1 //===- lib/MC/MCContext.cpp - Machine Code Context ------------------------===// 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 #include "llvm/MC/MCContext.h" 11 #include "llvm/ADT/SmallString.h" 12 #include "llvm/ADT/Twine.h" 13 #include "llvm/MC/MCAsmInfo.h" 14 #include "llvm/MC/MCDwarf.h" 15 #include "llvm/MC/MCLabel.h" 16 #include "llvm/MC/MCObjectFileInfo.h" 17 #include "llvm/MC/MCRegisterInfo.h" 18 #include "llvm/MC/MCSectionCOFF.h" 19 #include "llvm/MC/MCSectionELF.h" 20 #include "llvm/MC/MCSectionMachO.h" 21 #include "llvm/MC/MCStreamer.h" 22 #include "llvm/MC/MCSymbol.h" 23 #include "llvm/Support/ELF.h" 24 #include "llvm/Support/ErrorHandling.h" 25 #include "llvm/Support/FileSystem.h" 26 #include "llvm/Support/MemoryBuffer.h" 27 #include "llvm/Support/Signals.h" 28 #include "llvm/Support/SourceMgr.h" 29 #include <map> 30 31 using namespace llvm; 32 33 MCContext::MCContext(const MCAsmInfo *mai, const MCRegisterInfo *mri, 34 const MCObjectFileInfo *mofi, const SourceMgr *mgr, 35 bool DoAutoReset) 36 : SrcMgr(mgr), MAI(mai), MRI(mri), MOFI(mofi), Allocator(), 37 Symbols(Allocator), UsedNames(Allocator), 38 CurrentDwarfLoc(0, 0, 0, DWARF2_FLAG_IS_STMT, 0, 0), DwarfLocSeen(false), 39 GenDwarfForAssembly(false), GenDwarfFileNumber(0), DwarfVersion(4), 40 AllowTemporaryLabels(true), DwarfCompileUnitID(0), 41 AutoReset(DoAutoReset) { 42 43 std::error_code EC = llvm::sys::fs::current_path(CompilationDir); 44 if (EC) 45 CompilationDir.clear(); 46 47 SecureLogFile = getenv("AS_SECURE_LOG_FILE"); 48 SecureLog = nullptr; 49 SecureLogUsed = false; 50 51 if (SrcMgr && SrcMgr->getNumBuffers()) 52 MainFileName = 53 SrcMgr->getMemoryBuffer(SrcMgr->getMainFileID())->getBufferIdentifier(); 54 } 55 56 MCContext::~MCContext() { 57 58 if (AutoReset) 59 reset(); 60 61 // NOTE: The symbols are all allocated out of a bump pointer allocator, 62 // we don't need to free them here. 63 64 // If the stream for the .secure_log_unique directive was created free it. 65 delete (raw_ostream*)SecureLog; 66 } 67 68 //===----------------------------------------------------------------------===// 69 // Module Lifetime Management 70 //===----------------------------------------------------------------------===// 71 72 void MCContext::reset() { 73 UsedNames.clear(); 74 Symbols.clear(); 75 Allocator.Reset(); 76 Instances.clear(); 77 CompilationDir.clear(); 78 MainFileName.clear(); 79 MCDwarfLineTablesCUMap.clear(); 80 SectionStartEndSyms.clear(); 81 MCGenDwarfLabelEntries.clear(); 82 DwarfDebugFlags = StringRef(); 83 DwarfCompileUnitID = 0; 84 CurrentDwarfLoc = MCDwarfLoc(0,0,0,DWARF2_FLAG_IS_STMT,0,0); 85 86 MachOUniquingMap.clear(); 87 ELFUniquingMap.clear(); 88 COFFUniquingMap.clear(); 89 90 NextID.clear(); 91 AllowTemporaryLabels = true; 92 DwarfLocSeen = false; 93 GenDwarfForAssembly = false; 94 GenDwarfFileNumber = 0; 95 } 96 97 //===----------------------------------------------------------------------===// 98 // Symbol Manipulation 99 //===----------------------------------------------------------------------===// 100 101 MCSymbol *MCContext::GetOrCreateSymbol(const Twine &Name) { 102 SmallString<128> NameSV; 103 StringRef NameRef = Name.toStringRef(NameSV); 104 105 assert(!NameRef.empty() && "Normal symbols cannot be unnamed!"); 106 107 MCSymbol *&Sym = Symbols[NameRef]; 108 if (!Sym) 109 Sym = CreateSymbol(NameRef, false); 110 111 return Sym; 112 } 113 114 MCSymbol *MCContext::getOrCreateSectionSymbol(const MCSectionELF &Section) { 115 MCSymbol *&Sym = SectionSymbols[&Section]; 116 if (Sym) 117 return Sym; 118 119 StringRef Name = Section.getSectionName(); 120 121 MCSymbol *&OldSym = Symbols[Name]; 122 if (OldSym && OldSym->isUndefined()) { 123 Sym = OldSym; 124 return OldSym; 125 } 126 127 auto NameIter = UsedNames.insert(std::make_pair(Name, true)).first; 128 Sym = new (*this) MCSymbol(NameIter->getKey(), /*isTemporary*/ false); 129 130 if (!OldSym) 131 OldSym = Sym; 132 133 return Sym; 134 } 135 136 MCSymbol *MCContext::getOrCreateFrameAllocSymbol(StringRef FuncName, 137 unsigned Idx) { 138 return GetOrCreateSymbol(Twine(MAI->getPrivateGlobalPrefix()) + FuncName + 139 "$frame_escape_" + Twine(Idx)); 140 } 141 142 MCSymbol *MCContext::getOrCreateParentFrameOffsetSymbol(StringRef FuncName) { 143 return GetOrCreateSymbol(Twine(MAI->getPrivateGlobalPrefix()) + FuncName + 144 "$parent_frame_offset"); 145 } 146 147 MCSymbol *MCContext::CreateSymbol(StringRef Name, bool AlwaysAddSuffix) { 148 // Determine whether this is an assembler temporary or normal label, if used. 149 bool IsTemporary = false; 150 if (AllowTemporaryLabels) 151 IsTemporary = Name.startswith(MAI->getPrivateGlobalPrefix()); 152 153 SmallString<128> NewName = Name; 154 bool AddSuffix = AlwaysAddSuffix; 155 unsigned &NextUniqueID = NextID[Name]; 156 for (;;) { 157 if (AddSuffix) { 158 NewName.resize(Name.size()); 159 raw_svector_ostream(NewName) << NextUniqueID++; 160 } 161 auto NameEntry = UsedNames.insert(std::make_pair(NewName, true)); 162 if (NameEntry.second) { 163 // Ok, we found a name. Have the MCSymbol object itself refer to the copy 164 // of the string that is embedded in the UsedNames entry. 165 MCSymbol *Result = 166 new (*this) MCSymbol(NameEntry.first->getKey(), IsTemporary); 167 return Result; 168 } 169 assert(IsTemporary && "Cannot rename non-temporary symbols"); 170 AddSuffix = true; 171 } 172 llvm_unreachable("Infinite loop"); 173 } 174 175 MCSymbol *MCContext::createTempSymbol(const Twine &Name, bool AlwaysAddSuffix) { 176 SmallString<128> NameSV; 177 raw_svector_ostream(NameSV) << MAI->getPrivateGlobalPrefix() << Name; 178 return CreateSymbol(NameSV, AlwaysAddSuffix); 179 } 180 181 MCSymbol *MCContext::CreateLinkerPrivateTempSymbol() { 182 SmallString<128> NameSV; 183 raw_svector_ostream(NameSV) << MAI->getLinkerPrivateGlobalPrefix() << "tmp"; 184 return CreateSymbol(NameSV, true); 185 } 186 187 MCSymbol *MCContext::CreateTempSymbol() { 188 return createTempSymbol("tmp", true); 189 } 190 191 unsigned MCContext::NextInstance(unsigned LocalLabelVal) { 192 MCLabel *&Label = Instances[LocalLabelVal]; 193 if (!Label) 194 Label = new (*this) MCLabel(0); 195 return Label->incInstance(); 196 } 197 198 unsigned MCContext::GetInstance(unsigned LocalLabelVal) { 199 MCLabel *&Label = Instances[LocalLabelVal]; 200 if (!Label) 201 Label = new (*this) MCLabel(0); 202 return Label->getInstance(); 203 } 204 205 MCSymbol *MCContext::getOrCreateDirectionalLocalSymbol(unsigned LocalLabelVal, 206 unsigned Instance) { 207 MCSymbol *&Sym = LocalSymbols[std::make_pair(LocalLabelVal, Instance)]; 208 if (!Sym) 209 Sym = CreateTempSymbol(); 210 return Sym; 211 } 212 213 MCSymbol *MCContext::CreateDirectionalLocalSymbol(unsigned LocalLabelVal) { 214 unsigned Instance = NextInstance(LocalLabelVal); 215 return getOrCreateDirectionalLocalSymbol(LocalLabelVal, Instance); 216 } 217 218 MCSymbol *MCContext::GetDirectionalLocalSymbol(unsigned LocalLabelVal, 219 bool Before) { 220 unsigned Instance = GetInstance(LocalLabelVal); 221 if (!Before) 222 ++Instance; 223 return getOrCreateDirectionalLocalSymbol(LocalLabelVal, Instance); 224 } 225 226 MCSymbol *MCContext::LookupSymbol(const Twine &Name) const { 227 SmallString<128> NameSV; 228 StringRef NameRef = Name.toStringRef(NameSV); 229 return Symbols.lookup(NameRef); 230 } 231 232 //===----------------------------------------------------------------------===// 233 // Section Management 234 //===----------------------------------------------------------------------===// 235 236 const MCSectionMachO * 237 MCContext::getMachOSection(StringRef Segment, StringRef Section, 238 unsigned TypeAndAttributes, unsigned Reserved2, 239 SectionKind Kind, const char *BeginSymName) { 240 241 // We unique sections by their segment/section pair. The returned section 242 // may not have the same flags as the requested section, if so this should be 243 // diagnosed by the client as an error. 244 245 // Form the name to look up. 246 SmallString<64> Name; 247 Name += Segment; 248 Name.push_back(','); 249 Name += Section; 250 251 // Do the lookup, if we have a hit, return it. 252 const MCSectionMachO *&Entry = MachOUniquingMap[Name]; 253 if (Entry) 254 return Entry; 255 256 MCSymbol *Begin = nullptr; 257 if (BeginSymName) 258 Begin = createTempSymbol(BeginSymName, false); 259 260 // Otherwise, return a new section. 261 return Entry = new (*this) MCSectionMachO(Segment, Section, TypeAndAttributes, 262 Reserved2, Kind, Begin); 263 } 264 265 void MCContext::renameELFSection(const MCSectionELF *Section, StringRef Name) { 266 StringRef GroupName; 267 if (const MCSymbol *Group = Section->getGroup()) 268 GroupName = Group->getName(); 269 270 unsigned UniqueID = Section->getUniqueID(); 271 ELFUniquingMap.erase( 272 ELFSectionKey{Section->getSectionName(), GroupName, UniqueID}); 273 auto I = ELFUniquingMap.insert(std::make_pair( 274 ELFSectionKey{Name, GroupName, UniqueID}, 275 Section)).first; 276 StringRef CachedName = I->first.SectionName; 277 const_cast<MCSectionELF*>(Section)->setSectionName(CachedName); 278 } 279 280 const MCSectionELF * 281 MCContext::createELFRelSection(StringRef Name, unsigned Type, unsigned Flags, 282 unsigned EntrySize, const MCSymbol *Group, 283 const MCSectionELF *Associated) { 284 StringMap<bool>::iterator I; 285 bool Inserted; 286 std::tie(I, Inserted) = ELFRelSecNames.insert(std::make_pair(Name, true)); 287 288 return new (*this) 289 MCSectionELF(I->getKey(), Type, Flags, SectionKind::getReadOnly(), 290 EntrySize, Group, true, nullptr, Associated); 291 } 292 293 const MCSectionELF *MCContext::getELFSection(StringRef Section, unsigned Type, 294 unsigned Flags, unsigned EntrySize, 295 StringRef Group, unsigned UniqueID, 296 const char *BeginSymName) { 297 MCSymbol *GroupSym = nullptr; 298 if (!Group.empty()) 299 GroupSym = GetOrCreateSymbol(Group); 300 301 return getELFSection(Section, Type, Flags, EntrySize, GroupSym, UniqueID, 302 BeginSymName, nullptr); 303 } 304 305 const MCSectionELF *MCContext::getELFSection(StringRef Section, unsigned Type, 306 unsigned Flags, unsigned EntrySize, 307 const MCSymbol *GroupSym, 308 unsigned UniqueID, 309 const char *BeginSymName, 310 const MCSectionELF *Associated) { 311 StringRef Group = ""; 312 if (GroupSym) 313 Group = GroupSym->getName(); 314 // Do the lookup, if we have a hit, return it. 315 auto IterBool = ELFUniquingMap.insert( 316 std::make_pair(ELFSectionKey{Section, Group, UniqueID}, nullptr)); 317 auto &Entry = *IterBool.first; 318 if (!IterBool.second) 319 return Entry.second; 320 321 StringRef CachedName = Entry.first.SectionName; 322 323 SectionKind Kind; 324 if (Flags & ELF::SHF_EXECINSTR) 325 Kind = SectionKind::getText(); 326 else 327 Kind = SectionKind::getReadOnly(); 328 329 MCSymbol *Begin = nullptr; 330 if (BeginSymName) 331 Begin = createTempSymbol(BeginSymName, false); 332 333 MCSectionELF *Result = 334 new (*this) MCSectionELF(CachedName, Type, Flags, Kind, EntrySize, 335 GroupSym, UniqueID, Begin, Associated); 336 Entry.second = Result; 337 return Result; 338 } 339 340 const MCSectionELF *MCContext::CreateELFGroupSection() { 341 MCSectionELF *Result = new (*this) 342 MCSectionELF(".group", ELF::SHT_GROUP, 0, SectionKind::getReadOnly(), 4, 343 nullptr, ~0, nullptr, nullptr); 344 return Result; 345 } 346 347 const MCSectionCOFF * 348 MCContext::getCOFFSection(StringRef Section, unsigned Characteristics, 349 SectionKind Kind, StringRef COMDATSymName, 350 int Selection, const char *BeginSymName) { 351 MCSymbol *COMDATSymbol = nullptr; 352 if (!COMDATSymName.empty()) { 353 COMDATSymbol = GetOrCreateSymbol(COMDATSymName); 354 COMDATSymName = COMDATSymbol->getName(); 355 } 356 357 // Do the lookup, if we have a hit, return it. 358 COFFSectionKey T{Section, COMDATSymName, Selection}; 359 auto IterBool = COFFUniquingMap.insert(std::make_pair(T, nullptr)); 360 auto Iter = IterBool.first; 361 if (!IterBool.second) 362 return Iter->second; 363 364 MCSymbol *Begin = nullptr; 365 if (BeginSymName) 366 Begin = createTempSymbol(BeginSymName, false); 367 368 StringRef CachedName = Iter->first.SectionName; 369 MCSectionCOFF *Result = new (*this) MCSectionCOFF( 370 CachedName, Characteristics, COMDATSymbol, Selection, Kind, Begin); 371 372 Iter->second = Result; 373 return Result; 374 } 375 376 const MCSectionCOFF *MCContext::getCOFFSection(StringRef Section, 377 unsigned Characteristics, 378 SectionKind Kind, 379 const char *BeginSymName) { 380 return getCOFFSection(Section, Characteristics, Kind, "", 0, BeginSymName); 381 } 382 383 const MCSectionCOFF *MCContext::getCOFFSection(StringRef Section) { 384 COFFSectionKey T{Section, "", 0}; 385 auto Iter = COFFUniquingMap.find(T); 386 if (Iter == COFFUniquingMap.end()) 387 return nullptr; 388 return Iter->second; 389 } 390 391 const MCSectionCOFF * 392 MCContext::getAssociativeCOFFSection(const MCSectionCOFF *Sec, 393 const MCSymbol *KeySym) { 394 // Return the normal section if we don't have to be associative. 395 if (!KeySym) 396 return Sec; 397 398 // Make an associative section with the same name and kind as the normal 399 // section. 400 unsigned Characteristics = 401 Sec->getCharacteristics() | COFF::IMAGE_SCN_LNK_COMDAT; 402 return getCOFFSection(Sec->getSectionName(), Characteristics, Sec->getKind(), 403 KeySym->getName(), 404 COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE); 405 } 406 407 //===----------------------------------------------------------------------===// 408 // Dwarf Management 409 //===----------------------------------------------------------------------===// 410 411 /// GetDwarfFile - takes a file name an number to place in the dwarf file and 412 /// directory tables. If the file number has already been allocated it is an 413 /// error and zero is returned and the client reports the error, else the 414 /// allocated file number is returned. The file numbers may be in any order. 415 unsigned MCContext::GetDwarfFile(StringRef Directory, StringRef FileName, 416 unsigned FileNumber, unsigned CUID) { 417 MCDwarfLineTable &Table = MCDwarfLineTablesCUMap[CUID]; 418 return Table.getFile(Directory, FileName, FileNumber); 419 } 420 421 /// isValidDwarfFileNumber - takes a dwarf file number and returns true if it 422 /// currently is assigned and false otherwise. 423 bool MCContext::isValidDwarfFileNumber(unsigned FileNumber, unsigned CUID) { 424 const SmallVectorImpl<MCDwarfFile>& MCDwarfFiles = getMCDwarfFiles(CUID); 425 if(FileNumber == 0 || FileNumber >= MCDwarfFiles.size()) 426 return false; 427 428 return !MCDwarfFiles[FileNumber].Name.empty(); 429 } 430 431 /// finalizeDwarfSections - Emit end symbols for each non-empty code section. 432 /// Also remove empty sections from SectionStartEndSyms, to avoid generating 433 /// useless debug info for them. 434 void MCContext::finalizeDwarfSections(MCStreamer &MCOS) { 435 MCContext &context = MCOS.getContext(); 436 437 auto sec = SectionStartEndSyms.begin(); 438 while (sec != SectionStartEndSyms.end()) { 439 assert(sec->second.first && "Start symbol must be set by now"); 440 MCOS.SwitchSection(sec->first); 441 if (MCOS.mayHaveInstructions()) { 442 MCSymbol *SectionEndSym = context.CreateTempSymbol(); 443 MCOS.EmitLabel(SectionEndSym); 444 sec->second.second = SectionEndSym; 445 ++sec; 446 } else { 447 MapVector<const MCSection *, std::pair<MCSymbol *, MCSymbol *> >::iterator 448 to_erase = sec; 449 sec = SectionStartEndSyms.erase(to_erase); 450 } 451 } 452 } 453 454 void MCContext::FatalError(SMLoc Loc, const Twine &Msg) const { 455 // If we have a source manager and a location, use it. Otherwise just 456 // use the generic report_fatal_error(). 457 if (!SrcMgr || Loc == SMLoc()) 458 report_fatal_error(Msg, false); 459 460 // Use the source manager to print the message. 461 SrcMgr->PrintMessage(Loc, SourceMgr::DK_Error, Msg); 462 463 // If we reached here, we are failing ungracefully. Run the interrupt handlers 464 // to make sure any special cleanups get done, in particular that we remove 465 // files registered with RemoveFileOnSignal. 466 sys::RunInterruptHandlers(); 467 exit(1); 468 } 469