llvm/lib/ExecutionEngine/Orc/ObjectFileInterface.cpp

   1 //===------ ObjectFileInterface.cpp - MU interface utils for objects ------===//
   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/ObjectFileInterface.h"
  10 #include "llvm/ExecutionEngine/Orc/Shared/ObjectFormats.h"
  11 #include "llvm/Object/COFF.h"
  12 #include "llvm/Object/ELFObjectFile.h"
  13 #include "llvm/Object/MachO.h"
  14 #include "llvm/Object/ObjectFile.h"
  15 #include <optional>
  16
  17 #define DEBUG_TYPE "orc"
  18
  19 namespace llvm {
  20 namespace orc {
  21
  22 void addInitSymbol(MaterializationUnit::Interface &I, ExecutionSession &ES,
  23                    StringRef ObjFileName) {
  24   assert(!I.InitSymbol && "I already has an init symbol");
  25   size_t Counter = 0;
  26
  27   do {
  28     std::string InitSymString;
  29     raw_string_ostream(InitSymString)
  30         << "$." << ObjFileName << ".__inits." << Counter++;
  31     I.InitSymbol = ES.intern(InitSymString);
  32   } while (I.SymbolFlags.count(I.InitSymbol));
  33
  34   I.SymbolFlags[I.InitSymbol] = JITSymbolFlags::MaterializationSideEffectsOnly;
  35 }
  36
  37 static Expected<MaterializationUnit::Interface>
  38 getMachOObjectFileSymbolInfo(ExecutionSession &ES,
  39                              const object::MachOObjectFile &Obj) {
  40   MaterializationUnit::Interface I;
  41
  42   for (auto &Sym : Obj.symbols()) {
  43     Expected<uint32_t> SymFlagsOrErr = Sym.getFlags();
  44     if (!SymFlagsOrErr)
  45       // TODO: Test this error.
  46       return SymFlagsOrErr.takeError();
  47
  48     // Skip symbols not defined in this object file.
  49     if (*SymFlagsOrErr & object::BasicSymbolRef::SF_Undefined)
  50       continue;
  51
  52     // Skip symbols that are not global.
  53     if (!(*SymFlagsOrErr & object::BasicSymbolRef::SF_Global))
  54       continue;
  55
  56     // Skip symbols that have type SF_File.
  57     if (auto SymType = Sym.getType()) {
  58       if (*SymType == object::SymbolRef::ST_File)
  59         continue;
  60     } else
  61       return SymType.takeError();
  62
  63     auto Name = Sym.getName();
  64     if (!Name)
  65       return Name.takeError();
  66     auto SymFlags = JITSymbolFlags::fromObjectSymbol(Sym);
  67     if (!SymFlags)
  68       return SymFlags.takeError();
  69
  70     // Strip the 'exported' flag from MachO linker-private symbols.
  71     if (Name->starts_with("l"))
  72       *SymFlags &= ~JITSymbolFlags::Exported;
  73
  74     I.SymbolFlags[ES.intern(*Name)] = std::move(*SymFlags);
  75   }
  76
  77   for (auto &Sec : Obj.sections()) {
  78     auto SecType = Obj.getSectionType(Sec);
  79     if ((SecType & MachO::SECTION_TYPE) == MachO::S_MOD_INIT_FUNC_POINTERS) {
  80       addInitSymbol(I, ES, Obj.getFileName());
  81       break;
  82     }
  83     auto SegName = Obj.getSectionFinalSegmentName(Sec.getRawDataRefImpl());
  84     auto SecName = cantFail(Obj.getSectionName(Sec.getRawDataRefImpl()));
  85     if (isMachOInitializerSection(SegName, SecName)) {
  86       addInitSymbol(I, ES, Obj.getFileName());
  87       break;
  88     }
  89   }
  90
  91   return I;
  92 }
  93
  94 static Expected<MaterializationUnit::Interface>
  95 getELFObjectFileSymbolInfo(ExecutionSession &ES,
  96                            const object::ELFObjectFileBase &Obj) {
  97   MaterializationUnit::Interface I;
  98
  99   for (auto &Sym : Obj.symbols()) {
 100     Expected<uint32_t> SymFlagsOrErr = Sym.getFlags();
 101     if (!SymFlagsOrErr)
 102       // TODO: Test this error.
 103       return SymFlagsOrErr.takeError();
 104
 105     // Skip symbols not defined in this object file.
 106     if (*SymFlagsOrErr & object::BasicSymbolRef::SF_Undefined)
 107       continue;
 108
 109     // Skip symbols that are not global.
 110     if (!(*SymFlagsOrErr & object::BasicSymbolRef::SF_Global))
 111       continue;
 112
 113     // Skip symbols that have type SF_File.
 114     if (auto SymType = Sym.getType()) {
 115       if (*SymType == object::SymbolRef::ST_File)
 116         continue;
 117     } else
 118       return SymType.takeError();
 119
 120     auto Name = Sym.getName();
 121     if (!Name)
 122       return Name.takeError();
 123
 124     auto SymFlags = JITSymbolFlags::fromObjectSymbol(Sym);
 125     if (!SymFlags)
 126       return SymFlags.takeError();
 127
 128     // ELF STB_GNU_UNIQUE should map to Weak for ORC.
 129     if (Sym.getBinding() == ELF::STB_GNU_UNIQUE)
 130       *SymFlags |= JITSymbolFlags::Weak;
 131
 132     I.SymbolFlags[ES.intern(*Name)] = std::move(*SymFlags);
 133   }
 134
 135   SymbolStringPtr InitSymbol;
 136   for (auto &Sec : Obj.sections()) {
 137     if (auto SecName = Sec.getName()) {
 138       if (isELFInitializerSection(*SecName)) {
 139         addInitSymbol(I, ES, Obj.getFileName());
 140         break;
 141       }
 142     }
 143   }
 144
 145   return I;
 146 }
 147
 148 static Expected<MaterializationUnit::Interface>
 149 getCOFFObjectFileSymbolInfo(ExecutionSession &ES,
 150                             const object::COFFObjectFile &Obj) {
 151   MaterializationUnit::Interface I;
 152   std::vector<std::optional<object::coff_aux_section_definition>> ComdatDefs(
 153       Obj.getNumberOfSections() + 1);
 154   for (auto &Sym : Obj.symbols()) {
 155     Expected<uint32_t> SymFlagsOrErr = Sym.getFlags();
 156     if (!SymFlagsOrErr)
 157       // TODO: Test this error.
 158       return SymFlagsOrErr.takeError();
 159
 160     // Handle comdat symbols
 161     auto COFFSym = Obj.getCOFFSymbol(Sym);
 162     bool IsWeak = false;
 163     if (auto *Def = COFFSym.getSectionDefinition()) {
 164       auto Sec = Obj.getSection(COFFSym.getSectionNumber());
 165       if (!Sec)
 166         return Sec.takeError();
 167       if (((*Sec)->Characteristics & COFF::IMAGE_SCN_LNK_COMDAT) &&
 168           Def->Selection != COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
 169         ComdatDefs[COFFSym.getSectionNumber()] = *Def;
 170         continue;
 171       }
 172     }
 173     if (!COFF::isReservedSectionNumber(COFFSym.getSectionNumber()) &&
 174         ComdatDefs[COFFSym.getSectionNumber()]) {
 175       auto Def = ComdatDefs[COFFSym.getSectionNumber()];
 176       if (Def->Selection != COFF::IMAGE_COMDAT_SELECT_NODUPLICATES) {
 177         IsWeak = true;
 178       }
 179       ComdatDefs[COFFSym.getSectionNumber()] = std::nullopt;
 180     } else {
 181       // Skip symbols not defined in this object file.
 182       if (*SymFlagsOrErr & object::BasicSymbolRef::SF_Undefined)
 183         continue;
 184     }
 185
 186     // Skip symbols that are not global.
 187     if (!(*SymFlagsOrErr & object::BasicSymbolRef::SF_Global))
 188       continue;
 189
 190     // Skip symbols that have type SF_File.
 191     if (auto SymType = Sym.getType()) {
 192       if (*SymType == object::SymbolRef::ST_File)
 193         continue;
 194     } else
 195       return SymType.takeError();
 196
 197     auto Name = Sym.getName();
 198     if (!Name)
 199       return Name.takeError();
 200
 201     auto SymFlags = JITSymbolFlags::fromObjectSymbol(Sym);
 202     if (!SymFlags)
 203       return SymFlags.takeError();
 204     *SymFlags |= JITSymbolFlags::Exported;
 205
 206     // Weak external is always a function
 207     if (COFFSym.isWeakExternal())
 208       *SymFlags |= JITSymbolFlags::Callable;
 209
 210     if (IsWeak)
 211       *SymFlags |= JITSymbolFlags::Weak;
 212
 213     I.SymbolFlags[ES.intern(*Name)] = std::move(*SymFlags);
 214   }
 215
 216   SymbolStringPtr InitSymbol;
 217   for (auto &Sec : Obj.sections()) {
 218     if (auto SecName = Sec.getName()) {
 219       if (isCOFFInitializerSection(*SecName)) {
 220         addInitSymbol(I, ES, Obj.getFileName());
 221         break;
 222       }
 223     } else
 224       return SecName.takeError();
 225   }
 226
 227   return I;
 228 }
 229
 230 Expected<MaterializationUnit::Interface>
 231 getGenericObjectFileSymbolInfo(ExecutionSession &ES,
 232                                const object::ObjectFile &Obj) {
 233   MaterializationUnit::Interface I;
 234
 235   for (auto &Sym : Obj.symbols()) {
 236     Expected<uint32_t> SymFlagsOrErr = Sym.getFlags();
 237     if (!SymFlagsOrErr)
 238       // TODO: Test this error.
 239       return SymFlagsOrErr.takeError();
 240
 241     // Skip symbols not defined in this object file.
 242     if (*SymFlagsOrErr & object::BasicSymbolRef::SF_Undefined)
 243       continue;
 244
 245     // Skip symbols that are not global.
 246     if (!(*SymFlagsOrErr & object::BasicSymbolRef::SF_Global))
 247       continue;
 248
 249     // Skip symbols that have type SF_File.
 250     if (auto SymType = Sym.getType()) {
 251       if (*SymType == object::SymbolRef::ST_File)
 252         continue;
 253     } else
 254       return SymType.takeError();
 255
 256     auto Name = Sym.getName();
 257     if (!Name)
 258       return Name.takeError();
 259
 260     auto SymFlags = JITSymbolFlags::fromObjectSymbol(Sym);
 261     if (!SymFlags)
 262       return SymFlags.takeError();
 263
 264     I.SymbolFlags[ES.intern(*Name)] = std::move(*SymFlags);
 265   }
 266
 267   return I;
 268 }
 269
 270 Expected<MaterializationUnit::Interface>
 271 getObjectFileInterface(ExecutionSession &ES, MemoryBufferRef ObjBuffer) {
 272   auto Obj = object::ObjectFile::createObjectFile(ObjBuffer);
 273
 274   if (!Obj)
 275     return Obj.takeError();
 276
 277   if (auto *MachOObj = dyn_cast<object::MachOObjectFile>(Obj->get()))
 278     return getMachOObjectFileSymbolInfo(ES, *MachOObj);
 279   else if (auto *ELFObj = dyn_cast<object::ELFObjectFileBase>(Obj->get()))
 280     return getELFObjectFileSymbolInfo(ES, *ELFObj);
 281   else if (auto *COFFObj = dyn_cast<object::COFFObjectFile>(Obj->get()))
 282     return getCOFFObjectFileSymbolInfo(ES, *COFFObj);
 283
 284   return getGenericObjectFileSymbolInfo(ES, **Obj);
 285 }
 286
 287 } // End namespace orc.
 288 } // End namespace llvm.