lib/IR/Module.cpp

   1 //===- Module.cpp - Implement the Module 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 Module class for the IR library.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/IR/Module.h"
  15 #include "SymbolTableListTraitsImpl.h"
  16 #include "llvm/ADT/Optional.h"
  17 #include "llvm/ADT/SmallPtrSet.h"
  18 #include "llvm/ADT/SmallString.h"
  19 #include "llvm/ADT/SmallVector.h"
  20 #include "llvm/ADT/StringMap.h"
  21 #include "llvm/ADT/StringRef.h"
  22 #include "llvm/ADT/Twine.h"
  23 #include "llvm/IR/Attributes.h"
  24 #include "llvm/IR/Comdat.h"
  25 #include "llvm/IR/Constants.h"
  26 #include "llvm/IR/DataLayout.h"
  27 #include "llvm/IR/DebugInfoMetadata.h"
  28 #include "llvm/IR/DerivedTypes.h"
  29 #include "llvm/IR/Function.h"
  30 #include "llvm/IR/GVMaterializer.h"
  31 #include "llvm/IR/GlobalAlias.h"
  32 #include "llvm/IR/GlobalIFunc.h"
  33 #include "llvm/IR/GlobalValue.h"
  34 #include "llvm/IR/GlobalVariable.h"
  35 #include "llvm/IR/LLVMContext.h"
  36 #include "llvm/IR/Metadata.h"
  37 #include "llvm/IR/SymbolTableListTraits.h"
  38 #include "llvm/IR/Type.h"
  39 #include "llvm/IR/TypeFinder.h"
  40 #include "llvm/IR/Value.h"
  41 #include "llvm/IR/ValueSymbolTable.h"
  42 #include "llvm/Pass.h"
  43 #include "llvm/Support/Casting.h"
  44 #include "llvm/Support/CodeGen.h"
  45 #include "llvm/Support/Error.h"
  46 #include "llvm/Support/MemoryBuffer.h"
  47 #include "llvm/Support/Path.h"
  48 #include "llvm/Support/RandomNumberGenerator.h"
  49 #include <algorithm>
  50 #include <cassert>
  51 #include <cstdint>
  52 #include <memory>
  53 #include <utility>
  54 #include <vector>
  55
  56 using namespace llvm;
  57
  58 //===----------------------------------------------------------------------===//
  59 // Methods to implement the globals and functions lists.
  60 //
  61
  62 // Explicit instantiations of SymbolTableListTraits since some of the methods
  63 // are not in the public header file.
  64 template class llvm::SymbolTableListTraits<Function>;
  65 template class llvm::SymbolTableListTraits<GlobalVariable>;
  66 template class llvm::SymbolTableListTraits<GlobalAlias>;
  67 template class llvm::SymbolTableListTraits<GlobalIFunc>;
  68
  69 //===----------------------------------------------------------------------===//
  70 // Primitive Module methods.
  71 //
  72
  73 Module::Module(StringRef MID, LLVMContext &C)
  74     : Context(C), Materializer(), ModuleID(MID), SourceFileName(MID), DL("") {
  75   ValSymTab = new ValueSymbolTable();
  76   NamedMDSymTab = new StringMap<NamedMDNode *>();
  77   Context.addModule(this);
  78 }
  79
  80 Module::~Module() {
  81   Context.removeModule(this);
  82   dropAllReferences();
  83   GlobalList.clear();
  84   FunctionList.clear();
  85   AliasList.clear();
  86   IFuncList.clear();
  87   NamedMDList.clear();
  88   delete ValSymTab;
  89   delete static_cast<StringMap<NamedMDNode *> *>(NamedMDSymTab);
  90 }
  91
  92 std::unique_ptr<RandomNumberGenerator> Module::createRNG(const Pass* P) const {
  93   SmallString<32> Salt(P->getPassName());
  94
  95   // This RNG is guaranteed to produce the same random stream only
  96   // when the Module ID and thus the input filename is the same. This
  97   // might be problematic if the input filename extension changes
  98   // (e.g. from .c to .bc or .ll).
  99   //
 100   // We could store this salt in NamedMetadata, but this would make
 101   // the parameter non-const. This would unfortunately make this
 102   // interface unusable by any Machine passes, since they only have a
 103   // const reference to their IR Module. Alternatively we can always
 104   // store salt metadata from the Module constructor.
 105   Salt += sys::path::filename(getModuleIdentifier());
 106
 107   return std::unique_ptr<RandomNumberGenerator>(new RandomNumberGenerator(Salt));
 108 }
 109
 110 /// getNamedValue - Return the first global value in the module with
 111 /// the specified name, of arbitrary type.  This method returns null
 112 /// if a global with the specified name is not found.
 113 GlobalValue *Module::getNamedValue(StringRef Name) const {
 114   return cast_or_null<GlobalValue>(getValueSymbolTable().lookup(Name));
 115 }
 116
 117 /// getMDKindID - Return a unique non-zero ID for the specified metadata kind.
 118 /// This ID is uniqued across modules in the current LLVMContext.
 119 unsigned Module::getMDKindID(StringRef Name) const {
 120   return Context.getMDKindID(Name);
 121 }
 122
 123 /// getMDKindNames - Populate client supplied SmallVector with the name for
 124 /// custom metadata IDs registered in this LLVMContext.   ID #0 is not used,
 125 /// so it is filled in as an empty string.
 126 void Module::getMDKindNames(SmallVectorImpl<StringRef> &Result) const {
 127   return Context.getMDKindNames(Result);
 128 }
 129
 130 void Module::getOperandBundleTags(SmallVectorImpl<StringRef> &Result) const {
 131   return Context.getOperandBundleTags(Result);
 132 }
 133
 134 //===----------------------------------------------------------------------===//
 135 // Methods for easy access to the functions in the module.
 136 //
 137
 138 // getOrInsertFunction - Look up the specified function in the module symbol
 139 // table.  If it does not exist, add a prototype for the function and return
 140 // it.  This is nice because it allows most passes to get away with not handling
 141 // the symbol table directly for this common task.
 142 //
 143 Constant *Module::getOrInsertFunction(StringRef Name, FunctionType *Ty,
 144                                       AttributeList AttributeList) {
 145   // See if we have a definition for the specified function already.
 146   GlobalValue *F = getNamedValue(Name);
 147   if (!F) {
 148     // Nope, add it
 149     Function *New = Function::Create(Ty, GlobalVariable::ExternalLinkage,
 150                                      DL.getProgramAddressSpace(), Name);
 151     if (!New->isIntrinsic())       // Intrinsics get attrs set on construction
 152       New->setAttributes(AttributeList);
 153     FunctionList.push_back(New);
 154     return New;                    // Return the new prototype.
 155   }
 156
 157   // If the function exists but has the wrong type, return a bitcast to the
 158   // right type.
 159   auto *PTy = PointerType::get(Ty, F->getAddressSpace());
 160   if (F->getType() != PTy)
 161     return ConstantExpr::getBitCast(F, PTy);
 162
 163   // Otherwise, we just found the existing function or a prototype.
 164   return F;
 165 }
 166
 167 Constant *Module::getOrInsertFunction(StringRef Name,
 168                                       FunctionType *Ty) {
 169   return getOrInsertFunction(Name, Ty, AttributeList());
 170 }
 171
 172 // getFunction - Look up the specified function in the module symbol table.
 173 // If it does not exist, return null.
 174 //
 175 Function *Module::getFunction(StringRef Name) const {
 176   return dyn_cast_or_null<Function>(getNamedValue(Name));
 177 }
 178
 179 //===----------------------------------------------------------------------===//
 180 // Methods for easy access to the global variables in the module.
 181 //
 182
 183 /// getGlobalVariable - Look up the specified global variable in the module
 184 /// symbol table.  If it does not exist, return null.  The type argument
 185 /// should be the underlying type of the global, i.e., it should not have
 186 /// the top-level PointerType, which represents the address of the global.
 187 /// If AllowLocal is set to true, this function will return types that
 188 /// have an local. By default, these types are not returned.
 189 ///
 190 GlobalVariable *Module::getGlobalVariable(StringRef Name,
 191                                           bool AllowLocal) const {
 192   if (GlobalVariable *Result =
 193       dyn_cast_or_null<GlobalVariable>(getNamedValue(Name)))
 194     if (AllowLocal || !Result->hasLocalLinkage())
 195       return Result;
 196   return nullptr;
 197 }
 198
 199 /// getOrInsertGlobal - Look up the specified global in the module symbol table.
 200 ///   1. If it does not exist, add a declaration of the global and return it.
 201 ///   2. Else, the global exists but has the wrong type: return the function
 202 ///      with a constantexpr cast to the right type.
 203 ///   3. Finally, if the existing global is the correct declaration, return the
 204 ///      existing global.
 205 Constant *Module::getOrInsertGlobal(StringRef Name, Type *Ty) {
 206   // See if we have a definition for the specified global already.
 207   GlobalVariable *GV = dyn_cast_or_null<GlobalVariable>(getNamedValue(Name));
 208   if (!GV) {
 209     // Nope, add it
 210     GlobalVariable *New =
 211       new GlobalVariable(*this, Ty, false, GlobalVariable::ExternalLinkage,
 212                          nullptr, Name);
 213      return New;                    // Return the new declaration.
 214   }
 215
 216   // If the variable exists but has the wrong type, return a bitcast to the
 217   // right type.
 218   Type *GVTy = GV->getType();
 219   PointerType *PTy = PointerType::get(Ty, GVTy->getPointerAddressSpace());
 220   if (GVTy != PTy)
 221     return ConstantExpr::getBitCast(GV, PTy);
 222
 223   // Otherwise, we just found the existing function or a prototype.
 224   return GV;
 225 }
 226
 227 //===----------------------------------------------------------------------===//
 228 // Methods for easy access to the global variables in the module.
 229 //
 230
 231 // getNamedAlias - Look up the specified global in the module symbol table.
 232 // If it does not exist, return null.
 233 //
 234 GlobalAlias *Module::getNamedAlias(StringRef Name) const {
 235   return dyn_cast_or_null<GlobalAlias>(getNamedValue(Name));
 236 }
 237
 238 GlobalIFunc *Module::getNamedIFunc(StringRef Name) const {
 239   return dyn_cast_or_null<GlobalIFunc>(getNamedValue(Name));
 240 }
 241
 242 /// getNamedMetadata - Return the first NamedMDNode in the module with the
 243 /// specified name. This method returns null if a NamedMDNode with the
 244 /// specified name is not found.
 245 NamedMDNode *Module::getNamedMetadata(const Twine &Name) const {
 246   SmallString<256> NameData;
 247   StringRef NameRef = Name.toStringRef(NameData);
 248   return static_cast<StringMap<NamedMDNode*> *>(NamedMDSymTab)->lookup(NameRef);
 249 }
 250
 251 /// getOrInsertNamedMetadata - Return the first named MDNode in the module
 252 /// with the specified name. This method returns a new NamedMDNode if a
 253 /// NamedMDNode with the specified name is not found.
 254 NamedMDNode *Module::getOrInsertNamedMetadata(StringRef Name) {
 255   NamedMDNode *&NMD =
 256     (*static_cast<StringMap<NamedMDNode *> *>(NamedMDSymTab))[Name];
 257   if (!NMD) {
 258     NMD = new NamedMDNode(Name);
 259     NMD->setParent(this);
 260     NamedMDList.push_back(NMD);
 261   }
 262   return NMD;
 263 }
 264
 265 /// eraseNamedMetadata - Remove the given NamedMDNode from this module and
 266 /// delete it.
 267 void Module::eraseNamedMetadata(NamedMDNode *NMD) {
 268   static_cast<StringMap<NamedMDNode *> *>(NamedMDSymTab)->erase(NMD->getName());
 269   NamedMDList.erase(NMD->getIterator());
 270 }
 271
 272 bool Module::isValidModFlagBehavior(Metadata *MD, ModFlagBehavior &MFB) {
 273   if (ConstantInt *Behavior = mdconst::dyn_extract_or_null<ConstantInt>(MD)) {
 274     uint64_t Val = Behavior->getLimitedValue();
 275     if (Val >= ModFlagBehaviorFirstVal && Val <= ModFlagBehaviorLastVal) {
 276       MFB = static_cast<ModFlagBehavior>(Val);
 277       return true;
 278     }
 279   }
 280   return false;
 281 }
 282
 283 /// getModuleFlagsMetadata - Returns the module flags in the provided vector.
 284 void Module::
 285 getModuleFlagsMetadata(SmallVectorImpl<ModuleFlagEntry> &Flags) const {
 286   const NamedMDNode *ModFlags = getModuleFlagsMetadata();
 287   if (!ModFlags) return;
 288
 289   for (const MDNode *Flag : ModFlags->operands()) {
 290     ModFlagBehavior MFB;
 291     if (Flag->getNumOperands() >= 3 &&
 292         isValidModFlagBehavior(Flag->getOperand(0), MFB) &&
 293         dyn_cast_or_null<MDString>(Flag->getOperand(1))) {
 294       // Check the operands of the MDNode before accessing the operands.
 295       // The verifier will actually catch these failures.
 296       MDString *Key = cast<MDString>(Flag->getOperand(1));
 297       Metadata *Val = Flag->getOperand(2);
 298       Flags.push_back(ModuleFlagEntry(MFB, Key, Val));
 299     }
 300   }
 301 }
 302
 303 /// Return the corresponding value if Key appears in module flags, otherwise
 304 /// return null.
 305 Metadata *Module::getModuleFlag(StringRef Key) const {
 306   SmallVector<Module::ModuleFlagEntry, 8> ModuleFlags;
 307   getModuleFlagsMetadata(ModuleFlags);
 308   for (const ModuleFlagEntry &MFE : ModuleFlags) {
 309     if (Key == MFE.Key->getString())
 310       return MFE.Val;
 311   }
 312   return nullptr;
 313 }
 314
 315 /// getModuleFlagsMetadata - Returns the NamedMDNode in the module that
 316 /// represents module-level flags. This method returns null if there are no
 317 /// module-level flags.
 318 NamedMDNode *Module::getModuleFlagsMetadata() const {
 319   return getNamedMetadata("llvm.module.flags");
 320 }
 321
 322 /// getOrInsertModuleFlagsMetadata - Returns the NamedMDNode in the module that
 323 /// represents module-level flags. If module-level flags aren't found, it
 324 /// creates the named metadata that contains them.
 325 NamedMDNode *Module::getOrInsertModuleFlagsMetadata() {
 326   return getOrInsertNamedMetadata("llvm.module.flags");
 327 }
 328
 329 /// addModuleFlag - Add a module-level flag to the module-level flags
 330 /// metadata. It will create the module-level flags named metadata if it doesn't
 331 /// already exist.
 332 void Module::addModuleFlag(ModFlagBehavior Behavior, StringRef Key,
 333                            Metadata *Val) {
 334   Type *Int32Ty = Type::getInt32Ty(Context);
 335   Metadata *Ops[3] = {
 336       ConstantAsMetadata::get(ConstantInt::get(Int32Ty, Behavior)),
 337       MDString::get(Context, Key), Val};
 338   getOrInsertModuleFlagsMetadata()->addOperand(MDNode::get(Context, Ops));
 339 }
 340 void Module::addModuleFlag(ModFlagBehavior Behavior, StringRef Key,
 341                            Constant *Val) {
 342   addModuleFlag(Behavior, Key, ConstantAsMetadata::get(Val));
 343 }
 344 void Module::addModuleFlag(ModFlagBehavior Behavior, StringRef Key,
 345                            uint32_t Val) {
 346   Type *Int32Ty = Type::getInt32Ty(Context);
 347   addModuleFlag(Behavior, Key, ConstantInt::get(Int32Ty, Val));
 348 }
 349 void Module::addModuleFlag(MDNode *Node) {
 350   assert(Node->getNumOperands() == 3 &&
 351          "Invalid number of operands for module flag!");
 352   assert(mdconst::hasa<ConstantInt>(Node->getOperand(0)) &&
 353          isa<MDString>(Node->getOperand(1)) &&
 354          "Invalid operand types for module flag!");
 355   getOrInsertModuleFlagsMetadata()->addOperand(Node);
 356 }
 357
 358 void Module::setDataLayout(StringRef Desc) {
 359   DL.reset(Desc);
 360 }
 361
 362 void Module::setDataLayout(const DataLayout &Other) { DL = Other; }
 363
 364 const DataLayout &Module::getDataLayout() const { return DL; }
 365
 366 DICompileUnit *Module::debug_compile_units_iterator::operator*() const {
 367   return cast<DICompileUnit>(CUs->getOperand(Idx));
 368 }
 369 DICompileUnit *Module::debug_compile_units_iterator::operator->() const {
 370   return cast<DICompileUnit>(CUs->getOperand(Idx));
 371 }
 372
 373 void Module::debug_compile_units_iterator::SkipNoDebugCUs() {
 374   while (CUs && (Idx < CUs->getNumOperands()) &&
 375          ((*this)->getEmissionKind() == DICompileUnit::NoDebug))
 376     ++Idx;
 377 }
 378
 379 //===----------------------------------------------------------------------===//
 380 // Methods to control the materialization of GlobalValues in the Module.
 381 //
 382 void Module::setMaterializer(GVMaterializer *GVM) {
 383   assert(!Materializer &&
 384          "Module already has a GVMaterializer.  Call materializeAll"
 385          " to clear it out before setting another one.");
 386   Materializer.reset(GVM);
 387 }
 388
 389 Error Module::materialize(GlobalValue *GV) {
 390   if (!Materializer)
 391     return Error::success();
 392
 393   return Materializer->materialize(GV);
 394 }
 395
 396 Error Module::materializeAll() {
 397   if (!Materializer)
 398     return Error::success();
 399   std::unique_ptr<GVMaterializer> M = std::move(Materializer);
 400   return M->materializeModule();
 401 }
 402
 403 Error Module::materializeMetadata() {
 404   if (!Materializer)
 405     return Error::success();
 406   return Materializer->materializeMetadata();
 407 }
 408
 409 //===----------------------------------------------------------------------===//
 410 // Other module related stuff.
 411 //
 412
 413 std::vector<StructType *> Module::getIdentifiedStructTypes() const {
 414   // If we have a materializer, it is possible that some unread function
 415   // uses a type that is currently not visible to a TypeFinder, so ask
 416   // the materializer which types it created.
 417   if (Materializer)
 418     return Materializer->getIdentifiedStructTypes();
 419
 420   std::vector<StructType *> Ret;
 421   TypeFinder SrcStructTypes;
 422   SrcStructTypes.run(*this, true);
 423   Ret.assign(SrcStructTypes.begin(), SrcStructTypes.end());
 424   return Ret;
 425 }
 426
 427 // dropAllReferences() - This function causes all the subelements to "let go"
 428 // of all references that they are maintaining.  This allows one to 'delete' a
 429 // whole module at a time, even though there may be circular references... first
 430 // all references are dropped, and all use counts go to zero.  Then everything
 431 // is deleted for real.  Note that no operations are valid on an object that
 432 // has "dropped all references", except operator delete.
 433 //
 434 void Module::dropAllReferences() {
 435   for (Function &F : *this)
 436     F.dropAllReferences();
 437
 438   for (GlobalVariable &GV : globals())
 439     GV.dropAllReferences();
 440
 441   for (GlobalAlias &GA : aliases())
 442     GA.dropAllReferences();
 443
 444   for (GlobalIFunc &GIF : ifuncs())
 445     GIF.dropAllReferences();
 446 }
 447
 448 unsigned Module::getNumberRegisterParameters() const {
 449   auto *Val =
 450       cast_or_null<ConstantAsMetadata>(getModuleFlag("NumRegisterParameters"));
 451   if (!Val)
 452     return 0;
 453   return cast<ConstantInt>(Val->getValue())->getZExtValue();
 454 }
 455
 456 unsigned Module::getDwarfVersion() const {
 457   auto *Val = cast_or_null<ConstantAsMetadata>(getModuleFlag("Dwarf Version"));
 458   if (!Val)
 459     return 0;
 460   return cast<ConstantInt>(Val->getValue())->getZExtValue();
 461 }
 462
 463 unsigned Module::getCodeViewFlag() const {
 464   auto *Val = cast_or_null<ConstantAsMetadata>(getModuleFlag("CodeView"));
 465   if (!Val)
 466     return 0;
 467   return cast<ConstantInt>(Val->getValue())->getZExtValue();
 468 }
 469
 470 unsigned Module::getInstructionCount() {
 471   unsigned NumInstrs = 0;
 472   for (Function &F : FunctionList)
 473     NumInstrs += F.getInstructionCount();
 474   return NumInstrs;
 475 }
 476
 477 Comdat *Module::getOrInsertComdat(StringRef Name) {
 478   auto &Entry = *ComdatSymTab.insert(std::make_pair(Name, Comdat())).first;
 479   Entry.second.Name = &Entry;
 480   return &Entry.second;
 481 }
 482
 483 PICLevel::Level Module::getPICLevel() const {
 484   auto *Val = cast_or_null<ConstantAsMetadata>(getModuleFlag("PIC Level"));
 485
 486   if (!Val)
 487     return PICLevel::NotPIC;
 488
 489   return static_cast<PICLevel::Level>(
 490       cast<ConstantInt>(Val->getValue())->getZExtValue());
 491 }
 492
 493 void Module::setPICLevel(PICLevel::Level PL) {
 494   addModuleFlag(ModFlagBehavior::Max, "PIC Level", PL);
 495 }
 496
 497 PIELevel::Level Module::getPIELevel() const {
 498   auto *Val = cast_or_null<ConstantAsMetadata>(getModuleFlag("PIE Level"));
 499
 500   if (!Val)
 501     return PIELevel::Default;
 502
 503   return static_cast<PIELevel::Level>(
 504       cast<ConstantInt>(Val->getValue())->getZExtValue());
 505 }
 506
 507 void Module::setPIELevel(PIELevel::Level PL) {
 508   addModuleFlag(ModFlagBehavior::Max, "PIE Level", PL);
 509 }
 510
 511 Optional<CodeModel::Model> Module::getCodeModel() const {
 512   auto *Val = cast_or_null<ConstantAsMetadata>(getModuleFlag("Code Model"));
 513
 514   if (!Val)
 515     return None;
 516
 517   return static_cast<CodeModel::Model>(
 518       cast<ConstantInt>(Val->getValue())->getZExtValue());
 519 }
 520
 521 void Module::setCodeModel(CodeModel::Model CL) {
 522   // Linking object files with different code models is undefined behavior
 523   // because the compiler would have to generate additional code (to span
 524   // longer jumps) if a larger code model is used with a smaller one.
 525   // Therefore we will treat attempts to mix code models as an error.
 526   addModuleFlag(ModFlagBehavior::Error, "Code Model", CL);
 527 }
 528
 529 void Module::setProfileSummary(Metadata *M) {
 530   addModuleFlag(ModFlagBehavior::Error, "ProfileSummary", M);
 531 }
 532
 533 Metadata *Module::getProfileSummary() {
 534   return getModuleFlag("ProfileSummary");
 535 }
 536
 537 void Module::setOwnedMemoryBuffer(std::unique_ptr<MemoryBuffer> MB) {
 538   OwnedMemoryBuffer = std::move(MB);
 539 }
 540
 541 bool Module::getRtLibUseGOT() const {
 542   auto *Val = cast_or_null<ConstantAsMetadata>(getModuleFlag("RtLibUseGOT"));
 543   return Val && (cast<ConstantInt>(Val->getValue())->getZExtValue() > 0);
 544 }
 545
 546 void Module::setRtLibUseGOT() {
 547   addModuleFlag(ModFlagBehavior::Max, "RtLibUseGOT", 1);
 548 }
 549
 550 GlobalVariable *llvm::collectUsedGlobalVariables(
 551     const Module &M, SmallPtrSetImpl<GlobalValue *> &Set, bool CompilerUsed) {
 552   const char *Name = CompilerUsed ? "llvm.compiler.used" : "llvm.used";
 553   GlobalVariable *GV = M.getGlobalVariable(Name);
 554   if (!GV || !GV->hasInitializer())
 555     return GV;
 556
 557   const ConstantArray *Init = cast<ConstantArray>(GV->getInitializer());
 558   for (Value *Op : Init->operands()) {
 559     GlobalValue *G = cast<GlobalValue>(Op->stripPointerCastsNoFollowAliases());
 560     Set.insert(G);
 561   }
 562   return GV;
 563 }