src/llvm/lib/MC/MCContext.cpp

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