src/llvm/lib/IR/Globals.cpp

   1 //===-- Globals.cpp - Implement the GlobalValue & GlobalVariable class ----===//
   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 GlobalValue & GlobalVariable classes for the IR
  11 // library.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "llvm/IR/GlobalValue.h"
  16 #include "llvm/ADT/SmallPtrSet.h"
  17 #include "llvm/IR/Constants.h"
  18 #include "llvm/IR/DerivedTypes.h"
  19 #include "llvm/IR/GlobalAlias.h"
  20 #include "llvm/IR/GlobalVariable.h"
  21 #include "llvm/IR/Module.h"
  22 #include "llvm/IR/Operator.h"
  23 #include "llvm/Support/ErrorHandling.h"
  24 using namespace llvm;
  25
  26 //===----------------------------------------------------------------------===//
  27 //                            GlobalValue Class
  28 //===----------------------------------------------------------------------===//
  29
  30 bool GlobalValue::isMaterializable() const {
  31   if (const Function *F = dyn_cast<Function>(this))
  32     return F->isMaterializable();
  33   return false;
  34 }
  35 bool GlobalValue::isDematerializable() const {
  36   return getParent() && getParent()->isDematerializable(this);
  37 }
  38 std::error_code GlobalValue::materialize() {
  39   return getParent()->materialize(this);
  40 }
  41 void GlobalValue::Dematerialize() {
  42   getParent()->Dematerialize(this);
  43 }
  44
  45 const DataLayout *GlobalValue::getDataLayout() const {
  46   return getParent()->getDataLayout();
  47 }
  48
  49 /// Override destroyConstant to make sure it doesn't get called on
  50 /// GlobalValue's because they shouldn't be treated like other constants.
  51 void GlobalValue::destroyConstant() {
  52   llvm_unreachable("You can't GV->destroyConstant()!");
  53 }
  54
  55 /// copyAttributesFrom - copy all additional attributes (those not needed to
  56 /// create a GlobalValue) from the GlobalValue Src to this one.
  57 void GlobalValue::copyAttributesFrom(const GlobalValue *Src) {
  58   setVisibility(Src->getVisibility());
  59   setUnnamedAddr(Src->hasUnnamedAddr());
  60   setDLLStorageClass(Src->getDLLStorageClass());
  61 }
  62
  63 unsigned GlobalValue::getAlignment() const {
  64   if (auto *GA = dyn_cast<GlobalAlias>(this)) {
  65     // In general we cannot compute this at the IR level, but we try.
  66     if (const GlobalObject *GO = GA->getBaseObject())
  67       return GO->getAlignment();
  68
  69     // FIXME: we should also be able to handle:
  70     // Alias = Global + Offset
  71     // Alias = Absolute
  72     return 0;
  73   }
  74   return cast<GlobalObject>(this)->getAlignment();
  75 }
  76
  77 void GlobalObject::setAlignment(unsigned Align) {
  78   assert((Align & (Align-1)) == 0 && "Alignment is not a power of 2!");
  79   assert(Align <= MaximumAlignment &&
  80          "Alignment is greater than MaximumAlignment!");
  81   unsigned AlignmentData = Log2_32(Align) + 1;
  82   unsigned OldData = getGlobalValueSubClassData();
  83   setGlobalValueSubClassData((OldData & ~AlignmentMask) | AlignmentData);
  84   assert(getAlignment() == Align && "Alignment representation error!");
  85 }
  86
  87 unsigned GlobalObject::getGlobalObjectSubClassData() const {
  88   unsigned ValueData = getGlobalValueSubClassData();
  89   return ValueData >> AlignmentBits;
  90 }
  91
  92 void GlobalObject::setGlobalObjectSubClassData(unsigned Val) {
  93   unsigned OldData = getGlobalValueSubClassData();
  94   setGlobalValueSubClassData((OldData & AlignmentMask) |
  95                              (Val << AlignmentBits));
  96   assert(getGlobalObjectSubClassData() == Val && "representation error");
  97 }
  98
  99 void GlobalObject::copyAttributesFrom(const GlobalValue *Src) {
 100   const auto *GV = cast<GlobalObject>(Src);
 101   GlobalValue::copyAttributesFrom(GV);
 102   setAlignment(GV->getAlignment());
 103   setSection(GV->getSection());
 104 }
 105
 106 const char *GlobalValue::getSection() const {
 107   if (auto *GA = dyn_cast<GlobalAlias>(this)) {
 108     // In general we cannot compute this at the IR level, but we try.
 109     if (const GlobalObject *GO = GA->getBaseObject())
 110       return GO->getSection();
 111     return "";
 112   }
 113   return cast<GlobalObject>(this)->getSection();
 114 }
 115
 116 Comdat *GlobalValue::getComdat() {
 117   if (auto *GA = dyn_cast<GlobalAlias>(this)) {
 118     // In general we cannot compute this at the IR level, but we try.
 119     if (const GlobalObject *GO = GA->getBaseObject())
 120       return const_cast<GlobalObject *>(GO)->getComdat();
 121     return nullptr;
 122   }
 123   return cast<GlobalObject>(this)->getComdat();
 124 }
 125
 126 void GlobalObject::setSection(StringRef S) { Section = S; }
 127
 128 bool GlobalValue::isDeclaration() const {
 129   // Globals are definitions if they have an initializer.
 130   if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(this))
 131     return GV->getNumOperands() == 0;
 132
 133   // Functions are definitions if they have a body.
 134   if (const Function *F = dyn_cast<Function>(this))
 135     return F->empty() && !F->isMaterializable();
 136
 137   // Aliases are always definitions.
 138   assert(isa<GlobalAlias>(this));
 139   return false;
 140 }
 141
 142 //===----------------------------------------------------------------------===//
 143 // GlobalVariable Implementation
 144 //===----------------------------------------------------------------------===//
 145
 146 GlobalVariable::GlobalVariable(Type *Ty, bool constant, LinkageTypes Link,
 147                                Constant *InitVal, const Twine &Name,
 148                                ThreadLocalMode TLMode, unsigned AddressSpace,
 149                                bool isExternallyInitialized)
 150     : GlobalObject(PointerType::get(Ty, AddressSpace), Value::GlobalVariableVal,
 151                    OperandTraits<GlobalVariable>::op_begin(this),
 152                    InitVal != nullptr, Link, Name),
 153       isConstantGlobal(constant),
 154       isExternallyInitializedConstant(isExternallyInitialized) {
 155   setThreadLocalMode(TLMode);
 156   if (InitVal) {
 157     assert(InitVal->getType() == Ty &&
 158            "Initializer should be the same type as the GlobalVariable!");
 159     Op<0>() = InitVal;
 160   }
 161 }
 162
 163 GlobalVariable::GlobalVariable(Module &M, Type *Ty, bool constant,
 164                                LinkageTypes Link, Constant *InitVal,
 165                                const Twine &Name, GlobalVariable *Before,
 166                                ThreadLocalMode TLMode, unsigned AddressSpace,
 167                                bool isExternallyInitialized)
 168     : GlobalObject(PointerType::get(Ty, AddressSpace), Value::GlobalVariableVal,
 169                    OperandTraits<GlobalVariable>::op_begin(this),
 170                    InitVal != nullptr, Link, Name),
 171       isConstantGlobal(constant),
 172       isExternallyInitializedConstant(isExternallyInitialized) {
 173   setThreadLocalMode(TLMode);
 174   if (InitVal) {
 175     assert(InitVal->getType() == Ty &&
 176            "Initializer should be the same type as the GlobalVariable!");
 177     Op<0>() = InitVal;
 178   }
 179
 180   if (Before)
 181     Before->getParent()->getGlobalList().insert(Before, this);
 182   else
 183     M.getGlobalList().push_back(this);
 184 }
 185
 186 void GlobalVariable::setParent(Module *parent) {
 187   Parent = parent;
 188 }
 189
 190 void GlobalVariable::removeFromParent() {
 191   getParent()->getGlobalList().remove(this);
 192 }
 193
 194 void GlobalVariable::eraseFromParent() {
 195   getParent()->getGlobalList().erase(this);
 196 }
 197
 198 void GlobalVariable::replaceUsesOfWithOnConstant(Value *From, Value *To,
 199                                                  Use *U) {
 200   // If you call this, then you better know this GVar has a constant
 201   // initializer worth replacing. Enforce that here.
 202   assert(getNumOperands() == 1 &&
 203          "Attempt to replace uses of Constants on a GVar with no initializer");
 204
 205   // And, since you know it has an initializer, the From value better be
 206   // the initializer :)
 207   assert(getOperand(0) == From &&
 208          "Attempt to replace wrong constant initializer in GVar");
 209
 210   // And, you better have a constant for the replacement value
 211   assert(isa<Constant>(To) &&
 212          "Attempt to replace GVar initializer with non-constant");
 213
 214   // Okay, preconditions out of the way, replace the constant initializer.
 215   this->setOperand(0, cast<Constant>(To));
 216 }
 217
 218 void GlobalVariable::setInitializer(Constant *InitVal) {
 219   if (!InitVal) {
 220     if (hasInitializer()) {
 221       Op<0>().set(nullptr);
 222       NumOperands = 0;
 223     }
 224   } else {
 225     assert(InitVal->getType() == getType()->getElementType() &&
 226            "Initializer type must match GlobalVariable type");
 227     if (!hasInitializer())
 228       NumOperands = 1;
 229     Op<0>().set(InitVal);
 230   }
 231 }
 232
 233 /// copyAttributesFrom - copy all additional attributes (those not needed to
 234 /// create a GlobalVariable) from the GlobalVariable Src to this one.
 235 void GlobalVariable::copyAttributesFrom(const GlobalValue *Src) {
 236   assert(isa<GlobalVariable>(Src) && "Expected a GlobalVariable!");
 237   GlobalObject::copyAttributesFrom(Src);
 238   const GlobalVariable *SrcVar = cast<GlobalVariable>(Src);
 239   setThreadLocalMode(SrcVar->getThreadLocalMode());
 240   setExternallyInitialized(SrcVar->isExternallyInitialized());
 241 }
 242
 243
 244 //===----------------------------------------------------------------------===//
 245 // GlobalAlias Implementation
 246 //===----------------------------------------------------------------------===//
 247
 248 GlobalAlias::GlobalAlias(Type *Ty, unsigned AddressSpace, LinkageTypes Link,
 249                          const Twine &Name, Constant *Aliasee,
 250                          Module *ParentModule)
 251     : GlobalValue(PointerType::get(Ty, AddressSpace), Value::GlobalAliasVal,
 252                   &Op<0>(), 1, Link, Name) {
 253   Op<0>() = Aliasee;
 254
 255   if (ParentModule)
 256     ParentModule->getAliasList().push_back(this);
 257 }
 258
 259 GlobalAlias *GlobalAlias::create(Type *Ty, unsigned AddressSpace,
 260                                  LinkageTypes Link, const Twine &Name,
 261                                  Constant *Aliasee, Module *ParentModule) {
 262   return new GlobalAlias(Ty, AddressSpace, Link, Name, Aliasee, ParentModule);
 263 }
 264
 265 GlobalAlias *GlobalAlias::create(Type *Ty, unsigned AddressSpace,
 266                                  LinkageTypes Linkage, const Twine &Name,
 267                                  Module *Parent) {
 268   return create(Ty, AddressSpace, Linkage, Name, nullptr, Parent);
 269 }
 270
 271 GlobalAlias *GlobalAlias::create(Type *Ty, unsigned AddressSpace,
 272                                  LinkageTypes Linkage, const Twine &Name,
 273                                  GlobalValue *Aliasee) {
 274   return create(Ty, AddressSpace, Linkage, Name, Aliasee, Aliasee->getParent());
 275 }
 276
 277 GlobalAlias *GlobalAlias::create(LinkageTypes Link, const Twine &Name,
 278                                  GlobalValue *Aliasee) {
 279   PointerType *PTy = Aliasee->getType();
 280   return create(PTy->getElementType(), PTy->getAddressSpace(), Link, Name,
 281                 Aliasee);
 282 }
 283
 284 GlobalAlias *GlobalAlias::create(const Twine &Name, GlobalValue *Aliasee) {
 285   return create(Aliasee->getLinkage(), Name, Aliasee);
 286 }
 287
 288 void GlobalAlias::setParent(Module *parent) {
 289   Parent = parent;
 290 }
 291
 292 void GlobalAlias::removeFromParent() {
 293   getParent()->getAliasList().remove(this);
 294 }
 295
 296 void GlobalAlias::eraseFromParent() {
 297   getParent()->getAliasList().erase(this);
 298 }
 299
 300 void GlobalAlias::setAliasee(Constant *Aliasee) {
 301   assert((!Aliasee || Aliasee->getType() == getType()) &&
 302          "Alias and aliasee types should match!");
 303   setOperand(0, Aliasee);
 304 }