAlign());
 156   setSection(Src->getSection());
 157 }
 158
 159 std::string GlobalValue::getGlobalIdentifier(StringRef Name,
 160                                              GlobalValue::LinkageTypes Linkage,
 161                                              StringRef FileName) {
 162   // Value names may be prefixed with a binary '1' to indicate
 163   // that the backend should not modify the symbols due to any platform
 164   // naming convention. Do not include that '1' in the PGO profile name.
 165   Name.consume_front("\1");
 166
 167   std::string GlobalName;
 168   if (llvm::GlobalValue::isLocalLinkage(Linkage)) {
 169     // For local symbols, prepend the main file name to distinguish them.
 170     // Do not include the full path in the file name since there's no guarantee
 171     // that it will stay the same, e.g., if the files are checked out from
 172     // version control in different locations.
 173     if (FileName.empty())
 174       GlobalName += "<unknown>";
 175     else
 176       GlobalName += FileName;
 177
 178     GlobalName += GlobalIdentifierDelimiter;
 179   }
 180   GlobalName += Name;
 181   return GlobalName;
 182 }
 183
 184 std::string GlobalValue::getGlobalIdentifier() const {
 185   return getGlobalIdentifier(getName(), getLinkage(),
 186                              getParent()->getSourceFileName());
 187 }
 188
 189 StringRef GlobalValue::getSection() const {
 190   if (auto *GA = dyn_cast<GlobalAlias>(this)) {
 191     // In general we cannot compute this at the IR level, but we try.
 192     if (const GlobalObject *GO = GA->getAliaseeObject())
 193       return GO->getSection();
 194     return "";
 195   }
 196   return cast<GlobalObject>(this)->getSection();
 197 }
 198
 199 const Comdat *GlobalValue::getComdat() const {
 200   if (auto *GA = dyn_cast<GlobalAlias>(this)) {
 201     // In general we cannot compute this at the IR level, but we try.
 202     if (const GlobalObject *GO = GA->getAliaseeObject())
 203       return const_cast<GlobalObject *>(GO)->getComdat();
 204     return nullptr;
 205   }
 206   // ifunc and its resolver are separate things so don't use resolver comdat.
 207   if (isa<GlobalIFunc>(this))
 208     return nullptr;
 209   return cast<GlobalObject>(this)->getComdat();
 210 }
 211
 212 void GlobalObject::setComdat(Comdat *C) {
 213   if (ObjComdat)
 214     ObjComdat->removeUser(this);
 215   ObjComdat = C;
 216   if (C)
 217     C->addUser(this);
 218 }
 219
 220 StringRef GlobalValue::getPartition() const {
 221   if (!hasPartition())
 222     return "";
 223   return getContext().pImpl->GlobalValuePartitions[this];
 224 }
 225
 226 void GlobalValue::setPartition(StringRef S) {
 227   // Do nothing if we're clearing the partition and it is already empty.
 228   if (!hasPartition() && S.empty())
 229     return;
 230
 231   // Get or create a stable partition name string and put it in the table in the
 232   // context.
 233   if (!S.empty())
 234     S = getContext().pImpl->Saver.save(S);
 235   getContext().pImpl->GlobalValuePartitions[this] = S;
 236
 237   // Update the HasPartition field. Setting the partition to the empty string
 238   // means this global no longer has a partition.
 239   HasPartition = !S.empty();
 240 }
 241
 242 using SanitizerMetadata = GlobalValue::SanitizerMetadata;
 243 const SanitizerMetadata &GlobalValue::getSanitizerMetadata() const {
 244   assert(hasSanitizerMetadata());
 245   assert(getContext().pImpl->GlobalValueSanitizerMetadata.count(this));
 246   return getContext().pImpl->GlobalValueSanitizerMetadata[this];
 247 }
 248
 249 void GlobalValue::setSanitizerMetadata(SanitizerMetadata Meta) {
 250   getContext().pImpl->GlobalValueSanitizerMetadata[this] = Meta;
 251   HasSanitizerMetadata = true;
 252 }
 253
 254 void GlobalValue::removeSanitizerMetadata() {
 255   DenseMap<const GlobalValue *, SanitizerMetadata> &MetadataMap =
 256       getContext().pImpl->GlobalValueSanitizerMetadata;
 257   MetadataMap.erase(this);
 258   HasSanitizerMetadata = false;
 259 }
 260
 261 void GlobalValue::setNoSanitizeMetadata() {
 262   SanitizerMetadata Meta;
 263   Meta.NoAddress = true;
 264   Meta.NoHWAddress = true;
 265   setSanitizerMetadata(Meta);
 266 }
 267
 268 StringRef GlobalObject::getSectionImpl() const {
 269   assert(hasSection());
 270   return getContext().pImpl->GlobalObjectSections[this];
 271 }
 272
 273 void GlobalObject::setSection(StringRef S) {
 274   // Do nothing if we're clearing the section and it is already empty.
 275   if (!hasSection() && S.empty())
 276     return;
 277
 278   // Get or create a stable section name string and put it in the table in the
 279   // context.
 280   if (!S.empty())
 281     S = getContext().pImpl->Saver.save(S);
 282   getContext().pImpl->GlobalObjectSections[this] = S;
 283
 284   // Update the HasSectionHashEntryBit. Setting the section to the empty string
 285   // means this global no longer has a section.
 286   setGlobalObjectFlag(HasSectionHashEntryBit, !S.empty());
 287 }
 288
 289 bool GlobalValue::isNobuiltinFnDef() const {
 290   const Function *F = dyn_cast<Function>(this);
 291   if (!F || F->empty())
 292     return false;
 293   return F->hasFnAttribute(Attribute::NoBuiltin);
 294 }
 295
 296 bool GlobalValue::isDeclaration() const {
 297   // Globals are definitions if they have an initializer.
 298   if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(this))
 299     return GV->getNumOperands() == 0;
 300
 301   // Functions are definitions if they have a body.
 302   if (const Function *F = dyn_cast<Function>(this))
 303     return F->empty() && !F->isMaterializable();
 304
 305   // Aliases and ifuncs are always definitions.
 306   assert(isa<GlobalAlias>(this) || isa<GlobalIFunc>(this));
 307   return false;
 308 }
 309
 310 bool GlobalObject::canIncreaseAlignment() const {
 311   // Firstly, can only increase the alignment of a global if it
 312   // is a strong definition.
 313   if (!isStrongDefinitionForLinker())
 314     return false;
 315
 316   // It also has to either not have a section defined, or, not have
 317   // alignment specified. (If it is assigned a section, the global
 318   // could be densely packed with other objects in the section, and
 319   // increasing the alignment could cause padding issues.)
 320   if (hasSection() && getAlign())
 321     return false;
 322
 323   // On ELF platforms, we're further restricted in that we can't
 324   // increase the alignment of any variable which might be emitted
 325   // into a shared library, and which is exported. If the main
 326   // executable accesses a variable found in a shared-lib, the main
 327   // exe actually allocates memory for and exports the symbol ITSELF,
 328   // overriding the symbol found in the library. That is, at link
 329   // time, the observed alignment of the variable is copied into the
 330   // executable binary. (A COPY relocation is also generated, to copy
 331   // the initial data from the shadowed variable in the shared-lib
 332   // into the location in the main binary, before running code.)
 333   //
 334   // And thus, even though you might think you are defining the
 335   // global, and allocating the memory for the global in your object
 336   // file, and thus should be able to set the alignment arbitrarily,
 337   // that's not actually true. Doing so can cause an ABI breakage; an
 338   // executable might have already been built with the previous
 339   // alignment of the variable, and then assuming an increased
 340   // alignment will be incorrect.
 341
 342   // Conservatively assume ELF if there's no parent pointer.
 343   bool isELF =
 344       (!Parent || Triple(Parent->getTargetTriple()).isOSBinFormatELF());
 345   if (isELF && !isDSOLocal())
 346     return false;
 347
 348   // GV with toc-data attribute is defined in a TOC entry. To mitigate TOC
 349   // overflow, the alignment of such symbol should not be increased. Otherwise,
 350   // padding is needed thus more TOC entries are wasted.
 351   bool isXCOFF =
 352       (!Parent || Triple(Parent->getTargetTriple()).isOSBinFormatXCOFF());
 353   if (isXCOFF)
 354     if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(this))
 355       if (GV->hasAttribute("toc-data"))
 356         return false;
 357
 358   return true;
 359 }
 360
 361 template <typename Operation>
 362 static const GlobalObject *
 363 findBaseObject(const Constant *C, DenseSet<const GlobalAlias *> &Aliases,
 364                const Operation &Op) {
 365   if (auto *GO = dyn_cast<GlobalObject>(C)) {
 366     Op(*GO);
 367     return GO;
 368   }
 369   if (auto *GA = dyn_cast<GlobalAlias>(C)) {
 370     Op(*GA);
 371     if (Aliases.insert(GA).second)
 372       return findBaseObject(GA->getOperand(0), Aliases, Op);
 373   }
 374   if (auto *CE = dyn_cast<ConstantExpr>(C)) {
 375     switch (CE->getOpcode()) {
 376     case Instruction::Add: {
 377       auto *LHS = findBaseObject(CE->getOperand(0), Aliases, Op);
 378       auto *RHS = findBaseObject(CE->getOperand(1), Aliases, Op);
 379       if (LHS && RHS)
 380         return nullptr;
 381       return LHS ? LHS : RHS;
 382     }
 383     case Instruction::Sub: {
 384       if (findBaseObject(CE->getOperand(1), Aliases, Op))
 385         return nullptr;
 386       return findBaseObject(CE->getOperand(0), Aliases, Op);
 387     }
 388     case Instruction::IntToPtr:
 389     case Instruction::PtrToInt:
 390     case Instruction::BitCast:
 391     case Instruction::GetElementPtr:
 392       return findBaseObject(CE->getOperand(0), Aliases, Op);
 393     default:
 394       break;
 395     }
 396   }
 397   return nullptr;
 398 }
 399
 400 const GlobalObject *GlobalValue::getAliaseeObject() const {
 401   DenseSet<const GlobalAlias *> Aliases;
 402   return findBaseObject(this, Aliases, [](const GlobalValue &) {});
 403 }
 404
 405 bool GlobalValue::isAbsoluteSymbolRef() const {
 406   auto *GO = dyn_cast<GlobalObject>(this);
 407   if (!GO)
 408     return false;
 409
 410   return GO->getMetadata(LLVMContext::MD_absolute_symbol);
 411 }
 412
 413 std::optional<ConstantRange> GlobalValue::getAbsoluteSymbolRange() const {
 414   auto *GO = dyn_cast<GlobalObject>(this);
 415   if (!GO)
 416     return std::nullopt;
 417
 418   MDNode *MD = GO->getMetadata(LLVMContext::MD_absolute_symbol);
 419   if (!MD)
 420     return std::nullopt;
 421
 422   return getConstantRangeFromMetadata(*MD);
 423 }
 424
 425 bool GlobalValue::canBeOmittedFromSymbolTable() const {
 426   if (!hasLinkOnceODRLinkage())
 427     return false;
 428
 429   // We assume that anyone who sets global unnamed_addr on a non-constant
 430   // knows what they're doing.
 431   if (hasGlobalUnnamedAddr())
 432     return true;
 433
 434   // If it is a non constant variable, it needs to be uniqued across shared
 435   // objects.
 436   if (auto *Var = dyn_cast<GlobalVariable>(this))
 437     if (!Var->isConstant())
 438       return false;
 439
 440   return hasAtLeastLocalUnnamedAddr();
 441 }
 442
 443 //===----------------------------------------------------------------------===//
 444 // GlobalVariable Implementation
 445 //===----------------------------------------------------------------------===//
 446
 447 GlobalVariable::GlobalVariable(Type *Ty, bool constant, LinkageTypes Link,
 448                                Constant *InitVal, const Twine &Name,
 449                                ThreadLocalMode TLMode, unsigned AddressSpace,
 450                                bool isExternallyInitialized)
 451     : GlobalObject(Ty, Value::GlobalVariableVal, AllocMarker, Link, Name,
 452                    AddressSpace),
 453       isConstantGlobal(constant),
 454       isExternallyInitializedConstant(isExternallyInitialized) {
 455   assert(!Ty->isFunctionTy() && PointerType::isValidElementType(Ty) &&
 456          "invalid type for global variable");
 457   setThreadLocalMode(TLMode);
 458   if (InitVal) {
 459     assert(InitVal->getType() == Ty &&
 460            "Initializer should be the same type as the GlobalVariable!");
 461     Op<0>() = InitVal;
 462   } else {
 463     setGlobalVariableNumOperands(0);
 464   }
 465 }
 466
 467 GlobalVariable::GlobalVariable(Module &M, Type *Ty, bool constant,
 468                                LinkageTypes Link, Constant *InitVal,
 469                                const Twine &Name, GlobalVariable *Before,
 470                                ThreadLocalMode TLMode,
 471                                std::optional<unsigned> AddressSpace,
 472                                bool isExternallyInitialized)
 473     : GlobalVariable(Ty, constant, Link, InitVal, Name, TLMode,
 474                      AddressSpace
 475                          ? *AddressSpace
 476                          : M.getDataLayout().getDefaultGlobalsAddressSpace(),
 477                      isExternallyInitialized) {
 478   if (Before)
 479     Before->getParent()->insertGlobalVariable(Before->getIterator(), this);
 480   else
 481     M.insertGlobalVariable(this);
 482 }
 483
 484 void GlobalVariable::removeFromParent() {
 485   getParent()->removeGlobalVariable(this);
 486 }
 487
 488 void GlobalVariable::eraseFromParent() {
 489   getParent()->eraseGlobalVariable(this);
 490 }
 491
 492 void GlobalVariable::setInitializer(Constant *InitVal) {
 493   if (!InitVal) {
 494     if (hasInitializer()) {
 495       // Note, the num operands is used to compute the offset of the operand, so
 496       // the order here matters.  Clearing the operand then clearing the num
 497       // operands ensures we have the correct offset to the operand.
 498       Op<0>().set(nullptr);
 499       setGlobalVariableNumOperands(0);
 500     }
 501   } else {
 502     assert(InitVal->getType() == getValueType() &&
 503            "Initializer type must match GlobalVariable type");
 504     // Note, the num operands is used to compute the offset of the operand, so
 505     // the order here matters.  We need to set num operands to 1 first so that
 506     // we get the correct offset to the first operand when we set it.
 507     if (!hasInitializer())
 508       setGlobalVariableNumOperands(1);
 509     Op<0>().set(InitVal);
 510   }
 511 }
 512
 513 void GlobalVariable::replaceInitializer(Constant *InitVal) {
 514   assert(InitVal && "Can't compute type of null initializer");
 515   ValueType = InitVal->getType();
 516   setInitializer(InitVal);
 517 }
 518
 519 /// Copy all additional attributes (those not needed to create a GlobalVariable)
 520 /// from the GlobalVariable Src to this one.
 521 void GlobalVariable::copyAttributesFrom(const GlobalVariable *Src) {
 522   GlobalObject::copyAttributesFrom(Src);
 523   setExternallyInitialized(Src->isExternallyInitialized());
 524   setAttributes(Src->getAttributes());
 525   if (auto CM = Src->getCodeModel())
 526     setCodeModel(*CM);
 527 }
 528
 529 void GlobalVariable::dropAllReferences() {
 530   User::dropAllReferences();
 531   clearMetadata();
 532 }
 533
 534 void GlobalVariable::setCodeModel(CodeModel::Model CM) {
 535   unsigned CodeModelData = static_cast<unsigned>(CM) + 1;
 536   unsigned OldData = getGlobalValueSubClassData();
 537   unsigned NewData = (OldData & ~(CodeModelMask << CodeModelShift)) |
 538                      (CodeModelData << CodeModelShift);
 539   setGlobalValueSubClassData(NewData);
 540   assert(getCodeModel() == CM && "Code model representation error!");
 541 }
 542
 543 //===----------------------------------------------------------------------===//
 544 // GlobalAlias Implementation
 545 //===----------------------------------------------------------------------===//
 546
 547 GlobalAlias::GlobalAlias(Type *Ty, unsigned AddressSpace, LinkageTypes Link,
 548                          const Twine &Name, Constant *Aliasee,
 549                          Module *ParentModule)
 550     : GlobalValue(Ty, Value::GlobalAliasVal, AllocMarker, Link, Name,
 551                   AddressSpace) {
 552   setAliasee(Aliasee);
 553   if (ParentModule)
 554     ParentModule->insertAlias(this);
 555 }
 556
 557 GlobalAlias *GlobalAlias::create(Type *Ty, unsigned AddressSpace,
 558                                  LinkageTypes Link, const Twine &Name,
 559                                  Constant *Aliasee, Module *ParentModule) {
 560   return new GlobalAlias(Ty, AddressSpace, Link, Name, Aliasee, ParentModule);
 561 }
 562
 563 GlobalAlias *GlobalAlias::create(Type *Ty, unsigned AddressSpace,
 564                                  LinkageTypes Linkage, const Twine &Name,
 565                                  Module *Parent) {
 566   return create(Ty, AddressSpace, Linkage, Name, nullptr, Parent);
 567 }
 568
 569 GlobalAlias *GlobalAlias::create(Type *Ty, unsigned AddressSpace,
 570                                  LinkageTypes Linkage, const Twine &Name,
 571                                  GlobalValue *Aliasee) {
 572   return create(Ty, AddressSpace, Linkage, Name, Aliasee, Aliasee->getParent());
 573 }
 574
 575 GlobalAlias *GlobalAlias::create(LinkageTypes Link, const Twine &Name,
 576                                  GlobalValue *Aliasee) {
 577   return create(Aliasee->getValueType(), Aliasee->getAddressSpace(), Link, Name,
 578                 Aliasee);
 579 }
 580
 581 GlobalAlias *GlobalAlias::create(const Twine &Name, GlobalValue *Aliasee) {
 582   return create(Aliasee->getLinkage(), Name, Aliasee);
 583 }
 584
 585 void GlobalAlias::removeFromParent() { getParent()->removeAlias(this); }
 586
 587 void GlobalAlias::eraseFromParent() { getParent()->eraseAlias(this); }
 588
 589 void GlobalAlias::setAliasee(Constant *Aliasee) {
 590   assert((!Aliasee || Aliasee->getType() == getType()) &&
 591          "Alias and aliasee types should match!");
 592   Op<0>().set(Aliasee);
 593 }
 594
 595 const GlobalObject *GlobalAlias::getAliaseeObject() const {
 596   DenseSet<const GlobalAlias *> Aliases;
 597   return findBaseObject(getOperand(0), Aliases, [](const GlobalValue &) {});
 598 }
 599
 600 //===----------------------------------------------------------------------===//
 601 // GlobalIFunc Implementation
 602 //===----------------------------------------------------------------------===//
 603
 604 GlobalIFunc::GlobalIFunc(Type *Ty, unsigned AddressSpace, LinkageTypes Link,
 605                          const Twine &Name, Constant *Resolver,
 606                          Module *ParentModule)
 607     : GlobalObject(Ty, Value::GlobalIFuncVal, AllocMarker, Link, Name,
 608                    AddressSpace) {
 609   setResolver(Resolver);
 610   if (ParentModule)
 611     ParentModule->insertIFunc(this);
 612 }
 613
 614 GlobalIFunc *GlobalIFunc::create(Type *Ty, unsigned AddressSpace,
 615                                  LinkageTypes Link, const Twine &Name,
 616                                  Constant *Resolver, Module *ParentModule) {
 617   return new GlobalIFunc(Ty, AddressSpace, Link, Name, Resolver, ParentModule);
 618 }
 619
 620 void GlobalIFunc::removeFromParent() { getParent()->removeIFunc(this); }
 621
 622 void GlobalIFunc::eraseFromParent() { getParent()->eraseIFunc(this); }
 623
 624 const Function *GlobalIFunc::getResolverFunction() const {
 625   return dyn_cast<Function>(getResolver()->stripPointerCastsAndAliases());
 626 }
 627
 628 void GlobalIFunc::applyAlongResolverPath(
 629     function_ref<void(const GlobalValue &)> Op) const {
 630   DenseSet<const GlobalAlias *> Aliases;
 631   findBaseObject(getResolver(), Aliases, Op);
 632 }