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/MC/MCAsmInfo.h"
  12 #include "llvm/MC/MCSectionMachO.h"
  13 #include "llvm/MC/MCSectionELF.h"
  14 #include "llvm/MC/MCSectionCOFF.h"
  15 #include "llvm/MC/MCSymbol.h"
  16 #include "llvm/MC/MCLabel.h"
  17 #include "llvm/MC/MCDwarf.h"
  18 #include "llvm/Target/TargetAsmInfo.h"
  19 #include "llvm/ADT/SmallString.h"
  20 #include "llvm/ADT/Twine.h"
  21 #include "llvm/Support/ELF.h"
  22 using namespace llvm;
  23
  24 typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy;
  25 typedef StringMap<const MCSectionELF*> ELFUniqueMapTy;
  26 typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy;
  27
  28
  29 MCContext::MCContext(const MCAsmInfo &mai, const TargetAsmInfo *tai) :
  30   MAI(mai), TAI(tai), NextUniqueID(0),
  31   CurrentDwarfLoc(0,0,0,DWARF2_FLAG_IS_STMT,0,0),
  32   AllowTemporaryLabels(true) {
  33   MachOUniquingMap = 0;
  34   ELFUniquingMap = 0;
  35   COFFUniquingMap = 0;
  36
  37   SecureLogFile = getenv("AS_SECURE_LOG_FILE");
  38   SecureLog = 0;
  39   SecureLogUsed = false;
  40
  41   DwarfLocSeen = false;
  42 }
  43
  44 MCContext::~MCContext() {
  45   // NOTE: The symbols are all allocated out of a bump pointer allocator,
  46   // we don't need to free them here.
  47
  48   // If we have the MachO uniquing map, free it.
  49   delete (MachOUniqueMapTy*)MachOUniquingMap;
  50   delete (ELFUniqueMapTy*)ELFUniquingMap;
  51   delete (COFFUniqueMapTy*)COFFUniquingMap;
  52
  53   // If the stream for the .secure_log_unique directive was created free it.
  54   delete (raw_ostream*)SecureLog;
  55
  56   delete TAI;
  57 }
  58
  59 //===----------------------------------------------------------------------===//
  60 // Symbol Manipulation
  61 //===----------------------------------------------------------------------===//
  62
  63 MCSymbol *MCContext::GetOrCreateSymbol(StringRef Name) {
  64   assert(!Name.empty() && "Normal symbols cannot be unnamed!");
  65
  66   // Do the lookup and get the entire StringMapEntry.  We want access to the
  67   // key if we are creating the entry.
  68   StringMapEntry<MCSymbol*> &Entry = Symbols.GetOrCreateValue(Name);
  69   MCSymbol *Sym = Entry.getValue();
  70
  71   if (Sym)
  72     return Sym;
  73
  74   Sym = CreateSymbol(Name);
  75   Entry.setValue(Sym);
  76   return Sym;
  77 }
  78
  79 MCSymbol *MCContext::CreateSymbol(StringRef Name) {
  80   // Determine whether this is an assembler temporary or normal label, if used.
  81   bool isTemporary = false;
  82   if (AllowTemporaryLabels)
  83     isTemporary = Name.startswith(MAI.getPrivateGlobalPrefix());
  84
  85   StringMapEntry<bool> *NameEntry = &UsedNames.GetOrCreateValue(Name);
  86   if (NameEntry->getValue()) {
  87     assert(isTemporary && "Cannot rename non temporary symbols");
  88     SmallString<128> NewName = Name;
  89     do {
  90       NewName.resize(Name.size());
  91       raw_svector_ostream(NewName) << NextUniqueID++;
  92       NameEntry = &UsedNames.GetOrCreateValue(NewName);
  93     } while (NameEntry->getValue());
  94   }
  95   NameEntry->setValue(true);
  96
  97   // Ok, the entry doesn't already exist.  Have the MCSymbol object itself refer
  98   // to the copy of the string that is embedded in the UsedNames entry.
  99   MCSymbol *Result = new (*this) MCSymbol(NameEntry->getKey(), isTemporary);
 100
 101   return Result;
 102 }
 103
 104 MCSymbol *MCContext::GetOrCreateSymbol(const Twine &Name) {
 105   SmallString<128> NameSV;
 106   Name.toVector(NameSV);
 107   return GetOrCreateSymbol(NameSV.str());
 108 }
 109
 110 MCSymbol *MCContext::CreateTempSymbol() {
 111   SmallString<128> NameSV;
 112   raw_svector_ostream(NameSV)
 113     << MAI.getPrivateGlobalPrefix() << "tmp" << NextUniqueID++;
 114   return CreateSymbol(NameSV);
 115 }
 116
 117 unsigned MCContext::NextInstance(int64_t LocalLabelVal) {
 118   MCLabel *&Label = Instances[LocalLabelVal];
 119   if (!Label)
 120     Label = new (*this) MCLabel(0);
 121   return Label->incInstance();
 122 }
 123
 124 unsigned MCContext::GetInstance(int64_t LocalLabelVal) {
 125   MCLabel *&Label = Instances[LocalLabelVal];
 126   if (!Label)
 127     Label = new (*this) MCLabel(0);
 128   return Label->getInstance();
 129 }
 130
 131 MCSymbol *MCContext::CreateDirectionalLocalSymbol(int64_t LocalLabelVal) {
 132   return GetOrCreateSymbol(Twine(MAI.getPrivateGlobalPrefix()) +
 133                            Twine(LocalLabelVal) +
 134                            "\2" +
 135                            Twine(NextInstance(LocalLabelVal)));
 136 }
 137 MCSymbol *MCContext::GetDirectionalLocalSymbol(int64_t LocalLabelVal,
 138                                                int bORf) {
 139   return GetOrCreateSymbol(Twine(MAI.getPrivateGlobalPrefix()) +
 140                            Twine(LocalLabelVal) +
 141                            "\2" +
 142                            Twine(GetInstance(LocalLabelVal) + bORf));
 143 }
 144
 145 MCSymbol *MCContext::LookupSymbol(StringRef Name) const {
 146   return Symbols.lookup(Name);
 147 }
 148
 149 //===----------------------------------------------------------------------===//
 150 // Section Management
 151 //===----------------------------------------------------------------------===//
 152
 153 const MCSectionMachO *MCContext::
 154 getMachOSection(StringRef Segment, StringRef Section,
 155                 unsigned TypeAndAttributes,
 156                 unsigned Reserved2, SectionKind Kind) {
 157
 158   // We unique sections by their segment/section pair.  The returned section
 159   // may not have the same flags as the requested section, if so this should be
 160   // diagnosed by the client as an error.
 161
 162   // Create the map if it doesn't already exist.
 163   if (MachOUniquingMap == 0)
 164     MachOUniquingMap = new MachOUniqueMapTy();
 165   MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)MachOUniquingMap;
 166
 167   // Form the name to look up.
 168   SmallString<64> Name;
 169   Name += Segment;
 170   Name.push_back(',');
 171   Name += Section;
 172
 173   // Do the lookup, if we have a hit, return it.
 174   const MCSectionMachO *&Entry = Map[Name.str()];
 175   if (Entry) return Entry;
 176
 177   // Otherwise, return a new section.
 178   return Entry = new (*this) MCSectionMachO(Segment, Section, TypeAndAttributes,
 179                                             Reserved2, Kind);
 180 }
 181
 182 const MCSectionELF *MCContext::
 183 getELFSection(StringRef Section, unsigned Type, unsigned Flags,
 184               SectionKind Kind) {
 185   return getELFSection(Section, Type, Flags, Kind, 0, "");
 186 }
 187
 188 const MCSectionELF *MCContext::
 189 getELFSection(StringRef Section, unsigned Type, unsigned Flags,
 190               SectionKind Kind, unsigned EntrySize, StringRef Group) {
 191   if (ELFUniquingMap == 0)
 192     ELFUniquingMap = new ELFUniqueMapTy();
 193   ELFUniqueMapTy &Map = *(ELFUniqueMapTy*)ELFUniquingMap;
 194
 195   // Do the lookup, if we have a hit, return it.
 196   StringMapEntry<const MCSectionELF*> &Entry = Map.GetOrCreateValue(Section);
 197   if (Entry.getValue()) return Entry.getValue();
 198
 199   // Possibly refine the entry size first.
 200   if (!EntrySize) {
 201     EntrySize = MCSectionELF::DetermineEntrySize(Kind);
 202   }
 203
 204   MCSymbol *GroupSym = NULL;
 205   if (!Group.empty())
 206     GroupSym = GetOrCreateSymbol(Group);
 207
 208   MCSectionELF *Result = new (*this) MCSectionELF(Entry.getKey(), Type, Flags,
 209                                                   Kind, EntrySize, GroupSym);
 210   Entry.setValue(Result);
 211   return Result;
 212 }
 213
 214 const MCSectionELF *MCContext::CreateELFGroupSection() {
 215   MCSectionELF *Result =
 216     new (*this) MCSectionELF(".group", ELF::SHT_GROUP, 0,
 217                              SectionKind::getReadOnly(), 4, NULL);
 218   return Result;
 219 }
 220
 221 const MCSection *MCContext::getCOFFSection(StringRef Section,
 222                                            unsigned Characteristics,
 223                                            int Selection,
 224                                            SectionKind Kind) {
 225   if (COFFUniquingMap == 0)
 226     COFFUniquingMap = new COFFUniqueMapTy();
 227   COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)COFFUniquingMap;
 228
 229   // Do the lookup, if we have a hit, return it.
 230   StringMapEntry<const MCSectionCOFF*> &Entry = Map.GetOrCreateValue(Section);
 231   if (Entry.getValue()) return Entry.getValue();
 232
 233   MCSectionCOFF *Result = new (*this) MCSectionCOFF(Entry.getKey(),
 234                                                     Characteristics,
 235                                                     Selection, Kind);
 236
 237   Entry.setValue(Result);
 238   return Result;
 239 }
 240
 241 //===----------------------------------------------------------------------===//
 242 // Dwarf Management
 243 //===----------------------------------------------------------------------===//
 244
 245 /// GetDwarfFile - takes a file name an number to place in the dwarf file and
 246 /// directory tables.  If the file number has already been allocated it is an
 247 /// error and zero is returned and the client reports the error, else the
 248 /// allocated file number is returned.  The file numbers may be in any order.
 249 unsigned MCContext::GetDwarfFile(StringRef FileName, unsigned FileNumber) {
 250   // TODO: a FileNumber of zero says to use the next available file number.
 251   // Note: in GenericAsmParser::ParseDirectiveFile() FileNumber was checked
 252   // to not be less than one.  This needs to be change to be not less than zero.
 253
 254   // Make space for this FileNumber in the MCDwarfFiles vector if needed.
 255   if (FileNumber >= MCDwarfFiles.size()) {
 256     MCDwarfFiles.resize(FileNumber + 1);
 257   } else {
 258     MCDwarfFile *&ExistingFile = MCDwarfFiles[FileNumber];
 259     if (ExistingFile)
 260       // It is an error to use see the same number more than once.
 261       return 0;
 262   }
 263
 264   // Get the new MCDwarfFile slot for this FileNumber.
 265   MCDwarfFile *&File = MCDwarfFiles[FileNumber];
 266
 267   // Separate the directory part from the basename of the FileName.
 268   std::pair<StringRef, StringRef> Slash = FileName.rsplit('/');
 269
 270   // Find or make a entry in the MCDwarfDirs vector for this Directory.
 271   StringRef Name;
 272   unsigned DirIndex;
 273   // Capture directory name.
 274   if (Slash.second.empty()) {
 275     Name = Slash.first;
 276     DirIndex = 0; // For FileNames with no directories a DirIndex of 0 is used.
 277   } else {
 278     StringRef Directory = Slash.first;
 279     Name = Slash.second;
 280     for (DirIndex = 0; DirIndex < MCDwarfDirs.size(); DirIndex++) {
 281       if (Directory == MCDwarfDirs[DirIndex])
 282         break;
 283     }
 284     if (DirIndex >= MCDwarfDirs.size()) {
 285       char *Buf = static_cast<char *>(Allocate(Directory.size()));
 286       memcpy(Buf, Directory.data(), Directory.size());
 287       MCDwarfDirs.push_back(StringRef(Buf, Directory.size()));
 288     }
 289     // The DirIndex is one based, as DirIndex of 0 is used for FileNames with
 290     // no directories.  MCDwarfDirs[] is unlike MCDwarfFiles[] in that the
 291     // directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames are
 292     // stored at MCDwarfFiles[FileNumber].Name .
 293     DirIndex++;
 294   }
 295
 296   // Now make the MCDwarfFile entry and place it in the slot in the MCDwarfFiles
 297   // vector.
 298   char *Buf = static_cast<char *>(Allocate(Name.size()));
 299   memcpy(Buf, Name.data(), Name.size());
 300   File = new (*this) MCDwarfFile(StringRef(Buf, Name.size()), DirIndex);
 301
 302   // return the allocated FileNumber.
 303   return FileNumber;
 304 }
 305
 306 /// isValidDwarfFileNumber - takes a dwarf file number and returns true if it
 307 /// currently is assigned and false otherwise.
 308 bool MCContext::isValidDwarfFileNumber(unsigned FileNumber) {
 309   if(FileNumber == 0 || FileNumber >= MCDwarfFiles.size())
 310     return false;
 311
 312   return MCDwarfFiles[FileNumber] != 0;
 313 }