llvm/lib/ExecutionEngine/Orc/CompileOnDemandLayer.cpp

   1 //===----- CompileOnDemandLayer.cpp - Lazily emit IR on first call --------===//
   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 #include "llvm/ExecutionEngine/Orc/CompileOnDemandLayer.h"
  10 #include "llvm/ADT/Hashing.h"
  11 #include "llvm/ExecutionEngine/Orc/ExecutionUtils.h"
  12 #include "llvm/IR/Mangler.h"
  13 #include "llvm/IR/Module.h"
  14 #include "llvm/Support/FormatVariadic.h"
  15 #include <string>
  16
  17 using namespace llvm;
  18 using namespace llvm::orc;
  19
  20 static ThreadSafeModule extractSubModule(ThreadSafeModule &TSM,
  21                                          StringRef Suffix,
  22                                          GVPredicate ShouldExtract) {
  23
  24   auto DeleteExtractedDefs = [](GlobalValue &GV) {
  25     // Bump the linkage: this global will be provided by the external module.
  26     GV.setLinkage(GlobalValue::ExternalLinkage);
  27
  28     // Delete the definition in the source module.
  29     if (isa<Function>(GV)) {
  30       auto &F = cast<Function>(GV);
  31       F.deleteBody();
  32       F.setPersonalityFn(nullptr);
  33     } else if (isa<GlobalVariable>(GV)) {
  34       cast<GlobalVariable>(GV).setInitializer(nullptr);
  35     } else if (isa<GlobalAlias>(GV)) {
  36       // We need to turn deleted aliases into function or variable decls based
  37       // on the type of their aliasee.
  38       auto &A = cast<GlobalAlias>(GV);
  39       Constant *Aliasee = A.getAliasee();
  40       assert(A.hasName() && "Anonymous alias?");
  41       assert(Aliasee->hasName() && "Anonymous aliasee");
  42       std::string AliasName = std::string(A.getName());
  43
  44       if (isa<Function>(Aliasee)) {
  45         auto *F = cloneFunctionDecl(*A.getParent(), *cast<Function>(Aliasee));
  46         A.replaceAllUsesWith(F);
  47         A.eraseFromParent();
  48         F->setName(AliasName);
  49       } else if (isa<GlobalVariable>(Aliasee)) {
  50         auto *G = cloneGlobalVariableDecl(*A.getParent(),
  51                                           *cast<GlobalVariable>(Aliasee));
  52         A.replaceAllUsesWith(G);
  53         A.eraseFromParent();
  54         G->setName(AliasName);
  55       } else
  56         llvm_unreachable("Alias to unsupported type");
  57     } else
  58       llvm_unreachable("Unsupported global type");
  59   };
  60
  61   auto NewTSM = cloneToNewContext(TSM, ShouldExtract, DeleteExtractedDefs);
  62   NewTSM.withModuleDo([&](Module &M) {
  63     M.setModuleIdentifier((M.getModuleIdentifier() + Suffix).str());
  64   });
  65
  66   return NewTSM;
  67 }
  68
  69 namespace llvm {
  70 namespace orc {
  71
  72 class PartitioningIRMaterializationUnit : public IRMaterializationUnit {
  73 public:
  74   PartitioningIRMaterializationUnit(ExecutionSession &ES,
  75                                     const IRSymbolMapper::ManglingOptions &MO,
  76                                     ThreadSafeModule TSM,
  77                                     CompileOnDemandLayer &Parent)
  78       : IRMaterializationUnit(ES, MO, std::move(TSM)), Parent(Parent) {}
  79
  80   PartitioningIRMaterializationUnit(
  81       ThreadSafeModule TSM, SymbolFlagsMap SymbolFlags,
  82       SymbolStringPtr InitSymbol, SymbolNameToDefinitionMap SymbolToDefinition,
  83       CompileOnDemandLayer &Parent)
  84       : IRMaterializationUnit(std::move(TSM), std::move(SymbolFlags),
  85                               std::move(InitSymbol),
  86                               std::move(SymbolToDefinition)),
  87         Parent(Parent) {}
  88
  89 private:
  90   void materialize(std::unique_ptr<MaterializationResponsibility> R) override {
  91     Parent.emitPartition(std::move(R), std::move(TSM),
  92                          std::move(SymbolToDefinition));
  93   }
  94
  95   void discard(const JITDylib &V, const SymbolStringPtr &Name) override {
  96     // All original symbols were materialized by the CODLayer and should be
  97     // final. The function bodies provided by M should never be overridden.
  98     llvm_unreachable("Discard should never be called on an "
  99                      "ExtractingIRMaterializationUnit");
 100   }
 101
 102   mutable std::mutex SourceModuleMutex;
 103   CompileOnDemandLayer &Parent;
 104 };
 105
 106 Optional<CompileOnDemandLayer::GlobalValueSet>
 107 CompileOnDemandLayer::compileRequested(GlobalValueSet Requested) {
 108   return std::move(Requested);
 109 }
 110
 111 Optional<CompileOnDemandLayer::GlobalValueSet>
 112 CompileOnDemandLayer::compileWholeModule(GlobalValueSet Requested) {
 113   return None;
 114 }
 115
 116 CompileOnDemandLayer::CompileOnDemandLayer(
 117     ExecutionSession &ES, IRLayer &BaseLayer, LazyCallThroughManager &LCTMgr,
 118     IndirectStubsManagerBuilder BuildIndirectStubsManager)
 119     : IRLayer(ES, BaseLayer.getManglingOptions()), BaseLayer(BaseLayer),
 120       LCTMgr(LCTMgr),
 121       BuildIndirectStubsManager(std::move(BuildIndirectStubsManager)) {}
 122
 123 void CompileOnDemandLayer::setPartitionFunction(PartitionFunction Partition) {
 124   this->Partition = std::move(Partition);
 125 }
 126
 127 void CompileOnDemandLayer::setImplMap(ImplSymbolMap *Imp) {
 128   this->AliaseeImpls = Imp;
 129 }
 130 void CompileOnDemandLayer::emit(
 131     std::unique_ptr<MaterializationResponsibility> R, ThreadSafeModule TSM) {
 132   assert(TSM && "Null module");
 133
 134   auto &ES = getExecutionSession();
 135
 136   // Sort the callables and non-callables, build re-exports and lodge the
 137   // actual module with the implementation dylib.
 138   auto &PDR = getPerDylibResources(R->getTargetJITDylib());
 139
 140   SymbolAliasMap NonCallables;
 141   SymbolAliasMap Callables;
 142   TSM.withModuleDo([&](Module &M) {
 143     // First, do some cleanup on the module:
 144     cleanUpModule(M);
 145   });
 146
 147   for (auto &KV : R->getSymbols()) {
 148     auto &Name = KV.first;
 149     auto &Flags = KV.second;
 150     if (Flags.isCallable())
 151       Callables[Name] = SymbolAliasMapEntry(Name, Flags);
 152     else
 153       NonCallables[Name] = SymbolAliasMapEntry(Name, Flags);
 154   }
 155
 156   // Create a partitioning materialization unit and lodge it with the
 157   // implementation dylib.
 158   if (auto Err = PDR.getImplDylib().define(
 159           std::make_unique<PartitioningIRMaterializationUnit>(
 160               ES, *getManglingOptions(), std::move(TSM), *this))) {
 161     ES.reportError(std::move(Err));
 162     R->failMaterialization();
 163     return;
 164   }
 165
 166   if (!NonCallables.empty())
 167     if (auto Err =
 168             R->replace(reexports(PDR.getImplDylib(), std::move(NonCallables),
 169                                  JITDylibLookupFlags::MatchAllSymbols))) {
 170       getExecutionSession().reportError(std::move(Err));
 171       R->failMaterialization();
 172       return;
 173     }
 174   if (!Callables.empty()) {
 175     if (auto Err = R->replace(
 176             lazyReexports(LCTMgr, PDR.getISManager(), PDR.getImplDylib(),
 177                           std::move(Callables), AliaseeImpls))) {
 178       getExecutionSession().reportError(std::move(Err));
 179       R->failMaterialization();
 180       return;
 181     }
 182   }
 183 }
 184
 185 CompileOnDemandLayer::PerDylibResources &
 186 CompileOnDemandLayer::getPerDylibResources(JITDylib &TargetD) {
 187   auto I = DylibResources.find(&TargetD);
 188   if (I == DylibResources.end()) {
 189     auto &ImplD =
 190         getExecutionSession().createBareJITDylib(TargetD.getName() + ".impl");
 191     JITDylibSearchOrder NewLinkOrder;
 192     TargetD.withLinkOrderDo([&](const JITDylibSearchOrder &TargetLinkOrder) {
 193       NewLinkOrder = TargetLinkOrder;
 194     });
 195
 196     assert(!NewLinkOrder.empty() && NewLinkOrder.front().first == &TargetD &&
 197            NewLinkOrder.front().second ==
 198                JITDylibLookupFlags::MatchAllSymbols &&
 199            "TargetD must be at the front of its own search order and match "
 200            "non-exported symbol");
 201     NewLinkOrder.insert(std::next(NewLinkOrder.begin()),
 202                         {&ImplD, JITDylibLookupFlags::MatchAllSymbols});
 203     ImplD.setLinkOrder(NewLinkOrder, false);
 204     TargetD.setLinkOrder(std::move(NewLinkOrder), false);
 205
 206     PerDylibResources PDR(ImplD, BuildIndirectStubsManager());
 207     I = DylibResources.insert(std::make_pair(&TargetD, std::move(PDR))).first;
 208   }
 209
 210   return I->second;
 211 }
 212
 213 void CompileOnDemandLayer::cleanUpModule(Module &M) {
 214   for (auto &F : M.functions()) {
 215     if (F.isDeclaration())
 216       continue;
 217
 218     if (F.hasAvailableExternallyLinkage()) {
 219       F.deleteBody();
 220       F.setPersonalityFn(nullptr);
 221       continue;
 222     }
 223   }
 224 }
 225
 226 void CompileOnDemandLayer::expandPartition(GlobalValueSet &Partition) {
 227   // Expands the partition to ensure the following rules hold:
 228   // (1) If any alias is in the partition, its aliasee is also in the partition.
 229   // (2) If any aliasee is in the partition, its aliases are also in the
 230   //     partiton.
 231   // (3) If any global variable is in the partition then all global variables
 232   //     are in the partition.
 233   assert(!Partition.empty() && "Unexpected empty partition");
 234
 235   const Module &M = *(*Partition.begin())->getParent();
 236   bool ContainsGlobalVariables = false;
 237   std::vector<const GlobalValue *> GVsToAdd;
 238
 239   for (auto *GV : Partition)
 240     if (isa<GlobalAlias>(GV))
 241       GVsToAdd.push_back(
 242           cast<GlobalValue>(cast<GlobalAlias>(GV)->getAliasee()));
 243     else if (isa<GlobalVariable>(GV))
 244       ContainsGlobalVariables = true;
 245
 246   for (auto &A : M.aliases())
 247     if (Partition.count(cast<GlobalValue>(A.getAliasee())))
 248       GVsToAdd.push_back(&A);
 249
 250   if (ContainsGlobalVariables)
 251     for (auto &G : M.globals())
 252       GVsToAdd.push_back(&G);
 253
 254   for (auto *GV : GVsToAdd)
 255     Partition.insert(GV);
 256 }
 257
 258 void CompileOnDemandLayer::emitPartition(
 259     std::unique_ptr<MaterializationResponsibility> R, ThreadSafeModule TSM,
 260     IRMaterializationUnit::SymbolNameToDefinitionMap Defs) {
 261
 262   // FIXME: Need a 'notify lazy-extracting/emitting' callback to tie the
 263   //        extracted module key, extracted module, and source module key
 264   //        together. This could be used, for example, to provide a specific
 265   //        memory manager instance to the linking layer.
 266
 267   auto &ES = getExecutionSession();
 268   GlobalValueSet RequestedGVs;
 269   for (auto &Name : R->getRequestedSymbols()) {
 270     if (Name == R->getInitializerSymbol())
 271       TSM.withModuleDo([&](Module &M) {
 272         for (auto &GV : getStaticInitGVs(M))
 273           RequestedGVs.insert(&GV);
 274       });
 275     else {
 276       assert(Defs.count(Name) && "No definition for symbol");
 277       RequestedGVs.insert(Defs[Name]);
 278     }
 279   }
 280
 281   /// Perform partitioning with the context lock held, since the partition
 282   /// function is allowed to access the globals to compute the partition.
 283   auto GVsToExtract =
 284       TSM.withModuleDo([&](Module &M) { return Partition(RequestedGVs); });
 285
 286   // Take a 'None' partition to mean the whole module (as opposed to an empty
 287   // partition, which means "materialize nothing"). Emit the whole module
 288   // unmodified to the base layer.
 289   if (GVsToExtract == None) {
 290     Defs.clear();
 291     BaseLayer.emit(std::move(R), std::move(TSM));
 292     return;
 293   }
 294
 295   // If the partition is empty, return the whole module to the symbol table.
 296   if (GVsToExtract->empty()) {
 297     if (auto Err =
 298             R->replace(std::make_unique<PartitioningIRMaterializationUnit>(
 299                 std::move(TSM), R->getSymbols(), R->getInitializerSymbol(),
 300                 std::move(Defs), *this))) {
 301       getExecutionSession().reportError(std::move(Err));
 302       R->failMaterialization();
 303       return;
 304     }
 305     return;
 306   }
 307
 308   // Ok -- we actually need to partition the symbols. Promote the symbol
 309   // linkages/names, expand the partition to include any required symbols
 310   // (i.e. symbols that can't be separated from our partition), and
 311   // then extract the partition.
 312   //
 313   // FIXME: We apply this promotion once per partitioning. It's safe, but
 314   // overkill.
 315   auto ExtractedTSM =
 316       TSM.withModuleDo([&](Module &M) -> Expected<ThreadSafeModule> {
 317         auto PromotedGlobals = PromoteSymbols(M);
 318         if (!PromotedGlobals.empty()) {
 319
 320           MangleAndInterner Mangle(ES, M.getDataLayout());
 321           SymbolFlagsMap SymbolFlags;
 322           IRSymbolMapper::add(ES, *getManglingOptions(),
 323                               PromotedGlobals, SymbolFlags);
 324
 325           if (auto Err = R->defineMaterializing(SymbolFlags))
 326             return std::move(Err);
 327         }
 328
 329         expandPartition(*GVsToExtract);
 330
 331         // Submodule name is given by hashing the names of the globals.
 332         std::string SubModuleName;
 333         {
 334           std::vector<const GlobalValue*> HashGVs;
 335           HashGVs.reserve(GVsToExtract->size());
 336           for (auto *GV : *GVsToExtract)
 337             HashGVs.push_back(GV);
 338           llvm::sort(HashGVs, [](const GlobalValue *LHS, const GlobalValue *RHS) {
 339               return LHS->getName() < RHS->getName();
 340             });
 341           hash_code HC(0);
 342           for (auto *GV : HashGVs) {
 343             assert(GV->hasName() && "All GVs to extract should be named by now");
 344             auto GVName = GV->getName();
 345             HC = hash_combine(HC, hash_combine_range(GVName.begin(), GVName.end()));
 346           }
 347           raw_string_ostream(SubModuleName)
 348             << ".submodule."
 349             << formatv(sizeof(size_t) == 8 ? "{0:x16}" : "{0:x8}",
 350                        static_cast<size_t>(HC))
 351             << ".ll";
 352         }
 353
 354         // Extract the requested partiton (plus any necessary aliases) and
 355         // put the rest back into the impl dylib.
 356         auto ShouldExtract = [&](const GlobalValue &GV) -> bool {
 357           return GVsToExtract->count(&GV);
 358         };
 359
 360         return extractSubModule(TSM, SubModuleName , ShouldExtract);
 361       });
 362
 363   if (!ExtractedTSM) {
 364     ES.reportError(ExtractedTSM.takeError());
 365     R->failMaterialization();
 366     return;
 367   }
 368
 369   if (auto Err = R->replace(std::make_unique<PartitioningIRMaterializationUnit>(
 370           ES, *getManglingOptions(), std::move(TSM), *this))) {
 371     ES.reportError(std::move(Err));
 372     R->failMaterialization();
 373     return;
 374   }
 375   BaseLayer.emit(std::move(R), std::move(*ExtractedTSM));
 376 }
 377
 378 } // end namespace orc
 379 } // end namespace llvm